1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2023 Benjamin Tissoires
3 */
4
5 #include "vmlinux.h"
6 #include "hid_bpf.h"
7 #include "hid_bpf_helpers.h"
8 #include <bpf/bpf_tracing.h>
9
10 #define VID_HP 0x03F0
11 #define PID_ELITE_PRESENTER 0x464A
12
13 HID_BPF_CONFIG(
14 HID_DEVICE(BUS_BLUETOOTH, HID_GROUP_GENERIC, VID_HP, PID_ELITE_PRESENTER)
15 );
16
17 /*
18 * Already fixed as of commit 0db117359e47 ("HID: add quirk for 03f0:464a
19 * HP Elite Presenter Mouse") in the kernel, but this is a slightly better
20 * fix.
21 *
22 * The HP Elite Presenter Mouse HID Record Descriptor shows
23 * two mice (Report ID 0x1 and 0x2), one keypad (Report ID 0x5),
24 * two Consumer Controls (Report IDs 0x6 and 0x3).
25 * Prior to these fixes it registers one mouse, one keypad
26 * and one Consumer Control, and it was usable only as a
27 * digital laser pointer (one of the two mouses).
28 * We replace the second mouse collection with a pointer collection,
29 * allowing to use the device both as a mouse and a digital laser
30 * pointer.
31 */
32
SEC(HID_BPF_RDESC_FIXUP)33 SEC(HID_BPF_RDESC_FIXUP)
34 int BPF_PROG(hid_fix_rdesc, struct hid_bpf_ctx *hctx)
35 {
36 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
37
38 if (!data)
39 return 0; /* EPERM check */
40
41 /* replace application mouse by application pointer on the second collection */
42 if (data[79] == 0x02)
43 data[79] = 0x01;
44
45 return 0;
46 }
47
48 HID_BPF_OPS(hp_elite_presenter) = {
49 .hid_rdesc_fixup = (void *)hid_fix_rdesc,
50 };
51
52 SEC("syscall")
probe(struct hid_bpf_probe_args * ctx)53 int probe(struct hid_bpf_probe_args *ctx)
54 {
55 ctx->retval = ctx->rdesc_size != 264;
56 if (ctx->retval)
57 ctx->retval = -EINVAL;
58
59 return 0;
60 }
61
62 char _license[] SEC("license") = "GPL";
63