From: Tycho Andersen <tycho@tycho.ws>
To: Matthew Wilcox <willy@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
Kees Cook <keescook@chromium.org>,
Peter Zijlstra <peterz@infradead.org>,
Igor Stoppa <igor.stoppa@gmail.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
Dave Chinner <david@fromorbit.com>,
James Morris <jmorris@namei.org>,
Michal Hocko <mhocko@kernel.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
linux-integrity <linux-integrity@vger.kernel.org>,
linux-security-module <linux-security-module@vger.kernel.org>,
Igor Stoppa <igor.stoppa@huawei.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Jonathan Corbet <corbet@lwn.net>,
Laura Abbott <labbott@redhat.com>,
Randy Dunlap <rdunlap@infradead.org>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 10/17] prmem: documentation
Date: Tue, 30 Oct 2018 12:28:41 -0600 [thread overview]
Message-ID: <20181030182841.GE7343@cisco> (raw)
In-Reply-To: <20181030175814.GB10491@bombadil.infradead.org>
On Tue, Oct 30, 2018 at 10:58:14AM -0700, Matthew Wilcox wrote:
> On Tue, Oct 30, 2018 at 10:06:51AM -0700, Andy Lutomirski wrote:
> > > On Oct 30, 2018, at 9:37 AM, Kees Cook <keescook@chromium.org> wrote:
> > I support the addition of a rare-write mechanism to the upstream kernel.
> > And I think that there is only one sane way to implement it: using an
> > mm_struct. That mm_struct, just like any sane mm_struct, should only
> > differ from init_mm in that it has extra mappings in the *user* region.
>
> I'd like to understand this approach a little better. In a syscall path,
> we run with the user task's mm. What you're proposing is that when we
> want to modify rare data, we switch to rare_mm which contains a
> writable mapping to all the kernel data which is rare-write.
>
> So the API might look something like this:
>
> void *p = rare_alloc(...); /* writable pointer */
> p->a = x;
> q = rare_protect(p); /* read-only pointer */
>
> To subsequently modify q,
>
> p = rare_modify(q);
> q->a = y;
Do you mean
p->a = y;
here? I assume the intent is that q isn't writable ever, but that's
the one we have in the structure at rest.
Tycho
> rare_protect(p);
>
> Under the covers, rare_modify() would switch to the rare_mm and return
> (void *)((unsigned long)q + ARCH_RARE_OFFSET). All of the rare data
> would then be modifiable, although you don't have any other pointers
> to it. rare_protect() would switch back to the previous mm and return
> (p - ARCH_RARE_OFFSET).
>
> Does this satisfy Igor's requirements? We wouldn't be able to
> copy_to/from_user() while rare_mm was active. I think that's a feature
> though! It certainly satisfies my interests (kernel code be able to
> mark things as dynamically-allocated-and-read-only-after-initialisation)
next prev parent reply other threads:[~2018-10-30 18:28 UTC|newest]
Thread overview: 140+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-23 21:34 [RFC v1 PATCH 00/17] prmem: protected memory Igor Stoppa
2018-10-23 21:34 ` [PATCH 01/17] prmem: linker section for static write rare Igor Stoppa
2018-10-23 21:34 ` [PATCH 02/17] prmem: write rare for static allocation Igor Stoppa
2018-10-25 0:24 ` Dave Hansen
2018-10-29 18:03 ` Igor Stoppa
2018-10-26 9:41 ` Peter Zijlstra
2018-10-29 20:01 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 03/17] prmem: vmalloc support for dynamic allocation Igor Stoppa
2018-10-25 0:26 ` Dave Hansen
2018-10-29 18:07 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 04/17] prmem: " Igor Stoppa
2018-10-23 21:34 ` [PATCH 05/17] prmem: shorthands for write rare on common types Igor Stoppa
2018-10-25 0:28 ` Dave Hansen
2018-10-29 18:12 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 06/17] prmem: test cases for memory protection Igor Stoppa
2018-10-24 3:27 ` Randy Dunlap
2018-10-24 14:24 ` Igor Stoppa
2018-10-25 16:43 ` Dave Hansen
2018-10-29 18:16 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 07/17] prmem: lkdtm tests " Igor Stoppa
2018-10-23 21:34 ` [PATCH 08/17] prmem: struct page: track vmap_area Igor Stoppa
2018-10-24 3:12 ` Matthew Wilcox
2018-10-24 23:01 ` Igor Stoppa
2018-10-25 2:13 ` Matthew Wilcox
2018-10-29 18:21 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 09/17] prmem: hardened usercopy Igor Stoppa
2018-10-29 11:45 ` Chris von Recklinghausen
2018-10-29 18:24 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 10/17] prmem: documentation Igor Stoppa
2018-10-24 3:48 ` Randy Dunlap
2018-10-24 14:30 ` Igor Stoppa
2018-10-24 23:04 ` Mike Rapoport
2018-10-29 19:05 ` Igor Stoppa
2018-10-26 9:26 ` Peter Zijlstra
2018-10-26 10:20 ` Matthew Wilcox
2018-10-29 19:28 ` Igor Stoppa
2018-10-26 10:46 ` Kees Cook
2018-10-28 18:31 ` Peter Zijlstra
2018-10-29 21:04 ` Igor Stoppa
2018-10-30 15:26 ` Peter Zijlstra
2018-10-30 16:37 ` Kees Cook
2018-10-30 17:06 ` Andy Lutomirski
2018-10-30 17:58 ` Matthew Wilcox
2018-10-30 18:03 ` Dave Hansen
2018-10-31 9:18 ` Peter Zijlstra
2018-10-30 18:28 ` Tycho Andersen [this message]
2018-10-30 19:20 ` Matthew Wilcox
2018-10-30 20:43 ` Igor Stoppa
2018-10-30 21:02 ` Andy Lutomirski
2018-10-30 21:07 ` Kees Cook
2018-10-30 21:25 ` Igor Stoppa
2018-10-30 22:15 ` Igor Stoppa
2018-10-31 10:11 ` Peter Zijlstra
2018-10-31 20:38 ` Andy Lutomirski
2018-10-31 20:53 ` Andy Lutomirski
2018-10-31 9:45 ` Peter Zijlstra
2018-10-30 21:35 ` Matthew Wilcox
2018-10-30 21:49 ` Igor Stoppa
2018-10-31 4:41 ` Andy Lutomirski
2018-10-31 9:08 ` Igor Stoppa
2018-10-31 19:38 ` Igor Stoppa
2018-10-31 10:02 ` Peter Zijlstra
2018-10-31 20:36 ` Andy Lutomirski
2018-10-31 21:00 ` Peter Zijlstra
2018-10-31 22:57 ` Andy Lutomirski
2018-10-31 23:10 ` Igor Stoppa
2018-10-31 23:19 ` Andy Lutomirski
2018-10-31 23:26 ` Igor Stoppa
2018-11-01 8:21 ` Thomas Gleixner
2018-11-01 15:58 ` Igor Stoppa
2018-11-01 17:08 ` Peter Zijlstra
2018-10-30 18:51 ` Andy Lutomirski
2018-10-30 19:14 ` Kees Cook
2018-10-30 21:25 ` Matthew Wilcox
2018-10-30 21:55 ` Igor Stoppa
2018-10-30 22:08 ` Matthew Wilcox
2018-10-31 9:29 ` Peter Zijlstra
2018-10-30 23:18 ` Nadav Amit
2018-10-31 9:08 ` Peter Zijlstra
2018-11-01 16:31 ` Nadav Amit
2018-11-02 21:11 ` Nadav Amit
2018-10-31 9:36 ` Peter Zijlstra
2018-10-31 11:33 ` Matthew Wilcox
2018-11-13 14:25 ` Igor Stoppa
2018-11-13 17:16 ` Andy Lutomirski
2018-11-13 17:43 ` Nadav Amit
2018-11-13 17:47 ` Andy Lutomirski
2018-11-13 18:06 ` Nadav Amit
2018-11-13 18:31 ` Igor Stoppa
2018-11-13 18:33 ` Igor Stoppa
2018-11-13 18:36 ` Andy Lutomirski
2018-11-13 19:03 ` Igor Stoppa
2018-11-21 16:34 ` Igor Stoppa
2018-11-21 17:36 ` Nadav Amit
2018-11-21 18:01 ` Igor Stoppa
2018-11-21 18:15 ` Andy Lutomirski
2018-11-22 19:27 ` Igor Stoppa
2018-11-22 20:04 ` Matthew Wilcox
2018-11-22 20:53 ` Andy Lutomirski
2018-12-04 12:34 ` Igor Stoppa
2018-11-13 18:48 ` Andy Lutomirski
2018-11-13 19:35 ` Igor Stoppa
2018-11-13 18:26 ` Igor Stoppa
2018-11-13 18:35 ` Andy Lutomirski
2018-11-13 19:01 ` Igor Stoppa
2018-10-31 9:27 ` Igor Stoppa
2018-10-26 11:09 ` Markus Heiser
2018-10-29 19:35 ` Igor Stoppa
2018-10-26 15:05 ` Jonathan Corbet
2018-10-29 19:38 ` Igor Stoppa
2018-10-29 20:35 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 11/17] prmem: llist: use designated initializer Igor Stoppa
2018-10-23 21:34 ` [PATCH 12/17] prmem: linked list: set alignment Igor Stoppa
2018-10-26 9:31 ` Peter Zijlstra
2018-10-23 21:35 ` [PATCH 13/17] prmem: linked list: disable layout randomization Igor Stoppa
2018-10-24 13:43 ` Alexey Dobriyan
2018-10-29 19:40 ` Igor Stoppa
2018-10-26 9:32 ` Peter Zijlstra
2018-10-26 10:17 ` Matthew Wilcox
2018-10-30 15:39 ` Peter Zijlstra
2018-10-23 21:35 ` [PATCH 14/17] prmem: llist, hlist, both plain and rcu Igor Stoppa
2018-10-24 11:37 ` Mathieu Desnoyers
2018-10-24 14:03 ` Igor Stoppa
2018-10-24 14:56 ` Tycho Andersen
2018-10-24 22:52 ` Igor Stoppa
2018-10-25 8:11 ` Tycho Andersen
2018-10-28 9:52 ` Steven Rostedt
2018-10-29 19:43 ` Igor Stoppa
2018-10-26 9:38 ` Peter Zijlstra
2018-10-23 21:35 ` [PATCH 15/17] prmem: test cases for prlist and prhlist Igor Stoppa
2018-10-23 21:35 ` [PATCH 16/17] prmem: pratomic-long Igor Stoppa
2018-10-25 0:13 ` Peter Zijlstra
2018-10-29 21:17 ` Igor Stoppa
2018-10-30 15:58 ` Peter Zijlstra
2018-10-30 16:28 ` Will Deacon
2018-10-31 9:10 ` Peter Zijlstra
2018-11-01 3:28 ` Kees Cook
2018-10-23 21:35 ` [PATCH 17/17] prmem: ima: turn the measurements list write rare Igor Stoppa
2018-10-24 23:03 ` [RFC v1 PATCH 00/17] prmem: protected memory Dave Chinner
2018-10-29 19:47 ` Igor Stoppa
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