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_*.
69 #include "opt_kdtrace.h"
72 #include <sys/cdefs.h>
73 __FBSDID("$FreeBSD$");
75 #include <sys/param.h>
76 #include <sys/condvar.h>
77 #include <sys/kernel.h>
80 #include <sys/module.h>
81 #include <sys/rmlock.h>
84 #include <sys/systm.h>
85 #include <sys/sysctl.h>
87 #include <security/mac/mac_framework.h>
88 #include <security/mac/mac_internal.h>
89 #include <security/mac/mac_policy.h>
92 * DTrace SDT providers for MAC.
94 SDT_PROVIDER_DEFINE(mac);
95 SDT_PROVIDER_DEFINE(mac_framework);
97 SDT_PROBE_DEFINE2(mac, kernel, policy, modevent, "int",
98 "struct mac_policy_conf *mpc");
99 SDT_PROBE_DEFINE1(mac, kernel, policy, register, "struct mac_policy_conf *");
100 SDT_PROBE_DEFINE1(mac, kernel, policy, unregister, "struct mac_policy_conf *");
103 * Root sysctl node for all MAC and MAC policy controls.
105 SYSCTL_NODE(_security, OID_AUTO, mac, CTLFLAG_RW, 0,
106 "TrustedBSD MAC policy controls");
109 * Declare that the kernel provides MAC support, version 3 (FreeBSD 7.x).
110 * This permits modules to refuse to be loaded if the necessary support isn't
111 * present, even if it's pre-boot.
113 MODULE_VERSION(kernel_mac_support, MAC_VERSION);
115 static unsigned int mac_version = MAC_VERSION;
116 SYSCTL_UINT(_security_mac, OID_AUTO, version, CTLFLAG_RD, &mac_version, 0,
120 * Labels consist of a indexed set of "slots", which are allocated policies
121 * as required. The MAC Framework maintains a bitmask of slots allocated so
122 * far to prevent reuse. Slots cannot be reused, as the MAC Framework
123 * guarantees that newly allocated slots in labels will be NULL unless
124 * otherwise initialized, and because we do not have a mechanism to garbage
125 * collect slots on policy unload. As labeled policies tend to be statically
126 * loaded during boot, and not frequently unloaded and reloaded, this is not
127 * generally an issue.
129 #if MAC_MAX_SLOTS > 32
130 #error "MAC_MAX_SLOTS too large"
133 static unsigned int mac_max_slots = MAC_MAX_SLOTS;
134 static unsigned int mac_slot_offsets_free = (1 << MAC_MAX_SLOTS) - 1;
135 SYSCTL_UINT(_security_mac, OID_AUTO, max_slots, CTLFLAG_RD, &mac_max_slots,
139 * Has the kernel started generating labeled objects yet? All read/write
140 * access to this variable is serialized during the boot process. Following
141 * the end of serialization, we don't update this flag; no locking.
143 static int mac_late = 0;
146 * Each policy declares a mask of object types requiring labels to be
147 * allocated for them. For convenience, we combine and cache the bitwise or
148 * of the per-policy object flags to track whether we will allocate a label
149 * for an object type at run-time.
151 uint64_t mac_labeled;
152 SYSCTL_QUAD(_security_mac, OID_AUTO, labeled, CTLFLAG_RD, &mac_labeled, 0,
153 "Mask of object types being labeled");
155 MALLOC_DEFINE(M_MACTEMP, "mactemp", "MAC temporary label storage");
158 * MAC policy modules are placed in one of two lists: mac_static_policy_list,
159 * for policies that are loaded early and cannot be unloaded, and
160 * mac_policy_list, which holds policies either loaded later in the boot
161 * cycle or that may be unloaded. The static policy list does not require
162 * locks to iterate over, but the dynamic list requires synchronization.
163 * Support for dynamic policy loading can be compiled out using the
164 * MAC_STATIC kernel option.
166 * The dynamic policy list is protected by two locks: modifying the list
167 * requires both locks to be held exclusively. One of the locks,
168 * mac_policy_rm, is acquired over policy entry points that will never sleep;
169 * the other, mac_policy_sx, is acquire over policy entry points that may
170 * sleep. The former category will be used when kernel locks may be held
171 * over calls to the MAC Framework, during network processing in ithreads,
172 * etc. The latter will tend to involve potentially blocking memory
173 * allocations, extended attribute I/O, etc.
176 static struct rmlock mac_policy_rm; /* Non-sleeping entry points. */
177 static struct sx mac_policy_sx; /* Sleeping entry points. */
180 struct mac_policy_list_head mac_policy_list;
181 struct mac_policy_list_head mac_static_policy_list;
182 u_int mac_policy_count; /* Registered policy count. */
184 static void mac_policy_xlock(void);
185 static void mac_policy_xlock_assert(void);
186 static void mac_policy_xunlock(void);
189 mac_policy_slock_nosleep(struct rm_priotracker *tracker)
196 rm_rlock(&mac_policy_rm, tracker);
201 mac_policy_slock_sleep(void)
204 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
205 "mac_policy_slock_sleep");
211 sx_slock(&mac_policy_sx);
216 mac_policy_sunlock_nosleep(struct rm_priotracker *tracker)
223 rm_runlock(&mac_policy_rm, tracker);
228 mac_policy_sunlock_sleep(void)
235 sx_sunlock(&mac_policy_sx);
240 mac_policy_xlock(void)
243 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
244 "mac_policy_xlock()");
250 sx_xlock(&mac_policy_sx);
251 rm_wlock(&mac_policy_rm);
256 mac_policy_xunlock(void)
263 rm_wunlock(&mac_policy_rm);
264 sx_xunlock(&mac_policy_sx);
269 mac_policy_xlock_assert(void)
276 /* XXXRW: rm_assert(&mac_policy_rm, RA_WLOCKED); */
277 sx_assert(&mac_policy_sx, SA_XLOCKED);
282 * Initialize the MAC subsystem, including appropriate SMP locks.
288 LIST_INIT(&mac_static_policy_list);
289 LIST_INIT(&mac_policy_list);
290 mac_labelzone_init();
293 rm_init_flags(&mac_policy_rm, "mac_policy_rm", RM_NOWITNESS);
294 sx_init_flags(&mac_policy_sx, "mac_policy_sx", SX_NOWITNESS);
299 * For the purposes of modules that want to know if they were loaded "early",
300 * set the mac_late flag once we've processed modules either linked into the
301 * kernel, or loaded before the kernel startup.
311 * Given a policy, derive from its set of non-NULL label init methods what
312 * object types the policy is interested in.
315 mac_policy_getlabeled(struct mac_policy_conf *mpc)
319 #define MPC_FLAG(method, flag) \
320 if (mpc->mpc_ops->mpo_ ## method != NULL) \
324 MPC_FLAG(cred_init_label, MPC_OBJECT_CRED);
325 MPC_FLAG(proc_init_label, MPC_OBJECT_PROC);
326 MPC_FLAG(vnode_init_label, MPC_OBJECT_VNODE);
327 MPC_FLAG(inpcb_init_label, MPC_OBJECT_INPCB);
328 MPC_FLAG(socket_init_label, MPC_OBJECT_SOCKET);
329 MPC_FLAG(devfs_init_label, MPC_OBJECT_DEVFS);
330 MPC_FLAG(mbuf_init_label, MPC_OBJECT_MBUF);
331 MPC_FLAG(ipq_init_label, MPC_OBJECT_IPQ);
332 MPC_FLAG(ifnet_init_label, MPC_OBJECT_IFNET);
333 MPC_FLAG(bpfdesc_init_label, MPC_OBJECT_BPFDESC);
334 MPC_FLAG(pipe_init_label, MPC_OBJECT_PIPE);
335 MPC_FLAG(mount_init_label, MPC_OBJECT_MOUNT);
336 MPC_FLAG(posixsem_init_label, MPC_OBJECT_POSIXSEM);
337 MPC_FLAG(posixshm_init_label, MPC_OBJECT_POSIXSHM);
338 MPC_FLAG(sysvmsg_init_label, MPC_OBJECT_SYSVMSG);
339 MPC_FLAG(sysvmsq_init_label, MPC_OBJECT_SYSVMSQ);
340 MPC_FLAG(sysvsem_init_label, MPC_OBJECT_SYSVSEM);
341 MPC_FLAG(sysvshm_init_label, MPC_OBJECT_SYSVSHM);
342 MPC_FLAG(syncache_init_label, MPC_OBJECT_SYNCACHE);
343 MPC_FLAG(ip6q_init_label, MPC_OBJECT_IP6Q);
350 * When policies are loaded or unloaded, walk the list of registered policies
351 * and built mac_labeled, a bitmask representing the union of all objects
352 * requiring labels across all policies.
355 mac_policy_update(void)
357 struct mac_policy_conf *mpc;
359 mac_policy_xlock_assert();
362 mac_policy_count = 0;
363 LIST_FOREACH(mpc, &mac_static_policy_list, mpc_list) {
364 mac_labeled |= mac_policy_getlabeled(mpc);
367 LIST_FOREACH(mpc, &mac_policy_list, mpc_list) {
368 mac_labeled |= mac_policy_getlabeled(mpc);
374 mac_policy_register(struct mac_policy_conf *mpc)
376 struct mac_policy_conf *tmpc;
377 int error, slot, static_entry;
382 * We don't technically need exclusive access while !mac_late, but
383 * hold it for assertion consistency.
388 * If the module can potentially be unloaded, or we're loading late,
389 * we have to stick it in the non-static list and pay an extra
390 * performance overhead. Otherwise, we can pay a light locking cost
391 * and stick it in the static list.
393 static_entry = (!mac_late &&
394 !(mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK));
397 LIST_FOREACH(tmpc, &mac_static_policy_list, mpc_list) {
398 if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) {
404 LIST_FOREACH(tmpc, &mac_policy_list, mpc_list) {
405 if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) {
411 if (mpc->mpc_field_off != NULL) {
412 slot = ffs(mac_slot_offsets_free);
418 mac_slot_offsets_free &= ~(1 << slot);
419 *mpc->mpc_field_off = slot;
421 mpc->mpc_runtime_flags |= MPC_RUNTIME_FLAG_REGISTERED;
424 * If we're loading a MAC module after the framework has initialized,
425 * it has to go into the dynamic list. If we're loading it before
426 * we've finished initializing, it can go into the static list with
427 * weaker locker requirements.
430 LIST_INSERT_HEAD(&mac_static_policy_list, mpc, mpc_list);
432 LIST_INSERT_HEAD(&mac_policy_list, mpc, mpc_list);
435 * Per-policy initialization. Currently, this takes place under the
436 * exclusive lock, so policies must not sleep in their init method.
437 * In the future, we may want to separate "init" from "start", with
438 * "init" occuring without the lock held. Likewise, on tear-down,
439 * breaking out "stop" from "destroy".
441 if (mpc->mpc_ops->mpo_init != NULL)
442 (*(mpc->mpc_ops->mpo_init))(mpc);
445 SDT_PROBE(mac, kernel, policy, register, mpc, 0, 0, 0, 0);
446 printf("Security policy loaded: %s (%s)\n", mpc->mpc_fullname,
450 mac_policy_xunlock();
455 mac_policy_unregister(struct mac_policy_conf *mpc)
459 * If we fail the load, we may get a request to unload. Check to see
460 * if we did the run-time registration, and if not, silently succeed.
463 if ((mpc->mpc_runtime_flags & MPC_RUNTIME_FLAG_REGISTERED) == 0) {
464 mac_policy_xunlock();
469 * Don't allow unloading modules with private data.
471 if (mpc->mpc_field_off != NULL) {
472 mac_policy_xunlock();
477 * Only allow the unload to proceed if the module is unloadable by
478 * its own definition.
480 if ((mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK) == 0) {
481 mac_policy_xunlock();
484 if (mpc->mpc_ops->mpo_destroy != NULL)
485 (*(mpc->mpc_ops->mpo_destroy))(mpc);
487 LIST_REMOVE(mpc, mpc_list);
488 mpc->mpc_runtime_flags &= ~MPC_RUNTIME_FLAG_REGISTERED;
490 mac_policy_xunlock();
492 SDT_PROBE(mac, kernel, policy, unregister, mpc, 0, 0, 0, 0);
493 printf("Security policy unload: %s (%s)\n", mpc->mpc_fullname,
500 * Allow MAC policy modules to register during boot, etc.
503 mac_policy_modevent(module_t mod, int type, void *data)
505 struct mac_policy_conf *mpc;
509 mpc = (struct mac_policy_conf *) data;
513 printf("mac_policy_modevent: MAC_STATIC and late\n");
518 SDT_PROBE(mac, kernel, policy, modevent, type, mpc, 0, 0, 0);
521 if (mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_NOTLATE &&
523 printf("mac_policy_modevent: can't load %s policy "
524 "after booting\n", mpc->mpc_name);
528 error = mac_policy_register(mpc);
531 /* Don't unregister the module if it was never registered. */
532 if ((mpc->mpc_runtime_flags & MPC_RUNTIME_FLAG_REGISTERED)
534 error = mac_policy_unregister(mpc);
547 * Define an error value precedence, and given two arguments, selects the
548 * value with the higher precedence.
551 mac_error_select(int error1, int error2)
554 /* Certain decision-making errors take top priority. */
555 if (error1 == EDEADLK || error2 == EDEADLK)
558 /* Invalid arguments should be reported where possible. */
559 if (error1 == EINVAL || error2 == EINVAL)
562 /* Precedence goes to "visibility", with both process and file. */
563 if (error1 == ESRCH || error2 == ESRCH)
566 if (error1 == ENOENT || error2 == ENOENT)
569 /* Precedence goes to DAC/MAC protections. */
570 if (error1 == EACCES || error2 == EACCES)
573 /* Precedence goes to privilege. */
574 if (error1 == EPERM || error2 == EPERM)
577 /* Precedence goes to error over success; otherwise, arbitrary. */
584 mac_check_structmac_consistent(struct mac *mac)
587 if (mac->m_buflen < 0 ||
588 mac->m_buflen > MAC_MAX_LABEL_BUF_LEN)
594 SYSINIT(mac, SI_SUB_MAC, SI_ORDER_FIRST, mac_init, NULL);
595 SYSINIT(mac_late, SI_SUB_MAC_LATE, SI_ORDER_FIRST, mac_late_init, NULL);