From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
Borislav Petkov <bpetkov@suse.de>,
Greg KH <gregkh@linuxfoundation.org>,
Kees Cook <keescook@google.com>, Hugh Dickins <hughd@google.com>,
Brian Gerst <brgerst@gmail.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>,
David Laight <David.Laight@aculab.com>,
Eduardo Valentin <eduval@amazon.com>,
"Liguori, Anthony" <aliguori@amazon.com>,
Will Deacon <will.deacon@arm.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH v2 11/17] selftests/x86/ldt_gdt: Prepare for access bit forced
Date: Thu, 14 Dec 2017 13:48:50 -0800 [thread overview]
Message-ID: <CA+55aFxmwpkDNT0YcaiG-BQ5SUT6h6YkevVfNkU_eY-F2E-h7Q@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFyNN4Lhf4RhL95oeGvfng=H4wKSA3-MwzMo=KpBocQ7bA@mail.gmail.com>
On Thu, Dec 14, 2017 at 1:44 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> So it clearly needs to have the PAGE_USER bit clear (to avoid users
> accessing it directly), and it needs to be marked somehow for
> get_user_pages() to refuse it too, and access_ok() needs to fail it so
> that we can't do get_user/put_user on it.
Actually, just clearing PAGE_USER should make gup avoid it automatically.
So really the only other thing it needs is to have access_ok() avoid
it so that the kernel can't be fooled into accessing it for the user.
That does probably mean having to put it at the top of the user
address space and playing games with user_addr_max(). Which is not
wonderful, but certainly not rocket surgery either.
Linus
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next prev parent reply other threads:[~2017-12-14 21:48 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-14 11:27 [PATCH v2 00/17] x86/ldt: Use a VMA based read only mapping Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 01/17] mm/gup: Fixup p*_access_permitted() Peter Zijlstra
2017-12-14 12:41 ` Peter Zijlstra
2017-12-14 14:37 ` Peter Zijlstra
2017-12-14 20:44 ` Dave Hansen
2017-12-14 20:54 ` Peter Zijlstra
2017-12-14 21:18 ` Peter Zijlstra
2017-12-15 5:04 ` Dave Hansen
2017-12-15 6:09 ` Linus Torvalds
2017-12-15 7:51 ` Peter Zijlstra
2017-12-16 0:20 ` Linus Torvalds
2017-12-16 0:29 ` Dan Williams
2017-12-16 1:10 ` Linus Torvalds
2017-12-16 1:25 ` Dave Hansen
2017-12-16 2:28 ` Linus Torvalds
2017-12-16 2:48 ` Al Viro
2017-12-16 2:52 ` Linus Torvalds
2017-12-16 3:00 ` Linus Torvalds
2017-12-16 3:21 ` Dave Hansen
2017-12-16 1:29 ` Dan Williams
2017-12-16 0:31 ` Al Viro
2017-12-16 1:05 ` Linus Torvalds
2017-12-15 8:00 ` Peter Zijlstra
2017-12-15 10:25 ` Peter Zijlstra
2017-12-15 11:38 ` Peter Zijlstra
2017-12-15 16:38 ` Dan Williams
2017-12-18 11:54 ` Peter Zijlstra
2017-12-18 18:42 ` Dan Williams
2017-12-15 14:04 ` Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 02/17] mm: Exempt special mappings from mlock(), mprotect() and madvise() Peter Zijlstra
2017-12-14 16:19 ` Andy Lutomirski
2017-12-14 17:36 ` Peter Zijlstra
2018-01-02 16:44 ` Dmitry Safonov
2017-12-14 11:27 ` [PATCH v2 03/17] arch: Allow arch_dup_mmap() to fail Peter Zijlstra
2017-12-14 16:22 ` Andy Lutomirski
2017-12-14 11:27 ` [PATCH v2 04/17] x86/ldt: Rework locking Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 05/17] x86/ldt: Prevent ldt inheritance on exec Peter Zijlstra
2017-12-14 16:32 ` Andy Lutomirski
2017-12-14 11:27 ` [PATCH v2 06/17] x86/ldt: Do not install LDT for kernel threads Peter Zijlstra
2017-12-14 19:43 ` Peter Zijlstra
2017-12-14 21:27 ` Andy Lutomirski
2017-12-14 11:27 ` [PATCH v2 07/17] mm/softdirty: Move VM_SOFTDIRTY into high bits Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 08/17] mm/x86: Allow special mappings with user access cleared Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 09/17] mm: Provide vm_special_mapping::close Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 10/17] selftest/x86: Implement additional LDT selftests Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 11/17] selftests/x86/ldt_gdt: Prepare for access bit forced Peter Zijlstra
2017-12-14 16:20 ` Andy Lutomirski
2017-12-14 19:43 ` Linus Torvalds
2017-12-14 21:22 ` Andy Lutomirski
2017-12-14 21:44 ` Linus Torvalds
2017-12-14 21:48 ` Linus Torvalds [this message]
2017-12-14 22:02 ` Peter Zijlstra
2017-12-14 22:14 ` Linus Torvalds
2017-12-14 22:24 ` Peter Zijlstra
2017-12-14 22:52 ` Linus Torvalds
2017-12-14 22:11 ` Andy Lutomirski
2017-12-14 22:15 ` Linus Torvalds
2017-12-14 22:30 ` Andy Lutomirski
2017-12-14 22:23 ` Thomas Gleixner
2017-12-14 22:50 ` Linus Torvalds
2017-12-14 11:27 ` [PATCH v2 12/17] mm: Make populate_vma_page_range() available Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 13/17] x86/mm: Force LDT desc accessed bit Peter Zijlstra
2017-12-14 16:21 ` Andy Lutomirski
2017-12-14 11:27 ` [PATCH v2 14/17] x86/ldt: Reshuffle code Peter Zijlstra
2017-12-14 16:23 ` Andy Lutomirski
2017-12-14 16:31 ` Thomas Gleixner
2017-12-14 16:32 ` Thomas Gleixner
2017-12-14 16:34 ` Andy Lutomirski
2017-12-14 17:47 ` Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 15/17] x86/ldt: Prepare for VMA mapping Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 16/17] x86/ldt: Add VMA management code Peter Zijlstra
2017-12-14 11:27 ` [PATCH v2 17/17] x86/ldt: Make it read only VMA mapped Peter Zijlstra
2017-12-14 12:03 ` [PATCH v2 00/17] x86/ldt: Use a VMA based read only mapping Thomas Gleixner
2017-12-14 12:08 ` Peter Zijlstra
2017-12-14 16:35 ` Andy Lutomirski
2017-12-14 17:50 ` Peter Zijlstra
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