read_vsyscall.c

 1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (C) 2024. Huawei Technologies Co., Ltd */
 3#include "vmlinux.h"
 4#include <linux/types.h>
 5#include <bpf/bpf_helpers.h>
 6
 7#include "bpf_misc.h"
 8
 9int target_pid = 0;
10void *user_ptr = 0;
11int read_ret[10];
12
13char _license[] SEC("license") = "GPL";
14
15/*
16 * These are the kfuncs, the others are helpers
17 */
18int bpf_copy_from_user_str(void *dst, u32, const void *, u64) __weak __ksym;
19int bpf_copy_from_user_task_str(void *dst, u32, const void *,
20				struct task_struct *, u64) __weak __ksym;
21
22SEC("fentry/" SYS_PREFIX "sys_nanosleep")
23int do_probe_read(void *ctx)
24{
25	char buf[8];
26
27	if ((bpf_get_current_pid_tgid() >> 32) != target_pid)
28		return 0;
29
30	read_ret[0] = bpf_probe_read_kernel(buf, sizeof(buf), user_ptr);
31	read_ret[1] = bpf_probe_read_kernel_str(buf, sizeof(buf), user_ptr);
32	read_ret[2] = bpf_probe_read(buf, sizeof(buf), user_ptr);
33	read_ret[3] = bpf_probe_read_str(buf, sizeof(buf), user_ptr);
34	read_ret[4] = bpf_probe_read_user(buf, sizeof(buf), user_ptr);
35	read_ret[5] = bpf_probe_read_user_str(buf, sizeof(buf), user_ptr);
36
37	return 0;
38}
39
40SEC("fentry.s/" SYS_PREFIX "sys_nanosleep")
41int do_copy_from_user(void *ctx)
42{
43	char buf[8];
44
45	if ((bpf_get_current_pid_tgid() >> 32) != target_pid)
46		return 0;
47
48	read_ret[6] = bpf_copy_from_user(buf, sizeof(buf), user_ptr);
49	read_ret[7] = bpf_copy_from_user_task(buf, sizeof(buf), user_ptr,
50					      bpf_get_current_task_btf(), 0);
51	read_ret[8] = bpf_copy_from_user_str((char *)buf, sizeof(buf), user_ptr, 0);
52	read_ret[9] = bpf_copy_from_user_task_str((char *)buf,
53						  sizeof(buf),
54						  user_ptr,
55						  bpf_get_current_task_btf(),
56						  0);
57
58	return 0;
59}