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[209.132.180.67]) by mx.google.com with ESMTP id y7si6697590pgv.128.2018.02.27.00.05.46; Tue, 27 Feb 2018 00:06:01 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752089AbeB0IFF (ORCPT + 99 others); Tue, 27 Feb 2018 03:05:05 -0500 Received: from mx2.suse.de ([195.135.220.15]:56336 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751668AbeB0IFD (ORCPT ); Tue, 27 Feb 2018 03:05:03 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 3CB6BAD9E; Tue, 27 Feb 2018 08:05:02 +0000 (UTC) Received: by unicorn.suse.cz (Postfix, from userid 1000) id 79C4BA0991; Tue, 27 Feb 2018 09:05:01 +0100 (CET) Date: Tue, 27 Feb 2018 09:05:01 +0100 From: Michal Kubecek To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Paolo Abeni , "David S. Miller" , Manoj Boopathi Raj Subject: Re: [PATCH 4.4 002/193] net: replace dst_cache ip6_tunnel implementation with the generic one Message-ID: <20180227080500.p6truendtzuis7jb@unicorn.suse.cz> References: <20180223170325.997716448@linuxfoundation.org> <20180223170326.406395326@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180223170326.406395326@linuxfoundation.org> User-Agent: NeoMutt/20170421 (1.8.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 23, 2018 at 07:23:55PM +0100, Greg Kroah-Hartman wrote: > 4.4-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Paolo Abeni > > commit 607f725f6f7d5ec3759fbc16224afb60e2152a5b upstream. > > This also fix a potential race into the existing tunnel code, which > could lead to the wrong dst to be permanenty cached: > > CPU1: CPU2: > > > dst = ip6_route_output(...) > > dst_cache_reset() // no effect, > // the cache is empty > dst_cache_set() // the wrong dst > // is permanenty stored > // into the cache > > With the new dst implementation the above race is not possible > since the first cache lookup after dst_cache_reset will fail due > to the timestamp check > > Signed-off-by: Paolo Abeni > Suggested-and-acked-by: Hannes Frederic Sowa > Signed-off-by: David S. Miller > Signed-off-by: Manoj Boopathi Raj > Signed-off-by: Greg Kroah-Hartman > > --- ... > --- a/net/ipv6/ip6_gre.c > +++ b/net/ipv6/ip6_gre.c ... > @@ -1053,7 +962,6 @@ static int ip6_tnl_xmit2(struct sk_buff > struct ipv6_tel_txoption opt; > struct dst_entry *dst = NULL, *ndst = NULL; > struct net_device *tdev; > - bool use_cache = false; > int mtu; > unsigned int max_headroom = sizeof(struct ipv6hdr); > u8 proto; > @@ -1061,39 +969,28 @@ static int ip6_tnl_xmit2(struct sk_buff > > /* NBMA tunnel */ > if (ipv6_addr_any(&t->parms.raddr)) { > - if (skb->protocol == htons(ETH_P_IPV6)) { > - struct in6_addr *addr6; > - struct neighbour *neigh; > - int addr_type; > - > - if (!skb_dst(skb)) > - goto tx_err_link_failure; > - > - neigh = dst_neigh_lookup(skb_dst(skb), > - &ipv6_hdr(skb)->daddr); > - if (!neigh) > - goto tx_err_link_failure; > + struct in6_addr *addr6; > + struct neighbour *neigh; > + int addr_type; > + > + if (!skb_dst(skb)) > + goto tx_err_link_failure; > > - addr6 = (struct in6_addr *)&neigh->primary_key; > - addr_type = ipv6_addr_type(addr6); > + neigh = dst_neigh_lookup(skb_dst(skb), > + &ipv6_hdr(skb)->daddr); > + if (!neigh) > + goto tx_err_link_failure; > > - if (addr_type == IPV6_ADDR_ANY) > - addr6 = &ipv6_hdr(skb)->daddr; > + addr6 = (struct in6_addr *)&neigh->primary_key; > + addr_type = ipv6_addr_type(addr6); > > - memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr)); > - neigh_release(neigh); > - } > - } else if (t->parms.proto != 0 && !(t->parms.flags & > - (IP6_TNL_F_USE_ORIG_TCLASS | > - IP6_TNL_F_USE_ORIG_FWMARK))) { > - /* enable the cache only if neither the outer protocol nor the > - * routing decision depends on the current inner header value > - */ > - use_cache = true; > - } > + if (addr_type == IPV6_ADDR_ANY) > + addr6 = &ipv6_hdr(skb)->daddr; > > - if (use_cache) > - dst = ip6_tnl_dst_get(t); > + memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr)); > + neigh_release(neigh); > + } else if (!fl6->flowi6_mark) > + dst = dst_cache_get(&t->dst_cache); > > if (!ip6_tnl_xmit_ctl(t, &fl6->saddr, &fl6->daddr)) > goto tx_err_link_failure; > @@ -1156,8 +1053,8 @@ static int ip6_tnl_xmit2(struct sk_buff > skb = new_skb; > } > > - if (use_cache && ndst) > - ip6_tnl_dst_set(t, ndst); > + if (!fl6->flowi6_mark && ndst) > + dst_cache_set_ip6(&t->dst_cache, ndst, &fl6->saddr); > skb_dst_set(skb, dst); > > skb->transport_header = skb->network_header; This part looks essentially like a revert of earlier commit befb92542439 ("ipv6: check skb->protocol before lookup for nexthop", mainline 199ab00f3cdb). Is it possible that it comes from an incorrect resolution of the conflict caused by these two being backported in opposite order (befb92542439 < b8c7f80cbdcd) than the original mainline commits (607f725f6f7d < 199ab00f3cdb)? Michal Kubecek