lkml.org 
[lkml]   [2016]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: Documenting ptrace access mode checking
"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.

Eric

\
 
 \ /
  Last update: 2016-06-23 21:41    [W:0.052 / U:2.364 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site