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@bojieli
Created April 28, 2014 14:29
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detect link up/down and its initiator with kprobe
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/netdevice.h>
#include <linux/fs.h>
#include <linux/fs_struct.h>
/* For each probe you need to allocate a kprobe structure */
static struct kprobe kp = {
.symbol_name = "dev_change_flags",
};
#define BUFLEN 256
/* kprobe pre_handler: called just before the probed instruction is executed */
static int handler_pre(struct kprobe *p, struct pt_regs *regs)
{
printk(KERN_INFO "pre_handler: dev_change_flags called with rdi=%p rsi=%p rdx=%p rcx=%p\n",
(void *)regs->di, (void *)regs->si, (void *)regs->dx, (void *)regs->cx);
if (regs->di) {
char name[IFNAMSIZ + 1] = {0};
memcpy(name, ((struct net_device *)regs->di)->name, IFNAMSIZ);
printk(KERN_INFO "pre_handler: interface [%s] %s\n",
name, (regs->si & IFF_UP ? "up" : "down"));
if (current && current->fs) {
char buf[BUFLEN] = {0};
char *path = d_path(&current->fs->pwd, buf, BUFLEN);
if (path && path >= buf && path < buf + BUFLEN)
printk(KERN_INFO "pre_handler: process working dir: %s\n", path);
}
if (current && current->mm && current->mm->exe_file) {
char buf[BUFLEN] = {0};
char *path;
struct file *exe_file = current->mm->exe_file;
path_get(&exe_file->f_path);
path = d_path(&exe_file->f_path, buf, BUFLEN);
if (path && path >= buf && path < buf + BUFLEN)
printk(KERN_INFO "pre_handler: process exe path: %s\n", path);
}
printk(KERN_INFO "pre_handler: stack dump: ");
dump_stack();
} else {
printk(KERN_INFO "pre_handler: unexpected: rdi=0\n");
}
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)
{
}
/*
* 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");
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