ecryptfs: added ecryptfs_mount_auth_tok_only mount parameter

This patch adds a new mount parameter 'ecryptfs_mount_auth_tok_only' to
force ecryptfs to use only authentication tokens which signature has
been specified at mount time with parameters 'ecryptfs_sig' and
'ecryptfs_fnek_sig'. In this way, after disabling the passthrough and
the encrypted view modes, it's possible to make available to users only
files encrypted with the specified authentication token.

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Cc: Dustin Kirkland <kirkland@canonical.com>
Cc: James Morris <jmorris@namei.org>
[Tyler: Clean up coding style errors found by checkpatch]
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 0032a9f..59ab793 100644 (file)
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -377,6 +377,7 @@ struct ecryptfs_mount_crypt_stat {
 #define ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES      0x00000010
 #define ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK   0x00000020
 #define ECRYPTFS_GLOBAL_ENCFN_USE_FEK          0x00000040
+#define ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY    0x00000080
        u32 flags;
        struct list_head global_auth_tok_list;
        struct mutex global_auth_tok_list_mutex;

diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index e7f029f..b1f6858 100644 (file)
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -459,6 +459,15 @@ ecryptfs_find_auth_tok_for_sig(
        if (ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
                                                  mount_crypt_stat, sig)) {
 
+               /* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the
+                * mount_crypt_stat structure, we prevent to use auth toks that
+                * are not inserted through the ecryptfs_add_global_auth_tok
+                * function.
+                */
+               if (mount_crypt_stat->flags
+                               & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
+                       return -EINVAL;
+
                rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
                                                       sig);
        } else

diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index cbd4e18..09eb529 100644 (file)
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -208,7 +208,8 @@ enum { ecryptfs_opt_sig, ecryptfs_opt_ecryptfs_sig,
        ecryptfs_opt_passthrough, ecryptfs_opt_xattr_metadata,
        ecryptfs_opt_encrypted_view, ecryptfs_opt_fnek_sig,
        ecryptfs_opt_fn_cipher, ecryptfs_opt_fn_cipher_key_bytes,
-       ecryptfs_opt_unlink_sigs, ecryptfs_opt_err };
+       ecryptfs_opt_unlink_sigs, ecryptfs_opt_mount_auth_tok_only,
+       ecryptfs_opt_err };
 
 static const match_table_t tokens = {
        {ecryptfs_opt_sig, "sig=%s"},
@@ -223,6 +224,7 @@ static const match_table_t tokens = {
        {ecryptfs_opt_fn_cipher, "ecryptfs_fn_cipher=%s"},
        {ecryptfs_opt_fn_cipher_key_bytes, "ecryptfs_fn_key_bytes=%u"},
        {ecryptfs_opt_unlink_sigs, "ecryptfs_unlink_sigs"},
+       {ecryptfs_opt_mount_auth_tok_only, "ecryptfs_mount_auth_tok_only"},
        {ecryptfs_opt_err, NULL}
 };
 
@@ -406,6 +408,10 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options)
                case ecryptfs_opt_unlink_sigs:
                        mount_crypt_stat->flags |= ECRYPTFS_UNLINK_SIGS;
                        break;
+               case ecryptfs_opt_mount_auth_tok_only:
+                       mount_crypt_stat->flags |=
+                               ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY;
+                       break;
                case ecryptfs_opt_err:
                default:
                        printk(KERN_WARNING