Branch data Line data Source code
1 : : // SPDX-License-Identifier: GPL-2.0-or-later
2 : : /* Common capabilities, needed by capability.o.
3 : : */
4 : :
5 : : #include <linux/capability.h>
6 : : #include <linux/audit.h>
7 : : #include <linux/init.h>
8 : : #include <linux/kernel.h>
9 : : #include <linux/lsm_hooks.h>
10 : : #include <linux/file.h>
11 : : #include <linux/mm.h>
12 : : #include <linux/mman.h>
13 : : #include <linux/pagemap.h>
14 : : #include <linux/swap.h>
15 : : #include <linux/skbuff.h>
16 : : #include <linux/netlink.h>
17 : : #include <linux/ptrace.h>
18 : : #include <linux/xattr.h>
19 : : #include <linux/hugetlb.h>
20 : : #include <linux/mount.h>
21 : : #include <linux/sched.h>
22 : : #include <linux/prctl.h>
23 : : #include <linux/securebits.h>
24 : : #include <linux/user_namespace.h>
25 : : #include <linux/binfmts.h>
26 : : #include <linux/personality.h>
27 : :
28 : : /*
29 : : * If a non-root user executes a setuid-root binary in
30 : : * !secure(SECURE_NOROOT) mode, then we raise capabilities.
31 : : * However if fE is also set, then the intent is for only
32 : : * the file capabilities to be applied, and the setuid-root
33 : : * bit is left on either to change the uid (plausible) or
34 : : * to get full privilege on a kernel without file capabilities
35 : : * support. So in that case we do not raise capabilities.
36 : : *
37 : : * Warn if that happens, once per boot.
38 : : */
39 : 0 : static void warn_setuid_and_fcaps_mixed(const char *fname)
40 : : {
41 : 0 : static int warned;
42 : 0 : if (!warned) {
43 : 0 : printk(KERN_INFO "warning: `%s' has both setuid-root and"
44 : : " effective capabilities. Therefore not raising all"
45 : : " capabilities.\n", fname);
46 : 0 : warned = 1;
47 : : }
48 : : }
49 : :
50 : : /**
51 : : * cap_capable - Determine whether a task has a particular effective capability
52 : : * @cred: The credentials to use
53 : : * @ns: The user namespace in which we need the capability
54 : : * @cap: The capability to check for
55 : : * @opts: Bitmask of options defined in include/linux/security.h
56 : : *
57 : : * Determine whether the nominated task has the specified capability amongst
58 : : * its effective set, returning 0 if it does, -ve if it does not.
59 : : *
60 : : * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
61 : : * and has_capability() functions. That is, it has the reverse semantics:
62 : : * cap_has_capability() returns 0 when a task has a capability, but the
63 : : * kernel's capable() and has_capability() returns 1 for this case.
64 : : */
65 : 1538954 : int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
66 : : int cap, unsigned int opts)
67 : : {
68 : 74622 : struct user_namespace *ns = targ_ns;
69 : :
70 : : /* See if cred has the capability in the target user namespace
71 : : * by examining the target user namespace and all of the target
72 : : * user namespace's parents.
73 : : */
74 : 1613606 : for (;;) {
75 : : /* Do we have the necessary capabilities? */
76 [ - - + - : 1613606 : if (ns == cred->user_ns)
+ - + - +
- ]
77 [ - - + + : 1613606 : return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
+ - + - +
+ ]
78 : :
79 : : /*
80 : : * If we're already at a lower level than we're looking for,
81 : : * we're done searching.
82 : : */
83 [ # # # # : 0 : if (ns->level <= cred->user_ns->level)
# # # # #
# ]
84 : : return -EPERM;
85 : :
86 : : /*
87 : : * The owner of the user namespace in the parent of the
88 : : * user namespace has all caps.
89 : : */
90 [ # # # # : 0 : if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
# # # # #
# # # # #
# # # # #
# ]
91 : : return 0;
92 : :
93 : : /*
94 : : * If you have a capability in a parent user ns, then you have
95 : : * it over all children user namespaces as well.
96 : : */
97 : : ns = ns->parent;
98 : : }
99 : :
100 : : /* We never get here */
101 : : }
102 : :
103 : : /**
104 : : * cap_settime - Determine whether the current process may set the system clock
105 : : * @ts: The time to set
106 : : * @tz: The timezone to set
107 : : *
108 : : * Determine whether the current process may set the system clock and timezone
109 : : * information, returning 0 if permission granted, -ve if denied.
110 : : */
111 : 30 : int cap_settime(const struct timespec64 *ts, const struct timezone *tz)
112 : : {
113 [ - + ]: 30 : if (!capable(CAP_SYS_TIME))
114 : 0 : return -EPERM;
115 : : return 0;
116 : : }
117 : :
118 : : /**
119 : : * cap_ptrace_access_check - Determine whether the current process may access
120 : : * another
121 : : * @child: The process to be accessed
122 : : * @mode: The mode of attachment.
123 : : *
124 : : * If we are in the same or an ancestor user_ns and have all the target
125 : : * task's capabilities, then ptrace access is allowed.
126 : : * If we have the ptrace capability to the target user_ns, then ptrace
127 : : * access is allowed.
128 : : * Else denied.
129 : : *
130 : : * Determine whether a process may access another, returning 0 if permission
131 : : * granted, -ve if denied.
132 : : */
133 : 3327 : int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
134 : : {
135 : 3327 : int ret = 0;
136 : 3327 : const struct cred *cred, *child_cred;
137 : 3327 : const kernel_cap_t *caller_caps;
138 : :
139 : 3327 : rcu_read_lock();
140 [ + - ]: 3327 : cred = current_cred();
141 [ + - ]: 3327 : child_cred = __task_cred(child);
142 [ + - ]: 3327 : if (mode & PTRACE_MODE_FSCREDS)
143 : 3327 : caller_caps = &cred->cap_effective;
144 : : else
145 : 0 : caller_caps = &cred->cap_permitted;
146 [ + - + + ]: 6654 : if (cred->user_ns == child_cred->user_ns &&
147 : 3327 : cap_issubset(child_cred->cap_permitted, *caller_caps))
148 : 2955 : goto out;
149 [ + - ]: 372 : if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE))
150 : 372 : goto out;
151 : : ret = -EPERM;
152 : 3327 : out:
153 : 3327 : rcu_read_unlock();
154 : 3327 : return ret;
155 : : }
156 : :
157 : : /**
158 : : * cap_ptrace_traceme - Determine whether another process may trace the current
159 : : * @parent: The task proposed to be the tracer
160 : : *
161 : : * If parent is in the same or an ancestor user_ns and has all current's
162 : : * capabilities, then ptrace access is allowed.
163 : : * If parent has the ptrace capability to current's user_ns, then ptrace
164 : : * access is allowed.
165 : : * Else denied.
166 : : *
167 : : * Determine whether the nominated task is permitted to trace the current
168 : : * process, returning 0 if permission is granted, -ve if denied.
169 : : */
170 : 0 : int cap_ptrace_traceme(struct task_struct *parent)
171 : : {
172 : 0 : int ret = 0;
173 : 0 : const struct cred *cred, *child_cred;
174 : :
175 : 0 : rcu_read_lock();
176 [ # # ]: 0 : cred = __task_cred(parent);
177 [ # # ]: 0 : child_cred = current_cred();
178 [ # # # # ]: 0 : if (cred->user_ns == child_cred->user_ns &&
179 : 0 : cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
180 : 0 : goto out;
181 [ # # ]: 0 : if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE))
182 : 0 : goto out;
183 : : ret = -EPERM;
184 : 0 : out:
185 : 0 : rcu_read_unlock();
186 : 0 : return ret;
187 : : }
188 : :
189 : : /**
190 : : * cap_capget - Retrieve a task's capability sets
191 : : * @target: The task from which to retrieve the capability sets
192 : : * @effective: The place to record the effective set
193 : : * @inheritable: The place to record the inheritable set
194 : : * @permitted: The place to record the permitted set
195 : : *
196 : : * This function retrieves the capabilities of the nominated task and returns
197 : : * them to the caller.
198 : : */
199 : 930 : int cap_capget(struct task_struct *target, kernel_cap_t *effective,
200 : : kernel_cap_t *inheritable, kernel_cap_t *permitted)
201 : : {
202 : 930 : const struct cred *cred;
203 : :
204 : : /* Derived from kernel/capability.c:sys_capget. */
205 : 930 : rcu_read_lock();
206 : 930 : cred = __task_cred(target);
207 : 930 : *effective = cred->cap_effective;
208 : 930 : *inheritable = cred->cap_inheritable;
209 : 930 : *permitted = cred->cap_permitted;
210 : 930 : rcu_read_unlock();
211 : 930 : return 0;
212 : : }
213 : :
214 : : /*
215 : : * Determine whether the inheritable capabilities are limited to the old
216 : : * permitted set. Returns 1 if they are limited, 0 if they are not.
217 : : */
218 : 90 : static inline int cap_inh_is_capped(void)
219 : : {
220 : : /* they are so limited unless the current task has the CAP_SETPCAP
221 : : * capability
222 : : */
223 [ - - ]: 90 : if (cap_capable(current_cred(), current_cred()->user_ns,
224 : : CAP_SETPCAP, CAP_OPT_NONE) == 0)
225 : 90 : return 0;
226 : : return 1;
227 : : }
228 : :
229 : : /**
230 : : * cap_capset - Validate and apply proposed changes to current's capabilities
231 : : * @new: The proposed new credentials; alterations should be made here
232 : : * @old: The current task's current credentials
233 : : * @effective: A pointer to the proposed new effective capabilities set
234 : : * @inheritable: A pointer to the proposed new inheritable capabilities set
235 : : * @permitted: A pointer to the proposed new permitted capabilities set
236 : : *
237 : : * This function validates and applies a proposed mass change to the current
238 : : * process's capability sets. The changes are made to the proposed new
239 : : * credentials, and assuming no error, will be committed by the caller of LSM.
240 : : */
241 : 90 : int cap_capset(struct cred *new,
242 : : const struct cred *old,
243 : : const kernel_cap_t *effective,
244 : : const kernel_cap_t *inheritable,
245 : : const kernel_cap_t *permitted)
246 : : {
247 [ - + - - ]: 90 : if (cap_inh_is_capped() &&
248 : 0 : !cap_issubset(*inheritable,
249 : : cap_combine(old->cap_inheritable,
250 : : old->cap_permitted)))
251 : : /* incapable of using this inheritable set */
252 : : return -EPERM;
253 : :
254 [ + - ]: 180 : if (!cap_issubset(*inheritable,
255 : : cap_combine(old->cap_inheritable,
256 : : old->cap_bset)))
257 : : /* no new pI capabilities outside bounding set */
258 : : return -EPERM;
259 : :
260 : : /* verify restrictions on target's new Permitted set */
261 [ + - ]: 90 : if (!cap_issubset(*permitted, old->cap_permitted))
262 : : return -EPERM;
263 : :
264 : : /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
265 [ + - ]: 90 : if (!cap_issubset(*effective, *permitted))
266 : : return -EPERM;
267 : :
268 : 90 : new->cap_effective = *effective;
269 : 90 : new->cap_inheritable = *inheritable;
270 : 90 : new->cap_permitted = *permitted;
271 : :
272 : : /*
273 : : * Mask off ambient bits that are no longer both permitted and
274 : : * inheritable.
275 : : */
276 : 180 : new->cap_ambient = cap_intersect(new->cap_ambient,
277 : : cap_intersect(*permitted,
278 : : *inheritable));
279 [ - + - + ]: 90 : if (WARN_ON(!cap_ambient_invariant_ok(new)))
280 : 0 : return -EINVAL;
281 : : return 0;
282 : : }
283 : :
284 : : /**
285 : : * cap_inode_need_killpriv - Determine if inode change affects privileges
286 : : * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
287 : : *
288 : : * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
289 : : * affects the security markings on that inode, and if it is, should
290 : : * inode_killpriv() be invoked or the change rejected.
291 : : *
292 : : * Returns 1 if security.capability has a value, meaning inode_killpriv()
293 : : * is required, 0 otherwise, meaning inode_killpriv() is not required.
294 : : */
295 : 24810 : int cap_inode_need_killpriv(struct dentry *dentry)
296 : : {
297 : 24810 : struct inode *inode = d_backing_inode(dentry);
298 : 24810 : int error;
299 : :
300 : 24810 : error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0);
301 : 24810 : return error > 0;
302 : : }
303 : :
304 : : /**
305 : : * cap_inode_killpriv - Erase the security markings on an inode
306 : : * @dentry: The inode/dentry to alter
307 : : *
308 : : * Erase the privilege-enhancing security markings on an inode.
309 : : *
310 : : * Returns 0 if successful, -ve on error.
311 : : */
312 : 0 : int cap_inode_killpriv(struct dentry *dentry)
313 : : {
314 : 0 : int error;
315 : :
316 : 0 : error = __vfs_removexattr(dentry, XATTR_NAME_CAPS);
317 [ # # ]: 0 : if (error == -EOPNOTSUPP)
318 : 0 : error = 0;
319 : 0 : return error;
320 : : }
321 : :
322 : 0 : static bool rootid_owns_currentns(kuid_t kroot)
323 : : {
324 : 0 : struct user_namespace *ns;
325 : :
326 : 0 : if (!uid_valid(kroot))
327 : : return false;
328 : :
329 [ # # # # ]: 0 : for (ns = current_user_ns(); ; ns = ns->parent) {
330 [ # # # # ]: 0 : if (from_kuid(ns, kroot) == 0)
331 : 0 : return true;
332 : : if (ns == &init_user_ns)
333 : : break;
334 : : }
335 : :
336 : : return false;
337 : : }
338 : :
339 : 0 : static __u32 sansflags(__u32 m)
340 : : {
341 : 0 : return m & ~VFS_CAP_FLAGS_EFFECTIVE;
342 : : }
343 : :
344 : 0 : static bool is_v2header(size_t size, const struct vfs_cap_data *cap)
345 : : {
346 : 0 : if (size != XATTR_CAPS_SZ_2)
347 : : return false;
348 : 0 : return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_2;
349 : : }
350 : :
351 : 0 : static bool is_v3header(size_t size, const struct vfs_cap_data *cap)
352 : : {
353 [ # # ]: 0 : if (size != XATTR_CAPS_SZ_3)
354 : : return false;
355 : 0 : return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_3;
356 : : }
357 : :
358 : : /*
359 : : * getsecurity: We are called for security.* before any attempt to read the
360 : : * xattr from the inode itself.
361 : : *
362 : : * This gives us a chance to read the on-disk value and convert it. If we
363 : : * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler.
364 : : *
365 : : * Note we are not called by vfs_getxattr_alloc(), but that is only called
366 : : * by the integrity subsystem, which really wants the unconverted values -
367 : : * so that's good.
368 : : */
369 : 0 : int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
370 : : bool alloc)
371 : : {
372 : 0 : int size, ret;
373 : 0 : kuid_t kroot;
374 : 0 : uid_t root, mappedroot;
375 : 0 : char *tmpbuf = NULL;
376 : 0 : struct vfs_cap_data *cap;
377 : 0 : struct vfs_ns_cap_data *nscap;
378 : 0 : struct dentry *dentry;
379 : 0 : struct user_namespace *fs_ns;
380 : :
381 [ # # ]: 0 : if (strcmp(name, "capability") != 0)
382 : : return -EOPNOTSUPP;
383 : :
384 : 0 : dentry = d_find_any_alias(inode);
385 [ # # ]: 0 : if (!dentry)
386 : : return -EINVAL;
387 : :
388 : 0 : size = sizeof(struct vfs_ns_cap_data);
389 : 0 : ret = (int) vfs_getxattr_alloc(dentry, XATTR_NAME_CAPS,
390 : : &tmpbuf, size, GFP_NOFS);
391 : 0 : dput(dentry);
392 : :
393 [ # # ]: 0 : if (ret < 0)
394 : : return ret;
395 : :
396 : 0 : fs_ns = inode->i_sb->s_user_ns;
397 : 0 : cap = (struct vfs_cap_data *) tmpbuf;
398 [ # # # # ]: 0 : if (is_v2header((size_t) ret, cap)) {
399 : : /* If this is sizeof(vfs_cap_data) then we're ok with the
400 : : * on-disk value, so return that. */
401 [ # # ]: 0 : if (alloc)
402 : 0 : *buffer = tmpbuf;
403 : : else
404 : 0 : kfree(tmpbuf);
405 : 0 : return ret;
406 [ # # # # ]: 0 : } else if (!is_v3header((size_t) ret, cap)) {
407 : 0 : kfree(tmpbuf);
408 : 0 : return -EINVAL;
409 : : }
410 : :
411 : 0 : nscap = (struct vfs_ns_cap_data *) tmpbuf;
412 : 0 : root = le32_to_cpu(nscap->rootid);
413 [ # # ]: 0 : kroot = make_kuid(fs_ns, root);
414 : :
415 : : /* If the root kuid maps to a valid uid in current ns, then return
416 : : * this as a nscap. */
417 [ # # ]: 0 : mappedroot = from_kuid(current_user_ns(), kroot);
418 [ # # ]: 0 : if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) {
419 [ # # ]: 0 : if (alloc) {
420 : 0 : *buffer = tmpbuf;
421 : 0 : nscap->rootid = cpu_to_le32(mappedroot);
422 : : } else
423 : 0 : kfree(tmpbuf);
424 : 0 : return size;
425 : : }
426 : :
427 [ # # ]: 0 : if (!rootid_owns_currentns(kroot)) {
428 : 0 : kfree(tmpbuf);
429 : 0 : return -EOPNOTSUPP;
430 : : }
431 : :
432 : : /* This comes from a parent namespace. Return as a v2 capability */
433 : 0 : size = sizeof(struct vfs_cap_data);
434 [ # # ]: 0 : if (alloc) {
435 : 0 : *buffer = kmalloc(size, GFP_ATOMIC);
436 [ # # ]: 0 : if (*buffer) {
437 : 0 : struct vfs_cap_data *cap = *buffer;
438 : 0 : __le32 nsmagic, magic;
439 : 0 : magic = VFS_CAP_REVISION_2;
440 : 0 : nsmagic = le32_to_cpu(nscap->magic_etc);
441 : 0 : if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE)
442 : : magic |= VFS_CAP_FLAGS_EFFECTIVE;
443 : 0 : memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
444 : 0 : cap->magic_etc = cpu_to_le32(magic);
445 : : } else {
446 : : size = -ENOMEM;
447 : : }
448 : : }
449 : 0 : kfree(tmpbuf);
450 : 0 : return size;
451 : : }
452 : :
453 : 0 : static kuid_t rootid_from_xattr(const void *value, size_t size,
454 : : struct user_namespace *task_ns)
455 : : {
456 : 0 : const struct vfs_ns_cap_data *nscap = value;
457 : 0 : uid_t rootid = 0;
458 : :
459 : 0 : if (size == XATTR_CAPS_SZ_3)
460 : 0 : rootid = le32_to_cpu(nscap->rootid);
461 : :
462 [ # # ]: 0 : return make_kuid(task_ns, rootid);
463 : : }
464 : :
465 : 0 : static bool validheader(size_t size, const struct vfs_cap_data *cap)
466 : : {
467 [ # # # # ]: 0 : return is_v2header(size, cap) || is_v3header(size, cap);
468 : : }
469 : :
470 : : /*
471 : : * User requested a write of security.capability. If needed, update the
472 : : * xattr to change from v2 to v3, or to fixup the v3 rootid.
473 : : *
474 : : * If all is ok, we return the new size, on error return < 0.
475 : : */
476 : 0 : int cap_convert_nscap(struct dentry *dentry, void **ivalue, size_t size)
477 : : {
478 : 0 : struct vfs_ns_cap_data *nscap;
479 : 0 : uid_t nsrootid;
480 : 0 : const struct vfs_cap_data *cap = *ivalue;
481 : 0 : __u32 magic, nsmagic;
482 [ # # ]: 0 : struct inode *inode = d_backing_inode(dentry);
483 [ # # ]: 0 : struct user_namespace *task_ns = current_user_ns(),
484 : : *fs_ns = inode->i_sb->s_user_ns;
485 : 0 : kuid_t rootid;
486 : 0 : size_t newsize;
487 : :
488 [ # # ]: 0 : if (!*ivalue)
489 : : return -EINVAL;
490 [ # # # # ]: 0 : if (!validheader(size, cap))
491 : : return -EINVAL;
492 [ # # ]: 0 : if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
493 : : return -EPERM;
494 [ # # ]: 0 : if (size == XATTR_CAPS_SZ_2)
495 [ # # ]: 0 : if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP))
496 : : /* user is privileged, just write the v2 */
497 : : return size;
498 : :
499 [ # # ]: 0 : rootid = rootid_from_xattr(*ivalue, size, task_ns);
500 [ # # ]: 0 : if (!uid_valid(rootid))
501 : : return -EINVAL;
502 : :
503 : 0 : nsrootid = from_kuid(fs_ns, rootid);
504 : 0 : if (nsrootid == -1)
505 : : return -EINVAL;
506 : :
507 : 0 : newsize = sizeof(struct vfs_ns_cap_data);
508 : 0 : nscap = kmalloc(newsize, GFP_ATOMIC);
509 [ # # ]: 0 : if (!nscap)
510 : : return -ENOMEM;
511 : 0 : nscap->rootid = cpu_to_le32(nsrootid);
512 : 0 : nsmagic = VFS_CAP_REVISION_3;
513 : 0 : magic = le32_to_cpu(cap->magic_etc);
514 : 0 : if (magic & VFS_CAP_FLAGS_EFFECTIVE)
515 : : nsmagic |= VFS_CAP_FLAGS_EFFECTIVE;
516 : 0 : nscap->magic_etc = cpu_to_le32(nsmagic);
517 : 0 : memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
518 : :
519 : 0 : kvfree(*ivalue);
520 : 0 : *ivalue = nscap;
521 : 0 : return newsize;
522 : : }
523 : :
524 : : /*
525 : : * Calculate the new process capability sets from the capability sets attached
526 : : * to a file.
527 : : */
528 : : static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
529 : : struct linux_binprm *bprm,
530 : : bool *effective,
531 : : bool *has_fcap)
532 : : {
533 : : struct cred *new = bprm->cred;
534 : : unsigned i;
535 : : int ret = 0;
536 : :
537 : : if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
538 : : *effective = true;
539 : :
540 : : if (caps->magic_etc & VFS_CAP_REVISION_MASK)
541 : : *has_fcap = true;
542 : :
543 : : CAP_FOR_EACH_U32(i) {
544 : : __u32 permitted = caps->permitted.cap[i];
545 : : __u32 inheritable = caps->inheritable.cap[i];
546 : :
547 : : /*
548 : : * pP' = (X & fP) | (pI & fI)
549 : : * The addition of pA' is handled later.
550 : : */
551 : : new->cap_permitted.cap[i] =
552 : : (new->cap_bset.cap[i] & permitted) |
553 : : (new->cap_inheritable.cap[i] & inheritable);
554 : :
555 : : if (permitted & ~new->cap_permitted.cap[i])
556 : : /* insufficient to execute correctly */
557 : : ret = -EPERM;
558 : : }
559 : :
560 : : /*
561 : : * For legacy apps, with no internal support for recognizing they
562 : : * do not have enough capabilities, we return an error if they are
563 : : * missing some "forced" (aka file-permitted) capabilities.
564 : : */
565 : : return *effective ? ret : 0;
566 : : }
567 : :
568 : : /*
569 : : * Extract the on-exec-apply capability sets for an executable file.
570 : : */
571 : 45186 : int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
572 : : {
573 [ + - ]: 45186 : struct inode *inode = d_backing_inode(dentry);
574 : 45186 : __u32 magic_etc;
575 : 45186 : unsigned tocopy, i;
576 : 45186 : int size;
577 : 45186 : struct vfs_ns_cap_data data, *nscaps = &data;
578 : 45186 : struct vfs_cap_data *caps = (struct vfs_cap_data *) &data;
579 : 45186 : kuid_t rootkuid;
580 : 45186 : struct user_namespace *fs_ns;
581 : :
582 : 45186 : memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
583 : :
584 [ + - ]: 45186 : if (!inode)
585 : : return -ENODATA;
586 : :
587 : 45186 : fs_ns = inode->i_sb->s_user_ns;
588 : 45186 : size = __vfs_getxattr((struct dentry *)dentry, inode,
589 : : XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ);
590 [ - + ]: 45186 : if (size == -ENODATA || size == -EOPNOTSUPP)
591 : : /* no data, that's ok */
592 : : return -ENODATA;
593 : :
594 [ # # ]: 0 : if (size < 0)
595 : : return size;
596 : :
597 [ # # ]: 0 : if (size < sizeof(magic_etc))
598 : : return -EINVAL;
599 : :
600 : 0 : cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc);
601 : :
602 [ # # # # ]: 0 : rootkuid = make_kuid(fs_ns, 0);
603 [ # # # # ]: 0 : switch (magic_etc & VFS_CAP_REVISION_MASK) {
604 : 0 : case VFS_CAP_REVISION_1:
605 [ # # ]: 0 : if (size != XATTR_CAPS_SZ_1)
606 : : return -EINVAL;
607 : : tocopy = VFS_CAP_U32_1;
608 : : break;
609 : 0 : case VFS_CAP_REVISION_2:
610 [ # # ]: 0 : if (size != XATTR_CAPS_SZ_2)
611 : : return -EINVAL;
612 : : tocopy = VFS_CAP_U32_2;
613 : : break;
614 : 0 : case VFS_CAP_REVISION_3:
615 [ # # ]: 0 : if (size != XATTR_CAPS_SZ_3)
616 : : return -EINVAL;
617 : 0 : tocopy = VFS_CAP_U32_3;
618 : 0 : rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid));
619 : : break;
620 : :
621 : : default:
622 : : return -EINVAL;
623 : : }
624 : : /* Limit the caps to the mounter of the filesystem
625 : : * or the more limited uid specified in the xattr.
626 : : */
627 [ # # ]: 0 : if (!rootid_owns_currentns(rootkuid))
628 : : return -ENODATA;
629 : :
630 [ # # ]: 0 : CAP_FOR_EACH_U32(i) {
631 [ # # ]: 0 : if (i >= tocopy)
632 : : break;
633 : 0 : cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted);
634 : 0 : cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable);
635 : : }
636 : :
637 : 0 : cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
638 : 0 : cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
639 : :
640 : 0 : cpu_caps->rootid = rootkuid;
641 : :
642 : 0 : return 0;
643 : : }
644 : :
645 : : /*
646 : : * Attempt to get the on-exec apply capability sets for an executable file from
647 : : * its xattrs and, if present, apply them to the proposed credentials being
648 : : * constructed by execve().
649 : : */
650 : 45186 : static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_fcap)
651 : : {
652 : 45186 : int rc = 0;
653 : 45186 : struct cpu_vfs_cap_data vcaps;
654 : :
655 : 45186 : cap_clear(bprm->cred->cap_permitted);
656 : :
657 [ + - ]: 45186 : if (!file_caps_enabled)
658 : : return 0;
659 : :
660 [ + - ]: 45186 : if (!mnt_may_suid(bprm->file->f_path.mnt))
661 : : return 0;
662 : :
663 : : /*
664 : : * This check is redundant with mnt_may_suid() but is kept to make
665 : : * explicit that capability bits are limited to s_user_ns and its
666 : : * descendants.
667 : : */
668 : 45186 : if (!current_in_userns(bprm->file->f_path.mnt->mnt_sb->s_user_ns))
669 : : return 0;
670 : :
671 : 45186 : rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps);
672 [ + - ]: 45186 : if (rc < 0) {
673 [ - + ]: 45186 : if (rc == -EINVAL)
674 : 0 : printk(KERN_NOTICE "Invalid argument reading file caps for %s\n",
675 : : bprm->filename);
676 [ + - ]: 45186 : else if (rc == -ENODATA)
677 : 45186 : rc = 0;
678 : 0 : goto out;
679 : : }
680 : :
681 : 0 : rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap);
682 : :
683 : 0 : out:
684 [ - - ]: 45186 : if (rc)
685 : 0 : cap_clear(bprm->cred->cap_permitted);
686 : :
687 : : return rc;
688 : : }
689 : :
690 [ + - + - ]: 45156 : static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); }
691 : :
692 : 90372 : static inline bool __is_real(kuid_t uid, struct cred *cred)
693 [ + + - - : 45216 : { return uid_eq(cred->uid, uid); }
- + ]
694 : :
695 : 135528 : static inline bool __is_eff(kuid_t uid, struct cred *cred)
696 [ - + + - : 45156 : { return uid_eq(cred->euid, uid); }
- - ]
697 : :
698 : 45156 : static inline bool __is_suid(kuid_t uid, struct cred *cred)
699 [ + + + - : 45156 : { return !__is_real(uid, cred) && __is_eff(uid, cred); }
- - - - ]
700 : :
701 : : /*
702 : : * handle_privileged_root - Handle case of privileged root
703 : : * @bprm: The execution parameters, including the proposed creds
704 : : * @has_fcap: Are any file capabilities set?
705 : : * @effective: Do we have effective root privilege?
706 : : * @root_uid: This namespace' root UID WRT initial USER namespace
707 : : *
708 : : * Handle the case where root is privileged and hasn't been neutered by
709 : : * SECURE_NOROOT. If file capabilities are set, they won't be combined with
710 : : * set UID root and nothing is changed. If we are root, cap_permitted is
711 : : * updated. If we have become set UID root, the effective bit is set.
712 : : */
713 : 45186 : static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap,
714 : : bool *effective, kuid_t root_uid)
715 : : {
716 [ + - ]: 45186 : const struct cred *old = current_cred();
717 : 45186 : struct cred *new = bprm->cred;
718 : :
719 [ + - ]: 45186 : if (!root_privileged())
720 : : return;
721 : : /*
722 : : * If the legacy file capability is set, then don't set privs
723 : : * for a setuid root binary run by a non-root user. Do set it
724 : : * for a root user just to cause least surprise to an admin.
725 : : */
726 [ - + - - ]: 45186 : if (has_fcap && __is_suid(root_uid, new)) {
727 [ # # ]: 0 : warn_setuid_and_fcaps_mixed(bprm->filename);
728 : 0 : return;
729 : : }
730 : : /*
731 : : * To support inheritance of root-permissions and suid-root
732 : : * executables under compatibility mode, we override the
733 : : * capability sets for the file.
734 : : */
735 [ + + - + ]: 45186 : if (__is_eff(root_uid, new) || __is_real(root_uid, new)) {
736 : : /* pP' = (cap_bset & ~0) | (pI & ~0) */
737 : 90312 : new->cap_permitted = cap_combine(old->cap_bset,
738 : : old->cap_inheritable);
739 : : }
740 : : /*
741 : : * If only the real uid is 0, we do not set the effective bit.
742 : : */
743 [ + + ]: 45186 : if (__is_eff(root_uid, new))
744 : 45156 : *effective = true;
745 : : }
746 : :
747 : : #define __cap_gained(field, target, source) \
748 : : !cap_issubset(target->cap_##field, source->cap_##field)
749 : : #define __cap_grew(target, source, cred) \
750 : : !cap_issubset(cred->cap_##target, cred->cap_##source)
751 : : #define __cap_full(field, cred) \
752 : : cap_issubset(CAP_FULL_SET, cred->cap_##field)
753 : :
754 : 90342 : static inline bool __is_setuid(struct cred *new, const struct cred *old)
755 [ + - ]: 45156 : { return !uid_eq(new->euid, old->uid); }
756 : :
757 : 45186 : static inline bool __is_setgid(struct cred *new, const struct cred *old)
758 [ - + ]: 45186 : { return !gid_eq(new->egid, old->gid); }
759 : :
760 : : /*
761 : : * 1) Audit candidate if current->cap_effective is set
762 : : *
763 : : * We do not bother to audit if 3 things are true:
764 : : * 1) cap_effective has all caps
765 : : * 2) we became root *OR* are were already root
766 : : * 3) root is supposed to have all caps (SECURE_NOROOT)
767 : : * Since this is just a normal root execing a process.
768 : : *
769 : : * Number 1 above might fail if you don't have a full bset, but I think
770 : : * that is interesting information to audit.
771 : : *
772 : : * A number of other conditions require logging:
773 : : * 2) something prevented setuid root getting all caps
774 : : * 3) non-setuid root gets fcaps
775 : : * 4) non-setuid root gets ambient
776 : : */
777 : 45186 : static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old,
778 : : kuid_t root, bool has_fcap)
779 : : {
780 : 45186 : bool ret = false;
781 : :
782 [ + + + + ]: 90342 : if ((__cap_grew(effective, ambient, new) &&
783 [ - + + - ]: 90282 : !(__cap_full(effective, new) &&
784 [ # # ]: 0 : (__is_eff(root, new) || __is_real(root, new)) &&
785 [ + - ]: 45156 : root_privileged())) ||
786 [ - + ]: 45156 : (root_privileged() &&
787 [ # # ]: 0 : __is_suid(root, new) &&
788 [ + - ]: 45156 : !__cap_full(effective, new)) ||
789 [ - + ]: 45156 : (!__is_setuid(new, old) &&
790 [ # # ]: 0 : ((has_fcap &&
791 [ - + ]: 45156 : __cap_gained(permitted, new, old)) ||
792 : 45156 : __cap_gained(ambient, new, old))))
793 : :
794 : : ret = true;
795 : :
796 : 45186 : return ret;
797 : : }
798 : :
799 : : /**
800 : : * cap_bprm_set_creds - Set up the proposed credentials for execve().
801 : : * @bprm: The execution parameters, including the proposed creds
802 : : *
803 : : * Set up the proposed credentials for a new execution context being
804 : : * constructed by execve(). The proposed creds in @bprm->cred is altered,
805 : : * which won't take effect immediately. Returns 0 if successful, -ve on error.
806 : : */
807 : 45186 : int cap_bprm_set_creds(struct linux_binprm *bprm)
808 : : {
809 : 45186 : const struct cred *old = current_cred();
810 : 45186 : struct cred *new = bprm->cred;
811 : 45186 : bool effective = false, has_fcap = false, is_setid;
812 : 45186 : int ret;
813 : 45186 : kuid_t root_uid;
814 : :
815 [ - + + - ]: 45186 : if (WARN_ON(!cap_ambient_invariant_ok(old)))
816 : : return -EPERM;
817 : :
818 : 45186 : ret = get_file_caps(bprm, &effective, &has_fcap);
819 [ + - ]: 45186 : if (ret < 0)
820 : : return ret;
821 : :
822 : 45186 : root_uid = make_kuid(new->user_ns, 0);
823 : :
824 : 45186 : handle_privileged_root(bprm, has_fcap, &effective, root_uid);
825 : :
826 : : /* if we have fs caps, clear dangerous personality flags */
827 [ - + ]: 45186 : if (__cap_gained(permitted, new, old))
828 : 0 : bprm->per_clear |= PER_CLEAR_ON_SETID;
829 : :
830 : : /* Don't let someone trace a set[ug]id/setpcap binary with the revised
831 : : * credentials unless they have the appropriate permit.
832 : : *
833 : : * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
834 : : */
835 [ + - - + ]: 45186 : is_setid = __is_setuid(new, old) || __is_setgid(new, old);
836 : :
837 [ + - - + ]: 45186 : if ((is_setid || __cap_gained(permitted, new, old)) &&
838 [ # # # # ]: 0 : ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) ||
839 : 0 : !ptracer_capable(current, new->user_ns))) {
840 : : /* downgrade; they get no more than they had, and maybe less */
841 [ # # ]: 0 : if (!ns_capable(new->user_ns, CAP_SETUID) ||
842 [ # # ]: 0 : (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
843 : 0 : new->euid = new->uid;
844 : 0 : new->egid = new->gid;
845 : : }
846 : 0 : new->cap_permitted = cap_intersect(new->cap_permitted,
847 : : old->cap_permitted);
848 : : }
849 : :
850 : 45186 : new->suid = new->fsuid = new->euid;
851 : 45186 : new->sgid = new->fsgid = new->egid;
852 : :
853 : : /* File caps or setid cancels ambient. */
854 [ - + ]: 45186 : if (has_fcap || is_setid)
855 : 0 : cap_clear(new->cap_ambient);
856 : :
857 : : /*
858 : : * Now that we've computed pA', update pP' to give:
859 : : * pP' = (X & fP) | (pI & fI) | pA'
860 : : */
861 : 45186 : new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient);
862 : :
863 : : /*
864 : : * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set,
865 : : * this is the same as pE' = (fE ? pP' : 0) | pA'.
866 : : */
867 [ + + ]: 45186 : if (effective)
868 : 45156 : new->cap_effective = new->cap_permitted;
869 : : else
870 : 30 : new->cap_effective = new->cap_ambient;
871 : :
872 [ - + + - ]: 45186 : if (WARN_ON(!cap_ambient_invariant_ok(new)))
873 : : return -EPERM;
874 : :
875 [ + + ]: 45186 : if (nonroot_raised_pE(new, old, root_uid, has_fcap)) {
876 : 30 : ret = audit_log_bprm_fcaps(bprm, new, old);
877 [ + - ]: 30 : if (ret < 0)
878 : : return ret;
879 : : }
880 : :
881 : 45186 : new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
882 : :
883 [ - + + - ]: 45186 : if (WARN_ON(!cap_ambient_invariant_ok(new)))
884 : : return -EPERM;
885 : :
886 : : /* Check for privilege-elevated exec. */
887 : 45186 : bprm->cap_elevated = 0;
888 [ + - + + ]: 45186 : if (is_setid ||
889 : 30 : (!__is_real(root_uid, new) &&
890 [ + - - + ]: 60 : (effective ||
891 : 30 : __cap_grew(permitted, ambient, new))))
892 : 0 : bprm->cap_elevated = 1;
893 : :
894 : : return 0;
895 : : }
896 : :
897 : : /**
898 : : * cap_inode_setxattr - Determine whether an xattr may be altered
899 : : * @dentry: The inode/dentry being altered
900 : : * @name: The name of the xattr to be changed
901 : : * @value: The value that the xattr will be changed to
902 : : * @size: The size of value
903 : : * @flags: The replacement flag
904 : : *
905 : : * Determine whether an xattr may be altered or set on an inode, returning 0 if
906 : : * permission is granted, -ve if denied.
907 : : *
908 : : * This is used to make sure security xattrs don't get updated or set by those
909 : : * who aren't privileged to do so.
910 : : */
911 : 876 : int cap_inode_setxattr(struct dentry *dentry, const char *name,
912 : : const void *value, size_t size, int flags)
913 : : {
914 : 876 : struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
915 : :
916 : : /* Ignore non-security xattrs */
917 [ - + ]: 876 : if (strncmp(name, XATTR_SECURITY_PREFIX,
918 : : XATTR_SECURITY_PREFIX_LEN) != 0)
919 : : return 0;
920 : :
921 : : /*
922 : : * For XATTR_NAME_CAPS the check will be done in
923 : : * cap_convert_nscap(), called by setxattr()
924 : : */
925 [ # # ]: 0 : if (strcmp(name, XATTR_NAME_CAPS) == 0)
926 : : return 0;
927 : :
928 [ # # ]: 0 : if (!ns_capable(user_ns, CAP_SYS_ADMIN))
929 : 0 : return -EPERM;
930 : : return 0;
931 : : }
932 : :
933 : : /**
934 : : * cap_inode_removexattr - Determine whether an xattr may be removed
935 : : * @dentry: The inode/dentry being altered
936 : : * @name: The name of the xattr to be changed
937 : : *
938 : : * Determine whether an xattr may be removed from an inode, returning 0 if
939 : : * permission is granted, -ve if denied.
940 : : *
941 : : * This is used to make sure security xattrs don't get removed by those who
942 : : * aren't privileged to remove them.
943 : : */
944 : 120 : int cap_inode_removexattr(struct dentry *dentry, const char *name)
945 : : {
946 : 120 : struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
947 : :
948 : : /* Ignore non-security xattrs */
949 [ - + ]: 120 : if (strncmp(name, XATTR_SECURITY_PREFIX,
950 : : XATTR_SECURITY_PREFIX_LEN) != 0)
951 : : return 0;
952 : :
953 [ # # ]: 0 : if (strcmp(name, XATTR_NAME_CAPS) == 0) {
954 : : /* security.capability gets namespaced */
955 [ # # ]: 0 : struct inode *inode = d_backing_inode(dentry);
956 [ # # ]: 0 : if (!inode)
957 : : return -EINVAL;
958 [ # # ]: 0 : if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
959 : : return -EPERM;
960 : 0 : return 0;
961 : : }
962 : :
963 [ # # ]: 0 : if (!ns_capable(user_ns, CAP_SYS_ADMIN))
964 : 0 : return -EPERM;
965 : : return 0;
966 : : }
967 : :
968 : : /*
969 : : * cap_emulate_setxuid() fixes the effective / permitted capabilities of
970 : : * a process after a call to setuid, setreuid, or setresuid.
971 : : *
972 : : * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
973 : : * {r,e,s}uid != 0, the permitted and effective capabilities are
974 : : * cleared.
975 : : *
976 : : * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
977 : : * capabilities of the process are cleared.
978 : : *
979 : : * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
980 : : * capabilities are set to the permitted capabilities.
981 : : *
982 : : * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
983 : : * never happen.
984 : : *
985 : : * -astor
986 : : *
987 : : * cevans - New behaviour, Oct '99
988 : : * A process may, via prctl(), elect to keep its capabilities when it
989 : : * calls setuid() and switches away from uid==0. Both permitted and
990 : : * effective sets will be retained.
991 : : * Without this change, it was impossible for a daemon to drop only some
992 : : * of its privilege. The call to setuid(!=0) would drop all privileges!
993 : : * Keeping uid 0 is not an option because uid 0 owns too many vital
994 : : * files..
995 : : * Thanks to Olaf Kirch and Peter Benie for spotting this.
996 : : */
997 : 180 : static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
998 : : {
999 [ + + ]: 180 : kuid_t root_uid = make_kuid(old->user_ns, 0);
1000 : :
1001 [ + + - + ]: 180 : if ((uid_eq(old->uid, root_uid) ||
1002 [ # # ]: 0 : uid_eq(old->euid, root_uid) ||
1003 [ + + ]: 180 : uid_eq(old->suid, root_uid)) &&
1004 [ + + ]: 60 : (!uid_eq(new->uid, root_uid) &&
1005 [ + - ]: 30 : !uid_eq(new->euid, root_uid) &&
1006 : : !uid_eq(new->suid, root_uid))) {
1007 [ - + ]: 30 : if (!issecure(SECURE_KEEP_CAPS)) {
1008 : 0 : cap_clear(new->cap_permitted);
1009 : 0 : cap_clear(new->cap_effective);
1010 : : }
1011 : :
1012 : : /*
1013 : : * Pre-ambient programs expect setresuid to nonroot followed
1014 : : * by exec to drop capabilities. We should make sure that
1015 : : * this remains the case.
1016 : : */
1017 : 30 : cap_clear(new->cap_ambient);
1018 : : }
1019 [ + + + + ]: 180 : if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
1020 : 60 : cap_clear(new->cap_effective);
1021 [ + + + - ]: 180 : if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
1022 : 30 : new->cap_effective = new->cap_permitted;
1023 : 180 : }
1024 : :
1025 : : /**
1026 : : * cap_task_fix_setuid - Fix up the results of setuid() call
1027 : : * @new: The proposed credentials
1028 : : * @old: The current task's current credentials
1029 : : * @flags: Indications of what has changed
1030 : : *
1031 : : * Fix up the results of setuid() call before the credential changes are
1032 : : * actually applied, returning 0 to grant the changes, -ve to deny them.
1033 : : */
1034 : 180 : int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
1035 : : {
1036 [ + - - ]: 180 : switch (flags) {
1037 : : case LSM_SETID_RE:
1038 : : case LSM_SETID_ID:
1039 : : case LSM_SETID_RES:
1040 : : /* juggle the capabilities to follow [RES]UID changes unless
1041 : : * otherwise suppressed */
1042 [ + - ]: 180 : if (!issecure(SECURE_NO_SETUID_FIXUP))
1043 : 180 : cap_emulate_setxuid(new, old);
1044 : : break;
1045 : :
1046 : : case LSM_SETID_FS:
1047 : : /* juggle the capabilties to follow FSUID changes, unless
1048 : : * otherwise suppressed
1049 : : *
1050 : : * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
1051 : : * if not, we might be a bit too harsh here.
1052 : : */
1053 [ # # ]: 0 : if (!issecure(SECURE_NO_SETUID_FIXUP)) {
1054 [ # # ]: 0 : kuid_t root_uid = make_kuid(old->user_ns, 0);
1055 [ # # # # ]: 0 : if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
1056 : 0 : new->cap_effective =
1057 : 0 : cap_drop_fs_set(new->cap_effective);
1058 : :
1059 [ # # # # ]: 0 : if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
1060 : 0 : new->cap_effective =
1061 : 0 : cap_raise_fs_set(new->cap_effective,
1062 : : new->cap_permitted);
1063 : : }
1064 : : break;
1065 : :
1066 : : default:
1067 : : return -EINVAL;
1068 : : }
1069 : :
1070 : : return 0;
1071 : : }
1072 : :
1073 : : /*
1074 : : * Rationale: code calling task_setscheduler, task_setioprio, and
1075 : : * task_setnice, assumes that
1076 : : * . if capable(cap_sys_nice), then those actions should be allowed
1077 : : * . if not capable(cap_sys_nice), but acting on your own processes,
1078 : : * then those actions should be allowed
1079 : : * This is insufficient now since you can call code without suid, but
1080 : : * yet with increased caps.
1081 : : * So we check for increased caps on the target process.
1082 : : */
1083 : 180 : static int cap_safe_nice(struct task_struct *p)
1084 : : {
1085 : 180 : int is_subset, ret = 0;
1086 : :
1087 : 180 : rcu_read_lock();
1088 : 180 : is_subset = cap_issubset(__task_cred(p)->cap_permitted,
1089 : 180 : current_cred()->cap_permitted);
1090 [ - + - - ]: 180 : if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE))
1091 : 0 : ret = -EPERM;
1092 : 180 : rcu_read_unlock();
1093 : :
1094 : 180 : return ret;
1095 : : }
1096 : :
1097 : : /**
1098 : : * cap_task_setscheduler - Detemine if scheduler policy change is permitted
1099 : : * @p: The task to affect
1100 : : *
1101 : : * Detemine if the requested scheduler policy change is permitted for the
1102 : : * specified task, returning 0 if permission is granted, -ve if denied.
1103 : : */
1104 : 90 : int cap_task_setscheduler(struct task_struct *p)
1105 : : {
1106 : 90 : return cap_safe_nice(p);
1107 : : }
1108 : :
1109 : : /**
1110 : : * cap_task_ioprio - Detemine if I/O priority change is permitted
1111 : : * @p: The task to affect
1112 : : * @ioprio: The I/O priority to set
1113 : : *
1114 : : * Detemine if the requested I/O priority change is permitted for the specified
1115 : : * task, returning 0 if permission is granted, -ve if denied.
1116 : : */
1117 : 90 : int cap_task_setioprio(struct task_struct *p, int ioprio)
1118 : : {
1119 : 90 : return cap_safe_nice(p);
1120 : : }
1121 : :
1122 : : /**
1123 : : * cap_task_ioprio - Detemine if task priority change is permitted
1124 : : * @p: The task to affect
1125 : : * @nice: The nice value to set
1126 : : *
1127 : : * Detemine if the requested task priority change is permitted for the
1128 : : * specified task, returning 0 if permission is granted, -ve if denied.
1129 : : */
1130 : 0 : int cap_task_setnice(struct task_struct *p, int nice)
1131 : : {
1132 : 0 : return cap_safe_nice(p);
1133 : : }
1134 : :
1135 : : /*
1136 : : * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from
1137 : : * the current task's bounding set. Returns 0 on success, -ve on error.
1138 : : */
1139 : 1890 : static int cap_prctl_drop(unsigned long cap)
1140 : : {
1141 : 1890 : struct cred *new;
1142 : :
1143 [ + - ]: 1890 : if (!ns_capable(current_user_ns(), CAP_SETPCAP))
1144 : : return -EPERM;
1145 [ + - ]: 1890 : if (!cap_valid(cap))
1146 : : return -EINVAL;
1147 : :
1148 : 1890 : new = prepare_creds();
1149 [ + - ]: 1890 : if (!new)
1150 : : return -ENOMEM;
1151 : 1890 : cap_lower(new->cap_bset, cap);
1152 : 1890 : return commit_creds(new);
1153 : : }
1154 : :
1155 : : /**
1156 : : * cap_task_prctl - Implement process control functions for this security module
1157 : : * @option: The process control function requested
1158 : : * @arg2, @arg3, @arg4, @arg5: The argument data for this function
1159 : : *
1160 : : * Allow process control functions (sys_prctl()) to alter capabilities; may
1161 : : * also deny access to other functions not otherwise implemented here.
1162 : : *
1163 : : * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
1164 : : * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM
1165 : : * modules will consider performing the function.
1166 : : */
1167 : 9146 : int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
1168 : : unsigned long arg4, unsigned long arg5)
1169 : : {
1170 [ - + + + : 9146 : const struct cred *old = current_cred();
- - + + ]
1171 : 9146 : struct cred *new;
1172 : :
1173 [ - + + + : 9146 : switch (option) {
- - + + ]
1174 : 0 : case PR_CAPBSET_READ:
1175 [ # # ]: 0 : if (!cap_valid(arg2))
1176 : : return -EINVAL;
1177 : 0 : return !!cap_raised(old->cap_bset, arg2);
1178 : :
1179 : 1890 : case PR_CAPBSET_DROP:
1180 : 1890 : return cap_prctl_drop(arg2);
1181 : :
1182 : : /*
1183 : : * The next four prctl's remain to assist with transitioning a
1184 : : * system from legacy UID=0 based privilege (when filesystem
1185 : : * capabilities are not in use) to a system using filesystem
1186 : : * capabilities only - as the POSIX.1e draft intended.
1187 : : *
1188 : : * Note:
1189 : : *
1190 : : * PR_SET_SECUREBITS =
1191 : : * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
1192 : : * | issecure_mask(SECURE_NOROOT)
1193 : : * | issecure_mask(SECURE_NOROOT_LOCKED)
1194 : : * | issecure_mask(SECURE_NO_SETUID_FIXUP)
1195 : : * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
1196 : : *
1197 : : * will ensure that the current process and all of its
1198 : : * children will be locked into a pure
1199 : : * capability-based-privilege environment.
1200 : : */
1201 : 30 : case PR_SET_SECUREBITS:
1202 : 30 : if ((((old->securebits & SECURE_ALL_LOCKS) >> 1)
1203 [ + - ]: 30 : & (old->securebits ^ arg2)) /*[1]*/
1204 [ + - ]: 30 : || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/
1205 [ + - ]: 30 : || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
1206 [ - - ]: 30 : || (cap_capable(current_cred(),
1207 : 30 : current_cred()->user_ns,
1208 : : CAP_SETPCAP,
1209 : : CAP_OPT_NONE) != 0) /*[4]*/
1210 : : /*
1211 : : * [1] no changing of bits that are locked
1212 : : * [2] no unlocking of locks
1213 : : * [3] no setting of unsupported bits
1214 : : * [4] doing anything requires privilege (go read about
1215 : : * the "sendmail capabilities bug")
1216 : : */
1217 : : )
1218 : : /* cannot change a locked bit */
1219 : : return -EPERM;
1220 : :
1221 : 30 : new = prepare_creds();
1222 [ + - ]: 30 : if (!new)
1223 : : return -ENOMEM;
1224 : 30 : new->securebits = arg2;
1225 : 30 : return commit_creds(new);
1226 : :
1227 : 876 : case PR_GET_SECUREBITS:
1228 : 876 : return old->securebits;
1229 : :
1230 : : case PR_GET_KEEPCAPS:
1231 : 0 : return !!issecure(SECURE_KEEP_CAPS);
1232 : :
1233 : 0 : case PR_SET_KEEPCAPS:
1234 [ # # ]: 0 : if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
1235 : : return -EINVAL;
1236 [ # # ]: 0 : if (issecure(SECURE_KEEP_CAPS_LOCKED))
1237 : : return -EPERM;
1238 : :
1239 : 0 : new = prepare_creds();
1240 [ # # ]: 0 : if (!new)
1241 : : return -ENOMEM;
1242 [ # # ]: 0 : if (arg2)
1243 : 0 : new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
1244 : : else
1245 : 0 : new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
1246 : 0 : return commit_creds(new);
1247 : :
1248 : 90 : case PR_CAP_AMBIENT:
1249 [ - + ]: 90 : if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) {
1250 [ # # ]: 0 : if (arg3 | arg4 | arg5)
1251 : : return -EINVAL;
1252 : :
1253 : 0 : new = prepare_creds();
1254 [ # # ]: 0 : if (!new)
1255 : : return -ENOMEM;
1256 : 0 : cap_clear(new->cap_ambient);
1257 : 0 : return commit_creds(new);
1258 : : }
1259 : :
1260 [ + - ]: 90 : if (((!cap_valid(arg3)) | arg4 | arg5))
1261 : : return -EINVAL;
1262 : :
1263 [ + + ]: 90 : if (arg2 == PR_CAP_AMBIENT_IS_SET) {
1264 : 30 : return !!cap_raised(current_cred()->cap_ambient, arg3);
1265 [ + - ]: 60 : } else if (arg2 != PR_CAP_AMBIENT_RAISE &&
1266 : : arg2 != PR_CAP_AMBIENT_LOWER) {
1267 : : return -EINVAL;
1268 : : } else {
1269 [ + - + - ]: 60 : if (arg2 == PR_CAP_AMBIENT_RAISE &&
1270 [ + - + - ]: 60 : (!cap_raised(current_cred()->cap_permitted, arg3) ||
1271 [ + - ]: 60 : !cap_raised(current_cred()->cap_inheritable,
1272 [ + - ]: 60 : arg3) ||
1273 [ + - ]: 60 : issecure(SECURE_NO_CAP_AMBIENT_RAISE)))
1274 : : return -EPERM;
1275 : :
1276 : 60 : new = prepare_creds();
1277 [ + - ]: 60 : if (!new)
1278 : : return -ENOMEM;
1279 [ + - ]: 60 : if (arg2 == PR_CAP_AMBIENT_RAISE)
1280 : 60 : cap_raise(new->cap_ambient, arg3);
1281 : : else
1282 : 0 : cap_lower(new->cap_ambient, arg3);
1283 : 60 : return commit_creds(new);
1284 : : }
1285 : :
1286 : : default:
1287 : : /* No functionality available - continue with default */
1288 : : return -ENOSYS;
1289 : : }
1290 : : }
1291 : :
1292 : : /**
1293 : : * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
1294 : : * @mm: The VM space in which the new mapping is to be made
1295 : : * @pages: The size of the mapping
1296 : : *
1297 : : * Determine whether the allocation of a new virtual mapping by the current
1298 : : * task is permitted, returning 1 if permission is granted, 0 if not.
1299 : : */
1300 : 1538864 : int cap_vm_enough_memory(struct mm_struct *mm, long pages)
1301 : : {
1302 : 1538864 : int cap_sys_admin = 0;
1303 : :
1304 [ - - ]: 1538864 : if (cap_capable(current_cred(), &init_user_ns,
1305 : : CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0)
1306 : 1537184 : cap_sys_admin = 1;
1307 : :
1308 : 1538864 : return cap_sys_admin;
1309 : : }
1310 : :
1311 : : /*
1312 : : * cap_mmap_addr - check if able to map given addr
1313 : : * @addr: address attempting to be mapped
1314 : : *
1315 : : * If the process is attempting to map memory below dac_mmap_min_addr they need
1316 : : * CAP_SYS_RAWIO. The other parameters to this function are unused by the
1317 : : * capability security module. Returns 0 if this mapping should be allowed
1318 : : * -EPERM if not.
1319 : : */
1320 : 1436772 : int cap_mmap_addr(unsigned long addr)
1321 : : {
1322 : 1436772 : int ret = 0;
1323 : :
1324 [ - + ]: 1436772 : if (addr < dac_mmap_min_addr) {
1325 : 0 : ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
1326 : : CAP_OPT_NONE);
1327 : : /* set PF_SUPERPRIV if it turns out we allow the low mmap */
1328 [ # # ]: 0 : if (ret == 0)
1329 : 0 : current->flags |= PF_SUPERPRIV;
1330 : : }
1331 : 1436772 : return ret;
1332 : : }
1333 : :
1334 : 1283040 : int cap_mmap_file(struct file *file, unsigned long reqprot,
1335 : : unsigned long prot, unsigned long flags)
1336 : : {
1337 : 1283040 : return 0;
1338 : : }
1339 : :
1340 : : #ifdef CONFIG_SECURITY
1341 : :
1342 : : static struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
1343 : : LSM_HOOK_INIT(capable, cap_capable),
1344 : : LSM_HOOK_INIT(settime, cap_settime),
1345 : : LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
1346 : : LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
1347 : : LSM_HOOK_INIT(capget, cap_capget),
1348 : : LSM_HOOK_INIT(capset, cap_capset),
1349 : : LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds),
1350 : : LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
1351 : : LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
1352 : : LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity),
1353 : : LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
1354 : : LSM_HOOK_INIT(mmap_file, cap_mmap_file),
1355 : : LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
1356 : : LSM_HOOK_INIT(task_prctl, cap_task_prctl),
1357 : : LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler),
1358 : : LSM_HOOK_INIT(task_setioprio, cap_task_setioprio),
1359 : : LSM_HOOK_INIT(task_setnice, cap_task_setnice),
1360 : : LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
1361 : : };
1362 : :
1363 : 30 : static int __init capability_init(void)
1364 : : {
1365 : 30 : security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
1366 : : "capability");
1367 : 30 : return 0;
1368 : : }
1369 : :
1370 : : DEFINE_LSM(capability) = {
1371 : : .name = "capability",
1372 : : .order = LSM_ORDER_FIRST,
1373 : : .init = capability_init,
1374 : : };
1375 : :
1376 : : #endif /* CONFIG_SECURITY */
|
