This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: Building consensus over DNSSEC enhancements to glibc.
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: Paul Wouters <pwouters at redhat dot com>, Rich Felker <dalias at libc dot org>, Simo Sorce <simo at redhat dot com>
- Cc: Petr Spacek <pspacek at redhat dot com>, libc-alpha at sourceware dot org
- Date: Tue, 17 Nov 2015 14:04:34 -0500
- Subject: Re: Building consensus over DNSSEC enhancements to glibc.
- Authentication-results: sourceware.org; auth=none
- References: <563CED63 dot 1070201 at redhat dot com> <20151106182835 dot GC3818 at brightrain dot aerifal dot cx> <563D0953 dot 9020707 at redhat dot com> <56407C19 dot 2080906 at redhat dot com> <20151109180310 dot GO3818 at brightrain dot aerifal dot cx> <5649A3F3 dot 2060309 at redhat dot com> <20151116161642 dot GQ3818 at brightrain dot aerifal dot cx> <564A0FED dot 9010408 at redhat dot com> <20151116181740 dot GS3818 at brightrain dot aerifal dot cx> <564A1E3E dot 5090703 at redhat dot com> <20151116182322 dot GU3818 at brightrain dot aerifal dot cx> <564AB3F9 dot 4020404 at redhat dot com> <564AC146 dot 1040305 at redhat dot com> <564AD51D dot 4040100 at redhat dot com> <564AE333 dot 9090200 at redhat dot com>
On 11/17/2015 03:20 AM, Paul Wouters wrote:
> On 11/17/2015 04:19 PM, Carlos O'Donell wrote:
>
>>> If that is the only API to be offered, I recommend we patch the
>>> applications with the "postfix method" instead and for now limit
>>> ourselves with dnssec only if localhost is specified in resolv.conf.
>>
>> Why? It will never be enough to guarantee what you want. Such a check
>> is only a heuristic.
>>
>> If you want something more sane we could make a synthetic hwcap bit
>> like we did for Xen's "nosegneg" and use that to alter the behaviour
>> of the stub resolver. This gives you something which would allow you
>> to lock down the called recursive resolver from the very first userspace
>> process. It could also be disabled on a per-process basis if you had
>> a kernel interface for it. We have also had a thread local storage
>> synthetic hwcap bit when we transitioned to using that feature, so
>> there is some precedent.
>>
>> So you'd have:
>>
>> (a) New synthetic hwcap bit "local-validating-resolver" which forces
>> glibc to only talk to 127.0.0.1 from the very first userspace process.
>>
>> (b) New options flag "dns-strip-dnssec-ad-bit" which forces glibc to
>> remove AD-bit data.
>>
>> Mix-and-match.
>
> That still does not do fail safe.
Thanks for bringing that up again.
So I am willing to concede flipping the meaning of (b) and defaulting
to always stripping AD-bit if that means we have consensus for a way
forward.
I have background work in the Nuclear industry in Canada and I know
what fail safe means and the value it provides. Both from a certification
*and* usability perspective.
Cheers,
Carlos.