1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2020 Facebook */
3 #include <errno.h>
4 #include <stdio.h>
5 #include <stdlib.h>
6 #include <string.h>
7 #include <unistd.h>
8 #include <fcntl.h>
9 #include <sys/resource.h>
10 #include <bpf/libbpf.h>
11 #include <bpf/bpf.h>
12 #include <sys/mount.h>
13 #include "iterators.skel.h"
14 #include "bpf_preload_common.h"
15
16 int to_kernel = -1;
17 int from_kernel = 0;
18
send_link_to_kernel(struct bpf_link * link,const char * link_name)19 static int send_link_to_kernel(struct bpf_link *link, const char *link_name)
20 {
21 struct bpf_preload_info obj = {};
22 struct bpf_link_info info = {};
23 __u32 info_len = sizeof(info);
24 int err;
25
26 err = bpf_obj_get_info_by_fd(bpf_link__fd(link), &info, &info_len);
27 if (err)
28 return err;
29 obj.link_id = info.id;
30 if (strlen(link_name) >= sizeof(obj.link_name))
31 return -E2BIG;
32 strcpy(obj.link_name, link_name);
33 if (write(to_kernel, &obj, sizeof(obj)) != sizeof(obj))
34 return -EPIPE;
35 return 0;
36 }
37
main(int argc,char ** argv)38 int main(int argc, char **argv)
39 {
40 struct rlimit rlim = { RLIM_INFINITY, RLIM_INFINITY };
41 struct iterators_bpf *skel;
42 int err, magic;
43 int debug_fd;
44
45 debug_fd = open("/dev/console", O_WRONLY | O_NOCTTY | O_CLOEXEC);
46 if (debug_fd < 0)
47 return 1;
48 to_kernel = dup(1);
49 close(1);
50 dup(debug_fd);
51 /* now stdin and stderr point to /dev/console */
52
53 read(from_kernel, &magic, sizeof(magic));
54 if (magic != BPF_PRELOAD_START) {
55 printf("bad start magic %d\n", magic);
56 return 1;
57 }
58 setrlimit(RLIMIT_MEMLOCK, &rlim);
59 /* libbpf opens BPF object and loads it into the kernel */
60 skel = iterators_bpf__open_and_load();
61 if (!skel) {
62 /* iterators.skel.h is little endian.
63 * libbpf doesn't support automatic little->big conversion
64 * of BPF bytecode yet.
65 * The program load will fail in such case.
66 */
67 printf("Failed load could be due to wrong endianness\n");
68 return 1;
69 }
70 err = iterators_bpf__attach(skel);
71 if (err)
72 goto cleanup;
73
74 /* send two bpf_link IDs with names to the kernel */
75 err = send_link_to_kernel(skel->links.dump_bpf_map, "maps.debug");
76 if (err)
77 goto cleanup;
78 err = send_link_to_kernel(skel->links.dump_bpf_prog, "progs.debug");
79 if (err)
80 goto cleanup;
81
82 /* The kernel will proceed with pinnging the links in bpffs.
83 * UMD will wait on read from pipe.
84 */
85 read(from_kernel, &magic, sizeof(magic));
86 if (magic != BPF_PRELOAD_END) {
87 printf("bad final magic %d\n", magic);
88 err = -EINVAL;
89 }
90 cleanup:
91 iterators_bpf__destroy(skel);
92
93 return err != 0;
94 }
95