img: restrict to JPEG, PNG and GIF images by default

[git.ikiwiki.info.git] / IkiWiki / Plugin / img.pm

diff --git a/IkiWiki/Plugin/img.pm b/IkiWiki/Plugin/img.pm
index 54c13d06919e0858442758d8fec09eb34bf0f0c3..53d963425eb1dade14cdb5e8406457b20b2916f7 100644 (file)
--- a/IkiWiki/Plugin/img.pm
+++ b/IkiWiki/Plugin/img.pm
@@ -21,6 +21,28 @@ sub getsetup () {
                        rebuild => undef,
                        section => "widget",
                },
+               img_allowed_formats => {
+                       type => "string",
+                       default => [qw(jpeg png gif)],
+                       description => "Image formats to process (jpeg, png, gif, pdf, svg or 'everything' to accept all)",
+                       # ImageMagick has had arbitrary code execution flaws,
+                       # and the whole delegates mechanism is scary from
+                       # that perspective
+                       safe => 0,
+                       rebuild => 0,
+               },
+}
+
+sub allowed {
+       my $format = shift;
+       my $allowed = $config{img_allowed_formats};
+       $allowed = ['jpeg', 'png'] unless defined $allowed && @$allowed;
+
+       foreach my $a (@$allowed) {
+               return 1 if $a eq $format || $a eq 'everything';
+       }
+
+       return 0;
 }
 
 sub preprocess (@) {
@@ -64,6 +86,41 @@ sub preprocess (@) {
 
        my $dir = $params{page};
        my $base = IkiWiki::basename($file);
+       my $extension;
+       my $format;
+
+       if ($base =~ m/\.([a-z0-9]+)$/) {
+               $extension = $1;
+       }
+       else {
+               error gettext("Unable to detect image type from extension");
+       }
+
+       # Never interpret well-known file extensions as any other format,
+       # in case the wiki configuration unwisely allows attaching
+       # arbitrary files named *.jpg, etc.
+       if ($extension =~ m/^(jpeg|jpg)$/is) {
+               $format = 'jpeg';
+       }
+       elsif ($extension =~ m/^(png)$/is) {
+               $format = 'png';
+       }
+       elsif ($extension =~ m/^(gif)$/is) {
+               $format = 'gif';
+       }
+       elsif ($extension =~ m/^(svg)$/is) {
+               $format = 'svg';
+       }
+       elsif ($extension =~ m/^(pdf)$/is) {
+               $format = 'pdf';
+       }
+       else {
+               # allow ImageMagick to auto-detect (potentially dangerous)
+               $format = '';
+       }
+
+       error sprintf(gettext("%s image processing disabled in img_allowed_formats configuration"), $format ? $format : "\"$extension\"") unless allowed($format ? $format : "everything");
+
        my $issvg = $base=~s/\.svg$/.png/i;
        my $ispdf = $base=~s/\.pdf$/.png/i;
        my $pagenumber = exists($params{pagenumber}) ? int($params{pagenumber}) : 0;
@@ -76,9 +133,13 @@ sub preprocess (@) {
        my $im = Image::Magick->new();
        my $imglink;
        my $imgdatalink;
-       my $r = $im->Read("$srcfile\[$pagenumber]");
+       my $r = $im->Read("$format:$srcfile\[$pagenumber]");
        error sprintf(gettext("failed to read %s: %s"), $file, $r) if $r;
-       
+
+       if (! defined $im->Get("width") || ! defined $im->Get("height")) {
+               error sprintf(gettext("failed to get dimensions of %s"), $file);
+       }
+
        my ($dwidth, $dheight);
 
        if ($params{size} eq 'full') {