linux-kernel - Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems

lists.openwall.net		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 linux-cve-announce 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]

Message-ID: <524C2FDB.4080203@redhat.com>
Date:	Wed, 02 Oct 2013 16:38:19 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Alexander Graf <agraf@...e.de>
CC:	Michael Ellerman <michael@...erman.id.au>,
	Gleb Natapov <gleb@...hat.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	linux-kernel@...r.kernel.org, mpm@...enic.com,
	herbert@...dor.hengli.com.au, linuxppc-dev@...abs.org,
	kvm@...r.kernel.org, kvm-ppc@...r.kernel.org, tytso@....edu
Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on
 some powernv systems

Il 02/10/2013 16:36, Alexander Graf ha scritto:
>> > 
>> > With Michael's earlier patch in this series, the hwrng is accessible by
>> > host userspace via /dev/hwrng, no?
> Yes, but there's not token from user space that gets passed into the
> kernel to check whether access is ok or not. So while QEMU may not have
> permission to open /dev/hwrng it could spawn a guest that opens it,
> drains all entropy out of it and thus stall other processes which try to
> fetch entropy, no?
> 
> Maybe I haven't fully grasped the interface yet though :).

Yes, that's right.  I don't think it's a huge problem, but it's another
point in favor of just doing the hypercall in userspace.

Paolo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/