X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/7f5c2cfa5a987d887f42d6db95f80f42ceb3b5ff..f282512da75d19e38933f3083afa3c2a9dad463c:/IkiWiki/Plugin/img.pm

diff --git a/IkiWiki/Plugin/img.pm b/IkiWiki/Plugin/img.pm
index 54c13d069..ed2e9354d 100644
--- 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 +86,69 @@ 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.
+	my $magic;
+	my $offset = 0;
+	open(my $in, '<', $srcfile) or error sprintf(gettext("failed to read %s: %s"), $file, $!);
+	binmode($in);
+
+	if ($extension =~ m/^(jpeg|jpg)$/is) {
+		$format = 'jpeg';
+		$magic = "\377\330\377";
+	}
+	elsif ($extension =~ m/^(png)$/is) {
+		$format = 'png';
+		$magic = "\211PNG\r\n\032\n";
+	}
+	elsif ($extension =~ m/^(gif)$/is) {
+		$format = 'gif';
+		$magic = "GIF8";
+	}
+	elsif ($extension =~ m/^(svg)$/is) {
+		$format = 'svg';
+	}
+	elsif ($extension =~ m/^(pdf)$/is) {
+		$format = 'pdf';
+		$magic = "%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 ? $format : "everything");
+
+	# Try harder to protect ImageMagick from itself
+	if ($format eq 'svg') {
+		my $content;
+		read($in, $content, 5) or error sprintf(gettext("failed to read %s: %s"), $file, $!);
+		# This is an over-simplification, but ?xml is the check that
+		# ImageMagick uses. We also accept <svg for the simplest
+		# possible SVGs.
+		if ($content !~ m/^(.\?xml|<svg)/is) {
+			error sprintf(gettext("\"%s\" does not seem to be a valid %s file"), $file, $format);
+		}
+	}
+	elsif ($magic) {
+		my $content;
+		read($in, $content, length $magic) or error sprintf(gettext("failed to read %s: %s"), $file, $!);
+		if ($magic ne $content) {
+			error sprintf(gettext("\"%s\" does not seem to be a valid %s file"), $file, $format);
+		}
+	}
+
 	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 +161,13 @@ 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') {