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-rw-r--r--fs/notify/fanotify/fanotify_user.c1900
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);