[PATCH 14/18] crypto: sha256 - Use same state format as legacy drivers

Eric Biggers
2025-06-25T07:10:34Z

Make the export and import functions for the sha224, sha256,
hmac(sha224), and hmac(sha256) shash algorithms use the same format as
the padlock-sha and nx-sha256 drivers, as required by Herbert.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
crypto/sha256.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 95 insertions(+)

diff --git a/crypto/sha256.c b/crypto/sha256.c
index d81166cbba953..052806559f06c 100644
--- a/crypto/sha256.c
+++ b/crypto/sha256.c
@@ -11,10 +11,47 @@
#include <crypto/internal/hash.h>
#include <crypto/sha2.h>
#include <linux/kernel.h>
#include <linux/module.h>

+/*
+ * Export and import functions. crypto_shash wants a particular format that
+ * matches that used by some legacy drivers. It currently is the same as the
+ * library SHA context, except the value in bytecount must be block-aligned and
+ * the remainder must be stored in an extra u8 appended to the struct.
+ */
+
+#define SHA256_SHASH_STATE_SIZE 105
+static_assert(offsetof(struct __sha256_ctx, state) == 0);
+static_assert(offsetof(struct __sha256_ctx, bytecount) == 32);
+static_assert(offsetof(struct __sha256_ctx, buf) == 40);
+static_assert(sizeof(struct __sha256_ctx) + 1 == SHA256_SHASH_STATE_SIZE);
+
+static int __crypto_sha256_export(const struct __sha256_ctx *ctx0, void *out)
+{
+ struct __sha256_ctx ctx = *ctx0;
+ unsigned int partial;
+ u8 *p = out;
+
+ partial = ctx.bytecount % SHA256_BLOCK_SIZE;
+ ctx.bytecount -= partial;
+ memcpy(p, &ctx, sizeof(ctx));
+ p += sizeof(ctx);
+ *p = partial;
+ return 0;
+}
+
+static int __crypto_sha256_import(struct __sha256_ctx *ctx, const void *in)
+{
+ const u8 *p = in;
+
+ memcpy(ctx, p, sizeof(*ctx));
+ p += sizeof(*ctx);
+ ctx->bytecount += *p;
+ return 0;
+}
+
/* SHA-224 */

const u8 sha224_zero_message_hash[SHA224_DIGEST_SIZE] = {
0xd1, 0x4a, 0x02, 0x8c, 0x2a, 0x3a, 0x2b, 0xc9, 0x47,
0x61, 0x02, 0xbb, 0x28, 0x82, 0x34, 0xc4, 0x15, 0xa2,
@@ -49,10 +86,20 @@ static int crypto_sha224_digest(struct shash_desc *desc,
{
sha224(data, len, out);
return 0;
}

+static int crypto_sha224_export(struct shash_desc *desc, void *out)
+{
+ return __crypto_sha256_export(&SHA224_CTX(desc)->ctx, out);
+}
+
+static int crypto_sha224_import(struct shash_desc *desc, const void *in)
+{
+ return __crypto_sha256_import(&SHA224_CTX(desc)->ctx, in);
+}
+
/* SHA-256 */

const u8 sha256_zero_message_hash[SHA256_DIGEST_SIZE] = {
0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14,
0x9a, 0xfb, 0xf4, 0xc8, 0x99, 0x6f, 0xb9, 0x24,
@@ -87,10 +134,20 @@ static int crypto_sha256_digest(struct shash_desc *desc,
{
sha256(data, len, out);
return 0;
}

+static int crypto_sha256_export(struct shash_desc *desc, void *out)
+{
+ return __crypto_sha256_export(&SHA256_CTX(desc)->ctx, out);
+}
+
+static int crypto_sha256_import(struct shash_desc *desc, const void *in)
+{
+ return __crypto_sha256_import(&SHA256_CTX(desc)->ctx, in);
+}
+
/* HMAC-SHA224 */

#define HMAC_SHA224_KEY(tfm) ((struct hmac_sha224_key *)crypto_shash_ctx(tfm))
#define HMAC_SHA224_CTX(desc) ((struct hmac_sha224_ctx *)shash_desc_ctx(desc))

@@ -126,10 +183,23 @@ static int crypto_hmac_sha224_digest(struct shash_desc *desc,
{
hmac_sha224(HMAC_SHA224_KEY(desc->tfm), data, len, out);
return 0;
}

+static int crypto_hmac_sha224_export(struct shash_desc *desc, void *out)
+{
+ return __crypto_sha256_export(&HMAC_SHA224_CTX(desc)->ctx.sha_ctx, out);
+}
+
+static int crypto_hmac_sha224_import(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(&ctx->ctx.sha_ctx, in);
+}
+
/* HMAC-SHA256 */

#define HMAC_SHA256_KEY(tfm) ((struct hmac_sha256_key *)crypto_shash_ctx(tfm))
#define HMAC_SHA256_CTX(desc) ((struct hmac_sha256_ctx *)shash_desc_ctx(desc))

@@ -165,10 +235,23 @@ static int crypto_hmac_sha256_digest(struct shash_desc *desc,
{
hmac_sha256(HMAC_SHA256_KEY(desc->tfm), data, len, out);
return 0;
}

+static int crypto_hmac_sha256_export(struct shash_desc *desc, void *out)
+{
+ return __crypto_sha256_export(&HMAC_SHA256_CTX(desc)->ctx.sha_ctx, out);
+}
+
+static int crypto_hmac_sha256_import(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(&ctx->ctx.sha_ctx, in);
+}
+
/* Algorithm definitions */

static struct shash_alg algs[] = {
{
.base.cra_name = "sha224",
@@ -179,11 +262,14 @@ static struct shash_alg algs[] = {
.digestsize = SHA224_DIGEST_SIZE,
.init = crypto_sha224_init,
.update = crypto_sha224_update,
.final = crypto_sha224_final,
.digest = crypto_sha224_digest,
+ .export = crypto_sha224_export,
+ .import = crypto_sha224_import,
.descsize = sizeof(struct sha224_ctx),
+ .statesize = SHA256_SHASH_STATE_SIZE,
},
{
.base.cra_name = "sha256",
.base.cra_driver_name = "sha256-lib",
.base.cra_priority = 300,
@@ -192,11 +278,14 @@ static struct shash_alg algs[] = {
.digestsize = SHA256_DIGEST_SIZE,
.init = crypto_sha256_init,
.update = crypto_sha256_update,
.final = crypto_sha256_final,
.digest = crypto_sha256_digest,
+ .export = crypto_sha256_export,
+ .import = crypto_sha256_import,
.descsize = sizeof(struct sha256_ctx),
+ .statesize = SHA256_SHASH_STATE_SIZE,
},
{
.base.cra_name = "hmac(sha224)",
.base.cra_driver_name = "hmac-sha224-lib",
.base.cra_priority = 300,
@@ -207,11 +296,14 @@ static struct shash_alg algs[] = {
.setkey = crypto_hmac_sha224_setkey,
.init = crypto_hmac_sha224_init,
.update = crypto_hmac_sha224_update,
.final = crypto_hmac_sha224_final,
.digest = crypto_hmac_sha224_digest,
+ .export = crypto_hmac_sha224_export,
+ .import = crypto_hmac_sha224_import,
.descsize = sizeof(struct hmac_sha224_ctx),
+ .statesize = SHA256_SHASH_STATE_SIZE,
},
{
.base.cra_name = "hmac(sha256)",
.base.cra_driver_name = "hmac-sha256-lib",
.base.cra_priority = 300,
@@ -222,11 +314,14 @@ static struct shash_alg algs[] = {
.setkey = crypto_hmac_sha256_setkey,
.init = crypto_hmac_sha256_init,
.update = crypto_hmac_sha256_update,
.final = crypto_hmac_sha256_final,
.digest = crypto_hmac_sha256_digest,
+ .export = crypto_hmac_sha256_export,
+ .import = crypto_hmac_sha256_import,
.descsize = sizeof(struct hmac_sha256_ctx),
+ .statesize = SHA256_SHASH_STATE_SIZE,
},
};

static int __init crypto_sha256_mod_init(void)
{
--
2.50.0