blob: e4c4b3fc0c04e49e553610a8bd4d433e55e9212a [file] [log] [blame]
Andrew Morgane338d262008-02-04 22:29:42 -08001/* Common capabilities, needed by capability.o and root_plug.o
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 *
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
Randy.Dunlapc59ede72006-01-11 12:17:46 -080010#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/skbuff.h>
21#include <linux/netlink.h>
22#include <linux/ptrace.h>
23#include <linux/xattr.h>
24#include <linux/hugetlb.h>
Serge E. Hallynb5376772007-10-16 23:31:36 -070025#include <linux/mount.h>
Serge E. Hallynb460cbc2007-10-18 23:39:52 -070026#include <linux/sched.h>
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -070027#include <linux/prctl.h>
28#include <linux/securebits.h>
Andrew Morgan72c2d582007-10-18 03:05:59 -070029
Linus Torvalds1da177e2005-04-16 15:20:36 -070030int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
31{
32 NETLINK_CB(skb).eff_cap = current->cap_effective;
33 return 0;
34}
35
Darrel Goeddelc7bdb542006-06-27 13:26:11 -070036int cap_netlink_recv(struct sk_buff *skb, int cap)
Linus Torvalds1da177e2005-04-16 15:20:36 -070037{
Darrel Goeddelc7bdb542006-06-27 13:26:11 -070038 if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 return -EPERM;
40 return 0;
41}
42
43EXPORT_SYMBOL(cap_netlink_recv);
44
Andrew G. Morgana6dbb1e2008-01-21 17:18:30 -080045/*
46 * NOTE WELL: cap_capable() cannot be used like the kernel's capable()
47 * function. That is, it has the reverse semantics: cap_capable()
48 * returns 0 when a task has a capability, but the kernel's capable()
49 * returns 1 for this case.
50 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070051int cap_capable (struct task_struct *tsk, int cap)
52{
53 /* Derived from include/linux/sched.h:capable. */
54 if (cap_raised(tsk->cap_effective, cap))
55 return 0;
56 return -EPERM;
57}
58
59int cap_settime(struct timespec *ts, struct timezone *tz)
60{
61 if (!capable(CAP_SYS_TIME))
62 return -EPERM;
63 return 0;
64}
65
David Howells5cd9c582008-08-14 11:37:28 +010066int cap_ptrace_may_access(struct task_struct *child, unsigned int mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -070067{
68 /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
David Howells5cd9c582008-08-14 11:37:28 +010069 if (cap_issubset(child->cap_permitted, current->cap_permitted))
70 return 0;
71 if (capable(CAP_SYS_PTRACE))
72 return 0;
73 return -EPERM;
74}
75
76int cap_ptrace_traceme(struct task_struct *parent)
77{
78 /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
79 if (cap_issubset(current->cap_permitted, parent->cap_permitted))
80 return 0;
81 if (has_capability(parent, CAP_SYS_PTRACE))
82 return 0;
83 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -070084}
85
86int cap_capget (struct task_struct *target, kernel_cap_t *effective,
87 kernel_cap_t *inheritable, kernel_cap_t *permitted)
88{
89 /* Derived from kernel/capability.c:sys_capget. */
Andrew Morgane338d262008-02-04 22:29:42 -080090 *effective = target->cap_effective;
91 *inheritable = target->cap_inheritable;
92 *permitted = target->cap_permitted;
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 return 0;
94}
95
Andrew Morgan72c2d582007-10-18 03:05:59 -070096#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
97
98static inline int cap_block_setpcap(struct task_struct *target)
99{
100 /*
101 * No support for remote process capability manipulation with
102 * filesystem capability support.
103 */
104 return (target != current);
105}
106
107static inline int cap_inh_is_capped(void)
108{
109 /*
Andrew G. Morgana6dbb1e2008-01-21 17:18:30 -0800110 * Return 1 if changes to the inheritable set are limited
111 * to the old permitted set. That is, if the current task
112 * does *not* possess the CAP_SETPCAP capability.
Andrew Morgan72c2d582007-10-18 03:05:59 -0700113 */
Andrew G. Morgana6dbb1e2008-01-21 17:18:30 -0800114 return (cap_capable(current, CAP_SETPCAP) != 0);
Andrew Morgan72c2d582007-10-18 03:05:59 -0700115}
116
Andrew G. Morgan12097262008-07-04 09:59:59 -0700117static inline int cap_limit_ptraced_target(void) { return 1; }
118
Andrew Morgan72c2d582007-10-18 03:05:59 -0700119#else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
120
121static inline int cap_block_setpcap(struct task_struct *t) { return 0; }
122static inline int cap_inh_is_capped(void) { return 1; }
Andrew G. Morgan12097262008-07-04 09:59:59 -0700123static inline int cap_limit_ptraced_target(void)
124{
125 return !capable(CAP_SETPCAP);
126}
Andrew Morgan72c2d582007-10-18 03:05:59 -0700127
128#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
129
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
131 kernel_cap_t *inheritable, kernel_cap_t *permitted)
132{
Andrew Morgan72c2d582007-10-18 03:05:59 -0700133 if (cap_block_setpcap(target)) {
134 return -EPERM;
135 }
136 if (cap_inh_is_capped()
137 && !cap_issubset(*inheritable,
138 cap_combine(target->cap_inheritable,
139 current->cap_permitted))) {
140 /* incapable of using this inheritable set */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 return -EPERM;
142 }
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800143 if (!cap_issubset(*inheritable,
144 cap_combine(target->cap_inheritable,
145 current->cap_bset))) {
146 /* no new pI capabilities outside bounding set */
147 return -EPERM;
148 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149
150 /* verify restrictions on target's new Permitted set */
151 if (!cap_issubset (*permitted,
152 cap_combine (target->cap_permitted,
153 current->cap_permitted))) {
154 return -EPERM;
155 }
156
157 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
158 if (!cap_issubset (*effective, *permitted)) {
159 return -EPERM;
160 }
161
162 return 0;
163}
164
165void cap_capset_set (struct task_struct *target, kernel_cap_t *effective,
166 kernel_cap_t *inheritable, kernel_cap_t *permitted)
167{
168 target->cap_effective = *effective;
169 target->cap_inheritable = *inheritable;
170 target->cap_permitted = *permitted;
171}
172
Serge E. Hallynb5376772007-10-16 23:31:36 -0700173static inline void bprm_clear_caps(struct linux_binprm *bprm)
174{
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700175 cap_clear(bprm->cap_post_exec_permitted);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700176 bprm->cap_effective = false;
177}
178
179#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
180
181int cap_inode_need_killpriv(struct dentry *dentry)
182{
183 struct inode *inode = dentry->d_inode;
184 int error;
185
186 if (!inode->i_op || !inode->i_op->getxattr)
187 return 0;
188
189 error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
190 if (error <= 0)
191 return 0;
192 return 1;
193}
194
195int cap_inode_killpriv(struct dentry *dentry)
196{
197 struct inode *inode = dentry->d_inode;
198
199 if (!inode->i_op || !inode->i_op->removexattr)
200 return 0;
201
202 return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
203}
204
Andrew Morgane338d262008-02-04 22:29:42 -0800205static inline int cap_from_disk(struct vfs_cap_data *caps,
206 struct linux_binprm *bprm, unsigned size)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700207{
208 __u32 magic_etc;
Andrew Morgane338d262008-02-04 22:29:42 -0800209 unsigned tocopy, i;
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700210 int ret;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700211
Andrew Morgane338d262008-02-04 22:29:42 -0800212 if (size < sizeof(magic_etc))
Serge E. Hallynb5376772007-10-16 23:31:36 -0700213 return -EINVAL;
214
Andrew Morgane338d262008-02-04 22:29:42 -0800215 magic_etc = le32_to_cpu(caps->magic_etc);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700216
217 switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
Andrew Morgane338d262008-02-04 22:29:42 -0800218 case VFS_CAP_REVISION_1:
219 if (size != XATTR_CAPS_SZ_1)
220 return -EINVAL;
221 tocopy = VFS_CAP_U32_1;
222 break;
223 case VFS_CAP_REVISION_2:
224 if (size != XATTR_CAPS_SZ_2)
225 return -EINVAL;
226 tocopy = VFS_CAP_U32_2;
227 break;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700228 default:
229 return -EINVAL;
230 }
Andrew Morgane338d262008-02-04 22:29:42 -0800231
232 if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE) {
233 bprm->cap_effective = true;
234 } else {
235 bprm->cap_effective = false;
236 }
237
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700238 ret = 0;
239
240 CAP_FOR_EACH_U32(i) {
241 __u32 value_cpu;
242
243 if (i >= tocopy) {
244 /*
245 * Legacy capability sets have no upper bits
246 */
247 bprm->cap_post_exec_permitted.cap[i] = 0;
248 continue;
249 }
250 /*
251 * pP' = (X & fP) | (pI & fI)
252 */
253 value_cpu = le32_to_cpu(caps->data[i].permitted);
254 bprm->cap_post_exec_permitted.cap[i] =
255 (current->cap_bset.cap[i] & value_cpu) |
256 (current->cap_inheritable.cap[i] &
257 le32_to_cpu(caps->data[i].inheritable));
258 if (value_cpu & ~bprm->cap_post_exec_permitted.cap[i]) {
259 /*
260 * insufficient to execute correctly
261 */
262 ret = -EPERM;
263 }
Andrew Morgane338d262008-02-04 22:29:42 -0800264 }
265
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700266 /*
267 * For legacy apps, with no internal support for recognizing they
268 * do not have enough capabilities, we return an error if they are
269 * missing some "forced" (aka file-permitted) capabilities.
270 */
271 return bprm->cap_effective ? ret : 0;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700272}
273
274/* Locate any VFS capabilities: */
275static int get_file_caps(struct linux_binprm *bprm)
276{
277 struct dentry *dentry;
278 int rc = 0;
Andrew Morgane338d262008-02-04 22:29:42 -0800279 struct vfs_cap_data vcaps;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700280 struct inode *inode;
281
282 if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) {
283 bprm_clear_caps(bprm);
284 return 0;
285 }
286
287 dentry = dget(bprm->file->f_dentry);
288 inode = dentry->d_inode;
289 if (!inode->i_op || !inode->i_op->getxattr)
290 goto out;
291
Andrew Morgane338d262008-02-04 22:29:42 -0800292 rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &vcaps,
293 XATTR_CAPS_SZ);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700294 if (rc == -ENODATA || rc == -EOPNOTSUPP) {
295 /* no data, that's ok */
296 rc = 0;
297 goto out;
298 }
299 if (rc < 0)
300 goto out;
301
Andrew Morgane338d262008-02-04 22:29:42 -0800302 rc = cap_from_disk(&vcaps, bprm, rc);
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700303 if (rc == -EINVAL)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700304 printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700305 __func__, rc, bprm->filename);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700306
307out:
308 dput(dentry);
309 if (rc)
310 bprm_clear_caps(bprm);
311
312 return rc;
313}
314
315#else
316int cap_inode_need_killpriv(struct dentry *dentry)
317{
318 return 0;
319}
320
321int cap_inode_killpriv(struct dentry *dentry)
322{
323 return 0;
324}
325
326static inline int get_file_caps(struct linux_binprm *bprm)
327{
328 bprm_clear_caps(bprm);
329 return 0;
330}
331#endif
332
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333int cap_bprm_set_security (struct linux_binprm *bprm)
334{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700335 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336
Serge E. Hallynb5376772007-10-16 23:31:36 -0700337 ret = get_file_caps(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700339 if (!issecure(SECURE_NOROOT)) {
340 /*
341 * To support inheritance of root-permissions and suid-root
342 * executables under compatibility mode, we override the
343 * capability sets for the file.
344 *
345 * If only the real uid is 0, we do not set the effective
346 * bit.
347 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 if (bprm->e_uid == 0 || current->uid == 0) {
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700349 /* pP' = (cap_bset & ~0) | (pI & ~0) */
350 bprm->cap_post_exec_permitted = cap_combine(
351 current->cap_bset, current->cap_inheritable
352 );
353 bprm->cap_effective = (bprm->e_uid == 0);
354 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 }
Serge E. Hallynb5376772007-10-16 23:31:36 -0700357
358 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359}
360
361void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
362{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700364 !cap_issubset(bprm->cap_post_exec_permitted,
365 current->cap_permitted)) {
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -0700366 set_dumpable(current->mm, suid_dumpable);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700367 current->pdeath_signal = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368
369 if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
370 if (!capable(CAP_SETUID)) {
371 bprm->e_uid = current->uid;
372 bprm->e_gid = current->gid;
373 }
Andrew G. Morgan12097262008-07-04 09:59:59 -0700374 if (cap_limit_ptraced_target()) {
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700375 bprm->cap_post_exec_permitted = cap_intersect(
376 bprm->cap_post_exec_permitted,
377 current->cap_permitted);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 }
379 }
380 }
381
382 current->suid = current->euid = current->fsuid = bprm->e_uid;
383 current->sgid = current->egid = current->fsgid = bprm->e_gid;
384
385 /* For init, we want to retain the capabilities set
386 * in the init_task struct. Thus we skip the usual
387 * capability rules */
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700388 if (!is_global_init(current)) {
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700389 current->cap_permitted = bprm->cap_post_exec_permitted;
Andrew Morgane338d262008-02-04 22:29:42 -0800390 if (bprm->cap_effective)
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700391 current->cap_effective = bprm->cap_post_exec_permitted;
Andrew Morgane338d262008-02-04 22:29:42 -0800392 else
393 cap_clear(current->cap_effective);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 }
395
396 /* AUD: Audit candidate if current->cap_effective is set */
397
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700398 current->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399}
400
401int cap_bprm_secureexec (struct linux_binprm *bprm)
402{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700403 if (current->uid != 0) {
404 if (bprm->cap_effective)
405 return 1;
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700406 if (!cap_isclear(bprm->cap_post_exec_permitted))
Serge E. Hallynb5376772007-10-16 23:31:36 -0700407 return 1;
408 }
409
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 return (current->euid != current->uid ||
411 current->egid != current->gid);
412}
413
David Howells8f0cfa52008-04-29 00:59:41 -0700414int cap_inode_setxattr(struct dentry *dentry, const char *name,
415 const void *value, size_t size, int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700417 if (!strcmp(name, XATTR_NAME_CAPS)) {
418 if (!capable(CAP_SETFCAP))
419 return -EPERM;
420 return 0;
421 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
423 !capable(CAP_SYS_ADMIN))
424 return -EPERM;
425 return 0;
426}
427
David Howells8f0cfa52008-04-29 00:59:41 -0700428int cap_inode_removexattr(struct dentry *dentry, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700430 if (!strcmp(name, XATTR_NAME_CAPS)) {
431 if (!capable(CAP_SETFCAP))
432 return -EPERM;
433 return 0;
434 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
436 !capable(CAP_SYS_ADMIN))
437 return -EPERM;
438 return 0;
439}
440
441/* moved from kernel/sys.c. */
442/*
443 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
444 * a process after a call to setuid, setreuid, or setresuid.
445 *
446 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
447 * {r,e,s}uid != 0, the permitted and effective capabilities are
448 * cleared.
449 *
450 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
451 * capabilities of the process are cleared.
452 *
453 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
454 * capabilities are set to the permitted capabilities.
455 *
456 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
457 * never happen.
458 *
459 * -astor
460 *
461 * cevans - New behaviour, Oct '99
462 * A process may, via prctl(), elect to keep its capabilities when it
463 * calls setuid() and switches away from uid==0. Both permitted and
464 * effective sets will be retained.
465 * Without this change, it was impossible for a daemon to drop only some
466 * of its privilege. The call to setuid(!=0) would drop all privileges!
467 * Keeping uid 0 is not an option because uid 0 owns too many vital
468 * files..
469 * Thanks to Olaf Kirch and Peter Benie for spotting this.
470 */
471static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
472 int old_suid)
473{
474 if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
475 (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700476 !issecure(SECURE_KEEP_CAPS)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 cap_clear (current->cap_permitted);
478 cap_clear (current->cap_effective);
479 }
480 if (old_euid == 0 && current->euid != 0) {
481 cap_clear (current->cap_effective);
482 }
483 if (old_euid != 0 && current->euid == 0) {
484 current->cap_effective = current->cap_permitted;
485 }
486}
487
488int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
489 int flags)
490{
491 switch (flags) {
492 case LSM_SETID_RE:
493 case LSM_SETID_ID:
494 case LSM_SETID_RES:
495 /* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
496 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
497 cap_emulate_setxuid (old_ruid, old_euid, old_suid);
498 }
499 break;
500 case LSM_SETID_FS:
501 {
502 uid_t old_fsuid = old_ruid;
503
504 /* Copied from kernel/sys.c:setfsuid. */
505
506 /*
507 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
508 * if not, we might be a bit too harsh here.
509 */
510
511 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
512 if (old_fsuid == 0 && current->fsuid != 0) {
Andrew Morgane338d262008-02-04 22:29:42 -0800513 current->cap_effective =
514 cap_drop_fs_set(
515 current->cap_effective);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 }
517 if (old_fsuid != 0 && current->fsuid == 0) {
Andrew Morgane338d262008-02-04 22:29:42 -0800518 current->cap_effective =
519 cap_raise_fs_set(
520 current->cap_effective,
521 current->cap_permitted);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 }
523 }
524 break;
525 }
526 default:
527 return -EINVAL;
528 }
529
530 return 0;
531}
532
Serge E. Hallynb5376772007-10-16 23:31:36 -0700533#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
534/*
535 * Rationale: code calling task_setscheduler, task_setioprio, and
536 * task_setnice, assumes that
537 * . if capable(cap_sys_nice), then those actions should be allowed
538 * . if not capable(cap_sys_nice), but acting on your own processes,
539 * then those actions should be allowed
540 * This is insufficient now since you can call code without suid, but
541 * yet with increased caps.
542 * So we check for increased caps on the target process.
543 */
544static inline int cap_safe_nice(struct task_struct *p)
545{
546 if (!cap_issubset(p->cap_permitted, current->cap_permitted) &&
David Howells5cd9c582008-08-14 11:37:28 +0100547 !capable(CAP_SYS_NICE))
Serge E. Hallynb5376772007-10-16 23:31:36 -0700548 return -EPERM;
549 return 0;
550}
551
552int cap_task_setscheduler (struct task_struct *p, int policy,
553 struct sched_param *lp)
554{
555 return cap_safe_nice(p);
556}
557
558int cap_task_setioprio (struct task_struct *p, int ioprio)
559{
560 return cap_safe_nice(p);
561}
562
563int cap_task_setnice (struct task_struct *p, int nice)
564{
565 return cap_safe_nice(p);
566}
567
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800568/*
569 * called from kernel/sys.c for prctl(PR_CABSET_DROP)
570 * done without task_capability_lock() because it introduces
571 * no new races - i.e. only another task doing capget() on
572 * this task could get inconsistent info. There can be no
573 * racing writer bc a task can only change its own caps.
574 */
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700575static long cap_prctl_drop(unsigned long cap)
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800576{
577 if (!capable(CAP_SETPCAP))
578 return -EPERM;
579 if (!cap_valid(cap))
580 return -EINVAL;
581 cap_lower(current->cap_bset, cap);
582 return 0;
583}
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700584
Serge E. Hallynb5376772007-10-16 23:31:36 -0700585#else
586int cap_task_setscheduler (struct task_struct *p, int policy,
587 struct sched_param *lp)
588{
589 return 0;
590}
591int cap_task_setioprio (struct task_struct *p, int ioprio)
592{
593 return 0;
594}
595int cap_task_setnice (struct task_struct *p, int nice)
596{
597 return 0;
598}
Serge E. Hallynb5376772007-10-16 23:31:36 -0700599#endif
600
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700601int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
602 unsigned long arg4, unsigned long arg5, long *rc_p)
603{
604 long error = 0;
605
606 switch (option) {
607 case PR_CAPBSET_READ:
608 if (!cap_valid(arg2))
609 error = -EINVAL;
610 else
611 error = !!cap_raised(current->cap_bset, arg2);
612 break;
613#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
614 case PR_CAPBSET_DROP:
615 error = cap_prctl_drop(arg2);
616 break;
617
618 /*
619 * The next four prctl's remain to assist with transitioning a
620 * system from legacy UID=0 based privilege (when filesystem
621 * capabilities are not in use) to a system using filesystem
622 * capabilities only - as the POSIX.1e draft intended.
623 *
624 * Note:
625 *
626 * PR_SET_SECUREBITS =
627 * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
628 * | issecure_mask(SECURE_NOROOT)
629 * | issecure_mask(SECURE_NOROOT_LOCKED)
630 * | issecure_mask(SECURE_NO_SETUID_FIXUP)
631 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
632 *
633 * will ensure that the current process and all of its
634 * children will be locked into a pure
635 * capability-based-privilege environment.
636 */
637 case PR_SET_SECUREBITS:
638 if ((((current->securebits & SECURE_ALL_LOCKS) >> 1)
639 & (current->securebits ^ arg2)) /*[1]*/
640 || ((current->securebits & SECURE_ALL_LOCKS
641 & ~arg2)) /*[2]*/
642 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
643 || (cap_capable(current, CAP_SETPCAP) != 0)) { /*[4]*/
644 /*
645 * [1] no changing of bits that are locked
646 * [2] no unlocking of locks
647 * [3] no setting of unsupported bits
648 * [4] doing anything requires privilege (go read about
649 * the "sendmail capabilities bug")
650 */
651 error = -EPERM; /* cannot change a locked bit */
652 } else {
653 current->securebits = arg2;
654 }
655 break;
656 case PR_GET_SECUREBITS:
657 error = current->securebits;
658 break;
659
660#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
661
662 case PR_GET_KEEPCAPS:
663 if (issecure(SECURE_KEEP_CAPS))
664 error = 1;
665 break;
666 case PR_SET_KEEPCAPS:
667 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
668 error = -EINVAL;
669 else if (issecure(SECURE_KEEP_CAPS_LOCKED))
670 error = -EPERM;
671 else if (arg2)
672 current->securebits |= issecure_mask(SECURE_KEEP_CAPS);
673 else
674 current->securebits &=
675 ~issecure_mask(SECURE_KEEP_CAPS);
676 break;
677
678 default:
679 /* No functionality available - continue with default */
680 return 0;
681 }
682
683 /* Functionality provided */
684 *rc_p = error;
685 return 1;
686}
687
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688void cap_task_reparent_to_init (struct task_struct *p)
689{
Andrew Morgane338d262008-02-04 22:29:42 -0800690 cap_set_init_eff(p->cap_effective);
691 cap_clear(p->cap_inheritable);
692 cap_set_full(p->cap_permitted);
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700693 p->securebits = SECUREBITS_DEFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 return;
695}
696
697int cap_syslog (int type)
698{
699 if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
700 return -EPERM;
701 return 0;
702}
703
Alan Cox34b4e4a2007-08-22 14:01:28 -0700704int cap_vm_enough_memory(struct mm_struct *mm, long pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705{
706 int cap_sys_admin = 0;
707
708 if (cap_capable(current, CAP_SYS_ADMIN) == 0)
709 cap_sys_admin = 1;
Alan Cox34b4e4a2007-08-22 14:01:28 -0700710 return __vm_enough_memory(mm, pages, cap_sys_admin);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711}
712