Messages in this thread | | | From | Stephan Mueller <> | Subject | Re: [PATCH 3/3] hwrng: msm - Add support for prng v2 | Date | Wed, 27 Jun 2018 08:13:34 +0200 |
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Am Mittwoch, 27. Juni 2018, 07:08:53 CEST schrieb Vinod:
Hi Vinod,
> Thanks for the pointers, it helped me to test the driver :) > > I have two follow up question on crypto: > > - If there a way to avoid using a global variable in driver to hold the > pointer for driver memory? Looks like exynos driver does that. > > I understand that the crypto callback don't provide driver context as > they copy the data structures passed in registration API, but a simpler > way to get driver context would be desirable.
Sure the kernel crypto API can and has to maintain a per-instance data structure.
See the crypto/drbg.c for instance.
static int drbg_kcapi_random(struct crypto_rng *tfm, const u8 *src, unsigned int slen, u8 *dst, unsigned int dlen) { struct drbg_state *drbg = crypto_rng_ctx(tfm);
static int drbg_kcapi_seed(struct crypto_rng *tfm, const u8 *seed, unsigned int slen) { struct drbg_state *drbg = crypto_rng_ctx(tfm);
The key is:
alg->base.cra_ctxsize = sizeof(struct drbg_state);
during initialization since the kernel crypto API allocates that buffer for you and releases it during deallocation. > > - .seed seems to be mandatory, if I do not set it and even use > .seedsize = 0, it panics at crypto_rng_reset(). So is .seed > mandatory?
Well, seedsize = 0 just says that the RNG is ready to use after initialization (i.e. it does not need to be seeded after initialization).
That does not preclude that a caller wants to reseed.
And yes, .seed must be set. > > Thanks
Ciao Stephan
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