X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/eba2dee941c18b3a1bd9c8af52c01ba7b5b46a64..6b5b0a3282a1409476beb498030e035c5b462440:/doc/plugins/po.mdwn
diff --git a/doc/plugins/po.mdwn b/doc/plugins/po.mdwn
index cb0dd65c0..f91e44ea3 100644
--- a/doc/plugins/po.mdwn
+++ b/doc/plugins/po.mdwn
@@ -5,6 +5,8 @@ This plugin adds support for multi-lingual wikis, translated with
gettext, using [po4a](http://po4a.alioth.debian.org/).
It depends on the Perl `Locale::Po4a::Po` library (`apt-get install po4a`).
+As detailed bellow in the security section, `po4a` is subject to
+denial-of-service attacks before version 0.35.
[[!toc levels=2]]
@@ -31,6 +33,12 @@ Example: `bla/page.fr.po` is the PO "message catalog" used to
translate `bla/page.mdwn` into French; if `usedirs` is enabled, it is
rendered as `bla/page/index.fr.html`, else as `bla/page.fr.html`
+(In)Compatibility
+=================
+
+This plugin does not support the `indexpages` mode. If you don't know
+what it is, you probably don't care.
+
Configuration
=============
@@ -41,15 +49,15 @@ Supported languages
`po_master_language` is used to set the "master" language in
`ikiwiki.setup`, such as:
- po_master_language => { 'code' => 'en', 'name' => 'English' }
+ po_master_language => 'en|English'
`po_slave_languages` is used to set the list of supported "slave"
languages, such as:
- po_slave_languages => { 'fr' => 'Français',
- 'es' => 'Castellano',
- 'de' => 'Deutsch',
- }
+ po_slave_languages => [ 'fr|Français',
+ 'es|Español',
+ 'de|Deutsch',
+ ]
Decide which pages are translatable
-----------------------------------
@@ -64,39 +72,40 @@ worry about excluding them explicitly from this [[ikiwiki/PageSpec]].
Internal links
--------------
+### Links targets
+
The `po_link_to` option in `ikiwiki.setup` is used to decide how
internal links should be generated, depending on web server features
and site-specific preferences.
-### Default linking behavior
+#### Default linking behavior
If `po_link_to` is unset, or set to `default`, ikiwiki's default
linking behavior is preserved: `\[[destpage]]` links to the master
language's page.
-### Link to current language
+#### Link to current language
If `po_link_to` is set to `current`, `\[[destpage]]` links to the
`destpage`'s version written in the current page's language, if
available, *i.e.*:
-- `foo/destpage/index.LL.html` if `usedirs` is enabled
-- `foo/destpage.LL.html` if `usedirs` is disabled
+* `foo/destpage/index.LL.html` if `usedirs` is enabled
+* `foo/destpage.LL.html` if `usedirs` is disabled
-### Link to negotiated language
+#### Link to negotiated language
If `po_link_to` is set to `negotiated`, `\[[page]]` links to the
negotiated preferred language, *i.e.* `foo/page/`.
(In)compatibility notes:
-- if `usedirs` is disabled, it does not make sense to set `po_link_to`
+* if `usedirs` is disabled, it does not make sense to set `po_link_to`
to `negotiated`; this option combination is neither implemented
nor allowed.
-- if the web server does not support Content Negotiation, setting
+* if the web server does not support Content Negotiation, setting
`po_link_to` to `negotiated` will produce a unusable website.
-
Server support
==============
@@ -105,23 +114,28 @@ Apache
Using Apache `mod_negotiation` makes it really easy to have Apache
serve any page in the client's preferred language, if available.
-This is the default Debian Apache configuration.
-When `usedirs` is enabled, one has to set `DirectoryIndex index` for
-the wiki context.
+Add 'Options MultiViews' to the wiki directory's configuration in Apache.
-Setting `DefaultLanguage LL` (replace `LL` with your default MIME
-language code) for the wiki context can help to ensure
-`bla/page/index.en.html` is served as `Content-Language: LL`.
+When `usedirs` is enabled, you should also set `DirectoryIndex index`.
+
+These settings are also recommended, in order to avoid serving up rss files
+as index pages:
+
+ AddType application/rss+xml;qs=0.8 .rss
+ AddType application/atom+xml;qs=0.8 .atom
+
+For details, see [Apache's documentation](http://httpd.apache.org/docs/2.2/content-negotiation.html).
lighttpd
--------
-lighttpd unfortunately does not support content negotiation.
+Recent versions of lighttpd should be able to use
+`$HTTP["language"]` to configure the translated pages to be served.
-**FIXME**: does `mod_magnet` provide the functionality needed to
- emulate this?
+See [Lighttpd Issue](http://redmine.lighttpd.net/issues/show/1119)
+TODO: Example
Usage
=====
@@ -141,43 +155,21 @@ display things only on translatable or translation pages.
The `OTHERLANGUAGES` loop provides ways to display other languages'
versions of the same page, and the translations' status.
-One typically adds the following code to `templates/page.tmpl`:
-
-
-
-
-
- -
- ">
-
- ( %)
-
-
-
-
-
-
-
-
+completeness, expressed in percent, on "slave" pages. It is used by
+the default `templates/page.tmpl`.
Additional PageSpec tests
-------------------------
@@ -207,7 +199,7 @@ enabled, "slave" pages therefore link to the "master" page's
discussion page.
Likewise, "slave" pages are not supposed to have sub-pages;
-[[WikiLinks|wikilink]] that appear on a "slave" page therefore link to
+[[WikiLinks|ikiwiki/wikilink]] that appear on a "slave" page therefore link to
the master page's sub-pages.
Translating
@@ -219,346 +211,39 @@ interface could also be implemented at some point).
If [[tips/untrusted_git_push]] is setup, one can edit the PO files in one's
preferred `$EDITOR`, without needing to be online.
-TODO
-====
-
-Security checks
----------------
-
-### Security history
-
-The only past security issues I could find in GNU gettext and po4a
-are:
-
-- [CVE-2004-0966](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-0966),
- *i.e.* [Debian bug #278283](http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=278283):
- the autopoint and gettextize scripts in the GNU gettext package
- 1.14 and later versions, as used in Trustix Secure Linux 1.5
- through 2.1 and other operating systems, allows local users to
- overwrite files via a symlink attack on temporary files.
-- [CVE-2007-4462](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-4462):
- `lib/Locale/Po4a/Po.pm` in po4a before 0.32 allows local users to
- overwrite arbitrary files via a symlink attack on the
- gettextization.failed.po temporary file.
-
-**FIXME**: check whether this plugin would have been a possible attack
-vector to exploit these vulnerabilities.
-
-Depending on my mood, the lack of found security issues can either
-indicate that there are none, or reveal that no-one ever bothered to
-find (and publish) them.
-
-### PO file features
-
-Can any sort of directives be put in po files that will cause mischief
-(ie, include other files, run commands, crash gettext, whatever)?
-
-> No [documented](http://www.gnu.org/software/gettext/manual/gettext.html#PO-Files)
-> directive is supposed to do so. [[--intrigeri]]
-
-### Running po4a on untrusted content
-
-Are there any security issues on running po4a on untrusted content?
-
-To say the least, this issue is not well covered, at least publicly:
-
-- the documentation does not talk about it;
-- grep'ing the source code for `security` or `trust` gives no answer.
-
-On the other hand, a po4a developer answered my questions in
-a convincing manner, stating that processing untrusted content was not
-an initial goal, and analysing in detail the possible issues.
-
-#### Already checked
-
-- the core (`Po.pm`, `Transtractor.pm`) should be safe
-- po4a source code was fully checked for other potential symlink
- attacks, after discovery of one such issue
-- the only external program run by the core is `diff`, in `Po.pm` (in
- parts of its code we don't use)
-- `Locale::gettext`: only used to display translated error messages
-- Nicolas François "hopes" `DynaLoader` is safe, and has "no reason to
- think that `Encode` is not safe"
-- Nicolas François has "no reason to think that `Encode::Guess` is not
- safe". The po plugin nevertheless avoids using it by defining the
- input charset (`file_in_charset`) before asking `Transtractor` to
- read any file. NB: this hack depends on po4a internals to stay
- the same.
-
-#### To be checked
-
-##### Locale::Po4a modules
-
-The modules we want to use have to be checked, as not all are safe
-(e.g. the LaTeX module's behaviour is changed by commands included in
-the content); they may use regexps generated from the content.
-
-`Chooser.pm` only loads the plugin we tell it too: currently, this
-means the `Text` module only.
-
-`Text` module (I checked the CVS version):
-
-- it does not run any external program
-- only `do_paragraph()` builds regexp's that expand untrusted
- variables; they seem safe to me, but someone more expert than me
- will need to check. Joey?
-
- > Freaky code, but seems ok due to use of `quotementa`.
-
-##### Text::WrapI18N
-
-`Text::WrapI18N` can cause DoS (see the
-[Debian bug #470250](http://bugs.debian.org/470250)), but it is
-optional and we do not need the features it provides.
-
-It is loaded if available by `Locale::Po4a::Common`; looking at the
-code, I'm not sure we can prevent this at all, but maybe some symbol
-table manipulation tricks could work; overriding
-`Locale::Po4a::Common::wrapi18n` may be easier. I'm no expert at all
-in this field. Joey? [[--intrigeri]]
-
-> Update: Nicolas François suggests we add an option to po4a to
-> disable it. It would do the trick, but only for people running
-> a brand new po4a (probably too late for Lenny). Anyway, this option
-> would have to take effect in a `BEGIN` / `eval` that I'm not
-> familiar with. I can learn and do it, in case no Perl wizard
-> volunteers to provide the po4a patch. [[--intrigeri]]
-
->> That doesn't really need to be in a BEGIN. This patch moves it to
->> `import`, and makes this disable wrap18n:
->> `use Locale::Po4a::Common q{nowrapi18n}` --[[Joey]]
-
-
---- /usr/share/perl5/Locale/Po4a/Common.pm 2008-07-21 14:54:52.000000000 -0400
-+++ Common.pm 2008-11-11 18:27:34.000000000 -0500
-@@ -30,8 +30,16 @@
- use strict;
- use warnings;
-
--BEGIN {
-- if (eval { require Text::WrapI18N }) {
-+sub import {
-+ my $class=shift;
-+ my $wrapi18n=1;
-+ if ($_[0] eq 'nowrapi18n') {
-+ shift;
-+ $wrapi18n=0;
-+ }
-+ $class->export_to_level(1, $class, @_);
-+
-+ if ($wrapi18n && eval { require Text::WrapI18N }) {
-
- # Don't bother determining the wrap column if we cannot wrap.
- my $col=$ENV{COLUMNS};
-
-
-##### Term::ReadKey
-
-`Term::ReadKey` is not a hard dependency in our case, *i.e.* po4a
-works nicely without it. But the po4a Debian package recommends
-`libterm-readkey-perl`, so it will probably be installed on most
-systems using the po plugin.
-
-If `$ENV{COLUMNS}` is not set, `Locale::Po4a::Common` uses
-`Term::ReadKey::GetTerminalSize()` to get the terminal size. How safe
-is this?
-
-Part of `Term::ReadKey` is written in C. Depending on the runtime
-platform, this function use ioctl, environment, or C library function
-calls, and may end up running the `resize` command (without
-arguments).
-
-IMHO, using Term::ReadKey has too far reaching implications for us to
-be able to guarantee anything wrt. security. Since it is anyway of no
-use in our case, I suggest we define `ENV{COLUMNS}` before loading
-`Locale::Po4a::Common`, just to be on the safe side. Joey?
-[[--intrigeri]]
-
-> Update: adding an option to disable `Text::WrapI18N`, as Nicolas
-> François suggested, would as a bonus disable `Term::ReadKey`
-> as well. [[--intrigeri]]
-
-### msgmerge
-
-`refreshpofiles()` runs this external program. A po4a developer
-answered he does "not expect any security issues from it".
-
-### Fuzzing input
-
-I was not able to find any public information about gettext or po4a
-having been tested with a fuzzing program, such as `zzuf` or `fusil`.
-Moreover, some gettext parsers seem to be quite
-[easy to crash](http://fusil.hachoir.org/trac/browser/trunk/fuzzers/fusil-gettext),
-so it might be useful to bang msgmerge/po4a's heads against such
-a program in order to easily detect some of the most obvious DoS.
-[[--intrigeri]]
-
-> po4a was not fuzzy-tested, but according to one of its developers,
-> "it would be really appreciated". [[--intrigeri]]
-
-Test conditions:
-
-- a 21M file containing 100 concatenated copies of all the files in my
- `/usr/share/common-licenses/`; I had no existing PO file or
- translated versions at hand, which renders these tests
- quite incomplete.
-- po4a was the Debian 0.34-2 package; the same tests were also run
- after replacing the `Text` module with the CVS one (the core was not
- changed in CVS since 0.34-2 was released), without any significant
- difference in the results.
-- Perl 5.10.0-16
-
-#### po4a-gettextize
-
-`po4a-gettextize` uses more or less the same po4a features as our
-`refreshpot` function.
-
-Without specifying an input charset, zzuf'ed `po4a-gettextize` quickly
-errors out, complaining it was not able to detect the input charset;
-it leaves no incomplete file on disk.
-
-So I had to pretend the input was in UTF-8, as does the po plugin.
-
-Two ways of crashing were revealed by this command-line:
-
- zzuf -vc -s 0:100 -r 0.1:0.5 \
- po4a-gettextize -f text -o markdown -M utf-8 -L utf-8 \
- -m LICENSES >/dev/null
-
-They are:
-
- Malformed UTF-8 character (UTF-16 surrogate 0xdcc9) in substitution iterator at /usr/share/perl5/Locale/Po4a/Po.pm line 1443.
- Malformed UTF-8 character (fatal) at /usr/share/perl5/Locale/Po4a/Po.pm line 1443.
-
-and
-
- Malformed UTF-8 character (UTF-16 surrogate 0xdcec) in substitution (s///) at /usr/share/perl5/Locale/Po4a/Po.pm line 1443.
- Malformed UTF-8 character (fatal) at /usr/share/perl5/Locale/Po4a/Po.pm line 1443.
-
-Perl seems to exit cleanly, and an incomplete PO file is written on
-disk. I not sure whether if this is a bug in Perl or in `Po.pm`.
-
-> It's fairly standard perl behavior when fed malformed utf-8. As long as it doesn't
-> crash ikiwiki, it's probably acceptable. Ikiwiki can do some similar things itself when fed malformed utf-8 (doesn't crash tho) --[[Joey]]
-
-#### po4a-translate
-
-`po4a-translate` uses more or less the same po4a features as our
-`filter` function.
-
-Without specifying an input charset, same behaviour as
-`po4a-gettextize`, so let's specify UTF-8 as input charset as of now.
-
- zzuf -cv \
- po4a-translate -d -f text -o markdown -M utf-8 -L utf-8 \
- -k 0 -m LICENSES -p LICENSES.fr.po -l test.fr
-
-... prints tons of occurences of the following error, but a complete
-translated document is written (obviously with some weird chars
-inside):
-
- Use of uninitialized value in string ne at /usr/share/perl5/Locale/Po4a/TransTractor.pm line 854.
- Use of uninitialized value in string ne at /usr/share/perl5/Locale/Po4a/TransTractor.pm line 840.
- Use of uninitialized value in pattern match (m//) at /usr/share/perl5/Locale/Po4a/Po.pm line 1002.
-
-While:
-
- zzuf -cv -s 0:10 -r 0.001:0.3 \
- po4a-translate -d -f text -o markdown -M utf-8 -L utf-8 \
- -k 0 -m LICENSES -p LICENSES.fr.po -l test.fr
-
-... seems to lose the fight, at the `readpo(LICENSES.fr.po)` step,
-against some kind of infinite loop, deadlock, or any similar beast.
-It does not seem to eat memory, though.
-
-Whatever format module is used does not change anything. This is thus
-probably a bug in po4a's core or in a lib it depends on.
-
-The sub `read`, in `TransTractor.pm`, seems to be a good debugging
-starting point.
-
-#### msgmerge
-
-`msgmerge` is run in our `refreshpofiles` function. I did not manage
-to crash it with `zzuf`.
-
-gettext/po4a rough corners
---------------------------
-
-- fix infinite loop when synchronizing two ikiwiki (when checkouts
- live in different directories): say bla.fr.po has been updated in
- repo2; pulling repo2 from repo1 seems to trigger a PO update, that
- changes bla.fr.po in repo1; then pushing repo1 to repo2 triggers
- a PO update, that changes bla.fr.po in repo2; etc.; quickly fixed in
- `629968fc89bced6727981c0a1138072631751fee`, by disabling references
- in Pot files. Using `Locale::Po4a::write_if_needed` might be
- a cleaner solution. (warning: this function runs the external
- `diff` program, have to check security)
-- new translations created in the web interface must get proper
- charset/encoding gettext metadata, else the next automatic PO update
- removes any non-ascii chars; possible solution: put such metadata
- into the Pot file, and let it propagate; should be fixed in
- `773de05a7a1ee68d2bed173367cf5e716884945a`, time will tell.
-
-Better links
-------------
-
-### Page title in links
-
-To use the page titles set with the [[meta|plugins/meta]] plugin when
-rendering links would be very much nicer, than the current
-"filename.LL" format. This is actually a duplicate for
-[[bugs/pagetitle_function_does_not_respect_meta_titles]].
-
-Going to work on this in my `meta` branch.
-
-### Translation status in links
-
-See [[contrib/po]].
-
-### Backlinks
-
-They are not updated when the source page changes (e.g. meta title).
-
-Page formats
-------------
-
-Markdown is well supported, great, but what about others?
-
-The [[po|plugins/po]] uses `Locale::Po4a::Text` for every page format;
-this can be expected to work out of the box with most other wiki-like
-formats supported by ikiwiki. Some of their ad-hoc syntax might be
-parsed in a strange way, but the worst problems I can imagine would be
-wrapping issues; e.g. there is code in po4a dedicated to prevent
-re-wrapping the underlined Markdown headers.
-
-While it would be easy to better support formats such as [[html]] or
-LaTeX, by using for each one the dedicated po4a module, this can be
-problematic from a security point of view.
+Markup languages support
+------------------------
-**TODO**: test the more popular formats and write proper documentation
-about it.
+[[Markdown|mdwn]] and [[html]] are well supported. Some other markup
+languages supported by ikiwiki mostly work, but some pieces of syntax
+are not rendered correctly on the slave pages:
-Translation quality assurance
------------------------------
+* [[reStructuredText|rst]]: anonymous hyperlinks and internal
+ cross-references
+* [[wikitext]]: conversion of newlines to paragraphs
+* [[creole]]: verbatim text is wrapped, tables are broken
+* LaTeX: not supported yet; the dedicated po4a module
+ could be used to support it, but it would need a security audit
+* other markup languages have not been tested.
-Modifying a PO file via the CGI must be forbidden if the new version
-is not a valid PO file. As a bonus, check that it provides a more
-complete translation than the existing one.
+Security
+========
-A new `cansave` type of hook would be needed to implement this.
+[[po/discussion]] contains a detailed security analysis of this plugin
+and its dependencies.
-Note: committing to the underlying repository is a way to bypass
-this check.
+When using po4a older than 0.35, it is recommended to uninstall
+`Text::WrapI18N` (Debian package `libtext-wrapi18n-perl`), in order to
+avoid a potential denial of service.
-Creating new pages on the web
------------------------------
+BUGS
+====
-See [[contrib/po]].
+[[!inline pages="bugs/po:* and !bugs/done and !link(bugs/done) and !bugs/*/*"
+feeds=no actions=no archive=yes show=0]]
-Documentation
--------------
+TODO
+====
-Maybe write separate documentation depending on the people it targets:
-translators, wiki administrators, hackers. This plugin may be complex
-enough to deserve this.
+[[!inline pages="todo/po:* and !todo/done and !link(todo/done) and !todo/*/*"
+feeds=no actions=no archive=yes show=0]]