On Tue, Feb 27, 2018 at 09:05:01AM +0100, Michal Kubecek wrote: > 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 <[email protected]> > > > > 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: > > <xmit on ip6_tunnel> > > <cache lookup fails> > > dst = ip6_route_output(...) > > <tunnel params are changed via nl> > > 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 <[email protected]> > > Suggested-and-acked-by: Hannes Frederic Sowa <[email protected]> > > Signed-off-by: David S. Miller <[email protected]> > > Signed-off-by: Manoj Boopathi Raj <[email protected]> > > Signed-off-by: Greg Kroah-Hartman <[email protected]> > > > > --- > ... > > --- 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)?
Hm, I don't really know, it seems to be correct to me... Manoj, any ideas? You did this backport. thanks, greg k-h
