Router Advertisement/Solicitation sanity check

[project/odhcpd.git] / src / router.c

diff --git a/src/router.c b/src/router.c
index 0b01a77..a213c84 100644 (file)
--- a/src/router.c
+++ b/src/router.c
@@ -130,12 +130,66 @@ static void sigusr1_refresh(_unused int signal)
                        uloop_timeout_set(&iface->timer_rs, 1000);
 }
 
+static int router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
+{
+       struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
+       struct icmpv6_opt *opt;
+       size_t optlen = len - sizeof(*hdr);
+
+       /* Hoplimit is already checked in odhcpd_receive_packets */
+       if (len < sizeof(*hdr))
+               return 0;
+
+       if (hdr->icmp6_code)
+               return 0;
+
+       switch (hdr->icmp6_type) {
+       case ND_ROUTER_ADVERT:
+               if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
+                       return 0;
+
+               opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
+               break;
+
+       case ND_ROUTER_SOLICIT:
+               opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
+               break;
+
+       default:
+               return 0;
+       }
+
+       while (optlen > 0) {
+               size_t l = opt->len << 3;
+
+               if (optlen < sizeof(*opt))
+                       return 0;
+
+               if (l > optlen || l == 0)
+                       return 0;
+
+               if (opt->type == ND_OPT_SOURCE_LINKADDR && IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
+                       hdr->icmp6_type == ND_ROUTER_SOLICIT) {
+                       return 0;
+               }
+
+               opt = (struct icmpv6_opt *)(((uint8_t *)opt) + l);
+
+               optlen -= l;
+       }
+
+       return 1;
+}
 
 // Event handler for incoming ICMPv6 packets
-static void handle_icmpv6(_unused void *addr, void *data, size_t len,
+static void handle_icmpv6(void *addr, void *data, size_t len,
                struct interface *iface)
 {
        struct icmp6_hdr *hdr = data;
+       
+       if (!router_icmpv6_valid(addr, data, len))
+               return;
+
        if ((iface->ra == RELAYD_SERVER && !iface->master)) { // Server mode
                if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
                        send_router_advert(&iface->timer_rs);