Bug#890419: [PATCH] Fix boostrapping libvirt LXC containers

[Lubomir Rintel <lkundrak@v3.sk>]

One more patch, to make debootstrap work in case the container has a
separate userns, but not netns.

This makes debootstrap work with virt-install with this branch [1],
making it rather convenient to install a Debian container with virt-
install:

virt-install \
        --debug \
        --connect lxc:/// \
        --name debian \
        --memory 512 \
        --idmap uid_start=0,uid_target=1000000,uid_count=65536,gid_start=0,gid_target=1000000,gid_count=65536 \
        --filesystem /var/lib/libvirt/filesystems/debian,/ \
        --location http://ftp.us.debian.org/debian/dists/testing/

[1] https://github.com/lkundrak/virt-manager/tree/lr/lxc-install

From f2524081ad9b9b10ab6b4d1b50f3f55cdc3c9375 Mon Sep 17 00:00:00 2001
From: Lubomir Rintel <lkundrak@v3.sk>
Date: Tue, 20 Mar 2018 22:20:34 +0100
Subject: [PATCH 4/4] Unshare the net namespace in LXC namespace

If we're running without privnet but with a idmap we are CAP_SYS_ADMIN
in the userns but not in the netns and therefore mounting a new sysfs
instance is not allowed (since [7dc5dbc879bd sysfs: Restrict mounting
sysfs] in kernel 3.11).
---
 debootstrap | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/debootstrap b/debootstrap
index fcdb20f..86d489a 100755
--- a/debootstrap
+++ b/debootstrap
@@ -468,6 +468,10 @@ else
 	CHROOT_CMD="chroot $TARGET"
 fi
 
+if grep -q container=lxc-libvirt /proc/1/environ; then
+	CHROOT_CMD="unshare --net $CHROOT_CMD"
+fi
+
 if [ -z "$SHA_SIZE" ]; then
 	SHA_SIZE=256
 fi
-- 
2.14.3