1 /* Common capabilities, needed by capability.o and root_plug.o
3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
10 #include <linux/capability.h>
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/security.h>
15 #include <linux/file.h>
17 #include <linux/mman.h>
18 #include <linux/pagemap.h>
19 #include <linux/swap.h>
20 #include <linux/skbuff.h>
21 #include <linux/netlink.h>
22 #include <linux/ptrace.h>
23 #include <linux/xattr.h>
24 #include <linux/hugetlb.h>
25 #include <linux/mount.h>
26 #include <linux/sched.h>
27 #include <linux/prctl.h>
28 #include <linux/securebits.h>
30 int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
32 NETLINK_CB(skb).eff_cap = current->cap_effective;
36 int cap_netlink_recv(struct sk_buff *skb, int cap)
38 if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))
43 EXPORT_SYMBOL(cap_netlink_recv);
46 * NOTE WELL: cap_capable() cannot be used like the kernel's capable()
47 * function. That is, it has the reverse semantics: cap_capable()
48 * returns 0 when a task has a capability, but the kernel's capable()
49 * returns 1 for this case.
51 int cap_capable (struct task_struct *tsk, int cap)
53 /* Derived from include/linux/sched.h:capable. */
54 if (cap_raised(tsk->cap_effective, cap))
59 int cap_settime(struct timespec *ts, struct timezone *tz)
61 if (!capable(CAP_SYS_TIME))
66 int cap_ptrace_may_access(struct task_struct *child, unsigned int mode)
68 /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
69 if (cap_issubset(child->cap_permitted, current->cap_permitted))
71 if (capable(CAP_SYS_PTRACE))
76 int cap_ptrace_traceme(struct task_struct *parent)
78 /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
79 if (cap_issubset(current->cap_permitted, parent->cap_permitted))
81 if (has_capability(parent, CAP_SYS_PTRACE))
86 int cap_capget (struct task_struct *target, kernel_cap_t *effective,
87 kernel_cap_t *inheritable, kernel_cap_t *permitted)
89 /* Derived from kernel/capability.c:sys_capget. */
90 *effective = target->cap_effective;
91 *inheritable = target->cap_inheritable;
92 *permitted = target->cap_permitted;
96 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
98 static inline int cap_block_setpcap(struct task_struct *target)
101 * No support for remote process capability manipulation with
102 * filesystem capability support.
104 return (target != current);
107 static inline int cap_inh_is_capped(void)
110 * Return 1 if changes to the inheritable set are limited
111 * to the old permitted set. That is, if the current task
112 * does *not* possess the CAP_SETPCAP capability.
114 return (cap_capable(current, CAP_SETPCAP) != 0);
117 static inline int cap_limit_ptraced_target(void) { return 1; }
119 #else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
121 static inline int cap_block_setpcap(struct task_struct *t) { return 0; }
122 static inline int cap_inh_is_capped(void) { return 1; }
123 static inline int cap_limit_ptraced_target(void)
125 return !capable(CAP_SETPCAP);
128 #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
130 int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
131 kernel_cap_t *inheritable, kernel_cap_t *permitted)
133 if (cap_block_setpcap(target)) {
136 if (cap_inh_is_capped()
137 && !cap_issubset(*inheritable,
138 cap_combine(target->cap_inheritable,
139 current->cap_permitted))) {
140 /* incapable of using this inheritable set */
143 if (!cap_issubset(*inheritable,
144 cap_combine(target->cap_inheritable,
145 current->cap_bset))) {
146 /* no new pI capabilities outside bounding set */
150 /* verify restrictions on target's new Permitted set */
151 if (!cap_issubset (*permitted,
152 cap_combine (target->cap_permitted,
153 current->cap_permitted))) {
157 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
158 if (!cap_issubset (*effective, *permitted)) {
165 void cap_capset_set (struct task_struct *target, kernel_cap_t *effective,
166 kernel_cap_t *inheritable, kernel_cap_t *permitted)
168 target->cap_effective = *effective;
169 target->cap_inheritable = *inheritable;
170 target->cap_permitted = *permitted;
173 static inline void bprm_clear_caps(struct linux_binprm *bprm)
175 cap_clear(bprm->cap_post_exec_permitted);
176 bprm->cap_effective = false;
179 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
181 int cap_inode_need_killpriv(struct dentry *dentry)
183 struct inode *inode = dentry->d_inode;
186 if (!inode->i_op || !inode->i_op->getxattr)
189 error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
195 int cap_inode_killpriv(struct dentry *dentry)
197 struct inode *inode = dentry->d_inode;
199 if (!inode->i_op || !inode->i_op->removexattr)
202 return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
205 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
206 struct linux_binprm *bprm)
211 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
212 bprm->cap_effective = true;
214 bprm->cap_effective = false;
216 CAP_FOR_EACH_U32(i) {
217 __u32 permitted = caps->permitted.cap[i];
218 __u32 inheritable = caps->inheritable.cap[i];
221 * pP' = (X & fP) | (pI & fI)
223 bprm->cap_post_exec_permitted.cap[i] =
224 (current->cap_bset.cap[i] & permitted) |
225 (current->cap_inheritable.cap[i] & inheritable);
227 if (permitted & ~bprm->cap_post_exec_permitted.cap[i]) {
229 * insufficient to execute correctly
236 * For legacy apps, with no internal support for recognizing they
237 * do not have enough capabilities, we return an error if they are
238 * missing some "forced" (aka file-permitted) capabilities.
240 return bprm->cap_effective ? ret : 0;
243 int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
245 struct inode *inode = dentry->d_inode;
249 struct vfs_cap_data caps;
251 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
253 if (!inode || !inode->i_op || !inode->i_op->getxattr)
256 size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
258 if (size == -ENODATA || size == -EOPNOTSUPP) {
259 /* no data, that's ok */
265 if (size < sizeof(magic_etc))
268 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
270 switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
271 case VFS_CAP_REVISION_1:
272 if (size != XATTR_CAPS_SZ_1)
274 tocopy = VFS_CAP_U32_1;
276 case VFS_CAP_REVISION_2:
277 if (size != XATTR_CAPS_SZ_2)
279 tocopy = VFS_CAP_U32_2;
285 CAP_FOR_EACH_U32(i) {
288 cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
289 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
294 /* Locate any VFS capabilities: */
295 static int get_file_caps(struct linux_binprm *bprm)
297 struct dentry *dentry;
299 struct cpu_vfs_cap_data vcaps;
301 bprm_clear_caps(bprm);
303 if (!file_caps_enabled)
306 if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
309 dentry = dget(bprm->file->f_dentry);
311 rc = get_vfs_caps_from_disk(dentry, &vcaps);
314 printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
315 __func__, rc, bprm->filename);
316 else if (rc == -ENODATA)
321 rc = bprm_caps_from_vfs_caps(&vcaps, bprm);
326 bprm_clear_caps(bprm);
332 int cap_inode_need_killpriv(struct dentry *dentry)
337 int cap_inode_killpriv(struct dentry *dentry)
342 static inline int get_file_caps(struct linux_binprm *bprm)
344 bprm_clear_caps(bprm);
349 int cap_bprm_set_security (struct linux_binprm *bprm)
353 ret = get_file_caps(bprm);
355 if (!issecure(SECURE_NOROOT)) {
357 * To support inheritance of root-permissions and suid-root
358 * executables under compatibility mode, we override the
359 * capability sets for the file.
361 * If only the real uid is 0, we do not set the effective
364 if (bprm->e_uid == 0 || current->uid == 0) {
365 /* pP' = (cap_bset & ~0) | (pI & ~0) */
366 bprm->cap_post_exec_permitted = cap_combine(
367 current->cap_bset, current->cap_inheritable
369 bprm->cap_effective = (bprm->e_uid == 0);
377 void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
379 if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
380 !cap_issubset(bprm->cap_post_exec_permitted,
381 current->cap_permitted)) {
382 set_dumpable(current->mm, suid_dumpable);
383 current->pdeath_signal = 0;
385 if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
386 if (!capable(CAP_SETUID)) {
387 bprm->e_uid = current->uid;
388 bprm->e_gid = current->gid;
390 if (cap_limit_ptraced_target()) {
391 bprm->cap_post_exec_permitted = cap_intersect(
392 bprm->cap_post_exec_permitted,
393 current->cap_permitted);
398 current->suid = current->euid = current->fsuid = bprm->e_uid;
399 current->sgid = current->egid = current->fsgid = bprm->e_gid;
401 /* For init, we want to retain the capabilities set
402 * in the init_task struct. Thus we skip the usual
403 * capability rules */
404 if (!is_global_init(current)) {
405 current->cap_permitted = bprm->cap_post_exec_permitted;
406 if (bprm->cap_effective)
407 current->cap_effective = bprm->cap_post_exec_permitted;
409 cap_clear(current->cap_effective);
412 /* AUD: Audit candidate if current->cap_effective is set */
414 current->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
417 int cap_bprm_secureexec (struct linux_binprm *bprm)
419 if (current->uid != 0) {
420 if (bprm->cap_effective)
422 if (!cap_isclear(bprm->cap_post_exec_permitted))
426 return (current->euid != current->uid ||
427 current->egid != current->gid);
430 int cap_inode_setxattr(struct dentry *dentry, const char *name,
431 const void *value, size_t size, int flags)
433 if (!strcmp(name, XATTR_NAME_CAPS)) {
434 if (!capable(CAP_SETFCAP))
437 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
438 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
439 !capable(CAP_SYS_ADMIN))
444 int cap_inode_removexattr(struct dentry *dentry, const char *name)
446 if (!strcmp(name, XATTR_NAME_CAPS)) {
447 if (!capable(CAP_SETFCAP))
450 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
451 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
452 !capable(CAP_SYS_ADMIN))
457 /* moved from kernel/sys.c. */
459 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
460 * a process after a call to setuid, setreuid, or setresuid.
462 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
463 * {r,e,s}uid != 0, the permitted and effective capabilities are
466 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
467 * capabilities of the process are cleared.
469 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
470 * capabilities are set to the permitted capabilities.
472 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
477 * cevans - New behaviour, Oct '99
478 * A process may, via prctl(), elect to keep its capabilities when it
479 * calls setuid() and switches away from uid==0. Both permitted and
480 * effective sets will be retained.
481 * Without this change, it was impossible for a daemon to drop only some
482 * of its privilege. The call to setuid(!=0) would drop all privileges!
483 * Keeping uid 0 is not an option because uid 0 owns too many vital
485 * Thanks to Olaf Kirch and Peter Benie for spotting this.
487 static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
490 if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
491 (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
492 !issecure(SECURE_KEEP_CAPS)) {
493 cap_clear (current->cap_permitted);
494 cap_clear (current->cap_effective);
496 if (old_euid == 0 && current->euid != 0) {
497 cap_clear (current->cap_effective);
499 if (old_euid != 0 && current->euid == 0) {
500 current->cap_effective = current->cap_permitted;
504 int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
511 /* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
512 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
513 cap_emulate_setxuid (old_ruid, old_euid, old_suid);
518 uid_t old_fsuid = old_ruid;
520 /* Copied from kernel/sys.c:setfsuid. */
523 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
524 * if not, we might be a bit too harsh here.
527 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
528 if (old_fsuid == 0 && current->fsuid != 0) {
529 current->cap_effective =
531 current->cap_effective);
533 if (old_fsuid != 0 && current->fsuid == 0) {
534 current->cap_effective =
536 current->cap_effective,
537 current->cap_permitted);
549 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
551 * Rationale: code calling task_setscheduler, task_setioprio, and
552 * task_setnice, assumes that
553 * . if capable(cap_sys_nice), then those actions should be allowed
554 * . if not capable(cap_sys_nice), but acting on your own processes,
555 * then those actions should be allowed
556 * This is insufficient now since you can call code without suid, but
557 * yet with increased caps.
558 * So we check for increased caps on the target process.
560 static int cap_safe_nice(struct task_struct *p)
562 if (!cap_issubset(p->cap_permitted, current->cap_permitted) &&
563 !capable(CAP_SYS_NICE))
568 int cap_task_setscheduler (struct task_struct *p, int policy,
569 struct sched_param *lp)
571 return cap_safe_nice(p);
574 int cap_task_setioprio (struct task_struct *p, int ioprio)
576 return cap_safe_nice(p);
579 int cap_task_setnice (struct task_struct *p, int nice)
581 return cap_safe_nice(p);
585 * called from kernel/sys.c for prctl(PR_CABSET_DROP)
586 * done without task_capability_lock() because it introduces
587 * no new races - i.e. only another task doing capget() on
588 * this task could get inconsistent info. There can be no
589 * racing writer bc a task can only change its own caps.
591 static long cap_prctl_drop(unsigned long cap)
593 if (!capable(CAP_SETPCAP))
597 cap_lower(current->cap_bset, cap);
602 int cap_task_setscheduler (struct task_struct *p, int policy,
603 struct sched_param *lp)
607 int cap_task_setioprio (struct task_struct *p, int ioprio)
611 int cap_task_setnice (struct task_struct *p, int nice)
617 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
618 unsigned long arg4, unsigned long arg5, long *rc_p)
623 case PR_CAPBSET_READ:
624 if (!cap_valid(arg2))
627 error = !!cap_raised(current->cap_bset, arg2);
629 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
630 case PR_CAPBSET_DROP:
631 error = cap_prctl_drop(arg2);
635 * The next four prctl's remain to assist with transitioning a
636 * system from legacy UID=0 based privilege (when filesystem
637 * capabilities are not in use) to a system using filesystem
638 * capabilities only - as the POSIX.1e draft intended.
642 * PR_SET_SECUREBITS =
643 * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
644 * | issecure_mask(SECURE_NOROOT)
645 * | issecure_mask(SECURE_NOROOT_LOCKED)
646 * | issecure_mask(SECURE_NO_SETUID_FIXUP)
647 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
649 * will ensure that the current process and all of its
650 * children will be locked into a pure
651 * capability-based-privilege environment.
653 case PR_SET_SECUREBITS:
654 if ((((current->securebits & SECURE_ALL_LOCKS) >> 1)
655 & (current->securebits ^ arg2)) /*[1]*/
656 || ((current->securebits & SECURE_ALL_LOCKS
658 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
659 || (cap_capable(current, CAP_SETPCAP) != 0)) { /*[4]*/
661 * [1] no changing of bits that are locked
662 * [2] no unlocking of locks
663 * [3] no setting of unsupported bits
664 * [4] doing anything requires privilege (go read about
665 * the "sendmail capabilities bug")
667 error = -EPERM; /* cannot change a locked bit */
669 current->securebits = arg2;
672 case PR_GET_SECUREBITS:
673 error = current->securebits;
676 #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
678 case PR_GET_KEEPCAPS:
679 if (issecure(SECURE_KEEP_CAPS))
682 case PR_SET_KEEPCAPS:
683 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
685 else if (issecure(SECURE_KEEP_CAPS_LOCKED))
688 current->securebits |= issecure_mask(SECURE_KEEP_CAPS);
690 current->securebits &=
691 ~issecure_mask(SECURE_KEEP_CAPS);
695 /* No functionality available - continue with default */
699 /* Functionality provided */
704 void cap_task_reparent_to_init (struct task_struct *p)
706 cap_set_init_eff(p->cap_effective);
707 cap_clear(p->cap_inheritable);
708 cap_set_full(p->cap_permitted);
709 p->securebits = SECUREBITS_DEFAULT;
713 int cap_syslog (int type)
715 if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
720 int cap_vm_enough_memory(struct mm_struct *mm, long pages)
722 int cap_sys_admin = 0;
724 if (cap_capable(current, CAP_SYS_ADMIN) == 0)
726 return __vm_enough_memory(mm, pages, cap_sys_admin);