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 const char *cfg_pin_path = "/sys/fs/bpf/flow_dissector";
15 const char *cfg_map_name = "jmp_table";
16 bool cfg_attach = true;
17 char *cfg_section_name;
18 char *cfg_path_name;
19 
20 static void load_and_attach_program(void)
21 {
22 	struct bpf_program *prog, *main_prog;
23 	struct bpf_map *prog_array;
24 	int i, fd, prog_fd, ret;
25 	struct bpf_object *obj;
26 	int prog_array_fd;
27 
28 	ret = bpf_prog_load(cfg_path_name, BPF_PROG_TYPE_FLOW_DISSECTOR, &obj,
29 			    &prog_fd);
30 	if (ret)
31 		error(1, 0, "bpf_prog_load %s", cfg_path_name);
32 
33 	main_prog = bpf_object__find_program_by_title(obj, cfg_section_name);
34 	if (!main_prog)
35 		error(1, 0, "bpf_object__find_program_by_title %s",
36 		      cfg_section_name);
37 
38 	prog_fd = bpf_program__fd(main_prog);
39 	if (prog_fd < 0)
40 		error(1, 0, "bpf_program__fd");
41 
42 	prog_array = bpf_object__find_map_by_name(obj, cfg_map_name);
43 	if (!prog_array)
44 		error(1, 0, "bpf_object__find_map_by_name %s", cfg_map_name);
45 
46 	prog_array_fd = bpf_map__fd(prog_array);
47 	if (prog_array_fd < 0)
48 		error(1, 0, "bpf_map__fd %s", cfg_map_name);
49 
50 	i = 0;
51 	bpf_object__for_each_program(prog, obj) {
52 		fd = bpf_program__fd(prog);
53 		if (fd < 0)
54 			error(1, 0, "bpf_program__fd");
55 
56 		if (fd != prog_fd) {
57 			printf("%d: %s\n", i, bpf_program__title(prog, false));
58 			bpf_map_update_elem(prog_array_fd, &i, &fd, BPF_ANY);
59 			++i;
60 		}
61 	}
62 
63 	ret = bpf_prog_attach(prog_fd, 0 /* Ignore */, BPF_FLOW_DISSECTOR, 0);
64 	if (ret)
65 		error(1, 0, "bpf_prog_attach %s", cfg_path_name);
66 
67 	ret = bpf_object__pin(obj, cfg_pin_path);
68 	if (ret)
69 		error(1, 0, "bpf_object__pin %s", cfg_pin_path);
70 
71 }
72 
73 static void detach_program(void)
74 {
75 	char command[64];
76 	int ret;
77 
78 	ret = bpf_prog_detach(0, BPF_FLOW_DISSECTOR);
79 	if (ret)
80 		error(1, 0, "bpf_prog_detach");
81 
82 	/* To unpin, it is necessary and sufficient to just remove this dir */
83 	sprintf(command, "rm -r %s", cfg_pin_path);
84 	ret = system(command);
85 	if (ret)
86 		error(1, errno, command);
87 }
88 
89 static void parse_opts(int argc, char **argv)
90 {
91 	bool attach = false;
92 	bool detach = false;
93 	int c;
94 
95 	while ((c = getopt(argc, argv, "adp:s:")) != -1) {
96 		switch (c) {
97 		case 'a':
98 			if (detach)
99 				error(1, 0, "attach/detach are exclusive");
100 			attach = true;
101 			break;
102 		case 'd':
103 			if (attach)
104 				error(1, 0, "attach/detach are exclusive");
105 			detach = true;
106 			break;
107 		case 'p':
108 			if (cfg_path_name)
109 				error(1, 0, "only one prog name can be given");
110 
111 			cfg_path_name = optarg;
112 			break;
113 		case 's':
114 			if (cfg_section_name)
115 				error(1, 0, "only one section can be given");
116 
117 			cfg_section_name = optarg;
118 			break;
119 		}
120 	}
121 
122 	if (detach)
123 		cfg_attach = false;
124 
125 	if (cfg_attach && !cfg_path_name)
126 		error(1, 0, "must provide a path to the BPF program");
127 
128 	if (cfg_attach && !cfg_section_name)
129 		error(1, 0, "must provide a section name");
130 }
131 
132 int main(int argc, char **argv)
133 {
134 	parse_opts(argc, argv);
135 	if (cfg_attach)
136 		load_and_attach_program();
137 	else
138 		detach_program();
139 	return 0;
140 }
141