LCOV - code coverage report
Current view: top level - drivers/char - random.c (source / functions) Hit Total Coverage
Test: combined.info Lines: 571 757 75.4 %
Date: 2022-04-01 14:17:54 Functions: 43 57 75.4 %
Branches: 177 352 50.3 %

           Branch data     Line data    Source code
       1                 :            : /*
       2                 :            :  * random.c -- A strong random number generator
       3                 :            :  *
       4                 :            :  * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All
       5                 :            :  * Rights Reserved.
       6                 :            :  *
       7                 :            :  * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
       8                 :            :  *
       9                 :            :  * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999.  All
      10                 :            :  * rights reserved.
      11                 :            :  *
      12                 :            :  * Redistribution and use in source and binary forms, with or without
      13                 :            :  * modification, are permitted provided that the following conditions
      14                 :            :  * are met:
      15                 :            :  * 1. Redistributions of source code must retain the above copyright
      16                 :            :  *    notice, and the entire permission notice in its entirety,
      17                 :            :  *    including the disclaimer of warranties.
      18                 :            :  * 2. Redistributions in binary form must reproduce the above copyright
      19                 :            :  *    notice, this list of conditions and the following disclaimer in the
      20                 :            :  *    documentation and/or other materials provided with the distribution.
      21                 :            :  * 3. The name of the author may not be used to endorse or promote
      22                 :            :  *    products derived from this software without specific prior
      23                 :            :  *    written permission.
      24                 :            :  *
      25                 :            :  * ALTERNATIVELY, this product may be distributed under the terms of
      26                 :            :  * the GNU General Public License, in which case the provisions of the GPL are
      27                 :            :  * required INSTEAD OF the above restrictions.  (This clause is
      28                 :            :  * necessary due to a potential bad interaction between the GPL and
      29                 :            :  * the restrictions contained in a BSD-style copyright.)
      30                 :            :  *
      31                 :            :  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
      32                 :            :  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
      33                 :            :  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
      34                 :            :  * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
      35                 :            :  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
      36                 :            :  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
      37                 :            :  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
      38                 :            :  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
      39                 :            :  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      40                 :            :  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
      41                 :            :  * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
      42                 :            :  * DAMAGE.
      43                 :            :  */
      44                 :            : 
      45                 :            : /*
      46                 :            :  * (now, with legal B.S. out of the way.....)
      47                 :            :  *
      48                 :            :  * This routine gathers environmental noise from device drivers, etc.,
      49                 :            :  * and returns good random numbers, suitable for cryptographic use.
      50                 :            :  * Besides the obvious cryptographic uses, these numbers are also good
      51                 :            :  * for seeding TCP sequence numbers, and other places where it is
      52                 :            :  * desirable to have numbers which are not only random, but hard to
      53                 :            :  * predict by an attacker.
      54                 :            :  *
      55                 :            :  * Theory of operation
      56                 :            :  * ===================
      57                 :            :  *
      58                 :            :  * Computers are very predictable devices.  Hence it is extremely hard
      59                 :            :  * to produce truly random numbers on a computer --- as opposed to
      60                 :            :  * pseudo-random numbers, which can easily generated by using a
      61                 :            :  * algorithm.  Unfortunately, it is very easy for attackers to guess
      62                 :            :  * the sequence of pseudo-random number generators, and for some
      63                 :            :  * applications this is not acceptable.  So instead, we must try to
      64                 :            :  * gather "environmental noise" from the computer's environment, which
      65                 :            :  * must be hard for outside attackers to observe, and use that to
      66                 :            :  * generate random numbers.  In a Unix environment, this is best done
      67                 :            :  * from inside the kernel.
      68                 :            :  *
      69                 :            :  * Sources of randomness from the environment include inter-keyboard
      70                 :            :  * timings, inter-interrupt timings from some interrupts, and other
      71                 :            :  * events which are both (a) non-deterministic and (b) hard for an
      72                 :            :  * outside observer to measure.  Randomness from these sources are
      73                 :            :  * added to an "entropy pool", which is mixed using a CRC-like function.
      74                 :            :  * This is not cryptographically strong, but it is adequate assuming
      75                 :            :  * the randomness is not chosen maliciously, and it is fast enough that
      76                 :            :  * the overhead of doing it on every interrupt is very reasonable.
      77                 :            :  * As random bytes are mixed into the entropy pool, the routines keep
      78                 :            :  * an *estimate* of how many bits of randomness have been stored into
      79                 :            :  * the random number generator's internal state.
      80                 :            :  *
      81                 :            :  * When random bytes are desired, they are obtained by taking the SHA
      82                 :            :  * hash of the contents of the "entropy pool".  The SHA hash avoids
      83                 :            :  * exposing the internal state of the entropy pool.  It is believed to
      84                 :            :  * be computationally infeasible to derive any useful information
      85                 :            :  * about the input of SHA from its output.  Even if it is possible to
      86                 :            :  * analyze SHA in some clever way, as long as the amount of data
      87                 :            :  * returned from the generator is less than the inherent entropy in
      88                 :            :  * the pool, the output data is totally unpredictable.  For this
      89                 :            :  * reason, the routine decreases its internal estimate of how many
      90                 :            :  * bits of "true randomness" are contained in the entropy pool as it
      91                 :            :  * outputs random numbers.
      92                 :            :  *
      93                 :            :  * If this estimate goes to zero, the routine can still generate
      94                 :            :  * random numbers; however, an attacker may (at least in theory) be
      95                 :            :  * able to infer the future output of the generator from prior
      96                 :            :  * outputs.  This requires successful cryptanalysis of SHA, which is
      97                 :            :  * not believed to be feasible, but there is a remote possibility.
      98                 :            :  * Nonetheless, these numbers should be useful for the vast majority
      99                 :            :  * of purposes.
     100                 :            :  *
     101                 :            :  * Exported interfaces ---- output
     102                 :            :  * ===============================
     103                 :            :  *
     104                 :            :  * There are four exported interfaces; two for use within the kernel,
     105                 :            :  * and two or use from userspace.
     106                 :            :  *
     107                 :            :  * Exported interfaces ---- userspace output
     108                 :            :  * -----------------------------------------
     109                 :            :  *
     110                 :            :  * The userspace interfaces are two character devices /dev/random and
     111                 :            :  * /dev/urandom.  /dev/random is suitable for use when very high
     112                 :            :  * quality randomness is desired (for example, for key generation or
     113                 :            :  * one-time pads), as it will only return a maximum of the number of
     114                 :            :  * bits of randomness (as estimated by the random number generator)
     115                 :            :  * contained in the entropy pool.
     116                 :            :  *
     117                 :            :  * The /dev/urandom device does not have this limit, and will return
     118                 :            :  * as many bytes as are requested.  As more and more random bytes are
     119                 :            :  * requested without giving time for the entropy pool to recharge,
     120                 :            :  * this will result in random numbers that are merely cryptographically
     121                 :            :  * strong.  For many applications, however, this is acceptable.
     122                 :            :  *
     123                 :            :  * Exported interfaces ---- kernel output
     124                 :            :  * --------------------------------------
     125                 :            :  *
     126                 :            :  * The primary kernel interface is
     127                 :            :  *
     128                 :            :  *      void get_random_bytes(void *buf, int nbytes);
     129                 :            :  *
     130                 :            :  * This interface will return the requested number of random bytes,
     131                 :            :  * and place it in the requested buffer.  This is equivalent to a
     132                 :            :  * read from /dev/urandom.
     133                 :            :  *
     134                 :            :  * For less critical applications, there are the functions:
     135                 :            :  *
     136                 :            :  *      u32 get_random_u32()
     137                 :            :  *      u64 get_random_u64()
     138                 :            :  *      unsigned int get_random_int()
     139                 :            :  *      unsigned long get_random_long()
     140                 :            :  *
     141                 :            :  * These are produced by a cryptographic RNG seeded from get_random_bytes,
     142                 :            :  * and so do not deplete the entropy pool as much.  These are recommended
     143                 :            :  * for most in-kernel operations *if the result is going to be stored in
     144                 :            :  * the kernel*.
     145                 :            :  *
     146                 :            :  * Specifically, the get_random_int() family do not attempt to do
     147                 :            :  * "anti-backtracking".  If you capture the state of the kernel (e.g.
     148                 :            :  * by snapshotting the VM), you can figure out previous get_random_int()
     149                 :            :  * return values.  But if the value is stored in the kernel anyway,
     150                 :            :  * this is not a problem.
     151                 :            :  *
     152                 :            :  * It *is* safe to expose get_random_int() output to attackers (e.g. as
     153                 :            :  * network cookies); given outputs 1..n, it's not feasible to predict
     154                 :            :  * outputs 0 or n+1.  The only concern is an attacker who breaks into
     155                 :            :  * the kernel later; the get_random_int() engine is not reseeded as
     156                 :            :  * often as the get_random_bytes() one.
     157                 :            :  *
     158                 :            :  * get_random_bytes() is needed for keys that need to stay secret after
     159                 :            :  * they are erased from the kernel.  For example, any key that will
     160                 :            :  * be wrapped and stored encrypted.  And session encryption keys: we'd
     161                 :            :  * like to know that after the session is closed and the keys erased,
     162                 :            :  * the plaintext is unrecoverable to someone who recorded the ciphertext.
     163                 :            :  *
     164                 :            :  * But for network ports/cookies, stack canaries, PRNG seeds, address
     165                 :            :  * space layout randomization, session *authentication* keys, or other
     166                 :            :  * applications where the sensitive data is stored in the kernel in
     167                 :            :  * plaintext for as long as it's sensitive, the get_random_int() family
     168                 :            :  * is just fine.
     169                 :            :  *
     170                 :            :  * Consider ASLR.  We want to keep the address space secret from an
     171                 :            :  * outside attacker while the process is running, but once the address
     172                 :            :  * space is torn down, it's of no use to an attacker any more.  And it's
     173                 :            :  * stored in kernel data structures as long as it's alive, so worrying
     174                 :            :  * about an attacker's ability to extrapolate it from the get_random_int()
     175                 :            :  * CRNG is silly.
     176                 :            :  *
     177                 :            :  * Even some cryptographic keys are safe to generate with get_random_int().
     178                 :            :  * In particular, keys for SipHash are generally fine.  Here, knowledge
     179                 :            :  * of the key authorizes you to do something to a kernel object (inject
     180                 :            :  * packets to a network connection, or flood a hash table), and the
     181                 :            :  * key is stored with the object being protected.  Once it goes away,
     182                 :            :  * we no longer care if anyone knows the key.
     183                 :            :  *
     184                 :            :  * prandom_u32()
     185                 :            :  * -------------
     186                 :            :  *
     187                 :            :  * For even weaker applications, see the pseudorandom generator
     188                 :            :  * prandom_u32(), prandom_max(), and prandom_bytes().  If the random
     189                 :            :  * numbers aren't security-critical at all, these are *far* cheaper.
     190                 :            :  * Useful for self-tests, random error simulation, randomized backoffs,
     191                 :            :  * and any other application where you trust that nobody is trying to
     192                 :            :  * maliciously mess with you by guessing the "random" numbers.
     193                 :            :  *
     194                 :            :  * Exported interfaces ---- input
     195                 :            :  * ==============================
     196                 :            :  *
     197                 :            :  * The current exported interfaces for gathering environmental noise
     198                 :            :  * from the devices are:
     199                 :            :  *
     200                 :            :  *      void add_device_randomness(const void *buf, unsigned int size);
     201                 :            :  *      void add_input_randomness(unsigned int type, unsigned int code,
     202                 :            :  *                                unsigned int value);
     203                 :            :  *      void add_interrupt_randomness(int irq, int irq_flags);
     204                 :            :  *      void add_disk_randomness(struct gendisk *disk);
     205                 :            :  *
     206                 :            :  * add_device_randomness() is for adding data to the random pool that
     207                 :            :  * is likely to differ between two devices (or possibly even per boot).
     208                 :            :  * This would be things like MAC addresses or serial numbers, or the
     209                 :            :  * read-out of the RTC. This does *not* add any actual entropy to the
     210                 :            :  * pool, but it initializes the pool to different values for devices
     211                 :            :  * that might otherwise be identical and have very little entropy
     212                 :            :  * available to them (particularly common in the embedded world).
     213                 :            :  *
     214                 :            :  * add_input_randomness() uses the input layer interrupt timing, as well as
     215                 :            :  * the event type information from the hardware.
     216                 :            :  *
     217                 :            :  * add_interrupt_randomness() uses the interrupt timing as random
     218                 :            :  * inputs to the entropy pool. Using the cycle counters and the irq source
     219                 :            :  * as inputs, it feeds the randomness roughly once a second.
     220                 :            :  *
     221                 :            :  * add_disk_randomness() uses what amounts to the seek time of block
     222                 :            :  * layer request events, on a per-disk_devt basis, as input to the
     223                 :            :  * entropy pool. Note that high-speed solid state drives with very low
     224                 :            :  * seek times do not make for good sources of entropy, as their seek
     225                 :            :  * times are usually fairly consistent.
     226                 :            :  *
     227                 :            :  * All of these routines try to estimate how many bits of randomness a
     228                 :            :  * particular randomness source.  They do this by keeping track of the
     229                 :            :  * first and second order deltas of the event timings.
     230                 :            :  *
     231                 :            :  * Ensuring unpredictability at system startup
     232                 :            :  * ============================================
     233                 :            :  *
     234                 :            :  * When any operating system starts up, it will go through a sequence
     235                 :            :  * of actions that are fairly predictable by an adversary, especially
     236                 :            :  * if the start-up does not involve interaction with a human operator.
     237                 :            :  * This reduces the actual number of bits of unpredictability in the
     238                 :            :  * entropy pool below the value in entropy_count.  In order to
     239                 :            :  * counteract this effect, it helps to carry information in the
     240                 :            :  * entropy pool across shut-downs and start-ups.  To do this, put the
     241                 :            :  * following lines an appropriate script which is run during the boot
     242                 :            :  * sequence:
     243                 :            :  *
     244                 :            :  *      echo "Initializing random number generator..."
     245                 :            :  *      random_seed=/var/run/random-seed
     246                 :            :  *      # Carry a random seed from start-up to start-up
     247                 :            :  *      # Load and then save the whole entropy pool
     248                 :            :  *      if [ -f $random_seed ]; then
     249                 :            :  *              cat $random_seed >/dev/urandom
     250                 :            :  *      else
     251                 :            :  *              touch $random_seed
     252                 :            :  *      fi
     253                 :            :  *      chmod 600 $random_seed
     254                 :            :  *      dd if=/dev/urandom of=$random_seed count=1 bs=512
     255                 :            :  *
     256                 :            :  * and the following lines in an appropriate script which is run as
     257                 :            :  * the system is shutdown:
     258                 :            :  *
     259                 :            :  *      # Carry a random seed from shut-down to start-up
     260                 :            :  *      # Save the whole entropy pool
     261                 :            :  *      echo "Saving random seed..."
     262                 :            :  *      random_seed=/var/run/random-seed
     263                 :            :  *      touch $random_seed
     264                 :            :  *      chmod 600 $random_seed
     265                 :            :  *      dd if=/dev/urandom of=$random_seed count=1 bs=512
     266                 :            :  *
     267                 :            :  * For example, on most modern systems using the System V init
     268                 :            :  * scripts, such code fragments would be found in
     269                 :            :  * /etc/rc.d/init.d/random.  On older Linux systems, the correct script
     270                 :            :  * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
     271                 :            :  *
     272                 :            :  * Effectively, these commands cause the contents of the entropy pool
     273                 :            :  * to be saved at shut-down time and reloaded into the entropy pool at
     274                 :            :  * start-up.  (The 'dd' in the addition to the bootup script is to
     275                 :            :  * make sure that /etc/random-seed is different for every start-up,
     276                 :            :  * even if the system crashes without executing rc.0.)  Even with
     277                 :            :  * complete knowledge of the start-up activities, predicting the state
     278                 :            :  * of the entropy pool requires knowledge of the previous history of
     279                 :            :  * the system.
     280                 :            :  *
     281                 :            :  * Configuring the /dev/random driver under Linux
     282                 :            :  * ==============================================
     283                 :            :  *
     284                 :            :  * The /dev/random driver under Linux uses minor numbers 8 and 9 of
     285                 :            :  * the /dev/mem major number (#1).  So if your system does not have
     286                 :            :  * /dev/random and /dev/urandom created already, they can be created
     287                 :            :  * by using the commands:
     288                 :            :  *
     289                 :            :  *      mknod /dev/random c 1 8
     290                 :            :  *      mknod /dev/urandom c 1 9
     291                 :            :  *
     292                 :            :  * Acknowledgements:
     293                 :            :  * =================
     294                 :            :  *
     295                 :            :  * Ideas for constructing this random number generator were derived
     296                 :            :  * from Pretty Good Privacy's random number generator, and from private
     297                 :            :  * discussions with Phil Karn.  Colin Plumb provided a faster random
     298                 :            :  * number generator, which speed up the mixing function of the entropy
     299                 :            :  * pool, taken from PGPfone.  Dale Worley has also contributed many
     300                 :            :  * useful ideas and suggestions to improve this driver.
     301                 :            :  *
     302                 :            :  * Any flaws in the design are solely my responsibility, and should
     303                 :            :  * not be attributed to the Phil, Colin, or any of authors of PGP.
     304                 :            :  *
     305                 :            :  * Further background information on this topic may be obtained from
     306                 :            :  * RFC 1750, "Randomness Recommendations for Security", by Donald
     307                 :            :  * Eastlake, Steve Crocker, and Jeff Schiller.
     308                 :            :  */
     309                 :            : 
     310                 :            : #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
     311                 :            : 
     312                 :            : #include <linux/utsname.h>
     313                 :            : #include <linux/module.h>
     314                 :            : #include <linux/kernel.h>
     315                 :            : #include <linux/major.h>
     316                 :            : #include <linux/string.h>
     317                 :            : #include <linux/fcntl.h>
     318                 :            : #include <linux/slab.h>
     319                 :            : #include <linux/random.h>
     320                 :            : #include <linux/poll.h>
     321                 :            : #include <linux/init.h>
     322                 :            : #include <linux/fs.h>
     323                 :            : #include <linux/genhd.h>
     324                 :            : #include <linux/interrupt.h>
     325                 :            : #include <linux/mm.h>
     326                 :            : #include <linux/nodemask.h>
     327                 :            : #include <linux/spinlock.h>
     328                 :            : #include <linux/kthread.h>
     329                 :            : #include <linux/percpu.h>
     330                 :            : #include <linux/cryptohash.h>
     331                 :            : #include <linux/fips.h>
     332                 :            : #include <linux/ptrace.h>
     333                 :            : #include <linux/workqueue.h>
     334                 :            : #include <linux/irq.h>
     335                 :            : #include <linux/ratelimit.h>
     336                 :            : #include <linux/syscalls.h>
     337                 :            : #include <linux/completion.h>
     338                 :            : #include <linux/uuid.h>
     339                 :            : #include <crypto/chacha.h>
     340                 :            : 
     341                 :            : #include <asm/processor.h>
     342                 :            : #include <linux/uaccess.h>
     343                 :            : #include <asm/irq.h>
     344                 :            : #include <asm/irq_regs.h>
     345                 :            : #include <asm/io.h>
     346                 :            : 
     347                 :            : #define CREATE_TRACE_POINTS
     348                 :            : #include <trace/events/random.h>
     349                 :            : 
     350                 :            : /* #define ADD_INTERRUPT_BENCH */
     351                 :            : 
     352                 :            : /*
     353                 :            :  * Configuration information
     354                 :            :  */
     355                 :            : #define INPUT_POOL_SHIFT        12
     356                 :            : #define INPUT_POOL_WORDS        (1 << (INPUT_POOL_SHIFT-5))
     357                 :            : #define OUTPUT_POOL_SHIFT       10
     358                 :            : #define OUTPUT_POOL_WORDS       (1 << (OUTPUT_POOL_SHIFT-5))
     359                 :            : #define EXTRACT_SIZE            10
     360                 :            : 
     361                 :            : 
     362                 :            : #define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))
     363                 :            : 
     364                 :            : /*
     365                 :            :  * To allow fractional bits to be tracked, the entropy_count field is
     366                 :            :  * denominated in units of 1/8th bits.
     367                 :            :  *
     368                 :            :  * 2*(ENTROPY_SHIFT + poolbitshift) must <= 31, or the multiply in
     369                 :            :  * credit_entropy_bits() needs to be 64 bits wide.
     370                 :            :  */
     371                 :            : #define ENTROPY_SHIFT 3
     372                 :            : #define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT)
     373                 :            : 
     374                 :            : /*
     375                 :            :  * If the entropy count falls under this number of bits, then we
     376                 :            :  * should wake up processes which are selecting or polling on write
     377                 :            :  * access to /dev/random.
     378                 :            :  */
     379                 :            : static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
     380                 :            : 
     381                 :            : /*
     382                 :            :  * Originally, we used a primitive polynomial of degree .poolwords
     383                 :            :  * over GF(2).  The taps for various sizes are defined below.  They
     384                 :            :  * were chosen to be evenly spaced except for the last tap, which is 1
     385                 :            :  * to get the twisting happening as fast as possible.
     386                 :            :  *
     387                 :            :  * For the purposes of better mixing, we use the CRC-32 polynomial as
     388                 :            :  * well to make a (modified) twisted Generalized Feedback Shift
     389                 :            :  * Register.  (See M. Matsumoto & Y. Kurita, 1992.  Twisted GFSR
     390                 :            :  * generators.  ACM Transactions on Modeling and Computer Simulation
     391                 :            :  * 2(3):179-194.  Also see M. Matsumoto & Y. Kurita, 1994.  Twisted
     392                 :            :  * GFSR generators II.  ACM Transactions on Modeling and Computer
     393                 :            :  * Simulation 4:254-266)
     394                 :            :  *
     395                 :            :  * Thanks to Colin Plumb for suggesting this.
     396                 :            :  *
     397                 :            :  * The mixing operation is much less sensitive than the output hash,
     398                 :            :  * where we use SHA-1.  All that we want of mixing operation is that
     399                 :            :  * it be a good non-cryptographic hash; i.e. it not produce collisions
     400                 :            :  * when fed "random" data of the sort we expect to see.  As long as
     401                 :            :  * the pool state differs for different inputs, we have preserved the
     402                 :            :  * input entropy and done a good job.  The fact that an intelligent
     403                 :            :  * attacker can construct inputs that will produce controlled
     404                 :            :  * alterations to the pool's state is not important because we don't
     405                 :            :  * consider such inputs to contribute any randomness.  The only
     406                 :            :  * property we need with respect to them is that the attacker can't
     407                 :            :  * increase his/her knowledge of the pool's state.  Since all
     408                 :            :  * additions are reversible (knowing the final state and the input,
     409                 :            :  * you can reconstruct the initial state), if an attacker has any
     410                 :            :  * uncertainty about the initial state, he/she can only shuffle that
     411                 :            :  * uncertainty about, but never cause any collisions (which would
     412                 :            :  * decrease the uncertainty).
     413                 :            :  *
     414                 :            :  * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and
     415                 :            :  * Videau in their paper, "The Linux Pseudorandom Number Generator
     416                 :            :  * Revisited" (see: http://eprint.iacr.org/2012/251.pdf).  In their
     417                 :            :  * paper, they point out that we are not using a true Twisted GFSR,
     418                 :            :  * since Matsumoto & Kurita used a trinomial feedback polynomial (that
     419                 :            :  * is, with only three taps, instead of the six that we are using).
     420                 :            :  * As a result, the resulting polynomial is neither primitive nor
     421                 :            :  * irreducible, and hence does not have a maximal period over
     422                 :            :  * GF(2**32).  They suggest a slight change to the generator
     423                 :            :  * polynomial which improves the resulting TGFSR polynomial to be
     424                 :            :  * irreducible, which we have made here.
     425                 :            :  */
     426                 :            : static const struct poolinfo {
     427                 :            :         int poolbitshift, poolwords, poolbytes, poolfracbits;
     428                 :            : #define S(x) ilog2(x)+5, (x), (x)*4, (x) << (ENTROPY_SHIFT+5)
     429                 :            :         int tap1, tap2, tap3, tap4, tap5;
     430                 :            : } poolinfo_table[] = {
     431                 :            :         /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */
     432                 :            :         /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
     433                 :            :         { S(128),       104,    76,     51,     25,     1 },
     434                 :            : };
     435                 :            : 
     436                 :            : /*
     437                 :            :  * Static global variables
     438                 :            :  */
     439                 :            : static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
     440                 :            : static struct fasync_struct *fasync;
     441                 :            : 
     442                 :            : static DEFINE_SPINLOCK(random_ready_list_lock);
     443                 :            : static LIST_HEAD(random_ready_list);
     444                 :            : 
     445                 :            : struct crng_state {
     446                 :            :         __u32           state[16];
     447                 :            :         unsigned long   init_time;
     448                 :            :         spinlock_t      lock;
     449                 :            : };
     450                 :            : 
     451                 :            : static struct crng_state primary_crng = {
     452                 :            :         .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock),
     453                 :            : };
     454                 :            : 
     455                 :            : /*
     456                 :            :  * crng_init =  0 --> Uninitialized
     457                 :            :  *              1 --> Initialized
     458                 :            :  *              2 --> Initialized from input_pool
     459                 :            :  *
     460                 :            :  * crng_init is protected by primary_crng->lock, and only increases
     461                 :            :  * its value (from 0->1->2).
     462                 :            :  */
     463                 :            : static int crng_init = 0;
     464                 :            : #define crng_ready() (likely(crng_init > 1))
     465                 :            : static int crng_init_cnt = 0;
     466                 :            : static unsigned long crng_global_init_time = 0;
     467                 :            : #define CRNG_INIT_CNT_THRESH (2*CHACHA_KEY_SIZE)
     468                 :            : static void _extract_crng(struct crng_state *crng, __u8 out[CHACHA_BLOCK_SIZE]);
     469                 :            : static void _crng_backtrack_protect(struct crng_state *crng,
     470                 :            :                                     __u8 tmp[CHACHA_BLOCK_SIZE], int used);
     471                 :            : static void process_random_ready_list(void);
     472                 :            : static void _get_random_bytes(void *buf, int nbytes);
     473                 :            : 
     474                 :            : static struct ratelimit_state unseeded_warning =
     475                 :            :         RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
     476                 :            : static struct ratelimit_state urandom_warning =
     477                 :            :         RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
     478                 :            : 
     479                 :            : static int ratelimit_disable __read_mostly;
     480                 :            : 
     481                 :            : module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
     482                 :            : MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
     483                 :            : 
     484                 :            : /**********************************************************************
     485                 :            :  *
     486                 :            :  * OS independent entropy store.   Here are the functions which handle
     487                 :            :  * storing entropy in an entropy pool.
     488                 :            :  *
     489                 :            :  **********************************************************************/
     490                 :            : 
     491                 :            : struct entropy_store;
     492                 :            : struct entropy_store {
     493                 :            :         /* read-only data: */
     494                 :            :         const struct poolinfo *poolinfo;
     495                 :            :         __u32 *pool;
     496                 :            :         const char *name;
     497                 :            : 
     498                 :            :         /* read-write data: */
     499                 :            :         spinlock_t lock;
     500                 :            :         unsigned short add_ptr;
     501                 :            :         unsigned short input_rotate;
     502                 :            :         int entropy_count;
     503                 :            :         unsigned int initialized:1;
     504                 :            :         unsigned int last_data_init:1;
     505                 :            :         __u8 last_data[EXTRACT_SIZE];
     506                 :            : };
     507                 :            : 
     508                 :            : static ssize_t extract_entropy(struct entropy_store *r, void *buf,
     509                 :            :                                size_t nbytes, int min, int rsvd);
     510                 :            : static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
     511                 :            :                                 size_t nbytes, int fips);
     512                 :            : 
     513                 :            : static void crng_reseed(struct crng_state *crng, struct entropy_store *r);
     514                 :            : static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;
     515                 :            : 
     516                 :            : static struct entropy_store input_pool = {
     517                 :            :         .poolinfo = &poolinfo_table[0],
     518                 :            :         .name = "input",
     519                 :            :         .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
     520                 :            :         .pool = input_pool_data
     521                 :            : };
     522                 :            : 
     523                 :            : static __u32 const twist_table[8] = {
     524                 :            :         0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
     525                 :            :         0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
     526                 :            : 
     527                 :            : /*
     528                 :            :  * This function adds bytes into the entropy "pool".  It does not
     529                 :            :  * update the entropy estimate.  The caller should call
     530                 :            :  * credit_entropy_bits if this is appropriate.
     531                 :            :  *
     532                 :            :  * The pool is stirred with a primitive polynomial of the appropriate
     533                 :            :  * degree, and then twisted.  We twist by three bits at a time because
     534                 :            :  * it's cheap to do so and helps slightly in the expected case where
     535                 :            :  * the entropy is concentrated in the low-order bits.
     536                 :            :  */
     537                 :      66428 : static void _mix_pool_bytes(struct entropy_store *r, const void *in,
     538                 :            :                             int nbytes)
     539                 :            : {
     540                 :      66428 :         unsigned long i, tap1, tap2, tap3, tap4, tap5;
     541                 :      66428 :         int input_rotate;
     542                 :      66428 :         int wordmask = r->poolinfo->poolwords - 1;
     543                 :      66428 :         const char *bytes = in;
     544                 :      66428 :         __u32 w;
     545                 :            : 
     546                 :      66428 :         tap1 = r->poolinfo->tap1;
     547                 :      66428 :         tap2 = r->poolinfo->tap2;
     548                 :      66428 :         tap3 = r->poolinfo->tap3;
     549                 :      66428 :         tap4 = r->poolinfo->tap4;
     550                 :      66428 :         tap5 = r->poolinfo->tap5;
     551                 :            : 
     552                 :      66428 :         input_rotate = r->input_rotate;
     553                 :      66428 :         i = r->add_ptr;
     554                 :            : 
     555                 :            :         /* mix one byte at a time to simplify size handling and churn faster */
     556         [ +  + ]:     706964 :         while (nbytes--) {
     557         [ +  + ]:     640536 :                 w = rol32(*bytes++, input_rotate);
     558                 :     640536 :                 i = (i - 1) & wordmask;
     559                 :            : 
     560                 :            :                 /* XOR in the various taps */
     561                 :     640536 :                 w ^= r->pool[i];
     562                 :     640536 :                 w ^= r->pool[(i + tap1) & wordmask];
     563                 :     640536 :                 w ^= r->pool[(i + tap2) & wordmask];
     564                 :     640536 :                 w ^= r->pool[(i + tap3) & wordmask];
     565                 :     640536 :                 w ^= r->pool[(i + tap4) & wordmask];
     566                 :     640536 :                 w ^= r->pool[(i + tap5) & wordmask];
     567                 :            : 
     568                 :            :                 /* Mix the result back in with a twist */
     569                 :     640536 :                 r->pool[i] = (w >> 3) ^ twist_table[w & 7];
     570                 :            : 
     571                 :            :                 /*
     572                 :            :                  * Normally, we add 7 bits of rotation to the pool.
     573                 :            :                  * At the beginning of the pool, add an extra 7 bits
     574                 :            :                  * rotation, so that successive passes spread the
     575                 :            :                  * input bits across the pool evenly.
     576                 :            :                  */
     577         [ +  + ]:     645532 :                 input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
     578                 :            :         }
     579                 :            : 
     580                 :      66428 :         r->input_rotate = input_rotate;
     581                 :      66428 :         r->add_ptr = i;
     582                 :      66428 : }
     583                 :            : 
     584                 :        473 : static void __mix_pool_bytes(struct entropy_store *r, const void *in,
     585                 :            :                              int nbytes)
     586                 :            : {
     587                 :        473 :         trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_);
     588                 :        473 :         _mix_pool_bytes(r, in, nbytes);
     589                 :        473 : }
     590                 :            : 
     591                 :      11549 : static void mix_pool_bytes(struct entropy_store *r, const void *in,
     592                 :            :                            int nbytes)
     593                 :            : {
     594                 :      11549 :         unsigned long flags;
     595                 :            : 
     596                 :      11549 :         trace_mix_pool_bytes(r->name, nbytes, _RET_IP_);
     597                 :      11549 :         spin_lock_irqsave(&r->lock, flags);
     598                 :      11549 :         _mix_pool_bytes(r, in, nbytes);
     599                 :      11549 :         spin_unlock_irqrestore(&r->lock, flags);
     600                 :      11549 : }
     601                 :            : 
     602                 :            : struct fast_pool {
     603                 :            :         __u32           pool[4];
     604                 :            :         unsigned long   last;
     605                 :            :         unsigned short  reg_idx;
     606                 :            :         unsigned char   count;
     607                 :            : };
     608                 :            : 
     609                 :            : /*
     610                 :            :  * This is a fast mixing routine used by the interrupt randomness
     611                 :            :  * collector.  It's hardcoded for an 128 bit pool and assumes that any
     612                 :            :  * locks that might be needed are taken by the caller.
     613                 :            :  */
     614                 :      27745 : static void fast_mix(struct fast_pool *f)
     615                 :            : {
     616                 :      27745 :         __u32 a = f->pool[0],        b = f->pool[1];
     617                 :      27745 :         __u32 c = f->pool[2],        d = f->pool[3];
     618                 :            : 
     619                 :      27745 :         a += b;                 c += d;
     620                 :      27745 :         b = rol32(b, 6);        d = rol32(d, 27);
     621                 :      27745 :         d ^= a;                 b ^= c;
     622                 :            : 
     623                 :      27745 :         a += b;                 c += d;
     624                 :      27745 :         b = rol32(b, 16);       d = rol32(d, 14);
     625                 :      27745 :         d ^= a;                 b ^= c;
     626                 :            : 
     627                 :      27745 :         a += b;                 c += d;
     628                 :      27745 :         b = rol32(b, 6);        d = rol32(d, 27);
     629                 :      27745 :         d ^= a;                 b ^= c;
     630                 :            : 
     631                 :      27745 :         a += b;                 c += d;
     632                 :      27745 :         b = rol32(b, 16);       d = rol32(d, 14);
     633                 :      27745 :         d ^= a;                 b ^= c;
     634                 :            : 
     635                 :      27745 :         f->pool[0] = a;  f->pool[1] = b;
     636                 :      27745 :         f->pool[2] = c;  f->pool[3] = d;
     637                 :      27745 :         f->count++;
     638                 :      27745 : }
     639                 :            : 
     640                 :         11 : static void process_random_ready_list(void)
     641                 :            : {
     642                 :         11 :         unsigned long flags;
     643                 :         11 :         struct random_ready_callback *rdy, *tmp;
     644                 :            : 
     645                 :         11 :         spin_lock_irqsave(&random_ready_list_lock, flags);
     646         [ +  + ]:         22 :         list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
     647                 :         11 :                 struct module *owner = rdy->owner;
     648                 :            : 
     649                 :         11 :                 list_del_init(&rdy->list);
     650                 :         11 :                 rdy->func(rdy);
     651                 :         11 :                 module_put(owner);
     652                 :            :         }
     653                 :         11 :         spin_unlock_irqrestore(&random_ready_list_lock, flags);
     654                 :         11 : }
     655                 :            : 
     656                 :            : /*
     657                 :            :  * Credit (or debit) the entropy store with n bits of entropy.
     658                 :            :  * Use credit_entropy_bits_safe() if the value comes from userspace
     659                 :            :  * or otherwise should be checked for extreme values.
     660                 :            :  */
     661                 :      11208 : static void credit_entropy_bits(struct entropy_store *r, int nbits)
     662                 :            : {
     663                 :      11208 :         int entropy_count, orig, has_initialized = 0;
     664                 :      11208 :         const int pool_size = r->poolinfo->poolfracbits;
     665                 :      11208 :         int nfrac = nbits << ENTROPY_SHIFT;
     666                 :            : 
     667         [ +  + ]:      11208 :         if (!nbits)
     668                 :            :                 return;
     669                 :            : 
     670                 :       1558 : retry:
     671         [ -  + ]:       1558 :         entropy_count = orig = READ_ONCE(r->entropy_count);
     672         [ -  + ]:       1558 :         if (nfrac < 0) {
     673                 :            :                 /* Debit */
     674                 :          0 :                 entropy_count += nfrac;
     675                 :            :         } else {
     676                 :            :                 /*
     677                 :            :                  * Credit: we have to account for the possibility of
     678                 :            :                  * overwriting already present entropy.  Even in the
     679                 :            :                  * ideal case of pure Shannon entropy, new contributions
     680                 :            :                  * approach the full value asymptotically:
     681                 :            :                  *
     682                 :            :                  * entropy <- entropy + (pool_size - entropy) *
     683                 :            :                  *      (1 - exp(-add_entropy/pool_size))
     684                 :            :                  *
     685                 :            :                  * For add_entropy <= pool_size/2 then
     686                 :            :                  * (1 - exp(-add_entropy/pool_size)) >=
     687                 :            :                  *    (add_entropy/pool_size)*0.7869...
     688                 :            :                  * so we can approximate the exponential with
     689                 :            :                  * 3/4*add_entropy/pool_size and still be on the
     690                 :            :                  * safe side by adding at most pool_size/2 at a time.
     691                 :            :                  *
     692                 :            :                  * The use of pool_size-2 in the while statement is to
     693                 :            :                  * prevent rounding artifacts from making the loop
     694                 :            :                  * arbitrarily long; this limits the loop to log2(pool_size)*2
     695                 :            :                  * turns no matter how large nbits is.
     696                 :            :                  */
     697                 :       1558 :                 int pnfrac = nfrac;
     698                 :       1558 :                 const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2;
     699                 :            :                 /* The +2 corresponds to the /4 in the denominator */
     700                 :            : 
     701                 :       1558 :                 do {
     702                 :       1558 :                         unsigned int anfrac = min(pnfrac, pool_size/2);
     703                 :       1558 :                         unsigned int add =
     704                 :       1558 :                                 ((pool_size - entropy_count)*anfrac*3) >> s;
     705                 :            : 
     706                 :       1558 :                         entropy_count += add;
     707                 :       1558 :                         pnfrac -= anfrac;
     708   [ +  -  -  + ]:       1558 :                 } while (unlikely(entropy_count < pool_size-2 && pnfrac));
     709                 :            :         }
     710                 :            : 
     711   [ -  +  -  + ]:       1558 :         if (WARN_ON(entropy_count < 0)) {
     712                 :          0 :                 pr_warn("negative entropy/overflow: pool %s count %d\n",
     713                 :            :                         r->name, entropy_count);
     714                 :          0 :                 entropy_count = 0;
     715                 :       1558 :         } else if (entropy_count > pool_size)
     716                 :            :                 entropy_count = pool_size;
     717         [ -  + ]:       1558 :         if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
     718                 :          0 :                 goto retry;
     719                 :            : 
     720                 :       1558 :         if (has_initialized) {
     721                 :            :                 r->initialized = 1;
     722                 :            :                 kill_fasync(&fasync, SIGIO, POLL_IN);
     723                 :            :         }
     724                 :            : 
     725                 :       1558 :         trace_credit_entropy_bits(r->name, nbits,
     726                 :       1558 :                                   entropy_count >> ENTROPY_SHIFT, _RET_IP_);
     727                 :            : 
     728         [ +  - ]:       1558 :         if (r == &input_pool) {
     729                 :       1558 :                 int entropy_bits = entropy_count >> ENTROPY_SHIFT;
     730                 :            : 
     731         [ +  + ]:       1558 :                 if (crng_init < 2) {
     732         [ +  + ]:       1155 :                         if (entropy_bits < 128)
     733                 :            :                                 return;
     734                 :         11 :                         crng_reseed(&primary_crng, r);
     735                 :         11 :                         entropy_bits = ENTROPY_BITS(r);
     736                 :            :                 }
     737                 :            :         }
     738                 :            : }
     739                 :            : 
     740                 :          0 : static int credit_entropy_bits_safe(struct entropy_store *r, int nbits)
     741                 :            : {
     742                 :          0 :         const int nbits_max = r->poolinfo->poolwords * 32;
     743                 :            : 
     744                 :          0 :         if (nbits < 0)
     745                 :            :                 return -EINVAL;
     746                 :            : 
     747                 :            :         /* Cap the value to avoid overflows */
     748                 :          0 :         nbits = min(nbits,  nbits_max);
     749                 :            : 
     750                 :          0 :         credit_entropy_bits(r, nbits);
     751                 :          0 :         return 0;
     752                 :            : }
     753                 :            : 
     754                 :            : /*********************************************************************
     755                 :            :  *
     756                 :            :  * CRNG using CHACHA20
     757                 :            :  *
     758                 :            :  *********************************************************************/
     759                 :            : 
     760                 :            : #define CRNG_RESEED_INTERVAL (300*HZ)
     761                 :            : 
     762                 :            : static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
     763                 :            : 
     764                 :            : #ifdef CONFIG_NUMA
     765                 :            : /*
     766                 :            :  * Hack to deal with crazy userspace progams when they are all trying
     767                 :            :  * to access /dev/urandom in parallel.  The programs are almost
     768                 :            :  * certainly doing something terribly wrong, but we'll work around
     769                 :            :  * their brain damage.
     770                 :            :  */
     771                 :            : static struct crng_state **crng_node_pool __read_mostly;
     772                 :            : #endif
     773                 :            : 
     774                 :            : static void invalidate_batched_entropy(void);
     775                 :            : static void numa_crng_init(void);
     776                 :            : 
     777                 :            : static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
     778                 :          0 : static int __init parse_trust_cpu(char *arg)
     779                 :            : {
     780                 :          0 :         return kstrtobool(arg, &trust_cpu);
     781                 :            : }
     782                 :            : early_param("random.trust_cpu", parse_trust_cpu);
     783                 :            : 
     784                 :         22 : static void crng_initialize(struct crng_state *crng)
     785                 :            : {
     786                 :         22 :         int             i;
     787                 :         22 :         int             arch_init = 1;
     788                 :         22 :         unsigned long   rv;
     789                 :            : 
     790                 :         22 :         memcpy(&crng->state[0], "expand 32-byte k", 16);
     791         [ +  + ]:         22 :         if (crng == &primary_crng)
     792                 :         11 :                 _extract_entropy(&input_pool, &crng->state[4],
     793                 :            :                                  sizeof(__u32) * 12, 0);
     794                 :            :         else
     795                 :         11 :                 _get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
     796         [ +  + ]:        286 :         for (i = 4; i < 16; i++) {
     797   [ +  -  +  - ]:        528 :                 if (!arch_get_random_seed_long(&rv) &&
     798                 :        264 :                     !arch_get_random_long(&rv)) {
     799                 :        264 :                         rv = random_get_entropy();
     800                 :        264 :                         arch_init = 0;
     801                 :            :                 }
     802                 :        264 :                 crng->state[i] ^= rv;
     803                 :            :         }
     804   [ -  +  -  -  :         22 :         if (trust_cpu && arch_init && crng == &primary_crng) {
                   -  - ]
     805                 :          0 :                 invalidate_batched_entropy();
     806                 :          0 :                 numa_crng_init();
     807                 :          0 :                 crng_init = 2;
     808                 :          0 :                 pr_notice("crng done (trusting CPU's manufacturer)\n");
     809                 :            :         }
     810                 :         22 :         crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
     811                 :         22 : }
     812                 :            : 
     813                 :            : #ifdef CONFIG_NUMA
     814                 :         11 : static void do_numa_crng_init(struct work_struct *work)
     815                 :            : {
     816                 :         11 :         int i;
     817                 :         11 :         struct crng_state *crng;
     818                 :         11 :         struct crng_state **pool;
     819                 :            : 
     820                 :         11 :         pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL);
     821         [ +  + ]:         33 :         for_each_online_node(i) {
     822                 :         11 :                 crng = kmalloc_node(sizeof(struct crng_state),
     823                 :            :                                     GFP_KERNEL | __GFP_NOFAIL, i);
     824                 :         11 :                 spin_lock_init(&crng->lock);
     825                 :         11 :                 crng_initialize(crng);
     826                 :         11 :                 pool[i] = crng;
     827                 :            :         }
     828                 :         11 :         mb();
     829         [ -  + ]:         11 :         if (cmpxchg(&crng_node_pool, NULL, pool)) {
     830         [ #  # ]:          0 :                 for_each_node(i)
     831                 :          0 :                         kfree(pool[i]);
     832                 :          0 :                 kfree(pool);
     833                 :            :         }
     834                 :         11 : }
     835                 :            : 
     836                 :            : static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init);
     837                 :            : 
     838                 :         11 : static void numa_crng_init(void)
     839                 :            : {
     840                 :          0 :         schedule_work(&numa_crng_init_work);
     841                 :            : }
     842                 :            : #else
     843                 :            : static void numa_crng_init(void) {}
     844                 :            : #endif
     845                 :            : 
     846                 :            : /*
     847                 :            :  * crng_fast_load() can be called by code in the interrupt service
     848                 :            :  * path.  So we can't afford to dilly-dally.
     849                 :            :  */
     850                 :         44 : static int crng_fast_load(const char *cp, size_t len)
     851                 :            : {
     852                 :         44 :         unsigned long flags;
     853                 :         44 :         char *p;
     854                 :            : 
     855         [ -  + ]:         88 :         if (!spin_trylock_irqsave(&primary_crng.lock, flags))
     856                 :          0 :                 return 0;
     857         [ -  + ]:         44 :         if (crng_init != 0) {
     858                 :          0 :                 spin_unlock_irqrestore(&primary_crng.lock, flags);
     859                 :          0 :                 return 0;
     860                 :            :         }
     861                 :            :         p = (unsigned char *) &primary_crng.state[4];
     862   [ +  +  +  - ]:        748 :         while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
     863                 :        704 :                 p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp;
     864                 :        704 :                 cp++; crng_init_cnt++; len--;
     865                 :            :         }
     866                 :         44 :         spin_unlock_irqrestore(&primary_crng.lock, flags);
     867         [ +  + ]:         44 :         if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
     868                 :         11 :                 invalidate_batched_entropy();
     869                 :         11 :                 crng_init = 1;
     870                 :         11 :                 pr_notice("fast init done\n");
     871                 :            :         }
     872                 :            :         return 1;
     873                 :            : }
     874                 :            : 
     875                 :            : /*
     876                 :            :  * crng_slow_load() is called by add_device_randomness, which has two
     877                 :            :  * attributes.  (1) We can't trust the buffer passed to it is
     878                 :            :  * guaranteed to be unpredictable (so it might not have any entropy at
     879                 :            :  * all), and (2) it doesn't have the performance constraints of
     880                 :            :  * crng_fast_load().
     881                 :            :  *
     882                 :            :  * So we do something more comprehensive which is guaranteed to touch
     883                 :            :  * all of the primary_crng's state, and which uses a LFSR with a
     884                 :            :  * period of 255 as part of the mixing algorithm.  Finally, we do
     885                 :            :  * *not* advance crng_init_cnt since buffer we may get may be something
     886                 :            :  * like a fixed DMI table (for example), which might very well be
     887                 :            :  * unique to the machine, but is otherwise unvarying.
     888                 :            :  */
     889                 :       1270 : static int crng_slow_load(const char *cp, size_t len)
     890                 :            : {
     891                 :       1270 :         unsigned long           flags;
     892                 :       1270 :         static unsigned char    lfsr = 1;
     893                 :       1270 :         unsigned char           tmp;
     894                 :       1270 :         unsigned                i, max = CHACHA_KEY_SIZE;
     895                 :       1270 :         const char *            src_buf = cp;
     896                 :       1270 :         char *                  dest_buf = (char *) &primary_crng.state[4];
     897                 :            : 
     898         [ -  + ]:       2540 :         if (!spin_trylock_irqsave(&primary_crng.lock, flags))
     899                 :          0 :                 return 0;
     900         [ +  + ]:       1270 :         if (crng_init != 0) {
     901                 :        643 :                 spin_unlock_irqrestore(&primary_crng.lock, flags);
     902                 :        643 :                 return 0;
     903                 :            :         }
     904                 :        627 :         if (len > max)
     905                 :            :                 max = len;
     906                 :            : 
     907         [ +  + ]:      33957 :         for (i = 0; i < max ; i++) {
     908                 :      33330 :                 tmp = lfsr;
     909                 :      33330 :                 lfsr >>= 1;
     910         [ +  + ]:      33330 :                 if (tmp & 1)
     911                 :      16748 :                         lfsr ^= 0xE1;
     912                 :      33330 :                 tmp = dest_buf[i % CHACHA_KEY_SIZE];
     913                 :      33330 :                 dest_buf[i % CHACHA_KEY_SIZE] ^= src_buf[i % len] ^ lfsr;
     914                 :      33330 :                 lfsr += (tmp << 3) | (tmp >> 5);
     915                 :            :         }
     916                 :        627 :         spin_unlock_irqrestore(&primary_crng.lock, flags);
     917                 :        627 :         return 1;
     918                 :            : }
     919                 :            : 
     920                 :         22 : static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
     921                 :            : {
     922                 :         22 :         unsigned long   flags;
     923                 :         22 :         int             i, num;
     924                 :         22 :         union {
     925                 :            :                 __u8    block[CHACHA_BLOCK_SIZE];
     926                 :            :                 __u32   key[8];
     927                 :            :         } buf;
     928                 :            : 
     929         [ +  + ]:         22 :         if (r) {
     930                 :         11 :                 num = extract_entropy(r, &buf, 32, 16, 0);
     931         [ -  + ]:         11 :                 if (num == 0)
     932                 :          0 :                         return;
     933                 :            :         } else {
     934                 :         11 :                 _extract_crng(&primary_crng, buf.block);
     935                 :         11 :                 _crng_backtrack_protect(&primary_crng, buf.block,
     936                 :            :                                         CHACHA_KEY_SIZE);
     937                 :            :         }
     938                 :         22 :         spin_lock_irqsave(&crng->lock, flags);
     939         [ +  + ]:        220 :         for (i = 0; i < 8; i++) {
     940                 :        176 :                 unsigned long   rv;
     941   [ +  -  +  - ]:        352 :                 if (!arch_get_random_seed_long(&rv) &&
     942                 :        176 :                     !arch_get_random_long(&rv))
     943                 :        176 :                         rv = random_get_entropy();
     944                 :        176 :                 crng->state[i+4] ^= buf.key[i] ^ rv;
     945                 :            :         }
     946                 :         22 :         memzero_explicit(&buf, sizeof(buf));
     947                 :         22 :         crng->init_time = jiffies;
     948                 :         22 :         spin_unlock_irqrestore(&crng->lock, flags);
     949   [ +  +  +  - ]:         22 :         if (crng == &primary_crng && crng_init < 2) {
     950                 :         11 :                 invalidate_batched_entropy();
     951                 :         11 :                 numa_crng_init();
     952                 :         11 :                 crng_init = 2;
     953                 :         11 :                 process_random_ready_list();
     954                 :         11 :                 wake_up_interruptible(&crng_init_wait);
     955                 :         11 :                 kill_fasync(&fasync, SIGIO, POLL_IN);
     956                 :         11 :                 pr_notice("crng init done\n");
     957         [ -  + ]:         11 :                 if (unseeded_warning.missed) {
     958                 :          0 :                         pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
     959                 :            :                                   unseeded_warning.missed);
     960                 :          0 :                         unseeded_warning.missed = 0;
     961                 :            :                 }
     962         [ +  - ]:         11 :                 if (urandom_warning.missed) {
     963                 :         11 :                         pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
     964                 :            :                                   urandom_warning.missed);
     965                 :         11 :                         urandom_warning.missed = 0;
     966                 :            :                 }
     967                 :            :         }
     968                 :            : }
     969                 :            : 
     970                 :      56061 : static void _extract_crng(struct crng_state *crng,
     971                 :            :                           __u8 out[CHACHA_BLOCK_SIZE])
     972                 :            : {
     973                 :      56061 :         unsigned long v, flags;
     974                 :            : 
     975         [ +  + ]:      56061 :         if (crng_ready() &&
     976         [ +  + ]:      52337 :             (time_after(crng_global_init_time, crng->init_time) ||
     977         [ -  + ]:      52326 :              time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL)))
     978         [ +  - ]:         22 :                 crng_reseed(crng, crng == &primary_crng ? &input_pool : NULL);
     979                 :      56061 :         spin_lock_irqsave(&crng->lock, flags);
     980         [ -  + ]:      56061 :         if (arch_get_random_long(&v))
     981                 :          0 :                 crng->state[14] ^= v;
     982                 :      56061 :         chacha20_block(&crng->state[0], out);
     983         [ -  + ]:      56061 :         if (crng->state[12] == 0)
     984                 :          0 :                 crng->state[13]++;
     985                 :      56061 :         spin_unlock_irqrestore(&crng->lock, flags);
     986                 :      56061 : }
     987                 :            : 
     988                 :      56050 : static void extract_crng(__u8 out[CHACHA_BLOCK_SIZE])
     989                 :            : {
     990                 :      56050 :         struct crng_state *crng = NULL;
     991                 :            : 
     992                 :            : #ifdef CONFIG_NUMA
     993         [ +  + ]:      56050 :         if (crng_node_pool)
     994         [ -  + ]:      52304 :                 crng = crng_node_pool[numa_node_id()];
     995         [ -  + ]:      52304 :         if (crng == NULL)
     996                 :            : #endif
     997                 :            :                 crng = &primary_crng;
     998                 :      56050 :         _extract_crng(crng, out);
     999                 :      56050 : }
    1000                 :            : 
    1001                 :            : /*
    1002                 :            :  * Use the leftover bytes from the CRNG block output (if there is
    1003                 :            :  * enough) to mutate the CRNG key to provide backtracking protection.
    1004                 :            :  */
    1005                 :      30742 : static void _crng_backtrack_protect(struct crng_state *crng,
    1006                 :            :                                     __u8 tmp[CHACHA_BLOCK_SIZE], int used)
    1007                 :            : {
    1008                 :      30742 :         unsigned long   flags;
    1009                 :      30742 :         __u32           *s, *d;
    1010                 :      30742 :         int             i;
    1011                 :            : 
    1012                 :      30742 :         used = round_up(used, sizeof(__u32));
    1013         [ +  + ]:      30742 :         if (used + CHACHA_KEY_SIZE > CHACHA_BLOCK_SIZE) {
    1014                 :         22 :                 extract_crng(tmp);
    1015                 :         22 :                 used = 0;
    1016                 :            :         }
    1017                 :      30742 :         spin_lock_irqsave(&crng->lock, flags);
    1018                 :      30742 :         s = (__u32 *) &tmp[used];
    1019                 :      30742 :         d = &crng->state[4];
    1020         [ +  + ]:     276678 :         for (i=0; i < 8; i++)
    1021                 :     245936 :                 *d++ ^= *s++;
    1022                 :      30742 :         spin_unlock_irqrestore(&crng->lock, flags);
    1023                 :      30742 : }
    1024                 :            : 
    1025                 :      30731 : static void crng_backtrack_protect(__u8 tmp[CHACHA_BLOCK_SIZE], int used)
    1026                 :            : {
    1027                 :      30731 :         struct crng_state *crng = NULL;
    1028                 :            : 
    1029                 :            : #ifdef CONFIG_NUMA
    1030         [ +  + ]:      30731 :         if (crng_node_pool)
    1031         [ -  + ]:      27932 :                 crng = crng_node_pool[numa_node_id()];
    1032         [ -  + ]:      27932 :         if (crng == NULL)
    1033                 :            : #endif
    1034                 :            :                 crng = &primary_crng;
    1035                 :      30731 :         _crng_backtrack_protect(crng, tmp, used);
    1036                 :      30731 : }
    1037                 :            : 
    1038                 :       2609 : static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
    1039                 :            : {
    1040                 :       2609 :         ssize_t ret = 0, i = CHACHA_BLOCK_SIZE;
    1041                 :       2609 :         __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
    1042                 :       2609 :         int large_request = (nbytes > 256);
    1043                 :            : 
    1044         [ +  + ]:       5295 :         while (nbytes) {
    1045   [ +  +  -  + ]:       2774 :                 if (large_request && need_resched()) {
    1046         [ #  # ]:          0 :                         if (signal_pending(current)) {
    1047         [ #  # ]:          0 :                                 if (ret == 0)
    1048                 :          0 :                                         ret = -ERESTARTSYS;
    1049                 :            :                                 break;
    1050                 :            :                         }
    1051                 :          0 :                         schedule();
    1052                 :            :                 }
    1053                 :            : 
    1054                 :       2686 :                 extract_crng(tmp);
    1055                 :       2686 :                 i = min_t(int, nbytes, CHACHA_BLOCK_SIZE);
    1056   [ -  +  +  - ]:       5372 :                 if (copy_to_user(buf, tmp, i)) {
    1057                 :            :                         ret = -EFAULT;
    1058                 :            :                         break;
    1059                 :            :                 }
    1060                 :            : 
    1061                 :       2686 :                 nbytes -= i;
    1062                 :       2686 :                 buf += i;
    1063                 :       2686 :                 ret += i;
    1064                 :            :         }
    1065                 :       2609 :         crng_backtrack_protect(tmp, i);
    1066                 :            : 
    1067                 :            :         /* Wipe data just written to memory */
    1068                 :       2609 :         memzero_explicit(tmp, sizeof(tmp));
    1069                 :            : 
    1070                 :       2609 :         return ret;
    1071                 :            : }
    1072                 :            : 
    1073                 :            : 
    1074                 :            : /*********************************************************************
    1075                 :            :  *
    1076                 :            :  * Entropy input management
    1077                 :            :  *
    1078                 :            :  *********************************************************************/
    1079                 :            : 
    1080                 :            : /* There is one of these per entropy source */
    1081                 :            : struct timer_rand_state {
    1082                 :            :         cycles_t last_time;
    1083                 :            :         long last_delta, last_delta2;
    1084                 :            : };
    1085                 :            : 
    1086                 :            : #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
    1087                 :            : 
    1088                 :            : /*
    1089                 :            :  * Add device- or boot-specific data to the input pool to help
    1090                 :            :  * initialize it.
    1091                 :            :  *
    1092                 :            :  * None of this adds any entropy; it is meant to avoid the problem of
    1093                 :            :  * the entropy pool having similar initial state across largely
    1094                 :            :  * identical devices.
    1095                 :            :  */
    1096                 :      27203 : void add_device_randomness(const void *buf, unsigned int size)
    1097                 :            : {
    1098                 :      27203 :         unsigned long time = random_get_entropy() ^ jiffies;
    1099                 :      27203 :         unsigned long flags;
    1100                 :            : 
    1101   [ +  +  +  - ]:      27203 :         if (!crng_ready() && size)
    1102                 :       1270 :                 crng_slow_load(buf, size);
    1103                 :            : 
    1104                 :      27203 :         trace_add_device_randomness(size, _RET_IP_);
    1105                 :      27203 :         spin_lock_irqsave(&input_pool.lock, flags);
    1106                 :      27203 :         _mix_pool_bytes(&input_pool, buf, size);
    1107                 :      27203 :         _mix_pool_bytes(&input_pool, &time, sizeof(time));
    1108                 :      27203 :         spin_unlock_irqrestore(&input_pool.lock, flags);
    1109                 :      27203 : }
    1110                 :            : EXPORT_SYMBOL(add_device_randomness);
    1111                 :            : 
    1112                 :            : static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE;
    1113                 :            : 
    1114                 :            : /*
    1115                 :            :  * This function adds entropy to the entropy "pool" by using timing
    1116                 :            :  * delays.  It uses the timer_rand_state structure to make an estimate
    1117                 :            :  * of how many bits of entropy this call has added to the pool.
    1118                 :            :  *
    1119                 :            :  * The number "num" is also added to the pool - it should somehow describe
    1120                 :            :  * the type of event which just happened.  This is currently 0-255 for
    1121                 :            :  * keyboard scan codes, and 256 upwards for interrupts.
    1122                 :            :  *
    1123                 :            :  */
    1124                 :      10812 : static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
    1125                 :            : {
    1126                 :      10812 :         struct entropy_store    *r;
    1127                 :      10812 :         struct {
    1128                 :            :                 long jiffies;
    1129                 :            :                 unsigned cycles;
    1130                 :            :                 unsigned num;
    1131                 :            :         } sample;
    1132                 :      10812 :         long delta, delta2, delta3;
    1133                 :            : 
    1134                 :      10812 :         sample.jiffies = jiffies;
    1135                 :      10812 :         sample.cycles = random_get_entropy();
    1136                 :      10812 :         sample.num = num;
    1137                 :      10812 :         r = &input_pool;
    1138                 :      10812 :         mix_pool_bytes(r, &sample, sizeof(sample));
    1139                 :            : 
    1140                 :            :         /*
    1141                 :            :          * Calculate number of bits of randomness we probably added.
    1142                 :            :          * We take into account the first, second and third-order deltas
    1143                 :            :          * in order to make our estimate.
    1144                 :            :          */
    1145                 :      10812 :         delta = sample.jiffies - state->last_time;
    1146                 :      10812 :         state->last_time = sample.jiffies;
    1147                 :            : 
    1148                 :      10812 :         delta2 = delta - state->last_delta;
    1149                 :      10812 :         state->last_delta = delta;
    1150                 :            : 
    1151                 :      10812 :         delta3 = delta2 - state->last_delta2;
    1152                 :      10812 :         state->last_delta2 = delta2;
    1153                 :            : 
    1154                 :      10812 :         if (delta < 0)
    1155                 :            :                 delta = -delta;
    1156         [ +  + ]:      10812 :         if (delta2 < 0)
    1157                 :       3536 :                 delta2 = -delta2;
    1158         [ +  + ]:      10812 :         if (delta3 < 0)
    1159                 :       3664 :                 delta3 = -delta3;
    1160                 :      10812 :         if (delta > delta2)
    1161                 :            :                 delta = delta2;
    1162                 :      10812 :         if (delta > delta3)
    1163                 :            :                 delta = delta3;
    1164                 :            : 
    1165                 :            :         /*
    1166                 :            :          * delta is now minimum absolute delta.
    1167                 :            :          * Round down by 1 bit on general principles,
    1168                 :            :          * and limit entropy estimate to 12 bits.
    1169                 :            :          */
    1170                 :      10812 :         credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
    1171                 :      10812 : }
    1172                 :            : 
    1173                 :         11 : void add_input_randomness(unsigned int type, unsigned int code,
    1174                 :            :                                  unsigned int value)
    1175                 :            : {
    1176                 :         11 :         static unsigned char last_value;
    1177                 :            : 
    1178                 :            :         /* ignore autorepeat and the like */
    1179         [ +  - ]:         11 :         if (value == last_value)
    1180                 :            :                 return;
    1181                 :            : 
    1182                 :         11 :         last_value = value;
    1183                 :         11 :         add_timer_randomness(&input_timer_state,
    1184                 :         11 :                              (type << 4) ^ code ^ (code >> 4) ^ value);
    1185                 :         11 :         trace_add_input_randomness(ENTROPY_BITS(&input_pool));
    1186                 :            : }
    1187                 :            : EXPORT_SYMBOL_GPL(add_input_randomness);
    1188                 :            : 
    1189                 :            : static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
    1190                 :            : 
    1191                 :            : #ifdef ADD_INTERRUPT_BENCH
    1192                 :            : static unsigned long avg_cycles, avg_deviation;
    1193                 :            : 
    1194                 :            : #define AVG_SHIFT 8     /* Exponential average factor k=1/256 */
    1195                 :            : #define FIXED_1_2 (1 << (AVG_SHIFT-1))
    1196                 :            : 
    1197                 :            : static void add_interrupt_bench(cycles_t start)
    1198                 :            : {
    1199                 :            :         long delta = random_get_entropy() - start;
    1200                 :            : 
    1201                 :            :         /* Use a weighted moving average */
    1202                 :            :         delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT);
    1203                 :            :         avg_cycles += delta;
    1204                 :            :         /* And average deviation */
    1205                 :            :         delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT);
    1206                 :            :         avg_deviation += delta;
    1207                 :            : }
    1208                 :            : #else
    1209                 :            : #define add_interrupt_bench(x)
    1210                 :            : #endif
    1211                 :            : 
    1212                 :          0 : static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
    1213                 :            : {
    1214                 :          0 :         __u32 *ptr = (__u32 *) regs;
    1215                 :          0 :         unsigned int idx;
    1216                 :            : 
    1217                 :          0 :         if (regs == NULL)
    1218                 :            :                 return 0;
    1219         [ #  # ]:          0 :         idx = READ_ONCE(f->reg_idx);
    1220         [ #  # ]:          0 :         if (idx >= sizeof(struct pt_regs) / sizeof(__u32))
    1221                 :          0 :                 idx = 0;
    1222                 :          0 :         ptr += idx++;
    1223                 :          0 :         WRITE_ONCE(f->reg_idx, idx);
    1224                 :          0 :         return *ptr;
    1225                 :            : }
    1226                 :            : 
    1227                 :      27745 : void add_interrupt_randomness(int irq, int irq_flags)
    1228                 :            : {
    1229                 :      27745 :         struct entropy_store    *r;
    1230                 :      27745 :         struct fast_pool        *fast_pool = this_cpu_ptr(&irq_randomness);
    1231                 :      27745 :         struct pt_regs          *regs = get_irq_regs();
    1232                 :      27745 :         unsigned long           now = jiffies;
    1233                 :      27745 :         cycles_t                cycles = random_get_entropy();
    1234                 :      27745 :         __u32                   c_high, j_high;
    1235                 :      27745 :         __u64                   ip;
    1236                 :      27745 :         unsigned long           seed;
    1237                 :      27745 :         int                     credit = 0;
    1238                 :            : 
    1239         [ -  + ]:      27745 :         if (cycles == 0)
    1240         [ #  # ]:          0 :                 cycles = get_reg(fast_pool, regs);
    1241                 :      27745 :         c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
    1242                 :      27745 :         j_high = (sizeof(now) > 4) ? now >> 32 : 0;
    1243                 :      27745 :         fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
    1244                 :      27745 :         fast_pool->pool[1] ^= now ^ c_high;
    1245         [ +  - ]:      27745 :         ip = regs ? instruction_pointer(regs) : _RET_IP_;
    1246                 :      27745 :         fast_pool->pool[2] ^= ip;
    1247                 :      27745 :         fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
    1248                 :            :                 get_reg(fast_pool, regs);
    1249                 :            : 
    1250                 :      27745 :         fast_mix(fast_pool);
    1251                 :      27745 :         add_interrupt_bench(cycles);
    1252                 :            : 
    1253         [ +  + ]:      27745 :         if (unlikely(crng_init == 0)) {
    1254   [ +  +  +  - ]:       2860 :                 if ((fast_pool->count >= 64) &&
    1255                 :         44 :                     crng_fast_load((char *) fast_pool->pool,
    1256                 :            :                                    sizeof(fast_pool->pool))) {
    1257                 :         44 :                         fast_pool->count = 0;
    1258                 :         44 :                         fast_pool->last = now;
    1259                 :            :                 }
    1260                 :      27349 :                 return;
    1261                 :            :         }
    1262                 :            : 
    1263         [ +  + ]:      24929 :         if ((fast_pool->count < 64) &&
    1264         [ +  + ]:      24555 :             !time_after(now, fast_pool->last + HZ))
    1265                 :            :                 return;
    1266                 :            : 
    1267                 :        396 :         r = &input_pool;
    1268         [ +  - ]:        396 :         if (!spin_trylock(&r->lock))
    1269                 :            :                 return;
    1270                 :            : 
    1271                 :        396 :         fast_pool->last = now;
    1272                 :        396 :         __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
    1273                 :            : 
    1274                 :            :         /*
    1275                 :            :          * If we have architectural seed generator, produce a seed and
    1276                 :            :          * add it to the pool.  For the sake of paranoia don't let the
    1277                 :            :          * architectural seed generator dominate the input from the
    1278                 :            :          * interrupt noise.
    1279                 :            :          */
    1280         [ -  + ]:        396 :         if (arch_get_random_seed_long(&seed)) {
    1281                 :          0 :                 __mix_pool_bytes(r, &seed, sizeof(seed));
    1282                 :          0 :                 credit = 1;
    1283                 :            :         }
    1284                 :        396 :         spin_unlock(&r->lock);
    1285                 :            : 
    1286                 :        396 :         fast_pool->count = 0;
    1287                 :            : 
    1288                 :            :         /* award one bit for the contents of the fast pool */
    1289                 :        396 :         credit_entropy_bits(r, credit + 1);
    1290                 :            : }
    1291                 :            : EXPORT_SYMBOL_GPL(add_interrupt_randomness);
    1292                 :            : 
    1293                 :            : #ifdef CONFIG_BLOCK
    1294                 :      11681 : void add_disk_randomness(struct gendisk *disk)
    1295                 :            : {
    1296   [ +  +  +  - ]:      11681 :         if (!disk || !disk->random)
    1297                 :            :                 return;
    1298                 :            :         /* first major is 1, so we get >= 0x200 here */
    1299                 :      10801 :         add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
    1300                 :      10801 :         trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool));
    1301                 :            : }
    1302                 :            : EXPORT_SYMBOL_GPL(add_disk_randomness);
    1303                 :            : #endif
    1304                 :            : 
    1305                 :            : /*********************************************************************
    1306                 :            :  *
    1307                 :            :  * Entropy extraction routines
    1308                 :            :  *
    1309                 :            :  *********************************************************************/
    1310                 :            : 
    1311                 :            : /*
    1312                 :            :  * This function decides how many bytes to actually take from the
    1313                 :            :  * given pool, and also debits the entropy count accordingly.
    1314                 :            :  */
    1315                 :         11 : static size_t account(struct entropy_store *r, size_t nbytes, int min,
    1316                 :            :                       int reserved)
    1317                 :            : {
    1318                 :         11 :         int entropy_count, orig, have_bytes;
    1319                 :         11 :         size_t ibytes, nfrac;
    1320                 :            : 
    1321         [ -  + ]:         11 :         BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
    1322                 :            : 
    1323                 :            :         /* Can we pull enough? */
    1324                 :         11 : retry:
    1325         [ -  + ]:         11 :         entropy_count = orig = READ_ONCE(r->entropy_count);
    1326                 :         11 :         ibytes = nbytes;
    1327                 :            :         /* never pull more than available */
    1328                 :         11 :         have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
    1329                 :            : 
    1330                 :         11 :         if ((have_bytes -= reserved) < 0)
    1331                 :            :                 have_bytes = 0;
    1332                 :         11 :         ibytes = min_t(size_t, ibytes, have_bytes);
    1333         [ -  + ]:         11 :         if (ibytes < min)
    1334                 :          0 :                 ibytes = 0;
    1335                 :            : 
    1336   [ -  +  -  + ]:         11 :         if (WARN_ON(entropy_count < 0)) {
    1337                 :          0 :                 pr_warn("negative entropy count: pool %s count %d\n",
    1338                 :            :                         r->name, entropy_count);
    1339                 :          0 :                 entropy_count = 0;
    1340                 :            :         }
    1341                 :         11 :         nfrac = ibytes << (ENTROPY_SHIFT + 3);
    1342         [ +  + ]:         11 :         if ((size_t) entropy_count > nfrac)
    1343                 :         10 :                 entropy_count -= nfrac;
    1344                 :            :         else
    1345                 :            :                 entropy_count = 0;
    1346                 :            : 
    1347         [ -  + ]:         11 :         if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
    1348                 :          0 :                 goto retry;
    1349                 :            : 
    1350                 :         11 :         trace_debit_entropy(r->name, 8 * ibytes);
    1351   [ +  -  +  - ]:         11 :         if (ibytes && ENTROPY_BITS(r) < random_write_wakeup_bits) {
    1352                 :         11 :                 wake_up_interruptible(&random_write_wait);
    1353                 :         11 :                 kill_fasync(&fasync, SIGIO, POLL_OUT);
    1354                 :            :         }
    1355                 :            : 
    1356                 :         11 :         return ibytes;
    1357                 :            : }
    1358                 :            : 
    1359                 :            : /*
    1360                 :            :  * This function does the actual extraction for extract_entropy and
    1361                 :            :  * extract_entropy_user.
    1362                 :            :  *
    1363                 :            :  * Note: we assume that .poolwords is a multiple of 16 words.
    1364                 :            :  */
    1365                 :         77 : static void extract_buf(struct entropy_store *r, __u8 *out)
    1366                 :            : {
    1367                 :         77 :         int i;
    1368                 :         77 :         union {
    1369                 :            :                 __u32 w[5];
    1370                 :            :                 unsigned long l[LONGS(20)];
    1371                 :            :         } hash;
    1372                 :         77 :         __u32 workspace[SHA_WORKSPACE_WORDS];
    1373                 :         77 :         unsigned long flags;
    1374                 :            : 
    1375                 :            :         /*
    1376                 :            :          * If we have an architectural hardware random number
    1377                 :            :          * generator, use it for SHA's initial vector
    1378                 :            :          */
    1379                 :         77 :         sha_init(hash.w);
    1380         [ +  - ]:        154 :         for (i = 0; i < LONGS(20); i++) {
    1381                 :         77 :                 unsigned long v;
    1382         [ -  + ]:         77 :                 if (!arch_get_random_long(&v))
    1383                 :            :                         break;
    1384                 :          0 :                 hash.l[i] = v;
    1385                 :            :         }
    1386                 :            : 
    1387                 :            :         /* Generate a hash across the pool, 16 words (512 bits) at a time */
    1388                 :         77 :         spin_lock_irqsave(&r->lock, flags);
    1389         [ +  + ]:        770 :         for (i = 0; i < r->poolinfo->poolwords; i += 16)
    1390                 :        616 :                 sha_transform(hash.w, (__u8 *)(r->pool + i), workspace);
    1391                 :            : 
    1392                 :            :         /*
    1393                 :            :          * We mix the hash back into the pool to prevent backtracking
    1394                 :            :          * attacks (where the attacker knows the state of the pool
    1395                 :            :          * plus the current outputs, and attempts to find previous
    1396                 :            :          * ouputs), unless the hash function can be inverted. By
    1397                 :            :          * mixing at least a SHA1 worth of hash data back, we make
    1398                 :            :          * brute-forcing the feedback as hard as brute-forcing the
    1399                 :            :          * hash.
    1400                 :            :          */
    1401                 :         77 :         __mix_pool_bytes(r, hash.w, sizeof(hash.w));
    1402                 :         77 :         spin_unlock_irqrestore(&r->lock, flags);
    1403                 :            : 
    1404                 :         77 :         memzero_explicit(workspace, sizeof(workspace));
    1405                 :            : 
    1406                 :            :         /*
    1407                 :            :          * In case the hash function has some recognizable output
    1408                 :            :          * pattern, we fold it in half. Thus, we always feed back
    1409                 :            :          * twice as much data as we output.
    1410                 :            :          */
    1411                 :         77 :         hash.w[0] ^= hash.w[3];
    1412                 :         77 :         hash.w[1] ^= hash.w[4];
    1413                 :         77 :         hash.w[2] ^= rol32(hash.w[2], 16);
    1414                 :            : 
    1415                 :         77 :         memcpy(out, &hash, EXTRACT_SIZE);
    1416                 :         77 :         memzero_explicit(&hash, sizeof(hash));
    1417                 :         77 : }
    1418                 :            : 
    1419                 :         22 : static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
    1420                 :            :                                 size_t nbytes, int fips)
    1421                 :            : {
    1422                 :         22 :         ssize_t ret = 0, i;
    1423                 :         22 :         __u8 tmp[EXTRACT_SIZE];
    1424                 :         22 :         unsigned long flags;
    1425                 :            : 
    1426         [ +  + ]:         99 :         while (nbytes) {
    1427                 :         77 :                 extract_buf(r, tmp);
    1428                 :            : 
    1429         [ -  + ]:         77 :                 if (fips) {
    1430                 :          0 :                         spin_lock_irqsave(&r->lock, flags);
    1431         [ #  # ]:          0 :                         if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
    1432                 :          0 :                                 panic("Hardware RNG duplicated output!\n");
    1433                 :          0 :                         memcpy(r->last_data, tmp, EXTRACT_SIZE);
    1434                 :          0 :                         spin_unlock_irqrestore(&r->lock, flags);
    1435                 :            :                 }
    1436                 :         77 :                 i = min_t(int, nbytes, EXTRACT_SIZE);
    1437                 :         77 :                 memcpy(buf, tmp, i);
    1438                 :         77 :                 nbytes -= i;
    1439                 :         77 :                 buf += i;
    1440                 :         77 :                 ret += i;
    1441                 :            :         }
    1442                 :            : 
    1443                 :            :         /* Wipe data just returned from memory */
    1444                 :         22 :         memzero_explicit(tmp, sizeof(tmp));
    1445                 :            : 
    1446                 :         22 :         return ret;
    1447                 :            : }
    1448                 :            : 
    1449                 :            : /*
    1450                 :            :  * This function extracts randomness from the "entropy pool", and
    1451                 :            :  * returns it in a buffer.
    1452                 :            :  *
    1453                 :            :  * The min parameter specifies the minimum amount we can pull before
    1454                 :            :  * failing to avoid races that defeat catastrophic reseeding while the
    1455                 :            :  * reserved parameter indicates how much entropy we must leave in the
    1456                 :            :  * pool after each pull to avoid starving other readers.
    1457                 :            :  */
    1458                 :         11 : static ssize_t extract_entropy(struct entropy_store *r, void *buf,
    1459                 :            :                                  size_t nbytes, int min, int reserved)
    1460                 :            : {
    1461                 :         11 :         __u8 tmp[EXTRACT_SIZE];
    1462                 :         11 :         unsigned long flags;
    1463                 :            : 
    1464                 :            :         /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
    1465                 :         11 :         if (fips_enabled) {
    1466                 :            :                 spin_lock_irqsave(&r->lock, flags);
    1467                 :            :                 if (!r->last_data_init) {
    1468                 :            :                         r->last_data_init = 1;
    1469                 :            :                         spin_unlock_irqrestore(&r->lock, flags);
    1470                 :            :                         trace_extract_entropy(r->name, EXTRACT_SIZE,
    1471                 :            :                                               ENTROPY_BITS(r), _RET_IP_);
    1472                 :            :                         extract_buf(r, tmp);
    1473                 :            :                         spin_lock_irqsave(&r->lock, flags);
    1474                 :            :                         memcpy(r->last_data, tmp, EXTRACT_SIZE);
    1475                 :            :                 }
    1476                 :            :                 spin_unlock_irqrestore(&r->lock, flags);
    1477                 :            :         }
    1478                 :            : 
    1479                 :         11 :         trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
    1480                 :         11 :         nbytes = account(r, nbytes, min, reserved);
    1481                 :            : 
    1482                 :         11 :         return _extract_entropy(r, buf, nbytes, fips_enabled);
    1483                 :            : }
    1484                 :            : 
    1485                 :            : #define warn_unseeded_randomness(previous) \
    1486                 :            :         _warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous))
    1487                 :            : 
    1488                 :     269873 : static void _warn_unseeded_randomness(const char *func_name, void *caller,
    1489                 :            :                                       void **previous)
    1490                 :            : {
    1491                 :            : #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
    1492                 :            :         const bool print_once = false;
    1493                 :            : #else
    1494                 :     269873 :         static bool print_once __read_mostly;
    1495                 :            : #endif
    1496                 :            : 
    1497         [ +  + ]:     269873 :         if (print_once ||
    1498   [ +  -  +  - ]:         11 :             crng_ready() ||
    1499         [ +  - ]:         11 :             (previous && (caller == READ_ONCE(*previous))))
    1500                 :            :                 return;
    1501                 :         11 :         WRITE_ONCE(*previous, caller);
    1502                 :            : #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
    1503                 :         11 :         print_once = true;
    1504                 :            : #endif
    1505         [ +  - ]:         11 :         if (__ratelimit(&unseeded_warning))
    1506                 :         11 :                 printk_deferred(KERN_NOTICE "random: %s called from %pS "
    1507                 :            :                                 "with crng_init=%d\n", func_name, caller,
    1508                 :            :                                 crng_init);
    1509                 :            : }
    1510                 :            : 
    1511                 :            : /*
    1512                 :            :  * This function is the exported kernel interface.  It returns some
    1513                 :            :  * number of good random numbers, suitable for key generation, seeding
    1514                 :            :  * TCP sequence numbers, etc.  It does not rely on the hardware random
    1515                 :            :  * number generator.  For random bytes direct from the hardware RNG
    1516                 :            :  * (when available), use get_random_bytes_arch(). In order to ensure
    1517                 :            :  * that the randomness provided by this function is okay, the function
    1518                 :            :  * wait_for_random_bytes() should be called and return 0 at least once
    1519                 :            :  * at any point prior.
    1520                 :            :  */
    1521                 :      28122 : static void _get_random_bytes(void *buf, int nbytes)
    1522                 :            : {
    1523                 :      28122 :         __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
    1524                 :            : 
    1525                 :      28122 :         trace_get_random_bytes(nbytes, _RET_IP_);
    1526                 :            : 
    1527         [ -  + ]:      28122 :         while (nbytes >= CHACHA_BLOCK_SIZE) {
    1528                 :          0 :                 extract_crng(buf);
    1529                 :          0 :                 buf += CHACHA_BLOCK_SIZE;
    1530                 :          0 :                 nbytes -= CHACHA_BLOCK_SIZE;
    1531                 :            :         }
    1532                 :            : 
    1533         [ +  - ]:      28122 :         if (nbytes > 0) {
    1534                 :      28122 :                 extract_crng(tmp);
    1535                 :      28122 :                 memcpy(buf, tmp, nbytes);
    1536                 :      28122 :                 crng_backtrack_protect(tmp, nbytes);
    1537                 :            :         } else
    1538                 :          0 :                 crng_backtrack_protect(tmp, CHACHA_BLOCK_SIZE);
    1539                 :      28122 :         memzero_explicit(tmp, sizeof(tmp));
    1540                 :      28122 : }
    1541                 :            : 
    1542                 :      28111 : void get_random_bytes(void *buf, int nbytes)
    1543                 :            : {
    1544                 :      28111 :         static void *previous;
    1545                 :            : 
    1546                 :      28111 :         warn_unseeded_randomness(&previous);
    1547                 :      28111 :         _get_random_bytes(buf, nbytes);
    1548                 :      28111 : }
    1549                 :            : EXPORT_SYMBOL(get_random_bytes);
    1550                 :            : 
    1551                 :            : 
    1552                 :            : /*
    1553                 :            :  * Each time the timer fires, we expect that we got an unpredictable
    1554                 :            :  * jump in the cycle counter. Even if the timer is running on another
    1555                 :            :  * CPU, the timer activity will be touching the stack of the CPU that is
    1556                 :            :  * generating entropy..
    1557                 :            :  *
    1558                 :            :  * Note that we don't re-arm the timer in the timer itself - we are
    1559                 :            :  * happy to be scheduled away, since that just makes the load more
    1560                 :            :  * complex, but we do not want the timer to keep ticking unless the
    1561                 :            :  * entropy loop is running.
    1562                 :            :  *
    1563                 :            :  * So the re-arming always happens in the entropy loop itself.
    1564                 :            :  */
    1565                 :          0 : static void entropy_timer(struct timer_list *t)
    1566                 :            : {
    1567                 :          0 :         credit_entropy_bits(&input_pool, 1);
    1568                 :          0 : }
    1569                 :            : 
    1570                 :            : /*
    1571                 :            :  * If we have an actual cycle counter, see if we can
    1572                 :            :  * generate enough entropy with timing noise
    1573                 :            :  */
    1574                 :          0 : static void try_to_generate_entropy(void)
    1575                 :            : {
    1576                 :          0 :         struct {
    1577                 :            :                 unsigned long now;
    1578                 :            :                 struct timer_list timer;
    1579                 :            :         } stack;
    1580                 :            : 
    1581                 :          0 :         stack.now = random_get_entropy();
    1582                 :            : 
    1583                 :            :         /* Slow counter - or none. Don't even bother */
    1584         [ #  # ]:          0 :         if (stack.now == random_get_entropy())
    1585                 :          0 :                 return;
    1586                 :            : 
    1587                 :          0 :         timer_setup_on_stack(&stack.timer, entropy_timer, 0);
    1588         [ #  # ]:          0 :         while (!crng_ready()) {
    1589         [ #  # ]:          0 :                 if (!timer_pending(&stack.timer))
    1590                 :          0 :                         mod_timer(&stack.timer, jiffies+1);
    1591                 :          0 :                 mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now));
    1592                 :          0 :                 schedule();
    1593                 :          0 :                 stack.now = random_get_entropy();
    1594                 :            :         }
    1595                 :            : 
    1596                 :          0 :         del_timer_sync(&stack.timer);
    1597                 :          0 :         destroy_timer_on_stack(&stack.timer);
    1598                 :          0 :         mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now));
    1599                 :            : }
    1600                 :            : 
    1601                 :            : /*
    1602                 :            :  * Wait for the urandom pool to be seeded and thus guaranteed to supply
    1603                 :            :  * cryptographically secure random numbers. This applies to: the /dev/urandom
    1604                 :            :  * device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
    1605                 :            :  * family of functions. Using any of these functions without first calling
    1606                 :            :  * this function forfeits the guarantee of security.
    1607                 :            :  *
    1608                 :            :  * Returns: 0 if the urandom pool has been seeded.
    1609                 :            :  *          -ERESTARTSYS if the function was interrupted by a signal.
    1610                 :            :  */
    1611                 :          0 : int wait_for_random_bytes(void)
    1612                 :            : {
    1613         [ #  # ]:          0 :         if (likely(crng_ready()))
    1614                 :            :                 return 0;
    1615                 :            : 
    1616                 :          0 :         do {
    1617                 :          0 :                 int ret;
    1618   [ #  #  #  #  :          0 :                 ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
             #  #  #  # ]
    1619         [ #  # ]:          0 :                 if (ret)
    1620                 :          0 :                         return ret > 0 ? 0 : ret;
    1621                 :            : 
    1622                 :          0 :                 try_to_generate_entropy();
    1623         [ #  # ]:          0 :         } while (!crng_ready());
    1624                 :            : 
    1625                 :            :         return 0;
    1626                 :            : }
    1627                 :            : EXPORT_SYMBOL(wait_for_random_bytes);
    1628                 :            : 
    1629                 :            : /*
    1630                 :            :  * Returns whether or not the urandom pool has been seeded and thus guaranteed
    1631                 :            :  * to supply cryptographically secure random numbers. This applies to: the
    1632                 :            :  * /dev/urandom device, the get_random_bytes function, and the get_random_{u32,
    1633                 :            :  * ,u64,int,long} family of functions.
    1634                 :            :  *
    1635                 :            :  * Returns: true if the urandom pool has been seeded.
    1636                 :            :  *          false if the urandom pool has not been seeded.
    1637                 :            :  */
    1638                 :          0 : bool rng_is_initialized(void)
    1639                 :            : {
    1640                 :          0 :         return crng_ready();
    1641                 :            : }
    1642                 :            : EXPORT_SYMBOL(rng_is_initialized);
    1643                 :            : 
    1644                 :            : /*
    1645                 :            :  * Add a callback function that will be invoked when the nonblocking
    1646                 :            :  * pool is initialised.
    1647                 :            :  *
    1648                 :            :  * returns: 0 if callback is successfully added
    1649                 :            :  *          -EALREADY if pool is already initialised (callback not called)
    1650                 :            :  *          -ENOENT if module for callback is not alive
    1651                 :            :  */
    1652                 :         11 : int add_random_ready_callback(struct random_ready_callback *rdy)
    1653                 :            : {
    1654                 :         11 :         struct module *owner;
    1655                 :         11 :         unsigned long flags;
    1656                 :         11 :         int err = -EALREADY;
    1657                 :            : 
    1658         [ +  - ]:         11 :         if (crng_ready())
    1659                 :            :                 return err;
    1660                 :            : 
    1661                 :         11 :         owner = rdy->owner;
    1662         [ +  - ]:         11 :         if (!try_module_get(owner))
    1663                 :            :                 return -ENOENT;
    1664                 :            : 
    1665                 :         11 :         spin_lock_irqsave(&random_ready_list_lock, flags);
    1666         [ -  + ]:         11 :         if (crng_ready())
    1667                 :          0 :                 goto out;
    1668                 :            : 
    1669                 :         11 :         owner = NULL;
    1670                 :            : 
    1671                 :         11 :         list_add(&rdy->list, &random_ready_list);
    1672                 :         11 :         err = 0;
    1673                 :            : 
    1674                 :         11 : out:
    1675                 :         11 :         spin_unlock_irqrestore(&random_ready_list_lock, flags);
    1676                 :            : 
    1677                 :         11 :         module_put(owner);
    1678                 :            : 
    1679                 :         11 :         return err;
    1680                 :            : }
    1681                 :            : EXPORT_SYMBOL(add_random_ready_callback);
    1682                 :            : 
    1683                 :            : /*
    1684                 :            :  * Delete a previously registered readiness callback function.
    1685                 :            :  */
    1686                 :          0 : void del_random_ready_callback(struct random_ready_callback *rdy)
    1687                 :            : {
    1688                 :          0 :         unsigned long flags;
    1689                 :          0 :         struct module *owner = NULL;
    1690                 :            : 
    1691                 :          0 :         spin_lock_irqsave(&random_ready_list_lock, flags);
    1692         [ #  # ]:          0 :         if (!list_empty(&rdy->list)) {
    1693                 :          0 :                 list_del_init(&rdy->list);
    1694                 :          0 :                 owner = rdy->owner;
    1695                 :            :         }
    1696                 :          0 :         spin_unlock_irqrestore(&random_ready_list_lock, flags);
    1697                 :            : 
    1698                 :          0 :         module_put(owner);
    1699                 :          0 : }
    1700                 :            : EXPORT_SYMBOL(del_random_ready_callback);
    1701                 :            : 
    1702                 :            : /*
    1703                 :            :  * This function will use the architecture-specific hardware random
    1704                 :            :  * number generator if it is available.  The arch-specific hw RNG will
    1705                 :            :  * almost certainly be faster than what we can do in software, but it
    1706                 :            :  * is impossible to verify that it is implemented securely (as
    1707                 :            :  * opposed, to, say, the AES encryption of a sequence number using a
    1708                 :            :  * key known by the NSA).  So it's useful if we need the speed, but
    1709                 :            :  * only if we're willing to trust the hardware manufacturer not to
    1710                 :            :  * have put in a back door.
    1711                 :            :  *
    1712                 :            :  * Return number of bytes filled in.
    1713                 :            :  */
    1714                 :         11 : int __must_check get_random_bytes_arch(void *buf, int nbytes)
    1715                 :            : {
    1716                 :         11 :         int left = nbytes;
    1717                 :         11 :         char *p = buf;
    1718                 :            : 
    1719                 :         11 :         trace_get_random_bytes_arch(left, _RET_IP_);
    1720         [ +  - ]:         11 :         while (left) {
    1721                 :         11 :                 unsigned long v;
    1722                 :         11 :                 int chunk = min_t(int, left, sizeof(unsigned long));
    1723                 :            : 
    1724         [ -  + ]:         11 :                 if (!arch_get_random_long(&v))
    1725                 :            :                         break;
    1726                 :            : 
    1727                 :          0 :                 memcpy(p, &v, chunk);
    1728                 :          0 :                 p += chunk;
    1729                 :          0 :                 left -= chunk;
    1730                 :            :         }
    1731                 :            : 
    1732                 :         11 :         return nbytes - left;
    1733                 :            : }
    1734                 :            : EXPORT_SYMBOL(get_random_bytes_arch);
    1735                 :            : 
    1736                 :            : /*
    1737                 :            :  * init_std_data - initialize pool with system data
    1738                 :            :  *
    1739                 :            :  * @r: pool to initialize
    1740                 :            :  *
    1741                 :            :  * This function clears the pool's entropy count and mixes some system
    1742                 :            :  * data into the pool to prepare it for use. The pool is not cleared
    1743                 :            :  * as that can only decrease the entropy in the pool.
    1744                 :            :  */
    1745                 :         11 : static void __init init_std_data(struct entropy_store *r)
    1746                 :            : {
    1747                 :         11 :         int i;
    1748                 :         11 :         ktime_t now = ktime_get_real();
    1749                 :         11 :         unsigned long rv;
    1750                 :            : 
    1751                 :         11 :         mix_pool_bytes(r, &now, sizeof(now));
    1752         [ +  + ]:        715 :         for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
    1753   [ +  -  +  - ]:       1408 :                 if (!arch_get_random_seed_long(&rv) &&
    1754                 :        704 :                     !arch_get_random_long(&rv))
    1755                 :        704 :                         rv = random_get_entropy();
    1756                 :        704 :                 mix_pool_bytes(r, &rv, sizeof(rv));
    1757                 :            :         }
    1758                 :         11 :         mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
    1759                 :         11 : }
    1760                 :            : 
    1761                 :            : /*
    1762                 :            :  * Note that setup_arch() may call add_device_randomness()
    1763                 :            :  * long before we get here. This allows seeding of the pools
    1764                 :            :  * with some platform dependent data very early in the boot
    1765                 :            :  * process. But it limits our options here. We must use
    1766                 :            :  * statically allocated structures that already have all
    1767                 :            :  * initializations complete at compile time. We should also
    1768                 :            :  * take care not to overwrite the precious per platform data
    1769                 :            :  * we were given.
    1770                 :            :  */
    1771                 :         11 : int __init rand_initialize(void)
    1772                 :            : {
    1773                 :         11 :         init_std_data(&input_pool);
    1774                 :         11 :         crng_initialize(&primary_crng);
    1775                 :         11 :         crng_global_init_time = jiffies;
    1776         [ -  + ]:         11 :         if (ratelimit_disable) {
    1777                 :          0 :                 urandom_warning.interval = 0;
    1778                 :          0 :                 unseeded_warning.interval = 0;
    1779                 :            :         }
    1780                 :         11 :         return 0;
    1781                 :            : }
    1782                 :            : 
    1783                 :            : #ifdef CONFIG_BLOCK
    1784                 :        165 : void rand_initialize_disk(struct gendisk *disk)
    1785                 :            : {
    1786                 :        165 :         struct timer_rand_state *state;
    1787                 :            : 
    1788                 :            :         /*
    1789                 :            :          * If kzalloc returns null, we just won't use that entropy
    1790                 :            :          * source.
    1791                 :            :          */
    1792                 :        165 :         state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
    1793         [ +  - ]:        165 :         if (state) {
    1794                 :        165 :                 state->last_time = INITIAL_JIFFIES;
    1795                 :        165 :                 disk->random = state;
    1796                 :            :         }
    1797                 :        165 : }
    1798                 :            : #endif
    1799                 :            : 
    1800                 :            : static ssize_t
    1801                 :            : urandom_read_nowarn(struct file *file, char __user *buf, size_t nbytes,
    1802                 :            :                     loff_t *ppos)
    1803                 :            : {
    1804                 :            :         int ret;
    1805                 :            : 
    1806                 :            :         nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
    1807                 :            :         ret = extract_crng_user(buf, nbytes);
    1808                 :            :         trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool));
    1809                 :            :         return ret;
    1810                 :            : }
    1811                 :            : 
    1812                 :            : static ssize_t
    1813                 :        933 : urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
    1814                 :            : {
    1815                 :        933 :         unsigned long flags;
    1816                 :        933 :         static int maxwarn = 10;
    1817                 :            : 
    1818   [ +  +  +  + ]:        933 :         if (!crng_ready() && maxwarn > 0) {
    1819                 :        110 :                 maxwarn--;
    1820         [ +  + ]:        110 :                 if (__ratelimit(&urandom_warning))
    1821                 :         33 :                         pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",
    1822                 :            :                                   current->comm, nbytes);
    1823                 :        110 :                 spin_lock_irqsave(&primary_crng.lock, flags);
    1824                 :        110 :                 crng_init_cnt = 0;
    1825                 :        110 :                 spin_unlock_irqrestore(&primary_crng.lock, flags);
    1826                 :            :         }
    1827                 :            : 
    1828                 :        933 :         return urandom_read_nowarn(file, buf, nbytes, ppos);
    1829                 :            : }
    1830                 :            : 
    1831                 :            : static ssize_t
    1832                 :          0 : random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
    1833                 :            : {
    1834                 :          0 :         int ret;
    1835                 :            : 
    1836                 :          0 :         ret = wait_for_random_bytes();
    1837         [ #  # ]:          0 :         if (ret != 0)
    1838                 :          0 :                 return ret;
    1839                 :          0 :         return urandom_read_nowarn(file, buf, nbytes, ppos);
    1840                 :            : }
    1841                 :            : 
    1842                 :            : static __poll_t
    1843                 :          0 : random_poll(struct file *file, poll_table * wait)
    1844                 :            : {
    1845                 :          0 :         __poll_t mask;
    1846                 :            : 
    1847         [ #  # ]:          0 :         poll_wait(file, &crng_init_wait, wait);
    1848         [ #  # ]:          0 :         poll_wait(file, &random_write_wait, wait);
    1849                 :          0 :         mask = 0;
    1850         [ #  # ]:          0 :         if (crng_ready())
    1851                 :          0 :                 mask |= EPOLLIN | EPOLLRDNORM;
    1852         [ #  # ]:          0 :         if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
    1853                 :          0 :                 mask |= EPOLLOUT | EPOLLWRNORM;
    1854                 :          0 :         return mask;
    1855                 :            : }
    1856                 :            : 
    1857                 :            : static int
    1858                 :         11 : write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
    1859                 :            : {
    1860                 :         11 :         size_t bytes;
    1861                 :         11 :         __u32 t, buf[16];
    1862                 :         11 :         const char __user *p = buffer;
    1863                 :            : 
    1864         [ +  + ]:         22 :         while (count > 0) {
    1865                 :         11 :                 int b, i = 0;
    1866                 :            : 
    1867                 :         11 :                 bytes = min(count, sizeof(buf));
    1868         [ +  - ]:         11 :                 if (copy_from_user(&buf, p, bytes))
    1869                 :            :                         return -EFAULT;
    1870                 :            : 
    1871         [ +  - ]:         11 :                 for (b = bytes ; b > 0 ; b -= sizeof(__u32), i++) {
    1872         [ -  + ]:         11 :                         if (!arch_get_random_int(&t))
    1873                 :            :                                 break;
    1874                 :          0 :                         buf[i] ^= t;
    1875                 :            :                 }
    1876                 :            : 
    1877                 :         11 :                 count -= bytes;
    1878                 :         11 :                 p += bytes;
    1879                 :            : 
    1880                 :         11 :                 mix_pool_bytes(r, buf, bytes);
    1881                 :         11 :                 cond_resched();
    1882                 :            :         }
    1883                 :            : 
    1884                 :            :         return 0;
    1885                 :            : }
    1886                 :            : 
    1887                 :         11 : static ssize_t random_write(struct file *file, const char __user *buffer,
    1888                 :            :                             size_t count, loff_t *ppos)
    1889                 :            : {
    1890                 :         11 :         size_t ret;
    1891                 :            : 
    1892                 :         11 :         ret = write_pool(&input_pool, buffer, count);
    1893         [ -  + ]:         11 :         if (ret)
    1894                 :          0 :                 return ret;
    1895                 :            : 
    1896                 :         11 :         return (ssize_t)count;
    1897                 :            : }
    1898                 :            : 
    1899                 :          0 : static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
    1900                 :            : {
    1901                 :          0 :         int size, ent_count;
    1902                 :          0 :         int __user *p = (int __user *)arg;
    1903                 :          0 :         int retval;
    1904                 :            : 
    1905   [ #  #  #  #  :          0 :         switch (cmd) {
                   #  # ]
    1906                 :          0 :         case RNDGETENTCNT:
    1907                 :            :                 /* inherently racy, no point locking */
    1908                 :          0 :                 ent_count = ENTROPY_BITS(&input_pool);
    1909         [ #  # ]:          0 :                 if (put_user(ent_count, p))
    1910                 :          0 :                         return -EFAULT;
    1911                 :            :                 return 0;
    1912                 :          0 :         case RNDADDTOENTCNT:
    1913         [ #  # ]:          0 :                 if (!capable(CAP_SYS_ADMIN))
    1914                 :            :                         return -EPERM;
    1915         [ #  # ]:          0 :                 if (get_user(ent_count, p))
    1916                 :            :                         return -EFAULT;
    1917         [ #  # ]:          0 :                 return credit_entropy_bits_safe(&input_pool, ent_count);
    1918                 :          0 :         case RNDADDENTROPY:
    1919         [ #  # ]:          0 :                 if (!capable(CAP_SYS_ADMIN))
    1920                 :            :                         return -EPERM;
    1921         [ #  # ]:          0 :                 if (get_user(ent_count, p++))
    1922                 :            :                         return -EFAULT;
    1923         [ #  # ]:          0 :                 if (ent_count < 0)
    1924                 :            :                         return -EINVAL;
    1925         [ #  # ]:          0 :                 if (get_user(size, p++))
    1926                 :            :                         return -EFAULT;
    1927                 :          0 :                 retval = write_pool(&input_pool, (const char __user *)p,
    1928                 :            :                                     size);
    1929         [ #  # ]:          0 :                 if (retval < 0)
    1930                 :          0 :                         return retval;
    1931                 :          0 :                 return credit_entropy_bits_safe(&input_pool, ent_count);
    1932                 :          0 :         case RNDZAPENTCNT:
    1933                 :            :         case RNDCLEARPOOL:
    1934                 :            :                 /*
    1935                 :            :                  * Clear the entropy pool counters. We no longer clear
    1936                 :            :                  * the entropy pool, as that's silly.
    1937                 :            :                  */
    1938         [ #  # ]:          0 :                 if (!capable(CAP_SYS_ADMIN))
    1939                 :            :                         return -EPERM;
    1940                 :          0 :                 input_pool.entropy_count = 0;
    1941                 :          0 :                 return 0;
    1942                 :          0 :         case RNDRESEEDCRNG:
    1943         [ #  # ]:          0 :                 if (!capable(CAP_SYS_ADMIN))
    1944                 :            :                         return -EPERM;
    1945         [ #  # ]:          0 :                 if (crng_init < 2)
    1946                 :            :                         return -ENODATA;
    1947                 :          0 :                 crng_reseed(&primary_crng, NULL);
    1948                 :          0 :                 crng_global_init_time = jiffies - 1;
    1949                 :          0 :                 return 0;
    1950                 :            :         default:
    1951                 :            :                 return -EINVAL;
    1952                 :            :         }
    1953                 :            : }
    1954                 :            : 
    1955                 :          0 : static int random_fasync(int fd, struct file *filp, int on)
    1956                 :            : {
    1957                 :          0 :         return fasync_helper(fd, filp, on, &fasync);
    1958                 :            : }
    1959                 :            : 
    1960                 :            : const struct file_operations random_fops = {
    1961                 :            :         .read  = random_read,
    1962                 :            :         .write = random_write,
    1963                 :            :         .poll  = random_poll,
    1964                 :            :         .unlocked_ioctl = random_ioctl,
    1965                 :            :         .compat_ioctl = compat_ptr_ioctl,
    1966                 :            :         .fasync = random_fasync,
    1967                 :            :         .llseek = noop_llseek,
    1968                 :            : };
    1969                 :            : 
    1970                 :            : const struct file_operations urandom_fops = {
    1971                 :            :         .read  = urandom_read,
    1972                 :            :         .write = random_write,
    1973                 :            :         .unlocked_ioctl = random_ioctl,
    1974                 :            :         .compat_ioctl = compat_ptr_ioctl,
    1975                 :            :         .fasync = random_fasync,
    1976                 :            :         .llseek = noop_llseek,
    1977                 :            : };
    1978                 :            : 
    1979                 :      66990 : SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
    1980                 :            :                 unsigned int, flags)
    1981                 :            : {
    1982                 :      33495 :         int ret;
    1983                 :            : 
    1984         [ +  - ]:      33495 :         if (flags & ~(GRND_NONBLOCK|GRND_RANDOM|GRND_INSECURE))
    1985                 :            :                 return -EINVAL;
    1986                 :            : 
    1987                 :            :         /*
    1988                 :            :          * Requesting insecure and blocking randomness at the same time makes
    1989                 :            :          * no sense.
    1990                 :            :          */
    1991         [ +  - ]:      33495 :         if ((flags & (GRND_INSECURE|GRND_RANDOM)) == (GRND_INSECURE|GRND_RANDOM))
    1992                 :            :                 return -EINVAL;
    1993                 :            : 
    1994                 :      33495 :         if (count > INT_MAX)
    1995                 :            :                 count = INT_MAX;
    1996                 :            : 
    1997   [ +  -  +  + ]:      33495 :         if (!(flags & GRND_INSECURE) && !crng_ready()) {
    1998         [ -  + ]:      31819 :                 if (flags & GRND_NONBLOCK)
    1999                 :            :                         return -EAGAIN;
    2000                 :          0 :                 ret = wait_for_random_bytes();
    2001         [ #  # ]:          0 :                 if (unlikely(ret))
    2002                 :          0 :                         return ret;
    2003                 :            :         }
    2004                 :       1676 :         return urandom_read_nowarn(NULL, buf, count, NULL);
    2005                 :            : }
    2006                 :            : 
    2007                 :            : /********************************************************************
    2008                 :            :  *
    2009                 :            :  * Sysctl interface
    2010                 :            :  *
    2011                 :            :  ********************************************************************/
    2012                 :            : 
    2013                 :            : #ifdef CONFIG_SYSCTL
    2014                 :            : 
    2015                 :            : #include <linux/sysctl.h>
    2016                 :            : 
    2017                 :            : static int min_write_thresh;
    2018                 :            : static int max_write_thresh = INPUT_POOL_WORDS * 32;
    2019                 :            : static int random_min_urandom_seed = 60;
    2020                 :            : static char sysctl_bootid[16];
    2021                 :            : 
    2022                 :            : /*
    2023                 :            :  * This function is used to return both the bootid UUID, and random
    2024                 :            :  * UUID.  The difference is in whether table->data is NULL; if it is,
    2025                 :            :  * then a new UUID is generated and returned to the user.
    2026                 :            :  *
    2027                 :            :  * If the user accesses this via the proc interface, the UUID will be
    2028                 :            :  * returned as an ASCII string in the standard UUID format; if via the
    2029                 :            :  * sysctl system call, as 16 bytes of binary data.
    2030                 :            :  */
    2031                 :        132 : static int proc_do_uuid(struct ctl_table *table, int write,
    2032                 :            :                         void __user *buffer, size_t *lenp, loff_t *ppos)
    2033                 :            : {
    2034                 :        132 :         struct ctl_table fake_table;
    2035                 :        132 :         unsigned char buf[64], tmp_uuid[16], *uuid;
    2036                 :            : 
    2037                 :        132 :         uuid = table->data;
    2038         [ -  + ]:        132 :         if (!uuid) {
    2039                 :          0 :                 uuid = tmp_uuid;
    2040                 :          0 :                 generate_random_uuid(uuid);
    2041                 :            :         } else {
    2042                 :        132 :                 static DEFINE_SPINLOCK(bootid_spinlock);
    2043                 :            : 
    2044                 :        132 :                 spin_lock(&bootid_spinlock);
    2045         [ +  + ]:        132 :                 if (!uuid[8])
    2046                 :         11 :                         generate_random_uuid(uuid);
    2047                 :        132 :                 spin_unlock(&bootid_spinlock);
    2048                 :            :         }
    2049                 :            : 
    2050                 :        132 :         sprintf(buf, "%pU", uuid);
    2051                 :            : 
    2052                 :        132 :         fake_table.data = buf;
    2053                 :        132 :         fake_table.maxlen = sizeof(buf);
    2054                 :            : 
    2055                 :        132 :         return proc_dostring(&fake_table, write, buffer, lenp, ppos);
    2056                 :            : }
    2057                 :            : 
    2058                 :            : /*
    2059                 :            :  * Return entropy available scaled to integral bits
    2060                 :            :  */
    2061                 :          0 : static int proc_do_entropy(struct ctl_table *table, int write,
    2062                 :            :                            void __user *buffer, size_t *lenp, loff_t *ppos)
    2063                 :            : {
    2064                 :          0 :         struct ctl_table fake_table;
    2065                 :          0 :         int entropy_count;
    2066                 :            : 
    2067                 :          0 :         entropy_count = *(int *)table->data >> ENTROPY_SHIFT;
    2068                 :            : 
    2069                 :          0 :         fake_table.data = &entropy_count;
    2070                 :          0 :         fake_table.maxlen = sizeof(entropy_count);
    2071                 :            : 
    2072                 :          0 :         return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
    2073                 :            : }
    2074                 :            : 
    2075                 :            : static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
    2076                 :            : extern struct ctl_table random_table[];
    2077                 :            : struct ctl_table random_table[] = {
    2078                 :            :         {
    2079                 :            :                 .procname       = "poolsize",
    2080                 :            :                 .data           = &sysctl_poolsize,
    2081                 :            :                 .maxlen         = sizeof(int),
    2082                 :            :                 .mode           = 0444,
    2083                 :            :                 .proc_handler   = proc_dointvec,
    2084                 :            :         },
    2085                 :            :         {
    2086                 :            :                 .procname       = "entropy_avail",
    2087                 :            :                 .maxlen         = sizeof(int),
    2088                 :            :                 .mode           = 0444,
    2089                 :            :                 .proc_handler   = proc_do_entropy,
    2090                 :            :                 .data           = &input_pool.entropy_count,
    2091                 :            :         },
    2092                 :            :         {
    2093                 :            :                 .procname       = "write_wakeup_threshold",
    2094                 :            :                 .data           = &random_write_wakeup_bits,
    2095                 :            :                 .maxlen         = sizeof(int),
    2096                 :            :                 .mode           = 0644,
    2097                 :            :                 .proc_handler   = proc_dointvec_minmax,
    2098                 :            :                 .extra1         = &min_write_thresh,
    2099                 :            :                 .extra2         = &max_write_thresh,
    2100                 :            :         },
    2101                 :            :         {
    2102                 :            :                 .procname       = "urandom_min_reseed_secs",
    2103                 :            :                 .data           = &random_min_urandom_seed,
    2104                 :            :                 .maxlen         = sizeof(int),
    2105                 :            :                 .mode           = 0644,
    2106                 :            :                 .proc_handler   = proc_dointvec,
    2107                 :            :         },
    2108                 :            :         {
    2109                 :            :                 .procname       = "boot_id",
    2110                 :            :                 .data           = &sysctl_bootid,
    2111                 :            :                 .maxlen         = 16,
    2112                 :            :                 .mode           = 0444,
    2113                 :            :                 .proc_handler   = proc_do_uuid,
    2114                 :            :         },
    2115                 :            :         {
    2116                 :            :                 .procname       = "uuid",
    2117                 :            :                 .maxlen         = 16,
    2118                 :            :                 .mode           = 0444,
    2119                 :            :                 .proc_handler   = proc_do_uuid,
    2120                 :            :         },
    2121                 :            : #ifdef ADD_INTERRUPT_BENCH
    2122                 :            :         {
    2123                 :            :                 .procname       = "add_interrupt_avg_cycles",
    2124                 :            :                 .data           = &avg_cycles,
    2125                 :            :                 .maxlen         = sizeof(avg_cycles),
    2126                 :            :                 .mode           = 0444,
    2127                 :            :                 .proc_handler   = proc_doulongvec_minmax,
    2128                 :            :         },
    2129                 :            :         {
    2130                 :            :                 .procname       = "add_interrupt_avg_deviation",
    2131                 :            :                 .data           = &avg_deviation,
    2132                 :            :                 .maxlen         = sizeof(avg_deviation),
    2133                 :            :                 .mode           = 0444,
    2134                 :            :                 .proc_handler   = proc_doulongvec_minmax,
    2135                 :            :         },
    2136                 :            : #endif
    2137                 :            :         { }
    2138                 :            : };
    2139                 :            : #endif  /* CONFIG_SYSCTL */
    2140                 :            : 
    2141                 :            : struct batched_entropy {
    2142                 :            :         union {
    2143                 :            :                 u64 entropy_u64[CHACHA_BLOCK_SIZE / sizeof(u64)];
    2144                 :            :                 u32 entropy_u32[CHACHA_BLOCK_SIZE / sizeof(u32)];
    2145                 :            :         };
    2146                 :            :         unsigned int position;
    2147                 :            :         spinlock_t batch_lock;
    2148                 :            : };
    2149                 :            : 
    2150                 :            : /*
    2151                 :            :  * Get a random word for internal kernel use only. The quality of the random
    2152                 :            :  * number is either as good as RDRAND or as good as /dev/urandom, with the
    2153                 :            :  * goal of being quite fast and not depleting entropy. In order to ensure
    2154                 :            :  * that the randomness provided by this function is okay, the function
    2155                 :            :  * wait_for_random_bytes() should be called and return 0 at least once
    2156                 :            :  * at any point prior.
    2157                 :            :  */
    2158                 :            : static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
    2159                 :            :         .batch_lock     = __SPIN_LOCK_UNLOCKED(batched_entropy_u64.lock),
    2160                 :            : };
    2161                 :            : 
    2162                 :     161249 : u64 get_random_u64(void)
    2163                 :            : {
    2164                 :     161249 :         u64 ret;
    2165                 :     161249 :         unsigned long flags;
    2166                 :     161249 :         struct batched_entropy *batch;
    2167                 :     161249 :         static void *previous;
    2168                 :            : 
    2169                 :            : #if BITS_PER_LONG == 64
    2170         [ -  + ]:     161249 :         if (arch_get_random_long((unsigned long *)&ret))
    2171                 :          0 :                 return ret;
    2172                 :            : #else
    2173                 :            :         if (arch_get_random_long((unsigned long *)&ret) &&
    2174                 :            :             arch_get_random_long((unsigned long *)&ret + 1))
    2175                 :            :             return ret;
    2176                 :            : #endif
    2177                 :            : 
    2178                 :     161249 :         warn_unseeded_randomness(&previous);
    2179                 :            : 
    2180                 :     161249 :         batch = raw_cpu_ptr(&batched_entropy_u64);
    2181                 :     161249 :         spin_lock_irqsave(&batch->batch_lock, flags);
    2182         [ +  + ]:     161249 :         if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
    2183                 :      20170 :                 extract_crng((u8 *)batch->entropy_u64);
    2184                 :      20170 :                 batch->position = 0;
    2185                 :            :         }
    2186                 :     161249 :         ret = batch->entropy_u64[batch->position++];
    2187                 :     161249 :         spin_unlock_irqrestore(&batch->batch_lock, flags);
    2188                 :     161249 :         return ret;
    2189                 :            : }
    2190                 :            : EXPORT_SYMBOL(get_random_u64);
    2191                 :            : 
    2192                 :            : static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
    2193                 :            :         .batch_lock     = __SPIN_LOCK_UNLOCKED(batched_entropy_u32.lock),
    2194                 :            : };
    2195                 :      80513 : u32 get_random_u32(void)
    2196                 :            : {
    2197                 :      80513 :         u32 ret;
    2198                 :      80513 :         unsigned long flags;
    2199                 :      80513 :         struct batched_entropy *batch;
    2200                 :      80513 :         static void *previous;
    2201                 :            : 
    2202         [ -  + ]:      80513 :         if (arch_get_random_int(&ret))
    2203                 :          0 :                 return ret;
    2204                 :            : 
    2205                 :      80513 :         warn_unseeded_randomness(&previous);
    2206                 :            : 
    2207                 :      80513 :         batch = raw_cpu_ptr(&batched_entropy_u32);
    2208                 :      80513 :         spin_lock_irqsave(&batch->batch_lock, flags);
    2209         [ +  + ]:      80513 :         if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
    2210                 :       5050 :                 extract_crng((u8 *)batch->entropy_u32);
    2211                 :       5050 :                 batch->position = 0;
    2212                 :            :         }
    2213                 :      80513 :         ret = batch->entropy_u32[batch->position++];
    2214                 :      80513 :         spin_unlock_irqrestore(&batch->batch_lock, flags);
    2215                 :      80513 :         return ret;
    2216                 :            : }
    2217                 :            : EXPORT_SYMBOL(get_random_u32);
    2218                 :            : 
    2219                 :            : /* It's important to invalidate all potential batched entropy that might
    2220                 :            :  * be stored before the crng is initialized, which we can do lazily by
    2221                 :            :  * simply resetting the counter to zero so that it's re-extracted on the
    2222                 :            :  * next usage. */
    2223                 :         22 : static void invalidate_batched_entropy(void)
    2224                 :            : {
    2225                 :         22 :         int cpu;
    2226                 :         22 :         unsigned long flags;
    2227                 :            : 
    2228         [ +  + ]:         44 :         for_each_possible_cpu (cpu) {
    2229                 :         22 :                 struct batched_entropy *batched_entropy;
    2230                 :            : 
    2231                 :         22 :                 batched_entropy = per_cpu_ptr(&batched_entropy_u32, cpu);
    2232                 :         22 :                 spin_lock_irqsave(&batched_entropy->batch_lock, flags);
    2233                 :         22 :                 batched_entropy->position = 0;
    2234                 :         22 :                 spin_unlock(&batched_entropy->batch_lock);
    2235                 :            : 
    2236                 :         22 :                 batched_entropy = per_cpu_ptr(&batched_entropy_u64, cpu);
    2237                 :         22 :                 spin_lock(&batched_entropy->batch_lock);
    2238                 :         22 :                 batched_entropy->position = 0;
    2239                 :         22 :                 spin_unlock_irqrestore(&batched_entropy->batch_lock, flags);
    2240                 :            :         }
    2241                 :         22 : }
    2242                 :            : 
    2243                 :            : /**
    2244                 :            :  * randomize_page - Generate a random, page aligned address
    2245                 :            :  * @start:      The smallest acceptable address the caller will take.
    2246                 :            :  * @range:      The size of the area, starting at @start, within which the
    2247                 :            :  *              random address must fall.
    2248                 :            :  *
    2249                 :            :  * If @start + @range would overflow, @range is capped.
    2250                 :            :  *
    2251                 :            :  * NOTE: Historical use of randomize_range, which this replaces, presumed that
    2252                 :            :  * @start was already page aligned.  We now align it regardless.
    2253                 :            :  *
    2254                 :            :  * Return: A page aligned address within [start, start + range).  On error,
    2255                 :            :  * @start is returned.
    2256                 :            :  */
    2257                 :            : unsigned long
    2258                 :      26664 : randomize_page(unsigned long start, unsigned long range)
    2259                 :            : {
    2260         [ -  + ]:      26664 :         if (!PAGE_ALIGNED(start)) {
    2261                 :          0 :                 range -= PAGE_ALIGN(start) - start;
    2262                 :          0 :                 start = PAGE_ALIGN(start);
    2263                 :            :         }
    2264                 :            : 
    2265         [ -  + ]:      26664 :         if (start > ULONG_MAX - range)
    2266                 :          0 :                 range = ULONG_MAX - start;
    2267                 :            : 
    2268                 :      26664 :         range >>= PAGE_SHIFT;
    2269                 :            : 
    2270         [ +  - ]:      26664 :         if (range == 0)
    2271                 :            :                 return start;
    2272                 :            : 
    2273                 :      26664 :         return start + (get_random_long() % range << PAGE_SHIFT);
    2274                 :            : }
    2275                 :            : 
    2276                 :            : /* Interface for in-kernel drivers of true hardware RNGs.
    2277                 :            :  * Those devices may produce endless random bits and will be throttled
    2278                 :            :  * when our pool is full.
    2279                 :            :  */
    2280                 :          0 : void add_hwgenerator_randomness(const char *buffer, size_t count,
    2281                 :            :                                 size_t entropy)
    2282                 :            : {
    2283                 :          0 :         struct entropy_store *poolp = &input_pool;
    2284                 :            : 
    2285         [ #  # ]:          0 :         if (unlikely(crng_init == 0)) {
    2286                 :          0 :                 crng_fast_load(buffer, count);
    2287                 :          0 :                 return;
    2288                 :            :         }
    2289                 :            : 
    2290                 :            :         /* Suspend writing if we're above the trickle threshold.
    2291                 :            :          * We'll be woken up again once below random_write_wakeup_thresh,
    2292                 :            :          * or when the calling thread is about to terminate.
    2293                 :            :          */
    2294   [ #  #  #  #  :          0 :         wait_event_interruptible(random_write_wait, kthread_should_stop() ||
          #  #  #  #  #  
                      # ]
    2295                 :            :                         ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
    2296                 :          0 :         mix_pool_bytes(poolp, buffer, count);
    2297                 :          0 :         credit_entropy_bits(poolp, entropy);
    2298                 :            : }
    2299                 :            : EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
    2300                 :            : 
    2301                 :            : /* Handle random seed passed by bootloader.
    2302                 :            :  * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise
    2303                 :            :  * it would be regarded as device data.
    2304                 :            :  * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER.
    2305                 :            :  */
    2306                 :          0 : void add_bootloader_randomness(const void *buf, unsigned int size)
    2307                 :            : {
    2308                 :          0 :         if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER))
    2309                 :            :                 add_hwgenerator_randomness(buf, size, size * 8);
    2310                 :            :         else
    2311                 :          0 :                 add_device_randomness(buf, size);
    2312                 :          0 : }
    2313                 :            : EXPORT_SYMBOL_GPL(add_bootloader_randomness);

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