X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/a0deb3038c45c066e2c0c3acb8c6c4a93ca3301d..44bb872a9705781e20c1b7af89297240523d6bb9:/doc/plugins/po.mdwn?ds=inline diff --git a/doc/plugins/po.mdwn b/doc/plugins/po.mdwn index c83d5a612..e88cc3106 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 +129,9 @@ Usage Templates --------- +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' @@ -163,104 +167,224 @@ The following variables are available inside the loop (for every page in): The `PERCENTTRANSLATED` variable is set to the translation completeness, expressed in percent, on "slave" pages. +One can use it this way: + + +
+ +
+ + 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 and the PO files for the supported 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. -TODO -==== +Discussion 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. -OTHERLANGUAGES dependencies ---------------------------- +Translating +----------- -Pages using `OTHERLANGUAGES` depend on any "master" and "slave" pages -whose status is being displayed. It is supposed to trigger dependency -loops, but no practical bugs were noticed yet. +One can edit the PO files using ikiwiki's CGI (a message-by-message +interface could also be implemented at some point). -Should pages using the `OTHERLANGUAGES` template loop be declared as -linking to the same page in other versions? To be rigorous, they -should, but this may clutter the backlinks. +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 --------------- -- `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 -gettext/po4a rough corners --------------------------- +The only past security issues I could find in GNU gettext and po4a +are: -- fix the duplicated PO header mysterious bug -- fix the "duplicate message definition" error when updating a PO - file; do PO files need normalizing? (may be a side effect of - previous bug) +- [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. -Translation quality assurance ------------------------------ +**FIXME**: check whether this plugin would have been a possible attack +vector to exploit these vulnerabilities. -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. +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. -A new `cansave` type of hook would be needed to implement this. +### PO file features -Note: committing to the underlying repository is a way to bypass -this check. +Can any sort of directives be put in po files that will cause mischief +(ie, include other files, run commands, crash gettext, whatever)? -Translating online ------------------- +> 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 -As PO is a wiki page type, we already have an online PO editor, that -is ikiwiki's CGI. +- 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. -A message-by-message interface could also be implemented at some -point; a nice way to do offline translation work (without VCS access) -still has to be offered, though. +#### To be checked -Translating offline without VCS access --------------------------------------- +##### Locale::Po4a modules -The following workflow should be made possible for translators without -VCS access who need to edit the PO files in another editor than a web -browser: +- 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` -- download the page's PO file -- use any PO editor to update the translation -- upload the updated PO file +##### Text::WrapI18N -Implementation note: a generic mechanism to upload a page's source is -needed: it's only an alternative way to allow saving a the modified -page's source with the CGI. +`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. -### Short-term workflow +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]] -A possible workaround is: +##### Term::ReadKey -- pretend to edit the PO file online -- copy the PO file content from the textarea -- cancel the edit -- paste the content into a local file. -- edit the local file in any PO editor -- pretend to edit the PO file online -- paste the modified local file's content into the edit textarea -- save +`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]] + +### 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]] + +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. + +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.