From: Eric Dumazet <eric.dumazet@gmail•com>
To: David Ahern <dsahern@gmail•com>,
Casey Schaufler <casey@schaufler-ca•com>,
James Morris <james.l.morris@oracle•com>
Cc: Paul Moore <paul@paul-moore•com>,
netdev@vger•kernel.org, Stephen Smalley <sds@tycho•nsa.gov>,
selinux@tycho•nsa.gov,
LSM <linux-security-module@vger•kernel.org>
Subject: Re: [BUG] kernel stack corruption during/after Netlabel error
Date: Thu, 30 Nov 2017 09:57:09 -0800 [thread overview]
Message-ID: <1512064629.19682.21.camel@gmail.com> (raw)
In-Reply-To: <d29937fd-dd04-8568-f89c-505ff725761a@gmail.com>
On Thu, 2017-11-30 at 10:30 -0700, David Ahern wrote:
> On 11/30/17 8:44 AM, David Ahern wrote:
> > On 11/30/17 3:50 AM, Eric Dumazet wrote:
> > > @@ -1631,24 +1659,6 @@ int tcp_v4_rcv(struct sk_buff *skb)
> > >
> > > th = (const struct tcphdr *)skb->data;
> > > iph = ip_hdr(skb);
> > > - /* This is tricky : We move IPCB at its correct location
> > > into TCP_SKB_CB()
> > > - * barrier() makes sure compiler wont play
> > > fool^Waliasing games.
> > > - */
> > > - memmove(&TCP_SKB_CB(skb)->header.h4, IPCB(skb),
> > > - sizeof(struct inet_skb_parm));
> > > - barrier();
> > > -
> > > - TCP_SKB_CB(skb)->seq = ntohl(th->seq);
> > > - TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th-
> > > >syn + th->fin +
> > > - skb->len - th->doff * 4);
> > > - TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
> > > - TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
> > > - TCP_SKB_CB(skb)->tcp_tw_isn = 0;
> > > - TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
> > > - TCP_SKB_CB(skb)->sacked = 0;
> > > - TCP_SKB_CB(skb)->has_rxtstamp =
> > > - skb->tstamp || skb_hwtstamps(skb)-
> > > >hwtstamp;
> > > -
> > > lookup:
> > > sk = __inet_lookup_skb(&tcp_hashinfo, skb,
> > > __tcp_hdrlen(th), th->source,
> > > th->dest, sdif, &refcounted);
> >
> > I believe moving the above is going to affect lookups with VRF. Let
> > me
> > take a look before this gets committed.
> >
>
> Eric:
>
> Can you add this to the patch? Fixes socket lookups with VRF which
> stashes a flag in the cb.
>
> Thanks,
>
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index 4e09398009c1..6c020015d556 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -849,7 +849,7 @@ static inline bool inet_exact_dif_match(struct
> net
> *net, struct sk_buff *skb)
> {
> #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
> if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
> - skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
> + skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
> return true;
> #endif
> return false;
I wonder if this should not be in a separate patch ?
Bug was added in 971f10eca186cab238c49daa91f703c5a001b0b1 ("tcp: better
TCP_SKB_CB layout to reduce cache line misses") in linux 3.18
While VRF was added later.
If you agree, I will prepare a patch series, with different Fixes tag
so that David can decide which path needs to be backported into each
stable version.
Thanks.
next prev parent reply other threads:[~2017-11-30 17:57 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-29 10:26 [BUG] kernel stack corruption during/after Netlabel error James Morris
2017-11-29 12:29 ` Eric Dumazet
2017-11-29 17:31 ` Stephen Smalley
2017-11-29 17:34 ` Eric Dumazet
2017-11-29 19:29 ` Paul Moore
[not found] ` <CANn89iJc=tZkN41WoCm5Zy9nPfs1tfZf9nuSXYS9EB_aem+y4g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-11-29 19:59 ` Stephen Smalley
2017-11-29 20:23 ` Eric Dumazet
2017-11-29 22:49 ` Eric Dumazet
2017-11-29 23:41 ` James Morris
2017-11-30 0:22 ` Casey Schaufler
2017-11-30 0:31 ` James Morris
2017-11-30 3:16 ` Casey Schaufler
2017-11-30 10:50 ` Eric Dumazet
2017-11-30 12:47 ` Paul Moore
2017-11-30 16:57 ` Paul Moore
2017-11-30 14:33 ` Casey Schaufler
2017-11-30 15:11 ` Casey Schaufler
2017-11-30 15:44 ` David Ahern
2017-11-30 17:30 ` David Ahern
2017-11-30 17:57 ` Eric Dumazet [this message]
2017-11-30 18:03 ` David Ahern
2017-11-30 18:16 ` Casey Schaufler
2017-12-01 1:55 ` James Morris
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