commit 1db34f3b919f0863e0e80f29333ab43bbbf483a0
author Ryan Zuklie <rzuklie@google.com> Fri Jan 20 17:00:04 2023 -0800
committer Ryan Zuklie <rzuklie@google.com> Mon Jan 23 09:50:31 2023 -0800
tree d813749a04be5d6ac78fdbb4db466ac435306a24
parent 55d65ad71b473b1021044a51bf0728db5f81962e

Add BPF helpers for ipv4/ipv6 and tcp/udp offsets.

Test: build & install connectivity module
Change-Id: I869810d05ad8266b6a4107a5276864fdbcdbd9b0

bpf_progs/netd.c

diff --git a/bpf_progs/netd.c b/bpf_progs/netd.c
index 1272f96..8ca6ec6 100644
--- a/bpf_progs/netd.c
+++ b/bpf_progs/netd.c
@@ -46,8 +46,6 @@
 static const bool INGRESS = false;
 static const bool EGRESS = true;
 
-#define IP_PROTO_OFF offsetof(struct iphdr, protocol)
-#define IPV6_PROTO_OFF offsetof(struct ipv6hdr, nexthdr)
 
 // offsetof(struct iphdr, ihl) -- but that's a bitfield
 #define IPPROTO_IHL_OFF 0
@@ -231,7 +229,7 @@
     if (skb->protocol == htons(ETH_P_IP)) {
         uint8_t proto;
         // no need to check for success, proto will be zeroed if bpf_skb_load_bytes_net() fails
-        (void)bpf_skb_load_bytes_net(skb, IP_PROTO_OFF, &proto, sizeof(proto), kver);
+        (void)bpf_skb_load_bytes_net(skb, IP4_OFFSET(protocol), &proto, sizeof(proto), kver);
         if (proto == IPPROTO_ESP) return true;
         if (proto != IPPROTO_TCP) return false;  // handles read failure above
         uint8_t ihl;
@@ -247,7 +245,7 @@
     } else if (skb->protocol == htons(ETH_P_IPV6)) {
         uint8_t proto;
         // no need to check for success, proto will be zeroed if bpf_skb_load_bytes_net() fails
-        (void)bpf_skb_load_bytes_net(skb, IPV6_PROTO_OFF, &proto, sizeof(proto), kver);
+        (void)bpf_skb_load_bytes_net(skb, IP6_OFFSET(nexthdr), &proto, sizeof(proto), kver);
         if (proto == IPPROTO_ESP) return true;
         if (proto != IPPROTO_TCP) return false;  // handles read failure above
         // if the read below fails, we'll just assume no TCP flags are set, which is fine.