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_rms, is acquired 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 rmslock mac_policy_rms; /* Sleeping entry points. */ 196 #endif 197 198 struct mac_policy_list_head mac_policy_list; 199 struct mac_policy_list_head mac_static_policy_list; 200 u_int mac_policy_count; /* Registered policy count. */ 201 202 static void mac_policy_xlock(void); 203 static void mac_policy_xlock_assert(void); 204 static void mac_policy_xunlock(void); 205 206 void 207 mac_policy_slock_nosleep(struct rm_priotracker *tracker) 208 { 209 210 #ifndef MAC_STATIC 211 if (!mac_late) 212 return; 213 214 rm_rlock(&mac_policy_rm, tracker); 215 #endif 216 } 217 218 void 219 mac_policy_slock_sleep(void) 220 { 221 222 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, 223 "mac_policy_slock_sleep"); 224 225 #ifndef MAC_STATIC 226 if (!mac_late) 227 return; 228 229 rms_rlock(&mac_policy_rms); 230 #endif 231 } 232 233 void 234 mac_policy_sunlock_nosleep(struct rm_priotracker *tracker) 235 { 236 237 #ifndef MAC_STATIC 238 if (!mac_late) 239 return; 240 241 rm_runlock(&mac_policy_rm, tracker); 242 #endif 243 } 244 245 void 246 mac_policy_sunlock_sleep(void) 247 { 248 249 #ifndef MAC_STATIC 250 if (!mac_late) 251 return; 252 253 rms_runlock(&mac_policy_rms); 254 #endif 255 } 256 257 static void 258 mac_policy_xlock(void) 259 { 260 261 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, 262 "mac_policy_xlock()"); 263 264 #ifndef MAC_STATIC 265 if (!mac_late) 266 return; 267 268 rms_wlock(&mac_policy_rms); 269 rm_wlock(&mac_policy_rm); 270 #endif 271 } 272 273 static void 274 mac_policy_xunlock(void) 275 { 276 277 #ifndef MAC_STATIC 278 if (!mac_late) 279 return; 280 281 rm_wunlock(&mac_policy_rm); 282 rms_wunlock(&mac_policy_rms); 283 #endif 284 } 285 286 static void 287 mac_policy_xlock_assert(void) 288 { 289 290 #ifndef MAC_STATIC 291 if (!mac_late) 292 return; 293 294 rm_assert(&mac_policy_rm, RA_WLOCKED); 295 #endif 296 } 297 298 /* 299 * Initialize the MAC subsystem, including appropriate SMP locks. 300 */ 301 static void 302 mac_init(void) 303 { 304 305 LIST_INIT(&mac_static_policy_list); 306 LIST_INIT(&mac_policy_list); 307 mac_labelzone_init(); 308 309 #ifndef MAC_STATIC 310 rm_init_flags(&mac_policy_rm, "mac_policy_rm", RM_NOWITNESS | 311 RM_RECURSE); 312 rms_init(&mac_policy_rms, "mac_policy_rms"); 313 #endif 314 } 315 316 /* 317 * For the purposes of modules that want to know if they were loaded "early", 318 * set the mac_late flag once we've processed modules either linked into the 319 * kernel, or loaded before the kernel startup. 320 */ 321 static void 322 mac_late_init(void) 323 { 324 325 mac_late = 1; 326 } 327 328 /* 329 * Given a policy, derive from its set of non-NULL label init methods what 330 * object types the policy is interested in. 331 */ 332 static uint64_t 333 mac_policy_getlabeled(struct mac_policy_conf *mpc) 334 { 335 uint64_t labeled; 336 337 #define MPC_FLAG(method, flag) \ 338 if (mpc->mpc_ops->mpo_ ## method != NULL) \ 339 labeled |= (flag); \ 340 341 labeled = 0; 342 MPC_FLAG(cred_init_label, MPC_OBJECT_CRED); 343 MPC_FLAG(proc_init_label, MPC_OBJECT_PROC); 344 MPC_FLAG(vnode_init_label, MPC_OBJECT_VNODE); 345 MPC_FLAG(inpcb_init_label, MPC_OBJECT_INPCB); 346 MPC_FLAG(socket_init_label, MPC_OBJECT_SOCKET); 347 MPC_FLAG(devfs_init_label, MPC_OBJECT_DEVFS); 348 MPC_FLAG(mbuf_init_label, MPC_OBJECT_MBUF); 349 MPC_FLAG(ipq_init_label, MPC_OBJECT_IPQ); 350 MPC_FLAG(ifnet_init_label, MPC_OBJECT_IFNET); 351 MPC_FLAG(bpfdesc_init_label, MPC_OBJECT_BPFDESC); 352 MPC_FLAG(pipe_init_label, MPC_OBJECT_PIPE); 353 MPC_FLAG(mount_init_label, MPC_OBJECT_MOUNT); 354 MPC_FLAG(posixsem_init_label, MPC_OBJECT_POSIXSEM); 355 MPC_FLAG(posixshm_init_label, MPC_OBJECT_POSIXSHM); 356 MPC_FLAG(sysvmsg_init_label, MPC_OBJECT_SYSVMSG); 357 MPC_FLAG(sysvmsq_init_label, MPC_OBJECT_SYSVMSQ); 358 MPC_FLAG(sysvsem_init_label, MPC_OBJECT_SYSVSEM); 359 MPC_FLAG(sysvshm_init_label, MPC_OBJECT_SYSVSHM); 360 MPC_FLAG(syncache_init_label, MPC_OBJECT_SYNCACHE); 361 MPC_FLAG(ip6q_init_label, MPC_OBJECT_IP6Q); 362 363 #undef MPC_FLAG 364 return (labeled); 365 } 366 367 /* 368 * When policies are loaded or unloaded, walk the list of registered policies 369 * and built mac_labeled, a bitmask representing the union of all objects 370 * requiring labels across all policies. 371 */ 372 static void 373 mac_policy_update(void) 374 { 375 struct mac_policy_conf *mpc; 376 377 mac_policy_xlock_assert(); 378 379 mac_labeled = 0; 380 mac_policy_count = 0; 381 LIST_FOREACH(mpc, &mac_static_policy_list, mpc_list) { 382 mac_labeled |= mac_policy_getlabeled(mpc); 383 mac_policy_count++; 384 } 385 LIST_FOREACH(mpc, &mac_policy_list, mpc_list) { 386 mac_labeled |= mac_policy_getlabeled(mpc); 387 mac_policy_count++; 388 } 389 } 390 391 /* 392 * There are frequently used code paths which check for rarely installed 393 * policies. Gross hack below enables doing it in a cheap manner. 394 */ 395 396 #define FPO(f) (offsetof(struct mac_policy_ops, mpo_##f) / sizeof(uintptr_t)) 397 398 struct mac_policy_fastpath_elem { 399 int count; 400 bool *flag; 401 size_t offset; 402 }; 403 404 struct mac_policy_fastpath_elem mac_policy_fastpath_array[] = { 405 { .offset = FPO(priv_check), .flag = &mac_priv_check_fp_flag }, 406 { .offset = FPO(priv_grant), .flag = &mac_priv_grant_fp_flag }, 407 { .offset = FPO(vnode_check_lookup), 408 .flag = &mac_vnode_check_lookup_fp_flag }, 409 { .offset = FPO(vnode_check_open), 410 .flag = &mac_vnode_check_open_fp_flag }, 411 { .offset = FPO(vnode_check_stat), 412 .flag = &mac_vnode_check_stat_fp_flag }, 413 { .offset = FPO(vnode_check_read), 414 .flag = &mac_vnode_check_read_fp_flag }, 415 { .offset = FPO(vnode_check_write), 416 .flag = &mac_vnode_check_write_fp_flag }, 417 { .offset = FPO(vnode_check_mmap), 418 .flag = &mac_vnode_check_mmap_fp_flag }, 419 }; 420 421 static void 422 mac_policy_fastpath_enable(struct mac_policy_fastpath_elem *mpfe) 423 { 424 425 MPASS(mpfe->count >= 0); 426 mpfe->count++; 427 if (mpfe->count == 1) { 428 MPASS(*mpfe->flag == false); 429 *mpfe->flag = true; 430 } 431 } 432 433 static void 434 mac_policy_fastpath_disable(struct mac_policy_fastpath_elem *mpfe) 435 { 436 437 MPASS(mpfe->count >= 1); 438 mpfe->count--; 439 if (mpfe->count == 0) { 440 MPASS(*mpfe->flag == true); 441 *mpfe->flag = false; 442 } 443 } 444 445 static void 446 mac_policy_fastpath_register(struct mac_policy_conf *mpc) 447 { 448 struct mac_policy_fastpath_elem *mpfe; 449 uintptr_t **ops; 450 int i; 451 452 mac_policy_xlock_assert(); 453 454 ops = (uintptr_t **)mpc->mpc_ops; 455 for (i = 0; i < nitems(mac_policy_fastpath_array); i++) { 456 mpfe = &mac_policy_fastpath_array[i]; 457 if (ops[mpfe->offset] != NULL) 458 mac_policy_fastpath_enable(mpfe); 459 } 460 } 461 462 static void 463 mac_policy_fastpath_unregister(struct mac_policy_conf *mpc) 464 { 465 struct mac_policy_fastpath_elem *mpfe; 466 uintptr_t **ops; 467 int i; 468 469 mac_policy_xlock_assert(); 470 471 ops = (uintptr_t **)mpc->mpc_ops; 472 for (i = 0; i < nitems(mac_policy_fastpath_array); i++) { 473 mpfe = &mac_policy_fastpath_array[i]; 474 if (ops[mpfe->offset] != NULL) 475 mac_policy_fastpath_disable(mpfe); 476 } 477 } 478 479 #undef FPO 480 481 static int 482 mac_policy_register(struct mac_policy_conf *mpc) 483 { 484 struct mac_policy_conf *tmpc; 485 int error, slot, static_entry; 486 487 error = 0; 488 489 /* 490 * We don't technically need exclusive access while !mac_late, but 491 * hold it for assertion consistency. 492 */ 493 mac_policy_xlock(); 494 495 /* 496 * If the module can potentially be unloaded, or we're loading late, 497 * we have to stick it in the non-static list and pay an extra 498 * performance overhead. Otherwise, we can pay a light locking cost 499 * and stick it in the static list. 500 */ 501 static_entry = (!mac_late && 502 !(mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK)); 503 504 if (static_entry) { 505 LIST_FOREACH(tmpc, &mac_static_policy_list, mpc_list) { 506 if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) { 507 error = EEXIST; 508 goto out; 509 } 510 } 511 } else { 512 LIST_FOREACH(tmpc, &mac_policy_list, mpc_list) { 513 if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) { 514 error = EEXIST; 515 goto out; 516 } 517 } 518 } 519 if (mpc->mpc_field_off != NULL) { 520 slot = ffs(mac_slot_offsets_free); 521 if (slot == 0) { 522 error = ENOMEM; 523 goto out; 524 } 525 slot--; 526 mac_slot_offsets_free &= ~(1 << slot); 527 *mpc->mpc_field_off = slot; 528 } 529 mpc->mpc_runtime_flags |= MPC_RUNTIME_FLAG_REGISTERED; 530 531 /* 532 * If we're loading a MAC module after the framework has initialized, 533 * it has to go into the dynamic list. If we're loading it before 534 * we've finished initializing, it can go into the static list with 535 * weaker locker requirements. 536 */ 537 if (static_entry) 538 LIST_INSERT_HEAD(&mac_static_policy_list, mpc, mpc_list); 539 else 540 LIST_INSERT_HEAD(&mac_policy_list, mpc, mpc_list); 541 542 /* 543 * Per-policy initialization. Currently, this takes place under the 544 * exclusive lock, so policies must not sleep in their init method. 545 * In the future, we may want to separate "init" from "start", with 546 * "init" occurring without the lock held. Likewise, on tear-down, 547 * breaking out "stop" from "destroy". 548 */ 549 if (mpc->mpc_ops->mpo_init != NULL) 550 (*(mpc->mpc_ops->mpo_init))(mpc); 551 552 mac_policy_fastpath_register(mpc); 553 554 mac_policy_update(); 555 556 SDT_PROBE1(mac, , policy, register, mpc); 557 printf("Security policy loaded: %s (%s)\n", mpc->mpc_fullname, 558 mpc->mpc_name); 559 560 out: 561 mac_policy_xunlock(); 562 return (error); 563 } 564 565 static int 566 mac_policy_unregister(struct mac_policy_conf *mpc) 567 { 568 569 /* 570 * If we fail the load, we may get a request to unload. Check to see 571 * if we did the run-time registration, and if not, silently succeed. 572 */ 573 mac_policy_xlock(); 574 if ((mpc->mpc_runtime_flags & MPC_RUNTIME_FLAG_REGISTERED) == 0) { 575 mac_policy_xunlock(); 576 return (0); 577 } 578 #if 0 579 /* 580 * Don't allow unloading modules with private data. 581 */ 582 if (mpc->mpc_field_off != NULL) { 583 mac_policy_xunlock(); 584 return (EBUSY); 585 } 586 #endif 587 /* 588 * Only allow the unload to proceed if the module is unloadable by 589 * its own definition. 590 */ 591 if ((mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK) == 0) { 592 mac_policy_xunlock(); 593 return (EBUSY); 594 } 595 596 mac_policy_fastpath_unregister(mpc); 597 598 if (mpc->mpc_ops->mpo_destroy != NULL) 599 (*(mpc->mpc_ops->mpo_destroy))(mpc); 600 601 LIST_REMOVE(mpc, mpc_list); 602 mpc->mpc_runtime_flags &= ~MPC_RUNTIME_FLAG_REGISTERED; 603 mac_policy_update(); 604 mac_policy_xunlock(); 605 606 SDT_PROBE1(mac, , policy, unregister, mpc); 607 printf("Security policy unload: %s (%s)\n", mpc->mpc_fullname, 608 mpc->mpc_name); 609 610 return (0); 611 } 612 613 /* 614 * Allow MAC policy modules to register during boot, etc. 615 */ 616 int 617 mac_policy_modevent(module_t mod, int type, void *data) 618 { 619 struct mac_policy_conf *mpc; 620 int error; 621 622 error = 0; 623 mpc = (struct mac_policy_conf *) data; 624 625 #ifdef MAC_STATIC 626 if (mac_late) { 627 printf("mac_policy_modevent: MAC_STATIC and late\n"); 628 return (EBUSY); 629 } 630 #endif 631 632 SDT_PROBE2(mac, , policy, modevent, type, mpc); 633 switch (type) { 634 case MOD_LOAD: 635 if (mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_NOTLATE && 636 mac_late) { 637 printf("mac_policy_modevent: can't load %s policy " 638 "after booting\n", mpc->mpc_name); 639 error = EBUSY; 640 break; 641 } 642 error = mac_policy_register(mpc); 643 break; 644 case MOD_UNLOAD: 645 /* Don't unregister the module if it was never registered. */ 646 if ((mpc->mpc_runtime_flags & MPC_RUNTIME_FLAG_REGISTERED) 647 != 0) 648 error = mac_policy_unregister(mpc); 649 else 650 error = 0; 651 break; 652 default: 653 error = EOPNOTSUPP; 654 break; 655 } 656 657 return (error); 658 } 659 660 /* 661 * Define an error value precedence, and given two arguments, selects the 662 * value with the higher precedence. 663 */ 664 int 665 mac_error_select(int error1, int error2) 666 { 667 668 /* Certain decision-making errors take top priority. */ 669 if (error1 == EDEADLK || error2 == EDEADLK) 670 return (EDEADLK); 671 672 /* Invalid arguments should be reported where possible. */ 673 if (error1 == EINVAL || error2 == EINVAL) 674 return (EINVAL); 675 676 /* Precedence goes to "visibility", with both process and file. */ 677 if (error1 == ESRCH || error2 == ESRCH) 678 return (ESRCH); 679 680 if (error1 == ENOENT || error2 == ENOENT) 681 return (ENOENT); 682 683 /* Precedence goes to DAC/MAC protections. */ 684 if (error1 == EACCES || error2 == EACCES) 685 return (EACCES); 686 687 /* Precedence goes to privilege. */ 688 if (error1 == EPERM || error2 == EPERM) 689 return (EPERM); 690 691 /* Precedence goes to error over success; otherwise, arbitrary. */ 692 if (error1 != 0) 693 return (error1); 694 return (error2); 695 } 696 697 int 698 mac_check_structmac_consistent(struct mac *mac) 699 { 700 701 /* Require that labels have a non-zero length. */ 702 if (mac->m_buflen > MAC_MAX_LABEL_BUF_LEN || 703 mac->m_buflen <= sizeof("")) 704 return (EINVAL); 705 706 return (0); 707 } 708 709 SYSINIT(mac, SI_SUB_MAC, SI_ORDER_FIRST, mac_init, NULL); 710 SYSINIT(mac_late, SI_SUB_MAC_LATE, SI_ORDER_FIRST, mac_late_init, NULL); 711