[PATCH v3 1/6] drivers: crypto: qce: sha: Restore/save ahash state with custom struct in export/import

Thara Gopinath
2021-01-20T19:01:46Z

Export and import interfaces save and restore partial transformation
states. The partial states were being stored and restored in struct
sha1_state for sha1/hmac(sha1) transformations and sha256_state for
sha256/hmac(sha256) transformations.This led to a bunch of corner cases
where improper state was being stored and restored. A few of the corner
cases that turned up during testing are:

- wrong byte_count restored if export/import is called twice without h/w
transaction in between
- wrong buflen restored back if the pending buffer
length is exactly the block size.
- wrong state restored if buffer length is 0.

To fix these issues, save and restore the partial transformation state
using the newly introduced qce_sha_saved_state struct. This ensures that
all the pieces required to properly restart the transformation is captured
and restored back

Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
---

v1->v2:
- Introduced custom struct qce_sha_saved_state to store and
restore partial sha transformation. v1 was re-using
qce_sha_reqctx to save and restore partial states and this
could lead to potential memcpy issues around pointer copying.

drivers/crypto/qce/sha.c | 122 +++++++++++----------------------------
1 file changed, 34 insertions(+), 88 deletions(-)

diff --git a/drivers/crypto/qce/sha.c b/drivers/crypto/qce/sha.c
index 61c418c12345..08aed03e2b59 100644
--- a/drivers/crypto/qce/sha.c
+++ b/drivers/crypto/qce/sha.c
@@ -12,9 +12,15 @@
#include "core.h"
#include "sha.h"

-/* crypto hw padding constant for first operation */
-#define SHA_PADDING 64
-#define SHA_PADDING_MASK (SHA_PADDING - 1)
+struct qce_sha_saved_state {
+ u8 pending_buf[QCE_SHA_MAX_BLOCKSIZE];
+ u8 partial_digest[QCE_SHA_MAX_DIGESTSIZE];
+ __be32 byte_count[2];
+ unsigned int pending_buflen;
+ unsigned int flags;
+ u64 count;
+ bool first_blk;
+};

static LIST_HEAD(ahash_algs);

@@ -139,97 +145,37 @@ static int qce_ahash_init(struct ahash_request *req)

static int qce_ahash_export(struct ahash_request *req, void *out)
{
- struct crypto_ahash *ahash = crypto_ahash_reqtfm(req);
struct qce_sha_reqctx *rctx = ahash_request_ctx(req);
- unsigned long flags = rctx->flags;
- unsigned int digestsize = crypto_ahash_digestsize(ahash);
- unsigned int blocksize =
- crypto_tfm_alg_blocksize(crypto_ahash_tfm(ahash));
-
- if (IS_SHA1(flags) || IS_SHA1_HMAC(flags)) {
- struct sha1_state *out_state = out;
-
- out_state->count = rctx->count;
- qce_cpu_to_be32p_array((__be32 *)out_state->state,
- rctx->digest, digestsize);
- memcpy(out_state->buffer, rctx->buf, blocksize);
- } else if (IS_SHA256(flags) || IS_SHA256_HMAC(flags)) {
- struct sha256_state *out_state = out;
-
- out_state->count = rctx->count;
- qce_cpu_to_be32p_array((__be32 *)out_state->state,
- rctx->digest, digestsize);
- memcpy(out_state->buf, rctx->buf, blocksize);
- } else {
- return -EINVAL;
- }
-
- return 0;
-}
-
-static int qce_import_common(struct ahash_request *req, u64 in_count,
- const u32 *state, const u8 *buffer, bool hmac)
-{
- struct crypto_ahash *ahash = crypto_ahash_reqtfm(req);
- struct qce_sha_reqctx *rctx = ahash_request_ctx(req);
- unsigned int digestsize = crypto_ahash_digestsize(ahash);
- unsigned int blocksize;
- u64 count = in_count;
-
- blocksize = crypto_tfm_alg_blocksize(crypto_ahash_tfm(ahash));
- rctx->count = in_count;
- memcpy(rctx->buf, buffer, blocksize);
-
- if (in_count <= blocksize) {
- rctx->first_blk = 1;
- } else {
- rctx->first_blk = 0;
- /*
- * For HMAC, there is a hardware padding done when first block
- * is set. Therefore the byte_count must be incremened by 64
- * after the first block operation.
- */
- if (hmac)
- count += SHA_PADDING;
- }
+ struct qce_sha_saved_state *export_state = out;

- rctx->byte_count[0] = (__force __be32)(count & ~SHA_PADDING_MASK);
- rctx->byte_count[1] = (__force __be32)(count >> 32);
- qce_cpu_to_be32p_array((__be32 *)rctx->digest, (const u8 *)state,
- digestsize);
- rctx->buflen = (unsigned int)(in_count & (blocksize - 1));
+ memcpy(export_state->pending_buf, rctx->buf, rctx->buflen);
+ memcpy(export_state->partial_digest, rctx->digest,
+ sizeof(rctx->digest));
+ memcpy(export_state->byte_count, rctx->byte_count, 2);
+ export_state->pending_buflen = rctx->buflen;
+ export_state->count = rctx->count;
+ export_state->first_blk = rctx->first_blk;
+ export_state->flags = rctx->flags;

return 0;
}

static int qce_ahash_import(struct ahash_request *req, const void *in)
{
- struct qce_sha_reqctx *rctx;
- unsigned long flags;
- bool hmac;
- int ret;
-
- ret = qce_ahash_init(req);
- if (ret)
- return ret;
-
- rctx = ahash_request_ctx(req);
- flags = rctx->flags;
- hmac = IS_SHA_HMAC(flags);
-
- if (IS_SHA1(flags) || IS_SHA1_HMAC(flags)) {
- const struct sha1_state *state = in;
-
- ret = qce_import_common(req, state->count, state->state,
- state->buffer, hmac);
- } else if (IS_SHA256(flags) || IS_SHA256_HMAC(flags)) {
- const struct sha256_state *state = in;
+ struct qce_sha_reqctx *rctx = ahash_request_ctx(req);
+ struct qce_sha_saved_state *import_state = in;

- ret = qce_import_common(req, state->count, state->state,
- state->buf, hmac);
- }
+ memset(rctx, 0, sizeof(*rctx));
+ rctx->count = import_state->count;
+ rctx->buflen = import_state->pending_buflen;
+ rctx->first_blk = import_state->first_blk;
+ rctx->flags = import_state->flags;
+ memcpy(rctx->buf, import_state->pending_buf, rctx->buflen);
+ memcpy(rctx->digest, import_state->partial_digest,
+ sizeof(rctx->digest));
+ memcpy(rctx->byte_count, import_state->byte_count, 2);

- return ret;
+ return 0;
}

static int qce_ahash_update(struct ahash_request *req)
@@ -450,7 +396,7 @@ static const struct qce_ahash_def ahash_def[] = {
.drv_name = "sha1-qce",
.digestsize = SHA1_DIGEST_SIZE,
.blocksize = SHA1_BLOCK_SIZE,
- .statesize = sizeof(struct sha1_state),
+ .statesize = sizeof(struct qce_sha_saved_state),
.std_iv = std_iv_sha1,
},
{
@@ -459,7 +405,7 @@ static const struct qce_ahash_def ahash_def[] = {
.drv_name = "sha256-qce",
.digestsize = SHA256_DIGEST_SIZE,
.blocksize = SHA256_BLOCK_SIZE,
- .statesize = sizeof(struct sha256_state),
+ .statesize = sizeof(struct qce_sha_saved_state),
.std_iv = std_iv_sha256,
},
{
@@ -468,7 +414,7 @@ static const struct qce_ahash_def ahash_def[] = {
.drv_name = "hmac-sha1-qce",
.digestsize = SHA1_DIGEST_SIZE,
.blocksize = SHA1_BLOCK_SIZE,
- .statesize = sizeof(struct sha1_state),
+ .statesize = sizeof(struct qce_sha_saved_state),
.std_iv = std_iv_sha1,
},
{
@@ -477,7 +423,7 @@ static const struct qce_ahash_def ahash_def[] = {
.drv_name = "hmac-sha256-qce",
.digestsize = SHA256_DIGEST_SIZE,
.blocksize = SHA256_BLOCK_SIZE,
- .statesize = sizeof(struct sha256_state),
+ .statesize = sizeof(struct qce_sha_saved_state),
.std_iv = std_iv_sha256,
},
};
--
2.25.1