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e338d263 | 1 | /* Common capabilities, needed by capability.o and root_plug.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> | |
72c2d582 | 30 | |
1da177e4 LT |
31 | int cap_netlink_send(struct sock *sk, struct sk_buff *skb) |
32 | { | |
b6dff3ec | 33 | NETLINK_CB(skb).eff_cap = current_cap(); |
1da177e4 LT |
34 | return 0; |
35 | } | |
36 | ||
c7bdb545 | 37 | int cap_netlink_recv(struct sk_buff *skb, int cap) |
1da177e4 | 38 | { |
c7bdb545 | 39 | if (!cap_raised(NETLINK_CB(skb).eff_cap, cap)) |
1da177e4 LT |
40 | return -EPERM; |
41 | return 0; | |
42 | } | |
1da177e4 LT |
43 | EXPORT_SYMBOL(cap_netlink_recv); |
44 | ||
1d045980 | 45 | /** |
29881c45 JM |
46 | * cap_capable - Determine whether a task has a particular effective capability |
47 | * @tsk: The task to query | |
3699c53c | 48 | * @cred: The credentials to use |
1d045980 DH |
49 | * @cap: The capability to check for |
50 | * @audit: Whether to write an audit message or not | |
51 | * | |
52 | * Determine whether the nominated task has the specified capability amongst | |
29881c45 | 53 | * its effective set, returning 0 if it does, -ve if it does not. |
1d045980 | 54 | * |
3699c53c DH |
55 | * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable() |
56 | * and has_capability() functions. That is, it has the reverse semantics: | |
57 | * cap_has_capability() returns 0 when a task has a capability, but the | |
58 | * kernel's capable() and has_capability() returns 1 for this case. | |
a6dbb1ef | 59 | */ |
3699c53c DH |
60 | int cap_capable(struct task_struct *tsk, const struct cred *cred, int cap, |
61 | int audit) | |
1da177e4 | 62 | { |
3699c53c | 63 | return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; |
1da177e4 LT |
64 | } |
65 | ||
1d045980 DH |
66 | /** |
67 | * cap_settime - Determine whether the current process may set the system clock | |
68 | * @ts: The time to set | |
69 | * @tz: The timezone to set | |
70 | * | |
71 | * Determine whether the current process may set the system clock and timezone | |
72 | * information, returning 0 if permission granted, -ve if denied. | |
73 | */ | |
1da177e4 LT |
74 | int cap_settime(struct timespec *ts, struct timezone *tz) |
75 | { | |
76 | if (!capable(CAP_SYS_TIME)) | |
77 | return -EPERM; | |
78 | return 0; | |
79 | } | |
80 | ||
1d045980 DH |
81 | /** |
82 | * cap_ptrace_may_access - Determine whether the current process may access | |
83 | * another | |
84 | * @child: The process to be accessed | |
85 | * @mode: The mode of attachment. | |
86 | * | |
87 | * Determine whether a process may access another, returning 0 if permission | |
88 | * granted, -ve if denied. | |
89 | */ | |
5cd9c58f | 90 | int cap_ptrace_may_access(struct task_struct *child, unsigned int mode) |
1da177e4 | 91 | { |
c69e8d9c DH |
92 | int ret = 0; |
93 | ||
94 | rcu_read_lock(); | |
d84f4f99 DH |
95 | if (!cap_issubset(__task_cred(child)->cap_permitted, |
96 | current_cred()->cap_permitted) && | |
c69e8d9c DH |
97 | !capable(CAP_SYS_PTRACE)) |
98 | ret = -EPERM; | |
99 | rcu_read_unlock(); | |
100 | return ret; | |
5cd9c58f DH |
101 | } |
102 | ||
1d045980 DH |
103 | /** |
104 | * cap_ptrace_traceme - Determine whether another process may trace the current | |
105 | * @parent: The task proposed to be the tracer | |
106 | * | |
107 | * Determine whether the nominated task is permitted to trace the current | |
108 | * process, returning 0 if permission is granted, -ve if denied. | |
109 | */ | |
5cd9c58f DH |
110 | int cap_ptrace_traceme(struct task_struct *parent) |
111 | { | |
c69e8d9c DH |
112 | int ret = 0; |
113 | ||
114 | rcu_read_lock(); | |
d84f4f99 DH |
115 | if (!cap_issubset(current_cred()->cap_permitted, |
116 | __task_cred(parent)->cap_permitted) && | |
c69e8d9c DH |
117 | !has_capability(parent, CAP_SYS_PTRACE)) |
118 | ret = -EPERM; | |
119 | rcu_read_unlock(); | |
120 | return ret; | |
1da177e4 LT |
121 | } |
122 | ||
1d045980 DH |
123 | /** |
124 | * cap_capget - Retrieve a task's capability sets | |
125 | * @target: The task from which to retrieve the capability sets | |
126 | * @effective: The place to record the effective set | |
127 | * @inheritable: The place to record the inheritable set | |
128 | * @permitted: The place to record the permitted set | |
129 | * | |
130 | * This function retrieves the capabilities of the nominated task and returns | |
131 | * them to the caller. | |
132 | */ | |
133 | int cap_capget(struct task_struct *target, kernel_cap_t *effective, | |
134 | kernel_cap_t *inheritable, kernel_cap_t *permitted) | |
1da177e4 | 135 | { |
c69e8d9c | 136 | const struct cred *cred; |
b6dff3ec | 137 | |
1da177e4 | 138 | /* Derived from kernel/capability.c:sys_capget. */ |
c69e8d9c DH |
139 | rcu_read_lock(); |
140 | cred = __task_cred(target); | |
b6dff3ec DH |
141 | *effective = cred->cap_effective; |
142 | *inheritable = cred->cap_inheritable; | |
143 | *permitted = cred->cap_permitted; | |
c69e8d9c | 144 | rcu_read_unlock(); |
1da177e4 LT |
145 | return 0; |
146 | } | |
147 | ||
1d045980 DH |
148 | /* |
149 | * Determine whether the inheritable capabilities are limited to the old | |
150 | * permitted set. Returns 1 if they are limited, 0 if they are not. | |
151 | */ | |
72c2d582 AM |
152 | static inline int cap_inh_is_capped(void) |
153 | { | |
1d045980 | 154 | #ifdef CONFIG_SECURITY_FILE_CAPABILITIES |
72c2d582 | 155 | |
1d045980 DH |
156 | /* they are so limited unless the current task has the CAP_SETPCAP |
157 | * capability | |
158 | */ | |
3699c53c DH |
159 | if (cap_capable(current, current_cred(), CAP_SETPCAP, |
160 | SECURITY_CAP_AUDIT) == 0) | |
1d045980 DH |
161 | return 0; |
162 | #endif | |
163 | return 1; | |
1209726c | 164 | } |
72c2d582 | 165 | |
1d045980 DH |
166 | /** |
167 | * cap_capset - Validate and apply proposed changes to current's capabilities | |
168 | * @new: The proposed new credentials; alterations should be made here | |
169 | * @old: The current task's current credentials | |
170 | * @effective: A pointer to the proposed new effective capabilities set | |
171 | * @inheritable: A pointer to the proposed new inheritable capabilities set | |
172 | * @permitted: A pointer to the proposed new permitted capabilities set | |
173 | * | |
174 | * This function validates and applies a proposed mass change to the current | |
175 | * process's capability sets. The changes are made to the proposed new | |
176 | * credentials, and assuming no error, will be committed by the caller of LSM. | |
177 | */ | |
d84f4f99 DH |
178 | int cap_capset(struct cred *new, |
179 | const struct cred *old, | |
180 | const kernel_cap_t *effective, | |
181 | const kernel_cap_t *inheritable, | |
182 | const kernel_cap_t *permitted) | |
1da177e4 | 183 | { |
d84f4f99 DH |
184 | if (cap_inh_is_capped() && |
185 | !cap_issubset(*inheritable, | |
186 | cap_combine(old->cap_inheritable, | |
187 | old->cap_permitted))) | |
72c2d582 | 188 | /* incapable of using this inheritable set */ |
1da177e4 | 189 | return -EPERM; |
d84f4f99 | 190 | |
3b7391de | 191 | if (!cap_issubset(*inheritable, |
d84f4f99 DH |
192 | cap_combine(old->cap_inheritable, |
193 | old->cap_bset))) | |
3b7391de SH |
194 | /* no new pI capabilities outside bounding set */ |
195 | return -EPERM; | |
1da177e4 LT |
196 | |
197 | /* verify restrictions on target's new Permitted set */ | |
d84f4f99 | 198 | if (!cap_issubset(*permitted, old->cap_permitted)) |
1da177e4 | 199 | return -EPERM; |
1da177e4 LT |
200 | |
201 | /* verify the _new_Effective_ is a subset of the _new_Permitted_ */ | |
d84f4f99 | 202 | if (!cap_issubset(*effective, *permitted)) |
1da177e4 | 203 | return -EPERM; |
1da177e4 | 204 | |
d84f4f99 DH |
205 | new->cap_effective = *effective; |
206 | new->cap_inheritable = *inheritable; | |
207 | new->cap_permitted = *permitted; | |
1da177e4 LT |
208 | return 0; |
209 | } | |
210 | ||
1d045980 DH |
211 | /* |
212 | * Clear proposed capability sets for execve(). | |
213 | */ | |
b5376771 SH |
214 | static inline void bprm_clear_caps(struct linux_binprm *bprm) |
215 | { | |
a6f76f23 | 216 | cap_clear(bprm->cred->cap_permitted); |
b5376771 SH |
217 | bprm->cap_effective = false; |
218 | } | |
219 | ||
220 | #ifdef CONFIG_SECURITY_FILE_CAPABILITIES | |
221 | ||
1d045980 DH |
222 | /** |
223 | * cap_inode_need_killpriv - Determine if inode change affects privileges | |
224 | * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV | |
225 | * | |
226 | * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV | |
227 | * affects the security markings on that inode, and if it is, should | |
228 | * inode_killpriv() be invoked or the change rejected? | |
229 | * | |
230 | * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and | |
231 | * -ve to deny the change. | |
232 | */ | |
b5376771 SH |
233 | int cap_inode_need_killpriv(struct dentry *dentry) |
234 | { | |
235 | struct inode *inode = dentry->d_inode; | |
236 | int error; | |
237 | ||
238 | if (!inode->i_op || !inode->i_op->getxattr) | |
239 | return 0; | |
240 | ||
241 | error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0); | |
242 | if (error <= 0) | |
243 | return 0; | |
244 | return 1; | |
245 | } | |
246 | ||
1d045980 DH |
247 | /** |
248 | * cap_inode_killpriv - Erase the security markings on an inode | |
249 | * @dentry: The inode/dentry to alter | |
250 | * | |
251 | * Erase the privilege-enhancing security markings on an inode. | |
252 | * | |
253 | * Returns 0 if successful, -ve on error. | |
254 | */ | |
b5376771 SH |
255 | int cap_inode_killpriv(struct dentry *dentry) |
256 | { | |
257 | struct inode *inode = dentry->d_inode; | |
258 | ||
259 | if (!inode->i_op || !inode->i_op->removexattr) | |
260 | return 0; | |
261 | ||
262 | return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS); | |
263 | } | |
264 | ||
1d045980 DH |
265 | /* |
266 | * Calculate the new process capability sets from the capability sets attached | |
267 | * to a file. | |
268 | */ | |
c0b00441 | 269 | static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, |
a6f76f23 DH |
270 | struct linux_binprm *bprm, |
271 | bool *effective) | |
b5376771 | 272 | { |
a6f76f23 | 273 | struct cred *new = bprm->cred; |
c0b00441 EP |
274 | unsigned i; |
275 | int ret = 0; | |
276 | ||
277 | if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) | |
a6f76f23 | 278 | *effective = true; |
c0b00441 EP |
279 | |
280 | CAP_FOR_EACH_U32(i) { | |
281 | __u32 permitted = caps->permitted.cap[i]; | |
282 | __u32 inheritable = caps->inheritable.cap[i]; | |
283 | ||
284 | /* | |
285 | * pP' = (X & fP) | (pI & fI) | |
286 | */ | |
a6f76f23 DH |
287 | new->cap_permitted.cap[i] = |
288 | (new->cap_bset.cap[i] & permitted) | | |
289 | (new->cap_inheritable.cap[i] & inheritable); | |
c0b00441 | 290 | |
a6f76f23 DH |
291 | if (permitted & ~new->cap_permitted.cap[i]) |
292 | /* insufficient to execute correctly */ | |
c0b00441 | 293 | ret = -EPERM; |
c0b00441 EP |
294 | } |
295 | ||
296 | /* | |
297 | * For legacy apps, with no internal support for recognizing they | |
298 | * do not have enough capabilities, we return an error if they are | |
299 | * missing some "forced" (aka file-permitted) capabilities. | |
300 | */ | |
a6f76f23 | 301 | return *effective ? ret : 0; |
c0b00441 EP |
302 | } |
303 | ||
1d045980 DH |
304 | /* |
305 | * Extract the on-exec-apply capability sets for an executable file. | |
306 | */ | |
c0b00441 EP |
307 | int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps) |
308 | { | |
309 | struct inode *inode = dentry->d_inode; | |
b5376771 | 310 | __u32 magic_etc; |
e338d263 | 311 | unsigned tocopy, i; |
c0b00441 EP |
312 | int size; |
313 | struct vfs_cap_data caps; | |
314 | ||
315 | memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); | |
316 | ||
317 | if (!inode || !inode->i_op || !inode->i_op->getxattr) | |
318 | return -ENODATA; | |
319 | ||
320 | size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps, | |
321 | XATTR_CAPS_SZ); | |
a6f76f23 | 322 | if (size == -ENODATA || size == -EOPNOTSUPP) |
c0b00441 EP |
323 | /* no data, that's ok */ |
324 | return -ENODATA; | |
c0b00441 EP |
325 | if (size < 0) |
326 | return size; | |
b5376771 | 327 | |
e338d263 | 328 | if (size < sizeof(magic_etc)) |
b5376771 SH |
329 | return -EINVAL; |
330 | ||
c0b00441 | 331 | cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc); |
b5376771 | 332 | |
a6f76f23 | 333 | switch (magic_etc & VFS_CAP_REVISION_MASK) { |
e338d263 AM |
334 | case VFS_CAP_REVISION_1: |
335 | if (size != XATTR_CAPS_SZ_1) | |
336 | return -EINVAL; | |
337 | tocopy = VFS_CAP_U32_1; | |
338 | break; | |
339 | case VFS_CAP_REVISION_2: | |
340 | if (size != XATTR_CAPS_SZ_2) | |
341 | return -EINVAL; | |
342 | tocopy = VFS_CAP_U32_2; | |
343 | break; | |
b5376771 SH |
344 | default: |
345 | return -EINVAL; | |
346 | } | |
e338d263 | 347 | |
5459c164 | 348 | CAP_FOR_EACH_U32(i) { |
c0b00441 EP |
349 | if (i >= tocopy) |
350 | break; | |
351 | cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted); | |
352 | cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable); | |
e338d263 | 353 | } |
a6f76f23 | 354 | |
c0b00441 | 355 | return 0; |
b5376771 SH |
356 | } |
357 | ||
1d045980 DH |
358 | /* |
359 | * Attempt to get the on-exec apply capability sets for an executable file from | |
360 | * its xattrs and, if present, apply them to the proposed credentials being | |
361 | * constructed by execve(). | |
362 | */ | |
a6f76f23 | 363 | static int get_file_caps(struct linux_binprm *bprm, bool *effective) |
b5376771 SH |
364 | { |
365 | struct dentry *dentry; | |
366 | int rc = 0; | |
c0b00441 | 367 | struct cpu_vfs_cap_data vcaps; |
b5376771 | 368 | |
3318a386 SH |
369 | bprm_clear_caps(bprm); |
370 | ||
1f29fae2 SH |
371 | if (!file_caps_enabled) |
372 | return 0; | |
373 | ||
3318a386 | 374 | if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) |
b5376771 | 375 | return 0; |
b5376771 SH |
376 | |
377 | dentry = dget(bprm->file->f_dentry); | |
b5376771 | 378 | |
c0b00441 EP |
379 | rc = get_vfs_caps_from_disk(dentry, &vcaps); |
380 | if (rc < 0) { | |
381 | if (rc == -EINVAL) | |
382 | printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n", | |
383 | __func__, rc, bprm->filename); | |
384 | else if (rc == -ENODATA) | |
385 | rc = 0; | |
b5376771 SH |
386 | goto out; |
387 | } | |
b5376771 | 388 | |
a6f76f23 DH |
389 | rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective); |
390 | if (rc == -EINVAL) | |
391 | printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", | |
392 | __func__, rc, bprm->filename); | |
b5376771 SH |
393 | |
394 | out: | |
395 | dput(dentry); | |
396 | if (rc) | |
397 | bprm_clear_caps(bprm); | |
398 | ||
399 | return rc; | |
400 | } | |
401 | ||
402 | #else | |
403 | int cap_inode_need_killpriv(struct dentry *dentry) | |
404 | { | |
405 | return 0; | |
406 | } | |
407 | ||
408 | int cap_inode_killpriv(struct dentry *dentry) | |
409 | { | |
410 | return 0; | |
411 | } | |
412 | ||
e50a906e EP |
413 | int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps) |
414 | { | |
415 | memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); | |
416 | return -ENODATA; | |
417 | } | |
418 | ||
a6f76f23 | 419 | static inline int get_file_caps(struct linux_binprm *bprm, bool *effective) |
b5376771 SH |
420 | { |
421 | bprm_clear_caps(bprm); | |
422 | return 0; | |
423 | } | |
424 | #endif | |
425 | ||
a6f76f23 | 426 | /* |
1d045980 DH |
427 | * Determine whether a exec'ing process's new permitted capabilities should be |
428 | * limited to just what it already has. | |
429 | * | |
430 | * This prevents processes that are being ptraced from gaining access to | |
431 | * CAP_SETPCAP, unless the process they're tracing already has it, and the | |
432 | * binary they're executing has filecaps that elevate it. | |
433 | * | |
434 | * Returns 1 if they should be limited, 0 if they are not. | |
435 | */ | |
436 | static inline int cap_limit_ptraced_target(void) | |
437 | { | |
438 | #ifndef CONFIG_SECURITY_FILE_CAPABILITIES | |
439 | if (capable(CAP_SETPCAP)) | |
440 | return 0; | |
441 | #endif | |
442 | return 1; | |
443 | } | |
444 | ||
445 | /** | |
446 | * cap_bprm_set_creds - Set up the proposed credentials for execve(). | |
447 | * @bprm: The execution parameters, including the proposed creds | |
448 | * | |
449 | * Set up the proposed credentials for a new execution context being | |
450 | * constructed by execve(). The proposed creds in @bprm->cred is altered, | |
451 | * which won't take effect immediately. Returns 0 if successful, -ve on error. | |
a6f76f23 DH |
452 | */ |
453 | int cap_bprm_set_creds(struct linux_binprm *bprm) | |
1da177e4 | 454 | { |
a6f76f23 DH |
455 | const struct cred *old = current_cred(); |
456 | struct cred *new = bprm->cred; | |
457 | bool effective; | |
b5376771 | 458 | int ret; |
1da177e4 | 459 | |
a6f76f23 DH |
460 | effective = false; |
461 | ret = get_file_caps(bprm, &effective); | |
462 | if (ret < 0) | |
463 | return ret; | |
1da177e4 | 464 | |
5459c164 AM |
465 | if (!issecure(SECURE_NOROOT)) { |
466 | /* | |
467 | * To support inheritance of root-permissions and suid-root | |
468 | * executables under compatibility mode, we override the | |
469 | * capability sets for the file. | |
470 | * | |
a6f76f23 | 471 | * If only the real uid is 0, we do not set the effective bit. |
5459c164 | 472 | */ |
a6f76f23 | 473 | if (new->euid == 0 || new->uid == 0) { |
5459c164 | 474 | /* pP' = (cap_bset & ~0) | (pI & ~0) */ |
a6f76f23 DH |
475 | new->cap_permitted = cap_combine(old->cap_bset, |
476 | old->cap_inheritable); | |
1da177e4 | 477 | } |
a6f76f23 DH |
478 | if (new->euid == 0) |
479 | effective = true; | |
1da177e4 | 480 | } |
b5376771 | 481 | |
a6f76f23 DH |
482 | /* Don't let someone trace a set[ug]id/setpcap binary with the revised |
483 | * credentials unless they have the appropriate permit | |
484 | */ | |
485 | if ((new->euid != old->uid || | |
486 | new->egid != old->gid || | |
487 | !cap_issubset(new->cap_permitted, old->cap_permitted)) && | |
488 | bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) { | |
489 | /* downgrade; they get no more than they had, and maybe less */ | |
490 | if (!capable(CAP_SETUID)) { | |
491 | new->euid = new->uid; | |
492 | new->egid = new->gid; | |
1da177e4 | 493 | } |
a6f76f23 DH |
494 | if (cap_limit_ptraced_target()) |
495 | new->cap_permitted = cap_intersect(new->cap_permitted, | |
496 | old->cap_permitted); | |
1da177e4 LT |
497 | } |
498 | ||
a6f76f23 DH |
499 | new->suid = new->fsuid = new->euid; |
500 | new->sgid = new->fsgid = new->egid; | |
1da177e4 | 501 | |
a6f76f23 DH |
502 | /* For init, we want to retain the capabilities set in the initial |
503 | * task. Thus we skip the usual capability rules | |
504 | */ | |
b460cbc5 | 505 | if (!is_global_init(current)) { |
a6f76f23 DH |
506 | if (effective) |
507 | new->cap_effective = new->cap_permitted; | |
e338d263 | 508 | else |
d84f4f99 | 509 | cap_clear(new->cap_effective); |
1da177e4 | 510 | } |
a6f76f23 | 511 | bprm->cap_effective = effective; |
1da177e4 | 512 | |
3fc689e9 EP |
513 | /* |
514 | * Audit candidate if current->cap_effective is set | |
515 | * | |
516 | * We do not bother to audit if 3 things are true: | |
517 | * 1) cap_effective has all caps | |
518 | * 2) we are root | |
519 | * 3) root is supposed to have all caps (SECURE_NOROOT) | |
520 | * Since this is just a normal root execing a process. | |
521 | * | |
522 | * Number 1 above might fail if you don't have a full bset, but I think | |
523 | * that is interesting information to audit. | |
524 | */ | |
d84f4f99 DH |
525 | if (!cap_isclear(new->cap_effective)) { |
526 | if (!cap_issubset(CAP_FULL_SET, new->cap_effective) || | |
a6f76f23 DH |
527 | new->euid != 0 || new->uid != 0 || |
528 | issecure(SECURE_NOROOT)) { | |
529 | ret = audit_log_bprm_fcaps(bprm, new, old); | |
530 | if (ret < 0) | |
531 | return ret; | |
532 | } | |
3fc689e9 | 533 | } |
1da177e4 | 534 | |
d84f4f99 | 535 | new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
a6f76f23 | 536 | return 0; |
1da177e4 LT |
537 | } |
538 | ||
1d045980 DH |
539 | /** |
540 | * cap_bprm_secureexec - Determine whether a secure execution is required | |
541 | * @bprm: The execution parameters | |
542 | * | |
543 | * Determine whether a secure execution is required, return 1 if it is, and 0 | |
544 | * if it is not. | |
545 | * | |
546 | * The credentials have been committed by this point, and so are no longer | |
547 | * available through @bprm->cred. | |
a6f76f23 DH |
548 | */ |
549 | int cap_bprm_secureexec(struct linux_binprm *bprm) | |
1da177e4 | 550 | { |
c69e8d9c | 551 | const struct cred *cred = current_cred(); |
b6dff3ec DH |
552 | |
553 | if (cred->uid != 0) { | |
b5376771 SH |
554 | if (bprm->cap_effective) |
555 | return 1; | |
a6f76f23 | 556 | if (!cap_isclear(cred->cap_permitted)) |
b5376771 SH |
557 | return 1; |
558 | } | |
559 | ||
b6dff3ec DH |
560 | return (cred->euid != cred->uid || |
561 | cred->egid != cred->gid); | |
1da177e4 LT |
562 | } |
563 | ||
1d045980 DH |
564 | /** |
565 | * cap_inode_setxattr - Determine whether an xattr may be altered | |
566 | * @dentry: The inode/dentry being altered | |
567 | * @name: The name of the xattr to be changed | |
568 | * @value: The value that the xattr will be changed to | |
569 | * @size: The size of value | |
570 | * @flags: The replacement flag | |
571 | * | |
572 | * Determine whether an xattr may be altered or set on an inode, returning 0 if | |
573 | * permission is granted, -ve if denied. | |
574 | * | |
575 | * This is used to make sure security xattrs don't get updated or set by those | |
576 | * who aren't privileged to do so. | |
577 | */ | |
8f0cfa52 DH |
578 | int cap_inode_setxattr(struct dentry *dentry, const char *name, |
579 | const void *value, size_t size, int flags) | |
1da177e4 | 580 | { |
b5376771 SH |
581 | if (!strcmp(name, XATTR_NAME_CAPS)) { |
582 | if (!capable(CAP_SETFCAP)) | |
583 | return -EPERM; | |
584 | return 0; | |
1d045980 DH |
585 | } |
586 | ||
587 | if (!strncmp(name, XATTR_SECURITY_PREFIX, | |
1da177e4 LT |
588 | sizeof(XATTR_SECURITY_PREFIX) - 1) && |
589 | !capable(CAP_SYS_ADMIN)) | |
590 | return -EPERM; | |
591 | return 0; | |
592 | } | |
593 | ||
1d045980 DH |
594 | /** |
595 | * cap_inode_removexattr - Determine whether an xattr may be removed | |
596 | * @dentry: The inode/dentry being altered | |
597 | * @name: The name of the xattr to be changed | |
598 | * | |
599 | * Determine whether an xattr may be removed from an inode, returning 0 if | |
600 | * permission is granted, -ve if denied. | |
601 | * | |
602 | * This is used to make sure security xattrs don't get removed by those who | |
603 | * aren't privileged to remove them. | |
604 | */ | |
8f0cfa52 | 605 | int cap_inode_removexattr(struct dentry *dentry, const char *name) |
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, | |
1da177e4 LT |
614 | sizeof(XATTR_SECURITY_PREFIX) - 1) && |
615 | !capable(CAP_SYS_ADMIN)) | |
616 | return -EPERM; | |
617 | return 0; | |
618 | } | |
619 | ||
a6f76f23 | 620 | /* |
1da177e4 LT |
621 | * cap_emulate_setxuid() fixes the effective / permitted capabilities of |
622 | * a process after a call to setuid, setreuid, or setresuid. | |
623 | * | |
624 | * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of | |
625 | * {r,e,s}uid != 0, the permitted and effective capabilities are | |
626 | * cleared. | |
627 | * | |
628 | * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective | |
629 | * capabilities of the process are cleared. | |
630 | * | |
631 | * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective | |
632 | * capabilities are set to the permitted capabilities. | |
633 | * | |
a6f76f23 | 634 | * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should |
1da177e4 LT |
635 | * never happen. |
636 | * | |
a6f76f23 | 637 | * -astor |
1da177e4 LT |
638 | * |
639 | * cevans - New behaviour, Oct '99 | |
640 | * A process may, via prctl(), elect to keep its capabilities when it | |
641 | * calls setuid() and switches away from uid==0. Both permitted and | |
642 | * effective sets will be retained. | |
643 | * Without this change, it was impossible for a daemon to drop only some | |
644 | * of its privilege. The call to setuid(!=0) would drop all privileges! | |
645 | * Keeping uid 0 is not an option because uid 0 owns too many vital | |
646 | * files.. | |
647 | * Thanks to Olaf Kirch and Peter Benie for spotting this. | |
648 | */ | |
d84f4f99 | 649 | static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) |
1da177e4 | 650 | { |
d84f4f99 DH |
651 | if ((old->uid == 0 || old->euid == 0 || old->suid == 0) && |
652 | (new->uid != 0 && new->euid != 0 && new->suid != 0) && | |
3898b1b4 | 653 | !issecure(SECURE_KEEP_CAPS)) { |
d84f4f99 DH |
654 | cap_clear(new->cap_permitted); |
655 | cap_clear(new->cap_effective); | |
1da177e4 | 656 | } |
d84f4f99 DH |
657 | if (old->euid == 0 && new->euid != 0) |
658 | cap_clear(new->cap_effective); | |
659 | if (old->euid != 0 && new->euid == 0) | |
660 | new->cap_effective = new->cap_permitted; | |
1da177e4 LT |
661 | } |
662 | ||
1d045980 DH |
663 | /** |
664 | * cap_task_fix_setuid - Fix up the results of setuid() call | |
665 | * @new: The proposed credentials | |
666 | * @old: The current task's current credentials | |
667 | * @flags: Indications of what has changed | |
668 | * | |
669 | * Fix up the results of setuid() call before the credential changes are | |
670 | * actually applied, returning 0 to grant the changes, -ve to deny them. | |
671 | */ | |
d84f4f99 | 672 | int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) |
1da177e4 LT |
673 | { |
674 | switch (flags) { | |
675 | case LSM_SETID_RE: | |
676 | case LSM_SETID_ID: | |
677 | case LSM_SETID_RES: | |
1d045980 DH |
678 | /* juggle the capabilities to follow [RES]UID changes unless |
679 | * otherwise suppressed */ | |
d84f4f99 DH |
680 | if (!issecure(SECURE_NO_SETUID_FIXUP)) |
681 | cap_emulate_setxuid(new, old); | |
1da177e4 | 682 | break; |
1da177e4 | 683 | |
1d045980 DH |
684 | case LSM_SETID_FS: |
685 | /* juggle the capabilties to follow FSUID changes, unless | |
686 | * otherwise suppressed | |
687 | * | |
d84f4f99 DH |
688 | * FIXME - is fsuser used for all CAP_FS_MASK capabilities? |
689 | * if not, we might be a bit too harsh here. | |
690 | */ | |
691 | if (!issecure(SECURE_NO_SETUID_FIXUP)) { | |
1d045980 | 692 | if (old->fsuid == 0 && new->fsuid != 0) |
d84f4f99 DH |
693 | new->cap_effective = |
694 | cap_drop_fs_set(new->cap_effective); | |
1d045980 DH |
695 | |
696 | if (old->fsuid != 0 && new->fsuid == 0) | |
d84f4f99 DH |
697 | new->cap_effective = |
698 | cap_raise_fs_set(new->cap_effective, | |
699 | new->cap_permitted); | |
1da177e4 | 700 | } |
d84f4f99 | 701 | break; |
1d045980 | 702 | |
1da177e4 LT |
703 | default: |
704 | return -EINVAL; | |
705 | } | |
706 | ||
707 | return 0; | |
708 | } | |
709 | ||
b5376771 SH |
710 | #ifdef CONFIG_SECURITY_FILE_CAPABILITIES |
711 | /* | |
712 | * Rationale: code calling task_setscheduler, task_setioprio, and | |
713 | * task_setnice, assumes that | |
714 | * . if capable(cap_sys_nice), then those actions should be allowed | |
715 | * . if not capable(cap_sys_nice), but acting on your own processes, | |
716 | * then those actions should be allowed | |
717 | * This is insufficient now since you can call code without suid, but | |
718 | * yet with increased caps. | |
719 | * So we check for increased caps on the target process. | |
720 | */ | |
de45e806 | 721 | static int cap_safe_nice(struct task_struct *p) |
b5376771 | 722 | { |
c69e8d9c DH |
723 | int is_subset; |
724 | ||
725 | rcu_read_lock(); | |
726 | is_subset = cap_issubset(__task_cred(p)->cap_permitted, | |
727 | current_cred()->cap_permitted); | |
728 | rcu_read_unlock(); | |
729 | ||
730 | if (!is_subset && !capable(CAP_SYS_NICE)) | |
b5376771 SH |
731 | return -EPERM; |
732 | return 0; | |
733 | } | |
734 | ||
1d045980 DH |
735 | /** |
736 | * cap_task_setscheduler - Detemine if scheduler policy change is permitted | |
737 | * @p: The task to affect | |
738 | * @policy: The policy to effect | |
739 | * @lp: The parameters to the scheduling policy | |
740 | * | |
741 | * Detemine if the requested scheduler policy change is permitted for the | |
742 | * specified task, returning 0 if permission is granted, -ve if denied. | |
743 | */ | |
744 | int cap_task_setscheduler(struct task_struct *p, int policy, | |
b5376771 SH |
745 | struct sched_param *lp) |
746 | { | |
747 | return cap_safe_nice(p); | |
748 | } | |
749 | ||
1d045980 DH |
750 | /** |
751 | * cap_task_ioprio - Detemine if I/O priority change is permitted | |
752 | * @p: The task to affect | |
753 | * @ioprio: The I/O priority to set | |
754 | * | |
755 | * Detemine if the requested I/O priority change is permitted for the specified | |
756 | * task, returning 0 if permission is granted, -ve if denied. | |
757 | */ | |
758 | int cap_task_setioprio(struct task_struct *p, int ioprio) | |
b5376771 SH |
759 | { |
760 | return cap_safe_nice(p); | |
761 | } | |
762 | ||
1d045980 DH |
763 | /** |
764 | * cap_task_ioprio - Detemine if task priority change is permitted | |
765 | * @p: The task to affect | |
766 | * @nice: The nice value to set | |
767 | * | |
768 | * Detemine if the requested task priority change is permitted for the | |
769 | * specified task, returning 0 if permission is granted, -ve if denied. | |
770 | */ | |
771 | int cap_task_setnice(struct task_struct *p, int nice) | |
b5376771 SH |
772 | { |
773 | return cap_safe_nice(p); | |
774 | } | |
775 | ||
3b7391de | 776 | /* |
1d045980 DH |
777 | * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from |
778 | * the current task's bounding set. Returns 0 on success, -ve on error. | |
3b7391de | 779 | */ |
d84f4f99 | 780 | static long cap_prctl_drop(struct cred *new, unsigned long cap) |
3b7391de SH |
781 | { |
782 | if (!capable(CAP_SETPCAP)) | |
783 | return -EPERM; | |
784 | if (!cap_valid(cap)) | |
785 | return -EINVAL; | |
d84f4f99 DH |
786 | |
787 | cap_lower(new->cap_bset, cap); | |
3b7391de SH |
788 | return 0; |
789 | } | |
3898b1b4 | 790 | |
b5376771 SH |
791 | #else |
792 | int cap_task_setscheduler (struct task_struct *p, int policy, | |
793 | struct sched_param *lp) | |
794 | { | |
795 | return 0; | |
796 | } | |
797 | int cap_task_setioprio (struct task_struct *p, int ioprio) | |
798 | { | |
799 | return 0; | |
800 | } | |
801 | int cap_task_setnice (struct task_struct *p, int nice) | |
802 | { | |
803 | return 0; | |
804 | } | |
b5376771 SH |
805 | #endif |
806 | ||
1d045980 DH |
807 | /** |
808 | * cap_task_prctl - Implement process control functions for this security module | |
809 | * @option: The process control function requested | |
810 | * @arg2, @arg3, @arg4, @arg5: The argument data for this function | |
811 | * | |
812 | * Allow process control functions (sys_prctl()) to alter capabilities; may | |
813 | * also deny access to other functions not otherwise implemented here. | |
814 | * | |
815 | * Returns 0 or +ve on success, -ENOSYS if this function is not implemented | |
816 | * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM | |
817 | * modules will consider performing the function. | |
818 | */ | |
3898b1b4 | 819 | int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, |
d84f4f99 | 820 | unsigned long arg4, unsigned long arg5) |
3898b1b4 | 821 | { |
d84f4f99 | 822 | struct cred *new; |
3898b1b4 AM |
823 | long error = 0; |
824 | ||
d84f4f99 DH |
825 | new = prepare_creds(); |
826 | if (!new) | |
827 | return -ENOMEM; | |
828 | ||
3898b1b4 AM |
829 | switch (option) { |
830 | case PR_CAPBSET_READ: | |
d84f4f99 | 831 | error = -EINVAL; |
3898b1b4 | 832 | if (!cap_valid(arg2)) |
d84f4f99 DH |
833 | goto error; |
834 | error = !!cap_raised(new->cap_bset, arg2); | |
835 | goto no_change; | |
836 | ||
3898b1b4 AM |
837 | #ifdef CONFIG_SECURITY_FILE_CAPABILITIES |
838 | case PR_CAPBSET_DROP: | |
d84f4f99 DH |
839 | error = cap_prctl_drop(new, arg2); |
840 | if (error < 0) | |
841 | goto error; | |
842 | goto changed; | |
3898b1b4 AM |
843 | |
844 | /* | |
845 | * The next four prctl's remain to assist with transitioning a | |
846 | * system from legacy UID=0 based privilege (when filesystem | |
847 | * capabilities are not in use) to a system using filesystem | |
848 | * capabilities only - as the POSIX.1e draft intended. | |
849 | * | |
850 | * Note: | |
851 | * | |
852 | * PR_SET_SECUREBITS = | |
853 | * issecure_mask(SECURE_KEEP_CAPS_LOCKED) | |
854 | * | issecure_mask(SECURE_NOROOT) | |
855 | * | issecure_mask(SECURE_NOROOT_LOCKED) | |
856 | * | issecure_mask(SECURE_NO_SETUID_FIXUP) | |
857 | * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED) | |
858 | * | |
859 | * will ensure that the current process and all of its | |
860 | * children will be locked into a pure | |
861 | * capability-based-privilege environment. | |
862 | */ | |
863 | case PR_SET_SECUREBITS: | |
d84f4f99 DH |
864 | error = -EPERM; |
865 | if ((((new->securebits & SECURE_ALL_LOCKS) >> 1) | |
866 | & (new->securebits ^ arg2)) /*[1]*/ | |
867 | || ((new->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ | |
868 | || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ | |
3699c53c DH |
869 | || (cap_capable(current, current_cred(), CAP_SETPCAP, |
870 | SECURITY_CAP_AUDIT) != 0) /*[4]*/ | |
3898b1b4 AM |
871 | /* |
872 | * [1] no changing of bits that are locked | |
873 | * [2] no unlocking of locks | |
874 | * [3] no setting of unsupported bits | |
875 | * [4] doing anything requires privilege (go read about | |
876 | * the "sendmail capabilities bug") | |
877 | */ | |
d84f4f99 DH |
878 | ) |
879 | /* cannot change a locked bit */ | |
880 | goto error; | |
881 | new->securebits = arg2; | |
882 | goto changed; | |
883 | ||
3898b1b4 | 884 | case PR_GET_SECUREBITS: |
d84f4f99 DH |
885 | error = new->securebits; |
886 | goto no_change; | |
3898b1b4 AM |
887 | |
888 | #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */ | |
889 | ||
890 | case PR_GET_KEEPCAPS: | |
891 | if (issecure(SECURE_KEEP_CAPS)) | |
892 | error = 1; | |
d84f4f99 DH |
893 | goto no_change; |
894 | ||
3898b1b4 | 895 | case PR_SET_KEEPCAPS: |
d84f4f99 | 896 | error = -EINVAL; |
3898b1b4 | 897 | if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */ |
d84f4f99 DH |
898 | goto error; |
899 | error = -EPERM; | |
900 | if (issecure(SECURE_KEEP_CAPS_LOCKED)) | |
901 | goto error; | |
902 | if (arg2) | |
903 | new->securebits |= issecure_mask(SECURE_KEEP_CAPS); | |
3898b1b4 | 904 | else |
d84f4f99 DH |
905 | new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
906 | goto changed; | |
3898b1b4 AM |
907 | |
908 | default: | |
909 | /* No functionality available - continue with default */ | |
d84f4f99 DH |
910 | error = -ENOSYS; |
911 | goto error; | |
3898b1b4 AM |
912 | } |
913 | ||
914 | /* Functionality provided */ | |
d84f4f99 DH |
915 | changed: |
916 | return commit_creds(new); | |
917 | ||
918 | no_change: | |
919 | error = 0; | |
920 | error: | |
921 | abort_creds(new); | |
922 | return error; | |
1da177e4 LT |
923 | } |
924 | ||
1d045980 DH |
925 | /** |
926 | * cap_syslog - Determine whether syslog function is permitted | |
927 | * @type: Function requested | |
928 | * | |
929 | * Determine whether the current process is permitted to use a particular | |
930 | * syslog function, returning 0 if permission is granted, -ve if not. | |
931 | */ | |
932 | int cap_syslog(int type) | |
1da177e4 LT |
933 | { |
934 | if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN)) | |
935 | return -EPERM; | |
936 | return 0; | |
937 | } | |
938 | ||
1d045980 DH |
939 | /** |
940 | * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted | |
941 | * @mm: The VM space in which the new mapping is to be made | |
942 | * @pages: The size of the mapping | |
943 | * | |
944 | * Determine whether the allocation of a new virtual mapping by the current | |
945 | * task is permitted, returning 0 if permission is granted, -ve if not. | |
946 | */ | |
34b4e4aa | 947 | int cap_vm_enough_memory(struct mm_struct *mm, long pages) |
1da177e4 LT |
948 | { |
949 | int cap_sys_admin = 0; | |
950 | ||
3699c53c DH |
951 | if (cap_capable(current, current_cred(), CAP_SYS_ADMIN, |
952 | SECURITY_CAP_NOAUDIT) == 0) | |
1da177e4 | 953 | cap_sys_admin = 1; |
34b4e4aa | 954 | return __vm_enough_memory(mm, pages, cap_sys_admin); |
1da177e4 | 955 | } |