lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Sun, 27 Jul 2014 16:53:23 -0700
From: (Eric W. Biederman)
To:	Andy Lutomirski <>
Cc:	Paolo Bonzini <>,,
	Henrique de Moraes Holschuh <>,
	"linux-kernel\" <>,
	James Morris <>,
	LSM List <>,
	Al Viro <>,
	Linux API <>,
	Julien Tinnes <>,
	"Theodore Ts'o" <>,
	Greg Kroah-Hartman <>,
	Paul Moore <>,
	David Drysdale <>,
	Kees Cook <>,
	Meredydd Luff <>,
	Christoph Hellwig <>
Subject: Re: General flags to turn things off (getrandom, pid lookup, etc)

Andy Lutomirski <> writes:

> On Jul 27, 2014 5:06 PM, "Theodore Ts'o" <> wrote:
>> On Fri, Jul 25, 2014 at 11:30:48AM -0700, Andy Lutomirski wrote:
>> >
>> > There is recent interest in having a way to turn generally-available
>> > kernel features off.  Maybe we should add a good one so we can stop
>> > bikeshedding and avoid proliferating dumb interfaces.
>> I believe the seccomp infrastructure (which is already upstream)
>> should be able to do most of what you want, at least with respect to
>> features which are exposed via system calls (which was most of your
>> list).
> Seccomp can't really restrict lookups of non-self pids.  In fact, this
> feature idea started out as a response to a patch adding a kind of
> nasty seccomp feature to make it sort of possible.
> I agree that that seccomp can turn off GRND_RANDOM, but how is it
> supposed to do it in such a way that the filtered software will fall
> back to something sensible?  -ENOSYS?  -EPERM?  Something else?
> I think that -ENOSYS is clearly wrong, but standardizing this would be
> nice.  Admittedly, adding something fancy like this for GRND_RANDOM
> may not be appropriate.

Andy you seem to be arguing here for two system calls.
get_urandom() and get_random().

Where get_urandom only blocks if there is not enough starting entropy,
and get_random(GRND_RANDOM) blocks if there is currently not enough

That would allow -ENOSYS to be the right return value and it would
simply things for everyone.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists