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