Re: [PATCH 3.19 176/177] netfilter: x_tables: fix cgroup matching on non-full sks

[Greg Kroah-Hartman]

On Sun, May 03, 2015 at 12:47:17AM +0300, Thomas Backlund wrote:
> Den 02.05.2015 22:03, Greg Kroah-Hartman skrev:
> >3.19-stable review patch.  If anyone has any objections, please let me know.
> >
> >------------------
> >
> >From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> >
> >commit afb7718016fcb0370ac29a83b2839c78b76c2960 upstream.
> >
> >While originally only being intended for outgoing traffic, commit
> >a00e76349f35 ("netfilter: x_tables: allow to use cgroup match for
> >LOCAL_IN nf hooks") enabled xt_cgroups for the NF_INET_LOCAL_IN hook
> >as well, in order to allow for nfacct accounting.
> >
> >Besides being currently limited to early demuxes only, commit
> >a00e76349f35 forgot to add a check if we deal with full sockets,
> >i.e. in this case not with time wait sockets. TCP time wait sockets
> >do not have the same memory layout as full sockets, a lower memory
> >footprint and consequently also don't have a sk_classid member;
> >probing for sk_classid member there could potentially lead to a
> >crash.
> >
> >Fixes: a00e76349f35 ("netfilter: x_tables: allow to use cgroup match for LOCAL_IN nf hooks")
> >Cc: Alexey Perevalov <a.perevalov@xxxxxxxxxxx>
> >Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> >Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
> >Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> >
> >---
> >  net/netfilter/xt_cgroup.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >--- a/net/netfilter/xt_cgroup.c
> >+++ b/net/netfilter/xt_cgroup.c
> >@@ -39,7 +39,7 @@ cgroup_mt(const struct sk_buff *skb, str
> >  {
> >  	const struct xt_cgroup_info *info = par->matchinfo;
> >
> >-	if (skb->sk == NULL)
> >+	if (skb->sk == NULL || !sk_fullsock(skb->sk))
> >  		return false;
> >
> >  	return (info->id == skb->sk->sk_classid) ^ info->invert;
> >
> >
> 
> 
> This one breaks the build with:
> 
> net/netfilter/xt_cgroup.c: In function 'cgroup_mt':
> net/netfilter/xt_cgroup.c:42:2: error: implicit declaration of function
> 'sk_fullsock' [-Werror=implicit-function-declaration]
> 
> 
> In order to fix it, you also need to add:
> 
> From 1d0ab253872cdd3d8e7913f59c266c7fd01771d0 Mon Sep 17 00:00:00 2001
> From: Eric Dumazet <edumazet@xxxxxxxxxx>
> Date: Sun, 15 Mar 2015 21:12:12 -0700
> Subject: [PATCH] net: add sk_fullsock() helper
> 
> 
> which in turn needs this one:
> 
> From 10feb428a5045d5eb18a5d755fbb8f0cc9645626 Mon Sep 17 00:00:00 2001
> From: Eric Dumazet <edumazet@xxxxxxxxxx>
> Date: Thu, 12 Mar 2015 16:44:04 -0700
> Subject: [PATCH] inet: add TCP_NEW_SYN_RECV state

I've just dropped the patch, thanks for letting me know, odd that my
build tests missed it.

thanks,

greg k-h
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