Make the default behavior of local port assignment match traditional

systems (my last change did not mix well with some firewall
configurations).  As much as I dislike firewalls, this is one thing I
I was not prepared to break by default.. :-)

Allow the user to nominate one of three ranges of port numbers as
candidates for selecting a local address to replace a zero port number.
The ranges are selected via a setsockopt(s, IPPROTO_IP, IP_PORTRANGE, &arg)
call.  The three ranges are: default, high (to bypass firewalls) and
low (to get a port below 1024).

The default and high port ranges are sysctl settable under sysctl
net.inet.ip.portrange.*

This code also fixes a potential deadlock if the system accidently ran out
of local port addresses. It'd drop into an infinite while loop.

The secure port selection (for root) should reduce overheads and increase
reliability of rlogin/rlogind/rsh/rshd if they are modified to take
advantage of it.

Partly suggested by: pst
Reviewed by: wollman

1 files changed, 68 insertions, 14 deletions

diff --git a/sys/netinet/in_pcb.c b/sys/netinet/in_pcb.c
index 6fa0d2f..85496a6 100644
--- a/sys/netinet/in_pcb.c
+++ b/sys/netinet/in_pcb.c
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)in_pcb.c	8.4 (Berkeley) 5/24/95
- *	$Id: in_pcb.c,v 1.15 1995/11/14 20:33:59 phk Exp $
+ *	$Id: in_pcb.c,v 1.16 1996/01/19 08:00:58 peter Exp $
  */
 
 #include <sys/param.h>
@@ -65,13 +65,21 @@ struct	in_addr zeroin_addr;
  * These configure the range of local port addresses assigned to
  * "unspecified" outgoing connections/packets/whatever.
  */
-static int ipport_firstauto = IPPORT_FIRSTAUTO;
-static int ipport_lastauto = IPPORT_LASTAUTO;
+static int ipport_firstauto = IPPORT_RESERVED;		/* 1024 */
+static int ipport_lastauto  = IPPORT_USERRESERVED;	/* 5000 */
+static int ipport_hifirstauto = IPPORT_HIFIRSTAUTO;	/* 40000 */
+static int ipport_hilastauto  = IPPORT_HILASTAUTO;	/* 44999 */
 
-SYSCTL_INT(_net_inet_ip, OID_AUTO, port_first_auto, CTLFLAG_RW,
+SYSCTL_NODE(_net_inet_ip, IPPROTO_IP, portrange, CTLFLAG_RW, 0, "IP Ports");
+
+SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, first, CTLFLAG_RW,
 	   &ipport_firstauto, 0, "");
-SYSCTL_INT(_net_inet_ip, OID_AUTO, port_last_auto, CTLFLAG_RW,
+SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, last, CTLFLAG_RW,
 	   &ipport_lastauto, 0, "");
+SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, hifirst, CTLFLAG_RW,
+	   &ipport_hifirstauto, 0, "");
+SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, hilast, CTLFLAG_RW,
+	   &ipport_hilastauto, 0, "");
 
 static void	 in_pcbinshash __P((struct inpcb *));
 static void	 in_rtchange __P((struct inpcb *, int));
@@ -162,15 +170,61 @@ in_pcbbind(inp, nam)
 		}
 		inp->inp_laddr = sin->sin_addr;
 	}
-	if (lport == 0)
-		do {
-			++*lastport;
-			if (*lastport < ipport_firstauto ||
-			    *lastport > ipport_lastauto)
-				*lastport = ipport_firstauto;
-			lport = htons(*lastport);
-		} while (in_pcblookup(head,
-			    zeroin_addr, 0, inp->inp_laddr, lport, wild));
+	if (lport == 0) {
+		ushort first, last;
+		int count;
+
+		if (inp->inp_flags & INP_HIGHPORT) {
+			first = ipport_hifirstauto;	/* sysctl */
+			last  = ipport_hilastauto;
+		} else if (inp->inp_flags & INP_LOWPORT) {
+			if (error = suser(p->p_ucred, &p->p_acflag))
+				return (EACCES);
+			first = IPPORT_RESERVED - 1;	/* 1023 */
+			last  = 1;
+		} else {
+			first = ipport_firstauto;	/* sysctl */
+			last  = ipport_lastauto;
+		}
+		/*
+		 * Simple check to ensure all ports are not used up causing
+		 * a deadlock here.
+		 *
+		 * We split the two cases (up and down) so that the direction
+		 * is not being tested on each round of the loop.
+		 */
+		if (first > last) {
+			/*
+			 * counting down
+			 */
+			count = first - last;
+
+			do {
+				if (count-- <= 0)	/* completely used? */
+					return (EADDRNOTAVAIL);
+				--*lastport;
+				if (*lastport > first || *lastport < last)
+					*lastport = first;
+				lport = htons(*lastport);
+			} while (in_pcblookup(head,
+				 zeroin_addr, 0, inp->inp_laddr, lport, wild));
+		} else {
+			/*
+			 * counting up
+			 */
+			count = last - first;
+
+			do {
+				if (count-- <= 0)	/* completely used? */
+					return (EADDRNOTAVAIL);
+				++*lastport;
+				if (*lastport < first || *lastport > last)
+					*lastport = first;
+				lport = htons(*lastport);
+			} while (in_pcblookup(head,
+				 zeroin_addr, 0, inp->inp_laddr, lport, wild));
+		}
+	}
 	inp->inp_lport = lport;
 	in_pcbrehash(inp);
 	return (0);