ecryptfs: release keys loaded in ecryptfs_keyring_auth_tok_for_sig()

This patch allows keys requested in the function
ecryptfs_keyring_auth_tok_for_sig()to be released when they are no
longer required. In particular keys are directly released in the same
function if the obtained authentication token is not valid.

Further, a new function parameter 'auth_tok_key' has been added to
ecryptfs_find_auth_tok_for_sig() in order to provide callers the key
pointer to be passed to key_put().

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Cc: Dustin Kirkland <kirkland@canonical.com>
Cc: James Morris <jmorris@namei.org>
[Tyler: Initialize auth_tok_key to NULL in ecryptfs_parse_packet_set]
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

1 files changed, 28 insertions, 6 deletions

diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index 73811cfa2ea4..b85c6a7770a8 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -446,6 +446,7 @@ out:
  */
 static int
 ecryptfs_find_auth_tok_for_sig(
+        struct key **auth_tok_key,
         struct ecryptfs_auth_tok **auth_tok,
         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
         char *sig)
@@ -453,12 +454,12 @@ ecryptfs_find_auth_tok_for_sig(
         struct ecryptfs_global_auth_tok *global_auth_tok;
         int rc = 0;
 
+        (*auth_tok_key) = NULL;
         (*auth_tok) = NULL;
         if (ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
                                                   mount_crypt_stat, sig)) {
-                struct key *auth_tok_key;
 
-                rc = ecryptfs_keyring_auth_tok_for_sig(&auth_tok_key, auth_tok,
+                rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
                                                        sig);
         } else
                 (*auth_tok) = global_auth_tok->global_auth_tok;
@@ -509,6 +510,7 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
                              char *filename, size_t filename_size)
 {
         struct ecryptfs_write_tag_70_packet_silly_stack *s;
+        struct key *auth_tok_key = NULL;
         int rc = 0;
 
         s = kmalloc(sizeof(*s), GFP_KERNEL);
@@ -606,6 +608,7 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
         }
         dest[s->i++] = s->cipher_code;
         rc = ecryptfs_find_auth_tok_for_sig(
+                &auth_tok_key,
                 &s->auth_tok, mount_crypt_stat,
                 mount_crypt_stat->global_default_fnek_sig);
         if (rc) {
@@ -753,6 +756,8 @@ out_free_unlock:
 out_unlock:
         mutex_unlock(s->tfm_mutex);
 out:
+        if (auth_tok_key)
+                key_put(auth_tok_key);
         kfree(s);
         return rc;
 }
@@ -798,6 +803,7 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
                              char *data, size_t max_packet_size)
 {
         struct ecryptfs_parse_tag_70_packet_silly_stack *s;
+        struct key *auth_tok_key = NULL;
         int rc = 0;
 
         (*packet_size) = 0;
@@ -910,7 +916,8 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
          * >= ECRYPTFS_MAX_IV_BYTES. */
         memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
         s->desc.info = s->iv;
-        rc = ecryptfs_find_auth_tok_for_sig(&s->auth_tok, mount_crypt_stat,
+        rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
+                                            &s->auth_tok, mount_crypt_stat,
                                             s->fnek_sig_hex);
         if (rc) {
                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
@@ -986,6 +993,8 @@ out:
                 (*filename_size) = 0;
                 (*filename) = NULL;
         }
+        if (auth_tok_key)
+                key_put(auth_tok_key);
         kfree(s);
         return rc;
 }
@@ -1557,14 +1566,19 @@ int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
                        ECRYPTFS_VERSION_MAJOR,
                        ECRYPTFS_VERSION_MINOR);
                 rc = -EINVAL;
-                goto out;
+                goto out_release_key;
         }
         if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
             && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
                 printk(KERN_ERR "Invalid auth_tok structure "
                        "returned from key query\n");
                 rc = -EINVAL;
-                goto out;
+                goto out_release_key;
+        }
+out_release_key:
+        if (rc) {
+                key_put(*auth_tok_key);
+                (*auth_tok_key) = NULL;
         }
 out:
         return rc;
@@ -1688,6 +1702,7 @@ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
         size_t tag_11_contents_size;
         size_t tag_11_packet_size;
+        struct key *auth_tok_key = NULL;
         int rc = 0;
 
         INIT_LIST_HEAD(&auth_tok_list);
@@ -1784,6 +1799,10 @@ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
          * just one will be sufficient to decrypt to get the FEK. */
 find_next_matching_auth_tok:
         found_auth_tok = 0;
+        if (auth_tok_key) {
+                key_put(auth_tok_key);
+                auth_tok_key = NULL;
+        }
         list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
                 candidate_auth_tok = &auth_tok_list_item->auth_tok;
                 if (unlikely(ecryptfs_verbosity > 0)) {
@@ -1800,7 +1819,8 @@ find_next_matching_auth_tok:
                         rc = -EINVAL;
                         goto out_wipe_list;
                 }
-                ecryptfs_find_auth_tok_for_sig(&matching_auth_tok,
+                ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
+                                               &matching_auth_tok,
                                                crypt_stat->mount_crypt_stat,
                                                candidate_auth_tok_sig);
                 if (matching_auth_tok) {
@@ -1866,6 +1886,8 @@ found_matching_auth_tok:
 out_wipe_list:
         wipe_auth_tok_list(&auth_tok_list);
 out:
+        if (auth_tok_key)
+                key_put(auth_tok_key);
         return rc;
 }