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Commit 4af78261 authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

crypto: x86/chacha20 - add XChaCha20 support 



Add an XChaCha20 implementation that is hooked up to the x86_64 SIMD
implementations of ChaCha20.  This can be used by Adiantum.

An SSSE3 implementation of single-block HChaCha20 is also added so that
XChaCha20 can use it rather than the generic implementation.  This
required refactoring the ChaCha permutation into its own function.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 0f961f9f

arch/x86/crypto/chacha20-ssse3-x86_64.S

+56 −25
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
 */



#include <linux/linkage.h>

#include <asm/frame.h>



.section	.rodata.cst16.ROT8, "aM", @progbits, 16

.align 16
@@ -23,37 +24,24 @@ CTRINC: .octa 0x00000003000000020000000100000000 


.text



ENTRY(chacha20_block_xor_ssse3)

	# %rdi: Input state matrix, s

	# %rsi: up to 1 data block output, o

	# %rdx: up to 1 data block input, i

	# %rcx: input/output length in bytes



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

	# in four SSE registers. It performs matrix operation on four words in

	# parallel, but requires shuffling to rearrange the words after each

	# round. 8/16-bit word rotation is done with the slightly better

	# performing SSSE3 byte shuffling, 7/12-bit word rotation uses

	# traditional shift+OR.



	# x0..3 = s0..3

	movdqa		0x00(%rdi),%xmm0

	movdqa		0x10(%rdi),%xmm1

	movdqa		0x20(%rdi),%xmm2

	movdqa		0x30(%rdi),%xmm3

	movdqa		%xmm0,%xmm8

	movdqa		%xmm1,%xmm9

	movdqa		%xmm2,%xmm10

	movdqa		%xmm3,%xmm11

/*

 * chacha20_permute - permute one block

 *

 * Permute one 64-byte block where the state matrix is in %xmm0-%xmm3.  This

 * function performs matrix operations on four words in parallel, but requires

 * shuffling to rearrange the words after each round.  8/16-bit word rotation is

 * done with the slightly better performing SSSE3 byte shuffling, 7/12-bit word

 * rotation uses traditional shift+OR.

 *

 * Clobbers: %ecx, %xmm4-%xmm7

 */

chacha20_permute:



	movdqa		ROT8(%rip),%xmm4

	movdqa		ROT16(%rip),%xmm5



	mov		%rcx,%rax

	mov		$10,%ecx



.Ldoubleround:



	# x0 += x1, x3 = rotl32(x3 ^ x0, 16)

	paddd		%xmm1,%xmm0

	pxor		%xmm0,%xmm3
@@ -123,6 +111,29 @@ ENTRY(chacha20_block_xor_ssse3) 
	dec		%ecx

	jnz		.Ldoubleround



	ret

ENDPROC(chacha20_permute)



ENTRY(chacha20_block_xor_ssse3)

	# %rdi: Input state matrix, s

	# %rsi: up to 1 data block output, o

	# %rdx: up to 1 data block input, i

	# %rcx: input/output length in bytes

	FRAME_BEGIN



	# x0..3 = s0..3

	movdqa		0x00(%rdi),%xmm0

	movdqa		0x10(%rdi),%xmm1

	movdqa		0x20(%rdi),%xmm2

	movdqa		0x30(%rdi),%xmm3

	movdqa		%xmm0,%xmm8

	movdqa		%xmm1,%xmm9

	movdqa		%xmm2,%xmm10

	movdqa		%xmm3,%xmm11



	mov		%rcx,%rax

	call		chacha20_permute



	# o0 = i0 ^ (x0 + s0)

	paddd		%xmm8,%xmm0

	cmp		$0x10,%rax
@@ -156,6 +167,7 @@ ENTRY(chacha20_block_xor_ssse3) 
	movdqu		%xmm0,0x30(%rsi)



.Ldone:

	FRAME_END

	ret



.Lxorpart:
@@ -189,6 +201,25 @@ ENTRY(chacha20_block_xor_ssse3) 


ENDPROC(chacha20_block_xor_ssse3)



ENTRY(hchacha20_block_ssse3)

	# %rdi: Input state matrix, s

	# %rsi: output (8 32-bit words)

	FRAME_BEGIN



	movdqa		0x00(%rdi),%xmm0

	movdqa		0x10(%rdi),%xmm1

	movdqa		0x20(%rdi),%xmm2

	movdqa		0x30(%rdi),%xmm3



	call		chacha20_permute



	movdqu		%xmm0,0x00(%rsi)

	movdqu		%xmm3,0x10(%rsi)



	FRAME_END

	ret

ENDPROC(hchacha20_block_ssse3)



ENTRY(chacha20_4block_xor_ssse3)

	# %rdi: Input state matrix, s

	# %rsi: up to 4 data blocks output, o

arch/x86/crypto/chacha20_glue.c

+82 −26
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ asmlinkage void chacha20_block_xor_ssse3(u32 *state, u8 *dst, const u8 *src, 
					 unsigned int len);

asmlinkage void chacha20_4block_xor_ssse3(u32 *state, u8 *dst, const u8 *src,

					  unsigned int len);

asmlinkage void hchacha20_block_ssse3(const u32 *state, u32 *out);

#ifdef CONFIG_AS_AVX2

asmlinkage void chacha20_2block_xor_avx2(u32 *state, u8 *dst, const u8 *src,

					 unsigned int len);
@@ -121,10 +122,9 @@ static void chacha20_dosimd(u32 *state, u8 *dst, const u8 *src, 
	}

}



static int chacha20_simd(struct skcipher_request *req)

static int chacha20_simd_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);

	u32 *state, state_buf[16 + 2] __aligned(8);

	struct skcipher_walk walk;

	int err;
@@ -132,14 +132,9 @@ static int chacha20_simd(struct skcipher_request *req) 
	BUILD_BUG_ON(CHACHA20_STATE_ALIGN != 16);

	state = PTR_ALIGN(state_buf + 0, CHACHA20_STATE_ALIGN);



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

		return crypto_chacha_crypt(req);



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



	crypto_chacha_init(state, ctx, walk.iv);



	kernel_fpu_begin();

	crypto_chacha_init(state, ctx, iv);



	while (walk.nbytes > 0) {

		unsigned int nbytes = walk.nbytes;
@@ -153,12 +148,55 @@ static int chacha20_simd(struct skcipher_request *req) 
		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);

	}



	return err;

}



static int chacha20_simd(struct skcipher_request *req)

{

	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);

	int err;



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

		return crypto_chacha_crypt(req);



	kernel_fpu_begin();

	err = chacha20_simd_stream_xor(req, ctx, req->iv);

	kernel_fpu_end();

	return err;

}



static int xchacha20_simd(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, state_buf[16 + 2] __aligned(8);

	u8 real_iv[16];

	int err;



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

		return crypto_xchacha_crypt(req);



	BUILD_BUG_ON(CHACHA20_STATE_ALIGN != 16);

	state = PTR_ALIGN(state_buf + 0, CHACHA20_STATE_ALIGN);

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



	kernel_fpu_begin();



	hchacha20_block_ssse3(state, subctx.key);



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

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

	err = chacha20_simd_stream_xor(req, &subctx, real_iv);



	kernel_fpu_end();



	return err;

}



static struct skcipher_alg alg = {

static struct skcipher_alg algs[] = {

	{

		.base.cra_name		= "chacha20",

		.base.cra_driver_name	= "chacha20-simd",

		.base.cra_priority	= 300,
@@ -173,6 +211,22 @@ static struct skcipher_alg alg = { 
		.setkey			= crypto_chacha20_setkey,

		.encrypt		= chacha20_simd,

		.decrypt		= chacha20_simd,

	}, {

		.base.cra_name		= "xchacha20",

		.base.cra_driver_name	= "xchacha20-simd",

		.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,

		.setkey			= crypto_chacha20_setkey,

		.encrypt		= xchacha20_simd,

		.decrypt		= xchacha20_simd,

	},

};



static int __init chacha20_simd_mod_init(void)
@@ -190,12 +244,12 @@ static int __init chacha20_simd_mod_init(void) 
				boot_cpu_has(X86_FEATURE_AVX512BW); /* kmovq */

#endif

#endif

	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);
@@ -206,3 +260,5 @@ MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); 
MODULE_DESCRIPTION("chacha20 cipher algorithm, SIMD accelerated");

MODULE_ALIAS_CRYPTO("chacha20");

MODULE_ALIAS_CRYPTO("chacha20-simd");

MODULE_ALIAS_CRYPTO("xchacha20");

MODULE_ALIAS_CRYPTO("xchacha20-simd");

crypto/Kconfig

+3 −9
Original line number Diff line number Diff line
@@ -1468,19 +1468,13 @@ config CRYPTO_CHACHA20 
	  in some performance-sensitive scenarios.



config CRYPTO_CHACHA20_X86_64

	tristate "ChaCha20 cipher algorithm (x86_64/SSSE3/AVX2)"

	tristate "ChaCha stream cipher algorithms (x86_64/SSSE3/AVX2/AVX-512VL)"

	depends on X86 && 64BIT

	select CRYPTO_BLKCIPHER

	select CRYPTO_CHACHA20

	help

	  ChaCha20 cipher algorithm, RFC7539.



	  ChaCha20 is a 256-bit high-speed stream cipher designed by Daniel J.

	  Bernstein and further specified in RFC7539 for use in IETF protocols.

	  This is the x86_64 assembler implementation using SIMD instructions.



	  See also:

	  <http://cr.yp.to/chacha/chacha-20080128.pdf>

	  SSSE3, AVX2, and AVX-512VL optimized implementations of the ChaCha20

	  and XChaCha20 stream ciphers.



config CRYPTO_SEED

	tristate "SEED cipher algorithm"