SELinux: BUG in SELinux compat_net code

This patch is not applicable to Linus's tree as the code in question has
been removed for 2.6.30.  I'm sending in case any of the stable
maintainers would like to push to their branches (which I think anything
pre 2.6.30 would like to do).

Ubuntu users were experiencing a kernel panic when they enabled SELinux
due to an old bug in our handling of the compatibility mode network
controls, introduced Jan 1 2008 effad8df
Most distros have not used the compat_net code since the new code was
introduced and so noone has hit this problem before.  Ubuntu is the only
distro I know that enabled that legacy cruft by default.  But, I was ask
to look at it and found that the above patch changed a call to
avc_has_perm from if(send_perm) to if(!send_perm) in
selinux_ip_postroute_iptables_compat().  The result is that users who
turn on SELinux and have compat_net set can (and oftern will) BUG() in
avc_has_perm_noaudit since they are requesting 0 permissions.

This patch corrects that accidental bug introduction.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>