[PATCH] net: lwip: Change https entropy requests

[Ilias Apalodimas]

Hi Jerome,

On Thu, 14 Nov 2024 at 10:48, Jerome Forissier
<jerome.forissier at linaro.org> wrote:
>
>
>
> On 11/14/24 08:35, Ilias Apalodimas wrote:
> > mbedTLS requires some randomess in order to setup a TLS conection.
>
> MBed TLS, randomness, connection
>
> > Since we don't have known APIs -- e.g /dev/urandom, we must define
> > our own function which mbedTLS uses.
> > The crypto library will call that function recursively until it gets all
>
> s/recursively/repeatedly/
>
> > the randomness it needs. Instead of doing it in 8b chunks fill in whatever
> > mbedTLS asks for in one call.
> >
> > It's worth noting that 'len' in this function is controlled by mbedTLS
> > at build-time options and currently defaults to 128b.
>
> The description does not reflect well what the patch does and why IMO.
> The function already exists, there is no need to explain that. How about:
>
> ===
> net: lwip: provide entropy to MBed TLS in one go
>
> Take into account the 'len' parameter passed by MBed TLS to the entropy
> gathering function instead of doing 8-byte chunks. Note that the current
> code works because len is always 16 (defined at compile time), therefore
> mbedtls_hardware_poll() is called twice and the buffer is filled
> exactly. But passing 'len' to dm_rng_read() is both more correct and
> simpler.

Sure, I can send a v2, with a minor change, len is 128 currently not 16

Thanks
/Ilias
> ===
>
> >
> > Suggested-by: Simon Glass <sjg at chromium.org>
> > Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> > ---
> >  net/lwip/wget.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
>
> With or without an re-worded description:
>
> Reviewed-by: Jerome Forissier <jerome.forissier at linaro.org>
>
> Thanks,
> --
> Jerome
>
> >
> > diff --git a/net/lwip/wget.c b/net/lwip/wget.c
> > index ba8579899002..4fd552fd306e 100644
> > --- a/net/lwip/wget.c
> > +++ b/net/lwip/wget.c
> > @@ -42,7 +42,6 @@ int mbedtls_hardware_poll(void *data, unsigned char *output, size_t len,
> >                         size_t *olen)
> >  {
> >       struct udevice *dev;
> > -     u64 rng = 0;
> >       int ret;
> >
> >       *olen = 0;
> > @@ -52,12 +51,11 @@ int mbedtls_hardware_poll(void *data, unsigned char *output, size_t len,
> >               log_err("Failed to get an rng: %d\n", ret);
> >               return ret;
> >       }
> > -     ret = dm_rng_read(dev, &rng, sizeof(rng));
> > +     ret = dm_rng_read(dev, output, len);
> >       if (ret)
> >               return ret;
> >
> > -     memcpy(output, &rng, len);
> > -     *olen = sizeof(rng);
> > +     *olen = len;
> >
> >       return 0;
> >  }