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-rw-r--r--doc/plugins/po.mdwn316
-rw-r--r--doc/plugins/po/security.mdwn206
-rw-r--r--doc/plugins/write.mdwn50
3 files changed, 567 insertions, 5 deletions
diff --git a/doc/plugins/po.mdwn b/doc/plugins/po.mdwn
new file mode 100644
index 000000000..756012890
--- /dev/null
+++ b/doc/plugins/po.mdwn
@@ -0,0 +1,316 @@
+[[!template id=plugin name=po core=0 author="[[intrigeri]]"]]
+[[!tag type/format]]
+
+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]]
+
+Introduction
+============
+
+A language is chosen as the "master" one, and any other supported
+language is a "slave" one.
+
+A page written in the "master" language is a "master" page. It can be
+of any page type supported by ikiwiki, except `po`. It does not have to be
+named a special way: migration to this plugin does not imply any page
+renaming work.
+
+Example: `bla/page.mdwn` is a "master" Markdown page written in
+English; if `usedirs` is enabled, it is rendered as
+`bla/page/index.en.html`, else as `bla/page.en.html`.
+
+Any translation of a "master" page into a "slave" language is called
+a "slave" page; it is written in the gettext PO format. `po` is now
+a page type supported by ikiwiki.
+
+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
+=============
+
+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_slave_languages` is used to set the list of supported "slave"
+languages, such as:
+
+ po_slave_languages => { 'fr' => 'Français',
+ 'es' => 'Castellano',
+ 'de' => 'Deutsch',
+ }
+
+Decide which pages are translatable
+-----------------------------------
+
+The `po_translatable_pages` setting configures what pages are
+translatable. It is a [[ikiwiki/PageSpec]], so you have lots of
+control over what kind of pages are translatable.
+
+The `.po` files are not considered as being translatable, so you don't need to
+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
+
+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
+
+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
+
+#### 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`
+ to `negotiated`; this option combination is neither implemented
+ nor allowed.
+* if the web server does not support Content Negotiation, setting
+ `po_link_to` to `negotiated` will produce a unusable website.
+
+Server support
+==============
+
+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.
+
+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`.
+
+lighttpd
+--------
+
+lighttpd unfortunately does not support content negotiation.
+
+**FIXME**: does `mod_magnet` provide the functionality needed to
+ emulate this?
+
+
+Usage
+=====
+
+Templates
+---------
+
+When `po_link_to` is not set to `negotiated`, one should replace some
+occurrences of `BASEURL` with `HOMEPAGEURL` to get correct links to
+the wiki homepage.
+
+The `ISTRANSLATION` and `ISTRANSLATABLE` variables can be used to
+display things only on translatable or translation pages.
+
+### Display page's versions in other languages
+
+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`:
+
+ <TMPL_IF NAME="OTHERLANGUAGES">
+ <div id="otherlanguages">
+ <ul>
+ <TMPL_LOOP NAME="OTHERLANGUAGES">
+ <li>
+ <a href="<TMPL_VAR NAME="URL">"><TMPL_VAR NAME="LANGUAGE"></a>
+ <TMPL_UNLESS NAME="MASTER">
+ (<TMPL_VAR NAME="PERCENT">&nbsp;%)
+ </TMPL_UNLESS>
+ </li>
+ </TMPL_LOOP>
+ </ul>
+ </div>
+ </TMPL_IF>
+
+The following variables are available inside the loop (for every page in):
+
+* `URL` - url to the page
+* `CODE` - two-letters language code
+* `LANGUAGE` - language name (as defined in `po_slave_languages`)
+* `MASTER` - is true (1) if, and only if the page is a "master" page
+* `PERCENT` - for "slave" pages, is set to the translation completeness, in percents
+
+### Display the current translation status
+
+The `PERCENTTRANSLATED` variable is set to the translation
+completeness, expressed in percent, on "slave" pages.
+
+One can use it this way:
+
+ <TMPL_IF NAME="ISTRANSLATION">
+ <div id="percenttranslated">
+ <TMPL_VAR NAME="PERCENTTRANSLATED">
+ </div>
+ </TMPL_IF>
+
+Additional PageSpec tests
+-------------------------
+
+This plugin enhances the regular [[ikiwiki/PageSpec]] syntax with some
+additional tests that are documented [[here|ikiwiki/pagespec/po]].
+
+Automatic PO file update
+------------------------
+
+Committing changes to a "master" page:
+
+1. updates the POT file and the PO files for the "slave" languages;
+ the updated PO files are then put under version control;
+2. triggers a refresh of the corresponding HTML slave pages.
+
+Also, when the plugin has just been enabled, or when a page has just
+been declared as being translatable, the needed POT and PO files are
+created, and the PO files are checked into version control.
+
+Discussion pages and other sub-pages
+------------------------------------
+
+Discussion should happen in the language in which the pages are
+written for real, *i.e.* the "master" one. If discussion pages are
+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
+the master page's sub-pages.
+
+Translating
+-----------
+
+One can edit the PO files using ikiwiki's CGI (a message-by-message
+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.
+
+Markup languages support
+------------------------
+
+Markdown is well supported. Some other markup languages supported by
+ikiwiki mostly work, but some pieces of syntax are not rendered
+correctly on the slave pages:
+
+* [[reStructuredText|rst]]: anonymous hyperlinks and internal
+ cross-references
+* [[wikitext]]: conversion of newlines to paragraphs
+* [[creole]]: verbatim text is wrapped, tables are broken
+* [[html]] and LaTeX: not supported yet; the dedicated po4a modules
+ could be used to support them, but they would need a security audit
+* other markup languages have not been tested.
+
+Security
+========
+
+[[./security]] contains a detailed security analysis of this plugin
+and its dependencies.
+
+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.
+
+TODO
+====
+
+Better links
+------------
+
+Once the fix to
+[[bugs/pagetitle_function_does_not_respect_meta_titles]] from
+[[intrigeri]]'s `meta` branch is merged into ikiwiki upstream, the
+generated links' text will be optionally based on the page titles set
+with the [[meta|plugins/meta]] plugin, and will thus be translatable.
+It will also allow displaying the translation status in links to slave
+pages. Both were implemented, and reverted in commit
+ea753782b222bf4ba2fb4683b6363afdd9055b64, which should be reverted
+once [[intrigeri]]'s `meta` branch is merged.
+
+An integration branch, called `meta-po`, merges [[intrigeri]]'s `po`
+and `meta` branches, and thus has thise additional features.
+
+Robustness tests
+----------------
+
+### Enabling/disabling the plugin
+
+* enabling the plugin with `po_translatable_pages` set to blacklist: **OK**
+* enabling the plugin with `po_translatable_pages` set to whitelist: **OK**
+* enabling the plugin without `po_translatable_pages` set: **OK**
+* disabling the plugin: **OK**
+
+### Changing the plugin config
+
+* adding existing pages to `po_translatable_pages`: **OK**
+* removing existing pages from `po_translatable_pages`: **OK**
+* adding a language to `po_slave_languages`: **OK**
+* removing a language from `po_slave_languages`: **OK**
+* changing `po_master_language`: **OK**
+* replacing `po_master_language` with a language previously part of
+ `po_slave_languages`: needs two rebuilds, but **OK** (this is quite
+ a perverse test actually)
+
+### Creating/deleting/renaming pages
+
+All cases of master/slave page creation/deletion/rename, both via RCS
+and via CGI, have been tested.
+
+### Misc
+
+* general test with `usedirs` disabled: **OK**
+* general test with `indexpages` enabled: **not OK**
+* general test with `po_link_to=default` with `userdirs` enabled: **OK**
+* general test with `po_link_to=default` with `userdirs` disabled: **OK**
+
+Misc. bugs
+----------
+
+Documentation
+-------------
+
+Maybe write separate documentation depending on the people it targets:
+translators, wiki administrators, hackers. This plugin may be complex
+enough to deserve this.
diff --git a/doc/plugins/po/security.mdwn b/doc/plugins/po/security.mdwn
new file mode 100644
index 000000000..d1bbf6c05
--- /dev/null
+++ b/doc/plugins/po/security.mdwn
@@ -0,0 +1,206 @@
+[[!toc levels=2]]
+
+----
+
+# Probable holes
+
+_(The list of things to fix.)_
+
+## po4a-gettextize
+
+* po4a CVS 2009-01-16
+* Perl 5.10.0
+
+`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. I therefore had to pretend the
+input was in UTF-8, as does the po plugin.
+
+ zzuf -c -s 13 -r 0.1 \
+ po4a-gettextize -f text -o markdown -M utf-8 -L utf-8 \
+ -m GPL-3 -p GPL-3.pot
+
+Crashes with:
+
+ Malformed UTF-8 character (UTF-16 surrogate 0xdfa4) in substitution
+ iterator at /usr/share/perl5/Locale/Po4a/Po.pm line 1449.
+ Malformed UTF-8 character (fatal) at /usr/share/perl5/Locale/Po4a/Po.pm
+ line 1449.
+
+An incomplete pot file is left on disk. Unfortunately Po.pm tells us
+nothing about the place where the crash happens.
+
+> 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]]
+
+----
+
+# Potential gotchas
+
+_(Things not to do.)_
+
+
+## Blindly activating more po4a format modules
+
+The format 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.
+
+----
+
+# Hopefully non-holes
+
+_(AKA, the assumptions that will be the root of most security holes...)_
+
+## PO file features
+
+No [documented](http://www.gnu.org/software/gettext/manual/gettext.html#PO-Files)
+directive that can be put in po files is supposed to cause mischief
+(ie, include other files, run commands, crash gettext, whatever).
+
+## gettext
+
+### Security history
+
+The only past security issue I could find in GNU gettext is
+[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) may allow local users to overwrite files via
+a symlink attack on temporary files.
+
+This plugin would not have allowed to exploit this bug, as it does not
+use, either directly or indirectly, the faulty scripts.
+
+Note: the lack of found security issues can either indicate that there
+are none, or reveal that no-one ever bothered to find or publish them.
+
+### msgmerge
+
+`refreshpofiles()` runs this external program.
+
+* I was not able to crash it with `zzuf`.
+* I could not find any past security hole.
+
+### msgfmt
+
+`isvalidpo()` runs this external program.
+
+* I was not able to make it behave badly using zzuf: it exits cleanly
+ when too many errors are detected.
+* I could not find any past security hole.
+
+## po4a
+
+### Security history
+
+The only past security issue I could find in po4a is
+[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 allowed local users to
+overwrite arbitrary files via a symlink attack on the
+gettextization.failed.po temporary file.
+
+This plugin would not have allowed to exploit this bug, as it does not
+use, either directly or indirectly, the faulty `gettextize` function.
+
+Note: the lack of found security issues can either indicate that there
+are none, or reveal that no-one ever bothered to find or publish them.
+
+### General feeling
+
+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.
+The following analysis was done with his help.
+
+### Details
+
+* 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` is 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.
+
+#### Locale::Po4a::Text
+
+* does not run any external program
+* only `do_paragraph()` builds regexp's that expand untrusted
+ variables; according to [[Joey]], this is "Freaky code, but seems ok
+ due to use of `quotementa`".
+
+#### Text::WrapI18N
+
+`Text::WrapI18N` can cause DoS
+([Debian bug #470250](http://bugs.debian.org/470250)).
+It is optional, and we do not need the features it provides.
+
+If a recent enough po4a (>=0.35) is installed, this module's use is
+fully disabled. Else, the wiki administrator is warned about this
+at runtime.
+
+#### 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.
+
+`Term::ReadKey` has too far reaching implications for us to
+be able to guarantee anything wrt. security.
+
+If a recent enough po4a (>=2009-01-15 CVS, which will probably be
+released as 0.35) is installed, this module's use is fully disabled.
+
+#### Fuzzing input
+
+##### po4a-translate
+
+* po4a CVS 2009-01-16
+* Perl 5.10.0
+
+`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.
+
+`LICENSES` is a 21M file containing 100 concatenated copies of all the
+files in `/usr/share/common-licenses/`; I had no existing PO file or
+translated versions at hand, which renders these tests
+quite incomplete.
+
+ 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.
+
+The root of this bug lies in `Text::WrapI18N`, see the corresponding
+section.
+
+
+----
+
+# Fixed holes
+
diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 696bc6bc3..cccfb9bba 100644
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -326,6 +326,26 @@ This hook should avoid directly redirecting the user to a signin page,
since it's sometimes used to test to see which pages in a set of pages a
user can edit.
+### canremove
+
+ hook(type => "canremove", id => "foo", call => \&canremove);
+
+This hook can be used to implement arbitrary access methods to control
+when a page can be removed using the web interface (commits from
+revision control bypass it). It works exactly like the `canedit` hook,
+but is passed the named parameters `cgi` (a CGI object), `session`
+(a session object) and `page` (the page subject to deletion).
+
+### canrename
+
+ hook(type => "canrename", id => "foo", call => \&canrename);
+
+This hook can be used to implement arbitrary access methods to control when
+a page can be renamed using the web interface (commits from revision control
+bypass it). It works exactly like the `canedit` hook,
+but is passed the named parameters `cgi` (a CGI object), `session` (a
+session object), `src`, `srcfile`, `dest` and `destfile`.
+
### checkcontent
hook(type => "checkcontent", id => "foo", call => \&checkcontent);
@@ -338,8 +358,9 @@ the content the user has entered is a comment, it may also be passed some
additional parameters: `author`, `url`, and `subject`. The `subject`
parameter may also be filled with the user's comment about the change.
-Note: When the user edits an existing wiki page, the passed `content` will
-include only the lines that they added to the page, or modified.
+Note: When the user edits an existing wiki page, this hook is also
+passed a `diff` named parameter, which will include only the lines
+that they added to the page, or modified.
The hook should return `undef` on success. If the content is disallowed, it
should return a message stating what the problem is, or a function
@@ -390,9 +411,28 @@ they're saved, etc.
hook(type => "renamepage", id => "foo", call => \&renamepage);
This hook is called by the [[plugins/rename]] plugin when it renames
-something. The hook is passed named parameters: `page`, `oldpage`,
-`newpage`, and `content`, and should try to modify the content to reflect
-the name change. For example, by converting links to point to the new page.
+something, once per page linking to the renamed page's old location.
+The hook is passed named parameters: `page`, `oldpage`, `newpage`, and
+`content`, and should try to modify the content of `page` to reflect
+the name change. For example, by converting links to point to the
+new page.
+
+### rename
+
+ hook(type => "rename", id => "foo", call => \&rename);
+
+When a page or set of pages is renamed, the referenced function is
+called for every page, and is passed named parameters:
+
+* `torename`: a reference to a hash with keys: `src`, `srcfile`,
+ `dest`, `destfile`, `required`.
+* `cgi`: a CGI object
+* `session`: a session object.
+
+Such a hook function returns any additional rename hashes it wants to
+add. This hook is applied recursively to returned additional rename
+hashes, so that it handles the case where two plugins use the hook:
+plugin A would see when plugin B adds a new file to be renamed.
### getsetup