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

Groups > linux.kernel > #1430452

Re: Documenting ptrace access mode checking

Show all headers | View raw

On 06/23/2016 08:56 PM, Eric W. Biederman wrote:
> "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> writes:
>
>> Hi Oleg,
>>
>> On 06/22/2016 11:51 PM, Oleg Nesterov wrote:
>>> On 06/21, Eric W. Biederman wrote:
>>>>
>>>> Adding Oleg just because he seems to do most of the ptrace related
>>>> maintenance these days.
>>>
>>> so I have to admit that I never even tried to actually understand
>>> ptrace_may_access ;)
>>>
>>>> We certainly need something that gives a high level view so people
>>>> reading the man page can know what to expect.   If you get down into the
>>>> weeds we run the danger of people beginning to think they can depend
>>>> upon bugs in the implementation.
>>>
>>> Personally I agree. I think "man ptrace" shouldn't not tell too much
>>> about kernel internals.
>>
>> See my other replies on this topic. Somehow, we need a way of
>> describing the behavior that user-space sees. I think it's
>> inevitable that that means talking about what;s going on
>> "under the hood".
>>
>> Regarding Eric's point that "we run the danger of people beginning
>> to think they can depend upon bugs in the implementation": when it
>> comes to breaking the ABI, the presence or absence of documentation
>> doesn't save us on that point (Linus has a few times made his position
>> wrt to documentation clear).
>
> Which are interesting in this respect as a bug in the implementation
> that is a security issue can and will be changed, even if userspace
> breaks.  Breaking userspace is not desirable but when there is no other
> reasonable choice it will happen.

Yes, good point.

Cheers,

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

Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-21 11:50 +0200
  Re: Documenting ptrace access mode checking ebiederm@xmission.com (Eric W. Biederman) - 2016-06-21 22:10 +0200
    Re: Documenting ptrace access mode checking Kees Cook <keescook@chromium.org> - 2016-06-21 22:40 +0200
      Re: Documenting ptrace access mode checking ebiederm@xmission.com (Eric W. Biederman) - 2016-06-21 23:20 +0200
      Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-22 21:30 +0200
    Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-22 21:30 +0200
      Re: Documenting ptrace access mode checking ebiederm@xmission.com (Eric W. Biederman) - 2016-06-23 21:20 +0200
        Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-24 12:00 +0200
    Re: Documenting ptrace access mode checking Oleg Nesterov <oleg@redhat.com> - 2016-06-23 00:00 +0200
      Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-23 09:10 +0200
        Re: Documenting ptrace access mode checking ebiederm@xmission.com (Eric W. Biederman) - 2016-06-23 21:10 +0200
          Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-24 10:20 +0200
  Re: Documenting ptrace access mode checking Jann Horn <jann@thejh.net> - 2016-06-21 23:30 +0200
    Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-22 21:30 +0200
      Re: Documenting ptrace access mode checking Kees Cook <keescook@chromium.org> - 2016-06-22 23:20 +0200
        Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-23 09:10 +0200
        Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-24 10:50 +0200
          Re: Documenting ptrace access mode checking Casey Schaufler <casey@schaufler-ca.com> - 2016-06-24 17:20 +0200
            Re: Documenting ptrace access mode checking Kees Cook <keescook@chromium.org> - 2016-06-24 22:10 +0200
            Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-25 09:30 +0200
      Re: Documenting ptrace access mode checking Jann Horn <jann@thejh.net> - 2016-06-23 00:50 +0200
        Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-23 09:50 +0200
          Re: Documenting ptrace access mode checking Jann Horn <jann@thejh.net> - 2016-06-24 08:40 +0200
  Re: Documenting ptrace access mode checking Stephen Smalley <sds@tycho.nsa.gov> - 2016-06-23 20:10 +0200
    Re: Documenting ptrace access mode checking "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-06-24 10:40 +0200

csiph-web