1 /* auditfilter.c -- filtering of audit events 2 * 3 * Copyright 2003-2004 Red Hat, Inc. 4 * Copyright 2005 Hewlett-Packard Development Company, L.P. 5 * Copyright 2005 IBM Corporation 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21 22 #include <linux/kernel.h> 23 #include <linux/audit.h> 24 #include <linux/kthread.h> 25 #include <linux/mutex.h> 26 #include <linux/fs.h> 27 #include <linux/namei.h> 28 #include <linux/netlink.h> 29 #include <linux/sched.h> 30 #include <linux/slab.h> 31 #include <linux/security.h> 32 #include "audit.h" 33 34 /* 35 * Locking model: 36 * 37 * audit_filter_mutex: 38 * Synchronizes writes and blocking reads of audit's filterlist 39 * data. Rcu is used to traverse the filterlist and access 40 * contents of structs audit_entry, audit_watch and opaque 41 * LSM rules during filtering. If modified, these structures 42 * must be copied and replace their counterparts in the filterlist. 43 * An audit_parent struct is not accessed during filtering, so may 44 * be written directly provided audit_filter_mutex is held. 45 */ 46 47 /* Audit filter lists, defined in <linux/audit.h> */ 48 struct list_head audit_filter_list[AUDIT_NR_FILTERS] = { 49 LIST_HEAD_INIT(audit_filter_list[0]), 50 LIST_HEAD_INIT(audit_filter_list[1]), 51 LIST_HEAD_INIT(audit_filter_list[2]), 52 LIST_HEAD_INIT(audit_filter_list[3]), 53 LIST_HEAD_INIT(audit_filter_list[4]), 54 LIST_HEAD_INIT(audit_filter_list[5]), 55 #if AUDIT_NR_FILTERS != 6 56 #error Fix audit_filter_list initialiser 57 #endif 58 }; 59 static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = { 60 LIST_HEAD_INIT(audit_rules_list[0]), 61 LIST_HEAD_INIT(audit_rules_list[1]), 62 LIST_HEAD_INIT(audit_rules_list[2]), 63 LIST_HEAD_INIT(audit_rules_list[3]), 64 LIST_HEAD_INIT(audit_rules_list[4]), 65 LIST_HEAD_INIT(audit_rules_list[5]), 66 }; 67 68 DEFINE_MUTEX(audit_filter_mutex); 69 70 static inline void audit_free_rule(struct audit_entry *e) 71 { 72 int i; 73 struct audit_krule *erule = &e->rule; 74 75 /* some rules don't have associated watches */ 76 if (erule->watch) 77 audit_put_watch(erule->watch); 78 if (erule->fields) 79 for (i = 0; i < erule->field_count; i++) { 80 struct audit_field *f = &erule->fields[i]; 81 kfree(f->lsm_str); 82 security_audit_rule_free(f->lsm_rule); 83 } 84 kfree(erule->fields); 85 kfree(erule->filterkey); 86 kfree(e); 87 } 88 89 void audit_free_rule_rcu(struct rcu_head *head) 90 { 91 struct audit_entry *e = container_of(head, struct audit_entry, rcu); 92 audit_free_rule(e); 93 } 94 95 /* Initialize an audit filterlist entry. */ 96 static inline struct audit_entry *audit_init_entry(u32 field_count) 97 { 98 struct audit_entry *entry; 99 struct audit_field *fields; 100 101 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 102 if (unlikely(!entry)) 103 return NULL; 104 105 fields = kzalloc(sizeof(*fields) * field_count, GFP_KERNEL); 106 if (unlikely(!fields)) { 107 kfree(entry); 108 return NULL; 109 } 110 entry->rule.fields = fields; 111 112 return entry; 113 } 114 115 /* Unpack a filter field's string representation from user-space 116 * buffer. */ 117 char *audit_unpack_string(void **bufp, size_t *remain, size_t len) 118 { 119 char *str; 120 121 if (!*bufp || (len == 0) || (len > *remain)) 122 return ERR_PTR(-EINVAL); 123 124 /* Of the currently implemented string fields, PATH_MAX 125 * defines the longest valid length. 126 */ 127 if (len > PATH_MAX) 128 return ERR_PTR(-ENAMETOOLONG); 129 130 str = kmalloc(len + 1, GFP_KERNEL); 131 if (unlikely(!str)) 132 return ERR_PTR(-ENOMEM); 133 134 memcpy(str, *bufp, len); 135 str[len] = 0; 136 *bufp += len; 137 *remain -= len; 138 139 return str; 140 } 141 142 /* Translate an inode field to kernel respresentation. */ 143 static inline int audit_to_inode(struct audit_krule *krule, 144 struct audit_field *f) 145 { 146 if (krule->listnr != AUDIT_FILTER_EXIT || 147 krule->watch || krule->inode_f || krule->tree || 148 (f->op != Audit_equal && f->op != Audit_not_equal)) 149 return -EINVAL; 150 151 krule->inode_f = f; 152 return 0; 153 } 154 155 static __u32 *classes[AUDIT_SYSCALL_CLASSES]; 156 157 int __init audit_register_class(int class, unsigned *list) 158 { 159 __u32 *p = kzalloc(AUDIT_BITMASK_SIZE * sizeof(__u32), GFP_KERNEL); 160 if (!p) 161 return -ENOMEM; 162 while (*list != ~0U) { 163 unsigned n = *list++; 164 if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) { 165 kfree(p); 166 return -EINVAL; 167 } 168 p[AUDIT_WORD(n)] |= AUDIT_BIT(n); 169 } 170 if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) { 171 kfree(p); 172 return -EINVAL; 173 } 174 classes[class] = p; 175 return 0; 176 } 177 178 int audit_match_class(int class, unsigned syscall) 179 { 180 if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32)) 181 return 0; 182 if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class])) 183 return 0; 184 return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall); 185 } 186 187 #ifdef CONFIG_AUDITSYSCALL 188 static inline int audit_match_class_bits(int class, u32 *mask) 189 { 190 int i; 191 192 if (classes[class]) { 193 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) 194 if (mask[i] & classes[class][i]) 195 return 0; 196 } 197 return 1; 198 } 199 200 static int audit_match_signal(struct audit_entry *entry) 201 { 202 struct audit_field *arch = entry->rule.arch_f; 203 204 if (!arch) { 205 /* When arch is unspecified, we must check both masks on biarch 206 * as syscall number alone is ambiguous. */ 207 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL, 208 entry->rule.mask) && 209 audit_match_class_bits(AUDIT_CLASS_SIGNAL_32, 210 entry->rule.mask)); 211 } 212 213 switch(audit_classify_arch(arch->val)) { 214 case 0: /* native */ 215 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL, 216 entry->rule.mask)); 217 case 1: /* 32bit on biarch */ 218 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32, 219 entry->rule.mask)); 220 default: 221 return 1; 222 } 223 } 224 #endif 225 226 /* Common user-space to kernel rule translation. */ 227 static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule) 228 { 229 unsigned listnr; 230 struct audit_entry *entry; 231 int i, err; 232 233 err = -EINVAL; 234 listnr = rule->flags & ~AUDIT_FILTER_PREPEND; 235 switch(listnr) { 236 default: 237 goto exit_err; 238 #ifdef CONFIG_AUDITSYSCALL 239 case AUDIT_FILTER_ENTRY: 240 if (rule->action == AUDIT_ALWAYS) 241 goto exit_err; 242 case AUDIT_FILTER_EXIT: 243 case AUDIT_FILTER_TASK: 244 #endif 245 case AUDIT_FILTER_USER: 246 case AUDIT_FILTER_TYPE: 247 ; 248 } 249 if (unlikely(rule->action == AUDIT_POSSIBLE)) { 250 printk(KERN_ERR "AUDIT_POSSIBLE is deprecated\n"); 251 goto exit_err; 252 } 253 if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS) 254 goto exit_err; 255 if (rule->field_count > AUDIT_MAX_FIELDS) 256 goto exit_err; 257 258 err = -ENOMEM; 259 entry = audit_init_entry(rule->field_count); 260 if (!entry) 261 goto exit_err; 262 263 entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND; 264 entry->rule.listnr = listnr; 265 entry->rule.action = rule->action; 266 entry->rule.field_count = rule->field_count; 267 268 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) 269 entry->rule.mask[i] = rule->mask[i]; 270 271 for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) { 272 int bit = AUDIT_BITMASK_SIZE * 32 - i - 1; 273 __u32 *p = &entry->rule.mask[AUDIT_WORD(bit)]; 274 __u32 *class; 275 276 if (!(*p & AUDIT_BIT(bit))) 277 continue; 278 *p &= ~AUDIT_BIT(bit); 279 class = classes[i]; 280 if (class) { 281 int j; 282 for (j = 0; j < AUDIT_BITMASK_SIZE; j++) 283 entry->rule.mask[j] |= class[j]; 284 } 285 } 286 287 return entry; 288 289 exit_err: 290 return ERR_PTR(err); 291 } 292 293 static u32 audit_ops[] = 294 { 295 [Audit_equal] = AUDIT_EQUAL, 296 [Audit_not_equal] = AUDIT_NOT_EQUAL, 297 [Audit_bitmask] = AUDIT_BIT_MASK, 298 [Audit_bittest] = AUDIT_BIT_TEST, 299 [Audit_lt] = AUDIT_LESS_THAN, 300 [Audit_gt] = AUDIT_GREATER_THAN, 301 [Audit_le] = AUDIT_LESS_THAN_OR_EQUAL, 302 [Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL, 303 }; 304 305 static u32 audit_to_op(u32 op) 306 { 307 u32 n; 308 for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++) 309 ; 310 return n; 311 } 312 313 /* check if an audit field is valid */ 314 static int audit_field_valid(struct audit_entry *entry, struct audit_field *f) 315 { 316 switch(f->type) { 317 case AUDIT_MSGTYPE: 318 if (entry->rule.listnr != AUDIT_FILTER_TYPE && 319 entry->rule.listnr != AUDIT_FILTER_USER) 320 return -EINVAL; 321 break; 322 }; 323 324 switch(f->type) { 325 default: 326 return -EINVAL; 327 case AUDIT_UID: 328 case AUDIT_EUID: 329 case AUDIT_SUID: 330 case AUDIT_FSUID: 331 case AUDIT_LOGINUID: 332 case AUDIT_OBJ_UID: 333 case AUDIT_GID: 334 case AUDIT_EGID: 335 case AUDIT_SGID: 336 case AUDIT_FSGID: 337 case AUDIT_OBJ_GID: 338 case AUDIT_PID: 339 case AUDIT_PERS: 340 case AUDIT_MSGTYPE: 341 case AUDIT_PPID: 342 case AUDIT_DEVMAJOR: 343 case AUDIT_DEVMINOR: 344 case AUDIT_EXIT: 345 case AUDIT_SUCCESS: 346 /* bit ops are only useful on syscall args */ 347 if (f->op == Audit_bitmask || f->op == Audit_bittest) 348 return -EINVAL; 349 break; 350 case AUDIT_ARG0: 351 case AUDIT_ARG1: 352 case AUDIT_ARG2: 353 case AUDIT_ARG3: 354 case AUDIT_SUBJ_USER: 355 case AUDIT_SUBJ_ROLE: 356 case AUDIT_SUBJ_TYPE: 357 case AUDIT_SUBJ_SEN: 358 case AUDIT_SUBJ_CLR: 359 case AUDIT_OBJ_USER: 360 case AUDIT_OBJ_ROLE: 361 case AUDIT_OBJ_TYPE: 362 case AUDIT_OBJ_LEV_LOW: 363 case AUDIT_OBJ_LEV_HIGH: 364 case AUDIT_WATCH: 365 case AUDIT_DIR: 366 case AUDIT_FILTERKEY: 367 break; 368 case AUDIT_LOGINUID_SET: 369 if ((f->val != 0) && (f->val != 1)) 370 return -EINVAL; 371 /* FALL THROUGH */ 372 case AUDIT_ARCH: 373 if (f->op != Audit_not_equal && f->op != Audit_equal) 374 return -EINVAL; 375 break; 376 case AUDIT_PERM: 377 if (f->val & ~15) 378 return -EINVAL; 379 break; 380 case AUDIT_FILETYPE: 381 if (f->val & ~S_IFMT) 382 return -EINVAL; 383 break; 384 case AUDIT_FIELD_COMPARE: 385 if (f->val > AUDIT_MAX_FIELD_COMPARE) 386 return -EINVAL; 387 break; 388 }; 389 return 0; 390 } 391 392 /* Translate struct audit_rule_data to kernel's rule respresentation. */ 393 static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data, 394 size_t datasz) 395 { 396 int err = 0; 397 struct audit_entry *entry; 398 void *bufp; 399 size_t remain = datasz - sizeof(struct audit_rule_data); 400 int i; 401 char *str; 402 403 entry = audit_to_entry_common((struct audit_rule *)data); 404 if (IS_ERR(entry)) 405 goto exit_nofree; 406 407 bufp = data->buf; 408 entry->rule.vers_ops = 2; 409 for (i = 0; i < data->field_count; i++) { 410 struct audit_field *f = &entry->rule.fields[i]; 411 412 err = -EINVAL; 413 414 f->op = audit_to_op(data->fieldflags[i]); 415 if (f->op == Audit_bad) 416 goto exit_free; 417 418 f->type = data->fields[i]; 419 f->val = data->values[i]; 420 f->uid = INVALID_UID; 421 f->gid = INVALID_GID; 422 f->lsm_str = NULL; 423 f->lsm_rule = NULL; 424 425 /* Support legacy tests for a valid loginuid */ 426 if ((f->type == AUDIT_LOGINUID) && (f->val == 4294967295)) { 427 f->type = AUDIT_LOGINUID_SET; 428 f->val = 0; 429 } 430 431 err = audit_field_valid(entry, f); 432 if (err) 433 goto exit_free; 434 435 err = -EINVAL; 436 switch (f->type) { 437 case AUDIT_LOGINUID: 438 case AUDIT_UID: 439 case AUDIT_EUID: 440 case AUDIT_SUID: 441 case AUDIT_FSUID: 442 case AUDIT_OBJ_UID: 443 f->uid = make_kuid(current_user_ns(), f->val); 444 if (!uid_valid(f->uid)) 445 goto exit_free; 446 break; 447 case AUDIT_GID: 448 case AUDIT_EGID: 449 case AUDIT_SGID: 450 case AUDIT_FSGID: 451 case AUDIT_OBJ_GID: 452 f->gid = make_kgid(current_user_ns(), f->val); 453 if (!gid_valid(f->gid)) 454 goto exit_free; 455 break; 456 case AUDIT_ARCH: 457 entry->rule.arch_f = f; 458 break; 459 case AUDIT_SUBJ_USER: 460 case AUDIT_SUBJ_ROLE: 461 case AUDIT_SUBJ_TYPE: 462 case AUDIT_SUBJ_SEN: 463 case AUDIT_SUBJ_CLR: 464 case AUDIT_OBJ_USER: 465 case AUDIT_OBJ_ROLE: 466 case AUDIT_OBJ_TYPE: 467 case AUDIT_OBJ_LEV_LOW: 468 case AUDIT_OBJ_LEV_HIGH: 469 str = audit_unpack_string(&bufp, &remain, f->val); 470 if (IS_ERR(str)) 471 goto exit_free; 472 entry->rule.buflen += f->val; 473 474 err = security_audit_rule_init(f->type, f->op, str, 475 (void **)&f->lsm_rule); 476 /* Keep currently invalid fields around in case they 477 * become valid after a policy reload. */ 478 if (err == -EINVAL) { 479 printk(KERN_WARNING "audit rule for LSM " 480 "\'%s\' is invalid\n", str); 481 err = 0; 482 } 483 if (err) { 484 kfree(str); 485 goto exit_free; 486 } else 487 f->lsm_str = str; 488 break; 489 case AUDIT_WATCH: 490 str = audit_unpack_string(&bufp, &remain, f->val); 491 if (IS_ERR(str)) 492 goto exit_free; 493 entry->rule.buflen += f->val; 494 495 err = audit_to_watch(&entry->rule, str, f->val, f->op); 496 if (err) { 497 kfree(str); 498 goto exit_free; 499 } 500 break; 501 case AUDIT_DIR: 502 str = audit_unpack_string(&bufp, &remain, f->val); 503 if (IS_ERR(str)) 504 goto exit_free; 505 entry->rule.buflen += f->val; 506 507 err = audit_make_tree(&entry->rule, str, f->op); 508 kfree(str); 509 if (err) 510 goto exit_free; 511 break; 512 case AUDIT_INODE: 513 err = audit_to_inode(&entry->rule, f); 514 if (err) 515 goto exit_free; 516 break; 517 case AUDIT_FILTERKEY: 518 if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN) 519 goto exit_free; 520 str = audit_unpack_string(&bufp, &remain, f->val); 521 if (IS_ERR(str)) 522 goto exit_free; 523 entry->rule.buflen += f->val; 524 entry->rule.filterkey = str; 525 break; 526 } 527 } 528 529 if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal) 530 entry->rule.inode_f = NULL; 531 532 exit_nofree: 533 return entry; 534 535 exit_free: 536 audit_free_rule(entry); 537 return ERR_PTR(err); 538 } 539 540 /* Pack a filter field's string representation into data block. */ 541 static inline size_t audit_pack_string(void **bufp, const char *str) 542 { 543 size_t len = strlen(str); 544 545 memcpy(*bufp, str, len); 546 *bufp += len; 547 548 return len; 549 } 550 551 /* Translate kernel rule respresentation to struct audit_rule_data. */ 552 static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule) 553 { 554 struct audit_rule_data *data; 555 void *bufp; 556 int i; 557 558 data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL); 559 if (unlikely(!data)) 560 return NULL; 561 memset(data, 0, sizeof(*data)); 562 563 data->flags = krule->flags | krule->listnr; 564 data->action = krule->action; 565 data->field_count = krule->field_count; 566 bufp = data->buf; 567 for (i = 0; i < data->field_count; i++) { 568 struct audit_field *f = &krule->fields[i]; 569 570 data->fields[i] = f->type; 571 data->fieldflags[i] = audit_ops[f->op]; 572 switch(f->type) { 573 case AUDIT_SUBJ_USER: 574 case AUDIT_SUBJ_ROLE: 575 case AUDIT_SUBJ_TYPE: 576 case AUDIT_SUBJ_SEN: 577 case AUDIT_SUBJ_CLR: 578 case AUDIT_OBJ_USER: 579 case AUDIT_OBJ_ROLE: 580 case AUDIT_OBJ_TYPE: 581 case AUDIT_OBJ_LEV_LOW: 582 case AUDIT_OBJ_LEV_HIGH: 583 data->buflen += data->values[i] = 584 audit_pack_string(&bufp, f->lsm_str); 585 break; 586 case AUDIT_WATCH: 587 data->buflen += data->values[i] = 588 audit_pack_string(&bufp, 589 audit_watch_path(krule->watch)); 590 break; 591 case AUDIT_DIR: 592 data->buflen += data->values[i] = 593 audit_pack_string(&bufp, 594 audit_tree_path(krule->tree)); 595 break; 596 case AUDIT_FILTERKEY: 597 data->buflen += data->values[i] = 598 audit_pack_string(&bufp, krule->filterkey); 599 break; 600 default: 601 data->values[i] = f->val; 602 } 603 } 604 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i]; 605 606 return data; 607 } 608 609 /* Compare two rules in kernel format. Considered success if rules 610 * don't match. */ 611 static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b) 612 { 613 int i; 614 615 if (a->flags != b->flags || 616 a->listnr != b->listnr || 617 a->action != b->action || 618 a->field_count != b->field_count) 619 return 1; 620 621 for (i = 0; i < a->field_count; i++) { 622 if (a->fields[i].type != b->fields[i].type || 623 a->fields[i].op != b->fields[i].op) 624 return 1; 625 626 switch(a->fields[i].type) { 627 case AUDIT_SUBJ_USER: 628 case AUDIT_SUBJ_ROLE: 629 case AUDIT_SUBJ_TYPE: 630 case AUDIT_SUBJ_SEN: 631 case AUDIT_SUBJ_CLR: 632 case AUDIT_OBJ_USER: 633 case AUDIT_OBJ_ROLE: 634 case AUDIT_OBJ_TYPE: 635 case AUDIT_OBJ_LEV_LOW: 636 case AUDIT_OBJ_LEV_HIGH: 637 if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str)) 638 return 1; 639 break; 640 case AUDIT_WATCH: 641 if (strcmp(audit_watch_path(a->watch), 642 audit_watch_path(b->watch))) 643 return 1; 644 break; 645 case AUDIT_DIR: 646 if (strcmp(audit_tree_path(a->tree), 647 audit_tree_path(b->tree))) 648 return 1; 649 break; 650 case AUDIT_FILTERKEY: 651 /* both filterkeys exist based on above type compare */ 652 if (strcmp(a->filterkey, b->filterkey)) 653 return 1; 654 break; 655 case AUDIT_UID: 656 case AUDIT_EUID: 657 case AUDIT_SUID: 658 case AUDIT_FSUID: 659 case AUDIT_LOGINUID: 660 case AUDIT_OBJ_UID: 661 if (!uid_eq(a->fields[i].uid, b->fields[i].uid)) 662 return 1; 663 break; 664 case AUDIT_GID: 665 case AUDIT_EGID: 666 case AUDIT_SGID: 667 case AUDIT_FSGID: 668 case AUDIT_OBJ_GID: 669 if (!gid_eq(a->fields[i].gid, b->fields[i].gid)) 670 return 1; 671 break; 672 default: 673 if (a->fields[i].val != b->fields[i].val) 674 return 1; 675 } 676 } 677 678 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) 679 if (a->mask[i] != b->mask[i]) 680 return 1; 681 682 return 0; 683 } 684 685 /* Duplicate LSM field information. The lsm_rule is opaque, so must be 686 * re-initialized. */ 687 static inline int audit_dupe_lsm_field(struct audit_field *df, 688 struct audit_field *sf) 689 { 690 int ret = 0; 691 char *lsm_str; 692 693 /* our own copy of lsm_str */ 694 lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL); 695 if (unlikely(!lsm_str)) 696 return -ENOMEM; 697 df->lsm_str = lsm_str; 698 699 /* our own (refreshed) copy of lsm_rule */ 700 ret = security_audit_rule_init(df->type, df->op, df->lsm_str, 701 (void **)&df->lsm_rule); 702 /* Keep currently invalid fields around in case they 703 * become valid after a policy reload. */ 704 if (ret == -EINVAL) { 705 printk(KERN_WARNING "audit rule for LSM \'%s\' is " 706 "invalid\n", df->lsm_str); 707 ret = 0; 708 } 709 710 return ret; 711 } 712 713 /* Duplicate an audit rule. This will be a deep copy with the exception 714 * of the watch - that pointer is carried over. The LSM specific fields 715 * will be updated in the copy. The point is to be able to replace the old 716 * rule with the new rule in the filterlist, then free the old rule. 717 * The rlist element is undefined; list manipulations are handled apart from 718 * the initial copy. */ 719 struct audit_entry *audit_dupe_rule(struct audit_krule *old) 720 { 721 u32 fcount = old->field_count; 722 struct audit_entry *entry; 723 struct audit_krule *new; 724 char *fk; 725 int i, err = 0; 726 727 entry = audit_init_entry(fcount); 728 if (unlikely(!entry)) 729 return ERR_PTR(-ENOMEM); 730 731 new = &entry->rule; 732 new->vers_ops = old->vers_ops; 733 new->flags = old->flags; 734 new->listnr = old->listnr; 735 new->action = old->action; 736 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) 737 new->mask[i] = old->mask[i]; 738 new->prio = old->prio; 739 new->buflen = old->buflen; 740 new->inode_f = old->inode_f; 741 new->field_count = old->field_count; 742 743 /* 744 * note that we are OK with not refcounting here; audit_match_tree() 745 * never dereferences tree and we can't get false positives there 746 * since we'd have to have rule gone from the list *and* removed 747 * before the chunks found by lookup had been allocated, i.e. before 748 * the beginning of list scan. 749 */ 750 new->tree = old->tree; 751 memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount); 752 753 /* deep copy this information, updating the lsm_rule fields, because 754 * the originals will all be freed when the old rule is freed. */ 755 for (i = 0; i < fcount; i++) { 756 switch (new->fields[i].type) { 757 case AUDIT_SUBJ_USER: 758 case AUDIT_SUBJ_ROLE: 759 case AUDIT_SUBJ_TYPE: 760 case AUDIT_SUBJ_SEN: 761 case AUDIT_SUBJ_CLR: 762 case AUDIT_OBJ_USER: 763 case AUDIT_OBJ_ROLE: 764 case AUDIT_OBJ_TYPE: 765 case AUDIT_OBJ_LEV_LOW: 766 case AUDIT_OBJ_LEV_HIGH: 767 err = audit_dupe_lsm_field(&new->fields[i], 768 &old->fields[i]); 769 break; 770 case AUDIT_FILTERKEY: 771 fk = kstrdup(old->filterkey, GFP_KERNEL); 772 if (unlikely(!fk)) 773 err = -ENOMEM; 774 else 775 new->filterkey = fk; 776 } 777 if (err) { 778 audit_free_rule(entry); 779 return ERR_PTR(err); 780 } 781 } 782 783 if (old->watch) { 784 audit_get_watch(old->watch); 785 new->watch = old->watch; 786 } 787 788 return entry; 789 } 790 791 /* Find an existing audit rule. 792 * Caller must hold audit_filter_mutex to prevent stale rule data. */ 793 static struct audit_entry *audit_find_rule(struct audit_entry *entry, 794 struct list_head **p) 795 { 796 struct audit_entry *e, *found = NULL; 797 struct list_head *list; 798 int h; 799 800 if (entry->rule.inode_f) { 801 h = audit_hash_ino(entry->rule.inode_f->val); 802 *p = list = &audit_inode_hash[h]; 803 } else if (entry->rule.watch) { 804 /* we don't know the inode number, so must walk entire hash */ 805 for (h = 0; h < AUDIT_INODE_BUCKETS; h++) { 806 list = &audit_inode_hash[h]; 807 list_for_each_entry(e, list, list) 808 if (!audit_compare_rule(&entry->rule, &e->rule)) { 809 found = e; 810 goto out; 811 } 812 } 813 goto out; 814 } else { 815 *p = list = &audit_filter_list[entry->rule.listnr]; 816 } 817 818 list_for_each_entry(e, list, list) 819 if (!audit_compare_rule(&entry->rule, &e->rule)) { 820 found = e; 821 goto out; 822 } 823 824 out: 825 return found; 826 } 827 828 static u64 prio_low = ~0ULL/2; 829 static u64 prio_high = ~0ULL/2 - 1; 830 831 /* Add rule to given filterlist if not a duplicate. */ 832 static inline int audit_add_rule(struct audit_entry *entry) 833 { 834 struct audit_entry *e; 835 struct audit_watch *watch = entry->rule.watch; 836 struct audit_tree *tree = entry->rule.tree; 837 struct list_head *list; 838 int err; 839 #ifdef CONFIG_AUDITSYSCALL 840 int dont_count = 0; 841 842 /* If either of these, don't count towards total */ 843 if (entry->rule.listnr == AUDIT_FILTER_USER || 844 entry->rule.listnr == AUDIT_FILTER_TYPE) 845 dont_count = 1; 846 #endif 847 848 mutex_lock(&audit_filter_mutex); 849 e = audit_find_rule(entry, &list); 850 if (e) { 851 mutex_unlock(&audit_filter_mutex); 852 err = -EEXIST; 853 /* normally audit_add_tree_rule() will free it on failure */ 854 if (tree) 855 audit_put_tree(tree); 856 goto error; 857 } 858 859 if (watch) { 860 /* audit_filter_mutex is dropped and re-taken during this call */ 861 err = audit_add_watch(&entry->rule, &list); 862 if (err) { 863 mutex_unlock(&audit_filter_mutex); 864 goto error; 865 } 866 } 867 if (tree) { 868 err = audit_add_tree_rule(&entry->rule); 869 if (err) { 870 mutex_unlock(&audit_filter_mutex); 871 goto error; 872 } 873 } 874 875 entry->rule.prio = ~0ULL; 876 if (entry->rule.listnr == AUDIT_FILTER_EXIT) { 877 if (entry->rule.flags & AUDIT_FILTER_PREPEND) 878 entry->rule.prio = ++prio_high; 879 else 880 entry->rule.prio = --prio_low; 881 } 882 883 if (entry->rule.flags & AUDIT_FILTER_PREPEND) { 884 list_add(&entry->rule.list, 885 &audit_rules_list[entry->rule.listnr]); 886 list_add_rcu(&entry->list, list); 887 entry->rule.flags &= ~AUDIT_FILTER_PREPEND; 888 } else { 889 list_add_tail(&entry->rule.list, 890 &audit_rules_list[entry->rule.listnr]); 891 list_add_tail_rcu(&entry->list, list); 892 } 893 #ifdef CONFIG_AUDITSYSCALL 894 if (!dont_count) 895 audit_n_rules++; 896 897 if (!audit_match_signal(entry)) 898 audit_signals++; 899 #endif 900 mutex_unlock(&audit_filter_mutex); 901 902 return 0; 903 904 error: 905 if (watch) 906 audit_put_watch(watch); /* tmp watch, matches initial get */ 907 return err; 908 } 909 910 /* Remove an existing rule from filterlist. */ 911 static inline int audit_del_rule(struct audit_entry *entry) 912 { 913 struct audit_entry *e; 914 struct audit_watch *watch = entry->rule.watch; 915 struct audit_tree *tree = entry->rule.tree; 916 struct list_head *list; 917 int ret = 0; 918 #ifdef CONFIG_AUDITSYSCALL 919 int dont_count = 0; 920 921 /* If either of these, don't count towards total */ 922 if (entry->rule.listnr == AUDIT_FILTER_USER || 923 entry->rule.listnr == AUDIT_FILTER_TYPE) 924 dont_count = 1; 925 #endif 926 927 mutex_lock(&audit_filter_mutex); 928 e = audit_find_rule(entry, &list); 929 if (!e) { 930 mutex_unlock(&audit_filter_mutex); 931 ret = -ENOENT; 932 goto out; 933 } 934 935 if (e->rule.watch) 936 audit_remove_watch_rule(&e->rule); 937 938 if (e->rule.tree) 939 audit_remove_tree_rule(&e->rule); 940 941 list_del_rcu(&e->list); 942 list_del(&e->rule.list); 943 call_rcu(&e->rcu, audit_free_rule_rcu); 944 945 #ifdef CONFIG_AUDITSYSCALL 946 if (!dont_count) 947 audit_n_rules--; 948 949 if (!audit_match_signal(entry)) 950 audit_signals--; 951 #endif 952 mutex_unlock(&audit_filter_mutex); 953 954 out: 955 if (watch) 956 audit_put_watch(watch); /* match initial get */ 957 if (tree) 958 audit_put_tree(tree); /* that's the temporary one */ 959 960 return ret; 961 } 962 963 /* List rules using struct audit_rule_data. */ 964 static void audit_list_rules(int pid, int seq, struct sk_buff_head *q) 965 { 966 struct sk_buff *skb; 967 struct audit_krule *r; 968 int i; 969 970 /* This is a blocking read, so use audit_filter_mutex instead of rcu 971 * iterator to sync with list writers. */ 972 for (i=0; i<AUDIT_NR_FILTERS; i++) { 973 list_for_each_entry(r, &audit_rules_list[i], list) { 974 struct audit_rule_data *data; 975 976 data = audit_krule_to_data(r); 977 if (unlikely(!data)) 978 break; 979 skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1, 980 data, sizeof(*data) + data->buflen); 981 if (skb) 982 skb_queue_tail(q, skb); 983 kfree(data); 984 } 985 } 986 skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0); 987 if (skb) 988 skb_queue_tail(q, skb); 989 } 990 991 /* Log rule additions and removals */ 992 static void audit_log_rule_change(char *action, struct audit_krule *rule, int res) 993 { 994 struct audit_buffer *ab; 995 uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(current)); 996 u32 sessionid = audit_get_sessionid(current); 997 998 if (!audit_enabled) 999 return; 1000 1001 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); 1002 if (!ab) 1003 return; 1004 audit_log_format(ab, "auid=%u ses=%u" ,loginuid, sessionid); 1005 audit_log_task_context(ab); 1006 audit_log_format(ab, " op="); 1007 audit_log_string(ab, action); 1008 audit_log_key(ab, rule->filterkey); 1009 audit_log_format(ab, " list=%d res=%d", rule->listnr, res); 1010 audit_log_end(ab); 1011 } 1012 1013 /** 1014 * audit_receive_filter - apply all rules to the specified message type 1015 * @type: audit message type 1016 * @pid: target pid for netlink audit messages 1017 * @seq: netlink audit message sequence (serial) number 1018 * @data: payload data 1019 * @datasz: size of payload data 1020 * @loginuid: loginuid of sender 1021 * @sessionid: sessionid for netlink audit message 1022 * @sid: SE Linux Security ID of sender 1023 */ 1024 int audit_receive_filter(int type, int pid, int seq, void *data, size_t datasz) 1025 { 1026 struct task_struct *tsk; 1027 struct audit_netlink_list *dest; 1028 int err = 0; 1029 struct audit_entry *entry; 1030 1031 switch (type) { 1032 case AUDIT_LIST_RULES: 1033 /* We can't just spew out the rules here because we might fill 1034 * the available socket buffer space and deadlock waiting for 1035 * auditctl to read from it... which isn't ever going to 1036 * happen if we're actually running in the context of auditctl 1037 * trying to _send_ the stuff */ 1038 1039 dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL); 1040 if (!dest) 1041 return -ENOMEM; 1042 dest->pid = pid; 1043 skb_queue_head_init(&dest->q); 1044 1045 mutex_lock(&audit_filter_mutex); 1046 audit_list_rules(pid, seq, &dest->q); 1047 mutex_unlock(&audit_filter_mutex); 1048 1049 tsk = kthread_run(audit_send_list, dest, "audit_send_list"); 1050 if (IS_ERR(tsk)) { 1051 skb_queue_purge(&dest->q); 1052 kfree(dest); 1053 err = PTR_ERR(tsk); 1054 } 1055 break; 1056 case AUDIT_ADD_RULE: 1057 entry = audit_data_to_entry(data, datasz); 1058 if (IS_ERR(entry)) 1059 return PTR_ERR(entry); 1060 1061 err = audit_add_rule(entry); 1062 audit_log_rule_change("add rule", &entry->rule, !err); 1063 if (err) 1064 audit_free_rule(entry); 1065 break; 1066 case AUDIT_DEL_RULE: 1067 entry = audit_data_to_entry(data, datasz); 1068 if (IS_ERR(entry)) 1069 return PTR_ERR(entry); 1070 1071 err = audit_del_rule(entry); 1072 audit_log_rule_change("remove rule", &entry->rule, !err); 1073 audit_free_rule(entry); 1074 break; 1075 default: 1076 return -EINVAL; 1077 } 1078 1079 return err; 1080 } 1081 1082 int audit_comparator(u32 left, u32 op, u32 right) 1083 { 1084 switch (op) { 1085 case Audit_equal: 1086 return (left == right); 1087 case Audit_not_equal: 1088 return (left != right); 1089 case Audit_lt: 1090 return (left < right); 1091 case Audit_le: 1092 return (left <= right); 1093 case Audit_gt: 1094 return (left > right); 1095 case Audit_ge: 1096 return (left >= right); 1097 case Audit_bitmask: 1098 return (left & right); 1099 case Audit_bittest: 1100 return ((left & right) == right); 1101 default: 1102 BUG(); 1103 return 0; 1104 } 1105 } 1106 1107 int audit_uid_comparator(kuid_t left, u32 op, kuid_t right) 1108 { 1109 switch (op) { 1110 case Audit_equal: 1111 return uid_eq(left, right); 1112 case Audit_not_equal: 1113 return !uid_eq(left, right); 1114 case Audit_lt: 1115 return uid_lt(left, right); 1116 case Audit_le: 1117 return uid_lte(left, right); 1118 case Audit_gt: 1119 return uid_gt(left, right); 1120 case Audit_ge: 1121 return uid_gte(left, right); 1122 case Audit_bitmask: 1123 case Audit_bittest: 1124 default: 1125 BUG(); 1126 return 0; 1127 } 1128 } 1129 1130 int audit_gid_comparator(kgid_t left, u32 op, kgid_t right) 1131 { 1132 switch (op) { 1133 case Audit_equal: 1134 return gid_eq(left, right); 1135 case Audit_not_equal: 1136 return !gid_eq(left, right); 1137 case Audit_lt: 1138 return gid_lt(left, right); 1139 case Audit_le: 1140 return gid_lte(left, right); 1141 case Audit_gt: 1142 return gid_gt(left, right); 1143 case Audit_ge: 1144 return gid_gte(left, right); 1145 case Audit_bitmask: 1146 case Audit_bittest: 1147 default: 1148 BUG(); 1149 return 0; 1150 } 1151 } 1152 1153 /** 1154 * parent_len - find the length of the parent portion of a pathname 1155 * @path: pathname of which to determine length 1156 */ 1157 int parent_len(const char *path) 1158 { 1159 int plen; 1160 const char *p; 1161 1162 plen = strlen(path); 1163 1164 if (plen == 0) 1165 return plen; 1166 1167 /* disregard trailing slashes */ 1168 p = path + plen - 1; 1169 while ((*p == '/') && (p > path)) 1170 p--; 1171 1172 /* walk backward until we find the next slash or hit beginning */ 1173 while ((*p != '/') && (p > path)) 1174 p--; 1175 1176 /* did we find a slash? Then increment to include it in path */ 1177 if (*p == '/') 1178 p++; 1179 1180 return p - path; 1181 } 1182 1183 /** 1184 * audit_compare_dname_path - compare given dentry name with last component in 1185 * given path. Return of 0 indicates a match. 1186 * @dname: dentry name that we're comparing 1187 * @path: full pathname that we're comparing 1188 * @parentlen: length of the parent if known. Passing in AUDIT_NAME_FULL 1189 * here indicates that we must compute this value. 1190 */ 1191 int audit_compare_dname_path(const char *dname, const char *path, int parentlen) 1192 { 1193 int dlen, pathlen; 1194 const char *p; 1195 1196 dlen = strlen(dname); 1197 pathlen = strlen(path); 1198 if (pathlen < dlen) 1199 return 1; 1200 1201 parentlen = parentlen == AUDIT_NAME_FULL ? parent_len(path) : parentlen; 1202 if (pathlen - parentlen != dlen) 1203 return 1; 1204 1205 p = path + parentlen; 1206 1207 return strncmp(p, dname, dlen); 1208 } 1209 1210 static int audit_filter_user_rules(struct audit_krule *rule, int type, 1211 enum audit_state *state) 1212 { 1213 int i; 1214 1215 for (i = 0; i < rule->field_count; i++) { 1216 struct audit_field *f = &rule->fields[i]; 1217 int result = 0; 1218 u32 sid; 1219 1220 switch (f->type) { 1221 case AUDIT_PID: 1222 result = audit_comparator(task_pid_vnr(current), f->op, f->val); 1223 break; 1224 case AUDIT_UID: 1225 result = audit_uid_comparator(current_uid(), f->op, f->uid); 1226 break; 1227 case AUDIT_GID: 1228 result = audit_gid_comparator(current_gid(), f->op, f->gid); 1229 break; 1230 case AUDIT_LOGINUID: 1231 result = audit_uid_comparator(audit_get_loginuid(current), 1232 f->op, f->uid); 1233 break; 1234 case AUDIT_LOGINUID_SET: 1235 result = audit_comparator(audit_loginuid_set(current), 1236 f->op, f->val); 1237 break; 1238 case AUDIT_MSGTYPE: 1239 result = audit_comparator(type, f->op, f->val); 1240 break; 1241 case AUDIT_SUBJ_USER: 1242 case AUDIT_SUBJ_ROLE: 1243 case AUDIT_SUBJ_TYPE: 1244 case AUDIT_SUBJ_SEN: 1245 case AUDIT_SUBJ_CLR: 1246 if (f->lsm_rule) { 1247 security_task_getsecid(current, &sid); 1248 result = security_audit_rule_match(sid, 1249 f->type, 1250 f->op, 1251 f->lsm_rule, 1252 NULL); 1253 } 1254 break; 1255 } 1256 1257 if (!result) 1258 return 0; 1259 } 1260 switch (rule->action) { 1261 case AUDIT_NEVER: *state = AUDIT_DISABLED; break; 1262 case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break; 1263 } 1264 return 1; 1265 } 1266 1267 int audit_filter_user(int type) 1268 { 1269 enum audit_state state = AUDIT_DISABLED; 1270 struct audit_entry *e; 1271 int ret = 1; 1272 1273 rcu_read_lock(); 1274 list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) { 1275 if (audit_filter_user_rules(&e->rule, type, &state)) { 1276 if (state == AUDIT_DISABLED) 1277 ret = 0; 1278 break; 1279 } 1280 } 1281 rcu_read_unlock(); 1282 1283 return ret; /* Audit by default */ 1284 } 1285 1286 int audit_filter_type(int type) 1287 { 1288 struct audit_entry *e; 1289 int result = 0; 1290 1291 rcu_read_lock(); 1292 if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE])) 1293 goto unlock_and_return; 1294 1295 list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE], 1296 list) { 1297 int i; 1298 for (i = 0; i < e->rule.field_count; i++) { 1299 struct audit_field *f = &e->rule.fields[i]; 1300 if (f->type == AUDIT_MSGTYPE) { 1301 result = audit_comparator(type, f->op, f->val); 1302 if (!result) 1303 break; 1304 } 1305 } 1306 if (result) 1307 goto unlock_and_return; 1308 } 1309 unlock_and_return: 1310 rcu_read_unlock(); 1311 return result; 1312 } 1313 1314 static int update_lsm_rule(struct audit_krule *r) 1315 { 1316 struct audit_entry *entry = container_of(r, struct audit_entry, rule); 1317 struct audit_entry *nentry; 1318 int err = 0; 1319 1320 if (!security_audit_rule_known(r)) 1321 return 0; 1322 1323 nentry = audit_dupe_rule(r); 1324 if (IS_ERR(nentry)) { 1325 /* save the first error encountered for the 1326 * return value */ 1327 err = PTR_ERR(nentry); 1328 audit_panic("error updating LSM filters"); 1329 if (r->watch) 1330 list_del(&r->rlist); 1331 list_del_rcu(&entry->list); 1332 list_del(&r->list); 1333 } else { 1334 if (r->watch || r->tree) 1335 list_replace_init(&r->rlist, &nentry->rule.rlist); 1336 list_replace_rcu(&entry->list, &nentry->list); 1337 list_replace(&r->list, &nentry->rule.list); 1338 } 1339 call_rcu(&entry->rcu, audit_free_rule_rcu); 1340 1341 return err; 1342 } 1343 1344 /* This function will re-initialize the lsm_rule field of all applicable rules. 1345 * It will traverse the filter lists serarching for rules that contain LSM 1346 * specific filter fields. When such a rule is found, it is copied, the 1347 * LSM field is re-initialized, and the old rule is replaced with the 1348 * updated rule. */ 1349 int audit_update_lsm_rules(void) 1350 { 1351 struct audit_krule *r, *n; 1352 int i, err = 0; 1353 1354 /* audit_filter_mutex synchronizes the writers */ 1355 mutex_lock(&audit_filter_mutex); 1356 1357 for (i = 0; i < AUDIT_NR_FILTERS; i++) { 1358 list_for_each_entry_safe(r, n, &audit_rules_list[i], list) { 1359 int res = update_lsm_rule(r); 1360 if (!err) 1361 err = res; 1362 } 1363 } 1364 mutex_unlock(&audit_filter_mutex); 1365 1366 return err; 1367 } 1368