[pve-devel] [PATCH v2 container 1/1] Add device passthrough

[Filip Schauer <f.schauer@proxmox.com>]

Add a dev[n] argument to the container config to pass devices through to
a container. A device can be passed by its path. Alternatively a mapped
USB device can be passed through with usbmapping=<name>.

Signed-off-by: Filip Schauer <f.schauer@proxmox.com>
---
 src/PVE/LXC.pm        | 34 +++++++++++++++++++++++-
 src/PVE/LXC/Config.pm | 60 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
index c9b5ba7..a3ddb62 100644
--- a/src/PVE/LXC.pm
+++ b/src/PVE/LXC.pm
@@ -5,7 +5,8 @@ use warnings;
 
 use Cwd qw();
 use Errno qw(ELOOP ENOTDIR EROFS ECONNREFUSED EEXIST);
-use Fcntl qw(O_RDONLY O_WRONLY O_NOFOLLOW O_DIRECTORY);
+use Fcntl qw(O_RDONLY O_WRONLY O_NOFOLLOW O_DIRECTORY :mode);
+use File::Basename;
 use File::Path;
 use File::Spec;
 use IO::Poll qw(POLLIN POLLHUP);
@@ -639,6 +640,37 @@ sub update_lxc_config {
 	$raw .= "lxc.mount.auto = sys:mixed\n";
     }
 
+    # Clear passthrough directory from previous run
+    my $passthrough_dir = "/var/lib/lxc/$vmid/passthrough";
+    File::Path::rmtree($passthrough_dir);
+
+    PVE::LXC::Config->foreach_passthrough_device($conf, sub {
+	my ($key, $sanitized_path) = @_;
+
+	my $absolute_path = "/$sanitized_path";
+	my ($mode, $rdev) = (stat($absolute_path))[2, 6];
+	die "Could not find major and minor ids of device $absolute_path.\n"
+	    unless ($mode && $rdev);
+
+	my $major = PVE::Tools::dev_t_major($rdev);
+	my $minor = PVE::Tools::dev_t_minor($rdev);
+	my $device_type_char = S_ISBLK($mode) ? 'b' : 'c';
+	my $passthrough_device_path = "$passthrough_dir/$sanitized_path";
+	File::Path::make_path(dirname($passthrough_device_path));
+	PVE::Tools::run_command([
+	    '/usr/bin/mknod',
+	    '-m', '0660',
+	    $passthrough_device_path,
+	    $device_type_char,
+	    $major,
+	    $minor
+	]);
+	chown 100000, 100000, $passthrough_device_path if ($unprivileged);
+
+	$raw .= "lxc.cgroup2.devices.allow = $device_type_char $major:$minor rw\n";
+	$raw .= "lxc.mount.entry = $passthrough_device_path $sanitized_path none bind,create=file\n";
+    });
+
     # WARNING: DO NOT REMOVE this without making sure that loop device nodes
     # cannot be exposed to the container with r/w access (cgroup perms).
     # When this is enabled mounts will still remain in the monitor's namespace
diff --git a/src/PVE/LXC/Config.pm b/src/PVE/LXC/Config.pm
index 56e1f10..edd813e 100644
--- a/src/PVE/LXC/Config.pm
+++ b/src/PVE/LXC/Config.pm
@@ -29,6 +29,7 @@ mkdir $lockdir;
 mkdir "/etc/pve/nodes/$nodename/lxc";
 my $MAX_MOUNT_POINTS = 256;
 my $MAX_UNUSED_DISKS = $MAX_MOUNT_POINTS;
+my $MAX_DEVICES = 256;
 
 # BEGIN implemented abstract methods from PVE::AbstractConfig
 
@@ -908,6 +909,49 @@ for (my $i = 0; $i < $MAX_UNUSED_DISKS; $i++) {
     }
 }
 
+PVE::JSONSchema::register_format('pve-lxc-dev-string', \&verify_lxc_dev_string);
+sub verify_lxc_dev_string {
+    my ($dev, $noerr) = @_;
+
+    if (
+	$dev =~ m@/\.\.?/@ ||
+	$dev =~ m@/\.\.?$@ ||
+	$dev !~ m!^/dev/!
+    ) {
+	return undef if $noerr;
+	die "$dev is not a valid device path\n";
+    }
+
+    return $dev;
+}
+
+my $dev_desc = {
+    path => {
+	optional => 1,
+	type => 'string',
+	default_key => 1,
+	format => 'pve-lxc-dev-string',
+	format_description => 'Path',
+	description => 'Device to pass through to the container',
+	verbose_description => 'Path to the device to pass through to the container'
+    },
+    usbmapping => {
+	optional => 1,
+	type => 'string',
+	format => 'pve-configid',
+	format_description => 'mapping-id',
+	description => 'The ID of a cluster wide USB mapping.'
+    }
+};
+
+for (my $i = 0; $i < $MAX_DEVICES; $i++) {
+    $confdesc->{"dev$i"} = {
+	optional => 1,
+	type => 'string', format => $dev_desc,
+	description => "Device to pass through to the container",
+    }
+}
+
 sub parse_pct_config {
     my ($filename, $raw, $strict) = @_;
 
@@ -1255,6 +1299,22 @@ sub parse_volume {
     return;
 }
 
+sub parse_device {
+    my ($class, $device_string, $noerr) = @_;
+
+    my $res;
+    eval { $res = PVE::JSONSchema::parse_property_string($dev_desc, $device_string) };
+    if ($@) {
+	return undef if $noerr;
+	die $@;
+    }
+
+    die "Either path or usbmapping has to be defined"
+	unless (defined($res->{path}) || defined($res->{usbmapping}));
+
+    return $res;
+}
+
 sub print_volume {
     my ($class, $key, $volume) = @_;
 
-- 
2.39.2