1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/ptrace.h>
4 #include <linux/bpf.h>
5 
6 #include <netinet/in.h>
7 
8 #include <bpf/bpf_helpers.h>
9 #include <bpf/bpf_tracing.h>
10 #include "bpf_misc.h"
11 
12 static struct sockaddr_in old;
13 
14 SEC("kprobe/" SYS_PREFIX "sys_connect")
15 int BPF_KPROBE(handle_sys_connect)
16 {
17 #if SYSCALL_WRAPPER == 1
18 	struct pt_regs *real_regs;
19 #endif
20 	struct sockaddr_in new;
21 	void *ptr;
22 
23 #if SYSCALL_WRAPPER == 0
24 	ptr = (void *)PT_REGS_PARM2(ctx);
25 #else
26 	real_regs = (struct pt_regs *)PT_REGS_PARM1(ctx);
27 	bpf_probe_read_kernel(&ptr, sizeof(ptr), &PT_REGS_PARM2(real_regs));
28 #endif
29 
30 	bpf_probe_read_user(&old, sizeof(old), ptr);
31 	__builtin_memset(&new, 0xab, sizeof(new));
32 	bpf_probe_write_user(ptr, &new, sizeof(new));
33 
34 	return 0;
35 }
36 
37 char _license[] SEC("license") = "GPL";
38