[lxc-users] unprivileged container + setcap not working

[Serge E. Hallyn]

Quoting Philip (ultrafit67 at gmail.com):
> Please ignore step 4, lxc.id_map only allow ONE uid/gid, so
> lxc_switch_uid_gid will fail

I'm not sure what you mean by that, but your id mapping makes
uid 2000 on the host map to 0 in the container, and that is the
only uid in the container.

So lxc.init_uid would need to be 0 - the id in the container.

> On Fri, Dec 15, 2017 at 10:17 AM Philip <ultrafit67 at gmail.com> wrote:
> 
> > Hi,
> >
> > I want to use unprivileged container + setcap to set limited capabilities,
> > but can not success, here is my test (lxc-1.0.8 and lxc-2.0.8):
> >
> > testapp:
> > int ret = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
> > fprintf(stderr, "socket ret %d, %s\n", ret, strerror(errno));
> >
> > 1. add net_raw capability
> > setcap cap_net_admin,cap_net_raw=eip ./testapp
> >
> > 2. switch to uid 2000, execute testapp
> > $ ./testapp
> > socket ret 3, Success
> >
> > 3. use unprivileged container to run testapp
> > lxc config:
> > lxc.network.type = none
> > lxc.id_map = u 0 2000 1
> > lxc.id_map = g 0 2000 1
> >
> > sudo lxc-execute -n testapp -f config -P /files/testapp
> > ....
> > socket ret -1, Operation not permitted
> >
> > 4. using lxc-2.0.8, add init_uid/init_gid
> > lxc.init_uid = 2000
> > lxc.init_gid = 2000
> >
> > lxc-execute: utils.c: lxc_switch_uid_gid: 2069 Invalid argument - Failed
> > to switch to gid 2000.
> >
> > Can anyone help, what is going wrong?
> >

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