From: Paul LeoNerd Evans <leonerd@leonerd.org.uk>
To: Hagen Paul Pfeifer <hagen@jauu.net>, netdev@vger.kernel.org
Cc: David Miller <davem@davemloft.net>
Subject: Re: RFC: New BGF 'LOOP' instruction
Date: Tue, 3 Aug 2010 14:40:44 +0100 [thread overview]
Message-ID: <20100803134044.GR11110@cel.leo> (raw)
In-Reply-To: <6809423e656a160df11216ea5acc3d8b@localhost>
[-- Attachment #1: Type: text/plain, Size: 1812 bytes --]
On Tue, Aug 03, 2010 at 11:10:28AM +0200, Hagen Paul Pfeifer wrote:
> >> Rightnow, BPF is all but useless for parsing, say, IPv6. I only pick
> >> IPv6 as one example, I'm sure there must exist a great number more
> >> packet-based protocols that use a "linked-list" style approach to
> >> headers. None of those are currently filterable on the current set of
> >> instructions. LOOP would allow these.
> >
> > It's not meant for detailed packet protocol header analysis,
> > it's for stateless straight line matching of masked values
> > in packet headers.
>
> David is right, BPF cannot - and will not - keep with any high level
> connection tracking packet filter. There is an processing trade-off between
> packet classification and packet storage with post processing analysis.
This has nothing to do with high-level connection tracking.
I want to accept all (IPv4 or IPv6) TCP packets concerning port 80.
That's all. No connection tracking. Simply a "stateless straight line
matching of masked values in packet headers". Namely, the TCP source or
destination ports, being 80.
Should BPF be allowed to implement such a filter?
This is the core question.
If yes, then we either need LOOP, or alternatively my SKF_AD_TRANSPROTO
/ SKF_TRANS_OFF idea (see the other thread fork). Without either LOOP or
TRANSPROTO, it becomes next-to-impossible to -find- the TCP header in an
IPv6 packet, and hence make filtering decisions based on it.
If no, please justify what BPF -is- for then, given that right now
applications like tcpdump/libpcap already use it for this very purpose.
Please further justify why BPF has the "LDX MSH" instruction
--
Paul "LeoNerd" Evans
leonerd@leonerd.org.uk
ICQ# 4135350 | Registered Linux# 179460
http://www.leonerd.org.uk/
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 190 bytes --]
next prev parent reply other threads:[~2010-08-03 13:40 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-02 11:03 RFC: New BGF 'LOOP' instruction Paul LeoNerd Evans
2010-08-02 11:13 ` RFC: New BPF " Paul LeoNerd Evans
2010-08-02 20:16 ` RFC: New BGF " Hagen Paul Pfeifer
2010-08-03 5:18 ` David Miller
2010-08-03 7:07 ` Paul LeoNerd Evans
2010-08-03 7:19 ` David Miller
2010-08-03 9:10 ` Hagen Paul Pfeifer
2010-08-03 13:40 ` Paul LeoNerd Evans [this message]
2010-08-03 9:03 ` Hagen Paul Pfeifer
2010-08-03 7:18 ` RFC: New BPF " Paul LeoNerd Evans
2010-08-03 5:13 ` RFC: New BGF " David Miller
2010-08-03 7:04 ` Paul LeoNerd Evans
2010-08-03 7:18 ` David Miller
2010-08-03 12:58 ` Andi Kleen
2010-08-03 13:07 ` David Miller
2010-08-03 13:34 ` RFC: New BPF " Paul LeoNerd Evans
2010-08-03 13:42 ` Paul LeoNerd Evans
2010-08-03 14:09 ` Rémi Denis-Courmont
2010-08-03 14:13 ` Paul LeoNerd Evans
2010-08-03 14:16 ` Rémi Denis-Courmont
2010-08-03 14:19 ` Paul LeoNerd Evans
2010-08-03 15:17 ` Rémi Denis-Courmont
2010-08-03 15:27 ` Paul LeoNerd Evans
2010-08-03 14:05 ` RFC: New BGF " Andi Kleen
2010-08-03 14:11 ` Paul LeoNerd Evans
2010-08-03 14:34 ` Paul LeoNerd Evans
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20100803134044.GR11110@cel.leo \
--to=leonerd@leonerd.org.uk \
--cc=davem@davemloft.net \
--cc=hagen@jauu.net \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).