mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
3677d0a131
For the problem of increasing fragmentation of the bpf loader programs,
instead of using bpf_loader.o, which is used in samples/bpf, this
commit refactors the existing kprobe tracing programs with libbbpf
bpf loader.
- For kprobe events pointing to system calls, the SYSCALL() macro in
trace_common.h was used.
- Adding a kprobe event and attaching a bpf program to it was done
through bpf_program_attach().
- Instead of using the existing BPF MAP definition, MAP definition
has been refactored with the new BTF-defined MAP format.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200823085334.9413-3-danieltimlee@gmail.com
56 lines
1.8 KiB
C
56 lines
1.8 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 <linux/skbuff.h>
|
|
#include <linux/netdevice.h>
|
|
#include <uapi/linux/bpf.h>
|
|
#include <linux/version.h>
|
|
#include <bpf/bpf_helpers.h>
|
|
#include <bpf/bpf_tracing.h>
|
|
#include <bpf/bpf_core_read.h>
|
|
#include "trace_common.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("kprobe/" SYSCALL(sys_connect))
|
|
int bpf_prog1(struct pt_regs *ctx)
|
|
{
|
|
struct pt_regs *real_regs = (struct pt_regs *)PT_REGS_PARM1_CORE(ctx);
|
|
void *sockaddr_arg = (void *)PT_REGS_PARM2_CORE(real_regs);
|
|
int sockaddr_len = (int)PT_REGS_PARM3_CORE(real_regs);
|
|
struct sockaddr_in new_addr, orig_addr = {};
|
|
struct sockaddr_in *mapped_addr;
|
|
|
|
if (sockaddr_len > sizeof(orig_addr))
|
|
return 0;
|
|
|
|
if (bpf_probe_read_user(&orig_addr, sizeof(orig_addr), sockaddr_arg) != 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(sockaddr_arg, &new_addr,
|
|
sizeof(new_addr));
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
char _license[] SEC("license") = "GPL";
|
|
u32 _version SEC("version") = LINUX_VERSION_CODE;
|