读取内核空间中的符号链接 [英] Reading a symbolic link in kernel-space

问题描述

我正在编写LKM，需要找出特定符号链接指向的位置.基本上，我需要系统调用readlinkat(或readlink)的功能，但要在内核空间中.有没有简单的方法可以做到这一点?

I'm writing a LKM and need to find out where a specific symlink is pointing to. Basically I need the functionality of the syscall readlinkat (or readlink) but in kernel-space. Is there an easy way to do this?

直接使用readlinkat对我不起作用，我总是得到EFAULT(我想这是因为我的缓冲区显然在内核内存空间中，而不在用户空间中).

Using readlinkat directly is not working for me, I'm always getting EFAULT (I guess this is because my buffer is obviously in kernel memory space and not in user-space).

推荐答案

首先，您不能直接在内核模块中使用用户空间系统调用(readlinkat()或readlink()).而是需要在内核空间中使用导出的函数/符号.

Firstly, you can't use user space system calls(readlinkat() or readlink()) directly in your kernel module. Rather you need to use exported function / symbol within the kernel space.

接下来，可能要研究结构inode_operations 特定于您正在使用的文件系统.还要查看内部调用vfs_readlink()的 generic_readlink() .

Next, may want to look into the struct inode_operations specific to the file system which you are using. Also look into generic_readlink() which internally call vfs_readlink().

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