Am Mittwoch, 23. August 2017, 11:12:05 CEST schrieb Gilad Ben-Yossef:
Hi Gilad,
> The crypto API requires saving the last blocks of ciphertext
> in req->info for use as IV for CTS mode. The ccree driver
> was not doing this. This patch fixes that.
>
> The bug was manifested with cts(cbc(aes)) mode in tcrypt tests.
>
> Fixes: 302ef8ebb4b2 ("Add CryptoCell skcipher support")
> Signed-off-by: Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx>
> ---
>
> Changes from v1:
> - Free memory on error path, as pointed out by Stephan Mueller.
>
> drivers/staging/ccree/ssi_cipher.c | 40
> ++++++++++++++++++++++++++++++++++---- 1 file changed, 36 insertions(+), 4
> deletions(-)
>
> diff --git a/drivers/staging/ccree/ssi_cipher.c
> b/drivers/staging/ccree/ssi_cipher.c index af9afea..8d31a93 100644
> --- a/drivers/staging/ccree/ssi_cipher.c
> +++ b/drivers/staging/ccree/ssi_cipher.c
> @@ -24,6 +24,7 @@
> #include <crypto/ctr.h>
> #include <crypto/des.h>
> #include <crypto/xts.h>
> +#include <crypto/scatterwalk.h>
>
> #include "ssi_config.h"
> #include "ssi_driver.h"
> @@ -697,6 +698,7 @@ static int ssi_blkcipher_complete(struct device *dev,
> {
> int completion_error = 0;
> u32 inflight_counter;
> + struct ablkcipher_request *req = (struct ablkcipher_request *)areq;
>
> ssi_buffer_mgr_unmap_blkcipher_request(dev, req_ctx, ivsize, src, dst);
>
> @@ -707,6 +709,22 @@ static int ssi_blkcipher_complete(struct device *dev,
> ctx_p->drvdata->inflight_counter--;
>
> if (areq) {
> + /*
> + * The crypto API expects us to set the req->info to the last
> + * ciphertext block. For encrypt, simply copy from the result.
> + * For decrypt, we must copy from a saved buffer since this
> + * could be an in-place decryption operation and the src is
> + * lost by this point.
> + */
> + if (req_ctx->gen_ctx.op_type == DRV_CRYPTO_DIRECTION_DECRYPT) {
> + memcpy(req->info, req_ctx->backup_info, ivsize);
> + kfree(req_ctx->backup_info);
> + } else {
> + scatterwalk_map_and_copy(req->info, req->dst,
> + (req->nbytes - ivsize),
> + ivsize, 0);
Sorry to be persistent, but what about this code path? Here you do not free
it, yet it is allocated.
> + }
> +
> ablkcipher_request_complete(areq, completion_error);
> return 0;
> }
> @@ -739,11 +757,13 @@ static int ssi_blkcipher_process(
> if (unlikely(validate_data_size(ctx_p, nbytes))) {
> SSI_LOG_ERR("Unsupported data size %d.\n", nbytes);
> crypto_tfm_set_flags(tfm, CRYPTO_TFM_RES_BAD_BLOCK_LEN);
> - return -EINVAL;
> + rc = -EINVAL;
> + goto exit_process;
> }
> if (nbytes == 0) {
> /* No data to process is valid */
> - return 0;
> + rc = 0;
> + goto exit_process;
> }
> /*For CTS in case of data size aligned to 16 use CBC mode*/
> if (((nbytes % AES_BLOCK_SIZE) == 0) && (ctx_p->cipher_mode ==
> DRV_CIPHER_CBC_CTS)) { @@ -818,6 +838,9 @@ static int
> ssi_blkcipher_process(
> if (cts_restore_flag != 0)
> ctx_p->cipher_mode = DRV_CIPHER_CBC_CTS;
>
> + if (rc != -EINPROGRESS)
> + kfree(req_ctx->backup_info);
> +
> return rc;
> }
>
> @@ -858,7 +881,6 @@ static int ssi_ablkcipher_encrypt(struct
> ablkcipher_request *req) struct blkcipher_req_ctx *req_ctx =
> ablkcipher_request_ctx(req); unsigned int ivsize =
> crypto_ablkcipher_ivsize(ablk_tfm);
>
> - req_ctx->backup_info = req->info;
> req_ctx->is_giv = false;
>
> return ssi_blkcipher_process(tfm, req_ctx, req->dst, req->src,
> req->nbytes, req->info, ivsize, (void *)req, DRV_CRYPTO_DIRECTION_ENCRYPT);
> @@ -871,8 +893,18 @@ static int ssi_ablkcipher_decrypt(struct
> ablkcipher_request *req) struct blkcipher_req_ctx *req_ctx =
> ablkcipher_request_ctx(req); unsigned int ivsize =
> crypto_ablkcipher_ivsize(ablk_tfm);
>
> - req_ctx->backup_info = req->info;
> + /*
> + * Allocate and save the last IV sized bytes of the source, which will
> + * be lost in case of in-place decryption and might be needed for CTS.
> + */
> + req_ctx->backup_info = kmalloc(ivsize, GFP_KERNEL);
> + if (!req_ctx->backup_info)
> + return -ENOMEM;
> +
> + scatterwalk_map_and_copy(req_ctx->backup_info, req->src,
> + (req->nbytes - ivsize), ivsize, 0);
> req_ctx->is_giv = false;
> +
> return ssi_blkcipher_process(tfm, req_ctx, req->dst, req->src,
> req->nbytes, req->info, ivsize, (void *)req, DRV_CRYPTO_DIRECTION_DECRYPT);
> }
Ciao
Stephan
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