[pve-devel] [PATCH v3 qemu-server 07/11] Verify VM-specific CPU configs seperately

[Stefan Reiter]

$cpu_fmt is being reused for custom CPUs as well as VM-specific CPU
settings. The "pve-vm-cpu-conf" format is introduced to verify a config
specifically for use as VM-specific settings.

Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
---

v2 -> v3:
* move $cpu_fmt->{flags} changes here, to avoid having broken checks between
  patches


 PVE/QemuServer.pm           |  2 +-
 PVE/QemuServer/CPUConfig.pm | 68 ++++++++++++++++++++++++++++++++++---
 2 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 58e2944..04ab1c2 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -505,7 +505,7 @@ EODESCR
 	optional => 1,
 	description => "Emulated CPU type.",
 	type => 'string',
-	format => $PVE::QemuServer::CPUConfig::cpu_fmt,
+	format => 'pve-vm-cpu-conf',
     },
     parent => get_standard_option('pve-snapshot-name', {
 	optional => 1,
diff --git a/PVE/QemuServer/CPUConfig.pm b/PVE/QemuServer/CPUConfig.pm
index d335733..10b383e 100644
--- a/PVE/QemuServer/CPUConfig.pm
+++ b/PVE/QemuServer/CPUConfig.pm
@@ -90,9 +90,9 @@ my @supported_cpu_flags = (
     'hv-evmcs',
     'aes'
 );
-my $cpu_flag = qr/[+-](@{[join('|', @supported_cpu_flags)]})/;
+my $cpu_flag_re = qr/([+-])(@{[join('|', @supported_cpu_flags)]})/;
 
-our $cpu_fmt = {
+my $cpu_fmt = {
     cputype => {
 	description => "Emulated CPU type. Can be default or custom name.",
 	type => 'string',
@@ -131,14 +131,74 @@ our $cpu_fmt = {
     flags => {
 	description => "List of additional CPU flags separated by ';'."
 		     . " Use '+FLAG' to enable, '-FLAG' to disable a flag."
-		     . " Currently supported flags: @{[join(', ', @supported_cpu_flags)]}.",
+		     . " Custom CPU models can specify any flag supported by"
+		     . " QEMU/KVM, VM-specific flags must be from the following"
+		     . " set for security reasons: @{[join(', ', @supported_cpu_flags)]}.",
 	format_description => '+FLAG[;-FLAG...]',
 	type => 'string',
-	pattern => qr/$cpu_flag(;$cpu_flag)*/,
+	pattern => qr/[+-][a-zA-Z0-9\-_\.]+(;[+-][a-zA-Z0-9\-_\.]+)*/,
 	optional => 1,
     },
 };
 
+# $cpu_fmt describes both the CPU config passed as part of a VM config, as well
+# as the definition of a custom CPU model. There are some slight differences
+# though, which we catch in the custom verification function below.
+sub parse_cpu_conf_basic {
+    my ($cpu_str, $noerr) = @_;
+
+    my $cpu = eval { PVE::JSONSchema::parse_property_string($cpu_fmt, $cpu_str) };
+    if ($@) {
+        die $@ if !$noerr;
+        return undef;
+    }
+
+    # required, but can't be made "optional => 0" since it's not included as a
+    # seperate property in config file
+    if (!$cpu->{cputype}) {
+	die "CPU is missing cputype\n" if !$noerr;
+	return undef;
+    }
+
+    return $cpu;
+}
+
+PVE::JSONSchema::register_format('pve-vm-cpu-conf', \&verify_vm_cpu_conf);
+sub verify_vm_cpu_conf {
+    my ($cpu_str, $noerr) = @_;
+
+    my $cpu = parse_cpu_conf_basic($cpu_str, $noerr);
+    return undef if !$cpu;
+
+    my $cputype = $cpu->{cputype};
+
+    if (!$cpu->{'built-in'}) {
+	# Custom model only has to exist, all props are allowed
+	my $config = load_custom_model_conf();
+	return $cpu if $config && defined($config->{ids}->{$cputype});
+
+	die "Custom cputype '$cputype' not found\n" if !$noerr;
+	return undef;
+    }
+
+    # Only built-in models get here
+    if (!defined($cpu_vendor_list->{$cputype})) {
+	die "Default cputype '$cputype' not found\n" if !$noerr;
+	return undef;
+    }
+
+    if ($cpu->{flags} && $cpu->{flags} !~ m/$cpu_flag_re(;$cpu_flag_re)*/) {
+	die "VM-specific CPU flags must be a subset of: @{[join(', ', @supported_cpu_flags)]}\n"
+	    if !$noerr;
+	return undef;
+    }
+
+    die "Property 'reported-model' not allowed in VM-specific CPU config.\n"
+	if defined($cpu->{'reported-model'});
+
+    return $cpu;
+}
+
 # Section config settings
 my $defaultData = {
     # shallow copy, since SectionConfig modifies propertyList internally
-- 
2.20.1