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Groups > linux.kernel > #1550248

Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR

From Andy Lutomirski <luto@amacapital.net>
Newsgroups linux.kernel
Subject Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR
Date 2017-01-03 23:10 +0100
Message-ID <sVFrk-48v-31@gated-at.bofh.it> (permalink)
References <sSPdv-45l-3@gated-at.bofh.it> <sVxk6-6WU-17@gated-at.bofh.it> <sVCa7-1SP-63@gated-at.bofh.it> <sVFrk-48v-33@gated-at.bofh.it>
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On Tue, Jan 3, 2017 at 2:07 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Tuesday, January 3, 2017 10:29:33 AM CET Andy Lutomirski wrote:
>>
>> Hmm.  What if we approached this a bit differently?  We could add a
>> single new personality bit ADDR_LIMIT_EXPLICIT.  Setting this bit
>> cause PER_LINUX32_3GB etc to be automatically cleared.
>
> Both the ADDR_LIMIT_32BIT and ADDR_LIMIT_3GB flags I guess?

Yes.

>
>> When
>> ADDR_LIMIT_EXPLICIT is in effect, prctl can set a 64-bit numeric
>> limit.  If ADDR_LIMIT_EXPLICIT is cleared, the prctl value stops being
>> settable and reading it via prctl returns whatever is implied by the
>> other personality bits.
>
> I don't see anything wrong with it, but I'm a bit confused now
> what this would be good for, compared to using just prctl.
>
> Is this about setuid clearing the personality but not the prctl,
> or something else?

It's to avid ambiguity as to what happens if you set ADDR_LIMIT_32BIT
and use the prctl.  ISTM it would be nice for the semantics to be
fully defined in all cases.

--Andy

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[PATCHv2 00/29] 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:00 +0100
  [PATCHv2 17/29] x86/asm: remove __VIRTUAL_MASK_SHIFT==47 assert "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:00 +0100
  [PATCHv2 03/29] asm-generic: introduce __ARCH_USE_5LEVEL_HACK "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:00 +0100
  [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:00 +0100
    Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2016-12-27 03:20 +0100
      Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-27 03:40 +0100
        Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2016-12-27 04:30 +0100
          Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-01-02 10:20 +0100
        Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Carlos O'Donell <carlos@redhat.com> - 2016-12-29 04:00 +0100
          Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2016-12-31 03:10 +0100
            Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-01-02 09:40 +0100
              Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "H.J. Lu" <hjl.tools@gmail.com> - 2017-01-13 21:20 +0100
    Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Arnd Bergmann <arnd@arndb.de> - 2017-01-02 09:50 +0100
      Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-01-03 07:10 +0100
        Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Arnd Bergmann <arnd@arndb.de> - 2017-01-03 14:30 +0100
          Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-01-03 19:40 +0100
            Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-01-03 23:10 +0100
              Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Arnd Bergmann <arnd@arndb.de> - 2017-01-04 15:00 +0100
            Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Arnd Bergmann <arnd@arndb.de> - 2017-01-03 23:20 +0100
        Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-01-03 17:10 +0100
          Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-01-03 19:30 +0100
            Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-01-04 15:30 +0100
              Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-01-05 19:20 +0100
    Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-01-05 20:20 +0100
      Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-01-05 20:40 +0100
        Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-01-05 20:40 +0100
          Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-01-05 21:20 +0100
            Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-01-05 21:50 +0100
              Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-01-05 22:30 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-01-06 00:20 +0100
              Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-01-11 15:30 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-01-11 19:10 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-01-11 19:40 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-01-11 20:00 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-01-11 20:30 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-11 20:40 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Andi Kleen <ak@linux.intel.com> - 2017-01-11 22:50 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-01-11 20:40 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-11 20:40 +0100
                Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-01-11 19:30 +0100
          Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-01-05 21:20 +0100
  [PATCHv2 19/29] x86/paravirt: make paravirt code support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:00 +0100
  [PATCHv2 27/29] x86/mm: add support for 5-level paging for KASLR "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:00 +0100
  [PATCHv2 12/29] x86/mm: add support of p4d_t in vmalloc_fault() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:00 +0100
  [PATCHv2 18/29] x86/mm: define virtual memory map for 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:00 +0100
  [PATCHv2 04/29] arch, mm: convert all architectures to use 5level-fixup.h "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:10 +0100
  [PATCHv2 02/29] asm-generic: introduce 5level-fixup.h "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:10 +0100
  [PATCHv2 14/29] x86/kexec: support p4d_t "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:10 +0100
  [PATCHv2 08/29] x86: basic changes into headers for 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:10 +0100
  [PATCHv2 05/29] asm-generic: introduce <asm-generic/pgtable-nop4d.h> "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:10 +0100
  [PATCHv2 15/29] x86: convert the rest of the code to support p4d_t "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-27 03:10 +0100
  Re: [PATCHv2 00/29] 5-level paging "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-01-05 18:00 +0100

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