crypto: sha1 - Use same state format as legacy drivers

Same as sha256 and sha512: Use the state format that the generic partial
block handling code produces, as requested by Herbert, even though this
is applicable only to legacy drivers.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250712232329.818226-7-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

Author: Eric Biggers

crypto/sha1.c

@@ -12,6 +12,43 @@
 #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 SHA1_SHASH_STATE_SIZE (sizeof(struct sha1_ctx) + 1)
+static_assert(sizeof(struct sha1_ctx) == sizeof(struct sha1_state));
+static_assert(offsetof(struct sha1_ctx, state) == offsetof(struct sha1_state, state));
+static_assert(offsetof(struct sha1_ctx, bytecount) == offsetof(struct sha1_state, count));
+static_assert(offsetof(struct sha1_ctx, buf) == offsetof(struct sha1_state, buffer));
+
+static int __crypto_sha1_export(const struct sha1_ctx *ctx0, void *out)
+{
+	struct sha1_ctx ctx = *ctx0;
+	unsigned int partial;
+	u8 *p = out;
+
+	partial = ctx.bytecount % SHA1_BLOCK_SIZE;
+	ctx.bytecount -= partial;
+	memcpy(p, &ctx, sizeof(ctx));
+	p += sizeof(ctx);
+	*p = partial;
+	return 0;
+}
+
+static int __crypto_sha1_import(struct sha1_ctx *ctx, const void *in)
+{
+	const u8 *p = in;
+
+	memcpy(ctx, p, sizeof(*ctx));
+	p += sizeof(*ctx);
+	ctx->bytecount += *p;
+	return 0;
+}
+
 const u8 sha1_zero_message_hash[SHA1_DIGEST_SIZE] = {
 	0xda, 0x39, 0xa3, 0xee, 0x5e, 0x6b, 0x4b, 0x0d,
 	0x32, 0x55, 0xbf, 0xef, 0x95, 0x60, 0x18, 0x90,
@@ -47,6 +84,16 @@ static int crypto_sha1_digest(struct shash_desc *desc,
 	return 0;
 }
 
+static int crypto_sha1_export(struct shash_desc *desc, void *out)
+{
+	return __crypto_sha1_export(SHA1_CTX(desc), out);
+}
+
+static int crypto_sha1_import(struct shash_desc *desc, const void *in)
+{
+	return __crypto_sha1_import(SHA1_CTX(desc), in);
+}
+
 #define HMAC_SHA1_KEY(tfm) ((struct hmac_sha1_key *)crypto_shash_ctx(tfm))
 #define HMAC_SHA1_CTX(desc) ((struct hmac_sha1_ctx *)shash_desc_ctx(desc))
 
@@ -83,6 +130,19 @@ static int crypto_hmac_sha1_digest(struct shash_desc *desc,
 	return 0;
 }
 
+static int crypto_hmac_sha1_export(struct shash_desc *desc, void *out)
+{
+	return __crypto_sha1_export(&HMAC_SHA1_CTX(desc)->sha_ctx, out);
+}
+
+static int crypto_hmac_sha1_import(struct shash_desc *desc, const void *in)
+{
+	struct hmac_sha1_ctx *ctx = HMAC_SHA1_CTX(desc);
+
+	ctx->ostate = HMAC_SHA1_KEY(desc->tfm)->ostate;
+	return __crypto_sha1_import(&ctx->sha_ctx, in);
+}
+
 static struct shash_alg algs[] = {
 	{
 		.base.cra_name		= "sha1",
@@ -95,7 +155,10 @@ static struct shash_alg algs[] = {
 		.update			= crypto_sha1_update,
 		.final			= crypto_sha1_final,
 		.digest			= crypto_sha1_digest,
+		.export			= crypto_sha1_export,
+		.import			= crypto_sha1_import,
 		.descsize		= sizeof(struct sha1_ctx),
+		.statesize		= SHA1_SHASH_STATE_SIZE,
 	},
 	{
 		.base.cra_name		= "hmac(sha1)",
@@ -110,7 +173,10 @@ static struct shash_alg algs[] = {
 		.update			= crypto_hmac_sha1_update,
 		.final			= crypto_hmac_sha1_final,
 		.digest			= crypto_hmac_sha1_digest,
+		.export			= crypto_hmac_sha1_export,
+		.import			= crypto_hmac_sha1_import,
 		.descsize		= sizeof(struct hmac_sha1_ctx),
+		.statesize		= SHA1_SHASH_STATE_SIZE,
 	},
 };