Patch "ubifs: 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

    ubifs: 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:
     ubifs-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 11:12:11 -0800
Subject: ubifs: 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: <20201228191211.138300-5-ebiggers at kernel.org>

From: Eric Biggers <ebiggers at google.com>

commit 76786a0f083473de31678bdb259a3d4167cf756d 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 ubifs by rejecting no-key dentries in ubifs_create(),
ubifs_mkdir(), ubifs_mknod(), and ubifs_symlink().

Note that ubifs doesn't actually report the duplicate filenames from
readdir, but rather it seems to replace the original dentry with a new
one (which is still wrong, just a different effect from ext4).

On ubifs, this fixes xfstest generic/595 as well as the new xfstest I
wrote specifically for this bug.

Fixes: f4f61d2cc6d8 ("ubifs: Implement encrypted filenames")
Cc: stable at vger.kernel.org
Link: https://lore.kernel.org/r/20201118075609.120337-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers at google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 fs/ubifs/dir.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -290,6 +290,15 @@ done:
 	return d_splice_alias(inode, dentry);
 }
 
+static int ubifs_prepare_create(struct inode *dir, struct dentry *dentry,
+				struct fscrypt_name *nm)
+{
+	if (fscrypt_is_nokey_name(dentry))
+		return -ENOKEY;
+
+	return fscrypt_setup_filename(dir, &dentry->d_name, 0, nm);
+}
+
 static int ubifs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 			bool excl)
 {
@@ -313,7 +322,7 @@ static int ubifs_create(struct inode *di
 	if (err)
 		return err;
 
-	err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm);
+	err = ubifs_prepare_create(dir, dentry, &nm);
 	if (err)
 		goto out_budg;
 
@@ -977,7 +986,7 @@ static int ubifs_mkdir(struct inode *dir
 	if (err)
 		return err;
 
-	err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm);
+	err = ubifs_prepare_create(dir, dentry, &nm);
 	if (err)
 		goto out_budg;
 
@@ -1062,7 +1071,7 @@ static int ubifs_mknod(struct inode *dir
 		return err;
 	}
 
-	err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm);
+	err = ubifs_prepare_create(dir, dentry, &nm);
 	if (err) {
 		kfree(dev);
 		goto out_budg;
@@ -1146,7 +1155,7 @@ static int ubifs_symlink(struct inode *d
 	if (err)
 		return err;
 
-	err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm);
+	err = ubifs_prepare_create(dir, dentry, &nm);
 	if (err)
 		goto out_budg;
 


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