0001
0002 #include <string.h>
0003 #include <stdbool.h>
0004
0005 #include <linux/bpf.h>
0006 #include <linux/in.h>
0007 #include <linux/in6.h>
0008 #include <sys/socket.h>
0009
0010 #include <bpf/bpf_helpers.h>
0011 #include <bpf/bpf_endian.h>
0012
0013 #include <bpf_sockopt_helpers.h>
0014
0015 char _license[] SEC("license") = "GPL";
0016
0017 struct svc_addr {
0018 __be32 addr;
0019 __be16 port;
0020 };
0021
0022 struct {
0023 __uint(type, BPF_MAP_TYPE_SK_STORAGE);
0024 __uint(map_flags, BPF_F_NO_PREALLOC);
0025 __type(key, int);
0026 __type(value, struct svc_addr);
0027 } service_mapping SEC(".maps");
0028
0029 SEC("cgroup/connect4")
0030 int connect4(struct bpf_sock_addr *ctx)
0031 {
0032 struct sockaddr_in sa = {};
0033 struct svc_addr *orig;
0034
0035
0036 sa.sin_family = AF_INET;
0037 sa.sin_port = bpf_htons(22222);
0038 sa.sin_addr.s_addr = bpf_htonl(0x7f000001);
0039
0040 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
0041 return 0;
0042
0043
0044 if (ctx->user_port == bpf_htons(60000)) {
0045 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0,
0046 BPF_SK_STORAGE_GET_F_CREATE);
0047 if (!orig)
0048 return 0;
0049
0050 orig->addr = ctx->user_ip4;
0051 orig->port = ctx->user_port;
0052
0053 ctx->user_ip4 = bpf_htonl(0x7f000001);
0054 ctx->user_port = bpf_htons(60123);
0055 }
0056 return 1;
0057 }
0058
0059 SEC("cgroup/getsockname4")
0060 int getsockname4(struct bpf_sock_addr *ctx)
0061 {
0062 if (!get_set_sk_priority(ctx))
0063 return 1;
0064
0065
0066 if (ctx->user_port == bpf_htons(60123)) {
0067 ctx->user_ip4 = bpf_htonl(0x01020304);
0068 ctx->user_port = bpf_htons(60000);
0069 }
0070 return 1;
0071 }
0072
0073 SEC("cgroup/getpeername4")
0074 int getpeername4(struct bpf_sock_addr *ctx)
0075 {
0076 struct svc_addr *orig;
0077
0078 if (!get_set_sk_priority(ctx))
0079 return 1;
0080
0081
0082 if (ctx->user_port == bpf_htons(60123)) {
0083 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0);
0084 if (orig) {
0085 ctx->user_ip4 = orig->addr;
0086 ctx->user_port = orig->port;
0087 }
0088 }
0089 return 1;
0090 }