foo

[ikiwiki.git] / doc / security.mdwn

diff --git a/doc/security.mdwn b/doc/security.mdwn
index 575ccbad8075ba32ab8b3590ada760f491d1aaa6..7b056fd6c1fecbb4101cb8f9c5ba9dbf3efb867e 100644 (file)
--- a/doc/security.mdwn
+++ b/doc/security.mdwn
@@ -1,7 +1,10 @@
-If you are using ikiwiki to render pages that only you can edit, then there
-are no more security issues with this program than with cat(1). If,
-however, you let others edit pages in your wiki, then some security issues
-do need to be kept in mind.
+Let's do an ikiwiki security analysis..
+
+If you are using ikiwiki to render pages that only you can edit, do not
+generate any wrappers, and do not use the cgi, then there are no more
+security issues with this program than with cat(1). If, however, you let
+others edit pages in your wiki, then some possible security issues do need
+to be kept in mind.
 
 ## html attacks
 
@@ -37,3 +40,46 @@ hopefully your web server will not run it.
 If your web server does any parsing of special sorts of files (for example,
 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.
+
+## --gen-wrapper might generate insecure wrappers
+
+ikiwiki --gen-wrapper is intended to generate a wrapper program that
+runs ikiwiki to update a given wiki. The wrapper can in turn be made suid,
+for example to be used in a [[post-commit]] hook by people who cannot write
+to the html pages, etc.
+
+If the wrapper script is made suid, then any bugs in this wrapper would be
+security holes. The wrapper is written as securely as I know how and
+there's been no problem yet.
+
+## 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.
+
+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.
+
+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.
+
+Even with locking, if an attacker has local write access to the checkout,
+they could still fool ikiwiki using similar races. So it's best if only one
+person can ever write to the checkout that ikiwiki compiles the moo from.
+
+## cgi security
+
+When ikiwiki runs as a cgi to edit a page, it is passed the name of the
+page to edit. It has to make sure to sanitise this page, to prevent eg,
+editing of ../../../foo, or editing of files that are not part of the wiki,
+such as subversion dotfiles. This is done by sanitising the filename
+removing unallowed characters, then making sure it doesn't start with "/"
+or contain ".." or "/.svn/". Annoyingly ad-hoc, this kind of code is where
+security holes breed.