linux-kernel - Re: [PATCH] supress uid comparison test if core output files are pipes

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Date:	Wed, 24 Feb 2010 18:13:32 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Neil Horman <nhorman@...driver.com>
Cc:	oleg@...hat.com, viro@...iv.linux.org.uk,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] supress uid comparison test if core output files are
 pipes

On Wed, 24 Feb 2010 20:32:10 -0500 Neil Horman <nhorman@...driver.com> wrote:

> > > diff --git a/fs/exec.c b/fs/exec.c
> > > index 6303d18..6af2214 100644
> > > --- a/fs/exec.c
> > > +++ b/fs/exec.c
> > > @@ -1987,8 +1987,9 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
> > >  	/*
> > >  	 * Dont allow local users get cute and trick others to coredump
> > >  	 * into their pre-created files:
> > > +	 * Note, this is not relevant for pipes
> > >  	 */
> > > -	if (inode->i_uid != current_fsuid())
> > > +	if (!ispipe && (inode->i_uid != current_fsuid()))
> > >  		goto close_fail;
> > >  	if (!cprm.file->f_op)
> > >  		goto close_fail;
> > 
> > hm, this actually appears to fix a regression, added by:
> > 
> In a sense yes.  Previously though, Ingos check was both useless for pipes
> (since you can't have a user create a pipe that will map to what the coredump
> path creates anyway, making this check useless), but it worked anyway, since the
> crashing process created the pipe, so the uid check always matched.  With the
> refactoring andi and I did, thats no longer true, so the check could fail.  This
> patch just fixes it up by recongnizing that the check isn't needed at all for
> pipes

Which refactoring?  Please identify precisely the patch which this patch fixes up?
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