Patch "ext4: prevent creating duplicate encrypted filenames" has been added to the 4.19-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    ext4: prevent creating duplicate encrypted filenames

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ext4-prevent-creating-duplicate-encrypted-filenames.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Wed Dec 30 04:40:58 PM CET 2020
From: Eric Biggers <ebiggers at kernel.org>
Date: Mon, 28 Dec 2020 11:12:09 -0800
Subject: ext4: prevent creating duplicate encrypted filenames
To: stable at vger.kernel.org
Cc: linux-fscrypt at vger.kernel.org, linux-ext4 at vger.kernel.org, linux-f2fs-devel at lists.sourceforge.net, linux-mtd at lists.infradead.org
Message-ID: <20201228191211.138300-3-ebiggers at kernel.org>

From: Eric Biggers <ebiggers at google.com>

commit 75d18cd1868c2aee43553723872c35d7908f240f upstream.

As described in "fscrypt: add fscrypt_is_nokey_name()", it's possible to
create a duplicate filename in an encrypted directory by creating a file
concurrently with adding the directory's encryption key.

Fix this bug on ext4 by rejecting no-key dentries in ext4_add_entry().

Note that the duplicate check in ext4_find_dest_de() sometimes prevented
this bug.  However in many cases it didn't, since ext4_find_dest_de()
doesn't examine every dentry.

Fixes: 4461471107b7 ("ext4 crypto: enable filename encryption")
Cc: stable at vger.kernel.org
Link: https://lore.kernel.org/r/20201118075609.120337-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers at google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 fs/ext4/namei.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2106,6 +2106,9 @@ static int ext4_add_entry(handle_t *hand
 	if (!dentry->d_name.len)
 		return -EINVAL;
 
+	if (fscrypt_is_nokey_name(dentry))
+		return -ENOKEY;
+
 	retval = ext4_fname_setup_filename(dir, &dentry->d_name, 0, &fname);
 	if (retval)
 		return retval;


Patches currently in stable-queue which might be from ebiggers at kernel.org are

queue-4.19/fscrypt-add-fscrypt_is_nokey_name.patch
queue-4.19/ext4-prevent-creating-duplicate-encrypted-filenames.patch
queue-4.19/ubifs-prevent-creating-duplicate-encrypted-filenames.patch
queue-4.19/f2fs-prevent-creating-duplicate-encrypted-filenames.patch