forked from luck/tmp_suning_uos_patched
af9bd3e333
Currently, BPF programs with kprobe/sys_connect does not work properly. Commit34745aed51("samples/bpf: fix kprobe attachment issue on x64") This commit modifies the bpf_load behavior of kprobe events in the x64 architecture. If the current kprobe event target starts with "sys_*", add the prefix "__x64_" to the front of the event. Appending "__x64_" prefix with kprobe/sys_* event was appropriate as a solution to most of the problems caused by the commit below. commitd5a00528b5("syscalls/core, syscalls/x86: Rename struct pt_regs-based sys_*() to __x64_sys_*()") However, there is a problem with the sys_connect kprobe event that does not work properly. For __sys_connect event, parameters can be fetched normally, but for __x64_sys_connect, parameters cannot be fetched. ffffffff818d3520 <__x64_sys_connect>: ffffffff818d3520: e8 fb df 32 00 callq 0xffffffff81c01520 <__fentry__> ffffffff818d3525: 48 8b 57 60 movq 96(%rdi), %rdx ffffffff818d3529: 48 8b 77 68 movq 104(%rdi), %rsi ffffffff818d352d: 48 8b 7f 70 movq 112(%rdi), %rdi ffffffff818d3531: e8 1a ff ff ff callq 0xffffffff818d3450 <__sys_connect> ffffffff818d3536: 48 98 cltq ffffffff818d3538: c3 retq ffffffff818d3539: 0f 1f 80 00 00 00 00 nopl (%rax) As the assembly code for __x64_sys_connect shows, parameters should be fetched and set into rdi, rsi, rdx registers prior to calling __sys_connect. Because of this problem, this commit fixes the sys_connect event by first getting the value of the rdi register and then the value of the rdi, rsi, and rdx register through an offset based on that value. Fixes:34745aed51("samples/bpf: fix kprobe attachment issue on x64") Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200707184855.30968-2-danieltimlee@gmail.com
57 lines
1.8 KiB
C
57 lines
1.8 KiB
C
/* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include <linux/skbuff.h>
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#include <linux/netdevice.h>
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#include <uapi/linux/bpf.h>
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#include <linux/version.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include <bpf/bpf_core_read.h>
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#include "trace_common.h"
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struct bpf_map_def SEC("maps") dnat_map = {
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.type = BPF_MAP_TYPE_HASH,
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.key_size = sizeof(struct sockaddr_in),
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.value_size = sizeof(struct sockaddr_in),
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.max_entries = 256,
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};
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/* kprobe is NOT a stable ABI
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* kernel functions can be removed, renamed or completely change semantics.
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* Number of arguments and their positions can change, etc.
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* In such case this bpf+kprobe example will no longer be meaningful
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*
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* This example sits on a syscall, and the syscall ABI is relatively stable
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* of course, across platforms, and over time, the ABI may change.
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*/
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SEC("kprobe/" SYSCALL(sys_connect))
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int bpf_prog1(struct pt_regs *ctx)
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{
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struct pt_regs *real_regs = (struct pt_regs *)PT_REGS_PARM1_CORE(ctx);
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void *sockaddr_arg = (void *)PT_REGS_PARM2_CORE(real_regs);
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int sockaddr_len = (int)PT_REGS_PARM3_CORE(real_regs);
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struct sockaddr_in new_addr, orig_addr = {};
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struct sockaddr_in *mapped_addr;
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if (sockaddr_len > sizeof(orig_addr))
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return 0;
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if (bpf_probe_read_user(&orig_addr, sizeof(orig_addr), sockaddr_arg) != 0)
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return 0;
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mapped_addr = bpf_map_lookup_elem(&dnat_map, &orig_addr);
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if (mapped_addr != NULL) {
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memcpy(&new_addr, mapped_addr, sizeof(new_addr));
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bpf_probe_write_user(sockaddr_arg, &new_addr,
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sizeof(new_addr));
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}
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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u32 _version SEC("version") = LINUX_VERSION_CODE;
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