1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2018 Facebook
3 
4 #include <string.h>
5 
6 #include <linux/stddef.h>
7 #include <linux/bpf.h>
8 #include <linux/in.h>
9 #include <linux/in6.h>
10 #include <sys/socket.h>
11 
12 #include "bpf_helpers.h"
13 #include "bpf_endian.h"
14 
15 #define SRC_REWRITE_IP4		0x7f000004U
16 #define DST_REWRITE_IP4		0x7f000001U
17 #define DST_REWRITE_PORT4	4444
18 
19 int _version SEC("version") = 1;
20 
21 SEC("cgroup/connect4")
connect_v4_prog(struct bpf_sock_addr * ctx)22 int connect_v4_prog(struct bpf_sock_addr *ctx)
23 {
24 	struct sockaddr_in sa;
25 
26 	/* Rewrite destination. */
27 	ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4);
28 	ctx->user_port = bpf_htons(DST_REWRITE_PORT4);
29 
30 	if (ctx->type == SOCK_DGRAM || ctx->type == SOCK_STREAM) {
31 		///* Rewrite source. */
32 		memset(&sa, 0, sizeof(sa));
33 
34 		sa.sin_family = AF_INET;
35 		sa.sin_port = bpf_htons(0);
36 		sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);
37 
38 		if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
39 			return 0;
40 	}
41 
42 	return 1;
43 }
44 
45 char _license[] SEC("license") = "GPL";
46