Messages in this thread | | | Date | Mon, 12 Dec 2011 17:24:56 -0500 | From | KOSAKI Motohiro <> | Subject | Re: [patch 3/3] [PATCH] prctl: Add PR_SET_MM codes to set up mm_struct entires v3 |
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(12/12/11 4:58 PM), Cyrill Gorcunov wrote: > On Mon, Dec 12, 2011 at 04:49:38PM -0500, KOSAKI Motohiro wrote: >> 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. > > Except brk() call I don't see where it might be extremelly > dangerous at moment but indeed it might become very dangerous > once code grows. Still if evil minded person got CAP_SYS_ADMIN > these prctls are least thing one should carry about.
I'm sorry, I misunderstood your code. Your code only allow to change their own process attribute. So, it's enough harmless. Please ignore my last mail.
>> 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? >> > > It's not a problem to introduce CAP_CHECKPOINT_RESTORE, but > would it be accepted? I mean, are we fine with new capability > introduction? If yes -- I'll add new one and rebase the patch.
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