Merge tag 'fsnotify_for_v6.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull fsnotify fixes from Jan Kara:
 "Two fsnotify fixes.

  The fix from Ahelenia makes sure we generate event when modifying
  inode flags, the fix from Amir disables sending of events from device
  inodes to their parent directory as it could concievably create a
  usable side channel attack in case of some devices and so far we
  aren't aware of anybody depending on the functionality"

* tag 'fsnotify_for_v6.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fs: send fsnotify_xattr()/IN_ATTRIB from vfs_fileattr_set()/chattr(1)
  fsnotify: do not generate ACCESS/MODIFY events on child for special files

Author: torvalds

fs/file_attr.c

@@ -2,6 +2,7 @@
 #include <linux/fs.h>
 #include <linux/security.h>
 #include <linux/fscrypt.h>
+#include <linux/fsnotify.h>
 #include <linux/fileattr.h>
 #include <linux/export.h>
 #include <linux/syscalls.h>
@@ -298,6 +299,7 @@ int vfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
 		err = inode->i_op->fileattr_set(idmap, dentry, fa);
 		if (err)
 			goto out;
+		fsnotify_xattr(dentry);
 	}
 
 out:

fs/notify/fsnotify.c

@@ -270,8 +270,15 @@ int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
 	/*
 	 * Include parent/name in notification either if some notification
 	 * groups require parent info or the parent is interested in this event.
+	 * The parent interest in ACCESS/MODIFY events does not apply to special
+	 * files, where read/write are not on the filesystem of the parent and
+	 * events can provide an undesirable side-channel for information
+	 * exfiltration.
 	 */
-	parent_interested = mask & p_mask & ALL_FSNOTIFY_EVENTS;
+	parent_interested = mask & p_mask & ALL_FSNOTIFY_EVENTS &&
+			    !(data_type == FSNOTIFY_EVENT_PATH &&
+			      d_is_special(dentry) &&
+			      (mask & (FS_ACCESS | FS_MODIFY)));
 	if (parent_needed || parent_interested) {
 		/* When notifying parent, child should be passed as data */
 		WARN_ON_ONCE(inode != fsnotify_data_inode(data, data_type));