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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Red hat */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include "hid_bpf_helpers.h"
char _license[] SEC("license") = "GPL";
struct attach_prog_args {
int prog_fd;
unsigned int hid;
int retval;
int insert_head;
};
__u64 callback_check = 52;
__u64 callback2_check = 52;
SEC("?fmod_ret/hid_bpf_device_event")
int BPF_PROG(hid_first_event, struct hid_bpf_ctx *hid_ctx)
{
__u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 3 /* size */);
if (!rw_data)
return 0; /* EPERM check */
callback_check = rw_data[1];
rw_data[2] = rw_data[1] + 5;
return hid_ctx->size;
}
SEC("?fmod_ret/hid_bpf_device_event")
int BPF_PROG(hid_second_event, struct hid_bpf_ctx *hid_ctx)
{
__u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4 /* size */);
if (!rw_data)
return 0; /* EPERM check */
rw_data[3] = rw_data[2] + 5;
return hid_ctx->size;
}
SEC("?fmod_ret/hid_bpf_device_event")
int BPF_PROG(hid_change_report_id, struct hid_bpf_ctx *hid_ctx)
{
__u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 3 /* size */);
if (!rw_data)
return 0; /* EPERM check */
rw_data[0] = 2;
return 9;
}
SEC("syscall")
int attach_prog(struct attach_prog_args *ctx)
{
ctx->retval = hid_bpf_attach_prog(ctx->hid,
ctx->prog_fd,
ctx->insert_head ? HID_BPF_FLAG_INSERT_HEAD :
HID_BPF_FLAG_NONE);
return 0;
}
struct hid_hw_request_syscall_args {
/* data needs to come at offset 0 so we can use it in calls */
__u8 data[10];
unsigned int hid;
int retval;
size_t size;
enum hid_report_type type;
__u8 request_type;
};
SEC("syscall")
int hid_user_raw_request(struct hid_hw_request_syscall_args *args)
{
struct hid_bpf_ctx *ctx;
const size_t size = args->size;
int i, ret = 0;
if (size > sizeof(args->data))
return -7; /* -E2BIG */
ctx = hid_bpf_allocate_context(args->hid);
if (!ctx)
return -1; /* EPERM check */
ret = hid_bpf_hw_request(ctx,
args->data,
size,
args->type,
args->request_type);
args->retval = ret;
hid_bpf_release_context(ctx);
return 0;
}
static const __u8 rdesc[] = {
0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
0x09, 0x32, /* USAGE (Z) */
0x95, 0x01, /* REPORT_COUNT (1) */
0x81, 0x06, /* INPUT (Data,Var,Rel) */
0x06, 0x00, 0xff, /* Usage Page (Vendor Defined Page 1) */
0x19, 0x01, /* USAGE_MINIMUM (1) */
0x29, 0x03, /* USAGE_MAXIMUM (3) */
0x15, 0x00, /* LOGICAL_MINIMUM (0) */
0x25, 0x01, /* LOGICAL_MAXIMUM (1) */
0x95, 0x03, /* REPORT_COUNT (3) */
0x75, 0x01, /* REPORT_SIZE (1) */
0x91, 0x02, /* Output (Data,Var,Abs) */
0x95, 0x01, /* REPORT_COUNT (1) */
0x75, 0x05, /* REPORT_SIZE (5) */
0x91, 0x01, /* Output (Cnst,Var,Abs) */
0x06, 0x00, 0xff, /* Usage Page (Vendor Defined Page 1) */
0x19, 0x06, /* USAGE_MINIMUM (6) */
0x29, 0x08, /* USAGE_MAXIMUM (8) */
0x15, 0x00, /* LOGICAL_MINIMUM (0) */
0x25, 0x01, /* LOGICAL_MAXIMUM (1) */
0x95, 0x03, /* REPORT_COUNT (3) */
0x75, 0x01, /* REPORT_SIZE (1) */
0xb1, 0x02, /* Feature (Data,Var,Abs) */
0x95, 0x01, /* REPORT_COUNT (1) */
0x75, 0x05, /* REPORT_SIZE (5) */
0x91, 0x01, /* Output (Cnst,Var,Abs) */
0xc0, /* END_COLLECTION */
0xc0, /* END_COLLECTION */
};
SEC("?fmod_ret/hid_bpf_rdesc_fixup")
int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hid_ctx)
{
__u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4096 /* size */);
if (!data)
return 0; /* EPERM check */
callback2_check = data[4];
/* insert rdesc at offset 73 */
__builtin_memcpy(&data[73], rdesc, sizeof(rdesc));
/* Change Usage Vendor globally */
data[4] = 0x42;
return sizeof(rdesc) + 73;
}
SEC("?fmod_ret/hid_bpf_device_event")
int BPF_PROG(hid_test_insert1, struct hid_bpf_ctx *hid_ctx)
{
__u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4 /* size */);
if (!data)
return 0; /* EPERM check */
/* we need to be run first */
if (data[2] || data[3])
return -1;
data[1] = 1;
return 0;
}
SEC("?fmod_ret/hid_bpf_device_event")
int BPF_PROG(hid_test_insert2, struct hid_bpf_ctx *hid_ctx)
{
__u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4 /* size */);
if (!data)
return 0; /* EPERM check */
/* after insert0 and before insert2 */
if (!data[1] || data[3])
return -1;
data[2] = 2;
return 0;
}
SEC("?fmod_ret/hid_bpf_device_event")
int BPF_PROG(hid_test_insert3, struct hid_bpf_ctx *hid_ctx)
{
__u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4 /* size */);
if (!data)
return 0; /* EPERM check */
/* at the end */
if (!data[1] || !data[2])
return -1;
data[3] = 3;
return 0;
}
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