linux-kernel - Re: [RFC PATCH 1/2] crypto: caam - properly set IV after {en,de}crypt

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Date:   Wed, 28 Jun 2017 08:32:12 +0000
From:   Horia Geantă <horia.geanta@....com>
To:     David Gstir <david@...ma-star.at>,
        Dan Douglass <dan.douglass@....com>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "richard@...ma-star.at" <richard@...ma-star.at>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/2] crypto: caam - properly set IV after {en,de}crypt

On 6/19/2017 1:31 PM, Horia Geantă wrote:
> On 6/2/2017 3:25 PM, David Gstir wrote:
>> Certain cipher modes like CTS expect the IV (req->info) of
>> ablkcipher_request (or equivalently req->iv of skcipher_request) to
>> contain the last ciphertext block when the {en,de}crypt operation is done.
>> This is currently not the case for the CAAM driver which in turn breaks
>> e.g. cts(cbc(aes)) when the CAAM driver is enabled.
>>
>> This patch fixes the CAAM driver to properly set the IV after the
>> {en,de}crypt operation of ablkcipher finishes.
>>
>> Signed-off-by: David Gstir <david@...ma-star.at>
>> ---
>>  drivers/crypto/caam/caamalg.c | 26 ++++++++++++++++++++++++--
>>  1 file changed, 24 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/crypto/caam/caamalg.c b/drivers/crypto/caam/caamalg.c
>> index 398807d1b77e..d13c1aee4427 100644
>> --- a/drivers/crypto/caam/caamalg.c
>> +++ b/drivers/crypto/caam/caamalg.c
>> @@ -882,10 +882,11 @@ static void ablkcipher_encrypt_done(struct device *jrdev, u32 *desc, u32 err,
>>  {
>>  	struct ablkcipher_request *req = context;
>>  	struct ablkcipher_edesc *edesc;
>> -#ifdef DEBUG
>>  	struct crypto_ablkcipher *ablkcipher = crypto_ablkcipher_reqtfm(req);
>>  	int ivsize = crypto_ablkcipher_ivsize(ablkcipher);
>> +	int nents;
>>  
>> +#ifdef DEBUG
>>  	dev_err(jrdev, "%s %d: err 0x%x\n", __func__, __LINE__, err);
>>  #endif
>>  
>> @@ -904,6 +905,19 @@ static void ablkcipher_encrypt_done(struct device *jrdev, u32 *desc, u32 err,
>>  #endif
[snip]
>> +	sg_pcopy_to_buffer(req->dst, nents, req->info, ivsize,
>> +			   req->nbytes - ivsize);
> 
> scatterwalk_map_and_copy() should be used instead.
> 
David, IIUC this is the only change needed in this patch (applies both
for encryption and decryption, of course).
Will you formally resubmit?

Thanks,
Horia