On Wed 20 Jan 12:48 CST 2021, Thara Gopinath wrote:

Please drop "drivers: " from $subject.

> 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.gopin...@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));

No need to wrap this line.

> +     memcpy(export_state->byte_count, rctx->byte_count, 2);

You're only stashing 2 of the 8 bytes here. So you should either copy
sizeof(byte_count) bytes, or perhaps it's more obvious if you just
assigned byte_count[0] and byte_count[1]?

> +     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);

Same as above, you're just restoring 2 of the 8 bytes.

Regards,
Bjorn

>  
> -     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
> 

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