bin/56500: rpc.lockd needs to use reserved ports

[Jonathan Lennox]

The following reply was made to PR bin/56500; it has been noted by GNATS.

From: Jonathan Lennox <lennox at cs.columbia.edu>
To: FreeBSD-gnats-submit at FreeBSD.org, freebsd-bugs at FreeBSD.org
Cc:  
Subject: Re: bin/56500: rpc.lockd needs to use reserved ports
Date: Sat, 6 Sep 2003 13:28:13 -0400

 After a day or so of untangling how RPC code works, I've worked out a patch.
 
 I'm pretty sure that this patch regains root privileges for the absolute
 minimum amount of time necessary to bind to a reserved port.
 
 I've tested this, and it does (along with the patch in kern/56461) allow me
 to sucessfully lock files from a Linux server -- and thus to invoke movemail
 on my mailspool, and thus to read my mail on my FreeBSD machine, which was
 the whole motivation.
 
 --- usr.sbin/rpc.lockd/lock_proc.c.orig	Sat Sep  6 12:48:10 2003
 +++ usr.sbin/rpc.lockd/lock_proc.c	Sat Sep  6 13:18:08 2003
 @@ -197,6 +197,8 @@
  	const char *netid;
  	struct netconfig *nconf;
  	char host[NI_MAXHOST];
 +	uid_t old_euid;
 +	int clnt_fd;
  
  	gettimeofday(&time_now, NULL);
  
 @@ -270,6 +272,22 @@
  		syslog(LOG_ERR, "Unable to return result to %s", host);
  		return NULL;
  	}
 +
 +	/* Get the FD of the client, for bindresvport. */ 
 +	clnt_control(client, CLGET_FD, &clnt_fd);
 +
 +	/* Regain root privileges, for bindresvport. */
 +	old_euid = geteuid();
 +	seteuid(0);
 +
 +	/*
 +	 * Bind the client FD to a reserved port.
 +	 * Some NFS servers reject any NLM request from a non-reserved port. 
 +	 */ 
 +	bindresvport(clnt_fd, NULL);
 +
 +	/* Drop root privileges again. */
 +	seteuid(old_euid);
  
  	/* Success - update the cache entry */
  	clnt_cache_ptr[clnt_cache_next_to_use] = client;