| Message ID | 20200706174507.18556-1-dsahern@kernel.org |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v2,net] ipv6: fib6_select_path can not use out path for nexthop objects | expand |
From: David Ahern <dsahern@kernel.org> Date: Mon, 6 Jul 2020 11:45:07 -0600 > Brian reported a crash in IPv6 code when using rpfilter with a setup > running FRR and external nexthop objects. The root cause of the crash > is fib6_select_path setting fib6_nh in the result to NULL because of > an improper check for nexthop objects. > > More specifically, rpfilter invokes ip6_route_lookup with flowi6_oif > set causing fib6_select_path to be called with have_oif_match set. > fib6_select_path has early check on have_oif_match and jumps to the > out label which presumes a builtin fib6_nh. This path is invalid for > nexthop objects; for external nexthops fib6_select_path needs to just > return if the fib6_nh has already been set in the result otherwise it > returns after the call to nexthop_path_fib6_result. Update the check > on have_oif_match to not bail on external nexthops. > > Update selftests for this problem. > > Fixes: f88d8ea67fbd ("ipv6: Plumb support for nexthop object in a fib6_info") > Reported-by: Brian Rak <brak@choopa.com> > Signed-off-by: David Ahern <dsahern@kernel.org> > --- > v2 > - for multipath nexthops path may already be set; do not want to > overwrite that selection based on hash Applied and queued up for -stable, thanks David.
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 82cbb46a2a4f..ea0be7cf3d93 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -431,9 +431,12 @@ void fib6_select_path(const struct net *net, struct fib6_result *res, struct fib6_info *sibling, *next_sibling; struct fib6_info *match = res->f6i; - if ((!match->fib6_nsiblings && !match->nh) || have_oif_match) + if (!match->nh && (!match->fib6_nsiblings || have_oif_match)) goto out; + if (match->nh && have_oif_match && res->nh) + return; + /* We might have already computed the hash for ICMPv6 errors. In such * case it will always be non-zero. Otherwise now is the time to do it. */ diff --git a/tools/testing/selftests/net/fib_nexthops.sh b/tools/testing/selftests/net/fib_nexthops.sh index dee567f7576a..22dc2f3d428b 100755 --- a/tools/testing/selftests/net/fib_nexthops.sh +++ b/tools/testing/selftests/net/fib_nexthops.sh @@ -747,6 +747,19 @@ ipv6_fcnal_runtime() run_cmd "$IP nexthop add id 86 via 2001:db8:91::2 dev veth1" run_cmd "$IP ro add 2001:db8:101::1/128 nhid 81" + # rpfilter and default route + $IP nexthop flush >/dev/null 2>&1 + run_cmd "ip netns exec me ip6tables -t mangle -I PREROUTING 1 -m rpfilter --invert -j DROP" + run_cmd "$IP nexthop add id 91 via 2001:db8:91::2 dev veth1" + run_cmd "$IP nexthop add id 92 via 2001:db8:92::2 dev veth3" + run_cmd "$IP nexthop add id 93 group 91/92" + run_cmd "$IP -6 ro add default nhid 91" + run_cmd "ip netns exec me ping -c1 -w1 2001:db8:101::1" + log_test $? 0 "Nexthop with default route and rpfilter" + run_cmd "$IP -6 ro replace default nhid 93" + run_cmd "ip netns exec me ping -c1 -w1 2001:db8:101::1" + log_test $? 0 "Nexthop with multipath default route and rpfilter" + # TO-DO: # existing route with old nexthop; append route with new nexthop # existing route with old nexthop; replace route with new
Brian reported a crash in IPv6 code when using rpfilter with a setup running FRR and external nexthop objects. The root cause of the crash is fib6_select_path setting fib6_nh in the result to NULL because of an improper check for nexthop objects. More specifically, rpfilter invokes ip6_route_lookup with flowi6_oif set causing fib6_select_path to be called with have_oif_match set. fib6_select_path has early check on have_oif_match and jumps to the out label which presumes a builtin fib6_nh. This path is invalid for nexthop objects; for external nexthops fib6_select_path needs to just return if the fib6_nh has already been set in the result otherwise it returns after the call to nexthop_path_fib6_result. Update the check on have_oif_match to not bail on external nexthops. Update selftests for this problem. Fixes: f88d8ea67fbd ("ipv6: Plumb support for nexthop object in a fib6_info") Reported-by: Brian Rak <brak@choopa.com> Signed-off-by: David Ahern <dsahern@kernel.org> --- v2 - for multipath nexthops path may already be set; do not want to overwrite that selection based on hash net/ipv6/route.c | 5 ++++- tools/testing/selftests/net/fib_nexthops.sh | 13 +++++++++++++ 2 files changed, 17 insertions(+), 1 deletion(-)