[Bug 1067473] Re: [quantal] isc-dhcp-client dropped network-interface-security symlink and therefore may run unconfined

[Jamie Strandboge]

4.2.4-1ubuntu10.1 from quantal-proposed works great. The test case
passes and there are no apparmor denials.

** Tags removed: verification-needed
** Tags added: verification-done

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Title:
  [quantal] isc-dhcp-client dropped network-interface-security symlink
  and therefore may run unconfined

Status in “isc-dhcp” package in Ubuntu:
  In Progress
Status in “isc-dhcp” source package in Quantal:
  Fix Committed
Status in “isc-dhcp” source package in Raring:
  In Progress

Bug description:
  [IMPACT] 
   * dhclient is a root run process and successfully exploiting a flaw in dhclient could 
     have severe consequences for the user's system
  [TESTCASE]
   * On an Ubuntu server system using dhcp for an interface:
    1. sudo aa-status # bug not fixed
       ...
       1 processes are unconfined but have a profile defined.
       /sbin/dhclient (<pid>)
    2. install the updates
    3. reboot
    4. sudo aa-status # bug fixed
       ...
       5 processes are in enforce mode.
       /sbin/dhclient (<pid>)
       ...
       0 processes are unconfined but have a profile defined.

  [Regression Potential] 
   * Regression potential is low. The AppArmor profile for dhclient has been in use for 
     years and is still in effect on the default Ubuntu desktop because of when network 
     manager runs (the profile is loaded before the interface is brought up). Therefore
     there should be no surprise denials.

  
  = Initial report =
  I was doing install audits of 12.10 and noticed this with 'sudo aa-status':
  1 processes are unconfined but have a profile defined.
     /sbin/dhclient (<pid removed>)

  This is a regression over 12.04 and needs to be fixed in an SRU. I don't know what introduced the regression, but it is very likely a race condition. I saw it on 12.10 server but not on 12.10 desktop. It seems to be at least somewhat reproducible (rebooting once showed it is still affected) with an amd64 VM with 1024M of ram with installation defaults (except home directory is encrypted) and the following tasks installed:
  Basic Ubuntu server
  OpenSSH server
  DNS server
  LAMP server
  Mail server
  PostgreSQL database
  Print server
  Samba file server
  Tomcat Java server
  Virtual Machine host

  Upon investigation this is because /etc/init/network-interface-security.conf is looking for files in /etc/apparmor/init/network-interface-security/*. Unfortunately, the quantal merge dropped this:
  diff -Naur ./precise/isc-dhcp-4.1.ESV-R4/debian/isc-dhcp-client.links ./quantal/isc-dhcp-4.2.4/debian/isc-dhcp-client.links
  --- ./precise/isc-dhcp-4.1.ESV-R4/debian/isc-dhcp-client.links	2012-10-16 13:48:13.000000000 -0500
  +++ ./quantal/isc-dhcp-4.2.4/debian/isc-dhcp-client.links	1969-12-31 18:00:00.000000000 -0600
  @@ -1,3 +0,0 @@
  -sbin/dhclient sbin/dhclient3
  -usr/share/man/man8/dhclient.8.gz usr/share/man/man8/dhclient3.8.gz
  -etc/apparmor.d/sbin.dhclient etc/apparmor/init/network-interface-security/sbin.dhclient

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