"ps -e" without procfs(5)
Mikolaj Golub
trociny at freebsd.org
Sat Oct 29 10:32:47 UTC 2011
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.
>>
>> 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.
What do you think about the attached patch? This is a kernel
part. COMPAT_FREEBSD32 has not been tested after the last update (just checked
that it compiles): it looks I will not have access to amd64 box for testing
during the weekend. I will test it after the weekend.
Both kernel and userland parts are available here:
http://people.freebsd.org/~trociny/env.sys.patch
http://people.freebsd.org/~trociny/env.user.patch
Currently there is an issue with procstat -x: if one tried to run it on 64 bit
for a 32 bit process it would not detect this so would output a garbage. Could
somebody recommend a way how to get this info about a process from userlend?
--
Mikolaj Golub
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