svn commit: r359797 - in head/sys: net netinet netinet6

[Conrad Meyer]

On Sat, Apr 11, 2020 at 1:45 PM Alexander V. Chernikov
<melifaro at freebsd.org> wrote:
> This number only affects selection of the outbound path in presence of multiple paths available for the same prefix. It means to mitigate hash polarization in the network ( https://www.cisco.com/c/en/us/support/docs/ip/express-forwarding-cef/116376-technote-cef-00.html contains somewhat relevant description).
> I don't think it that knowing the number make DoSing of the particular system easier.

Thanks!  Does it need to be stable over time, or would it be
acceptable to be updated at some point?

> However, better quality randomness is always good.
> Speaking of "when" it is needed - you're right, it is needed pretty late in the boot process, after the userland starts.
> Will moving the order to SI_SUB_LAST help or I need to trigger number generation by different means?

SI_SUB_LAST is better, sure.  If you want to ensure you eventually get
a random number, and changing the number at runtime is acceptable, you
could have userspace induce seeding.  But maybe that is unnecessarily
complex.  Typical x86 systems using loader will have good entropy
available already at this point, outside of the installer or if there
is /boot corruption.

(It sounds like this application would be fine with not really random
numbers, at least early in boot.  We don't have a great API for that
need today, unfortunately.)

Cheers,
Conrad