Re: [PATCH v4 12/13] bluetooth/smp: ensure RNG is properly seeded before ECDH use

From	Marcel Holtmann <marcel@holtmann.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 12/13] bluetooth/smp: ensure RNG is properly seeded before ECDH use
Date	2017-06-08 19:10 +0200
Message-ID	<tQ96x-73e-13@gated-at.bofh.it> (permalink)
References	<tPqM9-3tE-3@gated-at.bofh.it> <tPqMa-3tE-27@gated-at.bofh.it> <tPVZD-76l-9@gated-at.bofh.it> <tPXRL-8na-5@gated-at.bofh.it> <tQ4qe-45j-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

Hi Jason,

>> yes, there are plenty of commands needed before a controller becomes usable.
> 
> That doesn't clearly address with precision what Ted was wondering.
> Specifically, the inquiry is: can you confirm with certainty whether
> or not all calls to get_random_bytes() in the bluetooth directory are
> *necessarily* going to come after a call to hci_power_on()?

on a powered down controller, you can not do any crypto. SMP is only during a connection and the RPAs are only generated when needed. So yes, doing this once in hci_power_on is plenty. However we might want to limit this to LE capable controllers since for BR/EDR only controllers this is not needed. For A2MP I need to check that we need the random numbers seeded there. However this hidden behind the high speed feature.

Regards

Marcel

Thread

Re: [PATCH v4 12/13] bluetooth/smp: ensure RNG is properly seeded  before ECDH use Theodore Ts'o <tytso@mit.edu> - 2017-06-08 05:10 +0200
  Re: [PATCH v4 12/13] bluetooth/smp: ensure RNG is properly seeded  before ECDH use Marcel Holtmann <marcel@holtmann.org> - 2017-06-08 07:10 +0200
    Re: [PATCH v4 12/13] bluetooth/smp: ensure RNG is properly seeded  before ECDH use "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-08 14:10 +0200
    Re: [PATCH v4 12/13] bluetooth/smp: ensure RNG is properly seeded  before ECDH use "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-08 14:10 +0200
      Re: [PATCH v4 12/13] bluetooth/smp: ensure RNG is properly seeded  before ECDH use Marcel Holtmann <marcel@holtmann.org> - 2017-06-08 19:10 +0200
        Re: [PATCH v4 12/13] bluetooth/smp: ensure RNG is properly seeded  before ECDH use "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-08 19:40 +0200
          [PATCH] bluetooth: ensure RNG is properly seeded before powerup "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-09 03:20 +0200

csiph-web