mirror of
https://github.com/cirosantilli/linux-kernel-module-cheat.git
synced 2026-01-13 20:12:26 +00:00
73 lines
1.7 KiB
C
73 lines
1.7 KiB
C
/* https://cirosantilli.com/linux-kernel-module-cheat#ioctl */
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#include <linux/debugfs.h>
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#include <linux/module.h>
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#include <linux/printk.h> /* printk */
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#include <linux/uaccess.h> /* copy_from_user, copy_to_user */
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#include <lkmc/ioctl.h>
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static struct dentry *debugfs_file;
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static long unlocked_ioctl(struct file *filp, unsigned int cmd, unsigned long argp)
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{
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void __user *arg_user;
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union {
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int i;
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lkmc_ioctl_struct s;
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} arg_kernel;
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arg_user = (void __user *)argp;
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pr_info("cmd = %x\n", cmd);
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switch (cmd) {
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case LKMC_IOCTL_INC:
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if (copy_from_user(&arg_kernel.i, arg_user, sizeof(arg_kernel.i))) {
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return -EFAULT;
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}
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pr_info("0 arg = %d\n", arg_kernel.i);
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arg_kernel.i += 1;
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if (copy_to_user(arg_user, &arg_kernel.i, sizeof(arg_kernel.i))) {
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return -EFAULT;
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}
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break;
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case LKMC_IOCTL_INC_DEC:
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if (copy_from_user(&arg_kernel.s, arg_user, sizeof(arg_kernel.s))) {
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return -EFAULT;
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}
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pr_info("1 arg = %d %d\n", arg_kernel.s.i, arg_kernel.s.j);
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arg_kernel.s.i += 1;
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arg_kernel.s.j -= 1;
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if (copy_to_user(arg_user, &arg_kernel.s, sizeof(arg_kernel.s))) {
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return -EFAULT;
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}
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break;
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default:
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return -EINVAL;
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break;
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}
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return 0;
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}
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static const struct file_operations fops = {
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.owner = THIS_MODULE,
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.unlocked_ioctl = unlocked_ioctl
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};
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static int myinit(void)
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{
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/* ioctl permissions are not automatically restricted by rwx as for read / write,
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* but we could of course implement that ourselves:
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* https://stackoverflow.com/questions/29891803/user-permission-check-on-ioctl-command */
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debugfs_file = debugfs_create_file("lkmc_ioctl", 0, NULL, NULL, &fops);
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return 0;
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}
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static void myexit(void)
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{
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debugfs_remove(debugfs_file);
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}
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module_init(myinit)
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module_exit(myexit)
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MODULE_LICENSE("GPL");
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