Re: [patch 3/3] [PATCH] prctl: Add PR_SET_MM codes to set up mm_struct entires v3

KOSAKI Motohiro
2011-12-12T21:49:47Z

Hi

> When we restore a task we need to set up text, data and data
> heap sizes from userspace to the values a task had at
> checkpoint time. This patch adds auxilary prctl codes for that.
>
> While most of them have a statistical nature (their values
> are involved into calculation of /proc/<pid>/statm output)
> the start_brk and brk values are used to compute an allowed
> size of program data segment expansion. Which means an arbitrary
> changes of this values might be dangerous operation. So to restrict
> access the following requirements applied to prctl calls:
>
> - The process has to have CAP_SYS_ADMIN capability granted.

This is very dangerous feature and useless from regular admins.
Moreover, CAP_SYS_ADMIN has a pretty overweight meanings and
we can't disable it on practical. So, I have a question. Why
don't you make new capability for checkpoint?