Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757532AbYAGWKZ (ORCPT ); Mon, 7 Jan 2008 17:10:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755020AbYAGWKM (ORCPT ); Mon, 7 Jan 2008 17:10:12 -0500 Received: from mx1.redhat.com ([66.187.233.31]:36920 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753668AbYAGWKK (ORCPT ); Mon, 7 Jan 2008 17:10:10 -0500 Message-ID: <4782A2DC.1050008@redhat.com> Date: Mon, 07 Jan 2008 16:08:28 -0600 From: Eric Sandeen User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Andrew Morton CC: linux-kernel Mailing List , Michael Halcrow , mike@halcrow.us, Jeff Moyer Subject: [PATCH] (UPDATED3) ecryptfs: check for existing key_tfm at mount time References: <476B4CB9.9070700@redhat.com> <20071221205618.d04bea09.akpm@linux-foundation.org> <476D4C8D.9080602@redhat.com> <20071222162516.df6fe557.akpm@linux-foundation.org> <476E9A30.6070602@redhat.com> In-Reply-To: <476E9A30.6070602@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6527 Lines: 188 (ugh, remove extra mutex_unlock I missed when changing locking per Andrew's suggestion...) Jeff Moyer pointed out that a mount; umount loop of ecryptfs, with the same cipher & other mount options, created a new ecryptfs_key_tfm_cache item each time, and the cache could grow quite large this way. Looking at this with mhalcrow, we saw that ecryptfs_parse_options() unconditionally called ecryptfs_add_new_key_tfm(), which is what was adding these items. Refactor ecryptfs_get_tfm_and_mutex_for_cipher_name() to create a new helper function, ecryptfs_tfm_exists(), which checks for the cipher on the cached key_tfm_list, and sets a pointer to it if it exists. This can then be called from ecryptfs_parse_options(), and new key_tfm's can be added only when a cached one is not found. With list locking changes suggested by akpm. Signed-off-by: Eric Sandeen --- Index: linux-2.6.24-rc3/fs/ecryptfs/crypto.c =================================================================== --- linux-2.6.24-rc3.orig/fs/ecryptfs/crypto.c +++ linux-2.6.24-rc3/fs/ecryptfs/crypto.c @@ -1780,7 +1780,7 @@ out: struct kmem_cache *ecryptfs_key_tfm_cache; static struct list_head key_tfm_list; -static struct mutex key_tfm_list_mutex; +struct mutex key_tfm_list_mutex; int ecryptfs_init_crypto(void) { @@ -1789,6 +1789,11 @@ int ecryptfs_init_crypto(void) return 0; } +/** + * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list + * + * Called only at module unload time + */ int ecryptfs_destroy_crypto(void) { struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp; @@ -1812,6 +1817,8 @@ ecryptfs_add_new_key_tfm(struct ecryptfs struct ecryptfs_key_tfm *tmp_tfm; int rc = 0; + BUG_ON(!mutex_is_locked(&key_tfm_list_mutex)); + tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL); if (key_tfm != NULL) (*key_tfm) = tmp_tfm; @@ -1838,13 +1845,50 @@ ecryptfs_add_new_key_tfm(struct ecryptfs (*key_tfm) = NULL; goto out; } - mutex_lock(&key_tfm_list_mutex); list_add(&tmp_tfm->key_tfm_list, &key_tfm_list); - mutex_unlock(&key_tfm_list_mutex); out: return rc; } +/** + * ecryptfs_tfm_exists - Search for existing tfm for cipher_name. + * @cipher_name: the name of the cipher to search for + * @key_tfm: set to corresponding tfm if found + * + * Searches for cached key_tfm matching @cipher_name + * Must be called with &key_tfm_list_mutex held + * Returns 1 if found, with @key_tfm set + * Returns 0 if not found, with @key_tfm set to NULL + */ +int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm) +{ + struct ecryptfs_key_tfm *tmp_key_tfm; + + BUG_ON(!mutex_is_locked(&key_tfm_list_mutex)); + + list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) { + if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) { + if (key_tfm) + (*key_tfm) = tmp_key_tfm; + return 1; + } + } + if (key_tfm) + (*key_tfm) = NULL; + return 0; +} + +/** + * ecryptfs_get_tfm_and_mutex_for_cipher_name + * + * @tfm: set to cached tfm found, or new tfm created + * @tfm_mutex: set to mutex for cached tfm found, or new tfm created + * @cipher_name: the name of the cipher to search for and/or add + * + * Sets pointers to @tfm & @tfm_mutex matching @cipher_name. + * Searches for cached item first, and creates new if not found. + * Returns 0 on success, non-zero if adding new cipher failed + */ int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm, struct mutex **tfm_mutex, char *cipher_name) @@ -1854,22 +1898,17 @@ int ecryptfs_get_tfm_and_mutex_for_ciphe (*tfm) = NULL; (*tfm_mutex) = NULL; + mutex_lock(&key_tfm_list_mutex); - list_for_each_entry(key_tfm, &key_tfm_list, key_tfm_list) { - if (strcmp(key_tfm->cipher_name, cipher_name) == 0) { - (*tfm) = key_tfm->key_tfm; - (*tfm_mutex) = &key_tfm->key_tfm_mutex; - mutex_unlock(&key_tfm_list_mutex); + if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) { + rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0); + if (rc) { + printk(KERN_ERR "Error adding new key_tfm to list; " + "rc = [%d]\n", rc); goto out; } } mutex_unlock(&key_tfm_list_mutex); - rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0); - if (rc) { - printk(KERN_ERR "Error adding new key_tfm to list; rc = [%d]\n", - rc); - goto out; - } (*tfm) = key_tfm->key_tfm; (*tfm_mutex) = &key_tfm->key_tfm_mutex; out: Index: linux-2.6.24-rc3/fs/ecryptfs/ecryptfs_kernel.h =================================================================== --- linux-2.6.24-rc3.orig/fs/ecryptfs/ecryptfs_kernel.h +++ linux-2.6.24-rc3/fs/ecryptfs/ecryptfs_kernel.h @@ -323,6 +323,8 @@ struct ecryptfs_key_tfm { unsigned char cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1]; }; +extern struct mutex key_tfm_list_mutex; + /** * This struct is to enable a mount-wide passphrase/salt combo. This * is more or less a stopgap to provide similar functionality to other @@ -617,6 +619,7 @@ ecryptfs_add_new_key_tfm(struct ecryptfs size_t key_size); int ecryptfs_init_crypto(void); int ecryptfs_destroy_crypto(void); +int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm); int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm, struct mutex **tfm_mutex, char *cipher_name); Index: linux-2.6.24-rc3/fs/ecryptfs/main.c =================================================================== --- linux-2.6.24-rc3.orig/fs/ecryptfs/main.c +++ linux-2.6.24-rc3/fs/ecryptfs/main.c @@ -410,9 +410,13 @@ static int ecryptfs_parse_options(struct if (!cipher_key_bytes_set) { mount_crypt_stat->global_default_cipher_key_size = 0; } - rc = ecryptfs_add_new_key_tfm( - NULL, mount_crypt_stat->global_default_cipher_name, - mount_crypt_stat->global_default_cipher_key_size); + mutex_lock(&key_tfm_list_mutex); + if (!ecryptfs_tfm_exists(mount_crypt_stat->global_default_cipher_name, + NULL)) + rc = ecryptfs_add_new_key_tfm( + NULL, mount_crypt_stat->global_default_cipher_name, + mount_crypt_stat->global_default_cipher_key_size); + mutex_unlock(&key_tfm_list_mutex); if (rc) { printk(KERN_ERR "Error attempting to initialize cipher with " "name = [%s] and key size = [%td]; rc = [%d]\n", -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/