From 35f1b4e96b9258a3668872b1139c51e5a23eb876 Mon Sep 17 00:00:00 2001 From: Michal Kubeček Date: Mon, 18 May 2015 20:53:55 +0200 Subject: ipv6: do not delete previously existing ECMP routes if add fails If adding a nexthop of an IPv6 multipath route fails, comment in ip6_route_multipath() says we are going to delete all nexthops already added. However, current implementation deletes even the routes it hasn't even tried to add yet. For example, running ip route add 1234:5678::/64 \ nexthop via fe80::aa dev dummy1 \ nexthop via fe80::bb dev dummy1 \ nexthop via fe80::cc dev dummy1 twice results in removing all routes first command added. Limit the second (delete) run to nexthops that succeeded in the first (add) run. Fixes: 51ebd3181572 ("ipv6: add support of equal cost multipath (ECMP)") Signed-off-by: Michal Kubecek Acked-by: Nicolas Dichtel Signed-off-by: David S. Miller --- net/ipv6/route.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index d3588885f097..3821a3517478 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -2504,9 +2504,9 @@ static int ip6_route_multipath(struct fib6_config *cfg, int add) int attrlen; int err = 0, last_err = 0; + remaining = cfg->fc_mp_len; beginning: rtnh = (struct rtnexthop *)cfg->fc_mp; - remaining = cfg->fc_mp_len; /* Parse a Multipath Entry */ while (rtnh_ok(rtnh, remaining)) { @@ -2536,6 +2536,7 @@ beginning: * next hops that have been already added. */ add = 0; + remaining = cfg->fc_mp_len - remaining; goto beginning; } } -- cgit v1.2.3 From 27596472473a02cfef2908a6bcda7e55264ba6b7 Mon Sep 17 00:00:00 2001 From: Michal Kubeček Date: Mon, 18 May 2015 20:54:00 +0200 Subject: ipv6: fix ECMP route replacement When replacing an IPv6 multipath route with "ip route replace", i.e. NLM_F_CREATE | NLM_F_REPLACE, fib6_add_rt2node() replaces only first matching route without fixing its siblings, resulting in corrupted siblings linked list; removing one of the siblings can then end in an infinite loop. IPv6 ECMP implementation is a bit different from IPv4 so that route replacement cannot work in exactly the same way. This should be a reasonable approximation: 1. If the new route is ECMP-able and there is a matching ECMP-able one already, replace it and all its siblings (if any). 2. If the new route is ECMP-able and no matching ECMP-able route exists, replace first matching non-ECMP-able (if any) or just add the new one. 3. If the new route is not ECMP-able, replace first matching non-ECMP-able route (if any) or add the new route. We also need to remove the NLM_F_REPLACE flag after replacing old route(s) by first nexthop of an ECMP route so that each subsequent nexthop does not replace previous one. Fixes: 51ebd3181572 ("ipv6: add support of equal cost multipath (ECMP)") Signed-off-by: Michal Kubecek Acked-by: Nicolas Dichtel Signed-off-by: David S. Miller --- net/ipv6/ip6_fib.c | 39 +++++++++++++++++++++++++++++++++++++-- net/ipv6/route.c | 11 +++++++---- 2 files changed, 44 insertions(+), 6 deletions(-) diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 96dbffff5a24..bde57b113009 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -693,6 +693,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt, { struct rt6_info *iter = NULL; struct rt6_info **ins; + struct rt6_info **fallback_ins = NULL; int replace = (info->nlh && (info->nlh->nlmsg_flags & NLM_F_REPLACE)); int add = (!info->nlh || @@ -716,8 +717,13 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt, (info->nlh->nlmsg_flags & NLM_F_EXCL)) return -EEXIST; if (replace) { - found++; - break; + if (rt_can_ecmp == rt6_qualify_for_ecmp(iter)) { + found++; + break; + } + if (rt_can_ecmp) + fallback_ins = fallback_ins ?: ins; + goto next_iter; } if (iter->dst.dev == rt->dst.dev && @@ -753,9 +759,17 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt, if (iter->rt6i_metric > rt->rt6i_metric) break; +next_iter: ins = &iter->dst.rt6_next; } + if (fallback_ins && !found) { + /* No ECMP-able route found, replace first non-ECMP one */ + ins = fallback_ins; + iter = *ins; + found++; + } + /* Reset round-robin state, if necessary */ if (ins == &fn->leaf) fn->rr_ptr = NULL; @@ -815,6 +829,8 @@ add: } } else { + int nsiblings; + if (!found) { if (add) goto add; @@ -835,8 +851,27 @@ add: info->nl_net->ipv6.rt6_stats->fib_route_nodes++; fn->fn_flags |= RTN_RTINFO; } + nsiblings = iter->rt6i_nsiblings; fib6_purge_rt(iter, fn, info->nl_net); rt6_release(iter); + + if (nsiblings) { + /* Replacing an ECMP route, remove all siblings */ + ins = &rt->dst.rt6_next; + iter = *ins; + while (iter) { + if (rt6_qualify_for_ecmp(iter)) { + *ins = iter->dst.rt6_next; + fib6_purge_rt(iter, fn, info->nl_net); + rt6_release(iter); + nsiblings--; + } else { + ins = &iter->dst.rt6_next; + } + iter = *ins; + } + WARN_ON(nsiblings != 0); + } } return 0; diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 3821a3517478..c73ae5039e46 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -2541,11 +2541,14 @@ beginning: } } /* Because each route is added like a single route we remove - * this flag after the first nexthop (if there is a collision, - * we have already fail to add the first nexthop: - * fib6_add_rt2node() has reject it). + * these flags after the first nexthop: if there is a collision, + * we have already failed to add the first nexthop: + * fib6_add_rt2node() has rejected it; when replacing, old + * nexthops have been replaced by first new, the rest should + * be added to it. */ - cfg->fc_nlinfo.nlh->nlmsg_flags &= ~NLM_F_EXCL; + cfg->fc_nlinfo.nlh->nlmsg_flags &= ~(NLM_F_EXCL | + NLM_F_REPLACE); rtnh = rtnh_next(rtnh, &remaining); } -- cgit v1.2.3