To accommodate systems that may disallow use of the NEON in kernel mode
in some circumstances, introduce a C fallback for synchronous AES in CTR
mode, and use it if may_use_simd() returns false.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
arch/arm64/crypto/Kconfig | 6 +-
arch/arm64/crypto/aes-ctr-fallback.h | 53 ++++++++++++++++++
arch/arm64/crypto/aes-glue.c | 59 +++++++++++++++-----
3 files changed, 101 insertions(+), 17 deletions(-)
diff --git a/arch/arm64/crypto/Kconfig b/arch/arm64/crypto/Kconfig
index ba637765c19a..a068dcbe2518 100644
--- a/arch/arm64/crypto/Kconfig
+++ b/arch/arm64/crypto/Kconfig
@@ -64,15 +64,17 @@ config CRYPTO_AES_ARM64_CE_CCM
config CRYPTO_AES_ARM64_CE_BLK
tristate "AES in ECB/CBC/CTR/XTS modes using ARMv8 Crypto Extensions"
- depends on ARM64 && KERNEL_MODE_NEON
+ depends on KERNEL_MODE_NEON
select CRYPTO_BLKCIPHER
select CRYPTO_AES_ARM64_CE
+ select CRYPTO_AES_ARM64
select CRYPTO_SIMD
config CRYPTO_AES_ARM64_NEON_BLK
tristate "AES in ECB/CBC/CTR/XTS modes using NEON instructions"
- depends on ARM64 && KERNEL_MODE_NEON
+ depends on KERNEL_MODE_NEON
select CRYPTO_BLKCIPHER
+ select CRYPTO_AES_ARM64
select CRYPTO_AES
select CRYPTO_SIMD
diff --git a/arch/arm64/crypto/aes-ctr-fallback.h b/arch/arm64/crypto/aes-ctr-fallback.h
new file mode 100644
index 000000000000..c9285717b6b5
--- /dev/null
+++ b/arch/arm64/crypto/aes-ctr-fallback.h
@@ -0,0 +1,53 @@
+/*
+ * Fallback for sync aes(ctr) in contexts where kernel mode NEON
+ * is not allowed
+ *
+ * Copyright (C) 2017 Linaro Ltd <ard.biesheuvel@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <crypto/aes.h>
+#include <crypto/internal/skcipher.h>
+
+asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
+
+static inline int aes_ctr_encrypt_fallback(struct crypto_aes_ctx *ctx,
+ struct skcipher_request *req)
+{
+ struct skcipher_walk walk;
+ u8 buf[AES_BLOCK_SIZE];
+ int err;
+
+ err = skcipher_walk_virt(&walk, req, true);
+
+ while (walk.nbytes > 0) {
+ u8 *dst = walk.dst.virt.addr;
+ u8 *src = walk.src.virt.addr;
+ int nbytes = walk.nbytes;
+ int tail = 0;
+
+ if (nbytes < walk.total) {
+ nbytes = round_down(nbytes, AES_BLOCK_SIZE);
+ tail = walk.nbytes % AES_BLOCK_SIZE;
+ }
+
+ do {
+ int bsize = min(nbytes, AES_BLOCK_SIZE);
+
+ __aes_arm64_encrypt(ctx->key_enc, buf, walk.iv,
+ 6 + ctx->key_length / 4);
+ crypto_xor_cpy(dst, src, buf, bsize);
+ crypto_inc(walk.iv, AES_BLOCK_SIZE);
+
+ dst += AES_BLOCK_SIZE;
+ src += AES_BLOCK_SIZE;
+ nbytes -= AES_BLOCK_SIZE;
+ } while (nbytes > 0);
+
+ err = skcipher_walk_done(&walk, tail);
+ }
+ return err;
+}
diff --git a/arch/arm64/crypto/aes-glue.c b/arch/arm64/crypto/aes-glue.c
index 0da30e3b0e4b..998ba519a026 100644
--- a/arch/arm64/crypto/aes-glue.c
+++ b/arch/arm64/crypto/aes-glue.c
@@ -10,6 +10,7 @@
#include <asm/neon.h>
#include <asm/hwcap.h>
+#include <asm/simd.h>
#include <crypto/aes.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/simd.h>
@@ -19,6 +20,7 @@
#include <crypto/xts.h>
#include "aes-ce-setkey.h"
+#include "aes-ctr-fallback.h"
#ifdef USE_V8_CRYPTO_EXTENSIONS
#define MODE "ce"
@@ -249,6 +251,17 @@ static int ctr_encrypt(struct skcipher_request *req)
return err;
}
+static int ctr_encrypt_sync(struct skcipher_request *req)
+{
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
+
+ if (!may_use_simd())
+ return aes_ctr_encrypt_fallback(ctx, req);
+
+ return ctr_encrypt(req);
+}
+
static int xts_encrypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
@@ -355,8 +368,8 @@ static struct skcipher_alg aes_algs[] = { {
.ivsize = AES_BLOCK_SIZE,
.chunksize = AES_BLOCK_SIZE,
.setkey = skcipher_aes_setkey,
- .encrypt = ctr_encrypt,
- .decrypt = ctr_encrypt,
+ .encrypt = ctr_encrypt_sync,
+ .decrypt = ctr_encrypt_sync,
}, {
.base = {
.cra_name = "__xts(aes)",
@@ -458,11 +471,35 @@ static int mac_init(struct shash_desc *desc)
return 0;
}
+static void mac_do_update(struct crypto_aes_ctx *ctx, u8 const in[], int blocks,
+ u8 dg[], int enc_before, int enc_after)
+{
+ int rounds = 6 + ctx->key_length / 4;
+
+ if (may_use_simd()) {
+ kernel_neon_begin();
+ aes_mac_update(in, ctx->key_enc, rounds, blocks, dg, enc_before,
+ enc_after);
+ kernel_neon_end();
+ } else {
+ if (enc_before)
+ __aes_arm64_encrypt(ctx->key_enc, dg, dg, rounds);
+
+ while (blocks--) {
+ crypto_xor(dg, in, AES_BLOCK_SIZE);
+ in += AES_BLOCK_SIZE;
+
+ if (blocks || enc_after)
+ __aes_arm64_encrypt(ctx->key_enc, dg, dg,
+ rounds);
+ }
+ }
+}
+
static int mac_update(struct shash_desc *desc, const u8 *p, unsigned int len)
{
struct mac_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
struct mac_desc_ctx *ctx = shash_desc_ctx(desc);
- int rounds = 6 + tctx->key.key_length / 4;
while (len > 0) {
unsigned int l;
@@ -474,10 +511,8 @@ static int mac_update(struct shash_desc *desc, const u8 *p, unsigned int len)
len %= AES_BLOCK_SIZE;
- kernel_neon_begin();
- aes_mac_update(p, tctx->key.key_enc, rounds, blocks,
- ctx->dg, (ctx->len != 0), (len != 0));
- kernel_neon_end();
+ mac_do_update(&tctx->key, p, blocks, ctx->dg,
+ (ctx->len != 0), (len != 0));
p += blocks * AES_BLOCK_SIZE;
@@ -505,11 +540,8 @@ static int cbcmac_final(struct shash_desc *desc, u8 *out)
{
struct mac_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
struct mac_desc_ctx *ctx = shash_desc_ctx(desc);
- int rounds = 6 + tctx->key.key_length / 4;
- kernel_neon_begin();
- aes_mac_update(NULL, tctx->key.key_enc, rounds, 0, ctx->dg, 1, 0);
- kernel_neon_end();
+ mac_do_update(&tctx->key, NULL, 0, ctx->dg, 1, 0);
memcpy(out, ctx->dg, AES_BLOCK_SIZE);
@@ -520,7 +552,6 @@ static int cmac_final(struct shash_desc *desc, u8 *out)
{
struct mac_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
struct mac_desc_ctx *ctx = shash_desc_ctx(desc);
- int rounds = 6 + tctx->key.key_length / 4;
u8 *consts = tctx->consts;
if (ctx->len != AES_BLOCK_SIZE) {
@@ -528,9 +559,7 @@ static int cmac_final(struct shash_desc *desc, u8 *out)
consts += AES_BLOCK_SIZE;
}
- kernel_neon_begin();
- aes_mac_update(consts, tctx->key.key_enc, rounds, 1, ctx->dg, 0, 1);
- kernel_neon_end();
+ mac_do_update(&tctx->key, consts, 1, ctx->dg, 0, 1);
memcpy(out, ctx->dg, AES_BLOCK_SIZE);
--
2.9.3
