bin/59493: Add insecure option to lpd

[perseant%nbdev.hhhh.org@localhost]

>Number:         59493
>Category:       bin
>Synopsis:       Add insecure option to lpd
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Sun Jun 29 19:10:00 +0000 2025
>Originator:     Konrad Schroder <perseant%netbsd.org@localhost>
>Release:        NetBSD-current 2025-06-29
>Organization:
>Environment:
System: NetBSD nbdev.hhhh.org 10.0 NetBSD 10.0 (XEN3_DOMU) #0: Thu Mar 28 08:33:33 UTC 2024 mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/xen/compile/XEN3_DOMU amd64
Architecture: x86_64
Machine: amd64
>Description:
	lpd(8) provides network access control using hosts_access(5) and
	requires reverse DNS to serve requests from the network.  In a modern
	setting, host access is generally provided via host firewall, and
	in a small network setting, anonymous clients are common.  The patch
	below provides a flag, -i, that disables the network security checks
	for cases where they do not make sense (e.g. home network, or
	a host that already uses npf(7) for access control).

	The default behavior, of course, would not be changed.
>How-To-Repeat:
	Set up a printer using lpd(8) and attempt to print from a remote host
	that does not have reverse DNS.
>Fix:
	The following patch implements the desired flag:

--------8<--------
Index: lpd/lpd.8
===================================================================
RCS file: /cvsroot/src/usr.sbin/lpr/lpd/lpd.8,v
retrieving revision 1.36
diff -u -r1.36 lpd.8
--- lpd/lpd.8	3 Jul 2017 21:35:31 -0000	1.36
+++ lpd/lpd.8	29 Jun 2025 18:45:15 -0000
@@ -95,6 +95,16 @@
 See
 .Xr setsockopt 2
 for more details.
+.It Fl i
+The
+.Fl i
+option selects 
+.Dq insecure
+mode, bypassing the address-based checks described below.  Options
+.Fl i
+and
+.Fl s
+are mutually exclusive.
 .It Fl l
 The
 .Fl l
@@ -137,7 +147,11 @@
 .Nm
 runs is subject to attack over the network and it is desired that the
 machine be protected from attempts to remotely fill spools and similar
-attacks.
+attacks.  Options
+.Fl s
+and
+.Fl i
+are mutually exclusive.
 .It Fl w
 The
 .Fl w
@@ -163,7 +177,9 @@
 port from
 .Pa /etc/services .
 .Pp
-Access control is provided by three means.
+Unless the
+.Fl i
+flag is specified, access control is provided by three means.
 First,
 .Pa /etc/hosts.allow
 and
Index: lpd/lpd.c
===================================================================
RCS file: /cvsroot/src/usr.sbin/lpr/lpd/lpd.c,v
retrieving revision 1.60
diff -u -r1.60 lpd.c
--- lpd/lpd.c	26 Apr 2023 18:25:02 -0000	1.60
+++ lpd/lpd.c	29 Jun 2025 18:45:15 -0000
@@ -117,6 +117,7 @@
 int deny_severity = LOG_AUTH|LOG_WARNING;
 #endif
 
+int	iflag;				/* insecure (no network checks) flag */
 int	lflag;				/* log requests flag */
 int	rflag;				/* allow of for remote printers */
 int	sflag;				/* secure (no inet) flag */
@@ -160,7 +161,7 @@
 	setprogname(*argv);
 
 	errs = 0;
-	while ((i = getopt(argc, argv, "b:dln:srw:W")) != -1)
+	while ((i = getopt(argc, argv, "b:diln:srw:W")) != -1)
 		switch (i) {
 		case 'b':
 			if (blist_addrs >= blist_size) {
@@ -176,6 +177,10 @@
 		case 'd':
 			options |= SO_DEBUG;
 			break;
+		case 'i':
+			sflag = 0;
+			iflag++;
+			break;
 		case 'l':
 			lflag++;
 			break;
@@ -189,6 +194,7 @@
 			rflag++;
 			break;
 		case 's':
+			iflag = 0;
 			sflag++;
 			break;
 		case 'w':
@@ -604,6 +610,12 @@
 	struct request_info req;
 #endif
 
+	if (iflag) {
+		strcpy(fromb, inet_ntoa(((struct sockaddr_in *)f)->sin_addr));
+		from = fromb;
+		return;
+	}
+
 	error = getnameinfo(f, f->sa_len, NULL, 0, serv, sizeof(serv),
 			    NI_NUMERICSERV);
 	if (error)
@@ -694,7 +706,7 @@
 {
 
 	(void)fprintf(stderr,
-	    "Usage: %s [-dlrsW] [-b bind-address] [-n maxchild] "
+	    "Usage: %s [-dilrsW] [-b bind-address] [-n maxchild] "
 	    "[-w maxwait] [port]\n", getprogname());
 	exit(1);
 }
--------8<--------

	If there are no objections I'll commit in the coming weeks.