如何从内核模块扫描用户空间内存

Question

I want to make a kernel module that scans a user-run process' memory and changes some values. I'm having some trouble figuring out the proper way to interface with user-memory.

I found the copy_to_user and copy_from_user functions from the IBM article User space memory access from the Linux kernel . But they take a user-space pointer. Since I'm not sure where the variable is that I want to change, I would like to scan the memory of the user-process but can't seem to find how.

I was thinking of reading /proc/$(pidof process)/maps for the address since the variable I want to change is in a shared object there. However, I read online that it's not good practice to read files in from a kernel module.

I was also thinking perhaps I could rig the copy_from_user function to copy the entire thing but didn't think that was a good idea since it's really big.

Any suggestions would be appreciated. Thanks.

Answer 1

What are you scanning the memory for and why can't you just do that from userspace? This is easily doable with accessing the mem file in proc.

As for the answer to the question, I'm afraid this is one of the things that if you have a reason to do it, you can easily find out how to do it on your own.