1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 2
3 #include "vmlinux.h" 3 #include "vmlinux.h"
4 #include <bpf/bpf_helpers.h> 4 #include <bpf/bpf_helpers.h>
5 #include <bpf/bpf_tracing.h> 5 #include <bpf/bpf_tracing.h>
6 #include "hid_bpf_helpers.h" 6 #include "hid_bpf_helpers.h"
7 7
8 static int hid_y_event(struct hid_bpf_ctx *hct 8 static int hid_y_event(struct hid_bpf_ctx *hctx)
9 { 9 {
10 s16 y; 10 s16 y;
11 __u8 *data = hid_bpf_get_data(hctx, 0 11 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
12 12
13 if (!data) 13 if (!data)
14 return 0; /* EPERM check */ 14 return 0; /* EPERM check */
15 15
16 bpf_printk("event: size: %d", hctx->si 16 bpf_printk("event: size: %d", hctx->size);
17 bpf_printk("incoming event: %02x %02x 17 bpf_printk("incoming event: %02x %02x %02x",
18 data[0], 18 data[0],
19 data[1], 19 data[1],
20 data[2]); 20 data[2]);
21 bpf_printk(" %02x %02x 21 bpf_printk(" %02x %02x %02x",
22 data[3], 22 data[3],
23 data[4], 23 data[4],
24 data[5]); 24 data[5]);
25 bpf_printk(" %02x %02x 25 bpf_printk(" %02x %02x %02x",
26 data[6], 26 data[6],
27 data[7], 27 data[7],
28 data[8]); 28 data[8]);
29 29
30 y = data[3] | (data[4] << 8); 30 y = data[3] | (data[4] << 8);
31 31
32 y = -y; 32 y = -y;
33 33
34 data[3] = y & 0xFF; 34 data[3] = y & 0xFF;
35 data[4] = (y >> 8) & 0xFF; 35 data[4] = (y >> 8) & 0xFF;
36 36
37 bpf_printk("modified event: %02x %02x 37 bpf_printk("modified event: %02x %02x %02x",
38 data[0], 38 data[0],
39 data[1], 39 data[1],
40 data[2]); 40 data[2]);
41 bpf_printk(" %02x %02x 41 bpf_printk(" %02x %02x %02x",
42 data[3], 42 data[3],
43 data[4], 43 data[4],
44 data[5]); 44 data[5]);
45 bpf_printk(" %02x %02x 45 bpf_printk(" %02x %02x %02x",
46 data[6], 46 data[6],
47 data[7], 47 data[7],
48 data[8]); 48 data[8]);
49 49
50 return 0; 50 return 0;
51 } 51 }
52 52
53 static int hid_x_event(struct hid_bpf_ctx *hct 53 static int hid_x_event(struct hid_bpf_ctx *hctx)
54 { 54 {
55 s16 x; 55 s16 x;
56 __u8 *data = hid_bpf_get_data(hctx, 0 56 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
57 57
58 if (!data) 58 if (!data)
59 return 0; /* EPERM check */ 59 return 0; /* EPERM check */
60 60
61 x = data[1] | (data[2] << 8); 61 x = data[1] | (data[2] << 8);
62 62
63 x = -x; 63 x = -x;
64 64
65 data[1] = x & 0xFF; 65 data[1] = x & 0xFF;
66 data[2] = (x >> 8) & 0xFF; 66 data[2] = (x >> 8) & 0xFF;
67 return 0; 67 return 0;
68 } 68 }
69 69
70 SEC("struct_ops/hid_device_event") 70 SEC("struct_ops/hid_device_event")
71 int BPF_PROG(hid_event, struct hid_bpf_ctx *hc 71 int BPF_PROG(hid_event, struct hid_bpf_ctx *hctx, enum hid_report_type type)
72 { 72 {
73 int ret = hid_y_event(hctx); 73 int ret = hid_y_event(hctx);
74 74
75 if (ret) 75 if (ret)
76 return ret; 76 return ret;
77 77
78 return hid_x_event(hctx); 78 return hid_x_event(hctx);
79 } 79 }
80 80
81 81
82 SEC("struct_ops/hid_rdesc_fixup") 82 SEC("struct_ops/hid_rdesc_fixup")
83 int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_c 83 int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx)
84 { 84 {
85 __u8 *data = hid_bpf_get_data(hctx, 0 85 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
86 86
87 if (!data) 87 if (!data)
88 return 0; /* EPERM check */ 88 return 0; /* EPERM check */
89 89
90 bpf_printk("rdesc: %02x %02x %02x", 90 bpf_printk("rdesc: %02x %02x %02x",
91 data[0], 91 data[0],
92 data[1], 92 data[1],
93 data[2]); 93 data[2]);
94 bpf_printk(" %02x %02x %02x", 94 bpf_printk(" %02x %02x %02x",
95 data[3], 95 data[3],
96 data[4], 96 data[4],
97 data[5]); 97 data[5]);
98 bpf_printk(" %02x %02x %02x ..." 98 bpf_printk(" %02x %02x %02x ...",
99 data[6], 99 data[6],
100 data[7], 100 data[7],
101 data[8]); 101 data[8]);
102 102
103 /* 103 /*
104 * The original report descriptor cont 104 * The original report descriptor contains:
105 * 105 *
106 * 0x05, 0x01, // 106 * 0x05, 0x01, // Usage Page (Generic Desktop) 30
107 * 0x16, 0x01, 0x80, // 107 * 0x16, 0x01, 0x80, // Logical Minimum (-32767) 32
108 * 0x26, 0xff, 0x7f, // 108 * 0x26, 0xff, 0x7f, // Logical Maximum (32767) 35
109 * 0x09, 0x30, // 109 * 0x09, 0x30, // Usage (X) 38
110 * 0x09, 0x31, // 110 * 0x09, 0x31, // Usage (Y) 40
111 * 111 *
112 * So byte 39 contains Usage X and byt 112 * So byte 39 contains Usage X and byte 41 Usage Y.
113 * 113 *
114 * We simply swap the axes here. 114 * We simply swap the axes here.
115 */ 115 */
116 data[39] = 0x31; 116 data[39] = 0x31;
117 data[41] = 0x30; 117 data[41] = 0x30;
118 118
119 return 0; 119 return 0;
120 } 120 }
121 121
122 SEC(".struct_ops.link") 122 SEC(".struct_ops.link")
123 struct hid_bpf_ops mouse_invert = { 123 struct hid_bpf_ops mouse_invert = {
124 .hid_rdesc_fixup = (void *)hid_rdesc_f 124 .hid_rdesc_fixup = (void *)hid_rdesc_fixup,
125 .hid_device_event = (void *)hid_event, 125 .hid_device_event = (void *)hid_event,
126 }; 126 };
127 127
128 char _license[] SEC("license") = "GPL"; 128 char _license[] SEC("license") = "GPL";
129 129
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