kprobe 内核模块

代码来自于linux内核sample/kprobe

kprobe_example.c

/* * NOTE: This example is works on x86 and powerpc. * Here‘s a sample kernel module showing the use of kprobes to dump a * stack trace and selected registers when do_fork() is called. * * For more information on theory of operation of kprobes, see * Documentation/kprobes.txt * * You will see the trace data in /var/log/messages and on the console * whenever do_fork() is invoked to create a new process. */

#include <linux/kernel.h>#include <linux/module.h>#include <linux/kprobes.h>

/* For each probe you need to allocate a kprobe structure */static struct kprobe kp = {    .symbol_name    = "do_fork",};

/* kprobe pre_handler: called just before the probed instruction is executed */static int handler_pre(struct kprobe *p, struct pt_regs *regs){#ifdef CONFIG_X86    printk(KERN_INFO "pre_handler: p->addr = 0x%p, ip = %lx,"            " flags = 0x%lx\n",        p->addr, regs->ip, regs->flags);#endif#ifdef CONFIG_PPC    printk(KERN_INFO "pre_handler: p->addr = 0x%p, nip = 0x%lx,"            " msr = 0x%lx\n",        p->addr, regs->nip, regs->msr);#endif#ifdef CONFIG_MIPS    printk(KERN_INFO "pre_handler: p->addr = 0x%p, epc = 0x%lx,"            " status = 0x%lx\n",        p->addr, regs->cp0_epc, regs->cp0_status);#endif

    /* A dump_stack() here will give a stack backtrace */    return 0;}

/* kprobe post_handler: called after the probed instruction is executed */static void handler_post(struct kprobe *p, struct pt_regs *regs,                unsigned long flags){#ifdef CONFIG_X86    printk(KERN_INFO "post_handler: p->addr = 0x%p, flags = 0x%lx\n",        p->addr, regs->flags);#endif#ifdef CONFIG_PPC    printk(KERN_INFO "post_handler: p->addr = 0x%p, msr = 0x%lx\n",        p->addr, regs->msr);#endif#ifdef CONFIG_MIPS    printk(KERN_INFO "post_handler: p->addr = 0x%p, status = 0x%lx\n",        p->addr, regs->cp0_status);#endif}

/* * fault_handler: this is called if an exception is generated for any * instruction within the pre- or post-handler, or when Kprobes * single-steps the probed instruction. */static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr){    printk(KERN_INFO "fault_handler: p->addr = 0x%p, trap #%dn",        p->addr, trapnr);    /* Return 0 because we don‘t handle the fault. */    return 0;}

static int __init kprobe_init(void){    int ret;    kp.pre_handler = handler_pre;    kp.post_handler = handler_post;    kp.fault_handler = handler_fault;

    ret = register_kprobe(&kp);    if (ret < 0) {        printk(KERN_INFO "register_kprobe failed, returned %d\n", ret);        return ret;    }    printk(KERN_INFO "Planted kprobe at %p\n", kp.addr);    return 0;}

static void __exit kprobe_exit(void){    unregister_kprobe(&kp);    printk(KERN_INFO "kprobe at %p unregistered\n", kp.addr);}

module_init(kprobe_init)module_exit(kprobe_exit)MODULE_LICENSE("GPL");

makefile 如下：

obj-m := kprobe-example.o KDIR := /lib/modules/$(shell uname -r)/buildPWD := $(shell pwd)default:    $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modulesclean:    rm -f *.mod.c *.ko *.o

su root

insmod kprobe-example.ko

cat /var/log/messages 查看消息

lsmod | grep krpobe

rm kprobe-example.ko