server parsed html files), then if you let anyone else add files to the wiki,
they can try to use this to exploit your web server.
-## symlink attacks
+## multiple accessors of wiki directory
-Could a committer trick ikiwiki into following a symlink and operating on
-some other tree that it shouldn't? svn supports symlinks, so one can get
-into the repo. ikiwiki uses File::Find to traverse the repo, and does not
-tell it to follow symlinks, but it might be possible to race replacing a
-directory with a symlink and trick it into following.
+If multiple people can write to the source directory ikiwiki is using, or to the destination directory it writes files to, then one can cause trouble for the other when they run ikiwiki through symlink attacks.
-It would certianly be possible to start out with a directory, let ikiwiki
-run and find a file in there, then replace it with a symlink, and ikiwiki
-would then go ahead and follow the symlink when it went to open that file
-to read it. If it was some private file and was running suid, that could be
-bad.
+So it's best if only one person can ever write to those directories.
-TODO: seems that locking to prevent more than one ikiwiki run at a time
-would both fix this and is a good idea in general. With locking, an
-attacker couldn't get ikiwiki to svn up while another instance was running.
+## setup files
-## multiple accessors of wiki source directory
+Setup files are not safe to keep in subversion with the rest of the wiki.
+Just don't do it. [[ikiwiki.setup]] is *not* used as the setup file for
+this wiki, BTW.
-If multiple people can write to the source directory ikiwiki is using, then
-one can cause trouble for the other when they run ikiwiki through symlink
-attacks.
+## svn commit logs
-So it's best if only one person can ever write to the checkout that ikiwiki
-compiles the wiki from.
+Anyone with svn commit access can forge "web commit from foo" and make it appeat on [[RecentChanges]] like foo committed. One way to avoid this would be to limit web commits to those done by a certian user.
-## webserver symlink attacks
+It's actually possible to force a whole series of svn commits to appear to have come just before yours, by forging svn log output. This could be guarded against somewhat by revision number scanning, since the forged revisions would duplicate the numbers of unforged ones. Or subversion could fix svn log to indent commit messages, which would make such forgery impossible..
-If someone checks in a symlink to /etc/passwd, ikiwiki would publish that.
-To aoid this, ikiwiki will need to avoid reading files that are symlinks.
-TODO and note discussion of races above.
+ikiwiki escapes any html in svn commit logs to prevent other mischief.
----
ikiwiki does not expose untrusted data to the shell. In fact it doesn't use
system() at all, and the only use of backticks is on data supplied by the
-wiki admin. And it runs with taint checks on of course..
-
-## destination directory file replacement
-
-Any file in the destination directory that is a valid page filename can be
-replaced, even if it was not originally rendered from a page. For example,
-ikiwiki.cgi could be edited in the wiki, and it would write out a
-replacement. File permission is preseved. Yipes!
-
-This was fixed by making ikiwiki check if the file it's writing to exists;
-if it does then it has to be a file that it's aware of creating before, or
-it will refuse to create it.
-
-Still, this sort of attack is something to keep in mind.
+wiki admin and untainted filenames. And it runs with taint checks on of course..
## cgi data security
or contain ".." or "/.svn/". Annoyingly ad-hoc, this kind of code is where
security holes breed. It needs a test suite at the very least.
-## cgi password security
-
-Login to the wiki involves sending a password in cleartext over the net.
-Cracking the password only allows editing the moo as that user though.
-If you care, you can use https, I suppose.
-
## CGI::Session security
I've audited this module and it is massively insecure by default. ikiwiki
uses it in one of the few secure ways; by forcing it to write to a
directory it controls (and not /tmp) and by setting a umask that makes the
file not be world readable.
+
+## cgi password security
+
+Login to the wiki involves sending a password in cleartext over the net.
+Cracking the password only allows editing the wiki as that user though.
+If you care, you can use https, I suppose.
+
+# Fixed holes.
+
+## destination directory file replacement
+
+Any file in the destination directory that is a valid page filename can be
+replaced, even if it was not originally rendered from a page. For example,
+ikiwiki.cgi could be edited in the wiki, and it would write out a
+replacement. File permission is preseved. Yipes!
+
+This was fixed by making ikiwiki check if the file it's writing to exists;
+if it does then it has to be a file that it's aware of creating before, or
+it will refuse to create it.
+
+Still, this sort of attack is something to keep in mind.
+
+## symlink attacks
+
+Could a committer trick ikiwiki into following a symlink and operating on
+some other tree that it shouldn't? svn supports symlinks, so one can get
+into the repo. ikiwiki uses File::Find to traverse the repo, and does not
+tell it to follow symlinks, but it might be possible to race replacing a
+directory with a symlink and trick it into following the link.
+
+Also, if someone checks in a symlink to /etc/passwd, ikiwiki would read and publish that, which could be used to expose files a committer otherwise wouldn't see.
+
+To avoid this, ikiwiki will avoid reading files that are symlinks, and uses locking to prevent more than one instance running at a time. The lock prevents one ikiwiki from running a svn up at the wrong time to race another ikiwiki. So only attackers who can write to the working copy on their own can race it.
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