136 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * Check if we can migrate child sockets.4 *5 * 1. If reuse_md->migrating_sk is NULL (SYN packet),6 * return SK_PASS without selecting a listener.7 * 2. If reuse_md->migrating_sk is not NULL (socket migration),8 * select a listener (reuseport_map[migrate_map[cookie]])9 *10 * Author: Kuniyuki Iwashima <kuniyu@amazon.co.jp>11 */12 13#include <stddef.h>14#include <string.h>15#include <linux/bpf.h>16#include <linux/if_ether.h>17#include <linux/ip.h>18#include <linux/ipv6.h>19#include <linux/tcp.h>20#include <linux/in.h>21#include <bpf/bpf_endian.h>22#include <bpf/bpf_helpers.h>23 24struct {25 __uint(type, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);26 __uint(max_entries, 256);27 __type(key, int);28 __type(value, __u64);29} reuseport_map SEC(".maps");30 31struct {32 __uint(type, BPF_MAP_TYPE_HASH);33 __uint(max_entries, 256);34 __type(key, __u64);35 __type(value, int);36} migrate_map SEC(".maps");37 38int migrated_at_close = 0;39int migrated_at_close_fastopen = 0;40int migrated_at_send_synack = 0;41int migrated_at_recv_ack = 0;42__be16 server_port;43 44SEC("xdp")45int drop_ack(struct xdp_md *xdp)46{47 void *data_end = (void *)(long)xdp->data_end;48 void *data = (void *)(long)xdp->data;49 struct ethhdr *eth = data;50 struct tcphdr *tcp = NULL;51 52 if (eth + 1 > data_end)53 goto pass;54 55 switch (bpf_ntohs(eth->h_proto)) {56 case ETH_P_IP: {57 struct iphdr *ip = (struct iphdr *)(eth + 1);58 59 if (ip + 1 > data_end)60 goto pass;61 62 if (ip->protocol != IPPROTO_TCP)63 goto pass;64 65 tcp = (struct tcphdr *)((void *)ip + ip->ihl * 4);66 break;67 }68 case ETH_P_IPV6: {69 struct ipv6hdr *ipv6 = (struct ipv6hdr *)(eth + 1);70 71 if (ipv6 + 1 > data_end)72 goto pass;73 74 if (ipv6->nexthdr != IPPROTO_TCP)75 goto pass;76 77 tcp = (struct tcphdr *)(ipv6 + 1);78 break;79 }80 default:81 goto pass;82 }83 84 if (tcp + 1 > data_end)85 goto pass;86 87 if (tcp->dest != server_port)88 goto pass;89 90 if (!tcp->syn && tcp->ack)91 return XDP_DROP;92 93pass:94 return XDP_PASS;95}96 97SEC("sk_reuseport/migrate")98int migrate_reuseport(struct sk_reuseport_md *reuse_md)99{100 int *key, flags = 0, state, err;101 __u64 cookie;102 103 if (!reuse_md->migrating_sk)104 return SK_PASS;105 106 state = reuse_md->migrating_sk->state;107 cookie = bpf_get_socket_cookie(reuse_md->sk);108 109 key = bpf_map_lookup_elem(&migrate_map, &cookie);110 if (!key)111 return SK_DROP;112 113 err = bpf_sk_select_reuseport(reuse_md, &reuseport_map, key, flags);114 if (err)115 return SK_PASS;116 117 switch (state) {118 case BPF_TCP_ESTABLISHED:119 __sync_fetch_and_add(&migrated_at_close, 1);120 break;121 case BPF_TCP_SYN_RECV:122 __sync_fetch_and_add(&migrated_at_close_fastopen, 1);123 break;124 case BPF_TCP_NEW_SYN_RECV:125 if (!reuse_md->len)126 __sync_fetch_and_add(&migrated_at_send_synack, 1);127 else128 __sync_fetch_and_add(&migrated_at_recv_ack, 1);129 break;130 }131 132 return SK_PASS;133}134 135char _license[] SEC("license") = "GPL";136