Support v6 fragment parsing

[flowspec-xdp] / xdp.c

diff --git a/xdp.c b/xdp.c
index 87b7eb5edae258cfbe695c21ac30ff4ae9c4a9a5..8623af44c1f0cdbb6b0591e7d4c6db148cf05739 100644 (file)
--- a/xdp.c
+++ b/xdp.c
@@ -18,7 +18,8 @@
 #define IP_PROTO_TCP 6
 #define IP_PROTO_UDP 17
 #define IP_PROTO_ICMP 1
-#define IP_PROTO_ICMPV6 58
+#define IP6_PROTO_ICMPV6 58
+#define IP6_PROTO_FRAG 44
 
 typedef __uint128_t uint128_t;
 
@@ -43,6 +44,15 @@ struct ip6hdr {
        uint128_t       daddr;
 } __attribute__((packed));
 
+#define IP6_MF 1
+#define IP6_FRAGOFF 0xfff8
+struct ip6_fraghdr {
+       uint8_t nexthdr;
+       uint8_t _reserved;
+       uint16_t frag_off; // BE low 3 bits flags, last is "more frags"
+       uint32_t id;
+} __attribute__((packed));
+
 // Our own ethhdr with optional vlan tags
 struct ethhdr_vlan {
        unsigned char   h_dest[ETH_ALEN];       /* destination eth addr */
@@ -161,6 +171,7 @@ int xdp_drop_prog(struct xdp_md *ctx)
        const struct udphdr *udp = NULL;
        const struct icmphdr *icmp = NULL;
        const struct icmp6hdr *icmpv6 = NULL;
+       const struct ip6_fraghdr *frag6 = NULL;
        const struct iphdr *ip = NULL;
        const struct ip6hdr *ip6 = NULL;
        const void *l4hdr = NULL;
@@ -195,15 +206,27 @@ int xdp_drop_prog(struct xdp_md *ctx)
                ip6 = (struct ip6hdr*) pktdata;
 
                l4hdr = pktdata + 40;
-               if (ip6->nexthdr == IP_PROTO_TCP) {
+
+               uint8_t v6nexthdr;
+               if (ip6->nexthdr == IP6_PROTO_FRAG) {
+                       if (l4hdr + sizeof(struct ip6_fraghdr) > data_end)
+                               return XDP_DROP;
+                       frag6 = (struct ip6_fraghdr*) l4hdr;
+                       l4hdr = l4hdr + sizeof(struct ip6_fraghdr);
+                       v6nexthdr = frag6->nexthdr;
+               } else {
+                       v6nexthdr = ip6->nexthdr;
+               }
+
+               if (v6nexthdr == IP_PROTO_TCP) {
                        if (l4hdr + sizeof(struct tcphdr) > data_end)
                                return XDP_DROP;
                        tcp = (struct tcphdr*) l4hdr;
-               } else if (ip6->nexthdr == IP_PROTO_UDP) {
+               } else if (v6nexthdr == IP_PROTO_UDP) {
                        if (l4hdr + sizeof(struct udphdr) > data_end)
                                return XDP_DROP;
                        udp = (struct udphdr*) l4hdr;
-               } else if (ip6->nexthdr == IP_PROTO_ICMPV6) {
+               } else if (v6nexthdr == IP6_PROTO_ICMPV6) {
                        if (l4hdr + sizeof(struct icmp6hdr) > data_end)
                                return XDP_DROP;
                        icmpv6 = (struct icmp6hdr*) l4hdr;