This patch adds a default null skcipher for users such as gcm
to perform copies on SG lists.
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
---
crypto/crypto_null.c | 39 +++++++++++++++++++++++++++++++++++++++
include/crypto/null.h | 3 +++
2 files changed, 42 insertions(+)
diff --git a/crypto/crypto_null.c b/crypto/crypto_null.c
index a203191..941c9a4 100644
--- a/crypto/crypto_null.c
+++ b/crypto/crypto_null.c
@@ -25,6 +25,10 @@
#include <linux/mm.h>
#include <linux/string.h>
+static DEFINE_MUTEX(crypto_default_null_skcipher_lock);
+static struct crypto_blkcipher *crypto_default_null_skcipher;
+static int crypto_default_null_skcipher_refcnt;
+
static int null_compress(struct crypto_tfm *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int *dlen)
{
@@ -149,6 +153,41 @@ MODULE_ALIAS_CRYPTO("compress_null");
MODULE_ALIAS_CRYPTO("digest_null");
MODULE_ALIAS_CRYPTO("cipher_null");
+struct crypto_blkcipher *crypto_get_default_null_skcipher(void)
+{
+ struct crypto_blkcipher *tfm;
+
+ mutex_lock(&crypto_default_null_skcipher_lock);
+ tfm = crypto_default_null_skcipher;
+
+ if (!tfm) {
+ tfm = crypto_alloc_blkcipher("ecb(cipher_null)", 0, 0);
+ if (IS_ERR(tfm))
+ goto unlock;
+
+ crypto_default_null_skcipher = tfm;
+ }
+
+ crypto_default_null_skcipher_refcnt++;
+
+unlock:
+ mutex_unlock(&crypto_default_null_skcipher_lock);
+
+ return tfm;
+}
+EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
+
+void crypto_put_default_null_skcipher(void)
+{
+ mutex_lock(&crypto_default_null_skcipher_lock);
+ if (!--crypto_default_null_skcipher_refcnt) {
+ crypto_free_blkcipher(crypto_default_null_skcipher);
+ crypto_default_null_skcipher = NULL;
+ }
+ mutex_unlock(&crypto_default_null_skcipher_lock);
+}
+EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
+
static int __init crypto_null_mod_init(void)
{
int ret = 0;
diff --git a/include/crypto/null.h b/include/crypto/null.h
index b7c864c..06dc30d 100644
--- a/include/crypto/null.h
+++ b/include/crypto/null.h
@@ -8,4 +8,7 @@
#define NULL_DIGEST_SIZE 0
#define NULL_IV_SIZE 0
+struct crypto_blkcipher *crypto_get_default_null_skcipher(void);
+void crypto_put_default_null_skcipher(void);
+
#endif
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