crypto: shash - Require all algorithms to support export/import
Herbert Xu [Wed, 22 Jul 2009 04:37:06 +0000 (12:37 +0800)]
This patch provides a default export/import function for all
shash algorithms.  It simply copies the descriptor context as
is done by sha1_generic.

This in essence means that all existing shash algorithms now
support export/import.  This is something that will be depended
upon in implementations such as hmac.  Therefore all new shash
and ahash implementations must support export/import.

For those that cannot obtain a partial result, padlock-sha's
fallback model should be used so that a partial result is always
available.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/shash.c

index 7713b52..98b7f46 100644 (file)
@@ -183,14 +183,16 @@ int crypto_shash_digest(struct shash_desc *desc, const u8 *data,
 }
 EXPORT_SYMBOL_GPL(crypto_shash_digest);
 
-static int shash_no_export(struct shash_desc *desc, void *out)
+static int shash_default_export(struct shash_desc *desc, void *out)
 {
-       return -ENOSYS;
+       memcpy(out, shash_desc_ctx(desc), crypto_shash_descsize(desc->tfm));
+       return 0;
 }
 
-static int shash_no_import(struct shash_desc *desc, const void *in)
+static int shash_default_import(struct shash_desc *desc, const void *in)
 {
-       return -ENOSYS;
+       memcpy(shash_desc_ctx(desc), in, crypto_shash_descsize(desc->tfm));
+       return 0;
 }
 
 static int shash_async_setkey(struct crypto_ahash *tfm, const u8 *key,
@@ -563,10 +565,11 @@ static int shash_prepare_alg(struct shash_alg *alg)
                alg->finup = shash_finup_unaligned;
        if (!alg->digest)
                alg->digest = shash_digest_unaligned;
-       if (!alg->import)
-               alg->import = shash_no_import;
-       if (!alg->export)
-               alg->export = shash_no_export;
+       if (!alg->export) {
+               alg->export = shash_default_export;
+               alg->import = shash_default_import;
+               alg->statesize = alg->descsize;
+       }
        if (!alg->setkey)
                alg->setkey = shash_no_setkey;