1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * AppArmor security module 4 * 5 * This file contains AppArmor mediation of files 6 * 7 * Copyright (C) 1998-2008 Novell/SUSE 8 * Copyright 2009-2010 Canonical Ltd. 9 */ 10 11 #include <linux/tty.h> 12 #include <linux/fdtable.h> 13 #include <linux/file.h> 14 #include <linux/fs.h> 15 #include <linux/mount.h> 16 17 #include "include/apparmor.h" 18 #include "include/audit.h" 19 #include "include/cred.h" 20 #include "include/file.h" 21 #include "include/match.h" 22 #include "include/net.h" 23 #include "include/path.h" 24 #include "include/policy.h" 25 #include "include/label.h" 26 27 static u32 map_mask_to_chr_mask(u32 mask) 28 { 29 u32 m = mask & PERMS_CHRS_MASK; 30 31 if (mask & AA_MAY_GETATTR) 32 m |= MAY_READ; 33 if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN)) 34 m |= MAY_WRITE; 35 36 return m; 37 } 38 39 /** 40 * file_audit_cb - call back for file specific audit fields 41 * @ab: audit_buffer (NOT NULL) 42 * @va: audit struct to audit values of (NOT NULL) 43 */ 44 static void file_audit_cb(struct audit_buffer *ab, void *va) 45 { 46 struct common_audit_data *sa = va; 47 kuid_t fsuid = current_fsuid(); 48 char str[10]; 49 50 if (aad(sa)->request & AA_AUDIT_FILE_MASK) { 51 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs, 52 map_mask_to_chr_mask(aad(sa)->request)); 53 audit_log_format(ab, " requested_mask=\"%s\"", str); 54 } 55 if (aad(sa)->denied & AA_AUDIT_FILE_MASK) { 56 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs, 57 map_mask_to_chr_mask(aad(sa)->denied)); 58 audit_log_format(ab, " denied_mask=\"%s\"", str); 59 } 60 if (aad(sa)->request & AA_AUDIT_FILE_MASK) { 61 audit_log_format(ab, " fsuid=%d", 62 from_kuid(&init_user_ns, fsuid)); 63 audit_log_format(ab, " ouid=%d", 64 from_kuid(&init_user_ns, aad(sa)->fs.ouid)); 65 } 66 67 if (aad(sa)->peer) { 68 audit_log_format(ab, " target="); 69 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer, 70 FLAG_VIEW_SUBNS, GFP_KERNEL); 71 } else if (aad(sa)->fs.target) { 72 audit_log_format(ab, " target="); 73 audit_log_untrustedstring(ab, aad(sa)->fs.target); 74 } 75 } 76 77 /** 78 * aa_audit_file - handle the auditing of file operations 79 * @profile: the profile being enforced (NOT NULL) 80 * @perms: the permissions computed for the request (NOT NULL) 81 * @op: operation being mediated 82 * @request: permissions requested 83 * @name: name of object being mediated (MAYBE NULL) 84 * @target: name of target (MAYBE NULL) 85 * @tlabel: target label (MAY BE NULL) 86 * @ouid: object uid 87 * @info: extra information message (MAYBE NULL) 88 * @error: 0 if operation allowed else failure error code 89 * 90 * Returns: %0 or error on failure 91 */ 92 int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms, 93 const char *op, u32 request, const char *name, 94 const char *target, struct aa_label *tlabel, 95 kuid_t ouid, const char *info, int error) 96 { 97 int type = AUDIT_APPARMOR_AUTO; 98 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op); 99 100 sa.u.tsk = NULL; 101 aad(&sa)->request = request; 102 aad(&sa)->name = name; 103 aad(&sa)->fs.target = target; 104 aad(&sa)->peer = tlabel; 105 aad(&sa)->fs.ouid = ouid; 106 aad(&sa)->info = info; 107 aad(&sa)->error = error; 108 sa.u.tsk = NULL; 109 110 if (likely(!aad(&sa)->error)) { 111 u32 mask = perms->audit; 112 113 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL)) 114 mask = 0xffff; 115 116 /* mask off perms that are not being force audited */ 117 aad(&sa)->request &= mask; 118 119 if (likely(!aad(&sa)->request)) 120 return 0; 121 type = AUDIT_APPARMOR_AUDIT; 122 } else { 123 /* only report permissions that were denied */ 124 aad(&sa)->request = aad(&sa)->request & ~perms->allow; 125 AA_BUG(!aad(&sa)->request); 126 127 if (aad(&sa)->request & perms->kill) 128 type = AUDIT_APPARMOR_KILL; 129 130 /* quiet known rejects, assumes quiet and kill do not overlap */ 131 if ((aad(&sa)->request & perms->quiet) && 132 AUDIT_MODE(profile) != AUDIT_NOQUIET && 133 AUDIT_MODE(profile) != AUDIT_ALL) 134 aad(&sa)->request &= ~perms->quiet; 135 136 if (!aad(&sa)->request) 137 return aad(&sa)->error; 138 } 139 140 aad(&sa)->denied = aad(&sa)->request & ~perms->allow; 141 return aa_audit(type, profile, &sa, file_audit_cb); 142 } 143 144 /** 145 * is_deleted - test if a file has been completely unlinked 146 * @dentry: dentry of file to test for deletion (NOT NULL) 147 * 148 * Returns: true if deleted else false 149 */ 150 static inline bool is_deleted(struct dentry *dentry) 151 { 152 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0) 153 return true; 154 return false; 155 } 156 157 static int path_name(const char *op, struct aa_label *label, 158 const struct path *path, int flags, char *buffer, 159 const char **name, struct path_cond *cond, u32 request) 160 { 161 struct aa_profile *profile; 162 const char *info = NULL; 163 int error; 164 165 error = aa_path_name(path, flags, buffer, name, &info, 166 labels_profile(label)->disconnected); 167 if (error) { 168 fn_for_each_confined(label, profile, 169 aa_audit_file(profile, &nullperms, op, request, *name, 170 NULL, NULL, cond->uid, info, error)); 171 return error; 172 } 173 174 return 0; 175 } 176 177 /** 178 * map_old_perms - map old file perms layout to the new layout 179 * @old: permission set in old mapping 180 * 181 * Returns: new permission mapping 182 */ 183 static u32 map_old_perms(u32 old) 184 { 185 u32 new = old & 0xf; 186 if (old & MAY_READ) 187 new |= AA_MAY_GETATTR | AA_MAY_OPEN; 188 if (old & MAY_WRITE) 189 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE | 190 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN; 191 if (old & 0x10) 192 new |= AA_MAY_LINK; 193 /* the old mapping lock and link_subset flags where overlaid 194 * and use was determined by part of a pair that they were in 195 */ 196 if (old & 0x20) 197 new |= AA_MAY_LOCK | AA_LINK_SUBSET; 198 if (old & 0x40) /* AA_EXEC_MMAP */ 199 new |= AA_EXEC_MMAP; 200 201 return new; 202 } 203 204 static void __aa_compute_fperms_allow(struct aa_perms *perms, 205 struct aa_dfa *dfa, 206 unsigned int state) 207 { 208 perms->allow |= AA_MAY_GETATTR; 209 210 /* change_profile wasn't determined by ownership in old mapping */ 211 if (ACCEPT_TABLE(dfa)[state] & 0x80000000) 212 perms->allow |= AA_MAY_CHANGE_PROFILE; 213 if (ACCEPT_TABLE(dfa)[state] & 0x40000000) 214 perms->allow |= AA_MAY_ONEXEC; 215 } 216 217 static struct aa_perms __aa_compute_fperms_user(struct aa_dfa *dfa, 218 unsigned int state) 219 { 220 struct aa_perms perms = { }; 221 222 perms.allow = map_old_perms(dfa_user_allow(dfa, state)); 223 perms.audit = map_old_perms(dfa_user_audit(dfa, state)); 224 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state)); 225 perms.xindex = dfa_user_xindex(dfa, state); 226 227 __aa_compute_fperms_allow(&perms, dfa, state); 228 229 return perms; 230 } 231 232 static struct aa_perms __aa_compute_fperms_other(struct aa_dfa *dfa, 233 unsigned int state) 234 { 235 struct aa_perms perms = { }; 236 237 perms.allow = map_old_perms(dfa_other_allow(dfa, state)); 238 perms.audit = map_old_perms(dfa_other_audit(dfa, state)); 239 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state)); 240 perms.xindex = dfa_other_xindex(dfa, state); 241 242 __aa_compute_fperms_allow(&perms, dfa, state); 243 244 return perms; 245 } 246 247 /** 248 * aa_compute_fperms - convert dfa compressed perms to internal perms and store 249 * them so they can be retrieved later. 250 * @file_rules: a file_rules structure containing a dfa (NOT NULL) for which 251 * permissions will be computed (NOT NULL) 252 * 253 * TODO: convert from dfa + state to permission entry 254 */ 255 void aa_compute_fperms(struct aa_file_rules *file_rules) 256 { 257 int state; 258 int state_count = file_rules->dfa->tables[YYTD_ID_BASE]->td_lolen; 259 260 // DFAs are restricted from having a state_count of less than 2 261 file_rules->fperms_table = kvzalloc( 262 state_count * 2 * sizeof(struct aa_perms), GFP_KERNEL); 263 264 // Since fperms_table is initialized with zeroes via kvzalloc(), we can 265 // skip the trap state (state == 0) 266 for (state = 1; state < state_count; state++) { 267 file_rules->fperms_table[state * 2] = 268 __aa_compute_fperms_user(file_rules->dfa, state); 269 file_rules->fperms_table[state * 2 + 1] = 270 __aa_compute_fperms_other(file_rules->dfa, state); 271 } 272 } 273 274 /** 275 * aa_lookup_fperms - convert dfa compressed perms to internal perms 276 * @dfa: dfa to lookup perms for (NOT NULL) 277 * @state: state in dfa 278 * @cond: conditions to consider (NOT NULL) 279 * 280 * TODO: convert from dfa + state to permission entry 281 * 282 * Returns: a pointer to a file permission set 283 */ 284 struct aa_perms default_perms = {}; 285 struct aa_perms *aa_lookup_fperms(struct aa_file_rules *file_rules, 286 unsigned int state, struct path_cond *cond) 287 { 288 if (!(file_rules->fperms_table)) 289 return &default_perms; 290 291 if (uid_eq(current_fsuid(), cond->uid)) 292 return &(file_rules->fperms_table[state * 2]); 293 294 return &(file_rules->fperms_table[state * 2 + 1]); 295 } 296 297 /** 298 * aa_str_perms - find permission that match @name 299 * @dfa: to match against (MAYBE NULL) 300 * @state: state to start matching in 301 * @name: string to match against dfa (NOT NULL) 302 * @cond: conditions to consider for permission set computation (NOT NULL) 303 * @perms: Returns - the permissions found when matching @name 304 * 305 * Returns: the final state in @dfa when beginning @start and walking @name 306 */ 307 unsigned int aa_str_perms(struct aa_file_rules *file_rules, unsigned int start, 308 const char *name, struct path_cond *cond, 309 struct aa_perms *perms) 310 { 311 unsigned int state; 312 state = aa_dfa_match(file_rules->dfa, start, name); 313 *perms = *(aa_lookup_fperms(file_rules, state, cond)); 314 315 return state; 316 } 317 318 int __aa_path_perm(const char *op, struct aa_profile *profile, const char *name, 319 u32 request, struct path_cond *cond, int flags, 320 struct aa_perms *perms) 321 { 322 int e = 0; 323 324 if (profile_unconfined(profile)) 325 return 0; 326 aa_str_perms(&(profile->file), profile->file.start, name, cond, perms); 327 if (request & ~perms->allow) 328 e = -EACCES; 329 return aa_audit_file(profile, perms, op, request, name, NULL, NULL, 330 cond->uid, NULL, e); 331 } 332 333 334 static int profile_path_perm(const char *op, struct aa_profile *profile, 335 const struct path *path, char *buffer, u32 request, 336 struct path_cond *cond, int flags, 337 struct aa_perms *perms) 338 { 339 const char *name; 340 int error; 341 342 if (profile_unconfined(profile)) 343 return 0; 344 345 error = path_name(op, &profile->label, path, 346 flags | profile->path_flags, buffer, &name, cond, 347 request); 348 if (error) 349 return error; 350 return __aa_path_perm(op, profile, name, request, cond, flags, 351 perms); 352 } 353 354 /** 355 * aa_path_perm - do permissions check & audit for @path 356 * @op: operation being checked 357 * @label: profile being enforced (NOT NULL) 358 * @path: path to check permissions of (NOT NULL) 359 * @flags: any additional path flags beyond what the profile specifies 360 * @request: requested permissions 361 * @cond: conditional info for this request (NOT NULL) 362 * 363 * Returns: %0 else error if access denied or other error 364 */ 365 int aa_path_perm(const char *op, struct aa_label *label, 366 const struct path *path, int flags, u32 request, 367 struct path_cond *cond) 368 { 369 struct aa_perms perms = {}; 370 struct aa_profile *profile; 371 char *buffer = NULL; 372 int error; 373 374 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR : 375 0); 376 buffer = aa_get_buffer(false); 377 if (!buffer) 378 return -ENOMEM; 379 error = fn_for_each_confined(label, profile, 380 profile_path_perm(op, profile, path, buffer, request, 381 cond, flags, &perms)); 382 383 aa_put_buffer(buffer); 384 385 return error; 386 } 387 388 /** 389 * xindex_is_subset - helper for aa_path_link 390 * @link: link permission set 391 * @target: target permission set 392 * 393 * test target x permissions are equal OR a subset of link x permissions 394 * this is done as part of the subset test, where a hardlink must have 395 * a subset of permissions that the target has. 396 * 397 * Returns: true if subset else false 398 */ 399 static inline bool xindex_is_subset(u32 link, u32 target) 400 { 401 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) || 402 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE))) 403 return false; 404 405 return true; 406 } 407 408 static int profile_path_link(struct aa_profile *profile, 409 const struct path *link, char *buffer, 410 const struct path *target, char *buffer2, 411 struct path_cond *cond) 412 { 413 const char *lname, *tname = NULL; 414 struct aa_perms lperms = {}, perms; 415 const char *info = NULL; 416 u32 request = AA_MAY_LINK; 417 unsigned int state; 418 int error; 419 420 error = path_name(OP_LINK, &profile->label, link, profile->path_flags, 421 buffer, &lname, cond, AA_MAY_LINK); 422 if (error) 423 goto audit; 424 425 /* buffer2 freed below, tname is pointer in buffer2 */ 426 error = path_name(OP_LINK, &profile->label, target, profile->path_flags, 427 buffer2, &tname, cond, AA_MAY_LINK); 428 if (error) 429 goto audit; 430 431 error = -EACCES; 432 /* aa_str_perms - handles the case of the dfa being NULL */ 433 state = aa_str_perms(&(profile->file), profile->file.start, lname, 434 cond, &lperms); 435 436 if (!(lperms.allow & AA_MAY_LINK)) 437 goto audit; 438 439 /* test to see if target can be paired with link */ 440 state = aa_dfa_null_transition(profile->file.dfa, state); 441 aa_str_perms(&(profile->file), state, tname, cond, &perms); 442 443 /* force audit/quiet masks for link are stored in the second entry 444 * in the link pair. 445 */ 446 lperms.audit = perms.audit; 447 lperms.quiet = perms.quiet; 448 lperms.kill = perms.kill; 449 450 if (!(perms.allow & AA_MAY_LINK)) { 451 info = "target restricted"; 452 lperms = perms; 453 goto audit; 454 } 455 456 /* done if link subset test is not required */ 457 if (!(perms.allow & AA_LINK_SUBSET)) 458 goto done_tests; 459 460 /* Do link perm subset test requiring allowed permission on link are 461 * a subset of the allowed permissions on target. 462 */ 463 aa_str_perms(&(profile->file), profile->file.start, tname, cond, 464 &perms); 465 466 /* AA_MAY_LINK is not considered in the subset test */ 467 request = lperms.allow & ~AA_MAY_LINK; 468 lperms.allow &= perms.allow | AA_MAY_LINK; 469 470 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow); 471 if (request & ~lperms.allow) { 472 goto audit; 473 } else if ((lperms.allow & MAY_EXEC) && 474 !xindex_is_subset(lperms.xindex, perms.xindex)) { 475 lperms.allow &= ~MAY_EXEC; 476 request |= MAY_EXEC; 477 info = "link not subset of target"; 478 goto audit; 479 } 480 481 done_tests: 482 error = 0; 483 484 audit: 485 return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname, 486 NULL, cond->uid, info, error); 487 } 488 489 /** 490 * aa_path_link - Handle hard link permission check 491 * @label: the label being enforced (NOT NULL) 492 * @old_dentry: the target dentry (NOT NULL) 493 * @new_dir: directory the new link will be created in (NOT NULL) 494 * @new_dentry: the link being created (NOT NULL) 495 * 496 * Handle the permission test for a link & target pair. Permission 497 * is encoded as a pair where the link permission is determined 498 * first, and if allowed, the target is tested. The target test 499 * is done from the point of the link match (not start of DFA) 500 * making the target permission dependent on the link permission match. 501 * 502 * The subset test if required forces that permissions granted 503 * on link are a subset of the permission granted to target. 504 * 505 * Returns: %0 if allowed else error 506 */ 507 int aa_path_link(struct aa_label *label, struct dentry *old_dentry, 508 const struct path *new_dir, struct dentry *new_dentry) 509 { 510 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry }; 511 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry }; 512 struct path_cond cond = { 513 d_backing_inode(old_dentry)->i_uid, 514 d_backing_inode(old_dentry)->i_mode 515 }; 516 char *buffer = NULL, *buffer2 = NULL; 517 struct aa_profile *profile; 518 int error; 519 520 /* buffer freed below, lname is pointer in buffer */ 521 buffer = aa_get_buffer(false); 522 buffer2 = aa_get_buffer(false); 523 error = -ENOMEM; 524 if (!buffer || !buffer2) 525 goto out; 526 527 error = fn_for_each_confined(label, profile, 528 profile_path_link(profile, &link, buffer, &target, 529 buffer2, &cond)); 530 out: 531 aa_put_buffer(buffer); 532 aa_put_buffer(buffer2); 533 return error; 534 } 535 536 static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label, 537 u32 request) 538 { 539 struct aa_label *l, *old; 540 541 /* update caching of label on file_ctx */ 542 spin_lock(&fctx->lock); 543 old = rcu_dereference_protected(fctx->label, 544 lockdep_is_held(&fctx->lock)); 545 l = aa_label_merge(old, label, GFP_ATOMIC); 546 if (l) { 547 if (l != old) { 548 rcu_assign_pointer(fctx->label, l); 549 aa_put_label(old); 550 } else 551 aa_put_label(l); 552 fctx->allow |= request; 553 } 554 spin_unlock(&fctx->lock); 555 } 556 557 static int __file_path_perm(const char *op, struct aa_label *label, 558 struct aa_label *flabel, struct file *file, 559 u32 request, u32 denied, bool in_atomic) 560 { 561 struct aa_profile *profile; 562 struct aa_perms perms = {}; 563 struct path_cond cond = { 564 .uid = i_uid_into_mnt(file_mnt_user_ns(file), file_inode(file)), 565 .mode = file_inode(file)->i_mode 566 }; 567 char *buffer; 568 int flags, error; 569 570 /* revalidation due to label out of date. No revocation at this time */ 571 if (!denied && aa_label_is_subset(flabel, label)) 572 /* TODO: check for revocation on stale profiles */ 573 return 0; 574 575 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0); 576 buffer = aa_get_buffer(in_atomic); 577 if (!buffer) 578 return -ENOMEM; 579 580 /* check every profile in task label not in current cache */ 581 error = fn_for_each_not_in_set(flabel, label, profile, 582 profile_path_perm(op, profile, &file->f_path, buffer, 583 request, &cond, flags, &perms)); 584 if (denied && !error) { 585 /* 586 * check every profile in file label that was not tested 587 * in the initial check above. 588 * 589 * TODO: cache full perms so this only happens because of 590 * conditionals 591 * TODO: don't audit here 592 */ 593 if (label == flabel) 594 error = fn_for_each(label, profile, 595 profile_path_perm(op, profile, &file->f_path, 596 buffer, request, &cond, flags, 597 &perms)); 598 else 599 error = fn_for_each_not_in_set(label, flabel, profile, 600 profile_path_perm(op, profile, &file->f_path, 601 buffer, request, &cond, flags, 602 &perms)); 603 } 604 if (!error) 605 update_file_ctx(file_ctx(file), label, request); 606 607 aa_put_buffer(buffer); 608 609 return error; 610 } 611 612 static int __file_sock_perm(const char *op, struct aa_label *label, 613 struct aa_label *flabel, struct file *file, 614 u32 request, u32 denied) 615 { 616 struct socket *sock = (struct socket *) file->private_data; 617 int error; 618 619 AA_BUG(!sock); 620 621 /* revalidation due to label out of date. No revocation at this time */ 622 if (!denied && aa_label_is_subset(flabel, label)) 623 return 0; 624 625 /* TODO: improve to skip profiles cached in flabel */ 626 error = aa_sock_file_perm(label, op, request, sock); 627 if (denied) { 628 /* TODO: improve to skip profiles checked above */ 629 /* check every profile in file label to is cached */ 630 last_error(error, aa_sock_file_perm(flabel, op, request, sock)); 631 } 632 if (!error) 633 update_file_ctx(file_ctx(file), label, request); 634 635 return error; 636 } 637 638 /** 639 * aa_file_perm - do permission revalidation check & audit for @file 640 * @op: operation being checked 641 * @label: label being enforced (NOT NULL) 642 * @file: file to revalidate access permissions on (NOT NULL) 643 * @request: requested permissions 644 * @in_atomic: whether allocations need to be done in atomic context 645 * 646 * Returns: %0 if access allowed else error 647 */ 648 int aa_file_perm(const char *op, struct aa_label *label, struct file *file, 649 u32 request, bool in_atomic) 650 { 651 struct aa_file_ctx *fctx; 652 struct aa_label *flabel; 653 u32 denied; 654 int error = 0; 655 656 AA_BUG(!label); 657 AA_BUG(!file); 658 659 fctx = file_ctx(file); 660 661 rcu_read_lock(); 662 flabel = rcu_dereference(fctx->label); 663 AA_BUG(!flabel); 664 665 /* revalidate access, if task is unconfined, or the cached cred 666 * doesn't match or if the request is for more permissions than 667 * was granted. 668 * 669 * Note: the test for !unconfined(flabel) is to handle file 670 * delegation from unconfined tasks 671 */ 672 denied = request & ~fctx->allow; 673 if (unconfined(label) || unconfined(flabel) || 674 (!denied && aa_label_is_subset(flabel, label))) { 675 rcu_read_unlock(); 676 goto done; 677 } 678 679 flabel = aa_get_newest_label(flabel); 680 rcu_read_unlock(); 681 /* TODO: label cross check */ 682 683 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry)) 684 error = __file_path_perm(op, label, flabel, file, request, 685 denied, in_atomic); 686 687 else if (S_ISSOCK(file_inode(file)->i_mode)) 688 error = __file_sock_perm(op, label, flabel, file, request, 689 denied); 690 aa_put_label(flabel); 691 692 done: 693 return error; 694 } 695 696 static void revalidate_tty(struct aa_label *label) 697 { 698 struct tty_struct *tty; 699 int drop_tty = 0; 700 701 tty = get_current_tty(); 702 if (!tty) 703 return; 704 705 spin_lock(&tty->files_lock); 706 if (!list_empty(&tty->tty_files)) { 707 struct tty_file_private *file_priv; 708 struct file *file; 709 /* TODO: Revalidate access to controlling tty. */ 710 file_priv = list_first_entry(&tty->tty_files, 711 struct tty_file_private, list); 712 file = file_priv->file; 713 714 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE, 715 IN_ATOMIC)) 716 drop_tty = 1; 717 } 718 spin_unlock(&tty->files_lock); 719 tty_kref_put(tty); 720 721 if (drop_tty) 722 no_tty(); 723 } 724 725 static int match_file(const void *p, struct file *file, unsigned int fd) 726 { 727 struct aa_label *label = (struct aa_label *)p; 728 729 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file), 730 IN_ATOMIC)) 731 return fd + 1; 732 return 0; 733 } 734 735 736 /* based on selinux's flush_unauthorized_files */ 737 void aa_inherit_files(const struct cred *cred, struct files_struct *files) 738 { 739 struct aa_label *label = aa_get_newest_cred_label(cred); 740 struct file *devnull = NULL; 741 unsigned int n; 742 743 revalidate_tty(label); 744 745 /* Revalidate access to inherited open files. */ 746 n = iterate_fd(files, 0, match_file, label); 747 if (!n) /* none found? */ 748 goto out; 749 750 devnull = dentry_open(&aa_null, O_RDWR, cred); 751 if (IS_ERR(devnull)) 752 devnull = NULL; 753 /* replace all the matching ones with this */ 754 do { 755 replace_fd(n - 1, devnull, 0); 756 } while ((n = iterate_fd(files, n, match_file, label)) != 0); 757 if (devnull) 758 fput(devnull); 759 out: 760 aa_put_label(label); 761 } 762