On 7/31/18 2:49 PM, Wolfgang Bumiller wrote:
> Signed-off-by: Wolfgang Bumiller <w.bumil...@proxmox.com>
> ---
> debian/control | 2 +-
> src/PVE/LXC.pm | 101
> +++++++++++++++++++++++++++++++++++++++++++++++++-
> src/PVE/LXC/Config.pm | 53 ++++++++++++++++++++++++++
> 3 files changed, 153 insertions(+), 3 deletions(-)
>
> diff --git a/debian/control b/debian/control
> index 7fbea8d..b3491c9 100644
> --- a/debian/control
> +++ b/debian/control
> @@ -7,7 +7,7 @@ Build-Depends: debhelper (>= 7.0.50~),
> libpve-guest-common-perl | libpve-common-perl (<= 4.0-89),
> libpve-storage-perl,
> libtest-mockmodule-perl,
> - lxc (>= 2.1.0-1) | lxc-pve (>= 2.1.0-1),
> + lxc (>= 3.0.2-1) | lxc-pve (>= 3.0.1+pve1-1),
> pve-cluster (>= 4.0-8),
> pve-doc-generator,
> Standards-Version: 3.8.4
> diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
> index bc03792..46222ba 100644
> --- a/src/PVE/LXC.pm
> +++ b/src/PVE/LXC.pm
> @@ -27,6 +27,8 @@ use PVE::Syscall;
> use PVE::LXC::Config;
> use Time::HiRes qw (gettimeofday);
>
> +my $LXC_CONFIG_PATH = '/usr/share/lxc/config';
> +
> my $nodename = PVE::INotify::nodename();
>
> my $cpuinfo= PVE::ProcFSTools::read_cpuinfo();
> @@ -368,6 +370,94 @@ sub get_cgroup_subsystems {
> return wantarray ? ($v1, $v2) : $v1;
> }
>
> +# Currently we do not need to create seccomp profile 'files' as the only
> +# choice our configuration actually allows is "with or without keyctl()",
> +# so we distinguish between using lxc's "default" seccomp profile and our
> +# added pve-userns.seccomp file.
> +#
> +# This returns a configuration line added to the raw lxc config.
> +sub make_seccomp_config {
> + my ($conf, $unprivileged, $features) = @_;
> + # User-configured profile has precedence, note that the user's entry
> would
> + # be written 'after' this line anyway...
> + if (PVE::LXC::Config->has_lxc_entry($conf, 'lxc.seccomp.profile')) {
> + # Warn the user if this conflicts with a feature:
> + if ($features->{keyctl}) {
> + warn "explicitly configured lxc.seccomp.profile overrides the
> following settings: features:keyctl\n";
> + }
> + return '';
> + }
> +
> + # Privileged containers keep using the default (which is already part of
> + # the files included via lxc.include, so we don't need to write it out,
> + # that way it stays admin-configurable via /usr/share/lxc/config/... as
> + # well)
> + return '' if !$unprivileged;
> +
> + # Unprivileged containers will get keyctl() disabled by default as a
> + # workaround for systemd-networkd behavior. But we have an option to
> + # explicitly enable it:
> + return '' if $features->{keyctl};
> +
> + # Finally we're in an unprivileged container without `keyctl` set
> + # explicitly. We have a file prepared for this:
> + return "lxc.seccomp.profile = $LXC_CONFIG_PATH/pve-userns.seccomp\n";
> +}
> +
> +# Since lxc-3.0.2 we can have lxc generate a profile for the container
> +# automatically. The default should be equivalent to the old
> +# `lxc-container-default-cgns` profile.
> +#
> +# Additionally this also added `lxc.apparmor.raw` which can be used to inject
> +# additional lines into the profile. We can use that to allow mounting
> specific
> +# file systems.
> +sub make_apparmor_config {
> + my ($conf, $unprivileged, $features) = @_;
> +
> + # user-configured profile has precedence, but first we go through our own
> + # code to figure out whether we should warn the user:
> +
> + my $raw = "lxc.apparmor.profile = generated\n";
> + my @profile_uses;
> +
> + # There's lxc.apparmor.allow_nesting now, which will add the necessary
> + # apparmor lines, create an apparmor namespace for the container, but
> also
> + # adds proc and sysfs mounts to /dev/.lxc/{proc,sys}. These do not have
> + # lxcfs mounted over them, because that would prevent the container from
> + # mounting new instances of them for nested containers.
> + if ($features->{nesting}) {
> + push @profile_uses, 'features:nesting';
> + $raw .= "lxc.apparmor.allow_nesting = 1\n"
> + } else {
> + # In the default profile in /etc/apparmor.d we patch this in because
> + # otherwise a container can for example run `chown` on /sys, breaking
> + # access to it for non-CAP_DAC_OVERRIDE tools on the host:
> + $raw .= "lxc.apparmor.raw = deny mount -> /proc/,\n";
> + $raw .= "lxc.apparmor.raw = deny mount -> /sys/,\n";
> + # Preferably we could use the 'remount' flag but this does not sit well
> + # with apparmor_parser currently:
> + # mount options=(rw, nosuid, nodev, noexec, remount) -> /sys/,
> + }
> +
> + if (my $mount = $features->{mount}) {
> + push @profile_uses, 'features:mount';
> + foreach my $fs (PVE::Tools::split_list($mount)) {
> + $raw .= "lxc.apparmor.raw = mount fstype=$fs,\n";
> + }
> + }
> +
> + # More to come?
> +
> + if (PVE::LXC::Config->has_lxc_entry($conf, 'lxc.apparmor.profile')) {
> + if (length(my $used = join(', ', @profile_uses))) {
> + warn "explicitly configured lxc.apparmor.profile overrides the
> following settings: $used\n";
> + }
> + return '';
> + }
> +
> + return $raw;
> +}
> +
> sub update_lxc_config {
> my ($vmid, $conf) = @_;
>
> @@ -386,7 +476,7 @@ sub update_lxc_config {
> $raw .= "lxc.arch = $conf->{arch}\n";
>
> my $unprivileged = $conf->{unprivileged};
> - my $custom_idmap = grep { $_->[0] eq 'lxc.idmap' } @{$conf->{lxc}};
> + my $custom_idmap = PVE::LXC::Config->has_lxc_entry($conf, 'lxc.idmap');
>
> my $ostype = $conf->{ostype} || die "missing 'ostype' - internal error";
>
> @@ -398,9 +488,16 @@ sub update_lxc_config {
> $inc = "$cfgpath/$ostype.userns.conf";
> $inc = "$cfgpath/userns.conf" if !-f $inc;
> $raw .= "lxc.include = $inc\n";
> - $raw .= "lxc.seccomp.profile = $cfgpath/pve-userns.seccomp\n";
> }
>
> + my $features = PVE::LXC::Config->parse_features($conf->{features});
> +
> + $raw .= make_seccomp_config($conf, $unprivileged || $custom_idmap,
> + $features);
> +
> + $raw .= make_apparmor_config($conf, $unprivileged || $custom_idmap,
> + $features);
what is the combination of '$unprivileged || $custom_idmap'`?
In the methods called this parameter is called just '$unprivileged',
so it's a bit confusing that it gets that also on true if an
user/group ID mapping is used.
maybe pull that out (with your addition this || construct is used in three
places)
call it something alike $usernamespaced or $use_userns?
Looks OK besides that.
> +
> # 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 a2693d7..9f6765e 100644
> --- a/src/PVE/LXC/Config.pm
> +++ b/src/PVE/LXC/Config.pm
> @@ -272,6 +272,41 @@
> PVE::JSONSchema::register_standard_option('pve-lxc-snapshot-name', {
> maxLength => 40,
> });
>
> +my $features_desc = {
> + mount => {
> + optional => 1,
> + type => 'string',
> + description => "Allow mounting file systems of specific types."
> + ." This should be a list of file system types as used with the
> mount command."
> + ." Note that this can have negative effects on the container's
> security."
> + ." With access to a loop device, mounting a file can circumvent the
> mknod"
> + ." permission of the devices cgroup, mounting an NFS file system
> can"
> + ." block the host's I/O completely and prevent it from rebooting,
> etc.",
> + format_description => 'fstype;fstype;...',
> + pattern => qr/[a-zA-Z0-9; ]+/,
> + },
> + nesting => {
> + optional => 1,
> + type => 'boolean',
> + default => 0,
> + description => "Allow nesting."
> + ." Best used with unprivileged containers with additional id
> mapping."
> + ." Note that this will expose procfs and sysfs contents of the host"
> + ." to the guest.",
> + },
> + keyctl => {
> + optional => 1,
> + type => 'boolean',
> + default => 0,
> + description => "For unprivileged containers only: Allow the use of the
> keyctl() system call."
> + ." This is required to use docker inside a container."
> + ." By default unprivileged containers will see this system call as
> non-existent."
> + ." This is mostly a workaround for systemd-networkd, as it will
> treat it as a fatal"
> + ." error when some keyctl() operations are denied by the kernel due
> to lacking permissions."
> + ." Essentially, you can choose between running systemd-networkd or
> docker.",
> + },
> +};
> +
> my $confdesc = {
> lock => {
> optional => 1,
> @@ -409,6 +444,12 @@ my $confdesc = {
> description => "Makes the container run as unprivileged user. (Should
> not be modified manually.)",
> default => 0,
> },
> + features => {
> + optional => 1,
> + type => 'string',
> + format => $features_desc,
> + description => "Allow containers access to advanced features.",
> + },
> };
>
> my $valid_lxc_conf_keys = {
> @@ -872,6 +913,9 @@ sub update_pct_config {
> }
> } elsif ($opt eq 'unprivileged') {
> die "unable to delete read-only option: '$opt'\n";
> + } elsif ($opt eq 'features') {
> + next if $hotplug_error->($opt);
> + delete $conf->{$opt};
> } else {
> die "implement me (delete: $opt)"
> }
> @@ -1025,6 +1069,9 @@ sub update_pct_config {
> } elsif ($opt eq 'ostype') {
> next if $hotplug_error->($opt);
> $conf->{$opt} = $value;
> + } elsif ($opt eq 'features') {
> + next if $hotplug_error->($opt);
> + $conf->{$opt} = $value;
> } else {
> die "implement me: $opt";
> }
> @@ -1176,6 +1223,12 @@ sub parse_lxc_network {
> return $res;
> }
>
> +sub parse_features {
> + my ($class, $data) = @_;
> + return {} if !$data;
> + return PVE::JSONSchema::parse_property_string($features_desc, $data);
> +}
> +
> sub option_exists {
> my ($class, $name) = @_;
>
>
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