1 // SPDX-License-Identifier: GPL-2.0
2 #include <error.h>
3 #include <errno.h>
4 #include <getopt.h>
5 #include <stdio.h>
6 #include <stdlib.h>
7 #include <string.h>
8 #include <sys/stat.h>
9 #include <fcntl.h>
10 #include <unistd.h>
11 #include <bpf/bpf.h>
12 #include <bpf/libbpf.h>
13 
14 #include "flow_dissector_load.h"
15 
16 const char *cfg_pin_path = "/sys/fs/bpf/flow_dissector";
17 const char *cfg_map_name = "jmp_table";
18 bool cfg_attach = true;
19 char *cfg_prog_name;
20 char *cfg_path_name;
21 
22 static void load_and_attach_program(void)
23 {
24 	int prog_fd, ret;
25 	struct bpf_object *obj;
26 
27 	/* Use libbpf 1.0 API mode */
28 	libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
29 
30 	ret = bpf_flow_load(&obj, cfg_path_name, cfg_prog_name,
31 			    cfg_map_name, NULL, &prog_fd, NULL);
32 	if (ret)
33 		error(1, 0, "bpf_flow_load %s", cfg_path_name);
34 
35 	ret = bpf_prog_attach(prog_fd, 0 /* Ignore */, BPF_FLOW_DISSECTOR, 0);
36 	if (ret)
37 		error(1, 0, "bpf_prog_attach %s", cfg_path_name);
38 
39 	ret = bpf_object__pin(obj, cfg_pin_path);
40 	if (ret)
41 		error(1, 0, "bpf_object__pin %s", cfg_pin_path);
42 }
43 
44 static void detach_program(void)
45 {
46 	char command[64];
47 	int ret;
48 
49 	ret = bpf_prog_detach(0, BPF_FLOW_DISSECTOR);
50 	if (ret)
51 		error(1, 0, "bpf_prog_detach");
52 
53 	/* To unpin, it is necessary and sufficient to just remove this dir */
54 	sprintf(command, "rm -r %s", cfg_pin_path);
55 	ret = system(command);
56 	if (ret)
57 		error(1, errno, "%s", command);
58 }
59 
60 static void parse_opts(int argc, char **argv)
61 {
62 	bool attach = false;
63 	bool detach = false;
64 	int c;
65 
66 	while ((c = getopt(argc, argv, "adp:s:")) != -1) {
67 		switch (c) {
68 		case 'a':
69 			if (detach)
70 				error(1, 0, "attach/detach are exclusive");
71 			attach = true;
72 			break;
73 		case 'd':
74 			if (attach)
75 				error(1, 0, "attach/detach are exclusive");
76 			detach = true;
77 			break;
78 		case 'p':
79 			if (cfg_path_name)
80 				error(1, 0, "only one path can be given");
81 
82 			cfg_path_name = optarg;
83 			break;
84 		case 's':
85 			if (cfg_prog_name)
86 				error(1, 0, "only one prog can be given");
87 
88 			cfg_prog_name = optarg;
89 			break;
90 		}
91 	}
92 
93 	if (detach)
94 		cfg_attach = false;
95 
96 	if (cfg_attach && !cfg_path_name)
97 		error(1, 0, "must provide a path to the BPF program");
98 
99 	if (cfg_attach && !cfg_prog_name)
100 		error(1, 0, "must provide a section name");
101 }
102 
103 int main(int argc, char **argv)
104 {
105 	parse_opts(argc, argv);
106 	if (cfg_attach)
107 		load_and_attach_program();
108 	else
109 		detach_program();
110 	return 0;
111 }
112