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 2009-2017 Canonical Ltd. 9 */ 10 11 #include <linux/fs.h> 12 #include <linux/mount.h> 13 #include <linux/namei.h> 14 #include <uapi/linux/mount.h> 15 16 #include "include/apparmor.h" 17 #include "include/audit.h" 18 #include "include/cred.h" 19 #include "include/domain.h" 20 #include "include/file.h" 21 #include "include/match.h" 22 #include "include/mount.h" 23 #include "include/path.h" 24 #include "include/policy.h" 25 26 27 static void audit_mnt_flags(struct audit_buffer *ab, unsigned long flags) 28 { 29 if (flags & MS_RDONLY) 30 audit_log_format(ab, "ro"); 31 else 32 audit_log_format(ab, "rw"); 33 if (flags & MS_NOSUID) 34 audit_log_format(ab, ", nosuid"); 35 if (flags & MS_NODEV) 36 audit_log_format(ab, ", nodev"); 37 if (flags & MS_NOEXEC) 38 audit_log_format(ab, ", noexec"); 39 if (flags & MS_SYNCHRONOUS) 40 audit_log_format(ab, ", sync"); 41 if (flags & MS_REMOUNT) 42 audit_log_format(ab, ", remount"); 43 if (flags & MS_MANDLOCK) 44 audit_log_format(ab, ", mand"); 45 if (flags & MS_DIRSYNC) 46 audit_log_format(ab, ", dirsync"); 47 if (flags & MS_NOATIME) 48 audit_log_format(ab, ", noatime"); 49 if (flags & MS_NODIRATIME) 50 audit_log_format(ab, ", nodiratime"); 51 if (flags & MS_BIND) 52 audit_log_format(ab, flags & MS_REC ? ", rbind" : ", bind"); 53 if (flags & MS_MOVE) 54 audit_log_format(ab, ", move"); 55 if (flags & MS_SILENT) 56 audit_log_format(ab, ", silent"); 57 if (flags & MS_POSIXACL) 58 audit_log_format(ab, ", acl"); 59 if (flags & MS_UNBINDABLE) 60 audit_log_format(ab, flags & MS_REC ? ", runbindable" : 61 ", unbindable"); 62 if (flags & MS_PRIVATE) 63 audit_log_format(ab, flags & MS_REC ? ", rprivate" : 64 ", private"); 65 if (flags & MS_SLAVE) 66 audit_log_format(ab, flags & MS_REC ? ", rslave" : 67 ", slave"); 68 if (flags & MS_SHARED) 69 audit_log_format(ab, flags & MS_REC ? ", rshared" : 70 ", shared"); 71 if (flags & MS_RELATIME) 72 audit_log_format(ab, ", relatime"); 73 if (flags & MS_I_VERSION) 74 audit_log_format(ab, ", iversion"); 75 if (flags & MS_STRICTATIME) 76 audit_log_format(ab, ", strictatime"); 77 if (flags & MS_NOUSER) 78 audit_log_format(ab, ", nouser"); 79 } 80 81 /** 82 * audit_cb - call back for mount specific audit fields 83 * @ab: audit_buffer (NOT NULL) 84 * @va: audit struct to audit values of (NOT NULL) 85 */ 86 static void audit_cb(struct audit_buffer *ab, void *va) 87 { 88 struct common_audit_data *sa = va; 89 90 if (aad(sa)->mnt.type) { 91 audit_log_format(ab, " fstype="); 92 audit_log_untrustedstring(ab, aad(sa)->mnt.type); 93 } 94 if (aad(sa)->mnt.src_name) { 95 audit_log_format(ab, " srcname="); 96 audit_log_untrustedstring(ab, aad(sa)->mnt.src_name); 97 } 98 if (aad(sa)->mnt.trans) { 99 audit_log_format(ab, " trans="); 100 audit_log_untrustedstring(ab, aad(sa)->mnt.trans); 101 } 102 if (aad(sa)->mnt.flags) { 103 audit_log_format(ab, " flags=\""); 104 audit_mnt_flags(ab, aad(sa)->mnt.flags); 105 audit_log_format(ab, "\""); 106 } 107 if (aad(sa)->mnt.data) { 108 audit_log_format(ab, " options="); 109 audit_log_untrustedstring(ab, aad(sa)->mnt.data); 110 } 111 } 112 113 /** 114 * audit_mount - handle the auditing of mount operations 115 * @profile: the profile being enforced (NOT NULL) 116 * @op: operation being mediated (NOT NULL) 117 * @name: name of object being mediated (MAYBE NULL) 118 * @src_name: src_name of object being mediated (MAYBE_NULL) 119 * @type: type of filesystem (MAYBE_NULL) 120 * @trans: name of trans (MAYBE NULL) 121 * @flags: filesystem independent mount flags 122 * @data: filesystem mount flags 123 * @request: permissions requested 124 * @perms: the permissions computed for the request (NOT NULL) 125 * @info: extra information message (MAYBE NULL) 126 * @error: 0 if operation allowed else failure error code 127 * 128 * Returns: %0 or error on failure 129 */ 130 static int audit_mount(struct aa_profile *profile, const char *op, 131 const char *name, const char *src_name, 132 const char *type, const char *trans, 133 unsigned long flags, const void *data, u32 request, 134 struct aa_perms *perms, const char *info, int error) 135 { 136 int audit_type = AUDIT_APPARMOR_AUTO; 137 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, op); 138 139 if (likely(!error)) { 140 u32 mask = perms->audit; 141 142 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL)) 143 mask = 0xffff; 144 145 /* mask off perms that are not being force audited */ 146 request &= mask; 147 148 if (likely(!request)) 149 return 0; 150 audit_type = AUDIT_APPARMOR_AUDIT; 151 } else { 152 /* only report permissions that were denied */ 153 request = request & ~perms->allow; 154 155 if (request & perms->kill) 156 audit_type = AUDIT_APPARMOR_KILL; 157 158 /* quiet known rejects, assumes quiet and kill do not overlap */ 159 if ((request & perms->quiet) && 160 AUDIT_MODE(profile) != AUDIT_NOQUIET && 161 AUDIT_MODE(profile) != AUDIT_ALL) 162 request &= ~perms->quiet; 163 164 if (!request) 165 return error; 166 } 167 168 aad(&sa)->name = name; 169 aad(&sa)->mnt.src_name = src_name; 170 aad(&sa)->mnt.type = type; 171 aad(&sa)->mnt.trans = trans; 172 aad(&sa)->mnt.flags = flags; 173 if (data && (perms->audit & AA_AUDIT_DATA)) 174 aad(&sa)->mnt.data = data; 175 aad(&sa)->info = info; 176 aad(&sa)->error = error; 177 178 return aa_audit(audit_type, profile, &sa, audit_cb); 179 } 180 181 /** 182 * match_mnt_flags - Do an ordered match on mount flags 183 * @dfa: dfa to match against 184 * @state: state to start in 185 * @flags: mount flags to match against 186 * 187 * Mount flags are encoded as an ordered match. This is done instead of 188 * checking against a simple bitmask, to allow for logical operations 189 * on the flags. 190 * 191 * Returns: next state after flags match 192 */ 193 static unsigned int match_mnt_flags(struct aa_dfa *dfa, unsigned int state, 194 unsigned long flags) 195 { 196 unsigned int i; 197 198 for (i = 0; i <= 31 ; ++i) { 199 if ((1 << i) & flags) 200 state = aa_dfa_next(dfa, state, i + 1); 201 } 202 203 return state; 204 } 205 206 /** 207 * compute_mnt_perms - compute mount permission associated with @state 208 * @dfa: dfa to match against (NOT NULL) 209 * @state: state match finished in 210 * 211 * Returns: mount permissions 212 */ 213 static struct aa_perms compute_mnt_perms(struct aa_dfa *dfa, 214 unsigned int state) 215 { 216 struct aa_perms perms = { 217 .allow = dfa_user_allow(dfa, state), 218 .audit = dfa_user_audit(dfa, state), 219 .quiet = dfa_user_quiet(dfa, state), 220 }; 221 222 return perms; 223 } 224 225 static const char * const mnt_info_table[] = { 226 "match succeeded", 227 "failed mntpnt match", 228 "failed srcname match", 229 "failed type match", 230 "failed flags match", 231 "failed data match", 232 "failed perms check" 233 }; 234 235 /* 236 * Returns 0 on success else element that match failed in, this is the 237 * index into the mnt_info_table above 238 */ 239 static int do_match_mnt(struct aa_dfa *dfa, unsigned int start, 240 const char *mntpnt, const char *devname, 241 const char *type, unsigned long flags, 242 void *data, bool binary, struct aa_perms *perms) 243 { 244 unsigned int state; 245 246 AA_BUG(!dfa); 247 AA_BUG(!perms); 248 249 state = aa_dfa_match(dfa, start, mntpnt); 250 state = aa_dfa_null_transition(dfa, state); 251 if (!state) 252 return 1; 253 254 if (devname) 255 state = aa_dfa_match(dfa, state, devname); 256 state = aa_dfa_null_transition(dfa, state); 257 if (!state) 258 return 2; 259 260 if (type) 261 state = aa_dfa_match(dfa, state, type); 262 state = aa_dfa_null_transition(dfa, state); 263 if (!state) 264 return 3; 265 266 state = match_mnt_flags(dfa, state, flags); 267 if (!state) 268 return 4; 269 *perms = compute_mnt_perms(dfa, state); 270 if (perms->allow & AA_MAY_MOUNT) 271 return 0; 272 273 /* only match data if not binary and the DFA flags data is expected */ 274 if (data && !binary && (perms->allow & AA_MNT_CONT_MATCH)) { 275 state = aa_dfa_null_transition(dfa, state); 276 if (!state) 277 return 4; 278 279 state = aa_dfa_match(dfa, state, data); 280 if (!state) 281 return 5; 282 *perms = compute_mnt_perms(dfa, state); 283 if (perms->allow & AA_MAY_MOUNT) 284 return 0; 285 } 286 287 /* failed at perms check, don't confuse with flags match */ 288 return 6; 289 } 290 291 292 static int path_flags(struct aa_profile *profile, const struct path *path) 293 { 294 AA_BUG(!profile); 295 AA_BUG(!path); 296 297 return profile->path_flags | 298 (S_ISDIR(path->dentry->d_inode->i_mode) ? PATH_IS_DIR : 0); 299 } 300 301 /** 302 * match_mnt_path_str - handle path matching for mount 303 * @profile: the confining profile 304 * @mntpath: for the mntpnt (NOT NULL) 305 * @buffer: buffer to be used to lookup mntpath 306 * @devname: string for the devname/src_name (MAY BE NULL OR ERRPTR) 307 * @type: string for the dev type (MAYBE NULL) 308 * @flags: mount flags to match 309 * @data: fs mount data (MAYBE NULL) 310 * @binary: whether @data is binary 311 * @devinfo: error str if (IS_ERR(@devname)) 312 * 313 * Returns: 0 on success else error 314 */ 315 static int match_mnt_path_str(struct aa_profile *profile, 316 const struct path *mntpath, char *buffer, 317 const char *devname, const char *type, 318 unsigned long flags, void *data, bool binary, 319 const char *devinfo) 320 { 321 struct aa_perms perms = { }; 322 const char *mntpnt = NULL, *info = NULL; 323 int pos, error; 324 325 AA_BUG(!profile); 326 AA_BUG(!mntpath); 327 AA_BUG(!buffer); 328 329 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) 330 return 0; 331 332 error = aa_path_name(mntpath, path_flags(profile, mntpath), buffer, 333 &mntpnt, &info, profile->disconnected); 334 if (error) 335 goto audit; 336 if (IS_ERR(devname)) { 337 error = PTR_ERR(devname); 338 devname = NULL; 339 info = devinfo; 340 goto audit; 341 } 342 343 error = -EACCES; 344 pos = do_match_mnt(profile->policy.dfa, 345 profile->policy.start[AA_CLASS_MOUNT], 346 mntpnt, devname, type, flags, data, binary, &perms); 347 if (pos) { 348 info = mnt_info_table[pos]; 349 goto audit; 350 } 351 error = 0; 352 353 audit: 354 return audit_mount(profile, OP_MOUNT, mntpnt, devname, type, NULL, 355 flags, data, AA_MAY_MOUNT, &perms, info, error); 356 } 357 358 /** 359 * match_mnt - handle path matching for mount 360 * @profile: the confining profile 361 * @path: for the mntpnt (NOT NULL) 362 * @buffer: buffer to be used to lookup mntpath 363 * @devpath: path devname/src_name (MAYBE NULL) 364 * @devbuffer: buffer to be used to lookup devname/src_name 365 * @type: string for the dev type (MAYBE NULL) 366 * @flags: mount flags to match 367 * @data: fs mount data (MAYBE NULL) 368 * @binary: whether @data is binary 369 * 370 * Returns: 0 on success else error 371 */ 372 static int match_mnt(struct aa_profile *profile, const struct path *path, 373 char *buffer, const struct path *devpath, char *devbuffer, 374 const char *type, unsigned long flags, void *data, 375 bool binary) 376 { 377 const char *devname = NULL, *info = NULL; 378 int error = -EACCES; 379 380 AA_BUG(!profile); 381 AA_BUG(devpath && !devbuffer); 382 383 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) 384 return 0; 385 386 if (devpath) { 387 error = aa_path_name(devpath, path_flags(profile, devpath), 388 devbuffer, &devname, &info, 389 profile->disconnected); 390 if (error) 391 devname = ERR_PTR(error); 392 } 393 394 return match_mnt_path_str(profile, path, buffer, devname, type, flags, 395 data, binary, info); 396 } 397 398 int aa_remount(struct aa_label *label, const struct path *path, 399 unsigned long flags, void *data) 400 { 401 struct aa_profile *profile; 402 char *buffer = NULL; 403 bool binary; 404 int error; 405 406 AA_BUG(!label); 407 AA_BUG(!path); 408 409 binary = path->dentry->d_sb->s_type->fs_flags & FS_BINARY_MOUNTDATA; 410 411 buffer = aa_get_buffer(false); 412 if (!buffer) 413 return -ENOMEM; 414 error = fn_for_each_confined(label, profile, 415 match_mnt(profile, path, buffer, NULL, NULL, NULL, 416 flags, data, binary)); 417 aa_put_buffer(buffer); 418 419 return error; 420 } 421 422 int aa_bind_mount(struct aa_label *label, const struct path *path, 423 const char *dev_name, unsigned long flags) 424 { 425 struct aa_profile *profile; 426 char *buffer = NULL, *old_buffer = NULL; 427 struct path old_path; 428 int error; 429 430 AA_BUG(!label); 431 AA_BUG(!path); 432 433 if (!dev_name || !*dev_name) 434 return -EINVAL; 435 436 flags &= MS_REC | MS_BIND; 437 438 error = kern_path(dev_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); 439 if (error) 440 return error; 441 442 buffer = aa_get_buffer(false); 443 old_buffer = aa_get_buffer(false); 444 error = -ENOMEM; 445 if (!buffer || !old_buffer) 446 goto out; 447 448 error = fn_for_each_confined(label, profile, 449 match_mnt(profile, path, buffer, &old_path, old_buffer, 450 NULL, flags, NULL, false)); 451 out: 452 aa_put_buffer(buffer); 453 aa_put_buffer(old_buffer); 454 path_put(&old_path); 455 456 return error; 457 } 458 459 int aa_mount_change_type(struct aa_label *label, const struct path *path, 460 unsigned long flags) 461 { 462 struct aa_profile *profile; 463 char *buffer = NULL; 464 int error; 465 466 AA_BUG(!label); 467 AA_BUG(!path); 468 469 /* These are the flags allowed by do_change_type() */ 470 flags &= (MS_REC | MS_SILENT | MS_SHARED | MS_PRIVATE | MS_SLAVE | 471 MS_UNBINDABLE); 472 473 buffer = aa_get_buffer(false); 474 if (!buffer) 475 return -ENOMEM; 476 error = fn_for_each_confined(label, profile, 477 match_mnt(profile, path, buffer, NULL, NULL, NULL, 478 flags, NULL, false)); 479 aa_put_buffer(buffer); 480 481 return error; 482 } 483 484 int aa_move_mount(struct aa_label *label, const struct path *path, 485 const char *orig_name) 486 { 487 struct aa_profile *profile; 488 char *buffer = NULL, *old_buffer = NULL; 489 struct path old_path; 490 int error; 491 492 AA_BUG(!label); 493 AA_BUG(!path); 494 495 if (!orig_name || !*orig_name) 496 return -EINVAL; 497 498 error = kern_path(orig_name, LOOKUP_FOLLOW, &old_path); 499 if (error) 500 return error; 501 502 buffer = aa_get_buffer(false); 503 old_buffer = aa_get_buffer(false); 504 error = -ENOMEM; 505 if (!buffer || !old_buffer) 506 goto out; 507 error = fn_for_each_confined(label, profile, 508 match_mnt(profile, path, buffer, &old_path, old_buffer, 509 NULL, MS_MOVE, NULL, false)); 510 out: 511 aa_put_buffer(buffer); 512 aa_put_buffer(old_buffer); 513 path_put(&old_path); 514 515 return error; 516 } 517 518 int aa_new_mount(struct aa_label *label, const char *dev_name, 519 const struct path *path, const char *type, unsigned long flags, 520 void *data) 521 { 522 struct aa_profile *profile; 523 char *buffer = NULL, *dev_buffer = NULL; 524 bool binary = true; 525 int error; 526 int requires_dev = 0; 527 struct path tmp_path, *dev_path = NULL; 528 529 AA_BUG(!label); 530 AA_BUG(!path); 531 532 if (type) { 533 struct file_system_type *fstype; 534 535 fstype = get_fs_type(type); 536 if (!fstype) 537 return -ENODEV; 538 binary = fstype->fs_flags & FS_BINARY_MOUNTDATA; 539 requires_dev = fstype->fs_flags & FS_REQUIRES_DEV; 540 put_filesystem(fstype); 541 542 if (requires_dev) { 543 if (!dev_name || !*dev_name) 544 return -ENOENT; 545 546 error = kern_path(dev_name, LOOKUP_FOLLOW, &tmp_path); 547 if (error) 548 return error; 549 dev_path = &tmp_path; 550 } 551 } 552 553 buffer = aa_get_buffer(false); 554 if (!buffer) { 555 error = -ENOMEM; 556 goto out; 557 } 558 if (dev_path) { 559 dev_buffer = aa_get_buffer(false); 560 if (!dev_buffer) { 561 error = -ENOMEM; 562 goto out; 563 } 564 error = fn_for_each_confined(label, profile, 565 match_mnt(profile, path, buffer, dev_path, dev_buffer, 566 type, flags, data, binary)); 567 } else { 568 error = fn_for_each_confined(label, profile, 569 match_mnt_path_str(profile, path, buffer, dev_name, 570 type, flags, data, binary, NULL)); 571 } 572 573 out: 574 aa_put_buffer(buffer); 575 aa_put_buffer(dev_buffer); 576 if (dev_path) 577 path_put(dev_path); 578 579 return error; 580 } 581 582 static int profile_umount(struct aa_profile *profile, const struct path *path, 583 char *buffer) 584 { 585 struct aa_perms perms = { }; 586 const char *name = NULL, *info = NULL; 587 unsigned int state; 588 int error; 589 590 AA_BUG(!profile); 591 AA_BUG(!path); 592 593 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) 594 return 0; 595 596 error = aa_path_name(path, path_flags(profile, path), buffer, &name, 597 &info, profile->disconnected); 598 if (error) 599 goto audit; 600 601 state = aa_dfa_match(profile->policy.dfa, 602 profile->policy.start[AA_CLASS_MOUNT], 603 name); 604 perms = compute_mnt_perms(profile->policy.dfa, state); 605 if (AA_MAY_UMOUNT & ~perms.allow) 606 error = -EACCES; 607 608 audit: 609 return audit_mount(profile, OP_UMOUNT, name, NULL, NULL, NULL, 0, NULL, 610 AA_MAY_UMOUNT, &perms, info, error); 611 } 612 613 int aa_umount(struct aa_label *label, struct vfsmount *mnt, int flags) 614 { 615 struct aa_profile *profile; 616 char *buffer = NULL; 617 int error; 618 struct path path = { .mnt = mnt, .dentry = mnt->mnt_root }; 619 620 AA_BUG(!label); 621 AA_BUG(!mnt); 622 623 buffer = aa_get_buffer(false); 624 if (!buffer) 625 return -ENOMEM; 626 627 error = fn_for_each_confined(label, profile, 628 profile_umount(profile, &path, buffer)); 629 aa_put_buffer(buffer); 630 631 return error; 632 } 633 634 /* helper fn for transition on pivotroot 635 * 636 * Returns: label for transition or ERR_PTR. Does not return NULL 637 */ 638 static struct aa_label *build_pivotroot(struct aa_profile *profile, 639 const struct path *new_path, 640 char *new_buffer, 641 const struct path *old_path, 642 char *old_buffer) 643 { 644 const char *old_name, *new_name = NULL, *info = NULL; 645 const char *trans_name = NULL; 646 struct aa_perms perms = { }; 647 unsigned int state; 648 int error; 649 650 AA_BUG(!profile); 651 AA_BUG(!new_path); 652 AA_BUG(!old_path); 653 654 if (profile_unconfined(profile) || 655 !PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) 656 return aa_get_newest_label(&profile->label); 657 658 error = aa_path_name(old_path, path_flags(profile, old_path), 659 old_buffer, &old_name, &info, 660 profile->disconnected); 661 if (error) 662 goto audit; 663 error = aa_path_name(new_path, path_flags(profile, new_path), 664 new_buffer, &new_name, &info, 665 profile->disconnected); 666 if (error) 667 goto audit; 668 669 error = -EACCES; 670 state = aa_dfa_match(profile->policy.dfa, 671 profile->policy.start[AA_CLASS_MOUNT], 672 new_name); 673 state = aa_dfa_null_transition(profile->policy.dfa, state); 674 state = aa_dfa_match(profile->policy.dfa, state, old_name); 675 perms = compute_mnt_perms(profile->policy.dfa, state); 676 677 if (AA_MAY_PIVOTROOT & perms.allow) 678 error = 0; 679 680 audit: 681 error = audit_mount(profile, OP_PIVOTROOT, new_name, old_name, 682 NULL, trans_name, 0, NULL, AA_MAY_PIVOTROOT, 683 &perms, info, error); 684 if (error) 685 return ERR_PTR(error); 686 687 return aa_get_newest_label(&profile->label); 688 } 689 690 int aa_pivotroot(struct aa_label *label, const struct path *old_path, 691 const struct path *new_path) 692 { 693 struct aa_profile *profile; 694 struct aa_label *target = NULL; 695 char *old_buffer = NULL, *new_buffer = NULL, *info = NULL; 696 int error; 697 698 AA_BUG(!label); 699 AA_BUG(!old_path); 700 AA_BUG(!new_path); 701 702 old_buffer = aa_get_buffer(false); 703 new_buffer = aa_get_buffer(false); 704 error = -ENOMEM; 705 if (!old_buffer || !new_buffer) 706 goto out; 707 target = fn_label_build(label, profile, GFP_KERNEL, 708 build_pivotroot(profile, new_path, new_buffer, 709 old_path, old_buffer)); 710 if (!target) { 711 info = "label build failed"; 712 error = -ENOMEM; 713 goto fail; 714 } else if (!IS_ERR(target)) { 715 error = aa_replace_current_label(target); 716 if (error) { 717 /* TODO: audit target */ 718 aa_put_label(target); 719 goto out; 720 } 721 aa_put_label(target); 722 } else 723 /* already audited error */ 724 error = PTR_ERR(target); 725 out: 726 aa_put_buffer(old_buffer); 727 aa_put_buffer(new_buffer); 728 729 return error; 730 731 fail: 732 /* TODO: add back in auditing of new_name and old_name */ 733 error = fn_for_each(label, profile, 734 audit_mount(profile, OP_PIVOTROOT, NULL /*new_name */, 735 NULL /* old_name */, 736 NULL, NULL, 737 0, NULL, AA_MAY_PIVOTROOT, &nullperms, info, 738 error)); 739 goto out; 740 } 741