Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 3570 insertions, 0 deletions

diff --git a/fs/notify/fanotify/Kconfig b/fs/notify/fanotify/Kconfig
new file mode 100644
index 0000000000..a511f9d867
--- /dev/null
+++ b/fs/notify/fanotify/Kconfig
@@ -0,0 +1,27 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config FANOTIFY
+	bool "Filesystem wide access notification"
+	select FSNOTIFY
+	select EXPORTFS
+	default n
+	help
+	   Say Y here to enable fanotify support.  fanotify is a file access
+	   notification system which differs from inotify in that it sends
+	   an open file descriptor to the userspace listener along with
+	   the event.
+
+	   If unsure, say Y.
+
+config FANOTIFY_ACCESS_PERMISSIONS
+	bool "fanotify permissions checking"
+	depends on FANOTIFY
+	depends on SECURITY
+	default n
+	help
+	   Say Y here is you want fanotify listeners to be able to make permissions
+	   decisions concerning filesystem events.  This is used by some fanotify
+	   listeners which need to scan files before allowing the system access to
+	   use those files.  This is used by some anti-malware vendors and by some
+	   hierarchical storage management systems.
+
+	   If unsure, say N.
diff --git a/fs/notify/fanotify/Makefile b/fs/notify/fanotify/Makefile
new file mode 100644
index 0000000000..25ef222915
--- /dev/null
+++ b/fs/notify/fanotify/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_FANOTIFY)		+= fanotify.o fanotify_user.o
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
new file mode 100644
index 0000000000..9dac7f6e72
--- /dev/null
+++ b/fs/notify/fanotify/fanotify.c
@@ -0,0 +1,1080 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/fanotify.h>
+#include <linux/fdtable.h>
+#include <linux/fsnotify_backend.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h> /* UINT_MAX */
+#include <linux/mount.h>
+#include <linux/sched.h>
+#include <linux/sched/user.h>
+#include <linux/sched/signal.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+#include <linux/audit.h>
+#include <linux/sched/mm.h>
+#include <linux/statfs.h>
+#include <linux/stringhash.h>
+
+#include "fanotify.h"
+
+static bool fanotify_path_equal(const struct path *p1, const struct path *p2)
+{
+	return p1->mnt == p2->mnt && p1->dentry == p2->dentry;
+}
+
+static unsigned int fanotify_hash_path(const struct path *path)
+{
+	return hash_ptr(path->dentry, FANOTIFY_EVENT_HASH_BITS) ^
+		hash_ptr(path->mnt, FANOTIFY_EVENT_HASH_BITS);
+}
+
+static inline bool fanotify_fsid_equal(__kernel_fsid_t *fsid1,
+				       __kernel_fsid_t *fsid2)
+{
+	return fsid1->val[0] == fsid2->val[0] && fsid1->val[1] == fsid2->val[1];
+}
+
+static unsigned int fanotify_hash_fsid(__kernel_fsid_t *fsid)
+{
+	return hash_32(fsid->val[0], FANOTIFY_EVENT_HASH_BITS) ^
+		hash_32(fsid->val[1], FANOTIFY_EVENT_HASH_BITS);
+}
+
+static bool fanotify_fh_equal(struct fanotify_fh *fh1,
+			      struct fanotify_fh *fh2)
+{
+	if (fh1->type != fh2->type || fh1->len != fh2->len)
+		return false;
+
+	return !fh1->len ||
+		!memcmp(fanotify_fh_buf(fh1), fanotify_fh_buf(fh2), fh1->len);
+}
+
+static unsigned int fanotify_hash_fh(struct fanotify_fh *fh)
+{
+	long salt = (long)fh->type | (long)fh->len << 8;
+
+	/*
+	 * full_name_hash() works long by long, so it handles fh buf optimally.
+	 */
+	return full_name_hash((void *)salt, fanotify_fh_buf(fh), fh->len);
+}
+
+static bool fanotify_fid_event_equal(struct fanotify_fid_event *ffe1,
+				     struct fanotify_fid_event *ffe2)
+{
+	/* Do not merge fid events without object fh */
+	if (!ffe1->object_fh.len)
+		return false;
+
+	return fanotify_fsid_equal(&ffe1->fsid, &ffe2->fsid) &&
+		fanotify_fh_equal(&ffe1->object_fh, &ffe2->object_fh);
+}
+
+static bool fanotify_info_equal(struct fanotify_info *info1,
+				struct fanotify_info *info2)
+{
+	if (info1->dir_fh_totlen != info2->dir_fh_totlen ||
+	    info1->dir2_fh_totlen != info2->dir2_fh_totlen ||
+	    info1->file_fh_totlen != info2->file_fh_totlen ||
+	    info1->name_len != info2->name_len ||
+	    info1->name2_len != info2->name2_len)
+		return false;
+
+	if (info1->dir_fh_totlen &&
+	    !fanotify_fh_equal(fanotify_info_dir_fh(info1),
+			       fanotify_info_dir_fh(info2)))
+		return false;
+
+	if (info1->dir2_fh_totlen &&
+	    !fanotify_fh_equal(fanotify_info_dir2_fh(info1),
+			       fanotify_info_dir2_fh(info2)))
+		return false;
+
+	if (info1->file_fh_totlen &&
+	    !fanotify_fh_equal(fanotify_info_file_fh(info1),
+			       fanotify_info_file_fh(info2)))
+		return false;
+
+	if (info1->name_len &&
+	    memcmp(fanotify_info_name(info1), fanotify_info_name(info2),
+		   info1->name_len))
+		return false;
+
+	return !info1->name2_len ||
+		!memcmp(fanotify_info_name2(info1), fanotify_info_name2(info2),
+			info1->name2_len);
+}
+
+static bool fanotify_name_event_equal(struct fanotify_name_event *fne1,
+				      struct fanotify_name_event *fne2)
+{
+	struct fanotify_info *info1 = &fne1->info;
+	struct fanotify_info *info2 = &fne2->info;
+
+	/* Do not merge name events without dir fh */
+	if (!info1->dir_fh_totlen)
+		return false;
+
+	if (!fanotify_fsid_equal(&fne1->fsid, &fne2->fsid))
+		return false;
+
+	return fanotify_info_equal(info1, info2);
+}
+
+static bool fanotify_error_event_equal(struct fanotify_error_event *fee1,
+				       struct fanotify_error_event *fee2)
+{
+	/* Error events against the same file system are always merged. */
+	if (!fanotify_fsid_equal(&fee1->fsid, &fee2->fsid))
+		return false;
+
+	return true;
+}
+
+static bool fanotify_should_merge(struct fanotify_event *old,
+				  struct fanotify_event *new)
+{
+	pr_debug("%s: old=%p new=%p\n", __func__, old, new);
+
+	if (old->hash != new->hash ||
+	    old->type != new->type || old->pid != new->pid)
+		return false;
+
+	/*
+	 * We want to merge many dirent events in the same dir (i.e.
+	 * creates/unlinks/renames), but we do not want to merge dirent
+	 * events referring to subdirs with dirent events referring to
+	 * non subdirs, otherwise, user won't be able to tell from a
+	 * mask FAN_CREATE|FAN_DELETE|FAN_ONDIR if it describes mkdir+
+	 * unlink pair or rmdir+create pair of events.
+	 */
+	if ((old->mask & FS_ISDIR) != (new->mask & FS_ISDIR))
+		return false;
+
+	/*
+	 * FAN_RENAME event is reported with special info record types,
+	 * so we cannot merge it with other events.
+	 */
+	if ((old->mask & FAN_RENAME) != (new->mask & FAN_RENAME))
+		return false;
+
+	switch (old->type) {
+	case FANOTIFY_EVENT_TYPE_PATH:
+		return fanotify_path_equal(fanotify_event_path(old),
+					   fanotify_event_path(new));
+	case FANOTIFY_EVENT_TYPE_FID:
+		return fanotify_fid_event_equal(FANOTIFY_FE(old),
+						FANOTIFY_FE(new));
+	case FANOTIFY_EVENT_TYPE_FID_NAME:
+		return fanotify_name_event_equal(FANOTIFY_NE(old),
+						 FANOTIFY_NE(new));
+	case FANOTIFY_EVENT_TYPE_FS_ERROR:
+		return fanotify_error_event_equal(FANOTIFY_EE(old),
+						  FANOTIFY_EE(new));
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	return false;
+}
+
+/* Limit event merges to limit CPU overhead per event */
+#define FANOTIFY_MAX_MERGE_EVENTS 128
+
+/* and the list better be locked by something too! */
+static int fanotify_merge(struct fsnotify_group *group,
+			  struct fsnotify_event *event)
+{
+	struct fanotify_event *old, *new = FANOTIFY_E(event);
+	unsigned int bucket = fanotify_event_hash_bucket(group, new);
+	struct hlist_head *hlist = &group->fanotify_data.merge_hash[bucket];
+	int i = 0;
+
+	pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
+		 group, event, bucket);
+
+	/*
+	 * Don't merge a permission event with any other event so that we know
+	 * the event structure we have created in fanotify_handle_event() is the
+	 * one we should check for permission response.
+	 */
+	if (fanotify_is_perm_event(new->mask))
+		return 0;
+
+	hlist_for_each_entry(old, hlist, merge_list) {
+		if (++i > FANOTIFY_MAX_MERGE_EVENTS)
+			break;
+		if (fanotify_should_merge(old, new)) {
+			old->mask |= new->mask;
+
+			if (fanotify_is_error_event(old->mask))
+				FANOTIFY_EE(old)->err_count++;
+
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Wait for response to permission event. The function also takes care of
+ * freeing the permission event (or offloads that in case the wait is canceled
+ * by a signal). The function returns 0 in case access got allowed by userspace,
+ * -EPERM in case userspace disallowed the access, and -ERESTARTSYS in case
+ * the wait got interrupted by a signal.
+ */
+static int fanotify_get_response(struct fsnotify_group *group,
+				 struct fanotify_perm_event *event,
+				 struct fsnotify_iter_info *iter_info)
+{
+	int ret;
+
+	pr_debug("%s: group=%p event=%p\n", __func__, group, event);
+
+	ret = wait_event_killable(group->fanotify_data.access_waitq,
+				  event->state == FAN_EVENT_ANSWERED);
+	/* Signal pending? */
+	if (ret < 0) {
+		spin_lock(&group->notification_lock);
+		/* Event reported to userspace and no answer yet? */
+		if (event->state == FAN_EVENT_REPORTED) {
+			/* Event will get freed once userspace answers to it */
+			event->state = FAN_EVENT_CANCELED;
+			spin_unlock(&group->notification_lock);
+			return ret;
+		}
+		/* Event not yet reported? Just remove it. */
+		if (event->state == FAN_EVENT_INIT) {
+			fsnotify_remove_queued_event(group, &event->fae.fse);
+			/* Permission events are not supposed to be hashed */
+			WARN_ON_ONCE(!hlist_unhashed(&event->fae.merge_list));
+		}
+		/*
+		 * Event may be also answered in case signal delivery raced
+		 * with wakeup. In that case we have nothing to do besides
+		 * freeing the event and reporting error.
+		 */
+		spin_unlock(&group->notification_lock);
+		goto out;
+	}
+
+	/* userspace responded, convert to something usable */
+	switch (event->response & FANOTIFY_RESPONSE_ACCESS) {
+	case FAN_ALLOW:
+		ret = 0;
+		break;
+	case FAN_DENY:
+	default:
+		ret = -EPERM;
+	}
+
+	/* Check if the response should be audited */
+	if (event->response & FAN_AUDIT)
+		audit_fanotify(event->response & ~FAN_AUDIT,
+			       &event->audit_rule);
+
+	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
+		 group, event, ret);
+out:
+	fsnotify_destroy_event(group, &event->fae.fse);
+
+	return ret;
+}
+
+/*
+ * This function returns a mask for an event that only contains the flags
+ * that have been specifically requested by the user. Flags that may have
+ * been included within the event mask, but have not been explicitly
+ * requested by the user, will not be present in the returned mask.
+ */
+static u32 fanotify_group_event_mask(struct fsnotify_group *group,
+				     struct fsnotify_iter_info *iter_info,
+				     u32 *match_mask, u32 event_mask,
+				     const void *data, int data_type,
+				     struct inode *dir)
+{
+	__u32 marks_mask = 0, marks_ignore_mask = 0;
+	__u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS |
+				     FANOTIFY_EVENT_FLAGS;
+	const struct path *path = fsnotify_data_path(data, data_type);
+	unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
+	struct fsnotify_mark *mark;
+	bool ondir = event_mask & FAN_ONDIR;
+	int type;
+
+	pr_debug("%s: report_mask=%x mask=%x data=%p data_type=%d\n",
+		 __func__, iter_info->report_mask, event_mask, data, data_type);
+
+	if (!fid_mode) {
+		/* Do we have path to open a file descriptor? */
+		if (!path)
+			return 0;
+		/* Path type events are only relevant for files and dirs */
+		if (!d_is_reg(path->dentry) && !d_can_lookup(path->dentry))
+			return 0;
+	} else if (!(fid_mode & FAN_REPORT_FID)) {
+		/* Do we have a directory inode to report? */
+		if (!dir && !ondir)
+			return 0;
+	}
+
+	fsnotify_foreach_iter_mark_type(iter_info, mark, type) {
+		/*
+		 * Apply ignore mask depending on event flags in ignore mask.
+		 */
+		marks_ignore_mask |=
+			fsnotify_effective_ignore_mask(mark, ondir, type);
+
+		/*
+		 * Send the event depending on event flags in mark mask.
+		 */
+		if (!fsnotify_mask_applicable(mark->mask, ondir, type))
+			continue;
+
+		marks_mask |= mark->mask;
+
+		/* Record the mark types of this group that matched the event */
+		*match_mask |= 1U << type;
+	}
+
+	test_mask = event_mask & marks_mask & ~marks_ignore_mask;
+
+	/*
+	 * For dirent modification events (create/delete/move) that do not carry
+	 * the child entry name information, we report FAN_ONDIR for mkdir/rmdir
+	 * so user can differentiate them from creat/unlink.
+	 *
+	 * For backward compatibility and consistency, do not report FAN_ONDIR
+	 * to user in legacy fanotify mode (reporting fd) and report FAN_ONDIR
+	 * to user in fid mode for all event types.
+	 *
+	 * We never report FAN_EVENT_ON_CHILD to user, but we do pass it in to
+	 * fanotify_alloc_event() when group is reporting fid as indication
+	 * that event happened on child.
+	 */
+	if (fid_mode) {
+		/* Do not report event flags without any event */
+		if (!(test_mask & ~FANOTIFY_EVENT_FLAGS))
+			return 0;
+	} else {
+		user_mask &= ~FANOTIFY_EVENT_FLAGS;
+	}
+
+	return test_mask & user_mask;
+}
+
+/*
+ * Check size needed to encode fanotify_fh.
+ *
+ * Return size of encoded fh without fanotify_fh header.
+ * Return 0 on failure to encode.
+ */
+static int fanotify_encode_fh_len(struct inode *inode)
+{
+	int dwords = 0;
+	int fh_len;
+
+	if (!inode)
+		return 0;
+
+	exportfs_encode_fid(inode, NULL, &dwords);
+	fh_len = dwords << 2;
+
+	/*
+	 * struct fanotify_error_event might be preallocated and is
+	 * limited to MAX_HANDLE_SZ.  This should never happen, but
+	 * safeguard by forcing an invalid file handle.
+	 */
+	if (WARN_ON_ONCE(fh_len > MAX_HANDLE_SZ))
+		return 0;
+
+	return fh_len;
+}
+
+/*
+ * Encode fanotify_fh.
+ *
+ * Return total size of encoded fh including fanotify_fh header.
+ * Return 0 on failure to encode.
+ */
+static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
+			      unsigned int fh_len, unsigned int *hash,
+			      gfp_t gfp)
+{
+	int dwords, type = 0;
+	char *ext_buf = NULL;
+	void *buf = fh->buf;
+	int err;
+
+	fh->type = FILEID_ROOT;
+	fh->len = 0;
+	fh->flags = 0;
+
+	/*
+	 * Invalid FHs are used by FAN_FS_ERROR for errors not
+	 * linked to any inode. The f_handle won't be reported
+	 * back to userspace.
+	 */
+	if (!inode)
+		goto out;
+
+	/*
+	 * !gpf means preallocated variable size fh, but fh_len could
+	 * be zero in that case if encoding fh len failed.
+	 */
+	err = -ENOENT;
+	if (fh_len < 4 || WARN_ON_ONCE(fh_len % 4) || fh_len > MAX_HANDLE_SZ)
+		goto out_err;
+
+	/* No external buffer in a variable size allocated fh */
+	if (gfp && fh_len > FANOTIFY_INLINE_FH_LEN) {
+		/* Treat failure to allocate fh as failure to encode fh */
+		err = -ENOMEM;
+		ext_buf = kmalloc(fh_len, gfp);
+		if (!ext_buf)
+			goto out_err;
+
+		*fanotify_fh_ext_buf_ptr(fh) = ext_buf;
+		buf = ext_buf;
+		fh->flags |= FANOTIFY_FH_FLAG_EXT_BUF;
+	}
+
+	dwords = fh_len >> 2;
+	type = exportfs_encode_fid(inode, buf, &dwords);
+	err = -EINVAL;
+	if (type <= 0 || type == FILEID_INVALID || fh_len != dwords << 2)
+		goto out_err;
+
+	fh->type = type;
+	fh->len = fh_len;
+
+out:
+	/*
+	 * Mix fh into event merge key.  Hash might be NULL in case of
+	 * unhashed FID events (i.e. FAN_FS_ERROR).
+	 */
+	if (hash)
+		*hash ^= fanotify_hash_fh(fh);
+
+	return FANOTIFY_FH_HDR_LEN + fh_len;
+
+out_err:
+	pr_warn_ratelimited("fanotify: failed to encode fid (type=%d, len=%d, err=%i)\n",
+			    type, fh_len, err);
+	kfree(ext_buf);
+	*fanotify_fh_ext_buf_ptr(fh) = NULL;
+	/* Report the event without a file identifier on encode error */
+	fh->type = FILEID_INVALID;
+	fh->len = 0;
+	return 0;
+}
+
+/*
+ * FAN_REPORT_FID is ambiguous in that it reports the fid of the child for
+ * some events and the fid of the parent for create/delete/move events.
+ *
+ * With the FAN_REPORT_TARGET_FID flag, the fid of the child is reported
+ * also in create/delete/move events in addition to the fid of the parent
+ * and the name of the child.
+ */
+static inline bool fanotify_report_child_fid(unsigned int fid_mode, u32 mask)
+{
+	if (mask & ALL_FSNOTIFY_DIRENT_EVENTS)
+		return (fid_mode & FAN_REPORT_TARGET_FID);
+
+	return (fid_mode & FAN_REPORT_FID) && !(mask & FAN_ONDIR);
+}
+
+/*
+ * The inode to use as identifier when reporting fid depends on the event
+ * and the group flags.
+ *
+ * With the group flag FAN_REPORT_TARGET_FID, always report the child fid.
+ *
+ * Without the group flag FAN_REPORT_TARGET_FID, report the modified directory
+ * fid on dirent events and the child fid otherwise.
+ *
+ * For example:
+ * FS_ATTRIB reports the child fid even if reported on a watched parent.
+ * FS_CREATE reports the modified dir fid without FAN_REPORT_TARGET_FID.
+ *       and reports the created child fid with FAN_REPORT_TARGET_FID.
+ */
+static struct inode *fanotify_fid_inode(u32 event_mask, const void *data,
+					int data_type, struct inode *dir,
+					unsigned int fid_mode)
+{
+	if ((event_mask & ALL_FSNOTIFY_DIRENT_EVENTS) &&
+	    !(fid_mode & FAN_REPORT_TARGET_FID))
+		return dir;
+
+	return fsnotify_data_inode(data, data_type);
+}
+
+/*
+ * The inode to use as identifier when reporting dir fid depends on the event.
+ * Report the modified directory inode on dirent modification events.
+ * Report the "victim" inode if "victim" is a directory.
+ * Report the parent inode if "victim" is not a directory and event is
+ * reported to parent.
+ * Otherwise, do not report dir fid.
+ */
+static struct inode *fanotify_dfid_inode(u32 event_mask, const void *data,
+					 int data_type, struct inode *dir)
+{
+	struct inode *inode = fsnotify_data_inode(data, data_type);
+
+	if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)
+		return dir;
+
+	if (inode && S_ISDIR(inode->i_mode))
+		return inode;
+
+	return dir;
+}
+
+static struct fanotify_event *fanotify_alloc_path_event(const struct path *path,
+							unsigned int *hash,
+							gfp_t gfp)
+{
+	struct fanotify_path_event *pevent;
+
+	pevent = kmem_cache_alloc(fanotify_path_event_cachep, gfp);
+	if (!pevent)
+		return NULL;
+
+	pevent->fae.type = FANOTIFY_EVENT_TYPE_PATH;
+	pevent->path = *path;
+	*hash ^= fanotify_hash_path(path);
+	path_get(path);
+
+	return &pevent->fae;
+}
+
+static struct fanotify_event *fanotify_alloc_perm_event(const struct path *path,
+							gfp_t gfp)
+{
+	struct fanotify_perm_event *pevent;
+
+	pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
+	if (!pevent)
+		return NULL;
+
+	pevent->fae.type = FANOTIFY_EVENT_TYPE_PATH_PERM;
+	pevent->response = 0;
+	pevent->hdr.type = FAN_RESPONSE_INFO_NONE;
+	pevent->hdr.pad = 0;
+	pevent->hdr.len = 0;
+	pevent->state = FAN_EVENT_INIT;
+	pevent->path = *path;
+	path_get(path);
+
+	return &pevent->fae;
+}
+
+static struct fanotify_event *fanotify_alloc_fid_event(struct inode *id,
+						       __kernel_fsid_t *fsid,
+						       unsigned int *hash,
+						       gfp_t gfp)
+{
+	struct fanotify_fid_event *ffe;
+
+	ffe = kmem_cache_alloc(fanotify_fid_event_cachep, gfp);
+	if (!ffe)
+		return NULL;
+
+	ffe->fae.type = FANOTIFY_EVENT_TYPE_FID;
+	ffe->fsid = *fsid;
+	*hash ^= fanotify_hash_fsid(fsid);
+	fanotify_encode_fh(&ffe->object_fh, id, fanotify_encode_fh_len(id),
+			   hash, gfp);
+
+	return &ffe->fae;
+}
+
+static struct fanotify_event *fanotify_alloc_name_event(struct inode *dir,
+							__kernel_fsid_t *fsid,
+							const struct qstr *name,
+							struct inode *child,
+							struct dentry *moved,
+							unsigned int *hash,
+							gfp_t gfp)
+{
+	struct fanotify_name_event *fne;
+	struct fanotify_info *info;
+	struct fanotify_fh *dfh, *ffh;
+	struct inode *dir2 = moved ? d_inode(moved->d_parent) : NULL;
+	const struct qstr *name2 = moved ? &moved->d_name : NULL;
+	unsigned int dir_fh_len = fanotify_encode_fh_len(dir);
+	unsigned int dir2_fh_len = fanotify_encode_fh_len(dir2);
+	unsigned int child_fh_len = fanotify_encode_fh_len(child);
+	unsigned long name_len = name ? name->len : 0;
+	unsigned long name2_len = name2 ? name2->len : 0;
+	unsigned int len, size;
+
+	/* Reserve terminating null byte even for empty name */
+	size = sizeof(*fne) + name_len + name2_len + 2;
+	if (dir_fh_len)
+		size += FANOTIFY_FH_HDR_LEN + dir_fh_len;
+	if (dir2_fh_len)
+		size += FANOTIFY_FH_HDR_LEN + dir2_fh_len;
+	if (child_fh_len)
+		size += FANOTIFY_FH_HDR_LEN + child_fh_len;
+	fne = kmalloc(size, gfp);
+	if (!fne)
+		return NULL;
+
+	fne->fae.type = FANOTIFY_EVENT_TYPE_FID_NAME;
+	fne->fsid = *fsid;
+	*hash ^= fanotify_hash_fsid(fsid);
+	info = &fne->info;
+	fanotify_info_init(info);
+	if (dir_fh_len) {
+		dfh = fanotify_info_dir_fh(info);
+		len = fanotify_encode_fh(dfh, dir, dir_fh_len, hash, 0);
+		fanotify_info_set_dir_fh(info, len);
+	}
+	if (dir2_fh_len) {
+		dfh = fanotify_info_dir2_fh(info);
+		len = fanotify_encode_fh(dfh, dir2, dir2_fh_len, hash, 0);
+		fanotify_info_set_dir2_fh(info, len);
+	}
+	if (child_fh_len) {
+		ffh = fanotify_info_file_fh(info);
+		len = fanotify_encode_fh(ffh, child, child_fh_len, hash, 0);
+		fanotify_info_set_file_fh(info, len);
+	}
+	if (name_len) {
+		fanotify_info_copy_name(info, name);
+		*hash ^= full_name_hash((void *)name_len, name->name, name_len);
+	}
+	if (name2_len) {
+		fanotify_info_copy_name2(info, name2);
+		*hash ^= full_name_hash((void *)name2_len, name2->name,
+					name2_len);
+	}
+
+	pr_debug("%s: size=%u dir_fh_len=%u child_fh_len=%u name_len=%u name='%.*s'\n",
+		 __func__, size, dir_fh_len, child_fh_len,
+		 info->name_len, info->name_len, fanotify_info_name(info));
+
+	if (dir2_fh_len) {
+		pr_debug("%s: dir2_fh_len=%u name2_len=%u name2='%.*s'\n",
+			 __func__, dir2_fh_len, info->name2_len,
+			 info->name2_len, fanotify_info_name2(info));
+	}
+
+	return &fne->fae;
+}
+
+static struct fanotify_event *fanotify_alloc_error_event(
+						struct fsnotify_group *group,
+						__kernel_fsid_t *fsid,
+						const void *data, int data_type,
+						unsigned int *hash)
+{
+	struct fs_error_report *report =
+			fsnotify_data_error_report(data, data_type);
+	struct inode *inode;
+	struct fanotify_error_event *fee;
+	int fh_len;
+
+	if (WARN_ON_ONCE(!report))
+		return NULL;
+
+	fee = mempool_alloc(&group->fanotify_data.error_events_pool, GFP_NOFS);
+	if (!fee)
+		return NULL;
+
+	fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
+	fee->error = report->error;
+	fee->err_count = 1;
+	fee->fsid = *fsid;
+
+	inode = report->inode;
+	fh_len = fanotify_encode_fh_len(inode);
+
+	/* Bad fh_len. Fallback to using an invalid fh. Should never happen. */
+	if (!fh_len && inode)
+		inode = NULL;
+
+	fanotify_encode_fh(&fee->object_fh, inode, fh_len, NULL, 0);
+
+	*hash ^= fanotify_hash_fsid(fsid);
+
+	return &fee->fae;
+}
+
+static struct fanotify_event *fanotify_alloc_event(
+				struct fsnotify_group *group,
+				u32 mask, const void *data, int data_type,
+				struct inode *dir, const struct qstr *file_name,
+				__kernel_fsid_t *fsid, u32 match_mask)
+{
+	struct fanotify_event *event = NULL;
+	gfp_t gfp = GFP_KERNEL_ACCOUNT;
+	unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
+	struct inode *id = fanotify_fid_inode(mask, data, data_type, dir,
+					      fid_mode);
+	struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir);
+	const struct path *path = fsnotify_data_path(data, data_type);
+	struct mem_cgroup *old_memcg;
+	struct dentry *moved = NULL;
+	struct inode *child = NULL;
+	bool name_event = false;
+	unsigned int hash = 0;
+	bool ondir = mask & FAN_ONDIR;
+	struct pid *pid;
+
+	if ((fid_mode & FAN_REPORT_DIR_FID) && dirid) {
+		/*
+		 * For certain events and group flags, report the child fid
+		 * in addition to reporting the parent fid and maybe child name.
+		 */
+		if (fanotify_report_child_fid(fid_mode, mask) && id != dirid)
+			child = id;
+
+		id = dirid;
+
+		/*
+		 * We record file name only in a group with FAN_REPORT_NAME
+		 * and when we have a directory inode to report.
+		 *
+		 * For directory entry modification event, we record the fid of
+		 * the directory and the name of the modified entry.
+		 *
+		 * For event on non-directory that is reported to parent, we
+		 * record the fid of the parent and the name of the child.
+		 *
+		 * Even if not reporting name, we need a variable length
+		 * fanotify_name_event if reporting both parent and child fids.
+		 */
+		if (!(fid_mode & FAN_REPORT_NAME)) {
+			name_event = !!child;
+			file_name = NULL;
+		} else if ((mask & ALL_FSNOTIFY_DIRENT_EVENTS) || !ondir) {
+			name_event = true;
+		}
+
+		/*
+		 * In the special case of FAN_RENAME event, use the match_mask
+		 * to determine if we need to report only the old parent+name,
+		 * only the new parent+name or both.
+		 * 'dirid' and 'file_name' are the old parent+name and
+		 * 'moved' has the new parent+name.
+		 */
+		if (mask & FAN_RENAME) {
+			bool report_old, report_new;
+
+			if (WARN_ON_ONCE(!match_mask))
+				return NULL;
+
+			/* Report both old and new parent+name if sb watching */
+			report_old = report_new =
+				match_mask & (1U << FSNOTIFY_ITER_TYPE_SB);
+			report_old |=
+				match_mask & (1U << FSNOTIFY_ITER_TYPE_INODE);
+			report_new |=
+				match_mask & (1U << FSNOTIFY_ITER_TYPE_INODE2);
+
+			if (!report_old) {
+				/* Do not report old parent+name */
+				dirid = NULL;
+				file_name = NULL;
+			}
+			if (report_new) {
+				/* Report new parent+name */
+				moved = fsnotify_data_dentry(data, data_type);
+			}
+		}
+	}
+
+	/*
+	 * For queues with unlimited length lost events are not expected and
+	 * can possibly have security implications. Avoid losing events when
+	 * memory is short. For the limited size queues, avoid OOM killer in the
+	 * target monitoring memcg as it may have security repercussion.
+	 */
+	if (group->max_events == UINT_MAX)
+		gfp |= __GFP_NOFAIL;
+	else
+		gfp |= __GFP_RETRY_MAYFAIL;
+
+	/* Whoever is interested in the event, pays for the allocation. */
+	old_memcg = set_active_memcg(group->memcg);
+
+	if (fanotify_is_perm_event(mask)) {
+		event = fanotify_alloc_perm_event(path, gfp);
+	} else if (fanotify_is_error_event(mask)) {
+		event = fanotify_alloc_error_event(group, fsid, data,
+						   data_type, &hash);
+	} else if (name_event && (file_name || moved || child)) {
+		event = fanotify_alloc_name_event(dirid, fsid, file_name, child,
+						  moved, &hash, gfp);
+	} else if (fid_mode) {
+		event = fanotify_alloc_fid_event(id, fsid, &hash, gfp);
+	} else {
+		event = fanotify_alloc_path_event(path, &hash, gfp);
+	}
+
+	if (!event)
+		goto out;
+
+	if (FAN_GROUP_FLAG(group, FAN_REPORT_TID))
+		pid = get_pid(task_pid(current));
+	else
+		pid = get_pid(task_tgid(current));
+
+	/* Mix event info, FAN_ONDIR flag and pid into event merge key */
+	hash ^= hash_long((unsigned long)pid | ondir, FANOTIFY_EVENT_HASH_BITS);
+	fanotify_init_event(event, hash, mask);
+	event->pid = pid;
+
+out:
+	set_active_memcg(old_memcg);
+	return event;
+}
+
+/*
+ * Get cached fsid of the filesystem containing the object from any connector.
+ * All connectors are supposed to have the same fsid, but we do not verify that
+ * here.
+ */
+static __kernel_fsid_t fanotify_get_fsid(struct fsnotify_iter_info *iter_info)
+{
+	struct fsnotify_mark *mark;
+	int type;
+	__kernel_fsid_t fsid = {};
+
+	fsnotify_foreach_iter_mark_type(iter_info, mark, type) {
+		struct fsnotify_mark_connector *conn;
+
+		conn = READ_ONCE(mark->connector);
+		/* Mark is just getting destroyed or created? */
+		if (!conn)
+			continue;
+		if (!(conn->flags & FSNOTIFY_CONN_FLAG_HAS_FSID))
+			continue;
+		/* Pairs with smp_wmb() in fsnotify_add_mark_list() */
+		smp_rmb();
+		fsid = conn->fsid;
+		if (WARN_ON_ONCE(!fsid.val[0] && !fsid.val[1]))
+			continue;
+		return fsid;
+	}
+
+	return fsid;
+}
+
+/*
+ * Add an event to hash table for faster merge.
+ */
+static void fanotify_insert_event(struct fsnotify_group *group,
+				  struct fsnotify_event *fsn_event)
+{
+	struct fanotify_event *event = FANOTIFY_E(fsn_event);
+	unsigned int bucket = fanotify_event_hash_bucket(group, event);
+	struct hlist_head *hlist = &group->fanotify_data.merge_hash[bucket];
+
+	assert_spin_locked(&group->notification_lock);
+
+	if (!fanotify_is_hashed_event(event->mask))
+		return;
+
+	pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
+		 group, event, bucket);
+
+	hlist_add_head(&event->merge_list, hlist);
+}
+
+static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
+				 const void *data, int data_type,
+				 struct inode *dir,
+				 const struct qstr *file_name, u32 cookie,
+				 struct fsnotify_iter_info *iter_info)
+{
+	int ret = 0;
+	struct fanotify_event *event;
+	struct fsnotify_event *fsn_event;
+	__kernel_fsid_t fsid = {};
+	u32 match_mask = 0;
+
+	BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
+	BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
+	BUILD_BUG_ON(FAN_ATTRIB != FS_ATTRIB);
+	BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
+	BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
+	BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
+	BUILD_BUG_ON(FAN_MOVED_TO != FS_MOVED_TO);
+	BUILD_BUG_ON(FAN_MOVED_FROM != FS_MOVED_FROM);
+	BUILD_BUG_ON(FAN_CREATE != FS_CREATE);
+	BUILD_BUG_ON(FAN_DELETE != FS_DELETE);
+	BUILD_BUG_ON(FAN_DELETE_SELF != FS_DELETE_SELF);
+	BUILD_BUG_ON(FAN_MOVE_SELF != FS_MOVE_SELF);
+	BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
+	BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
+	BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
+	BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
+	BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
+	BUILD_BUG_ON(FAN_OPEN_EXEC != FS_OPEN_EXEC);
+	BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
+	BUILD_BUG_ON(FAN_FS_ERROR != FS_ERROR);
+	BUILD_BUG_ON(FAN_RENAME != FS_RENAME);
+
+	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 21);
+
+	mask = fanotify_group_event_mask(group, iter_info, &match_mask,
+					 mask, data, data_type, dir);
+	if (!mask)
+		return 0;
+
+	pr_debug("%s: group=%p mask=%x report_mask=%x\n", __func__,
+		 group, mask, match_mask);
+
+	if (fanotify_is_perm_event(mask)) {
+		/*
+		 * fsnotify_prepare_user_wait() fails if we race with mark
+		 * deletion.  Just let the operation pass in that case.
+		 */
+		if (!fsnotify_prepare_user_wait(iter_info))
+			return 0;
+	}
+
+	if (FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS)) {
+		fsid = fanotify_get_fsid(iter_info);
+		/* Racing with mark destruction or creation? */
+		if (!fsid.val[0] && !fsid.val[1])
+			return 0;
+	}
+
+	event = fanotify_alloc_event(group, mask, data, data_type, dir,
+				     file_name, &fsid, match_mask);
+	ret = -ENOMEM;
+	if (unlikely(!event)) {
+		/*
+		 * We don't queue overflow events for permission events as
+		 * there the access is denied and so no event is in fact lost.
+		 */
+		if (!fanotify_is_perm_event(mask))
+			fsnotify_queue_overflow(group);
+		goto finish;
+	}
+
+	fsn_event = &event->fse;
+	ret = fsnotify_insert_event(group, fsn_event, fanotify_merge,
+				    fanotify_insert_event);
+	if (ret) {
+		/* Permission events shouldn't be merged */
+		BUG_ON(ret == 1 && mask & FANOTIFY_PERM_EVENTS);
+		/* Our event wasn't used in the end. Free it. */
+		fsnotify_destroy_event(group, fsn_event);
+
+		ret = 0;
+	} else if (fanotify_is_perm_event(mask)) {
+		ret = fanotify_get_response(group, FANOTIFY_PERM(event),
+					    iter_info);
+	}
+finish:
+	if (fanotify_is_perm_event(mask))
+		fsnotify_finish_user_wait(iter_info);
+
+	return ret;
+}
+
+static void fanotify_free_group_priv(struct fsnotify_group *group)
+{
+	kfree(group->fanotify_data.merge_hash);
+	if (group->fanotify_data.ucounts)
+		dec_ucount(group->fanotify_data.ucounts,
+			   UCOUNT_FANOTIFY_GROUPS);
+
+	if (mempool_initialized(&group->fanotify_data.error_events_pool))
+		mempool_exit(&group->fanotify_data.error_events_pool);
+}
+
+static void fanotify_free_path_event(struct fanotify_event *event)
+{
+	path_put(fanotify_event_path(event));
+	kmem_cache_free(fanotify_path_event_cachep, FANOTIFY_PE(event));
+}
+
+static void fanotify_free_perm_event(struct fanotify_event *event)
+{
+	path_put(fanotify_event_path(event));
+	kmem_cache_free(fanotify_perm_event_cachep, FANOTIFY_PERM(event));
+}
+
+static void fanotify_free_fid_event(struct fanotify_event *event)
+{
+	struct fanotify_fid_event *ffe = FANOTIFY_FE(event);
+
+	if (fanotify_fh_has_ext_buf(&ffe->object_fh))
+		kfree(fanotify_fh_ext_buf(&ffe->object_fh));
+	kmem_cache_free(fanotify_fid_event_cachep, ffe);
+}
+
+static void fanotify_free_name_event(struct fanotify_event *event)
+{
+	kfree(FANOTIFY_NE(event));
+}
+
+static void fanotify_free_error_event(struct fsnotify_group *group,
+				      struct fanotify_event *event)
+{
+	struct fanotify_error_event *fee = FANOTIFY_EE(event);
+
+	mempool_free(fee, &group->fanotify_data.error_events_pool);
+}
+
+static void fanotify_free_event(struct fsnotify_group *group,
+				struct fsnotify_event *fsn_event)
+{
+	struct fanotify_event *event;
+
+	event = FANOTIFY_E(fsn_event);
+	put_pid(event->pid);
+	switch (event->type) {
+	case FANOTIFY_EVENT_TYPE_PATH:
+		fanotify_free_path_event(event);
+		break;
+	case FANOTIFY_EVENT_TYPE_PATH_PERM:
+		fanotify_free_perm_event(event);
+		break;
+	case FANOTIFY_EVENT_TYPE_FID:
+		fanotify_free_fid_event(event);
+		break;
+	case FANOTIFY_EVENT_TYPE_FID_NAME:
+		fanotify_free_name_event(event);
+		break;
+	case FANOTIFY_EVENT_TYPE_OVERFLOW:
+		kfree(event);
+		break;
+	case FANOTIFY_EVENT_TYPE_FS_ERROR:
+		fanotify_free_error_event(group, event);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+}
+
+static void fanotify_freeing_mark(struct fsnotify_mark *mark,
+				  struct fsnotify_group *group)
+{
+	if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS))
+		dec_ucount(group->fanotify_data.ucounts, UCOUNT_FANOTIFY_MARKS);
+}
+
+static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
+{
+	kmem_cache_free(fanotify_mark_cache, fsn_mark);
+}
+
+const struct fsnotify_ops fanotify_fsnotify_ops = {
+	.handle_event = fanotify_handle_event,
+	.free_group_priv = fanotify_free_group_priv,
+	.free_event = fanotify_free_event,
+	.freeing_mark = fanotify_freeing_mark,
+	.free_mark = fanotify_free_mark,
+};
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
new file mode 100644
index 0000000000..e8a3c28c5d
--- /dev/null
+++ b/fs/notify/fanotify/fanotify.h
@@ -0,0 +1,504 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/fsnotify_backend.h>
+#include <linux/path.h>
+#include <linux/slab.h>
+#include <linux/exportfs.h>
+#include <linux/hashtable.h>
+
+extern struct kmem_cache *fanotify_mark_cache;
+extern struct kmem_cache *fanotify_fid_event_cachep;
+extern struct kmem_cache *fanotify_path_event_cachep;
+extern struct kmem_cache *fanotify_perm_event_cachep;
+
+/* Possible states of the permission event */
+enum {
+	FAN_EVENT_INIT,
+	FAN_EVENT_REPORTED,
+	FAN_EVENT_ANSWERED,
+	FAN_EVENT_CANCELED,
+};
+
+/*
+ * 3 dwords are sufficient for most local fs (64bit ino, 32bit generation).
+ * fh buf should be dword aligned. On 64bit arch, the ext_buf pointer is
+ * stored in either the first or last 2 dwords.
+ */
+#define FANOTIFY_INLINE_FH_LEN	(3 << 2)
+#define FANOTIFY_FH_HDR_LEN	offsetof(struct fanotify_fh, buf)
+
+/* Fixed size struct for file handle */
+struct fanotify_fh {
+	u8 type;
+	u8 len;
+#define FANOTIFY_FH_FLAG_EXT_BUF 1
+	u8 flags;
+	u8 pad;
+	unsigned char buf[];
+} __aligned(4);
+
+/* Variable size struct for dir file handle + child file handle + name */
+struct fanotify_info {
+	/* size of dir_fh/file_fh including fanotify_fh hdr size */
+	u8 dir_fh_totlen;
+	u8 dir2_fh_totlen;
+	u8 file_fh_totlen;
+	u8 name_len;
+	u8 name2_len;
+	u8 pad[3];
+	unsigned char buf[];
+	/*
+	 * (struct fanotify_fh) dir_fh starts at buf[0]
+	 * (optional) dir2_fh starts at buf[dir_fh_totlen]
+	 * (optional) file_fh starts at buf[dir_fh_totlen + dir2_fh_totlen]
+	 * name starts at buf[dir_fh_totlen + dir2_fh_totlen + file_fh_totlen]
+	 * ...
+	 */
+#define FANOTIFY_DIR_FH_SIZE(info)	((info)->dir_fh_totlen)
+#define FANOTIFY_DIR2_FH_SIZE(info)	((info)->dir2_fh_totlen)
+#define FANOTIFY_FILE_FH_SIZE(info)	((info)->file_fh_totlen)
+#define FANOTIFY_NAME_SIZE(info)	((info)->name_len + 1)
+#define FANOTIFY_NAME2_SIZE(info)	((info)->name2_len + 1)
+
+#define FANOTIFY_DIR_FH_OFFSET(info)	0
+#define FANOTIFY_DIR2_FH_OFFSET(info) \
+	(FANOTIFY_DIR_FH_OFFSET(info) + FANOTIFY_DIR_FH_SIZE(info))
+#define FANOTIFY_FILE_FH_OFFSET(info) \
+	(FANOTIFY_DIR2_FH_OFFSET(info) + FANOTIFY_DIR2_FH_SIZE(info))
+#define FANOTIFY_NAME_OFFSET(info) \
+	(FANOTIFY_FILE_FH_OFFSET(info) + FANOTIFY_FILE_FH_SIZE(info))
+#define FANOTIFY_NAME2_OFFSET(info) \
+	(FANOTIFY_NAME_OFFSET(info) + FANOTIFY_NAME_SIZE(info))
+
+#define FANOTIFY_DIR_FH_BUF(info) \
+	((info)->buf + FANOTIFY_DIR_FH_OFFSET(info))
+#define FANOTIFY_DIR2_FH_BUF(info) \
+	((info)->buf + FANOTIFY_DIR2_FH_OFFSET(info))
+#define FANOTIFY_FILE_FH_BUF(info) \
+	((info)->buf + FANOTIFY_FILE_FH_OFFSET(info))
+#define FANOTIFY_NAME_BUF(info) \
+	((info)->buf + FANOTIFY_NAME_OFFSET(info))
+#define FANOTIFY_NAME2_BUF(info) \
+	((info)->buf + FANOTIFY_NAME2_OFFSET(info))
+} __aligned(4);
+
+static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh)
+{
+	return (fh->flags & FANOTIFY_FH_FLAG_EXT_BUF);
+}
+
+static inline char **fanotify_fh_ext_buf_ptr(struct fanotify_fh *fh)
+{
+	BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN % 4);
+	BUILD_BUG_ON(__alignof__(char *) - 4 + sizeof(char *) >
+		     FANOTIFY_INLINE_FH_LEN);
+	return (char **)ALIGN((unsigned long)(fh->buf), __alignof__(char *));
+}
+
+static inline void *fanotify_fh_ext_buf(struct fanotify_fh *fh)
+{
+	return *fanotify_fh_ext_buf_ptr(fh);
+}
+
+static inline void *fanotify_fh_buf(struct fanotify_fh *fh)
+{
+	return fanotify_fh_has_ext_buf(fh) ? fanotify_fh_ext_buf(fh) : fh->buf;
+}
+
+static inline int fanotify_info_dir_fh_len(struct fanotify_info *info)
+{
+	if (!info->dir_fh_totlen ||
+	    WARN_ON_ONCE(info->dir_fh_totlen < FANOTIFY_FH_HDR_LEN))
+		return 0;
+
+	return info->dir_fh_totlen - FANOTIFY_FH_HDR_LEN;
+}
+
+static inline struct fanotify_fh *fanotify_info_dir_fh(struct fanotify_info *info)
+{
+	BUILD_BUG_ON(offsetof(struct fanotify_info, buf) % 4);
+
+	return (struct fanotify_fh *)FANOTIFY_DIR_FH_BUF(info);
+}
+
+static inline int fanotify_info_dir2_fh_len(struct fanotify_info *info)
+{
+	if (!info->dir2_fh_totlen ||
+	    WARN_ON_ONCE(info->dir2_fh_totlen < FANOTIFY_FH_HDR_LEN))
+		return 0;
+
+	return info->dir2_fh_totlen - FANOTIFY_FH_HDR_LEN;
+}
+
+static inline struct fanotify_fh *fanotify_info_dir2_fh(struct fanotify_info *info)
+{
+	return (struct fanotify_fh *)FANOTIFY_DIR2_FH_BUF(info);
+}
+
+static inline int fanotify_info_file_fh_len(struct fanotify_info *info)
+{
+	if (!info->file_fh_totlen ||
+	    WARN_ON_ONCE(info->file_fh_totlen < FANOTIFY_FH_HDR_LEN))
+		return 0;
+
+	return info->file_fh_totlen - FANOTIFY_FH_HDR_LEN;
+}
+
+static inline struct fanotify_fh *fanotify_info_file_fh(struct fanotify_info *info)
+{
+	return (struct fanotify_fh *)FANOTIFY_FILE_FH_BUF(info);
+}
+
+static inline char *fanotify_info_name(struct fanotify_info *info)
+{
+	if (!info->name_len)
+		return NULL;
+
+	return FANOTIFY_NAME_BUF(info);
+}
+
+static inline char *fanotify_info_name2(struct fanotify_info *info)
+{
+	if (!info->name2_len)
+		return NULL;
+
+	return FANOTIFY_NAME2_BUF(info);
+}
+
+static inline void fanotify_info_init(struct fanotify_info *info)
+{
+	BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN + MAX_HANDLE_SZ > U8_MAX);
+	BUILD_BUG_ON(NAME_MAX > U8_MAX);
+
+	info->dir_fh_totlen = 0;
+	info->dir2_fh_totlen = 0;
+	info->file_fh_totlen = 0;
+	info->name_len = 0;
+	info->name2_len = 0;
+}
+
+/* These set/copy helpers MUST be called by order */
+static inline void fanotify_info_set_dir_fh(struct fanotify_info *info,
+					    unsigned int totlen)
+{
+	if (WARN_ON_ONCE(info->dir2_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->file_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->name_len > 0) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
+		return;
+
+	info->dir_fh_totlen = totlen;
+}
+
+static inline void fanotify_info_set_dir2_fh(struct fanotify_info *info,
+					     unsigned int totlen)
+{
+	if (WARN_ON_ONCE(info->file_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->name_len > 0) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
+		return;
+
+	info->dir2_fh_totlen = totlen;
+}
+
+static inline void fanotify_info_set_file_fh(struct fanotify_info *info,
+					     unsigned int totlen)
+{
+	if (WARN_ON_ONCE(info->name_len > 0) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
+		return;
+
+	info->file_fh_totlen = totlen;
+}
+
+static inline void fanotify_info_copy_name(struct fanotify_info *info,
+					   const struct qstr *name)
+{
+	if (WARN_ON_ONCE(name->len > NAME_MAX) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
+		return;
+
+	info->name_len = name->len;
+	strcpy(fanotify_info_name(info), name->name);
+}
+
+static inline void fanotify_info_copy_name2(struct fanotify_info *info,
+					    const struct qstr *name)
+{
+	if (WARN_ON_ONCE(name->len > NAME_MAX))
+		return;
+
+	info->name2_len = name->len;
+	strcpy(fanotify_info_name2(info), name->name);
+}
+
+/*
+ * Common structure for fanotify events. Concrete structs are allocated in
+ * fanotify_handle_event() and freed when the information is retrieved by
+ * userspace. The type of event determines how it was allocated, how it will
+ * be freed and which concrete struct it may be cast to.
+ */
+enum fanotify_event_type {
+	FANOTIFY_EVENT_TYPE_FID, /* fixed length */
+	FANOTIFY_EVENT_TYPE_FID_NAME, /* variable length */
+	FANOTIFY_EVENT_TYPE_PATH,
+	FANOTIFY_EVENT_TYPE_PATH_PERM,
+	FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */
+	FANOTIFY_EVENT_TYPE_FS_ERROR, /* struct fanotify_error_event */
+	__FANOTIFY_EVENT_TYPE_NUM
+};
+
+#define FANOTIFY_EVENT_TYPE_BITS \
+	(ilog2(__FANOTIFY_EVENT_TYPE_NUM - 1) + 1)
+#define FANOTIFY_EVENT_HASH_BITS \
+	(32 - FANOTIFY_EVENT_TYPE_BITS)
+
+struct fanotify_event {
+	struct fsnotify_event fse;
+	struct hlist_node merge_list;	/* List for hashed merge */
+	u32 mask;
+	struct {
+		unsigned int type : FANOTIFY_EVENT_TYPE_BITS;
+		unsigned int hash : FANOTIFY_EVENT_HASH_BITS;
+	};
+	struct pid *pid;
+};
+
+static inline void fanotify_init_event(struct fanotify_event *event,
+				       unsigned int hash, u32 mask)
+{
+	fsnotify_init_event(&event->fse);
+	INIT_HLIST_NODE(&event->merge_list);
+	event->hash = hash;
+	event->mask = mask;
+	event->pid = NULL;
+}
+
+#define FANOTIFY_INLINE_FH(name, size)					\
+struct {								\
+	struct fanotify_fh (name);					\
+	/* Space for object_fh.buf[] - access with fanotify_fh_buf() */	\
+	unsigned char _inline_fh_buf[(size)];				\
+}
+
+struct fanotify_fid_event {
+	struct fanotify_event fae;
+	__kernel_fsid_t fsid;
+
+	FANOTIFY_INLINE_FH(object_fh, FANOTIFY_INLINE_FH_LEN);
+};
+
+static inline struct fanotify_fid_event *
+FANOTIFY_FE(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_fid_event, fae);
+}
+
+struct fanotify_name_event {
+	struct fanotify_event fae;
+	__kernel_fsid_t fsid;
+	struct fanotify_info info;
+};
+
+static inline struct fanotify_name_event *
+FANOTIFY_NE(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_name_event, fae);
+}
+
+struct fanotify_error_event {
+	struct fanotify_event fae;
+	s32 error; /* Error reported by the Filesystem. */
+	u32 err_count; /* Suppressed errors count */
+
+	__kernel_fsid_t fsid; /* FSID this error refers to. */
+
+	FANOTIFY_INLINE_FH(object_fh, MAX_HANDLE_SZ);
+};
+
+static inline struct fanotify_error_event *
+FANOTIFY_EE(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_error_event, fae);
+}
+
+static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event)
+{
+	if (event->type == FANOTIFY_EVENT_TYPE_FID)
+		return &FANOTIFY_FE(event)->fsid;
+	else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
+		return &FANOTIFY_NE(event)->fsid;
+	else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
+		return &FANOTIFY_EE(event)->fsid;
+	else
+		return NULL;
+}
+
+static inline struct fanotify_fh *fanotify_event_object_fh(
+						struct fanotify_event *event)
+{
+	if (event->type == FANOTIFY_EVENT_TYPE_FID)
+		return &FANOTIFY_FE(event)->object_fh;
+	else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
+		return fanotify_info_file_fh(&FANOTIFY_NE(event)->info);
+	else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
+		return &FANOTIFY_EE(event)->object_fh;
+	else
+		return NULL;
+}
+
+static inline struct fanotify_info *fanotify_event_info(
+						struct fanotify_event *event)
+{
+	if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
+		return &FANOTIFY_NE(event)->info;
+	else
+		return NULL;
+}
+
+static inline int fanotify_event_object_fh_len(struct fanotify_event *event)
+{
+	struct fanotify_info *info = fanotify_event_info(event);
+	struct fanotify_fh *fh = fanotify_event_object_fh(event);
+
+	if (info)
+		return info->file_fh_totlen ? fh->len : 0;
+	else
+		return fh ? fh->len : 0;
+}
+
+static inline int fanotify_event_dir_fh_len(struct fanotify_event *event)
+{
+	struct fanotify_info *info = fanotify_event_info(event);
+
+	return info ? fanotify_info_dir_fh_len(info) : 0;
+}
+
+static inline int fanotify_event_dir2_fh_len(struct fanotify_event *event)
+{
+	struct fanotify_info *info = fanotify_event_info(event);
+
+	return info ? fanotify_info_dir2_fh_len(info) : 0;
+}
+
+static inline bool fanotify_event_has_object_fh(struct fanotify_event *event)
+{
+	/* For error events, even zeroed fh are reported. */
+	if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
+		return true;
+	return fanotify_event_object_fh_len(event) > 0;
+}
+
+static inline bool fanotify_event_has_dir_fh(struct fanotify_event *event)
+{
+	return fanotify_event_dir_fh_len(event) > 0;
+}
+
+static inline bool fanotify_event_has_dir2_fh(struct fanotify_event *event)
+{
+	return fanotify_event_dir2_fh_len(event) > 0;
+}
+
+static inline bool fanotify_event_has_any_dir_fh(struct fanotify_event *event)
+{
+	return fanotify_event_has_dir_fh(event) ||
+		fanotify_event_has_dir2_fh(event);
+}
+
+struct fanotify_path_event {
+	struct fanotify_event fae;
+	struct path path;
+};
+
+static inline struct fanotify_path_event *
+FANOTIFY_PE(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_path_event, fae);
+}
+
+/*
+ * Structure for permission fanotify events. It gets allocated and freed in
+ * fanotify_handle_event() since we wait there for user response. When the
+ * information is retrieved by userspace the structure is moved from
+ * group->notification_list to group->fanotify_data.access_list to wait for
+ * user response.
+ */
+struct fanotify_perm_event {
+	struct fanotify_event fae;
+	struct path path;
+	u32 response;			/* userspace answer to the event */
+	unsigned short state;		/* state of the event */
+	int fd;		/* fd we passed to userspace for this event */
+	union {
+		struct fanotify_response_info_header hdr;
+		struct fanotify_response_info_audit_rule audit_rule;
+	};
+};
+
+static inline struct fanotify_perm_event *
+FANOTIFY_PERM(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_perm_event, fae);
+}
+
+static inline bool fanotify_is_perm_event(u32 mask)
+{
+	return IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS) &&
+		mask & FANOTIFY_PERM_EVENTS;
+}
+
+static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse)
+{
+	return container_of(fse, struct fanotify_event, fse);
+}
+
+static inline bool fanotify_is_error_event(u32 mask)
+{
+	return mask & FAN_FS_ERROR;
+}
+
+static inline const struct path *fanotify_event_path(struct fanotify_event *event)
+{
+	if (event->type == FANOTIFY_EVENT_TYPE_PATH)
+		return &FANOTIFY_PE(event)->path;
+	else if (event->type == FANOTIFY_EVENT_TYPE_PATH_PERM)
+		return &FANOTIFY_PERM(event)->path;
+	else
+		return NULL;
+}
+
+/*
+ * Use 128 size hash table to speed up events merge.
+ */
+#define FANOTIFY_HTABLE_BITS	(7)
+#define FANOTIFY_HTABLE_SIZE	(1 << FANOTIFY_HTABLE_BITS)
+#define FANOTIFY_HTABLE_MASK	(FANOTIFY_HTABLE_SIZE - 1)
+
+/*
+ * Permission events and overflow event do not get merged - don't hash them.
+ */
+static inline bool fanotify_is_hashed_event(u32 mask)
+{
+	return !(fanotify_is_perm_event(mask) ||
+		 fsnotify_is_overflow_event(mask));
+}
+
+static inline unsigned int fanotify_event_hash_bucket(
+						struct fsnotify_group *group,
+						struct fanotify_event *event)
+{
+	return event->hash & FANOTIFY_HTABLE_MASK;
+}
+
+static inline unsigned int fanotify_mark_user_flags(struct fsnotify_mark *mark)
+{
+	unsigned int mflags = 0;
+
+	if (mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
+		mflags |= FAN_MARK_IGNORED_SURV_MODIFY;
+	if (mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)
+		mflags |= FAN_MARK_EVICTABLE;
+	if (mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
+		mflags |= FAN_MARK_IGNORE;
+
+	return mflags;
+}
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
new file mode 100644
index 0000000000..62fe0b679e
--- /dev/null
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -0,0 +1,1957 @@
+// 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;
+}
+
+static int process_access_response_info(const char __user *info,
+					size_t info_len,
+				struct fanotify_response_info_audit_rule *friar)
+{
+	if (info_len != sizeof(*friar))
+		return -EINVAL;
+
+	if (copy_from_user(friar, info, sizeof(*friar)))
+		return -EFAULT;
+
+	if (friar->hdr.type != FAN_RESPONSE_INFO_AUDIT_RULE)
+		return -EINVAL;
+	if (friar->hdr.pad != 0)
+		return -EINVAL;
+	if (friar->hdr.len != sizeof(*friar))
+		return -EINVAL;
+
+	return info_len;
+}
+
+/*
+ * Finish processing of permission event by setting it to ANSWERED state and
+ * drop group->notification_lock.
+ */
+static void finish_permission_event(struct fsnotify_group *group,
+				    struct fanotify_perm_event *event, u32 response,
+				    struct fanotify_response_info_audit_rule *friar)
+				    __releases(&group->notification_lock)
+{
+	bool destroy = false;
+
+	assert_spin_locked(&group->notification_lock);
+	event->response = response & ~FAN_INFO;
+	if (response & FAN_INFO)
+		memcpy(&event->audit_rule, friar, sizeof(*friar));
+
+	if (event->state == FAN_EVENT_CANCELED)
+		destroy = true;
+	else
+		event->state = FAN_EVENT_ANSWERED;
+	spin_unlock(&group->notification_lock);
+	if (destroy)
+		fsnotify_destroy_event(group, &event->fae.fse);
+}
+
+static int process_access_response(struct fsnotify_group *group,
+				   struct fanotify_response *response_struct,
+				   const char __user *info,
+				   size_t info_len)
+{
+	struct fanotify_perm_event *event;
+	int fd = response_struct->fd;
+	u32 response = response_struct->response;
+	int ret = info_len;
+	struct fanotify_response_info_audit_rule friar;
+
+	pr_debug("%s: group=%p fd=%d response=%u buf=%p size=%zu\n", __func__,
+		 group, fd, response, info, info_len);
+	/*
+	 * make sure the response is valid, if invalid we do nothing and either
+	 * userspace can send a valid response or we will clean it up after the
+	 * timeout
+	 */
+	if (response & ~FANOTIFY_RESPONSE_VALID_MASK)
+		return -EINVAL;
+
+	switch (response & FANOTIFY_RESPONSE_ACCESS) {
+	case FAN_ALLOW:
+	case FAN_DENY:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT))
+		return -EINVAL;
+
+	if (response & FAN_INFO) {
+		ret = process_access_response_info(info, info_len, &friar);
+		if (ret < 0)
+			return ret;
+		if (fd == FAN_NOFD)
+			return ret;
+	} else {
+		ret = 0;
+	}
+
+	if (fd < 0)
+		return -EINVAL;
+
+	spin_lock(&group->notification_lock);
+	list_for_each_entry(event, &group->fanotify_data.access_list,
+			    fae.fse.list) {
+		if (event->fd != fd)
+			continue;
+
+		list_del_init(&event->fae.fse.list);
+		finish_permission_event(group, event, response, &friar);
+		wake_up(&group->fanotify_data.access_waitq);
+		return ret;
+	}
+	spin_unlock(&group->notification_lock);
+
+	return -ENOENT;
+}
+
+static size_t copy_error_info_to_user(struct fanotify_event *event,
+				      char __user *buf, int count)
+{
+	struct fanotify_event_info_error info = { };
+	struct fanotify_error_event *fee = FANOTIFY_EE(event);
+
+	info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR;
+	info.hdr.len = FANOTIFY_ERROR_INFO_LEN;
+
+	if (WARN_ON(count < info.hdr.len))
+		return -EFAULT;
+
+	info.error = fee->error;
+	info.error_count = fee->err_count;
+
+	if (copy_to_user(buf, &info, sizeof(info)))
+		return -EFAULT;
+
+	return info.hdr.len;
+}
+
+static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
+				 int info_type, const char *name,
+				 size_t name_len,
+				 char __user *buf, size_t count)
+{
+	struct fanotify_event_info_fid info = { };
+	struct file_handle handle = { };
+	unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf;
+	size_t fh_len = fh ? fh->len : 0;
+	size_t info_len = fanotify_fid_info_len(fh_len, name_len);
+	size_t len = info_len;
+
+	pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n",
+		 __func__, fh_len, name_len, info_len, count);
+
+	if (WARN_ON_ONCE(len < sizeof(info) || len > count))
+		return -EFAULT;
+
+	/*
+	 * Copy event info fid header followed by variable sized file handle
+	 * and optionally followed by variable sized filename.
+	 */
+	switch (info_type) {
+	case FAN_EVENT_INFO_TYPE_FID:
+	case FAN_EVENT_INFO_TYPE_DFID:
+		if (WARN_ON_ONCE(name_len))
+			return -EFAULT;
+		break;
+	case FAN_EVENT_INFO_TYPE_DFID_NAME:
+	case FAN_EVENT_INFO_TYPE_OLD_DFID_NAME:
+	case FAN_EVENT_INFO_TYPE_NEW_DFID_NAME:
+		if (WARN_ON_ONCE(!name || !name_len))
+			return -EFAULT;
+		break;
+	default:
+		return -EFAULT;
+	}
+
+	info.hdr.info_type = info_type;
+	info.hdr.len = len;
+	info.fsid = *fsid;
+	if (copy_to_user(buf, &info, sizeof(info)))
+		return -EFAULT;
+
+	buf += sizeof(info);
+	len -= sizeof(info);
+	if (WARN_ON_ONCE(len < sizeof(handle)))
+		return -EFAULT;
+
+	handle.handle_type = fh->type;
+	handle.handle_bytes = fh_len;
+
+	/* Mangle handle_type for bad file_handle */
+	if (!fh_len)
+		handle.handle_type = FILEID_INVALID;
+
+	if (copy_to_user(buf, &handle, sizeof(handle)))
+		return -EFAULT;
+
+	buf += sizeof(handle);
+	len -= sizeof(handle);
+	if (WARN_ON_ONCE(len < fh_len))
+		return -EFAULT;
+
+	/*
+	 * For an inline fh and inline file name, copy through stack to exclude
+	 * the copy from usercopy hardening protections.
+	 */
+	fh_buf = fanotify_fh_buf(fh);
+	if (fh_len <= FANOTIFY_INLINE_FH_LEN) {
+		memcpy(bounce, fh_buf, fh_len);
+		fh_buf = bounce;
+	}
+	if (copy_to_user(buf, fh_buf, fh_len))
+		return -EFAULT;
+
+	buf += fh_len;
+	len -= fh_len;
+
+	if (name_len) {
+		/* Copy the filename with terminating null */
+		name_len++;
+		if (WARN_ON_ONCE(len < name_len))
+			return -EFAULT;
+
+		if (copy_to_user(buf, name, name_len))
+			return -EFAULT;
+
+		buf += name_len;
+		len -= name_len;
+	}
+
+	/* Pad with 0's */
+	WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN);
+	if (len > 0 && clear_user(buf, len))
+		return -EFAULT;
+
+	return info_len;
+}
+
+static int copy_pidfd_info_to_user(int pidfd,
+				   char __user *buf,
+				   size_t count)
+{
+	struct fanotify_event_info_pidfd info = { };
+	size_t info_len = FANOTIFY_PIDFD_INFO_HDR_LEN;
+
+	if (WARN_ON_ONCE(info_len > count))
+		return -EFAULT;
+
+	info.hdr.info_type = FAN_EVENT_INFO_TYPE_PIDFD;
+	info.hdr.len = info_len;
+	info.pidfd = pidfd;
+
+	if (copy_to_user(buf, &info, info_len))
+		return -EFAULT;
+
+	return info_len;
+}
+
+static int copy_info_records_to_user(struct fanotify_event *event,
+				     struct fanotify_info *info,
+				     unsigned int info_mode, int pidfd,
+				     char __user *buf, size_t count)
+{
+	int ret, total_bytes = 0, info_type = 0;
+	unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS;
+	unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD;
+
+	/*
+	 * Event info records order is as follows:
+	 * 1. dir fid + name
+	 * 2. (optional) new dir fid + new name
+	 * 3. (optional) child fid
+	 */
+	if (fanotify_event_has_dir_fh(event)) {
+		info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
+					     FAN_EVENT_INFO_TYPE_DFID;
+
+		/* FAN_RENAME uses special info types */
+		if (event->mask & FAN_RENAME)
+			info_type = FAN_EVENT_INFO_TYPE_OLD_DFID_NAME;
+
+		ret = copy_fid_info_to_user(fanotify_event_fsid(event),
+					    fanotify_info_dir_fh(info),
+					    info_type,
+					    fanotify_info_name(info),
+					    info->name_len, buf, count);
+		if (ret < 0)
+			return ret;
+
+		buf += ret;
+		count -= ret;
+		total_bytes += ret;
+	}
+
+	/* New dir fid+name may be reported in addition to old dir fid+name */
+	if (fanotify_event_has_dir2_fh(event)) {
+		info_type = FAN_EVENT_INFO_TYPE_NEW_DFID_NAME;
+		ret = copy_fid_info_to_user(fanotify_event_fsid(event),
+					    fanotify_info_dir2_fh(info),
+					    info_type,
+					    fanotify_info_name2(info),
+					    info->name2_len, buf, count);
+		if (ret < 0)
+			return ret;
+
+		buf += ret;
+		count -= ret;
+		total_bytes += ret;
+	}
+
+	if (fanotify_event_has_object_fh(event)) {
+		const char *dot = NULL;
+		int dot_len = 0;
+
+		if (fid_mode == FAN_REPORT_FID || info_type) {
+			/*
+			 * With only group flag FAN_REPORT_FID only type FID is
+			 * reported. Second info record type is always FID.
+			 */
+			info_type = FAN_EVENT_INFO_TYPE_FID;
+		} else if ((fid_mode & FAN_REPORT_NAME) &&
+			   (event->mask & FAN_ONDIR)) {
+			/*
+			 * With group flag FAN_REPORT_NAME, if name was not
+			 * recorded in an event on a directory, report the name
+			 * "." with info type DFID_NAME.
+			 */
+			info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
+			dot = ".";
+			dot_len = 1;
+		} else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
+			   (event->mask & FAN_ONDIR)) {
+			/*
+			 * With group flag FAN_REPORT_DIR_FID, a single info
+			 * record has type DFID for directory entry modification
+			 * event and for event on a directory.
+			 */
+			info_type = FAN_EVENT_INFO_TYPE_DFID;
+		} else {
+			/*
+			 * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
+			 * a single info record has type FID for event on a
+			 * non-directory, when there is no directory to report.
+			 * For example, on FAN_DELETE_SELF event.
+			 */
+			info_type = FAN_EVENT_INFO_TYPE_FID;
+		}
+
+		ret = copy_fid_info_to_user(fanotify_event_fsid(event),
+					    fanotify_event_object_fh(event),
+					    info_type, dot, dot_len,
+					    buf, count);
+		if (ret < 0)
+			return ret;
+
+		buf += ret;
+		count -= ret;
+		total_bytes += ret;
+	}
+
+	if (pidfd_mode) {
+		ret = copy_pidfd_info_to_user(pidfd, buf, count);
+		if (ret < 0)
+			return ret;
+
+		buf += ret;
+		count -= ret;
+		total_bytes += ret;
+	}
+
+	if (fanotify_is_error_event(event->mask)) {
+		ret = copy_error_info_to_user(event, buf, count);
+		if (ret < 0)
+			return ret;
+		buf += ret;
+		count -= ret;
+		total_bytes += ret;
+	}
+
+	return total_bytes;
+}
+
+static ssize_t copy_event_to_user(struct fsnotify_group *group,
+				  struct fanotify_event *event,
+				  char __user *buf, size_t count)
+{
+	struct fanotify_event_metadata metadata;
+	const struct path *path = fanotify_event_path(event);
+	struct fanotify_info *info = fanotify_event_info(event);
+	unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
+	unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD;
+	struct file *f = NULL, *pidfd_file = NULL;
+	int ret, pidfd = 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_prepare(event->pid, 0, &pidfd_file);
+			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);
+
+	if (pidfd_file)
+		fd_install(pidfd, pidfd_file);
+
+	return metadata.event_len;
+
+out_close_fd:
+	if (fd != FAN_NOFD) {
+		put_unused_fd(fd);
+		fput(f);
+	}
+
+	if (pidfd >= 0) {
+		put_unused_fd(pidfd);
+		fput(pidfd_file);
+	}
+
+	return ret;
+}
+
+/* intofiy userspace file descriptor functions */
+static __poll_t fanotify_poll(struct file *file, poll_table *wait)
+{
+	struct fsnotify_group *group = file->private_data;
+	__poll_t ret = 0;
+
+	poll_wait(file, &group->notification_waitq, wait);
+	spin_lock(&group->notification_lock);
+	if (!fsnotify_notify_queue_is_empty(group))
+		ret = EPOLLIN | EPOLLRDNORM;
+	spin_unlock(&group->notification_lock);
+
+	return ret;
+}
+
+static ssize_t fanotify_read(struct file *file, char __user *buf,
+			     size_t count, loff_t *pos)
+{
+	struct fsnotify_group *group;
+	struct fanotify_event *event;
+	char __user *start;
+	int ret;
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+
+	start = buf;
+	group = file->private_data;
+
+	pr_debug("%s: group=%p\n", __func__, group);
+
+	add_wait_queue(&group->notification_waitq, &wait);
+	while (1) {
+		/*
+		 * User can supply arbitrarily large buffer. Avoid softlockups
+		 * in case there are lots of available events.
+		 */
+		cond_resched();
+		event = get_one_event(group, count);
+		if (IS_ERR(event)) {
+			ret = PTR_ERR(event);
+			break;
+		}
+
+		if (!event) {
+			ret = -EAGAIN;
+			if (file->f_flags & O_NONBLOCK)
+				break;
+
+			ret = -ERESTARTSYS;
+			if (signal_pending(current))
+				break;
+
+			if (start != buf)
+				break;
+
+			wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+			continue;
+		}
+
+		ret = copy_event_to_user(group, event, buf, count);
+		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, NULL);
+				wake_up(&group->fanotify_data.access_waitq);
+			} else {
+				spin_lock(&group->notification_lock);
+				list_add_tail(&event->fse.list,
+					&group->fanotify_data.access_list);
+				spin_unlock(&group->notification_lock);
+			}
+		}
+		if (ret < 0)
+			break;
+		buf += ret;
+		count -= ret;
+	}
+	remove_wait_queue(&group->notification_waitq, &wait);
+
+	if (start != buf && ret != -EFAULT)
+		ret = buf - start;
+	return ret;
+}
+
+static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
+{
+	struct fanotify_response response;
+	struct fsnotify_group *group;
+	int ret;
+	const char __user *info_buf = buf + sizeof(struct fanotify_response);
+	size_t info_len;
+
+	if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
+		return -EINVAL;
+
+	group = file->private_data;
+
+	pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
+
+	if (count < sizeof(response))
+		return -EINVAL;
+
+	if (copy_from_user(&response, buf, sizeof(response)))
+		return -EFAULT;
+
+	info_len = count - sizeof(response);
+
+	ret = process_access_response(group, &response, info_buf, info_len);
+	if (ret < 0)
+		count = ret;
+	else
+		count = sizeof(response) + ret;
+
+	return count;
+}
+
+static int fanotify_release(struct inode *ignored, struct file *file)
+{
+	struct fsnotify_group *group = file->private_data;
+	struct fsnotify_event *fsn_event;
+
+	/*
+	 * Stop new events from arriving in the notification queue. since
+	 * userspace cannot use fanotify fd anymore, no event can enter or
+	 * leave access_list by now either.
+	 */
+	fsnotify_group_stop_queueing(group);
+
+	/*
+	 * Process all permission events on access_list and notification queue
+	 * and simulate reply from userspace.
+	 */
+	spin_lock(&group->notification_lock);
+	while (!list_empty(&group->fanotify_data.access_list)) {
+		struct fanotify_perm_event *event;
+
+		event = list_first_entry(&group->fanotify_data.access_list,
+				struct fanotify_perm_event, fae.fse.list);
+		list_del_init(&event->fae.fse.list);
+		finish_permission_event(group, event, FAN_ALLOW, NULL);
+		spin_lock(&group->notification_lock);
+	}
+
+	/*
+	 * Destroy all non-permission events. For permission events just
+	 * dequeue them and set the response. They will be freed once the
+	 * response is consumed and fanotify_get_response() returns.
+	 */
+	while ((fsn_event = fsnotify_remove_first_event(group))) {
+		struct fanotify_event *event = FANOTIFY_E(fsn_event);
+
+		if (!(event->mask & FANOTIFY_PERM_EVENTS)) {
+			spin_unlock(&group->notification_lock);
+			fsnotify_destroy_event(group, fsn_event);
+		} else {
+			finish_permission_event(group, FANOTIFY_PERM(event),
+						FAN_ALLOW, NULL);
+		}
+		spin_lock(&group->notification_lock);
+	}
+	spin_unlock(&group->notification_lock);
+
+	/* Response for all permission events it set, wakeup waiters */
+	wake_up(&group->fanotify_data.access_waitq);
+
+	/* matches the fanotify_init->fsnotify_alloc_group */
+	fsnotify_destroy_group(group);
+
+	return 0;
+}
+
+static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct fsnotify_group *group;
+	struct fsnotify_event *fsn_event;
+	void __user *p;
+	int ret = -ENOTTY;
+	size_t send_len = 0;
+
+	group = file->private_data;
+
+	p = (void __user *) arg;
+
+	switch (cmd) {
+	case FIONREAD:
+		spin_lock(&group->notification_lock);
+		list_for_each_entry(fsn_event, &group->notification_list, list)
+			send_len += FAN_EVENT_METADATA_LEN;
+		spin_unlock(&group->notification_lock);
+		ret = put_user(send_len, (int __user *) p);
+		break;
+	}
+
+	return ret;
+}
+
+static const struct file_operations fanotify_fops = {
+	.show_fdinfo	= fanotify_show_fdinfo,
+	.poll		= fanotify_poll,
+	.read		= fanotify_read,
+	.write		= fanotify_write,
+	.fasync		= NULL,
+	.release	= fanotify_release,
+	.unlocked_ioctl	= fanotify_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+	.llseek		= noop_llseek,
+};
+
+static int fanotify_find_path(int dfd, const char __user *filename,
+			      struct path *path, unsigned int flags, __u64 mask,
+			      unsigned int obj_type)
+{
+	int ret;
+
+	pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
+		 dfd, filename, flags);
+
+	if (filename == NULL) {
+		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, unsigned int flags)
+{
+	unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
+	const struct export_operations *nop = dentry->d_sb->s_export_op;
+
+	/*
+	 * We need to make sure that the filesystem supports encoding of
+	 * file handles so user can use name_to_handle_at() to compare fids
+	 * reported with events to the file handle of watched objects.
+	 */
+	if (!nop)
+		return -EOPNOTSUPP;
+
+	/*
+	 * For sb/mount mark, we also need to make sure that the filesystem
+	 * supports decoding file handles, so user has a way to map back the
+	 * reported fids to filesystem objects.
+	 */
+	if (mark_type != FAN_MARK_INODE && !nop->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, flags);
+		if (ret)
+			goto path_put_and_out;
+
+		fsid = &__fsid;
+	}
+
+	/* inode held in place by reference to path; group by fget on fd */
+	if (mark_type == FAN_MARK_INODE)
+		inode = path.dentry->d_inode;
+	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);