crypto: sha256 - Implement export_core() and import_core()

Since commit 9d7a0ab ("crypto: ahash - Handle partial blocks in
API"), the recently-added export_core() and import_core() methods in
struct shash_alg have effectively become mandatory (even though it is
not tested or enforced), since legacy drivers that need a fallback
depend on them.  Make crypto/sha256.c compatible with these legacy
drivers by adding export_core() and import_core() methods to it.

Reported-by: Giovanni Cabiddu <[email protected]>
Reported-by: Ovidiu Panait <[email protected]>
Closes: https://lore.kernel.org/r/[email protected]
Fixes: 07f0909 ("crypto: sha256 - Use same state format as legacy drivers")
Tested-by: Giovanni Cabiddu <[email protected]>
Tested-by: Ovidiu Panait <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Eric Biggers <[email protected]>

Author: Eric Biggers

crypto/sha256.c

@@ -50,6 +50,19 @@ static int __crypto_sha256_import(struct __sha256_ctx *ctx, const void *in)
 	return 0;
 }
 
+static int __crypto_sha256_export_core(const struct __sha256_ctx *ctx,
+				       void *out)
+{
+	memcpy(out, ctx, offsetof(struct __sha256_ctx, buf));
+	return 0;
+}
+
+static int __crypto_sha256_import_core(struct __sha256_ctx *ctx, const void *in)
+{
+	memcpy(ctx, in, offsetof(struct __sha256_ctx, buf));
+	return 0;
+}
+
 /* SHA-224 */
 
 const u8 sha224_zero_message_hash[SHA224_DIGEST_SIZE] = {
@@ -98,6 +111,16 @@ static int crypto_sha224_import(struct shash_desc *desc, const void *in)
 	return __crypto_sha256_import(&SHA224_CTX(desc)->ctx, in);
 }
 
+static int crypto_sha224_export_core(struct shash_desc *desc, void *out)
+{
+	return __crypto_sha256_export_core(&SHA224_CTX(desc)->ctx, out);
+}
+
+static int crypto_sha224_import_core(struct shash_desc *desc, const void *in)
+{
+	return __crypto_sha256_import_core(&SHA224_CTX(desc)->ctx, in);
+}
+
 /* SHA-256 */
 
 const u8 sha256_zero_message_hash[SHA256_DIGEST_SIZE] = {
@@ -146,6 +169,16 @@ static int crypto_sha256_import(struct shash_desc *desc, const void *in)
 	return __crypto_sha256_import(&SHA256_CTX(desc)->ctx, in);
 }
 
+static int crypto_sha256_export_core(struct shash_desc *desc, void *out)
+{
+	return __crypto_sha256_export_core(&SHA256_CTX(desc)->ctx, out);
+}
+
+static int crypto_sha256_import_core(struct shash_desc *desc, const void *in)
+{
+	return __crypto_sha256_import_core(&SHA256_CTX(desc)->ctx, in);
+}
+
 /* HMAC-SHA224 */
 
 #define HMAC_SHA224_KEY(tfm) ((struct hmac_sha224_key *)crypto_shash_ctx(tfm))
@@ -198,6 +231,21 @@ static int crypto_hmac_sha224_import(struct shash_desc *desc, const void *in)
 	return __crypto_sha256_import(&ctx->ctx.sha_ctx, in);
 }
 
+static int crypto_hmac_sha224_export_core(struct shash_desc *desc, void *out)
+{
+	return __crypto_sha256_export_core(&HMAC_SHA224_CTX(desc)->ctx.sha_ctx,
+					   out);
+}
+
+static int crypto_hmac_sha224_import_core(struct shash_desc *desc,
+					  const void *in)
+{
+	struct hmac_sha224_ctx *ctx = HMAC_SHA224_CTX(desc);
+
+	ctx->ctx.ostate = HMAC_SHA224_KEY(desc->tfm)->key.ostate;
+	return __crypto_sha256_import_core(&ctx->ctx.sha_ctx, in);
+}
+
 /* HMAC-SHA256 */
 
 #define HMAC_SHA256_KEY(tfm) ((struct hmac_sha256_key *)crypto_shash_ctx(tfm))
@@ -250,6 +298,21 @@ static int crypto_hmac_sha256_import(struct shash_desc *desc, const void *in)
 	return __crypto_sha256_import(&ctx->ctx.sha_ctx, in);
 }
 
+static int crypto_hmac_sha256_export_core(struct shash_desc *desc, void *out)
+{
+	return __crypto_sha256_export_core(&HMAC_SHA256_CTX(desc)->ctx.sha_ctx,
+					   out);
+}
+
+static int crypto_hmac_sha256_import_core(struct shash_desc *desc,
+					  const void *in)
+{
+	struct hmac_sha256_ctx *ctx = HMAC_SHA256_CTX(desc);
+
+	ctx->ctx.ostate = HMAC_SHA256_KEY(desc->tfm)->key.ostate;
+	return __crypto_sha256_import_core(&ctx->ctx.sha_ctx, in);
+}
+
 /* Algorithm definitions */
 
 static struct shash_alg algs[] = {
@@ -266,6 +329,8 @@ static struct shash_alg algs[] = {
 		.digest			= crypto_sha224_digest,
 		.export			= crypto_sha224_export,
 		.import			= crypto_sha224_import,
+		.export_core		= crypto_sha224_export_core,
+		.import_core		= crypto_sha224_import_core,
 		.descsize		= sizeof(struct sha224_ctx),
 		.statesize		= SHA256_SHASH_STATE_SIZE,
 	},
@@ -282,6 +347,8 @@ static struct shash_alg algs[] = {
 		.digest			= crypto_sha256_digest,
 		.export			= crypto_sha256_export,
 		.import			= crypto_sha256_import,
+		.export_core		= crypto_sha256_export_core,
+		.import_core		= crypto_sha256_import_core,
 		.descsize		= sizeof(struct sha256_ctx),
 		.statesize		= SHA256_SHASH_STATE_SIZE,
 	},
@@ -300,6 +367,8 @@ static struct shash_alg algs[] = {
 		.digest			= crypto_hmac_sha224_digest,
 		.export			= crypto_hmac_sha224_export,
 		.import			= crypto_hmac_sha224_import,
+		.export_core		= crypto_hmac_sha224_export_core,
+		.import_core		= crypto_hmac_sha224_import_core,
 		.descsize		= sizeof(struct hmac_sha224_ctx),
 		.statesize		= SHA256_SHASH_STATE_SIZE,
 	},
@@ -318,6 +387,8 @@ static struct shash_alg algs[] = {
 		.digest			= crypto_hmac_sha256_digest,
 		.export			= crypto_hmac_sha256_export,
 		.import			= crypto_hmac_sha256_import,
+		.export_core		= crypto_hmac_sha256_export_core,
+		.import_core		= crypto_hmac_sha256_import_core,
 		.descsize		= sizeof(struct hmac_sha256_ctx),
 		.statesize		= SHA256_SHASH_STATE_SIZE,
 	},