CVE-2013-2207, BZ #15755: Disable pt_chown.

The helper binary pt_chown tricked into granting access to another
user's pseudo-terminal.

Pre-conditions for the attack:

 * Attacker with local user account
 * Kernel with FUSE support
 * "user_allow_other" in /etc/fuse.conf
 * Victim with allocated slave in /dev/pts

Using the setuid installed pt_chown and a weak check on whether a file
descriptor is a tty, an attacker could fake a pty check using FUSE and
trick pt_chown to grant ownership of a pty descriptor that the current
user does not own.  It cannot access /dev/pts/ptmx however.

In most modern distributions pt_chown is not needed because devpts
is enabled by default. The fix for this CVE is to disable building
and using pt_chown by default. We still provide a configure option
to enable hte use of pt_chown but distributions do so at their own
risk.

1 files changed, 1 insertions, 0 deletions

diff --git a/config.make.in b/config.make.in
index b01b70be2b..7b04568a22 100644
--- a/config.make.in
+++ b/config.make.in
@@ -95,6 +95,7 @@ link-obsolete-rpc = @link_obsolete_rpc@
 build-nscd = @build_nscd@
 use-nscd = @use_nscd@
 build-hardcoded-path-in-tests= @hardcoded_path_in_tests@
+build-pt-chown = @build_pt_chown@
 
 # Build tools.
 CC = @CC@