mirror of
https://github.com/torvalds/linux.git
synced 2024-11-22 12:11:40 +00:00
c5ffb26375
This commit enhances the syscall tracing programs by using the BPF_SYSCALL macro to reduce the inconvenience of parsing arguments from pt_regs. By simplifying argument extraction, bpf program will become clear to understand. Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20221224071527.2292-6-danieltimlee@gmail.com
53 lines
1.6 KiB
C
53 lines
1.6 KiB
C
/* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of version 2 of the GNU General Public
|
|
* License as published by the Free Software Foundation.
|
|
*/
|
|
#include "vmlinux.h"
|
|
#include <string.h>
|
|
#include <linux/version.h>
|
|
#include <bpf/bpf_helpers.h>
|
|
#include <bpf/bpf_tracing.h>
|
|
#include <bpf/bpf_core_read.h>
|
|
|
|
struct {
|
|
__uint(type, BPF_MAP_TYPE_HASH);
|
|
__type(key, struct sockaddr_in);
|
|
__type(value, struct sockaddr_in);
|
|
__uint(max_entries, 256);
|
|
} dnat_map SEC(".maps");
|
|
|
|
/* kprobe is NOT a stable ABI
|
|
* kernel functions can be removed, renamed or completely change semantics.
|
|
* Number of arguments and their positions can change, etc.
|
|
* In such case this bpf+kprobe example will no longer be meaningful
|
|
*
|
|
* This example sits on a syscall, and the syscall ABI is relatively stable
|
|
* of course, across platforms, and over time, the ABI may change.
|
|
*/
|
|
SEC("ksyscall/connect")
|
|
int BPF_KSYSCALL(bpf_prog1, int fd, struct sockaddr_in *uservaddr,
|
|
int addrlen)
|
|
{
|
|
struct sockaddr_in new_addr, orig_addr = {};
|
|
struct sockaddr_in *mapped_addr;
|
|
|
|
if (addrlen > sizeof(orig_addr))
|
|
return 0;
|
|
|
|
if (bpf_probe_read_user(&orig_addr, sizeof(orig_addr), uservaddr) != 0)
|
|
return 0;
|
|
|
|
mapped_addr = bpf_map_lookup_elem(&dnat_map, &orig_addr);
|
|
if (mapped_addr != NULL) {
|
|
memcpy(&new_addr, mapped_addr, sizeof(new_addr));
|
|
bpf_probe_write_user(uservaddr, &new_addr,
|
|
sizeof(new_addr));
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
char _license[] SEC("license") = "GPL";
|
|
u32 _version SEC("version") = LINUX_VERSION_CODE;
|