followup: code cleanup

[pve-container.git] / src / lxc-pve-autodev-hook

#!/usr/bin/perl

use strict;
use warnings;

exit 0 if $ENV{LXC_NAME} && $ENV{LXC_NAME} !~ /^\d+$/;

use File::Path;
use File::Basename;

use PVE::Tools;

my $vmid = $ENV{LXC_NAME};
my $root = $ENV{LXC_ROOTFS_MOUNT};

if (@ARGV != 3 || $ARGV[1] ne 'lxc' || $ARGV[2] ne 'autodev') {
    die "invalid usage, this is an LXC autodev hook\n";
}

if ($vmid ne $ARGV[0]) {
    die "got wrong name: $ARGV[0] while LXC_NAME=$vmid\n";
}

my $devlist_file = "/var/lib/lxc/$vmid/devices";
my $fd;

if (! open $fd, '<', $devlist_file) {
    exit 0 if $!{ENOENT}; # If the list is empty the file might not exist.
    die "failed to open device list: $!\n";
}

sub cgroup_do_write($$) {
    my ($path, $value) = @_;
    my $fd;
    if (!open($fd, '>', $path)) {
	warn "failed to open cgroup file $path: $!\n";
	return 0;
    }
    if (!defined syswrite($fd, $value)) {
	warn "failed to write value $value to cgroup file $path: $!\n";
	return 0;
    }
    close($fd);
    return 1;
}

while (defined(my $line = <$fd>)) {
    if ($line !~ m@^(b):(\d+):(\d+):/dev/(\S+)\s*$@) {
	warn "invalid .pve-devices entry: $line\n";
    }
    my ($type, $major, $minor, $dev) = ($1, $2, $3, $4);

    # Don't break out of $root/dev/
    if ($dev =~ /\.\./) {
	warn "skipping illegal device node entry: $dev\n";
	next;
    }

    # Never expose /dev/loop-control
    if ($major == 10 && $minor == 237) {
	warn "skipping illegal device entry (loop-control) for: $dev\n";
	next;
    }

    my $rel_devpath = "/dev/$dev";
    my $rel_dir = dirname($rel_devpath);
    File::Path::mkpath("$root/$rel_dir");

    PVE::Tools::run_command(['mknod', '-m', '666', "$root/dev/$dev",
                             $type, $major, $minor]);

    if ($dev =~ /^dm-\d+$/) {
	File::Path::mkpath("$root/dev/mapper");
	my $mapped_name = PVE::Tools::file_get_contents("/sys/block/$dev/dm/name");
	chomp $mapped_name;
	symlink("/dev/$dev", "$root/dev/mapper/$mapped_name");
    }

    my $cgbase = "/sys/fs/cgroup/devices/lxc/$vmid";
    my $limitpath = "$cgbase/devices.allow";
    my $nspath = "$cgbase/ns/devices.allow";
    if (!cgroup_do_write($limitpath, "$type $major:$minor rwm")) {
	warn "failed to allow access to device $dev ($major:$minor)\n";
    }
    if (!cgroup_do_write($nspath, "$type $major:$minor rwm")) {
	warn "failed to allow access to device $dev ($major:$minor) inside the namespace\n";
    }
}
close $fd;

exit 0;