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TOMOYO Linux Cross Reference
Linux/security/commoncap.c

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

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