From 163ae1c6ad6299b19e22b4a35d5ab24a89791a98 Mon Sep 17 00:00:00 2001 From: Eric Biggers 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 Cc: stable@vger.kernel.org # 4.1+; check fs/{ext4,f2fs} Signed-off-by: Theodore Ts'o --- fs/crypto/policy.c | 3 +++ 1 file changed, 3 insertions(+) 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;