On 9/25/18 3:25 AM, Ard Biesheuvel wrote:
> On Mon, 24 Sep 2018 at 19:53, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>>
>> On Mon, Sep 24, 2018 at 4:52 AM, Ard Biesheuvel
>> <ard.biesheuvel@xxxxxxxxxx> wrote:
>>> On Wed, 19 Sep 2018 at 04:11, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>>>> @@ -119,7 +119,7 @@ cryptoloop_transfer(struct loop_device *lo, int cmd,
>>>> unsigned in_offs, out_offs;
>>>> int err;
>>>>
>>>> - skcipher_request_set_tfm(req, tfm);
>>>> + skcipher_request_set_sync_tfm(req, tfm);
>>>> skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
>>>> NULL, NULL);
>>>>
>>>
>>> Does this work?
>>
>> Everything is a direct wrapper for existing types and functions, so I
>> wouldn't expect any functional change. I haven't been able to test
>> this particular interface, though. cryptoloop is very deprecated,
>> isn't it?
>>
>
> Ah yes, I managed to confuse myself there. This looks all fine to me.
>
> In any case, this is another example where we may decide to fix the
> code rather than retain the request allocation on the stack (but that
> is Jens's call ultimately, I suppose)
>
> diff --git a/drivers/block/cryptoloop.c b/drivers/block/cryptoloop.c
> index 7033a4beda66..5ed2167219ba 100644
> --- a/drivers/block/cryptoloop.c
> +++ b/drivers/block/cryptoloop.c
> @@ -110,7 +110,7 @@ cryptoloop_transfer(struct loop_device *lo, int cmd,
> int size, sector_t IV)
> {
> struct crypto_skcipher *tfm = lo->key_data;
> - SKCIPHER_REQUEST_ON_STACK(req, tfm);
> + struct skcipher_request *req;
> struct scatterlist sg_out;
> struct scatterlist sg_in;
>
> @@ -119,7 +119,10 @@ cryptoloop_transfer(struct loop_device *lo, int cmd,
> unsigned in_offs, out_offs;
> int err;
>
> - skcipher_request_set_tfm(req, tfm);
> + req = skcipher_request_alloc(tfm, GFP_NOIO);
> + if (!req)
> + return -ENOMEM;
Is this going to be reliable? ->transfer() is called when we're doing IO,
and you'd normally need a mempool backed allocation to make this safe
and guarantee forward progress.
--
Jens Axboe
