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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>
master
Eric Biggers 2026-03-18 23:17:20 -07:00
parent a78ae6e364
commit ea0c746ffa
4 changed files with 32 additions and 30 deletions
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1
arch/x86/crypto/aesni-intel_glue.c
View File

@ -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>

4
include/crypto/gcm.h
View File

@ -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;
};

2
lib/crypto/Kconfig
View File

@ -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

55
lib/crypto/aesgcm.c
View File

@ -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];
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_init(&ghash, &ctx->ghash_key);
ghash_update(&ghash, assoc, assoc_len);
ghash_update(&ghash, zeroes, -assoc_len & (GHASH_BLOCK_SIZE - 1));
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,