The patch titled
ecryptfs: check for existing key_tfm at mount time
has been added to the -mm tree. Its filename is
ecryptfs-check-for-existing-key_tfm-at-mount-time.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: ecryptfs: check for existing key_tfm at mount time
From: Eric Sandeen <sandeen@xxxxxxxxxx>
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 <sandeen@xxxxxxxxxx>
Cc: Michael Halcrow <mhalcrow@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ecryptfs/crypto.c | 66 +++++++++++++++++++++++++-------
fs/ecryptfs/ecryptfs_kernel.h | 1
fs/ecryptfs/main.c | 10 +++-
3 files changed, 61 insertions(+), 16 deletions(-)
diff -puN fs/ecryptfs/crypto.c~ecryptfs-check-for-existing-key_tfm-at-mount-time fs/ecryptfs/crypto.c
--- a/fs/ecryptfs/crypto.c~ecryptfs-check-for-existing-key_tfm-at-mount-time
+++ a/fs/ecryptfs/crypto.c
@@ -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 +1845,51 @@ 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)
@@ -1854,22 +1899,17 @@ 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:
diff -puN fs/ecryptfs/ecryptfs_kernel.h~ecryptfs-check-for-existing-key_tfm-at-mount-time fs/ecryptfs/ecryptfs_kernel.h
--- a/fs/ecryptfs/ecryptfs_kernel.h~ecryptfs-check-for-existing-key_tfm-at-mount-time
+++ a/fs/ecryptfs/ecryptfs_kernel.h
@@ -617,6 +617,7 @@ 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);
diff -puN fs/ecryptfs/main.c~ecryptfs-check-for-existing-key_tfm-at-mount-time fs/ecryptfs/main.c
--- a/fs/ecryptfs/main.c~ecryptfs-check-for-existing-key_tfm-at-mount-time
+++ a/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",
_
Patches currently in -mm which might be from sandeen@xxxxxxxxxx are
ecryptfs-fix-string-overflow-on-long-cipher-names.patch
ecryptfs-fix-unlocking-in-error-paths.patch
ecryptfs-redo-dgetmntget-on-dentry_open-failure.patch
hfs-handle-more-on-disk-corruptions-without-oopsing.patch
hfs-handle-more-on-disk-corruptions-without-oopsing-fix.patch
ext2-change-the-default-behaviour-on-error.patch
export-iov_shorten-for-ext4s-use.patch
ecryptfs-make-show_options-reflect-actual-mount-options.patch
ecryptfs-make-show_options-reflect-actual-mount-options-fix.patch
ecryptfs-remove-debug-as-mount-option-and-warn-if-set-via-modprobe.patch
ecryptfs-check-for-existing-key_tfm-at-mount-time.patch
ext3-change-the-default-behaviour-on-error.patch
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