1 /* 2 * AppArmor security module 3 * 4 * This file contains AppArmor mediation of files 5 * 6 * Copyright (C) 1998-2008 Novell/SUSE 7 * Copyright 2009-2017 Canonical Ltd. 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License as 11 * published by the Free Software Foundation, version 2 of the 12 * License. 13 */ 14 15 #include <linux/fs.h> 16 #include <linux/mount.h> 17 #include <linux/namei.h> 18 #include <uapi/linux/mount.h> 19 20 #include "include/apparmor.h" 21 #include "include/audit.h" 22 #include "include/cred.h" 23 #include "include/domain.h" 24 #include "include/file.h" 25 #include "include/match.h" 26 #include "include/mount.h" 27 #include "include/path.h" 28 #include "include/policy.h" 29 30 31 static void audit_mnt_flags(struct audit_buffer *ab, unsigned long flags) 32 { 33 if (flags & MS_RDONLY) 34 audit_log_format(ab, "ro"); 35 else 36 audit_log_format(ab, "rw"); 37 if (flags & MS_NOSUID) 38 audit_log_format(ab, ", nosuid"); 39 if (flags & MS_NODEV) 40 audit_log_format(ab, ", nodev"); 41 if (flags & MS_NOEXEC) 42 audit_log_format(ab, ", noexec"); 43 if (flags & MS_SYNCHRONOUS) 44 audit_log_format(ab, ", sync"); 45 if (flags & MS_REMOUNT) 46 audit_log_format(ab, ", remount"); 47 if (flags & MS_MANDLOCK) 48 audit_log_format(ab, ", mand"); 49 if (flags & MS_DIRSYNC) 50 audit_log_format(ab, ", dirsync"); 51 if (flags & MS_NOATIME) 52 audit_log_format(ab, ", noatime"); 53 if (flags & MS_NODIRATIME) 54 audit_log_format(ab, ", nodiratime"); 55 if (flags & MS_BIND) 56 audit_log_format(ab, flags & MS_REC ? ", rbind" : ", bind"); 57 if (flags & MS_MOVE) 58 audit_log_format(ab, ", move"); 59 if (flags & MS_SILENT) 60 audit_log_format(ab, ", silent"); 61 if (flags & MS_POSIXACL) 62 audit_log_format(ab, ", acl"); 63 if (flags & MS_UNBINDABLE) 64 audit_log_format(ab, flags & MS_REC ? ", runbindable" : 65 ", unbindable"); 66 if (flags & MS_PRIVATE) 67 audit_log_format(ab, flags & MS_REC ? ", rprivate" : 68 ", private"); 69 if (flags & MS_SLAVE) 70 audit_log_format(ab, flags & MS_REC ? ", rslave" : 71 ", slave"); 72 if (flags & MS_SHARED) 73 audit_log_format(ab, flags & MS_REC ? ", rshared" : 74 ", shared"); 75 if (flags & MS_RELATIME) 76 audit_log_format(ab, ", relatime"); 77 if (flags & MS_I_VERSION) 78 audit_log_format(ab, ", iversion"); 79 if (flags & MS_STRICTATIME) 80 audit_log_format(ab, ", strictatime"); 81 if (flags & MS_NOUSER) 82 audit_log_format(ab, ", nouser"); 83 } 84 85 /** 86 * audit_cb - call back for mount specific audit fields 87 * @ab: audit_buffer (NOT NULL) 88 * @va: audit struct to audit values of (NOT NULL) 89 */ 90 static void audit_cb(struct audit_buffer *ab, void *va) 91 { 92 struct common_audit_data *sa = va; 93 94 if (aad(sa)->mnt.type) { 95 audit_log_format(ab, " fstype="); 96 audit_log_untrustedstring(ab, aad(sa)->mnt.type); 97 } 98 if (aad(sa)->mnt.src_name) { 99 audit_log_format(ab, " srcname="); 100 audit_log_untrustedstring(ab, aad(sa)->mnt.src_name); 101 } 102 if (aad(sa)->mnt.trans) { 103 audit_log_format(ab, " trans="); 104 audit_log_untrustedstring(ab, aad(sa)->mnt.trans); 105 } 106 if (aad(sa)->mnt.flags) { 107 audit_log_format(ab, " flags=\""); 108 audit_mnt_flags(ab, aad(sa)->mnt.flags); 109 audit_log_format(ab, "\""); 110 } 111 if (aad(sa)->mnt.data) { 112 audit_log_format(ab, " options="); 113 audit_log_untrustedstring(ab, aad(sa)->mnt.data); 114 } 115 } 116 117 /** 118 * audit_mount - handle the auditing of mount operations 119 * @profile: the profile being enforced (NOT NULL) 120 * @op: operation being mediated (NOT NULL) 121 * @name: name of object being mediated (MAYBE NULL) 122 * @src_name: src_name of object being mediated (MAYBE_NULL) 123 * @type: type of filesystem (MAYBE_NULL) 124 * @trans: name of trans (MAYBE NULL) 125 * @flags: filesystem independent mount flags 126 * @data: filesystem mount flags 127 * @request: permissions requested 128 * @perms: the permissions computed for the request (NOT NULL) 129 * @info: extra information message (MAYBE NULL) 130 * @error: 0 if operation allowed else failure error code 131 * 132 * Returns: %0 or error on failure 133 */ 134 static int audit_mount(struct aa_profile *profile, const char *op, 135 const char *name, const char *src_name, 136 const char *type, const char *trans, 137 unsigned long flags, const void *data, u32 request, 138 struct aa_perms *perms, const char *info, int error) 139 { 140 int audit_type = AUDIT_APPARMOR_AUTO; 141 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, op); 142 143 if (likely(!error)) { 144 u32 mask = perms->audit; 145 146 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL)) 147 mask = 0xffff; 148 149 /* mask off perms that are not being force audited */ 150 request &= mask; 151 152 if (likely(!request)) 153 return 0; 154 audit_type = AUDIT_APPARMOR_AUDIT; 155 } else { 156 /* only report permissions that were denied */ 157 request = request & ~perms->allow; 158 159 if (request & perms->kill) 160 audit_type = AUDIT_APPARMOR_KILL; 161 162 /* quiet known rejects, assumes quiet and kill do not overlap */ 163 if ((request & perms->quiet) && 164 AUDIT_MODE(profile) != AUDIT_NOQUIET && 165 AUDIT_MODE(profile) != AUDIT_ALL) 166 request &= ~perms->quiet; 167 168 if (!request) 169 return error; 170 } 171 172 aad(&sa)->name = name; 173 aad(&sa)->mnt.src_name = src_name; 174 aad(&sa)->mnt.type = type; 175 aad(&sa)->mnt.trans = trans; 176 aad(&sa)->mnt.flags = flags; 177 if (data && (perms->audit & AA_AUDIT_DATA)) 178 aad(&sa)->mnt.data = data; 179 aad(&sa)->info = info; 180 aad(&sa)->error = error; 181 182 return aa_audit(audit_type, profile, &sa, audit_cb); 183 } 184 185 /** 186 * match_mnt_flags - Do an ordered match on mount flags 187 * @dfa: dfa to match against 188 * @state: state to start in 189 * @flags: mount flags to match against 190 * 191 * Mount flags are encoded as an ordered match. This is done instead of 192 * checking against a simple bitmask, to allow for logical operations 193 * on the flags. 194 * 195 * Returns: next state after flags match 196 */ 197 static unsigned int match_mnt_flags(struct aa_dfa *dfa, unsigned int state, 198 unsigned long flags) 199 { 200 unsigned int i; 201 202 for (i = 0; i <= 31 ; ++i) { 203 if ((1 << i) & flags) 204 state = aa_dfa_next(dfa, state, i + 1); 205 } 206 207 return state; 208 } 209 210 /** 211 * compute_mnt_perms - compute mount permission associated with @state 212 * @dfa: dfa to match against (NOT NULL) 213 * @state: state match finished in 214 * 215 * Returns: mount permissions 216 */ 217 static struct aa_perms compute_mnt_perms(struct aa_dfa *dfa, 218 unsigned int state) 219 { 220 struct aa_perms perms = { 221 .allow = dfa_user_allow(dfa, state), 222 .audit = dfa_user_audit(dfa, state), 223 .quiet = dfa_user_quiet(dfa, state), 224 .xindex = dfa_user_xindex(dfa, state), 225 }; 226 227 return perms; 228 } 229 230 static const char * const mnt_info_table[] = { 231 "match succeeded", 232 "failed mntpnt match", 233 "failed srcname match", 234 "failed type match", 235 "failed flags match", 236 "failed data match" 237 }; 238 239 /* 240 * Returns 0 on success else element that match failed in, this is the 241 * index into the mnt_info_table above 242 */ 243 static int do_match_mnt(struct aa_dfa *dfa, unsigned int start, 244 const char *mntpnt, const char *devname, 245 const char *type, unsigned long flags, 246 void *data, bool binary, struct aa_perms *perms) 247 { 248 unsigned int state; 249 250 AA_BUG(!dfa); 251 AA_BUG(!perms); 252 253 state = aa_dfa_match(dfa, start, mntpnt); 254 state = aa_dfa_null_transition(dfa, state); 255 if (!state) 256 return 1; 257 258 if (devname) 259 state = aa_dfa_match(dfa, state, devname); 260 state = aa_dfa_null_transition(dfa, state); 261 if (!state) 262 return 2; 263 264 if (type) 265 state = aa_dfa_match(dfa, state, type); 266 state = aa_dfa_null_transition(dfa, state); 267 if (!state) 268 return 3; 269 270 state = match_mnt_flags(dfa, state, flags); 271 if (!state) 272 return 4; 273 *perms = compute_mnt_perms(dfa, state); 274 if (perms->allow & AA_MAY_MOUNT) 275 return 0; 276 277 /* only match data if not binary and the DFA flags data is expected */ 278 if (data && !binary && (perms->allow & AA_MNT_CONT_MATCH)) { 279 state = aa_dfa_null_transition(dfa, state); 280 if (!state) 281 return 4; 282 283 state = aa_dfa_match(dfa, state, data); 284 if (!state) 285 return 5; 286 *perms = compute_mnt_perms(dfa, state); 287 if (perms->allow & AA_MAY_MOUNT) 288 return 0; 289 } 290 291 /* failed at end of flags match */ 292 return 4; 293 } 294 295 296 static int path_flags(struct aa_profile *profile, const struct path *path) 297 { 298 AA_BUG(!profile); 299 AA_BUG(!path); 300 301 return profile->path_flags | 302 (S_ISDIR(path->dentry->d_inode->i_mode) ? PATH_IS_DIR : 0); 303 } 304 305 /** 306 * match_mnt_path_str - handle path matching for mount 307 * @profile: the confining profile 308 * @mntpath: for the mntpnt (NOT NULL) 309 * @buffer: buffer to be used to lookup mntpath 310 * @devnme: string for the devname/src_name (MAY BE NULL OR ERRPTR) 311 * @type: string for the dev type (MAYBE NULL) 312 * @flags: mount flags to match 313 * @data: fs mount data (MAYBE NULL) 314 * @binary: whether @data is binary 315 * @devinfo: error str if (IS_ERR(@devname)) 316 * 317 * Returns: 0 on success else error 318 */ 319 static int match_mnt_path_str(struct aa_profile *profile, 320 const struct path *mntpath, char *buffer, 321 const char *devname, const char *type, 322 unsigned long flags, void *data, bool binary, 323 const char *devinfo) 324 { 325 struct aa_perms perms = { }; 326 const char *mntpnt = NULL, *info = NULL; 327 int pos, error; 328 329 AA_BUG(!profile); 330 AA_BUG(!mntpath); 331 AA_BUG(!buffer); 332 333 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) 334 return 0; 335 336 error = aa_path_name(mntpath, path_flags(profile, mntpath), buffer, 337 &mntpnt, &info, profile->disconnected); 338 if (error) 339 goto audit; 340 if (IS_ERR(devname)) { 341 error = PTR_ERR(devname); 342 devname = NULL; 343 info = devinfo; 344 goto audit; 345 } 346 347 error = -EACCES; 348 pos = do_match_mnt(profile->policy.dfa, 349 profile->policy.start[AA_CLASS_MOUNT], 350 mntpnt, devname, type, flags, data, binary, &perms); 351 if (pos) { 352 info = mnt_info_table[pos]; 353 goto audit; 354 } 355 error = 0; 356 357 audit: 358 return audit_mount(profile, OP_MOUNT, mntpnt, devname, type, NULL, 359 flags, data, AA_MAY_MOUNT, &perms, info, error); 360 } 361 362 /** 363 * match_mnt - handle path matching for mount 364 * @profile: the confining profile 365 * @mntpath: for the mntpnt (NOT NULL) 366 * @buffer: buffer to be used to lookup mntpath 367 * @devpath: path devname/src_name (MAYBE NULL) 368 * @devbuffer: buffer to be used to lookup devname/src_name 369 * @type: string for the dev type (MAYBE NULL) 370 * @flags: mount flags to match 371 * @data: fs mount data (MAYBE NULL) 372 * @binary: whether @data is binary 373 * 374 * Returns: 0 on success else error 375 */ 376 static int match_mnt(struct aa_profile *profile, const struct path *path, 377 char *buffer, struct path *devpath, char *devbuffer, 378 const char *type, unsigned long flags, void *data, 379 bool binary) 380 { 381 const char *devname = NULL, *info = NULL; 382 int error = -EACCES; 383 384 AA_BUG(!profile); 385 AA_BUG(devpath && !devbuffer); 386 387 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) 388 return 0; 389 390 if (devpath) { 391 error = aa_path_name(devpath, path_flags(profile, devpath), 392 devbuffer, &devname, &info, 393 profile->disconnected); 394 if (error) 395 devname = ERR_PTR(error); 396 } 397 398 return match_mnt_path_str(profile, path, buffer, devname, type, flags, 399 data, binary, info); 400 } 401 402 int aa_remount(struct aa_label *label, const struct path *path, 403 unsigned long flags, void *data) 404 { 405 struct aa_profile *profile; 406 char *buffer = NULL; 407 bool binary; 408 int error; 409 410 AA_BUG(!label); 411 AA_BUG(!path); 412 413 binary = path->dentry->d_sb->s_type->fs_flags & FS_BINARY_MOUNTDATA; 414 415 get_buffers(buffer); 416 error = fn_for_each_confined(label, profile, 417 match_mnt(profile, path, buffer, NULL, NULL, NULL, 418 flags, data, binary)); 419 put_buffers(buffer); 420 421 return error; 422 } 423 424 int aa_bind_mount(struct aa_label *label, const struct path *path, 425 const char *dev_name, unsigned long flags) 426 { 427 struct aa_profile *profile; 428 char *buffer = NULL, *old_buffer = NULL; 429 struct path old_path; 430 int error; 431 432 AA_BUG(!label); 433 AA_BUG(!path); 434 435 if (!dev_name || !*dev_name) 436 return -EINVAL; 437 438 flags &= MS_REC | MS_BIND; 439 440 error = kern_path(dev_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); 441 if (error) 442 return error; 443 444 get_buffers(buffer, old_buffer); 445 error = fn_for_each_confined(label, profile, 446 match_mnt(profile, path, buffer, &old_path, old_buffer, 447 NULL, flags, NULL, false)); 448 put_buffers(buffer, old_buffer); 449 path_put(&old_path); 450 451 return error; 452 } 453 454 int aa_mount_change_type(struct aa_label *label, const struct path *path, 455 unsigned long flags) 456 { 457 struct aa_profile *profile; 458 char *buffer = NULL; 459 int error; 460 461 AA_BUG(!label); 462 AA_BUG(!path); 463 464 /* These are the flags allowed by do_change_type() */ 465 flags &= (MS_REC | MS_SILENT | MS_SHARED | MS_PRIVATE | MS_SLAVE | 466 MS_UNBINDABLE); 467 468 get_buffers(buffer); 469 error = fn_for_each_confined(label, profile, 470 match_mnt(profile, path, buffer, NULL, NULL, NULL, 471 flags, NULL, false)); 472 put_buffers(buffer); 473 474 return error; 475 } 476 477 int aa_move_mount(struct aa_label *label, const struct path *path, 478 const char *orig_name) 479 { 480 struct aa_profile *profile; 481 char *buffer = NULL, *old_buffer = NULL; 482 struct path old_path; 483 int error; 484 485 AA_BUG(!label); 486 AA_BUG(!path); 487 488 if (!orig_name || !*orig_name) 489 return -EINVAL; 490 491 error = kern_path(orig_name, LOOKUP_FOLLOW, &old_path); 492 if (error) 493 return error; 494 495 get_buffers(buffer, old_buffer); 496 error = fn_for_each_confined(label, profile, 497 match_mnt(profile, path, buffer, &old_path, old_buffer, 498 NULL, MS_MOVE, NULL, false)); 499 put_buffers(buffer, old_buffer); 500 path_put(&old_path); 501 502 return error; 503 } 504 505 int aa_new_mount(struct aa_label *label, const char *dev_name, 506 const struct path *path, const char *type, unsigned long flags, 507 void *data) 508 { 509 struct aa_profile *profile; 510 char *buffer = NULL, *dev_buffer = NULL; 511 bool binary = true; 512 int error; 513 int requires_dev = 0; 514 struct path tmp_path, *dev_path = NULL; 515 516 AA_BUG(!label); 517 AA_BUG(!path); 518 519 if (type) { 520 struct file_system_type *fstype; 521 522 fstype = get_fs_type(type); 523 if (!fstype) 524 return -ENODEV; 525 binary = fstype->fs_flags & FS_BINARY_MOUNTDATA; 526 requires_dev = fstype->fs_flags & FS_REQUIRES_DEV; 527 put_filesystem(fstype); 528 529 if (requires_dev) { 530 if (!dev_name || !*dev_name) 531 return -ENOENT; 532 533 error = kern_path(dev_name, LOOKUP_FOLLOW, &tmp_path); 534 if (error) 535 return error; 536 dev_path = &tmp_path; 537 } 538 } 539 540 get_buffers(buffer, dev_buffer); 541 if (dev_path) { 542 error = fn_for_each_confined(label, profile, 543 match_mnt(profile, path, buffer, dev_path, dev_buffer, 544 type, flags, data, binary)); 545 } else { 546 error = fn_for_each_confined(label, profile, 547 match_mnt_path_str(profile, path, buffer, dev_name, 548 type, flags, data, binary, NULL)); 549 } 550 put_buffers(buffer, dev_buffer); 551 if (dev_path) 552 path_put(dev_path); 553 554 return error; 555 } 556 557 static int profile_umount(struct aa_profile *profile, struct path *path, 558 char *buffer) 559 { 560 struct aa_perms perms = { }; 561 const char *name = NULL, *info = NULL; 562 unsigned int state; 563 int error; 564 565 AA_BUG(!profile); 566 AA_BUG(!path); 567 568 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) 569 return 0; 570 571 error = aa_path_name(path, path_flags(profile, path), buffer, &name, 572 &info, profile->disconnected); 573 if (error) 574 goto audit; 575 576 state = aa_dfa_match(profile->policy.dfa, 577 profile->policy.start[AA_CLASS_MOUNT], 578 name); 579 perms = compute_mnt_perms(profile->policy.dfa, state); 580 if (AA_MAY_UMOUNT & ~perms.allow) 581 error = -EACCES; 582 583 audit: 584 return audit_mount(profile, OP_UMOUNT, name, NULL, NULL, NULL, 0, NULL, 585 AA_MAY_UMOUNT, &perms, info, error); 586 } 587 588 int aa_umount(struct aa_label *label, struct vfsmount *mnt, int flags) 589 { 590 struct aa_profile *profile; 591 char *buffer = NULL; 592 int error; 593 struct path path = { .mnt = mnt, .dentry = mnt->mnt_root }; 594 595 AA_BUG(!label); 596 AA_BUG(!mnt); 597 598 get_buffers(buffer); 599 error = fn_for_each_confined(label, profile, 600 profile_umount(profile, &path, buffer)); 601 put_buffers(buffer); 602 603 return error; 604 } 605 606 /* helper fn for transition on pivotroot 607 * 608 * Returns: label for transition or ERR_PTR. Does not return NULL 609 */ 610 static struct aa_label *build_pivotroot(struct aa_profile *profile, 611 const struct path *new_path, 612 char *new_buffer, 613 const struct path *old_path, 614 char *old_buffer) 615 { 616 const char *old_name, *new_name = NULL, *info = NULL; 617 const char *trans_name = NULL; 618 struct aa_perms perms = { }; 619 unsigned int state; 620 int error; 621 622 AA_BUG(!profile); 623 AA_BUG(!new_path); 624 AA_BUG(!old_path); 625 626 if (profile_unconfined(profile) || 627 !PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) 628 return aa_get_newest_label(&profile->label); 629 630 error = aa_path_name(old_path, path_flags(profile, old_path), 631 old_buffer, &old_name, &info, 632 profile->disconnected); 633 if (error) 634 goto audit; 635 error = aa_path_name(new_path, path_flags(profile, new_path), 636 new_buffer, &new_name, &info, 637 profile->disconnected); 638 if (error) 639 goto audit; 640 641 error = -EACCES; 642 state = aa_dfa_match(profile->policy.dfa, 643 profile->policy.start[AA_CLASS_MOUNT], 644 new_name); 645 state = aa_dfa_null_transition(profile->policy.dfa, state); 646 state = aa_dfa_match(profile->policy.dfa, state, old_name); 647 perms = compute_mnt_perms(profile->policy.dfa, state); 648 649 if (AA_MAY_PIVOTROOT & perms.allow) 650 error = 0; 651 652 audit: 653 error = audit_mount(profile, OP_PIVOTROOT, new_name, old_name, 654 NULL, trans_name, 0, NULL, AA_MAY_PIVOTROOT, 655 &perms, info, error); 656 if (error) 657 return ERR_PTR(error); 658 659 return aa_get_newest_label(&profile->label); 660 } 661 662 int aa_pivotroot(struct aa_label *label, const struct path *old_path, 663 const struct path *new_path) 664 { 665 struct aa_profile *profile; 666 struct aa_label *target = NULL; 667 char *old_buffer = NULL, *new_buffer = NULL, *info = NULL; 668 int error; 669 670 AA_BUG(!label); 671 AA_BUG(!old_path); 672 AA_BUG(!new_path); 673 674 get_buffers(old_buffer, new_buffer); 675 target = fn_label_build(label, profile, GFP_ATOMIC, 676 build_pivotroot(profile, new_path, new_buffer, 677 old_path, old_buffer)); 678 if (!target) { 679 info = "label build failed"; 680 error = -ENOMEM; 681 goto fail; 682 } else if (!IS_ERR(target)) { 683 error = aa_replace_current_label(target); 684 if (error) { 685 /* TODO: audit target */ 686 aa_put_label(target); 687 goto out; 688 } 689 } else 690 /* already audited error */ 691 error = PTR_ERR(target); 692 out: 693 put_buffers(old_buffer, new_buffer); 694 695 return error; 696 697 fail: 698 /* TODO: add back in auditing of new_name and old_name */ 699 error = fn_for_each(label, profile, 700 audit_mount(profile, OP_PIVOTROOT, NULL /*new_name */, 701 NULL /* old_name */, 702 NULL, NULL, 703 0, NULL, AA_MAY_PIVOTROOT, &nullperms, info, 704 error)); 705 goto out; 706 } 707