Current Perl versions put '.' at the end of the library search path
@INC, although this will be fixed in a future Perl release. This means
that when software loads an optionally-present module, it will be
looked for in the current working directory before giving up. An
attacker could use this to execute arbitrary Perl code from ikiwiki's
current working directory.
Removing '.' from the library search path in Perl is the correct
fix for this vulnerability, but is not trivial to do due to
backwards-compatibility concerns. Mitigate this (even if ikiwiki is run
with a vulnerable Perl version) by explicitly removing '.' from the
search path, and instead looking for ikiwiki's own modules relative
to the absolute path of the executable when run from the source
directory.
In tests that specifically want to use the current working directory,
use "-I".getcwd instead of "-I." so we use its absolute path, which
is immune to the removal of ".".
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.
$im->Read() takes a filename-like argument with several sets of special
syntax. Most of the possible metacharacters are escaped by the
default `wiki_file_chars` (and in any case not particularly disruptive),
but the colon ":" is not.
It seems the way to force ImageMagick to treat colons within the
filename as literal is to prepend a colon, so do that.
[[forum/refresh_and_setup]] indicates some confusion between --setup
and -setup. Both work, but it's clearer if we stick to one in
documentation and code.
A 2012 commit to [[plugins/theme]] claims that "-setup" is required
and "--setup" won't work, but I cannot find any evidence in ikiwiki's
source code that this has ever been the case.
Inkscape loses the bounding box of a SVG with no content when it
converts it to EPS, and ImageMagick does not have a special case for
converting SVG to PNG with Inkscape in one step (which Inkscape can do);
it prefers to convert SVG to EPS with Inkscape, then EPS to whatever.
there is now a size calculating part (which chooses a final size) and a
scaling part (which triggers if the sizes calculated by the former
indicate a downscaling).
this solves the issue of unproportional upscalings
(bugs/image_rescaling_distorts_with_small_pictures).
also, "small" pdf files (or pdf files without explicit size settings),
which would not be converted under the old mechanism, now get rendered
to pngs.
this commit affects a unit test: while svgs were previously
unconditionally rendered to pngs, this now only happens on downscaling.
this is intentional -- while a small version of an svg graphic is
likely to be more compact when rendered (eg as a preview), a large
version would not have that benefit, and why convert something that
browsers basically can show and be inconsistend with how other images
are handled. the new unit test simply makes the original svg larger to
check for the same behaviros as before.
Simon McVittie
Amitai Schlair
Joey Hess
chrysn