foo

[ikiwiki.git] / doc / security.mdwn

diff --git a/doc/security.mdwn b/doc/security.mdwn
index e514223e378573f23fa6866bec46d0c5d2f7c5b8..53000c08efd8ab194b5b6e79d5a360ebdb5155f8 100644 (file)
--- a/doc/security.mdwn
+++ b/doc/security.mdwn
@@ -10,20 +10,7 @@ to be kept in mind.
 
 # Probable holes
 
 
 # Probable holes
 

-## XSS holes in CGI output
-
-ikiwiki has not yet been audited to ensure that all cgi script input/output is
-sanitised to prevent XSS attacks.
-
-## image file etc attacks
-
-If it enounters a file type it does not understand, ikiwiki just copies it
-into place. So if you let users add any kind of file they like, they can
-upload images, movies, windows executables, css files, etc (though not html
-files). If these files exploit security holes in the browser of someone
-who's viewing the wiki, that can be a security problem.
-
-Of course nobody else seems to worry about this in other wikis, so should we?
+_(The list of things to fix.)_

 
 ## svn commit logs
 
 
 ## svn commit logs
 


@@ -43,6 +30,22 @@ ikiwiki escapes any html in svn commit logs to prevent other mischief.
 
 _(Things not to do.)_
 
 
 _(Things not to do.)_
 

+## image file etc attacks
+
+If it enounters a file type it does not understand, ikiwiki just copies it
+into place. So if you let users add any kind of file they like, they can
+upload images, movies, windows executables, css files, etc (though not html
+files). If these files exploit security holes in the browser of someone
+who's viewing the wiki, that can be a security problem.
+
+Of course nobody else seems to worry about this in other wikis, so should we?
+
+Currently only people with direct svn commit access can upload such files
+(and if you wanted to you could block that with a svn pre-commit hook).
+Wsers with only web commit access are limited to editing pages as ikiwiki
+doesn't support file uploads from browsers (yet), so they can't exploit
+this.
+

 ## multiple accessors of wiki directory
 
 If multiple people can write to the source directory ikiwiki is using, or
 ## multiple accessors of wiki directory
 
 If multiple people can write to the source directory ikiwiki is using, or


@@ -59,7 +62,7 @@ this wiki, BTW.
 
 ## page locking can be bypassed via direct svn commits
 
 
 ## page locking can be bypassed via direct svn commits
 

-A [[lock]]ed page can only be edited on the web by an admin, but
+A locked page can only be edited on the web by an admin, but

 anyone who is allowed to commit direct to svn can bypass this. This is by
 design, although a subversion pre-commit hook could be used to prevent
 editing of locked pages when using subversion, if you really need to.
 anyone who is allowed to commit direct to svn can bypass this. This is by
 design, although a subversion pre-commit hook could be used to prevent
 editing of locked pages when using subversion, if you really need to.


@@ -130,11 +133,20 @@ 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.
 
 Cracking the password only allows editing the wiki as that user though.
 If you care, you can use https, I suppose.
 

+## XSS holes in CGI output
+
+ikiwiki has not yet been audited to ensure that all cgi script input/output
+is sanitised to prevent XSS attacks. For example, a user can't register
+with a username containing html code (anymore).
+
+It's difficult to know for sure if all such avenues have really been
+closed though.
+

 ----
 
 # Fixed holes
 
 ----
 
 # Fixed holes
 

-_(Unless otherwise noted, these were discovered and immediatey fixed by the
+_(Unless otherwise noted, these were discovered and immediately fixed by the

 ikiwiki developers.)_
 
 ## destination directory file replacement
 ikiwiki developers.)_
 
 ## destination directory file replacement


@@ -172,12 +184,18 @@ their own can race it.
 
 Similarly, a svn commit of a symlink could be made, ikiwiki ignores it
 because of the above, but the symlink is still there, and then you edit the
 
 Similarly, a svn commit of a symlink could be made, ikiwiki ignores it
 because of the above, but the symlink is still there, and then you edit the

-page from the web, which follows the symlink when reading the page, and
-again when saving the changed page.
+page from the web, which follows the symlink when reading the page
+(exposing the content), and again when saving the changed page (changing
+the content).
+
+This was fixed for page saving by making ikiwiki refuse to write to files
+that are symlinks, or that are in subdirectories that are symlinks,
+combined with the above locking.

 
 

-This was fixed by making ikiwiki refuse to read or write to files that are
-symlinks, or that are in subdirectories that are symlinks, combined with
-the above locking.
+For page editing, it's fixed by ikiwiki checking to make sure that it
+already has found a page by scanning the tree, before loading it for
+editing, which as described above, also is done in a way that avoids
+symlink attacks.

 
 ## underlaydir override attacks
 
 
 ## underlaydir override attacks
 


@@ -186,21 +204,26 @@ pages to all wikis w/o needing to copy them into the wiki. Since ikiwiki
 internally stores only the base filename from the underlaydir or srcdir,
 and searches for a file in either directory when reading a page source,
 there is the potential for ikiwiki's scanner to reject a file from the
 internally stores only the base filename from the underlaydir or srcdir,
 and searches for a file in either directory when reading a page source,
 there is the potential for ikiwiki's scanner to reject a file from the

-srcdir for some reason (such as it being a symlink), find a valid copy of
-the file in the underlaydir, and then when loading the file, mistekenly
-load the bad file from the srcdir.
+srcdir for some reason (such as it being contained in a directory that is
+symlinked in), find a valid copy of the file in the underlaydir, and then
+when loading the file, mistakenly load the bad file from the srcdir.
+
+This attack is avoided by making ikiwiki refuse to add any files from the
+underlaydir if a file also exists in the srcdir with the same name.

 
 

-This attack is avoided by making ikiwiki scan the srcdir first, and refuse
-to add any files from the underlaydir if a file also exists in the srcdir
-with the same name. **But**, note that this assumes that any given page can
-be produced from a file with only one name (`page.mdwn` => `page.html`).
+## multiple page source issues

 
 

-If it's possible for files with different names to produce a given page, it
-would still be possible to use this attack to confuse ikiwiki into
-rendering the wrong thing. This is not currently possible, but must be kept
-in mind in the future when for example adding support for generating html
-pages from source with some other extension.
+Note that I previously worried that underlay override attacks could also be
+accomplished if ikiwiki were extended to support other page markup
+languages besides markdown. However, a closer look indicates that this is
+not a problem: ikiwiki does preserve the file extension when storing the
+source filename of a page, so a file with another extension that renders to
+the same page name can't bypass the check. Ie, ikiwiki won't skip foo.rst
+in the srcdir, find foo.mdwn in the underlay, decide to render page foo and
+then read the bad foo.mdwn. Instead it will remember the .rst extension and
+only render a file with that extension.

 
 ## XSS attacks in page content
 
 
 ## XSS attacks in page content
 

-ikiwiki supports [[HtmlSanitistion]], though it can be turned off.
+ikiwiki supports protecting users from their own broken browsers via the
+[[plugins/htmlscrubber]] plugin, which is enabled by default.