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