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 <[email protected]>
---
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",
On Thu, Dec 20, 2007 at 11:18:49PM -0600, Eric Sandeen wrote:
> 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 <[email protected]>
Acked-by: Mike Halcrow <[email protected]>
> ---
>
> 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",
>
On Thu, 20 Dec 2007 23:18:49 -0600 Eric Sandeen <[email protected]> wrote:
> 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.
>
This change looks fishy.
> +/**
> + * 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;
Here we return a pointer to an object without holding the lock and without
taking a refcount on it. What prevents it from getting moved/freed/etc
while this thread of control is playing with it?
> + 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)) {
And given that we've just unlocked key_tfm_list_mutex, how do we know that
the return value from ecryptfs_tfm_exists() is still true in this window?
> + 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);
It would all look a lot more solid if this locking was retained and both
ecryptfs_tfm_exists() and ecryptfs_add_new_key_tfm() were designed to be
called under key_tfm_list_mutex.
> @@ -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);
dittoes.
Andrew Morton wrote:
> It would all look a lot more solid if this locking was retained and both
> ecryptfs_tfm_exists() and ecryptfs_add_new_key_tfm() were designed to be
> called under key_tfm_list_mutex.
Hmm good point, sorry for missing that. How's this look?
===========
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 <[email protected]>
---
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
@@ -1812,6 +1812,11 @@ 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;
@@ -1835,6 +1840,8 @@ 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;
@@ -1861,13 +1868,51 @@ 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) {
+ mutex_unlock(&key_tfm_list_mutex);
+ 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)
@@ -1877,22 +1922,17 @@ 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
@@ -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 +410,13 @@ 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",
On Sat, 22 Dec 2007 11:42:37 -0600 Eric Sandeen <[email protected]> wrote:
> Andrew Morton wrote:
>
> > It would all look a lot more solid if this locking was retained and both
> > ecryptfs_tfm_exists() and ecryptfs_add_new_key_tfm() were designed to be
> > called under key_tfm_list_mutex.
>
> Hmm good point, sorry for missing that. How's this look?
key_tfm_list_mutex gets used in fs/ecryptfs/main.c but it is static in
fs/ecryptfs/crypto.c
Andrew Morton wrote:
> On Sat, 22 Dec 2007 11:42:37 -0600 Eric Sandeen <[email protected]> wrote:
>
>> Andrew Morton wrote:
>>
>>> It would all look a lot more solid if this locking was retained and both
>>> ecryptfs_tfm_exists() and ecryptfs_add_new_key_tfm() were designed to be
>>> called under key_tfm_list_mutex.
>> Hmm good point, sorry for missing that. How's this look?
>
> key_tfm_list_mutex gets used in fs/ecryptfs/main.c but it is static in
> fs/ecryptfs/crypto.c
>
Ah crud that was a bunk-ism in -mm that I missed.
I'll send another updated patch soon.
-Eric
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 <[email protected]>
---
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
@@ -1778,7 +1778,7 @@ 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)
{
@@ -1787,6 +1787,11 @@ 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;
@@ -1810,6 +1815,8 @@ 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;
@@ -1835,13 +1842,51 @@ 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) {
+ mutex_unlock(&key_tfm_list_mutex);
+ 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)
@@ -1851,22 +1896,17 @@ 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
@@ -420,9 +420,13 @@ 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",
(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 <[email protected]>
---
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",