[pve-devel] [PATCH container 1/2] net: Add `link_down` config to allow setting interfaces as disconnected

[Christoph Heiss]

If this network option is set, the host-side link will be forced down.
This has the effect that the interface inside the container has
LOWERLAYERDOWN set, which basically means that the PHY is considered
down, thus effectivly being "unplugged".

Also fix some trailing whitespace while touching the file.

Signed-off-by: Christoph Heiss <c.heiss at proxmox.com>
---
 src/PVE/LXC.pm        | 20 +++++++++++++-------
 src/PVE/LXC/Config.pm |  5 +++++
 src/lxcnetaddbr       |  3 ++-
 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
index ce6d5a5..039a476 100644
--- a/src/PVE/LXC.pm
+++ b/src/PVE/LXC.pm
@@ -668,7 +668,7 @@ sub update_lxc_config {

     # some init scripts expect a linux terminal (turnkey).
     $raw .= "lxc.environment = TERM=linux\n";
-
+
     my $utsname = $conf->{hostname} || "CT$vmid";
     $raw .= "lxc.uts.name = $utsname\n";

@@ -932,8 +932,9 @@ sub update_net {
 	my $oldnet = PVE::LXC::Config->parse_lxc_network($oldnetcfg);

 	if (safe_string_ne($oldnet->{hwaddr}, $newnet->{hwaddr}) ||
-	    safe_string_ne($oldnet->{name}, $newnet->{name})) {
-
+	    safe_string_ne($oldnet->{name}, $newnet->{name}) ||
+	    defined($oldnet->{link_down}) != defined($newnet->{link_down})
+	) {
 	    PVE::Network::veth_delete($veth);
 	    delete $conf->{$opt};
 	    PVE::LXC::Config->write_config($vmid, $conf);
@@ -1010,6 +1011,11 @@ sub hotplug_net {
     $cmd = ['lxc-attach', '-n', $vmid, '-s', 'NETWORK', '--', '/sbin/ip', 'link', 'set', $eth ,'up'  ];
     PVE::Tools::run_command($cmd);

+    # In case the network device should be disconnected, force the host-link down
+    if (defined($newnet->{link_down})) {
+	PVE::Tools::run_command(['/sbin/ip', 'link', 'set', 'dev', $veth, 'down']);
+    }
+
     my $done = { type => 'veth' };
     foreach (qw(bridge tag firewall hwaddr name)) {
 	$done->{$_} = $newnet->{$_} if $newnet->{$_};
@@ -1703,14 +1709,14 @@ sub __mountpoint_mount {
     my $type = $mountpoint->{type};
     my $quota = !$snapname && !$mountpoint->{ro} && $mountpoint->{quota};
     my $mounted_dev;
-
+
     return if !$volid || !$mount;

     $mount =~ s!/+!/!g;

     my $mount_path;
     my ($mpfd, $parentfd, $last_dir);
-
+
     if (defined($rootdir)) {
 	($rootdir, $mount_path, $mpfd, $parentfd, $last_dir) =
 	    __mount_prepare_rootdir($rootdir, $mount, $rootuid, $rootgid);
@@ -1719,7 +1725,7 @@ sub __mountpoint_mount {
     if (defined($stage_mount)) {
 	$mount_path = $rootdir;
     }
-
+
     my ($storage, $volname) = PVE::Storage::parse_volume_id($volid, 1);

     die "unknown snapshot path for '$volid'" if !$storage && defined($snapname);
@@ -1828,7 +1834,7 @@ sub __mountpoint_mount {
 	warn "cannot enable quota control for bind mounts\n" if $quota;
 	return wantarray ? ($volid, 0, undef) : $volid;
     }
-
+
     die "unsupported storage";
 }

diff --git a/src/PVE/LXC/Config.pm b/src/PVE/LXC/Config.pm
index af25a96..1d4362e 100644
--- a/src/PVE/LXC/Config.pm
+++ b/src/PVE/LXC/Config.pm
@@ -814,6 +814,11 @@ our $netconf_desc = {
 	description => "Apply rate limiting to the interface",
 	optional => 1,
     },
+    link_down => {
+	type => 'boolean',
+	description => 'Whether this interface should be disconnected (like pulling the plug).',
+	optional => 1,
+    },
 };
 PVE::JSONSchema::register_format('pve-lxc-network', $netconf_desc);

diff --git a/src/lxcnetaddbr b/src/lxcnetaddbr
index 83052e1..d8c6767 100755
--- a/src/lxcnetaddbr
+++ b/src/lxcnetaddbr
@@ -58,7 +58,8 @@ if (-d "/sys/class/net/$iface") {
     #avoid insecure dependency;
     ($bridgemtu) = $bridgemtu =~ /(\d+)/;

-    PVE::Tools::run_command("/sbin/ip link set dev $iface up mtu $bridgemtu");
+    my $linkstate = defined($net->{link_down}) ? 'down' : 'up';
+    PVE::Tools::run_command("/sbin/ip link set dev $iface $linkstate mtu $bridgemtu");
     PVE::Tools::run_command("/sbin/ip addr add 0.0.0.0/0 dev $iface");

     if ($have_sdn) {
--
2.39.1