1 /*- 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. 7 * All rights reserved. 8 * 9 * This software was developed by Robert Watson and Ilmar Habibulin for the 10 * TrustedBSD Project. 11 * 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. 16 * 17 * This software was enhanced by SPARTA ISSO under SPAWAR contract 18 * N66001-04-C-6019 ("SEFOS"). 19 * 20 * This software was developed at the University of Cambridge Computer 21 * Laboratory with support from a grant from Google, Inc. 22 * 23 * Redistribution and use in source and binary forms, with or without 24 * modification, are permitted provided that the following conditions 25 * are met: 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. 31 * 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 42 * SUCH DAMAGE. 43 */ 44 45 /*- 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 49 * calls. 50 * 51 * The MAC Framework implements three programming interfaces: 52 * 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. 56 * 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. 60 * 61 * - The user MAC API, defined in mac.h, which allows user programs to query 62 * and set label state on objects. 63 * 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_*. 67 */ 68 69 #include "opt_mac.h" 70 71 #include <sys/cdefs.h> 72 __FBSDID("$FreeBSD$"); 73 74 #include <sys/param.h> 75 #include <sys/systm.h> 76 #include <sys/condvar.h> 77 #include <sys/kernel.h> 78 #include <sys/lock.h> 79 #include <sys/mac.h> 80 #include <sys/module.h> 81 #include <sys/rmlock.h> 82 #include <sys/sdt.h> 83 #include <sys/sx.h> 84 #include <sys/sysctl.h> 85 86 #include <security/mac/mac_framework.h> 87 #include <security/mac/mac_internal.h> 88 #include <security/mac/mac_policy.h> 89 90 /* 91 * DTrace SDT providers for MAC. 92 */ 93 SDT_PROVIDER_DEFINE(mac); 94 SDT_PROVIDER_DEFINE(mac_framework); 95 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 *"); 102 103 /* 104 * Root sysctl node for all MAC and MAC policy controls. 105 */ 106 SYSCTL_NODE(_security, OID_AUTO, mac, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 107 "TrustedBSD MAC policy controls"); 108 109 /* 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. 113 */ 114 MODULE_VERSION(kernel_mac_support, MAC_VERSION); 115 116 static unsigned int mac_version = MAC_VERSION; 117 SYSCTL_UINT(_security_mac, OID_AUTO, version, CTLFLAG_RD, &mac_version, 0, 118 ""); 119 120 /* 121 * Flags for inlined checks. 122 */ 123 #define FPFLAG(f) \ 124 bool __read_frequently mac_##f##_fp_flag 125 126 FPFLAG(priv_check); 127 FPFLAG(priv_grant); 128 FPFLAG(vnode_check_lookup); 129 FPFLAG(vnode_check_open); 130 FPFLAG(vnode_check_stat); 131 FPFLAG(vnode_check_read); 132 FPFLAG(vnode_check_write); 133 FPFLAG(vnode_check_mmap); 134 135 #undef FPFLAG 136 137 /* 138 * Labels consist of a indexed set of "slots", which are allocated policies 139 * as required. The MAC Framework maintains a bitmask of slots allocated so 140 * far to prevent reuse. Slots cannot be reused, as the MAC Framework 141 * guarantees that newly allocated slots in labels will be NULL unless 142 * otherwise initialized, and because we do not have a mechanism to garbage 143 * collect slots on policy unload. As labeled policies tend to be statically 144 * loaded during boot, and not frequently unloaded and reloaded, this is not 145 * generally an issue. 146 */ 147 #if MAC_MAX_SLOTS > 32 148 #error "MAC_MAX_SLOTS too large" 149 #endif 150 151 static unsigned int mac_max_slots = MAC_MAX_SLOTS; 152 static unsigned int mac_slot_offsets_free = (1 << MAC_MAX_SLOTS) - 1; 153 SYSCTL_UINT(_security_mac, OID_AUTO, max_slots, CTLFLAG_RD, &mac_max_slots, 154 0, ""); 155 156 /* 157 * Has the kernel started generating labeled objects yet? All read/write 158 * access to this variable is serialized during the boot process. Following 159 * the end of serialization, we don't update this flag; no locking. 160 */ 161 static int mac_late = 0; 162 163 /* 164 * Each policy declares a mask of object types requiring labels to be 165 * allocated for them. For convenience, we combine and cache the bitwise or 166 * of the per-policy object flags to track whether we will allocate a label 167 * for an object type at run-time. 168 */ 169 uint64_t mac_labeled; 170 SYSCTL_UQUAD(_security_mac, OID_AUTO, labeled, CTLFLAG_RD, &mac_labeled, 0, 171 "Mask of object types being labeled"); 172 173 MALLOC_DEFINE(M_MACTEMP, "mactemp", "MAC temporary label storage"); 174 175 /* 176 * MAC policy modules are placed in one of two lists: mac_static_policy_list, 177 * for policies that are loaded early and cannot be unloaded, and 178 * mac_policy_list, which holds policies either loaded later in the boot 179 * cycle or that may be unloaded. The static policy list does not require 180 * locks to iterate over, but the dynamic list requires synchronization. 181 * Support for dynamic policy loading can be compiled out using the 182 * MAC_STATIC kernel option. 183 * 184 * The dynamic policy list is protected by two locks: modifying the list 185 * requires both locks to be held exclusively. One of the locks, 186 * mac_policy_rm, is acquired over policy entry points that will never sleep; 187 * the other, mac_policy_sx, is acquire over policy entry points that may 188 * sleep. The former category will be used when kernel locks may be held 189 * over calls to the MAC Framework, during network processing in ithreads, 190 * etc. The latter will tend to involve potentially blocking memory 191 * allocations, extended attribute I/O, etc. 192 */ 193 #ifndef MAC_STATIC 194 static struct rmlock mac_policy_rm; /* Non-sleeping entry points. */ 195 static struct sx mac_policy_sx; /* Sleeping entry points. */ 196 static struct rmslock mac_policy_rms; 197 #endif 198 199 struct mac_policy_list_head mac_policy_list; 200 struct mac_policy_list_head mac_static_policy_list; 201 u_int mac_policy_count; /* Registered policy count. */ 202 203 static void mac_policy_xlock(void); 204 static void mac_policy_xlock_assert(void); 205 static void mac_policy_xunlock(void); 206 207 void 208 mac_policy_slock_nosleep(struct rm_priotracker *tracker) 209 { 210 211 #ifndef MAC_STATIC 212 if (!mac_late) 213 return; 214 215 rm_rlock(&mac_policy_rm, tracker); 216 #endif 217 } 218 219 void 220 mac_policy_slock_sleep(void) 221 { 222 223 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, 224 "mac_policy_slock_sleep"); 225 226 #ifndef MAC_STATIC 227 if (!mac_late) 228 return; 229 230 rms_rlock(&mac_policy_rms); 231 #endif 232 } 233 234 void 235 mac_policy_sunlock_nosleep(struct rm_priotracker *tracker) 236 { 237 238 #ifndef MAC_STATIC 239 if (!mac_late) 240 return; 241 242 rm_runlock(&mac_policy_rm, tracker); 243 #endif 244 } 245 246 void 247 mac_policy_sunlock_sleep(void) 248 { 249 250 #ifndef MAC_STATIC 251 if (!mac_late) 252 return; 253 254 rms_runlock(&mac_policy_rms); 255 #endif 256 } 257 258 static void 259 mac_policy_xlock(void) 260 { 261 262 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, 263 "mac_policy_xlock()"); 264 265 #ifndef MAC_STATIC 266 if (!mac_late) 267 return; 268 269 sx_xlock(&mac_policy_sx); 270 rms_wlock(&mac_policy_rms); 271 rm_wlock(&mac_policy_rm); 272 #endif 273 } 274 275 static void 276 mac_policy_xunlock(void) 277 { 278 279 #ifndef MAC_STATIC 280 if (!mac_late) 281 return; 282 283 rm_wunlock(&mac_policy_rm); 284 rms_wunlock(&mac_policy_rms); 285 sx_xunlock(&mac_policy_sx); 286 #endif 287 } 288 289 static void 290 mac_policy_xlock_assert(void) 291 { 292 293 #ifndef MAC_STATIC 294 if (!mac_late) 295 return; 296 297 /* XXXRW: rm_assert(&mac_policy_rm, RA_WLOCKED); */ 298 sx_assert(&mac_policy_sx, SA_XLOCKED); 299 #endif 300 } 301 302 /* 303 * Initialize the MAC subsystem, including appropriate SMP locks. 304 */ 305 static void 306 mac_init(void) 307 { 308 309 LIST_INIT(&mac_static_policy_list); 310 LIST_INIT(&mac_policy_list); 311 mac_labelzone_init(); 312 313 #ifndef MAC_STATIC 314 rm_init_flags(&mac_policy_rm, "mac_policy_rm", RM_NOWITNESS | 315 RM_RECURSE); 316 sx_init_flags(&mac_policy_sx, "mac_policy_sx", SX_NOWITNESS); 317 rms_init(&mac_policy_rms, "mac_policy_rms"); 318 #endif 319 } 320 321 /* 322 * For the purposes of modules that want to know if they were loaded "early", 323 * set the mac_late flag once we've processed modules either linked into the 324 * kernel, or loaded before the kernel startup. 325 */ 326 static void 327 mac_late_init(void) 328 { 329 330 mac_late = 1; 331 } 332 333 /* 334 * Given a policy, derive from its set of non-NULL label init methods what 335 * object types the policy is interested in. 336 */ 337 static uint64_t 338 mac_policy_getlabeled(struct mac_policy_conf *mpc) 339 { 340 uint64_t labeled; 341 342 #define MPC_FLAG(method, flag) \ 343 if (mpc->mpc_ops->mpo_ ## method != NULL) \ 344 labeled |= (flag); \ 345 346 labeled = 0; 347 MPC_FLAG(cred_init_label, MPC_OBJECT_CRED); 348 MPC_FLAG(proc_init_label, MPC_OBJECT_PROC); 349 MPC_FLAG(vnode_init_label, MPC_OBJECT_VNODE); 350 MPC_FLAG(inpcb_init_label, MPC_OBJECT_INPCB); 351 MPC_FLAG(socket_init_label, MPC_OBJECT_SOCKET); 352 MPC_FLAG(devfs_init_label, MPC_OBJECT_DEVFS); 353 MPC_FLAG(mbuf_init_label, MPC_OBJECT_MBUF); 354 MPC_FLAG(ipq_init_label, MPC_OBJECT_IPQ); 355 MPC_FLAG(ifnet_init_label, MPC_OBJECT_IFNET); 356 MPC_FLAG(bpfdesc_init_label, MPC_OBJECT_BPFDESC); 357 MPC_FLAG(pipe_init_label, MPC_OBJECT_PIPE); 358 MPC_FLAG(mount_init_label, MPC_OBJECT_MOUNT); 359 MPC_FLAG(posixsem_init_label, MPC_OBJECT_POSIXSEM); 360 MPC_FLAG(posixshm_init_label, MPC_OBJECT_POSIXSHM); 361 MPC_FLAG(sysvmsg_init_label, MPC_OBJECT_SYSVMSG); 362 MPC_FLAG(sysvmsq_init_label, MPC_OBJECT_SYSVMSQ); 363 MPC_FLAG(sysvsem_init_label, MPC_OBJECT_SYSVSEM); 364 MPC_FLAG(sysvshm_init_label, MPC_OBJECT_SYSVSHM); 365 MPC_FLAG(syncache_init_label, MPC_OBJECT_SYNCACHE); 366 MPC_FLAG(ip6q_init_label, MPC_OBJECT_IP6Q); 367 368 #undef MPC_FLAG 369 return (labeled); 370 } 371 372 /* 373 * When policies are loaded or unloaded, walk the list of registered policies 374 * and built mac_labeled, a bitmask representing the union of all objects 375 * requiring labels across all policies. 376 */ 377 static void 378 mac_policy_update(void) 379 { 380 struct mac_policy_conf *mpc; 381 382 mac_policy_xlock_assert(); 383 384 mac_labeled = 0; 385 mac_policy_count = 0; 386 LIST_FOREACH(mpc, &mac_static_policy_list, mpc_list) { 387 mac_labeled |= mac_policy_getlabeled(mpc); 388 mac_policy_count++; 389 } 390 LIST_FOREACH(mpc, &mac_policy_list, mpc_list) { 391 mac_labeled |= mac_policy_getlabeled(mpc); 392 mac_policy_count++; 393 } 394 } 395 396 /* 397 * There are frequently used code paths which check for rarely installed 398 * policies. Gross hack below enables doing it in a cheap manner. 399 */ 400 401 #define FPO(f) (offsetof(struct mac_policy_ops, mpo_##f) / sizeof(uintptr_t)) 402 403 struct mac_policy_fastpath_elem { 404 int count; 405 bool *flag; 406 size_t offset; 407 }; 408 409 struct mac_policy_fastpath_elem mac_policy_fastpath_array[] = { 410 { .offset = FPO(priv_check), .flag = &mac_priv_check_fp_flag }, 411 { .offset = FPO(priv_grant), .flag = &mac_priv_grant_fp_flag }, 412 { .offset = FPO(vnode_check_lookup), 413 .flag = &mac_vnode_check_lookup_fp_flag }, 414 { .offset = FPO(vnode_check_open), 415 .flag = &mac_vnode_check_open_fp_flag }, 416 { .offset = FPO(vnode_check_stat), 417 .flag = &mac_vnode_check_stat_fp_flag }, 418 { .offset = FPO(vnode_check_read), 419 .flag = &mac_vnode_check_read_fp_flag }, 420 { .offset = FPO(vnode_check_write), 421 .flag = &mac_vnode_check_write_fp_flag }, 422 { .offset = FPO(vnode_check_mmap), 423 .flag = &mac_vnode_check_mmap_fp_flag }, 424 }; 425 426 static void 427 mac_policy_fastpath_enable(struct mac_policy_fastpath_elem *mpfe) 428 { 429 430 MPASS(mpfe->count >= 0); 431 mpfe->count++; 432 if (mpfe->count == 1) { 433 MPASS(*mpfe->flag == false); 434 *mpfe->flag = true; 435 } 436 } 437 438 static void 439 mac_policy_fastpath_disable(struct mac_policy_fastpath_elem *mpfe) 440 { 441 442 MPASS(mpfe->count >= 1); 443 mpfe->count--; 444 if (mpfe->count == 0) { 445 MPASS(*mpfe->flag == true); 446 *mpfe->flag = false; 447 } 448 } 449 450 static void 451 mac_policy_fastpath_register(struct mac_policy_conf *mpc) 452 { 453 struct mac_policy_fastpath_elem *mpfe; 454 uintptr_t **ops; 455 int i; 456 457 mac_policy_xlock_assert(); 458 459 ops = (uintptr_t **)mpc->mpc_ops; 460 for (i = 0; i < nitems(mac_policy_fastpath_array); i++) { 461 mpfe = &mac_policy_fastpath_array[i]; 462 if (ops[mpfe->offset] != NULL) 463 mac_policy_fastpath_enable(mpfe); 464 } 465 } 466 467 static void 468 mac_policy_fastpath_unregister(struct mac_policy_conf *mpc) 469 { 470 struct mac_policy_fastpath_elem *mpfe; 471 uintptr_t **ops; 472 int i; 473 474 mac_policy_xlock_assert(); 475 476 ops = (uintptr_t **)mpc->mpc_ops; 477 for (i = 0; i < nitems(mac_policy_fastpath_array); i++) { 478 mpfe = &mac_policy_fastpath_array[i]; 479 if (ops[mpfe->offset] != NULL) 480 mac_policy_fastpath_disable(mpfe); 481 } 482 } 483 484 #undef FPO 485 486 static int 487 mac_policy_register(struct mac_policy_conf *mpc) 488 { 489 struct mac_policy_conf *tmpc; 490 int error, slot, static_entry; 491 492 error = 0; 493 494 /* 495 * We don't technically need exclusive access while !mac_late, but 496 * hold it for assertion consistency. 497 */ 498 mac_policy_xlock(); 499 500 /* 501 * If the module can potentially be unloaded, or we're loading late, 502 * we have to stick it in the non-static list and pay an extra 503 * performance overhead. Otherwise, we can pay a light locking cost 504 * and stick it in the static list. 505 */ 506 static_entry = (!mac_late && 507 !(mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK)); 508 509 if (static_entry) { 510 LIST_FOREACH(tmpc, &mac_static_policy_list, mpc_list) { 511 if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) { 512 error = EEXIST; 513 goto out; 514 } 515 } 516 } else { 517 LIST_FOREACH(tmpc, &mac_policy_list, mpc_list) { 518 if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) { 519 error = EEXIST; 520 goto out; 521 } 522 } 523 } 524 if (mpc->mpc_field_off != NULL) { 525 slot = ffs(mac_slot_offsets_free); 526 if (slot == 0) { 527 error = ENOMEM; 528 goto out; 529 } 530 slot--; 531 mac_slot_offsets_free &= ~(1 << slot); 532 *mpc->mpc_field_off = slot; 533 } 534 mpc->mpc_runtime_flags |= MPC_RUNTIME_FLAG_REGISTERED; 535 536 /* 537 * If we're loading a MAC module after the framework has initialized, 538 * it has to go into the dynamic list. If we're loading it before 539 * we've finished initializing, it can go into the static list with 540 * weaker locker requirements. 541 */ 542 if (static_entry) 543 LIST_INSERT_HEAD(&mac_static_policy_list, mpc, mpc_list); 544 else 545 LIST_INSERT_HEAD(&mac_policy_list, mpc, mpc_list); 546 547 /* 548 * Per-policy initialization. Currently, this takes place under the 549 * exclusive lock, so policies must not sleep in their init method. 550 * In the future, we may want to separate "init" from "start", with 551 * "init" occurring without the lock held. Likewise, on tear-down, 552 * breaking out "stop" from "destroy". 553 */ 554 if (mpc->mpc_ops->mpo_init != NULL) 555 (*(mpc->mpc_ops->mpo_init))(mpc); 556 557 mac_policy_fastpath_register(mpc); 558 559 mac_policy_update(); 560 561 SDT_PROBE1(mac, , policy, register, mpc); 562 printf("Security policy loaded: %s (%s)\n", mpc->mpc_fullname, 563 mpc->mpc_name); 564 565 out: 566 mac_policy_xunlock(); 567 return (error); 568 } 569 570 static int 571 mac_policy_unregister(struct mac_policy_conf *mpc) 572 { 573 574 /* 575 * If we fail the load, we may get a request to unload. Check to see 576 * if we did the run-time registration, and if not, silently succeed. 577 */ 578 mac_policy_xlock(); 579 if ((mpc->mpc_runtime_flags & MPC_RUNTIME_FLAG_REGISTERED) == 0) { 580 mac_policy_xunlock(); 581 return (0); 582 } 583 #if 0 584 /* 585 * Don't allow unloading modules with private data. 586 */ 587 if (mpc->mpc_field_off != NULL) { 588 mac_policy_xunlock(); 589 return (EBUSY); 590 } 591 #endif 592 /* 593 * Only allow the unload to proceed if the module is unloadable by 594 * its own definition. 595 */ 596 if ((mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK) == 0) { 597 mac_policy_xunlock(); 598 return (EBUSY); 599 } 600 601 mac_policy_fastpath_unregister(mpc); 602 603 if (mpc->mpc_ops->mpo_destroy != NULL) 604 (*(mpc->mpc_ops->mpo_destroy))(mpc); 605 606 LIST_REMOVE(mpc, mpc_list); 607 mpc->mpc_runtime_flags &= ~MPC_RUNTIME_FLAG_REGISTERED; 608 mac_policy_update(); 609 mac_policy_xunlock(); 610 611 SDT_PROBE1(mac, , policy, unregister, mpc); 612 printf("Security policy unload: %s (%s)\n", mpc->mpc_fullname, 613 mpc->mpc_name); 614 615 return (0); 616 } 617 618 /* 619 * Allow MAC policy modules to register during boot, etc. 620 */ 621 int 622 mac_policy_modevent(module_t mod, int type, void *data) 623 { 624 struct mac_policy_conf *mpc; 625 int error; 626 627 error = 0; 628 mpc = (struct mac_policy_conf *) data; 629 630 #ifdef MAC_STATIC 631 if (mac_late) { 632 printf("mac_policy_modevent: MAC_STATIC and late\n"); 633 return (EBUSY); 634 } 635 #endif 636 637 SDT_PROBE2(mac, , policy, modevent, type, mpc); 638 switch (type) { 639 case MOD_LOAD: 640 if (mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_NOTLATE && 641 mac_late) { 642 printf("mac_policy_modevent: can't load %s policy " 643 "after booting\n", mpc->mpc_name); 644 error = EBUSY; 645 break; 646 } 647 error = mac_policy_register(mpc); 648 break; 649 case MOD_UNLOAD: 650 /* Don't unregister the module if it was never registered. */ 651 if ((mpc->mpc_runtime_flags & MPC_RUNTIME_FLAG_REGISTERED) 652 != 0) 653 error = mac_policy_unregister(mpc); 654 else 655 error = 0; 656 break; 657 default: 658 error = EOPNOTSUPP; 659 break; 660 } 661 662 return (error); 663 } 664 665 /* 666 * Define an error value precedence, and given two arguments, selects the 667 * value with the higher precedence. 668 */ 669 int 670 mac_error_select(int error1, int error2) 671 { 672 673 /* Certain decision-making errors take top priority. */ 674 if (error1 == EDEADLK || error2 == EDEADLK) 675 return (EDEADLK); 676 677 /* Invalid arguments should be reported where possible. */ 678 if (error1 == EINVAL || error2 == EINVAL) 679 return (EINVAL); 680 681 /* Precedence goes to "visibility", with both process and file. */ 682 if (error1 == ESRCH || error2 == ESRCH) 683 return (ESRCH); 684 685 if (error1 == ENOENT || error2 == ENOENT) 686 return (ENOENT); 687 688 /* Precedence goes to DAC/MAC protections. */ 689 if (error1 == EACCES || error2 == EACCES) 690 return (EACCES); 691 692 /* Precedence goes to privilege. */ 693 if (error1 == EPERM || error2 == EPERM) 694 return (EPERM); 695 696 /* Precedence goes to error over success; otherwise, arbitrary. */ 697 if (error1 != 0) 698 return (error1); 699 return (error2); 700 } 701 702 int 703 mac_check_structmac_consistent(struct mac *mac) 704 { 705 706 /* Require that labels have a non-zero length. */ 707 if (mac->m_buflen > MAC_MAX_LABEL_BUF_LEN || 708 mac->m_buflen <= sizeof("")) 709 return (EINVAL); 710 711 return (0); 712 } 713 714 SYSINIT(mac, SI_SUB_MAC, SI_ORDER_FIRST, mac_init, NULL); 715 SYSINIT(mac_late, SI_SUB_MAC_LATE, SI_ORDER_FIRST, mac_late_init, NULL); 716