tools/testing/selftests/bpf/progs/connect_force_port4.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <string.h>
   3 #include <stdbool.h>
   4
   5 #include <linux/bpf.h>
   6 #include <linux/in.h>
   7 #include <linux/in6.h>
   8 #include <sys/socket.h>
   9
  10 #include <bpf/bpf_helpers.h>
  11 #include <bpf/bpf_endian.h>
  12
  13 char _license[] SEC("license") = "GPL";
  14 int _version SEC("version") = 1;
  15
  16 struct svc_addr {
  17         __be32 addr;
  18         __be16 port;
  19 };
  20
  21 struct {
  22         __uint(type, BPF_MAP_TYPE_SK_STORAGE);
  23         __uint(map_flags, BPF_F_NO_PREALLOC);
  24         __type(key, int);
  25         __type(value, struct svc_addr);
  26 } service_mapping SEC(".maps");
  27
  28 SEC("cgroup/connect4")
  29 int connect4(struct bpf_sock_addr *ctx)
  30 {
  31         struct sockaddr_in sa = {};
  32         struct svc_addr *orig;
  33
  34         /* Force local address to 127.0.0.1:22222. */
  35         sa.sin_family = AF_INET;
  36         sa.sin_port = bpf_htons(22222);
  37         sa.sin_addr.s_addr = bpf_htonl(0x7f000001);
  38
  39         if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
  40                 return 0;
  41
  42         /* Rewire service 1.2.3.4:60000 to backend 127.0.0.1:60123. */
  43         if (ctx->user_port == bpf_htons(60000)) {
  44                 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0,
  45                                           BPF_SK_STORAGE_GET_F_CREATE);
  46                 if (!orig)
  47                         return 0;
  48
  49                 orig->addr = ctx->user_ip4;
  50                 orig->port = ctx->user_port;
  51
  52                 ctx->user_ip4 = bpf_htonl(0x7f000001);
  53                 ctx->user_port = bpf_htons(60123);
  54         }
  55         return 1;
  56 }
  57
  58 SEC("cgroup/getsockname4")
  59 int getsockname4(struct bpf_sock_addr *ctx)
  60 {
  61         /* Expose local server as 1.2.3.4:60000 to client. */
  62         if (ctx->user_port == bpf_htons(60123)) {
  63                 ctx->user_ip4 = bpf_htonl(0x01020304);
  64                 ctx->user_port = bpf_htons(60000);
  65         }
  66         return 1;
  67 }
  68
  69 SEC("cgroup/getpeername4")
  70 int getpeername4(struct bpf_sock_addr *ctx)
  71 {
  72         struct svc_addr *orig;
  73
  74         /* Expose service 1.2.3.4:60000 as peer instead of backend. */
  75         if (ctx->user_port == bpf_htons(60123)) {
  76                 orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0);
  77                 if (orig) {
  78                         ctx->user_ip4 = orig->addr;
  79                         ctx->user_port = orig->port;
  80                 }
  81         }
  82         return 1;
  83 }