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crypto: arm64/aes-cts-cbc - move request context data to the stack
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Since the CTS-CBC code completes synchronously, there is no point in
keeping part of the scratch data it uses in the request context, so
move it to the stack instead.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Ard Biesheuvel authored and Herbert Xu committed Sep 9, 2019
1 parent 0cfd507 commit 7c9d65c
Showing 1 changed file with 26 additions and 35 deletions.
61 changes: 26 additions & 35 deletions arch/arm64/crypto/aes-glue.c
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Original file line number Diff line number Diff line change
Expand Up @@ -107,12 +107,6 @@ asmlinkage void aes_mac_update(u8 const in[], u32 const rk[], int rounds,
int blocks, u8 dg[], int enc_before,
int enc_after);

struct cts_cbc_req_ctx {
struct scatterlist sg_src[2];
struct scatterlist sg_dst[2];
struct skcipher_request subreq;
};

struct crypto_aes_xts_ctx {
struct crypto_aes_ctx key1;
struct crypto_aes_ctx __aligned(8) key2;
Expand Down Expand Up @@ -292,23 +286,20 @@ static int __maybe_unused cbc_decrypt(struct skcipher_request *req)
return cbc_decrypt_walk(req, &walk);
}

static int cts_cbc_init_tfm(struct crypto_skcipher *tfm)
{
crypto_skcipher_set_reqsize(tfm, sizeof(struct cts_cbc_req_ctx));
return 0;
}

static int cts_cbc_encrypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
struct cts_cbc_req_ctx *rctx = skcipher_request_ctx(req);
int err, rounds = 6 + ctx->key_length / 4;
int cbc_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2;
struct scatterlist *src = req->src, *dst = req->dst;
struct scatterlist sg_src[2], sg_dst[2];
struct skcipher_request subreq;
struct skcipher_walk walk;

skcipher_request_set_tfm(&rctx->subreq, tfm);
skcipher_request_set_tfm(&subreq, tfm);
skcipher_request_set_callback(&subreq, skcipher_request_flags(req),
NULL, NULL);

if (req->cryptlen <= AES_BLOCK_SIZE) {
if (req->cryptlen < AES_BLOCK_SIZE)
Expand All @@ -317,31 +308,30 @@ static int cts_cbc_encrypt(struct skcipher_request *req)
}

if (cbc_blocks > 0) {
skcipher_request_set_crypt(&rctx->subreq, req->src, req->dst,
skcipher_request_set_crypt(&subreq, req->src, req->dst,
cbc_blocks * AES_BLOCK_SIZE,
req->iv);

err = skcipher_walk_virt(&walk, &rctx->subreq, false) ?:
cbc_encrypt_walk(&rctx->subreq, &walk);
err = skcipher_walk_virt(&walk, &subreq, false) ?:
cbc_encrypt_walk(&subreq, &walk);
if (err)
return err;

if (req->cryptlen == AES_BLOCK_SIZE)
return 0;

dst = src = scatterwalk_ffwd(rctx->sg_src, req->src,
rctx->subreq.cryptlen);
dst = src = scatterwalk_ffwd(sg_src, req->src, subreq.cryptlen);
if (req->dst != req->src)
dst = scatterwalk_ffwd(rctx->sg_dst, req->dst,
rctx->subreq.cryptlen);
dst = scatterwalk_ffwd(sg_dst, req->dst,
subreq.cryptlen);
}

/* handle ciphertext stealing */
skcipher_request_set_crypt(&rctx->subreq, src, dst,
skcipher_request_set_crypt(&subreq, src, dst,
req->cryptlen - cbc_blocks * AES_BLOCK_SIZE,
req->iv);

err = skcipher_walk_virt(&walk, &rctx->subreq, false);
err = skcipher_walk_virt(&walk, &subreq, false);
if (err)
return err;

Expand All @@ -357,13 +347,16 @@ static int cts_cbc_decrypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
struct cts_cbc_req_ctx *rctx = skcipher_request_ctx(req);
int err, rounds = 6 + ctx->key_length / 4;
int cbc_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2;
struct scatterlist *src = req->src, *dst = req->dst;
struct scatterlist sg_src[2], sg_dst[2];
struct skcipher_request subreq;
struct skcipher_walk walk;

skcipher_request_set_tfm(&rctx->subreq, tfm);
skcipher_request_set_tfm(&subreq, tfm);
skcipher_request_set_callback(&subreq, skcipher_request_flags(req),
NULL, NULL);

if (req->cryptlen <= AES_BLOCK_SIZE) {
if (req->cryptlen < AES_BLOCK_SIZE)
Expand All @@ -372,31 +365,30 @@ static int cts_cbc_decrypt(struct skcipher_request *req)
}

if (cbc_blocks > 0) {
skcipher_request_set_crypt(&rctx->subreq, req->src, req->dst,
skcipher_request_set_crypt(&subreq, req->src, req->dst,
cbc_blocks * AES_BLOCK_SIZE,
req->iv);

err = skcipher_walk_virt(&walk, &rctx->subreq, false) ?:
cbc_decrypt_walk(&rctx->subreq, &walk);
err = skcipher_walk_virt(&walk, &subreq, false) ?:
cbc_decrypt_walk(&subreq, &walk);
if (err)
return err;

if (req->cryptlen == AES_BLOCK_SIZE)
return 0;

dst = src = scatterwalk_ffwd(rctx->sg_src, req->src,
rctx->subreq.cryptlen);
dst = src = scatterwalk_ffwd(sg_src, req->src, subreq.cryptlen);
if (req->dst != req->src)
dst = scatterwalk_ffwd(rctx->sg_dst, req->dst,
rctx->subreq.cryptlen);
dst = scatterwalk_ffwd(sg_dst, req->dst,
subreq.cryptlen);
}

/* handle ciphertext stealing */
skcipher_request_set_crypt(&rctx->subreq, src, dst,
skcipher_request_set_crypt(&subreq, src, dst,
req->cryptlen - cbc_blocks * AES_BLOCK_SIZE,
req->iv);

err = skcipher_walk_virt(&walk, &rctx->subreq, false);
err = skcipher_walk_virt(&walk, &subreq, false);
if (err)
return err;

Expand Down Expand Up @@ -673,7 +665,6 @@ static struct skcipher_alg aes_algs[] = { {
.setkey = skcipher_aes_setkey,
.encrypt = cts_cbc_encrypt,
.decrypt = cts_cbc_decrypt,
.init = cts_cbc_init_tfm,
}, {
.base = {
.cra_name = "__essiv(cbc(aes),sha256)",
Expand Down

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