How to get username from Linux kernel space

Question

I am doing some Linux module development, restricting me to only kernel-available libraries, and I'd like to get the username of the user who is interacting with my module's username. AKA their "whoami". My module is actually wrapping around syscalls... I can get pid's from current->pid in kernel space. Is there any way to, perhaps, use the pid to track down the user to whom the pid belongs? Or another more simple way?

Thanks

Answer 1

You can use the filp_open function to open /etc/passwd file from the kernel. Next you'll need to use the file_operations to read the file:

struct file * file = filp_open(...);
file->f_op->read(file, ...);

Reading the file contents may be helpful for UID -> username translation.