From 53f07e90b7f1da6977143a488dd5cb73a33b233b Mon Sep 17 00:00:00 2001 From: Hans Dedecker Date: Sat, 9 Jan 2021 21:17:48 +0100 Subject: [PATCH 1/1] ra: fix routing loop on point to point links For point-to-point links (e.g. PPP) don't create a link prefix route when receiving a prefix information option with the on-link flag set. Point-to-point links are non shared media and as such a destination IPv6 address cannot be on-link. If a link prefix route points to a point-to-point link it can trigger a routing loop if the destination IPv6 address belongs to the prefix. If such a packet is received and not directed to a local IPv6 address it will be routed to the point-to-point link due to the link prefix route; the upstream ISP router will route the IPv6 packet back due to the assigned prefix route creating a "ping pong" effect Signed-off-by: Hans Dedecker --- src/ra.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/src/ra.c b/src/ra.c index 32a3097..4e6dd64 100644 --- a/src/ra.c +++ b/src/ra.c @@ -51,6 +51,7 @@ #include "ra.h" static bool nocarrier = false; +static bool ptp_link = false; static int sock = -1, rtnl = -1; static int if_index = 0; @@ -87,6 +88,13 @@ int ra_init(const char *ifname, const struct in6_addr *ifid, if (sock < 0) goto failure; + memset(&ifr, 0, sizeof(ifr)); + strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name) - 1); + if (ioctl(sock, SIOCGIFFLAGS, &ifr) < 0) + goto failure; + + ptp_link = !!(ifr.ifr_flags & IFF_POINTOPOINT); + memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name) - 1); if (ioctl(sock, SIOCGIFINDEX, &ifr) < 0) @@ -488,7 +496,8 @@ bool ra_process(void) || entry->valid < entry->preferred) continue; - if (pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK) + if ((pinfo->nd_opt_pi_flags_reserved & ND_OPT_PI_FLAG_ONLINK) && + !ptp_link) changed |= odhcp6c_update_entry(STATE_RA_ROUTE, entry, 7200, ra_holdoff_interval); -- 2.30.2