linux-kernel - Re: [PATCH v4 01/13] crypto: sha256 - support arch-optimized lib and expose through shash

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Message-ID: <aBGdiv17ztQnhAps@gondor.apana.org.au>
Date: Wed, 30 Apr 2025 11:48:26 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Eric Biggers <ebiggers@...nel.org>
Cc: linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	linux-riscv@...ts.infradead.org, sparclinux@...r.kernel.org,
	linux-s390@...r.kernel.org, x86@...nel.org,
	Ard Biesheuvel <ardb@...nel.org>,
	"Jason A . Donenfeld" <Jason@...c4.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v4 01/13] crypto: sha256 - support arch-optimized lib and
 expose through shash

On Mon, Apr 28, 2025 at 10:00:26AM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@...gle.com>
> 
> As has been done for various other algorithms, rework the design of the
> SHA-256 library to support arch-optimized implementations, and make
> crypto/sha256.c expose both generic and arch-optimized shash algorithms
> that wrap the library functions.
> 
> This allows users of the SHA-256 library functions to take advantage of
> the arch-optimized code, and this makes it much simpler to integrate
> SHA-256 for each architecture.
> 
> Note that sha256_base.h is not used in the new design.  It will be
> removed once all the architecture-specific code has been updated.
> 
> Move the generic block function into its own module to avoid a circular
> dependency from libsha256.ko => sha256-$ARCH.ko => libsha256.ko.
> 
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> ---
>  crypto/Kconfig                 |   1 +
>  crypto/Makefile                |   3 +-
>  crypto/sha256.c                | 201 +++++++++++++++++++++++++++++++++
>  crypto/sha256_generic.c        | 102 -----------------
>  include/crypto/internal/sha2.h |  28 +++++
>  include/crypto/sha2.h          |  15 +--
>  include/crypto/sha256_base.h   |   9 +-
>  lib/crypto/Kconfig             |  19 ++++
>  lib/crypto/Makefile            |   3 +
>  lib/crypto/sha256-generic.c    | 137 ++++++++++++++++++++++
>  lib/crypto/sha256.c            | 196 ++++++++++++++------------------
>  11 files changed, 487 insertions(+), 227 deletions(-)
>  create mode 100644 crypto/sha256.c
>  delete mode 100644 crypto/sha256_generic.c
>  create mode 100644 include/crypto/internal/sha2.h
>  create mode 100644 lib/crypto/sha256-generic.c

This is the patch that I will fold in here to maintain the existing
export format:

diff --git a/crypto/sha256.c b/crypto/sha256.c
index 1c2edcf9453d..c2588d08ee3e 100644
--- a/crypto/sha256.c
+++ b/crypto/sha256.c
@@ -116,6 +116,32 @@ static int crypto_sha224_final_arch(struct shash_desc *desc, u8 *out)
 	return 0;
 }
 
+static int crypto_sha256_import_lib(struct shash_desc *desc, const void *in)
+{
+	struct sha256_state *sctx = shash_desc_ctx(desc);
+	const u8 *p = in;
+
+	memcpy(sctx, p, sizeof(*sctx));
+	p += sizeof(*sctx);
+	sctx->count += *p;
+	return 0;
+}
+
+static int crypto_sha256_export_lib(struct shash_desc *desc, void *out)
+{
+	struct sha256_state *sctx0 = shash_desc_ctx(desc);
+	struct sha256_state sctx = *sctx0;
+	unsigned int partial;
+	u8 *p = out;
+
+	partial = sctx.count % SHA256_BLOCK_SIZE;
+	sctx.count -= partial;
+	memcpy(p, &sctx, sizeof(sctx));
+	p += sizeof(sctx);
+	*p = partial;
+	return 0;
+}
+
 static struct shash_alg algs[] = {
 	{
 		.base.cra_name		= "sha256",
@@ -130,6 +156,10 @@ static struct shash_alg algs[] = {
 		.finup			= crypto_sha256_finup_generic,
 		.digest			= crypto_sha256_digest_generic,
 		.descsize		= sizeof(struct sha256_state),
+		.statesize		= sizeof(struct crypto_sha256_state) +
+					  SHA256_BLOCK_SIZE + 1,
+		.import			= crypto_sha256_import_lib,
+		.export			= crypto_sha256_export_lib,
 	},
 	{
 		.base.cra_name		= "sha224",
@@ -142,6 +172,10 @@ static struct shash_alg algs[] = {
 		.update			= crypto_sha256_update_generic,
 		.final			= crypto_sha224_final_generic,
 		.descsize		= sizeof(struct sha256_state),
+		.statesize		= sizeof(struct crypto_sha256_state) +
+					  SHA256_BLOCK_SIZE + 1,
+		.import			= crypto_sha256_import_lib,
+		.export			= crypto_sha256_export_lib,
 	},
 	{
 		.base.cra_name		= "sha256",
@@ -156,6 +190,10 @@ static struct shash_alg algs[] = {
 		.finup			= crypto_sha256_finup_arch,
 		.digest			= crypto_sha256_digest_arch,
 		.descsize		= sizeof(struct sha256_state),
+		.statesize		= sizeof(struct crypto_sha256_state) +
+					  SHA256_BLOCK_SIZE + 1,
+		.import			= crypto_sha256_import_lib,
+		.export			= crypto_sha256_export_lib,
 	},
 	{
 		.base.cra_name		= "sha224",
@@ -168,6 +206,10 @@ static struct shash_alg algs[] = {
 		.update			= crypto_sha256_update_arch,
 		.final			= crypto_sha224_final_arch,
 		.descsize		= sizeof(struct sha256_state),
+		.statesize		= sizeof(struct crypto_sha256_state) +
+					  SHA256_BLOCK_SIZE + 1,
+		.import			= crypto_sha256_import_lib,
+		.export			= crypto_sha256_export_lib,
 	},
 };

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt