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From: Mike Rapoport <rppt@linux.ibm.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>, Jann Horn <jannh@google.com>,
	Daniel Colascione <dancol@google.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Pavel Emelyanov <xemul@virtuozzo.com>,
	Lokesh Gidra <lokeshgidra@google.com>,
	Nick Kralevich <nnk@google.com>, Nosh Minwalla <nosh@google.com>,
	Tim Murray <timmurray@google.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Linux API <linux-api@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/7] Add a UFFD_SECURE flag to the userfaultfd API.
Date: Fri, 25 Oct 2019 23:12:43 +0300
Message-ID: <20191025201242.GA8710@linux.ibm.com> (raw)
In-Reply-To: <20191024151054.GJ9902@redhat.com>

Hi,

On Thu, Oct 24, 2019 at 11:10:54AM -0400, Andrea Arcangeli wrote:
> Hello,
> 
> On Thu, Oct 24, 2019 at 12:02:59PM +0300, Mike Rapoport wrote:
> > That's no the reason that UFFD_FEATURE_EVENT_FORK does not show up in
> > Debian code search, CRIU simply is not there. Debian packages CRIU only in
> > experimental and I believe that's not indexed by the code search.
> > 
> > As for the limitations, the races were fixed, I just forgot to update the
> > wiki. As for the supported memory types and COW pages, these only affect
> > efficiency of post-copy, but not the correctness.
> 
> That's what I was hoping for. If the wiki information is stale and
> there are no races it is totally plausible that it's being actively
> used in production so we need to fix the kernel bug. I was just
> checking because I wasn't sure anymore of the status after I read the
> wiki.
> 
> If the CRIU initialization code that issues the uffd syscall runs as
> global root the ABI breaking permission check from Andy sounds the
> simplest for a short term fix, because it will be unnoticed by any
> production usage with CIRU --lazy-pages.
 
In general, criu can run as non-root, but such use of criu has limitations,
so allowing criu --lazy-pages only for root sounds reasonable as a short
term solution.

> Then later we could add a UFFD_FEATURE_EVENT_FORK2 that will not
> require root permission.

Agree.

> Thanks,
> Andrea
> 

-- 
Sincerely yours,
Mike.


  reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-12 19:15 [PATCH 0/7] Harden userfaultfd Daniel Colascione
2019-10-12 19:15 ` [PATCH 1/7] Add a new flags-accepting interface for anonymous inodes Daniel Colascione
2019-10-14  4:26   ` kbuild test robot
2019-10-14 15:38   ` Jann Horn
2019-10-14 18:15     ` Daniel Colascione
2019-10-14 18:30       ` Jann Horn
2019-10-15  8:08   ` Christoph Hellwig
2019-10-12 19:15 ` [PATCH 2/7] Add a concept of a "secure" anonymous file Daniel Colascione
2019-10-14  3:01   ` kbuild test robot
2019-10-15  8:08   ` Christoph Hellwig
2019-10-12 19:15 ` [PATCH 3/7] Add a UFFD_SECURE flag to the userfaultfd API Daniel Colascione
2019-10-12 23:10   ` Andy Lutomirski
2019-10-13  0:51     ` Daniel Colascione
2019-10-13  1:14       ` Andy Lutomirski
2019-10-13  1:38         ` Daniel Colascione
2019-10-14 16:04         ` Jann Horn
2019-10-23 19:09           ` Andrea Arcangeli
2019-10-23 19:21             ` Andy Lutomirski
2019-10-23 21:16               ` Andrea Arcangeli
2019-10-23 21:25                 ` Andy Lutomirski
2019-10-23 22:41                   ` Andrea Arcangeli
2019-10-23 23:01                     ` Andy Lutomirski
2019-10-23 23:27                       ` Andrea Arcangeli
2019-10-23 20:05             ` Daniel Colascione
2019-10-24  0:23               ` Andrea Arcangeli
2019-10-23 20:15             ` Linus Torvalds
2019-10-24  9:02             ` Mike Rapoport
2019-10-24 15:10               ` Andrea Arcangeli
2019-10-25 20:12                 ` Mike Rapoport [this message]
2019-10-22 21:27         ` Daniel Colascione
2019-10-23  4:11         ` Andy Lutomirski
2019-10-23  7:29           ` Cyrill Gorcunov
2019-10-23 12:43             ` Mike Rapoport
2019-10-23 17:13               ` Andy Lutomirski
2019-10-12 19:15 ` [PATCH 4/7] Teach SELinux about a new userfaultfd class Daniel Colascione
2019-10-12 23:08   ` Andy Lutomirski
2019-10-13  0:11     ` Daniel Colascione
2019-10-13  0:46       ` Andy Lutomirski
2019-10-12 19:16 ` [PATCH 5/7] Let userfaultfd opt out of handling kernel-mode faults Daniel Colascione
2019-10-12 19:16 ` [PATCH 6/7] Allow users to require UFFD_SECURE Daniel Colascione
2019-10-12 23:12   ` Andy Lutomirski
2019-10-12 19:16 ` [PATCH 7/7] Add a new sysctl for limiting userfaultfd to user mode faults Daniel Colascione
2019-10-16  0:02 ` [PATCH 0/7] Harden userfaultfd James Morris
2019-11-15 15:09 ` Stephen Smalley

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