Update the AES-XTS implementation based on NEON instructions so that it
can deal with inputs whose size is not a multiple of the cipher block
size. This is part of the original XTS specification, but was never
implemented before in the Linux kernel.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
arch/arm/crypto/aes-neonbs-core.S | 16 +++--
arch/arm/crypto/aes-neonbs-glue.c | 69 +++++++++++++++++---
2 files changed, 72 insertions(+), 13 deletions(-)
diff --git a/arch/arm/crypto/aes-neonbs-core.S b/arch/arm/crypto/aes-neonbs-core.S
index bb75918e4984..cfaed4e67535 100644
--- a/arch/arm/crypto/aes-neonbs-core.S
+++ b/arch/arm/crypto/aes-neonbs-core.S
@@ -889,9 +889,9 @@ ENDPROC(aesbs_ctr_encrypt)
/*
* aesbs_xts_encrypt(u8 out[], u8 const in[], u8 const rk[], int rounds,
- * int blocks, u8 iv[])
+ * int blocks, u8 iv[], int reorder_last_tweak)
* aesbs_xts_decrypt(u8 out[], u8 const in[], u8 const rk[], int rounds,
- * int blocks, u8 iv[])
+ * int blocks, u8 iv[], int reorder_last_tweak)
*/
__xts_prepare8:
vld1.8 {q14}, [r7] // load iv
@@ -944,17 +944,25 @@ __xts_prepare8:
vld1.8 {q7}, [r1]!
next_tweak q14, q12, q15, q13
- veor q7, q7, q12
+THUMB( itt le )
+ W(cmple) r8, #0
+ ble 1f
+0: veor q7, q7, q12
vst1.8 {q12}, [r4, :128]
-0: vst1.8 {q14}, [r7] // store next iv
+ vst1.8 {q14}, [r7] // store next iv
bx lr
+
+1: vswp q12, q14
+ b 0b
ENDPROC(__xts_prepare8)
.macro __xts_crypt, do8, o0, o1, o2, o3, o4, o5, o6, o7
push {r4-r8, lr}
mov r5, sp // preserve sp
ldrd r6, r7, [sp, #24] // get blocks and iv args
+ ldr r8, [sp, #32] // reorder final tweak?
+ rsb r8, r8, #1
sub ip, sp, #128 // make room for 8x tweak
bic ip, ip, #0xf // align sp to 16 bytes
mov sp, ip
diff --git a/arch/arm/crypto/aes-neonbs-glue.c b/arch/arm/crypto/aes-neonbs-glue.c
index 9000d0796d5e..e85839a8aaeb 100644
--- a/arch/arm/crypto/aes-neonbs-glue.c
+++ b/arch/arm/crypto/aes-neonbs-glue.c
@@ -12,6 +12,7 @@
#include <crypto/ctr.h>
#include <crypto/internal/simd.h>
#include <crypto/internal/skcipher.h>
+#include <crypto/scatterwalk.h>
#include <crypto/xts.h>
#include <linux/module.h>
@@ -37,9 +38,9 @@ asmlinkage void aesbs_ctr_encrypt(u8 out[], u8 const in[], u8 const rk[],
int rounds, int blocks, u8 ctr[], u8 final[]);
asmlinkage void aesbs_xts_encrypt(u8 out[], u8 const in[], u8 const rk[],
- int rounds, int blocks, u8 iv[]);
+ int rounds, int blocks, u8 iv[], int);
asmlinkage void aesbs_xts_decrypt(u8 out[], u8 const in[], u8 const rk[],
- int rounds, int blocks, u8 iv[]);
+ int rounds, int blocks, u8 iv[], int);
struct aesbs_ctx {
int rounds;
@@ -53,6 +54,7 @@ struct aesbs_cbc_ctx {
struct aesbs_xts_ctx {
struct aesbs_ctx key;
+ struct crypto_cipher *cts_tfm;
struct crypto_cipher *tweak_tfm;
};
@@ -291,6 +293,9 @@ static int aesbs_xts_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
return err;
key_len /= 2;
+ err = crypto_cipher_setkey(ctx->cts_tfm, in_key, key_len);
+ if (err)
+ return err;
err = crypto_cipher_setkey(ctx->tweak_tfm, in_key + key_len, key_len);
if (err)
return err;
@@ -302,7 +307,13 @@ static int xts_init(struct crypto_tfm *tfm)
{
struct aesbs_xts_ctx *ctx = crypto_tfm_ctx(tfm);
+ ctx->cts_tfm = crypto_alloc_cipher("aes", 0, 0);
+ if (IS_ERR(ctx->cts_tfm))
+ return PTR_ERR(ctx->cts_tfm);
+
ctx->tweak_tfm = crypto_alloc_cipher("aes", 0, 0);
+ if (IS_ERR(ctx->tweak_tfm))
+ crypto_free_cipher(ctx->cts_tfm);
return PTR_ERR_OR_ZERO(ctx->tweak_tfm);
}
@@ -312,17 +323,34 @@ static void xts_exit(struct crypto_tfm *tfm)
struct aesbs_xts_ctx *ctx = crypto_tfm_ctx(tfm);
crypto_free_cipher(ctx->tweak_tfm);
+ crypto_free_cipher(ctx->cts_tfm);
}
-static int __xts_crypt(struct skcipher_request *req,
+static int __xts_crypt(struct skcipher_request *req, bool encrypt,
void (*fn)(u8 out[], u8 const in[], u8 const rk[],
- int rounds, int blocks, u8 iv[]))
+ int rounds, int blocks, u8 iv[], int))
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct aesbs_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
+ int tail = req->cryptlen % AES_BLOCK_SIZE;
+ struct skcipher_request subreq;
+ u8 buf[2 * AES_BLOCK_SIZE];
struct skcipher_walk walk;
int err;
+ if (req->cryptlen < AES_BLOCK_SIZE)
+ return -EINVAL;
+
+ if (unlikely(tail)) {
+ skcipher_request_set_tfm(&subreq, tfm);
+ skcipher_request_set_callback(&subreq,
+ skcipher_request_flags(req),
+ NULL, NULL);
+ skcipher_request_set_crypt(&subreq, req->src, req->dst,
+ req->cryptlen - tail, req->iv);
+ req = &subreq;
+ }
+
err = skcipher_walk_virt(&walk, req, true);
if (err)
return err;
@@ -331,30 +359,53 @@ static int __xts_crypt(struct skcipher_request *req,
while (walk.nbytes >= AES_BLOCK_SIZE) {
unsigned int blocks = walk.nbytes / AES_BLOCK_SIZE;
+ int reorder_last_tweak = !encrypt && tail > 0;
- if (walk.nbytes < walk.total)
+ if (walk.nbytes < walk.total) {
blocks = round_down(blocks,
walk.stride / AES_BLOCK_SIZE);
+ reorder_last_tweak = 0;
+ }
kernel_neon_begin();
fn(walk.dst.virt.addr, walk.src.virt.addr, ctx->key.rk,
- ctx->key.rounds, blocks, walk.iv);
+ ctx->key.rounds, blocks, walk.iv, reorder_last_tweak);
kernel_neon_end();
err = skcipher_walk_done(&walk,
walk.nbytes - blocks * AES_BLOCK_SIZE);
}
- return err;
+ if (err || likely(!tail))
+ return err;
+
+ /* handle ciphertext stealing */
+ scatterwalk_map_and_copy(buf, req->dst, req->cryptlen - AES_BLOCK_SIZE,
+ AES_BLOCK_SIZE, 0);
+ memcpy(buf + AES_BLOCK_SIZE, buf, tail);
+ scatterwalk_map_and_copy(buf, req->src, req->cryptlen, tail, 0);
+
+ crypto_xor(buf, req->iv, AES_BLOCK_SIZE);
+
+ if (encrypt)
+ crypto_cipher_encrypt_one(ctx->cts_tfm, buf, buf);
+ else
+ crypto_cipher_decrypt_one(ctx->cts_tfm, buf, buf);
+
+ crypto_xor(buf, req->iv, AES_BLOCK_SIZE);
+
+ scatterwalk_map_and_copy(buf, req->dst, req->cryptlen - AES_BLOCK_SIZE,
+ AES_BLOCK_SIZE + tail, 1);
+ return 0;
}
static int xts_encrypt(struct skcipher_request *req)
{
- return __xts_crypt(req, aesbs_xts_encrypt);
+ return __xts_crypt(req, true, aesbs_xts_encrypt);
}
static int xts_decrypt(struct skcipher_request *req)
{
- return __xts_crypt(req, aesbs_xts_decrypt);
+ return __xts_crypt(req, false, aesbs_xts_decrypt);
}
static struct skcipher_alg aes_algs[] = { {
--
2.17.1
