eCryptfs: move ecryptfs_find_auth_tok_for_sig() call before mutex_lock

The ecryptfs_find_auth_tok_for_sig() call is moved before the
mutex_lock(s->tfm_mutex) instruction in order to avoid possible deadlocks
that may occur by holding the lock on the two semaphores 'key->sem' and
's->tfm_mutex' in reverse order.

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index 3c4039c..d95dd50 100644 (file)
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -635,6 +635,16 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
        }
        s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
        (*packet_size) = 0;
+       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) {
+               printk(KERN_ERR "%s: Error attempting to find auth tok for "
+                      "fnek sig [%s]; rc = [%d]\n", __func__,
+                      mount_crypt_stat->global_default_fnek_sig, rc);
+               goto out;
+       }
        rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
                &s->desc.tfm,
                &s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
@@ -720,16 +730,6 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
                goto out_free_unlock;
        }
        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) {
-               printk(KERN_ERR "%s: Error attempting to find auth tok for "
-                      "fnek sig [%s]; rc = [%d]\n", __func__,
-                      mount_crypt_stat->global_default_fnek_sig, rc);
-               goto out_free_unlock;
-       }
        /* TODO: Support other key modules than passphrase for
         * filename encryption */
        if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
@@ -983,6 +983,15 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
                       __func__, s->cipher_code);
                goto out;
        }
+       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 "
+                      "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
+                      rc);
+               goto out;
+       }
        rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->desc.tfm,
                                                        &s->tfm_mutex,
                                                        s->cipher_string);
@@ -1029,15 +1038,6 @@ 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(&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 "
-                      "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
-                      rc);
-               goto out_free_unlock;
-       }
        /* TODO: Support other key modules than passphrase for
         * filename encryption */
        if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {