netdev - Re: [v4 PATCH 1/2] NETFILTER module xt_hmark, new target for HASH based fwmark

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]

Date:	Thu, 01 Dec 2011 12:24:26 +0100
From:	Patrick McHardy <kaber@...sh.net>
To:	Hans Schillstrom <hans@...illstrom.com>
CC:	pablo@...filter.org, jengelh@...ozas.de,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
	hans.schillstrom@...csson.com
Subject: Re: [v4 PATCH 1/2] NETFILTER module xt_hmark, new target 	for HASH
 based fwmark

On 12/01/2011 12:05 PM, Hans Schillstrom wrote:
>>>> And final question, why not simply use ipv6_skip_exthdr()?
>>> problems with fragments...
>> So the probem is that it will return the transport layer protocol
>> header for fragments with frag_off == 0? We also have ipv6_find_hdr()
>> which we could modify to indicate this in the frag_off pointer.
> ipv6_find_hdr() will do the trick with a light modification
> What about a wrapper like:
>
> int __ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
> 		  int target, unsigned short *fragoff,  int *fragflg)
> {
> ...
> 		if (nexthdr == NEXTHDR_FRAGMENT) {
> 			unsigned short _frag_off;
> 			__be16 *fp;
>
> 			if (fragflg)
> 			        fragflg = 1;
> 			fp = skb_header_pointer(skb,
> 						start+offsetof(struct frag_hdr,
> 							       frag_off),
> 						sizeof(_frag_off),
> 						&_frag_off);
>
> ...
> }
>
> int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
> 		  int target, unsigned short *fragoff)
> {
>          return __ipv6_find_hdr(skb, offset, terget, fragoff, NULL);
> }

Hmm that would require to change all current callers. I was more
thinking of unconditionally setting *frag_off in case of
fragments, then you can initialize it to some impossible value
like 0xffff and determine the presence of a fragment header
based on its value after calling ipv6_find_hdr().

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html