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

[Fiona Ebner]

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? Would potentially help detecting other
issues with a source volume early.

> +			    my $path = PVE::Storage::path($storecfg, $source);
> +			    PVE::Storage::file_size_info($path, undef, 1);
> +			}
> +
>  			my $dest_info = {
>  			    vmid => $vmid,
>  			    drivename => $ds,
> @@ -441,7 +452,8 @@ my sub create_disks : prototype($$$$$$$$$$) {
>  		    }
>  		} else {
>  		    $source = PVE::Storage::abs_filesystem_path($storecfg, $source, 1);
> -		    ($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;
>  
>  		    if ($live_import && $ds ne 'efidisk0') {