LCOV - code coverage report
Current view: top level - fs/debugfs - inode.c (source / functions) Hit Total Coverage
Test: gcov_data_raspi2_real_modules_combined.info Lines: 134 264 50.8 %
Date: 2020-09-30 20:25:40 Functions: 17 27 63.0 %
Branches: 37 160 23.1 %

           Branch data     Line data    Source code
       1                 :            : // SPDX-License-Identifier: GPL-2.0
       2                 :            : /*
       3                 :            :  *  inode.c - part of debugfs, a tiny little debug file system
       4                 :            :  *
       5                 :            :  *  Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
       6                 :            :  *  Copyright (C) 2004 IBM Inc.
       7                 :            :  *  Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
       8                 :            :  *
       9                 :            :  *  debugfs is for people to use instead of /proc or /sys.
      10                 :            :  *  See ./Documentation/core-api/kernel-api.rst for more details.
      11                 :            :  */
      12                 :            : 
      13                 :            : #define pr_fmt(fmt)     "debugfs: " fmt
      14                 :            : 
      15                 :            : #include <linux/module.h>
      16                 :            : #include <linux/fs.h>
      17                 :            : #include <linux/mount.h>
      18                 :            : #include <linux/pagemap.h>
      19                 :            : #include <linux/init.h>
      20                 :            : #include <linux/kobject.h>
      21                 :            : #include <linux/namei.h>
      22                 :            : #include <linux/debugfs.h>
      23                 :            : #include <linux/fsnotify.h>
      24                 :            : #include <linux/string.h>
      25                 :            : #include <linux/seq_file.h>
      26                 :            : #include <linux/parser.h>
      27                 :            : #include <linux/magic.h>
      28                 :            : #include <linux/slab.h>
      29                 :            : #include <linux/security.h>
      30                 :            : 
      31                 :            : #include "internal.h"
      32                 :            : 
      33                 :            : #define DEBUGFS_DEFAULT_MODE    0700
      34                 :            : 
      35                 :            : static struct vfsmount *debugfs_mount;
      36                 :            : static int debugfs_mount_count;
      37                 :            : static bool debugfs_registered;
      38                 :            : 
      39                 :            : /*
      40                 :            :  * Don't allow access attributes to be changed whilst the kernel is locked down
      41                 :            :  * so that we can use the file mode as part of a heuristic to determine whether
      42                 :            :  * to lock down individual files.
      43                 :            :  */
      44                 :          0 : static int debugfs_setattr(struct dentry *dentry, struct iattr *ia)
      45                 :            : {
      46                 :          0 :         int ret = security_locked_down(LOCKDOWN_DEBUGFS);
      47                 :            : 
      48   [ #  #  #  # ]:          0 :         if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
      49                 :            :                 return ret;
      50                 :          0 :         return simple_setattr(dentry, ia);
      51                 :            : }
      52                 :            : 
      53                 :            : static const struct inode_operations debugfs_file_inode_operations = {
      54                 :            :         .setattr        = debugfs_setattr,
      55                 :            : };
      56                 :            : static const struct inode_operations debugfs_dir_inode_operations = {
      57                 :            :         .lookup         = simple_lookup,
      58                 :            :         .setattr        = debugfs_setattr,
      59                 :            : };
      60                 :            : static const struct inode_operations debugfs_symlink_inode_operations = {
      61                 :            :         .get_link       = simple_get_link,
      62                 :            :         .setattr        = debugfs_setattr,
      63                 :            : };
      64                 :            : 
      65                 :    1213020 : static struct inode *debugfs_get_inode(struct super_block *sb)
      66                 :            : {
      67                 :    1213020 :         struct inode *inode = new_inode(sb);
      68         [ +  - ]:    1213020 :         if (inode) {
      69                 :    1213020 :                 inode->i_ino = get_next_ino();
      70                 :    1213020 :                 inode->i_atime = inode->i_mtime =
      71                 :            :                         inode->i_ctime = current_time(inode);
      72                 :            :         }
      73                 :    1213020 :         return inode;
      74                 :            : }
      75                 :            : 
      76                 :            : struct debugfs_mount_opts {
      77                 :            :         kuid_t uid;
      78                 :            :         kgid_t gid;
      79                 :            :         umode_t mode;
      80                 :            : };
      81                 :            : 
      82                 :            : enum {
      83                 :            :         Opt_uid,
      84                 :            :         Opt_gid,
      85                 :            :         Opt_mode,
      86                 :            :         Opt_err
      87                 :            : };
      88                 :            : 
      89                 :            : static const match_table_t tokens = {
      90                 :            :         {Opt_uid, "uid=%u"},
      91                 :            :         {Opt_gid, "gid=%u"},
      92                 :            :         {Opt_mode, "mode=%o"},
      93                 :            :         {Opt_err, NULL}
      94                 :            : };
      95                 :            : 
      96                 :            : struct debugfs_fs_info {
      97                 :            :         struct debugfs_mount_opts mount_opts;
      98                 :            : };
      99                 :            : 
     100                 :        414 : static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
     101                 :            : {
     102                 :            :         substring_t args[MAX_OPT_ARGS];
     103                 :            :         int option;
     104                 :            :         int token;
     105                 :            :         kuid_t uid;
     106                 :            :         kgid_t gid;
     107                 :            :         char *p;
     108                 :            : 
     109                 :        414 :         opts->mode = DEBUGFS_DEFAULT_MODE;
     110                 :            : 
     111         [ -  + ]:        828 :         while ((p = strsep(&data, ",")) != NULL) {
     112         [ #  # ]:          0 :                 if (!*p)
     113                 :          0 :                         continue;
     114                 :            : 
     115                 :          0 :                 token = match_token(p, tokens, args);
     116   [ #  #  #  # ]:          0 :                 switch (token) {
     117                 :            :                 case Opt_uid:
     118         [ #  # ]:          0 :                         if (match_int(&args[0], &option))
     119                 :            :                                 return -EINVAL;
     120                 :          0 :                         uid = make_kuid(current_user_ns(), option);
     121         [ #  # ]:          0 :                         if (!uid_valid(uid))
     122                 :            :                                 return -EINVAL;
     123                 :          0 :                         opts->uid = uid;
     124                 :          0 :                         break;
     125                 :            :                 case Opt_gid:
     126         [ #  # ]:          0 :                         if (match_int(&args[0], &option))
     127                 :            :                                 return -EINVAL;
     128                 :          0 :                         gid = make_kgid(current_user_ns(), option);
     129         [ #  # ]:          0 :                         if (!gid_valid(gid))
     130                 :            :                                 return -EINVAL;
     131                 :          0 :                         opts->gid = gid;
     132                 :          0 :                         break;
     133                 :            :                 case Opt_mode:
     134         [ #  # ]:          0 :                         if (match_octal(&args[0], &option))
     135                 :            :                                 return -EINVAL;
     136                 :          0 :                         opts->mode = option & S_IALLUGO;
     137                 :          0 :                         break;
     138                 :            :                 /*
     139                 :            :                  * We might like to report bad mount options here;
     140                 :            :                  * but traditionally debugfs has ignored all mount options
     141                 :            :                  */
     142                 :            :                 }
     143                 :            :         }
     144                 :            : 
     145                 :            :         return 0;
     146                 :            : }
     147                 :            : 
     148                 :            : static int debugfs_apply_options(struct super_block *sb)
     149                 :            : {
     150                 :        414 :         struct debugfs_fs_info *fsi = sb->s_fs_info;
     151                 :        414 :         struct inode *inode = d_inode(sb->s_root);
     152                 :            :         struct debugfs_mount_opts *opts = &fsi->mount_opts;
     153                 :            : 
     154                 :        414 :         inode->i_mode &= ~S_IALLUGO;
     155                 :        414 :         inode->i_mode |= opts->mode;
     156                 :            : 
     157                 :        414 :         inode->i_uid = opts->uid;
     158                 :        414 :         inode->i_gid = opts->gid;
     159                 :            : 
     160                 :            :         return 0;
     161                 :            : }
     162                 :            : 
     163                 :        207 : static int debugfs_remount(struct super_block *sb, int *flags, char *data)
     164                 :            : {
     165                 :            :         int err;
     166                 :        207 :         struct debugfs_fs_info *fsi = sb->s_fs_info;
     167                 :            : 
     168                 :        207 :         sync_filesystem(sb);
     169                 :        207 :         err = debugfs_parse_options(data, &fsi->mount_opts);
     170         [ +  - ]:        207 :         if (err)
     171                 :            :                 goto fail;
     172                 :            : 
     173                 :            :         debugfs_apply_options(sb);
     174                 :            : 
     175                 :            : fail:
     176                 :        207 :         return err;
     177                 :            : }
     178                 :            : 
     179                 :      28754 : static int debugfs_show_options(struct seq_file *m, struct dentry *root)
     180                 :            : {
     181                 :      28754 :         struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
     182                 :      28754 :         struct debugfs_mount_opts *opts = &fsi->mount_opts;
     183                 :            : 
     184         [ -  + ]:      28754 :         if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
     185                 :          0 :                 seq_printf(m, ",uid=%u",
     186                 :            :                            from_kuid_munged(&init_user_ns, opts->uid));
     187         [ -  + ]:      28753 :         if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
     188                 :          0 :                 seq_printf(m, ",gid=%u",
     189                 :            :                            from_kgid_munged(&init_user_ns, opts->gid));
     190         [ -  + ]:      28753 :         if (opts->mode != DEBUGFS_DEFAULT_MODE)
     191                 :          0 :                 seq_printf(m, ",mode=%o", opts->mode);
     192                 :            : 
     193                 :      28753 :         return 0;
     194                 :            : }
     195                 :            : 
     196                 :          0 : static void debugfs_free_inode(struct inode *inode)
     197                 :            : {
     198         [ #  # ]:          0 :         if (S_ISLNK(inode->i_mode))
     199                 :          0 :                 kfree(inode->i_link);
     200                 :          0 :         free_inode_nonrcu(inode);
     201                 :          0 : }
     202                 :            : 
     203                 :            : static const struct super_operations debugfs_super_operations = {
     204                 :            :         .statfs         = simple_statfs,
     205                 :            :         .remount_fs     = debugfs_remount,
     206                 :            :         .show_options   = debugfs_show_options,
     207                 :            :         .free_inode     = debugfs_free_inode,
     208                 :            : };
     209                 :            : 
     210                 :      53406 : static void debugfs_release_dentry(struct dentry *dentry)
     211                 :            : {
     212                 :      53406 :         void *fsd = dentry->d_fsdata;
     213                 :            : 
     214         [ +  - ]:      53406 :         if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
     215                 :      53406 :                 kfree(dentry->d_fsdata);
     216                 :      53406 : }
     217                 :            : 
     218                 :          0 : static struct vfsmount *debugfs_automount(struct path *path)
     219                 :            : {
     220                 :            :         debugfs_automount_t f;
     221                 :          0 :         f = (debugfs_automount_t)path->dentry->d_fsdata;
     222                 :          0 :         return f(path->dentry, d_inode(path->dentry)->i_private);
     223                 :            : }
     224                 :            : 
     225                 :            : static const struct dentry_operations debugfs_dops = {
     226                 :            :         .d_delete = always_delete_dentry,
     227                 :            :         .d_release = debugfs_release_dentry,
     228                 :            :         .d_automount = debugfs_automount,
     229                 :            : };
     230                 :            : 
     231                 :        207 : static int debug_fill_super(struct super_block *sb, void *data, int silent)
     232                 :            : {
     233                 :            :         static const struct tree_descr debug_files[] = {{""}};
     234                 :            :         struct debugfs_fs_info *fsi;
     235                 :            :         int err;
     236                 :            : 
     237                 :        207 :         fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
     238                 :        207 :         sb->s_fs_info = fsi;
     239         [ +  - ]:        207 :         if (!fsi) {
     240                 :            :                 err = -ENOMEM;
     241                 :            :                 goto fail;
     242                 :            :         }
     243                 :            : 
     244                 :        207 :         err = debugfs_parse_options(data, &fsi->mount_opts);
     245         [ +  - ]:        207 :         if (err)
     246                 :            :                 goto fail;
     247                 :            : 
     248                 :        207 :         err  =  simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
     249         [ +  - ]:        207 :         if (err)
     250                 :            :                 goto fail;
     251                 :            : 
     252                 :        207 :         sb->s_op = &debugfs_super_operations;
     253                 :        207 :         sb->s_d_op = &debugfs_dops;
     254                 :            : 
     255                 :            :         debugfs_apply_options(sb);
     256                 :            : 
     257                 :        207 :         return 0;
     258                 :            : 
     259                 :            : fail:
     260                 :          0 :         kfree(fsi);
     261                 :          0 :         sb->s_fs_info = NULL;
     262                 :          0 :         return err;
     263                 :            : }
     264                 :            : 
     265                 :        414 : static struct dentry *debug_mount(struct file_system_type *fs_type,
     266                 :            :                         int flags, const char *dev_name,
     267                 :            :                         void *data)
     268                 :            : {
     269                 :        414 :         return mount_single(fs_type, flags, data, debug_fill_super);
     270                 :            : }
     271                 :            : 
     272                 :            : static struct file_system_type debug_fs_type = {
     273                 :            :         .owner =        THIS_MODULE,
     274                 :            :         .name =         "debugfs",
     275                 :            :         .mount =        debug_mount,
     276                 :            :         .kill_sb =      kill_litter_super,
     277                 :            : };
     278                 :            : MODULE_ALIAS_FS("debugfs");
     279                 :            : 
     280                 :            : /**
     281                 :            :  * debugfs_lookup() - look up an existing debugfs file
     282                 :            :  * @name: a pointer to a string containing the name of the file to look up.
     283                 :            :  * @parent: a pointer to the parent dentry of the file.
     284                 :            :  *
     285                 :            :  * This function will return a pointer to a dentry if it succeeds.  If the file
     286                 :            :  * doesn't exist or an error occurs, %NULL will be returned.  The returned
     287                 :            :  * dentry must be passed to dput() when it is no longer needed.
     288                 :            :  *
     289                 :            :  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
     290                 :            :  * returned.
     291                 :            :  */
     292                 :        207 : struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
     293                 :            : {
     294                 :            :         struct dentry *dentry;
     295                 :            : 
     296         [ +  - ]:        207 :         if (IS_ERR(parent))
     297                 :            :                 return NULL;
     298                 :            : 
     299         [ +  - ]:        207 :         if (!parent)
     300                 :        207 :                 parent = debugfs_mount->mnt_root;
     301                 :            : 
     302                 :        207 :         dentry = lookup_one_len_unlocked(name, parent, strlen(name));
     303         [ +  - ]:        207 :         if (IS_ERR(dentry))
     304                 :            :                 return NULL;
     305         [ +  - ]:        207 :         if (!d_really_is_positive(dentry)) {
     306                 :        207 :                 dput(dentry);
     307                 :        207 :                 return NULL;
     308                 :            :         }
     309                 :            :         return dentry;
     310                 :            : }
     311                 :            : EXPORT_SYMBOL_GPL(debugfs_lookup);
     312                 :            : 
     313                 :    1213019 : static struct dentry *start_creating(const char *name, struct dentry *parent)
     314                 :            : {
     315                 :            :         struct dentry *dentry;
     316                 :            :         int error;
     317                 :            : 
     318                 :            :         pr_debug("creating file '%s'\n", name);
     319                 :            : 
     320         [ +  - ]:    1213019 :         if (IS_ERR(parent))
     321                 :            :                 return parent;
     322                 :            : 
     323                 :    1213019 :         error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
     324                 :            :                               &debugfs_mount_count);
     325         [ -  + ]:    1213020 :         if (error) {
     326                 :          0 :                 pr_err("Unable to pin filesystem for file '%s'\n", name);
     327                 :          0 :                 return ERR_PTR(error);
     328                 :            :         }
     329                 :            : 
     330                 :            :         /* If the parent is not specified, we create it in the root.
     331                 :            :          * We need the root dentry to do this, which is in the super
     332                 :            :          * block. A pointer to that is in the struct vfsmount that we
     333                 :            :          * have around.
     334                 :            :          */
     335         [ +  + ]:    1213020 :         if (!parent)
     336                 :       8280 :                 parent = debugfs_mount->mnt_root;
     337                 :            : 
     338                 :            :         inode_lock(d_inode(parent));
     339                 :    1213020 :         dentry = lookup_one_len(name, parent, strlen(name));
     340   [ +  -  -  + ]:    2426040 :         if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
     341         [ #  # ]:          0 :                 if (d_is_dir(dentry))
     342                 :          0 :                         pr_err("Directory '%s' with parent '%s' already present!\n",
     343                 :            :                                name, parent->d_name.name);
     344                 :            :                 else
     345                 :          0 :                         pr_err("File '%s' in directory '%s' already present!\n",
     346                 :            :                                name, parent->d_name.name);
     347                 :          0 :                 dput(dentry);
     348                 :            :                 dentry = ERR_PTR(-EEXIST);
     349                 :            :         }
     350                 :            : 
     351         [ -  + ]:    1213020 :         if (IS_ERR(dentry)) {
     352                 :            :                 inode_unlock(d_inode(parent));
     353                 :          0 :                 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
     354                 :            :         }
     355                 :            : 
     356                 :    1213020 :         return dentry;
     357                 :            : }
     358                 :            : 
     359                 :          0 : static struct dentry *failed_creating(struct dentry *dentry)
     360                 :            : {
     361                 :          0 :         inode_unlock(d_inode(dentry->d_parent));
     362                 :          0 :         dput(dentry);
     363                 :          0 :         simple_release_fs(&debugfs_mount, &debugfs_mount_count);
     364                 :          0 :         return ERR_PTR(-ENOMEM);
     365                 :            : }
     366                 :            : 
     367                 :            : static struct dentry *end_creating(struct dentry *dentry)
     368                 :            : {
     369                 :    1213020 :         inode_unlock(d_inode(dentry->d_parent));
     370                 :            :         return dentry;
     371                 :            : }
     372                 :            : 
     373                 :     745614 : static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
     374                 :            :                                 struct dentry *parent, void *data,
     375                 :            :                                 const struct file_operations *proxy_fops,
     376                 :            :                                 const struct file_operations *real_fops)
     377                 :            : {
     378                 :            :         struct dentry *dentry;
     379                 :            :         struct inode *inode;
     380                 :            : 
     381         [ +  + ]:     745614 :         if (!(mode & S_IFMT))
     382                 :     742923 :                 mode |= S_IFREG;
     383         [ -  + ]:     745614 :         BUG_ON(!S_ISREG(mode));
     384                 :     745614 :         dentry = start_creating(name, parent);
     385                 :            : 
     386         [ +  - ]:     745614 :         if (IS_ERR(dentry))
     387                 :            :                 return dentry;
     388                 :            : 
     389                 :     745614 :         inode = debugfs_get_inode(dentry->d_sb);
     390         [ -  + ]:     745614 :         if (unlikely(!inode)) {
     391                 :          0 :                 pr_err("out of free dentries, can not create file '%s'\n",
     392                 :            :                        name);
     393                 :          0 :                 return failed_creating(dentry);
     394                 :            :         }
     395                 :            : 
     396                 :     745614 :         inode->i_mode = mode;
     397                 :     745614 :         inode->i_private = data;
     398                 :            : 
     399                 :     745614 :         inode->i_op = &debugfs_file_inode_operations;
     400                 :     745614 :         inode->i_fop = proxy_fops;
     401                 :     745614 :         dentry->d_fsdata = (void *)((unsigned long)real_fops |
     402                 :            :                                 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
     403                 :            : 
     404                 :     745614 :         d_instantiate(dentry, inode);
     405                 :    1491228 :         fsnotify_create(d_inode(dentry->d_parent), dentry);
     406                 :     745614 :         return end_creating(dentry);
     407                 :            : }
     408                 :            : 
     409                 :            : /**
     410                 :            :  * debugfs_create_file - create a file in the debugfs filesystem
     411                 :            :  * @name: a pointer to a string containing the name of the file to create.
     412                 :            :  * @mode: the permission that the file should have.
     413                 :            :  * @parent: a pointer to the parent dentry for this file.  This should be a
     414                 :            :  *          directory dentry if set.  If this parameter is NULL, then the
     415                 :            :  *          file will be created in the root of the debugfs filesystem.
     416                 :            :  * @data: a pointer to something that the caller will want to get to later
     417                 :            :  *        on.  The inode.i_private pointer will point to this value on
     418                 :            :  *        the open() call.
     419                 :            :  * @fops: a pointer to a struct file_operations that should be used for
     420                 :            :  *        this file.
     421                 :            :  *
     422                 :            :  * This is the basic "create a file" function for debugfs.  It allows for a
     423                 :            :  * wide range of flexibility in creating a file, or a directory (if you want
     424                 :            :  * to create a directory, the debugfs_create_dir() function is
     425                 :            :  * recommended to be used instead.)
     426                 :            :  *
     427                 :            :  * This function will return a pointer to a dentry if it succeeds.  This
     428                 :            :  * pointer must be passed to the debugfs_remove() function when the file is
     429                 :            :  * to be removed (no automatic cleanup happens if your module is unloaded,
     430                 :            :  * you are responsible here.)  If an error occurs, %ERR_PTR(-ERROR) will be
     431                 :            :  * returned.
     432                 :            :  *
     433                 :            :  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
     434                 :            :  * returned.
     435                 :            :  */
     436                 :     644805 : struct dentry *debugfs_create_file(const char *name, umode_t mode,
     437                 :            :                                    struct dentry *parent, void *data,
     438                 :            :                                    const struct file_operations *fops)
     439                 :            : {
     440                 :            : 
     441   [ #  #  -  + ]:     644805 :         return __debugfs_create_file(name, mode, parent, data,
     442                 :            :                                 fops ? &debugfs_full_proxy_file_operations :
     443                 :            :                                         &debugfs_noop_file_operations,
     444                 :            :                                 fops);
     445                 :            : }
     446                 :            : EXPORT_SYMBOL_GPL(debugfs_create_file);
     447                 :            : 
     448                 :            : /**
     449                 :            :  * debugfs_create_file_unsafe - create a file in the debugfs filesystem
     450                 :            :  * @name: a pointer to a string containing the name of the file to create.
     451                 :            :  * @mode: the permission that the file should have.
     452                 :            :  * @parent: a pointer to the parent dentry for this file.  This should be a
     453                 :            :  *          directory dentry if set.  If this parameter is NULL, then the
     454                 :            :  *          file will be created in the root of the debugfs filesystem.
     455                 :            :  * @data: a pointer to something that the caller will want to get to later
     456                 :            :  *        on.  The inode.i_private pointer will point to this value on
     457                 :            :  *        the open() call.
     458                 :            :  * @fops: a pointer to a struct file_operations that should be used for
     459                 :            :  *        this file.
     460                 :            :  *
     461                 :            :  * debugfs_create_file_unsafe() is completely analogous to
     462                 :            :  * debugfs_create_file(), the only difference being that the fops
     463                 :            :  * handed it will not get protected against file removals by the
     464                 :            :  * debugfs core.
     465                 :            :  *
     466                 :            :  * It is your responsibility to protect your struct file_operation
     467                 :            :  * methods against file removals by means of debugfs_file_get()
     468                 :            :  * and debugfs_file_put(). ->open() is still protected by
     469                 :            :  * debugfs though.
     470                 :            :  *
     471                 :            :  * Any struct file_operations defined by means of
     472                 :            :  * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
     473                 :            :  * thus, may be used here.
     474                 :            :  */
     475                 :     100809 : struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
     476                 :            :                                    struct dentry *parent, void *data,
     477                 :            :                                    const struct file_operations *fops)
     478                 :            : {
     479                 :            : 
     480         [ -  + ]:     100809 :         return __debugfs_create_file(name, mode, parent, data,
     481                 :            :                                 fops ? &debugfs_open_proxy_file_operations :
     482                 :            :                                         &debugfs_noop_file_operations,
     483                 :            :                                 fops);
     484                 :            : }
     485                 :            : EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
     486                 :            : 
     487                 :            : /**
     488                 :            :  * debugfs_create_file_size - create a file in the debugfs filesystem
     489                 :            :  * @name: a pointer to a string containing the name of the file to create.
     490                 :            :  * @mode: the permission that the file should have.
     491                 :            :  * @parent: a pointer to the parent dentry for this file.  This should be a
     492                 :            :  *          directory dentry if set.  If this parameter is NULL, then the
     493                 :            :  *          file will be created in the root of the debugfs filesystem.
     494                 :            :  * @data: a pointer to something that the caller will want to get to later
     495                 :            :  *        on.  The inode.i_private pointer will point to this value on
     496                 :            :  *        the open() call.
     497                 :            :  * @fops: a pointer to a struct file_operations that should be used for
     498                 :            :  *        this file.
     499                 :            :  * @file_size: initial file size
     500                 :            :  *
     501                 :            :  * This is the basic "create a file" function for debugfs.  It allows for a
     502                 :            :  * wide range of flexibility in creating a file, or a directory (if you want
     503                 :            :  * to create a directory, the debugfs_create_dir() function is
     504                 :            :  * recommended to be used instead.)
     505                 :            :  *
     506                 :            :  * This function will return a pointer to a dentry if it succeeds.  This
     507                 :            :  * pointer must be passed to the debugfs_remove() function when the file is
     508                 :            :  * to be removed (no automatic cleanup happens if your module is unloaded,
     509                 :            :  * you are responsible here.)  If an error occurs, %ERR_PTR(-ERROR) will be
     510                 :            :  * returned.
     511                 :            :  *
     512                 :            :  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
     513                 :            :  * returned.
     514                 :            :  */
     515                 :          0 : struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
     516                 :            :                                         struct dentry *parent, void *data,
     517                 :            :                                         const struct file_operations *fops,
     518                 :            :                                         loff_t file_size)
     519                 :            : {
     520                 :            :         struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
     521                 :            : 
     522         [ #  # ]:          0 :         if (de)
     523                 :          0 :                 d_inode(de)->i_size = file_size;
     524                 :          0 :         return de;
     525                 :            : }
     526                 :            : EXPORT_SYMBOL_GPL(debugfs_create_file_size);
     527                 :            : 
     528                 :            : /**
     529                 :            :  * debugfs_create_dir - create a directory in the debugfs filesystem
     530                 :            :  * @name: a pointer to a string containing the name of the directory to
     531                 :            :  *        create.
     532                 :            :  * @parent: a pointer to the parent dentry for this file.  This should be a
     533                 :            :  *          directory dentry if set.  If this parameter is NULL, then the
     534                 :            :  *          directory will be created in the root of the debugfs filesystem.
     535                 :            :  *
     536                 :            :  * This function creates a directory in debugfs with the given name.
     537                 :            :  *
     538                 :            :  * This function will return a pointer to a dentry if it succeeds.  This
     539                 :            :  * pointer must be passed to the debugfs_remove() function when the file is
     540                 :            :  * to be removed (no automatic cleanup happens if your module is unloaded,
     541                 :            :  * you are responsible here.)  If an error occurs, %ERR_PTR(-ERROR) will be
     542                 :            :  * returned.
     543                 :            :  *
     544                 :            :  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
     545                 :            :  * returned.
     546                 :            :  */
     547                 :      91080 : struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
     548                 :            : {
     549                 :      91080 :         struct dentry *dentry = start_creating(name, parent);
     550                 :            :         struct inode *inode;
     551                 :            : 
     552         [ +  - ]:      91080 :         if (IS_ERR(dentry))
     553                 :            :                 return dentry;
     554                 :            : 
     555                 :      91080 :         inode = debugfs_get_inode(dentry->d_sb);
     556         [ -  + ]:      91080 :         if (unlikely(!inode)) {
     557                 :          0 :                 pr_err("out of free dentries, can not create directory '%s'\n",
     558                 :            :                        name);
     559                 :          0 :                 return failed_creating(dentry);
     560                 :            :         }
     561                 :            : 
     562                 :      91080 :         inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
     563                 :      91080 :         inode->i_op = &debugfs_dir_inode_operations;
     564                 :      91080 :         inode->i_fop = &simple_dir_operations;
     565                 :            : 
     566                 :            :         /* directory inodes start off with i_nlink == 2 (for "." entry) */
     567                 :      91080 :         inc_nlink(inode);
     568                 :      91080 :         d_instantiate(dentry, inode);
     569                 :     182160 :         inc_nlink(d_inode(dentry->d_parent));
     570                 :     182160 :         fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
     571                 :      91080 :         return end_creating(dentry);
     572                 :            : }
     573                 :            : EXPORT_SYMBOL_GPL(debugfs_create_dir);
     574                 :            : 
     575                 :            : /**
     576                 :            :  * debugfs_create_automount - create automount point in the debugfs filesystem
     577                 :            :  * @name: a pointer to a string containing the name of the file to create.
     578                 :            :  * @parent: a pointer to the parent dentry for this file.  This should be a
     579                 :            :  *          directory dentry if set.  If this parameter is NULL, then the
     580                 :            :  *          file will be created in the root of the debugfs filesystem.
     581                 :            :  * @f: function to be called when pathname resolution steps on that one.
     582                 :            :  * @data: opaque argument to pass to f().
     583                 :            :  *
     584                 :            :  * @f should return what ->d_automount() would.
     585                 :            :  */
     586                 :        207 : struct dentry *debugfs_create_automount(const char *name,
     587                 :            :                                         struct dentry *parent,
     588                 :            :                                         debugfs_automount_t f,
     589                 :            :                                         void *data)
     590                 :            : {
     591                 :        207 :         struct dentry *dentry = start_creating(name, parent);
     592                 :            :         struct inode *inode;
     593                 :            : 
     594         [ +  - ]:        207 :         if (IS_ERR(dentry))
     595                 :            :                 return dentry;
     596                 :            : 
     597                 :        207 :         inode = debugfs_get_inode(dentry->d_sb);
     598         [ -  + ]:        207 :         if (unlikely(!inode)) {
     599                 :          0 :                 pr_err("out of free dentries, can not create automount '%s'\n",
     600                 :            :                        name);
     601                 :          0 :                 return failed_creating(dentry);
     602                 :            :         }
     603                 :            : 
     604                 :        207 :         make_empty_dir_inode(inode);
     605                 :        207 :         inode->i_flags |= S_AUTOMOUNT;
     606                 :        207 :         inode->i_private = data;
     607                 :        207 :         dentry->d_fsdata = (void *)f;
     608                 :            :         /* directory inodes start off with i_nlink == 2 (for "." entry) */
     609                 :        207 :         inc_nlink(inode);
     610                 :        207 :         d_instantiate(dentry, inode);
     611                 :        414 :         inc_nlink(d_inode(dentry->d_parent));
     612                 :        414 :         fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
     613                 :        207 :         return end_creating(dentry);
     614                 :            : }
     615                 :            : EXPORT_SYMBOL(debugfs_create_automount);
     616                 :            : 
     617                 :            : /**
     618                 :            :  * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
     619                 :            :  * @name: a pointer to a string containing the name of the symbolic link to
     620                 :            :  *        create.
     621                 :            :  * @parent: a pointer to the parent dentry for this symbolic link.  This
     622                 :            :  *          should be a directory dentry if set.  If this parameter is NULL,
     623                 :            :  *          then the symbolic link will be created in the root of the debugfs
     624                 :            :  *          filesystem.
     625                 :            :  * @target: a pointer to a string containing the path to the target of the
     626                 :            :  *          symbolic link.
     627                 :            :  *
     628                 :            :  * This function creates a symbolic link with the given name in debugfs that
     629                 :            :  * links to the given target path.
     630                 :            :  *
     631                 :            :  * This function will return a pointer to a dentry if it succeeds.  This
     632                 :            :  * pointer must be passed to the debugfs_remove() function when the symbolic
     633                 :            :  * link is to be removed (no automatic cleanup happens if your module is
     634                 :            :  * unloaded, you are responsible here.)  If an error occurs, %ERR_PTR(-ERROR)
     635                 :            :  * will be returned.
     636                 :            :  *
     637                 :            :  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
     638                 :            :  * returned.
     639                 :            :  */
     640                 :     376119 : struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
     641                 :            :                                       const char *target)
     642                 :            : {
     643                 :            :         struct dentry *dentry;
     644                 :            :         struct inode *inode;
     645                 :     376119 :         char *link = kstrdup(target, GFP_KERNEL);
     646         [ +  - ]:     376119 :         if (!link)
     647                 :            :                 return ERR_PTR(-ENOMEM);
     648                 :            : 
     649                 :     376119 :         dentry = start_creating(name, parent);
     650         [ -  + ]:     376119 :         if (IS_ERR(dentry)) {
     651                 :          0 :                 kfree(link);
     652                 :          0 :                 return dentry;
     653                 :            :         }
     654                 :            : 
     655                 :     376119 :         inode = debugfs_get_inode(dentry->d_sb);
     656         [ -  + ]:     376119 :         if (unlikely(!inode)) {
     657                 :          0 :                 pr_err("out of free dentries, can not create symlink '%s'\n",
     658                 :            :                        name);
     659                 :          0 :                 kfree(link);
     660                 :          0 :                 return failed_creating(dentry);
     661                 :            :         }
     662                 :     376119 :         inode->i_mode = S_IFLNK | S_IRWXUGO;
     663                 :     376119 :         inode->i_op = &debugfs_symlink_inode_operations;
     664                 :     376119 :         inode->i_link = link;
     665                 :     376119 :         d_instantiate(dentry, inode);
     666                 :     376119 :         return end_creating(dentry);
     667                 :            : }
     668                 :            : EXPORT_SYMBOL_GPL(debugfs_create_symlink);
     669                 :            : 
     670                 :          0 : static void __debugfs_file_removed(struct dentry *dentry)
     671                 :            : {
     672                 :            :         struct debugfs_fsdata *fsd;
     673                 :            : 
     674                 :            :         /*
     675                 :            :          * Paired with the closing smp_mb() implied by a successful
     676                 :            :          * cmpxchg() in debugfs_file_get(): either
     677                 :            :          * debugfs_file_get() must see a dead dentry or we must see a
     678                 :            :          * debugfs_fsdata instance at ->d_fsdata here (or both).
     679                 :            :          */
     680                 :          0 :         smp_mb();
     681                 :            :         fsd = READ_ONCE(dentry->d_fsdata);
     682         [ #  # ]:          0 :         if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
     683                 :          0 :                 return;
     684         [ #  # ]:          0 :         if (!refcount_dec_and_test(&fsd->active_users))
     685                 :          0 :                 wait_for_completion(&fsd->active_users_drained);
     686                 :            : }
     687                 :            : 
     688                 :          0 : static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
     689                 :            : {
     690                 :            :         int ret = 0;
     691                 :            : 
     692         [ #  # ]:          0 :         if (simple_positive(dentry)) {
     693                 :            :                 dget(dentry);
     694         [ #  # ]:          0 :                 if (d_is_dir(dentry)) {
     695                 :          0 :                         ret = simple_rmdir(d_inode(parent), dentry);
     696         [ #  # ]:          0 :                         if (!ret)
     697                 :          0 :                                 fsnotify_rmdir(d_inode(parent), dentry);
     698                 :            :                 } else {
     699                 :          0 :                         simple_unlink(d_inode(parent), dentry);
     700                 :          0 :                         fsnotify_unlink(d_inode(parent), dentry);
     701                 :            :                 }
     702         [ #  # ]:          0 :                 if (!ret)
     703                 :          0 :                         d_delete(dentry);
     704         [ #  # ]:          0 :                 if (d_is_reg(dentry))
     705                 :          0 :                         __debugfs_file_removed(dentry);
     706                 :          0 :                 dput(dentry);
     707                 :            :         }
     708                 :          0 :         return ret;
     709                 :            : }
     710                 :            : 
     711                 :            : /**
     712                 :            :  * debugfs_remove - removes a file or directory from the debugfs filesystem
     713                 :            :  * @dentry: a pointer to a the dentry of the file or directory to be
     714                 :            :  *          removed.  If this parameter is NULL or an error value, nothing
     715                 :            :  *          will be done.
     716                 :            :  *
     717                 :            :  * This function removes a file or directory in debugfs that was previously
     718                 :            :  * created with a call to another debugfs function (like
     719                 :            :  * debugfs_create_file() or variants thereof.)
     720                 :            :  *
     721                 :            :  * This function is required to be called in order for the file to be
     722                 :            :  * removed, no automatic cleanup of files will happen when a module is
     723                 :            :  * removed, you are responsible here.
     724                 :            :  */
     725                 :          0 : void debugfs_remove(struct dentry *dentry)
     726                 :            : {
     727                 :            :         struct dentry *parent;
     728                 :            :         int ret;
     729                 :            : 
     730         [ #  # ]:          0 :         if (IS_ERR_OR_NULL(dentry))
     731                 :          0 :                 return;
     732                 :            : 
     733                 :          0 :         parent = dentry->d_parent;
     734                 :            :         inode_lock(d_inode(parent));
     735                 :          0 :         ret = __debugfs_remove(dentry, parent);
     736                 :            :         inode_unlock(d_inode(parent));
     737         [ #  # ]:          0 :         if (!ret)
     738                 :          0 :                 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
     739                 :            : }
     740                 :            : EXPORT_SYMBOL_GPL(debugfs_remove);
     741                 :            : 
     742                 :            : /**
     743                 :            :  * debugfs_remove_recursive - recursively removes a directory
     744                 :            :  * @dentry: a pointer to a the dentry of the directory to be removed.  If this
     745                 :            :  *          parameter is NULL or an error value, nothing will be done.
     746                 :            :  *
     747                 :            :  * This function recursively removes a directory tree in debugfs that
     748                 :            :  * was previously created with a call to another debugfs function
     749                 :            :  * (like debugfs_create_file() or variants thereof.)
     750                 :            :  *
     751                 :            :  * This function is required to be called in order for the file to be
     752                 :            :  * removed, no automatic cleanup of files will happen when a module is
     753                 :            :  * removed, you are responsible here.
     754                 :            :  */
     755                 :          0 : void debugfs_remove_recursive(struct dentry *dentry)
     756                 :            : {
     757                 :            :         struct dentry *child, *parent;
     758                 :            : 
     759         [ #  # ]:          0 :         if (IS_ERR_OR_NULL(dentry))
     760                 :          0 :                 return;
     761                 :            : 
     762                 :            :         parent = dentry;
     763                 :            :  down:
     764                 :            :         inode_lock(d_inode(parent));
     765                 :            :  loop:
     766                 :            :         /*
     767                 :            :          * The parent->d_subdirs is protected by the d_lock. Outside that
     768                 :            :          * lock, the child can be unlinked and set to be freed which can
     769                 :            :          * use the d_u.d_child as the rcu head and corrupt this list.
     770                 :            :          */
     771                 :            :         spin_lock(&parent->d_lock);
     772         [ #  # ]:          0 :         list_for_each_entry(child, &parent->d_subdirs, d_child) {
     773         [ #  # ]:          0 :                 if (!simple_positive(child))
     774                 :          0 :                         continue;
     775                 :            : 
     776                 :            :                 /* perhaps simple_empty(child) makes more sense */
     777         [ #  # ]:          0 :                 if (!list_empty(&child->d_subdirs)) {
     778                 :            :                         spin_unlock(&parent->d_lock);
     779                 :            :                         inode_unlock(d_inode(parent));
     780                 :          0 :                         parent = child;
     781                 :          0 :                         goto down;
     782                 :            :                 }
     783                 :            : 
     784                 :            :                 spin_unlock(&parent->d_lock);
     785                 :            : 
     786         [ #  # ]:          0 :                 if (!__debugfs_remove(child, parent))
     787                 :          0 :                         simple_release_fs(&debugfs_mount, &debugfs_mount_count);
     788                 :            : 
     789                 :            :                 /*
     790                 :            :                  * The parent->d_lock protects agaist child from unlinking
     791                 :            :                  * from d_subdirs. When releasing the parent->d_lock we can
     792                 :            :                  * no longer trust that the next pointer is valid.
     793                 :            :                  * Restart the loop. We'll skip this one with the
     794                 :            :                  * simple_positive() check.
     795                 :            :                  */
     796                 :            :                 goto loop;
     797                 :            :         }
     798                 :            :         spin_unlock(&parent->d_lock);
     799                 :            : 
     800                 :            :         inode_unlock(d_inode(parent));
     801                 :            :         child = parent;
     802                 :          0 :         parent = parent->d_parent;
     803                 :            :         inode_lock(d_inode(parent));
     804                 :            : 
     805         [ #  # ]:          0 :         if (child != dentry)
     806                 :            :                 /* go up */
     807                 :            :                 goto loop;
     808                 :            : 
     809         [ #  # ]:          0 :         if (!__debugfs_remove(child, parent))
     810                 :          0 :                 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
     811                 :            :         inode_unlock(d_inode(parent));
     812                 :            : }
     813                 :            : EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
     814                 :            : 
     815                 :            : /**
     816                 :            :  * debugfs_rename - rename a file/directory in the debugfs filesystem
     817                 :            :  * @old_dir: a pointer to the parent dentry for the renamed object. This
     818                 :            :  *          should be a directory dentry.
     819                 :            :  * @old_dentry: dentry of an object to be renamed.
     820                 :            :  * @new_dir: a pointer to the parent dentry where the object should be
     821                 :            :  *          moved. This should be a directory dentry.
     822                 :            :  * @new_name: a pointer to a string containing the target name.
     823                 :            :  *
     824                 :            :  * This function renames a file/directory in debugfs.  The target must not
     825                 :            :  * exist for rename to succeed.
     826                 :            :  *
     827                 :            :  * This function will return a pointer to old_dentry (which is updated to
     828                 :            :  * reflect renaming) if it succeeds. If an error occurs, %NULL will be
     829                 :            :  * returned.
     830                 :            :  *
     831                 :            :  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
     832                 :            :  * returned.
     833                 :            :  */
     834                 :          0 : struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
     835                 :            :                 struct dentry *new_dir, const char *new_name)
     836                 :            : {
     837                 :            :         int error;
     838                 :            :         struct dentry *dentry = NULL, *trap;
     839                 :            :         struct name_snapshot old_name;
     840                 :            : 
     841         [ #  # ]:          0 :         if (IS_ERR(old_dir))
     842                 :            :                 return old_dir;
     843         [ #  # ]:          0 :         if (IS_ERR(new_dir))
     844                 :            :                 return new_dir;
     845         [ #  # ]:          0 :         if (IS_ERR_OR_NULL(old_dentry))
     846                 :            :                 return old_dentry;
     847                 :            : 
     848                 :          0 :         trap = lock_rename(new_dir, old_dir);
     849                 :            :         /* Source or destination directories don't exist? */
     850   [ #  #  #  # ]:          0 :         if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
     851                 :            :                 goto exit;
     852                 :            :         /* Source does not exist, cyclic rename, or mountpoint? */
     853   [ #  #  #  #  :          0 :         if (d_really_is_negative(old_dentry) || old_dentry == trap ||
                   #  # ]
     854                 :            :             d_mountpoint(old_dentry))
     855                 :            :                 goto exit;
     856                 :          0 :         dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
     857                 :            :         /* Lookup failed, cyclic rename or target exists? */
     858   [ #  #  #  #  :          0 :         if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
                   #  # ]
     859                 :            :                 goto exit;
     860                 :            : 
     861                 :          0 :         take_dentry_name_snapshot(&old_name, old_dentry);
     862                 :            : 
     863                 :          0 :         error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
     864                 :            :                               dentry, 0);
     865         [ #  # ]:          0 :         if (error) {
     866                 :          0 :                 release_dentry_name_snapshot(&old_name);
     867                 :          0 :                 goto exit;
     868                 :            :         }
     869                 :          0 :         d_move(old_dentry, dentry);
     870                 :          0 :         fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
     871                 :            :                 d_is_dir(old_dentry),
     872                 :            :                 NULL, old_dentry);
     873                 :          0 :         release_dentry_name_snapshot(&old_name);
     874                 :          0 :         unlock_rename(new_dir, old_dir);
     875                 :          0 :         dput(dentry);
     876                 :          0 :         return old_dentry;
     877                 :            : exit:
     878   [ #  #  #  # ]:          0 :         if (dentry && !IS_ERR(dentry))
     879                 :          0 :                 dput(dentry);
     880                 :          0 :         unlock_rename(new_dir, old_dir);
     881         [ #  # ]:          0 :         if (IS_ERR(dentry))
     882                 :          0 :                 return dentry;
     883                 :            :         return ERR_PTR(-EINVAL);
     884                 :            : }
     885                 :            : EXPORT_SYMBOL_GPL(debugfs_rename);
     886                 :            : 
     887                 :            : /**
     888                 :            :  * debugfs_initialized - Tells whether debugfs has been registered
     889                 :            :  */
     890                 :        414 : bool debugfs_initialized(void)
     891                 :            : {
     892                 :        414 :         return debugfs_registered;
     893                 :            : }
     894                 :            : EXPORT_SYMBOL_GPL(debugfs_initialized);
     895                 :            : 
     896                 :        207 : static int __init debugfs_init(void)
     897                 :            : {
     898                 :            :         int retval;
     899                 :            : 
     900                 :        207 :         retval = sysfs_create_mount_point(kernel_kobj, "debug");
     901         [ +  - ]:        207 :         if (retval)
     902                 :            :                 return retval;
     903                 :            : 
     904                 :        207 :         retval = register_filesystem(&debug_fs_type);
     905         [ -  + ]:        207 :         if (retval)
     906                 :          0 :                 sysfs_remove_mount_point(kernel_kobj, "debug");
     907                 :            :         else
     908                 :        207 :                 debugfs_registered = true;
     909                 :            : 
     910                 :        207 :         return retval;
     911                 :            : }
     912                 :            : core_initcall(debugfs_init);
     913                 :            : 

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