linux-kernel - [PATCH v2 4/5] eCryptfs: move ecryptfs_find_auth_tok_for_sig() call before mutex

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Date:	Mon, 21 Mar 2011 16:00:54 +0100
From:	Roberto Sassu <roberto.sassu@...ito.it>
To:	tyhicks@...ux.vnet.ibm.com
Cc:	kirkland@...onical.com, dhowells@...hat.com, jmorris@...ei.org,
	linux-fsdevel@...r.kernel.org, keyrings@...ux-nfs.org,
	linux-kernel@...r.kernel.org, ecryptfs-devel@...ts.launchpad.net,
	Roberto Sassu <roberto.sassu@...ito.it>
Subject: [PATCH v2 4/5] 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@...ito.it>
---
 fs/ecryptfs/keystore.c |   38 +++++++++++++++++++-------------------
 1 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index ff92b3c..09b3afe 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -643,6 +643,16 @@ 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);
@@ -728,16 +738,6 @@ 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) {
@@ -991,6 +991,15 @@ 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);
@@ -1037,15 +1046,6 @@ 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) {
-- 
1.7.4


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