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/audit.h>
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/security.h>
16 #include <linux/file.h>
18 #include <linux/mman.h>
19 #include <linux/pagemap.h>
20 #include <linux/swap.h>
21 #include <linux/skbuff.h>
22 #include <linux/netlink.h>
23 #include <linux/ptrace.h>
24 #include <linux/xattr.h>
25 #include <linux/hugetlb.h>
26 #include <linux/mount.h>
27 #include <linux/sched.h>
28 #include <linux/prctl.h>
29 #include <linux/securebits.h>
31 int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
33 NETLINK_CB(skb).eff_cap = current->cap_effective;
37 int cap_netlink_recv(struct sk_buff *skb, int cap)
39 if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))
44 EXPORT_SYMBOL(cap_netlink_recv);
47 * NOTE WELL: cap_capable() cannot be used like the kernel's capable()
48 * function. That is, it has the reverse semantics: cap_capable()
49 * returns 0 when a task has a capability, but the kernel's capable()
50 * returns 1 for this case.
52 int cap_capable(struct task_struct *tsk, int cap, int audit)
54 /* Derived from include/linux/sched.h:capable. */
55 if (cap_raised(tsk->cap_effective, cap))
60 int cap_settime(struct timespec *ts, struct timezone *tz)
62 if (!capable(CAP_SYS_TIME))
67 int cap_ptrace_may_access(struct task_struct *child, unsigned int mode)
69 /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
70 if (cap_issubset(child->cap_permitted, current->cap_permitted))
72 if (capable(CAP_SYS_PTRACE))
77 int cap_ptrace_traceme(struct task_struct *parent)
79 /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
80 if (cap_issubset(current->cap_permitted, parent->cap_permitted))
82 if (has_capability(parent, CAP_SYS_PTRACE))
87 int cap_capget (struct task_struct *target, kernel_cap_t *effective,
88 kernel_cap_t *inheritable, kernel_cap_t *permitted)
90 /* Derived from kernel/capability.c:sys_capget. */
91 *effective = target->cap_effective;
92 *inheritable = target->cap_inheritable;
93 *permitted = target->cap_permitted;
97 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
99 static inline int cap_block_setpcap(struct task_struct *target)
102 * No support for remote process capability manipulation with
103 * filesystem capability support.
105 return (target != current);
108 static inline int cap_inh_is_capped(void)
111 * Return 1 if changes to the inheritable set are limited
112 * to the old permitted set. That is, if the current task
113 * does *not* possess the CAP_SETPCAP capability.
115 return (cap_capable(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0);
118 static inline int cap_limit_ptraced_target(void) { return 1; }
120 #else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
122 static inline int cap_block_setpcap(struct task_struct *t) { return 0; }
123 static inline int cap_inh_is_capped(void) { return 1; }
124 static inline int cap_limit_ptraced_target(void)
126 return !capable(CAP_SETPCAP);
129 #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
131 int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
132 kernel_cap_t *inheritable, kernel_cap_t *permitted)
134 if (cap_block_setpcap(target)) {
137 if (cap_inh_is_capped()
138 && !cap_issubset(*inheritable,
139 cap_combine(target->cap_inheritable,
140 current->cap_permitted))) {
141 /* incapable of using this inheritable set */
144 if (!cap_issubset(*inheritable,
145 cap_combine(target->cap_inheritable,
146 current->cap_bset))) {
147 /* no new pI capabilities outside bounding set */
151 /* verify restrictions on target's new Permitted set */
152 if (!cap_issubset (*permitted,
153 cap_combine (target->cap_permitted,
154 current->cap_permitted))) {
158 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
159 if (!cap_issubset (*effective, *permitted)) {
166 void cap_capset_set (struct task_struct *target, kernel_cap_t *effective,
167 kernel_cap_t *inheritable, kernel_cap_t *permitted)
169 target->cap_effective = *effective;
170 target->cap_inheritable = *inheritable;
171 target->cap_permitted = *permitted;
174 static inline void bprm_clear_caps(struct linux_binprm *bprm)
176 cap_clear(bprm->cap_post_exec_permitted);
177 bprm->cap_effective = false;
180 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
182 int cap_inode_need_killpriv(struct dentry *dentry)
184 struct inode *inode = dentry->d_inode;
187 if (!inode->i_op || !inode->i_op->getxattr)
190 error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
196 int cap_inode_killpriv(struct dentry *dentry)
198 struct inode *inode = dentry->d_inode;
200 if (!inode->i_op || !inode->i_op->removexattr)
203 return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
206 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
207 struct linux_binprm *bprm)
212 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
213 bprm->cap_effective = true;
215 bprm->cap_effective = false;
217 CAP_FOR_EACH_U32(i) {
218 __u32 permitted = caps->permitted.cap[i];
219 __u32 inheritable = caps->inheritable.cap[i];
222 * pP' = (X & fP) | (pI & fI)
224 bprm->cap_post_exec_permitted.cap[i] =
225 (current->cap_bset.cap[i] & permitted) |
226 (current->cap_inheritable.cap[i] & inheritable);
228 if (permitted & ~bprm->cap_post_exec_permitted.cap[i]) {
230 * insufficient to execute correctly
237 * For legacy apps, with no internal support for recognizing they
238 * do not have enough capabilities, we return an error if they are
239 * missing some "forced" (aka file-permitted) capabilities.
241 return bprm->cap_effective ? ret : 0;
244 int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
246 struct inode *inode = dentry->d_inode;
250 struct vfs_cap_data caps;
252 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
254 if (!inode || !inode->i_op || !inode->i_op->getxattr)
257 size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
259 if (size == -ENODATA || size == -EOPNOTSUPP) {
260 /* no data, that's ok */
266 if (size < sizeof(magic_etc))
269 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
271 switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
272 case VFS_CAP_REVISION_1:
273 if (size != XATTR_CAPS_SZ_1)
275 tocopy = VFS_CAP_U32_1;
277 case VFS_CAP_REVISION_2:
278 if (size != XATTR_CAPS_SZ_2)
280 tocopy = VFS_CAP_U32_2;
286 CAP_FOR_EACH_U32(i) {
289 cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
290 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
295 /* Locate any VFS capabilities: */
296 static int get_file_caps(struct linux_binprm *bprm)
298 struct dentry *dentry;
300 struct cpu_vfs_cap_data vcaps;
302 bprm_clear_caps(bprm);
304 if (!file_caps_enabled)
307 if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
310 dentry = dget(bprm->file->f_dentry);
312 rc = get_vfs_caps_from_disk(dentry, &vcaps);
315 printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
316 __func__, rc, bprm->filename);
317 else if (rc == -ENODATA)
322 rc = bprm_caps_from_vfs_caps(&vcaps, bprm);
327 bprm_clear_caps(bprm);
333 int cap_inode_need_killpriv(struct dentry *dentry)
338 int cap_inode_killpriv(struct dentry *dentry)
343 static inline int get_file_caps(struct linux_binprm *bprm)
345 bprm_clear_caps(bprm);
350 int cap_bprm_set_security (struct linux_binprm *bprm)
354 ret = get_file_caps(bprm);
356 if (!issecure(SECURE_NOROOT)) {
358 * To support inheritance of root-permissions and suid-root
359 * executables under compatibility mode, we override the
360 * capability sets for the file.
362 * If only the real uid is 0, we do not set the effective
365 if (bprm->e_uid == 0 || current->uid == 0) {
366 /* pP' = (cap_bset & ~0) | (pI & ~0) */
367 bprm->cap_post_exec_permitted = cap_combine(
368 current->cap_bset, current->cap_inheritable
370 bprm->cap_effective = (bprm->e_uid == 0);
378 void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
380 kernel_cap_t pP = current->cap_permitted;
381 kernel_cap_t pE = current->cap_effective;
383 if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
384 !cap_issubset(bprm->cap_post_exec_permitted,
385 current->cap_permitted)) {
386 set_dumpable(current->mm, suid_dumpable);
387 current->pdeath_signal = 0;
389 if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
390 if (!capable(CAP_SETUID)) {
391 bprm->e_uid = current->uid;
392 bprm->e_gid = current->gid;
394 if (cap_limit_ptraced_target()) {
395 bprm->cap_post_exec_permitted = cap_intersect(
396 bprm->cap_post_exec_permitted,
397 current->cap_permitted);
402 current->suid = current->euid = current->fsuid = bprm->e_uid;
403 current->sgid = current->egid = current->fsgid = bprm->e_gid;
405 /* For init, we want to retain the capabilities set
406 * in the init_task struct. Thus we skip the usual
407 * capability rules */
408 if (!is_global_init(current)) {
409 current->cap_permitted = bprm->cap_post_exec_permitted;
410 if (bprm->cap_effective)
411 current->cap_effective = bprm->cap_post_exec_permitted;
413 cap_clear(current->cap_effective);
417 * Audit candidate if current->cap_effective is set
419 * We do not bother to audit if 3 things are true:
420 * 1) cap_effective has all caps
422 * 3) root is supposed to have all caps (SECURE_NOROOT)
423 * Since this is just a normal root execing a process.
425 * Number 1 above might fail if you don't have a full bset, but I think
426 * that is interesting information to audit.
428 if (!cap_isclear(current->cap_effective)) {
429 if (!cap_issubset(CAP_FULL_SET, current->cap_effective) ||
430 (bprm->e_uid != 0) || (current->uid != 0) ||
431 issecure(SECURE_NOROOT))
432 audit_log_bprm_fcaps(bprm, &pP, &pE);
435 current->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
438 int cap_bprm_secureexec (struct linux_binprm *bprm)
440 if (current->uid != 0) {
441 if (bprm->cap_effective)
443 if (!cap_isclear(bprm->cap_post_exec_permitted))
447 return (current->euid != current->uid ||
448 current->egid != current->gid);
451 int cap_inode_setxattr(struct dentry *dentry, const char *name,
452 const void *value, size_t size, int flags)
454 if (!strcmp(name, XATTR_NAME_CAPS)) {
455 if (!capable(CAP_SETFCAP))
458 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
459 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
460 !capable(CAP_SYS_ADMIN))
465 int cap_inode_removexattr(struct dentry *dentry, const char *name)
467 if (!strcmp(name, XATTR_NAME_CAPS)) {
468 if (!capable(CAP_SETFCAP))
471 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
472 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
473 !capable(CAP_SYS_ADMIN))
478 /* moved from kernel/sys.c. */
480 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
481 * a process after a call to setuid, setreuid, or setresuid.
483 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
484 * {r,e,s}uid != 0, the permitted and effective capabilities are
487 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
488 * capabilities of the process are cleared.
490 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
491 * capabilities are set to the permitted capabilities.
493 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
498 * cevans - New behaviour, Oct '99
499 * A process may, via prctl(), elect to keep its capabilities when it
500 * calls setuid() and switches away from uid==0. Both permitted and
501 * effective sets will be retained.
502 * Without this change, it was impossible for a daemon to drop only some
503 * of its privilege. The call to setuid(!=0) would drop all privileges!
504 * Keeping uid 0 is not an option because uid 0 owns too many vital
506 * Thanks to Olaf Kirch and Peter Benie for spotting this.
508 static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
511 if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
512 (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
513 !issecure(SECURE_KEEP_CAPS)) {
514 cap_clear (current->cap_permitted);
515 cap_clear (current->cap_effective);
517 if (old_euid == 0 && current->euid != 0) {
518 cap_clear (current->cap_effective);
520 if (old_euid != 0 && current->euid == 0) {
521 current->cap_effective = current->cap_permitted;
525 int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
532 /* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
533 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
534 cap_emulate_setxuid (old_ruid, old_euid, old_suid);
539 uid_t old_fsuid = old_ruid;
541 /* Copied from kernel/sys.c:setfsuid. */
544 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
545 * if not, we might be a bit too harsh here.
548 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
549 if (old_fsuid == 0 && current->fsuid != 0) {
550 current->cap_effective =
552 current->cap_effective);
554 if (old_fsuid != 0 && current->fsuid == 0) {
555 current->cap_effective =
557 current->cap_effective,
558 current->cap_permitted);
570 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
572 * Rationale: code calling task_setscheduler, task_setioprio, and
573 * task_setnice, assumes that
574 * . if capable(cap_sys_nice), then those actions should be allowed
575 * . if not capable(cap_sys_nice), but acting on your own processes,
576 * then those actions should be allowed
577 * This is insufficient now since you can call code without suid, but
578 * yet with increased caps.
579 * So we check for increased caps on the target process.
581 static int cap_safe_nice(struct task_struct *p)
583 if (!cap_issubset(p->cap_permitted, current->cap_permitted) &&
584 !capable(CAP_SYS_NICE))
589 int cap_task_setscheduler (struct task_struct *p, int policy,
590 struct sched_param *lp)
592 return cap_safe_nice(p);
595 int cap_task_setioprio (struct task_struct *p, int ioprio)
597 return cap_safe_nice(p);
600 int cap_task_setnice (struct task_struct *p, int nice)
602 return cap_safe_nice(p);
606 * called from kernel/sys.c for prctl(PR_CABSET_DROP)
607 * done without task_capability_lock() because it introduces
608 * no new races - i.e. only another task doing capget() on
609 * this task could get inconsistent info. There can be no
610 * racing writer bc a task can only change its own caps.
612 static long cap_prctl_drop(unsigned long cap)
614 if (!capable(CAP_SETPCAP))
618 cap_lower(current->cap_bset, cap);
623 int cap_task_setscheduler (struct task_struct *p, int policy,
624 struct sched_param *lp)
628 int cap_task_setioprio (struct task_struct *p, int ioprio)
632 int cap_task_setnice (struct task_struct *p, int nice)
638 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
639 unsigned long arg4, unsigned long arg5, long *rc_p)
644 case PR_CAPBSET_READ:
645 if (!cap_valid(arg2))
648 error = !!cap_raised(current->cap_bset, arg2);
650 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
651 case PR_CAPBSET_DROP:
652 error = cap_prctl_drop(arg2);
656 * The next four prctl's remain to assist with transitioning a
657 * system from legacy UID=0 based privilege (when filesystem
658 * capabilities are not in use) to a system using filesystem
659 * capabilities only - as the POSIX.1e draft intended.
663 * PR_SET_SECUREBITS =
664 * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
665 * | issecure_mask(SECURE_NOROOT)
666 * | issecure_mask(SECURE_NOROOT_LOCKED)
667 * | issecure_mask(SECURE_NO_SETUID_FIXUP)
668 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
670 * will ensure that the current process and all of its
671 * children will be locked into a pure
672 * capability-based-privilege environment.
674 case PR_SET_SECUREBITS:
675 if ((((current->securebits & SECURE_ALL_LOCKS) >> 1)
676 & (current->securebits ^ arg2)) /*[1]*/
677 || ((current->securebits & SECURE_ALL_LOCKS
679 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
680 || (cap_capable(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0)) { /*[4]*/
682 * [1] no changing of bits that are locked
683 * [2] no unlocking of locks
684 * [3] no setting of unsupported bits
685 * [4] doing anything requires privilege (go read about
686 * the "sendmail capabilities bug")
688 error = -EPERM; /* cannot change a locked bit */
690 current->securebits = arg2;
693 case PR_GET_SECUREBITS:
694 error = current->securebits;
697 #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
699 case PR_GET_KEEPCAPS:
700 if (issecure(SECURE_KEEP_CAPS))
703 case PR_SET_KEEPCAPS:
704 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
706 else if (issecure(SECURE_KEEP_CAPS_LOCKED))
709 current->securebits |= issecure_mask(SECURE_KEEP_CAPS);
711 current->securebits &=
712 ~issecure_mask(SECURE_KEEP_CAPS);
716 /* No functionality available - continue with default */
720 /* Functionality provided */
725 void cap_task_reparent_to_init (struct task_struct *p)
727 cap_set_init_eff(p->cap_effective);
728 cap_clear(p->cap_inheritable);
729 cap_set_full(p->cap_permitted);
730 p->securebits = SECUREBITS_DEFAULT;
734 int cap_syslog (int type)
736 if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
741 int cap_vm_enough_memory(struct mm_struct *mm, long pages)
743 int cap_sys_admin = 0;
745 if (cap_capable(current, CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT) == 0)
747 return __vm_enough_memory(mm, pages, cap_sys_admin);