Patch "f2fs: 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

    f2fs: 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:
     f2fs-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 11:12:10 -0800
Subject: f2fs: 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: <20201228191211.138300-4-ebiggers at kernel.org>

From: Eric Biggers <ebiggers at google.com>

commit bfc2b7e8518999003a61f91c1deb5e88ed77b07d 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 f2fs by rejecting no-key dentries in f2fs_add_link().

Note that the weird check for the current task in f2fs_do_add_link()
seems to make this bug difficult to reproduce on f2fs.

Fixes: 9ea97163c6da ("f2fs crypto: add filename encryption for f2fs_add_link")
Cc: stable at vger.kernel.org
Link: https://lore.kernel.org/r/20201118075609.120337-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers at google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 fs/f2fs/f2fs.h |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2857,6 +2857,8 @@ bool f2fs_empty_dir(struct inode *dir);
 
 static inline int f2fs_add_link(struct dentry *dentry, struct inode *inode)
 {
+	if (fscrypt_is_nokey_name(dentry))
+		return -ENOKEY;
 	return f2fs_do_add_link(d_inode(dentry->d_parent), &dentry->d_name,
 				inode, inode->i_ino, inode->i_mode);
 }


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