Re: This is my first patch for systemd

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On Thu, Jul 22, 2010 at 08:22, Daniel J Walsh <dwalsh@xxxxxxxxxx> wrote:
> The patch does not handle, systemd creating the directories for the
> fifo_file.  In the future, their is talk of making /var/run a tmpfs file
> system.  This would mean systemd would create /var/run/mysqld/ before
> creating /var/run/mysqld/mysqld.socket.  Additional SELinux controls
> would have to be added to systemd to get this correct.  Not sure if the
> correct thing to do is at selabel or use
> selinux_getfileconfrompath(daemon, parentdir, "dir")

Hmm, one thing that I've been thinking about for a while now is a
policy extension to type transitions allowing a match against the
object name.

So for example, assuming /var/run gets correctly labelled as var_run_t:

typename_transition systemd_t var_run_t:file "mysqld" mysql_var_run_t;

If some form of globbing or patterns was added, this could in theory
even replace the current file_contexts file with a big list of
named_type_transitions in the policy.  Admittedly it could potentially
make the policy larger, but I believe with careful encoding and
compression it would be a net reduction in the size of
/etc/selinux/$POLICYNAME/ (since the plain-text highly-repetitive
file_contexts would go away).

There are a few limitations that I can think of, though:

 * You could only match on whatever "name" field is available in the
security manager, not the full path, although with proper labels on
most of the path components this is not really an issue.

 * Since the name matching would need to be performed in the kernel,
there would be a very strict limit on the complexity of the pattern or
glob engine (probably NOT a bad thing :-D)

As an example of where this would be useful, you could automatically
assign separate labels to ".htpasswd" and ".htaccess" files created in
www-data directories to prevent compromised web applications from
creating, modifying, or even reading them.

Cheers,
Kyle Moffett


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