2 * Copyright (c) 1999-2002, 2006, 2009 Robert N. M. Watson
3 * Copyright (c) 2001 Ilmar S. Habibulin
4 * Copyright (c) 2001-2005 Networks Associates Technology, Inc.
5 * Copyright (c) 2005-2006 SPARTA, Inc.
6 * Copyright (c) 2008-2009 Apple Inc.
9 * This software was developed by Robert Watson and Ilmar Habibulin for the
12 * This software was developed for the FreeBSD Project in part by Network
13 * Associates Laboratories, the Security Research Division of Network
14 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
15 * as part of the DARPA CHATS research program.
17 * This software was enhanced by SPARTA ISSO under SPAWAR contract
18 * N66001-04-C-6019 ("SEFOS").
20 * This software was developed at the University of Cambridge Computer
21 * Laboratory with support from a grant from Google, Inc.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the above copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
32 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
46 * Framework for extensible kernel access control. This file contains core
47 * kernel infrastructure for the TrustedBSD MAC Framework, including policy
48 * registration, versioning, locking, error composition operator, and system
51 * The MAC Framework implements three programming interfaces:
53 * - The kernel MAC interface, defined in mac_framework.h, and invoked
54 * throughout the kernel to request security decisions, notify of security
55 * related events, etc.
57 * - The MAC policy module interface, defined in mac_policy.h, which is
58 * implemented by MAC policy modules and invoked by the MAC Framework to
59 * forward kernel security requests and notifications to policy modules.
61 * - The user MAC API, defined in mac.h, which allows user programs to query
62 * and set label state on objects.
64 * The majority of the MAC Framework implementation may be found in
65 * src/sys/security/mac. Sample policy modules may be found in
66 * src/sys/security/mac_*.
71 #include <sys/cdefs.h>
72 __FBSDID("$FreeBSD$");
74 #include <sys/param.h>
75 #include <sys/systm.h>
76 #include <sys/condvar.h>
77 #include <sys/kernel.h>
80 #include <sys/module.h>
81 #include <sys/rmlock.h>
84 #include <sys/sysctl.h>
86 #include <security/mac/mac_framework.h>
87 #include <security/mac/mac_internal.h>
88 #include <security/mac/mac_policy.h>
91 * DTrace SDT providers for MAC.
93 SDT_PROVIDER_DEFINE(mac);
94 SDT_PROVIDER_DEFINE(mac_framework);
96 SDT_PROBE_DEFINE2(mac, , policy, modevent, "int",
97 "struct mac_policy_conf *");
98 SDT_PROBE_DEFINE1(mac, , policy, register,
99 "struct mac_policy_conf *");
100 SDT_PROBE_DEFINE1(mac, , policy, unregister,
101 "struct mac_policy_conf *");
104 * Root sysctl node for all MAC and MAC policy controls.
106 SYSCTL_NODE(_security, OID_AUTO, mac, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
107 "TrustedBSD MAC policy controls");
110 * Declare that the kernel provides MAC support, version 3 (FreeBSD 7.x).
111 * This permits modules to refuse to be loaded if the necessary support isn't
112 * present, even if it's pre-boot.
114 MODULE_VERSION(kernel_mac_support, MAC_VERSION);
116 static unsigned int mac_version = MAC_VERSION;
117 SYSCTL_UINT(_security_mac, OID_AUTO, version, CTLFLAG_RD, &mac_version, 0,
121 * Flags for inlined checks. Note this would be best hotpatched at runtime.
122 * The following is a band-aid.
124 * Use FPFLAG for hooks running in commonly executed paths and FPFLAG_RARE
128 bool __read_frequently mac_##f##_fp_flag
130 #define FPFLAG_RARE(f) \
131 bool __read_mostly mac_##f##_fp_flag
135 FPFLAG(vnode_check_lookup);
136 FPFLAG(vnode_check_open);
137 FPFLAG(vnode_check_stat);
138 FPFLAG(vnode_check_read);
139 FPFLAG(vnode_check_write);
140 FPFLAG(vnode_check_mmap);
141 FPFLAG_RARE(vnode_check_poll);
142 FPFLAG_RARE(vnode_check_rename_from);
148 * Labels consist of a indexed set of "slots", which are allocated policies
149 * as required. The MAC Framework maintains a bitmask of slots allocated so
150 * far to prevent reuse. Slots cannot be reused, as the MAC Framework
151 * guarantees that newly allocated slots in labels will be NULL unless
152 * otherwise initialized, and because we do not have a mechanism to garbage
153 * collect slots on policy unload. As labeled policies tend to be statically
154 * loaded during boot, and not frequently unloaded and reloaded, this is not
155 * generally an issue.
157 #if MAC_MAX_SLOTS > 32
158 #error "MAC_MAX_SLOTS too large"
161 static unsigned int mac_max_slots = MAC_MAX_SLOTS;
162 static unsigned int mac_slot_offsets_free = (1 << MAC_MAX_SLOTS) - 1;
163 SYSCTL_UINT(_security_mac, OID_AUTO, max_slots, CTLFLAG_RD, &mac_max_slots,
167 * Has the kernel started generating labeled objects yet? All read/write
168 * access to this variable is serialized during the boot process. Following
169 * the end of serialization, we don't update this flag; no locking.
171 static int mac_late = 0;
174 * Each policy declares a mask of object types requiring labels to be
175 * allocated for them. For convenience, we combine and cache the bitwise or
176 * of the per-policy object flags to track whether we will allocate a label
177 * for an object type at run-time.
179 uint64_t mac_labeled;
180 SYSCTL_UQUAD(_security_mac, OID_AUTO, labeled, CTLFLAG_RD, &mac_labeled, 0,
181 "Mask of object types being labeled");
183 MALLOC_DEFINE(M_MACTEMP, "mactemp", "MAC temporary label storage");
186 * MAC policy modules are placed in one of two lists: mac_static_policy_list,
187 * for policies that are loaded early and cannot be unloaded, and
188 * mac_policy_list, which holds policies either loaded later in the boot
189 * cycle or that may be unloaded. The static policy list does not require
190 * locks to iterate over, but the dynamic list requires synchronization.
191 * Support for dynamic policy loading can be compiled out using the
192 * MAC_STATIC kernel option.
194 * The dynamic policy list is protected by two locks: modifying the list
195 * requires both locks to be held exclusively. One of the locks,
196 * mac_policy_rm, is acquired over policy entry points that will never sleep;
197 * the other, mac_policy_rms, is acquired over policy entry points that may
198 * sleep. The former category will be used when kernel locks may be held
199 * over calls to the MAC Framework, during network processing in ithreads,
200 * etc. The latter will tend to involve potentially blocking memory
201 * allocations, extended attribute I/O, etc.
204 static struct rmlock mac_policy_rm; /* Non-sleeping entry points. */
205 static struct rmslock mac_policy_rms; /* Sleeping entry points. */
208 struct mac_policy_list_head mac_policy_list;
209 struct mac_policy_list_head mac_static_policy_list;
210 u_int mac_policy_count; /* Registered policy count. */
212 static void mac_policy_xlock(void);
213 static void mac_policy_xlock_assert(void);
214 static void mac_policy_xunlock(void);
217 mac_policy_slock_nosleep(struct rm_priotracker *tracker)
224 rm_rlock(&mac_policy_rm, tracker);
229 mac_policy_slock_sleep(void)
232 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
233 "mac_policy_slock_sleep");
239 rms_rlock(&mac_policy_rms);
244 mac_policy_sunlock_nosleep(struct rm_priotracker *tracker)
251 rm_runlock(&mac_policy_rm, tracker);
256 mac_policy_sunlock_sleep(void)
263 rms_runlock(&mac_policy_rms);
268 mac_policy_xlock(void)
271 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
272 "mac_policy_xlock()");
278 rms_wlock(&mac_policy_rms);
279 rm_wlock(&mac_policy_rm);
284 mac_policy_xunlock(void)
291 rm_wunlock(&mac_policy_rm);
292 rms_wunlock(&mac_policy_rms);
297 mac_policy_xlock_assert(void)
304 rm_assert(&mac_policy_rm, RA_WLOCKED);
309 * Initialize the MAC subsystem, including appropriate SMP locks.
315 LIST_INIT(&mac_static_policy_list);
316 LIST_INIT(&mac_policy_list);
317 mac_labelzone_init();
320 rm_init_flags(&mac_policy_rm, "mac_policy_rm", RM_NOWITNESS |
322 rms_init(&mac_policy_rms, "mac_policy_rms");
327 * For the purposes of modules that want to know if they were loaded "early",
328 * set the mac_late flag once we've processed modules either linked into the
329 * kernel, or loaded before the kernel startup.
339 * Given a policy, derive from its set of non-NULL label init methods what
340 * object types the policy is interested in.
343 mac_policy_getlabeled(struct mac_policy_conf *mpc)
347 #define MPC_FLAG(method, flag) \
348 if (mpc->mpc_ops->mpo_ ## method != NULL) \
352 MPC_FLAG(cred_init_label, MPC_OBJECT_CRED);
353 MPC_FLAG(proc_init_label, MPC_OBJECT_PROC);
354 MPC_FLAG(vnode_init_label, MPC_OBJECT_VNODE);
355 MPC_FLAG(inpcb_init_label, MPC_OBJECT_INPCB);
356 MPC_FLAG(socket_init_label, MPC_OBJECT_SOCKET);
357 MPC_FLAG(devfs_init_label, MPC_OBJECT_DEVFS);
358 MPC_FLAG(mbuf_init_label, MPC_OBJECT_MBUF);
359 MPC_FLAG(ipq_init_label, MPC_OBJECT_IPQ);
360 MPC_FLAG(ifnet_init_label, MPC_OBJECT_IFNET);
361 MPC_FLAG(bpfdesc_init_label, MPC_OBJECT_BPFDESC);
362 MPC_FLAG(pipe_init_label, MPC_OBJECT_PIPE);
363 MPC_FLAG(mount_init_label, MPC_OBJECT_MOUNT);
364 MPC_FLAG(posixsem_init_label, MPC_OBJECT_POSIXSEM);
365 MPC_FLAG(posixshm_init_label, MPC_OBJECT_POSIXSHM);
366 MPC_FLAG(sysvmsg_init_label, MPC_OBJECT_SYSVMSG);
367 MPC_FLAG(sysvmsq_init_label, MPC_OBJECT_SYSVMSQ);
368 MPC_FLAG(sysvsem_init_label, MPC_OBJECT_SYSVSEM);
369 MPC_FLAG(sysvshm_init_label, MPC_OBJECT_SYSVSHM);
370 MPC_FLAG(syncache_init_label, MPC_OBJECT_SYNCACHE);
371 MPC_FLAG(ip6q_init_label, MPC_OBJECT_IP6Q);
378 * When policies are loaded or unloaded, walk the list of registered policies
379 * and built mac_labeled, a bitmask representing the union of all objects
380 * requiring labels across all policies.
383 mac_policy_update(void)
385 struct mac_policy_conf *mpc;
387 mac_policy_xlock_assert();
390 mac_policy_count = 0;
391 LIST_FOREACH(mpc, &mac_static_policy_list, mpc_list) {
392 mac_labeled |= mac_policy_getlabeled(mpc);
395 LIST_FOREACH(mpc, &mac_policy_list, mpc_list) {
396 mac_labeled |= mac_policy_getlabeled(mpc);
402 * There are frequently used code paths which check for rarely installed
403 * policies. Gross hack below enables doing it in a cheap manner.
406 #define FPO(f) (offsetof(struct mac_policy_ops, mpo_##f) / sizeof(uintptr_t))
408 struct mac_policy_fastpath_elem {
414 struct mac_policy_fastpath_elem mac_policy_fastpath_array[] = {
415 { .offset = FPO(priv_check), .flag = &mac_priv_check_fp_flag },
416 { .offset = FPO(priv_grant), .flag = &mac_priv_grant_fp_flag },
417 { .offset = FPO(vnode_check_lookup),
418 .flag = &mac_vnode_check_lookup_fp_flag },
419 { .offset = FPO(vnode_check_open),
420 .flag = &mac_vnode_check_open_fp_flag },
421 { .offset = FPO(vnode_check_stat),
422 .flag = &mac_vnode_check_stat_fp_flag },
423 { .offset = FPO(vnode_check_read),
424 .flag = &mac_vnode_check_read_fp_flag },
425 { .offset = FPO(vnode_check_write),
426 .flag = &mac_vnode_check_write_fp_flag },
427 { .offset = FPO(vnode_check_mmap),
428 .flag = &mac_vnode_check_mmap_fp_flag },
429 { .offset = FPO(vnode_check_poll),
430 .flag = &mac_vnode_check_poll_fp_flag },
431 { .offset = FPO(vnode_check_rename_from),
432 .flag = &mac_vnode_check_rename_from_fp_flag },
436 mac_policy_fastpath_enable(struct mac_policy_fastpath_elem *mpfe)
439 MPASS(mpfe->count >= 0);
441 if (mpfe->count == 1) {
442 MPASS(*mpfe->flag == false);
448 mac_policy_fastpath_disable(struct mac_policy_fastpath_elem *mpfe)
451 MPASS(mpfe->count >= 1);
453 if (mpfe->count == 0) {
454 MPASS(*mpfe->flag == true);
460 mac_policy_fastpath_register(struct mac_policy_conf *mpc)
462 struct mac_policy_fastpath_elem *mpfe;
466 mac_policy_xlock_assert();
468 ops = (uintptr_t **)mpc->mpc_ops;
469 for (i = 0; i < nitems(mac_policy_fastpath_array); i++) {
470 mpfe = &mac_policy_fastpath_array[i];
471 if (ops[mpfe->offset] != NULL)
472 mac_policy_fastpath_enable(mpfe);
477 mac_policy_fastpath_unregister(struct mac_policy_conf *mpc)
479 struct mac_policy_fastpath_elem *mpfe;
483 mac_policy_xlock_assert();
485 ops = (uintptr_t **)mpc->mpc_ops;
486 for (i = 0; i < nitems(mac_policy_fastpath_array); i++) {
487 mpfe = &mac_policy_fastpath_array[i];
488 if (ops[mpfe->offset] != NULL)
489 mac_policy_fastpath_disable(mpfe);
496 mac_policy_register(struct mac_policy_conf *mpc)
498 struct mac_policy_conf *tmpc;
499 int error, slot, static_entry;
504 * We don't technically need exclusive access while !mac_late, but
505 * hold it for assertion consistency.
510 * If the module can potentially be unloaded, or we're loading late,
511 * we have to stick it in the non-static list and pay an extra
512 * performance overhead. Otherwise, we can pay a light locking cost
513 * and stick it in the static list.
515 static_entry = (!mac_late &&
516 !(mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK));
519 LIST_FOREACH(tmpc, &mac_static_policy_list, mpc_list) {
520 if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) {
526 LIST_FOREACH(tmpc, &mac_policy_list, mpc_list) {
527 if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) {
533 if (mpc->mpc_field_off != NULL) {
534 slot = ffs(mac_slot_offsets_free);
540 mac_slot_offsets_free &= ~(1 << slot);
541 *mpc->mpc_field_off = slot;
543 mpc->mpc_runtime_flags |= MPC_RUNTIME_FLAG_REGISTERED;
546 * If we're loading a MAC module after the framework has initialized,
547 * it has to go into the dynamic list. If we're loading it before
548 * we've finished initializing, it can go into the static list with
549 * weaker locker requirements.
552 LIST_INSERT_HEAD(&mac_static_policy_list, mpc, mpc_list);
554 LIST_INSERT_HEAD(&mac_policy_list, mpc, mpc_list);
557 * Per-policy initialization. Currently, this takes place under the
558 * exclusive lock, so policies must not sleep in their init method.
559 * In the future, we may want to separate "init" from "start", with
560 * "init" occurring without the lock held. Likewise, on tear-down,
561 * breaking out "stop" from "destroy".
563 if (mpc->mpc_ops->mpo_init != NULL)
564 (*(mpc->mpc_ops->mpo_init))(mpc);
566 mac_policy_fastpath_register(mpc);
570 SDT_PROBE1(mac, , policy, register, mpc);
571 printf("Security policy loaded: %s (%s)\n", mpc->mpc_fullname,
575 mac_policy_xunlock();
580 mac_policy_unregister(struct mac_policy_conf *mpc)
584 * If we fail the load, we may get a request to unload. Check to see
585 * if we did the run-time registration, and if not, silently succeed.
588 if ((mpc->mpc_runtime_flags & MPC_RUNTIME_FLAG_REGISTERED) == 0) {
589 mac_policy_xunlock();
594 * Don't allow unloading modules with private data.
596 if (mpc->mpc_field_off != NULL) {
597 mac_policy_xunlock();
602 * Only allow the unload to proceed if the module is unloadable by
603 * its own definition.
605 if ((mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK) == 0) {
606 mac_policy_xunlock();
610 mac_policy_fastpath_unregister(mpc);
612 if (mpc->mpc_ops->mpo_destroy != NULL)
613 (*(mpc->mpc_ops->mpo_destroy))(mpc);
615 LIST_REMOVE(mpc, mpc_list);
616 mpc->mpc_runtime_flags &= ~MPC_RUNTIME_FLAG_REGISTERED;
618 mac_policy_xunlock();
620 SDT_PROBE1(mac, , policy, unregister, mpc);
621 printf("Security policy unload: %s (%s)\n", mpc->mpc_fullname,
628 * Allow MAC policy modules to register during boot, etc.
631 mac_policy_modevent(module_t mod, int type, void *data)
633 struct mac_policy_conf *mpc;
637 mpc = (struct mac_policy_conf *) data;
641 printf("mac_policy_modevent: MAC_STATIC and late\n");
646 SDT_PROBE2(mac, , policy, modevent, type, mpc);
649 if (mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_NOTLATE &&
651 printf("mac_policy_modevent: can't load %s policy "
652 "after booting\n", mpc->mpc_name);
656 error = mac_policy_register(mpc);
659 /* Don't unregister the module if it was never registered. */
660 if ((mpc->mpc_runtime_flags & MPC_RUNTIME_FLAG_REGISTERED)
662 error = mac_policy_unregister(mpc);
675 * Define an error value precedence, and given two arguments, selects the
676 * value with the higher precedence.
679 mac_error_select(int error1, int error2)
682 /* Certain decision-making errors take top priority. */
683 if (error1 == EDEADLK || error2 == EDEADLK)
686 /* Invalid arguments should be reported where possible. */
687 if (error1 == EINVAL || error2 == EINVAL)
690 /* Precedence goes to "visibility", with both process and file. */
691 if (error1 == ESRCH || error2 == ESRCH)
694 if (error1 == ENOENT || error2 == ENOENT)
697 /* Precedence goes to DAC/MAC protections. */
698 if (error1 == EACCES || error2 == EACCES)
701 /* Precedence goes to privilege. */
702 if (error1 == EPERM || error2 == EPERM)
705 /* Precedence goes to error over success; otherwise, arbitrary. */
712 mac_check_structmac_consistent(struct mac *mac)
715 /* Require that labels have a non-zero length. */
716 if (mac->m_buflen > MAC_MAX_LABEL_BUF_LEN ||
717 mac->m_buflen <= sizeof(""))
723 SYSINIT(mac, SI_SUB_MAC, SI_ORDER_FIRST, mac_init, NULL);
724 SYSINIT(mac_late, SI_SUB_MAC_LATE, SI_ORDER_FIRST, mac_late_init, NULL);