Commit d97a9430 authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

crypto: arm/chacha20 - add XChaCha20 support 



Add an XChaCha20 implementation that is hooked up to the ARM NEON
implementation of ChaCha20.  This is needed for use in the Adiantum
encryption mode; see the generic code patch,
"crypto: chacha20-generic - add XChaCha20 support", for more details.

We also update the NEON code to support HChaCha20 on one block, so we
can use that in XChaCha20 rather than calling the generic HChaCha20.
This required factoring the permutation out into its own macro.

Reviewed-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent be2830b1

arch/arm/crypto/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -126,7 +126,7 @@ config CRYPTO_CRC32_ARM_CE 
	select CRYPTO_HASH



config CRYPTO_CHACHA20_NEON

	tristate "NEON accelerated ChaCha20 symmetric cipher"

	tristate "NEON accelerated ChaCha20 stream cipher algorithms"

	depends on KERNEL_MODE_NEON

	select CRYPTO_BLKCIPHER

	select CRYPTO_CHACHA20

arch/arm/crypto/chacha20-neon-core.S

+48 −22
Original line number Diff line number Diff line
@@ -52,27 +52,16 @@ 
	.fpu		neon

	.align		5



ENTRY(chacha20_block_xor_neon)

	// r0: Input state matrix, s

	// r1: 1 data block output, o

	// r2: 1 data block input, i



	//

	// This function encrypts one ChaCha20 block by loading the state matrix

	// in four NEON registers. It performs matrix operation on four words in

	// parallel, but requireds shuffling to rearrange the words after each

	// round.

	//



	// x0..3 = s0..3

	add		ip, r0, #0x20

	vld1.32		{q0-q1}, [r0]

	vld1.32		{q2-q3}, [ip]



	vmov		q8, q0

	vmov		q9, q1

	vmov		q10, q2

	vmov		q11, q3

/*

 * chacha20_permute - permute one block

 *

 * Permute one 64-byte block where the state matrix is stored in the four NEON

 * registers q0-q3.  It performs matrix operations on four words in parallel,

 * but requires shuffling to rearrange the words after each round.

 *

 * Clobbers: r3, ip, q4-q5

 */

chacha20_permute:



	adr		ip, .Lrol8_table

	mov		r3, #10
@@ -142,6 +131,27 @@ ENTRY(chacha20_block_xor_neon) 
	subs		r3, r3, #1

	bne		.Ldoubleround



	bx		lr

ENDPROC(chacha20_permute)



ENTRY(chacha20_block_xor_neon)

	// r0: Input state matrix, s

	// r1: 1 data block output, o

	// r2: 1 data block input, i

	push		{lr}



	// x0..3 = s0..3

	add		ip, r0, #0x20

	vld1.32		{q0-q1}, [r0]

	vld1.32		{q2-q3}, [ip]



	vmov		q8, q0

	vmov		q9, q1

	vmov		q10, q2

	vmov		q11, q3



	bl		chacha20_permute



	add		ip, r2, #0x20

	vld1.8		{q4-q5}, [r2]

	vld1.8		{q6-q7}, [ip]
@@ -166,9 +176,25 @@ ENTRY(chacha20_block_xor_neon) 
	vst1.8		{q0-q1}, [r1]

	vst1.8		{q2-q3}, [ip]



	bx		lr

	pop		{pc}

ENDPROC(chacha20_block_xor_neon)



ENTRY(hchacha20_block_neon)

	// r0: Input state matrix, s

	// r1: output (8 32-bit words)

	push		{lr}



	vld1.32		{q0-q1}, [r0]!

	vld1.32		{q2-q3}, [r0]



	bl		chacha20_permute



	vst1.32		{q0}, [r1]!

	vst1.32		{q3}, [r1]



	pop		{pc}

ENDPROC(hchacha20_block_neon)



	.align		4

.Lctrinc:	.word	0, 1, 2, 3

.Lrol8_table:	.byte	3, 0, 1, 2, 7, 4, 5, 6

arch/arm/crypto/chacha20-neon-glue.c

+77 −26
Original line number Diff line number Diff line 
/*

 * ChaCha20 256-bit cipher algorithm, RFC7539, ARM NEON functions

 * ChaCha20 (RFC7539) and XChaCha20 stream ciphers, NEON accelerated

 *

 * Copyright (C) 2016 Linaro, Ltd. <ard.biesheuvel@linaro.org>

 *
@@ -30,6 +30,7 @@ 


asmlinkage void chacha20_block_xor_neon(u32 *state, u8 *dst, const u8 *src);

asmlinkage void chacha20_4block_xor_neon(u32 *state, u8 *dst, const u8 *src);

asmlinkage void hchacha20_block_neon(const u32 *state, u32 *out);



static void chacha20_doneon(u32 *state, u8 *dst, const u8 *src,

			    unsigned int bytes)
@@ -57,20 +58,16 @@ static void chacha20_doneon(u32 *state, u8 *dst, const u8 *src, 
	}

}



static int chacha20_neon(struct skcipher_request *req)

static int chacha20_neon_stream_xor(struct skcipher_request *req,

				    struct chacha_ctx *ctx, u8 *iv)

{

	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);

	struct skcipher_walk walk;

	u32 state[16];

	int err;



	if (req->cryptlen <= CHACHA_BLOCK_SIZE || !may_use_simd())

		return crypto_chacha_crypt(req);



	err = skcipher_walk_virt(&walk, req, false);



	crypto_chacha_init(state, ctx, walk.iv);

	crypto_chacha_init(state, ctx, iv);



	while (walk.nbytes > 0) {

		unsigned int nbytes = walk.nbytes;
@@ -88,7 +85,41 @@ static int chacha20_neon(struct skcipher_request *req) 
	return err;

}



static struct skcipher_alg alg = {

static int chacha20_neon(struct skcipher_request *req)

{

	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);



	if (req->cryptlen <= CHACHA_BLOCK_SIZE || !may_use_simd())

		return crypto_chacha_crypt(req);



	return chacha20_neon_stream_xor(req, ctx, req->iv);

}



static int xchacha20_neon(struct skcipher_request *req)

{

	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);

	struct chacha_ctx subctx;

	u32 state[16];

	u8 real_iv[16];



	if (req->cryptlen <= CHACHA_BLOCK_SIZE || !may_use_simd())

		return crypto_xchacha_crypt(req);



	crypto_chacha_init(state, ctx, req->iv);



	kernel_neon_begin();

	hchacha20_block_neon(state, subctx.key);

	kernel_neon_end();



	memcpy(&real_iv[0], req->iv + 24, 8);

	memcpy(&real_iv[8], req->iv + 16, 8);

	return chacha20_neon_stream_xor(req, &subctx, real_iv);

}



static struct skcipher_alg algs[] = {

	{

		.base.cra_name		= "chacha20",

		.base.cra_driver_name	= "chacha20-neon",

		.base.cra_priority	= 300,
@@ -104,6 +135,23 @@ static struct skcipher_alg alg = { 
		.setkey			= crypto_chacha20_setkey,

		.encrypt		= chacha20_neon,

		.decrypt		= chacha20_neon,

	}, {

		.base.cra_name		= "xchacha20",

		.base.cra_driver_name	= "xchacha20-neon",

		.base.cra_priority	= 300,

		.base.cra_blocksize	= 1,

		.base.cra_ctxsize	= sizeof(struct chacha_ctx),

		.base.cra_module	= THIS_MODULE,



		.min_keysize		= CHACHA_KEY_SIZE,

		.max_keysize		= CHACHA_KEY_SIZE,

		.ivsize			= XCHACHA_IV_SIZE,

		.chunksize		= CHACHA_BLOCK_SIZE,

		.walksize		= 4 * CHACHA_BLOCK_SIZE,

		.setkey			= crypto_chacha20_setkey,

		.encrypt		= xchacha20_neon,

		.decrypt		= xchacha20_neon,

	}

};



static int __init chacha20_simd_mod_init(void)
@@ -111,12 +159,12 @@ static int __init chacha20_simd_mod_init(void) 
	if (!(elf_hwcap & HWCAP_NEON))

		return -ENODEV;



	return crypto_register_skcipher(&alg);

	return crypto_register_skciphers(algs, ARRAY_SIZE(algs));

}



static void __exit chacha20_simd_mod_fini(void)

{

	crypto_unregister_skcipher(&alg);

	crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));

}



module_init(chacha20_simd_mod_init);
@@ -125,3 +173,6 @@ module_exit(chacha20_simd_mod_fini); 
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");

MODULE_LICENSE("GPL v2");

MODULE_ALIAS_CRYPTO("chacha20");

MODULE_ALIAS_CRYPTO("chacha20-neon");

MODULE_ALIAS_CRYPTO("xchacha20");

MODULE_ALIAS_CRYPTO("xchacha20-neon");

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