X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/44bb872a9705781e20c1b7af89297240523d6bb9..44ce9563a328ecb3b5fa8fd97afa30c3033fca76:/doc/plugins/po.mdwn diff --git a/doc/plugins/po.mdwn b/doc/plugins/po.mdwn index e88cc3106..04420c115 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 ============= @@ -47,7 +55,7 @@ Supported languages languages, such as: po_slave_languages => { 'fr' => 'Français', - 'es' => 'Castellano', + 'es' => 'Español', 'de' => 'Deutsch', } @@ -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 ============== @@ -105,7 +114,8 @@ 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. + +Add 'Options MultiViews' to the wiki directory's configuration in Apache. When `usedirs` is enabled, one has to set `DirectoryIndex index` for the wiki context. @@ -114,6 +124,8 @@ 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`. +For details, see [Apache's documentation](http://httpd.apache.org/docs/2.2/content-negotiation.html). + lighttpd -------- @@ -129,6 +141,10 @@ 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. @@ -137,43 +153,21 @@ 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`: - - -
- -
- - -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 +An example of its use can be found in the default +`templates/page.tmpl`. In case you want to customize it, 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: - - -
- -
- +completeness, expressed in percent, on "slave" pages. It is used by +the default `templates/page.tmpl`. Additional PageSpec tests ------------------------- @@ -194,14 +188,18 @@ 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 ----------------- +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 ----------- @@ -211,180 +209,123 @@ 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 +Markup languages support +------------------------ -The only past security issues I could find in GNU gettext and po4a -are: +[[Markdown|mdwn]] 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: -- [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. +* [[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. -**FIXME**: check whether this plugin would have been a possible attack -vector to exploit these vulnerabilities. +Security +======== -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/discussion]] contains a detailed security analysis of this plugin +and its dependencies. -### PO file features +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. -Can any sort of directives be put in po files that will cause mischief -(ie, include other files, run commands, crash gettext, whatever)? +TODO +==== -> No [documented](http://www.gnu.org/software/gettext/manual/gettext.html#PO-Files) -> directive is supposed to do so. [[--intrigeri]] +Better links +------------ -### Running po4a on untrusted content +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. -Are there any security issues on running po4a on untrusted content? +An integration branch, called `meta-po`, merges [[intrigeri]]'s `po` +and `meta` branches, and thus has this additional features. -To say the least, this issue is not well covered, at least publicly: +Language display order +---------------------- -- the documentation does not talk about it; -- grep'ing the source code for `security` or `trust` gives no answer. +Jonas pointed out that one might want to control the order that links to +other languages are listed, for various reasons. Currently, there is no +order, as `po_slave_languages` is a hash. It would need to be converted +to an array to support this. (If twere done, twere best done quickly.) +--[[Joey]] -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. +Pagespecs +--------- -#### Already checked +I was suprised that, when using the map directive, a pagespec of "*" +listed all the translated pages as well as regular pages. That can +make a big difference to an existing wiki when po is turned on, +and seems generally not wanted. +(OTOH, you do want to match translated pages by +default when locking pages.) --[[Joey]] -- 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. +Edit links on untranslated pages +-------------------------------- -#### To be checked +If a page is not translated yet, the "translated" version of it +displays wikilinks to other, existing (but not yet translated?) +pages as edit links, as if those pages do not exist. -##### Locale::Po4a modules +That's really confusing, especially as clicking such a link +brings up an edit form to create a new, english page. -- 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; we - currently only use the `Text` module -- the `Text` module does not run any external program -- check that no module is loaded by `Chooser.pm`, when we tell it to - load the `Text` one -- `nsgmls` is used by `Sgml.pm` +This is with po_link_to=current or negotiated. With default, it doesn't +happen.. -##### Text::WrapI18N +Also, this may only happen if the page being linked to is coming from an +underlay, and the underlays lack translation to a given language. +--[[Joey]] -`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. +Double commits of po files +-------------------------- -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]] +When adding a new english page, the po files are created, committed, +and then committed again. The second commit makes this change: -##### Term::ReadKey + -"Content-Type: text/plain; charset=utf-8\n" + -"Content-Transfer-Encoding: ENCODING" + +"Content-Type: text/plain; charset=UTF-8\n" + +"Content-Transfer-Encoding: ENCODING\n" -`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. +Same thing happens when a change to an existing page triggers a po file +update. --[[Joey]] -If `$ENV{COLUMNS}` is not set, `Locale::Po4a::Common` uses -`Term::ReadKey::GetTerminalSize()` to get the terminal size. How safe -is this? +Ugly messages with empty files +------------------------------ -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). +If there are empty .mdwn files, the po plugin displays some ugly messages. -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]] - -### msgmerge +Translation of directives +------------------------- -`refreshpofiles()` runs this external program. A po4a developer -answered he does "not expect any security issues from it". +If a translated page contains a directive, it may expand to some english +text, or text in whatever single language ikiwiki is configured to "speak". -### Fuzzing input +Maybe there could be a way to switch ikiwiki to speaking another language +when building a non-english page? Then the directives would get translated. -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]] +2 test suite failures +-------------------- -> po4a was not fuzzy-tested, but according to one of its developers, -> "it would be really appreciated". [[--intrigeri]] +t/po is currently failing tests 57 and 59 (and I would like to release +soon..) --[[Joey]] -gettext/po4a rough corners --------------------------- +Documentation +------------- -- 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. - -Misc. improvements ------------------- - -### page titles - -Use nice page titles from meta plugin in links, as inline already -does. This is actually a duplicate for -[[bugs/pagetitle_function_does_not_respect_meta_titles]], which might -be fixed by something like [[todo/using_meta_titles_for_parentlinks]]. - -### source files format - -Markdown is supported, great, but what about others? The set of file -formats supported both in ikiwiki and po4a probably is greater than -`{markdown}`. Warning: the po4a modules are the place where one can -expect security issues. - -Translation quality assurance ------------------------------ - -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. - -A new `cansave` type of hook would be needed to implement this. - -Note: committing to the underlying repository is a way to bypass -this check. +Maybe write separate documentation depending on the people it targets: +translators, wiki administrators, hackers. This plugin may be complex +enough to deserve this.