[pve-devel] [PATCH qemu-server v2 8/9] allow non-root users to set /dev/u?random as an RNG source

[Filip Schauer]

Allow non-root users with the VM.Config.HWType privilege to configure
/dev/urandom & /dev/random as an entropy source for a VirtIO RNG device.
/dev/hwrng remains restricted to the root user.

Signed-off-by: Filip Schauer <f.schauer at proxmox.com>
---
 PVE/API2/Qemu.pm  | 42 ++++++++++++++++++++++++++++++++++++++++++
 PVE/QemuServer.pm | 13 +++++++++++--
 2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/PVE/API2/Qemu.pm b/PVE/API2/Qemu.pm
index db356b7e..8262c9d4 100644
--- a/PVE/API2/Qemu.pm
+++ b/PVE/API2/Qemu.pm
@@ -670,6 +670,7 @@ my $hwtypeoptions = {
     'vga' => 1,
     'watchdog' => 1,
     'audio0' => 1,
+    'rng0' => 1,
 };
 
 my $generaloptions = {
@@ -798,6 +799,36 @@ my sub check_vm_create_hostpci_perm {
     return 1;
 };
 
+my sub check_rng_perm {
+    my ($rpcenv, $authuser, $vmid, $pool, $opt, $value) = @_;
+
+    return 1 if $authuser eq 'root at pam';
+
+    $rpcenv->check_vm_perm($authuser, $vmid, $pool, ['VM.Config.HWType']);
+
+    my $device = PVE::JSONSchema::parse_property_string('pve-qm-rng', $value);
+    if ($device->{source}) {
+	if ($device->{source} eq '/dev/hwrng') {
+	    die "only root can set '$opt' config for a non-mapped Hardware RNG device\n";
+	}
+    }
+
+    return 1;
+}
+
+my sub check_vm_create_rng_perm {
+    my ($rpcenv, $authuser, $vmid, $pool, $param) = @_;
+
+    return 1 if $authuser eq 'root at pam';
+
+    foreach my $opt (keys %{$param}) {
+	next if $opt !~ m/^rng\d+$/;
+	check_rng_perm($rpcenv, $authuser, $vmid, $pool, $opt, $param->{$opt});
+    }
+
+    return 1;
+};
+
 my $check_vm_modify_config_perm = sub {
     my ($rpcenv, $authuser, $vmid, $pool, $key_list) = @_;
 
@@ -1111,6 +1142,7 @@ __PACKAGE__->register_method({
 	    &$check_vm_create_serial_perm($rpcenv, $authuser, $vmid, $pool, $param);
 	    check_vm_create_usb_perm($rpcenv, $authuser, $vmid, $pool, $param);
 	    check_vm_create_hostpci_perm($rpcenv, $authuser, $vmid, $pool, $param);
+	    check_vm_create_rng_perm($rpcenv, $authuser, $vmid, $pool, $param);
 
 	    PVE::QemuServer::check_bridge_access($rpcenv, $authuser, $param);
 	    &$check_cpu_model_access($rpcenv, $authuser, $param);
@@ -2008,6 +2040,10 @@ my $update_vm_api  = sub {
 		    check_hostpci_perm($rpcenv, $authuser, $vmid, undef, $opt, $val);
 		    PVE::QemuConfig->add_to_pending_delete($conf, $opt, $force);
 		    PVE::QemuConfig->write_config($vmid, $conf);
+		} elsif ($opt eq m/^rng\d+$/) {
+		    check_rng_perm($rpcenv, $authuser, $vmid, undef, $opt, $val);
+		    PVE::QemuConfig->add_to_pending_delete($conf, $opt, $force);
+		    PVE::QemuConfig->write_config($vmid, $conf);
 		} elsif ($opt eq 'tags') {
 		    assert_tag_permissions($vmid, $val, '', $rpcenv, $authuser);
 		    delete $conf->{$opt};
@@ -2098,6 +2134,12 @@ my $update_vm_api  = sub {
 		    }
 		    check_hostpci_perm($rpcenv, $authuser, $vmid, undef, $opt, $param->{$opt});
 		    $conf->{pending}->{$opt} = $param->{$opt};
+		} elsif ($opt =~ m/^rng\d+$/) {
+		    if (my $oldvalue = $conf->{$opt}) {
+			check_rng_perm($rpcenv, $authuser, $vmid, undef, $opt, $oldvalue);
+		    }
+		    check_rng_perm($rpcenv, $authuser, $vmid, undef, $opt, $param->{$opt});
+		    $conf->{pending}->{$opt} = $param->{$opt};
 		} elsif ($opt eq 'tags') {
 		    assert_tag_permissions($vmid, $conf->{$opt}, $param->{$opt}, $rpcenv, $authuser);
 		    $conf->{pending}->{$opt} = PVE::GuestHelpers::get_unique_tags($param->{$opt});
diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 93e65825..606f51fa 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -6602,8 +6602,17 @@ sub check_mapping_access {
 	    } else {
 		die "either 'host' or 'mapping' must be set.\n";
 	    }
-       }
-   }
+	} elsif ($opt =~ m/^rng\d+$/) {
+	    my $device = PVE::JSONSchema::parse_property_string('pve-qm-rng', $conf->{$opt});
+
+	    if ($device->{source}) {
+		if ($device->{source} eq '/dev/hwrng') {
+		    die "only root can set '$opt' config for a non-mapped Hardware RNG device\n"
+			if $user ne 'root at pam';
+		}
+	    }
+	}
+    }
 };
 
 sub check_restore_permissions {
-- 
2.39.5