[Bug 306362] Re: Default D-Bus system bus policy is allow

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** Changed in: dbus (Debian)
       Status: Unknown => Fix Released

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https://bugs.launchpad.net/bugs/306362

Title:
  Default D-Bus system bus policy is allow

Status in D-Bus:
  Fix Released
Status in “dbus” package in Ubuntu:
  Fix Released
Status in “dbus” package in Debian:
  Fix Released
Status in “dbus” package in Fedora:
  Fix Released

Bug description:
  A new security release of DBus is now available:

  http://dbus.freedesktop.org/dbus/releases/dbus-1.2.6.tar.gz

  This release contains a (partial, see below) fix for:
  https://bugs.freedesktop.org/show_bug.cgi?id=18229

  == Summary ==

  Joachim Breitner discovered a mistake in the default configuration for the
  system bus (system.conf) which made the default policy for both sent and
  received messages effectively *allow*, and not deny as intended.

  This release fixes the send side permission, but does not change the receive.
  See below for more details.

  == Available workarounds ==

  Add explicit <deny> rules to existing policy files which do not
  already have them.

  == Mitigating factors ==

  There are three important mitigating factors.

  * First, in an examination of a Fedora 10 system, many services contained
  explicit <deny> rules under the "default" context. These deny rules did (and
  continue to) operate as expected.

  * Second, an increasing trend has been for core system services to use
  PolicyKit, or otherwise do security checks on the service side.  Any system
  which relies on PolicyKit is unaffected by this flaw.

  * Third, the SELinux DBus support is not affected by this flaw.

  Now, as mentioned above this fix is partial.  DBus has two kinds of policy
  permissions, send and receive.  Generally speaking, the send side permission is
  much more important.  However, DBus has supported receive side permissions for
  a few reasons, among those are:

  * Ensuring signals containing sensitive data aren't visible by unexpected
  processes.  Suggested fix: Do not put sensitive data in DBus signals; use
  targeted method calls.

  * A way for processes to "second-pass" filter messages before they reach their
  C code.  Suggested fix: Something like PolicyKit (or just manual service-side
  permission checks) remain a better way to do this.

  For compatibility reasons, this release only fixes the send-side permission
  check, and not receive.  A greater number of services will need to be updated
  for a future tightening of the receive permission.

  We are as yet unsure when (and in fact, if) the receive permission will be
  tightened in the DBus 1.2 stable branch.  We will gather information about any
  affected programs and make a final determination at in the near future.

  == Conclusion Summary ==

  * Add explicit <deny> rules under the default policy if this is applicable to
  your service (i.e. not using PolicyKit or similar)
  * Do not put sensitive information in signals

  == Thanks ==

  Thanks to Joachim Breitner for the initial report and proposed patch, Tomas
  Hoger for the current fix, and others for their assistance with this issue.
  _______________________________________________
  dbus mailing list
  dbus at lists.freedesktop.org
  http://lists.freedesktop.org/mailman/listinfo/dbus

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