Commit | Line | Data |
---|---|---|
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> | |
15 | #include <linux/security.h> | |
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 | ||
1da177e4 LT |
56 | int cap_netlink_send(struct sock *sk, struct sk_buff *skb) |
57 | { | |
1da177e4 LT |
58 | return 0; |
59 | } | |
60 | ||
1d045980 DH |
61 | /** |
62 | * cap_capable - Determine whether a task has a particular effective capability | |
3699c53c | 63 | * @cred: The credentials to use |
3486740a | 64 | * @ns: The user namespace in which we need the capability |
1d045980 DH |
65 | * @cap: The capability to check for |
66 | * @audit: Whether to write an audit message or not | |
67 | * | |
68 | * Determine whether the nominated task has the specified capability amongst | |
69 | * its effective set, returning 0 if it does, -ve if it does not. | |
70 | * | |
3699c53c DH |
71 | * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable() |
72 | * and has_capability() functions. That is, it has the reverse semantics: | |
73 | * cap_has_capability() returns 0 when a task has a capability, but the | |
74 | * kernel's capable() and has_capability() returns 1 for this case. | |
a6dbb1ef | 75 | */ |
6a9de491 EP |
76 | int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, |
77 | int cap, int audit) | |
1da177e4 | 78 | { |
3486740a SH |
79 | for (;;) { |
80 | /* The creator of the user namespace has all caps. */ | |
81 | if (targ_ns != &init_user_ns && targ_ns->creator == cred->user) | |
82 | return 0; | |
83 | ||
84 | /* Do we have the necessary capabilities? */ | |
85 | if (targ_ns == cred->user->user_ns) | |
86 | return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; | |
87 | ||
88 | /* Have we tried all of the parent namespaces? */ | |
89 | if (targ_ns == &init_user_ns) | |
90 | return -EPERM; | |
91 | ||
92 | /* | |
93 | *If you have a capability in a parent user ns, then you have | |
94 | * it over all children user namespaces as well. | |
95 | */ | |
96 | targ_ns = targ_ns->creator->user_ns; | |
97 | } | |
98 | ||
99 | /* We never get here */ | |
1da177e4 LT |
100 | } |
101 | ||
1d045980 DH |
102 | /** |
103 | * cap_settime - Determine whether the current process may set the system clock | |
104 | * @ts: The time to set | |
105 | * @tz: The timezone to set | |
106 | * | |
107 | * Determine whether the current process may set the system clock and timezone | |
108 | * information, returning 0 if permission granted, -ve if denied. | |
109 | */ | |
1e6d7679 | 110 | int cap_settime(const struct timespec *ts, const struct timezone *tz) |
1da177e4 LT |
111 | { |
112 | if (!capable(CAP_SYS_TIME)) | |
113 | return -EPERM; | |
114 | return 0; | |
115 | } | |
116 | ||
1d045980 | 117 | /** |
9e48858f | 118 | * cap_ptrace_access_check - Determine whether the current process may access |
1d045980 DH |
119 | * another |
120 | * @child: The process to be accessed | |
121 | * @mode: The mode of attachment. | |
122 | * | |
8409cca7 SH |
123 | * If we are in the same or an ancestor user_ns and have all the target |
124 | * task's capabilities, then ptrace access is allowed. | |
125 | * If we have the ptrace capability to the target user_ns, then ptrace | |
126 | * access is allowed. | |
127 | * Else denied. | |
128 | * | |
1d045980 DH |
129 | * Determine whether a process may access another, returning 0 if permission |
130 | * granted, -ve if denied. | |
131 | */ | |
9e48858f | 132 | int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) |
1da177e4 | 133 | { |
c69e8d9c | 134 | int ret = 0; |
8409cca7 | 135 | const struct cred *cred, *child_cred; |
c69e8d9c DH |
136 | |
137 | rcu_read_lock(); | |
8409cca7 SH |
138 | cred = current_cred(); |
139 | child_cred = __task_cred(child); | |
140 | if (cred->user->user_ns == child_cred->user->user_ns && | |
141 | cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) | |
142 | goto out; | |
143 | if (ns_capable(child_cred->user->user_ns, CAP_SYS_PTRACE)) | |
144 | goto out; | |
145 | ret = -EPERM; | |
146 | out: | |
c69e8d9c DH |
147 | rcu_read_unlock(); |
148 | return ret; | |
5cd9c58f DH |
149 | } |
150 | ||
1d045980 DH |
151 | /** |
152 | * cap_ptrace_traceme - Determine whether another process may trace the current | |
153 | * @parent: The task proposed to be the tracer | |
154 | * | |
8409cca7 SH |
155 | * If parent is in the same or an ancestor user_ns and has all current's |
156 | * capabilities, then ptrace access is allowed. | |
157 | * If parent has the ptrace capability to current's user_ns, then ptrace | |
158 | * access is allowed. | |
159 | * Else denied. | |
160 | * | |
1d045980 DH |
161 | * Determine whether the nominated task is permitted to trace the current |
162 | * process, returning 0 if permission is granted, -ve if denied. | |
163 | */ | |
5cd9c58f DH |
164 | int cap_ptrace_traceme(struct task_struct *parent) |
165 | { | |
c69e8d9c | 166 | int ret = 0; |
8409cca7 | 167 | const struct cred *cred, *child_cred; |
c69e8d9c DH |
168 | |
169 | rcu_read_lock(); | |
8409cca7 SH |
170 | cred = __task_cred(parent); |
171 | child_cred = current_cred(); | |
172 | if (cred->user->user_ns == child_cred->user->user_ns && | |
173 | cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) | |
174 | goto out; | |
175 | if (has_ns_capability(parent, child_cred->user->user_ns, CAP_SYS_PTRACE)) | |
176 | goto out; | |
177 | ret = -EPERM; | |
178 | out: | |
c69e8d9c DH |
179 | rcu_read_unlock(); |
180 | return ret; | |
1da177e4 LT |
181 | } |
182 | ||
1d045980 DH |
183 | /** |
184 | * cap_capget - Retrieve a task's capability sets | |
185 | * @target: The task from which to retrieve the capability sets | |
186 | * @effective: The place to record the effective set | |
187 | * @inheritable: The place to record the inheritable set | |
188 | * @permitted: The place to record the permitted set | |
189 | * | |
190 | * This function retrieves the capabilities of the nominated task and returns | |
191 | * them to the caller. | |
192 | */ | |
193 | int cap_capget(struct task_struct *target, kernel_cap_t *effective, | |
194 | kernel_cap_t *inheritable, kernel_cap_t *permitted) | |
1da177e4 | 195 | { |
c69e8d9c | 196 | const struct cred *cred; |
b6dff3ec | 197 | |
1da177e4 | 198 | /* Derived from kernel/capability.c:sys_capget. */ |
c69e8d9c DH |
199 | rcu_read_lock(); |
200 | cred = __task_cred(target); | |
b6dff3ec DH |
201 | *effective = cred->cap_effective; |
202 | *inheritable = cred->cap_inheritable; | |
203 | *permitted = cred->cap_permitted; | |
c69e8d9c | 204 | rcu_read_unlock(); |
1da177e4 LT |
205 | return 0; |
206 | } | |
207 | ||
1d045980 DH |
208 | /* |
209 | * Determine whether the inheritable capabilities are limited to the old | |
210 | * permitted set. Returns 1 if they are limited, 0 if they are not. | |
211 | */ | |
72c2d582 AM |
212 | static inline int cap_inh_is_capped(void) |
213 | { | |
72c2d582 | 214 | |
1d045980 DH |
215 | /* they are so limited unless the current task has the CAP_SETPCAP |
216 | * capability | |
217 | */ | |
6a9de491 EP |
218 | if (cap_capable(current_cred(), current_cred()->user->user_ns, |
219 | CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0) | |
1d045980 | 220 | return 0; |
1d045980 | 221 | return 1; |
1209726c | 222 | } |
72c2d582 | 223 | |
1d045980 DH |
224 | /** |
225 | * cap_capset - Validate and apply proposed changes to current's capabilities | |
226 | * @new: The proposed new credentials; alterations should be made here | |
227 | * @old: The current task's current credentials | |
228 | * @effective: A pointer to the proposed new effective capabilities set | |
229 | * @inheritable: A pointer to the proposed new inheritable capabilities set | |
230 | * @permitted: A pointer to the proposed new permitted capabilities set | |
231 | * | |
232 | * This function validates and applies a proposed mass change to the current | |
233 | * process's capability sets. The changes are made to the proposed new | |
234 | * credentials, and assuming no error, will be committed by the caller of LSM. | |
235 | */ | |
d84f4f99 DH |
236 | int cap_capset(struct cred *new, |
237 | const struct cred *old, | |
238 | const kernel_cap_t *effective, | |
239 | const kernel_cap_t *inheritable, | |
240 | const kernel_cap_t *permitted) | |
1da177e4 | 241 | { |
d84f4f99 DH |
242 | if (cap_inh_is_capped() && |
243 | !cap_issubset(*inheritable, | |
244 | cap_combine(old->cap_inheritable, | |
245 | old->cap_permitted))) | |
72c2d582 | 246 | /* incapable of using this inheritable set */ |
1da177e4 | 247 | return -EPERM; |
d84f4f99 | 248 | |
3b7391de | 249 | if (!cap_issubset(*inheritable, |
d84f4f99 DH |
250 | cap_combine(old->cap_inheritable, |
251 | old->cap_bset))) | |
3b7391de SH |
252 | /* no new pI capabilities outside bounding set */ |
253 | return -EPERM; | |
1da177e4 LT |
254 | |
255 | /* verify restrictions on target's new Permitted set */ | |
d84f4f99 | 256 | if (!cap_issubset(*permitted, old->cap_permitted)) |
1da177e4 | 257 | return -EPERM; |
1da177e4 LT |
258 | |
259 | /* verify the _new_Effective_ is a subset of the _new_Permitted_ */ | |
d84f4f99 | 260 | if (!cap_issubset(*effective, *permitted)) |
1da177e4 | 261 | return -EPERM; |
1da177e4 | 262 | |
d84f4f99 DH |
263 | new->cap_effective = *effective; |
264 | new->cap_inheritable = *inheritable; | |
265 | new->cap_permitted = *permitted; | |
1da177e4 LT |
266 | return 0; |
267 | } | |
268 | ||
1d045980 DH |
269 | /* |
270 | * Clear proposed capability sets for execve(). | |
271 | */ | |
b5376771 SH |
272 | static inline void bprm_clear_caps(struct linux_binprm *bprm) |
273 | { | |
a6f76f23 | 274 | cap_clear(bprm->cred->cap_permitted); |
b5376771 SH |
275 | bprm->cap_effective = false; |
276 | } | |
277 | ||
1d045980 DH |
278 | /** |
279 | * cap_inode_need_killpriv - Determine if inode change affects privileges | |
280 | * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV | |
281 | * | |
282 | * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV | |
283 | * affects the security markings on that inode, and if it is, should | |
284 | * inode_killpriv() be invoked or the change rejected? | |
285 | * | |
286 | * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and | |
287 | * -ve to deny the change. | |
288 | */ | |
b5376771 SH |
289 | int cap_inode_need_killpriv(struct dentry *dentry) |
290 | { | |
291 | struct inode *inode = dentry->d_inode; | |
292 | int error; | |
293 | ||
acfa4380 | 294 | if (!inode->i_op->getxattr) |
b5376771 SH |
295 | return 0; |
296 | ||
297 | error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0); | |
298 | if (error <= 0) | |
299 | return 0; | |
300 | return 1; | |
301 | } | |
302 | ||
1d045980 DH |
303 | /** |
304 | * cap_inode_killpriv - Erase the security markings on an inode | |
305 | * @dentry: The inode/dentry to alter | |
306 | * | |
307 | * Erase the privilege-enhancing security markings on an inode. | |
308 | * | |
309 | * Returns 0 if successful, -ve on error. | |
310 | */ | |
b5376771 SH |
311 | int cap_inode_killpriv(struct dentry *dentry) |
312 | { | |
313 | struct inode *inode = dentry->d_inode; | |
314 | ||
acfa4380 | 315 | if (!inode->i_op->removexattr) |
b5376771 SH |
316 | return 0; |
317 | ||
318 | return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS); | |
319 | } | |
320 | ||
1d045980 DH |
321 | /* |
322 | * Calculate the new process capability sets from the capability sets attached | |
323 | * to a file. | |
324 | */ | |
c0b00441 | 325 | static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, |
a6f76f23 | 326 | struct linux_binprm *bprm, |
4d49f671 ZL |
327 | bool *effective, |
328 | bool *has_cap) | |
b5376771 | 329 | { |
a6f76f23 | 330 | struct cred *new = bprm->cred; |
c0b00441 EP |
331 | unsigned i; |
332 | int ret = 0; | |
333 | ||
334 | if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) | |
a6f76f23 | 335 | *effective = true; |
c0b00441 | 336 | |
4d49f671 ZL |
337 | if (caps->magic_etc & VFS_CAP_REVISION_MASK) |
338 | *has_cap = true; | |
339 | ||
c0b00441 EP |
340 | CAP_FOR_EACH_U32(i) { |
341 | __u32 permitted = caps->permitted.cap[i]; | |
342 | __u32 inheritable = caps->inheritable.cap[i]; | |
343 | ||
344 | /* | |
345 | * pP' = (X & fP) | (pI & fI) | |
346 | */ | |
a6f76f23 DH |
347 | new->cap_permitted.cap[i] = |
348 | (new->cap_bset.cap[i] & permitted) | | |
349 | (new->cap_inheritable.cap[i] & inheritable); | |
c0b00441 | 350 | |
a6f76f23 DH |
351 | if (permitted & ~new->cap_permitted.cap[i]) |
352 | /* insufficient to execute correctly */ | |
c0b00441 | 353 | ret = -EPERM; |
c0b00441 EP |
354 | } |
355 | ||
356 | /* | |
357 | * For legacy apps, with no internal support for recognizing they | |
358 | * do not have enough capabilities, we return an error if they are | |
359 | * missing some "forced" (aka file-permitted) capabilities. | |
360 | */ | |
a6f76f23 | 361 | return *effective ? ret : 0; |
c0b00441 EP |
362 | } |
363 | ||
1d045980 DH |
364 | /* |
365 | * Extract the on-exec-apply capability sets for an executable file. | |
366 | */ | |
c0b00441 EP |
367 | int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps) |
368 | { | |
369 | struct inode *inode = dentry->d_inode; | |
b5376771 | 370 | __u32 magic_etc; |
e338d263 | 371 | unsigned tocopy, i; |
c0b00441 EP |
372 | int size; |
373 | struct vfs_cap_data caps; | |
374 | ||
375 | memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); | |
376 | ||
acfa4380 | 377 | if (!inode || !inode->i_op->getxattr) |
c0b00441 EP |
378 | return -ENODATA; |
379 | ||
380 | size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps, | |
381 | XATTR_CAPS_SZ); | |
a6f76f23 | 382 | if (size == -ENODATA || size == -EOPNOTSUPP) |
c0b00441 EP |
383 | /* no data, that's ok */ |
384 | return -ENODATA; | |
c0b00441 EP |
385 | if (size < 0) |
386 | return size; | |
b5376771 | 387 | |
e338d263 | 388 | if (size < sizeof(magic_etc)) |
b5376771 SH |
389 | return -EINVAL; |
390 | ||
c0b00441 | 391 | cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc); |
b5376771 | 392 | |
a6f76f23 | 393 | switch (magic_etc & VFS_CAP_REVISION_MASK) { |
e338d263 AM |
394 | case VFS_CAP_REVISION_1: |
395 | if (size != XATTR_CAPS_SZ_1) | |
396 | return -EINVAL; | |
397 | tocopy = VFS_CAP_U32_1; | |
398 | break; | |
399 | case VFS_CAP_REVISION_2: | |
400 | if (size != XATTR_CAPS_SZ_2) | |
401 | return -EINVAL; | |
402 | tocopy = VFS_CAP_U32_2; | |
403 | break; | |
b5376771 SH |
404 | default: |
405 | return -EINVAL; | |
406 | } | |
e338d263 | 407 | |
5459c164 | 408 | CAP_FOR_EACH_U32(i) { |
c0b00441 EP |
409 | if (i >= tocopy) |
410 | break; | |
411 | cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted); | |
412 | cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable); | |
e338d263 | 413 | } |
a6f76f23 | 414 | |
c0b00441 | 415 | return 0; |
b5376771 SH |
416 | } |
417 | ||
1d045980 DH |
418 | /* |
419 | * Attempt to get the on-exec apply capability sets for an executable file from | |
420 | * its xattrs and, if present, apply them to the proposed credentials being | |
421 | * constructed by execve(). | |
422 | */ | |
4d49f671 | 423 | static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_cap) |
b5376771 SH |
424 | { |
425 | struct dentry *dentry; | |
426 | int rc = 0; | |
c0b00441 | 427 | struct cpu_vfs_cap_data vcaps; |
b5376771 | 428 | |
3318a386 SH |
429 | bprm_clear_caps(bprm); |
430 | ||
1f29fae2 SH |
431 | if (!file_caps_enabled) |
432 | return 0; | |
433 | ||
3318a386 | 434 | if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) |
b5376771 | 435 | return 0; |
b5376771 SH |
436 | |
437 | dentry = dget(bprm->file->f_dentry); | |
b5376771 | 438 | |
c0b00441 EP |
439 | rc = get_vfs_caps_from_disk(dentry, &vcaps); |
440 | if (rc < 0) { | |
441 | if (rc == -EINVAL) | |
442 | printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n", | |
443 | __func__, rc, bprm->filename); | |
444 | else if (rc == -ENODATA) | |
445 | rc = 0; | |
b5376771 SH |
446 | goto out; |
447 | } | |
b5376771 | 448 | |
4d49f671 | 449 | rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_cap); |
a6f76f23 DH |
450 | if (rc == -EINVAL) |
451 | printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", | |
452 | __func__, rc, bprm->filename); | |
b5376771 SH |
453 | |
454 | out: | |
455 | dput(dentry); | |
456 | if (rc) | |
457 | bprm_clear_caps(bprm); | |
458 | ||
459 | return rc; | |
460 | } | |
461 | ||
1d045980 DH |
462 | /** |
463 | * cap_bprm_set_creds - Set up the proposed credentials for execve(). | |
464 | * @bprm: The execution parameters, including the proposed creds | |
465 | * | |
466 | * Set up the proposed credentials for a new execution context being | |
467 | * constructed by execve(). The proposed creds in @bprm->cred is altered, | |
468 | * which won't take effect immediately. Returns 0 if successful, -ve on error. | |
a6f76f23 DH |
469 | */ |
470 | int cap_bprm_set_creds(struct linux_binprm *bprm) | |
1da177e4 | 471 | { |
a6f76f23 DH |
472 | const struct cred *old = current_cred(); |
473 | struct cred *new = bprm->cred; | |
7d8db180 | 474 | bool effective, has_cap = false; |
b5376771 | 475 | int ret; |
1da177e4 | 476 | |
a6f76f23 | 477 | effective = false; |
4d49f671 | 478 | ret = get_file_caps(bprm, &effective, &has_cap); |
a6f76f23 DH |
479 | if (ret < 0) |
480 | return ret; | |
1da177e4 | 481 | |
5459c164 | 482 | if (!issecure(SECURE_NOROOT)) { |
b5f22a59 SH |
483 | /* |
484 | * If the legacy file capability is set, then don't set privs | |
485 | * for a setuid root binary run by a non-root user. Do set it | |
486 | * for a root user just to cause least surprise to an admin. | |
487 | */ | |
4d49f671 | 488 | if (has_cap && new->uid != 0 && new->euid == 0) { |
b5f22a59 SH |
489 | warn_setuid_and_fcaps_mixed(bprm->filename); |
490 | goto skip; | |
491 | } | |
5459c164 AM |
492 | /* |
493 | * To support inheritance of root-permissions and suid-root | |
494 | * executables under compatibility mode, we override the | |
495 | * capability sets for the file. | |
496 | * | |
a6f76f23 | 497 | * If only the real uid is 0, we do not set the effective bit. |
5459c164 | 498 | */ |
a6f76f23 | 499 | if (new->euid == 0 || new->uid == 0) { |
5459c164 | 500 | /* pP' = (cap_bset & ~0) | (pI & ~0) */ |
a6f76f23 DH |
501 | new->cap_permitted = cap_combine(old->cap_bset, |
502 | old->cap_inheritable); | |
1da177e4 | 503 | } |
a6f76f23 DH |
504 | if (new->euid == 0) |
505 | effective = true; | |
1da177e4 | 506 | } |
b5f22a59 | 507 | skip: |
b5376771 | 508 | |
d52fc5dd EP |
509 | /* if we have fs caps, clear dangerous personality flags */ |
510 | if (!cap_issubset(new->cap_permitted, old->cap_permitted)) | |
511 | bprm->per_clear |= PER_CLEAR_ON_SETID; | |
512 | ||
513 | ||
a6f76f23 DH |
514 | /* Don't let someone trace a set[ug]id/setpcap binary with the revised |
515 | * credentials unless they have the appropriate permit | |
516 | */ | |
517 | if ((new->euid != old->uid || | |
518 | new->egid != old->gid || | |
519 | !cap_issubset(new->cap_permitted, old->cap_permitted)) && | |
520 | bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) { | |
521 | /* downgrade; they get no more than they had, and maybe less */ | |
522 | if (!capable(CAP_SETUID)) { | |
523 | new->euid = new->uid; | |
524 | new->egid = new->gid; | |
1da177e4 | 525 | } |
b3a222e5 SH |
526 | new->cap_permitted = cap_intersect(new->cap_permitted, |
527 | old->cap_permitted); | |
1da177e4 LT |
528 | } |
529 | ||
a6f76f23 DH |
530 | new->suid = new->fsuid = new->euid; |
531 | new->sgid = new->fsgid = new->egid; | |
1da177e4 | 532 | |
4bf2ea77 EP |
533 | if (effective) |
534 | new->cap_effective = new->cap_permitted; | |
535 | else | |
536 | cap_clear(new->cap_effective); | |
a6f76f23 | 537 | bprm->cap_effective = effective; |
1da177e4 | 538 | |
3fc689e9 EP |
539 | /* |
540 | * Audit candidate if current->cap_effective is set | |
541 | * | |
542 | * We do not bother to audit if 3 things are true: | |
543 | * 1) cap_effective has all caps | |
544 | * 2) we are root | |
545 | * 3) root is supposed to have all caps (SECURE_NOROOT) | |
546 | * Since this is just a normal root execing a process. | |
547 | * | |
548 | * Number 1 above might fail if you don't have a full bset, but I think | |
549 | * that is interesting information to audit. | |
550 | */ | |
d84f4f99 DH |
551 | if (!cap_isclear(new->cap_effective)) { |
552 | if (!cap_issubset(CAP_FULL_SET, new->cap_effective) || | |
a6f76f23 DH |
553 | new->euid != 0 || new->uid != 0 || |
554 | issecure(SECURE_NOROOT)) { | |
555 | ret = audit_log_bprm_fcaps(bprm, new, old); | |
556 | if (ret < 0) | |
557 | return ret; | |
558 | } | |
3fc689e9 | 559 | } |
1da177e4 | 560 | |
d84f4f99 | 561 | new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
a6f76f23 | 562 | return 0; |
1da177e4 LT |
563 | } |
564 | ||
1d045980 DH |
565 | /** |
566 | * cap_bprm_secureexec - Determine whether a secure execution is required | |
567 | * @bprm: The execution parameters | |
568 | * | |
569 | * Determine whether a secure execution is required, return 1 if it is, and 0 | |
570 | * if it is not. | |
571 | * | |
572 | * The credentials have been committed by this point, and so are no longer | |
573 | * available through @bprm->cred. | |
a6f76f23 DH |
574 | */ |
575 | int cap_bprm_secureexec(struct linux_binprm *bprm) | |
1da177e4 | 576 | { |
c69e8d9c | 577 | const struct cred *cred = current_cred(); |
b6dff3ec DH |
578 | |
579 | if (cred->uid != 0) { | |
b5376771 SH |
580 | if (bprm->cap_effective) |
581 | return 1; | |
a6f76f23 | 582 | if (!cap_isclear(cred->cap_permitted)) |
b5376771 SH |
583 | return 1; |
584 | } | |
585 | ||
b6dff3ec DH |
586 | return (cred->euid != cred->uid || |
587 | cred->egid != cred->gid); | |
1da177e4 LT |
588 | } |
589 | ||
1d045980 DH |
590 | /** |
591 | * cap_inode_setxattr - Determine whether an xattr may be altered | |
592 | * @dentry: The inode/dentry being altered | |
593 | * @name: The name of the xattr to be changed | |
594 | * @value: The value that the xattr will be changed to | |
595 | * @size: The size of value | |
596 | * @flags: The replacement flag | |
597 | * | |
598 | * Determine whether an xattr may be altered or set on an inode, returning 0 if | |
599 | * permission is granted, -ve if denied. | |
600 | * | |
601 | * This is used to make sure security xattrs don't get updated or set by those | |
602 | * who aren't privileged to do so. | |
603 | */ | |
8f0cfa52 DH |
604 | int cap_inode_setxattr(struct dentry *dentry, const char *name, |
605 | const void *value, size_t size, int flags) | |
1da177e4 | 606 | { |
b5376771 SH |
607 | if (!strcmp(name, XATTR_NAME_CAPS)) { |
608 | if (!capable(CAP_SETFCAP)) | |
609 | return -EPERM; | |
610 | return 0; | |
1d045980 DH |
611 | } |
612 | ||
613 | if (!strncmp(name, XATTR_SECURITY_PREFIX, | |
c5b60b5e | 614 | sizeof(XATTR_SECURITY_PREFIX) - 1) && |
1da177e4 LT |
615 | !capable(CAP_SYS_ADMIN)) |
616 | return -EPERM; | |
617 | return 0; | |
618 | } | |
619 | ||
1d045980 DH |
620 | /** |
621 | * cap_inode_removexattr - Determine whether an xattr may be removed | |
622 | * @dentry: The inode/dentry being altered | |
623 | * @name: The name of the xattr to be changed | |
624 | * | |
625 | * Determine whether an xattr may be removed from an inode, returning 0 if | |
626 | * permission is granted, -ve if denied. | |
627 | * | |
628 | * This is used to make sure security xattrs don't get removed by those who | |
629 | * aren't privileged to remove them. | |
630 | */ | |
8f0cfa52 | 631 | int cap_inode_removexattr(struct dentry *dentry, const char *name) |
1da177e4 | 632 | { |
b5376771 SH |
633 | if (!strcmp(name, XATTR_NAME_CAPS)) { |
634 | if (!capable(CAP_SETFCAP)) | |
635 | return -EPERM; | |
636 | return 0; | |
1d045980 DH |
637 | } |
638 | ||
639 | if (!strncmp(name, XATTR_SECURITY_PREFIX, | |
c5b60b5e | 640 | sizeof(XATTR_SECURITY_PREFIX) - 1) && |
1da177e4 LT |
641 | !capable(CAP_SYS_ADMIN)) |
642 | return -EPERM; | |
643 | return 0; | |
644 | } | |
645 | ||
a6f76f23 | 646 | /* |
1da177e4 LT |
647 | * cap_emulate_setxuid() fixes the effective / permitted capabilities of |
648 | * a process after a call to setuid, setreuid, or setresuid. | |
649 | * | |
650 | * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of | |
651 | * {r,e,s}uid != 0, the permitted and effective capabilities are | |
652 | * cleared. | |
653 | * | |
654 | * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective | |
655 | * capabilities of the process are cleared. | |
656 | * | |
657 | * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective | |
658 | * capabilities are set to the permitted capabilities. | |
659 | * | |
a6f76f23 | 660 | * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should |
1da177e4 LT |
661 | * never happen. |
662 | * | |
a6f76f23 | 663 | * -astor |
1da177e4 LT |
664 | * |
665 | * cevans - New behaviour, Oct '99 | |
666 | * A process may, via prctl(), elect to keep its capabilities when it | |
667 | * calls setuid() and switches away from uid==0. Both permitted and | |
668 | * effective sets will be retained. | |
669 | * Without this change, it was impossible for a daemon to drop only some | |
670 | * of its privilege. The call to setuid(!=0) would drop all privileges! | |
671 | * Keeping uid 0 is not an option because uid 0 owns too many vital | |
672 | * files.. | |
673 | * Thanks to Olaf Kirch and Peter Benie for spotting this. | |
674 | */ | |
d84f4f99 | 675 | static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) |
1da177e4 | 676 | { |
d84f4f99 DH |
677 | if ((old->uid == 0 || old->euid == 0 || old->suid == 0) && |
678 | (new->uid != 0 && new->euid != 0 && new->suid != 0) && | |
3898b1b4 | 679 | !issecure(SECURE_KEEP_CAPS)) { |
d84f4f99 DH |
680 | cap_clear(new->cap_permitted); |
681 | cap_clear(new->cap_effective); | |
1da177e4 | 682 | } |
d84f4f99 DH |
683 | if (old->euid == 0 && new->euid != 0) |
684 | cap_clear(new->cap_effective); | |
685 | if (old->euid != 0 && new->euid == 0) | |
686 | new->cap_effective = new->cap_permitted; | |
1da177e4 LT |
687 | } |
688 | ||
1d045980 DH |
689 | /** |
690 | * cap_task_fix_setuid - Fix up the results of setuid() call | |
691 | * @new: The proposed credentials | |
692 | * @old: The current task's current credentials | |
693 | * @flags: Indications of what has changed | |
694 | * | |
695 | * Fix up the results of setuid() call before the credential changes are | |
696 | * actually applied, returning 0 to grant the changes, -ve to deny them. | |
697 | */ | |
d84f4f99 | 698 | int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) |
1da177e4 LT |
699 | { |
700 | switch (flags) { | |
701 | case LSM_SETID_RE: | |
702 | case LSM_SETID_ID: | |
703 | case LSM_SETID_RES: | |
1d045980 DH |
704 | /* juggle the capabilities to follow [RES]UID changes unless |
705 | * otherwise suppressed */ | |
d84f4f99 DH |
706 | if (!issecure(SECURE_NO_SETUID_FIXUP)) |
707 | cap_emulate_setxuid(new, old); | |
1da177e4 | 708 | break; |
1da177e4 | 709 | |
1d045980 DH |
710 | case LSM_SETID_FS: |
711 | /* juggle the capabilties to follow FSUID changes, unless | |
712 | * otherwise suppressed | |
713 | * | |
d84f4f99 DH |
714 | * FIXME - is fsuser used for all CAP_FS_MASK capabilities? |
715 | * if not, we might be a bit too harsh here. | |
716 | */ | |
717 | if (!issecure(SECURE_NO_SETUID_FIXUP)) { | |
1d045980 | 718 | if (old->fsuid == 0 && new->fsuid != 0) |
d84f4f99 DH |
719 | new->cap_effective = |
720 | cap_drop_fs_set(new->cap_effective); | |
1d045980 DH |
721 | |
722 | if (old->fsuid != 0 && new->fsuid == 0) | |
d84f4f99 DH |
723 | new->cap_effective = |
724 | cap_raise_fs_set(new->cap_effective, | |
725 | new->cap_permitted); | |
1da177e4 | 726 | } |
d84f4f99 | 727 | break; |
1d045980 | 728 | |
1da177e4 LT |
729 | default: |
730 | return -EINVAL; | |
731 | } | |
732 | ||
733 | return 0; | |
734 | } | |
735 | ||
b5376771 SH |
736 | /* |
737 | * Rationale: code calling task_setscheduler, task_setioprio, and | |
738 | * task_setnice, assumes that | |
739 | * . if capable(cap_sys_nice), then those actions should be allowed | |
740 | * . if not capable(cap_sys_nice), but acting on your own processes, | |
741 | * then those actions should be allowed | |
742 | * This is insufficient now since you can call code without suid, but | |
743 | * yet with increased caps. | |
744 | * So we check for increased caps on the target process. | |
745 | */ | |
de45e806 | 746 | static int cap_safe_nice(struct task_struct *p) |
b5376771 | 747 | { |
c69e8d9c DH |
748 | int is_subset; |
749 | ||
750 | rcu_read_lock(); | |
751 | is_subset = cap_issubset(__task_cred(p)->cap_permitted, | |
752 | current_cred()->cap_permitted); | |
753 | rcu_read_unlock(); | |
754 | ||
755 | if (!is_subset && !capable(CAP_SYS_NICE)) | |
b5376771 SH |
756 | return -EPERM; |
757 | return 0; | |
758 | } | |
759 | ||
1d045980 DH |
760 | /** |
761 | * cap_task_setscheduler - Detemine if scheduler policy change is permitted | |
762 | * @p: The task to affect | |
1d045980 DH |
763 | * |
764 | * Detemine if the requested scheduler policy change is permitted for the | |
765 | * specified task, returning 0 if permission is granted, -ve if denied. | |
766 | */ | |
b0ae1981 | 767 | int cap_task_setscheduler(struct task_struct *p) |
b5376771 SH |
768 | { |
769 | return cap_safe_nice(p); | |
770 | } | |
771 | ||
1d045980 DH |
772 | /** |
773 | * cap_task_ioprio - Detemine if I/O priority change is permitted | |
774 | * @p: The task to affect | |
775 | * @ioprio: The I/O priority to set | |
776 | * | |
777 | * Detemine if the requested I/O priority change is permitted for the specified | |
778 | * task, returning 0 if permission is granted, -ve if denied. | |
779 | */ | |
780 | int cap_task_setioprio(struct task_struct *p, int ioprio) | |
b5376771 SH |
781 | { |
782 | return cap_safe_nice(p); | |
783 | } | |
784 | ||
1d045980 DH |
785 | /** |
786 | * cap_task_ioprio - Detemine if task priority change is permitted | |
787 | * @p: The task to affect | |
788 | * @nice: The nice value to set | |
789 | * | |
790 | * Detemine if the requested task priority change is permitted for the | |
791 | * specified task, returning 0 if permission is granted, -ve if denied. | |
792 | */ | |
793 | int cap_task_setnice(struct task_struct *p, int nice) | |
b5376771 SH |
794 | { |
795 | return cap_safe_nice(p); | |
796 | } | |
797 | ||
3b7391de | 798 | /* |
1d045980 DH |
799 | * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from |
800 | * the current task's bounding set. Returns 0 on success, -ve on error. | |
3b7391de | 801 | */ |
d84f4f99 | 802 | static long cap_prctl_drop(struct cred *new, unsigned long cap) |
3b7391de SH |
803 | { |
804 | if (!capable(CAP_SETPCAP)) | |
805 | return -EPERM; | |
806 | if (!cap_valid(cap)) | |
807 | return -EINVAL; | |
d84f4f99 DH |
808 | |
809 | cap_lower(new->cap_bset, cap); | |
3b7391de SH |
810 | return 0; |
811 | } | |
3898b1b4 | 812 | |
1d045980 DH |
813 | /** |
814 | * cap_task_prctl - Implement process control functions for this security module | |
815 | * @option: The process control function requested | |
816 | * @arg2, @arg3, @arg4, @arg5: The argument data for this function | |
817 | * | |
818 | * Allow process control functions (sys_prctl()) to alter capabilities; may | |
819 | * also deny access to other functions not otherwise implemented here. | |
820 | * | |
821 | * Returns 0 or +ve on success, -ENOSYS if this function is not implemented | |
822 | * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM | |
823 | * modules will consider performing the function. | |
824 | */ | |
3898b1b4 | 825 | int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, |
d84f4f99 | 826 | unsigned long arg4, unsigned long arg5) |
3898b1b4 | 827 | { |
d84f4f99 | 828 | struct cred *new; |
3898b1b4 AM |
829 | long error = 0; |
830 | ||
d84f4f99 DH |
831 | new = prepare_creds(); |
832 | if (!new) | |
833 | return -ENOMEM; | |
834 | ||
3898b1b4 AM |
835 | switch (option) { |
836 | case PR_CAPBSET_READ: | |
d84f4f99 | 837 | error = -EINVAL; |
3898b1b4 | 838 | if (!cap_valid(arg2)) |
d84f4f99 DH |
839 | goto error; |
840 | error = !!cap_raised(new->cap_bset, arg2); | |
841 | goto no_change; | |
842 | ||
3898b1b4 | 843 | case PR_CAPBSET_DROP: |
d84f4f99 DH |
844 | error = cap_prctl_drop(new, arg2); |
845 | if (error < 0) | |
846 | goto error; | |
847 | goto changed; | |
3898b1b4 AM |
848 | |
849 | /* | |
850 | * The next four prctl's remain to assist with transitioning a | |
851 | * system from legacy UID=0 based privilege (when filesystem | |
852 | * capabilities are not in use) to a system using filesystem | |
853 | * capabilities only - as the POSIX.1e draft intended. | |
854 | * | |
855 | * Note: | |
856 | * | |
857 | * PR_SET_SECUREBITS = | |
858 | * issecure_mask(SECURE_KEEP_CAPS_LOCKED) | |
859 | * | issecure_mask(SECURE_NOROOT) | |
860 | * | issecure_mask(SECURE_NOROOT_LOCKED) | |
861 | * | issecure_mask(SECURE_NO_SETUID_FIXUP) | |
862 | * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED) | |
863 | * | |
864 | * will ensure that the current process and all of its | |
865 | * children will be locked into a pure | |
866 | * capability-based-privilege environment. | |
867 | */ | |
868 | case PR_SET_SECUREBITS: | |
d84f4f99 DH |
869 | error = -EPERM; |
870 | if ((((new->securebits & SECURE_ALL_LOCKS) >> 1) | |
871 | & (new->securebits ^ arg2)) /*[1]*/ | |
872 | || ((new->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ | |
873 | || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ | |
6a9de491 | 874 | || (cap_capable(current_cred(), |
3486740a | 875 | current_cred()->user->user_ns, CAP_SETPCAP, |
3699c53c | 876 | SECURITY_CAP_AUDIT) != 0) /*[4]*/ |
3898b1b4 AM |
877 | /* |
878 | * [1] no changing of bits that are locked | |
879 | * [2] no unlocking of locks | |
880 | * [3] no setting of unsupported bits | |
881 | * [4] doing anything requires privilege (go read about | |
882 | * the "sendmail capabilities bug") | |
883 | */ | |
d84f4f99 DH |
884 | ) |
885 | /* cannot change a locked bit */ | |
886 | goto error; | |
887 | new->securebits = arg2; | |
888 | goto changed; | |
889 | ||
3898b1b4 | 890 | case PR_GET_SECUREBITS: |
d84f4f99 DH |
891 | error = new->securebits; |
892 | goto no_change; | |
3898b1b4 | 893 | |
3898b1b4 AM |
894 | case PR_GET_KEEPCAPS: |
895 | if (issecure(SECURE_KEEP_CAPS)) | |
896 | error = 1; | |
d84f4f99 DH |
897 | goto no_change; |
898 | ||
3898b1b4 | 899 | case PR_SET_KEEPCAPS: |
d84f4f99 | 900 | error = -EINVAL; |
3898b1b4 | 901 | if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */ |
d84f4f99 DH |
902 | goto error; |
903 | error = -EPERM; | |
904 | if (issecure(SECURE_KEEP_CAPS_LOCKED)) | |
905 | goto error; | |
906 | if (arg2) | |
907 | new->securebits |= issecure_mask(SECURE_KEEP_CAPS); | |
3898b1b4 | 908 | else |
d84f4f99 DH |
909 | new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
910 | goto changed; | |
3898b1b4 AM |
911 | |
912 | default: | |
913 | /* No functionality available - continue with default */ | |
d84f4f99 DH |
914 | error = -ENOSYS; |
915 | goto error; | |
3898b1b4 AM |
916 | } |
917 | ||
918 | /* Functionality provided */ | |
d84f4f99 DH |
919 | changed: |
920 | return commit_creds(new); | |
921 | ||
922 | no_change: | |
d84f4f99 DH |
923 | error: |
924 | abort_creds(new); | |
925 | return error; | |
1da177e4 LT |
926 | } |
927 | ||
1d045980 DH |
928 | /** |
929 | * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted | |
930 | * @mm: The VM space in which the new mapping is to be made | |
931 | * @pages: The size of the mapping | |
932 | * | |
933 | * Determine whether the allocation of a new virtual mapping by the current | |
934 | * task is permitted, returning 0 if permission is granted, -ve if not. | |
935 | */ | |
34b4e4aa | 936 | int cap_vm_enough_memory(struct mm_struct *mm, long pages) |
1da177e4 LT |
937 | { |
938 | int cap_sys_admin = 0; | |
939 | ||
6a9de491 | 940 | if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN, |
3699c53c | 941 | SECURITY_CAP_NOAUDIT) == 0) |
1da177e4 | 942 | cap_sys_admin = 1; |
34b4e4aa | 943 | return __vm_enough_memory(mm, pages, cap_sys_admin); |
1da177e4 | 944 | } |
7c73875e EP |
945 | |
946 | /* | |
947 | * cap_file_mmap - check if able to map given addr | |
948 | * @file: unused | |
949 | * @reqprot: unused | |
950 | * @prot: unused | |
951 | * @flags: unused | |
952 | * @addr: address attempting to be mapped | |
953 | * @addr_only: unused | |
954 | * | |
6f262d8e | 955 | * If the process is attempting to map memory below dac_mmap_min_addr they need |
7c73875e EP |
956 | * CAP_SYS_RAWIO. The other parameters to this function are unused by the |
957 | * capability security module. Returns 0 if this mapping should be allowed | |
958 | * -EPERM if not. | |
959 | */ | |
960 | int cap_file_mmap(struct file *file, unsigned long reqprot, | |
961 | unsigned long prot, unsigned long flags, | |
962 | unsigned long addr, unsigned long addr_only) | |
963 | { | |
964 | int ret = 0; | |
965 | ||
a2551df7 | 966 | if (addr < dac_mmap_min_addr) { |
6a9de491 | 967 | ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO, |
7c73875e EP |
968 | SECURITY_CAP_AUDIT); |
969 | /* set PF_SUPERPRIV if it turns out we allow the low mmap */ | |
970 | if (ret == 0) | |
971 | current->flags |= PF_SUPERPRIV; | |
972 | } | |
973 | return ret; | |
974 | } |