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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2022 Benjamin Tissoires
*
* This is a pure HID-BPF example, and should be considered as such:
* on the Etekcity Scroll 6E, the X and Y axes will be swapped and
* inverted. On any other device... Not sure what this will do.
*
* This C main file is generic though. To adapt the code and test, users
* must amend only the .bpf.c file, which this program will load any
* eBPF program it finds.
*/
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
#include <unistd.h>
#include <linux/bpf.h>
#include <linux/errno.h>
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
#include "hid_mouse.skel.h"
#include "hid_bpf_attach.h"
static bool running = true;
static void int_exit(int sig)
{
running = false;
exit(0);
}
static void usage(const char *prog)
{
fprintf(stderr,
"%s: %s /sys/bus/hid/devices/0BUS:0VID:0PID:00ID\n\n",
__func__, prog);
fprintf(stderr,
"This program will upload and attach a HID-BPF program to the given device.\n"
"On the Etekcity Scroll 6E, the X and Y axis will be inverted, but on any other\n"
"device, chances are high that the device will not be working anymore\n\n"
"consider this as a demo and adapt the eBPF program to your needs\n"
"Hit Ctrl-C to unbind the program and reset the device\n");
}
static int get_hid_id(const char *path)
{
const char *str_id, *dir;
char uevent[1024];
int fd;
memset(uevent, 0, sizeof(uevent));
snprintf(uevent, sizeof(uevent) - 1, "%s/uevent", path);
fd = open(uevent, O_RDONLY | O_NONBLOCK);
if (fd < 0)
return -ENOENT;
close(fd);
dir = basename((char *)path);
str_id = dir + sizeof("0003:0001:0A37.");
return (int)strtol(str_id, NULL, 16);
}
int main(int argc, char **argv)
{
struct hid_mouse *skel;
struct bpf_program *prog;
int err;
const char *optstr = "";
const char *sysfs_path;
int opt, hid_id, attach_fd;
struct attach_prog_args args = {
.retval = -1,
};
DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattr,
.ctx_in = &args,
.ctx_size_in = sizeof(args),
);
while ((opt = getopt(argc, argv, optstr)) != -1) {
switch (opt) {
default:
usage(basename(argv[0]));
return 1;
}
}
if (optind == argc) {
usage(basename(argv[0]));
return 1;
}
sysfs_path = argv[optind];
if (!sysfs_path) {
perror("sysfs");
return 1;
}
skel = hid_mouse__open_and_load();
if (!skel) {
fprintf(stderr, "%s %s:%d", __func__, __FILE__, __LINE__);
return -1;
}
hid_id = get_hid_id(sysfs_path);
if (hid_id < 0) {
fprintf(stderr, "can not open HID device: %m\n");
return 1;
}
args.hid = hid_id;
attach_fd = bpf_program__fd(skel->progs.attach_prog);
if (attach_fd < 0) {
fprintf(stderr, "can't locate attach prog: %m\n");
return 1;
}
bpf_object__for_each_program(prog, *skel->skeleton->obj) {
/* ignore syscalls */
if (bpf_program__get_type(prog) != BPF_PROG_TYPE_TRACING)
continue;
args.retval = -1;
args.prog_fd = bpf_program__fd(prog);
err = bpf_prog_test_run_opts(attach_fd, &tattr);
if (err) {
fprintf(stderr, "can't attach prog to hid device %d: %m (err: %d)\n",
hid_id, err);
return 1;
}
}
signal(SIGINT, int_exit);
signal(SIGTERM, int_exit);
while (running)
sleep(1);
hid_mouse__destroy(skel);
return 0;
}
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