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

[Thomas Backlund]

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

--
Thomas

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