[PATCH 17/18] lib/crypto: sha256: Sync sha256_update() with sha512_update()

Eric Biggers
2025-06-25T07:10:35Z

The BLOCK_HASH_UPDATE_BLOCKS macro is difficult to read. For now, let's
just write the update explicitly in the straightforward way, mirroring
sha512_update(). It's possible that we'll bring back a macro for this
later, but it needs to be properly justified and hopefully a bit more
readable.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
lib/crypto/sha256.c | 28 +++++++++++++++++++++++++---
1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/lib/crypto/sha256.c b/lib/crypto/sha256.c
index 0de49bf8e8b8b..c93bf4699160c 100644
--- a/lib/crypto/sha256.c
+++ b/lib/crypto/sha256.c
@@ -8,11 +8,10 @@
* Copyright (c) 2014 Red Hat Inc.
* Copyright 2025 Google LLC
*/

#include <crypto/hmac.h>
-#include <crypto/internal/blockhash.h>
#include <crypto/sha2.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/unaligned.h>
@@ -177,12 +176,35 @@ EXPORT_SYMBOL_GPL(sha256_init);
void __sha256_update(struct __sha256_ctx *ctx, const u8 *data, size_t len)
{
size_t partial = ctx->bytecount % SHA256_BLOCK_SIZE;

ctx->bytecount += len;
- BLOCK_HASH_UPDATE_BLOCKS(sha256_blocks, &ctx->state, data, len,
- SHA256_BLOCK_SIZE, ctx->buf, partial);
+
+ if (partial + len >= SHA256_BLOCK_SIZE) {
+ size_t nblocks;
+
+ if (partial) {
+ size_t l = SHA256_BLOCK_SIZE - partial;
+
+ memcpy(&ctx->buf[partial], data, l);
+ data += l;
+ len -= l;
+
+ sha256_blocks(&ctx->state, ctx->buf, 1);
+ }
+
+ nblocks = len / SHA256_BLOCK_SIZE;
+ len %= SHA256_BLOCK_SIZE;
+
+ if (nblocks) {
+ sha256_blocks(&ctx->state, data, nblocks);
+ data += nblocks * SHA256_BLOCK_SIZE;
+ }
+ partial = 0;
+ }
+ if (len)
+ memcpy(&ctx->buf[partial], data, len);
}
EXPORT_SYMBOL(__sha256_update);

static void __sha256_final(struct __sha256_ctx *ctx,
u8 *out, size_t digest_size)
--
2.50.0