Logitech__SpaceNavigator.bpf.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/* Copyright (c) 2025 Curran Muhlberger
 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_LOGITECH 0x046D
11#define PID_SPACENAVIGATOR 0xC626
12
13HID_BPF_CONFIG(
14	HID_DEVICE(BUS_USB, HID_GROUP_ANY, VID_LOGITECH, PID_SPACENAVIGATOR)
15);
16
17/*
18 * The 3Dconnexion SpaceNavigator 3D Mouse is a multi-axis controller with 6
19 * axes (grouped as X,Y,Z and Rx,Ry,Rz).  Axis data is absolute, but the report
20 * descriptor erroneously declares it to be relative.  We fix the report
21 * descriptor to mark both axis collections as absolute.
22 *
23 * The kernel attempted to fix this in commit 24985cf68612 (HID: support
24 * Logitech/3DConnexion SpaceTraveler and SpaceNavigator), but the descriptor
25 * data offsets are incorrect for at least some SpaceNavigator units.
26 */
27
28SEC(HID_BPF_RDESC_FIXUP)
29int BPF_PROG(hid_fix_rdesc, struct hid_bpf_ctx *hctx)
30{
31	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
32
33	if (!data)
34		return 0; /* EPERM check */
35
36	/* Offset of Input item in X,Y,Z and Rx,Ry,Rz collections for all known
37	 * firmware variants.
38	 * - 2009 model: X,Y,Z @ 32-33, Rx,Ry,Rz @ 49-50 (fixup originally
39	 *   applied in kernel)
40	 * - 2016 model (size==228): X,Y,Z @ 36-37, Rx,Ry,Rz @ 53-54
41	 *
42	 * The descriptor size of the 2009 model is not known, and there is evidence
43	 * for at least two other variants (with sizes 202 & 217) besides the 2016
44	 * model, so we try all known offsets regardless of descriptor size.
45	 */
46	const u8 offsets[] = {32, 36, 49, 53};
47
48	for (size_t idx = 0; idx < ARRAY_SIZE(offsets); idx++) {
49		u8 offset = offsets[idx];
50
51		/* if Input (Data,Var,Rel) , make it Input (Data,Var,Abs) */
52		if (data[offset] == 0x81 && data[offset + 1] == 0x06)
53			data[offset + 1] = 0x02;
54	}
55
56	return 0;
57}
58
59HID_BPF_OPS(logitech_spacenavigator) = {
60	.hid_rdesc_fixup = (void *)hid_fix_rdesc,
61};
62
63SEC("syscall")
64int probe(struct hid_bpf_probe_args *ctx)
65{
66	/* Ensure report descriptor size matches one of the known variants. */
67	if (ctx->rdesc_size != 202 &&
68	    ctx->rdesc_size != 217 &&
69	    ctx->rdesc_size != 228) {
70		ctx->retval = -EINVAL;
71		return 0;
72	}
73
74	/* Check whether the kernel has already applied the fix. */
75	if ((ctx->rdesc[32] == 0x81 && ctx->rdesc[33] == 0x02 &&
76	     ctx->rdesc[49] == 0x81 && ctx->rdesc[50] == 0x02) ||
77	    (ctx->rdesc[36] == 0x81 && ctx->rdesc[37] == 0x02 &&
78	     ctx->rdesc[53] == 0x81 && ctx->rdesc[54] == 0x02))
79		ctx->retval = -EINVAL;
80	else
81		ctx->retval = 0;
82
83	return 0;
84}
85
86char _license[] SEC("license") = "GPL";