linux-kernel - Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map

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Date:	Fri, 16 Sep 2011 22:07:32 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Vasiliy Kulikov <segoon@...nwall.com>
Cc:	Pavel Machek <pavel@....cz>, Andrew Morton <akpm00@...il.com>,
	linux-kernel@...r.kernel.org, containers@...ts.osdl.org,
	linux-fsdevel@...r.kernel.org,
	Kirill Shutemov <kirill@...temov.name>,
	Pavel Emelyanov <xemul@...allels.com>,
	James Bottomley <jbottomley@...allels.com>,
	Nathan Lynch <ntl@...ox.com>, Zan Lynx <zlynx@....org>,
	Daniel Lezcano <dlezcano@...ibm.com>,
	Tejun Heo <tj@...nel.org>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Al Viro <viro@...IV.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/
 directory v12

On Fri, Sep 16, 2011 at 09:56:18PM +0400, Vasiliy Kulikov wrote:
...
> > 
> > v14: (by Vasiliy Kulikov)
> >  - for security reason map_files/ entries are allowed for
> >    readers with CAP_SYS_ADMIN credentials granted only
> 
> This changelog is currently much longer than the commit description text ;)

Yes, I know ;) I would like to keep it (to appreciate everyone who spent time
in review and feedback).
...
> 
> > +
> > + inode = dentry->d_inode;
> > + task = get_proc_task(inode);
> > + if (!task)
> > +         goto out_notask;
> > +
> > + if (!ptrace_may_access(task, PTRACE_MODE_READ))
> > +         goto out;
> 
> While this is not needed with capable() check, it's OK to keep it for
> the future more finegranted access checks.

yeah

> 
> BTW, not a big deal, but probably you should return -EACCES on
> !capable() as file presence is not an issue in this case.
> 
>     if (!ptrace_may_access(task, PTRACE_MODE_READ))
>         goto out_notask;
> 
>     status = -EACCES;
>     if (!capable(CAP_SYS_ADMIN))
>         goto out_notask;
> 
>     status = 0;
> 
> 

That's not a proble to fix it actually. So can I fix it and
put some tage here (Reviewed or something?).

	Cyrill
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