lib/crypto: aesgcm: Use GHASH library API

Make the AES-GCM library use the GHASH library instead of directly
calling gf128mul_lle().  This allows the architecture-optimized GHASH
implementations to be used, or the improved generic implementation if no
architecture-optimized implementation is usable.

Note: this means that <crypto/gcm.h> no longer needs to include
<crypto/gf128mul.h>.  Remove that inclusion, and include
<crypto/gf128mul.h> explicitly from arch/x86/crypto/aesni-intel_glue.c
which previously was relying on the transitive inclusion.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260319061723.1140720-20-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index e6c38d1d8a929ae5243b7b153300b8c6bf41732e..f522fff9231e8e0b8be09482e6bb9d366515d09c 100644 (file)
--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -25,6 +25,7 @@
 #include <crypto/aes.h>
 #include <crypto/b128ops.h>
 #include <crypto/gcm.h>
+#include <crypto/gf128mul.h>
 #include <crypto/xts.h>
 #include <asm/cpu_device_id.h>
 #include <asm/simd.h>

diff --git a/include/crypto/gcm.h b/include/crypto/gcm.h
index b524e47bd4d01a31aa4c09b2960bda10a7c87e5e..1d5f39ff1dc42f203b1ed998b0b192c97a2f32b5 100644 (file)
--- a/include/crypto/gcm.h
+++ b/include/crypto/gcm.h
@@ -4,7 +4,7 @@
 #include <linux/errno.h>
 
 #include <crypto/aes.h>
-#include <crypto/gf128mul.h>
+#include <crypto/gf128hash.h>
 
 #define GCM_AES_IV_SIZE 12
 #define GCM_RFC4106_IV_SIZE 8
@@ -65,7 +65,7 @@ static inline int crypto_ipsec_check_assoclen(unsigned int assoclen)
 }
 
 struct aesgcm_ctx {
-       be128                   ghash_key;
+       struct ghash_key        ghash_key;
        struct aes_enckey       aes_key;
        unsigned int            authsize;
 };

diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index a39e7707e9ee006fd431005e8e0b06d74fe23a6d..32fafe245f47db9f6da2a5bffed76149a4098d21 100644 (file)
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -41,7 +41,7 @@ config CRYPTO_LIB_AES_CBC_MACS
 config CRYPTO_LIB_AESGCM
        tristate
        select CRYPTO_LIB_AES
-       select CRYPTO_LIB_GF128MUL
+       select CRYPTO_LIB_GF128HASH
        select CRYPTO_LIB_UTILS
 
 config CRYPTO_LIB_ARC4

diff --git a/lib/crypto/aesgcm.c b/lib/crypto/aesgcm.c
index 02f5b5f32c764b88dab8abfe52affb920b26ef12..8c7e74d2d1471c16a8dcd71c8ba69d15691fea2f 100644 (file)
--- a/lib/crypto/aesgcm.c
+++ b/lib/crypto/aesgcm.c
@@ -5,9 +5,8 @@
  * Copyright 2022 Google LLC
  */
 
-#include <crypto/algapi.h>
 #include <crypto/gcm.h>
-#include <crypto/ghash.h>
+#include <crypto/utils.h>
 #include <linux/export.h>
 #include <linux/module.h>
 #include <asm/irqflags.h>
@@ -45,7 +44,7 @@ static void aesgcm_encrypt_block(const struct aes_enckey *key, void *dst,
 int aesgcm_expandkey(struct aesgcm_ctx *ctx, const u8 *key,
                     unsigned int keysize, unsigned int authsize)
 {
-       u8 kin[AES_BLOCK_SIZE] = {};
+       u8 h[AES_BLOCK_SIZE] = {};
        int ret;
 
        ret = crypto_gcm_check_authsize(authsize) ?:
@@ -54,24 +53,13 @@ int aesgcm_expandkey(struct aesgcm_ctx *ctx, const u8 *key,
                return ret;
 
        ctx->authsize = authsize;
-       aesgcm_encrypt_block(&ctx->aes_key, &ctx->ghash_key, kin);
-
+       aesgcm_encrypt_block(&ctx->aes_key, h, h);
+       ghash_preparekey(&ctx->ghash_key, h);
+       memzero_explicit(h, sizeof(h));
        return 0;
 }
 EXPORT_SYMBOL(aesgcm_expandkey);
 
-static void aesgcm_ghash(be128 *ghash, const be128 *key, const void *src,
-                        int len)
-{
-       while (len > 0) {
-               crypto_xor((u8 *)ghash, src, min(len, GHASH_BLOCK_SIZE));
-               gf128mul_lle(ghash, key);
-
-               src += GHASH_BLOCK_SIZE;
-               len -= GHASH_BLOCK_SIZE;
-       }
-}
-
 /**
  * aesgcm_mac - Generates the authentication tag using AES-GCM algorithm.
  * @ctx: The data structure that will hold the AES-GCM key schedule
@@ -88,20 +76,33 @@ static void aesgcm_ghash(be128 *ghash, const be128 *key, const void *src,
 static void aesgcm_mac(const struct aesgcm_ctx *ctx, const u8 *src, int src_len,
                       const u8 *assoc, int assoc_len, __be32 *ctr, u8 *authtag)
 {
-       be128 tail = { cpu_to_be64(assoc_len * 8), cpu_to_be64(src_len * 8) };
-       u8 buf[AES_BLOCK_SIZE];
-       be128 ghash = {};
+       static const u8 zeroes[GHASH_BLOCK_SIZE];
+       __be64 tail[2] = {
+               cpu_to_be64((u64)assoc_len * 8),
+               cpu_to_be64((u64)src_len * 8),
+       };
+       struct ghash_ctx ghash;
+       u8 ghash_out[AES_BLOCK_SIZE];
+       u8 enc_ctr[AES_BLOCK_SIZE];
+
+       ghash_init(&ghash, &ctx->ghash_key);
+
+       ghash_update(&ghash, assoc, assoc_len);
+       ghash_update(&ghash, zeroes, -assoc_len & (GHASH_BLOCK_SIZE - 1));
 
-       aesgcm_ghash(&ghash, &ctx->ghash_key, assoc, assoc_len);
-       aesgcm_ghash(&ghash, &ctx->ghash_key, src, src_len);
-       aesgcm_ghash(&ghash, &ctx->ghash_key, &tail, sizeof(tail));
+       ghash_update(&ghash, src, src_len);
+       ghash_update(&ghash, zeroes, -src_len & (GHASH_BLOCK_SIZE - 1));
+
+       ghash_update(&ghash, (const u8 *)&tail, sizeof(tail));
+
+       ghash_final(&ghash, ghash_out);
 
        ctr[3] = cpu_to_be32(1);
-       aesgcm_encrypt_block(&ctx->aes_key, buf, ctr);
-       crypto_xor_cpy(authtag, buf, (u8 *)&ghash, ctx->authsize);
+       aesgcm_encrypt_block(&ctx->aes_key, enc_ctr, ctr);
+       crypto_xor_cpy(authtag, ghash_out, enc_ctr, ctx->authsize);
 
-       memzero_explicit(&ghash, sizeof(ghash));
-       memzero_explicit(buf, sizeof(buf));
+       memzero_explicit(ghash_out, sizeof(ghash_out));
+       memzero_explicit(enc_ctr, sizeof(enc_ctr));
 }
 
 static void aesgcm_crypt(const struct aesgcm_ctx *ctx, u8 *dst, const u8 *src,