Unverified Commit 2a42754b authored by Amir Goldstein's avatar Amir Goldstein Committed by Christian Brauner
Browse files

fsnotify: disable notification by default for all pseudo files 



Most pseudo files are not applicable for fsnotify events at all,
let alone to the new pre-content events.

Disable notifications to all files allocated with alloc_file_pseudo()
and enable legacy inotify events for the specific cases of pipe and
socket, which have known users of inotify events.

Pre-content events are also kept disabled for sockets and pipes.

Fixes: 20bf82a8 ("mm: don't allow huge faults for files with pre content watches")
Reported-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Closes: https://lore.kernel.org/linux-fsdevel/20250131121703.1e4d00a7.alex.williamson@redhat.com/


Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/linux-fsdevel/CAHk-=wi2pThSVY=zhO=ZKxViBj5QCRX-=AS2+rVknQgJnHXDFg@mail.gmail.com/


Tested-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20250203223205.861346-3-amir73il@gmail.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 95101401

fs/file_table.c

+11 −0
Original line number Diff line number Diff line
@@ -375,7 +375,13 @@ struct file *alloc_file_pseudo(struct inode *inode, struct vfsmount *mnt, 
	if (IS_ERR(file)) {

		ihold(inode);

		path_put(&path);

		return file;

	}

	/*

	 * Disable all fsnotify events for pseudo files by default.

	 * They may be enabled by caller with file_set_fsnotify_mode().

	 */

	file_set_fsnotify_mode(file, FMODE_NONOTIFY);

	return file;

}

EXPORT_SYMBOL(alloc_file_pseudo);
@@ -400,6 +406,11 @@ struct file *alloc_file_pseudo_noaccount(struct inode *inode, 
		return file;

	}

	file_init_path(file, &path, fops);

	/*

	 * Disable all fsnotify events for pseudo files by default.

	 * They may be enabled by caller with file_set_fsnotify_mode().

	 */

	file_set_fsnotify_mode(file, FMODE_NONOTIFY);

	return file;

}

EXPORT_SYMBOL_GPL(alloc_file_pseudo_noaccount);

fs/open.c

+2 −2
Original line number Diff line number Diff line
@@ -936,8 +936,8 @@ static int do_dentry_open(struct file *f, 


	/*

	 * Set FMODE_NONOTIFY_* bits according to existing permission watches.

	 * If FMODE_NONOTIFY was already set for an fanotify fd, this doesn't

	 * change anything.

	 * If FMODE_NONOTIFY mode was already set for an fanotify fd or for a

	 * pseudo file, this call will not change the mode.

	 */

	file_set_fsnotify_mode_from_watchers(f);

	error = fsnotify_open_perm(f);

fs/pipe.c

+6 −0
Original line number Diff line number Diff line
@@ -960,6 +960,12 @@ int create_pipe_files(struct file **res, int flags) 
	res[1] = f;

	stream_open(inode, res[0]);

	stream_open(inode, res[1]);

	/*

	 * Disable permission and pre-content events, but enable legacy

	 * inotify events for legacy users.

	 */

	file_set_fsnotify_mode(res[0], FMODE_NONOTIFY_PERM);

	file_set_fsnotify_mode(res[1], FMODE_NONOTIFY_PERM);

	return 0;

}

net/socket.c

+5 −0
Original line number Diff line number Diff line
@@ -479,6 +479,11 @@ struct file *sock_alloc_file(struct socket *sock, int flags, const char *dname) 
	sock->file = file;

	file->private_data = sock;

	stream_open(SOCK_INODE(sock), file);

	/*

	 * Disable permission and pre-content events, but enable legacy

	 * inotify events for legacy users.

	 */

	file_set_fsnotify_mode(file, FMODE_NONOTIFY_PERM);

	return file;

}

EXPORT_SYMBOL(sock_alloc_file);