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crypto: sahara - Remove VLA usage of skcipher
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In the quest to remove all stack VLA usage from the kernel[1], this
replaces struct crypto_skcipher and SKCIPHER_REQUEST_ON_STACK() usage
with struct crypto_sync_skcipher and SYNC_SKCIPHER_REQUEST_ON_STACK(),
which uses a fixed stack size.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Kees Cook authored and Herbert Xu committed Sep 28, 2018
1 parent 36b3875 commit ba70152
Showing 1 changed file with 15 additions and 16 deletions.
31 changes: 15 additions & 16 deletions drivers/crypto/sahara.c
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Original file line number Diff line number Diff line change
Expand Up @@ -149,7 +149,7 @@ struct sahara_ctx {
/* AES-specific context */
int keylen;
u8 key[AES_KEYSIZE_128];
struct crypto_skcipher *fallback;
struct crypto_sync_skcipher *fallback;
};

struct sahara_aes_reqctx {
Expand Down Expand Up @@ -621,14 +621,14 @@ static int sahara_aes_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
/*
* The requested key size is not supported by HW, do a fallback.
*/
crypto_skcipher_clear_flags(ctx->fallback, CRYPTO_TFM_REQ_MASK);
crypto_skcipher_set_flags(ctx->fallback, tfm->base.crt_flags &
crypto_sync_skcipher_clear_flags(ctx->fallback, CRYPTO_TFM_REQ_MASK);
crypto_sync_skcipher_set_flags(ctx->fallback, tfm->base.crt_flags &
CRYPTO_TFM_REQ_MASK);

ret = crypto_skcipher_setkey(ctx->fallback, key, keylen);
ret = crypto_sync_skcipher_setkey(ctx->fallback, key, keylen);

tfm->base.crt_flags &= ~CRYPTO_TFM_RES_MASK;
tfm->base.crt_flags |= crypto_skcipher_get_flags(ctx->fallback) &
tfm->base.crt_flags |= crypto_sync_skcipher_get_flags(ctx->fallback) &
CRYPTO_TFM_RES_MASK;
return ret;
}
Expand Down Expand Up @@ -666,9 +666,9 @@ static int sahara_aes_ecb_encrypt(struct ablkcipher_request *req)
int err;

if (unlikely(ctx->keylen != AES_KEYSIZE_128)) {
SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);
SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);

skcipher_request_set_tfm(subreq, ctx->fallback);
skcipher_request_set_sync_tfm(subreq, ctx->fallback);
skcipher_request_set_callback(subreq, req->base.flags,
NULL, NULL);
skcipher_request_set_crypt(subreq, req->src, req->dst,
Expand All @@ -688,9 +688,9 @@ static int sahara_aes_ecb_decrypt(struct ablkcipher_request *req)
int err;

if (unlikely(ctx->keylen != AES_KEYSIZE_128)) {
SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);
SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);

skcipher_request_set_tfm(subreq, ctx->fallback);
skcipher_request_set_sync_tfm(subreq, ctx->fallback);
skcipher_request_set_callback(subreq, req->base.flags,
NULL, NULL);
skcipher_request_set_crypt(subreq, req->src, req->dst,
Expand All @@ -710,9 +710,9 @@ static int sahara_aes_cbc_encrypt(struct ablkcipher_request *req)
int err;

if (unlikely(ctx->keylen != AES_KEYSIZE_128)) {
SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);
SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);

skcipher_request_set_tfm(subreq, ctx->fallback);
skcipher_request_set_sync_tfm(subreq, ctx->fallback);
skcipher_request_set_callback(subreq, req->base.flags,
NULL, NULL);
skcipher_request_set_crypt(subreq, req->src, req->dst,
Expand All @@ -732,9 +732,9 @@ static int sahara_aes_cbc_decrypt(struct ablkcipher_request *req)
int err;

if (unlikely(ctx->keylen != AES_KEYSIZE_128)) {
SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);
SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);

skcipher_request_set_tfm(subreq, ctx->fallback);
skcipher_request_set_sync_tfm(subreq, ctx->fallback);
skcipher_request_set_callback(subreq, req->base.flags,
NULL, NULL);
skcipher_request_set_crypt(subreq, req->src, req->dst,
Expand All @@ -752,8 +752,7 @@ static int sahara_aes_cra_init(struct crypto_tfm *tfm)
const char *name = crypto_tfm_alg_name(tfm);
struct sahara_ctx *ctx = crypto_tfm_ctx(tfm);

ctx->fallback = crypto_alloc_skcipher(name, 0,
CRYPTO_ALG_ASYNC |
ctx->fallback = crypto_alloc_sync_skcipher(name, 0,
CRYPTO_ALG_NEED_FALLBACK);
if (IS_ERR(ctx->fallback)) {
pr_err("Error allocating fallback algo %s\n", name);
Expand All @@ -769,7 +768,7 @@ static void sahara_aes_cra_exit(struct crypto_tfm *tfm)
{
struct sahara_ctx *ctx = crypto_tfm_ctx(tfm);

crypto_free_skcipher(ctx->fallback);
crypto_free_sync_skcipher(ctx->fallback);
}

static u32 sahara_sha_init_hdr(struct sahara_dev *dev,
Expand Down

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