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 33 static bool running = true; 34 35 static void int_exit(int sig) 36 { 37 running = false; 38 exit(0); 39 } 40 41 static void usage(const char *prog) 42 { 43 fprintf(stderr, 44 "%s: %s /sys/bus/hid/devices/0BUS:0VID:0PID:00ID\n\n", 45 __func__, prog); 46 fprintf(stderr, 47 "This program will upload and attach a HID-BPF program to the given device.\n" 48 "On the Etekcity Scroll 6E, the X and Y axis will be inverted, but on any other\n" 49 "device, chances are high that the device will not be working anymore\n\n" 50 "consider this as a demo and adapt the eBPF program to your needs\n" 51 "Hit Ctrl-C to unbind the program and reset the device\n"); 52 } 53 54 static int get_hid_id(const char *path) 55 { 56 const char *str_id, *dir; 57 char uevent[1024]; 58 int fd; 59 60 memset(uevent, 0, sizeof(uevent)); 61 snprintf(uevent, sizeof(uevent) - 1, "%s/uevent", path); 62 63 fd = open(uevent, O_RDONLY | O_NONBLOCK); 64 if (fd < 0) 65 return -ENOENT; 66 67 close(fd); 68 69 dir = basename((char *)path); 70 71 str_id = dir + sizeof("0003:0001:0A37."); 72 return (int)strtol(str_id, NULL, 16); 73 } 74 75 int main(int argc, char **argv) 76 { 77 struct hid_mouse *skel; 78 struct bpf_link *link; 79 int err; 80 const char *optstr = ""; 81 const char *sysfs_path; 82 int opt, hid_id; 83 84 while ((opt = getopt(argc, argv, optstr)) != -1) { 85 switch (opt) { 86 default: 87 usage(basename(argv[0])); 88 return 1; 89 } 90 } 91 92 if (optind == argc) { 93 usage(basename(argv[0])); 94 return 1; 95 } 96 97 sysfs_path = argv[optind]; 98 if (!sysfs_path) { 99 perror("sysfs"); 100 return 1; 101 } 102 103 skel = hid_mouse__open(); 104 if (!skel) { 105 fprintf(stderr, "%s %s:%d", __func__, __FILE__, __LINE__); 106 return -1; 107 } 108 109 hid_id = get_hid_id(sysfs_path); 110 111 if (hid_id < 0) { 112 fprintf(stderr, "can not open HID device: %m\n"); 113 return 1; 114 } 115 skel->struct_ops.mouse_invert->hid_id = hid_id; 116 117 err = hid_mouse__load(skel); 118 if (err < 0) { 119 fprintf(stderr, "can not load HID-BPF program: %m\n"); 120 return 1; 121 } 122 123 link = bpf_map__attach_struct_ops(skel->maps.mouse_invert); 124 if (!link) { 125 fprintf(stderr, "can not attach HID-BPF program: %m\n"); 126 return 1; 127 } 128 129 signal(SIGINT, int_exit); 130 signal(SIGTERM, int_exit); 131 132 while (running) 133 sleep(1); 134 135 hid_mouse__destroy(skel); 136 137 return 0; 138 } 139