Linux内核:设置通过create_device()创建的/dev文件的权限 [英] Linux kernel : Setting the permissions for a /dev file that was created via create_device()

问题描述

我正在制作一个小的linux模块，该模块是char设备的驱动程序.在我的代码中，我创建了设备类，而不是设备本身，因此创建了/dev文件在我的系统中创建.问题是/dev文件仅具有root权限，而用户没有对该文件的读取，写入或执行权限，我想更改/dev文件权限.

I am making a small linux module that is a driver to a char device. In my code i create the device class, than the device it self and thus a /dev file is created in my system. the problem is that the /dev file has only root permissions and the user has neither read nor write nor execute permissions on that file, i would like to change the /dev file permissions.

我已经在网上搜索了答案，发现是要更改udev文件，但这解决方案不适用于我的情况，因为当模块加载到内核时，我需要动态更改权限.我正在编写的模块不会总是在我的机器上运行，因此我需要它来动态"更改权限.

I have searched the web for answers and what i found was to change the udev file, but this solution will not work in my case because i need the permissions to change dynamicly when the module is loaded into the kernel. The module i am writing will not always run on my machine, thus i need it to change the permissions "on the fly".

major_number_firewall = register_chrdev(0, device_name_firewall, &my_file_implementation_firewall);

device_class = class_create(THIS_MODULE, class_name_firewall);

log_file_device = device_create(device_class, NULL, MKDEV(major_number_firewall, MINOR_LOG), NULL, device_name_log_file);

是否具有更改权限的功能?

Is there a function for changing the permissions?

推荐答案

1. 您可以编写一个小的 udev规则来实现此目的.

如果要实现char设备驱动程序，请考虑使用 misc_register()和 misc_unregister()，它们是上述调用的包装(device_create() ...).请参考结构混合设备

If you are implementing a char device driver, then consider using misc_register() and misc_unregister() which is wrapper over the above calls (device_create()...). Refer to struct miscdevice

struct miscdevice  {
    int minor;
    const char *name;
    const struct file_operations *fops;
    struct list_head list;
    struct device *parent;
    struct device *this_device;
    const char *nodename;
    umode_t mode;
};

您可以使用成员(struct miscdevice *)-> mode 设置适当的权限(S_IRUGO | S_IRWXUGO | S_IALLUGO |等...)

You can use the member (struct miscdevice *)->mode to set the appropriate permissions (S_IRUGO | S_IRWXUGO | S_IALLUGO | etc ...)

希望这会有所帮助.

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