diff options
Diffstat (limited to 'fs/notify/fanotify/fanotify_user.c')
| -rw-r--r-- | fs/notify/fanotify/fanotify_user.c | 1900 |
1 files changed, 1900 insertions, 0 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c new file mode 100644 index 000000000..9df5db0f1 --- /dev/null +++ b/fs/notify/fanotify/fanotify_user.c @@ -0,0 +1,1900 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/fanotify.h> +#include <linux/fcntl.h> +#include <linux/fdtable.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 "../../mount.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 __read_mostly; +struct kmem_cache *fanotify_fid_event_cachep __read_mostly; +struct kmem_cache *fanotify_path_event_cachep __read_mostly; +struct kmem_cache *fanotify_perm_event_cachep __read_mostly; + +#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)) { + /* + * we still send an event even if we can't open the file. this + * can happen when say tasks are gone and we try to open their + * /proc files or we try to open a WRONLY file like in sysfs + * we just send the errno to userspace since there isn't much + * else we can do. + */ + put_unused_fd(client_fd); + client_fd = PTR_ERR(new_file); + } else { + *file = new_file; + } + + return client_fd; +} + +/* + * 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, + unsigned int response) + __releases(&group->notification_lock) +{ + bool destroy = false; + + assert_spin_locked(&group->notification_lock); + event->response = response; + 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) +{ + struct fanotify_perm_event *event; + int fd = response_struct->fd; + int response = response_struct->response; + + pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group, + fd, response); + /* + * 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 + */ + switch (response & ~FAN_AUDIT) { + case FAN_ALLOW: + case FAN_DENY: + break; + default: + return -EINVAL; + } + + if (fd < 0) + return -EINVAL; + + if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT)) + 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); + wake_up(&group->fanotify_data.access_waitq); + return 0; + } + 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; + int ret, pidfd = FAN_NOPIDFD, fd = FAN_NOFD; + + 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); + if (fd < 0) + return fd; + } + metadata.fd = fd; + + 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. Report FAN_NOPIDFD to the event listener + * in those cases, with all other pidfd creation errors being + * reported as FAN_EPIDFD. + */ + if (metadata.pid == 0 || + !pid_has_task(event->pid, PIDTYPE_TGID)) { + pidfd = FAN_NOPIDFD; + } else { + pidfd = pidfd_create(event->pid, 0); + if (pidfd < 0) + pidfd = 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 (fanotify_is_perm_event(event->mask)) + FANOTIFY_PERM(event)->fd = fd; + + 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); + + return metadata.event_len; + +out_close_fd: + if (fd != FAN_NOFD) { + put_unused_fd(fd); + fput(f); + } + + if (pidfd >= 0) + close_fd(pidfd); + + 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); + if (unlikely(ret == -EOPENSTALE)) { + /* + * We cannot report events with stale fd so drop it. + * Setting ret to 0 will continue the event loop and + * do the right thing if there are no more events to + * read (i.e. return bytes read, -EAGAIN or wait). + */ + ret = 0; + } + + /* + * 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) { + spin_lock(&group->notification_lock); + finish_permission_event(group, + FANOTIFY_PERM(event), FAN_DENY); + 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 = { .fd = -1, .response = -1 }; + struct fsnotify_group *group; + int ret; + + if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) + return -EINVAL; + + group = file->private_data; + + if (count < sizeof(response)) + return -EINVAL; + + count = sizeof(response); + + pr_debug("%s: group=%p count=%zu\n", __func__, group, count); + + if (copy_from_user(&response, buf, count)) + return -EFAULT; + + ret = process_access_response(group, &response); + if (ret < 0) + count = 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); + 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); + } + 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) { + struct fd f = fdget(dfd); + + ret = -EBADF; + if (!f.file) + goto out; + + ret = -ENOTDIR; + if ((flags & FAN_MARK_ONLYDIR) && + !(S_ISDIR(file_inode(f.file)->i_mode))) { + fdput(f); + goto out; + } + + *path = f.file->f_path; + path_get(path); + fdput(f); + } 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, + fsnotify_connp_t *connp, __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(connp, 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 int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, + struct vfsmount *mnt, __u32 mask, + unsigned int flags, __u32 umask) +{ + return fanotify_remove_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, + mask, flags, umask); +} + +static int fanotify_remove_sb_mark(struct fsnotify_group *group, + struct super_block *sb, __u32 mask, + unsigned int flags, __u32 umask) +{ + return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask, + flags, umask); +} + +static int fanotify_remove_inode_mark(struct fsnotify_group *group, + struct inode *inode, __u32 mask, + unsigned int flags, __u32 umask) +{ + return fanotify_remove_mark(group, &inode->i_fsnotify_marks, mask, + flags, umask); +} + +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; +} + +static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, + fsnotify_connp_t *connp, + unsigned int obj_type, + unsigned int fan_flags, + __kernel_fsid_t *fsid) +{ + struct ucounts *ucounts = group->fanotify_data.ucounts; + 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); + + mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); + if (!mark) { + ret = -ENOMEM; + goto out_dec_ucounts; + } + + fsnotify_init_mark(mark, group); + if (fan_flags & FAN_MARK_EVICTABLE) + mark->flags |= FSNOTIFY_MARK_FLAG_NO_IREF; + + ret = fsnotify_add_mark_locked(mark, connp, obj_type, 0, fsid); + if (ret) { + fsnotify_put_mark(mark); + goto out_dec_ucounts; + } + + return 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, + fsnotify_connp_t *connp, unsigned int obj_type, + __u32 mask, unsigned int fan_flags, + __kernel_fsid_t *fsid) +{ + struct fsnotify_mark *fsn_mark; + bool recalc; + int ret = 0; + + fsnotify_group_lock(group); + fsn_mark = fsnotify_find_mark(connp, group); + if (!fsn_mark) { + fsn_mark = fanotify_add_new_mark(group, connp, 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 int fanotify_add_vfsmount_mark(struct fsnotify_group *group, + struct vfsmount *mnt, __u32 mask, + unsigned int flags, __kernel_fsid_t *fsid) +{ + return fanotify_add_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, + FSNOTIFY_OBJ_TYPE_VFSMOUNT, mask, flags, fsid); +} + +static int fanotify_add_sb_mark(struct fsnotify_group *group, + struct super_block *sb, __u32 mask, + unsigned int flags, __kernel_fsid_t *fsid) +{ + return fanotify_add_mark(group, &sb->s_fsnotify_marks, + FSNOTIFY_OBJ_TYPE_SB, mask, flags, fsid); +} + +static int fanotify_add_inode_mark(struct fsnotify_group *group, + struct inode *inode, __u32 mask, + unsigned int flags, __kernel_fsid_t *fsid) +{ + pr_debug("%s: group=%p inode=%p\n", __func__, group, inode); + + /* + * 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 ((flags & FANOTIFY_MARK_IGNORE_BITS) && + !(flags & FAN_MARK_IGNORED_SURV_MODIFY) && + inode_is_open_for_write(inode)) + return 0; + + return fanotify_add_mark(group, &inode->i_fsnotify_marks, + FSNOTIFY_OBJ_TYPE_INODE, mask, flags, fsid); +} + +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 | FSNOTIFY_GROUP_NOFS); + 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 = FS_PRIO_0; + break; + case FAN_CLASS_CONTENT: + group->priority = FS_PRIO_1; + break; + case FAN_CLASS_PRE_CONTENT: + group->priority = FS_PRIO_2; + 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, __kernel_fsid_t *fsid) +{ + __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); + if (err) + return err; + + if (!fsid->val[0] && !fsid->val[1]) + return -ENODEV; + + /* + * 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 (root_fsid.val[0] != fsid->val[0] || + root_fsid.val[1] != fsid->val[1]) + return -EXDEV; + + return 0; +} + +/* Check if filesystem can encode a unique fid */ +static int fanotify_test_fid(struct dentry *dentry) +{ + /* + * We need to make sure that the file system supports at least + * encoding a file handle so user can use name_to_handle_at() to + * compare fid returned with event to the file handle of watched + * objects. However, name_to_handle_at() requires that the + * filesystem also supports decoding file handles. + */ + if (!dentry->d_sb->s_export_op || + !dentry->d_sb->s_export_op->fh_to_dentry) + 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 fd f; + struct path path; + __kernel_fsid_t __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; + 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; + } + + f = fdget(fanotify_fd); + if (unlikely(!f.file)) + return -EBADF; + + /* verify that this is indeed an fanotify instance */ + ret = -EINVAL; + if (unlikely(f.file->f_op != &fanotify_fops)) + goto fput_and_out; + group = f.file->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. + */ + ret = -EPERM; + if ((!capable(CAP_SYS_ADMIN) || + FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) && + mark_type != FAN_MARK_INODE) + goto fput_and_out; + + /* + * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not + * allowed to set permissions events. + */ + ret = -EINVAL; + if (mask & FANOTIFY_PERM_EVENTS && + group->priority == FS_PRIO_0) + goto fput_and_out; + + if (mask & FAN_FS_ERROR && + mark_type != FAN_MARK_FILESYSTEM) + goto fput_and_out; + + /* + * 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) + goto fput_and_out; + + /* + * 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)) + goto fput_and_out; + + /* + * 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)) + goto fput_and_out; + + if (mark_cmd == FAN_MARK_FLUSH) { + ret = 0; + 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); + goto fput_and_out; + } + + ret = fanotify_find_path(dfd, pathname, &path, flags, + (mask & ALL_FSNOTIFY_EVENTS), obj_type); + if (ret) + goto fput_and_out; + + 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, &__fsid); + if (ret) + goto path_put_and_out; + + ret = fanotify_test_fid(path.dentry); + 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; + else + mnt = path.mnt; + + ret = mnt ? -EINVAL : -EISDIR; + /* FAN_MARK_IGNORE requires SURV_MODIFY for sb/mount/dir marks */ + if (mark_cmd == FAN_MARK_ADD && ignore == FAN_MARK_IGNORE && + (mnt || S_ISDIR(inode->i_mode)) && + !(flags & FAN_MARK_IGNORED_SURV_MODIFY)) + 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: + if (mark_type == FAN_MARK_MOUNT) + ret = fanotify_add_vfsmount_mark(group, mnt, mask, + flags, fsid); + else if (mark_type == FAN_MARK_FILESYSTEM) + ret = fanotify_add_sb_mark(group, mnt->mnt_sb, mask, + flags, fsid); + else + ret = fanotify_add_inode_mark(group, inode, mask, + flags, fsid); + break; + case FAN_MARK_REMOVE: + if (mark_type == FAN_MARK_MOUNT) + ret = fanotify_remove_vfsmount_mark(group, mnt, mask, + flags, umask); + else if (mark_type == FAN_MARK_FILESYSTEM) + ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask, + flags, umask); + else + ret = fanotify_remove_inode_mark(group, inode, mask, + flags, umask); + break; + default: + ret = -EINVAL; + } + +path_put_and_out: + path_put(&path); +fput_and_out: + fdput(f); + 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) != 12); + BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 11); + + fanotify_mark_cache = KMEM_CACHE(fsnotify_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); |