Subject: Re: net/ipv6/exthdrs.c

From: Kis-Szabo Andras <[email-masked]>
Date: 19 Jun 2002 11:30:39 +0200

Hello,

> > Is there any plan to add the ESP header to the ipv6_ext_hdr() function (as a
> > known header)?
> No, ESP is not a normal extension header, it terminates parse.
> So, ipv6_skip_headers cannot skip it.
The same behaviour as in NONE, but the NONE is listed and the ESP is
not. (But it is not a problem to me, I just asked something :) )

> BTW the same is with netfilter. I do not see how are you going to use it. :-)
The ESP belongs to the headers, it is a member of a possible chain.
- header match - i had to search for the ESP, too
- ESP match - it has a public SPI value, which can be used in rules
- general iteration, skipped together with the NONE.
It terminates the header chain, but the existance of the ESP header and
its SPI value are usefull information.

> > (It requires changes in this file and in the icmp.c at the first round.)
> I am afraid this will simply break the function.
Yes, i am afraid You're right. :(
Adding the ESP to the headers will break the icmp code. :(

> This may be right even not depending on this issue. Goals are different:
> the function in exthdrs.c does the best efforts to guess what protocol
> is, the function in netfilter should be paranoid.
I added a similar function (exactly the same but with the ESP) to decide
about the nexthdr value and a new header parser/evaluator with strict
size/pointer checks.
Last week one of our user sent a direct request to eliminate the
duplicated functions - so He pushed me to send the original question to
this forum.

Thanks for the answers, I 'wrote up them'.

Regards,

	kisza

-- 
    Andras Kis-Szabo       Security Development, Design and Audit
-------------------------/        Zorp, NetFilter and IPv6
 [email-masked] /-----Member of the BUTE-MIS-SEARCHlab------>