Subject: [PATCH v2 33/35] lib/crypto: aesgcm: Use new AES library API

From: Eric Biggers <[email-masked]>
Date: Mon, 12 Jan 2026 11:20:31 -0800

Switch from the old AES library functions (which use struct
crypto_aes_ctx) to the new ones (which use struct aes_enckey).  This
eliminates the unnecessary computation and caching of the decryption
round keys.  The new AES en/decryption functions are also much faster
and use AES instructions when supported by the CPU.

Note that in addition to the change in the key preparation function and
the key struct type itself, the change in the type of the key struct
results in aes_encrypt() (which is temporarily a type-generic macro)
calling the new encryption function rather than the old one.

Acked-by: Ard Biesheuvel <[email-masked]>
Signed-off-by: Eric Biggers <[email-masked]>
---
 include/crypto/gcm.h |  2 +-
 lib/crypto/aesgcm.c  | 12 ++++++------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/crypto/gcm.h b/include/crypto/gcm.h
index fd9df607a836..b524e47bd4d0 100644
--- a/include/crypto/gcm.h
+++ b/include/crypto/gcm.h
@@ -64,11 +64,11 @@ static inline int crypto_ipsec_check_assoclen(unsigned int assoclen)
 	return 0;
 }
 
 struct aesgcm_ctx {
 	be128			ghash_key;
-	struct crypto_aes_ctx	aes_ctx;
+	struct aes_enckey	aes_key;
 	unsigned int		authsize;
 };
 
 int aesgcm_expandkey(struct aesgcm_ctx *ctx, const u8 *key,
 		     unsigned int keysize, unsigned int authsize);
diff --git a/lib/crypto/aesgcm.c b/lib/crypto/aesgcm.c
index ac0b2fcfd606..02f5b5f32c76 100644
--- a/lib/crypto/aesgcm.c
+++ b/lib/crypto/aesgcm.c
@@ -10,11 +10,11 @@
 #include <crypto/ghash.h>
 #include <linux/export.h>
 #include <linux/module.h>
 #include <asm/irqflags.h>
 
-static void aesgcm_encrypt_block(const struct crypto_aes_ctx *ctx, void *dst,
+static void aesgcm_encrypt_block(const struct aes_enckey *key, void *dst,
 				 const void *src)
 {
 	unsigned long flags;
 
 	/*
@@ -24,11 +24,11 @@ static void aesgcm_encrypt_block(const struct crypto_aes_ctx *ctx, void *dst,
 	 * mitigates this risk to some extent by pulling the entire S-box into
 	 * the caches before doing any substitutions, but this strategy is more
 	 * effective when running with interrupts disabled.
 	 */
 	local_irq_save(flags);
-	aes_encrypt(ctx, dst, src);
+	aes_encrypt(key, dst, src);
 	local_irq_restore(flags);
 }
 
 /**
  * aesgcm_expandkey - Expands the AES and GHASH keys for the AES-GCM key
@@ -47,16 +47,16 @@ int aesgcm_expandkey(struct aesgcm_ctx *ctx, const u8 *key,
 {
 	u8 kin[AES_BLOCK_SIZE] = {};
 	int ret;
 
 	ret = crypto_gcm_check_authsize(authsize) ?:
-	      aes_expandkey(&ctx->aes_ctx, key, keysize);
+	      aes_prepareenckey(&ctx->aes_key, key, keysize);
 	if (ret)
 		return ret;
 
 	ctx->authsize = authsize;
-	aesgcm_encrypt_block(&ctx->aes_ctx, &ctx->ghash_key, kin);
+	aesgcm_encrypt_block(&ctx->aes_key, &ctx->ghash_key, kin);
 
 	return 0;
 }
 EXPORT_SYMBOL(aesgcm_expandkey);
 
@@ -95,11 +95,11 @@ static void aesgcm_mac(const struct aesgcm_ctx *ctx, const u8 *src, int src_len,
 	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));
 
 	ctr[3] = cpu_to_be32(1);
-	aesgcm_encrypt_block(&ctx->aes_ctx, buf, ctr);
+	aesgcm_encrypt_block(&ctx->aes_key, buf, ctr);
 	crypto_xor_cpy(authtag, buf, (u8 *)&ghash, ctx->authsize);
 
 	memzero_explicit(&ghash, sizeof(ghash));
 	memzero_explicit(buf, sizeof(buf));
 }
@@ -117,11 +117,11 @@ static void aesgcm_crypt(const struct aesgcm_ctx *ctx, u8 *dst, const u8 *src,
 		 * inadvertent IV reuse, which must be avoided at all cost for
 		 * stream ciphers such as AES-CTR. Given the range of 'int
 		 * len', this cannot happen, so no explicit test is necessary.
 		 */
 		ctr[3] = cpu_to_be32(n++);
-		aesgcm_encrypt_block(&ctx->aes_ctx, buf, ctr);
+		aesgcm_encrypt_block(&ctx->aes_key, buf, ctr);
 		crypto_xor_cpy(dst, src, buf, min(len, AES_BLOCK_SIZE));
 
 		dst += AES_BLOCK_SIZE;
 		src += AES_BLOCK_SIZE;
 		len -= AES_BLOCK_SIZE;
-- 
2.52.0