From 0ea0699ea01df81750becf742083933a23a95d94 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 4 Jul 2024 17:26:41 -0700 Subject: route: filter by interface on multipath routes The ip route command would silently hide multipath routes when filter by interface. The problem was it was not looking for interface when filter multipath routes. Example: ip link add name dummy1 up type dummy ip link add name dummy2 up type dummy ip address add 192.0.2.1/28 dev dummy1 ip address add 192.0.2.17/28 dev dummy2 ip route add 198.51.100.0/24 \ nexthop via 192.0.2.2 dev dummy1 \ nexthop via 192.0.2.18 dev dummy2 Before: ip route show dev dummy1 192.0.2.0/28 proto kernel scope link src 192.0.2.1 After: ip route show dev dummy1 192.0.2.0/28 proto kernel scope link src 192.0.2.1 198.51.100.0/24 nexthop via 192.0.2.2 dev dummy1 weight 1 nexthop via 192.0.2.18 dev dummy2 weight 1 Reported-by: "Muggeridge, Matt" Signed-off-by: Stephen Hemminger --- ip/iproute.c | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) diff --git a/ip/iproute.c b/ip/iproute.c index b5304611..44666240 100644 --- a/ip/iproute.c +++ b/ip/iproute.c @@ -154,6 +154,24 @@ static int flush_update(void) return 0; } +static bool filter_multipath(const struct rtattr *rta) +{ + const struct rtnexthop *nh = RTA_DATA(rta); + int len = RTA_PAYLOAD(rta); + + while (len >= sizeof(*nh)) { + if (nh->rtnh_len > len) + break; + + if (!((nh->rtnh_ifindex ^ filter.oif) & filter.oifmask)) + return true; + + len -= NLMSG_ALIGN(nh->rtnh_len); + nh = RTNH_NEXT(nh); + } + return false; +} + static int filter_nlmsg(struct nlmsghdr *n, struct rtattr **tb, int host_len) { struct rtmsg *r = NLMSG_DATA(n); @@ -310,12 +328,15 @@ static int filter_nlmsg(struct nlmsghdr *n, struct rtattr **tb, int host_len) return 0; } if (filter.oifmask) { - int oif = 0; + if (tb[RTA_OIF]) { + int oif = rta_getattr_u32(tb[RTA_OIF]); - if (tb[RTA_OIF]) - oif = rta_getattr_u32(tb[RTA_OIF]); - if ((oif^filter.oif)&filter.oifmask) - return 0; + if ((oif ^ filter.oif) & filter.oifmask) + return 0; + } else if (tb[RTA_MULTIPATH]) { + if (!filter_multipath(tb[RTA_MULTIPATH])) + return 0; + } } if (filter.markmask) { int mark = 0; -- cgit v1.2.3-70-g09d2