60 lines
1.4 KiB
C
60 lines
1.4 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 <linux/stddef.h>
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#include <linux/bpf.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_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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int _version SEC("version") = 1;
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SEC("cgroup/sendmsg6")
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int sendmsg_v6_prog(struct bpf_sock_addr *ctx)
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{
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if (ctx->type != SOCK_DGRAM)
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return 0;
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/* Rewrite source. */
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if (ctx->msg_src_ip6[3] == bpf_htonl(1) ||
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ctx->msg_src_ip6[3] == bpf_htonl(0)) {
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ctx->msg_src_ip6[0] = bpf_htonl(SRC_REWRITE_IP6_0);
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ctx->msg_src_ip6[1] = bpf_htonl(SRC_REWRITE_IP6_1);
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ctx->msg_src_ip6[2] = bpf_htonl(SRC_REWRITE_IP6_2);
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ctx->msg_src_ip6[3] = bpf_htonl(SRC_REWRITE_IP6_3);
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} else {
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/* Unexpected source. Reject sendmsg. */
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return 0;
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}
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/* Rewrite destination. */
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if (ctx->user_ip6[0] == bpf_htonl(0xFACEB00C)) {
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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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} else {
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/* Unexpected destination. Reject sendmsg. */
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return 0;
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}
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return 1;
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}
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char _license[] SEC("license") = "GPL";
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