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/security.h> 31 #include "audit.h" 32 33 /* 34 * Locking model: 35 * 36 * audit_filter_mutex: 37 * Synchronizes writes and blocking reads of audit's filterlist 38 * data. Rcu is used to traverse the filterlist and access 39 * contents of structs audit_entry, audit_watch and opaque 40 * LSM rules during filtering. If modified, these structures 41 * must be copied and replace their counterparts in the filterlist. 42 * An audit_parent struct is not accessed during filtering, so may 43 * be written directly provided audit_filter_mutex is held. 44 */ 45 46 /* Audit filter lists, defined in <linux/audit.h> */ 47 struct list_head audit_filter_list[AUDIT_NR_FILTERS] = { 48 LIST_HEAD_INIT(audit_filter_list[0]), 49 LIST_HEAD_INIT(audit_filter_list[1]), 50 LIST_HEAD_INIT(audit_filter_list[2]), 51 LIST_HEAD_INIT(audit_filter_list[3]), 52 LIST_HEAD_INIT(audit_filter_list[4]), 53 LIST_HEAD_INIT(audit_filter_list[5]), 54 #if AUDIT_NR_FILTERS != 6 55 #error Fix audit_filter_list initialiser 56 #endif 57 }; 58 static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = { 59 LIST_HEAD_INIT(audit_rules_list[0]), 60 LIST_HEAD_INIT(audit_rules_list[1]), 61 LIST_HEAD_INIT(audit_rules_list[2]), 62 LIST_HEAD_INIT(audit_rules_list[3]), 63 LIST_HEAD_INIT(audit_rules_list[4]), 64 LIST_HEAD_INIT(audit_rules_list[5]), 65 }; 66 67 DEFINE_MUTEX(audit_filter_mutex); 68 69 static inline void audit_free_rule(struct audit_entry *e) 70 { 71 int i; 72 struct audit_krule *erule = &e->rule; 73 /* some rules don't have associated watches */ 74 if (erule->watch) 75 audit_put_watch(erule->watch); 76 if (erule->fields) 77 for (i = 0; i < erule->field_count; i++) { 78 struct audit_field *f = &erule->fields[i]; 79 kfree(f->lsm_str); 80 security_audit_rule_free(f->lsm_rule); 81 } 82 kfree(erule->fields); 83 kfree(erule->filterkey); 84 kfree(e); 85 } 86 87 void audit_free_rule_rcu(struct rcu_head *head) 88 { 89 struct audit_entry *e = container_of(head, struct audit_entry, rcu); 90 audit_free_rule(e); 91 } 92 93 /* Initialize an audit filterlist entry. */ 94 static inline struct audit_entry *audit_init_entry(u32 field_count) 95 { 96 struct audit_entry *entry; 97 struct audit_field *fields; 98 99 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 100 if (unlikely(!entry)) 101 return NULL; 102 103 fields = kzalloc(sizeof(*fields) * field_count, GFP_KERNEL); 104 if (unlikely(!fields)) { 105 kfree(entry); 106 return NULL; 107 } 108 entry->rule.fields = fields; 109 110 return entry; 111 } 112 113 /* Unpack a filter field's string representation from user-space 114 * buffer. */ 115 char *audit_unpack_string(void **bufp, size_t *remain, size_t len) 116 { 117 char *str; 118 119 if (!*bufp || (len == 0) || (len > *remain)) 120 return ERR_PTR(-EINVAL); 121 122 /* Of the currently implemented string fields, PATH_MAX 123 * defines the longest valid length. 124 */ 125 if (len > PATH_MAX) 126 return ERR_PTR(-ENAMETOOLONG); 127 128 str = kmalloc(len + 1, GFP_KERNEL); 129 if (unlikely(!str)) 130 return ERR_PTR(-ENOMEM); 131 132 memcpy(str, *bufp, len); 133 str[len] = 0; 134 *bufp += len; 135 *remain -= len; 136 137 return str; 138 } 139 140 /* Translate an inode field to kernel respresentation. */ 141 static inline int audit_to_inode(struct audit_krule *krule, 142 struct audit_field *f) 143 { 144 if (krule->listnr != AUDIT_FILTER_EXIT || 145 krule->watch || krule->inode_f || krule->tree || 146 (f->op != Audit_equal && f->op != Audit_not_equal)) 147 return -EINVAL; 148 149 krule->inode_f = f; 150 return 0; 151 } 152 153 static __u32 *classes[AUDIT_SYSCALL_CLASSES]; 154 155 int __init audit_register_class(int class, unsigned *list) 156 { 157 __u32 *p = kzalloc(AUDIT_BITMASK_SIZE * sizeof(__u32), GFP_KERNEL); 158 if (!p) 159 return -ENOMEM; 160 while (*list != ~0U) { 161 unsigned n = *list++; 162 if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) { 163 kfree(p); 164 return -EINVAL; 165 } 166 p[AUDIT_WORD(n)] |= AUDIT_BIT(n); 167 } 168 if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) { 169 kfree(p); 170 return -EINVAL; 171 } 172 classes[class] = p; 173 return 0; 174 } 175 176 int audit_match_class(int class, unsigned syscall) 177 { 178 if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32)) 179 return 0; 180 if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class])) 181 return 0; 182 return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall); 183 } 184 185 #ifdef CONFIG_AUDITSYSCALL 186 static inline int audit_match_class_bits(int class, u32 *mask) 187 { 188 int i; 189 190 if (classes[class]) { 191 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) 192 if (mask[i] & classes[class][i]) 193 return 0; 194 } 195 return 1; 196 } 197 198 static int audit_match_signal(struct audit_entry *entry) 199 { 200 struct audit_field *arch = entry->rule.arch_f; 201 202 if (!arch) { 203 /* When arch is unspecified, we must check both masks on biarch 204 * as syscall number alone is ambiguous. */ 205 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL, 206 entry->rule.mask) && 207 audit_match_class_bits(AUDIT_CLASS_SIGNAL_32, 208 entry->rule.mask)); 209 } 210 211 switch(audit_classify_arch(arch->val)) { 212 case 0: /* native */ 213 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL, 214 entry->rule.mask)); 215 case 1: /* 32bit on biarch */ 216 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32, 217 entry->rule.mask)); 218 default: 219 return 1; 220 } 221 } 222 #endif 223 224 /* Common user-space to kernel rule translation. */ 225 static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule) 226 { 227 unsigned listnr; 228 struct audit_entry *entry; 229 int i, err; 230 231 err = -EINVAL; 232 listnr = rule->flags & ~AUDIT_FILTER_PREPEND; 233 switch(listnr) { 234 default: 235 goto exit_err; 236 case AUDIT_FILTER_USER: 237 case AUDIT_FILTER_TYPE: 238 #ifdef CONFIG_AUDITSYSCALL 239 case AUDIT_FILTER_ENTRY: 240 case AUDIT_FILTER_EXIT: 241 case AUDIT_FILTER_TASK: 242 #endif 243 ; 244 } 245 if (unlikely(rule->action == AUDIT_POSSIBLE)) { 246 printk(KERN_ERR "AUDIT_POSSIBLE is deprecated\n"); 247 goto exit_err; 248 } 249 if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS) 250 goto exit_err; 251 if (rule->field_count > AUDIT_MAX_FIELDS) 252 goto exit_err; 253 254 err = -ENOMEM; 255 entry = audit_init_entry(rule->field_count); 256 if (!entry) 257 goto exit_err; 258 259 entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND; 260 entry->rule.listnr = listnr; 261 entry->rule.action = rule->action; 262 entry->rule.field_count = rule->field_count; 263 264 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) 265 entry->rule.mask[i] = rule->mask[i]; 266 267 for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) { 268 int bit = AUDIT_BITMASK_SIZE * 32 - i - 1; 269 __u32 *p = &entry->rule.mask[AUDIT_WORD(bit)]; 270 __u32 *class; 271 272 if (!(*p & AUDIT_BIT(bit))) 273 continue; 274 *p &= ~AUDIT_BIT(bit); 275 class = classes[i]; 276 if (class) { 277 int j; 278 for (j = 0; j < AUDIT_BITMASK_SIZE; j++) 279 entry->rule.mask[j] |= class[j]; 280 } 281 } 282 283 return entry; 284 285 exit_err: 286 return ERR_PTR(err); 287 } 288 289 static u32 audit_ops[] = 290 { 291 [Audit_equal] = AUDIT_EQUAL, 292 [Audit_not_equal] = AUDIT_NOT_EQUAL, 293 [Audit_bitmask] = AUDIT_BIT_MASK, 294 [Audit_bittest] = AUDIT_BIT_TEST, 295 [Audit_lt] = AUDIT_LESS_THAN, 296 [Audit_gt] = AUDIT_GREATER_THAN, 297 [Audit_le] = AUDIT_LESS_THAN_OR_EQUAL, 298 [Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL, 299 }; 300 301 static u32 audit_to_op(u32 op) 302 { 303 u32 n; 304 for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++) 305 ; 306 return n; 307 } 308 309 310 /* Translate struct audit_rule to kernel's rule respresentation. 311 * Exists for backward compatibility with userspace. */ 312 static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule) 313 { 314 struct audit_entry *entry; 315 int err = 0; 316 int i; 317 318 entry = audit_to_entry_common(rule); 319 if (IS_ERR(entry)) 320 goto exit_nofree; 321 322 for (i = 0; i < rule->field_count; i++) { 323 struct audit_field *f = &entry->rule.fields[i]; 324 u32 n; 325 326 n = rule->fields[i] & (AUDIT_NEGATE|AUDIT_OPERATORS); 327 328 /* Support for legacy operators where 329 * AUDIT_NEGATE bit signifies != and otherwise assumes == */ 330 if (n & AUDIT_NEGATE) 331 f->op = Audit_not_equal; 332 else if (!n) 333 f->op = Audit_equal; 334 else 335 f->op = audit_to_op(n); 336 337 entry->rule.vers_ops = (n & AUDIT_OPERATORS) ? 2 : 1; 338 339 f->type = rule->fields[i] & ~(AUDIT_NEGATE|AUDIT_OPERATORS); 340 f->val = rule->values[i]; 341 342 err = -EINVAL; 343 if (f->op == Audit_bad) 344 goto exit_free; 345 346 switch(f->type) { 347 default: 348 goto exit_free; 349 case AUDIT_PID: 350 case AUDIT_UID: 351 case AUDIT_EUID: 352 case AUDIT_SUID: 353 case AUDIT_FSUID: 354 case AUDIT_GID: 355 case AUDIT_EGID: 356 case AUDIT_SGID: 357 case AUDIT_FSGID: 358 case AUDIT_LOGINUID: 359 case AUDIT_PERS: 360 case AUDIT_MSGTYPE: 361 case AUDIT_PPID: 362 case AUDIT_DEVMAJOR: 363 case AUDIT_DEVMINOR: 364 case AUDIT_EXIT: 365 case AUDIT_SUCCESS: 366 /* bit ops are only useful on syscall args */ 367 if (f->op == Audit_bitmask || f->op == Audit_bittest) 368 goto exit_free; 369 break; 370 case AUDIT_ARG0: 371 case AUDIT_ARG1: 372 case AUDIT_ARG2: 373 case AUDIT_ARG3: 374 break; 375 /* arch is only allowed to be = or != */ 376 case AUDIT_ARCH: 377 if (f->op != Audit_not_equal && f->op != Audit_equal) 378 goto exit_free; 379 entry->rule.arch_f = f; 380 break; 381 case AUDIT_PERM: 382 if (f->val & ~15) 383 goto exit_free; 384 break; 385 case AUDIT_FILETYPE: 386 if ((f->val & ~S_IFMT) > S_IFMT) 387 goto exit_free; 388 break; 389 case AUDIT_INODE: 390 err = audit_to_inode(&entry->rule, f); 391 if (err) 392 goto exit_free; 393 break; 394 } 395 } 396 397 if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal) 398 entry->rule.inode_f = NULL; 399 400 exit_nofree: 401 return entry; 402 403 exit_free: 404 audit_free_rule(entry); 405 return ERR_PTR(err); 406 } 407 408 /* Translate struct audit_rule_data to kernel's rule respresentation. */ 409 static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data, 410 size_t datasz) 411 { 412 int err = 0; 413 struct audit_entry *entry; 414 void *bufp; 415 size_t remain = datasz - sizeof(struct audit_rule_data); 416 int i; 417 char *str; 418 419 entry = audit_to_entry_common((struct audit_rule *)data); 420 if (IS_ERR(entry)) 421 goto exit_nofree; 422 423 bufp = data->buf; 424 entry->rule.vers_ops = 2; 425 for (i = 0; i < data->field_count; i++) { 426 struct audit_field *f = &entry->rule.fields[i]; 427 428 err = -EINVAL; 429 430 f->op = audit_to_op(data->fieldflags[i]); 431 if (f->op == Audit_bad) 432 goto exit_free; 433 434 f->type = data->fields[i]; 435 f->val = data->values[i]; 436 f->lsm_str = NULL; 437 f->lsm_rule = NULL; 438 switch(f->type) { 439 case AUDIT_PID: 440 case AUDIT_UID: 441 case AUDIT_EUID: 442 case AUDIT_SUID: 443 case AUDIT_FSUID: 444 case AUDIT_GID: 445 case AUDIT_EGID: 446 case AUDIT_SGID: 447 case AUDIT_FSGID: 448 case AUDIT_LOGINUID: 449 case AUDIT_PERS: 450 case AUDIT_MSGTYPE: 451 case AUDIT_PPID: 452 case AUDIT_DEVMAJOR: 453 case AUDIT_DEVMINOR: 454 case AUDIT_EXIT: 455 case AUDIT_SUCCESS: 456 case AUDIT_ARG0: 457 case AUDIT_ARG1: 458 case AUDIT_ARG2: 459 case AUDIT_ARG3: 460 break; 461 case AUDIT_ARCH: 462 entry->rule.arch_f = f; 463 break; 464 case AUDIT_SUBJ_USER: 465 case AUDIT_SUBJ_ROLE: 466 case AUDIT_SUBJ_TYPE: 467 case AUDIT_SUBJ_SEN: 468 case AUDIT_SUBJ_CLR: 469 case AUDIT_OBJ_USER: 470 case AUDIT_OBJ_ROLE: 471 case AUDIT_OBJ_TYPE: 472 case AUDIT_OBJ_LEV_LOW: 473 case AUDIT_OBJ_LEV_HIGH: 474 str = audit_unpack_string(&bufp, &remain, f->val); 475 if (IS_ERR(str)) 476 goto exit_free; 477 entry->rule.buflen += f->val; 478 479 err = security_audit_rule_init(f->type, f->op, str, 480 (void **)&f->lsm_rule); 481 /* Keep currently invalid fields around in case they 482 * become valid after a policy reload. */ 483 if (err == -EINVAL) { 484 printk(KERN_WARNING "audit rule for LSM " 485 "\'%s\' is invalid\n", str); 486 err = 0; 487 } 488 if (err) { 489 kfree(str); 490 goto exit_free; 491 } else 492 f->lsm_str = str; 493 break; 494 case AUDIT_WATCH: 495 str = audit_unpack_string(&bufp, &remain, f->val); 496 if (IS_ERR(str)) 497 goto exit_free; 498 entry->rule.buflen += f->val; 499 500 err = audit_to_watch(&entry->rule, str, f->val, f->op); 501 if (err) { 502 kfree(str); 503 goto exit_free; 504 } 505 break; 506 case AUDIT_DIR: 507 str = audit_unpack_string(&bufp, &remain, f->val); 508 if (IS_ERR(str)) 509 goto exit_free; 510 entry->rule.buflen += f->val; 511 512 err = audit_make_tree(&entry->rule, str, f->op); 513 kfree(str); 514 if (err) 515 goto exit_free; 516 break; 517 case AUDIT_INODE: 518 err = audit_to_inode(&entry->rule, f); 519 if (err) 520 goto exit_free; 521 break; 522 case AUDIT_FILTERKEY: 523 err = -EINVAL; 524 if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN) 525 goto exit_free; 526 str = audit_unpack_string(&bufp, &remain, f->val); 527 if (IS_ERR(str)) 528 goto exit_free; 529 entry->rule.buflen += f->val; 530 entry->rule.filterkey = str; 531 break; 532 case AUDIT_PERM: 533 if (f->val & ~15) 534 goto exit_free; 535 break; 536 case AUDIT_FILETYPE: 537 if ((f->val & ~S_IFMT) > S_IFMT) 538 goto exit_free; 539 break; 540 default: 541 goto exit_free; 542 } 543 } 544 545 if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal) 546 entry->rule.inode_f = NULL; 547 548 exit_nofree: 549 return entry; 550 551 exit_free: 552 audit_free_rule(entry); 553 return ERR_PTR(err); 554 } 555 556 /* Pack a filter field's string representation into data block. */ 557 static inline size_t audit_pack_string(void **bufp, const char *str) 558 { 559 size_t len = strlen(str); 560 561 memcpy(*bufp, str, len); 562 *bufp += len; 563 564 return len; 565 } 566 567 /* Translate kernel rule respresentation to struct audit_rule. 568 * Exists for backward compatibility with userspace. */ 569 static struct audit_rule *audit_krule_to_rule(struct audit_krule *krule) 570 { 571 struct audit_rule *rule; 572 int i; 573 574 rule = kzalloc(sizeof(*rule), GFP_KERNEL); 575 if (unlikely(!rule)) 576 return NULL; 577 578 rule->flags = krule->flags | krule->listnr; 579 rule->action = krule->action; 580 rule->field_count = krule->field_count; 581 for (i = 0; i < rule->field_count; i++) { 582 rule->values[i] = krule->fields[i].val; 583 rule->fields[i] = krule->fields[i].type; 584 585 if (krule->vers_ops == 1) { 586 if (krule->fields[i].op == Audit_not_equal) 587 rule->fields[i] |= AUDIT_NEGATE; 588 } else { 589 rule->fields[i] |= audit_ops[krule->fields[i].op]; 590 } 591 } 592 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i]; 593 594 return rule; 595 } 596 597 /* Translate kernel rule respresentation to struct audit_rule_data. */ 598 static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule) 599 { 600 struct audit_rule_data *data; 601 void *bufp; 602 int i; 603 604 data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL); 605 if (unlikely(!data)) 606 return NULL; 607 memset(data, 0, sizeof(*data)); 608 609 data->flags = krule->flags | krule->listnr; 610 data->action = krule->action; 611 data->field_count = krule->field_count; 612 bufp = data->buf; 613 for (i = 0; i < data->field_count; i++) { 614 struct audit_field *f = &krule->fields[i]; 615 616 data->fields[i] = f->type; 617 data->fieldflags[i] = audit_ops[f->op]; 618 switch(f->type) { 619 case AUDIT_SUBJ_USER: 620 case AUDIT_SUBJ_ROLE: 621 case AUDIT_SUBJ_TYPE: 622 case AUDIT_SUBJ_SEN: 623 case AUDIT_SUBJ_CLR: 624 case AUDIT_OBJ_USER: 625 case AUDIT_OBJ_ROLE: 626 case AUDIT_OBJ_TYPE: 627 case AUDIT_OBJ_LEV_LOW: 628 case AUDIT_OBJ_LEV_HIGH: 629 data->buflen += data->values[i] = 630 audit_pack_string(&bufp, f->lsm_str); 631 break; 632 case AUDIT_WATCH: 633 data->buflen += data->values[i] = 634 audit_pack_string(&bufp, 635 audit_watch_path(krule->watch)); 636 break; 637 case AUDIT_DIR: 638 data->buflen += data->values[i] = 639 audit_pack_string(&bufp, 640 audit_tree_path(krule->tree)); 641 break; 642 case AUDIT_FILTERKEY: 643 data->buflen += data->values[i] = 644 audit_pack_string(&bufp, krule->filterkey); 645 break; 646 default: 647 data->values[i] = f->val; 648 } 649 } 650 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i]; 651 652 return data; 653 } 654 655 /* Compare two rules in kernel format. Considered success if rules 656 * don't match. */ 657 static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b) 658 { 659 int i; 660 661 if (a->flags != b->flags || 662 a->listnr != b->listnr || 663 a->action != b->action || 664 a->field_count != b->field_count) 665 return 1; 666 667 for (i = 0; i < a->field_count; i++) { 668 if (a->fields[i].type != b->fields[i].type || 669 a->fields[i].op != b->fields[i].op) 670 return 1; 671 672 switch(a->fields[i].type) { 673 case AUDIT_SUBJ_USER: 674 case AUDIT_SUBJ_ROLE: 675 case AUDIT_SUBJ_TYPE: 676 case AUDIT_SUBJ_SEN: 677 case AUDIT_SUBJ_CLR: 678 case AUDIT_OBJ_USER: 679 case AUDIT_OBJ_ROLE: 680 case AUDIT_OBJ_TYPE: 681 case AUDIT_OBJ_LEV_LOW: 682 case AUDIT_OBJ_LEV_HIGH: 683 if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str)) 684 return 1; 685 break; 686 case AUDIT_WATCH: 687 if (strcmp(audit_watch_path(a->watch), 688 audit_watch_path(b->watch))) 689 return 1; 690 break; 691 case AUDIT_DIR: 692 if (strcmp(audit_tree_path(a->tree), 693 audit_tree_path(b->tree))) 694 return 1; 695 break; 696 case AUDIT_FILTERKEY: 697 /* both filterkeys exist based on above type compare */ 698 if (strcmp(a->filterkey, b->filterkey)) 699 return 1; 700 break; 701 default: 702 if (a->fields[i].val != b->fields[i].val) 703 return 1; 704 } 705 } 706 707 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) 708 if (a->mask[i] != b->mask[i]) 709 return 1; 710 711 return 0; 712 } 713 714 /* Duplicate LSM field information. The lsm_rule is opaque, so must be 715 * re-initialized. */ 716 static inline int audit_dupe_lsm_field(struct audit_field *df, 717 struct audit_field *sf) 718 { 719 int ret = 0; 720 char *lsm_str; 721 722 /* our own copy of lsm_str */ 723 lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL); 724 if (unlikely(!lsm_str)) 725 return -ENOMEM; 726 df->lsm_str = lsm_str; 727 728 /* our own (refreshed) copy of lsm_rule */ 729 ret = security_audit_rule_init(df->type, df->op, df->lsm_str, 730 (void **)&df->lsm_rule); 731 /* Keep currently invalid fields around in case they 732 * become valid after a policy reload. */ 733 if (ret == -EINVAL) { 734 printk(KERN_WARNING "audit rule for LSM \'%s\' is " 735 "invalid\n", df->lsm_str); 736 ret = 0; 737 } 738 739 return ret; 740 } 741 742 /* Duplicate an audit rule. This will be a deep copy with the exception 743 * of the watch - that pointer is carried over. The LSM specific fields 744 * will be updated in the copy. The point is to be able to replace the old 745 * rule with the new rule in the filterlist, then free the old rule. 746 * The rlist element is undefined; list manipulations are handled apart from 747 * the initial copy. */ 748 struct audit_entry *audit_dupe_rule(struct audit_krule *old, 749 struct audit_watch *watch) 750 { 751 u32 fcount = old->field_count; 752 struct audit_entry *entry; 753 struct audit_krule *new; 754 char *fk; 755 int i, err = 0; 756 757 entry = audit_init_entry(fcount); 758 if (unlikely(!entry)) 759 return ERR_PTR(-ENOMEM); 760 761 new = &entry->rule; 762 new->vers_ops = old->vers_ops; 763 new->flags = old->flags; 764 new->listnr = old->listnr; 765 new->action = old->action; 766 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) 767 new->mask[i] = old->mask[i]; 768 new->prio = old->prio; 769 new->buflen = old->buflen; 770 new->inode_f = old->inode_f; 771 new->watch = NULL; 772 new->field_count = old->field_count; 773 /* 774 * note that we are OK with not refcounting here; audit_match_tree() 775 * never dereferences tree and we can't get false positives there 776 * since we'd have to have rule gone from the list *and* removed 777 * before the chunks found by lookup had been allocated, i.e. before 778 * the beginning of list scan. 779 */ 780 new->tree = old->tree; 781 memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount); 782 783 /* deep copy this information, updating the lsm_rule fields, because 784 * the originals will all be freed when the old rule is freed. */ 785 for (i = 0; i < fcount; i++) { 786 switch (new->fields[i].type) { 787 case AUDIT_SUBJ_USER: 788 case AUDIT_SUBJ_ROLE: 789 case AUDIT_SUBJ_TYPE: 790 case AUDIT_SUBJ_SEN: 791 case AUDIT_SUBJ_CLR: 792 case AUDIT_OBJ_USER: 793 case AUDIT_OBJ_ROLE: 794 case AUDIT_OBJ_TYPE: 795 case AUDIT_OBJ_LEV_LOW: 796 case AUDIT_OBJ_LEV_HIGH: 797 err = audit_dupe_lsm_field(&new->fields[i], 798 &old->fields[i]); 799 break; 800 case AUDIT_FILTERKEY: 801 fk = kstrdup(old->filterkey, GFP_KERNEL); 802 if (unlikely(!fk)) 803 err = -ENOMEM; 804 else 805 new->filterkey = fk; 806 } 807 if (err) { 808 audit_free_rule(entry); 809 return ERR_PTR(err); 810 } 811 } 812 813 if (watch) { 814 audit_get_watch(watch); 815 new->watch = watch; 816 } 817 818 return entry; 819 } 820 821 /* Find an existing audit rule. 822 * Caller must hold audit_filter_mutex to prevent stale rule data. */ 823 static struct audit_entry *audit_find_rule(struct audit_entry *entry, 824 struct list_head **p) 825 { 826 struct audit_entry *e, *found = NULL; 827 struct list_head *list; 828 int h; 829 830 if (entry->rule.inode_f) { 831 h = audit_hash_ino(entry->rule.inode_f->val); 832 *p = list = &audit_inode_hash[h]; 833 } else if (entry->rule.watch) { 834 /* we don't know the inode number, so must walk entire hash */ 835 for (h = 0; h < AUDIT_INODE_BUCKETS; h++) { 836 list = &audit_inode_hash[h]; 837 list_for_each_entry(e, list, list) 838 if (!audit_compare_rule(&entry->rule, &e->rule)) { 839 found = e; 840 goto out; 841 } 842 } 843 goto out; 844 } else { 845 *p = list = &audit_filter_list[entry->rule.listnr]; 846 } 847 848 list_for_each_entry(e, list, list) 849 if (!audit_compare_rule(&entry->rule, &e->rule)) { 850 found = e; 851 goto out; 852 } 853 854 out: 855 return found; 856 } 857 858 static u64 prio_low = ~0ULL/2; 859 static u64 prio_high = ~0ULL/2 - 1; 860 861 /* Add rule to given filterlist if not a duplicate. */ 862 static inline int audit_add_rule(struct audit_entry *entry) 863 { 864 struct audit_entry *e; 865 struct audit_watch *watch = entry->rule.watch; 866 struct audit_tree *tree = entry->rule.tree; 867 struct list_head *list; 868 int h, err; 869 #ifdef CONFIG_AUDITSYSCALL 870 int dont_count = 0; 871 872 /* If either of these, don't count towards total */ 873 if (entry->rule.listnr == AUDIT_FILTER_USER || 874 entry->rule.listnr == AUDIT_FILTER_TYPE) 875 dont_count = 1; 876 #endif 877 878 mutex_lock(&audit_filter_mutex); 879 e = audit_find_rule(entry, &list); 880 if (e) { 881 mutex_unlock(&audit_filter_mutex); 882 err = -EEXIST; 883 /* normally audit_add_tree_rule() will free it on failure */ 884 if (tree) 885 audit_put_tree(tree); 886 goto error; 887 } 888 889 if (watch) { 890 /* audit_filter_mutex is dropped and re-taken during this call */ 891 err = audit_add_watch(&entry->rule); 892 if (err) { 893 mutex_unlock(&audit_filter_mutex); 894 goto error; 895 } 896 /* entry->rule.watch may have changed during audit_add_watch() */ 897 watch = entry->rule.watch; 898 h = audit_hash_ino((u32)audit_watch_inode(watch)); 899 list = &audit_inode_hash[h]; 900 } 901 if (tree) { 902 err = audit_add_tree_rule(&entry->rule); 903 if (err) { 904 mutex_unlock(&audit_filter_mutex); 905 goto error; 906 } 907 } 908 909 entry->rule.prio = ~0ULL; 910 if (entry->rule.listnr == AUDIT_FILTER_EXIT) { 911 if (entry->rule.flags & AUDIT_FILTER_PREPEND) 912 entry->rule.prio = ++prio_high; 913 else 914 entry->rule.prio = --prio_low; 915 } 916 917 if (entry->rule.flags & AUDIT_FILTER_PREPEND) { 918 list_add(&entry->rule.list, 919 &audit_rules_list[entry->rule.listnr]); 920 list_add_rcu(&entry->list, list); 921 entry->rule.flags &= ~AUDIT_FILTER_PREPEND; 922 } else { 923 list_add_tail(&entry->rule.list, 924 &audit_rules_list[entry->rule.listnr]); 925 list_add_tail_rcu(&entry->list, list); 926 } 927 #ifdef CONFIG_AUDITSYSCALL 928 if (!dont_count) 929 audit_n_rules++; 930 931 if (!audit_match_signal(entry)) 932 audit_signals++; 933 #endif 934 mutex_unlock(&audit_filter_mutex); 935 936 return 0; 937 938 error: 939 if (watch) 940 audit_put_watch(watch); /* tmp watch, matches initial get */ 941 return err; 942 } 943 944 /* Remove an existing rule from filterlist. */ 945 static inline int audit_del_rule(struct audit_entry *entry) 946 { 947 struct audit_entry *e; 948 struct audit_watch *watch = entry->rule.watch; 949 struct audit_tree *tree = entry->rule.tree; 950 struct list_head *list; 951 LIST_HEAD(inotify_list); 952 int ret = 0; 953 #ifdef CONFIG_AUDITSYSCALL 954 int dont_count = 0; 955 956 /* If either of these, don't count towards total */ 957 if (entry->rule.listnr == AUDIT_FILTER_USER || 958 entry->rule.listnr == AUDIT_FILTER_TYPE) 959 dont_count = 1; 960 #endif 961 962 mutex_lock(&audit_filter_mutex); 963 e = audit_find_rule(entry, &list); 964 if (!e) { 965 mutex_unlock(&audit_filter_mutex); 966 ret = -ENOENT; 967 goto out; 968 } 969 970 if (e->rule.watch) 971 audit_remove_watch_rule(&e->rule, &inotify_list); 972 973 if (e->rule.tree) 974 audit_remove_tree_rule(&e->rule); 975 976 list_del_rcu(&e->list); 977 list_del(&e->rule.list); 978 call_rcu(&e->rcu, audit_free_rule_rcu); 979 980 #ifdef CONFIG_AUDITSYSCALL 981 if (!dont_count) 982 audit_n_rules--; 983 984 if (!audit_match_signal(entry)) 985 audit_signals--; 986 #endif 987 mutex_unlock(&audit_filter_mutex); 988 989 if (!list_empty(&inotify_list)) 990 audit_inotify_unregister(&inotify_list); 991 992 out: 993 if (watch) 994 audit_put_watch(watch); /* match initial get */ 995 if (tree) 996 audit_put_tree(tree); /* that's the temporary one */ 997 998 return ret; 999 } 1000 1001 /* List rules using struct audit_rule. Exists for backward 1002 * compatibility with userspace. */ 1003 static void audit_list(int pid, int seq, struct sk_buff_head *q) 1004 { 1005 struct sk_buff *skb; 1006 struct audit_krule *r; 1007 int i; 1008 1009 /* This is a blocking read, so use audit_filter_mutex instead of rcu 1010 * iterator to sync with list writers. */ 1011 for (i=0; i<AUDIT_NR_FILTERS; i++) { 1012 list_for_each_entry(r, &audit_rules_list[i], list) { 1013 struct audit_rule *rule; 1014 1015 rule = audit_krule_to_rule(r); 1016 if (unlikely(!rule)) 1017 break; 1018 skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1, 1019 rule, sizeof(*rule)); 1020 if (skb) 1021 skb_queue_tail(q, skb); 1022 kfree(rule); 1023 } 1024 } 1025 skb = audit_make_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0); 1026 if (skb) 1027 skb_queue_tail(q, skb); 1028 } 1029 1030 /* List rules using struct audit_rule_data. */ 1031 static void audit_list_rules(int pid, int seq, struct sk_buff_head *q) 1032 { 1033 struct sk_buff *skb; 1034 struct audit_krule *r; 1035 int i; 1036 1037 /* This is a blocking read, so use audit_filter_mutex instead of rcu 1038 * iterator to sync with list writers. */ 1039 for (i=0; i<AUDIT_NR_FILTERS; i++) { 1040 list_for_each_entry(r, &audit_rules_list[i], list) { 1041 struct audit_rule_data *data; 1042 1043 data = audit_krule_to_data(r); 1044 if (unlikely(!data)) 1045 break; 1046 skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1, 1047 data, sizeof(*data) + data->buflen); 1048 if (skb) 1049 skb_queue_tail(q, skb); 1050 kfree(data); 1051 } 1052 } 1053 skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0); 1054 if (skb) 1055 skb_queue_tail(q, skb); 1056 } 1057 1058 /* Log rule additions and removals */ 1059 static void audit_log_rule_change(uid_t loginuid, u32 sessionid, u32 sid, 1060 char *action, struct audit_krule *rule, 1061 int res) 1062 { 1063 struct audit_buffer *ab; 1064 1065 if (!audit_enabled) 1066 return; 1067 1068 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); 1069 if (!ab) 1070 return; 1071 audit_log_format(ab, "auid=%u ses=%u", loginuid, sessionid); 1072 if (sid) { 1073 char *ctx = NULL; 1074 u32 len; 1075 if (security_secid_to_secctx(sid, &ctx, &len)) 1076 audit_log_format(ab, " ssid=%u", sid); 1077 else { 1078 audit_log_format(ab, " subj=%s", ctx); 1079 security_release_secctx(ctx, len); 1080 } 1081 } 1082 audit_log_format(ab, " op="); 1083 audit_log_string(ab, action); 1084 audit_log_key(ab, rule->filterkey); 1085 audit_log_format(ab, " list=%d res=%d", rule->listnr, res); 1086 audit_log_end(ab); 1087 } 1088 1089 /** 1090 * audit_receive_filter - apply all rules to the specified message type 1091 * @type: audit message type 1092 * @pid: target pid for netlink audit messages 1093 * @uid: target uid for netlink audit messages 1094 * @seq: netlink audit message sequence (serial) number 1095 * @data: payload data 1096 * @datasz: size of payload data 1097 * @loginuid: loginuid of sender 1098 * @sessionid: sessionid for netlink audit message 1099 * @sid: SE Linux Security ID of sender 1100 */ 1101 int audit_receive_filter(int type, int pid, int uid, int seq, void *data, 1102 size_t datasz, uid_t loginuid, u32 sessionid, u32 sid) 1103 { 1104 struct task_struct *tsk; 1105 struct audit_netlink_list *dest; 1106 int err = 0; 1107 struct audit_entry *entry; 1108 1109 switch (type) { 1110 case AUDIT_LIST: 1111 case AUDIT_LIST_RULES: 1112 /* We can't just spew out the rules here because we might fill 1113 * the available socket buffer space and deadlock waiting for 1114 * auditctl to read from it... which isn't ever going to 1115 * happen if we're actually running in the context of auditctl 1116 * trying to _send_ the stuff */ 1117 1118 dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL); 1119 if (!dest) 1120 return -ENOMEM; 1121 dest->pid = pid; 1122 skb_queue_head_init(&dest->q); 1123 1124 mutex_lock(&audit_filter_mutex); 1125 if (type == AUDIT_LIST) 1126 audit_list(pid, seq, &dest->q); 1127 else 1128 audit_list_rules(pid, seq, &dest->q); 1129 mutex_unlock(&audit_filter_mutex); 1130 1131 tsk = kthread_run(audit_send_list, dest, "audit_send_list"); 1132 if (IS_ERR(tsk)) { 1133 skb_queue_purge(&dest->q); 1134 kfree(dest); 1135 err = PTR_ERR(tsk); 1136 } 1137 break; 1138 case AUDIT_ADD: 1139 case AUDIT_ADD_RULE: 1140 if (type == AUDIT_ADD) 1141 entry = audit_rule_to_entry(data); 1142 else 1143 entry = audit_data_to_entry(data, datasz); 1144 if (IS_ERR(entry)) 1145 return PTR_ERR(entry); 1146 1147 err = audit_add_rule(entry); 1148 audit_log_rule_change(loginuid, sessionid, sid, "add rule", 1149 &entry->rule, !err); 1150 1151 if (err) 1152 audit_free_rule(entry); 1153 break; 1154 case AUDIT_DEL: 1155 case AUDIT_DEL_RULE: 1156 if (type == AUDIT_DEL) 1157 entry = audit_rule_to_entry(data); 1158 else 1159 entry = audit_data_to_entry(data, datasz); 1160 if (IS_ERR(entry)) 1161 return PTR_ERR(entry); 1162 1163 err = audit_del_rule(entry); 1164 audit_log_rule_change(loginuid, sessionid, sid, "remove rule", 1165 &entry->rule, !err); 1166 1167 audit_free_rule(entry); 1168 break; 1169 default: 1170 return -EINVAL; 1171 } 1172 1173 return err; 1174 } 1175 1176 int audit_comparator(u32 left, u32 op, u32 right) 1177 { 1178 switch (op) { 1179 case Audit_equal: 1180 return (left == right); 1181 case Audit_not_equal: 1182 return (left != right); 1183 case Audit_lt: 1184 return (left < right); 1185 case Audit_le: 1186 return (left <= right); 1187 case Audit_gt: 1188 return (left > right); 1189 case Audit_ge: 1190 return (left >= right); 1191 case Audit_bitmask: 1192 return (left & right); 1193 case Audit_bittest: 1194 return ((left & right) == right); 1195 default: 1196 BUG(); 1197 return 0; 1198 } 1199 } 1200 1201 /* Compare given dentry name with last component in given path, 1202 * return of 0 indicates a match. */ 1203 int audit_compare_dname_path(const char *dname, const char *path, 1204 int *dirlen) 1205 { 1206 int dlen, plen; 1207 const char *p; 1208 1209 if (!dname || !path) 1210 return 1; 1211 1212 dlen = strlen(dname); 1213 plen = strlen(path); 1214 if (plen < dlen) 1215 return 1; 1216 1217 /* disregard trailing slashes */ 1218 p = path + plen - 1; 1219 while ((*p == '/') && (p > path)) 1220 p--; 1221 1222 /* find last path component */ 1223 p = p - dlen + 1; 1224 if (p < path) 1225 return 1; 1226 else if (p > path) { 1227 if (*--p != '/') 1228 return 1; 1229 else 1230 p++; 1231 } 1232 1233 /* return length of path's directory component */ 1234 if (dirlen) 1235 *dirlen = p - path; 1236 return strncmp(p, dname, dlen); 1237 } 1238 1239 static int audit_filter_user_rules(struct netlink_skb_parms *cb, 1240 struct audit_krule *rule, 1241 enum audit_state *state) 1242 { 1243 int i; 1244 1245 for (i = 0; i < rule->field_count; i++) { 1246 struct audit_field *f = &rule->fields[i]; 1247 int result = 0; 1248 1249 switch (f->type) { 1250 case AUDIT_PID: 1251 result = audit_comparator(cb->creds.pid, f->op, f->val); 1252 break; 1253 case AUDIT_UID: 1254 result = audit_comparator(cb->creds.uid, f->op, f->val); 1255 break; 1256 case AUDIT_GID: 1257 result = audit_comparator(cb->creds.gid, f->op, f->val); 1258 break; 1259 case AUDIT_LOGINUID: 1260 result = audit_comparator(cb->loginuid, f->op, f->val); 1261 break; 1262 } 1263 1264 if (!result) 1265 return 0; 1266 } 1267 switch (rule->action) { 1268 case AUDIT_NEVER: *state = AUDIT_DISABLED; break; 1269 case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break; 1270 } 1271 return 1; 1272 } 1273 1274 int audit_filter_user(struct netlink_skb_parms *cb) 1275 { 1276 enum audit_state state = AUDIT_DISABLED; 1277 struct audit_entry *e; 1278 int ret = 1; 1279 1280 rcu_read_lock(); 1281 list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) { 1282 if (audit_filter_user_rules(cb, &e->rule, &state)) { 1283 if (state == AUDIT_DISABLED) 1284 ret = 0; 1285 break; 1286 } 1287 } 1288 rcu_read_unlock(); 1289 1290 return ret; /* Audit by default */ 1291 } 1292 1293 int audit_filter_type(int type) 1294 { 1295 struct audit_entry *e; 1296 int result = 0; 1297 1298 rcu_read_lock(); 1299 if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE])) 1300 goto unlock_and_return; 1301 1302 list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE], 1303 list) { 1304 int i; 1305 for (i = 0; i < e->rule.field_count; i++) { 1306 struct audit_field *f = &e->rule.fields[i]; 1307 if (f->type == AUDIT_MSGTYPE) { 1308 result = audit_comparator(type, f->op, f->val); 1309 if (!result) 1310 break; 1311 } 1312 } 1313 if (result) 1314 goto unlock_and_return; 1315 } 1316 unlock_and_return: 1317 rcu_read_unlock(); 1318 return result; 1319 } 1320 1321 static int update_lsm_rule(struct audit_krule *r) 1322 { 1323 struct audit_entry *entry = container_of(r, struct audit_entry, rule); 1324 struct audit_entry *nentry; 1325 struct audit_watch *watch; 1326 struct audit_tree *tree; 1327 int err = 0; 1328 1329 if (!security_audit_rule_known(r)) 1330 return 0; 1331 1332 watch = r->watch; 1333 tree = r->tree; 1334 nentry = audit_dupe_rule(r, watch); 1335 if (IS_ERR(nentry)) { 1336 /* save the first error encountered for the 1337 * return value */ 1338 err = PTR_ERR(nentry); 1339 audit_panic("error updating LSM filters"); 1340 if (watch) 1341 list_del(&r->rlist); 1342 list_del_rcu(&entry->list); 1343 list_del(&r->list); 1344 } else { 1345 if (watch) { 1346 list_add(&nentry->rule.rlist, audit_watch_rules(watch)); 1347 list_del(&r->rlist); 1348 } else if (tree) 1349 list_replace_init(&r->rlist, &nentry->rule.rlist); 1350 list_replace_rcu(&entry->list, &nentry->list); 1351 list_replace(&r->list, &nentry->rule.list); 1352 } 1353 call_rcu(&entry->rcu, audit_free_rule_rcu); 1354 1355 return err; 1356 } 1357 1358 /* This function will re-initialize the lsm_rule field of all applicable rules. 1359 * It will traverse the filter lists serarching for rules that contain LSM 1360 * specific filter fields. When such a rule is found, it is copied, the 1361 * LSM field is re-initialized, and the old rule is replaced with the 1362 * updated rule. */ 1363 int audit_update_lsm_rules(void) 1364 { 1365 struct audit_krule *r, *n; 1366 int i, err = 0; 1367 1368 /* audit_filter_mutex synchronizes the writers */ 1369 mutex_lock(&audit_filter_mutex); 1370 1371 for (i = 0; i < AUDIT_NR_FILTERS; i++) { 1372 list_for_each_entry_safe(r, n, &audit_rules_list[i], list) { 1373 int res = update_lsm_rule(r); 1374 if (!err) 1375 err = res; 1376 } 1377 } 1378 mutex_unlock(&audit_filter_mutex); 1379 1380 return err; 1381 } 1382