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