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crypto: arm/chacha20 - add XChaCha20 support
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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: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Eric Biggers authored and Herbert Xu committed Nov 20, 2018
1 parent be2830b commit d97a943
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Showing 3 changed files with 126 additions and 49 deletions.
2 changes: 1 addition & 1 deletion arch/arm/crypto/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -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
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70 changes: 48 additions & 22 deletions arch/arm/crypto/chacha20-neon-core.S
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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]
Expand All @@ -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
Expand Down
103 changes: 77 additions & 26 deletions arch/arm/crypto/chacha20-neon-glue.c
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* 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>
*
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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;
Expand All @@ -88,35 +85,86 @@ static int chacha20_neon(struct skcipher_request *req)
return err;
}

static struct skcipher_alg alg = {
.base.cra_name = "chacha20",
.base.cra_driver_name = "chacha20-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 = CHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE,
.walksize = 4 * CHACHA_BLOCK_SIZE,
.setkey = crypto_chacha20_setkey,
.encrypt = chacha20_neon,
.decrypt = chacha20_neon,
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,
.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 = CHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE,
.walksize = 4 * CHACHA_BLOCK_SIZE,
.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)
{
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);
Expand All @@ -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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