xref: /linux/security/commoncap.c (revision fd639726bf15fca8ee1a00dce8e0096d0ad9bd18)
1 /* Common capabilities, needed by capability.o.
2  *
3  *	This program is free software; you can redistribute it and/or modify
4  *	it under the terms of the GNU General Public License as published by
5  *	the Free Software Foundation; either version 2 of the License, or
6  *	(at your option) any later version.
7  *
8  */
9 
10 #include <linux/capability.h>
11 #include <linux/audit.h>
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/lsm_hooks.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>
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>
26 #include <linux/mount.h>
27 #include <linux/sched.h>
28 #include <linux/prctl.h>
29 #include <linux/securebits.h>
30 #include <linux/user_namespace.h>
31 #include <linux/binfmts.h>
32 #include <linux/personality.h>
33 
34 /*
35  * If a non-root user executes a setuid-root binary in
36  * !secure(SECURE_NOROOT) mode, then we raise capabilities.
37  * However if fE is also set, then the intent is for only
38  * the file capabilities to be applied, and the setuid-root
39  * bit is left on either to change the uid (plausible) or
40  * to get full privilege on a kernel without file capabilities
41  * support.  So in that case we do not raise capabilities.
42  *
43  * Warn if that happens, once per boot.
44  */
45 static void warn_setuid_and_fcaps_mixed(const char *fname)
46 {
47 	static int warned;
48 	if (!warned) {
49 		printk(KERN_INFO "warning: `%s' has both setuid-root and"
50 			" effective capabilities. Therefore not raising all"
51 			" capabilities.\n", fname);
52 		warned = 1;
53 	}
54 }
55 
56 /**
57  * cap_capable - Determine whether a task has a particular effective capability
58  * @cred: The credentials to use
59  * @ns:  The user namespace in which we need the capability
60  * @cap: The capability to check for
61  * @audit: Whether to write an audit message or not
62  *
63  * Determine whether the nominated task has the specified capability amongst
64  * its effective set, returning 0 if it does, -ve if it does not.
65  *
66  * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
67  * and has_capability() functions.  That is, it has the reverse semantics:
68  * cap_has_capability() returns 0 when a task has a capability, but the
69  * kernel's capable() and has_capability() returns 1 for this case.
70  */
71 int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
72 		int cap, int audit)
73 {
74 	struct user_namespace *ns = targ_ns;
75 
76 	/* See if cred has the capability in the target user namespace
77 	 * by examining the target user namespace and all of the target
78 	 * user namespace's parents.
79 	 */
80 	for (;;) {
81 		/* Do we have the necessary capabilities? */
82 		if (ns == cred->user_ns)
83 			return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
84 
85 		/*
86 		 * If we're already at a lower level than we're looking for,
87 		 * we're done searching.
88 		 */
89 		if (ns->level <= cred->user_ns->level)
90 			return -EPERM;
91 
92 		/*
93 		 * The owner of the user namespace in the parent of the
94 		 * user namespace has all caps.
95 		 */
96 		if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
97 			return 0;
98 
99 		/*
100 		 * If you have a capability in a parent user ns, then you have
101 		 * it over all children user namespaces as well.
102 		 */
103 		ns = ns->parent;
104 	}
105 
106 	/* We never get here */
107 }
108 
109 /**
110  * cap_settime - Determine whether the current process may set the system clock
111  * @ts: The time to set
112  * @tz: The timezone to set
113  *
114  * Determine whether the current process may set the system clock and timezone
115  * information, returning 0 if permission granted, -ve if denied.
116  */
117 int cap_settime(const struct timespec64 *ts, const struct timezone *tz)
118 {
119 	if (!capable(CAP_SYS_TIME))
120 		return -EPERM;
121 	return 0;
122 }
123 
124 /**
125  * cap_ptrace_access_check - Determine whether the current process may access
126  *			   another
127  * @child: The process to be accessed
128  * @mode: The mode of attachment.
129  *
130  * If we are in the same or an ancestor user_ns and have all the target
131  * task's capabilities, then ptrace access is allowed.
132  * If we have the ptrace capability to the target user_ns, then ptrace
133  * access is allowed.
134  * Else denied.
135  *
136  * Determine whether a process may access another, returning 0 if permission
137  * granted, -ve if denied.
138  */
139 int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
140 {
141 	int ret = 0;
142 	const struct cred *cred, *child_cred;
143 	const kernel_cap_t *caller_caps;
144 
145 	rcu_read_lock();
146 	cred = current_cred();
147 	child_cred = __task_cred(child);
148 	if (mode & PTRACE_MODE_FSCREDS)
149 		caller_caps = &cred->cap_effective;
150 	else
151 		caller_caps = &cred->cap_permitted;
152 	if (cred->user_ns == child_cred->user_ns &&
153 	    cap_issubset(child_cred->cap_permitted, *caller_caps))
154 		goto out;
155 	if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE))
156 		goto out;
157 	ret = -EPERM;
158 out:
159 	rcu_read_unlock();
160 	return ret;
161 }
162 
163 /**
164  * cap_ptrace_traceme - Determine whether another process may trace the current
165  * @parent: The task proposed to be the tracer
166  *
167  * If parent is in the same or an ancestor user_ns and has all current's
168  * capabilities, then ptrace access is allowed.
169  * If parent has the ptrace capability to current's user_ns, then ptrace
170  * access is allowed.
171  * Else denied.
172  *
173  * Determine whether the nominated task is permitted to trace the current
174  * process, returning 0 if permission is granted, -ve if denied.
175  */
176 int cap_ptrace_traceme(struct task_struct *parent)
177 {
178 	int ret = 0;
179 	const struct cred *cred, *child_cred;
180 
181 	rcu_read_lock();
182 	cred = __task_cred(parent);
183 	child_cred = current_cred();
184 	if (cred->user_ns == child_cred->user_ns &&
185 	    cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
186 		goto out;
187 	if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE))
188 		goto out;
189 	ret = -EPERM;
190 out:
191 	rcu_read_unlock();
192 	return ret;
193 }
194 
195 /**
196  * cap_capget - Retrieve a task's capability sets
197  * @target: The task from which to retrieve the capability sets
198  * @effective: The place to record the effective set
199  * @inheritable: The place to record the inheritable set
200  * @permitted: The place to record the permitted set
201  *
202  * This function retrieves the capabilities of the nominated task and returns
203  * them to the caller.
204  */
205 int cap_capget(struct task_struct *target, kernel_cap_t *effective,
206 	       kernel_cap_t *inheritable, kernel_cap_t *permitted)
207 {
208 	const struct cred *cred;
209 
210 	/* Derived from kernel/capability.c:sys_capget. */
211 	rcu_read_lock();
212 	cred = __task_cred(target);
213 	*effective   = cred->cap_effective;
214 	*inheritable = cred->cap_inheritable;
215 	*permitted   = cred->cap_permitted;
216 	rcu_read_unlock();
217 	return 0;
218 }
219 
220 /*
221  * Determine whether the inheritable capabilities are limited to the old
222  * permitted set.  Returns 1 if they are limited, 0 if they are not.
223  */
224 static inline int cap_inh_is_capped(void)
225 {
226 
227 	/* they are so limited unless the current task has the CAP_SETPCAP
228 	 * capability
229 	 */
230 	if (cap_capable(current_cred(), current_cred()->user_ns,
231 			CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
232 		return 0;
233 	return 1;
234 }
235 
236 /**
237  * cap_capset - Validate and apply proposed changes to current's capabilities
238  * @new: The proposed new credentials; alterations should be made here
239  * @old: The current task's current credentials
240  * @effective: A pointer to the proposed new effective capabilities set
241  * @inheritable: A pointer to the proposed new inheritable capabilities set
242  * @permitted: A pointer to the proposed new permitted capabilities set
243  *
244  * This function validates and applies a proposed mass change to the current
245  * process's capability sets.  The changes are made to the proposed new
246  * credentials, and assuming no error, will be committed by the caller of LSM.
247  */
248 int cap_capset(struct cred *new,
249 	       const struct cred *old,
250 	       const kernel_cap_t *effective,
251 	       const kernel_cap_t *inheritable,
252 	       const kernel_cap_t *permitted)
253 {
254 	if (cap_inh_is_capped() &&
255 	    !cap_issubset(*inheritable,
256 			  cap_combine(old->cap_inheritable,
257 				      old->cap_permitted)))
258 		/* incapable of using this inheritable set */
259 		return -EPERM;
260 
261 	if (!cap_issubset(*inheritable,
262 			  cap_combine(old->cap_inheritable,
263 				      old->cap_bset)))
264 		/* no new pI capabilities outside bounding set */
265 		return -EPERM;
266 
267 	/* verify restrictions on target's new Permitted set */
268 	if (!cap_issubset(*permitted, old->cap_permitted))
269 		return -EPERM;
270 
271 	/* verify the _new_Effective_ is a subset of the _new_Permitted_ */
272 	if (!cap_issubset(*effective, *permitted))
273 		return -EPERM;
274 
275 	new->cap_effective   = *effective;
276 	new->cap_inheritable = *inheritable;
277 	new->cap_permitted   = *permitted;
278 
279 	/*
280 	 * Mask off ambient bits that are no longer both permitted and
281 	 * inheritable.
282 	 */
283 	new->cap_ambient = cap_intersect(new->cap_ambient,
284 					 cap_intersect(*permitted,
285 						       *inheritable));
286 	if (WARN_ON(!cap_ambient_invariant_ok(new)))
287 		return -EINVAL;
288 	return 0;
289 }
290 
291 /**
292  * cap_inode_need_killpriv - Determine if inode change affects privileges
293  * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
294  *
295  * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
296  * affects the security markings on that inode, and if it is, should
297  * inode_killpriv() be invoked or the change rejected.
298  *
299  * Returns 1 if security.capability has a value, meaning inode_killpriv()
300  * is required, 0 otherwise, meaning inode_killpriv() is not required.
301  */
302 int cap_inode_need_killpriv(struct dentry *dentry)
303 {
304 	struct inode *inode = d_backing_inode(dentry);
305 	int error;
306 
307 	error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0);
308 	return error > 0;
309 }
310 
311 /**
312  * cap_inode_killpriv - Erase the security markings on an inode
313  * @dentry: The inode/dentry to alter
314  *
315  * Erase the privilege-enhancing security markings on an inode.
316  *
317  * Returns 0 if successful, -ve on error.
318  */
319 int cap_inode_killpriv(struct dentry *dentry)
320 {
321 	int error;
322 
323 	error = __vfs_removexattr(dentry, XATTR_NAME_CAPS);
324 	if (error == -EOPNOTSUPP)
325 		error = 0;
326 	return error;
327 }
328 
329 static bool rootid_owns_currentns(kuid_t kroot)
330 {
331 	struct user_namespace *ns;
332 
333 	if (!uid_valid(kroot))
334 		return false;
335 
336 	for (ns = current_user_ns(); ; ns = ns->parent) {
337 		if (from_kuid(ns, kroot) == 0)
338 			return true;
339 		if (ns == &init_user_ns)
340 			break;
341 	}
342 
343 	return false;
344 }
345 
346 static __u32 sansflags(__u32 m)
347 {
348 	return m & ~VFS_CAP_FLAGS_EFFECTIVE;
349 }
350 
351 static bool is_v2header(size_t size, __le32 magic)
352 {
353 	__u32 m = le32_to_cpu(magic);
354 	if (size != XATTR_CAPS_SZ_2)
355 		return false;
356 	return sansflags(m) == VFS_CAP_REVISION_2;
357 }
358 
359 static bool is_v3header(size_t size, __le32 magic)
360 {
361 	__u32 m = le32_to_cpu(magic);
362 
363 	if (size != XATTR_CAPS_SZ_3)
364 		return false;
365 	return sansflags(m) == VFS_CAP_REVISION_3;
366 }
367 
368 /*
369  * getsecurity: We are called for security.* before any attempt to read the
370  * xattr from the inode itself.
371  *
372  * This gives us a chance to read the on-disk value and convert it.  If we
373  * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler.
374  *
375  * Note we are not called by vfs_getxattr_alloc(), but that is only called
376  * by the integrity subsystem, which really wants the unconverted values -
377  * so that's good.
378  */
379 int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
380 			  bool alloc)
381 {
382 	int size, ret;
383 	kuid_t kroot;
384 	uid_t root, mappedroot;
385 	char *tmpbuf = NULL;
386 	struct vfs_cap_data *cap;
387 	struct vfs_ns_cap_data *nscap;
388 	struct dentry *dentry;
389 	struct user_namespace *fs_ns;
390 
391 	if (strcmp(name, "capability") != 0)
392 		return -EOPNOTSUPP;
393 
394 	dentry = d_find_alias(inode);
395 	if (!dentry)
396 		return -EINVAL;
397 
398 	size = sizeof(struct vfs_ns_cap_data);
399 	ret = (int) vfs_getxattr_alloc(dentry, XATTR_NAME_CAPS,
400 				 &tmpbuf, size, GFP_NOFS);
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;
408 	if (is_v2header((size_t) ret, cap->magic_etc)) {
409 		/* If this is sizeof(vfs_cap_data) then we're ok with the
410 		 * on-disk value, so return that.  */
411 		if (alloc)
412 			*buffer = tmpbuf;
413 		else
414 			kfree(tmpbuf);
415 		return ret;
416 	} else if (!is_v3header((size_t) ret, cap->magic_etc)) {
417 		kfree(tmpbuf);
418 		return -EINVAL;
419 	}
420 
421 	nscap = (struct vfs_ns_cap_data *) tmpbuf;
422 	root = le32_to_cpu(nscap->rootid);
423 	kroot = make_kuid(fs_ns, root);
424 
425 	/* If the root kuid maps to a valid uid in current ns, then return
426 	 * this as a nscap. */
427 	mappedroot = from_kuid(current_user_ns(), kroot);
428 	if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) {
429 		if (alloc) {
430 			*buffer = tmpbuf;
431 			nscap->rootid = cpu_to_le32(mappedroot);
432 		} else
433 			kfree(tmpbuf);
434 		return size;
435 	}
436 
437 	if (!rootid_owns_currentns(kroot)) {
438 		kfree(tmpbuf);
439 		return -EOPNOTSUPP;
440 	}
441 
442 	/* This comes from a parent namespace.  Return as a v2 capability */
443 	size = sizeof(struct vfs_cap_data);
444 	if (alloc) {
445 		*buffer = kmalloc(size, GFP_ATOMIC);
446 		if (*buffer) {
447 			struct vfs_cap_data *cap = *buffer;
448 			__le32 nsmagic, magic;
449 			magic = VFS_CAP_REVISION_2;
450 			nsmagic = le32_to_cpu(nscap->magic_etc);
451 			if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE)
452 				magic |= VFS_CAP_FLAGS_EFFECTIVE;
453 			memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
454 			cap->magic_etc = cpu_to_le32(magic);
455 		}
456 	}
457 	kfree(tmpbuf);
458 	return size;
459 }
460 
461 static kuid_t rootid_from_xattr(const void *value, size_t size,
462 				struct user_namespace *task_ns)
463 {
464 	const struct vfs_ns_cap_data *nscap = value;
465 	uid_t rootid = 0;
466 
467 	if (size == XATTR_CAPS_SZ_3)
468 		rootid = le32_to_cpu(nscap->rootid);
469 
470 	return make_kuid(task_ns, rootid);
471 }
472 
473 static bool validheader(size_t size, __le32 magic)
474 {
475 	return is_v2header(size, magic) || is_v3header(size, magic);
476 }
477 
478 /*
479  * User requested a write of security.capability.  If needed, update the
480  * xattr to change from v2 to v3, or to fixup the v3 rootid.
481  *
482  * If all is ok, we return the new size, on error return < 0.
483  */
484 int cap_convert_nscap(struct dentry *dentry, void **ivalue, size_t size)
485 {
486 	struct vfs_ns_cap_data *nscap;
487 	uid_t nsrootid;
488 	const struct vfs_cap_data *cap = *ivalue;
489 	__u32 magic, nsmagic;
490 	struct inode *inode = d_backing_inode(dentry);
491 	struct user_namespace *task_ns = current_user_ns(),
492 		*fs_ns = inode->i_sb->s_user_ns;
493 	kuid_t rootid;
494 	size_t newsize;
495 
496 	if (!*ivalue)
497 		return -EINVAL;
498 	if (!validheader(size, cap->magic_etc))
499 		return -EINVAL;
500 	if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
501 		return -EPERM;
502 	if (size == XATTR_CAPS_SZ_2)
503 		if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP))
504 			/* user is privileged, just write the v2 */
505 			return size;
506 
507 	rootid = rootid_from_xattr(*ivalue, size, task_ns);
508 	if (!uid_valid(rootid))
509 		return -EINVAL;
510 
511 	nsrootid = from_kuid(fs_ns, rootid);
512 	if (nsrootid == -1)
513 		return -EINVAL;
514 
515 	newsize = sizeof(struct vfs_ns_cap_data);
516 	nscap = kmalloc(newsize, GFP_ATOMIC);
517 	if (!nscap)
518 		return -ENOMEM;
519 	nscap->rootid = cpu_to_le32(nsrootid);
520 	nsmagic = VFS_CAP_REVISION_3;
521 	magic = le32_to_cpu(cap->magic_etc);
522 	if (magic & VFS_CAP_FLAGS_EFFECTIVE)
523 		nsmagic |= VFS_CAP_FLAGS_EFFECTIVE;
524 	nscap->magic_etc = cpu_to_le32(nsmagic);
525 	memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
526 
527 	kvfree(*ivalue);
528 	*ivalue = nscap;
529 	return newsize;
530 }
531 
532 /*
533  * Calculate the new process capability sets from the capability sets attached
534  * to a file.
535  */
536 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
537 					  struct linux_binprm *bprm,
538 					  bool *effective,
539 					  bool *has_fcap)
540 {
541 	struct cred *new = bprm->cred;
542 	unsigned i;
543 	int ret = 0;
544 
545 	if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
546 		*effective = true;
547 
548 	if (caps->magic_etc & VFS_CAP_REVISION_MASK)
549 		*has_fcap = true;
550 
551 	CAP_FOR_EACH_U32(i) {
552 		__u32 permitted = caps->permitted.cap[i];
553 		__u32 inheritable = caps->inheritable.cap[i];
554 
555 		/*
556 		 * pP' = (X & fP) | (pI & fI)
557 		 * The addition of pA' is handled later.
558 		 */
559 		new->cap_permitted.cap[i] =
560 			(new->cap_bset.cap[i] & permitted) |
561 			(new->cap_inheritable.cap[i] & inheritable);
562 
563 		if (permitted & ~new->cap_permitted.cap[i])
564 			/* insufficient to execute correctly */
565 			ret = -EPERM;
566 	}
567 
568 	/*
569 	 * For legacy apps, with no internal support for recognizing they
570 	 * do not have enough capabilities, we return an error if they are
571 	 * missing some "forced" (aka file-permitted) capabilities.
572 	 */
573 	return *effective ? ret : 0;
574 }
575 
576 /*
577  * Extract the on-exec-apply capability sets for an executable file.
578  */
579 int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
580 {
581 	struct inode *inode = d_backing_inode(dentry);
582 	__u32 magic_etc;
583 	unsigned tocopy, i;
584 	int size;
585 	struct vfs_ns_cap_data data, *nscaps = &data;
586 	struct vfs_cap_data *caps = (struct vfs_cap_data *) &data;
587 	kuid_t rootkuid;
588 	struct user_namespace *fs_ns;
589 
590 	memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
591 
592 	if (!inode)
593 		return -ENODATA;
594 
595 	fs_ns = inode->i_sb->s_user_ns;
596 	size = __vfs_getxattr((struct dentry *)dentry, inode,
597 			      XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ);
598 	if (size == -ENODATA || size == -EOPNOTSUPP)
599 		/* no data, that's ok */
600 		return -ENODATA;
601 
602 	if (size < 0)
603 		return size;
604 
605 	if (size < sizeof(magic_etc))
606 		return -EINVAL;
607 
608 	cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc);
609 
610 	rootkuid = make_kuid(fs_ns, 0);
611 	switch (magic_etc & VFS_CAP_REVISION_MASK) {
612 	case VFS_CAP_REVISION_1:
613 		if (size != XATTR_CAPS_SZ_1)
614 			return -EINVAL;
615 		tocopy = VFS_CAP_U32_1;
616 		break;
617 	case VFS_CAP_REVISION_2:
618 		if (size != XATTR_CAPS_SZ_2)
619 			return -EINVAL;
620 		tocopy = VFS_CAP_U32_2;
621 		break;
622 	case VFS_CAP_REVISION_3:
623 		if (size != XATTR_CAPS_SZ_3)
624 			return -EINVAL;
625 		tocopy = VFS_CAP_U32_3;
626 		rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid));
627 		break;
628 
629 	default:
630 		return -EINVAL;
631 	}
632 	/* Limit the caps to the mounter of the filesystem
633 	 * or the more limited uid specified in the xattr.
634 	 */
635 	if (!rootid_owns_currentns(rootkuid))
636 		return -ENODATA;
637 
638 	CAP_FOR_EACH_U32(i) {
639 		if (i >= tocopy)
640 			break;
641 		cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted);
642 		cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable);
643 	}
644 
645 	cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
646 	cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
647 
648 	return 0;
649 }
650 
651 /*
652  * Attempt to get the on-exec apply capability sets for an executable file from
653  * its xattrs and, if present, apply them to the proposed credentials being
654  * constructed by execve().
655  */
656 static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_fcap)
657 {
658 	int rc = 0;
659 	struct cpu_vfs_cap_data vcaps;
660 
661 	cap_clear(bprm->cred->cap_permitted);
662 
663 	if (!file_caps_enabled)
664 		return 0;
665 
666 	if (!mnt_may_suid(bprm->file->f_path.mnt))
667 		return 0;
668 
669 	/*
670 	 * This check is redundant with mnt_may_suid() but is kept to make
671 	 * explicit that capability bits are limited to s_user_ns and its
672 	 * descendants.
673 	 */
674 	if (!current_in_userns(bprm->file->f_path.mnt->mnt_sb->s_user_ns))
675 		return 0;
676 
677 	rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps);
678 	if (rc < 0) {
679 		if (rc == -EINVAL)
680 			printk(KERN_NOTICE "Invalid argument reading file caps for %s\n",
681 					bprm->filename);
682 		else if (rc == -ENODATA)
683 			rc = 0;
684 		goto out;
685 	}
686 
687 	rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap);
688 	if (rc == -EINVAL)
689 		printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
690 		       __func__, rc, bprm->filename);
691 
692 out:
693 	if (rc)
694 		cap_clear(bprm->cred->cap_permitted);
695 
696 	return rc;
697 }
698 
699 static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); }
700 
701 static inline bool __is_real(kuid_t uid, struct cred *cred)
702 { return uid_eq(cred->uid, uid); }
703 
704 static inline bool __is_eff(kuid_t uid, struct cred *cred)
705 { return uid_eq(cred->euid, uid); }
706 
707 static inline bool __is_suid(kuid_t uid, struct cred *cred)
708 { return !__is_real(uid, cred) && __is_eff(uid, cred); }
709 
710 /*
711  * handle_privileged_root - Handle case of privileged root
712  * @bprm: The execution parameters, including the proposed creds
713  * @has_fcap: Are any file capabilities set?
714  * @effective: Do we have effective root privilege?
715  * @root_uid: This namespace' root UID WRT initial USER namespace
716  *
717  * Handle the case where root is privileged and hasn't been neutered by
718  * SECURE_NOROOT.  If file capabilities are set, they won't be combined with
719  * set UID root and nothing is changed.  If we are root, cap_permitted is
720  * updated.  If we have become set UID root, the effective bit is set.
721  */
722 static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap,
723 				   bool *effective, kuid_t root_uid)
724 {
725 	const struct cred *old = current_cred();
726 	struct cred *new = bprm->cred;
727 
728 	if (!root_privileged())
729 		return;
730 	/*
731 	 * If the legacy file capability is set, then don't set privs
732 	 * for a setuid root binary run by a non-root user.  Do set it
733 	 * for a root user just to cause least surprise to an admin.
734 	 */
735 	if (has_fcap && __is_suid(root_uid, new)) {
736 		warn_setuid_and_fcaps_mixed(bprm->filename);
737 		return;
738 	}
739 	/*
740 	 * To support inheritance of root-permissions and suid-root
741 	 * executables under compatibility mode, we override the
742 	 * capability sets for the file.
743 	 */
744 	if (__is_eff(root_uid, new) || __is_real(root_uid, new)) {
745 		/* pP' = (cap_bset & ~0) | (pI & ~0) */
746 		new->cap_permitted = cap_combine(old->cap_bset,
747 						 old->cap_inheritable);
748 	}
749 	/*
750 	 * If only the real uid is 0, we do not set the effective bit.
751 	 */
752 	if (__is_eff(root_uid, new))
753 		*effective = true;
754 }
755 
756 #define __cap_gained(field, target, source) \
757 	!cap_issubset(target->cap_##field, source->cap_##field)
758 #define __cap_grew(target, source, cred) \
759 	!cap_issubset(cred->cap_##target, cred->cap_##source)
760 #define __cap_full(field, cred) \
761 	cap_issubset(CAP_FULL_SET, cred->cap_##field)
762 
763 static inline bool __is_setuid(struct cred *new, const struct cred *old)
764 { return !uid_eq(new->euid, old->uid); }
765 
766 static inline bool __is_setgid(struct cred *new, const struct cred *old)
767 { return !gid_eq(new->egid, old->gid); }
768 
769 /*
770  * 1) Audit candidate if current->cap_effective is set
771  *
772  * We do not bother to audit if 3 things are true:
773  *   1) cap_effective has all caps
774  *   2) we became root *OR* are were already root
775  *   3) root is supposed to have all caps (SECURE_NOROOT)
776  * Since this is just a normal root execing a process.
777  *
778  * Number 1 above might fail if you don't have a full bset, but I think
779  * that is interesting information to audit.
780  *
781  * A number of other conditions require logging:
782  * 2) something prevented setuid root getting all caps
783  * 3) non-setuid root gets fcaps
784  * 4) non-setuid root gets ambient
785  */
786 static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old,
787 				     kuid_t root, bool has_fcap)
788 {
789 	bool ret = false;
790 
791 	if ((__cap_grew(effective, ambient, new) &&
792 	     !(__cap_full(effective, new) &&
793 	       (__is_eff(root, new) || __is_real(root, new)) &&
794 	       root_privileged())) ||
795 	    (root_privileged() &&
796 	     __is_suid(root, new) &&
797 	     !__cap_full(effective, new)) ||
798 	    (!__is_setuid(new, old) &&
799 	     ((has_fcap &&
800 	       __cap_gained(permitted, new, old)) ||
801 	      __cap_gained(ambient, new, old))))
802 
803 		ret = true;
804 
805 	return ret;
806 }
807 
808 /**
809  * cap_bprm_set_creds - Set up the proposed credentials for execve().
810  * @bprm: The execution parameters, including the proposed creds
811  *
812  * Set up the proposed credentials for a new execution context being
813  * constructed by execve().  The proposed creds in @bprm->cred is altered,
814  * which won't take effect immediately.  Returns 0 if successful, -ve on error.
815  */
816 int cap_bprm_set_creds(struct linux_binprm *bprm)
817 {
818 	const struct cred *old = current_cred();
819 	struct cred *new = bprm->cred;
820 	bool effective = false, has_fcap = false, is_setid;
821 	int ret;
822 	kuid_t root_uid;
823 
824 	if (WARN_ON(!cap_ambient_invariant_ok(old)))
825 		return -EPERM;
826 
827 	ret = get_file_caps(bprm, &effective, &has_fcap);
828 	if (ret < 0)
829 		return ret;
830 
831 	root_uid = make_kuid(new->user_ns, 0);
832 
833 	handle_privileged_root(bprm, has_fcap, &effective, root_uid);
834 
835 	/* if we have fs caps, clear dangerous personality flags */
836 	if (__cap_gained(permitted, new, old))
837 		bprm->per_clear |= PER_CLEAR_ON_SETID;
838 
839 	/* Don't let someone trace a set[ug]id/setpcap binary with the revised
840 	 * credentials unless they have the appropriate permit.
841 	 *
842 	 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
843 	 */
844 	is_setid = __is_setuid(new, old) || __is_setgid(new, old);
845 
846 	if ((is_setid || __cap_gained(permitted, new, old)) &&
847 	    ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) ||
848 	     !ptracer_capable(current, new->user_ns))) {
849 		/* downgrade; they get no more than they had, and maybe less */
850 		if (!ns_capable(new->user_ns, CAP_SETUID) ||
851 		    (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
852 			new->euid = new->uid;
853 			new->egid = new->gid;
854 		}
855 		new->cap_permitted = cap_intersect(new->cap_permitted,
856 						   old->cap_permitted);
857 	}
858 
859 	new->suid = new->fsuid = new->euid;
860 	new->sgid = new->fsgid = new->egid;
861 
862 	/* File caps or setid cancels ambient. */
863 	if (has_fcap || is_setid)
864 		cap_clear(new->cap_ambient);
865 
866 	/*
867 	 * Now that we've computed pA', update pP' to give:
868 	 *   pP' = (X & fP) | (pI & fI) | pA'
869 	 */
870 	new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient);
871 
872 	/*
873 	 * Set pE' = (fE ? pP' : pA').  Because pA' is zero if fE is set,
874 	 * this is the same as pE' = (fE ? pP' : 0) | pA'.
875 	 */
876 	if (effective)
877 		new->cap_effective = new->cap_permitted;
878 	else
879 		new->cap_effective = new->cap_ambient;
880 
881 	if (WARN_ON(!cap_ambient_invariant_ok(new)))
882 		return -EPERM;
883 
884 	if (nonroot_raised_pE(new, old, root_uid, has_fcap)) {
885 		ret = audit_log_bprm_fcaps(bprm, new, old);
886 		if (ret < 0)
887 			return ret;
888 	}
889 
890 	new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
891 
892 	if (WARN_ON(!cap_ambient_invariant_ok(new)))
893 		return -EPERM;
894 
895 	/* Check for privilege-elevated exec. */
896 	bprm->cap_elevated = 0;
897 	if (is_setid ||
898 	    (!__is_real(root_uid, new) &&
899 	     (effective ||
900 	      __cap_grew(permitted, ambient, new))))
901 		bprm->cap_elevated = 1;
902 
903 	return 0;
904 }
905 
906 /**
907  * cap_inode_setxattr - Determine whether an xattr may be altered
908  * @dentry: The inode/dentry being altered
909  * @name: The name of the xattr to be changed
910  * @value: The value that the xattr will be changed to
911  * @size: The size of value
912  * @flags: The replacement flag
913  *
914  * Determine whether an xattr may be altered or set on an inode, returning 0 if
915  * permission is granted, -ve if denied.
916  *
917  * This is used to make sure security xattrs don't get updated or set by those
918  * who aren't privileged to do so.
919  */
920 int cap_inode_setxattr(struct dentry *dentry, const char *name,
921 		       const void *value, size_t size, int flags)
922 {
923 	/* Ignore non-security xattrs */
924 	if (strncmp(name, XATTR_SECURITY_PREFIX,
925 			sizeof(XATTR_SECURITY_PREFIX) - 1) != 0)
926 		return 0;
927 
928 	/*
929 	 * For XATTR_NAME_CAPS the check will be done in
930 	 * cap_convert_nscap(), called by setxattr()
931 	 */
932 	if (strcmp(name, XATTR_NAME_CAPS) == 0)
933 		return 0;
934 
935 	if (!capable(CAP_SYS_ADMIN))
936 		return -EPERM;
937 	return 0;
938 }
939 
940 /**
941  * cap_inode_removexattr - Determine whether an xattr may be removed
942  * @dentry: The inode/dentry being altered
943  * @name: The name of the xattr to be changed
944  *
945  * Determine whether an xattr may be removed from an inode, returning 0 if
946  * permission is granted, -ve if denied.
947  *
948  * This is used to make sure security xattrs don't get removed by those who
949  * aren't privileged to remove them.
950  */
951 int cap_inode_removexattr(struct dentry *dentry, const char *name)
952 {
953 	/* Ignore non-security xattrs */
954 	if (strncmp(name, XATTR_SECURITY_PREFIX,
955 			sizeof(XATTR_SECURITY_PREFIX) - 1) != 0)
956 		return 0;
957 
958 	if (strcmp(name, XATTR_NAME_CAPS) == 0) {
959 		/* security.capability gets namespaced */
960 		struct inode *inode = d_backing_inode(dentry);
961 		if (!inode)
962 			return -EINVAL;
963 		if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
964 			return -EPERM;
965 		return 0;
966 	}
967 
968 	if (!capable(CAP_SYS_ADMIN))
969 		return -EPERM;
970 	return 0;
971 }
972 
973 /*
974  * cap_emulate_setxuid() fixes the effective / permitted capabilities of
975  * a process after a call to setuid, setreuid, or setresuid.
976  *
977  *  1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
978  *  {r,e,s}uid != 0, the permitted and effective capabilities are
979  *  cleared.
980  *
981  *  2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
982  *  capabilities of the process are cleared.
983  *
984  *  3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
985  *  capabilities are set to the permitted capabilities.
986  *
987  *  fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
988  *  never happen.
989  *
990  *  -astor
991  *
992  * cevans - New behaviour, Oct '99
993  * A process may, via prctl(), elect to keep its capabilities when it
994  * calls setuid() and switches away from uid==0. Both permitted and
995  * effective sets will be retained.
996  * Without this change, it was impossible for a daemon to drop only some
997  * of its privilege. The call to setuid(!=0) would drop all privileges!
998  * Keeping uid 0 is not an option because uid 0 owns too many vital
999  * files..
1000  * Thanks to Olaf Kirch and Peter Benie for spotting this.
1001  */
1002 static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
1003 {
1004 	kuid_t root_uid = make_kuid(old->user_ns, 0);
1005 
1006 	if ((uid_eq(old->uid, root_uid) ||
1007 	     uid_eq(old->euid, root_uid) ||
1008 	     uid_eq(old->suid, root_uid)) &&
1009 	    (!uid_eq(new->uid, root_uid) &&
1010 	     !uid_eq(new->euid, root_uid) &&
1011 	     !uid_eq(new->suid, root_uid))) {
1012 		if (!issecure(SECURE_KEEP_CAPS)) {
1013 			cap_clear(new->cap_permitted);
1014 			cap_clear(new->cap_effective);
1015 		}
1016 
1017 		/*
1018 		 * Pre-ambient programs expect setresuid to nonroot followed
1019 		 * by exec to drop capabilities.  We should make sure that
1020 		 * this remains the case.
1021 		 */
1022 		cap_clear(new->cap_ambient);
1023 	}
1024 	if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
1025 		cap_clear(new->cap_effective);
1026 	if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
1027 		new->cap_effective = new->cap_permitted;
1028 }
1029 
1030 /**
1031  * cap_task_fix_setuid - Fix up the results of setuid() call
1032  * @new: The proposed credentials
1033  * @old: The current task's current credentials
1034  * @flags: Indications of what has changed
1035  *
1036  * Fix up the results of setuid() call before the credential changes are
1037  * actually applied, returning 0 to grant the changes, -ve to deny them.
1038  */
1039 int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
1040 {
1041 	switch (flags) {
1042 	case LSM_SETID_RE:
1043 	case LSM_SETID_ID:
1044 	case LSM_SETID_RES:
1045 		/* juggle the capabilities to follow [RES]UID changes unless
1046 		 * otherwise suppressed */
1047 		if (!issecure(SECURE_NO_SETUID_FIXUP))
1048 			cap_emulate_setxuid(new, old);
1049 		break;
1050 
1051 	case LSM_SETID_FS:
1052 		/* juggle the capabilties to follow FSUID changes, unless
1053 		 * otherwise suppressed
1054 		 *
1055 		 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
1056 		 *          if not, we might be a bit too harsh here.
1057 		 */
1058 		if (!issecure(SECURE_NO_SETUID_FIXUP)) {
1059 			kuid_t root_uid = make_kuid(old->user_ns, 0);
1060 			if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
1061 				new->cap_effective =
1062 					cap_drop_fs_set(new->cap_effective);
1063 
1064 			if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
1065 				new->cap_effective =
1066 					cap_raise_fs_set(new->cap_effective,
1067 							 new->cap_permitted);
1068 		}
1069 		break;
1070 
1071 	default:
1072 		return -EINVAL;
1073 	}
1074 
1075 	return 0;
1076 }
1077 
1078 /*
1079  * Rationale: code calling task_setscheduler, task_setioprio, and
1080  * task_setnice, assumes that
1081  *   . if capable(cap_sys_nice), then those actions should be allowed
1082  *   . if not capable(cap_sys_nice), but acting on your own processes,
1083  *   	then those actions should be allowed
1084  * This is insufficient now since you can call code without suid, but
1085  * yet with increased caps.
1086  * So we check for increased caps on the target process.
1087  */
1088 static int cap_safe_nice(struct task_struct *p)
1089 {
1090 	int is_subset, ret = 0;
1091 
1092 	rcu_read_lock();
1093 	is_subset = cap_issubset(__task_cred(p)->cap_permitted,
1094 				 current_cred()->cap_permitted);
1095 	if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE))
1096 		ret = -EPERM;
1097 	rcu_read_unlock();
1098 
1099 	return ret;
1100 }
1101 
1102 /**
1103  * cap_task_setscheduler - Detemine if scheduler policy change is permitted
1104  * @p: The task to affect
1105  *
1106  * Detemine if the requested scheduler policy change is permitted for the
1107  * specified task, returning 0 if permission is granted, -ve if denied.
1108  */
1109 int cap_task_setscheduler(struct task_struct *p)
1110 {
1111 	return cap_safe_nice(p);
1112 }
1113 
1114 /**
1115  * cap_task_ioprio - Detemine if I/O priority change is permitted
1116  * @p: The task to affect
1117  * @ioprio: The I/O priority to set
1118  *
1119  * Detemine if the requested I/O priority change is permitted for the specified
1120  * task, returning 0 if permission is granted, -ve if denied.
1121  */
1122 int cap_task_setioprio(struct task_struct *p, int ioprio)
1123 {
1124 	return cap_safe_nice(p);
1125 }
1126 
1127 /**
1128  * cap_task_ioprio - Detemine if task priority change is permitted
1129  * @p: The task to affect
1130  * @nice: The nice value to set
1131  *
1132  * Detemine if the requested task priority change is permitted for the
1133  * specified task, returning 0 if permission is granted, -ve if denied.
1134  */
1135 int cap_task_setnice(struct task_struct *p, int nice)
1136 {
1137 	return cap_safe_nice(p);
1138 }
1139 
1140 /*
1141  * Implement PR_CAPBSET_DROP.  Attempt to remove the specified capability from
1142  * the current task's bounding set.  Returns 0 on success, -ve on error.
1143  */
1144 static int cap_prctl_drop(unsigned long cap)
1145 {
1146 	struct cred *new;
1147 
1148 	if (!ns_capable(current_user_ns(), CAP_SETPCAP))
1149 		return -EPERM;
1150 	if (!cap_valid(cap))
1151 		return -EINVAL;
1152 
1153 	new = prepare_creds();
1154 	if (!new)
1155 		return -ENOMEM;
1156 	cap_lower(new->cap_bset, cap);
1157 	return commit_creds(new);
1158 }
1159 
1160 /**
1161  * cap_task_prctl - Implement process control functions for this security module
1162  * @option: The process control function requested
1163  * @arg2, @arg3, @arg4, @arg5: The argument data for this function
1164  *
1165  * Allow process control functions (sys_prctl()) to alter capabilities; may
1166  * also deny access to other functions not otherwise implemented here.
1167  *
1168  * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
1169  * here, other -ve on error.  If -ENOSYS is returned, sys_prctl() and other LSM
1170  * modules will consider performing the function.
1171  */
1172 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
1173 		   unsigned long arg4, unsigned long arg5)
1174 {
1175 	const struct cred *old = current_cred();
1176 	struct cred *new;
1177 
1178 	switch (option) {
1179 	case PR_CAPBSET_READ:
1180 		if (!cap_valid(arg2))
1181 			return -EINVAL;
1182 		return !!cap_raised(old->cap_bset, arg2);
1183 
1184 	case PR_CAPBSET_DROP:
1185 		return cap_prctl_drop(arg2);
1186 
1187 	/*
1188 	 * The next four prctl's remain to assist with transitioning a
1189 	 * system from legacy UID=0 based privilege (when filesystem
1190 	 * capabilities are not in use) to a system using filesystem
1191 	 * capabilities only - as the POSIX.1e draft intended.
1192 	 *
1193 	 * Note:
1194 	 *
1195 	 *  PR_SET_SECUREBITS =
1196 	 *      issecure_mask(SECURE_KEEP_CAPS_LOCKED)
1197 	 *    | issecure_mask(SECURE_NOROOT)
1198 	 *    | issecure_mask(SECURE_NOROOT_LOCKED)
1199 	 *    | issecure_mask(SECURE_NO_SETUID_FIXUP)
1200 	 *    | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
1201 	 *
1202 	 * will ensure that the current process and all of its
1203 	 * children will be locked into a pure
1204 	 * capability-based-privilege environment.
1205 	 */
1206 	case PR_SET_SECUREBITS:
1207 		if ((((old->securebits & SECURE_ALL_LOCKS) >> 1)
1208 		     & (old->securebits ^ arg2))			/*[1]*/
1209 		    || ((old->securebits & SECURE_ALL_LOCKS & ~arg2))	/*[2]*/
1210 		    || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS))	/*[3]*/
1211 		    || (cap_capable(current_cred(),
1212 				    current_cred()->user_ns, CAP_SETPCAP,
1213 				    SECURITY_CAP_AUDIT) != 0)		/*[4]*/
1214 			/*
1215 			 * [1] no changing of bits that are locked
1216 			 * [2] no unlocking of locks
1217 			 * [3] no setting of unsupported bits
1218 			 * [4] doing anything requires privilege (go read about
1219 			 *     the "sendmail capabilities bug")
1220 			 */
1221 		    )
1222 			/* cannot change a locked bit */
1223 			return -EPERM;
1224 
1225 		new = prepare_creds();
1226 		if (!new)
1227 			return -ENOMEM;
1228 		new->securebits = arg2;
1229 		return commit_creds(new);
1230 
1231 	case PR_GET_SECUREBITS:
1232 		return old->securebits;
1233 
1234 	case PR_GET_KEEPCAPS:
1235 		return !!issecure(SECURE_KEEP_CAPS);
1236 
1237 	case PR_SET_KEEPCAPS:
1238 		if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
1239 			return -EINVAL;
1240 		if (issecure(SECURE_KEEP_CAPS_LOCKED))
1241 			return -EPERM;
1242 
1243 		new = prepare_creds();
1244 		if (!new)
1245 			return -ENOMEM;
1246 		if (arg2)
1247 			new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
1248 		else
1249 			new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
1250 		return commit_creds(new);
1251 
1252 	case PR_CAP_AMBIENT:
1253 		if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) {
1254 			if (arg3 | arg4 | arg5)
1255 				return -EINVAL;
1256 
1257 			new = prepare_creds();
1258 			if (!new)
1259 				return -ENOMEM;
1260 			cap_clear(new->cap_ambient);
1261 			return commit_creds(new);
1262 		}
1263 
1264 		if (((!cap_valid(arg3)) | arg4 | arg5))
1265 			return -EINVAL;
1266 
1267 		if (arg2 == PR_CAP_AMBIENT_IS_SET) {
1268 			return !!cap_raised(current_cred()->cap_ambient, arg3);
1269 		} else if (arg2 != PR_CAP_AMBIENT_RAISE &&
1270 			   arg2 != PR_CAP_AMBIENT_LOWER) {
1271 			return -EINVAL;
1272 		} else {
1273 			if (arg2 == PR_CAP_AMBIENT_RAISE &&
1274 			    (!cap_raised(current_cred()->cap_permitted, arg3) ||
1275 			     !cap_raised(current_cred()->cap_inheritable,
1276 					 arg3) ||
1277 			     issecure(SECURE_NO_CAP_AMBIENT_RAISE)))
1278 				return -EPERM;
1279 
1280 			new = prepare_creds();
1281 			if (!new)
1282 				return -ENOMEM;
1283 			if (arg2 == PR_CAP_AMBIENT_RAISE)
1284 				cap_raise(new->cap_ambient, arg3);
1285 			else
1286 				cap_lower(new->cap_ambient, arg3);
1287 			return commit_creds(new);
1288 		}
1289 
1290 	default:
1291 		/* No functionality available - continue with default */
1292 		return -ENOSYS;
1293 	}
1294 }
1295 
1296 /**
1297  * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
1298  * @mm: The VM space in which the new mapping is to be made
1299  * @pages: The size of the mapping
1300  *
1301  * Determine whether the allocation of a new virtual mapping by the current
1302  * task is permitted, returning 1 if permission is granted, 0 if not.
1303  */
1304 int cap_vm_enough_memory(struct mm_struct *mm, long pages)
1305 {
1306 	int cap_sys_admin = 0;
1307 
1308 	if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN,
1309 			SECURITY_CAP_NOAUDIT) == 0)
1310 		cap_sys_admin = 1;
1311 	return cap_sys_admin;
1312 }
1313 
1314 /*
1315  * cap_mmap_addr - check if able to map given addr
1316  * @addr: address attempting to be mapped
1317  *
1318  * If the process is attempting to map memory below dac_mmap_min_addr they need
1319  * CAP_SYS_RAWIO.  The other parameters to this function are unused by the
1320  * capability security module.  Returns 0 if this mapping should be allowed
1321  * -EPERM if not.
1322  */
1323 int cap_mmap_addr(unsigned long addr)
1324 {
1325 	int ret = 0;
1326 
1327 	if (addr < dac_mmap_min_addr) {
1328 		ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
1329 				  SECURITY_CAP_AUDIT);
1330 		/* set PF_SUPERPRIV if it turns out we allow the low mmap */
1331 		if (ret == 0)
1332 			current->flags |= PF_SUPERPRIV;
1333 	}
1334 	return ret;
1335 }
1336 
1337 int cap_mmap_file(struct file *file, unsigned long reqprot,
1338 		  unsigned long prot, unsigned long flags)
1339 {
1340 	return 0;
1341 }
1342 
1343 #ifdef CONFIG_SECURITY
1344 
1345 struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
1346 	LSM_HOOK_INIT(capable, cap_capable),
1347 	LSM_HOOK_INIT(settime, cap_settime),
1348 	LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
1349 	LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
1350 	LSM_HOOK_INIT(capget, cap_capget),
1351 	LSM_HOOK_INIT(capset, cap_capset),
1352 	LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds),
1353 	LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
1354 	LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
1355 	LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity),
1356 	LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
1357 	LSM_HOOK_INIT(mmap_file, cap_mmap_file),
1358 	LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
1359 	LSM_HOOK_INIT(task_prctl, cap_task_prctl),
1360 	LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler),
1361 	LSM_HOOK_INIT(task_setioprio, cap_task_setioprio),
1362 	LSM_HOOK_INIT(task_setnice, cap_task_setnice),
1363 	LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
1364 };
1365 
1366 void __init capability_add_hooks(void)
1367 {
1368 	security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
1369 				"capability");
1370 }
1371 
1372 #endif /* CONFIG_SECURITY */
1373