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2874c5fd 1// SPDX-License-Identifier: GPL-2.0-or-later
3e1c2515 2/* Common capabilities, needed by capability.o.
1da177e4
LT
3 */
4
c59ede7b 5#include <linux/capability.h>
3fc689e9 6#include <linux/audit.h>
1da177e4
LT
7#include <linux/init.h>
8#include <linux/kernel.h>
b1d9e6b0 9#include <linux/lsm_hooks.h>
1da177e4
LT
10#include <linux/file.h>
11#include <linux/mm.h>
12#include <linux/mman.h>
13#include <linux/pagemap.h>
14#include <linux/swap.h>
1da177e4
LT
15#include <linux/skbuff.h>
16#include <linux/netlink.h>
17#include <linux/ptrace.h>
18#include <linux/xattr.h>
19#include <linux/hugetlb.h>
b5376771 20#include <linux/mount.h>
b460cbc5 21#include <linux/sched.h>
3898b1b4
AM
22#include <linux/prctl.h>
23#include <linux/securebits.h>
3486740a 24#include <linux/user_namespace.h>
40401530 25#include <linux/binfmts.h>
51b79bee 26#include <linux/personality.h>
72c2d582 27
b5f22a59
SH
28/*
29 * If a non-root user executes a setuid-root binary in
30 * !secure(SECURE_NOROOT) mode, then we raise capabilities.
31 * However if fE is also set, then the intent is for only
32 * the file capabilities to be applied, and the setuid-root
33 * bit is left on either to change the uid (plausible) or
34 * to get full privilege on a kernel without file capabilities
35 * support. So in that case we do not raise capabilities.
36 *
37 * Warn if that happens, once per boot.
38 */
d7627467 39static void warn_setuid_and_fcaps_mixed(const char *fname)
b5f22a59
SH
40{
41 static int warned;
42 if (!warned) {
43 printk(KERN_INFO "warning: `%s' has both setuid-root and"
44 " effective capabilities. Therefore not raising all"
45 " capabilities.\n", fname);
46 warned = 1;
47 }
48}
49
1d045980
DH
50/**
51 * cap_capable - Determine whether a task has a particular effective capability
3699c53c 52 * @cred: The credentials to use
3486740a 53 * @ns: The user namespace in which we need the capability
1d045980 54 * @cap: The capability to check for
e88ed488 55 * @opts: Bitmask of options defined in include/linux/security.h
1d045980
DH
56 *
57 * Determine whether the nominated task has the specified capability amongst
58 * its effective set, returning 0 if it does, -ve if it does not.
59 *
3699c53c
DH
60 * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
61 * and has_capability() functions. That is, it has the reverse semantics:
62 * cap_has_capability() returns 0 when a task has a capability, but the
63 * kernel's capable() and has_capability() returns 1 for this case.
a6dbb1ef 64 */
6a9de491 65int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
c1a85a00 66 int cap, unsigned int opts)
1da177e4 67{
520d9eab 68 struct user_namespace *ns = targ_ns;
3486740a 69
520d9eab
EB
70 /* See if cred has the capability in the target user namespace
71 * by examining the target user namespace and all of the target
72 * user namespace's parents.
73 */
74 for (;;) {
3486740a 75 /* Do we have the necessary capabilities? */
520d9eab 76 if (ns == cred->user_ns)
3486740a
SH
77 return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
78
64db4c7f
KT
79 /*
80 * If we're already at a lower level than we're looking for,
81 * we're done searching.
82 */
83 if (ns->level <= cred->user_ns->level)
3486740a
SH
84 return -EPERM;
85
520d9eab
EB
86 /*
87 * The owner of the user namespace in the parent of the
88 * user namespace has all caps.
89 */
90 if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
91 return 0;
92
3486740a 93 /*
520d9eab 94 * If you have a capability in a parent user ns, then you have
3486740a
SH
95 * it over all children user namespaces as well.
96 */
520d9eab 97 ns = ns->parent;
3486740a
SH
98 }
99
100 /* We never get here */
1da177e4
LT
101}
102
1d045980
DH
103/**
104 * cap_settime - Determine whether the current process may set the system clock
105 * @ts: The time to set
106 * @tz: The timezone to set
107 *
108 * Determine whether the current process may set the system clock and timezone
109 * information, returning 0 if permission granted, -ve if denied.
110 */
457db29b 111int cap_settime(const struct timespec64 *ts, const struct timezone *tz)
1da177e4
LT
112{
113 if (!capable(CAP_SYS_TIME))
114 return -EPERM;
115 return 0;
116}
117
1d045980 118/**
9e48858f 119 * cap_ptrace_access_check - Determine whether the current process may access
1d045980
DH
120 * another
121 * @child: The process to be accessed
122 * @mode: The mode of attachment.
123 *
8409cca7
SH
124 * If we are in the same or an ancestor user_ns and have all the target
125 * task's capabilities, then ptrace access is allowed.
126 * If we have the ptrace capability to the target user_ns, then ptrace
127 * access is allowed.
128 * Else denied.
129 *
1d045980
DH
130 * Determine whether a process may access another, returning 0 if permission
131 * granted, -ve if denied.
132 */
9e48858f 133int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
1da177e4 134{
c69e8d9c 135 int ret = 0;
8409cca7 136 const struct cred *cred, *child_cred;
caaee623 137 const kernel_cap_t *caller_caps;
c69e8d9c
DH
138
139 rcu_read_lock();
8409cca7
SH
140 cred = current_cred();
141 child_cred = __task_cred(child);
caaee623
JH
142 if (mode & PTRACE_MODE_FSCREDS)
143 caller_caps = &cred->cap_effective;
144 else
145 caller_caps = &cred->cap_permitted;
c4a4d603 146 if (cred->user_ns == child_cred->user_ns &&
caaee623 147 cap_issubset(child_cred->cap_permitted, *caller_caps))
8409cca7 148 goto out;
c4a4d603 149 if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE))
8409cca7
SH
150 goto out;
151 ret = -EPERM;
152out:
c69e8d9c
DH
153 rcu_read_unlock();
154 return ret;
5cd9c58f
DH
155}
156
1d045980
DH
157/**
158 * cap_ptrace_traceme - Determine whether another process may trace the current
159 * @parent: The task proposed to be the tracer
160 *
8409cca7
SH
161 * If parent is in the same or an ancestor user_ns and has all current's
162 * capabilities, then ptrace access is allowed.
163 * If parent has the ptrace capability to current's user_ns, then ptrace
164 * access is allowed.
165 * Else denied.
166 *
1d045980
DH
167 * Determine whether the nominated task is permitted to trace the current
168 * process, returning 0 if permission is granted, -ve if denied.
169 */
5cd9c58f
DH
170int cap_ptrace_traceme(struct task_struct *parent)
171{
c69e8d9c 172 int ret = 0;
8409cca7 173 const struct cred *cred, *child_cred;
c69e8d9c
DH
174
175 rcu_read_lock();
8409cca7
SH
176 cred = __task_cred(parent);
177 child_cred = current_cred();
c4a4d603 178 if (cred->user_ns == child_cred->user_ns &&
8409cca7
SH
179 cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
180 goto out;
c4a4d603 181 if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE))
8409cca7
SH
182 goto out;
183 ret = -EPERM;
184out:
c69e8d9c
DH
185 rcu_read_unlock();
186 return ret;
1da177e4
LT
187}
188
1d045980
DH
189/**
190 * cap_capget - Retrieve a task's capability sets
191 * @target: The task from which to retrieve the capability sets
192 * @effective: The place to record the effective set
193 * @inheritable: The place to record the inheritable set
194 * @permitted: The place to record the permitted set
195 *
196 * This function retrieves the capabilities of the nominated task and returns
197 * them to the caller.
198 */
199int cap_capget(struct task_struct *target, kernel_cap_t *effective,
200 kernel_cap_t *inheritable, kernel_cap_t *permitted)
1da177e4 201{
c69e8d9c 202 const struct cred *cred;
b6dff3ec 203
1da177e4 204 /* Derived from kernel/capability.c:sys_capget. */
c69e8d9c
DH
205 rcu_read_lock();
206 cred = __task_cred(target);
b6dff3ec
DH
207 *effective = cred->cap_effective;
208 *inheritable = cred->cap_inheritable;
209 *permitted = cred->cap_permitted;
c69e8d9c 210 rcu_read_unlock();
1da177e4
LT
211 return 0;
212}
213
1d045980
DH
214/*
215 * Determine whether the inheritable capabilities are limited to the old
216 * permitted set. Returns 1 if they are limited, 0 if they are not.
217 */
72c2d582
AM
218static inline int cap_inh_is_capped(void)
219{
1d045980
DH
220 /* they are so limited unless the current task has the CAP_SETPCAP
221 * capability
222 */
c4a4d603 223 if (cap_capable(current_cred(), current_cred()->user_ns,
c1a85a00 224 CAP_SETPCAP, CAP_OPT_NONE) == 0)
1d045980 225 return 0;
1d045980 226 return 1;
1209726c 227}
72c2d582 228
1d045980
DH
229/**
230 * cap_capset - Validate and apply proposed changes to current's capabilities
231 * @new: The proposed new credentials; alterations should be made here
232 * @old: The current task's current credentials
233 * @effective: A pointer to the proposed new effective capabilities set
234 * @inheritable: A pointer to the proposed new inheritable capabilities set
235 * @permitted: A pointer to the proposed new permitted capabilities set
236 *
237 * This function validates and applies a proposed mass change to the current
238 * process's capability sets. The changes are made to the proposed new
239 * credentials, and assuming no error, will be committed by the caller of LSM.
240 */
d84f4f99
DH
241int cap_capset(struct cred *new,
242 const struct cred *old,
243 const kernel_cap_t *effective,
244 const kernel_cap_t *inheritable,
245 const kernel_cap_t *permitted)
1da177e4 246{
d84f4f99
DH
247 if (cap_inh_is_capped() &&
248 !cap_issubset(*inheritable,
249 cap_combine(old->cap_inheritable,
250 old->cap_permitted)))
72c2d582 251 /* incapable of using this inheritable set */
1da177e4 252 return -EPERM;
d84f4f99 253
3b7391de 254 if (!cap_issubset(*inheritable,
d84f4f99
DH
255 cap_combine(old->cap_inheritable,
256 old->cap_bset)))
3b7391de
SH
257 /* no new pI capabilities outside bounding set */
258 return -EPERM;
1da177e4
LT
259
260 /* verify restrictions on target's new Permitted set */
d84f4f99 261 if (!cap_issubset(*permitted, old->cap_permitted))
1da177e4 262 return -EPERM;
1da177e4
LT
263
264 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
d84f4f99 265 if (!cap_issubset(*effective, *permitted))
1da177e4 266 return -EPERM;
1da177e4 267
d84f4f99
DH
268 new->cap_effective = *effective;
269 new->cap_inheritable = *inheritable;
270 new->cap_permitted = *permitted;
58319057
AL
271
272 /*
273 * Mask off ambient bits that are no longer both permitted and
274 * inheritable.
275 */
276 new->cap_ambient = cap_intersect(new->cap_ambient,
277 cap_intersect(*permitted,
278 *inheritable));
279 if (WARN_ON(!cap_ambient_invariant_ok(new)))
280 return -EINVAL;
1da177e4
LT
281 return 0;
282}
283
1d045980
DH
284/**
285 * cap_inode_need_killpriv - Determine if inode change affects privileges
286 * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
287 *
288 * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
289 * affects the security markings on that inode, and if it is, should
ab5348c9 290 * inode_killpriv() be invoked or the change rejected.
1d045980 291 *
ab5348c9
SB
292 * Returns 1 if security.capability has a value, meaning inode_killpriv()
293 * is required, 0 otherwise, meaning inode_killpriv() is not required.
1d045980 294 */
b5376771
SH
295int cap_inode_need_killpriv(struct dentry *dentry)
296{
c6f493d6 297 struct inode *inode = d_backing_inode(dentry);
b5376771
SH
298 int error;
299
5d6c3191
AG
300 error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0);
301 return error > 0;
b5376771
SH
302}
303
1d045980
DH
304/**
305 * cap_inode_killpriv - Erase the security markings on an inode
71bc356f
CB
306 *
307 * @mnt_userns: user namespace of the mount the inode was found from
308 * @dentry: The inode/dentry to alter
1d045980
DH
309 *
310 * Erase the privilege-enhancing security markings on an inode.
311 *
71bc356f
CB
312 * If the inode has been found through an idmapped mount the user namespace of
313 * the vfsmount must be passed through @mnt_userns. This function will then
314 * take care to map the inode according to @mnt_userns before checking
315 * permissions. On non-idmapped mounts or if permission checking is to be
316 * performed on the raw inode simply passs init_user_ns.
317 *
1d045980
DH
318 * Returns 0 if successful, -ve on error.
319 */
71bc356f 320int cap_inode_killpriv(struct user_namespace *mnt_userns, struct dentry *dentry)
b5376771 321{
5d6c3191 322 int error;
b5376771 323
71bc356f 324 error = __vfs_removexattr(mnt_userns, dentry, XATTR_NAME_CAPS);
5d6c3191
AG
325 if (error == -EOPNOTSUPP)
326 error = 0;
327 return error;
b5376771
SH
328}
329
8db6c34f
SH
330static bool rootid_owns_currentns(kuid_t kroot)
331{
332 struct user_namespace *ns;
333
334 if (!uid_valid(kroot))
335 return false;
336
337 for (ns = current_user_ns(); ; ns = ns->parent) {
338 if (from_kuid(ns, kroot) == 0)
339 return true;
340 if (ns == &init_user_ns)
341 break;
342 }
343
344 return false;
345}
346
347static __u32 sansflags(__u32 m)
348{
349 return m & ~VFS_CAP_FLAGS_EFFECTIVE;
350}
351
dc32b5c3 352static bool is_v2header(size_t size, const struct vfs_cap_data *cap)
8db6c34f 353{
8db6c34f
SH
354 if (size != XATTR_CAPS_SZ_2)
355 return false;
dc32b5c3 356 return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_2;
8db6c34f
SH
357}
358
dc32b5c3 359static bool is_v3header(size_t size, const struct vfs_cap_data *cap)
8db6c34f 360{
8db6c34f
SH
361 if (size != XATTR_CAPS_SZ_3)
362 return false;
dc32b5c3 363 return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_3;
8db6c34f
SH
364}
365
366/*
367 * getsecurity: We are called for security.* before any attempt to read the
368 * xattr from the inode itself.
369 *
370 * This gives us a chance to read the on-disk value and convert it. If we
371 * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler.
372 *
373 * Note we are not called by vfs_getxattr_alloc(), but that is only called
374 * by the integrity subsystem, which really wants the unconverted values -
375 * so that's good.
376 */
71bc356f
CB
377int cap_inode_getsecurity(struct user_namespace *mnt_userns,
378 struct inode *inode, const char *name, void **buffer,
8db6c34f
SH
379 bool alloc)
380{
381 int size, ret;
382 kuid_t kroot;
f2b00be4 383 u32 nsmagic, magic;
8db6c34f
SH
384 uid_t root, mappedroot;
385 char *tmpbuf = NULL;
386 struct vfs_cap_data *cap;
f2b00be4 387 struct vfs_ns_cap_data *nscap = NULL;
8db6c34f
SH
388 struct dentry *dentry;
389 struct user_namespace *fs_ns;
390
391 if (strcmp(name, "capability") != 0)
392 return -EOPNOTSUPP;
393
355139a8 394 dentry = d_find_any_alias(inode);
8db6c34f
SH
395 if (!dentry)
396 return -EINVAL;
397
398 size = sizeof(struct vfs_ns_cap_data);
71bc356f 399 ret = (int)vfs_getxattr_alloc(mnt_userns, dentry, XATTR_NAME_CAPS,
c7c7a1a1 400 &tmpbuf, size, GFP_NOFS);
8db6c34f
SH
401 dput(dentry);
402
403 if (ret < 0)
404 return ret;
405
406 fs_ns = inode->i_sb->s_user_ns;
407 cap = (struct vfs_cap_data *) tmpbuf;
dc32b5c3 408 if (is_v2header((size_t) ret, cap)) {
f2b00be4
MS
409 root = 0;
410 } else if (is_v3header((size_t) ret, cap)) {
411 nscap = (struct vfs_ns_cap_data *) tmpbuf;
412 root = le32_to_cpu(nscap->rootid);
413 } else {
414 size = -EINVAL;
415 goto out_free;
8db6c34f
SH
416 }
417
8db6c34f
SH
418 kroot = make_kuid(fs_ns, root);
419
71bc356f
CB
420 /* If this is an idmapped mount shift the kuid. */
421 kroot = kuid_into_mnt(mnt_userns, kroot);
422
8db6c34f
SH
423 /* If the root kuid maps to a valid uid in current ns, then return
424 * this as a nscap. */
425 mappedroot = from_kuid(current_user_ns(), kroot);
426 if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) {
f2b00be4 427 size = sizeof(struct vfs_ns_cap_data);
8db6c34f 428 if (alloc) {
f2b00be4
MS
429 if (!nscap) {
430 /* v2 -> v3 conversion */
431 nscap = kzalloc(size, GFP_ATOMIC);
432 if (!nscap) {
433 size = -ENOMEM;
434 goto out_free;
435 }
436 nsmagic = VFS_CAP_REVISION_3;
437 magic = le32_to_cpu(cap->magic_etc);
438 if (magic & VFS_CAP_FLAGS_EFFECTIVE)
439 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE;
440 memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
441 nscap->magic_etc = cpu_to_le32(nsmagic);
442 } else {
443 /* use allocated v3 buffer */
444 tmpbuf = NULL;
445 }
8db6c34f 446 nscap->rootid = cpu_to_le32(mappedroot);
f2b00be4
MS
447 *buffer = nscap;
448 }
449 goto out_free;
8db6c34f
SH
450 }
451
452 if (!rootid_owns_currentns(kroot)) {
f2b00be4
MS
453 size = -EOVERFLOW;
454 goto out_free;
8db6c34f
SH
455 }
456
457 /* This comes from a parent namespace. Return as a v2 capability */
458 size = sizeof(struct vfs_cap_data);
459 if (alloc) {
f2b00be4
MS
460 if (nscap) {
461 /* v3 -> v2 conversion */
462 cap = kzalloc(size, GFP_ATOMIC);
463 if (!cap) {
464 size = -ENOMEM;
465 goto out_free;
466 }
8db6c34f
SH
467 magic = VFS_CAP_REVISION_2;
468 nsmagic = le32_to_cpu(nscap->magic_etc);
469 if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE)
470 magic |= VFS_CAP_FLAGS_EFFECTIVE;
471 memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
472 cap->magic_etc = cpu_to_le32(magic);
1f578172 473 } else {
f2b00be4
MS
474 /* use unconverted v2 */
475 tmpbuf = NULL;
8db6c34f 476 }
f2b00be4 477 *buffer = cap;
8db6c34f 478 }
f2b00be4 479out_free:
8db6c34f
SH
480 kfree(tmpbuf);
481 return size;
482}
483
e65ce2a5
CB
484/**
485 * rootid_from_xattr - translate root uid of vfs caps
486 *
487 * @value: vfs caps value which may be modified by this function
488 * @size: size of @ivalue
489 * @task_ns: user namespace of the caller
490 * @mnt_userns: user namespace of the mount the inode was found from
491 *
492 * If the inode has been found through an idmapped mount the user namespace of
493 * the vfsmount must be passed through @mnt_userns. This function will then
494 * take care to map the inode according to @mnt_userns before checking
495 * permissions. On non-idmapped mounts or if permission checking is to be
496 * performed on the raw inode simply passs init_user_ns.
497 */
8db6c34f 498static kuid_t rootid_from_xattr(const void *value, size_t size,
e65ce2a5
CB
499 struct user_namespace *task_ns,
500 struct user_namespace *mnt_userns)
8db6c34f
SH
501{
502 const struct vfs_ns_cap_data *nscap = value;
e65ce2a5 503 kuid_t rootkid;
8db6c34f
SH
504 uid_t rootid = 0;
505
506 if (size == XATTR_CAPS_SZ_3)
507 rootid = le32_to_cpu(nscap->rootid);
508
e65ce2a5
CB
509 rootkid = make_kuid(task_ns, rootid);
510 return kuid_from_mnt(mnt_userns, rootkid);
8db6c34f
SH
511}
512
dc32b5c3 513static bool validheader(size_t size, const struct vfs_cap_data *cap)
8db6c34f 514{
dc32b5c3 515 return is_v2header(size, cap) || is_v3header(size, cap);
8db6c34f
SH
516}
517
e65ce2a5
CB
518/**
519 * cap_convert_nscap - check vfs caps
520 *
521 * @mnt_userns: user namespace of the mount the inode was found from
522 * @dentry: used to retrieve inode to check permissions on
523 * @ivalue: vfs caps value which may be modified by this function
524 * @size: size of @ivalue
525 *
8db6c34f
SH
526 * User requested a write of security.capability. If needed, update the
527 * xattr to change from v2 to v3, or to fixup the v3 rootid.
528 *
e65ce2a5
CB
529 * If the inode has been found through an idmapped mount the user namespace of
530 * the vfsmount must be passed through @mnt_userns. This function will then
531 * take care to map the inode according to @mnt_userns before checking
532 * permissions. On non-idmapped mounts or if permission checking is to be
533 * performed on the raw inode simply passs init_user_ns.
534 *
8db6c34f
SH
535 * If all is ok, we return the new size, on error return < 0.
536 */
e65ce2a5
CB
537int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry,
538 const void **ivalue, size_t size)
8db6c34f
SH
539{
540 struct vfs_ns_cap_data *nscap;
541 uid_t nsrootid;
542 const struct vfs_cap_data *cap = *ivalue;
543 __u32 magic, nsmagic;
544 struct inode *inode = d_backing_inode(dentry);
545 struct user_namespace *task_ns = current_user_ns(),
95ebabde
EB
546 *fs_ns = inode->i_sb->s_user_ns,
547 *ancestor;
8db6c34f
SH
548 kuid_t rootid;
549 size_t newsize;
550
551 if (!*ivalue)
552 return -EINVAL;
dc32b5c3 553 if (!validheader(size, cap))
8db6c34f 554 return -EINVAL;
e65ce2a5 555 if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP))
8db6c34f 556 return -EPERM;
e65ce2a5 557 if (size == XATTR_CAPS_SZ_2 && (mnt_userns == &init_user_ns))
8db6c34f
SH
558 if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP))
559 /* user is privileged, just write the v2 */
560 return size;
561
e65ce2a5 562 rootid = rootid_from_xattr(*ivalue, size, task_ns, mnt_userns);
8db6c34f
SH
563 if (!uid_valid(rootid))
564 return -EINVAL;
565
566 nsrootid = from_kuid(fs_ns, rootid);
567 if (nsrootid == -1)
568 return -EINVAL;
569
95ebabde
EB
570 /*
571 * Do not allow allow adding a v3 filesystem capability xattr
572 * if the rootid field is ambiguous.
573 */
574 for (ancestor = task_ns->parent; ancestor; ancestor = ancestor->parent) {
575 if (from_kuid(ancestor, rootid) == 0)
576 return -EINVAL;
577 }
578
8db6c34f
SH
579 newsize = sizeof(struct vfs_ns_cap_data);
580 nscap = kmalloc(newsize, GFP_ATOMIC);
581 if (!nscap)
582 return -ENOMEM;
583 nscap->rootid = cpu_to_le32(nsrootid);
584 nsmagic = VFS_CAP_REVISION_3;
585 magic = le32_to_cpu(cap->magic_etc);
586 if (magic & VFS_CAP_FLAGS_EFFECTIVE)
587 nsmagic |= VFS_CAP_FLAGS_EFFECTIVE;
588 nscap->magic_etc = cpu_to_le32(nsmagic);
589 memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
590
8db6c34f
SH
591 *ivalue = nscap;
592 return newsize;
593}
594
1d045980
DH
595/*
596 * Calculate the new process capability sets from the capability sets attached
597 * to a file.
598 */
c0b00441 599static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
a6f76f23 600 struct linux_binprm *bprm,
4d49f671 601 bool *effective,
fc7eadf7 602 bool *has_fcap)
b5376771 603{
a6f76f23 604 struct cred *new = bprm->cred;
c0b00441
EP
605 unsigned i;
606 int ret = 0;
607
608 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
a6f76f23 609 *effective = true;
c0b00441 610
4d49f671 611 if (caps->magic_etc & VFS_CAP_REVISION_MASK)
fc7eadf7 612 *has_fcap = true;
4d49f671 613
c0b00441
EP
614 CAP_FOR_EACH_U32(i) {
615 __u32 permitted = caps->permitted.cap[i];
616 __u32 inheritable = caps->inheritable.cap[i];
617
618 /*
619 * pP' = (X & fP) | (pI & fI)
58319057 620 * The addition of pA' is handled later.
c0b00441 621 */
a6f76f23
DH
622 new->cap_permitted.cap[i] =
623 (new->cap_bset.cap[i] & permitted) |
624 (new->cap_inheritable.cap[i] & inheritable);
c0b00441 625
a6f76f23
DH
626 if (permitted & ~new->cap_permitted.cap[i])
627 /* insufficient to execute correctly */
c0b00441 628 ret = -EPERM;
c0b00441
EP
629 }
630
631 /*
632 * For legacy apps, with no internal support for recognizing they
633 * do not have enough capabilities, we return an error if they are
634 * missing some "forced" (aka file-permitted) capabilities.
635 */
a6f76f23 636 return *effective ? ret : 0;
c0b00441
EP
637}
638
71bc356f
CB
639/**
640 * get_vfs_caps_from_disk - retrieve vfs caps from disk
641 *
642 * @mnt_userns: user namespace of the mount the inode was found from
643 * @dentry: dentry from which @inode is retrieved
644 * @cpu_caps: vfs capabilities
645 *
1d045980 646 * Extract the on-exec-apply capability sets for an executable file.
71bc356f
CB
647 *
648 * If the inode has been found through an idmapped mount the user namespace of
649 * the vfsmount must be passed through @mnt_userns. This function will then
650 * take care to map the inode according to @mnt_userns before checking
651 * permissions. On non-idmapped mounts or if permission checking is to be
652 * performed on the raw inode simply passs init_user_ns.
1d045980 653 */
71bc356f
CB
654int get_vfs_caps_from_disk(struct user_namespace *mnt_userns,
655 const struct dentry *dentry,
656 struct cpu_vfs_cap_data *cpu_caps)
c0b00441 657{
c6f493d6 658 struct inode *inode = d_backing_inode(dentry);
b5376771 659 __u32 magic_etc;
e338d263 660 unsigned tocopy, i;
c0b00441 661 int size;
8db6c34f
SH
662 struct vfs_ns_cap_data data, *nscaps = &data;
663 struct vfs_cap_data *caps = (struct vfs_cap_data *) &data;
664 kuid_t rootkuid;
76ba89c7 665 struct user_namespace *fs_ns;
c0b00441
EP
666
667 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
668
5d6c3191 669 if (!inode)
c0b00441
EP
670 return -ENODATA;
671
76ba89c7 672 fs_ns = inode->i_sb->s_user_ns;
5d6c3191 673 size = __vfs_getxattr((struct dentry *)dentry, inode,
8db6c34f 674 XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ);
a6f76f23 675 if (size == -ENODATA || size == -EOPNOTSUPP)
c0b00441
EP
676 /* no data, that's ok */
677 return -ENODATA;
8db6c34f 678
c0b00441
EP
679 if (size < 0)
680 return size;
b5376771 681
e338d263 682 if (size < sizeof(magic_etc))
b5376771
SH
683 return -EINVAL;
684
8db6c34f 685 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc);
b5376771 686
8db6c34f 687 rootkuid = make_kuid(fs_ns, 0);
a6f76f23 688 switch (magic_etc & VFS_CAP_REVISION_MASK) {
e338d263
AM
689 case VFS_CAP_REVISION_1:
690 if (size != XATTR_CAPS_SZ_1)
691 return -EINVAL;
692 tocopy = VFS_CAP_U32_1;
693 break;
694 case VFS_CAP_REVISION_2:
695 if (size != XATTR_CAPS_SZ_2)
696 return -EINVAL;
697 tocopy = VFS_CAP_U32_2;
698 break;
8db6c34f
SH
699 case VFS_CAP_REVISION_3:
700 if (size != XATTR_CAPS_SZ_3)
701 return -EINVAL;
702 tocopy = VFS_CAP_U32_3;
703 rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid));
704 break;
705
b5376771
SH
706 default:
707 return -EINVAL;
708 }
8db6c34f
SH
709 /* Limit the caps to the mounter of the filesystem
710 * or the more limited uid specified in the xattr.
711 */
71bc356f 712 rootkuid = kuid_into_mnt(mnt_userns, rootkuid);
8db6c34f
SH
713 if (!rootid_owns_currentns(rootkuid))
714 return -ENODATA;
e338d263 715
5459c164 716 CAP_FOR_EACH_U32(i) {
c0b00441
EP
717 if (i >= tocopy)
718 break;
8db6c34f
SH
719 cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted);
720 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable);
e338d263 721 }
a6f76f23 722
7d8b6c63
EP
723 cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
724 cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
725
2fec30e2
RGB
726 cpu_caps->rootid = rootkuid;
727
c0b00441 728 return 0;
b5376771
SH
729}
730
1d045980
DH
731/*
732 * Attempt to get the on-exec apply capability sets for an executable file from
733 * its xattrs and, if present, apply them to the proposed credentials being
734 * constructed by execve().
735 */
56305aa9
EB
736static int get_file_caps(struct linux_binprm *bprm, struct file *file,
737 bool *effective, bool *has_fcap)
b5376771 738{
b5376771 739 int rc = 0;
c0b00441 740 struct cpu_vfs_cap_data vcaps;
b5376771 741
ee67ae7e 742 cap_clear(bprm->cred->cap_permitted);
3318a386 743
1f29fae2
SH
744 if (!file_caps_enabled)
745 return 0;
746
56305aa9 747 if (!mnt_may_suid(file->f_path.mnt))
b5376771 748 return 0;
380cf5ba
AL
749
750 /*
751 * This check is redundant with mnt_may_suid() but is kept to make
752 * explicit that capability bits are limited to s_user_ns and its
753 * descendants.
754 */
56305aa9 755 if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns))
d07b846f 756 return 0;
b5376771 757
71bc356f
CB
758 rc = get_vfs_caps_from_disk(file_mnt_user_ns(file),
759 file->f_path.dentry, &vcaps);
c0b00441
EP
760 if (rc < 0) {
761 if (rc == -EINVAL)
8db6c34f
SH
762 printk(KERN_NOTICE "Invalid argument reading file caps for %s\n",
763 bprm->filename);
c0b00441
EP
764 else if (rc == -ENODATA)
765 rc = 0;
b5376771
SH
766 goto out;
767 }
b5376771 768
fc7eadf7 769 rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap);
b5376771
SH
770
771out:
b5376771 772 if (rc)
ee67ae7e 773 cap_clear(bprm->cred->cap_permitted);
b5376771
SH
774
775 return rc;
776}
777
9304b46c
RGB
778static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); }
779
81a6a012
RGB
780static inline bool __is_real(kuid_t uid, struct cred *cred)
781{ return uid_eq(cred->uid, uid); }
782
783static inline bool __is_eff(kuid_t uid, struct cred *cred)
784{ return uid_eq(cred->euid, uid); }
785
786static inline bool __is_suid(kuid_t uid, struct cred *cred)
787{ return !__is_real(uid, cred) && __is_eff(uid, cred); }
788
db1a8922
RGB
789/*
790 * handle_privileged_root - Handle case of privileged root
791 * @bprm: The execution parameters, including the proposed creds
792 * @has_fcap: Are any file capabilities set?
793 * @effective: Do we have effective root privilege?
794 * @root_uid: This namespace' root UID WRT initial USER namespace
795 *
796 * Handle the case where root is privileged and hasn't been neutered by
797 * SECURE_NOROOT. If file capabilities are set, they won't be combined with
798 * set UID root and nothing is changed. If we are root, cap_permitted is
799 * updated. If we have become set UID root, the effective bit is set.
800 */
fc7eadf7 801static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap,
db1a8922
RGB
802 bool *effective, kuid_t root_uid)
803{
804 const struct cred *old = current_cred();
805 struct cred *new = bprm->cred;
806
9304b46c 807 if (!root_privileged())
db1a8922
RGB
808 return;
809 /*
810 * If the legacy file capability is set, then don't set privs
811 * for a setuid root binary run by a non-root user. Do set it
812 * for a root user just to cause least surprise to an admin.
813 */
81a6a012 814 if (has_fcap && __is_suid(root_uid, new)) {
db1a8922
RGB
815 warn_setuid_and_fcaps_mixed(bprm->filename);
816 return;
817 }
818 /*
819 * To support inheritance of root-permissions and suid-root
820 * executables under compatibility mode, we override the
821 * capability sets for the file.
822 */
81a6a012 823 if (__is_eff(root_uid, new) || __is_real(root_uid, new)) {
db1a8922
RGB
824 /* pP' = (cap_bset & ~0) | (pI & ~0) */
825 new->cap_permitted = cap_combine(old->cap_bset,
826 old->cap_inheritable);
827 }
828 /*
829 * If only the real uid is 0, we do not set the effective bit.
830 */
81a6a012 831 if (__is_eff(root_uid, new))
db1a8922
RGB
832 *effective = true;
833}
834
4c7e715f
RGB
835#define __cap_gained(field, target, source) \
836 !cap_issubset(target->cap_##field, source->cap_##field)
837#define __cap_grew(target, source, cred) \
838 !cap_issubset(cred->cap_##target, cred->cap_##source)
839#define __cap_full(field, cred) \
840 cap_issubset(CAP_FULL_SET, cred->cap_##field)
81a6a012
RGB
841
842static inline bool __is_setuid(struct cred *new, const struct cred *old)
843{ return !uid_eq(new->euid, old->uid); }
844
845static inline bool __is_setgid(struct cred *new, const struct cred *old)
846{ return !gid_eq(new->egid, old->gid); }
847
9fbc2c79 848/*
dbbbe110 849 * 1) Audit candidate if current->cap_effective is set
9fbc2c79
RGB
850 *
851 * We do not bother to audit if 3 things are true:
852 * 1) cap_effective has all caps
588fb2c7 853 * 2) we became root *OR* are were already root
9fbc2c79
RGB
854 * 3) root is supposed to have all caps (SECURE_NOROOT)
855 * Since this is just a normal root execing a process.
856 *
857 * Number 1 above might fail if you don't have a full bset, but I think
858 * that is interesting information to audit.
dbbbe110
RGB
859 *
860 * A number of other conditions require logging:
861 * 2) something prevented setuid root getting all caps
862 * 3) non-setuid root gets fcaps
863 * 4) non-setuid root gets ambient
9fbc2c79 864 */
dbbbe110
RGB
865static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old,
866 kuid_t root, bool has_fcap)
9fbc2c79
RGB
867{
868 bool ret = false;
869
dbbbe110
RGB
870 if ((__cap_grew(effective, ambient, new) &&
871 !(__cap_full(effective, new) &&
872 (__is_eff(root, new) || __is_real(root, new)) &&
873 root_privileged())) ||
874 (root_privileged() &&
875 __is_suid(root, new) &&
876 !__cap_full(effective, new)) ||
877 (!__is_setuid(new, old) &&
878 ((has_fcap &&
879 __cap_gained(permitted, new, old)) ||
880 __cap_gained(ambient, new, old))))
881
02ebbaf4 882 ret = true;
dbbbe110 883
9fbc2c79
RGB
884 return ret;
885}
886
1d045980 887/**
56305aa9 888 * cap_bprm_creds_from_file - Set up the proposed credentials for execve().
1d045980 889 * @bprm: The execution parameters, including the proposed creds
56305aa9 890 * @file: The file to pull the credentials from
1d045980
DH
891 *
892 * Set up the proposed credentials for a new execution context being
893 * constructed by execve(). The proposed creds in @bprm->cred is altered,
894 * which won't take effect immediately. Returns 0 if successful, -ve on error.
a6f76f23 895 */
56305aa9 896int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file)
1da177e4 897{
56305aa9 898 /* Process setpcap binaries and capabilities for uid 0 */
a6f76f23
DH
899 const struct cred *old = current_cred();
900 struct cred *new = bprm->cred;
fc7eadf7 901 bool effective = false, has_fcap = false, is_setid;
b5376771 902 int ret;
18815a18 903 kuid_t root_uid;
1da177e4 904
58319057
AL
905 if (WARN_ON(!cap_ambient_invariant_ok(old)))
906 return -EPERM;
907
56305aa9 908 ret = get_file_caps(bprm, file, &effective, &has_fcap);
a6f76f23
DH
909 if (ret < 0)
910 return ret;
1da177e4 911
18815a18
EB
912 root_uid = make_kuid(new->user_ns, 0);
913
fc7eadf7 914 handle_privileged_root(bprm, has_fcap, &effective, root_uid);
b5376771 915
d52fc5dd 916 /* if we have fs caps, clear dangerous personality flags */
4c7e715f 917 if (__cap_gained(permitted, new, old))
56305aa9 918 bprm->per_clear |= PER_CLEAR_ON_SETID;
d52fc5dd 919
a6f76f23 920 /* Don't let someone trace a set[ug]id/setpcap binary with the revised
259e5e6c
AL
921 * credentials unless they have the appropriate permit.
922 *
923 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
a6f76f23 924 */
81a6a012 925 is_setid = __is_setuid(new, old) || __is_setgid(new, old);
58319057 926
4c7e715f 927 if ((is_setid || __cap_gained(permitted, new, old)) &&
9227dd2a 928 ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) ||
20523132 929 !ptracer_capable(current, new->user_ns))) {
a6f76f23 930 /* downgrade; they get no more than they had, and maybe less */
70169420 931 if (!ns_capable(new->user_ns, CAP_SETUID) ||
259e5e6c 932 (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
a6f76f23
DH
933 new->euid = new->uid;
934 new->egid = new->gid;
1da177e4 935 }
b3a222e5
SH
936 new->cap_permitted = cap_intersect(new->cap_permitted,
937 old->cap_permitted);
1da177e4
LT
938 }
939
a6f76f23
DH
940 new->suid = new->fsuid = new->euid;
941 new->sgid = new->fsgid = new->egid;
1da177e4 942
58319057 943 /* File caps or setid cancels ambient. */
fc7eadf7 944 if (has_fcap || is_setid)
58319057
AL
945 cap_clear(new->cap_ambient);
946
947 /*
948 * Now that we've computed pA', update pP' to give:
949 * pP' = (X & fP) | (pI & fI) | pA'
950 */
951 new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient);
952
953 /*
954 * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set,
955 * this is the same as pE' = (fE ? pP' : 0) | pA'.
956 */
4bf2ea77
EP
957 if (effective)
958 new->cap_effective = new->cap_permitted;
959 else
58319057
AL
960 new->cap_effective = new->cap_ambient;
961
962 if (WARN_ON(!cap_ambient_invariant_ok(new)))
963 return -EPERM;
964
dbbbe110 965 if (nonroot_raised_pE(new, old, root_uid, has_fcap)) {
9fbc2c79
RGB
966 ret = audit_log_bprm_fcaps(bprm, new, old);
967 if (ret < 0)
968 return ret;
3fc689e9 969 }
1da177e4 970
d84f4f99 971 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
58319057
AL
972
973 if (WARN_ON(!cap_ambient_invariant_ok(new)))
974 return -EPERM;
975
46d98eb4 976 /* Check for privilege-elevated exec. */
02ebbaf4
RGB
977 if (is_setid ||
978 (!__is_real(root_uid, new) &&
979 (effective ||
980 __cap_grew(permitted, ambient, new))))
56305aa9 981 bprm->secureexec = 1;
b5376771 982
ee67ae7e 983 return 0;
1da177e4
LT
984}
985
1d045980
DH
986/**
987 * cap_inode_setxattr - Determine whether an xattr may be altered
988 * @dentry: The inode/dentry being altered
989 * @name: The name of the xattr to be changed
990 * @value: The value that the xattr will be changed to
991 * @size: The size of value
992 * @flags: The replacement flag
993 *
994 * Determine whether an xattr may be altered or set on an inode, returning 0 if
995 * permission is granted, -ve if denied.
996 *
997 * This is used to make sure security xattrs don't get updated or set by those
998 * who aren't privileged to do so.
999 */
8f0cfa52
DH
1000int cap_inode_setxattr(struct dentry *dentry, const char *name,
1001 const void *value, size_t size, int flags)
1da177e4 1002{
b1d749c5
EB
1003 struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
1004
8db6c34f
SH
1005 /* Ignore non-security xattrs */
1006 if (strncmp(name, XATTR_SECURITY_PREFIX,
c5eaab1d 1007 XATTR_SECURITY_PREFIX_LEN) != 0)
8db6c34f
SH
1008 return 0;
1009
1010 /*
1011 * For XATTR_NAME_CAPS the check will be done in
1012 * cap_convert_nscap(), called by setxattr()
1013 */
1014 if (strcmp(name, XATTR_NAME_CAPS) == 0)
b5376771 1015 return 0;
1d045980 1016
b1d749c5 1017 if (!ns_capable(user_ns, CAP_SYS_ADMIN))
1da177e4
LT
1018 return -EPERM;
1019 return 0;
1020}
1021
1d045980
DH
1022/**
1023 * cap_inode_removexattr - Determine whether an xattr may be removed
71bc356f
CB
1024 *
1025 * @mnt_userns: User namespace of the mount the inode was found from
1026 * @dentry: The inode/dentry being altered
1027 * @name: The name of the xattr to be changed
1d045980
DH
1028 *
1029 * Determine whether an xattr may be removed from an inode, returning 0 if
1030 * permission is granted, -ve if denied.
1031 *
71bc356f
CB
1032 * If the inode has been found through an idmapped mount the user namespace of
1033 * the vfsmount must be passed through @mnt_userns. This function will then
1034 * take care to map the inode according to @mnt_userns before checking
1035 * permissions. On non-idmapped mounts or if permission checking is to be
1036 * performed on the raw inode simply passs init_user_ns.
1037 *
1d045980
DH
1038 * This is used to make sure security xattrs don't get removed by those who
1039 * aren't privileged to remove them.
1040 */
71bc356f
CB
1041int cap_inode_removexattr(struct user_namespace *mnt_userns,
1042 struct dentry *dentry, const char *name)
1da177e4 1043{
b1d749c5
EB
1044 struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
1045
8db6c34f
SH
1046 /* Ignore non-security xattrs */
1047 if (strncmp(name, XATTR_SECURITY_PREFIX,
c5eaab1d 1048 XATTR_SECURITY_PREFIX_LEN) != 0)
8db6c34f
SH
1049 return 0;
1050
1051 if (strcmp(name, XATTR_NAME_CAPS) == 0) {
1052 /* security.capability gets namespaced */
1053 struct inode *inode = d_backing_inode(dentry);
1054 if (!inode)
1055 return -EINVAL;
71bc356f 1056 if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP))
b5376771
SH
1057 return -EPERM;
1058 return 0;
1d045980
DH
1059 }
1060
b1d749c5 1061 if (!ns_capable(user_ns, CAP_SYS_ADMIN))
1da177e4
LT
1062 return -EPERM;
1063 return 0;
1064}
1065
a6f76f23 1066/*
1da177e4
LT
1067 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
1068 * a process after a call to setuid, setreuid, or setresuid.
1069 *
1070 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
1071 * {r,e,s}uid != 0, the permitted and effective capabilities are
1072 * cleared.
1073 *
1074 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
1075 * capabilities of the process are cleared.
1076 *
1077 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
1078 * capabilities are set to the permitted capabilities.
1079 *
a6f76f23 1080 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
1da177e4
LT
1081 * never happen.
1082 *
a6f76f23 1083 * -astor
1da177e4
LT
1084 *
1085 * cevans - New behaviour, Oct '99
1086 * A process may, via prctl(), elect to keep its capabilities when it
1087 * calls setuid() and switches away from uid==0. Both permitted and
1088 * effective sets will be retained.
1089 * Without this change, it was impossible for a daemon to drop only some
1090 * of its privilege. The call to setuid(!=0) would drop all privileges!
1091 * Keeping uid 0 is not an option because uid 0 owns too many vital
1092 * files..
1093 * Thanks to Olaf Kirch and Peter Benie for spotting this.
1094 */
d84f4f99 1095static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
1da177e4 1096{
18815a18
EB
1097 kuid_t root_uid = make_kuid(old->user_ns, 0);
1098
1099 if ((uid_eq(old->uid, root_uid) ||
1100 uid_eq(old->euid, root_uid) ||
1101 uid_eq(old->suid, root_uid)) &&
1102 (!uid_eq(new->uid, root_uid) &&
1103 !uid_eq(new->euid, root_uid) &&
58319057
AL
1104 !uid_eq(new->suid, root_uid))) {
1105 if (!issecure(SECURE_KEEP_CAPS)) {
1106 cap_clear(new->cap_permitted);
1107 cap_clear(new->cap_effective);
1108 }
1109
1110 /*
1111 * Pre-ambient programs expect setresuid to nonroot followed
1112 * by exec to drop capabilities. We should make sure that
1113 * this remains the case.
1114 */
1115 cap_clear(new->cap_ambient);
1da177e4 1116 }
18815a18 1117 if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
d84f4f99 1118 cap_clear(new->cap_effective);
18815a18 1119 if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
d84f4f99 1120 new->cap_effective = new->cap_permitted;
1da177e4
LT
1121}
1122
1d045980
DH
1123/**
1124 * cap_task_fix_setuid - Fix up the results of setuid() call
1125 * @new: The proposed credentials
1126 * @old: The current task's current credentials
1127 * @flags: Indications of what has changed
1128 *
1129 * Fix up the results of setuid() call before the credential changes are
1130 * actually applied, returning 0 to grant the changes, -ve to deny them.
1131 */
d84f4f99 1132int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
1da177e4
LT
1133{
1134 switch (flags) {
1135 case LSM_SETID_RE:
1136 case LSM_SETID_ID:
1137 case LSM_SETID_RES:
1d045980
DH
1138 /* juggle the capabilities to follow [RES]UID changes unless
1139 * otherwise suppressed */
d84f4f99
DH
1140 if (!issecure(SECURE_NO_SETUID_FIXUP))
1141 cap_emulate_setxuid(new, old);
1da177e4 1142 break;
1da177e4 1143
1d045980
DH
1144 case LSM_SETID_FS:
1145 /* juggle the capabilties to follow FSUID changes, unless
1146 * otherwise suppressed
1147 *
d84f4f99
DH
1148 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
1149 * if not, we might be a bit too harsh here.
1150 */
1151 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
18815a18
EB
1152 kuid_t root_uid = make_kuid(old->user_ns, 0);
1153 if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
d84f4f99
DH
1154 new->cap_effective =
1155 cap_drop_fs_set(new->cap_effective);
1d045980 1156
18815a18 1157 if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
d84f4f99
DH
1158 new->cap_effective =
1159 cap_raise_fs_set(new->cap_effective,
1160 new->cap_permitted);
1da177e4 1161 }
d84f4f99 1162 break;
1d045980 1163
1da177e4
LT
1164 default:
1165 return -EINVAL;
1166 }
1167
1168 return 0;
1169}
1170
b5376771
SH
1171/*
1172 * Rationale: code calling task_setscheduler, task_setioprio, and
1173 * task_setnice, assumes that
1174 * . if capable(cap_sys_nice), then those actions should be allowed
1175 * . if not capable(cap_sys_nice), but acting on your own processes,
1176 * then those actions should be allowed
1177 * This is insufficient now since you can call code without suid, but
1178 * yet with increased caps.
1179 * So we check for increased caps on the target process.
1180 */
de45e806 1181static int cap_safe_nice(struct task_struct *p)
b5376771 1182{
f54fb863 1183 int is_subset, ret = 0;
c69e8d9c
DH
1184
1185 rcu_read_lock();
1186 is_subset = cap_issubset(__task_cred(p)->cap_permitted,
1187 current_cred()->cap_permitted);
f54fb863
SH
1188 if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE))
1189 ret = -EPERM;
c69e8d9c
DH
1190 rcu_read_unlock();
1191
f54fb863 1192 return ret;
b5376771
SH
1193}
1194
1d045980
DH
1195/**
1196 * cap_task_setscheduler - Detemine if scheduler policy change is permitted
1197 * @p: The task to affect
1d045980
DH
1198 *
1199 * Detemine if the requested scheduler policy change is permitted for the
1200 * specified task, returning 0 if permission is granted, -ve if denied.
1201 */
b0ae1981 1202int cap_task_setscheduler(struct task_struct *p)
b5376771
SH
1203{
1204 return cap_safe_nice(p);
1205}
1206
1d045980
DH
1207/**
1208 * cap_task_ioprio - Detemine if I/O priority change is permitted
1209 * @p: The task to affect
1210 * @ioprio: The I/O priority to set
1211 *
1212 * Detemine if the requested I/O priority change is permitted for the specified
1213 * task, returning 0 if permission is granted, -ve if denied.
1214 */
1215int cap_task_setioprio(struct task_struct *p, int ioprio)
b5376771
SH
1216{
1217 return cap_safe_nice(p);
1218}
1219
1d045980
DH
1220/**
1221 * cap_task_ioprio - Detemine if task priority change is permitted
1222 * @p: The task to affect
1223 * @nice: The nice value to set
1224 *
1225 * Detemine if the requested task priority change is permitted for the
1226 * specified task, returning 0 if permission is granted, -ve if denied.
1227 */
1228int cap_task_setnice(struct task_struct *p, int nice)
b5376771
SH
1229{
1230 return cap_safe_nice(p);
1231}
1232
3b7391de 1233/*
1d045980
DH
1234 * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from
1235 * the current task's bounding set. Returns 0 on success, -ve on error.
3b7391de 1236 */
6d6f3328 1237static int cap_prctl_drop(unsigned long cap)
3b7391de 1238{
6d6f3328
TH
1239 struct cred *new;
1240
160da84d 1241 if (!ns_capable(current_user_ns(), CAP_SETPCAP))
3b7391de
SH
1242 return -EPERM;
1243 if (!cap_valid(cap))
1244 return -EINVAL;
d84f4f99 1245
6d6f3328
TH
1246 new = prepare_creds();
1247 if (!new)
1248 return -ENOMEM;
d84f4f99 1249 cap_lower(new->cap_bset, cap);
6d6f3328 1250 return commit_creds(new);
3b7391de 1251}
3898b1b4 1252
1d045980
DH
1253/**
1254 * cap_task_prctl - Implement process control functions for this security module
1255 * @option: The process control function requested
1256 * @arg2, @arg3, @arg4, @arg5: The argument data for this function
1257 *
1258 * Allow process control functions (sys_prctl()) to alter capabilities; may
1259 * also deny access to other functions not otherwise implemented here.
1260 *
1261 * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
1262 * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM
1263 * modules will consider performing the function.
1264 */
3898b1b4 1265int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
d84f4f99 1266 unsigned long arg4, unsigned long arg5)
3898b1b4 1267{
6d6f3328 1268 const struct cred *old = current_cred();
d84f4f99 1269 struct cred *new;
d84f4f99 1270
3898b1b4
AM
1271 switch (option) {
1272 case PR_CAPBSET_READ:
1273 if (!cap_valid(arg2))
6d6f3328
TH
1274 return -EINVAL;
1275 return !!cap_raised(old->cap_bset, arg2);
d84f4f99 1276
3898b1b4 1277 case PR_CAPBSET_DROP:
6d6f3328 1278 return cap_prctl_drop(arg2);
3898b1b4
AM
1279
1280 /*
1281 * The next four prctl's remain to assist with transitioning a
1282 * system from legacy UID=0 based privilege (when filesystem
1283 * capabilities are not in use) to a system using filesystem
1284 * capabilities only - as the POSIX.1e draft intended.
1285 *
1286 * Note:
1287 *
1288 * PR_SET_SECUREBITS =
1289 * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
1290 * | issecure_mask(SECURE_NOROOT)
1291 * | issecure_mask(SECURE_NOROOT_LOCKED)
1292 * | issecure_mask(SECURE_NO_SETUID_FIXUP)
1293 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
1294 *
1295 * will ensure that the current process and all of its
1296 * children will be locked into a pure
1297 * capability-based-privilege environment.
1298 */
1299 case PR_SET_SECUREBITS:
6d6f3328
TH
1300 if ((((old->securebits & SECURE_ALL_LOCKS) >> 1)
1301 & (old->securebits ^ arg2)) /*[1]*/
1302 || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/
d84f4f99 1303 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
6a9de491 1304 || (cap_capable(current_cred(),
c1a85a00
MM
1305 current_cred()->user_ns,
1306 CAP_SETPCAP,
1307 CAP_OPT_NONE) != 0) /*[4]*/
3898b1b4
AM
1308 /*
1309 * [1] no changing of bits that are locked
1310 * [2] no unlocking of locks
1311 * [3] no setting of unsupported bits
1312 * [4] doing anything requires privilege (go read about
1313 * the "sendmail capabilities bug")
1314 */
d84f4f99
DH
1315 )
1316 /* cannot change a locked bit */
6d6f3328
TH
1317 return -EPERM;
1318
1319 new = prepare_creds();
1320 if (!new)
1321 return -ENOMEM;
d84f4f99 1322 new->securebits = arg2;
6d6f3328 1323 return commit_creds(new);
d84f4f99 1324
3898b1b4 1325 case PR_GET_SECUREBITS:
6d6f3328 1326 return old->securebits;
3898b1b4 1327
3898b1b4 1328 case PR_GET_KEEPCAPS:
6d6f3328 1329 return !!issecure(SECURE_KEEP_CAPS);
d84f4f99 1330
3898b1b4
AM
1331 case PR_SET_KEEPCAPS:
1332 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
6d6f3328 1333 return -EINVAL;
d84f4f99 1334 if (issecure(SECURE_KEEP_CAPS_LOCKED))
6d6f3328
TH
1335 return -EPERM;
1336
1337 new = prepare_creds();
1338 if (!new)
1339 return -ENOMEM;
d84f4f99
DH
1340 if (arg2)
1341 new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
3898b1b4 1342 else
d84f4f99 1343 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
6d6f3328 1344 return commit_creds(new);
3898b1b4 1345
58319057
AL
1346 case PR_CAP_AMBIENT:
1347 if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) {
1348 if (arg3 | arg4 | arg5)
1349 return -EINVAL;
1350
1351 new = prepare_creds();
1352 if (!new)
1353 return -ENOMEM;
1354 cap_clear(new->cap_ambient);
1355 return commit_creds(new);
1356 }
1357
1358 if (((!cap_valid(arg3)) | arg4 | arg5))
1359 return -EINVAL;
1360
1361 if (arg2 == PR_CAP_AMBIENT_IS_SET) {
1362 return !!cap_raised(current_cred()->cap_ambient, arg3);
1363 } else if (arg2 != PR_CAP_AMBIENT_RAISE &&
1364 arg2 != PR_CAP_AMBIENT_LOWER) {
1365 return -EINVAL;
1366 } else {
1367 if (arg2 == PR_CAP_AMBIENT_RAISE &&
1368 (!cap_raised(current_cred()->cap_permitted, arg3) ||
1369 !cap_raised(current_cred()->cap_inheritable,
746bf6d6
AL
1370 arg3) ||
1371 issecure(SECURE_NO_CAP_AMBIENT_RAISE)))
58319057
AL
1372 return -EPERM;
1373
1374 new = prepare_creds();
1375 if (!new)
1376 return -ENOMEM;
1377 if (arg2 == PR_CAP_AMBIENT_RAISE)
1378 cap_raise(new->cap_ambient, arg3);
1379 else
1380 cap_lower(new->cap_ambient, arg3);
1381 return commit_creds(new);
1382 }
1383
3898b1b4
AM
1384 default:
1385 /* No functionality available - continue with default */
6d6f3328 1386 return -ENOSYS;
3898b1b4 1387 }
1da177e4
LT
1388}
1389
1d045980
DH
1390/**
1391 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
1392 * @mm: The VM space in which the new mapping is to be made
1393 * @pages: The size of the mapping
1394 *
1395 * Determine whether the allocation of a new virtual mapping by the current
b1d9e6b0 1396 * task is permitted, returning 1 if permission is granted, 0 if not.
1d045980 1397 */
34b4e4aa 1398int cap_vm_enough_memory(struct mm_struct *mm, long pages)
1da177e4
LT
1399{
1400 int cap_sys_admin = 0;
1401
c1a85a00
MM
1402 if (cap_capable(current_cred(), &init_user_ns,
1403 CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0)
1da177e4 1404 cap_sys_admin = 1;
c1a85a00 1405
b1d9e6b0 1406 return cap_sys_admin;
1da177e4 1407}
7c73875e
EP
1408
1409/*
d007794a 1410 * cap_mmap_addr - check if able to map given addr
7c73875e 1411 * @addr: address attempting to be mapped
7c73875e 1412 *
6f262d8e 1413 * If the process is attempting to map memory below dac_mmap_min_addr they need
7c73875e
EP
1414 * CAP_SYS_RAWIO. The other parameters to this function are unused by the
1415 * capability security module. Returns 0 if this mapping should be allowed
1416 * -EPERM if not.
1417 */
d007794a 1418int cap_mmap_addr(unsigned long addr)
7c73875e
EP
1419{
1420 int ret = 0;
1421
a2551df7 1422 if (addr < dac_mmap_min_addr) {
6a9de491 1423 ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
c1a85a00 1424 CAP_OPT_NONE);
7c73875e
EP
1425 /* set PF_SUPERPRIV if it turns out we allow the low mmap */
1426 if (ret == 0)
1427 current->flags |= PF_SUPERPRIV;
1428 }
1429 return ret;
1430}
d007794a 1431
e5467859
AV
1432int cap_mmap_file(struct file *file, unsigned long reqprot,
1433 unsigned long prot, unsigned long flags)
d007794a 1434{
e5467859 1435 return 0;
d007794a 1436}
b1d9e6b0
CS
1437
1438#ifdef CONFIG_SECURITY
1439
d1c5947e 1440static struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
b1d9e6b0
CS
1441 LSM_HOOK_INIT(capable, cap_capable),
1442 LSM_HOOK_INIT(settime, cap_settime),
1443 LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
1444 LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
1445 LSM_HOOK_INIT(capget, cap_capget),
1446 LSM_HOOK_INIT(capset, cap_capset),
56305aa9 1447 LSM_HOOK_INIT(bprm_creds_from_file, cap_bprm_creds_from_file),
b1d9e6b0
CS
1448 LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
1449 LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
8db6c34f 1450 LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity),
b1d9e6b0
CS
1451 LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
1452 LSM_HOOK_INIT(mmap_file, cap_mmap_file),
1453 LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
1454 LSM_HOOK_INIT(task_prctl, cap_task_prctl),
1455 LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler),
1456 LSM_HOOK_INIT(task_setioprio, cap_task_setioprio),
1457 LSM_HOOK_INIT(task_setnice, cap_task_setnice),
1458 LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
1459};
1460
d117a154 1461static int __init capability_init(void)
b1d9e6b0 1462{
d69dece5
CS
1463 security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
1464 "capability");
d117a154 1465 return 0;
b1d9e6b0
CS
1466}
1467
d117a154
KC
1468DEFINE_LSM(capability) = {
1469 .name = "capability",
1470 .order = LSM_ORDER_FIRST,
1471 .init = capability_init,
1472};
1473
b1d9e6b0 1474#endif /* CONFIG_SECURITY */