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