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Date: Thu, 20 Dec 2007 23:18:49 -0600
From: Eric Sandeen <sandeen@...hat.com>
To: linux-kernel Mailing List <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Michael Halcrow <mhalcrow@...ibm.com>
CC: mike@...crow.us, Jeff Moyer <jmoyer@...hat.com>
Subject: [PATCH] ecryptfs: check for existing key_tfm at mount time
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.
Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---
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
@@ -1868,6 +1868,33 @@ 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
+ *
+ * Returns 1 if found, with key_tfm set
+ * Returns 0 if not found, 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;
+
+ mutex_lock(&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) {
+ mutex_unlock(&key_tfm_list_mutex);
+ if (key_tfm)
+ (*key_tfm) = tmp_key_tfm;
+ return 1;
+ }
+ }
+ mutex_unlock(&key_tfm_list_mutex);
+ if (key_tfm)
+ (*key_tfm) = NULL;
+ return 0;
+}
+
int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
struct mutex **tfm_mutex,
char *cipher_name)
@@ -1877,22 +1904,15 @@ 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
@@ -623,6 +623,7 @@ 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 +410,11 @@ 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);
+ 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);
if (rc) {
printk(KERN_ERR "Error attempting to initialize cipher with "
"name = [%s] and key size = [%td]; rc = [%d]\n",
--
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