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