register_kretprobe 失败,return 值为 -2
register_kretprobe fails with a return value of -2
我写了一个 kretprobe 来连接到 fs/binfmt_elf.c 文件中提到的 randomize_stack_top() 函数。在使用 insmod 加载 LKM 时,register_kretprobe() 调用失败,return 值为 -2。我该如何处理 debugging/rectifying 才能启动我的模块?
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/binfmts.h>
#include <linux/elf.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <asm/uaccess.h>
#include <asm/current.h>
#include <asm/param.h>
/* Global variables */
int randomize_stack_retval;
// randomize_stack_top() kretprobe specific declarations
static char stack_name[NAME_MAX] = "randomize_stack_top";
static int randomize_stack_top_entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
return 0;
}
static int randomize_stack_top_ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
randomize_stack_retval = regs_return_value(regs); //store in global variable
printk(KERN_INFO "%d\n",randomize_stack_retval);
return 0;
}
//randomize_stack_top return probe
static struct kretprobe randomize_kretprobe = {
.handler = randomize_stack_top_ret_handler,
.entry_handler = randomize_stack_top_entry_handler,
.maxactive = NR_CPUS,
};
/* Register kretprobe */
static int __init kretprobe_init(void)
{
int ret;
randomize_kretprobe.kp.symbol_name = stack_name;
ret = register_kretprobe(&randomize_kretprobe);
if (ret < 0) {
printk(KERN_INFO "register_kretprobe failed, returned %d\n",
ret);
return -1;
}
printk(KERN_INFO "Planted return probe at %s: %p\n",
randomize_kretprobe.kp.symbol_name, randomize_kretprobe.kp.addr);
return 0;
}
/* Unregister kretprobe */
static void __exit kretprobe_exit(void)
{
unregister_kretprobe(&randomize_kretprobe);
printk(KERN_INFO "kretprobe at %p unregistered\n",
randomize_kretprobe.kp.addr);
// nmissed > 0 suggests that maxactive was set too low.
printk(KERN_INFO "Missed probing %d instances of %s\n",
randomize_kretprobe.nmissed, randomize_kretprobe.kp.symbol_name);
}
module_init(kretprobe_init);
module_exit(kretprobe_exit);
MODULE_LICENSE("GPL");
-2对应于-ENOENT
(你可以在include/uapi/asm-generic/errno-base.h
中查看)。可能,这意味着 kprobe 找不到具有给定名称的符号。
请注意,randomize_stack_top
是具有简短实现的静态函数,并且仅使用一次。所以它可以被 gcc 内联。
我写了一个 kretprobe 来连接到 fs/binfmt_elf.c 文件中提到的 randomize_stack_top() 函数。在使用 insmod 加载 LKM 时,register_kretprobe() 调用失败,return 值为 -2。我该如何处理 debugging/rectifying 才能启动我的模块?
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/binfmts.h>
#include <linux/elf.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <asm/uaccess.h>
#include <asm/current.h>
#include <asm/param.h>
/* Global variables */
int randomize_stack_retval;
// randomize_stack_top() kretprobe specific declarations
static char stack_name[NAME_MAX] = "randomize_stack_top";
static int randomize_stack_top_entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
return 0;
}
static int randomize_stack_top_ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
randomize_stack_retval = regs_return_value(regs); //store in global variable
printk(KERN_INFO "%d\n",randomize_stack_retval);
return 0;
}
//randomize_stack_top return probe
static struct kretprobe randomize_kretprobe = {
.handler = randomize_stack_top_ret_handler,
.entry_handler = randomize_stack_top_entry_handler,
.maxactive = NR_CPUS,
};
/* Register kretprobe */
static int __init kretprobe_init(void)
{
int ret;
randomize_kretprobe.kp.symbol_name = stack_name;
ret = register_kretprobe(&randomize_kretprobe);
if (ret < 0) {
printk(KERN_INFO "register_kretprobe failed, returned %d\n",
ret);
return -1;
}
printk(KERN_INFO "Planted return probe at %s: %p\n",
randomize_kretprobe.kp.symbol_name, randomize_kretprobe.kp.addr);
return 0;
}
/* Unregister kretprobe */
static void __exit kretprobe_exit(void)
{
unregister_kretprobe(&randomize_kretprobe);
printk(KERN_INFO "kretprobe at %p unregistered\n",
randomize_kretprobe.kp.addr);
// nmissed > 0 suggests that maxactive was set too low.
printk(KERN_INFO "Missed probing %d instances of %s\n",
randomize_kretprobe.nmissed, randomize_kretprobe.kp.symbol_name);
}
module_init(kretprobe_init);
module_exit(kretprobe_exit);
MODULE_LICENSE("GPL");
-2对应于-ENOENT
(你可以在include/uapi/asm-generic/errno-base.h
中查看)。可能,这意味着 kprobe 找不到具有给定名称的符号。
请注意,randomize_stack_top
是具有简短实现的静态函数,并且仅使用一次。所以它可以被 gcc 内联。