Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1412635

Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls

Show all headers | View raw

On 06/01/2016 07:17 PM, Dave Hansen wrote:
> On 06/01/2016 05:11 PM, Michael Kerrisk (man-pages) wrote:
>>>>>>
>>>>>> If I read this right, it doesn't actually remove any pkey restrictions
>>>>>> that may have been applied while the key was allocated.  So there could be
>>>>>> pages with that key assigned that might do surprising things if the key is
>>>>>> reallocated for another use later, right?  Is that how the API is intended
>>>>>> to work?
>>>>
>>>> Yeah, that's how it works.
>>>>
>>>> It's not ideal.  It would be _best_ if we during mm_pkey_free(), we
>>>> ensured that no VMAs under that mm have that vma_pkey() set.  But, that
>>>> search would be potentially expensive (a walk over all VMAs), or would
>>>> force us to keep a data structure with a count of all the VMAs with a
>>>> given key.
>>>>
>>>> I should probably discuss this behavior in the manpages and address it
>> s/probably//
>>
>> And, did I miss it. Was there an updated man-pages patch in the latest
>> series? I did not notice it.
> 
> There have been to changes to the patches that warranted updating the
> manpages until now.  I'll send the update immediately.

Do those updated pages include discussion of the point noted above?
I could not see it mentioned there.

Just by the way, the above behavior seems to offer possibilities
for users to shoot themselves in the foot, in a way that has security
implications. (Or do I misunderstand?)

Thanks,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/8] System Calls for Memory Protection Keys Dave Hansen <dave@sr71.net> - 2016-05-31 17:30 +0200
  [PATCH 5/8] x86, pkeys: allocation/free syscalls Dave Hansen <dave@sr71.net> - 2016-05-31 17:30 +0200
    Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls Jonathan Corbet <corbet@lwn.net> - 2016-06-01 20:40 +0200
      Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls Dave Hansen <dave@sr71.net> - 2016-06-01 21:40 +0200
        Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-02 02:20 +0200
          Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls Dave Hansen <dave@sr71.net> - 2016-06-02 02:20 +0200
            Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-03 02:30 +0200
              Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls Dave Hansen <dave@sr71.net> - 2016-06-03 19:30 +0200
                Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-03 21:50 +0200
    Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls Arnd Bergmann <arnd@arndb.de> - 2016-06-02 13:50 +0200
      Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls Dave Hansen <dave@sr71.net> - 2016-06-02 23:20 +0200
  [PATCH 4/8] x86: wire up mprotect_key() system call Dave Hansen <dave@sr71.net> - 2016-05-31 17:30 +0200
  [PATCH 3/8] x86, pkeys: make mprotect_key() mask off additional vm_flags Dave Hansen <dave@sr71.net> - 2016-05-31 17:30 +0200
  [PATCH 7/8] pkeys: add details of system call use to Documentation/ Dave Hansen <dave@sr71.net> - 2016-05-31 17:30 +0200
    Re: [PATCH 7/8] pkeys: add details of system call use to  Documentation/ Jonathan Corbet <corbet@lwn.net> - 2016-06-01 18:50 +0200
      Re: [PATCH 7/8] pkeys: add details of system call use to  Documentation/ Dave Hansen <dave@sr71.net> - 2016-06-01 18:50 +0200
        Re: [PATCH 7/8] pkeys: add details of system call use to  Documentation/ Jonathan Corbet <corbet@lwn.net> - 2016-06-01 19:00 +0200
          Re: [PATCH 7/8] pkeys: add details of system call use to  Documentation/ Dave Hansen <dave@sr71.net> - 2016-06-01 19:20 +0200
  [PATCH 6/8] x86, pkeys: add pkey set/get syscalls Dave Hansen <dave@sr71.net> - 2016-05-31 17:30 +0200
  [PATCH 2/8] mm: implement new pkey_mprotect() system call Dave Hansen <dave@sr71.net> - 2016-05-31 17:40 +0200
  [PATCH 1/8] x86, pkeys: add fault handling for PF_PK page fault bit Dave Hansen <dave@sr71.net> - 2016-05-31 17:40 +0200

csiph-web