[lxc-users] Getting GID, UID of container process from container host

[Shailendra Rana]

Hi,

I do not see NSpid field in status file.

# cat /proc/14307/status | grep -i ns

I am running a docker container.
docker -v
Docker version 1.12.1, build 23cf638

Thanks,
Shailendra

On 31 January 2018 at 02:09, Stéphane Graber <stgraber at ubuntu.com> wrote:
> On Tue, Jan 30, 2018 at 10:19:12PM +0530, Shailendra Rana wrote:
>> Hi,
>>
>> Is there a way we can get the PID/GID/UID of a container process using
>> the host  PID/GID/UID of that container process ? Basically mapping of
>> host PID/GID/UID to container PID/GID/UID.
>>
>> Thanks,
>> Shailendra
>
> It's technically doable, yes, but not particularly enjoyable :)
>
> stgraber at castiana:~$ ls -lh /proc/ | grep 8261
> dr-xr-xr-x  9          1000000          1000000    0 Jan 30 15:33 8261
> stgraber at castiana:~$ cat /proc/8261/status | grep -i ns
> NStgid: 8261    1
> NSpid:  8261    1
> NSpgid: 8261    1
> NSsid:  8261    1
> stgraber at castiana:~$ cat /proc/8261/uid_map
>          0    1000000 1000000000
> stgraber at castiana:~$ cat /proc/8261/gid_map
>          0    1000000 1000000000
>
>
> In this case, host PID 8261 is PID 1 in the container as can be found in
> the status file. For the owner, you need to read the uid and gid map,
> then do the math.
>
> In this case, the map says that uid 0 in the container is uid 1000000 on
> the host. The gid map is the same, so that means that this process is
> running as uid=0 gid=0 in the container.
>
> --
> Stéphane Graber
> Ubuntu developer
> http://www.ubuntu.com
>
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