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1da177e4 LT |
1 | /* Common capabilities, needed by capability.o and root_plug.o |
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> |
1da177e4 LT |
11 | #include <linux/module.h> |
12 | #include <linux/init.h> | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/security.h> | |
15 | #include <linux/file.h> | |
16 | #include <linux/mm.h> | |
17 | #include <linux/mman.h> | |
18 | #include <linux/pagemap.h> | |
19 | #include <linux/swap.h> | |
1da177e4 LT |
20 | #include <linux/skbuff.h> |
21 | #include <linux/netlink.h> | |
22 | #include <linux/ptrace.h> | |
23 | #include <linux/xattr.h> | |
24 | #include <linux/hugetlb.h> | |
b5376771 | 25 | #include <linux/mount.h> |
1da177e4 LT |
26 | |
27 | int cap_netlink_send(struct sock *sk, struct sk_buff *skb) | |
28 | { | |
29 | NETLINK_CB(skb).eff_cap = current->cap_effective; | |
30 | return 0; | |
31 | } | |
32 | ||
c7bdb545 | 33 | int cap_netlink_recv(struct sk_buff *skb, int cap) |
1da177e4 | 34 | { |
c7bdb545 | 35 | if (!cap_raised(NETLINK_CB(skb).eff_cap, cap)) |
1da177e4 LT |
36 | return -EPERM; |
37 | return 0; | |
38 | } | |
39 | ||
40 | EXPORT_SYMBOL(cap_netlink_recv); | |
41 | ||
42 | int cap_capable (struct task_struct *tsk, int cap) | |
43 | { | |
44 | /* Derived from include/linux/sched.h:capable. */ | |
45 | if (cap_raised(tsk->cap_effective, cap)) | |
46 | return 0; | |
47 | return -EPERM; | |
48 | } | |
49 | ||
50 | int cap_settime(struct timespec *ts, struct timezone *tz) | |
51 | { | |
52 | if (!capable(CAP_SYS_TIME)) | |
53 | return -EPERM; | |
54 | return 0; | |
55 | } | |
56 | ||
57 | int cap_ptrace (struct task_struct *parent, struct task_struct *child) | |
58 | { | |
59 | /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */ | |
d4eb82c7 CW |
60 | if (!cap_issubset(child->cap_permitted, parent->cap_permitted) && |
61 | !__capable(parent, CAP_SYS_PTRACE)) | |
1da177e4 LT |
62 | return -EPERM; |
63 | return 0; | |
64 | } | |
65 | ||
66 | int cap_capget (struct task_struct *target, kernel_cap_t *effective, | |
67 | kernel_cap_t *inheritable, kernel_cap_t *permitted) | |
68 | { | |
69 | /* Derived from kernel/capability.c:sys_capget. */ | |
70 | *effective = cap_t (target->cap_effective); | |
71 | *inheritable = cap_t (target->cap_inheritable); | |
72 | *permitted = cap_t (target->cap_permitted); | |
73 | return 0; | |
74 | } | |
75 | ||
76 | int cap_capset_check (struct task_struct *target, kernel_cap_t *effective, | |
77 | kernel_cap_t *inheritable, kernel_cap_t *permitted) | |
78 | { | |
79 | /* Derived from kernel/capability.c:sys_capset. */ | |
80 | /* verify restrictions on target's new Inheritable set */ | |
81 | if (!cap_issubset (*inheritable, | |
82 | cap_combine (target->cap_inheritable, | |
83 | current->cap_permitted))) { | |
84 | return -EPERM; | |
85 | } | |
86 | ||
87 | /* verify restrictions on target's new Permitted set */ | |
88 | if (!cap_issubset (*permitted, | |
89 | cap_combine (target->cap_permitted, | |
90 | current->cap_permitted))) { | |
91 | return -EPERM; | |
92 | } | |
93 | ||
94 | /* verify the _new_Effective_ is a subset of the _new_Permitted_ */ | |
95 | if (!cap_issubset (*effective, *permitted)) { | |
96 | return -EPERM; | |
97 | } | |
98 | ||
99 | return 0; | |
100 | } | |
101 | ||
102 | void cap_capset_set (struct task_struct *target, kernel_cap_t *effective, | |
103 | kernel_cap_t *inheritable, kernel_cap_t *permitted) | |
104 | { | |
105 | target->cap_effective = *effective; | |
106 | target->cap_inheritable = *inheritable; | |
107 | target->cap_permitted = *permitted; | |
108 | } | |
109 | ||
b5376771 SH |
110 | static inline void bprm_clear_caps(struct linux_binprm *bprm) |
111 | { | |
112 | cap_clear(bprm->cap_inheritable); | |
113 | cap_clear(bprm->cap_permitted); | |
114 | bprm->cap_effective = false; | |
115 | } | |
116 | ||
117 | #ifdef CONFIG_SECURITY_FILE_CAPABILITIES | |
118 | ||
119 | int cap_inode_need_killpriv(struct dentry *dentry) | |
120 | { | |
121 | struct inode *inode = dentry->d_inode; | |
122 | int error; | |
123 | ||
124 | if (!inode->i_op || !inode->i_op->getxattr) | |
125 | return 0; | |
126 | ||
127 | error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0); | |
128 | if (error <= 0) | |
129 | return 0; | |
130 | return 1; | |
131 | } | |
132 | ||
133 | int cap_inode_killpriv(struct dentry *dentry) | |
134 | { | |
135 | struct inode *inode = dentry->d_inode; | |
136 | ||
137 | if (!inode->i_op || !inode->i_op->removexattr) | |
138 | return 0; | |
139 | ||
140 | return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS); | |
141 | } | |
142 | ||
143 | static inline int cap_from_disk(__le32 *caps, struct linux_binprm *bprm, | |
144 | int size) | |
145 | { | |
146 | __u32 magic_etc; | |
147 | ||
148 | if (size != XATTR_CAPS_SZ) | |
149 | return -EINVAL; | |
150 | ||
151 | magic_etc = le32_to_cpu(caps[0]); | |
152 | ||
153 | switch ((magic_etc & VFS_CAP_REVISION_MASK)) { | |
154 | case VFS_CAP_REVISION: | |
155 | if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE) | |
156 | bprm->cap_effective = true; | |
157 | else | |
158 | bprm->cap_effective = false; | |
159 | bprm->cap_permitted = to_cap_t( le32_to_cpu(caps[1]) ); | |
160 | bprm->cap_inheritable = to_cap_t( le32_to_cpu(caps[2]) ); | |
161 | return 0; | |
162 | default: | |
163 | return -EINVAL; | |
164 | } | |
165 | } | |
166 | ||
167 | /* Locate any VFS capabilities: */ | |
168 | static int get_file_caps(struct linux_binprm *bprm) | |
169 | { | |
170 | struct dentry *dentry; | |
171 | int rc = 0; | |
172 | __le32 v1caps[XATTR_CAPS_SZ]; | |
173 | struct inode *inode; | |
174 | ||
175 | if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) { | |
176 | bprm_clear_caps(bprm); | |
177 | return 0; | |
178 | } | |
179 | ||
180 | dentry = dget(bprm->file->f_dentry); | |
181 | inode = dentry->d_inode; | |
182 | if (!inode->i_op || !inode->i_op->getxattr) | |
183 | goto out; | |
184 | ||
185 | rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &v1caps, | |
186 | XATTR_CAPS_SZ); | |
187 | if (rc == -ENODATA || rc == -EOPNOTSUPP) { | |
188 | /* no data, that's ok */ | |
189 | rc = 0; | |
190 | goto out; | |
191 | } | |
192 | if (rc < 0) | |
193 | goto out; | |
194 | ||
195 | rc = cap_from_disk(v1caps, bprm, rc); | |
196 | if (rc) | |
197 | printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", | |
198 | __FUNCTION__, rc, bprm->filename); | |
199 | ||
200 | out: | |
201 | dput(dentry); | |
202 | if (rc) | |
203 | bprm_clear_caps(bprm); | |
204 | ||
205 | return rc; | |
206 | } | |
207 | ||
208 | #else | |
209 | int cap_inode_need_killpriv(struct dentry *dentry) | |
210 | { | |
211 | return 0; | |
212 | } | |
213 | ||
214 | int cap_inode_killpriv(struct dentry *dentry) | |
215 | { | |
216 | return 0; | |
217 | } | |
218 | ||
219 | static inline int get_file_caps(struct linux_binprm *bprm) | |
220 | { | |
221 | bprm_clear_caps(bprm); | |
222 | return 0; | |
223 | } | |
224 | #endif | |
225 | ||
1da177e4 LT |
226 | int cap_bprm_set_security (struct linux_binprm *bprm) |
227 | { | |
b5376771 | 228 | int ret; |
1da177e4 | 229 | |
b5376771 SH |
230 | ret = get_file_caps(bprm); |
231 | if (ret) | |
232 | printk(KERN_NOTICE "%s: get_file_caps returned %d for %s\n", | |
233 | __FUNCTION__, ret, bprm->filename); | |
1da177e4 LT |
234 | |
235 | /* To support inheritance of root-permissions and suid-root | |
236 | * executables under compatibility mode, we raise all three | |
237 | * capability sets for the file. | |
238 | * | |
239 | * If only the real uid is 0, we only raise the inheritable | |
240 | * and permitted sets of the executable file. | |
241 | */ | |
242 | ||
243 | if (!issecure (SECURE_NOROOT)) { | |
244 | if (bprm->e_uid == 0 || current->uid == 0) { | |
245 | cap_set_full (bprm->cap_inheritable); | |
246 | cap_set_full (bprm->cap_permitted); | |
247 | } | |
248 | if (bprm->e_uid == 0) | |
b5376771 | 249 | bprm->cap_effective = true; |
1da177e4 | 250 | } |
b5376771 SH |
251 | |
252 | return ret; | |
1da177e4 LT |
253 | } |
254 | ||
255 | void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) | |
256 | { | |
257 | /* Derived from fs/exec.c:compute_creds. */ | |
258 | kernel_cap_t new_permitted, working; | |
259 | ||
260 | new_permitted = cap_intersect (bprm->cap_permitted, cap_bset); | |
261 | working = cap_intersect (bprm->cap_inheritable, | |
262 | current->cap_inheritable); | |
263 | new_permitted = cap_combine (new_permitted, working); | |
264 | ||
265 | if (bprm->e_uid != current->uid || bprm->e_gid != current->gid || | |
266 | !cap_issubset (new_permitted, current->cap_permitted)) { | |
6c5d5238 | 267 | set_dumpable(current->mm, suid_dumpable); |
b5376771 | 268 | current->pdeath_signal = 0; |
1da177e4 LT |
269 | |
270 | if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) { | |
271 | if (!capable(CAP_SETUID)) { | |
272 | bprm->e_uid = current->uid; | |
273 | bprm->e_gid = current->gid; | |
274 | } | |
275 | if (!capable (CAP_SETPCAP)) { | |
276 | new_permitted = cap_intersect (new_permitted, | |
277 | current->cap_permitted); | |
278 | } | |
279 | } | |
280 | } | |
281 | ||
282 | current->suid = current->euid = current->fsuid = bprm->e_uid; | |
283 | current->sgid = current->egid = current->fsgid = bprm->e_gid; | |
284 | ||
285 | /* For init, we want to retain the capabilities set | |
286 | * in the init_task struct. Thus we skip the usual | |
287 | * capability rules */ | |
f400e198 | 288 | if (!is_init(current)) { |
1da177e4 | 289 | current->cap_permitted = new_permitted; |
b5376771 SH |
290 | current->cap_effective = bprm->cap_effective ? |
291 | new_permitted : 0; | |
1da177e4 LT |
292 | } |
293 | ||
294 | /* AUD: Audit candidate if current->cap_effective is set */ | |
295 | ||
296 | current->keep_capabilities = 0; | |
297 | } | |
298 | ||
299 | int cap_bprm_secureexec (struct linux_binprm *bprm) | |
300 | { | |
b5376771 SH |
301 | if (current->uid != 0) { |
302 | if (bprm->cap_effective) | |
303 | return 1; | |
304 | if (!cap_isclear(bprm->cap_permitted)) | |
305 | return 1; | |
306 | if (!cap_isclear(bprm->cap_inheritable)) | |
307 | return 1; | |
308 | } | |
309 | ||
1da177e4 LT |
310 | return (current->euid != current->uid || |
311 | current->egid != current->gid); | |
312 | } | |
313 | ||
314 | int cap_inode_setxattr(struct dentry *dentry, char *name, void *value, | |
315 | size_t size, int flags) | |
316 | { | |
b5376771 SH |
317 | if (!strcmp(name, XATTR_NAME_CAPS)) { |
318 | if (!capable(CAP_SETFCAP)) | |
319 | return -EPERM; | |
320 | return 0; | |
321 | } else if (!strncmp(name, XATTR_SECURITY_PREFIX, | |
1da177e4 LT |
322 | sizeof(XATTR_SECURITY_PREFIX) - 1) && |
323 | !capable(CAP_SYS_ADMIN)) | |
324 | return -EPERM; | |
325 | return 0; | |
326 | } | |
327 | ||
328 | int cap_inode_removexattr(struct dentry *dentry, char *name) | |
329 | { | |
b5376771 SH |
330 | if (!strcmp(name, XATTR_NAME_CAPS)) { |
331 | if (!capable(CAP_SETFCAP)) | |
332 | return -EPERM; | |
333 | return 0; | |
334 | } else if (!strncmp(name, XATTR_SECURITY_PREFIX, | |
1da177e4 LT |
335 | sizeof(XATTR_SECURITY_PREFIX) - 1) && |
336 | !capable(CAP_SYS_ADMIN)) | |
337 | return -EPERM; | |
338 | return 0; | |
339 | } | |
340 | ||
341 | /* moved from kernel/sys.c. */ | |
342 | /* | |
343 | * cap_emulate_setxuid() fixes the effective / permitted capabilities of | |
344 | * a process after a call to setuid, setreuid, or setresuid. | |
345 | * | |
346 | * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of | |
347 | * {r,e,s}uid != 0, the permitted and effective capabilities are | |
348 | * cleared. | |
349 | * | |
350 | * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective | |
351 | * capabilities of the process are cleared. | |
352 | * | |
353 | * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective | |
354 | * capabilities are set to the permitted capabilities. | |
355 | * | |
356 | * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should | |
357 | * never happen. | |
358 | * | |
359 | * -astor | |
360 | * | |
361 | * cevans - New behaviour, Oct '99 | |
362 | * A process may, via prctl(), elect to keep its capabilities when it | |
363 | * calls setuid() and switches away from uid==0. Both permitted and | |
364 | * effective sets will be retained. | |
365 | * Without this change, it was impossible for a daemon to drop only some | |
366 | * of its privilege. The call to setuid(!=0) would drop all privileges! | |
367 | * Keeping uid 0 is not an option because uid 0 owns too many vital | |
368 | * files.. | |
369 | * Thanks to Olaf Kirch and Peter Benie for spotting this. | |
370 | */ | |
371 | static inline void cap_emulate_setxuid (int old_ruid, int old_euid, | |
372 | int old_suid) | |
373 | { | |
374 | if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) && | |
375 | (current->uid != 0 && current->euid != 0 && current->suid != 0) && | |
376 | !current->keep_capabilities) { | |
377 | cap_clear (current->cap_permitted); | |
378 | cap_clear (current->cap_effective); | |
379 | } | |
380 | if (old_euid == 0 && current->euid != 0) { | |
381 | cap_clear (current->cap_effective); | |
382 | } | |
383 | if (old_euid != 0 && current->euid == 0) { | |
384 | current->cap_effective = current->cap_permitted; | |
385 | } | |
386 | } | |
387 | ||
388 | int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid, | |
389 | int flags) | |
390 | { | |
391 | switch (flags) { | |
392 | case LSM_SETID_RE: | |
393 | case LSM_SETID_ID: | |
394 | case LSM_SETID_RES: | |
395 | /* Copied from kernel/sys.c:setreuid/setuid/setresuid. */ | |
396 | if (!issecure (SECURE_NO_SETUID_FIXUP)) { | |
397 | cap_emulate_setxuid (old_ruid, old_euid, old_suid); | |
398 | } | |
399 | break; | |
400 | case LSM_SETID_FS: | |
401 | { | |
402 | uid_t old_fsuid = old_ruid; | |
403 | ||
404 | /* Copied from kernel/sys.c:setfsuid. */ | |
405 | ||
406 | /* | |
407 | * FIXME - is fsuser used for all CAP_FS_MASK capabilities? | |
408 | * if not, we might be a bit too harsh here. | |
409 | */ | |
410 | ||
411 | if (!issecure (SECURE_NO_SETUID_FIXUP)) { | |
412 | if (old_fsuid == 0 && current->fsuid != 0) { | |
413 | cap_t (current->cap_effective) &= | |
414 | ~CAP_FS_MASK; | |
415 | } | |
416 | if (old_fsuid != 0 && current->fsuid == 0) { | |
417 | cap_t (current->cap_effective) |= | |
418 | (cap_t (current->cap_permitted) & | |
419 | CAP_FS_MASK); | |
420 | } | |
421 | } | |
422 | break; | |
423 | } | |
424 | default: | |
425 | return -EINVAL; | |
426 | } | |
427 | ||
428 | return 0; | |
429 | } | |
430 | ||
b5376771 SH |
431 | #ifdef CONFIG_SECURITY_FILE_CAPABILITIES |
432 | /* | |
433 | * Rationale: code calling task_setscheduler, task_setioprio, and | |
434 | * task_setnice, assumes that | |
435 | * . if capable(cap_sys_nice), then those actions should be allowed | |
436 | * . if not capable(cap_sys_nice), but acting on your own processes, | |
437 | * then those actions should be allowed | |
438 | * This is insufficient now since you can call code without suid, but | |
439 | * yet with increased caps. | |
440 | * So we check for increased caps on the target process. | |
441 | */ | |
442 | static inline int cap_safe_nice(struct task_struct *p) | |
443 | { | |
444 | if (!cap_issubset(p->cap_permitted, current->cap_permitted) && | |
445 | !__capable(current, CAP_SYS_NICE)) | |
446 | return -EPERM; | |
447 | return 0; | |
448 | } | |
449 | ||
450 | int cap_task_setscheduler (struct task_struct *p, int policy, | |
451 | struct sched_param *lp) | |
452 | { | |
453 | return cap_safe_nice(p); | |
454 | } | |
455 | ||
456 | int cap_task_setioprio (struct task_struct *p, int ioprio) | |
457 | { | |
458 | return cap_safe_nice(p); | |
459 | } | |
460 | ||
461 | int cap_task_setnice (struct task_struct *p, int nice) | |
462 | { | |
463 | return cap_safe_nice(p); | |
464 | } | |
465 | ||
466 | int cap_task_kill(struct task_struct *p, struct siginfo *info, | |
467 | int sig, u32 secid) | |
468 | { | |
469 | if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info))) | |
470 | return 0; | |
471 | ||
472 | if (secid) | |
473 | /* | |
474 | * Signal sent as a particular user. | |
475 | * Capabilities are ignored. May be wrong, but it's the | |
476 | * only thing we can do at the moment. | |
477 | * Used only by usb drivers? | |
478 | */ | |
479 | return 0; | |
480 | if (cap_issubset(p->cap_permitted, current->cap_permitted)) | |
481 | return 0; | |
482 | if (capable(CAP_KILL)) | |
483 | return 0; | |
484 | ||
485 | return -EPERM; | |
486 | } | |
487 | #else | |
488 | int cap_task_setscheduler (struct task_struct *p, int policy, | |
489 | struct sched_param *lp) | |
490 | { | |
491 | return 0; | |
492 | } | |
493 | int cap_task_setioprio (struct task_struct *p, int ioprio) | |
494 | { | |
495 | return 0; | |
496 | } | |
497 | int cap_task_setnice (struct task_struct *p, int nice) | |
498 | { | |
499 | return 0; | |
500 | } | |
501 | int cap_task_kill(struct task_struct *p, struct siginfo *info, | |
502 | int sig, u32 secid) | |
503 | { | |
504 | return 0; | |
505 | } | |
506 | #endif | |
507 | ||
1da177e4 LT |
508 | void cap_task_reparent_to_init (struct task_struct *p) |
509 | { | |
510 | p->cap_effective = CAP_INIT_EFF_SET; | |
511 | p->cap_inheritable = CAP_INIT_INH_SET; | |
512 | p->cap_permitted = CAP_FULL_SET; | |
513 | p->keep_capabilities = 0; | |
514 | return; | |
515 | } | |
516 | ||
517 | int cap_syslog (int type) | |
518 | { | |
519 | if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN)) | |
520 | return -EPERM; | |
521 | return 0; | |
522 | } | |
523 | ||
34b4e4aa | 524 | int cap_vm_enough_memory(struct mm_struct *mm, long pages) |
1da177e4 LT |
525 | { |
526 | int cap_sys_admin = 0; | |
527 | ||
528 | if (cap_capable(current, CAP_SYS_ADMIN) == 0) | |
529 | cap_sys_admin = 1; | |
34b4e4aa | 530 | return __vm_enough_memory(mm, pages, cap_sys_admin); |
1da177e4 LT |
531 | } |
532 |