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 13 HID_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 28 SEC(HID_BPF_RDESC_FIXUP) 29 int 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 59 HID_BPF_OPS(logitech_spacenavigator) = { 60 .hid_rdesc_fixup = (void *)hid_fix_rdesc, 61 }; 62 63 SEC("syscall") 64 int 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 86 char _license[] SEC("license") = "GPL"; 87