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