| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Amir Goldstein | 2847 | 37.56% | 61 | 28.11% |
| Eric Paris | 1986 | 26.20% | 33 | 15.21% |
| Jan Kara | 638 | 8.42% | 31 | 14.29% |
| Matthew Bobrowski | 475 | 6.27% | 4 | 1.84% |
| Gabriel Krisman Bertazi | 334 | 4.41% | 10 | 4.61% |
| Richard Guy Briggs | 284 | 3.75% | 2 | 0.92% |
| Andreas Gruenbacher | 181 | 2.39% | 9 | 4.15% |
| Al Viro | 155 | 2.05% | 12 | 5.53% |
| Lino Sanfilippo | 144 | 1.90% | 10 | 4.61% |
| Aaron Goidel | 58 | 0.77% | 1 | 0.46% |
| Heinrich Schuchardt | 54 | 0.71% | 3 | 1.38% |
| Miklos Szeredi | 38 | 0.50% | 1 | 0.46% |
| Steve Grubb | 35 | 0.46% | 1 | 0.46% |
| Eric Dumazet | 33 | 0.44% | 1 | 0.46% |
| Sven Schnelle | 32 | 0.42% | 1 | 0.46% |
| Christian Brauner | 32 | 0.42% | 3 | 1.38% |
| nixiaoming | 27 | 0.36% | 1 | 0.46% |
| Dominik Brodowski | 26 | 0.34% | 1 | 0.46% |
| Brian Gerst | 21 | 0.28% | 1 | 0.46% |
| Christoph Hellwig | 21 | 0.28% | 1 | 0.46% |
| Peter Zijlstra | 19 | 0.25% | 1 | 0.46% |
| Kees Cook | 18 | 0.24% | 1 | 0.46% |
| Shakeel Butt | 13 | 0.17% | 1 | 0.46% |
| Dan Carpenter | 11 | 0.15% | 1 | 0.46% |
| Heiko Carstens | 10 | 0.13% | 1 | 0.46% |
| Will Woods | 9 | 0.12% | 1 | 0.46% |
| Yann Droneaud | 8 | 0.11% | 1 | 0.46% |
| Cyrill V. Gorcunov | 8 | 0.11% | 1 | 0.46% |
| Andreas Schwab | 6 | 0.08% | 1 | 0.46% |
| Fabian Frederick | 6 | 0.08% | 2 | 0.92% |
| David Daney | 6 | 0.08% | 1 | 0.46% |
| Arnd Bergmann | 6 | 0.08% | 2 | 0.92% |
| Robert Love | 6 | 0.08% | 2 | 0.92% |
| Linus Torvalds | 6 | 0.08% | 2 | 0.92% |
| Alexey Dobriyan | 4 | 0.05% | 1 | 0.46% |
| Andi Kleen | 3 | 0.04% | 1 | 0.46% |
| Linus Torvalds (pre-git) | 3 | 0.04% | 1 | 0.46% |
| Balbir Singh | 3 | 0.04% | 1 | 0.46% |
| Ingo Molnar | 3 | 0.04% | 1 | 0.46% |
| Eric W. Biedermann | 3 | 0.04% | 1 | 0.46% |
| Vasily Averin | 2 | 0.03% | 1 | 0.46% |
| Lucas De Marchi | 1 | 0.01% | 1 | 0.46% |
| Justin P. Mattock | 1 | 0.01% | 1 | 0.46% |
| Nikolay Borisov | 1 | 0.01% | 1 | 0.46% |
| Greg Kroah-Hartman | 1 | 0.01% | 1 | 0.46% |
| Joel Granados | 1 | 0.01% | 1 | 0.46% |
| Total | 7579 | 217 |
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// SPDX-License-Identifier: GPL-2.0 #include <linux/fanotify.h> #include <linux/fcntl.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/anon_inodes.h> #include <linux/fsnotify_backend.h> #include <linux/init.h> #include <linux/mount.h> #include <linux/namei.h> #include <linux/poll.h> #include <linux/security.h> #include <linux/syscalls.h> #include <linux/slab.h> #include <linux/types.h> #include <linux/uaccess.h> #include <linux/compat.h> #include <linux/sched/signal.h> #include <linux/memcontrol.h> #include <linux/statfs.h> #include <linux/exportfs.h> #include <asm/ioctls.h> #include "../fsnotify.h" #include "../fdinfo.h" #include "fanotify.h" #define FANOTIFY_DEFAULT_MAX_EVENTS 16384 #define FANOTIFY_OLD_DEFAULT_MAX_MARKS 8192 #define FANOTIFY_DEFAULT_MAX_GROUPS 128 #define FANOTIFY_DEFAULT_FEE_POOL_SIZE 32 /* * Legacy fanotify marks limits (8192) is per group and we introduced a tunable * limit of marks per user, similar to inotify. Effectively, the legacy limit * of fanotify marks per user is <max marks per group> * <max groups per user>. * This default limit (1M) also happens to match the increased limit of inotify * max_user_watches since v5.10. */ #define FANOTIFY_DEFAULT_MAX_USER_MARKS \ (FANOTIFY_OLD_DEFAULT_MAX_MARKS * FANOTIFY_DEFAULT_MAX_GROUPS) /* * Most of the memory cost of adding an inode mark is pinning the marked inode. * The size of the filesystem inode struct is not uniform across filesystems, * so double the size of a VFS inode is used as a conservative approximation. */ #define INODE_MARK_COST (2 * sizeof(struct inode)) /* configurable via /proc/sys/fs/fanotify/ */ static int fanotify_max_queued_events __read_mostly; #ifdef CONFIG_SYSCTL #include <linux/sysctl.h> static long ft_zero = 0; static long ft_int_max = INT_MAX; static struct ctl_table fanotify_table[] = { { .procname = "max_user_groups", .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS], .maxlen = sizeof(long), .mode = 0644, .proc_handler = proc_doulongvec_minmax, .extra1 = &ft_zero, .extra2 = &ft_int_max, }, { .procname = "max_user_marks", .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS], .maxlen = sizeof(long), .mode = 0644, .proc_handler = proc_doulongvec_minmax, .extra1 = &ft_zero, .extra2 = &ft_int_max, }, { .procname = "max_queued_events", .data = &fanotify_max_queued_events, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO }, }; static void __init fanotify_sysctls_init(void) { register_sysctl("fs/fanotify", fanotify_table); } #else #define fanotify_sysctls_init() do { } while (0) #endif /* CONFIG_SYSCTL */ /* * All flags that may be specified in parameter event_f_flags of fanotify_init. * * Internal and external open flags are stored together in field f_flags of * struct file. Only external open flags shall be allowed in event_f_flags. * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be * excluded. */ #define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \ O_ACCMODE | O_APPEND | O_NONBLOCK | \ __O_SYNC | O_DSYNC | O_CLOEXEC | \ O_LARGEFILE | O_NOATIME ) extern const struct fsnotify_ops fanotify_fsnotify_ops; struct kmem_cache *fanotify_mark_cache __ro_after_init; struct kmem_cache *fanotify_fid_event_cachep __ro_after_init; struct kmem_cache *fanotify_path_event_cachep __ro_after_init; struct kmem_cache *fanotify_perm_event_cachep __ro_after_init; #define FANOTIFY_EVENT_ALIGN 4 #define FANOTIFY_FID_INFO_HDR_LEN \ (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle)) #define FANOTIFY_PIDFD_INFO_HDR_LEN \ sizeof(struct fanotify_event_info_pidfd) #define FANOTIFY_ERROR_INFO_LEN \ (sizeof(struct fanotify_event_info_error)) static int fanotify_fid_info_len(int fh_len, int name_len) { int info_len = fh_len; if (name_len) info_len += name_len + 1; return roundup(FANOTIFY_FID_INFO_HDR_LEN + info_len, FANOTIFY_EVENT_ALIGN); } /* FAN_RENAME may have one or two dir+name info records */ static int fanotify_dir_name_info_len(struct fanotify_event *event) { struct fanotify_info *info = fanotify_event_info(event); int dir_fh_len = fanotify_event_dir_fh_len(event); int dir2_fh_len = fanotify_event_dir2_fh_len(event); int info_len = 0; if (dir_fh_len) info_len += fanotify_fid_info_len(dir_fh_len, info->name_len); if (dir2_fh_len) info_len += fanotify_fid_info_len(dir2_fh_len, info->name2_len); return info_len; } static size_t fanotify_event_len(unsigned int info_mode, struct fanotify_event *event) { size_t event_len = FAN_EVENT_METADATA_LEN; int fh_len; int dot_len = 0; if (!info_mode) return event_len; if (fanotify_is_error_event(event->mask)) event_len += FANOTIFY_ERROR_INFO_LEN; if (fanotify_event_has_any_dir_fh(event)) { event_len += fanotify_dir_name_info_len(event); } else if ((info_mode & FAN_REPORT_NAME) && (event->mask & FAN_ONDIR)) { /* * With group flag FAN_REPORT_NAME, if name was not recorded in * event on a directory, we will report the name ".". */ dot_len = 1; } if (info_mode & FAN_REPORT_PIDFD) event_len += FANOTIFY_PIDFD_INFO_HDR_LEN; if (fanotify_event_has_object_fh(event)) { fh_len = fanotify_event_object_fh_len(event); event_len += fanotify_fid_info_len(fh_len, dot_len); } return event_len; } /* * Remove an hashed event from merge hash table. */ static void fanotify_unhash_event(struct fsnotify_group *group, struct fanotify_event *event) { assert_spin_locked(&group->notification_lock); pr_debug("%s: group=%p event=%p bucket=%u\n", __func__, group, event, fanotify_event_hash_bucket(group, event)); if (WARN_ON_ONCE(hlist_unhashed(&event->merge_list))) return; hlist_del_init(&event->merge_list); } /* * Get an fanotify notification event if one exists and is small * enough to fit in "count". Return an error pointer if the count * is not large enough. When permission event is dequeued, its state is * updated accordingly. */ static struct fanotify_event *get_one_event(struct fsnotify_group *group, size_t count) { size_t event_size; struct fanotify_event *event = NULL; struct fsnotify_event *fsn_event; unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); pr_debug("%s: group=%p count=%zd\n", __func__, group, count); spin_lock(&group->notification_lock); fsn_event = fsnotify_peek_first_event(group); if (!fsn_event) goto out; event = FANOTIFY_E(fsn_event); event_size = fanotify_event_len(info_mode, event); if (event_size > count) { event = ERR_PTR(-EINVAL); goto out; } /* * Held the notification_lock the whole time, so this is the * same event we peeked above. */ fsnotify_remove_first_event(group); if (fanotify_is_perm_event(event->mask)) FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED; if (fanotify_is_hashed_event(event->mask)) fanotify_unhash_event(group, event); out: spin_unlock(&group->notification_lock); return event; } static int create_fd(struct fsnotify_group *group, const struct path *path, struct file **file) { int client_fd; struct file *new_file; client_fd = get_unused_fd_flags(group->fanotify_data.f_flags); if (client_fd < 0) return client_fd; /* * we need a new file handle for the userspace program so it can read even if it was * originally opened O_WRONLY. */ new_file = dentry_open(path, group->fanotify_data.f_flags | __FMODE_NONOTIFY, current_cred()); if (IS_ERR(new_file)) { put_unused_fd(client_fd); client_fd = PTR_ERR(new_file); } else { *file = new_file; } return client_fd; } static int process_access_response_info(const char __user *info, size_t info_len, struct fanotify_response_info_audit_rule *friar) { if (info_len != sizeof(*friar)) return -EINVAL; if (copy_from_user(friar, info, sizeof(*friar))) return -EFAULT; if (friar->hdr.type != FAN_RESPONSE_INFO_AUDIT_RULE) return -EINVAL; if (friar->hdr.pad != 0) return -EINVAL; if (friar->hdr.len != sizeof(*friar)) return -EINVAL; return info_len; } /* * Finish processing of permission event by setting it to ANSWERED state and * drop group->notification_lock. */ static void finish_permission_event(struct fsnotify_group *group, struct fanotify_perm_event *event, u32 response, struct fanotify_response_info_audit_rule *friar) __releases(&group->notification_lock) { bool destroy = false; assert_spin_locked(&group->notification_lock); event->response = response & ~FAN_INFO; if (response & FAN_INFO) memcpy(&event->audit_rule, friar, sizeof(*friar)); if (event->state == FAN_EVENT_CANCELED) destroy = true; else event->state = FAN_EVENT_ANSWERED; spin_unlock(&group->notification_lock); if (destroy) fsnotify_destroy_event(group, &event->fae.fse); } static int process_access_response(struct fsnotify_group *group, struct fanotify_response *response_struct, const char __user *info, size_t info_len) { struct fanotify_perm_event *event; int fd = response_struct->fd; u32 response = response_struct->response; int ret = info_len; struct fanotify_response_info_audit_rule friar; pr_debug("%s: group=%p fd=%d response=%u buf=%p size=%zu\n", __func__, group, fd, response, info, info_len); /* * make sure the response is valid, if invalid we do nothing and either * userspace can send a valid response or we will clean it up after the * timeout */ if (response & ~FANOTIFY_RESPONSE_VALID_MASK) return -EINVAL; switch (response & FANOTIFY_RESPONSE_ACCESS) { case FAN_ALLOW: case FAN_DENY: break; default: return -EINVAL; } if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT)) return -EINVAL; if (response & FAN_INFO) { ret = process_access_response_info(info, info_len, &friar); if (ret < 0) return ret; if (fd == FAN_NOFD) return ret; } else { ret = 0; } if (fd < 0) return -EINVAL; spin_lock(&group->notification_lock); list_for_each_entry(event, &group->fanotify_data.access_list, fae.fse.list) { if (event->fd != fd) continue; list_del_init(&event->fae.fse.list); finish_permission_event(group, event, response, &friar); wake_up(&group->fanotify_data.access_waitq); return ret; } spin_unlock(&group->notification_lock); return -ENOENT; } static size_t copy_error_info_to_user(struct fanotify_event *event, char __user *buf, int count) { struct fanotify_event_info_error info = { }; struct fanotify_error_event *fee = FANOTIFY_EE(event); info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR; info.hdr.len = FANOTIFY_ERROR_INFO_LEN; if (WARN_ON(count < info.hdr.len)) return -EFAULT; info.error = fee->error; info.error_count = fee->err_count; if (copy_to_user(buf, &info, sizeof(info))) return -EFAULT; return info.hdr.len; } static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh, int info_type, const char *name, size_t name_len, char __user *buf, size_t count) { struct fanotify_event_info_fid info = { }; struct file_handle handle = { }; unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf; size_t fh_len = fh ? fh->len : 0; size_t info_len = fanotify_fid_info_len(fh_len, name_len); size_t len = info_len; pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n", __func__, fh_len, name_len, info_len, count); if (WARN_ON_ONCE(len < sizeof(info) || len > count)) return -EFAULT; /* * Copy event info fid header followed by variable sized file handle * and optionally followed by variable sized filename. */ switch (info_type) { case FAN_EVENT_INFO_TYPE_FID: case FAN_EVENT_INFO_TYPE_DFID: if (WARN_ON_ONCE(name_len)) return -EFAULT; break; case FAN_EVENT_INFO_TYPE_DFID_NAME: case FAN_EVENT_INFO_TYPE_OLD_DFID_NAME: case FAN_EVENT_INFO_TYPE_NEW_DFID_NAME: if (WARN_ON_ONCE(!name || !name_len)) return -EFAULT; break; default: return -EFAULT; } info.hdr.info_type = info_type; info.hdr.len = len; info.fsid = *fsid; if (copy_to_user(buf, &info, sizeof(info))) return -EFAULT; buf += sizeof(info); len -= sizeof(info); if (WARN_ON_ONCE(len < sizeof(handle))) return -EFAULT; handle.handle_type = fh->type; handle.handle_bytes = fh_len; /* Mangle handle_type for bad file_handle */ if (!fh_len) handle.handle_type = FILEID_INVALID; if (copy_to_user(buf, &handle, sizeof(handle))) return -EFAULT; buf += sizeof(handle); len -= sizeof(handle); if (WARN_ON_ONCE(len < fh_len)) return -EFAULT; /* * For an inline fh and inline file name, copy through stack to exclude * the copy from usercopy hardening protections. */ fh_buf = fanotify_fh_buf(fh); if (fh_len <= FANOTIFY_INLINE_FH_LEN) { memcpy(bounce, fh_buf, fh_len); fh_buf = bounce; } if (copy_to_user(buf, fh_buf, fh_len)) return -EFAULT; buf += fh_len; len -= fh_len; if (name_len) { /* Copy the filename with terminating null */ name_len++; if (WARN_ON_ONCE(len < name_len)) return -EFAULT; if (copy_to_user(buf, name, name_len)) return -EFAULT; buf += name_len; len -= name_len; } /* Pad with 0's */ WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN); if (len > 0 && clear_user(buf, len)) return -EFAULT; return info_len; } static int copy_pidfd_info_to_user(int pidfd, char __user *buf, size_t count) { struct fanotify_event_info_pidfd info = { }; size_t info_len = FANOTIFY_PIDFD_INFO_HDR_LEN; if (WARN_ON_ONCE(info_len > count)) return -EFAULT; info.hdr.info_type = FAN_EVENT_INFO_TYPE_PIDFD; info.hdr.len = info_len; info.pidfd = pidfd; if (copy_to_user(buf, &info, info_len)) return -EFAULT; return info_len; } static int copy_info_records_to_user(struct fanotify_event *event, struct fanotify_info *info, unsigned int info_mode, int pidfd, char __user *buf, size_t count) { int ret, total_bytes = 0, info_type = 0; unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS; unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; /* * Event info records order is as follows: * 1. dir fid + name * 2. (optional) new dir fid + new name * 3. (optional) child fid */ if (fanotify_event_has_dir_fh(event)) { info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME : FAN_EVENT_INFO_TYPE_DFID; /* FAN_RENAME uses special info types */ if (event->mask & FAN_RENAME) info_type = FAN_EVENT_INFO_TYPE_OLD_DFID_NAME; ret = copy_fid_info_to_user(fanotify_event_fsid(event), fanotify_info_dir_fh(info), info_type, fanotify_info_name(info), info->name_len, buf, count); if (ret < 0) return ret; buf += ret; count -= ret; total_bytes += ret; } /* New dir fid+name may be reported in addition to old dir fid+name */ if (fanotify_event_has_dir2_fh(event)) { info_type = FAN_EVENT_INFO_TYPE_NEW_DFID_NAME; ret = copy_fid_info_to_user(fanotify_event_fsid(event), fanotify_info_dir2_fh(info), info_type, fanotify_info_name2(info), info->name2_len, buf, count); if (ret < 0) return ret; buf += ret; count -= ret; total_bytes += ret; } if (fanotify_event_has_object_fh(event)) { const char *dot = NULL; int dot_len = 0; if (fid_mode == FAN_REPORT_FID || info_type) { /* * With only group flag FAN_REPORT_FID only type FID is * reported. Second info record type is always FID. */ info_type = FAN_EVENT_INFO_TYPE_FID; } else if ((fid_mode & FAN_REPORT_NAME) && (event->mask & FAN_ONDIR)) { /* * With group flag FAN_REPORT_NAME, if name was not * recorded in an event on a directory, report the name * "." with info type DFID_NAME. */ info_type = FAN_EVENT_INFO_TYPE_DFID_NAME; dot = "."; dot_len = 1; } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) || (event->mask & FAN_ONDIR)) { /* * With group flag FAN_REPORT_DIR_FID, a single info * record has type DFID for directory entry modification * event and for event on a directory. */ info_type = FAN_EVENT_INFO_TYPE_DFID; } else { /* * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID, * a single info record has type FID for event on a * non-directory, when there is no directory to report. * For example, on FAN_DELETE_SELF event. */ info_type = FAN_EVENT_INFO_TYPE_FID; } ret = copy_fid_info_to_user(fanotify_event_fsid(event), fanotify_event_object_fh(event), info_type, dot, dot_len, buf, count); if (ret < 0) return ret; buf += ret; count -= ret; total_bytes += ret; } if (pidfd_mode) { ret = copy_pidfd_info_to_user(pidfd, buf, count); if (ret < 0) return ret; buf += ret; count -= ret; total_bytes += ret; } if (fanotify_is_error_event(event->mask)) { ret = copy_error_info_to_user(event, buf, count); if (ret < 0) return ret; buf += ret; count -= ret; total_bytes += ret; } return total_bytes; } static ssize_t copy_event_to_user(struct fsnotify_group *group, struct fanotify_event *event, char __user *buf, size_t count) { struct fanotify_event_metadata metadata; const struct path *path = fanotify_event_path(event); struct fanotify_info *info = fanotify_event_info(event); unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; struct file *f = NULL, *pidfd_file = NULL; int ret, pidfd = -ESRCH, fd = -EBADF; pr_debug("%s: group=%p event=%p\n", __func__, group, event); metadata.event_len = fanotify_event_len(info_mode, event); metadata.metadata_len = FAN_EVENT_METADATA_LEN; metadata.vers = FANOTIFY_METADATA_VERSION; metadata.reserved = 0; metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS; metadata.pid = pid_vnr(event->pid); /* * For an unprivileged listener, event->pid can be used to identify the * events generated by the listener process itself, without disclosing * the pids of other processes. */ if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && task_tgid(current) != event->pid) metadata.pid = 0; /* * For now, fid mode is required for an unprivileged listener and * fid mode does not report fd in events. Keep this check anyway * for safety in case fid mode requirement is relaxed in the future * to allow unprivileged listener to get events with no fd and no fid. */ if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && path && path->mnt && path->dentry) { fd = create_fd(group, path, &f); /* * Opening an fd from dentry can fail for several reasons. * For example, when tasks are gone and we try to open their * /proc files or we try to open a WRONLY file like in sysfs * or when trying to open a file that was deleted on the * remote network server. * * For a group with FAN_REPORT_FD_ERROR, we will send the * event with the error instead of the open fd, otherwise * Userspace may not get the error at all. * In any case, userspace will not know which file failed to * open, so add a debug print for further investigation. */ if (fd < 0) { pr_debug("fanotify: create_fd(%pd2) failed err=%d\n", path->dentry, fd); if (!FAN_GROUP_FLAG(group, FAN_REPORT_FD_ERROR)) { /* * Historically, we've handled EOPENSTALE in a * special way and silently dropped such * events. Now we have to keep it to maintain * backward compatibility... */ if (fd == -EOPENSTALE) fd = 0; return fd; } } } if (FAN_GROUP_FLAG(group, FAN_REPORT_FD_ERROR)) metadata.fd = fd; else metadata.fd = fd >= 0 ? fd : FAN_NOFD; if (pidfd_mode) { /* * Complain if the FAN_REPORT_PIDFD and FAN_REPORT_TID mutual * exclusion is ever lifted. At the time of incoporating pidfd * support within fanotify, the pidfd API only supported the * creation of pidfds for thread-group leaders. */ WARN_ON_ONCE(FAN_GROUP_FLAG(group, FAN_REPORT_TID)); /* * The PIDTYPE_TGID check for an event->pid is performed * preemptively in an attempt to catch out cases where the event * listener reads events after the event generating process has * already terminated. Depending on flag FAN_REPORT_FD_ERROR, * report either -ESRCH or FAN_NOPIDFD to the event listener in * those cases with all other pidfd creation errors reported as * the error code itself or as FAN_EPIDFD. */ if (metadata.pid && pid_has_task(event->pid, PIDTYPE_TGID)) pidfd = pidfd_prepare(event->pid, 0, &pidfd_file); if (!FAN_GROUP_FLAG(group, FAN_REPORT_FD_ERROR) && pidfd < 0) pidfd = pidfd == -ESRCH ? FAN_NOPIDFD : FAN_EPIDFD; } ret = -EFAULT; /* * Sanity check copy size in case get_one_event() and * event_len sizes ever get out of sync. */ if (WARN_ON_ONCE(metadata.event_len > count)) goto out_close_fd; if (copy_to_user(buf, &metadata, FAN_EVENT_METADATA_LEN)) goto out_close_fd; buf += FAN_EVENT_METADATA_LEN; count -= FAN_EVENT_METADATA_LEN; if (info_mode) { ret = copy_info_records_to_user(event, info, info_mode, pidfd, buf, count); if (ret < 0) goto out_close_fd; } if (f) fd_install(fd, f); if (pidfd_file) fd_install(pidfd, pidfd_file); if (fanotify_is_perm_event(event->mask)) FANOTIFY_PERM(event)->fd = fd; return metadata.event_len; out_close_fd: if (f) { put_unused_fd(fd); fput(f); } if (pidfd_file) { put_unused_fd(pidfd); fput(pidfd_file); } return ret; } /* intofiy userspace file descriptor functions */ static __poll_t fanotify_poll(struct file *file, poll_table *wait) { struct fsnotify_group *group = file->private_data; __poll_t ret = 0; poll_wait(file, &group->notification_waitq, wait); spin_lock(&group->notification_lock); if (!fsnotify_notify_queue_is_empty(group)) ret = EPOLLIN | EPOLLRDNORM; spin_unlock(&group->notification_lock); return ret; } static ssize_t fanotify_read(struct file *file, char __user *buf, size_t count, loff_t *pos) { struct fsnotify_group *group; struct fanotify_event *event; char __user *start; int ret; DEFINE_WAIT_FUNC(wait, woken_wake_function); start = buf; group = file->private_data; pr_debug("%s: group=%p\n", __func__, group); add_wait_queue(&group->notification_waitq, &wait); while (1) { /* * User can supply arbitrarily large buffer. Avoid softlockups * in case there are lots of available events. */ cond_resched(); event = get_one_event(group, count); if (IS_ERR(event)) { ret = PTR_ERR(event); break; } if (!event) { ret = -EAGAIN; if (file->f_flags & O_NONBLOCK) break; ret = -ERESTARTSYS; if (signal_pending(current)) break; if (start != buf) break; wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); continue; } ret = copy_event_to_user(group, event, buf, count); /* * Permission events get queued to wait for response. Other * events can be destroyed now. */ if (!fanotify_is_perm_event(event->mask)) { fsnotify_destroy_event(group, &event->fse); } else { if (ret <= 0 || FANOTIFY_PERM(event)->fd < 0) { spin_lock(&group->notification_lock); finish_permission_event(group, FANOTIFY_PERM(event), FAN_DENY, NULL); wake_up(&group->fanotify_data.access_waitq); } else { spin_lock(&group->notification_lock); list_add_tail(&event->fse.list, &group->fanotify_data.access_list); spin_unlock(&group->notification_lock); } } if (ret < 0) break; buf += ret; count -= ret; } remove_wait_queue(&group->notification_waitq, &wait); if (start != buf && ret != -EFAULT) ret = buf - start; return ret; } static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) { struct fanotify_response response; struct fsnotify_group *group; int ret; const char __user *info_buf = buf + sizeof(struct fanotify_response); size_t info_len; if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) return -EINVAL; group = file->private_data; pr_debug("%s: group=%p count=%zu\n", __func__, group, count); if (count < sizeof(response)) return -EINVAL; if (copy_from_user(&response, buf, sizeof(response))) return -EFAULT; info_len = count - sizeof(response); ret = process_access_response(group, &response, info_buf, info_len); if (ret < 0) count = ret; else count = sizeof(response) + ret; return count; } static int fanotify_release(struct inode *ignored, struct file *file) { struct fsnotify_group *group = file->private_data; struct fsnotify_event *fsn_event; /* * Stop new events from arriving in the notification queue. since * userspace cannot use fanotify fd anymore, no event can enter or * leave access_list by now either. */ fsnotify_group_stop_queueing(group); /* * Process all permission events on access_list and notification queue * and simulate reply from userspace. */ spin_lock(&group->notification_lock); while (!list_empty(&group->fanotify_data.access_list)) { struct fanotify_perm_event *event; event = list_first_entry(&group->fanotify_data.access_list, struct fanotify_perm_event, fae.fse.list); list_del_init(&event->fae.fse.list); finish_permission_event(group, event, FAN_ALLOW, NULL); spin_lock(&group->notification_lock); } /* * Destroy all non-permission events. For permission events just * dequeue them and set the response. They will be freed once the * response is consumed and fanotify_get_response() returns. */ while ((fsn_event = fsnotify_remove_first_event(group))) { struct fanotify_event *event = FANOTIFY_E(fsn_event); if (!(event->mask & FANOTIFY_PERM_EVENTS)) { spin_unlock(&group->notification_lock); fsnotify_destroy_event(group, fsn_event); } else { finish_permission_event(group, FANOTIFY_PERM(event), FAN_ALLOW, NULL); } spin_lock(&group->notification_lock); } spin_unlock(&group->notification_lock); /* Response for all permission events it set, wakeup waiters */ wake_up(&group->fanotify_data.access_waitq); /* matches the fanotify_init->fsnotify_alloc_group */ fsnotify_destroy_group(group); return 0; } static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct fsnotify_group *group; struct fsnotify_event *fsn_event; void __user *p; int ret = -ENOTTY; size_t send_len = 0; group = file->private_data; p = (void __user *) arg; switch (cmd) { case FIONREAD: spin_lock(&group->notification_lock); list_for_each_entry(fsn_event, &group->notification_list, list) send_len += FAN_EVENT_METADATA_LEN; spin_unlock(&group->notification_lock); ret = put_user(send_len, (int __user *) p); break; } return ret; } static const struct file_operations fanotify_fops = { .show_fdinfo = fanotify_show_fdinfo, .poll = fanotify_poll, .read = fanotify_read, .write = fanotify_write, .fasync = NULL, .release = fanotify_release, .unlocked_ioctl = fanotify_ioctl, .compat_ioctl = compat_ptr_ioctl, .llseek = noop_llseek, }; static int fanotify_find_path(int dfd, const char __user *filename, struct path *path, unsigned int flags, __u64 mask, unsigned int obj_type) { int ret; pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, dfd, filename, flags); if (filename == NULL) { CLASS(fd, f)(dfd); if (fd_empty(f)) return -EBADF; if ((flags & FAN_MARK_ONLYDIR) && !(S_ISDIR(file_inode(fd_file(f))->i_mode))) return -ENOTDIR; *path = fd_file(f)->f_path; path_get(path); } else { unsigned int lookup_flags = 0; if (!(flags & FAN_MARK_DONT_FOLLOW)) lookup_flags |= LOOKUP_FOLLOW; if (flags & FAN_MARK_ONLYDIR) lookup_flags |= LOOKUP_DIRECTORY; ret = user_path_at(dfd, filename, lookup_flags, path); if (ret) goto out; } /* you can only watch an inode if you have read permissions on it */ ret = path_permission(path, MAY_READ); if (ret) { path_put(path); goto out; } ret = security_path_notify(path, mask, obj_type); if (ret) path_put(path); out: return ret; } static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, __u32 mask, unsigned int flags, __u32 umask, int *destroy) { __u32 oldmask, newmask; /* umask bits cannot be removed by user */ mask &= ~umask; spin_lock(&fsn_mark->lock); oldmask = fsnotify_calc_mask(fsn_mark); if (!(flags & FANOTIFY_MARK_IGNORE_BITS)) { fsn_mark->mask &= ~mask; } else { fsn_mark->ignore_mask &= ~mask; } newmask = fsnotify_calc_mask(fsn_mark); /* * We need to keep the mark around even if remaining mask cannot * result in any events (e.g. mask == FAN_ONDIR) to support incremenal * changes to the mask. * Destroy mark when only umask bits remain. */ *destroy = !((fsn_mark->mask | fsn_mark->ignore_mask) & ~umask); spin_unlock(&fsn_mark->lock); return oldmask & ~newmask; } static int fanotify_remove_mark(struct fsnotify_group *group, void *obj, unsigned int obj_type, __u32 mask, unsigned int flags, __u32 umask) { struct fsnotify_mark *fsn_mark = NULL; __u32 removed; int destroy_mark; fsnotify_group_lock(group); fsn_mark = fsnotify_find_mark(obj, obj_type, group); if (!fsn_mark) { fsnotify_group_unlock(group); return -ENOENT; } removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, umask, &destroy_mark); if (removed & fsnotify_conn_mask(fsn_mark->connector)) fsnotify_recalc_mask(fsn_mark->connector); if (destroy_mark) fsnotify_detach_mark(fsn_mark); fsnotify_group_unlock(group); if (destroy_mark) fsnotify_free_mark(fsn_mark); /* matches the fsnotify_find_mark() */ fsnotify_put_mark(fsn_mark); return 0; } static bool fanotify_mark_update_flags(struct fsnotify_mark *fsn_mark, unsigned int fan_flags) { bool want_iref = !(fan_flags & FAN_MARK_EVICTABLE); unsigned int ignore = fan_flags & FANOTIFY_MARK_IGNORE_BITS; bool recalc = false; /* * When using FAN_MARK_IGNORE for the first time, mark starts using * independent event flags in ignore mask. After that, trying to * update the ignore mask with the old FAN_MARK_IGNORED_MASK API * will result in EEXIST error. */ if (ignore == FAN_MARK_IGNORE) fsn_mark->flags |= FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS; /* * Setting FAN_MARK_IGNORED_SURV_MODIFY for the first time may lead to * the removal of the FS_MODIFY bit in calculated mask if it was set * because of an ignore mask that is now going to survive FS_MODIFY. */ if (ignore && (fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) && !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) { fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; if (!(fsn_mark->mask & FS_MODIFY)) recalc = true; } if (fsn_mark->connector->type != FSNOTIFY_OBJ_TYPE_INODE || want_iref == !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)) return recalc; /* * NO_IREF may be removed from a mark, but not added. * When removed, fsnotify_recalc_mask() will take the inode ref. */ WARN_ON_ONCE(!want_iref); fsn_mark->flags &= ~FSNOTIFY_MARK_FLAG_NO_IREF; return true; } static bool fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, __u32 mask, unsigned int fan_flags) { bool recalc; spin_lock(&fsn_mark->lock); if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS)) fsn_mark->mask |= mask; else fsn_mark->ignore_mask |= mask; recalc = fsnotify_calc_mask(fsn_mark) & ~fsnotify_conn_mask(fsn_mark->connector); recalc |= fanotify_mark_update_flags(fsn_mark, fan_flags); spin_unlock(&fsn_mark->lock); return recalc; } struct fan_fsid { struct super_block *sb; __kernel_fsid_t id; bool weak; }; static int fanotify_set_mark_fsid(struct fsnotify_group *group, struct fsnotify_mark *mark, struct fan_fsid *fsid) { struct fsnotify_mark_connector *conn; struct fsnotify_mark *old; struct super_block *old_sb = NULL; FANOTIFY_MARK(mark)->fsid = fsid->id; mark->flags |= FSNOTIFY_MARK_FLAG_HAS_FSID; if (fsid->weak) mark->flags |= FSNOTIFY_MARK_FLAG_WEAK_FSID; /* First mark added will determine if group is single or multi fsid */ if (list_empty(&group->marks_list)) return 0; /* Find sb of an existing mark */ list_for_each_entry(old, &group->marks_list, g_list) { conn = READ_ONCE(old->connector); if (!conn) continue; old_sb = fsnotify_connector_sb(conn); if (old_sb) break; } /* Only detached marks left? */ if (!old_sb) return 0; /* Do not allow mixing of marks with weak and strong fsid */ if ((mark->flags ^ old->flags) & FSNOTIFY_MARK_FLAG_WEAK_FSID) return -EXDEV; /* Allow mixing of marks with strong fsid from different fs */ if (!fsid->weak) return 0; /* Do not allow mixing marks with weak fsid from different fs */ if (old_sb != fsid->sb) return -EXDEV; /* Do not allow mixing marks from different btrfs sub-volumes */ if (!fanotify_fsid_equal(&FANOTIFY_MARK(old)->fsid, &FANOTIFY_MARK(mark)->fsid)) return -EXDEV; return 0; } static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, void *obj, unsigned int obj_type, unsigned int fan_flags, struct fan_fsid *fsid) { struct ucounts *ucounts = group->fanotify_data.ucounts; struct fanotify_mark *fan_mark; struct fsnotify_mark *mark; int ret; /* * Enforce per user marks limits per user in all containing user ns. * A group with FAN_UNLIMITED_MARKS does not contribute to mark count * in the limited groups account. */ if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS) && !inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_FANOTIFY_MARKS)) return ERR_PTR(-ENOSPC); fan_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!fan_mark) { ret = -ENOMEM; goto out_dec_ucounts; } mark = &fan_mark->fsn_mark; fsnotify_init_mark(mark, group); if (fan_flags & FAN_MARK_EVICTABLE) mark->flags |= FSNOTIFY_MARK_FLAG_NO_IREF; /* Cache fsid of filesystem containing the marked object */ if (fsid) { ret = fanotify_set_mark_fsid(group, mark, fsid); if (ret) goto out_put_mark; } else { fan_mark->fsid.val[0] = fan_mark->fsid.val[1] = 0; } ret = fsnotify_add_mark_locked(mark, obj, obj_type, 0); if (ret) goto out_put_mark; return mark; out_put_mark: fsnotify_put_mark(mark); out_dec_ucounts: if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS)) dec_ucount(ucounts, UCOUNT_FANOTIFY_MARKS); return ERR_PTR(ret); } static int fanotify_group_init_error_pool(struct fsnotify_group *group) { if (mempool_initialized(&group->fanotify_data.error_events_pool)) return 0; return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool, FANOTIFY_DEFAULT_FEE_POOL_SIZE, sizeof(struct fanotify_error_event)); } static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark, unsigned int fan_flags) { /* * Non evictable mark cannot be downgraded to evictable mark. */ if (fan_flags & FAN_MARK_EVICTABLE && !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)) return -EEXIST; /* * New ignore mask semantics cannot be downgraded to old semantics. */ if (fan_flags & FAN_MARK_IGNORED_MASK && fsn_mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS) return -EEXIST; /* * An ignore mask that survives modify could never be downgraded to not * survive modify. With new FAN_MARK_IGNORE semantics we make that rule * explicit and return an error when trying to update the ignore mask * without the original FAN_MARK_IGNORED_SURV_MODIFY value. */ if (fan_flags & FAN_MARK_IGNORE && !(fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) && fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY) return -EEXIST; return 0; } static int fanotify_add_mark(struct fsnotify_group *group, void *obj, unsigned int obj_type, __u32 mask, unsigned int fan_flags, struct fan_fsid *fsid) { struct fsnotify_mark *fsn_mark; bool recalc; int ret = 0; fsnotify_group_lock(group); fsn_mark = fsnotify_find_mark(obj, obj_type, group); if (!fsn_mark) { fsn_mark = fanotify_add_new_mark(group, obj, obj_type, fan_flags, fsid); if (IS_ERR(fsn_mark)) { fsnotify_group_unlock(group); return PTR_ERR(fsn_mark); } } /* * Check if requested mark flags conflict with an existing mark flags. */ ret = fanotify_may_update_existing_mark(fsn_mark, fan_flags); if (ret) goto out; /* * Error events are pre-allocated per group, only if strictly * needed (i.e. FAN_FS_ERROR was requested). */ if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS) && (mask & FAN_FS_ERROR)) { ret = fanotify_group_init_error_pool(group); if (ret) goto out; } recalc = fanotify_mark_add_to_mask(fsn_mark, mask, fan_flags); if (recalc) fsnotify_recalc_mask(fsn_mark->connector); out: fsnotify_group_unlock(group); fsnotify_put_mark(fsn_mark); return ret; } static struct fsnotify_event *fanotify_alloc_overflow_event(void) { struct fanotify_event *oevent; oevent = kmalloc(sizeof(*oevent), GFP_KERNEL_ACCOUNT); if (!oevent) return NULL; fanotify_init_event(oevent, 0, FS_Q_OVERFLOW); oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW; return &oevent->fse; } static struct hlist_head *fanotify_alloc_merge_hash(void) { struct hlist_head *hash; hash = kmalloc(sizeof(struct hlist_head) << FANOTIFY_HTABLE_BITS, GFP_KERNEL_ACCOUNT); if (!hash) return NULL; __hash_init(hash, FANOTIFY_HTABLE_SIZE); return hash; } /* fanotify syscalls */ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) { struct fsnotify_group *group; int f_flags, fd; unsigned int fid_mode = flags & FANOTIFY_FID_BITS; unsigned int class = flags & FANOTIFY_CLASS_BITS; unsigned int internal_flags = 0; pr_debug("%s: flags=%x event_f_flags=%x\n", __func__, flags, event_f_flags); if (!capable(CAP_SYS_ADMIN)) { /* * An unprivileged user can setup an fanotify group with * limited functionality - an unprivileged group is limited to * notification events with file handles and it cannot use * unlimited queue/marks. */ if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) || !fid_mode) return -EPERM; /* * Setting the internal flag FANOTIFY_UNPRIV on the group * prevents setting mount/filesystem marks on this group and * prevents reporting pid and open fd in events. */ internal_flags |= FANOTIFY_UNPRIV; } #ifdef CONFIG_AUDITSYSCALL if (flags & ~(FANOTIFY_INIT_FLAGS | FAN_ENABLE_AUDIT)) #else if (flags & ~FANOTIFY_INIT_FLAGS) #endif return -EINVAL; /* * A pidfd can only be returned for a thread-group leader; thus * FAN_REPORT_PIDFD and FAN_REPORT_TID need to remain mutually * exclusive. */ if ((flags & FAN_REPORT_PIDFD) && (flags & FAN_REPORT_TID)) return -EINVAL; if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) return -EINVAL; switch (event_f_flags & O_ACCMODE) { case O_RDONLY: case O_RDWR: case O_WRONLY: break; default: return -EINVAL; } if (fid_mode && class != FAN_CLASS_NOTIF) return -EINVAL; /* * Child name is reported with parent fid so requires dir fid. * We can report both child fid and dir fid with or without name. */ if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID)) return -EINVAL; /* * FAN_REPORT_TARGET_FID requires FAN_REPORT_NAME and FAN_REPORT_FID * and is used as an indication to report both dir and child fid on all * dirent events. */ if ((fid_mode & FAN_REPORT_TARGET_FID) && (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID))) return -EINVAL; f_flags = O_RDWR | __FMODE_NONOTIFY; if (flags & FAN_CLOEXEC) f_flags |= O_CLOEXEC; if (flags & FAN_NONBLOCK) f_flags |= O_NONBLOCK; /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ group = fsnotify_alloc_group(&fanotify_fsnotify_ops, FSNOTIFY_GROUP_USER); if (IS_ERR(group)) { return PTR_ERR(group); } /* Enforce groups limits per user in all containing user ns */ group->fanotify_data.ucounts = inc_ucount(current_user_ns(), current_euid(), UCOUNT_FANOTIFY_GROUPS); if (!group->fanotify_data.ucounts) { fd = -EMFILE; goto out_destroy_group; } group->fanotify_data.flags = flags | internal_flags; group->memcg = get_mem_cgroup_from_mm(current->mm); group->fanotify_data.merge_hash = fanotify_alloc_merge_hash(); if (!group->fanotify_data.merge_hash) { fd = -ENOMEM; goto out_destroy_group; } group->overflow_event = fanotify_alloc_overflow_event(); if (unlikely(!group->overflow_event)) { fd = -ENOMEM; goto out_destroy_group; } if (force_o_largefile()) event_f_flags |= O_LARGEFILE; group->fanotify_data.f_flags = event_f_flags; init_waitqueue_head(&group->fanotify_data.access_waitq); INIT_LIST_HEAD(&group->fanotify_data.access_list); switch (class) { case FAN_CLASS_NOTIF: group->priority = FSNOTIFY_PRIO_NORMAL; break; case FAN_CLASS_CONTENT: group->priority = FSNOTIFY_PRIO_CONTENT; break; case FAN_CLASS_PRE_CONTENT: group->priority = FSNOTIFY_PRIO_PRE_CONTENT; break; default: fd = -EINVAL; goto out_destroy_group; } if (flags & FAN_UNLIMITED_QUEUE) { fd = -EPERM; if (!capable(CAP_SYS_ADMIN)) goto out_destroy_group; group->max_events = UINT_MAX; } else { group->max_events = fanotify_max_queued_events; } if (flags & FAN_UNLIMITED_MARKS) { fd = -EPERM; if (!capable(CAP_SYS_ADMIN)) goto out_destroy_group; } if (flags & FAN_ENABLE_AUDIT) { fd = -EPERM; if (!capable(CAP_AUDIT_WRITE)) goto out_destroy_group; } fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); if (fd < 0) goto out_destroy_group; return fd; out_destroy_group: fsnotify_destroy_group(group); return fd; } static int fanotify_test_fsid(struct dentry *dentry, unsigned int flags, struct fan_fsid *fsid) { unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; __kernel_fsid_t root_fsid; int err; /* * Make sure dentry is not of a filesystem with zero fsid (e.g. fuse). */ err = vfs_get_fsid(dentry, &fsid->id); if (err) return err; fsid->sb = dentry->d_sb; if (!fsid->id.val[0] && !fsid->id.val[1]) { err = -ENODEV; goto weak; } /* * Make sure dentry is not of a filesystem subvolume (e.g. btrfs) * which uses a different fsid than sb root. */ err = vfs_get_fsid(dentry->d_sb->s_root, &root_fsid); if (err) return err; if (!fanotify_fsid_equal(&root_fsid, &fsid->id)) { err = -EXDEV; goto weak; } fsid->weak = false; return 0; weak: /* Allow weak fsid when marking inodes */ fsid->weak = true; return (mark_type == FAN_MARK_INODE) ? 0 : err; } /* Check if filesystem can encode a unique fid */ static int fanotify_test_fid(struct dentry *dentry, unsigned int flags) { unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; const struct export_operations *nop = dentry->d_sb->s_export_op; /* * We need to make sure that the filesystem supports encoding of * file handles so user can use name_to_handle_at() to compare fids * reported with events to the file handle of watched objects. */ if (!exportfs_can_encode_fid(nop)) return -EOPNOTSUPP; /* * For sb/mount mark, we also need to make sure that the filesystem * supports decoding file handles, so user has a way to map back the * reported fids to filesystem objects. */ if (mark_type != FAN_MARK_INODE && !exportfs_can_decode_fh(nop)) return -EOPNOTSUPP; return 0; } static int fanotify_events_supported(struct fsnotify_group *group, const struct path *path, __u64 mask, unsigned int flags) { unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; /* Strict validation of events in non-dir inode mask with v5.17+ APIs */ bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) || (mask & FAN_RENAME) || (flags & FAN_MARK_IGNORE); /* * Some filesystems such as 'proc' acquire unusual locks when opening * files. For them fanotify permission events have high chances of * deadlocking the system - open done when reporting fanotify event * blocks on this "unusual" lock while another process holding the lock * waits for fanotify permission event to be answered. Just disallow * permission events for such filesystems. */ if (mask & FANOTIFY_PERM_EVENTS && path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM) return -EINVAL; /* * mount and sb marks are not allowed on kernel internal pseudo fs, * like pipe_mnt, because that would subscribe to events on all the * anonynous pipes in the system. * * SB_NOUSER covers all of the internal pseudo fs whose objects are not * exposed to user's mount namespace, but there are other SB_KERNMOUNT * fs, like nsfs, debugfs, for which the value of allowing sb and mount * mark is questionable. For now we leave them alone. */ if (mark_type != FAN_MARK_INODE && path->mnt->mnt_sb->s_flags & SB_NOUSER) return -EINVAL; /* * We shouldn't have allowed setting dirent events and the directory * flags FAN_ONDIR and FAN_EVENT_ON_CHILD in mask of non-dir inode, * but because we always allowed it, error only when using new APIs. */ if (strict_dir_events && mark_type == FAN_MARK_INODE && !d_is_dir(path->dentry) && (mask & FANOTIFY_DIRONLY_EVENT_BITS)) return -ENOTDIR; return 0; } static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, int dfd, const char __user *pathname) { struct inode *inode = NULL; struct vfsmount *mnt = NULL; struct fsnotify_group *group; struct path path; struct fan_fsid __fsid, *fsid = NULL; u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS; unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; unsigned int mark_cmd = flags & FANOTIFY_MARK_CMD_BITS; unsigned int ignore = flags & FANOTIFY_MARK_IGNORE_BITS; unsigned int obj_type, fid_mode; void *obj; u32 umask = 0; int ret; pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", __func__, fanotify_fd, flags, dfd, pathname, mask); /* we only use the lower 32 bits as of right now. */ if (upper_32_bits(mask)) return -EINVAL; if (flags & ~FANOTIFY_MARK_FLAGS) return -EINVAL; switch (mark_type) { case FAN_MARK_INODE: obj_type = FSNOTIFY_OBJ_TYPE_INODE; break; case FAN_MARK_MOUNT: obj_type = FSNOTIFY_OBJ_TYPE_VFSMOUNT; break; case FAN_MARK_FILESYSTEM: obj_type = FSNOTIFY_OBJ_TYPE_SB; break; default: return -EINVAL; } switch (mark_cmd) { case FAN_MARK_ADD: case FAN_MARK_REMOVE: if (!mask) return -EINVAL; break; case FAN_MARK_FLUSH: if (flags & ~(FANOTIFY_MARK_TYPE_BITS | FAN_MARK_FLUSH)) return -EINVAL; break; default: return -EINVAL; } if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) valid_mask |= FANOTIFY_PERM_EVENTS; if (mask & ~valid_mask) return -EINVAL; /* We don't allow FAN_MARK_IGNORE & FAN_MARK_IGNORED_MASK together */ if (ignore == (FAN_MARK_IGNORE | FAN_MARK_IGNORED_MASK)) return -EINVAL; /* * Event flags (FAN_ONDIR, FAN_EVENT_ON_CHILD) have no effect with * FAN_MARK_IGNORED_MASK. */ if (ignore == FAN_MARK_IGNORED_MASK) { mask &= ~FANOTIFY_EVENT_FLAGS; umask = FANOTIFY_EVENT_FLAGS; } CLASS(fd, f)(fanotify_fd); if (fd_empty(f)) return -EBADF; /* verify that this is indeed an fanotify instance */ if (unlikely(fd_file(f)->f_op != &fanotify_fops)) return -EINVAL; group = fd_file(f)->private_data; /* * An unprivileged user is not allowed to setup mount nor filesystem * marks. This also includes setting up such marks by a group that * was initialized by an unprivileged user. */ if ((!capable(CAP_SYS_ADMIN) || FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) && mark_type != FAN_MARK_INODE) return -EPERM; /* * Permission events require minimum priority FAN_CLASS_CONTENT. */ if (mask & FANOTIFY_PERM_EVENTS && group->priority < FSNOTIFY_PRIO_CONTENT) return -EINVAL; if (mask & FAN_FS_ERROR && mark_type != FAN_MARK_FILESYSTEM) return -EINVAL; /* * Evictable is only relevant for inode marks, because only inode object * can be evicted on memory pressure. */ if (flags & FAN_MARK_EVICTABLE && mark_type != FAN_MARK_INODE) return -EINVAL; /* * Events that do not carry enough information to report * event->fd require a group that supports reporting fid. Those * events are not supported on a mount mark, because they do not * carry enough information (i.e. path) to be filtered by mount * point. */ fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); if (mask & ~(FANOTIFY_FD_EVENTS|FANOTIFY_EVENT_FLAGS) && (!fid_mode || mark_type == FAN_MARK_MOUNT)) return -EINVAL; /* * FAN_RENAME uses special info type records to report the old and * new parent+name. Reporting only old and new parent id is less * useful and was not implemented. */ if (mask & FAN_RENAME && !(fid_mode & FAN_REPORT_NAME)) return -EINVAL; if (mark_cmd == FAN_MARK_FLUSH) { if (mark_type == FAN_MARK_MOUNT) fsnotify_clear_vfsmount_marks_by_group(group); else if (mark_type == FAN_MARK_FILESYSTEM) fsnotify_clear_sb_marks_by_group(group); else fsnotify_clear_inode_marks_by_group(group); return 0; } ret = fanotify_find_path(dfd, pathname, &path, flags, (mask & ALL_FSNOTIFY_EVENTS), obj_type); if (ret) return ret; if (mark_cmd == FAN_MARK_ADD) { ret = fanotify_events_supported(group, &path, mask, flags); if (ret) goto path_put_and_out; } if (fid_mode) { ret = fanotify_test_fsid(path.dentry, flags, &__fsid); if (ret) goto path_put_and_out; ret = fanotify_test_fid(path.dentry, flags); if (ret) goto path_put_and_out; fsid = &__fsid; } /* inode held in place by reference to path; group by fget on fd */ if (mark_type == FAN_MARK_INODE) { inode = path.dentry->d_inode; obj = inode; } else { mnt = path.mnt; if (mark_type == FAN_MARK_MOUNT) obj = mnt; else obj = mnt->mnt_sb; } /* * If some other task has this inode open for write we should not add * an ignore mask, unless that ignore mask is supposed to survive * modification changes anyway. */ if (mark_cmd == FAN_MARK_ADD && (flags & FANOTIFY_MARK_IGNORE_BITS) && !(flags & FAN_MARK_IGNORED_SURV_MODIFY)) { ret = mnt ? -EINVAL : -EISDIR; /* FAN_MARK_IGNORE requires SURV_MODIFY for sb/mount/dir marks */ if (ignore == FAN_MARK_IGNORE && (mnt || S_ISDIR(inode->i_mode))) goto path_put_and_out; ret = 0; if (inode && inode_is_open_for_write(inode)) goto path_put_and_out; } /* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */ if (mnt || !S_ISDIR(inode->i_mode)) { mask &= ~FAN_EVENT_ON_CHILD; umask = FAN_EVENT_ON_CHILD; /* * If group needs to report parent fid, register for getting * events with parent/name info for non-directory. */ if ((fid_mode & FAN_REPORT_DIR_FID) && (flags & FAN_MARK_ADD) && !ignore) mask |= FAN_EVENT_ON_CHILD; } /* create/update an inode mark */ switch (mark_cmd) { case FAN_MARK_ADD: ret = fanotify_add_mark(group, obj, obj_type, mask, flags, fsid); break; case FAN_MARK_REMOVE: ret = fanotify_remove_mark(group, obj, obj_type, mask, flags, umask); break; default: ret = -EINVAL; } path_put_and_out: path_put(&path); return ret; } #ifndef CONFIG_ARCH_SPLIT_ARG64 SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, __u64, mask, int, dfd, const char __user *, pathname) { return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname); } #endif #if defined(CONFIG_ARCH_SPLIT_ARG64) || defined(CONFIG_COMPAT) SYSCALL32_DEFINE6(fanotify_mark, int, fanotify_fd, unsigned int, flags, SC_ARG64(mask), int, dfd, const char __user *, pathname) { return do_fanotify_mark(fanotify_fd, flags, SC_VAL64(__u64, mask), dfd, pathname); } #endif /* * fanotify_user_setup - Our initialization function. Note that we cannot return * error because we have compiled-in VFS hooks. So an (unlikely) failure here * must result in panic(). */ static int __init fanotify_user_setup(void) { struct sysinfo si; int max_marks; si_meminfo(&si); /* * Allow up to 1% of addressable memory to be accounted for per user * marks limited to the range [8192, 1048576]. mount and sb marks are * a lot cheaper than inode marks, but there is no reason for a user * to have many of those, so calculate by the cost of inode marks. */ max_marks = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) / INODE_MARK_COST; max_marks = clamp(max_marks, FANOTIFY_OLD_DEFAULT_MAX_MARKS, FANOTIFY_DEFAULT_MAX_USER_MARKS); BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS); BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 13); BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 11); fanotify_mark_cache = KMEM_CACHE(fanotify_mark, SLAB_PANIC|SLAB_ACCOUNT); fanotify_fid_event_cachep = KMEM_CACHE(fanotify_fid_event, SLAB_PANIC); fanotify_path_event_cachep = KMEM_CACHE(fanotify_path_event, SLAB_PANIC); if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) { fanotify_perm_event_cachep = KMEM_CACHE(fanotify_perm_event, SLAB_PANIC); } fanotify_max_queued_events = FANOTIFY_DEFAULT_MAX_EVENTS; init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS] = FANOTIFY_DEFAULT_MAX_GROUPS; init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS] = max_marks; fanotify_sysctls_init(); return 0; } device_initcall(fanotify_user_setup);
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