SELinux: call cap_file_mmap in selinux_file_mmap
[linux-2.6-block.git] / security / commoncap.c
CommitLineData
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
b5f22a59
SH
31/*
32 * If a non-root user executes a setuid-root binary in
33 * !secure(SECURE_NOROOT) mode, then we raise capabilities.
34 * However if fE is also set, then the intent is for only
35 * the file capabilities to be applied, and the setuid-root
36 * bit is left on either to change the uid (plausible) or
37 * to get full privilege on a kernel without file capabilities
38 * support. So in that case we do not raise capabilities.
39 *
40 * Warn if that happens, once per boot.
41 */
42static void warn_setuid_and_fcaps_mixed(char *fname)
43{
44 static int warned;
45 if (!warned) {
46 printk(KERN_INFO "warning: `%s' has both setuid-root and"
47 " effective capabilities. Therefore not raising all"
48 " capabilities.\n", fname);
49 warned = 1;
50 }
51}
52
1da177e4
LT
53int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
54{
b6dff3ec 55 NETLINK_CB(skb).eff_cap = current_cap();
1da177e4
LT
56 return 0;
57}
58
c7bdb545 59int cap_netlink_recv(struct sk_buff *skb, int cap)
1da177e4 60{
c7bdb545 61 if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))
1da177e4
LT
62 return -EPERM;
63 return 0;
64}
1da177e4
LT
65EXPORT_SYMBOL(cap_netlink_recv);
66
1d045980
DH
67/**
68 * cap_capable - Determine whether a task has a particular effective capability
69 * @tsk: The task to query
3699c53c 70 * @cred: The credentials to use
1d045980
DH
71 * @cap: The capability to check for
72 * @audit: Whether to write an audit message or not
73 *
74 * Determine whether the nominated task has the specified capability amongst
75 * its effective set, returning 0 if it does, -ve if it does not.
76 *
3699c53c
DH
77 * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
78 * and has_capability() functions. That is, it has the reverse semantics:
79 * cap_has_capability() returns 0 when a task has a capability, but the
80 * kernel's capable() and has_capability() returns 1 for this case.
a6dbb1ef 81 */
3699c53c
DH
82int cap_capable(struct task_struct *tsk, const struct cred *cred, int cap,
83 int audit)
1da177e4 84{
3699c53c 85 return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
1da177e4
LT
86}
87
1d045980
DH
88/**
89 * cap_settime - Determine whether the current process may set the system clock
90 * @ts: The time to set
91 * @tz: The timezone to set
92 *
93 * Determine whether the current process may set the system clock and timezone
94 * information, returning 0 if permission granted, -ve if denied.
95 */
1da177e4
LT
96int cap_settime(struct timespec *ts, struct timezone *tz)
97{
98 if (!capable(CAP_SYS_TIME))
99 return -EPERM;
100 return 0;
101}
102
1d045980 103/**
9e48858f 104 * cap_ptrace_access_check - Determine whether the current process may access
1d045980
DH
105 * another
106 * @child: The process to be accessed
107 * @mode: The mode of attachment.
108 *
109 * Determine whether a process may access another, returning 0 if permission
110 * granted, -ve if denied.
111 */
9e48858f 112int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
1da177e4 113{
c69e8d9c
DH
114 int ret = 0;
115
116 rcu_read_lock();
d84f4f99
DH
117 if (!cap_issubset(__task_cred(child)->cap_permitted,
118 current_cred()->cap_permitted) &&
c69e8d9c
DH
119 !capable(CAP_SYS_PTRACE))
120 ret = -EPERM;
121 rcu_read_unlock();
122 return ret;
5cd9c58f
DH
123}
124
1d045980
DH
125/**
126 * cap_ptrace_traceme - Determine whether another process may trace the current
127 * @parent: The task proposed to be the tracer
128 *
129 * Determine whether the nominated task is permitted to trace the current
130 * process, returning 0 if permission is granted, -ve if denied.
131 */
5cd9c58f
DH
132int cap_ptrace_traceme(struct task_struct *parent)
133{
c69e8d9c
DH
134 int ret = 0;
135
136 rcu_read_lock();
d84f4f99
DH
137 if (!cap_issubset(current_cred()->cap_permitted,
138 __task_cred(parent)->cap_permitted) &&
c69e8d9c
DH
139 !has_capability(parent, CAP_SYS_PTRACE))
140 ret = -EPERM;
141 rcu_read_unlock();
142 return ret;
1da177e4
LT
143}
144
1d045980
DH
145/**
146 * cap_capget - Retrieve a task's capability sets
147 * @target: The task from which to retrieve the capability sets
148 * @effective: The place to record the effective set
149 * @inheritable: The place to record the inheritable set
150 * @permitted: The place to record the permitted set
151 *
152 * This function retrieves the capabilities of the nominated task and returns
153 * them to the caller.
154 */
155int cap_capget(struct task_struct *target, kernel_cap_t *effective,
156 kernel_cap_t *inheritable, kernel_cap_t *permitted)
1da177e4 157{
c69e8d9c 158 const struct cred *cred;
b6dff3ec 159
1da177e4 160 /* Derived from kernel/capability.c:sys_capget. */
c69e8d9c
DH
161 rcu_read_lock();
162 cred = __task_cred(target);
b6dff3ec
DH
163 *effective = cred->cap_effective;
164 *inheritable = cred->cap_inheritable;
165 *permitted = cred->cap_permitted;
c69e8d9c 166 rcu_read_unlock();
1da177e4
LT
167 return 0;
168}
169
1d045980
DH
170/*
171 * Determine whether the inheritable capabilities are limited to the old
172 * permitted set. Returns 1 if they are limited, 0 if they are not.
173 */
72c2d582
AM
174static inline int cap_inh_is_capped(void)
175{
1d045980 176#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
72c2d582 177
1d045980
DH
178 /* they are so limited unless the current task has the CAP_SETPCAP
179 * capability
180 */
3699c53c
DH
181 if (cap_capable(current, current_cred(), CAP_SETPCAP,
182 SECURITY_CAP_AUDIT) == 0)
1d045980
DH
183 return 0;
184#endif
185 return 1;
1209726c 186}
72c2d582 187
1d045980
DH
188/**
189 * cap_capset - Validate and apply proposed changes to current's capabilities
190 * @new: The proposed new credentials; alterations should be made here
191 * @old: The current task's current credentials
192 * @effective: A pointer to the proposed new effective capabilities set
193 * @inheritable: A pointer to the proposed new inheritable capabilities set
194 * @permitted: A pointer to the proposed new permitted capabilities set
195 *
196 * This function validates and applies a proposed mass change to the current
197 * process's capability sets. The changes are made to the proposed new
198 * credentials, and assuming no error, will be committed by the caller of LSM.
199 */
d84f4f99
DH
200int cap_capset(struct cred *new,
201 const struct cred *old,
202 const kernel_cap_t *effective,
203 const kernel_cap_t *inheritable,
204 const kernel_cap_t *permitted)
1da177e4 205{
d84f4f99
DH
206 if (cap_inh_is_capped() &&
207 !cap_issubset(*inheritable,
208 cap_combine(old->cap_inheritable,
209 old->cap_permitted)))
72c2d582 210 /* incapable of using this inheritable set */
1da177e4 211 return -EPERM;
d84f4f99 212
3b7391de 213 if (!cap_issubset(*inheritable,
d84f4f99
DH
214 cap_combine(old->cap_inheritable,
215 old->cap_bset)))
3b7391de
SH
216 /* no new pI capabilities outside bounding set */
217 return -EPERM;
1da177e4
LT
218
219 /* verify restrictions on target's new Permitted set */
d84f4f99 220 if (!cap_issubset(*permitted, old->cap_permitted))
1da177e4 221 return -EPERM;
1da177e4
LT
222
223 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
d84f4f99 224 if (!cap_issubset(*effective, *permitted))
1da177e4 225 return -EPERM;
1da177e4 226
d84f4f99
DH
227 new->cap_effective = *effective;
228 new->cap_inheritable = *inheritable;
229 new->cap_permitted = *permitted;
1da177e4
LT
230 return 0;
231}
232
1d045980
DH
233/*
234 * Clear proposed capability sets for execve().
235 */
b5376771
SH
236static inline void bprm_clear_caps(struct linux_binprm *bprm)
237{
a6f76f23 238 cap_clear(bprm->cred->cap_permitted);
b5376771
SH
239 bprm->cap_effective = false;
240}
241
242#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
243
1d045980
DH
244/**
245 * cap_inode_need_killpriv - Determine if inode change affects privileges
246 * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
247 *
248 * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
249 * affects the security markings on that inode, and if it is, should
250 * inode_killpriv() be invoked or the change rejected?
251 *
252 * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and
253 * -ve to deny the change.
254 */
b5376771
SH
255int cap_inode_need_killpriv(struct dentry *dentry)
256{
257 struct inode *inode = dentry->d_inode;
258 int error;
259
acfa4380 260 if (!inode->i_op->getxattr)
b5376771
SH
261 return 0;
262
263 error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
264 if (error <= 0)
265 return 0;
266 return 1;
267}
268
1d045980
DH
269/**
270 * cap_inode_killpriv - Erase the security markings on an inode
271 * @dentry: The inode/dentry to alter
272 *
273 * Erase the privilege-enhancing security markings on an inode.
274 *
275 * Returns 0 if successful, -ve on error.
276 */
b5376771
SH
277int cap_inode_killpriv(struct dentry *dentry)
278{
279 struct inode *inode = dentry->d_inode;
280
acfa4380 281 if (!inode->i_op->removexattr)
b5376771
SH
282 return 0;
283
284 return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
285}
286
1d045980
DH
287/*
288 * Calculate the new process capability sets from the capability sets attached
289 * to a file.
290 */
c0b00441 291static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
a6f76f23
DH
292 struct linux_binprm *bprm,
293 bool *effective)
b5376771 294{
a6f76f23 295 struct cred *new = bprm->cred;
c0b00441
EP
296 unsigned i;
297 int ret = 0;
298
299 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
a6f76f23 300 *effective = true;
c0b00441
EP
301
302 CAP_FOR_EACH_U32(i) {
303 __u32 permitted = caps->permitted.cap[i];
304 __u32 inheritable = caps->inheritable.cap[i];
305
306 /*
307 * pP' = (X & fP) | (pI & fI)
308 */
a6f76f23
DH
309 new->cap_permitted.cap[i] =
310 (new->cap_bset.cap[i] & permitted) |
311 (new->cap_inheritable.cap[i] & inheritable);
c0b00441 312
a6f76f23
DH
313 if (permitted & ~new->cap_permitted.cap[i])
314 /* insufficient to execute correctly */
c0b00441 315 ret = -EPERM;
c0b00441
EP
316 }
317
318 /*
319 * For legacy apps, with no internal support for recognizing they
320 * do not have enough capabilities, we return an error if they are
321 * missing some "forced" (aka file-permitted) capabilities.
322 */
a6f76f23 323 return *effective ? ret : 0;
c0b00441
EP
324}
325
1d045980
DH
326/*
327 * Extract the on-exec-apply capability sets for an executable file.
328 */
c0b00441
EP
329int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
330{
331 struct inode *inode = dentry->d_inode;
b5376771 332 __u32 magic_etc;
e338d263 333 unsigned tocopy, i;
c0b00441
EP
334 int size;
335 struct vfs_cap_data caps;
336
337 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
338
acfa4380 339 if (!inode || !inode->i_op->getxattr)
c0b00441
EP
340 return -ENODATA;
341
342 size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
343 XATTR_CAPS_SZ);
a6f76f23 344 if (size == -ENODATA || size == -EOPNOTSUPP)
c0b00441
EP
345 /* no data, that's ok */
346 return -ENODATA;
c0b00441
EP
347 if (size < 0)
348 return size;
b5376771 349
e338d263 350 if (size < sizeof(magic_etc))
b5376771
SH
351 return -EINVAL;
352
c0b00441 353 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
b5376771 354
a6f76f23 355 switch (magic_etc & VFS_CAP_REVISION_MASK) {
e338d263
AM
356 case VFS_CAP_REVISION_1:
357 if (size != XATTR_CAPS_SZ_1)
358 return -EINVAL;
359 tocopy = VFS_CAP_U32_1;
360 break;
361 case VFS_CAP_REVISION_2:
362 if (size != XATTR_CAPS_SZ_2)
363 return -EINVAL;
364 tocopy = VFS_CAP_U32_2;
365 break;
b5376771
SH
366 default:
367 return -EINVAL;
368 }
e338d263 369
5459c164 370 CAP_FOR_EACH_U32(i) {
c0b00441
EP
371 if (i >= tocopy)
372 break;
373 cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
374 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
e338d263 375 }
a6f76f23 376
c0b00441 377 return 0;
b5376771
SH
378}
379
1d045980
DH
380/*
381 * Attempt to get the on-exec apply capability sets for an executable file from
382 * its xattrs and, if present, apply them to the proposed credentials being
383 * constructed by execve().
384 */
a6f76f23 385static int get_file_caps(struct linux_binprm *bprm, bool *effective)
b5376771
SH
386{
387 struct dentry *dentry;
388 int rc = 0;
c0b00441 389 struct cpu_vfs_cap_data vcaps;
b5376771 390
3318a386
SH
391 bprm_clear_caps(bprm);
392
1f29fae2
SH
393 if (!file_caps_enabled)
394 return 0;
395
3318a386 396 if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
b5376771 397 return 0;
b5376771
SH
398
399 dentry = dget(bprm->file->f_dentry);
b5376771 400
c0b00441
EP
401 rc = get_vfs_caps_from_disk(dentry, &vcaps);
402 if (rc < 0) {
403 if (rc == -EINVAL)
404 printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
405 __func__, rc, bprm->filename);
406 else if (rc == -ENODATA)
407 rc = 0;
b5376771
SH
408 goto out;
409 }
b5376771 410
a6f76f23
DH
411 rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective);
412 if (rc == -EINVAL)
413 printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
414 __func__, rc, bprm->filename);
b5376771
SH
415
416out:
417 dput(dentry);
418 if (rc)
419 bprm_clear_caps(bprm);
420
421 return rc;
422}
423
424#else
425int cap_inode_need_killpriv(struct dentry *dentry)
426{
427 return 0;
428}
429
430int cap_inode_killpriv(struct dentry *dentry)
431{
432 return 0;
433}
434
e50a906e
EP
435int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
436{
437 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
438 return -ENODATA;
439}
440
a6f76f23 441static inline int get_file_caps(struct linux_binprm *bprm, bool *effective)
b5376771
SH
442{
443 bprm_clear_caps(bprm);
444 return 0;
445}
446#endif
447
a6f76f23 448/*
1d045980
DH
449 * Determine whether a exec'ing process's new permitted capabilities should be
450 * limited to just what it already has.
451 *
452 * This prevents processes that are being ptraced from gaining access to
453 * CAP_SETPCAP, unless the process they're tracing already has it, and the
454 * binary they're executing has filecaps that elevate it.
455 *
456 * Returns 1 if they should be limited, 0 if they are not.
457 */
458static inline int cap_limit_ptraced_target(void)
459{
460#ifndef CONFIG_SECURITY_FILE_CAPABILITIES
461 if (capable(CAP_SETPCAP))
462 return 0;
463#endif
464 return 1;
465}
466
467/**
468 * cap_bprm_set_creds - Set up the proposed credentials for execve().
469 * @bprm: The execution parameters, including the proposed creds
470 *
471 * Set up the proposed credentials for a new execution context being
472 * constructed by execve(). The proposed creds in @bprm->cred is altered,
473 * which won't take effect immediately. Returns 0 if successful, -ve on error.
a6f76f23
DH
474 */
475int cap_bprm_set_creds(struct linux_binprm *bprm)
1da177e4 476{
a6f76f23
DH
477 const struct cred *old = current_cred();
478 struct cred *new = bprm->cred;
479 bool effective;
b5376771 480 int ret;
1da177e4 481
a6f76f23
DH
482 effective = false;
483 ret = get_file_caps(bprm, &effective);
484 if (ret < 0)
485 return ret;
1da177e4 486
5459c164 487 if (!issecure(SECURE_NOROOT)) {
b5f22a59
SH
488 /*
489 * If the legacy file capability is set, then don't set privs
490 * for a setuid root binary run by a non-root user. Do set it
491 * for a root user just to cause least surprise to an admin.
492 */
493 if (effective && new->uid != 0 && new->euid == 0) {
494 warn_setuid_and_fcaps_mixed(bprm->filename);
495 goto skip;
496 }
5459c164
AM
497 /*
498 * To support inheritance of root-permissions and suid-root
499 * executables under compatibility mode, we override the
500 * capability sets for the file.
501 *
a6f76f23 502 * If only the real uid is 0, we do not set the effective bit.
5459c164 503 */
a6f76f23 504 if (new->euid == 0 || new->uid == 0) {
5459c164 505 /* pP' = (cap_bset & ~0) | (pI & ~0) */
a6f76f23
DH
506 new->cap_permitted = cap_combine(old->cap_bset,
507 old->cap_inheritable);
1da177e4 508 }
a6f76f23
DH
509 if (new->euid == 0)
510 effective = true;
1da177e4 511 }
b5f22a59 512skip:
b5376771 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 }
a6f76f23
DH
526 if (cap_limit_ptraced_target())
527 new->cap_permitted = cap_intersect(new->cap_permitted,
528 old->cap_permitted);
1da177e4
LT
529 }
530
a6f76f23
DH
531 new->suid = new->fsuid = new->euid;
532 new->sgid = new->fsgid = new->egid;
1da177e4 533
a6f76f23
DH
534 /* For init, we want to retain the capabilities set in the initial
535 * task. Thus we skip the usual capability rules
536 */
b460cbc5 537 if (!is_global_init(current)) {
a6f76f23
DH
538 if (effective)
539 new->cap_effective = new->cap_permitted;
e338d263 540 else
d84f4f99 541 cap_clear(new->cap_effective);
1da177e4 542 }
a6f76f23 543 bprm->cap_effective = effective;
1da177e4 544
3fc689e9
EP
545 /*
546 * Audit candidate if current->cap_effective is set
547 *
548 * We do not bother to audit if 3 things are true:
549 * 1) cap_effective has all caps
550 * 2) we are root
551 * 3) root is supposed to have all caps (SECURE_NOROOT)
552 * Since this is just a normal root execing a process.
553 *
554 * Number 1 above might fail if you don't have a full bset, but I think
555 * that is interesting information to audit.
556 */
d84f4f99
DH
557 if (!cap_isclear(new->cap_effective)) {
558 if (!cap_issubset(CAP_FULL_SET, new->cap_effective) ||
a6f76f23
DH
559 new->euid != 0 || new->uid != 0 ||
560 issecure(SECURE_NOROOT)) {
561 ret = audit_log_bprm_fcaps(bprm, new, old);
562 if (ret < 0)
563 return ret;
564 }
3fc689e9 565 }
1da177e4 566
d84f4f99 567 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
a6f76f23 568 return 0;
1da177e4
LT
569}
570
1d045980
DH
571/**
572 * cap_bprm_secureexec - Determine whether a secure execution is required
573 * @bprm: The execution parameters
574 *
575 * Determine whether a secure execution is required, return 1 if it is, and 0
576 * if it is not.
577 *
578 * The credentials have been committed by this point, and so are no longer
579 * available through @bprm->cred.
a6f76f23
DH
580 */
581int cap_bprm_secureexec(struct linux_binprm *bprm)
1da177e4 582{
c69e8d9c 583 const struct cred *cred = current_cred();
b6dff3ec
DH
584
585 if (cred->uid != 0) {
b5376771
SH
586 if (bprm->cap_effective)
587 return 1;
a6f76f23 588 if (!cap_isclear(cred->cap_permitted))
b5376771
SH
589 return 1;
590 }
591
b6dff3ec
DH
592 return (cred->euid != cred->uid ||
593 cred->egid != cred->gid);
1da177e4
LT
594}
595
1d045980
DH
596/**
597 * cap_inode_setxattr - Determine whether an xattr may be altered
598 * @dentry: The inode/dentry being altered
599 * @name: The name of the xattr to be changed
600 * @value: The value that the xattr will be changed to
601 * @size: The size of value
602 * @flags: The replacement flag
603 *
604 * Determine whether an xattr may be altered or set on an inode, returning 0 if
605 * permission is granted, -ve if denied.
606 *
607 * This is used to make sure security xattrs don't get updated or set by those
608 * who aren't privileged to do so.
609 */
8f0cfa52
DH
610int cap_inode_setxattr(struct dentry *dentry, const char *name,
611 const void *value, size_t size, int flags)
1da177e4 612{
b5376771
SH
613 if (!strcmp(name, XATTR_NAME_CAPS)) {
614 if (!capable(CAP_SETFCAP))
615 return -EPERM;
616 return 0;
1d045980
DH
617 }
618
619 if (!strncmp(name, XATTR_SECURITY_PREFIX,
1da177e4
LT
620 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
621 !capable(CAP_SYS_ADMIN))
622 return -EPERM;
623 return 0;
624}
625
1d045980
DH
626/**
627 * cap_inode_removexattr - Determine whether an xattr may be removed
628 * @dentry: The inode/dentry being altered
629 * @name: The name of the xattr to be changed
630 *
631 * Determine whether an xattr may be removed from an inode, returning 0 if
632 * permission is granted, -ve if denied.
633 *
634 * This is used to make sure security xattrs don't get removed by those who
635 * aren't privileged to remove them.
636 */
8f0cfa52 637int cap_inode_removexattr(struct dentry *dentry, const char *name)
1da177e4 638{
b5376771
SH
639 if (!strcmp(name, XATTR_NAME_CAPS)) {
640 if (!capable(CAP_SETFCAP))
641 return -EPERM;
642 return 0;
1d045980
DH
643 }
644
645 if (!strncmp(name, XATTR_SECURITY_PREFIX,
1da177e4
LT
646 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
647 !capable(CAP_SYS_ADMIN))
648 return -EPERM;
649 return 0;
650}
651
a6f76f23 652/*
1da177e4
LT
653 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
654 * a process after a call to setuid, setreuid, or setresuid.
655 *
656 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
657 * {r,e,s}uid != 0, the permitted and effective capabilities are
658 * cleared.
659 *
660 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
661 * capabilities of the process are cleared.
662 *
663 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
664 * capabilities are set to the permitted capabilities.
665 *
a6f76f23 666 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
1da177e4
LT
667 * never happen.
668 *
a6f76f23 669 * -astor
1da177e4
LT
670 *
671 * cevans - New behaviour, Oct '99
672 * A process may, via prctl(), elect to keep its capabilities when it
673 * calls setuid() and switches away from uid==0. Both permitted and
674 * effective sets will be retained.
675 * Without this change, it was impossible for a daemon to drop only some
676 * of its privilege. The call to setuid(!=0) would drop all privileges!
677 * Keeping uid 0 is not an option because uid 0 owns too many vital
678 * files..
679 * Thanks to Olaf Kirch and Peter Benie for spotting this.
680 */
d84f4f99 681static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
1da177e4 682{
d84f4f99
DH
683 if ((old->uid == 0 || old->euid == 0 || old->suid == 0) &&
684 (new->uid != 0 && new->euid != 0 && new->suid != 0) &&
3898b1b4 685 !issecure(SECURE_KEEP_CAPS)) {
d84f4f99
DH
686 cap_clear(new->cap_permitted);
687 cap_clear(new->cap_effective);
1da177e4 688 }
d84f4f99
DH
689 if (old->euid == 0 && new->euid != 0)
690 cap_clear(new->cap_effective);
691 if (old->euid != 0 && new->euid == 0)
692 new->cap_effective = new->cap_permitted;
1da177e4
LT
693}
694
1d045980
DH
695/**
696 * cap_task_fix_setuid - Fix up the results of setuid() call
697 * @new: The proposed credentials
698 * @old: The current task's current credentials
699 * @flags: Indications of what has changed
700 *
701 * Fix up the results of setuid() call before the credential changes are
702 * actually applied, returning 0 to grant the changes, -ve to deny them.
703 */
d84f4f99 704int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
1da177e4
LT
705{
706 switch (flags) {
707 case LSM_SETID_RE:
708 case LSM_SETID_ID:
709 case LSM_SETID_RES:
1d045980
DH
710 /* juggle the capabilities to follow [RES]UID changes unless
711 * otherwise suppressed */
d84f4f99
DH
712 if (!issecure(SECURE_NO_SETUID_FIXUP))
713 cap_emulate_setxuid(new, old);
1da177e4 714 break;
1da177e4 715
1d045980
DH
716 case LSM_SETID_FS:
717 /* juggle the capabilties to follow FSUID changes, unless
718 * otherwise suppressed
719 *
d84f4f99
DH
720 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
721 * if not, we might be a bit too harsh here.
722 */
723 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
1d045980 724 if (old->fsuid == 0 && new->fsuid != 0)
d84f4f99
DH
725 new->cap_effective =
726 cap_drop_fs_set(new->cap_effective);
1d045980
DH
727
728 if (old->fsuid != 0 && new->fsuid == 0)
d84f4f99
DH
729 new->cap_effective =
730 cap_raise_fs_set(new->cap_effective,
731 new->cap_permitted);
1da177e4 732 }
d84f4f99 733 break;
1d045980 734
1da177e4
LT
735 default:
736 return -EINVAL;
737 }
738
739 return 0;
740}
741
b5376771
SH
742#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
743/*
744 * Rationale: code calling task_setscheduler, task_setioprio, and
745 * task_setnice, assumes that
746 * . if capable(cap_sys_nice), then those actions should be allowed
747 * . if not capable(cap_sys_nice), but acting on your own processes,
748 * then those actions should be allowed
749 * This is insufficient now since you can call code without suid, but
750 * yet with increased caps.
751 * So we check for increased caps on the target process.
752 */
de45e806 753static int cap_safe_nice(struct task_struct *p)
b5376771 754{
c69e8d9c
DH
755 int is_subset;
756
757 rcu_read_lock();
758 is_subset = cap_issubset(__task_cred(p)->cap_permitted,
759 current_cred()->cap_permitted);
760 rcu_read_unlock();
761
762 if (!is_subset && !capable(CAP_SYS_NICE))
b5376771
SH
763 return -EPERM;
764 return 0;
765}
766
1d045980
DH
767/**
768 * cap_task_setscheduler - Detemine if scheduler policy change is permitted
769 * @p: The task to affect
770 * @policy: The policy to effect
771 * @lp: The parameters to the scheduling policy
772 *
773 * Detemine if the requested scheduler policy change is permitted for the
774 * specified task, returning 0 if permission is granted, -ve if denied.
775 */
776int cap_task_setscheduler(struct task_struct *p, int policy,
b5376771
SH
777 struct sched_param *lp)
778{
779 return cap_safe_nice(p);
780}
781
1d045980
DH
782/**
783 * cap_task_ioprio - Detemine if I/O priority change is permitted
784 * @p: The task to affect
785 * @ioprio: The I/O priority to set
786 *
787 * Detemine if the requested I/O priority change is permitted for the specified
788 * task, returning 0 if permission is granted, -ve if denied.
789 */
790int cap_task_setioprio(struct task_struct *p, int ioprio)
b5376771
SH
791{
792 return cap_safe_nice(p);
793}
794
1d045980
DH
795/**
796 * cap_task_ioprio - Detemine if task priority change is permitted
797 * @p: The task to affect
798 * @nice: The nice value to set
799 *
800 * Detemine if the requested task priority change is permitted for the
801 * specified task, returning 0 if permission is granted, -ve if denied.
802 */
803int cap_task_setnice(struct task_struct *p, int nice)
b5376771
SH
804{
805 return cap_safe_nice(p);
806}
807
3b7391de 808/*
1d045980
DH
809 * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from
810 * the current task's bounding set. Returns 0 on success, -ve on error.
3b7391de 811 */
d84f4f99 812static long cap_prctl_drop(struct cred *new, unsigned long cap)
3b7391de
SH
813{
814 if (!capable(CAP_SETPCAP))
815 return -EPERM;
816 if (!cap_valid(cap))
817 return -EINVAL;
d84f4f99
DH
818
819 cap_lower(new->cap_bset, cap);
3b7391de
SH
820 return 0;
821}
3898b1b4 822
b5376771
SH
823#else
824int cap_task_setscheduler (struct task_struct *p, int policy,
825 struct sched_param *lp)
826{
827 return 0;
828}
829int cap_task_setioprio (struct task_struct *p, int ioprio)
830{
831 return 0;
832}
833int cap_task_setnice (struct task_struct *p, int nice)
834{
835 return 0;
836}
b5376771
SH
837#endif
838
1d045980
DH
839/**
840 * cap_task_prctl - Implement process control functions for this security module
841 * @option: The process control function requested
842 * @arg2, @arg3, @arg4, @arg5: The argument data for this function
843 *
844 * Allow process control functions (sys_prctl()) to alter capabilities; may
845 * also deny access to other functions not otherwise implemented here.
846 *
847 * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
848 * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM
849 * modules will consider performing the function.
850 */
3898b1b4 851int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
d84f4f99 852 unsigned long arg4, unsigned long arg5)
3898b1b4 853{
d84f4f99 854 struct cred *new;
3898b1b4
AM
855 long error = 0;
856
d84f4f99
DH
857 new = prepare_creds();
858 if (!new)
859 return -ENOMEM;
860
3898b1b4
AM
861 switch (option) {
862 case PR_CAPBSET_READ:
d84f4f99 863 error = -EINVAL;
3898b1b4 864 if (!cap_valid(arg2))
d84f4f99
DH
865 goto error;
866 error = !!cap_raised(new->cap_bset, arg2);
867 goto no_change;
868
3898b1b4
AM
869#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
870 case PR_CAPBSET_DROP:
d84f4f99
DH
871 error = cap_prctl_drop(new, arg2);
872 if (error < 0)
873 goto error;
874 goto changed;
3898b1b4
AM
875
876 /*
877 * The next four prctl's remain to assist with transitioning a
878 * system from legacy UID=0 based privilege (when filesystem
879 * capabilities are not in use) to a system using filesystem
880 * capabilities only - as the POSIX.1e draft intended.
881 *
882 * Note:
883 *
884 * PR_SET_SECUREBITS =
885 * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
886 * | issecure_mask(SECURE_NOROOT)
887 * | issecure_mask(SECURE_NOROOT_LOCKED)
888 * | issecure_mask(SECURE_NO_SETUID_FIXUP)
889 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
890 *
891 * will ensure that the current process and all of its
892 * children will be locked into a pure
893 * capability-based-privilege environment.
894 */
895 case PR_SET_SECUREBITS:
d84f4f99
DH
896 error = -EPERM;
897 if ((((new->securebits & SECURE_ALL_LOCKS) >> 1)
898 & (new->securebits ^ arg2)) /*[1]*/
899 || ((new->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/
900 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
3699c53c
DH
901 || (cap_capable(current, current_cred(), CAP_SETPCAP,
902 SECURITY_CAP_AUDIT) != 0) /*[4]*/
3898b1b4
AM
903 /*
904 * [1] no changing of bits that are locked
905 * [2] no unlocking of locks
906 * [3] no setting of unsupported bits
907 * [4] doing anything requires privilege (go read about
908 * the "sendmail capabilities bug")
909 */
d84f4f99
DH
910 )
911 /* cannot change a locked bit */
912 goto error;
913 new->securebits = arg2;
914 goto changed;
915
3898b1b4 916 case PR_GET_SECUREBITS:
d84f4f99
DH
917 error = new->securebits;
918 goto no_change;
3898b1b4
AM
919
920#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
921
922 case PR_GET_KEEPCAPS:
923 if (issecure(SECURE_KEEP_CAPS))
924 error = 1;
d84f4f99
DH
925 goto no_change;
926
3898b1b4 927 case PR_SET_KEEPCAPS:
d84f4f99 928 error = -EINVAL;
3898b1b4 929 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
d84f4f99
DH
930 goto error;
931 error = -EPERM;
932 if (issecure(SECURE_KEEP_CAPS_LOCKED))
933 goto error;
934 if (arg2)
935 new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
3898b1b4 936 else
d84f4f99
DH
937 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
938 goto changed;
3898b1b4
AM
939
940 default:
941 /* No functionality available - continue with default */
d84f4f99
DH
942 error = -ENOSYS;
943 goto error;
3898b1b4
AM
944 }
945
946 /* Functionality provided */
d84f4f99
DH
947changed:
948 return commit_creds(new);
949
950no_change:
d84f4f99
DH
951error:
952 abort_creds(new);
953 return error;
1da177e4
LT
954}
955
1d045980
DH
956/**
957 * cap_syslog - Determine whether syslog function is permitted
958 * @type: Function requested
959 *
960 * Determine whether the current process is permitted to use a particular
961 * syslog function, returning 0 if permission is granted, -ve if not.
962 */
963int cap_syslog(int type)
1da177e4
LT
964{
965 if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
966 return -EPERM;
967 return 0;
968}
969
1d045980
DH
970/**
971 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
972 * @mm: The VM space in which the new mapping is to be made
973 * @pages: The size of the mapping
974 *
975 * Determine whether the allocation of a new virtual mapping by the current
976 * task is permitted, returning 0 if permission is granted, -ve if not.
977 */
34b4e4aa 978int cap_vm_enough_memory(struct mm_struct *mm, long pages)
1da177e4
LT
979{
980 int cap_sys_admin = 0;
981
3699c53c
DH
982 if (cap_capable(current, current_cred(), CAP_SYS_ADMIN,
983 SECURITY_CAP_NOAUDIT) == 0)
1da177e4 984 cap_sys_admin = 1;
34b4e4aa 985 return __vm_enough_memory(mm, pages, cap_sys_admin);
1da177e4 986}
7c73875e
EP
987
988/*
989 * cap_file_mmap - check if able to map given addr
990 * @file: unused
991 * @reqprot: unused
992 * @prot: unused
993 * @flags: unused
994 * @addr: address attempting to be mapped
995 * @addr_only: unused
996 *
997 * If the process is attempting to map memory below mmap_min_addr they need
998 * CAP_SYS_RAWIO. The other parameters to this function are unused by the
999 * capability security module. Returns 0 if this mapping should be allowed
1000 * -EPERM if not.
1001 */
1002int cap_file_mmap(struct file *file, unsigned long reqprot,
1003 unsigned long prot, unsigned long flags,
1004 unsigned long addr, unsigned long addr_only)
1005{
1006 int ret = 0;
1007
1008 if (addr < mmap_min_addr) {
1009 ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO,
1010 SECURITY_CAP_AUDIT);
1011 /* set PF_SUPERPRIV if it turns out we allow the low mmap */
1012 if (ret == 0)
1013 current->flags |= PF_SUPERPRIV;
1014 }
1015 return ret;
1016}