samples/bpf/test_probe_write_user_user.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <stdio.h>
0003 #include <assert.h>
0004 #include <unistd.h>
0005 #include <bpf/bpf.h>
0006 #include <bpf/libbpf.h>
0007 #include <sys/socket.h>
0008 #include <netinet/in.h>
0009 #include <arpa/inet.h>
0010
0011 int main(int ac, char **argv)
0012 {
0013     struct sockaddr_in *serv_addr_in, *mapped_addr_in, *tmp_addr_in;
0014     struct sockaddr serv_addr, mapped_addr, tmp_addr;
0015     int serverfd, serverconnfd, clientfd, map_fd;
0016     struct bpf_link *link = NULL;
0017     struct bpf_program *prog;
0018     struct bpf_object *obj;
0019     socklen_t sockaddr_len;
0020     char filename[256];
0021     char *ip;
0022
0023     serv_addr_in = (struct sockaddr_in *)&serv_addr;
0024     mapped_addr_in = (struct sockaddr_in *)&mapped_addr;
0025     tmp_addr_in = (struct sockaddr_in *)&tmp_addr;
0026
0027     snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
0028     obj = bpf_object__open_file(filename, NULL);
0029     if (libbpf_get_error(obj)) {
0030         fprintf(stderr, "ERROR: opening BPF object file failed\n");
0031         return 0;
0032     }
0033
0034     prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
0035     if (libbpf_get_error(prog)) {
0036         fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
0037         goto cleanup;
0038     }
0039
0040     /* load BPF program */
0041     if (bpf_object__load(obj)) {
0042         fprintf(stderr, "ERROR: loading BPF object file failed\n");
0043         goto cleanup;
0044     }
0045
0046     map_fd = bpf_object__find_map_fd_by_name(obj, "dnat_map");
0047     if (map_fd < 0) {
0048         fprintf(stderr, "ERROR: finding a map in obj file failed\n");
0049         goto cleanup;
0050     }
0051
0052     link = bpf_program__attach(prog);
0053     if (libbpf_get_error(link)) {
0054         fprintf(stderr, "ERROR: bpf_program__attach failed\n");
0055         link = NULL;
0056         goto cleanup;
0057     }
0058
0059     assert((serverfd = socket(AF_INET, SOCK_STREAM, 0)) > 0);
0060     assert((clientfd = socket(AF_INET, SOCK_STREAM, 0)) > 0);
0061
0062     /* Bind server to ephemeral port on lo */
0063     memset(&serv_addr, 0, sizeof(serv_addr));
0064     serv_addr_in->sin_family = AF_INET;
0065     serv_addr_in->sin_port = 0;
0066     serv_addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
0067
0068     assert(bind(serverfd, &serv_addr, sizeof(serv_addr)) == 0);
0069
0070     sockaddr_len = sizeof(serv_addr);
0071     assert(getsockname(serverfd, &serv_addr, &sockaddr_len) == 0);
0072     ip = inet_ntoa(serv_addr_in->sin_addr);
0073     printf("Server bound to: %s:%d\n", ip, ntohs(serv_addr_in->sin_port));
0074
0075     memset(&mapped_addr, 0, sizeof(mapped_addr));
0076     mapped_addr_in->sin_family = AF_INET;
0077     mapped_addr_in->sin_port = htons(5555);
0078     mapped_addr_in->sin_addr.s_addr = inet_addr("255.255.255.255");
0079
0080     assert(!bpf_map_update_elem(map_fd, &mapped_addr, &serv_addr, BPF_ANY));
0081
0082     assert(listen(serverfd, 5) == 0);
0083
0084     ip = inet_ntoa(mapped_addr_in->sin_addr);
0085     printf("Client connecting to: %s:%d\n",
0086            ip, ntohs(mapped_addr_in->sin_port));
0087     assert(connect(clientfd, &mapped_addr, sizeof(mapped_addr)) == 0);
0088
0089     sockaddr_len = sizeof(tmp_addr);
0090     ip = inet_ntoa(tmp_addr_in->sin_addr);
0091     assert((serverconnfd = accept(serverfd, &tmp_addr, &sockaddr_len)) > 0);
0092     printf("Server received connection from: %s:%d\n",
0093            ip, ntohs(tmp_addr_in->sin_port));
0094
0095     sockaddr_len = sizeof(tmp_addr);
0096     assert(getpeername(clientfd, &tmp_addr, &sockaddr_len) == 0);
0097     ip = inet_ntoa(tmp_addr_in->sin_addr);
0098     printf("Client's peer address: %s:%d\n",
0099            ip, ntohs(tmp_addr_in->sin_port));
0100
0101     /* Is the server's getsockname = the socket getpeername */
0102     assert(memcmp(&serv_addr, &tmp_addr, sizeof(struct sockaddr_in)) == 0);
0103
0104 cleanup:
0105     bpf_link__destroy(link);
0106     bpf_object__close(obj);
0107     return 0;
0108 }