1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/fanotify.h> 3 #include <linux/fcntl.h> 4 #include <linux/fdtable.h> 5 #include <linux/file.h> 6 #include <linux/fs.h> 7 #include <linux/anon_inodes.h> 8 #include <linux/fsnotify_backend.h> 9 #include <linux/init.h> 10 #include <linux/mount.h> 11 #include <linux/namei.h> 12 #include <linux/poll.h> 13 #include <linux/security.h> 14 #include <linux/syscalls.h> 15 #include <linux/slab.h> 16 #include <linux/types.h> 17 #include <linux/uaccess.h> 18 #include <linux/compat.h> 19 #include <linux/sched/signal.h> 20 #include <linux/memcontrol.h> 21 #include <linux/statfs.h> 22 #include <linux/exportfs.h> 23 24 #include <asm/ioctls.h> 25 26 #include "../../mount.h" 27 #include "../fdinfo.h" 28 #include "fanotify.h" 29 30 #define FANOTIFY_DEFAULT_MAX_EVENTS 16384 31 #define FANOTIFY_OLD_DEFAULT_MAX_MARKS 8192 32 #define FANOTIFY_DEFAULT_MAX_GROUPS 128 33 #define FANOTIFY_DEFAULT_FEE_POOL_SIZE 32 34 35 /* 36 * Legacy fanotify marks limits (8192) is per group and we introduced a tunable 37 * limit of marks per user, similar to inotify. Effectively, the legacy limit 38 * of fanotify marks per user is <max marks per group> * <max groups per user>. 39 * This default limit (1M) also happens to match the increased limit of inotify 40 * max_user_watches since v5.10. 41 */ 42 #define FANOTIFY_DEFAULT_MAX_USER_MARKS \ 43 (FANOTIFY_OLD_DEFAULT_MAX_MARKS * FANOTIFY_DEFAULT_MAX_GROUPS) 44 45 /* 46 * Most of the memory cost of adding an inode mark is pinning the marked inode. 47 * The size of the filesystem inode struct is not uniform across filesystems, 48 * so double the size of a VFS inode is used as a conservative approximation. 49 */ 50 #define INODE_MARK_COST (2 * sizeof(struct inode)) 51 52 /* configurable via /proc/sys/fs/fanotify/ */ 53 static int fanotify_max_queued_events __read_mostly; 54 55 #ifdef CONFIG_SYSCTL 56 57 #include <linux/sysctl.h> 58 59 static long ft_zero = 0; 60 static long ft_int_max = INT_MAX; 61 62 static struct ctl_table fanotify_table[] = { 63 { 64 .procname = "max_user_groups", 65 .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS], 66 .maxlen = sizeof(long), 67 .mode = 0644, 68 .proc_handler = proc_doulongvec_minmax, 69 .extra1 = &ft_zero, 70 .extra2 = &ft_int_max, 71 }, 72 { 73 .procname = "max_user_marks", 74 .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS], 75 .maxlen = sizeof(long), 76 .mode = 0644, 77 .proc_handler = proc_doulongvec_minmax, 78 .extra1 = &ft_zero, 79 .extra2 = &ft_int_max, 80 }, 81 { 82 .procname = "max_queued_events", 83 .data = &fanotify_max_queued_events, 84 .maxlen = sizeof(int), 85 .mode = 0644, 86 .proc_handler = proc_dointvec_minmax, 87 .extra1 = SYSCTL_ZERO 88 }, 89 { } 90 }; 91 92 static void __init fanotify_sysctls_init(void) 93 { 94 register_sysctl("fs/fanotify", fanotify_table); 95 } 96 #else 97 #define fanotify_sysctls_init() do { } while (0) 98 #endif /* CONFIG_SYSCTL */ 99 100 /* 101 * All flags that may be specified in parameter event_f_flags of fanotify_init. 102 * 103 * Internal and external open flags are stored together in field f_flags of 104 * struct file. Only external open flags shall be allowed in event_f_flags. 105 * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be 106 * excluded. 107 */ 108 #define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \ 109 O_ACCMODE | O_APPEND | O_NONBLOCK | \ 110 __O_SYNC | O_DSYNC | O_CLOEXEC | \ 111 O_LARGEFILE | O_NOATIME ) 112 113 extern const struct fsnotify_ops fanotify_fsnotify_ops; 114 115 struct kmem_cache *fanotify_mark_cache __read_mostly; 116 struct kmem_cache *fanotify_fid_event_cachep __read_mostly; 117 struct kmem_cache *fanotify_path_event_cachep __read_mostly; 118 struct kmem_cache *fanotify_perm_event_cachep __read_mostly; 119 120 #define FANOTIFY_EVENT_ALIGN 4 121 #define FANOTIFY_FID_INFO_HDR_LEN \ 122 (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle)) 123 #define FANOTIFY_PIDFD_INFO_HDR_LEN \ 124 sizeof(struct fanotify_event_info_pidfd) 125 #define FANOTIFY_ERROR_INFO_LEN \ 126 (sizeof(struct fanotify_event_info_error)) 127 128 static int fanotify_fid_info_len(int fh_len, int name_len) 129 { 130 int info_len = fh_len; 131 132 if (name_len) 133 info_len += name_len + 1; 134 135 return roundup(FANOTIFY_FID_INFO_HDR_LEN + info_len, 136 FANOTIFY_EVENT_ALIGN); 137 } 138 139 /* FAN_RENAME may have one or two dir+name info records */ 140 static int fanotify_dir_name_info_len(struct fanotify_event *event) 141 { 142 struct fanotify_info *info = fanotify_event_info(event); 143 int dir_fh_len = fanotify_event_dir_fh_len(event); 144 int dir2_fh_len = fanotify_event_dir2_fh_len(event); 145 int info_len = 0; 146 147 if (dir_fh_len) 148 info_len += fanotify_fid_info_len(dir_fh_len, 149 info->name_len); 150 if (dir2_fh_len) 151 info_len += fanotify_fid_info_len(dir2_fh_len, 152 info->name2_len); 153 154 return info_len; 155 } 156 157 static size_t fanotify_event_len(unsigned int info_mode, 158 struct fanotify_event *event) 159 { 160 size_t event_len = FAN_EVENT_METADATA_LEN; 161 int fh_len; 162 int dot_len = 0; 163 164 if (!info_mode) 165 return event_len; 166 167 if (fanotify_is_error_event(event->mask)) 168 event_len += FANOTIFY_ERROR_INFO_LEN; 169 170 if (fanotify_event_has_any_dir_fh(event)) { 171 event_len += fanotify_dir_name_info_len(event); 172 } else if ((info_mode & FAN_REPORT_NAME) && 173 (event->mask & FAN_ONDIR)) { 174 /* 175 * With group flag FAN_REPORT_NAME, if name was not recorded in 176 * event on a directory, we will report the name ".". 177 */ 178 dot_len = 1; 179 } 180 181 if (info_mode & FAN_REPORT_PIDFD) 182 event_len += FANOTIFY_PIDFD_INFO_HDR_LEN; 183 184 if (fanotify_event_has_object_fh(event)) { 185 fh_len = fanotify_event_object_fh_len(event); 186 event_len += fanotify_fid_info_len(fh_len, dot_len); 187 } 188 189 return event_len; 190 } 191 192 /* 193 * Remove an hashed event from merge hash table. 194 */ 195 static void fanotify_unhash_event(struct fsnotify_group *group, 196 struct fanotify_event *event) 197 { 198 assert_spin_locked(&group->notification_lock); 199 200 pr_debug("%s: group=%p event=%p bucket=%u\n", __func__, 201 group, event, fanotify_event_hash_bucket(group, event)); 202 203 if (WARN_ON_ONCE(hlist_unhashed(&event->merge_list))) 204 return; 205 206 hlist_del_init(&event->merge_list); 207 } 208 209 /* 210 * Get an fanotify notification event if one exists and is small 211 * enough to fit in "count". Return an error pointer if the count 212 * is not large enough. When permission event is dequeued, its state is 213 * updated accordingly. 214 */ 215 static struct fanotify_event *get_one_event(struct fsnotify_group *group, 216 size_t count) 217 { 218 size_t event_size; 219 struct fanotify_event *event = NULL; 220 struct fsnotify_event *fsn_event; 221 unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); 222 223 pr_debug("%s: group=%p count=%zd\n", __func__, group, count); 224 225 spin_lock(&group->notification_lock); 226 fsn_event = fsnotify_peek_first_event(group); 227 if (!fsn_event) 228 goto out; 229 230 event = FANOTIFY_E(fsn_event); 231 event_size = fanotify_event_len(info_mode, event); 232 233 if (event_size > count) { 234 event = ERR_PTR(-EINVAL); 235 goto out; 236 } 237 238 /* 239 * Held the notification_lock the whole time, so this is the 240 * same event we peeked above. 241 */ 242 fsnotify_remove_first_event(group); 243 if (fanotify_is_perm_event(event->mask)) 244 FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED; 245 if (fanotify_is_hashed_event(event->mask)) 246 fanotify_unhash_event(group, event); 247 out: 248 spin_unlock(&group->notification_lock); 249 return event; 250 } 251 252 static int create_fd(struct fsnotify_group *group, struct path *path, 253 struct file **file) 254 { 255 int client_fd; 256 struct file *new_file; 257 258 client_fd = get_unused_fd_flags(group->fanotify_data.f_flags); 259 if (client_fd < 0) 260 return client_fd; 261 262 /* 263 * we need a new file handle for the userspace program so it can read even if it was 264 * originally opened O_WRONLY. 265 */ 266 new_file = dentry_open(path, 267 group->fanotify_data.f_flags | __FMODE_NONOTIFY, 268 current_cred()); 269 if (IS_ERR(new_file)) { 270 /* 271 * we still send an event even if we can't open the file. this 272 * can happen when say tasks are gone and we try to open their 273 * /proc files or we try to open a WRONLY file like in sysfs 274 * we just send the errno to userspace since there isn't much 275 * else we can do. 276 */ 277 put_unused_fd(client_fd); 278 client_fd = PTR_ERR(new_file); 279 } else { 280 *file = new_file; 281 } 282 283 return client_fd; 284 } 285 286 /* 287 * Finish processing of permission event by setting it to ANSWERED state and 288 * drop group->notification_lock. 289 */ 290 static void finish_permission_event(struct fsnotify_group *group, 291 struct fanotify_perm_event *event, 292 unsigned int response) 293 __releases(&group->notification_lock) 294 { 295 bool destroy = false; 296 297 assert_spin_locked(&group->notification_lock); 298 event->response = response; 299 if (event->state == FAN_EVENT_CANCELED) 300 destroy = true; 301 else 302 event->state = FAN_EVENT_ANSWERED; 303 spin_unlock(&group->notification_lock); 304 if (destroy) 305 fsnotify_destroy_event(group, &event->fae.fse); 306 } 307 308 static int process_access_response(struct fsnotify_group *group, 309 struct fanotify_response *response_struct) 310 { 311 struct fanotify_perm_event *event; 312 int fd = response_struct->fd; 313 int response = response_struct->response; 314 315 pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group, 316 fd, response); 317 /* 318 * make sure the response is valid, if invalid we do nothing and either 319 * userspace can send a valid response or we will clean it up after the 320 * timeout 321 */ 322 switch (response & ~FAN_AUDIT) { 323 case FAN_ALLOW: 324 case FAN_DENY: 325 break; 326 default: 327 return -EINVAL; 328 } 329 330 if (fd < 0) 331 return -EINVAL; 332 333 if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT)) 334 return -EINVAL; 335 336 spin_lock(&group->notification_lock); 337 list_for_each_entry(event, &group->fanotify_data.access_list, 338 fae.fse.list) { 339 if (event->fd != fd) 340 continue; 341 342 list_del_init(&event->fae.fse.list); 343 finish_permission_event(group, event, response); 344 wake_up(&group->fanotify_data.access_waitq); 345 return 0; 346 } 347 spin_unlock(&group->notification_lock); 348 349 return -ENOENT; 350 } 351 352 static size_t copy_error_info_to_user(struct fanotify_event *event, 353 char __user *buf, int count) 354 { 355 struct fanotify_event_info_error info = { }; 356 struct fanotify_error_event *fee = FANOTIFY_EE(event); 357 358 info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR; 359 info.hdr.len = FANOTIFY_ERROR_INFO_LEN; 360 361 if (WARN_ON(count < info.hdr.len)) 362 return -EFAULT; 363 364 info.error = fee->error; 365 info.error_count = fee->err_count; 366 367 if (copy_to_user(buf, &info, sizeof(info))) 368 return -EFAULT; 369 370 return info.hdr.len; 371 } 372 373 static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh, 374 int info_type, const char *name, 375 size_t name_len, 376 char __user *buf, size_t count) 377 { 378 struct fanotify_event_info_fid info = { }; 379 struct file_handle handle = { }; 380 unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf; 381 size_t fh_len = fh ? fh->len : 0; 382 size_t info_len = fanotify_fid_info_len(fh_len, name_len); 383 size_t len = info_len; 384 385 pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n", 386 __func__, fh_len, name_len, info_len, count); 387 388 if (WARN_ON_ONCE(len < sizeof(info) || len > count)) 389 return -EFAULT; 390 391 /* 392 * Copy event info fid header followed by variable sized file handle 393 * and optionally followed by variable sized filename. 394 */ 395 switch (info_type) { 396 case FAN_EVENT_INFO_TYPE_FID: 397 case FAN_EVENT_INFO_TYPE_DFID: 398 if (WARN_ON_ONCE(name_len)) 399 return -EFAULT; 400 break; 401 case FAN_EVENT_INFO_TYPE_DFID_NAME: 402 case FAN_EVENT_INFO_TYPE_OLD_DFID_NAME: 403 case FAN_EVENT_INFO_TYPE_NEW_DFID_NAME: 404 if (WARN_ON_ONCE(!name || !name_len)) 405 return -EFAULT; 406 break; 407 default: 408 return -EFAULT; 409 } 410 411 info.hdr.info_type = info_type; 412 info.hdr.len = len; 413 info.fsid = *fsid; 414 if (copy_to_user(buf, &info, sizeof(info))) 415 return -EFAULT; 416 417 buf += sizeof(info); 418 len -= sizeof(info); 419 if (WARN_ON_ONCE(len < sizeof(handle))) 420 return -EFAULT; 421 422 handle.handle_type = fh->type; 423 handle.handle_bytes = fh_len; 424 425 /* Mangle handle_type for bad file_handle */ 426 if (!fh_len) 427 handle.handle_type = FILEID_INVALID; 428 429 if (copy_to_user(buf, &handle, sizeof(handle))) 430 return -EFAULT; 431 432 buf += sizeof(handle); 433 len -= sizeof(handle); 434 if (WARN_ON_ONCE(len < fh_len)) 435 return -EFAULT; 436 437 /* 438 * For an inline fh and inline file name, copy through stack to exclude 439 * the copy from usercopy hardening protections. 440 */ 441 fh_buf = fanotify_fh_buf(fh); 442 if (fh_len <= FANOTIFY_INLINE_FH_LEN) { 443 memcpy(bounce, fh_buf, fh_len); 444 fh_buf = bounce; 445 } 446 if (copy_to_user(buf, fh_buf, fh_len)) 447 return -EFAULT; 448 449 buf += fh_len; 450 len -= fh_len; 451 452 if (name_len) { 453 /* Copy the filename with terminating null */ 454 name_len++; 455 if (WARN_ON_ONCE(len < name_len)) 456 return -EFAULT; 457 458 if (copy_to_user(buf, name, name_len)) 459 return -EFAULT; 460 461 buf += name_len; 462 len -= name_len; 463 } 464 465 /* Pad with 0's */ 466 WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN); 467 if (len > 0 && clear_user(buf, len)) 468 return -EFAULT; 469 470 return info_len; 471 } 472 473 static int copy_pidfd_info_to_user(int pidfd, 474 char __user *buf, 475 size_t count) 476 { 477 struct fanotify_event_info_pidfd info = { }; 478 size_t info_len = FANOTIFY_PIDFD_INFO_HDR_LEN; 479 480 if (WARN_ON_ONCE(info_len > count)) 481 return -EFAULT; 482 483 info.hdr.info_type = FAN_EVENT_INFO_TYPE_PIDFD; 484 info.hdr.len = info_len; 485 info.pidfd = pidfd; 486 487 if (copy_to_user(buf, &info, info_len)) 488 return -EFAULT; 489 490 return info_len; 491 } 492 493 static int copy_info_records_to_user(struct fanotify_event *event, 494 struct fanotify_info *info, 495 unsigned int info_mode, int pidfd, 496 char __user *buf, size_t count) 497 { 498 int ret, total_bytes = 0, info_type = 0; 499 unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS; 500 unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; 501 502 /* 503 * Event info records order is as follows: 504 * 1. dir fid + name 505 * 2. (optional) new dir fid + new name 506 * 3. (optional) child fid 507 */ 508 if (fanotify_event_has_dir_fh(event)) { 509 info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME : 510 FAN_EVENT_INFO_TYPE_DFID; 511 512 /* FAN_RENAME uses special info types */ 513 if (event->mask & FAN_RENAME) 514 info_type = FAN_EVENT_INFO_TYPE_OLD_DFID_NAME; 515 516 ret = copy_fid_info_to_user(fanotify_event_fsid(event), 517 fanotify_info_dir_fh(info), 518 info_type, 519 fanotify_info_name(info), 520 info->name_len, buf, count); 521 if (ret < 0) 522 return ret; 523 524 buf += ret; 525 count -= ret; 526 total_bytes += ret; 527 } 528 529 /* New dir fid+name may be reported in addition to old dir fid+name */ 530 if (fanotify_event_has_dir2_fh(event)) { 531 info_type = FAN_EVENT_INFO_TYPE_NEW_DFID_NAME; 532 ret = copy_fid_info_to_user(fanotify_event_fsid(event), 533 fanotify_info_dir2_fh(info), 534 info_type, 535 fanotify_info_name2(info), 536 info->name2_len, buf, count); 537 if (ret < 0) 538 return ret; 539 540 buf += ret; 541 count -= ret; 542 total_bytes += ret; 543 } 544 545 if (fanotify_event_has_object_fh(event)) { 546 const char *dot = NULL; 547 int dot_len = 0; 548 549 if (fid_mode == FAN_REPORT_FID || info_type) { 550 /* 551 * With only group flag FAN_REPORT_FID only type FID is 552 * reported. Second info record type is always FID. 553 */ 554 info_type = FAN_EVENT_INFO_TYPE_FID; 555 } else if ((fid_mode & FAN_REPORT_NAME) && 556 (event->mask & FAN_ONDIR)) { 557 /* 558 * With group flag FAN_REPORT_NAME, if name was not 559 * recorded in an event on a directory, report the name 560 * "." with info type DFID_NAME. 561 */ 562 info_type = FAN_EVENT_INFO_TYPE_DFID_NAME; 563 dot = "."; 564 dot_len = 1; 565 } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) || 566 (event->mask & FAN_ONDIR)) { 567 /* 568 * With group flag FAN_REPORT_DIR_FID, a single info 569 * record has type DFID for directory entry modification 570 * event and for event on a directory. 571 */ 572 info_type = FAN_EVENT_INFO_TYPE_DFID; 573 } else { 574 /* 575 * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID, 576 * a single info record has type FID for event on a 577 * non-directory, when there is no directory to report. 578 * For example, on FAN_DELETE_SELF event. 579 */ 580 info_type = FAN_EVENT_INFO_TYPE_FID; 581 } 582 583 ret = copy_fid_info_to_user(fanotify_event_fsid(event), 584 fanotify_event_object_fh(event), 585 info_type, dot, dot_len, 586 buf, count); 587 if (ret < 0) 588 return ret; 589 590 buf += ret; 591 count -= ret; 592 total_bytes += ret; 593 } 594 595 if (pidfd_mode) { 596 ret = copy_pidfd_info_to_user(pidfd, buf, count); 597 if (ret < 0) 598 return ret; 599 600 buf += ret; 601 count -= ret; 602 total_bytes += ret; 603 } 604 605 if (fanotify_is_error_event(event->mask)) { 606 ret = copy_error_info_to_user(event, buf, count); 607 if (ret < 0) 608 return ret; 609 buf += ret; 610 count -= ret; 611 total_bytes += ret; 612 } 613 614 return total_bytes; 615 } 616 617 static ssize_t copy_event_to_user(struct fsnotify_group *group, 618 struct fanotify_event *event, 619 char __user *buf, size_t count) 620 { 621 struct fanotify_event_metadata metadata; 622 struct path *path = fanotify_event_path(event); 623 struct fanotify_info *info = fanotify_event_info(event); 624 unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); 625 unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; 626 struct file *f = NULL; 627 int ret, pidfd = FAN_NOPIDFD, fd = FAN_NOFD; 628 629 pr_debug("%s: group=%p event=%p\n", __func__, group, event); 630 631 metadata.event_len = fanotify_event_len(info_mode, event); 632 metadata.metadata_len = FAN_EVENT_METADATA_LEN; 633 metadata.vers = FANOTIFY_METADATA_VERSION; 634 metadata.reserved = 0; 635 metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS; 636 metadata.pid = pid_vnr(event->pid); 637 /* 638 * For an unprivileged listener, event->pid can be used to identify the 639 * events generated by the listener process itself, without disclosing 640 * the pids of other processes. 641 */ 642 if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && 643 task_tgid(current) != event->pid) 644 metadata.pid = 0; 645 646 /* 647 * For now, fid mode is required for an unprivileged listener and 648 * fid mode does not report fd in events. Keep this check anyway 649 * for safety in case fid mode requirement is relaxed in the future 650 * to allow unprivileged listener to get events with no fd and no fid. 651 */ 652 if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && 653 path && path->mnt && path->dentry) { 654 fd = create_fd(group, path, &f); 655 if (fd < 0) 656 return fd; 657 } 658 metadata.fd = fd; 659 660 if (pidfd_mode) { 661 /* 662 * Complain if the FAN_REPORT_PIDFD and FAN_REPORT_TID mutual 663 * exclusion is ever lifted. At the time of incoporating pidfd 664 * support within fanotify, the pidfd API only supported the 665 * creation of pidfds for thread-group leaders. 666 */ 667 WARN_ON_ONCE(FAN_GROUP_FLAG(group, FAN_REPORT_TID)); 668 669 /* 670 * The PIDTYPE_TGID check for an event->pid is performed 671 * preemptively in an attempt to catch out cases where the event 672 * listener reads events after the event generating process has 673 * already terminated. Report FAN_NOPIDFD to the event listener 674 * in those cases, with all other pidfd creation errors being 675 * reported as FAN_EPIDFD. 676 */ 677 if (metadata.pid == 0 || 678 !pid_has_task(event->pid, PIDTYPE_TGID)) { 679 pidfd = FAN_NOPIDFD; 680 } else { 681 pidfd = pidfd_create(event->pid, 0); 682 if (pidfd < 0) 683 pidfd = FAN_EPIDFD; 684 } 685 } 686 687 ret = -EFAULT; 688 /* 689 * Sanity check copy size in case get_one_event() and 690 * event_len sizes ever get out of sync. 691 */ 692 if (WARN_ON_ONCE(metadata.event_len > count)) 693 goto out_close_fd; 694 695 if (copy_to_user(buf, &metadata, FAN_EVENT_METADATA_LEN)) 696 goto out_close_fd; 697 698 buf += FAN_EVENT_METADATA_LEN; 699 count -= FAN_EVENT_METADATA_LEN; 700 701 if (fanotify_is_perm_event(event->mask)) 702 FANOTIFY_PERM(event)->fd = fd; 703 704 if (info_mode) { 705 ret = copy_info_records_to_user(event, info, info_mode, pidfd, 706 buf, count); 707 if (ret < 0) 708 goto out_close_fd; 709 } 710 711 if (f) 712 fd_install(fd, f); 713 714 return metadata.event_len; 715 716 out_close_fd: 717 if (fd != FAN_NOFD) { 718 put_unused_fd(fd); 719 fput(f); 720 } 721 722 if (pidfd >= 0) 723 close_fd(pidfd); 724 725 return ret; 726 } 727 728 /* intofiy userspace file descriptor functions */ 729 static __poll_t fanotify_poll(struct file *file, poll_table *wait) 730 { 731 struct fsnotify_group *group = file->private_data; 732 __poll_t ret = 0; 733 734 poll_wait(file, &group->notification_waitq, wait); 735 spin_lock(&group->notification_lock); 736 if (!fsnotify_notify_queue_is_empty(group)) 737 ret = EPOLLIN | EPOLLRDNORM; 738 spin_unlock(&group->notification_lock); 739 740 return ret; 741 } 742 743 static ssize_t fanotify_read(struct file *file, char __user *buf, 744 size_t count, loff_t *pos) 745 { 746 struct fsnotify_group *group; 747 struct fanotify_event *event; 748 char __user *start; 749 int ret; 750 DEFINE_WAIT_FUNC(wait, woken_wake_function); 751 752 start = buf; 753 group = file->private_data; 754 755 pr_debug("%s: group=%p\n", __func__, group); 756 757 add_wait_queue(&group->notification_waitq, &wait); 758 while (1) { 759 /* 760 * User can supply arbitrarily large buffer. Avoid softlockups 761 * in case there are lots of available events. 762 */ 763 cond_resched(); 764 event = get_one_event(group, count); 765 if (IS_ERR(event)) { 766 ret = PTR_ERR(event); 767 break; 768 } 769 770 if (!event) { 771 ret = -EAGAIN; 772 if (file->f_flags & O_NONBLOCK) 773 break; 774 775 ret = -ERESTARTSYS; 776 if (signal_pending(current)) 777 break; 778 779 if (start != buf) 780 break; 781 782 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 783 continue; 784 } 785 786 ret = copy_event_to_user(group, event, buf, count); 787 if (unlikely(ret == -EOPENSTALE)) { 788 /* 789 * We cannot report events with stale fd so drop it. 790 * Setting ret to 0 will continue the event loop and 791 * do the right thing if there are no more events to 792 * read (i.e. return bytes read, -EAGAIN or wait). 793 */ 794 ret = 0; 795 } 796 797 /* 798 * Permission events get queued to wait for response. Other 799 * events can be destroyed now. 800 */ 801 if (!fanotify_is_perm_event(event->mask)) { 802 fsnotify_destroy_event(group, &event->fse); 803 } else { 804 if (ret <= 0) { 805 spin_lock(&group->notification_lock); 806 finish_permission_event(group, 807 FANOTIFY_PERM(event), FAN_DENY); 808 wake_up(&group->fanotify_data.access_waitq); 809 } else { 810 spin_lock(&group->notification_lock); 811 list_add_tail(&event->fse.list, 812 &group->fanotify_data.access_list); 813 spin_unlock(&group->notification_lock); 814 } 815 } 816 if (ret < 0) 817 break; 818 buf += ret; 819 count -= ret; 820 } 821 remove_wait_queue(&group->notification_waitq, &wait); 822 823 if (start != buf && ret != -EFAULT) 824 ret = buf - start; 825 return ret; 826 } 827 828 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) 829 { 830 struct fanotify_response response = { .fd = -1, .response = -1 }; 831 struct fsnotify_group *group; 832 int ret; 833 834 if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) 835 return -EINVAL; 836 837 group = file->private_data; 838 839 if (count < sizeof(response)) 840 return -EINVAL; 841 842 count = sizeof(response); 843 844 pr_debug("%s: group=%p count=%zu\n", __func__, group, count); 845 846 if (copy_from_user(&response, buf, count)) 847 return -EFAULT; 848 849 ret = process_access_response(group, &response); 850 if (ret < 0) 851 count = ret; 852 853 return count; 854 } 855 856 static int fanotify_release(struct inode *ignored, struct file *file) 857 { 858 struct fsnotify_group *group = file->private_data; 859 struct fsnotify_event *fsn_event; 860 861 /* 862 * Stop new events from arriving in the notification queue. since 863 * userspace cannot use fanotify fd anymore, no event can enter or 864 * leave access_list by now either. 865 */ 866 fsnotify_group_stop_queueing(group); 867 868 /* 869 * Process all permission events on access_list and notification queue 870 * and simulate reply from userspace. 871 */ 872 spin_lock(&group->notification_lock); 873 while (!list_empty(&group->fanotify_data.access_list)) { 874 struct fanotify_perm_event *event; 875 876 event = list_first_entry(&group->fanotify_data.access_list, 877 struct fanotify_perm_event, fae.fse.list); 878 list_del_init(&event->fae.fse.list); 879 finish_permission_event(group, event, FAN_ALLOW); 880 spin_lock(&group->notification_lock); 881 } 882 883 /* 884 * Destroy all non-permission events. For permission events just 885 * dequeue them and set the response. They will be freed once the 886 * response is consumed and fanotify_get_response() returns. 887 */ 888 while ((fsn_event = fsnotify_remove_first_event(group))) { 889 struct fanotify_event *event = FANOTIFY_E(fsn_event); 890 891 if (!(event->mask & FANOTIFY_PERM_EVENTS)) { 892 spin_unlock(&group->notification_lock); 893 fsnotify_destroy_event(group, fsn_event); 894 } else { 895 finish_permission_event(group, FANOTIFY_PERM(event), 896 FAN_ALLOW); 897 } 898 spin_lock(&group->notification_lock); 899 } 900 spin_unlock(&group->notification_lock); 901 902 /* Response for all permission events it set, wakeup waiters */ 903 wake_up(&group->fanotify_data.access_waitq); 904 905 /* matches the fanotify_init->fsnotify_alloc_group */ 906 fsnotify_destroy_group(group); 907 908 return 0; 909 } 910 911 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 912 { 913 struct fsnotify_group *group; 914 struct fsnotify_event *fsn_event; 915 void __user *p; 916 int ret = -ENOTTY; 917 size_t send_len = 0; 918 919 group = file->private_data; 920 921 p = (void __user *) arg; 922 923 switch (cmd) { 924 case FIONREAD: 925 spin_lock(&group->notification_lock); 926 list_for_each_entry(fsn_event, &group->notification_list, list) 927 send_len += FAN_EVENT_METADATA_LEN; 928 spin_unlock(&group->notification_lock); 929 ret = put_user(send_len, (int __user *) p); 930 break; 931 } 932 933 return ret; 934 } 935 936 static const struct file_operations fanotify_fops = { 937 .show_fdinfo = fanotify_show_fdinfo, 938 .poll = fanotify_poll, 939 .read = fanotify_read, 940 .write = fanotify_write, 941 .fasync = NULL, 942 .release = fanotify_release, 943 .unlocked_ioctl = fanotify_ioctl, 944 .compat_ioctl = compat_ptr_ioctl, 945 .llseek = noop_llseek, 946 }; 947 948 static int fanotify_find_path(int dfd, const char __user *filename, 949 struct path *path, unsigned int flags, __u64 mask, 950 unsigned int obj_type) 951 { 952 int ret; 953 954 pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, 955 dfd, filename, flags); 956 957 if (filename == NULL) { 958 struct fd f = fdget(dfd); 959 960 ret = -EBADF; 961 if (!f.file) 962 goto out; 963 964 ret = -ENOTDIR; 965 if ((flags & FAN_MARK_ONLYDIR) && 966 !(S_ISDIR(file_inode(f.file)->i_mode))) { 967 fdput(f); 968 goto out; 969 } 970 971 *path = f.file->f_path; 972 path_get(path); 973 fdput(f); 974 } else { 975 unsigned int lookup_flags = 0; 976 977 if (!(flags & FAN_MARK_DONT_FOLLOW)) 978 lookup_flags |= LOOKUP_FOLLOW; 979 if (flags & FAN_MARK_ONLYDIR) 980 lookup_flags |= LOOKUP_DIRECTORY; 981 982 ret = user_path_at(dfd, filename, lookup_flags, path); 983 if (ret) 984 goto out; 985 } 986 987 /* you can only watch an inode if you have read permissions on it */ 988 ret = path_permission(path, MAY_READ); 989 if (ret) { 990 path_put(path); 991 goto out; 992 } 993 994 ret = security_path_notify(path, mask, obj_type); 995 if (ret) 996 path_put(path); 997 998 out: 999 return ret; 1000 } 1001 1002 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, 1003 __u32 mask, unsigned int flags, 1004 __u32 umask, int *destroy) 1005 { 1006 __u32 oldmask, newmask; 1007 1008 /* umask bits cannot be removed by user */ 1009 mask &= ~umask; 1010 spin_lock(&fsn_mark->lock); 1011 oldmask = fsnotify_calc_mask(fsn_mark); 1012 if (!(flags & FAN_MARK_IGNORED_MASK)) { 1013 fsn_mark->mask &= ~mask; 1014 } else { 1015 fsn_mark->ignored_mask &= ~mask; 1016 } 1017 newmask = fsnotify_calc_mask(fsn_mark); 1018 /* 1019 * We need to keep the mark around even if remaining mask cannot 1020 * result in any events (e.g. mask == FAN_ONDIR) to support incremenal 1021 * changes to the mask. 1022 * Destroy mark when only umask bits remain. 1023 */ 1024 *destroy = !((fsn_mark->mask | fsn_mark->ignored_mask) & ~umask); 1025 spin_unlock(&fsn_mark->lock); 1026 1027 return oldmask & ~newmask; 1028 } 1029 1030 static int fanotify_remove_mark(struct fsnotify_group *group, 1031 fsnotify_connp_t *connp, __u32 mask, 1032 unsigned int flags, __u32 umask) 1033 { 1034 struct fsnotify_mark *fsn_mark = NULL; 1035 __u32 removed; 1036 int destroy_mark; 1037 1038 fsnotify_group_lock(group); 1039 fsn_mark = fsnotify_find_mark(connp, group); 1040 if (!fsn_mark) { 1041 fsnotify_group_unlock(group); 1042 return -ENOENT; 1043 } 1044 1045 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, 1046 umask, &destroy_mark); 1047 if (removed & fsnotify_conn_mask(fsn_mark->connector)) 1048 fsnotify_recalc_mask(fsn_mark->connector); 1049 if (destroy_mark) 1050 fsnotify_detach_mark(fsn_mark); 1051 fsnotify_group_unlock(group); 1052 if (destroy_mark) 1053 fsnotify_free_mark(fsn_mark); 1054 1055 /* matches the fsnotify_find_mark() */ 1056 fsnotify_put_mark(fsn_mark); 1057 return 0; 1058 } 1059 1060 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, 1061 struct vfsmount *mnt, __u32 mask, 1062 unsigned int flags, __u32 umask) 1063 { 1064 return fanotify_remove_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, 1065 mask, flags, umask); 1066 } 1067 1068 static int fanotify_remove_sb_mark(struct fsnotify_group *group, 1069 struct super_block *sb, __u32 mask, 1070 unsigned int flags, __u32 umask) 1071 { 1072 return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask, 1073 flags, umask); 1074 } 1075 1076 static int fanotify_remove_inode_mark(struct fsnotify_group *group, 1077 struct inode *inode, __u32 mask, 1078 unsigned int flags, __u32 umask) 1079 { 1080 return fanotify_remove_mark(group, &inode->i_fsnotify_marks, mask, 1081 flags, umask); 1082 } 1083 1084 static bool fanotify_mark_update_flags(struct fsnotify_mark *fsn_mark, 1085 unsigned int fan_flags) 1086 { 1087 bool want_iref = !(fan_flags & FAN_MARK_EVICTABLE); 1088 bool recalc = false; 1089 1090 /* 1091 * Setting FAN_MARK_IGNORED_SURV_MODIFY for the first time may lead to 1092 * the removal of the FS_MODIFY bit in calculated mask if it was set 1093 * because of an ignored mask that is now going to survive FS_MODIFY. 1094 */ 1095 if ((fan_flags & FAN_MARK_IGNORED_MASK) && 1096 (fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) && 1097 !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) { 1098 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; 1099 if (!(fsn_mark->mask & FS_MODIFY)) 1100 recalc = true; 1101 } 1102 1103 if (fsn_mark->connector->type != FSNOTIFY_OBJ_TYPE_INODE || 1104 want_iref == !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)) 1105 return recalc; 1106 1107 /* 1108 * NO_IREF may be removed from a mark, but not added. 1109 * When removed, fsnotify_recalc_mask() will take the inode ref. 1110 */ 1111 WARN_ON_ONCE(!want_iref); 1112 fsn_mark->flags &= ~FSNOTIFY_MARK_FLAG_NO_IREF; 1113 1114 return true; 1115 } 1116 1117 static bool fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, 1118 __u32 mask, unsigned int fan_flags) 1119 { 1120 bool recalc; 1121 1122 spin_lock(&fsn_mark->lock); 1123 if (!(fan_flags & FAN_MARK_IGNORED_MASK)) 1124 fsn_mark->mask |= mask; 1125 else 1126 fsn_mark->ignored_mask |= mask; 1127 1128 recalc = fsnotify_calc_mask(fsn_mark) & 1129 ~fsnotify_conn_mask(fsn_mark->connector); 1130 1131 recalc |= fanotify_mark_update_flags(fsn_mark, fan_flags); 1132 spin_unlock(&fsn_mark->lock); 1133 1134 return recalc; 1135 } 1136 1137 static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, 1138 fsnotify_connp_t *connp, 1139 unsigned int obj_type, 1140 unsigned int fan_flags, 1141 __kernel_fsid_t *fsid) 1142 { 1143 struct ucounts *ucounts = group->fanotify_data.ucounts; 1144 struct fsnotify_mark *mark; 1145 int ret; 1146 1147 /* 1148 * Enforce per user marks limits per user in all containing user ns. 1149 * A group with FAN_UNLIMITED_MARKS does not contribute to mark count 1150 * in the limited groups account. 1151 */ 1152 if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS) && 1153 !inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_FANOTIFY_MARKS)) 1154 return ERR_PTR(-ENOSPC); 1155 1156 mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); 1157 if (!mark) { 1158 ret = -ENOMEM; 1159 goto out_dec_ucounts; 1160 } 1161 1162 fsnotify_init_mark(mark, group); 1163 if (fan_flags & FAN_MARK_EVICTABLE) 1164 mark->flags |= FSNOTIFY_MARK_FLAG_NO_IREF; 1165 1166 ret = fsnotify_add_mark_locked(mark, connp, obj_type, 0, fsid); 1167 if (ret) { 1168 fsnotify_put_mark(mark); 1169 goto out_dec_ucounts; 1170 } 1171 1172 return mark; 1173 1174 out_dec_ucounts: 1175 if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS)) 1176 dec_ucount(ucounts, UCOUNT_FANOTIFY_MARKS); 1177 return ERR_PTR(ret); 1178 } 1179 1180 static int fanotify_group_init_error_pool(struct fsnotify_group *group) 1181 { 1182 if (mempool_initialized(&group->fanotify_data.error_events_pool)) 1183 return 0; 1184 1185 return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool, 1186 FANOTIFY_DEFAULT_FEE_POOL_SIZE, 1187 sizeof(struct fanotify_error_event)); 1188 } 1189 1190 static int fanotify_add_mark(struct fsnotify_group *group, 1191 fsnotify_connp_t *connp, unsigned int obj_type, 1192 __u32 mask, unsigned int fan_flags, 1193 __kernel_fsid_t *fsid) 1194 { 1195 struct fsnotify_mark *fsn_mark; 1196 bool recalc; 1197 int ret = 0; 1198 1199 fsnotify_group_lock(group); 1200 fsn_mark = fsnotify_find_mark(connp, group); 1201 if (!fsn_mark) { 1202 fsn_mark = fanotify_add_new_mark(group, connp, obj_type, 1203 fan_flags, fsid); 1204 if (IS_ERR(fsn_mark)) { 1205 fsnotify_group_unlock(group); 1206 return PTR_ERR(fsn_mark); 1207 } 1208 } 1209 1210 /* 1211 * Non evictable mark cannot be downgraded to evictable mark. 1212 */ 1213 if (fan_flags & FAN_MARK_EVICTABLE && 1214 !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)) { 1215 ret = -EEXIST; 1216 goto out; 1217 } 1218 1219 /* 1220 * Error events are pre-allocated per group, only if strictly 1221 * needed (i.e. FAN_FS_ERROR was requested). 1222 */ 1223 if (!(fan_flags & FAN_MARK_IGNORED_MASK) && (mask & FAN_FS_ERROR)) { 1224 ret = fanotify_group_init_error_pool(group); 1225 if (ret) 1226 goto out; 1227 } 1228 1229 recalc = fanotify_mark_add_to_mask(fsn_mark, mask, fan_flags); 1230 if (recalc) 1231 fsnotify_recalc_mask(fsn_mark->connector); 1232 1233 out: 1234 fsnotify_group_unlock(group); 1235 1236 fsnotify_put_mark(fsn_mark); 1237 return ret; 1238 } 1239 1240 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, 1241 struct vfsmount *mnt, __u32 mask, 1242 unsigned int flags, __kernel_fsid_t *fsid) 1243 { 1244 return fanotify_add_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, 1245 FSNOTIFY_OBJ_TYPE_VFSMOUNT, mask, flags, fsid); 1246 } 1247 1248 static int fanotify_add_sb_mark(struct fsnotify_group *group, 1249 struct super_block *sb, __u32 mask, 1250 unsigned int flags, __kernel_fsid_t *fsid) 1251 { 1252 return fanotify_add_mark(group, &sb->s_fsnotify_marks, 1253 FSNOTIFY_OBJ_TYPE_SB, mask, flags, fsid); 1254 } 1255 1256 static int fanotify_add_inode_mark(struct fsnotify_group *group, 1257 struct inode *inode, __u32 mask, 1258 unsigned int flags, __kernel_fsid_t *fsid) 1259 { 1260 pr_debug("%s: group=%p inode=%p\n", __func__, group, inode); 1261 1262 /* 1263 * If some other task has this inode open for write we should not add 1264 * an ignored mark, unless that ignored mark is supposed to survive 1265 * modification changes anyway. 1266 */ 1267 if ((flags & FAN_MARK_IGNORED_MASK) && 1268 !(flags & FAN_MARK_IGNORED_SURV_MODIFY) && 1269 inode_is_open_for_write(inode)) 1270 return 0; 1271 1272 return fanotify_add_mark(group, &inode->i_fsnotify_marks, 1273 FSNOTIFY_OBJ_TYPE_INODE, mask, flags, fsid); 1274 } 1275 1276 static struct fsnotify_event *fanotify_alloc_overflow_event(void) 1277 { 1278 struct fanotify_event *oevent; 1279 1280 oevent = kmalloc(sizeof(*oevent), GFP_KERNEL_ACCOUNT); 1281 if (!oevent) 1282 return NULL; 1283 1284 fanotify_init_event(oevent, 0, FS_Q_OVERFLOW); 1285 oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW; 1286 1287 return &oevent->fse; 1288 } 1289 1290 static struct hlist_head *fanotify_alloc_merge_hash(void) 1291 { 1292 struct hlist_head *hash; 1293 1294 hash = kmalloc(sizeof(struct hlist_head) << FANOTIFY_HTABLE_BITS, 1295 GFP_KERNEL_ACCOUNT); 1296 if (!hash) 1297 return NULL; 1298 1299 __hash_init(hash, FANOTIFY_HTABLE_SIZE); 1300 1301 return hash; 1302 } 1303 1304 /* fanotify syscalls */ 1305 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 1306 { 1307 struct fsnotify_group *group; 1308 int f_flags, fd; 1309 unsigned int fid_mode = flags & FANOTIFY_FID_BITS; 1310 unsigned int class = flags & FANOTIFY_CLASS_BITS; 1311 unsigned int internal_flags = 0; 1312 1313 pr_debug("%s: flags=%x event_f_flags=%x\n", 1314 __func__, flags, event_f_flags); 1315 1316 if (!capable(CAP_SYS_ADMIN)) { 1317 /* 1318 * An unprivileged user can setup an fanotify group with 1319 * limited functionality - an unprivileged group is limited to 1320 * notification events with file handles and it cannot use 1321 * unlimited queue/marks. 1322 */ 1323 if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) || !fid_mode) 1324 return -EPERM; 1325 1326 /* 1327 * Setting the internal flag FANOTIFY_UNPRIV on the group 1328 * prevents setting mount/filesystem marks on this group and 1329 * prevents reporting pid and open fd in events. 1330 */ 1331 internal_flags |= FANOTIFY_UNPRIV; 1332 } 1333 1334 #ifdef CONFIG_AUDITSYSCALL 1335 if (flags & ~(FANOTIFY_INIT_FLAGS | FAN_ENABLE_AUDIT)) 1336 #else 1337 if (flags & ~FANOTIFY_INIT_FLAGS) 1338 #endif 1339 return -EINVAL; 1340 1341 /* 1342 * A pidfd can only be returned for a thread-group leader; thus 1343 * FAN_REPORT_PIDFD and FAN_REPORT_TID need to remain mutually 1344 * exclusive. 1345 */ 1346 if ((flags & FAN_REPORT_PIDFD) && (flags & FAN_REPORT_TID)) 1347 return -EINVAL; 1348 1349 if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) 1350 return -EINVAL; 1351 1352 switch (event_f_flags & O_ACCMODE) { 1353 case O_RDONLY: 1354 case O_RDWR: 1355 case O_WRONLY: 1356 break; 1357 default: 1358 return -EINVAL; 1359 } 1360 1361 if (fid_mode && class != FAN_CLASS_NOTIF) 1362 return -EINVAL; 1363 1364 /* 1365 * Child name is reported with parent fid so requires dir fid. 1366 * We can report both child fid and dir fid with or without name. 1367 */ 1368 if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID)) 1369 return -EINVAL; 1370 1371 /* 1372 * FAN_REPORT_TARGET_FID requires FAN_REPORT_NAME and FAN_REPORT_FID 1373 * and is used as an indication to report both dir and child fid on all 1374 * dirent events. 1375 */ 1376 if ((fid_mode & FAN_REPORT_TARGET_FID) && 1377 (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID))) 1378 return -EINVAL; 1379 1380 f_flags = O_RDWR | __FMODE_NONOTIFY; 1381 if (flags & FAN_CLOEXEC) 1382 f_flags |= O_CLOEXEC; 1383 if (flags & FAN_NONBLOCK) 1384 f_flags |= O_NONBLOCK; 1385 1386 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ 1387 group = fsnotify_alloc_group(&fanotify_fsnotify_ops, 1388 FSNOTIFY_GROUP_USER | FSNOTIFY_GROUP_NOFS); 1389 if (IS_ERR(group)) { 1390 return PTR_ERR(group); 1391 } 1392 1393 /* Enforce groups limits per user in all containing user ns */ 1394 group->fanotify_data.ucounts = inc_ucount(current_user_ns(), 1395 current_euid(), 1396 UCOUNT_FANOTIFY_GROUPS); 1397 if (!group->fanotify_data.ucounts) { 1398 fd = -EMFILE; 1399 goto out_destroy_group; 1400 } 1401 1402 group->fanotify_data.flags = flags | internal_flags; 1403 group->memcg = get_mem_cgroup_from_mm(current->mm); 1404 1405 group->fanotify_data.merge_hash = fanotify_alloc_merge_hash(); 1406 if (!group->fanotify_data.merge_hash) { 1407 fd = -ENOMEM; 1408 goto out_destroy_group; 1409 } 1410 1411 group->overflow_event = fanotify_alloc_overflow_event(); 1412 if (unlikely(!group->overflow_event)) { 1413 fd = -ENOMEM; 1414 goto out_destroy_group; 1415 } 1416 1417 if (force_o_largefile()) 1418 event_f_flags |= O_LARGEFILE; 1419 group->fanotify_data.f_flags = event_f_flags; 1420 init_waitqueue_head(&group->fanotify_data.access_waitq); 1421 INIT_LIST_HEAD(&group->fanotify_data.access_list); 1422 switch (class) { 1423 case FAN_CLASS_NOTIF: 1424 group->priority = FS_PRIO_0; 1425 break; 1426 case FAN_CLASS_CONTENT: 1427 group->priority = FS_PRIO_1; 1428 break; 1429 case FAN_CLASS_PRE_CONTENT: 1430 group->priority = FS_PRIO_2; 1431 break; 1432 default: 1433 fd = -EINVAL; 1434 goto out_destroy_group; 1435 } 1436 1437 if (flags & FAN_UNLIMITED_QUEUE) { 1438 fd = -EPERM; 1439 if (!capable(CAP_SYS_ADMIN)) 1440 goto out_destroy_group; 1441 group->max_events = UINT_MAX; 1442 } else { 1443 group->max_events = fanotify_max_queued_events; 1444 } 1445 1446 if (flags & FAN_UNLIMITED_MARKS) { 1447 fd = -EPERM; 1448 if (!capable(CAP_SYS_ADMIN)) 1449 goto out_destroy_group; 1450 } 1451 1452 if (flags & FAN_ENABLE_AUDIT) { 1453 fd = -EPERM; 1454 if (!capable(CAP_AUDIT_WRITE)) 1455 goto out_destroy_group; 1456 } 1457 1458 fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); 1459 if (fd < 0) 1460 goto out_destroy_group; 1461 1462 return fd; 1463 1464 out_destroy_group: 1465 fsnotify_destroy_group(group); 1466 return fd; 1467 } 1468 1469 static int fanotify_test_fsid(struct dentry *dentry, __kernel_fsid_t *fsid) 1470 { 1471 __kernel_fsid_t root_fsid; 1472 int err; 1473 1474 /* 1475 * Make sure dentry is not of a filesystem with zero fsid (e.g. fuse). 1476 */ 1477 err = vfs_get_fsid(dentry, fsid); 1478 if (err) 1479 return err; 1480 1481 if (!fsid->val[0] && !fsid->val[1]) 1482 return -ENODEV; 1483 1484 /* 1485 * Make sure dentry is not of a filesystem subvolume (e.g. btrfs) 1486 * which uses a different fsid than sb root. 1487 */ 1488 err = vfs_get_fsid(dentry->d_sb->s_root, &root_fsid); 1489 if (err) 1490 return err; 1491 1492 if (root_fsid.val[0] != fsid->val[0] || 1493 root_fsid.val[1] != fsid->val[1]) 1494 return -EXDEV; 1495 1496 return 0; 1497 } 1498 1499 /* Check if filesystem can encode a unique fid */ 1500 static int fanotify_test_fid(struct dentry *dentry) 1501 { 1502 /* 1503 * We need to make sure that the file system supports at least 1504 * encoding a file handle so user can use name_to_handle_at() to 1505 * compare fid returned with event to the file handle of watched 1506 * objects. However, name_to_handle_at() requires that the 1507 * filesystem also supports decoding file handles. 1508 */ 1509 if (!dentry->d_sb->s_export_op || 1510 !dentry->d_sb->s_export_op->fh_to_dentry) 1511 return -EOPNOTSUPP; 1512 1513 return 0; 1514 } 1515 1516 static int fanotify_events_supported(struct fsnotify_group *group, 1517 struct path *path, __u64 mask, 1518 unsigned int flags) 1519 { 1520 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; 1521 /* Strict validation of events in non-dir inode mask with v5.17+ APIs */ 1522 bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) || 1523 (mask & FAN_RENAME); 1524 1525 /* 1526 * Some filesystems such as 'proc' acquire unusual locks when opening 1527 * files. For them fanotify permission events have high chances of 1528 * deadlocking the system - open done when reporting fanotify event 1529 * blocks on this "unusual" lock while another process holding the lock 1530 * waits for fanotify permission event to be answered. Just disallow 1531 * permission events for such filesystems. 1532 */ 1533 if (mask & FANOTIFY_PERM_EVENTS && 1534 path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM) 1535 return -EINVAL; 1536 1537 /* 1538 * We shouldn't have allowed setting dirent events and the directory 1539 * flags FAN_ONDIR and FAN_EVENT_ON_CHILD in mask of non-dir inode, 1540 * but because we always allowed it, error only when using new APIs. 1541 */ 1542 if (strict_dir_events && mark_type == FAN_MARK_INODE && 1543 !d_is_dir(path->dentry) && (mask & FANOTIFY_DIRONLY_EVENT_BITS)) 1544 return -ENOTDIR; 1545 1546 return 0; 1547 } 1548 1549 static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, 1550 int dfd, const char __user *pathname) 1551 { 1552 struct inode *inode = NULL; 1553 struct vfsmount *mnt = NULL; 1554 struct fsnotify_group *group; 1555 struct fd f; 1556 struct path path; 1557 __kernel_fsid_t __fsid, *fsid = NULL; 1558 u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS; 1559 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; 1560 bool ignored = flags & FAN_MARK_IGNORED_MASK; 1561 unsigned int obj_type, fid_mode; 1562 u32 umask = 0; 1563 int ret; 1564 1565 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", 1566 __func__, fanotify_fd, flags, dfd, pathname, mask); 1567 1568 /* we only use the lower 32 bits as of right now. */ 1569 if (upper_32_bits(mask)) 1570 return -EINVAL; 1571 1572 if (flags & ~FANOTIFY_MARK_FLAGS) 1573 return -EINVAL; 1574 1575 switch (mark_type) { 1576 case FAN_MARK_INODE: 1577 obj_type = FSNOTIFY_OBJ_TYPE_INODE; 1578 break; 1579 case FAN_MARK_MOUNT: 1580 obj_type = FSNOTIFY_OBJ_TYPE_VFSMOUNT; 1581 break; 1582 case FAN_MARK_FILESYSTEM: 1583 obj_type = FSNOTIFY_OBJ_TYPE_SB; 1584 break; 1585 default: 1586 return -EINVAL; 1587 } 1588 1589 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { 1590 case FAN_MARK_ADD: 1591 case FAN_MARK_REMOVE: 1592 if (!mask) 1593 return -EINVAL; 1594 break; 1595 case FAN_MARK_FLUSH: 1596 if (flags & ~(FANOTIFY_MARK_TYPE_BITS | FAN_MARK_FLUSH)) 1597 return -EINVAL; 1598 break; 1599 default: 1600 return -EINVAL; 1601 } 1602 1603 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) 1604 valid_mask |= FANOTIFY_PERM_EVENTS; 1605 1606 if (mask & ~valid_mask) 1607 return -EINVAL; 1608 1609 /* Event flags (ONDIR, ON_CHILD) are meaningless in ignored mask */ 1610 if (ignored) 1611 mask &= ~FANOTIFY_EVENT_FLAGS; 1612 1613 f = fdget(fanotify_fd); 1614 if (unlikely(!f.file)) 1615 return -EBADF; 1616 1617 /* verify that this is indeed an fanotify instance */ 1618 ret = -EINVAL; 1619 if (unlikely(f.file->f_op != &fanotify_fops)) 1620 goto fput_and_out; 1621 group = f.file->private_data; 1622 1623 /* 1624 * An unprivileged user is not allowed to setup mount nor filesystem 1625 * marks. This also includes setting up such marks by a group that 1626 * was initialized by an unprivileged user. 1627 */ 1628 ret = -EPERM; 1629 if ((!capable(CAP_SYS_ADMIN) || 1630 FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) && 1631 mark_type != FAN_MARK_INODE) 1632 goto fput_and_out; 1633 1634 /* 1635 * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not 1636 * allowed to set permissions events. 1637 */ 1638 ret = -EINVAL; 1639 if (mask & FANOTIFY_PERM_EVENTS && 1640 group->priority == FS_PRIO_0) 1641 goto fput_and_out; 1642 1643 if (mask & FAN_FS_ERROR && 1644 mark_type != FAN_MARK_FILESYSTEM) 1645 goto fput_and_out; 1646 1647 /* 1648 * Evictable is only relevant for inode marks, because only inode object 1649 * can be evicted on memory pressure. 1650 */ 1651 if (flags & FAN_MARK_EVICTABLE && 1652 mark_type != FAN_MARK_INODE) 1653 goto fput_and_out; 1654 1655 /* 1656 * Events that do not carry enough information to report 1657 * event->fd require a group that supports reporting fid. Those 1658 * events are not supported on a mount mark, because they do not 1659 * carry enough information (i.e. path) to be filtered by mount 1660 * point. 1661 */ 1662 fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); 1663 if (mask & ~(FANOTIFY_FD_EVENTS|FANOTIFY_EVENT_FLAGS) && 1664 (!fid_mode || mark_type == FAN_MARK_MOUNT)) 1665 goto fput_and_out; 1666 1667 /* 1668 * FAN_RENAME uses special info type records to report the old and 1669 * new parent+name. Reporting only old and new parent id is less 1670 * useful and was not implemented. 1671 */ 1672 if (mask & FAN_RENAME && !(fid_mode & FAN_REPORT_NAME)) 1673 goto fput_and_out; 1674 1675 if (flags & FAN_MARK_FLUSH) { 1676 ret = 0; 1677 if (mark_type == FAN_MARK_MOUNT) 1678 fsnotify_clear_vfsmount_marks_by_group(group); 1679 else if (mark_type == FAN_MARK_FILESYSTEM) 1680 fsnotify_clear_sb_marks_by_group(group); 1681 else 1682 fsnotify_clear_inode_marks_by_group(group); 1683 goto fput_and_out; 1684 } 1685 1686 ret = fanotify_find_path(dfd, pathname, &path, flags, 1687 (mask & ALL_FSNOTIFY_EVENTS), obj_type); 1688 if (ret) 1689 goto fput_and_out; 1690 1691 if (flags & FAN_MARK_ADD) { 1692 ret = fanotify_events_supported(group, &path, mask, flags); 1693 if (ret) 1694 goto path_put_and_out; 1695 } 1696 1697 if (fid_mode) { 1698 ret = fanotify_test_fsid(path.dentry, &__fsid); 1699 if (ret) 1700 goto path_put_and_out; 1701 1702 ret = fanotify_test_fid(path.dentry); 1703 if (ret) 1704 goto path_put_and_out; 1705 1706 fsid = &__fsid; 1707 } 1708 1709 /* inode held in place by reference to path; group by fget on fd */ 1710 if (mark_type == FAN_MARK_INODE) 1711 inode = path.dentry->d_inode; 1712 else 1713 mnt = path.mnt; 1714 1715 /* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */ 1716 if (mnt || !S_ISDIR(inode->i_mode)) { 1717 mask &= ~FAN_EVENT_ON_CHILD; 1718 umask = FAN_EVENT_ON_CHILD; 1719 /* 1720 * If group needs to report parent fid, register for getting 1721 * events with parent/name info for non-directory. 1722 */ 1723 if ((fid_mode & FAN_REPORT_DIR_FID) && 1724 (flags & FAN_MARK_ADD) && !ignored) 1725 mask |= FAN_EVENT_ON_CHILD; 1726 } 1727 1728 /* create/update an inode mark */ 1729 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) { 1730 case FAN_MARK_ADD: 1731 if (mark_type == FAN_MARK_MOUNT) 1732 ret = fanotify_add_vfsmount_mark(group, mnt, mask, 1733 flags, fsid); 1734 else if (mark_type == FAN_MARK_FILESYSTEM) 1735 ret = fanotify_add_sb_mark(group, mnt->mnt_sb, mask, 1736 flags, fsid); 1737 else 1738 ret = fanotify_add_inode_mark(group, inode, mask, 1739 flags, fsid); 1740 break; 1741 case FAN_MARK_REMOVE: 1742 if (mark_type == FAN_MARK_MOUNT) 1743 ret = fanotify_remove_vfsmount_mark(group, mnt, mask, 1744 flags, umask); 1745 else if (mark_type == FAN_MARK_FILESYSTEM) 1746 ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask, 1747 flags, umask); 1748 else 1749 ret = fanotify_remove_inode_mark(group, inode, mask, 1750 flags, umask); 1751 break; 1752 default: 1753 ret = -EINVAL; 1754 } 1755 1756 path_put_and_out: 1757 path_put(&path); 1758 fput_and_out: 1759 fdput(f); 1760 return ret; 1761 } 1762 1763 #ifndef CONFIG_ARCH_SPLIT_ARG64 1764 SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, 1765 __u64, mask, int, dfd, 1766 const char __user *, pathname) 1767 { 1768 return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname); 1769 } 1770 #endif 1771 1772 #if defined(CONFIG_ARCH_SPLIT_ARG64) || defined(CONFIG_COMPAT) 1773 SYSCALL32_DEFINE6(fanotify_mark, 1774 int, fanotify_fd, unsigned int, flags, 1775 SC_ARG64(mask), int, dfd, 1776 const char __user *, pathname) 1777 { 1778 return do_fanotify_mark(fanotify_fd, flags, SC_VAL64(__u64, mask), 1779 dfd, pathname); 1780 } 1781 #endif 1782 1783 /* 1784 * fanotify_user_setup - Our initialization function. Note that we cannot return 1785 * error because we have compiled-in VFS hooks. So an (unlikely) failure here 1786 * must result in panic(). 1787 */ 1788 static int __init fanotify_user_setup(void) 1789 { 1790 struct sysinfo si; 1791 int max_marks; 1792 1793 si_meminfo(&si); 1794 /* 1795 * Allow up to 1% of addressable memory to be accounted for per user 1796 * marks limited to the range [8192, 1048576]. mount and sb marks are 1797 * a lot cheaper than inode marks, but there is no reason for a user 1798 * to have many of those, so calculate by the cost of inode marks. 1799 */ 1800 max_marks = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) / 1801 INODE_MARK_COST; 1802 max_marks = clamp(max_marks, FANOTIFY_OLD_DEFAULT_MAX_MARKS, 1803 FANOTIFY_DEFAULT_MAX_USER_MARKS); 1804 1805 BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS); 1806 BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 12); 1807 BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 10); 1808 1809 fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, 1810 SLAB_PANIC|SLAB_ACCOUNT); 1811 fanotify_fid_event_cachep = KMEM_CACHE(fanotify_fid_event, 1812 SLAB_PANIC); 1813 fanotify_path_event_cachep = KMEM_CACHE(fanotify_path_event, 1814 SLAB_PANIC); 1815 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) { 1816 fanotify_perm_event_cachep = 1817 KMEM_CACHE(fanotify_perm_event, SLAB_PANIC); 1818 } 1819 1820 fanotify_max_queued_events = FANOTIFY_DEFAULT_MAX_EVENTS; 1821 init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS] = 1822 FANOTIFY_DEFAULT_MAX_GROUPS; 1823 init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS] = max_marks; 1824 fanotify_sysctls_init(); 1825 1826 return 0; 1827 } 1828 device_initcall(fanotify_user_setup); 1829