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 "../fsnotify.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/ */ 53static int fanotify_max_queued_events __read_mostly; 54 55#ifdef CONFIG_SYSCTL 56 57#include <linux/sysctl.h> 58 59static long ft_zero = 0; 60static long ft_int_max = INT_MAX; 61 62static 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 91static void __init fanotify_sysctls_init(void) 92{ 93 register_sysctl("fs/fanotify", fanotify_table); 94} 95#else 96#define fanotify_sysctls_init() do { } while (0) 97#endif /* CONFIG_SYSCTL */ 98 99/* 100 * All flags that may be specified in parameter event_f_flags of fanotify_init. 101 * 102 * Internal and external open flags are stored together in field f_flags of 103 * struct file. Only external open flags shall be allowed in event_f_flags. 104 * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be 105 * excluded. 106 */ 107#define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \ 108 O_ACCMODE | O_APPEND | O_NONBLOCK | \ 109 __O_SYNC | O_DSYNC | O_CLOEXEC | \ 110 O_LARGEFILE | O_NOATIME ) 111 112extern const struct fsnotify_ops fanotify_fsnotify_ops; 113 114struct kmem_cache *fanotify_mark_cache __ro_after_init; 115struct kmem_cache *fanotify_fid_event_cachep __ro_after_init; 116struct kmem_cache *fanotify_path_event_cachep __ro_after_init; 117struct kmem_cache *fanotify_perm_event_cachep __ro_after_init; 118 119#define FANOTIFY_EVENT_ALIGN 4 120#define FANOTIFY_FID_INFO_HDR_LEN \ 121 (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle)) 122#define FANOTIFY_PIDFD_INFO_HDR_LEN \ 123 sizeof(struct fanotify_event_info_pidfd) 124#define FANOTIFY_ERROR_INFO_LEN \ 125 (sizeof(struct fanotify_event_info_error)) 126 127static int fanotify_fid_info_len(int fh_len, int name_len) 128{ 129 int info_len = fh_len; 130 131 if (name_len) 132 info_len += name_len + 1; 133 134 return roundup(FANOTIFY_FID_INFO_HDR_LEN + info_len, 135 FANOTIFY_EVENT_ALIGN); 136} 137 138/* FAN_RENAME may have one or two dir+name info records */ 139static int fanotify_dir_name_info_len(struct fanotify_event *event) 140{ 141 struct fanotify_info *info = fanotify_event_info(event); 142 int dir_fh_len = fanotify_event_dir_fh_len(event); 143 int dir2_fh_len = fanotify_event_dir2_fh_len(event); 144 int info_len = 0; 145 146 if (dir_fh_len) 147 info_len += fanotify_fid_info_len(dir_fh_len, 148 info->name_len); 149 if (dir2_fh_len) 150 info_len += fanotify_fid_info_len(dir2_fh_len, 151 info->name2_len); 152 153 return info_len; 154} 155 156static size_t fanotify_event_len(unsigned int info_mode, 157 struct fanotify_event *event) 158{ 159 size_t event_len = FAN_EVENT_METADATA_LEN; 160 int fh_len; 161 int dot_len = 0; 162 163 if (!info_mode) 164 return event_len; 165 166 if (fanotify_is_error_event(event->mask)) 167 event_len += FANOTIFY_ERROR_INFO_LEN; 168 169 if (fanotify_event_has_any_dir_fh(event)) { 170 event_len += fanotify_dir_name_info_len(event); 171 } else if ((info_mode & FAN_REPORT_NAME) && 172 (event->mask & FAN_ONDIR)) { 173 /* 174 * With group flag FAN_REPORT_NAME, if name was not recorded in 175 * event on a directory, we will report the name ".". 176 */ 177 dot_len = 1; 178 } 179 180 if (info_mode & FAN_REPORT_PIDFD) 181 event_len += FANOTIFY_PIDFD_INFO_HDR_LEN; 182 183 if (fanotify_event_has_object_fh(event)) { 184 fh_len = fanotify_event_object_fh_len(event); 185 event_len += fanotify_fid_info_len(fh_len, dot_len); 186 } 187 188 return event_len; 189} 190 191/* 192 * Remove an hashed event from merge hash table. 193 */ 194static void fanotify_unhash_event(struct fsnotify_group *group, 195 struct fanotify_event *event) 196{ 197 assert_spin_locked(&group->notification_lock); 198 199 pr_debug("%s: group=%p event=%p bucket=%u\n", __func__, 200 group, event, fanotify_event_hash_bucket(group, event)); 201 202 if (WARN_ON_ONCE(hlist_unhashed(&event->merge_list))) 203 return; 204 205 hlist_del_init(&event->merge_list); 206} 207 208/* 209 * Get an fanotify notification event if one exists and is small 210 * enough to fit in "count". Return an error pointer if the count 211 * is not large enough. When permission event is dequeued, its state is 212 * updated accordingly. 213 */ 214static struct fanotify_event *get_one_event(struct fsnotify_group *group, 215 size_t count) 216{ 217 size_t event_size; 218 struct fanotify_event *event = NULL; 219 struct fsnotify_event *fsn_event; 220 unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); 221 222 pr_debug("%s: group=%p count=%zd\n", __func__, group, count); 223 224 spin_lock(&group->notification_lock); 225 fsn_event = fsnotify_peek_first_event(group); 226 if (!fsn_event) 227 goto out; 228 229 event = FANOTIFY_E(fsn_event); 230 event_size = fanotify_event_len(info_mode, event); 231 232 if (event_size > count) { 233 event = ERR_PTR(-EINVAL); 234 goto out; 235 } 236 237 /* 238 * Held the notification_lock the whole time, so this is the 239 * same event we peeked above. 240 */ 241 fsnotify_remove_first_event(group); 242 if (fanotify_is_perm_event(event->mask)) 243 FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED; 244 if (fanotify_is_hashed_event(event->mask)) 245 fanotify_unhash_event(group, event); 246out: 247 spin_unlock(&group->notification_lock); 248 return event; 249} 250 251static int create_fd(struct fsnotify_group *group, const struct path *path, 252 struct file **file) 253{ 254 int client_fd; 255 struct file *new_file; 256 257 client_fd = get_unused_fd_flags(group->fanotify_data.f_flags); 258 if (client_fd < 0) 259 return client_fd; 260 261 /* 262 * we need a new file handle for the userspace program so it can read even if it was 263 * originally opened O_WRONLY. 264 */ 265 new_file = dentry_open(path, 266 group->fanotify_data.f_flags | __FMODE_NONOTIFY, 267 current_cred()); 268 if (IS_ERR(new_file)) { 269 /* 270 * we still send an event even if we can't open the file. this 271 * can happen when say tasks are gone and we try to open their 272 * /proc files or we try to open a WRONLY file like in sysfs 273 * we just send the errno to userspace since there isn't much 274 * else we can do. 275 */ 276 put_unused_fd(client_fd); 277 client_fd = PTR_ERR(new_file); 278 } else { 279 *file = new_file; 280 } 281 282 return client_fd; 283} 284 285static int process_access_response_info(const char __user *info, 286 size_t info_len, 287 struct fanotify_response_info_audit_rule *friar) 288{ 289 if (info_len != sizeof(*friar)) 290 return -EINVAL; 291 292 if (copy_from_user(friar, info, sizeof(*friar))) 293 return -EFAULT; 294 295 if (friar->hdr.type != FAN_RESPONSE_INFO_AUDIT_RULE) 296 return -EINVAL; 297 if (friar->hdr.pad != 0) 298 return -EINVAL; 299 if (friar->hdr.len != sizeof(*friar)) 300 return -EINVAL; 301 302 return info_len; 303} 304 305/* 306 * Finish processing of permission event by setting it to ANSWERED state and 307 * drop group->notification_lock. 308 */ 309static void finish_permission_event(struct fsnotify_group *group, 310 struct fanotify_perm_event *event, u32 response, 311 struct fanotify_response_info_audit_rule *friar) 312 __releases(&group->notification_lock) 313{ 314 bool destroy = false; 315 316 assert_spin_locked(&group->notification_lock); 317 event->response = response & ~FAN_INFO; 318 if (response & FAN_INFO) 319 memcpy(&event->audit_rule, friar, sizeof(*friar)); 320 321 if (event->state == FAN_EVENT_CANCELED) 322 destroy = true; 323 else 324 event->state = FAN_EVENT_ANSWERED; 325 spin_unlock(&group->notification_lock); 326 if (destroy) 327 fsnotify_destroy_event(group, &event->fae.fse); 328} 329 330static int process_access_response(struct fsnotify_group *group, 331 struct fanotify_response *response_struct, 332 const char __user *info, 333 size_t info_len) 334{ 335 struct fanotify_perm_event *event; 336 int fd = response_struct->fd; 337 u32 response = response_struct->response; 338 int ret = info_len; 339 struct fanotify_response_info_audit_rule friar; 340 341 pr_debug("%s: group=%p fd=%d response=%u buf=%p size=%zu\n", __func__, 342 group, fd, response, info, info_len); 343 /* 344 * make sure the response is valid, if invalid we do nothing and either 345 * userspace can send a valid response or we will clean it up after the 346 * timeout 347 */ 348 if (response & ~FANOTIFY_RESPONSE_VALID_MASK) 349 return -EINVAL; 350 351 switch (response & FANOTIFY_RESPONSE_ACCESS) { 352 case FAN_ALLOW: 353 case FAN_DENY: 354 break; 355 default: 356 return -EINVAL; 357 } 358 359 if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT)) 360 return -EINVAL; 361 362 if (response & FAN_INFO) { 363 ret = process_access_response_info(info, info_len, &friar); 364 if (ret < 0) 365 return ret; 366 if (fd == FAN_NOFD) 367 return ret; 368 } else { 369 ret = 0; 370 } 371 372 if (fd < 0) 373 return -EINVAL; 374 375 spin_lock(&group->notification_lock); 376 list_for_each_entry(event, &group->fanotify_data.access_list, 377 fae.fse.list) { 378 if (event->fd != fd) 379 continue; 380 381 list_del_init(&event->fae.fse.list); 382 finish_permission_event(group, event, response, &friar); 383 wake_up(&group->fanotify_data.access_waitq); 384 return ret; 385 } 386 spin_unlock(&group->notification_lock); 387 388 return -ENOENT; 389} 390 391static size_t copy_error_info_to_user(struct fanotify_event *event, 392 char __user *buf, int count) 393{ 394 struct fanotify_event_info_error info = { }; 395 struct fanotify_error_event *fee = FANOTIFY_EE(event); 396 397 info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR; 398 info.hdr.len = FANOTIFY_ERROR_INFO_LEN; 399 400 if (WARN_ON(count < info.hdr.len)) 401 return -EFAULT; 402 403 info.error = fee->error; 404 info.error_count = fee->err_count; 405 406 if (copy_to_user(buf, &info, sizeof(info))) 407 return -EFAULT; 408 409 return info.hdr.len; 410} 411 412static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh, 413 int info_type, const char *name, 414 size_t name_len, 415 char __user *buf, size_t count) 416{ 417 struct fanotify_event_info_fid info = { }; 418 struct file_handle handle = { }; 419 unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf; 420 size_t fh_len = fh ? fh->len : 0; 421 size_t info_len = fanotify_fid_info_len(fh_len, name_len); 422 size_t len = info_len; 423 424 pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n", 425 __func__, fh_len, name_len, info_len, count); 426 427 if (WARN_ON_ONCE(len < sizeof(info) || len > count)) 428 return -EFAULT; 429 430 /* 431 * Copy event info fid header followed by variable sized file handle 432 * and optionally followed by variable sized filename. 433 */ 434 switch (info_type) { 435 case FAN_EVENT_INFO_TYPE_FID: 436 case FAN_EVENT_INFO_TYPE_DFID: 437 if (WARN_ON_ONCE(name_len)) 438 return -EFAULT; 439 break; 440 case FAN_EVENT_INFO_TYPE_DFID_NAME: 441 case FAN_EVENT_INFO_TYPE_OLD_DFID_NAME: 442 case FAN_EVENT_INFO_TYPE_NEW_DFID_NAME: 443 if (WARN_ON_ONCE(!name || !name_len)) 444 return -EFAULT; 445 break; 446 default: 447 return -EFAULT; 448 } 449 450 info.hdr.info_type = info_type; 451 info.hdr.len = len; 452 info.fsid = *fsid; 453 if (copy_to_user(buf, &info, sizeof(info))) 454 return -EFAULT; 455 456 buf += sizeof(info); 457 len -= sizeof(info); 458 if (WARN_ON_ONCE(len < sizeof(handle))) 459 return -EFAULT; 460 461 handle.handle_type = fh->type; 462 handle.handle_bytes = fh_len; 463 464 /* Mangle handle_type for bad file_handle */ 465 if (!fh_len) 466 handle.handle_type = FILEID_INVALID; 467 468 if (copy_to_user(buf, &handle, sizeof(handle))) 469 return -EFAULT; 470 471 buf += sizeof(handle); 472 len -= sizeof(handle); 473 if (WARN_ON_ONCE(len < fh_len)) 474 return -EFAULT; 475 476 /* 477 * For an inline fh and inline file name, copy through stack to exclude 478 * the copy from usercopy hardening protections. 479 */ 480 fh_buf = fanotify_fh_buf(fh); 481 if (fh_len <= FANOTIFY_INLINE_FH_LEN) { 482 memcpy(bounce, fh_buf, fh_len); 483 fh_buf = bounce; 484 } 485 if (copy_to_user(buf, fh_buf, fh_len)) 486 return -EFAULT; 487 488 buf += fh_len; 489 len -= fh_len; 490 491 if (name_len) { 492 /* Copy the filename with terminating null */ 493 name_len++; 494 if (WARN_ON_ONCE(len < name_len)) 495 return -EFAULT; 496 497 if (copy_to_user(buf, name, name_len)) 498 return -EFAULT; 499 500 buf += name_len; 501 len -= name_len; 502 } 503 504 /* Pad with 0's */ 505 WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN); 506 if (len > 0 && clear_user(buf, len)) 507 return -EFAULT; 508 509 return info_len; 510} 511 512static int copy_pidfd_info_to_user(int pidfd, 513 char __user *buf, 514 size_t count) 515{ 516 struct fanotify_event_info_pidfd info = { }; 517 size_t info_len = FANOTIFY_PIDFD_INFO_HDR_LEN; 518 519 if (WARN_ON_ONCE(info_len > count)) 520 return -EFAULT; 521 522 info.hdr.info_type = FAN_EVENT_INFO_TYPE_PIDFD; 523 info.hdr.len = info_len; 524 info.pidfd = pidfd; 525 526 if (copy_to_user(buf, &info, info_len)) 527 return -EFAULT; 528 529 return info_len; 530} 531 532static int copy_info_records_to_user(struct fanotify_event *event, 533 struct fanotify_info *info, 534 unsigned int info_mode, int pidfd, 535 char __user *buf, size_t count) 536{ 537 int ret, total_bytes = 0, info_type = 0; 538 unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS; 539 unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; 540 541 /* 542 * Event info records order is as follows: 543 * 1. dir fid + name 544 * 2. (optional) new dir fid + new name 545 * 3. (optional) child fid 546 */ 547 if (fanotify_event_has_dir_fh(event)) { 548 info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME : 549 FAN_EVENT_INFO_TYPE_DFID; 550 551 /* FAN_RENAME uses special info types */ 552 if (event->mask & FAN_RENAME) 553 info_type = FAN_EVENT_INFO_TYPE_OLD_DFID_NAME; 554 555 ret = copy_fid_info_to_user(fanotify_event_fsid(event), 556 fanotify_info_dir_fh(info), 557 info_type, 558 fanotify_info_name(info), 559 info->name_len, buf, count); 560 if (ret < 0) 561 return ret; 562 563 buf += ret; 564 count -= ret; 565 total_bytes += ret; 566 } 567 568 /* New dir fid+name may be reported in addition to old dir fid+name */ 569 if (fanotify_event_has_dir2_fh(event)) { 570 info_type = FAN_EVENT_INFO_TYPE_NEW_DFID_NAME; 571 ret = copy_fid_info_to_user(fanotify_event_fsid(event), 572 fanotify_info_dir2_fh(info), 573 info_type, 574 fanotify_info_name2(info), 575 info->name2_len, buf, count); 576 if (ret < 0) 577 return ret; 578 579 buf += ret; 580 count -= ret; 581 total_bytes += ret; 582 } 583 584 if (fanotify_event_has_object_fh(event)) { 585 const char *dot = NULL; 586 int dot_len = 0; 587 588 if (fid_mode == FAN_REPORT_FID || info_type) { 589 /* 590 * With only group flag FAN_REPORT_FID only type FID is 591 * reported. Second info record type is always FID. 592 */ 593 info_type = FAN_EVENT_INFO_TYPE_FID; 594 } else if ((fid_mode & FAN_REPORT_NAME) && 595 (event->mask & FAN_ONDIR)) { 596 /* 597 * With group flag FAN_REPORT_NAME, if name was not 598 * recorded in an event on a directory, report the name 599 * "." with info type DFID_NAME. 600 */ 601 info_type = FAN_EVENT_INFO_TYPE_DFID_NAME; 602 dot = "."; 603 dot_len = 1; 604 } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) || 605 (event->mask & FAN_ONDIR)) { 606 /* 607 * With group flag FAN_REPORT_DIR_FID, a single info 608 * record has type DFID for directory entry modification 609 * event and for event on a directory. 610 */ 611 info_type = FAN_EVENT_INFO_TYPE_DFID; 612 } else { 613 /* 614 * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID, 615 * a single info record has type FID for event on a 616 * non-directory, when there is no directory to report. 617 * For example, on FAN_DELETE_SELF event. 618 */ 619 info_type = FAN_EVENT_INFO_TYPE_FID; 620 } 621 622 ret = copy_fid_info_to_user(fanotify_event_fsid(event), 623 fanotify_event_object_fh(event), 624 info_type, dot, dot_len, 625 buf, count); 626 if (ret < 0) 627 return ret; 628 629 buf += ret; 630 count -= ret; 631 total_bytes += ret; 632 } 633 634 if (pidfd_mode) { 635 ret = copy_pidfd_info_to_user(pidfd, buf, count); 636 if (ret < 0) 637 return ret; 638 639 buf += ret; 640 count -= ret; 641 total_bytes += ret; 642 } 643 644 if (fanotify_is_error_event(event->mask)) { 645 ret = copy_error_info_to_user(event, buf, count); 646 if (ret < 0) 647 return ret; 648 buf += ret; 649 count -= ret; 650 total_bytes += ret; 651 } 652 653 return total_bytes; 654} 655 656static ssize_t copy_event_to_user(struct fsnotify_group *group, 657 struct fanotify_event *event, 658 char __user *buf, size_t count) 659{ 660 struct fanotify_event_metadata metadata; 661 const struct path *path = fanotify_event_path(event); 662 struct fanotify_info *info = fanotify_event_info(event); 663 unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); 664 unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; 665 struct file *f = NULL, *pidfd_file = NULL; 666 int ret, pidfd = FAN_NOPIDFD, fd = FAN_NOFD; 667 668 pr_debug("%s: group=%p event=%p\n", __func__, group, event); 669 670 metadata.event_len = fanotify_event_len(info_mode, event); 671 metadata.metadata_len = FAN_EVENT_METADATA_LEN; 672 metadata.vers = FANOTIFY_METADATA_VERSION; 673 metadata.reserved = 0; 674 metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS; 675 metadata.pid = pid_vnr(event->pid); 676 /* 677 * For an unprivileged listener, event->pid can be used to identify the 678 * events generated by the listener process itself, without disclosing 679 * the pids of other processes. 680 */ 681 if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && 682 task_tgid(current) != event->pid) 683 metadata.pid = 0; 684 685 /* 686 * For now, fid mode is required for an unprivileged listener and 687 * fid mode does not report fd in events. Keep this check anyway 688 * for safety in case fid mode requirement is relaxed in the future 689 * to allow unprivileged listener to get events with no fd and no fid. 690 */ 691 if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && 692 path && path->mnt && path->dentry) { 693 fd = create_fd(group, path, &f); 694 if (fd < 0) 695 return fd; 696 } 697 metadata.fd = fd; 698 699 if (pidfd_mode) { 700 /* 701 * Complain if the FAN_REPORT_PIDFD and FAN_REPORT_TID mutual 702 * exclusion is ever lifted. At the time of incoporating pidfd 703 * support within fanotify, the pidfd API only supported the 704 * creation of pidfds for thread-group leaders. 705 */ 706 WARN_ON_ONCE(FAN_GROUP_FLAG(group, FAN_REPORT_TID)); 707 708 /* 709 * The PIDTYPE_TGID check for an event->pid is performed 710 * preemptively in an attempt to catch out cases where the event 711 * listener reads events after the event generating process has 712 * already terminated. Report FAN_NOPIDFD to the event listener 713 * in those cases, with all other pidfd creation errors being 714 * reported as FAN_EPIDFD. 715 */ 716 if (metadata.pid == 0 || 717 !pid_has_task(event->pid, PIDTYPE_TGID)) { 718 pidfd = FAN_NOPIDFD; 719 } else { 720 pidfd = pidfd_prepare(event->pid, 0, &pidfd_file); 721 if (pidfd < 0) 722 pidfd = FAN_EPIDFD; 723 } 724 } 725 726 ret = -EFAULT; 727 /* 728 * Sanity check copy size in case get_one_event() and 729 * event_len sizes ever get out of sync. 730 */ 731 if (WARN_ON_ONCE(metadata.event_len > count)) 732 goto out_close_fd; 733 734 if (copy_to_user(buf, &metadata, FAN_EVENT_METADATA_LEN)) 735 goto out_close_fd; 736 737 buf += FAN_EVENT_METADATA_LEN; 738 count -= FAN_EVENT_METADATA_LEN; 739 740 if (fanotify_is_perm_event(event->mask)) 741 FANOTIFY_PERM(event)->fd = fd; 742 743 if (info_mode) { 744 ret = copy_info_records_to_user(event, info, info_mode, pidfd, 745 buf, count); 746 if (ret < 0) 747 goto out_close_fd; 748 } 749 750 if (f) 751 fd_install(fd, f); 752 753 if (pidfd_file) 754 fd_install(pidfd, pidfd_file); 755 756 return metadata.event_len; 757 758out_close_fd: 759 if (fd != FAN_NOFD) { 760 put_unused_fd(fd); 761 fput(f); 762 } 763 764 if (pidfd >= 0) { 765 put_unused_fd(pidfd); 766 fput(pidfd_file); 767 } 768 769 return ret; 770} 771 772/* intofiy userspace file descriptor functions */ 773static __poll_t fanotify_poll(struct file *file, poll_table *wait) 774{ 775 struct fsnotify_group *group = file->private_data; 776 __poll_t ret = 0; 777 778 poll_wait(file, &group->notification_waitq, wait); 779 spin_lock(&group->notification_lock); 780 if (!fsnotify_notify_queue_is_empty(group)) 781 ret = EPOLLIN | EPOLLRDNORM; 782 spin_unlock(&group->notification_lock); 783 784 return ret; 785} 786 787static ssize_t fanotify_read(struct file *file, char __user *buf, 788 size_t count, loff_t *pos) 789{ 790 struct fsnotify_group *group; 791 struct fanotify_event *event; 792 char __user *start; 793 int ret; 794 DEFINE_WAIT_FUNC(wait, woken_wake_function); 795 796 start = buf; 797 group = file->private_data; 798 799 pr_debug("%s: group=%p\n", __func__, group); 800 801 add_wait_queue(&group->notification_waitq, &wait); 802 while (1) { 803 /* 804 * User can supply arbitrarily large buffer. Avoid softlockups 805 * in case there are lots of available events. 806 */ 807 cond_resched(); 808 event = get_one_event(group, count); 809 if (IS_ERR(event)) { 810 ret = PTR_ERR(event); 811 break; 812 } 813 814 if (!event) { 815 ret = -EAGAIN; 816 if (file->f_flags & O_NONBLOCK) 817 break; 818 819 ret = -ERESTARTSYS; 820 if (signal_pending(current)) 821 break; 822 823 if (start != buf) 824 break; 825 826 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 827 continue; 828 } 829 830 ret = copy_event_to_user(group, event, buf, count); 831 if (unlikely(ret == -EOPENSTALE)) { 832 /* 833 * We cannot report events with stale fd so drop it. 834 * Setting ret to 0 will continue the event loop and 835 * do the right thing if there are no more events to 836 * read (i.e. return bytes read, -EAGAIN or wait). 837 */ 838 ret = 0; 839 } 840 841 /* 842 * Permission events get queued to wait for response. Other 843 * events can be destroyed now. 844 */ 845 if (!fanotify_is_perm_event(event->mask)) { 846 fsnotify_destroy_event(group, &event->fse); 847 } else { 848 if (ret <= 0) { 849 spin_lock(&group->notification_lock); 850 finish_permission_event(group, 851 FANOTIFY_PERM(event), FAN_DENY, NULL); 852 wake_up(&group->fanotify_data.access_waitq); 853 } else { 854 spin_lock(&group->notification_lock); 855 list_add_tail(&event->fse.list, 856 &group->fanotify_data.access_list); 857 spin_unlock(&group->notification_lock); 858 } 859 } 860 if (ret < 0) 861 break; 862 buf += ret; 863 count -= ret; 864 } 865 remove_wait_queue(&group->notification_waitq, &wait); 866 867 if (start != buf && ret != -EFAULT) 868 ret = buf - start; 869 return ret; 870} 871 872static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) 873{ 874 struct fanotify_response response; 875 struct fsnotify_group *group; 876 int ret; 877 const char __user *info_buf = buf + sizeof(struct fanotify_response); 878 size_t info_len; 879 880 if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) 881 return -EINVAL; 882 883 group = file->private_data; 884 885 pr_debug("%s: group=%p count=%zu\n", __func__, group, count); 886 887 if (count < sizeof(response)) 888 return -EINVAL; 889 890 if (copy_from_user(&response, buf, sizeof(response))) 891 return -EFAULT; 892 893 info_len = count - sizeof(response); 894 895 ret = process_access_response(group, &response, info_buf, info_len); 896 if (ret < 0) 897 count = ret; 898 else 899 count = sizeof(response) + ret; 900 901 return count; 902} 903 904static int fanotify_release(struct inode *ignored, struct file *file) 905{ 906 struct fsnotify_group *group = file->private_data; 907 struct fsnotify_event *fsn_event; 908 909 /* 910 * Stop new events from arriving in the notification queue. since 911 * userspace cannot use fanotify fd anymore, no event can enter or 912 * leave access_list by now either. 913 */ 914 fsnotify_group_stop_queueing(group); 915 916 /* 917 * Process all permission events on access_list and notification queue 918 * and simulate reply from userspace. 919 */ 920 spin_lock(&group->notification_lock); 921 while (!list_empty(&group->fanotify_data.access_list)) { 922 struct fanotify_perm_event *event; 923 924 event = list_first_entry(&group->fanotify_data.access_list, 925 struct fanotify_perm_event, fae.fse.list); 926 list_del_init(&event->fae.fse.list); 927 finish_permission_event(group, event, FAN_ALLOW, NULL); 928 spin_lock(&group->notification_lock); 929 } 930 931 /* 932 * Destroy all non-permission events. For permission events just 933 * dequeue them and set the response. They will be freed once the 934 * response is consumed and fanotify_get_response() returns. 935 */ 936 while ((fsn_event = fsnotify_remove_first_event(group))) { 937 struct fanotify_event *event = FANOTIFY_E(fsn_event); 938 939 if (!(event->mask & FANOTIFY_PERM_EVENTS)) { 940 spin_unlock(&group->notification_lock); 941 fsnotify_destroy_event(group, fsn_event); 942 } else { 943 finish_permission_event(group, FANOTIFY_PERM(event), 944 FAN_ALLOW, NULL); 945 } 946 spin_lock(&group->notification_lock); 947 } 948 spin_unlock(&group->notification_lock); 949 950 /* Response for all permission events it set, wakeup waiters */ 951 wake_up(&group->fanotify_data.access_waitq); 952 953 /* matches the fanotify_init->fsnotify_alloc_group */ 954 fsnotify_destroy_group(group); 955 956 return 0; 957} 958 959static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 960{ 961 struct fsnotify_group *group; 962 struct fsnotify_event *fsn_event; 963 void __user *p; 964 int ret = -ENOTTY; 965 size_t send_len = 0; 966 967 group = file->private_data; 968 969 p = (void __user *) arg; 970 971 switch (cmd) { 972 case FIONREAD: 973 spin_lock(&group->notification_lock); 974 list_for_each_entry(fsn_event, &group->notification_list, list) 975 send_len += FAN_EVENT_METADATA_LEN; 976 spin_unlock(&group->notification_lock); 977 ret = put_user(send_len, (int __user *) p); 978 break; 979 } 980 981 return ret; 982} 983 984static const struct file_operations fanotify_fops = { 985 .show_fdinfo = fanotify_show_fdinfo, 986 .poll = fanotify_poll, 987 .read = fanotify_read, 988 .write = fanotify_write, 989 .fasync = NULL, 990 .release = fanotify_release, 991 .unlocked_ioctl = fanotify_ioctl, 992 .compat_ioctl = compat_ptr_ioctl, 993 .llseek = noop_llseek, 994}; 995 996static int fanotify_find_path(int dfd, const char __user *filename, 997 struct path *path, unsigned int flags, __u64 mask, 998 unsigned int obj_type) 999{ 1000 int ret; 1001 1002 pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, 1003 dfd, filename, flags); 1004 1005 if (filename == NULL) { 1006 struct fd f = fdget(dfd); 1007 1008 ret = -EBADF; 1009 if (!f.file) 1010 goto out; 1011 1012 ret = -ENOTDIR; 1013 if ((flags & FAN_MARK_ONLYDIR) && 1014 !(S_ISDIR(file_inode(f.file)->i_mode))) { 1015 fdput(f); 1016 goto out; 1017 } 1018 1019 *path = f.file->f_path; 1020 path_get(path); 1021 fdput(f); 1022 } else { 1023 unsigned int lookup_flags = 0; 1024 1025 if (!(flags & FAN_MARK_DONT_FOLLOW)) 1026 lookup_flags |= LOOKUP_FOLLOW; 1027 if (flags & FAN_MARK_ONLYDIR) 1028 lookup_flags |= LOOKUP_DIRECTORY; 1029 1030 ret = user_path_at(dfd, filename, lookup_flags, path); 1031 if (ret) 1032 goto out; 1033 } 1034 1035 /* you can only watch an inode if you have read permissions on it */ 1036 ret = path_permission(path, MAY_READ); 1037 if (ret) { 1038 path_put(path); 1039 goto out; 1040 } 1041 1042 ret = security_path_notify(path, mask, obj_type); 1043 if (ret) 1044 path_put(path); 1045 1046out: 1047 return ret; 1048} 1049 1050static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, 1051 __u32 mask, unsigned int flags, 1052 __u32 umask, int *destroy) 1053{ 1054 __u32 oldmask, newmask; 1055 1056 /* umask bits cannot be removed by user */ 1057 mask &= ~umask; 1058 spin_lock(&fsn_mark->lock); 1059 oldmask = fsnotify_calc_mask(fsn_mark); 1060 if (!(flags & FANOTIFY_MARK_IGNORE_BITS)) { 1061 fsn_mark->mask &= ~mask; 1062 } else { 1063 fsn_mark->ignore_mask &= ~mask; 1064 } 1065 newmask = fsnotify_calc_mask(fsn_mark); 1066 /* 1067 * We need to keep the mark around even if remaining mask cannot 1068 * result in any events (e.g. mask == FAN_ONDIR) to support incremenal 1069 * changes to the mask. 1070 * Destroy mark when only umask bits remain. 1071 */ 1072 *destroy = !((fsn_mark->mask | fsn_mark->ignore_mask) & ~umask); 1073 spin_unlock(&fsn_mark->lock); 1074 1075 return oldmask & ~newmask; 1076} 1077 1078static int fanotify_remove_mark(struct fsnotify_group *group, 1079 void *obj, unsigned int obj_type, __u32 mask, 1080 unsigned int flags, __u32 umask) 1081{ 1082 struct fsnotify_mark *fsn_mark = NULL; 1083 __u32 removed; 1084 int destroy_mark; 1085 1086 fsnotify_group_lock(group); 1087 fsn_mark = fsnotify_find_mark(obj, obj_type, group); 1088 if (!fsn_mark) { 1089 fsnotify_group_unlock(group); 1090 return -ENOENT; 1091 } 1092 1093 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, 1094 umask, &destroy_mark); 1095 if (removed & fsnotify_conn_mask(fsn_mark->connector)) 1096 fsnotify_recalc_mask(fsn_mark->connector); 1097 if (destroy_mark) 1098 fsnotify_detach_mark(fsn_mark); 1099 fsnotify_group_unlock(group); 1100 if (destroy_mark) 1101 fsnotify_free_mark(fsn_mark); 1102 1103 /* matches the fsnotify_find_mark() */ 1104 fsnotify_put_mark(fsn_mark); 1105 return 0; 1106} 1107 1108static bool fanotify_mark_update_flags(struct fsnotify_mark *fsn_mark, 1109 unsigned int fan_flags) 1110{ 1111 bool want_iref = !(fan_flags & FAN_MARK_EVICTABLE); 1112 unsigned int ignore = fan_flags & FANOTIFY_MARK_IGNORE_BITS; 1113 bool recalc = false; 1114 1115 /* 1116 * When using FAN_MARK_IGNORE for the first time, mark starts using 1117 * independent event flags in ignore mask. After that, trying to 1118 * update the ignore mask with the old FAN_MARK_IGNORED_MASK API 1119 * will result in EEXIST error. 1120 */ 1121 if (ignore == FAN_MARK_IGNORE) 1122 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS; 1123 1124 /* 1125 * Setting FAN_MARK_IGNORED_SURV_MODIFY for the first time may lead to 1126 * the removal of the FS_MODIFY bit in calculated mask if it was set 1127 * because of an ignore mask that is now going to survive FS_MODIFY. 1128 */ 1129 if (ignore && (fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) && 1130 !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) { 1131 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; 1132 if (!(fsn_mark->mask & FS_MODIFY)) 1133 recalc = true; 1134 } 1135 1136 if (fsn_mark->connector->type != FSNOTIFY_OBJ_TYPE_INODE || 1137 want_iref == !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)) 1138 return recalc; 1139 1140 /* 1141 * NO_IREF may be removed from a mark, but not added. 1142 * When removed, fsnotify_recalc_mask() will take the inode ref. 1143 */ 1144 WARN_ON_ONCE(!want_iref); 1145 fsn_mark->flags &= ~FSNOTIFY_MARK_FLAG_NO_IREF; 1146 1147 return true; 1148} 1149 1150static bool fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, 1151 __u32 mask, unsigned int fan_flags) 1152{ 1153 bool recalc; 1154 1155 spin_lock(&fsn_mark->lock); 1156 if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS)) 1157 fsn_mark->mask |= mask; 1158 else 1159 fsn_mark->ignore_mask |= mask; 1160 1161 recalc = fsnotify_calc_mask(fsn_mark) & 1162 ~fsnotify_conn_mask(fsn_mark->connector); 1163 1164 recalc |= fanotify_mark_update_flags(fsn_mark, fan_flags); 1165 spin_unlock(&fsn_mark->lock); 1166 1167 return recalc; 1168} 1169 1170struct fan_fsid { 1171 struct super_block *sb; 1172 __kernel_fsid_t id; 1173 bool weak; 1174}; 1175 1176static int fanotify_set_mark_fsid(struct fsnotify_group *group, 1177 struct fsnotify_mark *mark, 1178 struct fan_fsid *fsid) 1179{ 1180 struct fsnotify_mark_connector *conn; 1181 struct fsnotify_mark *old; 1182 struct super_block *old_sb = NULL; 1183 1184 FANOTIFY_MARK(mark)->fsid = fsid->id; 1185 mark->flags |= FSNOTIFY_MARK_FLAG_HAS_FSID; 1186 if (fsid->weak) 1187 mark->flags |= FSNOTIFY_MARK_FLAG_WEAK_FSID; 1188 1189 /* First mark added will determine if group is single or multi fsid */ 1190 if (list_empty(&group->marks_list)) 1191 return 0; 1192 1193 /* Find sb of an existing mark */ 1194 list_for_each_entry(old, &group->marks_list, g_list) { 1195 conn = READ_ONCE(old->connector); 1196 if (!conn) 1197 continue; 1198 old_sb = fsnotify_connector_sb(conn); 1199 if (old_sb) 1200 break; 1201 } 1202 1203 /* Only detached marks left? */ 1204 if (!old_sb) 1205 return 0; 1206 1207 /* Do not allow mixing of marks with weak and strong fsid */ 1208 if ((mark->flags ^ old->flags) & FSNOTIFY_MARK_FLAG_WEAK_FSID) 1209 return -EXDEV; 1210 1211 /* Allow mixing of marks with strong fsid from different fs */ 1212 if (!fsid->weak) 1213 return 0; 1214 1215 /* Do not allow mixing marks with weak fsid from different fs */ 1216 if (old_sb != fsid->sb) 1217 return -EXDEV; 1218 1219 /* Do not allow mixing marks from different btrfs sub-volumes */ 1220 if (!fanotify_fsid_equal(&FANOTIFY_MARK(old)->fsid, 1221 &FANOTIFY_MARK(mark)->fsid)) 1222 return -EXDEV; 1223 1224 return 0; 1225} 1226 1227static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, 1228 void *obj, 1229 unsigned int obj_type, 1230 unsigned int fan_flags, 1231 struct fan_fsid *fsid) 1232{ 1233 struct ucounts *ucounts = group->fanotify_data.ucounts; 1234 struct fanotify_mark *fan_mark; 1235 struct fsnotify_mark *mark; 1236 int ret; 1237 1238 /* 1239 * Enforce per user marks limits per user in all containing user ns. 1240 * A group with FAN_UNLIMITED_MARKS does not contribute to mark count 1241 * in the limited groups account. 1242 */ 1243 if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS) && 1244 !inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_FANOTIFY_MARKS)) 1245 return ERR_PTR(-ENOSPC); 1246 1247 fan_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); 1248 if (!fan_mark) { 1249 ret = -ENOMEM; 1250 goto out_dec_ucounts; 1251 } 1252 1253 mark = &fan_mark->fsn_mark; 1254 fsnotify_init_mark(mark, group); 1255 if (fan_flags & FAN_MARK_EVICTABLE) 1256 mark->flags |= FSNOTIFY_MARK_FLAG_NO_IREF; 1257 1258 /* Cache fsid of filesystem containing the marked object */ 1259 if (fsid) { 1260 ret = fanotify_set_mark_fsid(group, mark, fsid); 1261 if (ret) 1262 goto out_put_mark; 1263 } else { 1264 fan_mark->fsid.val[0] = fan_mark->fsid.val[1] = 0; 1265 } 1266 1267 ret = fsnotify_add_mark_locked(mark, obj, obj_type, 0); 1268 if (ret) 1269 goto out_put_mark; 1270 1271 return mark; 1272 1273out_put_mark: 1274 fsnotify_put_mark(mark); 1275out_dec_ucounts: 1276 if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS)) 1277 dec_ucount(ucounts, UCOUNT_FANOTIFY_MARKS); 1278 return ERR_PTR(ret); 1279} 1280 1281static int fanotify_group_init_error_pool(struct fsnotify_group *group) 1282{ 1283 if (mempool_initialized(&group->fanotify_data.error_events_pool)) 1284 return 0; 1285 1286 return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool, 1287 FANOTIFY_DEFAULT_FEE_POOL_SIZE, 1288 sizeof(struct fanotify_error_event)); 1289} 1290 1291static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark, 1292 unsigned int fan_flags) 1293{ 1294 /* 1295 * Non evictable mark cannot be downgraded to evictable mark. 1296 */ 1297 if (fan_flags & FAN_MARK_EVICTABLE && 1298 !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)) 1299 return -EEXIST; 1300 1301 /* 1302 * New ignore mask semantics cannot be downgraded to old semantics. 1303 */ 1304 if (fan_flags & FAN_MARK_IGNORED_MASK && 1305 fsn_mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS) 1306 return -EEXIST; 1307 1308 /* 1309 * An ignore mask that survives modify could never be downgraded to not 1310 * survive modify. With new FAN_MARK_IGNORE semantics we make that rule 1311 * explicit and return an error when trying to update the ignore mask 1312 * without the original FAN_MARK_IGNORED_SURV_MODIFY value. 1313 */ 1314 if (fan_flags & FAN_MARK_IGNORE && 1315 !(fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) && 1316 fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY) 1317 return -EEXIST; 1318 1319 return 0; 1320} 1321 1322static int fanotify_add_mark(struct fsnotify_group *group, 1323 void *obj, unsigned int obj_type, 1324 __u32 mask, unsigned int fan_flags, 1325 struct fan_fsid *fsid) 1326{ 1327 struct fsnotify_mark *fsn_mark; 1328 bool recalc; 1329 int ret = 0; 1330 1331 fsnotify_group_lock(group); 1332 fsn_mark = fsnotify_find_mark(obj, obj_type, group); 1333 if (!fsn_mark) { 1334 fsn_mark = fanotify_add_new_mark(group, obj, obj_type, 1335 fan_flags, fsid); 1336 if (IS_ERR(fsn_mark)) { 1337 fsnotify_group_unlock(group); 1338 return PTR_ERR(fsn_mark); 1339 } 1340 } 1341 1342 /* 1343 * Check if requested mark flags conflict with an existing mark flags. 1344 */ 1345 ret = fanotify_may_update_existing_mark(fsn_mark, fan_flags); 1346 if (ret) 1347 goto out; 1348 1349 /* 1350 * Error events are pre-allocated per group, only if strictly 1351 * needed (i.e. FAN_FS_ERROR was requested). 1352 */ 1353 if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS) && 1354 (mask & FAN_FS_ERROR)) { 1355 ret = fanotify_group_init_error_pool(group); 1356 if (ret) 1357 goto out; 1358 } 1359 1360 recalc = fanotify_mark_add_to_mask(fsn_mark, mask, fan_flags); 1361 if (recalc) 1362 fsnotify_recalc_mask(fsn_mark->connector); 1363 1364out: 1365 fsnotify_group_unlock(group); 1366 1367 fsnotify_put_mark(fsn_mark); 1368 return ret; 1369} 1370 1371static struct fsnotify_event *fanotify_alloc_overflow_event(void) 1372{ 1373 struct fanotify_event *oevent; 1374 1375 oevent = kmalloc(sizeof(*oevent), GFP_KERNEL_ACCOUNT); 1376 if (!oevent) 1377 return NULL; 1378 1379 fanotify_init_event(oevent, 0, FS_Q_OVERFLOW); 1380 oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW; 1381 1382 return &oevent->fse; 1383} 1384 1385static struct hlist_head *fanotify_alloc_merge_hash(void) 1386{ 1387 struct hlist_head *hash; 1388 1389 hash = kmalloc(sizeof(struct hlist_head) << FANOTIFY_HTABLE_BITS, 1390 GFP_KERNEL_ACCOUNT); 1391 if (!hash) 1392 return NULL; 1393 1394 __hash_init(hash, FANOTIFY_HTABLE_SIZE); 1395 1396 return hash; 1397} 1398 1399/* fanotify syscalls */ 1400SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 1401{ 1402 struct fsnotify_group *group; 1403 int f_flags, fd; 1404 unsigned int fid_mode = flags & FANOTIFY_FID_BITS; 1405 unsigned int class = flags & FANOTIFY_CLASS_BITS; 1406 unsigned int internal_flags = 0; 1407 1408 pr_debug("%s: flags=%x event_f_flags=%x\n", 1409 __func__, flags, event_f_flags); 1410 1411 if (!capable(CAP_SYS_ADMIN)) { 1412 /* 1413 * An unprivileged user can setup an fanotify group with 1414 * limited functionality - an unprivileged group is limited to 1415 * notification events with file handles and it cannot use 1416 * unlimited queue/marks. 1417 */ 1418 if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) || !fid_mode) 1419 return -EPERM; 1420 1421 /* 1422 * Setting the internal flag FANOTIFY_UNPRIV on the group 1423 * prevents setting mount/filesystem marks on this group and 1424 * prevents reporting pid and open fd in events. 1425 */ 1426 internal_flags |= FANOTIFY_UNPRIV; 1427 } 1428 1429#ifdef CONFIG_AUDITSYSCALL 1430 if (flags & ~(FANOTIFY_INIT_FLAGS | FAN_ENABLE_AUDIT)) 1431#else 1432 if (flags & ~FANOTIFY_INIT_FLAGS) 1433#endif 1434 return -EINVAL; 1435 1436 /* 1437 * A pidfd can only be returned for a thread-group leader; thus 1438 * FAN_REPORT_PIDFD and FAN_REPORT_TID need to remain mutually 1439 * exclusive. 1440 */ 1441 if ((flags & FAN_REPORT_PIDFD) && (flags & FAN_REPORT_TID)) 1442 return -EINVAL; 1443 1444 if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) 1445 return -EINVAL; 1446 1447 switch (event_f_flags & O_ACCMODE) { 1448 case O_RDONLY: 1449 case O_RDWR: 1450 case O_WRONLY: 1451 break; 1452 default: 1453 return -EINVAL; 1454 } 1455 1456 if (fid_mode && class != FAN_CLASS_NOTIF) 1457 return -EINVAL; 1458 1459 /* 1460 * Child name is reported with parent fid so requires dir fid. 1461 * We can report both child fid and dir fid with or without name. 1462 */ 1463 if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID)) 1464 return -EINVAL; 1465 1466 /* 1467 * FAN_REPORT_TARGET_FID requires FAN_REPORT_NAME and FAN_REPORT_FID 1468 * and is used as an indication to report both dir and child fid on all 1469 * dirent events. 1470 */ 1471 if ((fid_mode & FAN_REPORT_TARGET_FID) && 1472 (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID))) 1473 return -EINVAL; 1474 1475 f_flags = O_RDWR | __FMODE_NONOTIFY; 1476 if (flags & FAN_CLOEXEC) 1477 f_flags |= O_CLOEXEC; 1478 if (flags & FAN_NONBLOCK) 1479 f_flags |= O_NONBLOCK; 1480 1481 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ 1482 group = fsnotify_alloc_group(&fanotify_fsnotify_ops, 1483 FSNOTIFY_GROUP_USER | FSNOTIFY_GROUP_NOFS); 1484 if (IS_ERR(group)) { 1485 return PTR_ERR(group); 1486 } 1487 1488 /* Enforce groups limits per user in all containing user ns */ 1489 group->fanotify_data.ucounts = inc_ucount(current_user_ns(), 1490 current_euid(), 1491 UCOUNT_FANOTIFY_GROUPS); 1492 if (!group->fanotify_data.ucounts) { 1493 fd = -EMFILE; 1494 goto out_destroy_group; 1495 } 1496 1497 group->fanotify_data.flags = flags | internal_flags; 1498 group->memcg = get_mem_cgroup_from_mm(current->mm); 1499 1500 group->fanotify_data.merge_hash = fanotify_alloc_merge_hash(); 1501 if (!group->fanotify_data.merge_hash) { 1502 fd = -ENOMEM; 1503 goto out_destroy_group; 1504 } 1505 1506 group->overflow_event = fanotify_alloc_overflow_event(); 1507 if (unlikely(!group->overflow_event)) { 1508 fd = -ENOMEM; 1509 goto out_destroy_group; 1510 } 1511 1512 if (force_o_largefile()) 1513 event_f_flags |= O_LARGEFILE; 1514 group->fanotify_data.f_flags = event_f_flags; 1515 init_waitqueue_head(&group->fanotify_data.access_waitq); 1516 INIT_LIST_HEAD(&group->fanotify_data.access_list); 1517 switch (class) { 1518 case FAN_CLASS_NOTIF: 1519 group->priority = FSNOTIFY_PRIO_NORMAL; 1520 break; 1521 case FAN_CLASS_CONTENT: 1522 group->priority = FSNOTIFY_PRIO_CONTENT; 1523 break; 1524 case FAN_CLASS_PRE_CONTENT: 1525 group->priority = FSNOTIFY_PRIO_PRE_CONTENT; 1526 break; 1527 default: 1528 fd = -EINVAL; 1529 goto out_destroy_group; 1530 } 1531 1532 if (flags & FAN_UNLIMITED_QUEUE) { 1533 fd = -EPERM; 1534 if (!capable(CAP_SYS_ADMIN)) 1535 goto out_destroy_group; 1536 group->max_events = UINT_MAX; 1537 } else { 1538 group->max_events = fanotify_max_queued_events; 1539 } 1540 1541 if (flags & FAN_UNLIMITED_MARKS) { 1542 fd = -EPERM; 1543 if (!capable(CAP_SYS_ADMIN)) 1544 goto out_destroy_group; 1545 } 1546 1547 if (flags & FAN_ENABLE_AUDIT) { 1548 fd = -EPERM; 1549 if (!capable(CAP_AUDIT_WRITE)) 1550 goto out_destroy_group; 1551 } 1552 1553 fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); 1554 if (fd < 0) 1555 goto out_destroy_group; 1556 1557 return fd; 1558 1559out_destroy_group: 1560 fsnotify_destroy_group(group); 1561 return fd; 1562} 1563 1564static int fanotify_test_fsid(struct dentry *dentry, unsigned int flags, 1565 struct fan_fsid *fsid) 1566{ 1567 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; 1568 __kernel_fsid_t root_fsid; 1569 int err; 1570 1571 /* 1572 * Make sure dentry is not of a filesystem with zero fsid (e.g. fuse). 1573 */ 1574 err = vfs_get_fsid(dentry, &fsid->id); 1575 if (err) 1576 return err; 1577 1578 fsid->sb = dentry->d_sb; 1579 if (!fsid->id.val[0] && !fsid->id.val[1]) { 1580 err = -ENODEV; 1581 goto weak; 1582 } 1583 1584 /* 1585 * Make sure dentry is not of a filesystem subvolume (e.g. btrfs) 1586 * which uses a different fsid than sb root. 1587 */ 1588 err = vfs_get_fsid(dentry->d_sb->s_root, &root_fsid); 1589 if (err) 1590 return err; 1591 1592 if (!fanotify_fsid_equal(&root_fsid, &fsid->id)) { 1593 err = -EXDEV; 1594 goto weak; 1595 } 1596 1597 fsid->weak = false; 1598 return 0; 1599 1600weak: 1601 /* Allow weak fsid when marking inodes */ 1602 fsid->weak = true; 1603 return (mark_type == FAN_MARK_INODE) ? 0 : err; 1604} 1605 1606/* Check if filesystem can encode a unique fid */ 1607static int fanotify_test_fid(struct dentry *dentry, unsigned int flags) 1608{ 1609 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; 1610 const struct export_operations *nop = dentry->d_sb->s_export_op; 1611 1612 /* 1613 * We need to make sure that the filesystem supports encoding of 1614 * file handles so user can use name_to_handle_at() to compare fids 1615 * reported with events to the file handle of watched objects. 1616 */ 1617 if (!exportfs_can_encode_fid(nop)) 1618 return -EOPNOTSUPP; 1619 1620 /* 1621 * For sb/mount mark, we also need to make sure that the filesystem 1622 * supports decoding file handles, so user has a way to map back the 1623 * reported fids to filesystem objects. 1624 */ 1625 if (mark_type != FAN_MARK_INODE && !exportfs_can_decode_fh(nop)) 1626 return -EOPNOTSUPP; 1627 1628 return 0; 1629} 1630 1631static int fanotify_events_supported(struct fsnotify_group *group, 1632 const struct path *path, __u64 mask, 1633 unsigned int flags) 1634{ 1635 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; 1636 /* Strict validation of events in non-dir inode mask with v5.17+ APIs */ 1637 bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) || 1638 (mask & FAN_RENAME) || 1639 (flags & FAN_MARK_IGNORE); 1640 1641 /* 1642 * Some filesystems such as 'proc' acquire unusual locks when opening 1643 * files. For them fanotify permission events have high chances of 1644 * deadlocking the system - open done when reporting fanotify event 1645 * blocks on this "unusual" lock while another process holding the lock 1646 * waits for fanotify permission event to be answered. Just disallow 1647 * permission events for such filesystems. 1648 */ 1649 if (mask & FANOTIFY_PERM_EVENTS && 1650 path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM) 1651 return -EINVAL; 1652 1653 /* 1654 * mount and sb marks are not allowed on kernel internal pseudo fs, 1655 * like pipe_mnt, because that would subscribe to events on all the 1656 * anonynous pipes in the system. 1657 * 1658 * SB_NOUSER covers all of the internal pseudo fs whose objects are not 1659 * exposed to user's mount namespace, but there are other SB_KERNMOUNT 1660 * fs, like nsfs, debugfs, for which the value of allowing sb and mount 1661 * mark is questionable. For now we leave them alone. 1662 */ 1663 if (mark_type != FAN_MARK_INODE && 1664 path->mnt->mnt_sb->s_flags & SB_NOUSER) 1665 return -EINVAL; 1666 1667 /* 1668 * We shouldn't have allowed setting dirent events and the directory 1669 * flags FAN_ONDIR and FAN_EVENT_ON_CHILD in mask of non-dir inode, 1670 * but because we always allowed it, error only when using new APIs. 1671 */ 1672 if (strict_dir_events && mark_type == FAN_MARK_INODE && 1673 !d_is_dir(path->dentry) && (mask & FANOTIFY_DIRONLY_EVENT_BITS)) 1674 return -ENOTDIR; 1675 1676 return 0; 1677} 1678 1679static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, 1680 int dfd, const char __user *pathname) 1681{ 1682 struct inode *inode = NULL; 1683 struct vfsmount *mnt = NULL; 1684 struct fsnotify_group *group; 1685 struct fd f; 1686 struct path path; 1687 struct fan_fsid __fsid, *fsid = NULL; 1688 u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS; 1689 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; 1690 unsigned int mark_cmd = flags & FANOTIFY_MARK_CMD_BITS; 1691 unsigned int ignore = flags & FANOTIFY_MARK_IGNORE_BITS; 1692 unsigned int obj_type, fid_mode; 1693 void *obj; 1694 u32 umask = 0; 1695 int ret; 1696 1697 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", 1698 __func__, fanotify_fd, flags, dfd, pathname, mask); 1699 1700 /* we only use the lower 32 bits as of right now. */ 1701 if (upper_32_bits(mask)) 1702 return -EINVAL; 1703 1704 if (flags & ~FANOTIFY_MARK_FLAGS) 1705 return -EINVAL; 1706 1707 switch (mark_type) { 1708 case FAN_MARK_INODE: 1709 obj_type = FSNOTIFY_OBJ_TYPE_INODE; 1710 break; 1711 case FAN_MARK_MOUNT: 1712 obj_type = FSNOTIFY_OBJ_TYPE_VFSMOUNT; 1713 break; 1714 case FAN_MARK_FILESYSTEM: 1715 obj_type = FSNOTIFY_OBJ_TYPE_SB; 1716 break; 1717 default: 1718 return -EINVAL; 1719 } 1720 1721 switch (mark_cmd) { 1722 case FAN_MARK_ADD: 1723 case FAN_MARK_REMOVE: 1724 if (!mask) 1725 return -EINVAL; 1726 break; 1727 case FAN_MARK_FLUSH: 1728 if (flags & ~(FANOTIFY_MARK_TYPE_BITS | FAN_MARK_FLUSH)) 1729 return -EINVAL; 1730 break; 1731 default: 1732 return -EINVAL; 1733 } 1734 1735 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) 1736 valid_mask |= FANOTIFY_PERM_EVENTS; 1737 1738 if (mask & ~valid_mask) 1739 return -EINVAL; 1740 1741 1742 /* We don't allow FAN_MARK_IGNORE & FAN_MARK_IGNORED_MASK together */ 1743 if (ignore == (FAN_MARK_IGNORE | FAN_MARK_IGNORED_MASK)) 1744 return -EINVAL; 1745 1746 /* 1747 * Event flags (FAN_ONDIR, FAN_EVENT_ON_CHILD) have no effect with 1748 * FAN_MARK_IGNORED_MASK. 1749 */ 1750 if (ignore == FAN_MARK_IGNORED_MASK) { 1751 mask &= ~FANOTIFY_EVENT_FLAGS; 1752 umask = FANOTIFY_EVENT_FLAGS; 1753 } 1754 1755 f = fdget(fanotify_fd); 1756 if (unlikely(!f.file)) 1757 return -EBADF; 1758 1759 /* verify that this is indeed an fanotify instance */ 1760 ret = -EINVAL; 1761 if (unlikely(f.file->f_op != &fanotify_fops)) 1762 goto fput_and_out; 1763 group = f.file->private_data; 1764 1765 /* 1766 * An unprivileged user is not allowed to setup mount nor filesystem 1767 * marks. This also includes setting up such marks by a group that 1768 * was initialized by an unprivileged user. 1769 */ 1770 ret = -EPERM; 1771 if ((!capable(CAP_SYS_ADMIN) || 1772 FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) && 1773 mark_type != FAN_MARK_INODE) 1774 goto fput_and_out; 1775 1776 /* 1777 * Permission events require minimum priority FAN_CLASS_CONTENT. 1778 */ 1779 ret = -EINVAL; 1780 if (mask & FANOTIFY_PERM_EVENTS && 1781 group->priority < FSNOTIFY_PRIO_CONTENT) 1782 goto fput_and_out; 1783 1784 if (mask & FAN_FS_ERROR && 1785 mark_type != FAN_MARK_FILESYSTEM) 1786 goto fput_and_out; 1787 1788 /* 1789 * Evictable is only relevant for inode marks, because only inode object 1790 * can be evicted on memory pressure. 1791 */ 1792 if (flags & FAN_MARK_EVICTABLE && 1793 mark_type != FAN_MARK_INODE) 1794 goto fput_and_out; 1795 1796 /* 1797 * Events that do not carry enough information to report 1798 * event->fd require a group that supports reporting fid. Those 1799 * events are not supported on a mount mark, because they do not 1800 * carry enough information (i.e. path) to be filtered by mount 1801 * point. 1802 */ 1803 fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); 1804 if (mask & ~(FANOTIFY_FD_EVENTS|FANOTIFY_EVENT_FLAGS) && 1805 (!fid_mode || mark_type == FAN_MARK_MOUNT)) 1806 goto fput_and_out; 1807 1808 /* 1809 * FAN_RENAME uses special info type records to report the old and 1810 * new parent+name. Reporting only old and new parent id is less 1811 * useful and was not implemented. 1812 */ 1813 if (mask & FAN_RENAME && !(fid_mode & FAN_REPORT_NAME)) 1814 goto fput_and_out; 1815 1816 if (mark_cmd == FAN_MARK_FLUSH) { 1817 ret = 0; 1818 if (mark_type == FAN_MARK_MOUNT) 1819 fsnotify_clear_vfsmount_marks_by_group(group); 1820 else if (mark_type == FAN_MARK_FILESYSTEM) 1821 fsnotify_clear_sb_marks_by_group(group); 1822 else 1823 fsnotify_clear_inode_marks_by_group(group); 1824 goto fput_and_out; 1825 } 1826 1827 ret = fanotify_find_path(dfd, pathname, &path, flags, 1828 (mask & ALL_FSNOTIFY_EVENTS), obj_type); 1829 if (ret) 1830 goto fput_and_out; 1831 1832 if (mark_cmd == FAN_MARK_ADD) { 1833 ret = fanotify_events_supported(group, &path, mask, flags); 1834 if (ret) 1835 goto path_put_and_out; 1836 } 1837 1838 if (fid_mode) { 1839 ret = fanotify_test_fsid(path.dentry, flags, &__fsid); 1840 if (ret) 1841 goto path_put_and_out; 1842 1843 ret = fanotify_test_fid(path.dentry, flags); 1844 if (ret) 1845 goto path_put_and_out; 1846 1847 fsid = &__fsid; 1848 } 1849 1850 /* inode held in place by reference to path; group by fget on fd */ 1851 if (mark_type == FAN_MARK_INODE) { 1852 inode = path.dentry->d_inode; 1853 obj = inode; 1854 } else { 1855 mnt = path.mnt; 1856 if (mark_type == FAN_MARK_MOUNT) 1857 obj = mnt; 1858 else 1859 obj = mnt->mnt_sb; 1860 } 1861 1862 /* 1863 * If some other task has this inode open for write we should not add 1864 * an ignore mask, unless that ignore mask is supposed to survive 1865 * modification changes anyway. 1866 */ 1867 if (mark_cmd == FAN_MARK_ADD && (flags & FANOTIFY_MARK_IGNORE_BITS) && 1868 !(flags & FAN_MARK_IGNORED_SURV_MODIFY)) { 1869 ret = mnt ? -EINVAL : -EISDIR; 1870 /* FAN_MARK_IGNORE requires SURV_MODIFY for sb/mount/dir marks */ 1871 if (ignore == FAN_MARK_IGNORE && 1872 (mnt || S_ISDIR(inode->i_mode))) 1873 goto path_put_and_out; 1874 1875 ret = 0; 1876 if (inode && inode_is_open_for_write(inode)) 1877 goto path_put_and_out; 1878 } 1879 1880 /* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */ 1881 if (mnt || !S_ISDIR(inode->i_mode)) { 1882 mask &= ~FAN_EVENT_ON_CHILD; 1883 umask = FAN_EVENT_ON_CHILD; 1884 /* 1885 * If group needs to report parent fid, register for getting 1886 * events with parent/name info for non-directory. 1887 */ 1888 if ((fid_mode & FAN_REPORT_DIR_FID) && 1889 (flags & FAN_MARK_ADD) && !ignore) 1890 mask |= FAN_EVENT_ON_CHILD; 1891 } 1892 1893 /* create/update an inode mark */ 1894 switch (mark_cmd) { 1895 case FAN_MARK_ADD: 1896 ret = fanotify_add_mark(group, obj, obj_type, mask, flags, 1897 fsid); 1898 break; 1899 case FAN_MARK_REMOVE: 1900 ret = fanotify_remove_mark(group, obj, obj_type, mask, flags, 1901 umask); 1902 break; 1903 default: 1904 ret = -EINVAL; 1905 } 1906 1907path_put_and_out: 1908 path_put(&path); 1909fput_and_out: 1910 fdput(f); 1911 return ret; 1912} 1913 1914#ifndef CONFIG_ARCH_SPLIT_ARG64 1915SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, 1916 __u64, mask, int, dfd, 1917 const char __user *, pathname) 1918{ 1919 return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname); 1920} 1921#endif 1922 1923#if defined(CONFIG_ARCH_SPLIT_ARG64) || defined(CONFIG_COMPAT) 1924SYSCALL32_DEFINE6(fanotify_mark, 1925 int, fanotify_fd, unsigned int, flags, 1926 SC_ARG64(mask), int, dfd, 1927 const char __user *, pathname) 1928{ 1929 return do_fanotify_mark(fanotify_fd, flags, SC_VAL64(__u64, mask), 1930 dfd, pathname); 1931} 1932#endif 1933 1934/* 1935 * fanotify_user_setup - Our initialization function. Note that we cannot return 1936 * error because we have compiled-in VFS hooks. So an (unlikely) failure here 1937 * must result in panic(). 1938 */ 1939static int __init fanotify_user_setup(void) 1940{ 1941 struct sysinfo si; 1942 int max_marks; 1943 1944 si_meminfo(&si); 1945 /* 1946 * Allow up to 1% of addressable memory to be accounted for per user 1947 * marks limited to the range [8192, 1048576]. mount and sb marks are 1948 * a lot cheaper than inode marks, but there is no reason for a user 1949 * to have many of those, so calculate by the cost of inode marks. 1950 */ 1951 max_marks = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) / 1952 INODE_MARK_COST; 1953 max_marks = clamp(max_marks, FANOTIFY_OLD_DEFAULT_MAX_MARKS, 1954 FANOTIFY_DEFAULT_MAX_USER_MARKS); 1955 1956 BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS); 1957 BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 12); 1958 BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 11); 1959 1960 fanotify_mark_cache = KMEM_CACHE(fanotify_mark, 1961 SLAB_PANIC|SLAB_ACCOUNT); 1962 fanotify_fid_event_cachep = KMEM_CACHE(fanotify_fid_event, 1963 SLAB_PANIC); 1964 fanotify_path_event_cachep = KMEM_CACHE(fanotify_path_event, 1965 SLAB_PANIC); 1966 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) { 1967 fanotify_perm_event_cachep = 1968 KMEM_CACHE(fanotify_perm_event, SLAB_PANIC); 1969 } 1970 1971 fanotify_max_queued_events = FANOTIFY_DEFAULT_MAX_EVENTS; 1972 init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS] = 1973 FANOTIFY_DEFAULT_MAX_GROUPS; 1974 init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS] = max_marks; 1975 fanotify_sysctls_init(); 1976 1977 return 0; 1978} 1979device_initcall(fanotify_user_setup); 1980