mirror of https://gitee.com/openkylin/linux.git
73 lines
1.7 KiB
C
73 lines
1.7 KiB
C
// 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_helpers.h"
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#include "bpf_endian.h"
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#define SRC_REWRITE_IP4 0x7f000004U
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#define DST_REWRITE_IP4 0x7f000001U
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#define DST_REWRITE_PORT4 4444
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int _version SEC("version") = 1;
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SEC("cgroup/connect4")
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int connect_v4_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_in 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.ipv4.saddr, 0, sizeof(tuple.ipv4.saddr));
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memset(&tuple.ipv4.sport, 0, sizeof(tuple.ipv4.sport));
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tuple.ipv4.daddr = bpf_htonl(DST_REWRITE_IP4);
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tuple.ipv4.dport = bpf_htons(DST_REWRITE_PORT4);
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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.ipv4),
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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.ipv4),
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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_ip4 != tuple.ipv4.daddr ||
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sk->src_port != DST_REWRITE_PORT4) {
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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_ip4 = bpf_htonl(DST_REWRITE_IP4);
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ctx->user_port = bpf_htons(DST_REWRITE_PORT4);
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/* Rewrite source. */
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memset(&sa, 0, sizeof(sa));
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sa.sin_family = AF_INET;
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sa.sin_port = bpf_htons(0);
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sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);
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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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