我该如何解决 copy_from_user 不起作用的问题?
how can I fix copy_from_user doesn't work?
我正在尝试在 Linux 中编写加密驱动程序,但是当我使用 copy_from_user()
加密字符串并将其复制到缓冲区时,它不起作用并且 k 值为字符串中的字符数
如果我将 copy_from_user
中的 temp
更改为 buf
它可以正常工作
ssize_t encdec_write_caesar(struct file *filp, const char *buf, size_t count, loff_t *f_pos)
{
char *temp ;
temp = kmalloc(memory_size * sizeof(char),GFP_USER);
memset(temp, 0, memory_size);
int i , k ;
k = ((encdec_private_date *)(filp->private_data))->key;
for(i = 0; i < count; i++)
{
temp[i] = (buf[i] + k) % 128;
}
k = copy_from_user ( caesar_Buf , temp , count);
printk("write-> %d\n" ,k);
kfree(temp);
return 0;
}
这是代码的一部分
#include <linux/ctype.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
#include <linux/fcntl.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/string.h>
#include "encdec.h"
#define MODULE_NAME "encdec"
MODULE_LICENSE("GPL");
MODULE_AUTHOR("YOUR NAME");
int encdec_open(struct inode *inode, struct file *filp);
int encdec_release(struct inode *inode, struct file *filp);
int encdec_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg);
ssize_t encdec_read_caesar( struct file *filp, char *buf, size_t count, loff_t *f_pos );
ssize_t encdec_write_caesar(struct file *filp, const char *buf, size_t count, loff_t *f_pos);
int memory_size = 0;
MODULE_PARM(memory_size, "i");
int major = 0;
char *caesar_Buf = NULL;
struct file_operations fops_caesar = {
.open = encdec_open,
.release = encdec_release,
.read = encdec_read_caesar,
.write = encdec_write_caesar,
.llseek = NULL,
.ioctl = encdec_ioctl,
.owner = THIS_MODULE
};
// Implemetation suggestion:
// -------------------------
// Use this structure as your file-object's private data structure
typedef struct {
unsigned char key;
int read_state;
} encdec_private_date;
int init_module(void)
{
major = register_chrdev(major, MODULE_NAME, &fops_caesar);
if(major < 0)
{
return major;
}
caesar_Buf = (char *)kmalloc(memory_size * sizeof(char),GFP_KERNEL);
return 0;
}
您应该使用 copy_from_user
而不是直接访问 buf
(在循环内,而不是在访问 temp
时(在 kernel-space 内存中。)
copy_from_user
旨在确保在用户上下文中访问仅访问 user-space 数据——即,有人不会在系统调用中传递指向内核内存的指针并泄漏数据来自内核。
我正在尝试在 Linux 中编写加密驱动程序,但是当我使用 copy_from_user()
加密字符串并将其复制到缓冲区时,它不起作用并且 k 值为字符串中的字符数
如果我将 copy_from_user
中的 temp
更改为 buf
它可以正常工作
ssize_t encdec_write_caesar(struct file *filp, const char *buf, size_t count, loff_t *f_pos)
{
char *temp ;
temp = kmalloc(memory_size * sizeof(char),GFP_USER);
memset(temp, 0, memory_size);
int i , k ;
k = ((encdec_private_date *)(filp->private_data))->key;
for(i = 0; i < count; i++)
{
temp[i] = (buf[i] + k) % 128;
}
k = copy_from_user ( caesar_Buf , temp , count);
printk("write-> %d\n" ,k);
kfree(temp);
return 0;
}
这是代码的一部分
#include <linux/ctype.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
#include <linux/fcntl.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/string.h>
#include "encdec.h"
#define MODULE_NAME "encdec"
MODULE_LICENSE("GPL");
MODULE_AUTHOR("YOUR NAME");
int encdec_open(struct inode *inode, struct file *filp);
int encdec_release(struct inode *inode, struct file *filp);
int encdec_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg);
ssize_t encdec_read_caesar( struct file *filp, char *buf, size_t count, loff_t *f_pos );
ssize_t encdec_write_caesar(struct file *filp, const char *buf, size_t count, loff_t *f_pos);
int memory_size = 0;
MODULE_PARM(memory_size, "i");
int major = 0;
char *caesar_Buf = NULL;
struct file_operations fops_caesar = {
.open = encdec_open,
.release = encdec_release,
.read = encdec_read_caesar,
.write = encdec_write_caesar,
.llseek = NULL,
.ioctl = encdec_ioctl,
.owner = THIS_MODULE
};
// Implemetation suggestion:
// -------------------------
// Use this structure as your file-object's private data structure
typedef struct {
unsigned char key;
int read_state;
} encdec_private_date;
int init_module(void)
{
major = register_chrdev(major, MODULE_NAME, &fops_caesar);
if(major < 0)
{
return major;
}
caesar_Buf = (char *)kmalloc(memory_size * sizeof(char),GFP_KERNEL);
return 0;
}
您应该使用 copy_from_user
而不是直接访问 buf
(在循环内,而不是在访问 temp
时(在 kernel-space 内存中。)
copy_from_user
旨在确保在用户上下文中访问仅访问 user-space 数据——即,有人不会在系统调用中传递指向内核内存的指针并泄漏数据来自内核。