Patch "fscrypto: require write access to mount to set encryption policy" has been added to the 4.7-stable tree

Patch "fscrypto: require write access to mount to set encryption policy" has been added to the 4.7-stable tree

[gregkh]

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

    fscrypto: require write access to mount to set encryption policy

to the 4.7-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:
     fscrypto-require-write-access-to-mount-to-set-encryption-policy.patch
and it can be found in the queue-4.7 subdirectory.

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


>From ba63f23d69a3a10e7e527a02702023da68ef8a6d Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 8 Sep 2016 14:20:38 -0700
Subject: fscrypto: require write access to mount to set encryption policy

From: Eric Biggers <ebiggers@google.com>

commit ba63f23d69a3a10e7e527a02702023da68ef8a6d upstream.

Since setting an encryption policy requires writing metadata to the
filesystem, it should be guarded by mnt_want_write/mnt_drop_write.
Otherwise, a user could cause a write to a frozen or readonly
filesystem.  This was handled correctly by f2fs but not by ext4.  Make
fscrypt_process_policy() handle it rather than relying on the filesystem
to get it right.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Cc: stable@vger.kernel.org # 4.1+; check fs/{ext4,f2fs}
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ext4/ioctl.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -782,7 +782,13 @@ resizefs_out:
 			goto encryption_policy_out;
 		}
 
+		err = mnt_want_write_file(filp);
+		if (err)
+			goto encryption_policy_out;
+
 		err = ext4_process_policy(&policy, inode);
+
+		mnt_drop_write_file(filp);
 encryption_policy_out:
 		return err;
 #else


Patches currently in stable-queue which might be from ebiggers@google.com are

queue-4.7/fscrypto-require-write-access-to-mount-to-set-encryption-policy.patch