bpf: icmp6: wire up ext_err for icmp6_handle_ns()

Allow tail_call_internal() to return the index of a missed tail-call.

Signed-off-by: Julian Wiedmann <jwi@isovalent.com>

bpf/bpf_lxc.c

@@ -768,7 +768,7 @@ static __always_inline int __tail_handle_ipv6(struct __ctx_buff *ctx,
 	 * are subjected to forwarding into the container.
 	 */
 	if (unlikely(is_icmp6_ndp(ctx, ip6, ETH_HLEN)))
-		return icmp6_ndp_handle(ctx, ETH_HLEN, METRIC_EGRESS);
+		return icmp6_ndp_handle(ctx, ETH_HLEN, METRIC_EGRESS, ext_err);
 
 	if (unlikely(!is_valid_lxc_src_ip(ip6)))
 		return DROP_INVALID_SIP;

bpf/lib/icmp6.h

@@ -346,18 +346,20 @@ int tail_icmp6_handle_ns(struct __ctx_buff *ctx)
  * @ctx:	socket buffer
  * @nh_off:	offset to the IPv6 header
  * @direction:  direction of packet(ingress or egress)
+ * @ext_err:	extended error value
  *
  * Respond to ICMPv6 Neighbour Solicitation
  *
  * NOTE: This is terminal function and will cause the BPF program to exit
  */
 static __always_inline int icmp6_handle_ns(struct __ctx_buff *ctx, int nh_off,
-					   enum metric_dir direction)
+					   enum metric_dir direction,
+					   __s8 *ext_err)
 {
 	ctx_store_meta(ctx, 0, nh_off);
 	ctx_store_meta(ctx, 1, direction);
 
-	return tail_call_internal(ctx, CILIUM_CALL_HANDLE_ICMP6_NS, NULL);
+	return tail_call_internal(ctx, CILIUM_CALL_HANDLE_ICMP6_NS, ext_err);
 }
 
 static __always_inline bool
@@ -373,7 +375,8 @@ is_icmp6_ndp(struct __ctx_buff *ctx, const struct ipv6hdr *ip6, int nh_off)
 }
 
 static __always_inline int icmp6_ndp_handle(struct __ctx_buff *ctx, int nh_off,
-					    enum metric_dir direction)
+					    enum metric_dir direction,
+					    __s8 *ext_err)
 {
 	__u8 type;
 
@@ -382,7 +385,7 @@ static __always_inline int icmp6_ndp_handle(struct __ctx_buff *ctx, int nh_off,
 
 	cilium_dbg(ctx, DBG_ICMP6_HANDLE, type, 0);
 	if (type == ICMP6_NS_MSG_TYPE)
-		return icmp6_handle_ns(ctx, nh_off, direction);
+		return icmp6_handle_ns(ctx, nh_off, direction, ext_err);
 
 	/* All branching above will have issued a tail call, all
 	 * remaining traffic is subject to forwarding to containers.