Subject: [PATCH 33/36] lib/crypto: aesgcm: Use new AES library API

From: Eric Biggers <[email-masked]>
Date: Sun, 4 Jan 2026 21:13:06 -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: aes_encrypt_new() will be renamed to aes_encrypt() once all
callers of the old aes_encrypt() have been updated.

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..19106fe008fd 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_new(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