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3e1c2515 | 1 | /* Common capabilities, needed by capability.o. |
1da177e4 LT |
2 | * |
3 | * This program is free software; you can redistribute it and/or modify | |
4 | * it under the terms of the GNU General Public License as published by | |
5 | * the Free Software Foundation; either version 2 of the License, or | |
6 | * (at your option) any later version. | |
7 | * | |
8 | */ | |
9 | ||
c59ede7b | 10 | #include <linux/capability.h> |
3fc689e9 | 11 | #include <linux/audit.h> |
1da177e4 LT |
12 | #include <linux/module.h> |
13 | #include <linux/init.h> | |
14 | #include <linux/kernel.h> | |
b1d9e6b0 | 15 | #include <linux/lsm_hooks.h> |
1da177e4 LT |
16 | #include <linux/file.h> |
17 | #include <linux/mm.h> | |
18 | #include <linux/mman.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/swap.h> | |
1da177e4 LT |
21 | #include <linux/skbuff.h> |
22 | #include <linux/netlink.h> | |
23 | #include <linux/ptrace.h> | |
24 | #include <linux/xattr.h> | |
25 | #include <linux/hugetlb.h> | |
b5376771 | 26 | #include <linux/mount.h> |
b460cbc5 | 27 | #include <linux/sched.h> |
3898b1b4 AM |
28 | #include <linux/prctl.h> |
29 | #include <linux/securebits.h> | |
3486740a | 30 | #include <linux/user_namespace.h> |
40401530 | 31 | #include <linux/binfmts.h> |
51b79bee | 32 | #include <linux/personality.h> |
72c2d582 | 33 | |
b5f22a59 SH |
34 | /* |
35 | * If a non-root user executes a setuid-root binary in | |
36 | * !secure(SECURE_NOROOT) mode, then we raise capabilities. | |
37 | * However if fE is also set, then the intent is for only | |
38 | * the file capabilities to be applied, and the setuid-root | |
39 | * bit is left on either to change the uid (plausible) or | |
40 | * to get full privilege on a kernel without file capabilities | |
41 | * support. So in that case we do not raise capabilities. | |
42 | * | |
43 | * Warn if that happens, once per boot. | |
44 | */ | |
d7627467 | 45 | static void warn_setuid_and_fcaps_mixed(const char *fname) |
b5f22a59 SH |
46 | { |
47 | static int warned; | |
48 | if (!warned) { | |
49 | printk(KERN_INFO "warning: `%s' has both setuid-root and" | |
50 | " effective capabilities. Therefore not raising all" | |
51 | " capabilities.\n", fname); | |
52 | warned = 1; | |
53 | } | |
54 | } | |
55 | ||
1d045980 DH |
56 | /** |
57 | * cap_capable - Determine whether a task has a particular effective capability | |
3699c53c | 58 | * @cred: The credentials to use |
3486740a | 59 | * @ns: The user namespace in which we need the capability |
1d045980 DH |
60 | * @cap: The capability to check for |
61 | * @audit: Whether to write an audit message or not | |
62 | * | |
63 | * Determine whether the nominated task has the specified capability amongst | |
64 | * its effective set, returning 0 if it does, -ve if it does not. | |
65 | * | |
3699c53c DH |
66 | * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable() |
67 | * and has_capability() functions. That is, it has the reverse semantics: | |
68 | * cap_has_capability() returns 0 when a task has a capability, but the | |
69 | * kernel's capable() and has_capability() returns 1 for this case. | |
a6dbb1ef | 70 | */ |
6a9de491 EP |
71 | int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, |
72 | int cap, int audit) | |
1da177e4 | 73 | { |
520d9eab | 74 | struct user_namespace *ns = targ_ns; |
3486740a | 75 | |
520d9eab EB |
76 | /* See if cred has the capability in the target user namespace |
77 | * by examining the target user namespace and all of the target | |
78 | * user namespace's parents. | |
79 | */ | |
80 | for (;;) { | |
3486740a | 81 | /* Do we have the necessary capabilities? */ |
520d9eab | 82 | if (ns == cred->user_ns) |
3486740a SH |
83 | return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; |
84 | ||
85 | /* Have we tried all of the parent namespaces? */ | |
520d9eab | 86 | if (ns == &init_user_ns) |
3486740a SH |
87 | return -EPERM; |
88 | ||
520d9eab EB |
89 | /* |
90 | * The owner of the user namespace in the parent of the | |
91 | * user namespace has all caps. | |
92 | */ | |
93 | if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) | |
94 | return 0; | |
95 | ||
3486740a | 96 | /* |
520d9eab | 97 | * If you have a capability in a parent user ns, then you have |
3486740a SH |
98 | * it over all children user namespaces as well. |
99 | */ | |
520d9eab | 100 | ns = ns->parent; |
3486740a SH |
101 | } |
102 | ||
103 | /* We never get here */ | |
1da177e4 LT |
104 | } |
105 | ||
1d045980 DH |
106 | /** |
107 | * cap_settime - Determine whether the current process may set the system clock | |
108 | * @ts: The time to set | |
109 | * @tz: The timezone to set | |
110 | * | |
111 | * Determine whether the current process may set the system clock and timezone | |
112 | * information, returning 0 if permission granted, -ve if denied. | |
113 | */ | |
457db29b | 114 | int cap_settime(const struct timespec64 *ts, const struct timezone *tz) |
1da177e4 LT |
115 | { |
116 | if (!capable(CAP_SYS_TIME)) | |
117 | return -EPERM; | |
118 | return 0; | |
119 | } | |
120 | ||
1d045980 | 121 | /** |
9e48858f | 122 | * cap_ptrace_access_check - Determine whether the current process may access |
1d045980 DH |
123 | * another |
124 | * @child: The process to be accessed | |
125 | * @mode: The mode of attachment. | |
126 | * | |
8409cca7 SH |
127 | * If we are in the same or an ancestor user_ns and have all the target |
128 | * task's capabilities, then ptrace access is allowed. | |
129 | * If we have the ptrace capability to the target user_ns, then ptrace | |
130 | * access is allowed. | |
131 | * Else denied. | |
132 | * | |
1d045980 DH |
133 | * Determine whether a process may access another, returning 0 if permission |
134 | * granted, -ve if denied. | |
135 | */ | |
9e48858f | 136 | int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) |
1da177e4 | 137 | { |
c69e8d9c | 138 | int ret = 0; |
8409cca7 | 139 | const struct cred *cred, *child_cred; |
caaee623 | 140 | const kernel_cap_t *caller_caps; |
c69e8d9c DH |
141 | |
142 | rcu_read_lock(); | |
8409cca7 SH |
143 | cred = current_cred(); |
144 | child_cred = __task_cred(child); | |
caaee623 JH |
145 | if (mode & PTRACE_MODE_FSCREDS) |
146 | caller_caps = &cred->cap_effective; | |
147 | else | |
148 | caller_caps = &cred->cap_permitted; | |
c4a4d603 | 149 | if (cred->user_ns == child_cred->user_ns && |
caaee623 | 150 | cap_issubset(child_cred->cap_permitted, *caller_caps)) |
8409cca7 | 151 | goto out; |
c4a4d603 | 152 | if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE)) |
8409cca7 SH |
153 | goto out; |
154 | ret = -EPERM; | |
155 | out: | |
c69e8d9c DH |
156 | rcu_read_unlock(); |
157 | return ret; | |
5cd9c58f DH |
158 | } |
159 | ||
1d045980 DH |
160 | /** |
161 | * cap_ptrace_traceme - Determine whether another process may trace the current | |
162 | * @parent: The task proposed to be the tracer | |
163 | * | |
8409cca7 SH |
164 | * If parent is in the same or an ancestor user_ns and has all current's |
165 | * capabilities, then ptrace access is allowed. | |
166 | * If parent has the ptrace capability to current's user_ns, then ptrace | |
167 | * access is allowed. | |
168 | * Else denied. | |
169 | * | |
1d045980 DH |
170 | * Determine whether the nominated task is permitted to trace the current |
171 | * process, returning 0 if permission is granted, -ve if denied. | |
172 | */ | |
5cd9c58f DH |
173 | int cap_ptrace_traceme(struct task_struct *parent) |
174 | { | |
c69e8d9c | 175 | int ret = 0; |
8409cca7 | 176 | const struct cred *cred, *child_cred; |
c69e8d9c DH |
177 | |
178 | rcu_read_lock(); | |
8409cca7 SH |
179 | cred = __task_cred(parent); |
180 | child_cred = current_cred(); | |
c4a4d603 | 181 | if (cred->user_ns == child_cred->user_ns && |
8409cca7 SH |
182 | cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) |
183 | goto out; | |
c4a4d603 | 184 | if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE)) |
8409cca7 SH |
185 | goto out; |
186 | ret = -EPERM; | |
187 | out: | |
c69e8d9c DH |
188 | rcu_read_unlock(); |
189 | return ret; | |
1da177e4 LT |
190 | } |
191 | ||
1d045980 DH |
192 | /** |
193 | * cap_capget - Retrieve a task's capability sets | |
194 | * @target: The task from which to retrieve the capability sets | |
195 | * @effective: The place to record the effective set | |
196 | * @inheritable: The place to record the inheritable set | |
197 | * @permitted: The place to record the permitted set | |
198 | * | |
199 | * This function retrieves the capabilities of the nominated task and returns | |
200 | * them to the caller. | |
201 | */ | |
202 | int cap_capget(struct task_struct *target, kernel_cap_t *effective, | |
203 | kernel_cap_t *inheritable, kernel_cap_t *permitted) | |
1da177e4 | 204 | { |
c69e8d9c | 205 | const struct cred *cred; |
b6dff3ec | 206 | |
1da177e4 | 207 | /* Derived from kernel/capability.c:sys_capget. */ |
c69e8d9c DH |
208 | rcu_read_lock(); |
209 | cred = __task_cred(target); | |
b6dff3ec DH |
210 | *effective = cred->cap_effective; |
211 | *inheritable = cred->cap_inheritable; | |
212 | *permitted = cred->cap_permitted; | |
c69e8d9c | 213 | rcu_read_unlock(); |
1da177e4 LT |
214 | return 0; |
215 | } | |
216 | ||
1d045980 DH |
217 | /* |
218 | * Determine whether the inheritable capabilities are limited to the old | |
219 | * permitted set. Returns 1 if they are limited, 0 if they are not. | |
220 | */ | |
72c2d582 AM |
221 | static inline int cap_inh_is_capped(void) |
222 | { | |
72c2d582 | 223 | |
1d045980 DH |
224 | /* they are so limited unless the current task has the CAP_SETPCAP |
225 | * capability | |
226 | */ | |
c4a4d603 | 227 | if (cap_capable(current_cred(), current_cred()->user_ns, |
6a9de491 | 228 | CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0) |
1d045980 | 229 | return 0; |
1d045980 | 230 | return 1; |
1209726c | 231 | } |
72c2d582 | 232 | |
1d045980 DH |
233 | /** |
234 | * cap_capset - Validate and apply proposed changes to current's capabilities | |
235 | * @new: The proposed new credentials; alterations should be made here | |
236 | * @old: The current task's current credentials | |
237 | * @effective: A pointer to the proposed new effective capabilities set | |
238 | * @inheritable: A pointer to the proposed new inheritable capabilities set | |
239 | * @permitted: A pointer to the proposed new permitted capabilities set | |
240 | * | |
241 | * This function validates and applies a proposed mass change to the current | |
242 | * process's capability sets. The changes are made to the proposed new | |
243 | * credentials, and assuming no error, will be committed by the caller of LSM. | |
244 | */ | |
d84f4f99 DH |
245 | int cap_capset(struct cred *new, |
246 | const struct cred *old, | |
247 | const kernel_cap_t *effective, | |
248 | const kernel_cap_t *inheritable, | |
249 | const kernel_cap_t *permitted) | |
1da177e4 | 250 | { |
d84f4f99 DH |
251 | if (cap_inh_is_capped() && |
252 | !cap_issubset(*inheritable, | |
253 | cap_combine(old->cap_inheritable, | |
254 | old->cap_permitted))) | |
72c2d582 | 255 | /* incapable of using this inheritable set */ |
1da177e4 | 256 | return -EPERM; |
d84f4f99 | 257 | |
3b7391de | 258 | if (!cap_issubset(*inheritable, |
d84f4f99 DH |
259 | cap_combine(old->cap_inheritable, |
260 | old->cap_bset))) | |
3b7391de SH |
261 | /* no new pI capabilities outside bounding set */ |
262 | return -EPERM; | |
1da177e4 LT |
263 | |
264 | /* verify restrictions on target's new Permitted set */ | |
d84f4f99 | 265 | if (!cap_issubset(*permitted, old->cap_permitted)) |
1da177e4 | 266 | return -EPERM; |
1da177e4 LT |
267 | |
268 | /* verify the _new_Effective_ is a subset of the _new_Permitted_ */ | |
d84f4f99 | 269 | if (!cap_issubset(*effective, *permitted)) |
1da177e4 | 270 | return -EPERM; |
1da177e4 | 271 | |
d84f4f99 DH |
272 | new->cap_effective = *effective; |
273 | new->cap_inheritable = *inheritable; | |
274 | new->cap_permitted = *permitted; | |
58319057 AL |
275 | |
276 | /* | |
277 | * Mask off ambient bits that are no longer both permitted and | |
278 | * inheritable. | |
279 | */ | |
280 | new->cap_ambient = cap_intersect(new->cap_ambient, | |
281 | cap_intersect(*permitted, | |
282 | *inheritable)); | |
283 | if (WARN_ON(!cap_ambient_invariant_ok(new))) | |
284 | return -EINVAL; | |
1da177e4 LT |
285 | return 0; |
286 | } | |
287 | ||
1d045980 DH |
288 | /* |
289 | * Clear proposed capability sets for execve(). | |
290 | */ | |
b5376771 SH |
291 | static inline void bprm_clear_caps(struct linux_binprm *bprm) |
292 | { | |
a6f76f23 | 293 | cap_clear(bprm->cred->cap_permitted); |
b5376771 SH |
294 | bprm->cap_effective = false; |
295 | } | |
296 | ||
1d045980 DH |
297 | /** |
298 | * cap_inode_need_killpriv - Determine if inode change affects privileges | |
299 | * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV | |
300 | * | |
301 | * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV | |
302 | * affects the security markings on that inode, and if it is, should | |
303 | * inode_killpriv() be invoked or the change rejected? | |
304 | * | |
305 | * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and | |
306 | * -ve to deny the change. | |
307 | */ | |
b5376771 SH |
308 | int cap_inode_need_killpriv(struct dentry *dentry) |
309 | { | |
c6f493d6 | 310 | struct inode *inode = d_backing_inode(dentry); |
b5376771 SH |
311 | int error; |
312 | ||
5d6c3191 AG |
313 | error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); |
314 | return error > 0; | |
b5376771 SH |
315 | } |
316 | ||
1d045980 DH |
317 | /** |
318 | * cap_inode_killpriv - Erase the security markings on an inode | |
319 | * @dentry: The inode/dentry to alter | |
320 | * | |
321 | * Erase the privilege-enhancing security markings on an inode. | |
322 | * | |
323 | * Returns 0 if successful, -ve on error. | |
324 | */ | |
b5376771 SH |
325 | int cap_inode_killpriv(struct dentry *dentry) |
326 | { | |
5d6c3191 | 327 | int error; |
b5376771 | 328 | |
5d6c3191 AG |
329 | error = __vfs_removexattr(dentry, XATTR_NAME_CAPS); |
330 | if (error == -EOPNOTSUPP) | |
331 | error = 0; | |
332 | return error; | |
b5376771 SH |
333 | } |
334 | ||
d7acd1fa SH |
335 | static bool rootid_owns_currentns(kuid_t kroot) |
336 | { | |
337 | struct user_namespace *ns; | |
338 | ||
339 | if (!uid_valid(kroot)) | |
340 | return false; | |
341 | ||
342 | for (ns = current_user_ns(); ; ns = ns->parent) { | |
343 | if (from_kuid(ns, kroot) == 0) | |
344 | return true; | |
345 | if (ns == &init_user_ns) | |
346 | break; | |
347 | } | |
348 | ||
349 | return false; | |
350 | } | |
351 | ||
352 | static __u32 sansflags(__u32 m) | |
353 | { | |
354 | return m & ~VFS_CAP_FLAGS_EFFECTIVE; | |
355 | } | |
356 | ||
357 | static bool is_v2header(size_t size, __le32 magic) | |
358 | { | |
359 | __u32 m = le32_to_cpu(magic); | |
360 | if (size != XATTR_CAPS_SZ_2) | |
361 | return false; | |
362 | return sansflags(m) == VFS_CAP_REVISION_2; | |
363 | } | |
364 | ||
365 | static bool is_v3header(size_t size, __le32 magic) | |
366 | { | |
367 | __u32 m = le32_to_cpu(magic); | |
368 | ||
369 | if (size != XATTR_CAPS_SZ_3) | |
370 | return false; | |
371 | return sansflags(m) == VFS_CAP_REVISION_3; | |
372 | } | |
373 | ||
374 | /* | |
375 | * getsecurity: We are called for security.* before any attempt to read the | |
376 | * xattr from the inode itself. | |
377 | * | |
378 | * This gives us a chance to read the on-disk value and convert it. If we | |
379 | * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler. | |
380 | * | |
381 | * Note we are not called by vfs_getxattr_alloc(), but that is only called | |
382 | * by the integrity subsystem, which really wants the unconverted values - | |
383 | * so that's good. | |
384 | */ | |
385 | int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer, | |
386 | bool alloc) | |
387 | { | |
388 | int size, ret; | |
389 | kuid_t kroot; | |
390 | uid_t root, mappedroot; | |
391 | char *tmpbuf = NULL; | |
392 | struct vfs_cap_data *cap; | |
393 | struct vfs_ns_cap_data *nscap; | |
394 | struct dentry *dentry; | |
395 | struct user_namespace *fs_ns; | |
396 | ||
397 | if (strcmp(name, "capability") != 0) | |
398 | return -EOPNOTSUPP; | |
399 | ||
400 | dentry = d_find_alias(inode); | |
401 | if (!dentry) | |
402 | return -EINVAL; | |
403 | ||
404 | size = sizeof(struct vfs_ns_cap_data); | |
405 | ret = (int) vfs_getxattr_alloc(dentry, XATTR_NAME_CAPS, | |
406 | &tmpbuf, size, GFP_NOFS); | |
407 | dput(dentry); | |
408 | ||
409 | if (ret < 0) | |
410 | return ret; | |
411 | ||
412 | fs_ns = inode->i_sb->s_user_ns; | |
413 | cap = (struct vfs_cap_data *) tmpbuf; | |
414 | if (is_v2header((size_t) ret, cap->magic_etc)) { | |
415 | /* If this is sizeof(vfs_cap_data) then we're ok with the | |
416 | * on-disk value, so return that. */ | |
417 | if (alloc) | |
418 | *buffer = tmpbuf; | |
419 | else | |
420 | kfree(tmpbuf); | |
421 | return ret; | |
422 | } else if (!is_v3header((size_t) ret, cap->magic_etc)) { | |
423 | kfree(tmpbuf); | |
424 | return -EINVAL; | |
425 | } | |
426 | ||
427 | nscap = (struct vfs_ns_cap_data *) tmpbuf; | |
428 | root = le32_to_cpu(nscap->rootid); | |
429 | kroot = make_kuid(fs_ns, root); | |
430 | ||
431 | /* If the root kuid maps to a valid uid in current ns, then return | |
432 | * this as a nscap. */ | |
433 | mappedroot = from_kuid(current_user_ns(), kroot); | |
434 | if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) { | |
435 | if (alloc) { | |
436 | *buffer = tmpbuf; | |
437 | nscap->rootid = cpu_to_le32(mappedroot); | |
438 | } else | |
439 | kfree(tmpbuf); | |
440 | return size; | |
441 | } | |
442 | ||
443 | if (!rootid_owns_currentns(kroot)) { | |
444 | kfree(tmpbuf); | |
445 | return -EOPNOTSUPP; | |
446 | } | |
447 | ||
448 | /* This comes from a parent namespace. Return as a v2 capability */ | |
449 | size = sizeof(struct vfs_cap_data); | |
450 | if (alloc) { | |
451 | *buffer = kmalloc(size, GFP_ATOMIC); | |
452 | if (*buffer) { | |
453 | struct vfs_cap_data *cap = *buffer; | |
454 | __le32 nsmagic, magic; | |
455 | magic = VFS_CAP_REVISION_2; | |
456 | nsmagic = le32_to_cpu(nscap->magic_etc); | |
457 | if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE) | |
458 | magic |= VFS_CAP_FLAGS_EFFECTIVE; | |
459 | memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32); | |
460 | cap->magic_etc = cpu_to_le32(magic); | |
461 | } | |
462 | } | |
463 | kfree(tmpbuf); | |
464 | return size; | |
465 | } | |
466 | ||
467 | static kuid_t rootid_from_xattr(const void *value, size_t size, | |
468 | struct user_namespace *task_ns) | |
469 | { | |
470 | const struct vfs_ns_cap_data *nscap = value; | |
471 | uid_t rootid = 0; | |
472 | ||
473 | if (size == XATTR_CAPS_SZ_3) | |
474 | rootid = le32_to_cpu(nscap->rootid); | |
475 | ||
476 | return make_kuid(task_ns, rootid); | |
477 | } | |
478 | ||
479 | static bool validheader(size_t size, __le32 magic) | |
480 | { | |
481 | return is_v2header(size, magic) || is_v3header(size, magic); | |
482 | } | |
483 | ||
484 | /* | |
485 | * User requested a write of security.capability. If needed, update the | |
486 | * xattr to change from v2 to v3, or to fixup the v3 rootid. | |
487 | * | |
488 | * If all is ok, we return the new size, on error return < 0. | |
489 | */ | |
490 | int cap_convert_nscap(struct dentry *dentry, void **ivalue, size_t size) | |
491 | { | |
492 | struct vfs_ns_cap_data *nscap; | |
493 | uid_t nsrootid; | |
494 | const struct vfs_cap_data *cap = *ivalue; | |
495 | __u32 magic, nsmagic; | |
496 | struct inode *inode = d_backing_inode(dentry); | |
497 | struct user_namespace *task_ns = current_user_ns(), | |
498 | *fs_ns = inode->i_sb->s_user_ns; | |
499 | kuid_t rootid; | |
500 | size_t newsize; | |
501 | ||
502 | if (!*ivalue) | |
503 | return -EINVAL; | |
504 | if (!validheader(size, cap->magic_etc)) | |
505 | return -EINVAL; | |
506 | if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP)) | |
507 | return -EPERM; | |
508 | if (size == XATTR_CAPS_SZ_2) | |
509 | if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP)) | |
510 | /* user is privileged, just write the v2 */ | |
511 | return size; | |
512 | ||
513 | rootid = rootid_from_xattr(*ivalue, size, task_ns); | |
514 | if (!uid_valid(rootid)) | |
515 | return -EINVAL; | |
516 | ||
517 | nsrootid = from_kuid(fs_ns, rootid); | |
518 | if (nsrootid == -1) | |
519 | return -EINVAL; | |
520 | ||
521 | newsize = sizeof(struct vfs_ns_cap_data); | |
522 | nscap = kmalloc(newsize, GFP_ATOMIC); | |
523 | if (!nscap) | |
524 | return -ENOMEM; | |
525 | nscap->rootid = cpu_to_le32(nsrootid); | |
526 | nsmagic = VFS_CAP_REVISION_3; | |
527 | magic = le32_to_cpu(cap->magic_etc); | |
528 | if (magic & VFS_CAP_FLAGS_EFFECTIVE) | |
529 | nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; | |
530 | nscap->magic_etc = cpu_to_le32(nsmagic); | |
531 | memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); | |
532 | ||
533 | kvfree(*ivalue); | |
534 | *ivalue = nscap; | |
535 | return newsize; | |
536 | } | |
537 | ||
1d045980 DH |
538 | /* |
539 | * Calculate the new process capability sets from the capability sets attached | |
540 | * to a file. | |
541 | */ | |
c0b00441 | 542 | static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, |
a6f76f23 | 543 | struct linux_binprm *bprm, |
4d49f671 ZL |
544 | bool *effective, |
545 | bool *has_cap) | |
b5376771 | 546 | { |
a6f76f23 | 547 | struct cred *new = bprm->cred; |
c0b00441 EP |
548 | unsigned i; |
549 | int ret = 0; | |
550 | ||
551 | if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) | |
a6f76f23 | 552 | *effective = true; |
c0b00441 | 553 | |
4d49f671 ZL |
554 | if (caps->magic_etc & VFS_CAP_REVISION_MASK) |
555 | *has_cap = true; | |
556 | ||
c0b00441 EP |
557 | CAP_FOR_EACH_U32(i) { |
558 | __u32 permitted = caps->permitted.cap[i]; | |
559 | __u32 inheritable = caps->inheritable.cap[i]; | |
560 | ||
561 | /* | |
562 | * pP' = (X & fP) | (pI & fI) | |
58319057 | 563 | * The addition of pA' is handled later. |
c0b00441 | 564 | */ |
a6f76f23 DH |
565 | new->cap_permitted.cap[i] = |
566 | (new->cap_bset.cap[i] & permitted) | | |
567 | (new->cap_inheritable.cap[i] & inheritable); | |
c0b00441 | 568 | |
a6f76f23 DH |
569 | if (permitted & ~new->cap_permitted.cap[i]) |
570 | /* insufficient to execute correctly */ | |
c0b00441 | 571 | ret = -EPERM; |
c0b00441 EP |
572 | } |
573 | ||
574 | /* | |
575 | * For legacy apps, with no internal support for recognizing they | |
576 | * do not have enough capabilities, we return an error if they are | |
577 | * missing some "forced" (aka file-permitted) capabilities. | |
578 | */ | |
a6f76f23 | 579 | return *effective ? ret : 0; |
c0b00441 EP |
580 | } |
581 | ||
1d045980 DH |
582 | /* |
583 | * Extract the on-exec-apply capability sets for an executable file. | |
584 | */ | |
c0b00441 EP |
585 | int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps) |
586 | { | |
c6f493d6 | 587 | struct inode *inode = d_backing_inode(dentry); |
b5376771 | 588 | __u32 magic_etc; |
e338d263 | 589 | unsigned tocopy, i; |
c0b00441 | 590 | int size; |
d7acd1fa SH |
591 | struct vfs_ns_cap_data data, *nscaps = &data; |
592 | struct vfs_cap_data *caps = (struct vfs_cap_data *) &data; | |
593 | kuid_t rootkuid; | |
594 | struct user_namespace *fs_ns = inode->i_sb->s_user_ns; | |
c0b00441 EP |
595 | |
596 | memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); | |
597 | ||
5d6c3191 | 598 | if (!inode) |
c0b00441 EP |
599 | return -ENODATA; |
600 | ||
5d6c3191 | 601 | size = __vfs_getxattr((struct dentry *)dentry, inode, |
d7acd1fa | 602 | XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ); |
a6f76f23 | 603 | if (size == -ENODATA || size == -EOPNOTSUPP) |
c0b00441 EP |
604 | /* no data, that's ok */ |
605 | return -ENODATA; | |
d7acd1fa | 606 | |
c0b00441 EP |
607 | if (size < 0) |
608 | return size; | |
b5376771 | 609 | |
e338d263 | 610 | if (size < sizeof(magic_etc)) |
b5376771 SH |
611 | return -EINVAL; |
612 | ||
d7acd1fa | 613 | cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc); |
b5376771 | 614 | |
d7acd1fa | 615 | rootkuid = make_kuid(fs_ns, 0); |
a6f76f23 | 616 | switch (magic_etc & VFS_CAP_REVISION_MASK) { |
e338d263 AM |
617 | case VFS_CAP_REVISION_1: |
618 | if (size != XATTR_CAPS_SZ_1) | |
619 | return -EINVAL; | |
620 | tocopy = VFS_CAP_U32_1; | |
621 | break; | |
622 | case VFS_CAP_REVISION_2: | |
623 | if (size != XATTR_CAPS_SZ_2) | |
624 | return -EINVAL; | |
625 | tocopy = VFS_CAP_U32_2; | |
626 | break; | |
d7acd1fa SH |
627 | case VFS_CAP_REVISION_3: |
628 | if (size != XATTR_CAPS_SZ_3) | |
629 | return -EINVAL; | |
630 | tocopy = VFS_CAP_U32_3; | |
631 | rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid)); | |
632 | break; | |
633 | ||
b5376771 SH |
634 | default: |
635 | return -EINVAL; | |
636 | } | |
d7acd1fa SH |
637 | /* Limit the caps to the mounter of the filesystem |
638 | * or the more limited uid specified in the xattr. | |
639 | */ | |
640 | if (!rootid_owns_currentns(rootkuid)) | |
641 | return -ENODATA; | |
e338d263 | 642 | |
5459c164 | 643 | CAP_FOR_EACH_U32(i) { |
c0b00441 EP |
644 | if (i >= tocopy) |
645 | break; | |
d7acd1fa SH |
646 | cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted); |
647 | cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable); | |
e338d263 | 648 | } |
a6f76f23 | 649 | |
7d8b6c63 EP |
650 | cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; |
651 | cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; | |
652 | ||
c0b00441 | 653 | return 0; |
b5376771 SH |
654 | } |
655 | ||
1d045980 DH |
656 | /* |
657 | * Attempt to get the on-exec apply capability sets for an executable file from | |
658 | * its xattrs and, if present, apply them to the proposed credentials being | |
659 | * constructed by execve(). | |
660 | */ | |
4d49f671 | 661 | static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_cap) |
b5376771 | 662 | { |
b5376771 | 663 | int rc = 0; |
c0b00441 | 664 | struct cpu_vfs_cap_data vcaps; |
b5376771 | 665 | |
3318a386 SH |
666 | bprm_clear_caps(bprm); |
667 | ||
1f29fae2 SH |
668 | if (!file_caps_enabled) |
669 | return 0; | |
670 | ||
0dc04886 | 671 | if (path_nosuid(&bprm->file->f_path)) |
b5376771 | 672 | return 0; |
380cf5ba AL |
673 | |
674 | /* | |
675 | * This check is redundant with mnt_may_suid() but is kept to make | |
676 | * explicit that capability bits are limited to s_user_ns and its | |
677 | * descendants. | |
678 | */ | |
d07b846f SF |
679 | if (!current_in_userns(bprm->file->f_path.mnt->mnt_sb->s_user_ns)) |
680 | return 0; | |
b5376771 | 681 | |
f4a4a8b1 | 682 | rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps); |
c0b00441 EP |
683 | if (rc < 0) { |
684 | if (rc == -EINVAL) | |
d7acd1fa SH |
685 | printk(KERN_NOTICE "Invalid argument reading file caps for %s\n", |
686 | bprm->filename); | |
c0b00441 EP |
687 | else if (rc == -ENODATA) |
688 | rc = 0; | |
b5376771 SH |
689 | goto out; |
690 | } | |
b5376771 | 691 | |
4d49f671 | 692 | rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_cap); |
a6f76f23 DH |
693 | if (rc == -EINVAL) |
694 | printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", | |
695 | __func__, rc, bprm->filename); | |
b5376771 SH |
696 | |
697 | out: | |
b5376771 SH |
698 | if (rc) |
699 | bprm_clear_caps(bprm); | |
700 | ||
701 | return rc; | |
702 | } | |
703 | ||
1d045980 DH |
704 | /** |
705 | * cap_bprm_set_creds - Set up the proposed credentials for execve(). | |
706 | * @bprm: The execution parameters, including the proposed creds | |
707 | * | |
708 | * Set up the proposed credentials for a new execution context being | |
709 | * constructed by execve(). The proposed creds in @bprm->cred is altered, | |
710 | * which won't take effect immediately. Returns 0 if successful, -ve on error. | |
a6f76f23 DH |
711 | */ |
712 | int cap_bprm_set_creds(struct linux_binprm *bprm) | |
1da177e4 | 713 | { |
a6f76f23 DH |
714 | const struct cred *old = current_cred(); |
715 | struct cred *new = bprm->cred; | |
58319057 | 716 | bool effective, has_cap = false, is_setid; |
b5376771 | 717 | int ret; |
18815a18 | 718 | kuid_t root_uid; |
1da177e4 | 719 | |
58319057 AL |
720 | if (WARN_ON(!cap_ambient_invariant_ok(old))) |
721 | return -EPERM; | |
722 | ||
a6f76f23 | 723 | effective = false; |
4d49f671 | 724 | ret = get_file_caps(bprm, &effective, &has_cap); |
a6f76f23 DH |
725 | if (ret < 0) |
726 | return ret; | |
1da177e4 | 727 | |
18815a18 EB |
728 | root_uid = make_kuid(new->user_ns, 0); |
729 | ||
5459c164 | 730 | if (!issecure(SECURE_NOROOT)) { |
b5f22a59 SH |
731 | /* |
732 | * If the legacy file capability is set, then don't set privs | |
733 | * for a setuid root binary run by a non-root user. Do set it | |
734 | * for a root user just to cause least surprise to an admin. | |
735 | */ | |
18815a18 | 736 | if (has_cap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, root_uid)) { |
b5f22a59 SH |
737 | warn_setuid_and_fcaps_mixed(bprm->filename); |
738 | goto skip; | |
739 | } | |
5459c164 AM |
740 | /* |
741 | * To support inheritance of root-permissions and suid-root | |
742 | * executables under compatibility mode, we override the | |
743 | * capability sets for the file. | |
744 | * | |
a6f76f23 | 745 | * If only the real uid is 0, we do not set the effective bit. |
5459c164 | 746 | */ |
18815a18 | 747 | if (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) { |
5459c164 | 748 | /* pP' = (cap_bset & ~0) | (pI & ~0) */ |
a6f76f23 DH |
749 | new->cap_permitted = cap_combine(old->cap_bset, |
750 | old->cap_inheritable); | |
1da177e4 | 751 | } |
18815a18 | 752 | if (uid_eq(new->euid, root_uid)) |
a6f76f23 | 753 | effective = true; |
1da177e4 | 754 | } |
b5f22a59 | 755 | skip: |
b5376771 | 756 | |
d52fc5dd EP |
757 | /* if we have fs caps, clear dangerous personality flags */ |
758 | if (!cap_issubset(new->cap_permitted, old->cap_permitted)) | |
759 | bprm->per_clear |= PER_CLEAR_ON_SETID; | |
760 | ||
761 | ||
a6f76f23 | 762 | /* Don't let someone trace a set[ug]id/setpcap binary with the revised |
259e5e6c AL |
763 | * credentials unless they have the appropriate permit. |
764 | * | |
765 | * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. | |
a6f76f23 | 766 | */ |
58319057 AL |
767 | is_setid = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, old->gid); |
768 | ||
769 | if ((is_setid || | |
a6f76f23 | 770 | !cap_issubset(new->cap_permitted, old->cap_permitted)) && |
9227dd2a | 771 | ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || |
20523132 | 772 | !ptracer_capable(current, new->user_ns))) { |
a6f76f23 | 773 | /* downgrade; they get no more than they had, and maybe less */ |
70169420 | 774 | if (!ns_capable(new->user_ns, CAP_SETUID) || |
259e5e6c | 775 | (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { |
a6f76f23 DH |
776 | new->euid = new->uid; |
777 | new->egid = new->gid; | |
1da177e4 | 778 | } |
b3a222e5 SH |
779 | new->cap_permitted = cap_intersect(new->cap_permitted, |
780 | old->cap_permitted); | |
1da177e4 LT |
781 | } |
782 | ||
a6f76f23 DH |
783 | new->suid = new->fsuid = new->euid; |
784 | new->sgid = new->fsgid = new->egid; | |
1da177e4 | 785 | |
58319057 AL |
786 | /* File caps or setid cancels ambient. */ |
787 | if (has_cap || is_setid) | |
788 | cap_clear(new->cap_ambient); | |
789 | ||
790 | /* | |
791 | * Now that we've computed pA', update pP' to give: | |
792 | * pP' = (X & fP) | (pI & fI) | pA' | |
793 | */ | |
794 | new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient); | |
795 | ||
796 | /* | |
797 | * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set, | |
798 | * this is the same as pE' = (fE ? pP' : 0) | pA'. | |
799 | */ | |
4bf2ea77 EP |
800 | if (effective) |
801 | new->cap_effective = new->cap_permitted; | |
802 | else | |
58319057 AL |
803 | new->cap_effective = new->cap_ambient; |
804 | ||
805 | if (WARN_ON(!cap_ambient_invariant_ok(new))) | |
806 | return -EPERM; | |
807 | ||
a6f76f23 | 808 | bprm->cap_effective = effective; |
1da177e4 | 809 | |
3fc689e9 EP |
810 | /* |
811 | * Audit candidate if current->cap_effective is set | |
812 | * | |
813 | * We do not bother to audit if 3 things are true: | |
814 | * 1) cap_effective has all caps | |
815 | * 2) we are root | |
816 | * 3) root is supposed to have all caps (SECURE_NOROOT) | |
817 | * Since this is just a normal root execing a process. | |
818 | * | |
819 | * Number 1 above might fail if you don't have a full bset, but I think | |
820 | * that is interesting information to audit. | |
821 | */ | |
58319057 | 822 | if (!cap_issubset(new->cap_effective, new->cap_ambient)) { |
d84f4f99 | 823 | if (!cap_issubset(CAP_FULL_SET, new->cap_effective) || |
18815a18 | 824 | !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) || |
a6f76f23 DH |
825 | issecure(SECURE_NOROOT)) { |
826 | ret = audit_log_bprm_fcaps(bprm, new, old); | |
827 | if (ret < 0) | |
828 | return ret; | |
829 | } | |
3fc689e9 | 830 | } |
1da177e4 | 831 | |
d84f4f99 | 832 | new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
58319057 AL |
833 | |
834 | if (WARN_ON(!cap_ambient_invariant_ok(new))) | |
835 | return -EPERM; | |
836 | ||
a6f76f23 | 837 | return 0; |
1da177e4 LT |
838 | } |
839 | ||
1d045980 DH |
840 | /** |
841 | * cap_bprm_secureexec - Determine whether a secure execution is required | |
842 | * @bprm: The execution parameters | |
843 | * | |
844 | * Determine whether a secure execution is required, return 1 if it is, and 0 | |
845 | * if it is not. | |
846 | * | |
847 | * The credentials have been committed by this point, and so are no longer | |
848 | * available through @bprm->cred. | |
a6f76f23 DH |
849 | */ |
850 | int cap_bprm_secureexec(struct linux_binprm *bprm) | |
1da177e4 | 851 | { |
c69e8d9c | 852 | const struct cred *cred = current_cred(); |
18815a18 | 853 | kuid_t root_uid = make_kuid(cred->user_ns, 0); |
b6dff3ec | 854 | |
18815a18 | 855 | if (!uid_eq(cred->uid, root_uid)) { |
b5376771 SH |
856 | if (bprm->cap_effective) |
857 | return 1; | |
58319057 | 858 | if (!cap_issubset(cred->cap_permitted, cred->cap_ambient)) |
b5376771 SH |
859 | return 1; |
860 | } | |
861 | ||
18815a18 EB |
862 | return (!uid_eq(cred->euid, cred->uid) || |
863 | !gid_eq(cred->egid, cred->gid)); | |
1da177e4 LT |
864 | } |
865 | ||
1d045980 DH |
866 | /** |
867 | * cap_inode_setxattr - Determine whether an xattr may be altered | |
868 | * @dentry: The inode/dentry being altered | |
869 | * @name: The name of the xattr to be changed | |
870 | * @value: The value that the xattr will be changed to | |
871 | * @size: The size of value | |
872 | * @flags: The replacement flag | |
873 | * | |
874 | * Determine whether an xattr may be altered or set on an inode, returning 0 if | |
875 | * permission is granted, -ve if denied. | |
876 | * | |
877 | * This is used to make sure security xattrs don't get updated or set by those | |
878 | * who aren't privileged to do so. | |
879 | */ | |
8f0cfa52 DH |
880 | int cap_inode_setxattr(struct dentry *dentry, const char *name, |
881 | const void *value, size_t size, int flags) | |
1da177e4 | 882 | { |
d7acd1fa SH |
883 | /* Ignore non-security xattrs */ |
884 | if (strncmp(name, XATTR_SECURITY_PREFIX, | |
885 | sizeof(XATTR_SECURITY_PREFIX) - 1) != 0) | |
886 | return 0; | |
7a66bd87 | 887 | |
d7acd1fa SH |
888 | /* |
889 | * For XATTR_NAME_CAPS the check will be done in | |
890 | * cap_convert_nscap(), called by setxattr() | |
891 | */ | |
892 | if (strcmp(name, XATTR_NAME_CAPS) == 0) | |
b5376771 | 893 | return 0; |
1d045980 | 894 | |
d7acd1fa | 895 | if (!ns_capable(dentry->d_sb->s_user_ns, CAP_SYS_ADMIN)) |
1da177e4 LT |
896 | return -EPERM; |
897 | return 0; | |
898 | } | |
899 | ||
1d045980 DH |
900 | /** |
901 | * cap_inode_removexattr - Determine whether an xattr may be removed | |
902 | * @dentry: The inode/dentry being altered | |
903 | * @name: The name of the xattr to be changed | |
904 | * | |
905 | * Determine whether an xattr may be removed from 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 removed by those who | |
909 | * aren't privileged to remove them. | |
910 | */ | |
8f0cfa52 | 911 | int cap_inode_removexattr(struct dentry *dentry, const char *name) |
1da177e4 | 912 | { |
d7acd1fa SH |
913 | /* Ignore non-security xattrs */ |
914 | if (strncmp(name, XATTR_SECURITY_PREFIX, | |
915 | sizeof(XATTR_SECURITY_PREFIX) - 1) != 0) | |
916 | return 0; | |
7a66bd87 | 917 | |
d7acd1fa SH |
918 | if (strcmp(name, XATTR_NAME_CAPS) == 0) { |
919 | /* security.capability gets namespaced */ | |
920 | struct inode *inode = d_backing_inode(dentry); | |
921 | if (!inode) | |
922 | return -EINVAL; | |
923 | if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP)) | |
b5376771 SH |
924 | return -EPERM; |
925 | return 0; | |
1d045980 DH |
926 | } |
927 | ||
d7acd1fa | 928 | if (!ns_capable(dentry->d_sb->s_user_ns, CAP_SYS_ADMIN)) |
1da177e4 LT |
929 | return -EPERM; |
930 | return 0; | |
931 | } | |
932 | ||
a6f76f23 | 933 | /* |
1da177e4 LT |
934 | * cap_emulate_setxuid() fixes the effective / permitted capabilities of |
935 | * a process after a call to setuid, setreuid, or setresuid. | |
936 | * | |
937 | * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of | |
938 | * {r,e,s}uid != 0, the permitted and effective capabilities are | |
939 | * cleared. | |
940 | * | |
941 | * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective | |
942 | * capabilities of the process are cleared. | |
943 | * | |
944 | * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective | |
945 | * capabilities are set to the permitted capabilities. | |
946 | * | |
a6f76f23 | 947 | * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should |
1da177e4 LT |
948 | * never happen. |
949 | * | |
a6f76f23 | 950 | * -astor |
1da177e4 LT |
951 | * |
952 | * cevans - New behaviour, Oct '99 | |
953 | * A process may, via prctl(), elect to keep its capabilities when it | |
954 | * calls setuid() and switches away from uid==0. Both permitted and | |
955 | * effective sets will be retained. | |
956 | * Without this change, it was impossible for a daemon to drop only some | |
957 | * of its privilege. The call to setuid(!=0) would drop all privileges! | |
958 | * Keeping uid 0 is not an option because uid 0 owns too many vital | |
959 | * files.. | |
960 | * Thanks to Olaf Kirch and Peter Benie for spotting this. | |
961 | */ | |
d84f4f99 | 962 | static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) |
1da177e4 | 963 | { |
18815a18 EB |
964 | kuid_t root_uid = make_kuid(old->user_ns, 0); |
965 | ||
966 | if ((uid_eq(old->uid, root_uid) || | |
967 | uid_eq(old->euid, root_uid) || | |
968 | uid_eq(old->suid, root_uid)) && | |
969 | (!uid_eq(new->uid, root_uid) && | |
970 | !uid_eq(new->euid, root_uid) && | |
58319057 AL |
971 | !uid_eq(new->suid, root_uid))) { |
972 | if (!issecure(SECURE_KEEP_CAPS)) { | |
973 | cap_clear(new->cap_permitted); | |
974 | cap_clear(new->cap_effective); | |
975 | } | |
976 | ||
977 | /* | |
978 | * Pre-ambient programs expect setresuid to nonroot followed | |
979 | * by exec to drop capabilities. We should make sure that | |
980 | * this remains the case. | |
981 | */ | |
982 | cap_clear(new->cap_ambient); | |
1da177e4 | 983 | } |
18815a18 | 984 | if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid)) |
d84f4f99 | 985 | cap_clear(new->cap_effective); |
18815a18 | 986 | if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid)) |
d84f4f99 | 987 | new->cap_effective = new->cap_permitted; |
1da177e4 LT |
988 | } |
989 | ||
1d045980 DH |
990 | /** |
991 | * cap_task_fix_setuid - Fix up the results of setuid() call | |
992 | * @new: The proposed credentials | |
993 | * @old: The current task's current credentials | |
994 | * @flags: Indications of what has changed | |
995 | * | |
996 | * Fix up the results of setuid() call before the credential changes are | |
997 | * actually applied, returning 0 to grant the changes, -ve to deny them. | |
998 | */ | |
d84f4f99 | 999 | int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) |
1da177e4 LT |
1000 | { |
1001 | switch (flags) { | |
1002 | case LSM_SETID_RE: | |
1003 | case LSM_SETID_ID: | |
1004 | case LSM_SETID_RES: | |
1d045980 DH |
1005 | /* juggle the capabilities to follow [RES]UID changes unless |
1006 | * otherwise suppressed */ | |
d84f4f99 DH |
1007 | if (!issecure(SECURE_NO_SETUID_FIXUP)) |
1008 | cap_emulate_setxuid(new, old); | |
1da177e4 | 1009 | break; |
1da177e4 | 1010 | |
1d045980 DH |
1011 | case LSM_SETID_FS: |
1012 | /* juggle the capabilties to follow FSUID changes, unless | |
1013 | * otherwise suppressed | |
1014 | * | |
d84f4f99 DH |
1015 | * FIXME - is fsuser used for all CAP_FS_MASK capabilities? |
1016 | * if not, we might be a bit too harsh here. | |
1017 | */ | |
1018 | if (!issecure(SECURE_NO_SETUID_FIXUP)) { | |
18815a18 EB |
1019 | kuid_t root_uid = make_kuid(old->user_ns, 0); |
1020 | if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid)) | |
d84f4f99 DH |
1021 | new->cap_effective = |
1022 | cap_drop_fs_set(new->cap_effective); | |
1d045980 | 1023 | |
18815a18 | 1024 | if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid)) |
d84f4f99 DH |
1025 | new->cap_effective = |
1026 | cap_raise_fs_set(new->cap_effective, | |
1027 | new->cap_permitted); | |
1da177e4 | 1028 | } |
d84f4f99 | 1029 | break; |
1d045980 | 1030 | |
1da177e4 LT |
1031 | default: |
1032 | return -EINVAL; | |
1033 | } | |
1034 | ||
1035 | return 0; | |
1036 | } | |
1037 | ||
b5376771 SH |
1038 | /* |
1039 | * Rationale: code calling task_setscheduler, task_setioprio, and | |
1040 | * task_setnice, assumes that | |
1041 | * . if capable(cap_sys_nice), then those actions should be allowed | |
1042 | * . if not capable(cap_sys_nice), but acting on your own processes, | |
1043 | * then those actions should be allowed | |
1044 | * This is insufficient now since you can call code without suid, but | |
1045 | * yet with increased caps. | |
1046 | * So we check for increased caps on the target process. | |
1047 | */ | |
de45e806 | 1048 | static int cap_safe_nice(struct task_struct *p) |
b5376771 | 1049 | { |
f54fb863 | 1050 | int is_subset, ret = 0; |
c69e8d9c DH |
1051 | |
1052 | rcu_read_lock(); | |
1053 | is_subset = cap_issubset(__task_cred(p)->cap_permitted, | |
1054 | current_cred()->cap_permitted); | |
f54fb863 SH |
1055 | if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) |
1056 | ret = -EPERM; | |
c69e8d9c DH |
1057 | rcu_read_unlock(); |
1058 | ||
f54fb863 | 1059 | return ret; |
b5376771 SH |
1060 | } |
1061 | ||
1d045980 DH |
1062 | /** |
1063 | * cap_task_setscheduler - Detemine if scheduler policy change is permitted | |
1064 | * @p: The task to affect | |
1d045980 DH |
1065 | * |
1066 | * Detemine if the requested scheduler policy change is permitted for the | |
1067 | * specified task, returning 0 if permission is granted, -ve if denied. | |
1068 | */ | |
b0ae1981 | 1069 | int cap_task_setscheduler(struct task_struct *p) |
b5376771 SH |
1070 | { |
1071 | return cap_safe_nice(p); | |
1072 | } | |
1073 | ||
1d045980 DH |
1074 | /** |
1075 | * cap_task_ioprio - Detemine if I/O priority change is permitted | |
1076 | * @p: The task to affect | |
1077 | * @ioprio: The I/O priority to set | |
1078 | * | |
1079 | * Detemine if the requested I/O priority change is permitted for the specified | |
1080 | * task, returning 0 if permission is granted, -ve if denied. | |
1081 | */ | |
1082 | int cap_task_setioprio(struct task_struct *p, int ioprio) | |
b5376771 SH |
1083 | { |
1084 | return cap_safe_nice(p); | |
1085 | } | |
1086 | ||
1d045980 DH |
1087 | /** |
1088 | * cap_task_ioprio - Detemine if task priority change is permitted | |
1089 | * @p: The task to affect | |
1090 | * @nice: The nice value to set | |
1091 | * | |
1092 | * Detemine if the requested task priority change is permitted for the | |
1093 | * specified task, returning 0 if permission is granted, -ve if denied. | |
1094 | */ | |
1095 | int cap_task_setnice(struct task_struct *p, int nice) | |
b5376771 SH |
1096 | { |
1097 | return cap_safe_nice(p); | |
1098 | } | |
1099 | ||
3b7391de | 1100 | /* |
1d045980 DH |
1101 | * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from |
1102 | * the current task's bounding set. Returns 0 on success, -ve on error. | |
3b7391de | 1103 | */ |
6d6f3328 | 1104 | static int cap_prctl_drop(unsigned long cap) |
3b7391de | 1105 | { |
6d6f3328 TH |
1106 | struct cred *new; |
1107 | ||
160da84d | 1108 | if (!ns_capable(current_user_ns(), CAP_SETPCAP)) |
3b7391de SH |
1109 | return -EPERM; |
1110 | if (!cap_valid(cap)) | |
1111 | return -EINVAL; | |
d84f4f99 | 1112 | |
6d6f3328 TH |
1113 | new = prepare_creds(); |
1114 | if (!new) | |
1115 | return -ENOMEM; | |
d84f4f99 | 1116 | cap_lower(new->cap_bset, cap); |
6d6f3328 | 1117 | return commit_creds(new); |
3b7391de | 1118 | } |
3898b1b4 | 1119 | |
1d045980 DH |
1120 | /** |
1121 | * cap_task_prctl - Implement process control functions for this security module | |
1122 | * @option: The process control function requested | |
1123 | * @arg2, @arg3, @arg4, @arg5: The argument data for this function | |
1124 | * | |
1125 | * Allow process control functions (sys_prctl()) to alter capabilities; may | |
1126 | * also deny access to other functions not otherwise implemented here. | |
1127 | * | |
1128 | * Returns 0 or +ve on success, -ENOSYS if this function is not implemented | |
1129 | * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM | |
1130 | * modules will consider performing the function. | |
1131 | */ | |
3898b1b4 | 1132 | int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, |
d84f4f99 | 1133 | unsigned long arg4, unsigned long arg5) |
3898b1b4 | 1134 | { |
6d6f3328 | 1135 | const struct cred *old = current_cred(); |
d84f4f99 | 1136 | struct cred *new; |
d84f4f99 | 1137 | |
3898b1b4 AM |
1138 | switch (option) { |
1139 | case PR_CAPBSET_READ: | |
1140 | if (!cap_valid(arg2)) | |
6d6f3328 TH |
1141 | return -EINVAL; |
1142 | return !!cap_raised(old->cap_bset, arg2); | |
d84f4f99 | 1143 | |
3898b1b4 | 1144 | case PR_CAPBSET_DROP: |
6d6f3328 | 1145 | return cap_prctl_drop(arg2); |
3898b1b4 AM |
1146 | |
1147 | /* | |
1148 | * The next four prctl's remain to assist with transitioning a | |
1149 | * system from legacy UID=0 based privilege (when filesystem | |
1150 | * capabilities are not in use) to a system using filesystem | |
1151 | * capabilities only - as the POSIX.1e draft intended. | |
1152 | * | |
1153 | * Note: | |
1154 | * | |
1155 | * PR_SET_SECUREBITS = | |
1156 | * issecure_mask(SECURE_KEEP_CAPS_LOCKED) | |
1157 | * | issecure_mask(SECURE_NOROOT) | |
1158 | * | issecure_mask(SECURE_NOROOT_LOCKED) | |
1159 | * | issecure_mask(SECURE_NO_SETUID_FIXUP) | |
1160 | * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED) | |
1161 | * | |
1162 | * will ensure that the current process and all of its | |
1163 | * children will be locked into a pure | |
1164 | * capability-based-privilege environment. | |
1165 | */ | |
1166 | case PR_SET_SECUREBITS: | |
6d6f3328 TH |
1167 | if ((((old->securebits & SECURE_ALL_LOCKS) >> 1) |
1168 | & (old->securebits ^ arg2)) /*[1]*/ | |
1169 | || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ | |
d84f4f99 | 1170 | || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ |
6a9de491 | 1171 | || (cap_capable(current_cred(), |
c4a4d603 | 1172 | current_cred()->user_ns, CAP_SETPCAP, |
3699c53c | 1173 | SECURITY_CAP_AUDIT) != 0) /*[4]*/ |
3898b1b4 AM |
1174 | /* |
1175 | * [1] no changing of bits that are locked | |
1176 | * [2] no unlocking of locks | |
1177 | * [3] no setting of unsupported bits | |
1178 | * [4] doing anything requires privilege (go read about | |
1179 | * the "sendmail capabilities bug") | |
1180 | */ | |
d84f4f99 DH |
1181 | ) |
1182 | /* cannot change a locked bit */ | |
6d6f3328 TH |
1183 | return -EPERM; |
1184 | ||
1185 | new = prepare_creds(); | |
1186 | if (!new) | |
1187 | return -ENOMEM; | |
d84f4f99 | 1188 | new->securebits = arg2; |
6d6f3328 | 1189 | return commit_creds(new); |
d84f4f99 | 1190 | |
3898b1b4 | 1191 | case PR_GET_SECUREBITS: |
6d6f3328 | 1192 | return old->securebits; |
3898b1b4 | 1193 | |
3898b1b4 | 1194 | case PR_GET_KEEPCAPS: |
6d6f3328 | 1195 | return !!issecure(SECURE_KEEP_CAPS); |
d84f4f99 | 1196 | |
3898b1b4 AM |
1197 | case PR_SET_KEEPCAPS: |
1198 | if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */ | |
6d6f3328 | 1199 | return -EINVAL; |
d84f4f99 | 1200 | if (issecure(SECURE_KEEP_CAPS_LOCKED)) |
6d6f3328 TH |
1201 | return -EPERM; |
1202 | ||
1203 | new = prepare_creds(); | |
1204 | if (!new) | |
1205 | return -ENOMEM; | |
d84f4f99 DH |
1206 | if (arg2) |
1207 | new->securebits |= issecure_mask(SECURE_KEEP_CAPS); | |
3898b1b4 | 1208 | else |
d84f4f99 | 1209 | new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
6d6f3328 | 1210 | return commit_creds(new); |
3898b1b4 | 1211 | |
58319057 AL |
1212 | case PR_CAP_AMBIENT: |
1213 | if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) { | |
1214 | if (arg3 | arg4 | arg5) | |
1215 | return -EINVAL; | |
1216 | ||
1217 | new = prepare_creds(); | |
1218 | if (!new) | |
1219 | return -ENOMEM; | |
1220 | cap_clear(new->cap_ambient); | |
1221 | return commit_creds(new); | |
1222 | } | |
1223 | ||
1224 | if (((!cap_valid(arg3)) | arg4 | arg5)) | |
1225 | return -EINVAL; | |
1226 | ||
1227 | if (arg2 == PR_CAP_AMBIENT_IS_SET) { | |
1228 | return !!cap_raised(current_cred()->cap_ambient, arg3); | |
1229 | } else if (arg2 != PR_CAP_AMBIENT_RAISE && | |
1230 | arg2 != PR_CAP_AMBIENT_LOWER) { | |
1231 | return -EINVAL; | |
1232 | } else { | |
1233 | if (arg2 == PR_CAP_AMBIENT_RAISE && | |
1234 | (!cap_raised(current_cred()->cap_permitted, arg3) || | |
1235 | !cap_raised(current_cred()->cap_inheritable, | |
746bf6d6 AL |
1236 | arg3) || |
1237 | issecure(SECURE_NO_CAP_AMBIENT_RAISE))) | |
58319057 AL |
1238 | return -EPERM; |
1239 | ||
1240 | new = prepare_creds(); | |
1241 | if (!new) | |
1242 | return -ENOMEM; | |
1243 | if (arg2 == PR_CAP_AMBIENT_RAISE) | |
1244 | cap_raise(new->cap_ambient, arg3); | |
1245 | else | |
1246 | cap_lower(new->cap_ambient, arg3); | |
1247 | return commit_creds(new); | |
1248 | } | |
1249 | ||
3898b1b4 AM |
1250 | default: |
1251 | /* No functionality available - continue with default */ | |
6d6f3328 | 1252 | return -ENOSYS; |
3898b1b4 | 1253 | } |
1da177e4 LT |
1254 | } |
1255 | ||
1d045980 DH |
1256 | /** |
1257 | * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted | |
1258 | * @mm: The VM space in which the new mapping is to be made | |
1259 | * @pages: The size of the mapping | |
1260 | * | |
1261 | * Determine whether the allocation of a new virtual mapping by the current | |
b1d9e6b0 | 1262 | * task is permitted, returning 1 if permission is granted, 0 if not. |
1d045980 | 1263 | */ |
34b4e4aa | 1264 | int cap_vm_enough_memory(struct mm_struct *mm, long pages) |
1da177e4 LT |
1265 | { |
1266 | int cap_sys_admin = 0; | |
1267 | ||
6a9de491 | 1268 | if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN, |
3699c53c | 1269 | SECURITY_CAP_NOAUDIT) == 0) |
1da177e4 | 1270 | cap_sys_admin = 1; |
b1d9e6b0 | 1271 | return cap_sys_admin; |
1da177e4 | 1272 | } |
7c73875e EP |
1273 | |
1274 | /* | |
d007794a | 1275 | * cap_mmap_addr - check if able to map given addr |
7c73875e | 1276 | * @addr: address attempting to be mapped |
7c73875e | 1277 | * |
6f262d8e | 1278 | * If the process is attempting to map memory below dac_mmap_min_addr they need |
7c73875e EP |
1279 | * CAP_SYS_RAWIO. The other parameters to this function are unused by the |
1280 | * capability security module. Returns 0 if this mapping should be allowed | |
1281 | * -EPERM if not. | |
1282 | */ | |
d007794a | 1283 | int cap_mmap_addr(unsigned long addr) |
7c73875e EP |
1284 | { |
1285 | int ret = 0; | |
1286 | ||
a2551df7 | 1287 | if (addr < dac_mmap_min_addr) { |
6a9de491 | 1288 | ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO, |
7c73875e EP |
1289 | SECURITY_CAP_AUDIT); |
1290 | /* set PF_SUPERPRIV if it turns out we allow the low mmap */ | |
1291 | if (ret == 0) | |
1292 | current->flags |= PF_SUPERPRIV; | |
1293 | } | |
1294 | return ret; | |
1295 | } | |
b6450630 | 1296 | EXPORT_SYMBOL_GPL(cap_mmap_addr); |
d007794a | 1297 | |
e5467859 AV |
1298 | int cap_mmap_file(struct file *file, unsigned long reqprot, |
1299 | unsigned long prot, unsigned long flags) | |
d007794a | 1300 | { |
e5467859 | 1301 | return 0; |
d007794a | 1302 | } |
b6450630 | 1303 | EXPORT_SYMBOL_GPL(cap_mmap_file); |
b1d9e6b0 CS |
1304 | |
1305 | #ifdef CONFIG_SECURITY | |
1306 | ||
ca97d939 | 1307 | struct security_hook_list capability_hooks[] __lsm_ro_after_init = { |
b1d9e6b0 CS |
1308 | LSM_HOOK_INIT(capable, cap_capable), |
1309 | LSM_HOOK_INIT(settime, cap_settime), | |
1310 | LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check), | |
1311 | LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme), | |
1312 | LSM_HOOK_INIT(capget, cap_capget), | |
1313 | LSM_HOOK_INIT(capset, cap_capset), | |
1314 | LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds), | |
1315 | LSM_HOOK_INIT(bprm_secureexec, cap_bprm_secureexec), | |
1316 | LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv), | |
1317 | LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv), | |
d7acd1fa | 1318 | LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity), |
b1d9e6b0 CS |
1319 | LSM_HOOK_INIT(mmap_addr, cap_mmap_addr), |
1320 | LSM_HOOK_INIT(mmap_file, cap_mmap_file), | |
1321 | LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid), | |
1322 | LSM_HOOK_INIT(task_prctl, cap_task_prctl), | |
1323 | LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler), | |
1324 | LSM_HOOK_INIT(task_setioprio, cap_task_setioprio), | |
1325 | LSM_HOOK_INIT(task_setnice, cap_task_setnice), | |
1326 | LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory), | |
1327 | }; | |
1328 | ||
1329 | void __init capability_add_hooks(void) | |
1330 | { | |
d69dece5 CS |
1331 | security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), |
1332 | "capability"); | |
b1d9e6b0 CS |
1333 | } |
1334 | ||
1335 | #endif /* CONFIG_SECURITY */ |