bpf: Test BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.

This patch adds a test for BPF_SK_REUSEPORT_SELECT_OR_MIGRATE and
removes 'static' from settimeo() in network_helpers.c.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210612123224.12525-12-kuniyu@amazon.co.jp

tools/testing/selftests/bpf/network_helpers.c

@@ -40,7 +40,7 @@ struct ipv6_packet pkt_v6 = {
 	.tcp.doff = 5,
 };
 
-static int settimeo(int fd, int timeout_ms)
+int settimeo(int fd, int timeout_ms)
 {
 	struct timeval timeout = { .tv_sec = 3 };
 

tools/testing/selftests/bpf/network_helpers.h

@@ -33,6 +33,7 @@ struct ipv6_packet {
 } __packed;
 extern struct ipv6_packet pkt_v6;
 
+int settimeo(int fd, int timeout_ms);
 int start_server(int family, int type, const char *addr, __u16 port,
 		 int timeout_ms);
 int connect_to_fd(int server_fd, int timeout_ms);

tools/testing/selftests/bpf/progs/test_migrate_reuseport.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Check if we can migrate child sockets.
+ *
+ *   1. If reuse_md->migrating_sk is NULL (SYN packet),
+ *        return SK_PASS without selecting a listener.
+ *   2. If reuse_md->migrating_sk is not NULL (socket migration),
+ *        select a listener (reuseport_map[migrate_map[cookie]])
+ *
+ * Author: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
+ */
+
+#include <stddef.h>
+#include <string.h>
+#include <linux/bpf.h>
+#include <linux/if_ether.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/tcp.h>
+#include <linux/in.h>
+#include <bpf/bpf_endian.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);
+	__uint(max_entries, 256);
+	__type(key, int);
+	__type(value, __u64);
+} reuseport_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 256);
+	__type(key, __u64);
+	__type(value, int);
+} migrate_map SEC(".maps");
+
+int migrated_at_close = 0;
+int migrated_at_close_fastopen = 0;
+int migrated_at_send_synack = 0;
+int migrated_at_recv_ack = 0;
+__be16 server_port;
+
+SEC("xdp")
+int drop_ack(struct xdp_md *xdp)
+{
+	void *data_end = (void *)(long)xdp->data_end;
+	void *data = (void *)(long)xdp->data;
+	struct ethhdr *eth = data;
+	struct tcphdr *tcp = NULL;
+
+	if (eth + 1 > data_end)
+		goto pass;
+
+	switch (bpf_ntohs(eth->h_proto)) {
+	case ETH_P_IP: {
+		struct iphdr *ip = (struct iphdr *)(eth + 1);
+
+		if (ip + 1 > data_end)
+			goto pass;
+
+		if (ip->protocol != IPPROTO_TCP)
+			goto pass;
+
+		tcp = (struct tcphdr *)((void *)ip + ip->ihl * 4);
+		break;
+	}
+	case ETH_P_IPV6: {
+		struct ipv6hdr *ipv6 = (struct ipv6hdr *)(eth + 1);
+
+		if (ipv6 + 1 > data_end)
+			goto pass;
+
+		if (ipv6->nexthdr != IPPROTO_TCP)
+			goto pass;
+
+		tcp = (struct tcphdr *)(ipv6 + 1);
+		break;
+	}
+	default:
+		goto pass;
+	}
+
+	if (tcp + 1 > data_end)
+		goto pass;
+
+	if (tcp->dest != server_port)
+		goto pass;
+
+	if (!tcp->syn && tcp->ack)
+		return XDP_DROP;
+
+pass:
+	return XDP_PASS;
+}
+
+SEC("sk_reuseport/migrate")
+int migrate_reuseport(struct sk_reuseport_md *reuse_md)
+{
+	int *key, flags = 0, state, err;
+	__u64 cookie;
+
+	if (!reuse_md->migrating_sk)
+		return SK_PASS;
+
+	state = reuse_md->migrating_sk->state;
+	cookie = bpf_get_socket_cookie(reuse_md->sk);
+
+	key = bpf_map_lookup_elem(&migrate_map, &cookie);
+	if (!key)
+		return SK_DROP;
+
+	err = bpf_sk_select_reuseport(reuse_md, &reuseport_map, key, flags);
+	if (err)
+		return SK_PASS;
+
+	switch (state) {
+	case BPF_TCP_ESTABLISHED:
+		__sync_fetch_and_add(&migrated_at_close, 1);
+		break;
+	case BPF_TCP_SYN_RECV:
+		__sync_fetch_and_add(&migrated_at_close_fastopen, 1);
+		break;
+	case BPF_TCP_NEW_SYN_RECV:
+		if (!reuse_md->len)
+			__sync_fetch_and_add(&migrated_at_send_synack, 1);
+		else
+			__sync_fetch_and_add(&migrated_at_recv_ack, 1);
+		break;
+	}
+
+	return SK_PASS;
+}
+
+char _license[] SEC("license") = "GPL";