eCryptfs: check for eCryptfs cipher support at mount

commit 5f5b331d5c21228a6519dcb793fc1629646c51a6 upstream.

The issue occurs when eCryptfs is mounted with a cipher supported by
the crypto subsystem but not by eCryptfs. The mount succeeds and an
error does not occur until a write. This change checks for eCryptfs
cipher support at mount time.

Resolves Launchpad issue #338914, reported by Tyler Hicks in 03/2009.
https://bugs.launchpad.net/ecryptfs/+bug/338914

Signed-off-by: Tim Sally <tsally@atomicpeace.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index c2a9c39300c48de3f27a24751f52c73959ec1218..240832e8b289b4718d84ea5efa270f43cb6a4c94 100644 (file)
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -280,6 +280,7 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
        char *fnek_src;
        char *cipher_key_bytes_src;
        char *fn_cipher_key_bytes_src;
+       u8 cipher_code;
 
        *check_ruid = 0;
 
@@ -421,6 +422,18 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
            && !fn_cipher_key_bytes_set)
                mount_crypt_stat->global_default_fn_cipher_key_bytes =
                        mount_crypt_stat->global_default_cipher_key_size;
+
+       cipher_code = ecryptfs_code_for_cipher_string(
+               mount_crypt_stat->global_default_cipher_name,
+               mount_crypt_stat->global_default_cipher_key_size);
+       if (!cipher_code) {
+               ecryptfs_printk(KERN_ERR,
+                               "eCryptfs doesn't support cipher: %s",
+                               mount_crypt_stat->global_default_cipher_name);
+               rc = -EINVAL;
+               goto out;
+       }
+
        mutex_lock(&key_tfm_list_mutex);
        if (!ecryptfs_tfm_exists(mount_crypt_stat->global_default_cipher_name,
                                 NULL)) {