FAILED: patch "[PATCH] fscrypto: add authorization check for setting encryption" failed to apply to 4.4-stable tree

FAILED: patch "[PATCH] fscrypto: add authorization check for setting encryption" failed to apply to 4.4-stable tree

[gregkh]

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 163ae1c6ad6299b19e22b4a35d5ab24a89791a98 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 8 Sep 2016 10:57:08 -0700
Subject: [PATCH] fscrypto: add authorization check for setting encryption
 policy

On an ext4 or f2fs filesystem with file encryption supported, a user
could set an encryption policy on any empty directory(*) to which they
had readonly access.  This is obviously problematic, since such a
directory might be owned by another user and the new encryption policy
would prevent that other user from creating files in their own directory
(for example).

Fix this by requiring inode_owner_or_capable() permission to set an
encryption policy.  This means that either the caller must own the file,
or the caller must have the capability CAP_FOWNER.

(*) Or also on any regular file, for f2fs v4.6 and later and ext4
    v4.8-rc1 and later; a separate bug fix is coming for that.

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>

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 0f9961eede1e..c9800b1a2e93 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -95,6 +95,9 @@ static int create_encryption_context_from_policy(struct inode *inode,
 int fscrypt_process_policy(struct inode *inode,
 				const struct fscrypt_policy *policy)
 {
+	if (!inode_owner_or_capable(inode))
+		return -EACCES;
+
 	if (policy->version != 0)
 		return -EINVAL;