crypto: hash - Add crypto_clone_ahash/shash

This patch adds the helpers crypto_clone_ahash and crypto_clone_shash.
They are the hash-specific counterparts of crypto_clone_tfm.

This allows code paths that cannot otherwise allocate a hash tfm
object to do so.  Once a new tfm has been obtained its key could
then be changed without impacting other users.

Note that only algorithms that implement clone_tfm can be cloned.
However, all keyless hashes can be cloned by simply reusing the
tfm object.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 52 insertions, 0 deletions

diff --git a/crypto/shash.c b/crypto/shash.c
index 4cefa614dbbd..5845b7d59b2f 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -445,6 +445,24 @@ int crypto_init_shash_ops_async(struct crypto_tfm *tfm)
 	return 0;
 }
 
+struct crypto_ahash *crypto_clone_shash_ops_async(struct crypto_ahash *nhash,
+						  struct crypto_ahash *hash)
+{
+	struct crypto_shash **nctx = crypto_ahash_ctx(nhash);
+	struct crypto_shash **ctx = crypto_ahash_ctx(hash);
+	struct crypto_shash *shash;
+
+	shash = crypto_clone_shash(*ctx);
+	if (IS_ERR(shash)) {
+		crypto_free_ahash(nhash);
+		return ERR_CAST(shash);
+	}
+
+	*nctx = shash;
+
+	return nhash;
+}
+
 static void crypto_shash_exit_tfm(struct crypto_tfm *tfm)
 {
 	struct crypto_shash *hash = __crypto_shash_cast(tfm);
@@ -564,6 +582,40 @@ int crypto_has_shash(const char *alg_name, u32 type, u32 mask)
 }
 EXPORT_SYMBOL_GPL(crypto_has_shash);
 
+struct crypto_shash *crypto_clone_shash(struct crypto_shash *hash)
+{
+	struct crypto_tfm *tfm = crypto_shash_tfm(hash);
+	struct shash_alg *alg = crypto_shash_alg(hash);
+	struct crypto_shash *nhash;
+	int err;
+
+	if (!crypto_shash_alg_has_setkey(alg)) {
+		tfm = crypto_tfm_get(tfm);
+		if (IS_ERR(tfm))
+			return ERR_CAST(tfm);
+
+		return hash;
+	}
+
+	if (!alg->clone_tfm)
+		return ERR_PTR(-ENOSYS);
+
+	nhash = crypto_clone_tfm(&crypto_shash_type, tfm);
+	if (IS_ERR(nhash))
+		return nhash;
+
+	nhash->descsize = hash->descsize;
+
+	err = alg->clone_tfm(nhash, hash);
+	if (err) {
+		crypto_free_shash(nhash);
+		return ERR_PTR(err);
+	}
+
+	return nhash;
+}
+EXPORT_SYMBOL_GPL(crypto_clone_shash);
+
 int hash_prepare_alg(struct hash_alg_common *alg)
 {
 	struct crypto_istat_hash *istat = hash_get_stat(alg);