Date: Tue, 25 Oct 2011 12:27:52 +0300 From: Mikolaj Golub <trociny@freebsd.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-hackers@freebsd.org, Robert Watson <rwatson@freebsd.org> Subject: Re: "ps -e" without procfs(5) Message-ID: <86aa8p1kvb.fsf@in138.ua3> In-Reply-To: <20111025082451.GO50300@deviant.kiev.zoral.com.ua> (Kostik Belousov's message of "Tue, 25 Oct 2011 11:24:51 %2B0300") References: <86y5wkeuw9.fsf@kopusha.home.net> <20111016171005.GB50300@deviant.kiev.zoral.com.ua> <86aa8qozyx.fsf@kopusha.home.net> <20111025082451.GO50300@deviant.kiev.zoral.com.ua>
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On Tue, 25 Oct 2011 11:24:51 +0300 Kostik Belousov wrote:
KB> On Tue, Oct 25, 2011 at 12:13:10AM +0300, Mikolaj Golub wrote:
>>
>> On Sun, 16 Oct 2011 20:10:05 +0300 Kostik Belousov wrote:
>>
>> KB> In my opinion, the way to implement the feature is to (re)use
>> KB> linprocfs_doargv() and provide another kern.proc sysctl to retrieve the
>> KB> argv and env vectors. Then, ps(1) and procstat(1) can use it, as well as
>> KB> procfs and linprocfs inside the kernel.
>>
>> Thanks! I am testing a patch (without auxv vector so far) and have some
>> questions.
>>
>> Original ps -e returns environment only for user owned processes (the access is
>> restricted by the permissions of /proc/pid/mem file). My kern.proc.env sysctl
>> does not have such a restriction. I suppose I should add it? What function I
>> could use for this?
>>
>> BTW, linprocfs allows to read other user's environment.
KB> linprocfs uses p_cansee() to check the permissions. There are sysctls
KB> security.bsd.see_other_{ug}ids that control the behaviour.
KB> I believe that the new sysctl shall use the same check.
This looks reasonable for me. But I just wanted to be sure that this would be
ok for other people, as my patch changes the system behavior: currently with
security.bsd.see_other_{ug}ids and procfs (not linprocfs) mounted a user can
see other users args but not env; after the change a user will see both args
and env (until security.bsd.see_other_{ug}ids is off).
>>
>> KB> While you are at the code, it would be useful to also export the auxv vector,
>> KB> which is immediately before env.
>>
>> It looks I can find the location of auxv but what about the size? Or do you
>> propose to extend struct ps_strings to store location and size of auxv? I
>> could do this way...
KB> No, extending ps_strings is not needed and it is too radical change.
KB> The auxv vector must end by the AT_NULL aux entry. You can also artificially
KB> limit the amount of read aux vectors to, say, 256, which is much more then
KB> it is currently defined.
Thanks.
--
Mikolaj Golub
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