[pve-devel] [PATCH v2 qemu-server 1/1] disk import: add additional safeguards for imported image files

[Fiona Ebner]

On 15.11.24 10:42 AM, Fiona Ebner wrote:
> On 04.11.24 11:42 AM, Fabian Grünbichler wrote:
>> creating non-raw disk images with arbitrary content is only possible with raw
>> access to the storage, but checking for references to external files doesn't
>> hurt.
>>
>> Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
>> ---
>>
>> Notes:
>>     requires pve-storage change to actually have an effect
>>     
>>     v2:
>>     - re-order code to improve readability
>>     - extract $path into variable to avoid scalar vs array context issue
>>
>>  PVE/API2/Qemu.pm | 18 +++++++++++++++---
>>  1 file changed, 15 insertions(+), 3 deletions(-)
>>
>> diff --git a/PVE/API2/Qemu.pm b/PVE/API2/Qemu.pm
>> index 848001b6..ae0c39bf 100644
>> --- a/PVE/API2/Qemu.pm
>> +++ b/PVE/API2/Qemu.pm
>> @@ -412,18 +412,29 @@ my sub create_disks : prototype($$$$$$$$$$) {
>>  
>>  		$needs_creation = $live_import;
>>  
>> -		if (PVE::Storage::parse_volume_id($source, 1)) { # PVE-managed volume
>> +		my ($source_storage, $source_volid) = PVE::Storage::parse_volume_id($source, 1);
>> +
>> +		if ($source_storage) { # PVE-managed volume
>>  		    if ($live_import && $ds ne 'efidisk0') {
>>  			my $path = PVE::Storage::path($storecfg, $source)
>>  			    or die "failed to get a path for '$source'\n";
>>  			$source = $path;
>> -			($size, my $source_format) = PVE::Storage::file_size_info($source);
>> +			# check potentially untrusted image file!
>> +			($size, my $source_format) = PVE::Storage::file_size_info($source, undef, 1);
>> +
>>  			die "could not get file size of $source\n" if !$size;
>>  			$live_import_mapping->{$ds} = {
>>  			    path => $source,
>>  			    format => $source_format,
>>  			};
>>  		    } else {
>> +			# check potentially untrusted image file!
>> +			my $scfg = PVE::Storage::storage_config($storecfg, $source_storage);
>> +			if ($scfg->{path}) {
> 
> Is there a special reason this is made conditional on the presence of
> $scfg->{path}? Note that the above check for live import isn't.
> Shouldn't matter much right now (except if there is a weird third-party
> plugin that has qcow2 and doesn't use $scfg->{path}), but as long as we
> get a result for PVE::Storage::path(), we should be able to call
> file_size_info() too, right?
> 

Or maybe not, but then live-import should've used volume_size_info() too
I guess? I think it would be good to add an 'untrusted' flag to
volume_size_info() too and have the storage layer do the right thing,
rather than manually checking $scfg->{path} here.