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authorSimon McVittie <smcv@debian.org>2016-05-04 08:54:19 +0100
committerSimon McVittie <smcv@debian.org>2016-05-05 23:43:50 +0100
commit545a7bbbf07dd2375a96eae09f9abd6329a919e5 (patch)
tree87d4952a8d68b4d65a05b4ee6681a088d7cf9519
parent54a9f8d07de3bf853a74c34ca98bcb3ec9bc8ac7 (diff)
downloadikiwiki-545a7bbbf07dd2375a96eae09f9abd6329a919e5.tar
ikiwiki-545a7bbbf07dd2375a96eae09f9abd6329a919e5.tar.gz
img: restrict to JPEG, PNG and GIF images by default
This mitigates CVE-2016-3714. Wiki administrators who know that they have prevented arbitrary code execution via other formats can re-enable the other formats if desired.
-rw-r--r--IkiWiki/Plugin/img.pm24
-rwxr-xr-xt/img.t46
-rw-r--r--t/img/redsquare.jpgbin0 -> 294 bytes
3 files changed, 65 insertions, 5 deletions
diff --git a/IkiWiki/Plugin/img.pm b/IkiWiki/Plugin/img.pm
index a63e27dd6..53d963425 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 (@) {
@@ -97,6 +119,8 @@ sub preprocess (@) {
$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;
diff --git a/t/img.t b/t/img.t
index b73988b7c..6f822bbd5 100755
--- a/t/img.t
+++ b/t/img.t
@@ -44,19 +44,26 @@ my $PDFS_WORK = defined $magick->Get("width");
ok(! system("rm -rf t/tmp; mkdir -p t/tmp/in"));
ok(! system("cp t/img/redsquare.png t/tmp/in/redsquare.png"));
+ok(! system("cp t/img/redsquare.jpg t/tmp/in/redsquare.jpg"));
+ok(! system("cp t/img/redsquare.jpg t/tmp/in/redsquare.jpeg"));
# colons in filenames are a corner case for img
ok(! system("cp t/img/redsquare.png t/tmp/in/hello:world.png"));
ok(! system("cp t/img/redsquare.png t/tmp/in/a:b:c.png"));
ok(! system("cp t/img/redsquare.png t/tmp/in/a:b:c:d.png"));
ok(! system("cp t/img/redsquare.png t/tmp/in/a:b:c:d:e:f:g:h:i:j.png"));
-if ($SVGS_WORK) {
- writefile("bluesquare.svg", "t/tmp/in",
- '<svg width="30" height="30"><rect x="0" y="0" width="30" height="30" fill="blue"/></svg>');
-}
+writefile("bluesquare.svg", "t/tmp/in",
+ '<svg width="30" height="30"><rect x="0" y="0" width="30" height="30" fill="blue"/></svg>');
+ok(! system("cp t/tmp/in/bluesquare.svg t/tmp/in/really-svg.png"));
+ok(! system("cp t/tmp/in/bluesquare.svg t/tmp/in/really-svg.bmp"));
+ok(! system("cp t/tmp/in/bluesquare.svg t/tmp/in/really-svg.pdf"));
# using different image sizes for different pages, so the pagenumber selection can be tested easily
ok(! system("cp t/img/twopages.pdf t/tmp/in/twopages.pdf"));
+ok(! system("cp t/img/twopages.pdf t/tmp/in/really-pdf.jpeg"));
+ok(! system("cp t/img/twopages.pdf t/tmp/in/really-pdf.jpg"));
+ok(! system("cp t/img/twopages.pdf t/tmp/in/really-pdf.png"));
+ok(! system("cp t/img/twopages.pdf t/tmp/in/really-pdf.svg"));
my $maybe_svg_img = "";
if ($SVGS_WORK) {
@@ -73,6 +80,8 @@ EOF
writefile("imgconversions.mdwn", "t/tmp/in", <<EOF
[[!img redsquare.png]]
+[[!img redsquare.jpg size=11x]]
+[[!img redsquare.jpeg size=12x]]
[[!img redsquare.png size=10x]]
[[!img redsquare.png size=30x50]] expecting 30x30
[[!img hello:world.png size=x8]] expecting 8x8
@@ -80,11 +89,20 @@ writefile("imgconversions.mdwn", "t/tmp/in", <<EOF
[[!img a:b:c:d:e:f:g:h:i:j.png size=x6]]
$maybe_svg_img
$maybe_pdf_img
+
+# bad ideas
+[[!img really-svg.png size=666x]]
+[[!img really-svg.bmp size=666x]]
+[[!img really-svg.pdf size=666x]]
+[[!img really-pdf.jpeg size=666x]]
+[[!img really-pdf.jpg size=666x]]
+[[!img really-pdf.png size=666x]]
+[[!img really-pdf.svg size=666x]]
EOF
);
ok(utime(333333333, 333333333, "t/tmp/in/imgconversions.mdwn"));
-ok(! system(@command));
+ok(! system(@command, '--set-yaml', 'img_allowed_formats=[jpeg, png, svg, pdf]'));
sub size($) {
my $filename = shift;
@@ -122,6 +140,24 @@ is(size("$outpath/x8-hello:world.png"), "8x8");
is(size("$outpath/x4-a:b:c.png"), "4x4");
is(size("$outpath/x6-a:b:c:d:e:f:g:h:i:j.png"), "6x6");
+is(size("$outpath/11x-redsquare.jpg"), "11x11");
+is(size("$outpath/12x-redsquare.jpeg"), "12x12");
+like($outhtml, qr{src="(\./)?imgconversions/11x-redsquare\.jpg" width="11" height="11"});
+like($outhtml, qr{src="(\./)?imgconversions/12x-redsquare\.jpeg" width="12" height="12"});
+
+# We do not misinterpret images
+ok(! -e "$outpath/666x-really-svg.png");
+ok(! -e "$outpath/666x-really-svg.bmp");
+ok(! -e "$outpath/666x-really-pdf.jpeg");
+ok(! -e "$outpath/666x-really-pdf.jpg");
+ok(! -e "$outpath/666x-really-pdf.png");
+
+# disable support for uncommon formats and try again
+ok(! system(@command, "--rebuild"));
+ok(! -e "$outpath/10x-bluesquare.png");
+ok(! -e "$outpath/12x-twopages.png");
+ok(! -e "$outpath/16x-p1-twopages.png");
+
# now let's remove them again
if (1) { # for easier testing
diff --git a/t/img/redsquare.jpg b/t/img/redsquare.jpg
new file mode 100644
index 000000000..565d7f33b
--- /dev/null
+++ b/t/img/redsquare.jpg
Binary files differ