[PATCH v3 15/29] crypto: x86/poly1305 - depend on generic library not generic shash

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

Remove the dependency on the generic Poly1305 driver. Instead, depend
on the generic library so that we only reuse code without pulling in
the generic skcipher implementation as well.

Since this removes the last remaining user of the routines exported
by the generic shash driver, unexport them and make them static.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 arch/x86/crypto/poly1305_glue.c    | 67 ++++++++++++++++----
 crypto/Kconfig                     |  2 +-
 crypto/poly1305_generic.c          | 11 ++--
 include/crypto/internal/poly1305.h |  7 --
 4 files changed, 61 insertions(+), 26 deletions(-)

diff --git a/arch/x86/crypto/poly1305_glue.c b/arch/x86/crypto/poly1305_glue.c
index b43b93c95e79..19d94b63be26 100644
--- a/arch/x86/crypto/poly1305_glue.c
+++ b/arch/x86/crypto/poly1305_glue.c
@@ -34,6 +34,24 @@ static void poly1305_simd_mult(u32 *a, const u32 *b)
 	poly1305_block_sse2(a, m, b, 1);
 }
 
+static unsigned int poly1305_scalar_blocks(struct poly1305_desc_ctx *dctx,
+					   const u8 *src, unsigned int srclen)
+{
+	unsigned int datalen;
+
+	if (unlikely(!dctx->sset)) {
+		datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
+		src += srclen - datalen;
+		srclen = datalen;
+	}
+	if (srclen >= POLY1305_BLOCK_SIZE) {
+		poly1305_core_blocks(&dctx->h, dctx->r, src,
+				     srclen / POLY1305_BLOCK_SIZE, 1);
+		srclen %= POLY1305_BLOCK_SIZE;
+	}
+	return srclen;
+}
+
 static unsigned int poly1305_simd_blocks(struct poly1305_desc_ctx *dctx,
 					 const u8 *src, unsigned int srclen)
 {
@@ -89,14 +107,9 @@ static int poly1305_simd_update(struct shash_desc *desc,
 				const u8 *src, unsigned int srclen)
 {
 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
+	bool do_simd = (srclen > 288) && crypto_simd_usable();
 	unsigned int bytes;
 
-	/* kernel_fpu_begin/end is costly, use fallback for small updates */
-	if (srclen <= 288 || !crypto_simd_usable())
-		return crypto_poly1305_update(desc, src, srclen);
-
-	kernel_fpu_begin();
-
 	if (unlikely(dctx->buflen)) {
 		bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
 		memcpy(dctx->buf + dctx->buflen, src, bytes);
@@ -105,25 +118,57 @@ static int poly1305_simd_update(struct shash_desc *desc,
 		dctx->buflen += bytes;
 
 		if (dctx->buflen == POLY1305_BLOCK_SIZE) {
-			poly1305_simd_blocks(dctx, dctx->buf,
-					     POLY1305_BLOCK_SIZE);
+			if (likely(do_simd)) {
+				kernel_fpu_begin();
+				poly1305_simd_blocks(dctx, dctx->buf,
+						     POLY1305_BLOCK_SIZE);
+				kernel_fpu_end();
+			} else {
+				poly1305_scalar_blocks(dctx, dctx->buf,
+						       POLY1305_BLOCK_SIZE);
+			}
 			dctx->buflen = 0;
 		}
 	}
 
 	if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
-		bytes = poly1305_simd_blocks(dctx, src, srclen);
+		if (likely(do_simd)) {
+			kernel_fpu_begin();
+			bytes = poly1305_simd_blocks(dctx, src, srclen);
+			kernel_fpu_end();
+		} else {
+			bytes = poly1305_scalar_blocks(dctx, src, srclen);
+		}
 		src += srclen - bytes;
 		srclen = bytes;
 	}
 
-	kernel_fpu_end();
-
 	if (unlikely(srclen)) {
 		dctx->buflen = srclen;
 		memcpy(dctx->buf, src, srclen);
 	}
+}
+
+static int crypto_poly1305_init(struct shash_desc *desc)
+{
+	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
+
+	poly1305_core_init(&dctx->h);
+	dctx->buflen = 0;
+	dctx->rset = 0;
+	dctx->sset = false;
+
+	return 0;
+}
+
+static int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
+{
+	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
+
+	if (unlikely(!dctx->sset))
+		return -ENOKEY;
 
+	poly1305_final_generic(dctx, dst);
 	return 0;
 }
 
diff --git a/crypto/Kconfig b/crypto/Kconfig
index ead0c3d15823..ae31f8730858 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -710,7 +710,7 @@ config CRYPTO_POLY1305
 config CRYPTO_POLY1305_X86_64
 	tristate "Poly1305 authenticator algorithm (x86_64/SSE2/AVX2)"
 	depends on X86 && 64BIT
-	select CRYPTO_POLY1305
+	select CRYPTO_LIB_POLY1305_GENERIC
 	help
 	  Poly1305 authenticator algorithm, RFC7539.
 
diff --git a/crypto/poly1305_generic.c b/crypto/poly1305_generic.c
index afe9a9e576dd..21edbd8c99fb 100644
--- a/crypto/poly1305_generic.c
+++ b/crypto/poly1305_generic.c
@@ -19,7 +19,7 @@
 #include <linux/module.h>
 #include <asm/unaligned.h>
 
-int crypto_poly1305_init(struct shash_desc *desc)
+static int crypto_poly1305_init(struct shash_desc *desc)
 {
 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
 
@@ -30,7 +30,6 @@ int crypto_poly1305_init(struct shash_desc *desc)
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(crypto_poly1305_init);
 
 static void poly1305_blocks(struct poly1305_desc_ctx *dctx, const u8 *src,
 			    unsigned int srclen)
@@ -47,8 +46,8 @@ static void poly1305_blocks(struct poly1305_desc_ctx *dctx, const u8 *src,
 			     srclen / POLY1305_BLOCK_SIZE, 1);
 }
 
-int crypto_poly1305_update(struct shash_desc *desc,
-			   const u8 *src, unsigned int srclen)
+static int crypto_poly1305_update(struct shash_desc *desc,
+				  const u8 *src, unsigned int srclen)
 {
 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
 	unsigned int bytes;
@@ -80,9 +79,8 @@ int crypto_poly1305_update(struct shash_desc *desc,
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(crypto_poly1305_update);
 
-int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
+static int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
 {
 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
 
@@ -92,7 +90,6 @@ int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
 	poly1305_final_generic(dctx, dst);
 	return 0;
 }
-EXPORT_SYMBOL_GPL(crypto_poly1305_final);
 
 static struct shash_alg poly1305_alg = {
 	.digestsize	= POLY1305_DIGEST_SIZE,
diff --git a/include/crypto/internal/poly1305.h b/include/crypto/internal/poly1305.h
index 68269f0d0062..50067536def9 100644
--- a/include/crypto/internal/poly1305.h
+++ b/include/crypto/internal/poly1305.h
@@ -35,13 +35,6 @@ void poly1305_update_generic(struct poly1305_desc_ctx *desc, const u8 *src,
 
 void poly1305_final_generic(struct poly1305_desc_ctx *desc, u8 *digest);
 
-/* Crypto API helper functions for the Poly1305 MAC */
-int crypto_poly1305_init(struct shash_desc *desc);
-
-int crypto_poly1305_update(struct shash_desc *desc,
-			   const u8 *src, unsigned int srclen);
-int crypto_poly1305_final(struct shash_desc *desc, u8 *dst);
-
 /*
  * Poly1305 requires a unique key for each tag, which implies that we can't set
  * it on the tfm that gets accessed by multiple users simultaneously. Instead we
-- 
2.20.1