X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/bd2dd8c60336ad7a03194d2a53f5409a620e484d..741b26aa176b34d0359a2b89dd6d8293fcdf2b3d:/doc/plugins/po.mdwn diff --git a/doc/plugins/po.mdwn b/doc/plugins/po.mdwn index f9cd0ff03..919864ede 100644 --- a/doc/plugins/po.mdwn +++ b/doc/plugins/po.mdwn @@ -6,6 +6,8 @@ gettext, using [po4a](http://po4a.alioth.debian.org/). It depends on the Perl `Locale::Po4a::Po` library (`apt-get install po4a`). +[[!toc levels=2]] + Introduction ============ @@ -13,7 +15,7 @@ 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, but PO. It does not have to 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. @@ -22,7 +24,7 @@ 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 "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 @@ -56,9 +58,8 @@ 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 translations files are anyway not considered as being -translatable, so you don't need to worry about excluding them -explicitly from this [[ikiwiki/PageSpec]]. +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 -------------- @@ -128,6 +129,10 @@ 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. @@ -180,38 +185,55 @@ Additional PageSpec tests This plugin enhances the regular [[ikiwiki/PageSpec]] syntax with some additional tests that are documented [[here|ikiwiki/pagespec/po]]. -Automatic PO files update -------------------------- +Automatic PO file update +------------------------ Committing changes to a "master" page: -1. updates the POT file, as well as the PO files for the "slave" - languages (this is done in the `needsbuild` hook); the updated PO - files are then put under version control; -2. triggers a refresh of the corresponding HTML slave pages (this is - achieved by making any "slave" page dependent on the corresponding - "master" page, in the `needsbuild` hook). +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 ----------------- +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 -her preferred `$EDITOR`, without needing to be online. +If [[tips/untrusted_git_push]] is setup, one can edit the PO files in one's +preferred `$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. + TODO ==== @@ -219,10 +241,262 @@ TODO Security checks --------------- -- `refreshpofiles` uses `system()`, whose args have to be checked more - thoroughly to prevent any security issue (command injection, etc.). -- `refreshpofiles` and `refreshpot` create new files; this may need - some checks, e.g. using `IkiWiki::prep_writefile()` +### 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 -------------------------- @@ -231,36 +505,27 @@ gettext/po4a rough corners 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.; fixed in - `629968fc89bced6727981c0a1138072631751fee`? + 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 ------------------- +Better links +------------ -### page titles +### Page title in links -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]]. - -### websetup - -Which configuration settings are safe enough for websetup? - -### backlinks - -`po_link_to = negotiated`: if a given translatable `sourcepage.mdwn` -links to \[[destpage]], `sourcepage.LL.po` also link to \[[destpage]], -and the latter has the master page *and* all its translations listed -in the backlinks. - -`po_link_to = current`: seems to work nicely +Using the fix to +[[bugs/pagetitle_function_does_not_respect_meta_titles]] from +[[intrigeri]]'s `meta` branch, the generated links' text is based on +the page titles set with the [[meta|plugins/meta]] plugin. This has to +be merged upstream, though. Translation quality assurance ----------------------------- @@ -273,3 +538,69 @@ 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. + +Creating new pages on the web +----------------------------- + +See [[contrib/po|contrib/po]]. + +Renaming/deleting pages +----------------------- + +Renaming or deleting a translation in the CGI should be forbidden. +Implementing this requires two new hooks: `canrename` and `canremove`, +that would be run respectively by the `rename` and the `remove` plugins. + +Robustness tests +---------------- + +### Disabling the plugin + +- enabling the plugin with `po_translatable_pages` set +- 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 pages + +- creating a master page via RCS: **OK** +- creating a master page via CGI: **OK** + +### Deleting pages + +- removing a master page via RCS: **OK** +- removing a translation via RCS: **OK** +- removing a master page via CGI: **OK** +- removing a translation via CGI: **OK** + +### Renaming pages + +- renaming a master page via RCS: **OK** (but the old translations + are lost, because not all RCS track file renaming) +- renaming a master page and its translations via RCS: **OK** +- renaming a master page via CGI: **OK** +- renaming a translation via RCS +- renaming a translation via CGI + +### Misc + +- general test with `usedirs` disabled: **OK** +- general test with `indexpages` enabled +- general test with `po_link_to=default` + +Documentation +------------- + +Maybe write separate documentation depending on the people it targets: +translators, wiki administrators, hackers. This plugin may be complex +enough to deserve this.