1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* Copyright (c) 2022 Benjamin Tissoires |
3 | * |
4 | * This is a pure HID-BPF example, and should be considered as such: |
5 | * on the Etekcity Scroll 6E, the X and Y axes will be swapped and |
6 | * inverted. On any other device... Not sure what this will do. |
7 | * |
8 | * This C main file is generic though. To adapt the code and test, users |
9 | * must amend only the .bpf.c file, which this program will load any |
10 | * eBPF program it finds. |
11 | */ |
12 | |
13 | #include <assert.h> |
14 | #include <errno.h> |
15 | #include <fcntl.h> |
16 | #include <libgen.h> |
17 | #include <signal.h> |
18 | #include <stdbool.h> |
19 | #include <stdio.h> |
20 | #include <stdlib.h> |
21 | #include <string.h> |
22 | #include <sys/resource.h> |
23 | #include <unistd.h> |
24 | |
25 | #include <linux/bpf.h> |
26 | #include <linux/errno.h> |
27 | |
28 | #include <bpf/bpf.h> |
29 | #include <bpf/libbpf.h> |
30 | |
31 | #include "hid_mouse.skel.h" |
32 | #include "hid_bpf_attach.h" |
33 | |
34 | static bool running = true; |
35 | |
36 | static void int_exit(int sig) |
37 | { |
38 | running = false; |
39 | exit(status: 0); |
40 | } |
41 | |
42 | static void usage(const char *prog) |
43 | { |
44 | fprintf(stderr, |
45 | format: "%s: %s /sys/bus/hid/devices/0BUS:0VID:0PID:00ID\n\n" , |
46 | __func__, prog); |
47 | fprintf(stderr, |
48 | format: "This program will upload and attach a HID-BPF program to the given device.\n" |
49 | "On the Etekcity Scroll 6E, the X and Y axis will be inverted, but on any other\n" |
50 | "device, chances are high that the device will not be working anymore\n\n" |
51 | "consider this as a demo and adapt the eBPF program to your needs\n" |
52 | "Hit Ctrl-C to unbind the program and reset the device\n" ); |
53 | } |
54 | |
55 | static int get_hid_id(const char *path) |
56 | { |
57 | const char *str_id, *dir; |
58 | char uevent[1024]; |
59 | int fd; |
60 | |
61 | memset(s: uevent, c: 0, n: sizeof(uevent)); |
62 | snprintf(s: uevent, maxlen: sizeof(uevent) - 1, format: "%s/uevent" , path); |
63 | |
64 | fd = open(file: uevent, O_RDONLY | O_NONBLOCK); |
65 | if (fd < 0) |
66 | return -ENOENT; |
67 | |
68 | close(fd: fd); |
69 | |
70 | dir = basename(path: (char *)path); |
71 | |
72 | str_id = dir + sizeof("0003:0001:0A37." ); |
73 | return (int)strtol(nptr: str_id, NULL, base: 16); |
74 | } |
75 | |
76 | int main(int argc, char **argv) |
77 | { |
78 | struct hid_mouse *skel; |
79 | struct bpf_program *prog; |
80 | int err; |
81 | const char *optstr = "" ; |
82 | const char *sysfs_path; |
83 | int opt, hid_id, attach_fd; |
84 | struct attach_prog_args args = { |
85 | .retval = -1, |
86 | }; |
87 | DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattr, |
88 | .ctx_in = &args, |
89 | .ctx_size_in = sizeof(args), |
90 | ); |
91 | |
92 | while ((opt = getopt(argc: argc, argv: argv, shortopts: optstr)) != -1) { |
93 | switch (opt) { |
94 | default: |
95 | usage(basename(path: argv[0])); |
96 | return 1; |
97 | } |
98 | } |
99 | |
100 | if (optind == argc) { |
101 | usage(basename(path: argv[0])); |
102 | return 1; |
103 | } |
104 | |
105 | sysfs_path = argv[optind]; |
106 | if (!sysfs_path) { |
107 | perror(s: "sysfs" ); |
108 | return 1; |
109 | } |
110 | |
111 | skel = hid_mouse__open_and_load(); |
112 | if (!skel) { |
113 | fprintf(stderr, format: "%s %s:%d" , __func__, __FILE__, __LINE__); |
114 | return -1; |
115 | } |
116 | |
117 | hid_id = get_hid_id(path: sysfs_path); |
118 | |
119 | if (hid_id < 0) { |
120 | fprintf(stderr, format: "can not open HID device: %m\n" ); |
121 | return 1; |
122 | } |
123 | args.hid = hid_id; |
124 | |
125 | attach_fd = bpf_program__fd(skel->progs.attach_prog); |
126 | if (attach_fd < 0) { |
127 | fprintf(stderr, format: "can't locate attach prog: %m\n" ); |
128 | return 1; |
129 | } |
130 | |
131 | bpf_object__for_each_program(prog, *skel->skeleton->obj) { |
132 | /* ignore syscalls */ |
133 | if (bpf_program__get_type(prog) != BPF_PROG_TYPE_TRACING) |
134 | continue; |
135 | |
136 | args.retval = -1; |
137 | args.prog_fd = bpf_program__fd(prog); |
138 | err = bpf_prog_test_run_opts(attach_fd, &tattr); |
139 | if (err) { |
140 | fprintf(stderr, format: "can't attach prog to hid device %d: %m (err: %d)\n" , |
141 | hid_id, err); |
142 | return 1; |
143 | } |
144 | } |
145 | |
146 | signal(SIGINT, handler: int_exit); |
147 | signal(SIGTERM, handler: int_exit); |
148 | |
149 | while (running) |
150 | sleep(seconds: 1); |
151 | |
152 | hid_mouse__destroy(skel); |
153 | |
154 | return 0; |
155 | } |
156 | |