Re: [BUGFIX PATCH v2] staging: ccree: save ciphertext for CTS IV

[Stephan Mueller]

Am Mittwoch, 23. August 2017, 12:47:36 CEST schrieb Gilad Ben-Yossef:

Hi Gilad,
> 
> Thank you for your persistence. It is appreciated :-)
> 
> If I understood correctly what you are referring to than the buffer is not
> allocated in this code path (unless I've missed something):

Ah, that is what I was missing :-)

Thanks for clarification. No further objections ;-)

Ciao
Stephan

Re: [BUGFIX PATCH v2] staging: ccree: save ciphertext for CTS IV

[Gilad Ben-Yossef]

On Wed, Aug 23, 2017 at 1:03 PM, Stephan Mueller  wrote:
> 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 
>> ---
>>
>> 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 
>>  #include 
>>  #include 
>> +#include 
>>
>>  #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.

Thank you for your persistence. It is appreciated :-)

If I understood correctly what you are referring to than the buffer is not
allocated in this code path (unless I've missed something):

The buffer is allocated in ssi_ablkcipher_decrypt() which sets
req_ctx->gen_ctx.op_type
to DRV_CRYPTO_DIRECTION_DECRYPT.

The buffer is not allocated in the parallel function
(ssi_ablkcipher_encrypt) which matches
the else clause of this if statement.



>> + }
>> +
>>   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.
>> +  

Re: [BUGFIX PATCH v2] staging: ccree: save ciphertext for CTS IV

[Stephan Mueller]

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 
> ---
> 
> 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 
>  #include 
>  #include 
> +#include 
> 
>  #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

[BUGFIX PATCH v2] staging: ccree: save ciphertext for CTS IV

[Gilad Ben-Yossef]

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 
---

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 
 #include 
 #include 
+#include 
 
 #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);
+   }
+
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);
 }
 
-- 
2.1.4