[Bug libc/5010] New: sunrpc service cleanup causes unwanted port mapper traffic

["ian at iay dot org dot uk" <sourceware-bugzilla at sourceware dot org>]

The svc_register function may be called with a final (protocol) parameter of 0 to suppress registration 
of the service with the local port mapper.

However, the svc_unregister function always calls the port mapper to unregister the service, even if it 
was not originally called during service registration.

This means that even if you didn't want your service registered with the port mapper, the library will 
attempt to bind a privileged UDP port on your behalf when the service is unregistered.  Note that you 
can't avoid this by simply not calling svc_unregister, because the __rpc_thread_svc_cleanup function will 
always call svc_unregister on your behalf on thread wind-down.

The main effect of this is seen in an SELinux environment, where an application that only makes internal 
use of the RPC calls nevertheless appears to require the ability to bind privileged ports.  This may lead 
to people blindly granting such privileges to applications that don't really require them, which is 
obviously a bad thing from a security perspective.

-- 
           Summary: sunrpc service cleanup causes unwanted port mapper
                    traffic
           Product: glibc
           Version: 2.4
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: ian at iay dot org dot uk
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=5010

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