arch/arm64/crypto/aes-ce-ccm-glue.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * aes-ce-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
  *
  * Copyright (C) 2013 - 2017 Linaro Ltd.
  * Copyright (C) 2024 Google LLC
  *
  * Author: Ard Biesheuvel <ardb@kernel.org>
  */

 #include <asm/neon.h>
 #include <linux/unaligned.h>
 #include <crypto/aes.h>
 #include <crypto/scatterwalk.h>
 #include <crypto/internal/aead.h>
 #include <crypto/internal/skcipher.h>
 #include <linux/module.h>

 #include "aes-ce-setkey.h"

 MODULE_IMPORT_NS(CRYPTO_INTERNAL);

 static int num_rounds(struct crypto_aes_ctx *ctx)
 {
 	/*
 	 * # of rounds specified by AES:
 	 * 128 bit key		10 rounds
 	 * 192 bit key		12 rounds
 	 * 256 bit key		14 rounds
 	 * => n byte key	=> 6 + (n/4) rounds
 	 */
 	return 6 + ctx->key_length / 4;
 }

 asmlinkage u32 ce_aes_mac_update(u8 const in[], u32 const rk[], int rounds,
 				 int blocks, u8 dg[], int enc_before,
 				 int enc_after);

 asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
 				   u32 const rk[], u32 rounds, u8 mac[],
 				   u8 ctr[], u8 const final_iv[]);

 asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
 				   u32 const rk[], u32 rounds, u8 mac[],
 				   u8 ctr[], u8 const final_iv[]);

 static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
 		      unsigned int key_len)
 {
 	struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);

 	return ce_aes_expandkey(ctx, in_key, key_len);
 }

 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
 {
 	if ((authsize & 1) || authsize < 4)
 		return -EINVAL;
 	return 0;
 }

 static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
 {
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
 	__be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
 	u32 l = req->iv[0] + 1;

 	/* verify that CCM dimension 'L' is set correctly in the IV */
 	if (l < 2 || l > 8)
 		return -EINVAL;

 	/* verify that msglen can in fact be represented in L bytes */
 	if (l < 4 && msglen >> (8 * l))
 		return -EOVERFLOW;

 	/*
 	 * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
 	 * uses a u32 type to represent msglen so the top 4 bytes are always 0.
 	 */
 	n[0] = 0;
 	n[1] = cpu_to_be32(msglen);

 	memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);

 	/*
 	 * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
 	 * - bits 0..2	: max # of bytes required to represent msglen, minus 1
 	 *                (already set by caller)
 	 * - bits 3..5	: size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
 	 * - bit 6	: indicates presence of authenticate-only data
 	 */
 	maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
 	if (req->assoclen)
 		maciv[0] |= 0x40;

 	memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
 	return 0;
 }

 static u32 ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
 				u32 macp, u32 const rk[], u32 rounds)
 {
 	int enc_after = (macp + abytes) % AES_BLOCK_SIZE;

 	do {
 		u32 blocks = abytes / AES_BLOCK_SIZE;

 		if (macp == AES_BLOCK_SIZE || (!macp && blocks > 0)) {
 			u32 rem = ce_aes_mac_update(in, rk, rounds, blocks, mac,
 						    macp, enc_after);
 			u32 adv = (blocks - rem) * AES_BLOCK_SIZE;

 			macp = enc_after ? 0 : AES_BLOCK_SIZE;
 			in += adv;
 			abytes -= adv;

 			if (unlikely(rem)) {
 				kernel_neon_end();
 				kernel_neon_begin();
 				macp = 0;
 			}
 		} else {
 			u32 l = min(AES_BLOCK_SIZE - macp, abytes);

 			crypto_xor(&mac[macp], in, l);
 			in += l;
 			macp += l;
 			abytes -= l;
 		}
 	} while (abytes > 0);

 	return macp;
 }

 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
 {
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
 	struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 	struct __packed { __be16 l; __be32 h; u16 len; } ltag;
 	struct scatter_walk walk;
 	u32 len = req->assoclen;
 	u32 macp = AES_BLOCK_SIZE;

 	/* prepend the AAD with a length tag */
 	if (len < 0xff00) {
 		ltag.l = cpu_to_be16(len);
 		ltag.len = 2;
 	} else  {
 		ltag.l = cpu_to_be16(0xfffe);
 		put_unaligned_be32(len, &ltag.h);
 		ltag.len = 6;
 	}

 	macp = ce_aes_ccm_auth_data(mac, (u8 *)&ltag, ltag.len, macp,
 				    ctx->key_enc, num_rounds(ctx));
 	scatterwalk_start(&walk, req->src);

 	do {
 		u32 n = scatterwalk_clamp(&walk, len);
 		u8 *p;

 		if (!n) {
 			scatterwalk_start(&walk, sg_next(walk.sg));
 			n = scatterwalk_clamp(&walk, len);
 		}
 		p = scatterwalk_map(&walk);

 		macp = ce_aes_ccm_auth_data(mac, p, n, macp, ctx->key_enc,
 					    num_rounds(ctx));

 		len -= n;

 		scatterwalk_unmap(p);
 		scatterwalk_advance(&walk, n);
 		scatterwalk_done(&walk, 0, len);
 	} while (len);
 }

 static int ccm_encrypt(struct aead_request *req)
 {
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
 	struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 	struct skcipher_walk walk;
 	u8 __aligned(8) mac[AES_BLOCK_SIZE];
 	u8 orig_iv[AES_BLOCK_SIZE];
 	u32 len = req->cryptlen;
 	int err;

 	err = ccm_init_mac(req, mac, len);
 	if (err)
 		return err;

 	/* preserve the original iv for the final round */
 	memcpy(orig_iv, req->iv, AES_BLOCK_SIZE);

 	err = skcipher_walk_aead_encrypt(&walk, req, false);
 	if (unlikely(err))
 		return err;

 	kernel_neon_begin();

 	if (req->assoclen)
 		ccm_calculate_auth_mac(req, mac);

 	do {
 		u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 		const u8 *src = walk.src.virt.addr;
 		u8 *dst = walk.dst.virt.addr;
 		u8 buf[AES_BLOCK_SIZE];
 		u8 *final_iv = NULL;

 		if (walk.nbytes == walk.total) {
 			tail = 0;
 			final_iv = orig_iv;
 		}

 		if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
 			src = dst = memcpy(&buf[sizeof(buf) - walk.nbytes],
 					   src, walk.nbytes);

 		ce_aes_ccm_encrypt(dst, src, walk.nbytes - tail,
 				   ctx->key_enc, num_rounds(ctx),
 				   mac, walk.iv, final_iv);

 		if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
 			memcpy(walk.dst.virt.addr, dst, walk.nbytes);

 		if (walk.nbytes) {
 			err = skcipher_walk_done(&walk, tail);
 		}
 	} while (walk.nbytes);

 	kernel_neon_end();

 	if (unlikely(err))
 		return err;

 	/* copy authtag to end of dst */
 	scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
 				 crypto_aead_authsize(aead), 1);

 	return 0;
 }

 static int ccm_decrypt(struct aead_request *req)
 {
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
 	struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 	unsigned int authsize = crypto_aead_authsize(aead);
 	struct skcipher_walk walk;
 	u8 __aligned(8) mac[AES_BLOCK_SIZE];
 	u8 orig_iv[AES_BLOCK_SIZE];
 	u32 len = req->cryptlen - authsize;
 	int err;

 	err = ccm_init_mac(req, mac, len);
 	if (err)
 		return err;

 	/* preserve the original iv for the final round */
 	memcpy(orig_iv, req->iv, AES_BLOCK_SIZE);

 	err = skcipher_walk_aead_decrypt(&walk, req, false);
 	if (unlikely(err))
 		return err;

 	kernel_neon_begin();

 	if (req->assoclen)
 		ccm_calculate_auth_mac(req, mac);

 	do {
 		u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 		const u8 *src = walk.src.virt.addr;
 		u8 *dst = walk.dst.virt.addr;
 		u8 buf[AES_BLOCK_SIZE];
 		u8 *final_iv = NULL;

 		if (walk.nbytes == walk.total) {
 			tail = 0;
 			final_iv = orig_iv;
 		}

 		if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
 			src = dst = memcpy(&buf[sizeof(buf) - walk.nbytes],
 					   src, walk.nbytes);

 		ce_aes_ccm_decrypt(dst, src, walk.nbytes - tail,
 				   ctx->key_enc, num_rounds(ctx),
 				   mac, walk.iv, final_iv);

 		if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
 			memcpy(walk.dst.virt.addr, dst, walk.nbytes);

 		if (walk.nbytes) {
 			err = skcipher_walk_done(&walk, tail);
 		}
 	} while (walk.nbytes);

 	kernel_neon_end();

 	if (unlikely(err))
 		return err;

 	/* compare calculated auth tag with the stored one */
 	scatterwalk_map_and_copy(orig_iv, req->src,
 				 req->assoclen + req->cryptlen - authsize,
 				 authsize, 0);

 	if (crypto_memneq(mac, orig_iv, authsize))
 		return -EBADMSG;
 	return 0;
 }

 static struct aead_alg ccm_aes_alg = {
 	.base = {
 		.cra_name		= "ccm(aes)",
 		.cra_driver_name	= "ccm-aes-ce",
 		.cra_priority		= 300,
 		.cra_blocksize		= 1,
 		.cra_ctxsize		= sizeof(struct crypto_aes_ctx),
 		.cra_module		= THIS_MODULE,
 	},
 	.ivsize		= AES_BLOCK_SIZE,
 	.chunksize	= AES_BLOCK_SIZE,
 	.maxauthsize	= AES_BLOCK_SIZE,
 	.setkey		= ccm_setkey,
 	.setauthsize	= ccm_setauthsize,
 	.encrypt	= ccm_encrypt,
 	.decrypt	= ccm_decrypt,
 };

 static int __init aes_mod_init(void)
 {
 	if (!cpu_have_named_feature(AES))
 		return -ENODEV;
 	return crypto_register_aead(&ccm_aes_alg);
 }

 static void __exit aes_mod_exit(void)
 {
 	crypto_unregister_aead(&ccm_aes_alg);
 }

 module_init(aes_mod_init);
 module_exit(aes_mod_exit);

 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
 MODULE_AUTHOR("Ard Biesheuvel <ardb@kernel.org>");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS_CRYPTO("ccm(aes)");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* aes-ce-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
	*
	* Copyright (C) 2013 - 2017 Linaro Ltd.
	* Copyright (C) 2024 Google LLC
	*
	* Author: Ard Biesheuvel <ardb@kernel.org>
	*/

	#include <asm/neon.h>
	#include <linux/unaligned.h>
	#include <crypto/aes.h>
	#include <crypto/scatterwalk.h>
	#include <crypto/internal/aead.h>
	#include <crypto/internal/skcipher.h>
	#include <linux/module.h>

	#include "aes-ce-setkey.h"

	MODULE_IMPORT_NS(CRYPTO_INTERNAL);

	static int num_rounds(struct crypto_aes_ctx *ctx)
	{
	/*
	* # of rounds specified by AES:
	* 128 bit key 10 rounds
	* 192 bit key 12 rounds
	* 256 bit key 14 rounds
	* => n byte key => 6 + (n/4) rounds
	*/
	return 6 + ctx->key_length / 4;
	}

	asmlinkage u32 ce_aes_mac_update(u8 const in[], u32 const rk[], int rounds,
	int blocks, u8 dg[], int enc_before,
	int enc_after);

	asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
	u32 const rk[], u32 rounds, u8 mac[],
	u8 ctr[], u8 const final_iv[]);

	asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
	u32 const rk[], u32 rounds, u8 mac[],
	u8 ctr[], u8 const final_iv[]);

	static int ccm_setkey(struct crypto_aead tfm, const u8 in_key,
	unsigned int key_len)
	{
	struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);

	return ce_aes_expandkey(ctx, in_key, key_len);
	}

	static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
	{
	if ((authsize & 1) \|\| authsize < 4)
	return -EINVAL;
	return 0;
	}

	static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
	{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	__be32 n = (__be32 )&maciv[AES_BLOCK_SIZE - 8];
	u32 l = req->iv[0] + 1;

	/* verify that CCM dimension 'L' is set correctly in the IV */
	if (l < 2 \|\| l > 8)
	return -EINVAL;

	/* verify that msglen can in fact be represented in L bytes */
	if (l < 4 && msglen >> (8 * l))
	return -EOVERFLOW;

	/*
	* Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
	* uses a u32 type to represent msglen so the top 4 bytes are always 0.
	*/
	n[0] = 0;
	n[1] = cpu_to_be32(msglen);

	memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);

	/*
	* Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
	* - bits 0..2 : max # of bytes required to represent msglen, minus 1
	* (already set by caller)
	* - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
	* - bit 6 : indicates presence of authenticate-only data
	*/
	maciv[0] \|= (crypto_aead_authsize(aead) - 2) << 2;
	if (req->assoclen)
	maciv[0] \|= 0x40;

	memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
	return 0;
	}

	static u32 ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
	u32 macp, u32 const rk[], u32 rounds)
	{
	int enc_after = (macp + abytes) % AES_BLOCK_SIZE;

	do {
	u32 blocks = abytes / AES_BLOCK_SIZE;

	if (macp == AES_BLOCK_SIZE \|\| (!macp && blocks > 0)) {
	u32 rem = ce_aes_mac_update(in, rk, rounds, blocks, mac,
	macp, enc_after);
	u32 adv = (blocks - rem) * AES_BLOCK_SIZE;

	macp = enc_after ? 0 : AES_BLOCK_SIZE;
	in += adv;
	abytes -= adv;

	if (unlikely(rem)) {
	kernel_neon_end();
	kernel_neon_begin();
	macp = 0;
	}
	} else {
	u32 l = min(AES_BLOCK_SIZE - macp, abytes);

	crypto_xor(&mac[macp], in, l);
	in += l;
	macp += l;
	abytes -= l;
	}
	} while (abytes > 0);

	return macp;
	}

	static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
	{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
	struct __packed { __be16 l; __be32 h; u16 len; } ltag;
	struct scatter_walk walk;
	u32 len = req->assoclen;
	u32 macp = AES_BLOCK_SIZE;

	/* prepend the AAD with a length tag */
	if (len < 0xff00) {
	ltag.l = cpu_to_be16(len);
	ltag.len = 2;
	} else {
	ltag.l = cpu_to_be16(0xfffe);
	put_unaligned_be32(len, &ltag.h);
	ltag.len = 6;
	}

	macp = ce_aes_ccm_auth_data(mac, (u8 *)&ltag, ltag.len, macp,
	ctx->key_enc, num_rounds(ctx));
	scatterwalk_start(&walk, req->src);

	do {
	u32 n = scatterwalk_clamp(&walk, len);
	u8 *p;

	if (!n) {
	scatterwalk_start(&walk, sg_next(walk.sg));
	n = scatterwalk_clamp(&walk, len);
	}
	p = scatterwalk_map(&walk);

	macp = ce_aes_ccm_auth_data(mac, p, n, macp, ctx->key_enc,
	num_rounds(ctx));

	len -= n;

	scatterwalk_unmap(p);
	scatterwalk_advance(&walk, n);
	scatterwalk_done(&walk, 0, len);
	} while (len);
	}

	static int ccm_encrypt(struct aead_request *req)
	{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
	struct skcipher_walk walk;
	u8 __aligned(8) mac[AES_BLOCK_SIZE];
	u8 orig_iv[AES_BLOCK_SIZE];
	u32 len = req->cryptlen;
	int err;

	err = ccm_init_mac(req, mac, len);
	if (err)
	return err;

	/* preserve the original iv for the final round */
	memcpy(orig_iv, req->iv, AES_BLOCK_SIZE);

	err = skcipher_walk_aead_encrypt(&walk, req, false);
	if (unlikely(err))
	return err;

	kernel_neon_begin();

	if (req->assoclen)
	ccm_calculate_auth_mac(req, mac);

	do {
	u32 tail = walk.nbytes % AES_BLOCK_SIZE;
	const u8 *src = walk.src.virt.addr;
	u8 *dst = walk.dst.virt.addr;
	u8 buf[AES_BLOCK_SIZE];
	u8 *final_iv = NULL;

	if (walk.nbytes == walk.total) {
	tail = 0;
	final_iv = orig_iv;
	}

	if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
	src = dst = memcpy(&buf[sizeof(buf) - walk.nbytes],
	src, walk.nbytes);

	ce_aes_ccm_encrypt(dst, src, walk.nbytes - tail,
	ctx->key_enc, num_rounds(ctx),
	mac, walk.iv, final_iv);

	if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
	memcpy(walk.dst.virt.addr, dst, walk.nbytes);

	if (walk.nbytes) {
	err = skcipher_walk_done(&walk, tail);
	}
	} while (walk.nbytes);

	kernel_neon_end();

	if (unlikely(err))
	return err;

	/* copy authtag to end of dst */
	scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
	crypto_aead_authsize(aead), 1);

	return 0;
	}

	static int ccm_decrypt(struct aead_request *req)
	{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
	unsigned int authsize = crypto_aead_authsize(aead);
	struct skcipher_walk walk;
	u8 __aligned(8) mac[AES_BLOCK_SIZE];
	u8 orig_iv[AES_BLOCK_SIZE];
	u32 len = req->cryptlen - authsize;
	int err;

	err = ccm_init_mac(req, mac, len);
	if (err)
	return err;

	/* preserve the original iv for the final round */
	memcpy(orig_iv, req->iv, AES_BLOCK_SIZE);

	err = skcipher_walk_aead_decrypt(&walk, req, false);
	if (unlikely(err))
	return err;

	kernel_neon_begin();

	if (req->assoclen)
	ccm_calculate_auth_mac(req, mac);

	do {
	u32 tail = walk.nbytes % AES_BLOCK_SIZE;
	const u8 *src = walk.src.virt.addr;
	u8 *dst = walk.dst.virt.addr;
	u8 buf[AES_BLOCK_SIZE];
	u8 *final_iv = NULL;

	if (walk.nbytes == walk.total) {
	tail = 0;
	final_iv = orig_iv;
	}

	if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
	src = dst = memcpy(&buf[sizeof(buf) - walk.nbytes],
	src, walk.nbytes);

	ce_aes_ccm_decrypt(dst, src, walk.nbytes - tail,
	ctx->key_enc, num_rounds(ctx),
	mac, walk.iv, final_iv);

	if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
	memcpy(walk.dst.virt.addr, dst, walk.nbytes);

	if (walk.nbytes) {
	err = skcipher_walk_done(&walk, tail);
	}
	} while (walk.nbytes);

	kernel_neon_end();

	if (unlikely(err))
	return err;

	/* compare calculated auth tag with the stored one */
	scatterwalk_map_and_copy(orig_iv, req->src,
	req->assoclen + req->cryptlen - authsize,
	authsize, 0);

	if (crypto_memneq(mac, orig_iv, authsize))
	return -EBADMSG;
	return 0;
	}

	static struct aead_alg ccm_aes_alg = {
	.base = {
	.cra_name = "ccm(aes)",
	.cra_driver_name = "ccm-aes-ce",
	.cra_priority = 300,
	.cra_blocksize = 1,
	.cra_ctxsize = sizeof(struct crypto_aes_ctx),
	.cra_module = THIS_MODULE,
	},
	.ivsize = AES_BLOCK_SIZE,
	.chunksize = AES_BLOCK_SIZE,
	.maxauthsize = AES_BLOCK_SIZE,
	.setkey = ccm_setkey,
	.setauthsize = ccm_setauthsize,
	.encrypt = ccm_encrypt,
	.decrypt = ccm_decrypt,
	};

	static int __init aes_mod_init(void)
	{
	if (!cpu_have_named_feature(AES))
	return -ENODEV;
	return crypto_register_aead(&ccm_aes_alg);
	}

	static void __exit aes_mod_exit(void)
	{
	crypto_unregister_aead(&ccm_aes_alg);
	}

	module_init(aes_mod_init);
	module_exit(aes_mod_exit);

	MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
	MODULE_AUTHOR("Ard Biesheuvel <ardb@kernel.org>");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS_CRYPTO("ccm(aes)");