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// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2018 Facebook
#include <string.h>
#include <linux/stddef.h>
#include <linux/bpf.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <sys/socket.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#define SRC_REWRITE_IP6_0 0
#define SRC_REWRITE_IP6_1 0
#define SRC_REWRITE_IP6_2 0
#define SRC_REWRITE_IP6_3 6
#define DST_REWRITE_IP6_0 0
#define DST_REWRITE_IP6_1 0
#define DST_REWRITE_IP6_2 0
#define DST_REWRITE_IP6_3 1
#define DST_REWRITE_PORT6 6666
SEC("cgroup/connect6")
int connect_v6_prog(struct bpf_sock_addr *ctx)
{
struct bpf_sock_tuple tuple = {};
struct sockaddr_in6 sa;
struct bpf_sock *sk;
/* Verify that new destination is available. */
memset(&tuple.ipv6.saddr, 0, sizeof(tuple.ipv6.saddr));
memset(&tuple.ipv6.sport, 0, sizeof(tuple.ipv6.sport));
tuple.ipv6.daddr[0] = bpf_htonl(DST_REWRITE_IP6_0);
tuple.ipv6.daddr[1] = bpf_htonl(DST_REWRITE_IP6_1);
tuple.ipv6.daddr[2] = bpf_htonl(DST_REWRITE_IP6_2);
tuple.ipv6.daddr[3] = bpf_htonl(DST_REWRITE_IP6_3);
tuple.ipv6.dport = bpf_htons(DST_REWRITE_PORT6);
if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
return 0;
else if (ctx->type == SOCK_STREAM)
sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv6),
BPF_F_CURRENT_NETNS, 0);
else
sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv6),
BPF_F_CURRENT_NETNS, 0);
if (!sk)
return 0;
if (sk->src_ip6[0] != tuple.ipv6.daddr[0] ||
sk->src_ip6[1] != tuple.ipv6.daddr[1] ||
sk->src_ip6[2] != tuple.ipv6.daddr[2] ||
sk->src_ip6[3] != tuple.ipv6.daddr[3] ||
sk->src_port != DST_REWRITE_PORT6) {
bpf_sk_release(sk);
return 0;
}
bpf_sk_release(sk);
/* Rewrite destination. */
ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0);
ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1);
ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2);
ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3);
ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
/* Rewrite source. */
memset(&sa, 0, sizeof(sa));
sa.sin6_family = AF_INET6;
sa.sin6_port = bpf_htons(0);
sa.sin6_addr.s6_addr32[0] = bpf_htonl(SRC_REWRITE_IP6_0);
sa.sin6_addr.s6_addr32[1] = bpf_htonl(SRC_REWRITE_IP6_1);
sa.sin6_addr.s6_addr32[2] = bpf_htonl(SRC_REWRITE_IP6_2);
sa.sin6_addr.s6_addr32[3] = bpf_htonl(SRC_REWRITE_IP6_3);
if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
return 0;
return 1;
}
char _license[] SEC("license") = "GPL";
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