Re: [PATCH v6] Added PR_SET_PROCTITLE_AREA option for prctl()

[Ingo Molnar]

* Bryan Donlan <bdonlan@xxxxxxxxx> wrote:

> On Tue, Dec 8, 2009 at 12:38 AM, Ingo Molnar <mingo@xxxxxxx> wrote:
> >
> > * KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
> >
> >> > The feature looks useful, but the choice of a prctl as an API is strange
> >> > - it limits us to the current task only - while the ability to set
> >> > arguments for another task looks a more generic (and potentially more
> >> > useful) solution.
> >>
> >> No. It's impossible.
> >> /proc/{pid}/cmdline read user process's memory. iow, this prctl() don't
> >> receive string, it receive virtual address itself. [...]
> >
> > it's not 'impossible' at all, you yourself mention ptrace:
> 
> If another process is going to use ptrace to inject the cmdline string 
> into the victim's address space, it can also temporarily hijack a 
> thread to run prctl() on its behalf...

That's exactly the point i made. There's no reason not to offer the API 
i suggested as long as permissions are checked (as usual) - because 
ptrace already allows this (and more).

Thanks,

	Ingo
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