Patch "fscrypto: require write access to mount to set encryption policy" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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 4.4-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-4.4 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

commit ba63f23d69a3a10e7e527a02702023da68ef8a6d upstream.

[Please apply to 4.4-stable.  Note: this was already backported, but
only to ext4; it was missed that it should go to f2fs as well.  This is
needed to make xfstest generic/395 pass on f2fs.]

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>
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/f2fs/file.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1541,12 +1541,18 @@ static int f2fs_ioc_set_encryption_polic
 				sizeof(policy)))
 		return -EFAULT;
 
+	err = mnt_want_write_file(filp);
+	if (err)
+		return err;
+
 	mutex_lock(&inode->i_mutex);
 
 	err = f2fs_process_policy(&policy, inode);
 
 	mutex_unlock(&inode->i_mutex);
 
+	mnt_drop_write_file(filp);
+
 	return err;
 #else
 	return -EOPNOTSUPP;


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

queue-4.4/keys-fix-race-between-updating-and-finding-a-negative-key.patch
queue-4.4/fscrypto-require-write-access-to-mount-to-set-encryption-policy.patch
queue-4.4/fs-cache-fix-dereference-of-null-user_key_payload.patch
queue-4.4/lib-digsig-fix-dereference-of-null-user_key_payload.patch
queue-4.4/fscrypt-fix-dereference-of-null-user_key_payload.patch
queue-4.4/f2fs-crypto-add-missing-locking-for-keyring_key-access.patch
queue-4.4/keys-encrypted-fix-dereference-of-null-user_key_payload.patch
queue-4.4/f2fs-crypto-replace-some-bug_on-s-with-error-checks.patch
queue-4.4/keys-don-t-let-add_key-update-an-uninstantiated-key.patch