LXR linux/tools/testing/selftests/bpf/progs/connect_force

   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#include <bpf_sockopt_helpers.h>
  14
  15char _license[] SEC("license") = "GPL";
  16int _version SEC("version") = 1;
  17
  18struct svc_addr {
  19        __be32 addr;
  20        __be16 port;
  21};
  22
  23struct {
  24        __uint(type, BPF_MAP_TYPE_SK_STORAGE);
  25        __uint(map_flags, BPF_F_NO_PREALLOC);
  26        __type(key, int);
  27        __type(value, struct svc_addr);
  28} service_mapping SEC(".maps");
  29
  30SEC("cgroup/connect4")
  31int connect4(struct bpf_sock_addr *ctx)
  32{
  33        struct sockaddr_in sa = {};
  34        struct svc_addr *orig;
  35
  36        /* Force local address to 127.0.0.1:22222. */
  37        sa.sin_family = AF_INET;
  38        sa.sin_port = bpf_htons(22222);
  39        sa.sin_addr.s_addr = bpf_htonl(0x7f000001);
  40
  41        if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
  42                return 0;
  43
  44        /* Rewire service 1.2.3.4:60000 to backend 127.0.0.1:60123. */
  45        if (ctx->user_port == bpf_htons(60000)) {
  46                orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0,
  47                                          BPF_SK_STORAGE_GET_F_CREATE);
  48                if (!orig)
  49                        return 0;
  50
  51                orig->addr = ctx->user_ip4;
  52                orig->port = ctx->user_port;
  53
  54                ctx->user_ip4 = bpf_htonl(0x7f000001);
  55                ctx->user_port = bpf_htons(60123);
  56        }
  57        return 1;
  58}
  59
  60SEC("cgroup/getsockname4")
  61int getsockname4(struct bpf_sock_addr *ctx)
  62{
  63        if (!get_set_sk_priority(ctx))
  64                return 1;
  65
  66        /* Expose local server as 1.2.3.4:60000 to client. */
  67        if (ctx->user_port == bpf_htons(60123)) {
  68                ctx->user_ip4 = bpf_htonl(0x01020304);
  69                ctx->user_port = bpf_htons(60000);
  70        }
  71        return 1;
  72}
  73
  74SEC("cgroup/getpeername4")
  75int getpeername4(struct bpf_sock_addr *ctx)
  76{
  77        struct svc_addr *orig;
  78
  79        if (!get_set_sk_priority(ctx))
  80                return 1;
  81
  82        /* Expose service 1.2.3.4:60000 as peer instead of backend. */
  83        if (ctx->user_port == bpf_htons(60123)) {
  84                orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0);
  85                if (orig) {
  86                        ctx->user_ip4 = orig->addr;
  87                        ctx->user_port = orig->port;
  88                }
  89        }
  90        return 1;
  91}
  92