samples/bpf/test_probe_write_user_user.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <stdio.h>
   3 #include <assert.h>
   4 #include <unistd.h>
   5 #include <bpf/bpf.h>
   6 #include <bpf/libbpf.h>
   7 #include <sys/socket.h>
   8 #include <netinet/in.h>
   9 #include <arpa/inet.h>
  10
  11 int main(int ac, char **argv)
  12 {
  13         struct sockaddr_in *serv_addr_in, *mapped_addr_in, *tmp_addr_in;
  14         struct sockaddr serv_addr, mapped_addr, tmp_addr;
  15         int serverfd, serverconnfd, clientfd, map_fd;
  16         struct bpf_link *link = NULL;
  17         struct bpf_program *prog;
  18         struct bpf_object *obj;
  19         socklen_t sockaddr_len;
  20         char filename[256];
  21         char *ip;
  22
  23         serv_addr_in = (struct sockaddr_in *)&serv_addr;
  24         mapped_addr_in = (struct sockaddr_in *)&mapped_addr;
  25         tmp_addr_in = (struct sockaddr_in *)&tmp_addr;
  26
  27         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  28         obj = bpf_object__open_file(filename, NULL);
  29         if (libbpf_get_error(obj)) {
  30                 fprintf(stderr, "ERROR: opening BPF object file failed\n");
  31                 return 0;
  32         }
  33
  34         prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
  35         if (libbpf_get_error(prog)) {
  36                 fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
  37                 goto cleanup;
  38         }
  39
  40         /* load BPF program */
  41         if (bpf_object__load(obj)) {
  42                 fprintf(stderr, "ERROR: loading BPF object file failed\n");
  43                 goto cleanup;
  44         }
  45
  46         map_fd = bpf_object__find_map_fd_by_name(obj, "dnat_map");
  47         if (map_fd < 0) {
  48                 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
  49                 goto cleanup;
  50         }
  51
  52         link = bpf_program__attach(prog);
  53         if (libbpf_get_error(link)) {
  54                 fprintf(stderr, "ERROR: bpf_program__attach failed\n");
  55                 link = NULL;
  56                 goto cleanup;
  57         }
  58
  59         assert((serverfd = socket(AF_INET, SOCK_STREAM, 0)) > 0);
  60         assert((clientfd = socket(AF_INET, SOCK_STREAM, 0)) > 0);
  61
  62         /* Bind server to ephemeral port on lo */
  63         memset(&serv_addr, 0, sizeof(serv_addr));
  64         serv_addr_in->sin_family = AF_INET;
  65         serv_addr_in->sin_port = 0;
  66         serv_addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
  67
  68         assert(bind(serverfd, &serv_addr, sizeof(serv_addr)) == 0);
  69
  70         sockaddr_len = sizeof(serv_addr);
  71         assert(getsockname(serverfd, &serv_addr, &sockaddr_len) == 0);
  72         ip = inet_ntoa(serv_addr_in->sin_addr);
  73         printf("Server bound to: %s:%d\n", ip, ntohs(serv_addr_in->sin_port));
  74
  75         memset(&mapped_addr, 0, sizeof(mapped_addr));
  76         mapped_addr_in->sin_family = AF_INET;
  77         mapped_addr_in->sin_port = htons(5555);
  78         mapped_addr_in->sin_addr.s_addr = inet_addr("255.255.255.255");
  79
  80         assert(!bpf_map_update_elem(map_fd, &mapped_addr, &serv_addr, BPF_ANY));
  81
  82         assert(listen(serverfd, 5) == 0);
  83
  84         ip = inet_ntoa(mapped_addr_in->sin_addr);
  85         printf("Client connecting to: %s:%d\n",
  86                ip, ntohs(mapped_addr_in->sin_port));
  87         assert(connect(clientfd, &mapped_addr, sizeof(mapped_addr)) == 0);
  88
  89         sockaddr_len = sizeof(tmp_addr);
  90         ip = inet_ntoa(tmp_addr_in->sin_addr);
  91         assert((serverconnfd = accept(serverfd, &tmp_addr, &sockaddr_len)) > 0);
  92         printf("Server received connection from: %s:%d\n",
  93                ip, ntohs(tmp_addr_in->sin_port));
  94
  95         sockaddr_len = sizeof(tmp_addr);
  96         assert(getpeername(clientfd, &tmp_addr, &sockaddr_len) == 0);
  97         ip = inet_ntoa(tmp_addr_in->sin_addr);
  98         printf("Client's peer address: %s:%d\n",
  99                ip, ntohs(tmp_addr_in->sin_port));
 100
 101         /* Is the server's getsockname = the socket getpeername */
 102         assert(memcmp(&serv_addr, &tmp_addr, sizeof(struct sockaddr_in)) == 0);
 103
 104 cleanup:
 105         bpf_link__destroy(link);
 106         bpf_object__close(obj);
 107         return 0;
 108 }