cgmanager: put unprivileged containers under $(curcgroup)/lxc/$(container0

Currently if we are in /user.slice/user-1000.slice/session-c2.scope,
and we start an unprivileged container t1, it will be in cgroup
3:memory:/user.slice/user-1000.slice/session-c2.scope/t1.  If
we then do a 'lxc-cgroup -n t1 freezer.tasks', cgm_get will
first switch to 3:memory:/user.slice/user-1000.slice/session-c2.scope
then look up 't1's values.  The reasons for this are

1. cgmanager get_value is relative to your own cgroup, so we need
to be sure to be in t1's cgroup or an ancestor
2. we don't want to be in the container's cgroup bc it might freeze us.

But in Ubuntu 15.04 it was decided that
3:memory:/user.slice/user-1000.slice/session-c2.scope/tasks should
not be writeable by the user, making this fail.

Therefore put all unprivileged cgroups under "lxc/%n".  That way
the "lxc" cgroup should always be owned by the user so that he can
enter.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

diff --git a/src/lxc/utils.c b/src/lxc/utils.c
index e66a01f0c1edb82817eedfc550ded10802543ce9..f4abe7de630a6dee392aad271e5a07c6b543aa43 100644 (file)
--- a/src/lxc/utils.c
+++ b/src/lxc/utils.c
@@ -322,7 +322,7 @@ const char *lxc_global_config_value(const char *option_name)
                sprintf(user_config_path, "%s/.config/lxc/lxc.conf", user_home);
                sprintf(user_default_config_path, "%s/.config/lxc/default.conf", user_home);
                sprintf(user_lxc_path, "%s/.local/share/lxc/", user_home);
-               user_cgroup_pattern = strdup("%n");
+               user_cgroup_pattern = strdup("lxc/%n");
        }
        else {
                user_config_path = strdup(LXC_GLOBAL_CONF);