Merge tag 'fsnotify_for_v6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull fsnotify updates from Jan Kara:
 "fanotify changes allowing use of fanotify directory events even for
  filesystems such as FUSE which don't report proper fsid"

* tag 'fsnotify_for_v6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fanotify: allow "weak" fsid when watching a single filesystem
  fanotify: store fsid in mark instead of in connector

Author: torvalds

fs/notify/fanotify/fanotify.c

@@ -29,12 +29,6 @@ static unsigned int fanotify_hash_path(const struct path *path)
 		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) ^
@@ -838,9 +832,8 @@ static struct fanotify_event *fanotify_alloc_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.
+ * Get cached fsid of the filesystem containing the object from any mark.
+ * All marks 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)
 {
@@ -849,18 +842,11 @@ static __kernel_fsid_t fanotify_get_fsid(struct fsnotify_iter_info *iter_info)
 	__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)
+		if (!(mark->flags & FSNOTIFY_MARK_FLAG_HAS_FSID))
 			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]))
+		fsid = FANOTIFY_MARK(mark)->fsid;
+		if (!(mark->flags & FSNOTIFY_MARK_FLAG_WEAK_FSID) &&
+		    WARN_ON_ONCE(!fsid.val[0] && !fsid.val[1]))
 			continue;
 		return fsid;
 	}
@@ -942,12 +928,8 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
 			return 0;
 	}
 
-	if (FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS)) {
+	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);
@@ -1068,7 +1050,7 @@ static void fanotify_freeing_mark(struct fsnotify_mark *mark,
 
 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
 {
-	kmem_cache_free(fanotify_mark_cache, fsn_mark);
+	kmem_cache_free(fanotify_mark_cache, FANOTIFY_MARK(fsn_mark));
 }
 
 const struct fsnotify_ops fanotify_fsnotify_ops = {

fs/notify/fanotify/fanotify.h

@@ -489,6 +489,22 @@ static inline unsigned int fanotify_event_hash_bucket(
 	return event->hash & FANOTIFY_HTABLE_MASK;
 }
 
+struct fanotify_mark {
+	struct fsnotify_mark fsn_mark;
+	__kernel_fsid_t fsid;
+};
+
+static inline struct fanotify_mark *FANOTIFY_MARK(struct fsnotify_mark *mark)
+{
+	return container_of(mark, struct fanotify_mark, fsn_mark);
+}
+
+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 inline unsigned int fanotify_mark_user_flags(struct fsnotify_mark *mark)
 {
 	unsigned int mflags = 0;

fs/notify/fanotify/fanotify_user.c

@@ -23,7 +23,7 @@
 
 #include <asm/ioctls.h>
 
-#include "../../mount.h"
+#include "../fsnotify.h"
 #include "../fdinfo.h"
 #include "fanotify.h"
 
@@ -1192,13 +1192,71 @@ static bool fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
 	return recalc;
 }
 
+struct fan_fsid {
+	struct super_block *sb;
+	__kernel_fsid_t id;
+	bool weak;
+};
+
+static int fanotify_set_mark_fsid(struct fsnotify_group *group,
+				  struct fsnotify_mark *mark,
+				  struct fan_fsid *fsid)
+{
+	struct fsnotify_mark_connector *conn;
+	struct fsnotify_mark *old;
+	struct super_block *old_sb = NULL;
+
+	FANOTIFY_MARK(mark)->fsid = fsid->id;
+	mark->flags |= FSNOTIFY_MARK_FLAG_HAS_FSID;
+	if (fsid->weak)
+		mark->flags |= FSNOTIFY_MARK_FLAG_WEAK_FSID;
+
+	/* First mark added will determine if group is single or multi fsid */
+	if (list_empty(&group->marks_list))
+		return 0;
+
+	/* Find sb of an existing mark */
+	list_for_each_entry(old, &group->marks_list, g_list) {
+		conn = READ_ONCE(old->connector);
+		if (!conn)
+			continue;
+		old_sb = fsnotify_connector_sb(conn);
+		if (old_sb)
+			break;
+	}
+
+	/* Only detached marks left? */
+	if (!old_sb)
+		return 0;
+
+	/* Do not allow mixing of marks with weak and strong fsid */
+	if ((mark->flags ^ old->flags) & FSNOTIFY_MARK_FLAG_WEAK_FSID)
+		return -EXDEV;
+
+	/* Allow mixing of marks with strong fsid from different fs */
+	if (!fsid->weak)
+		return 0;
+
+	/* Do not allow mixing marks with weak fsid from different fs */
+	if (old_sb != fsid->sb)
+		return -EXDEV;
+
+	/* Do not allow mixing marks from different btrfs sub-volumes */
+	if (!fanotify_fsid_equal(&FANOTIFY_MARK(old)->fsid,
+				 &FANOTIFY_MARK(mark)->fsid))
+		return -EXDEV;
+
+	return 0;
+}
+
 static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
 						   fsnotify_connp_t *connp,
 						   unsigned int obj_type,
 						   unsigned int fan_flags,
-						   __kernel_fsid_t *fsid)
+						   struct fan_fsid *fsid)
 {
 	struct ucounts *ucounts = group->fanotify_data.ucounts;
+	struct fanotify_mark *fan_mark;
 	struct fsnotify_mark *mark;
 	int ret;
 
@@ -1211,24 +1269,34 @@ static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
 	    !inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_FANOTIFY_MARKS))
 		return ERR_PTR(-ENOSPC);
 
-	mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
-	if (!mark) {
+	fan_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
+	if (!fan_mark) {
 		ret = -ENOMEM;
 		goto out_dec_ucounts;
 	}
 
+	mark = &fan_mark->fsn_mark;
 	fsnotify_init_mark(mark, group);
 	if (fan_flags & FAN_MARK_EVICTABLE)
 		mark->flags |= FSNOTIFY_MARK_FLAG_NO_IREF;
 
-	ret = fsnotify_add_mark_locked(mark, connp, obj_type, 0, fsid);
-	if (ret) {
-		fsnotify_put_mark(mark);
-		goto out_dec_ucounts;
+	/* Cache fsid of filesystem containing the marked object */
+	if (fsid) {
+		ret = fanotify_set_mark_fsid(group, mark, fsid);
+		if (ret)
+			goto out_put_mark;
+	} else {
+		fan_mark->fsid.val[0] = fan_mark->fsid.val[1] = 0;
 	}
 
+	ret = fsnotify_add_mark_locked(mark, connp, obj_type, 0);
+	if (ret)
+		goto out_put_mark;
+
 	return mark;
 
+out_put_mark:
+	fsnotify_put_mark(mark);
 out_dec_ucounts:
 	if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS))
 		dec_ucount(ucounts, UCOUNT_FANOTIFY_MARKS);
@@ -1279,7 +1347,7 @@ static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark,
 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 fan_fsid *fsid)
 {
 	struct fsnotify_mark *fsn_mark;
 	bool recalc;
@@ -1327,23 +1395,23 @@ static int fanotify_add_mark(struct fsnotify_group *group,
 
 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
 				      struct vfsmount *mnt, __u32 mask,
-				      unsigned int flags, __kernel_fsid_t *fsid)
+				      unsigned int flags, struct fan_fsid *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)
+				unsigned int flags, struct fan_fsid *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)
+				   unsigned int flags, struct fan_fsid *fsid)
 {
 	pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
 
@@ -1554,20 +1622,25 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 	return fd;
 }
 
-static int fanotify_test_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
+static int fanotify_test_fsid(struct dentry *dentry, unsigned int flags,
+			      struct fan_fsid *fsid)
 {
+	unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
 	__kernel_fsid_t root_fsid;
 	int err;
 
 	/*
 	 * Make sure dentry is not of a filesystem with zero fsid (e.g. fuse).
 	 */
-	err = vfs_get_fsid(dentry, fsid);
+	err = vfs_get_fsid(dentry, &fsid->id);
 	if (err)
 		return err;
 
-	if (!fsid->val[0] && !fsid->val[1])
-		return -ENODEV;
+	fsid->sb = dentry->d_sb;
+	if (!fsid->id.val[0] && !fsid->id.val[1]) {
+		err = -ENODEV;
+		goto weak;
+	}
 
 	/*
 	 * Make sure dentry is not of a filesystem subvolume (e.g. btrfs)
@@ -1577,11 +1650,18 @@ static int fanotify_test_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
 	if (err)
 		return err;
 
-	if (root_fsid.val[0] != fsid->val[0] ||
-	    root_fsid.val[1] != fsid->val[1])
-		return -EXDEV;
+	if (!fanotify_fsid_equal(&root_fsid, &fsid->id)) {
+		err = -EXDEV;
+		goto weak;
+	}
 
+	fsid->weak = false;
 	return 0;
+
+weak:
+	/* Allow weak fsid when marking inodes */
+	fsid->weak = true;
+	return (mark_type == FAN_MARK_INODE) ? 0 : err;
 }
 
 /* Check if filesystem can encode a unique fid */
@@ -1665,7 +1745,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	struct fsnotify_group *group;
 	struct fd f;
 	struct path path;
-	__kernel_fsid_t __fsid, *fsid = NULL;
+	struct fan_fsid __fsid, *fsid = NULL;
 	u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS;
 	unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
 	unsigned int mark_cmd = flags & FANOTIFY_MARK_CMD_BITS;
@@ -1817,7 +1897,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	}
 
 	if (fid_mode) {
-		ret = fanotify_test_fsid(path.dentry, &__fsid);
+		ret = fanotify_test_fsid(path.dentry, flags, &__fsid);
 		if (ret)
 			goto path_put_and_out;
 
@@ -1935,7 +2015,7 @@ static int __init fanotify_user_setup(void)
 	BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 12);
 	BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 11);
 
-	fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
+	fanotify_mark_cache = KMEM_CACHE(fanotify_mark,
 					 SLAB_PANIC|SLAB_ACCOUNT);
 	fanotify_fid_event_cachep = KMEM_CACHE(fanotify_fid_event,
 					       SLAB_PANIC);