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From: Al Viro <viro@ZenIV.linux.org.uk>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Jeff Layton" <jlayton@kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	"J. Bruce Fields" <bfields@fieldses.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Daniel P . Berrangé" <berrange@redhat.com>,
	"Kate Stewart" <kstewart@linuxfoundation.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Philippe Ombredanne" <pombredanne@nexb.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v2] locks: change POSIX lock ownership on execve when files_struct is displaced
Date: Thu, 22 Mar 2018 11:14:25 +0000
Message-ID: <20180322111424.GE30522@ZenIV.linux.org.uk> (raw)
In-Reply-To: <87bmfgvg8w.fsf@xmission.com>

On Thu, Mar 22, 2018 at 12:19:59AM -0500, Eric W. Biederman wrote:
> Jeff Layton <jlayton@kernel.org> writes:
> 
> > From: Jeff Layton <jlayton@redhat.com>
> >
> > POSIX mandates that open fds and their associated file locks should be
> > preserved across an execve. This works, unless the process is
> > multithreaded at the time that execve is called.
> 
> Would this perhaps work better if we moved unshare_files to after or
> inside of de_thread.  That would remove any cases where fd->count is > 1
> simply because you are multi-threaded.  It would only leave the strange
> cases where files struct is shared between different processes.

So during the probing of binfmts, etc. the descriptor table would be modifiable
by other threads?

flush_old_exec() is far too late in execve()...

  parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-17 14:25 [PATCH] " Jeff Layton
2018-03-17 15:05 ` Al Viro
2018-03-17 15:43   ` Jeff Layton
2018-03-17 15:52     ` Al Viro
2018-03-17 19:28       ` Jeff Layton
2018-03-17 16:58 ` [PATCH v2] " Jeff Layton
     [not found]   ` <87bmfgvg8w.fsf@xmission.com>
2018-03-22 11:14     ` Al Viro [this message]
     [not found]     ` <871sgcvfh7.fsf@xmission.com>
2018-03-22 10:57       ` Jeff Layton
2018-04-02 12:56       ` Jeff Layton
2018-04-03 17:22         ` Eric W. Biederman

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