netstat: Fix possible ANSI terminal injection

include/escape.h

@@ -0,0 +1,28 @@
+/*
+ * escape.h - printing handling
+ *
+ * Copyright © 2011-2023 Jim Warner <james.warner@comcast.net>
+ * Copyright © 2016-2023 Craig Small <csmall@dropbear.xyz>
+ * Copyright © 1998-2005 Albert Cahalan
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef PROCPS_PROC_ESCAPE_H
+#define PROCPS_PROC_ESCAPE_H
+
+int escape_str (char *dst, const char *src, int bufsize);
+
+#endif

lib/Makefile

@@ -21,7 +21,7 @@ AFOBJS	 = unix.o inet.o inet6.o ax25.o ipx.o ddp.o ipx.o netrom.o af.o rose.o ec
 AFGROBJS = inet_gr.o inet6_gr.o ipx_gr.o ddp_gr.o netrom_gr.o ax25_gr.o rose_gr.o getroute.o x25_gr.o
 AFSROBJS = inet_sr.o inet6_sr.o netrom_sr.o ipx_sr.o setroute.o x25_sr.o
 ACTOBJS  = slip_ac.o ppp_ac.o activate.o
-VARIA	 = getargs.o masq_info.o proc.o util.o nstrcmp.o interface.o sockets.o
+VARIA	 = getargs.o masq_info.o proc.o util.o nstrcmp.o interface.o sockets.o escape.o
 
 # Default Name
 NET_LIB_NAME = net-tools

lib/escape.c

@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Escape character print handling derived from procps
+ * Copyright 1998-2002 by Albert Cahalan
+ * Copyright 2020-2022 Jim Warner <james.warner@comcast.net>
+ *
+ */
+
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+#include <langinfo.h>
+
+static const char UTF_tab[] = {
+	1,  1,	1,  1,	1,  1,	1,  1,
+	1,  1,	1,  1,	1,  1,	1,  1, // 0x00 - 0x0F
+	1,  1,	1,  1,	1,  1,	1,  1,
+	1,  1,	1,  1,	1,  1,	1,  1, // 0x10 - 0x1F
+	1,  1,	1,  1,	1,  1,	1,  1,
+	1,  1,	1,  1,	1,  1,	1,  1, // 0x20 - 0x2F
+	1,  1,	1,  1,	1,  1,	1,  1,
+	1,  1,	1,  1,	1,  1,	1,  1, // 0x30 - 0x3F
+	1,  1,	1,  1,	1,  1,	1,  1,
+	1,  1,	1,  1,	1,  1,	1,  1, // 0x40 - 0x4F
+	1,  1,	1,  1,	1,  1,	1,  1,
+	1,  1,	1,  1,	1,  1,	1,  1, // 0x50 - 0x5F
+	1,  1,	1,  1,	1,  1,	1,  1,
+	1,  1,	1,  1,	1,  1,	1,  1, // 0x60 - 0x6F
+	1,  1,	1,  1,	1,  1,	1,  1,
+	1,  1,	1,  1,	1,  1,	1,  1, // 0x70 - 0x7F
+	-1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, // 0x80 - 0x8F
+	-1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, // 0x90 - 0x9F
+	-1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, // 0xA0 - 0xAF
+	-1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, // 0xB0 - 0xBF
+	-1, -1, 2,  2,	2,  2,	2,  2,
+	2,  2,	2,  2,	2,  2,	2,  2, // 0xC0 - 0xCF
+	2,  2,	2,  2,	2,  2,	2,  2,
+	2,  2,	2,  2,	2,  2,	2,  2, // 0xD0 - 0xDF
+	3,  3,	3,  3,	3,  3,	3,  3,
+	3,  3,	3,  3,	3,  3,	3,  3, // 0xE0 - 0xEF
+	4,  4,	4,  4,	4,  -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, // 0xF0 - 0xFF
+};
+
+static const unsigned char ESC_tab[] = {
+	"@..............................." // 0x00 - 0x1F
+	"||||||||||||||||||||||||||||||||" // 0x20 - 0x3F
+	"||||||||||||||||||||||||||||||||" // 0x40 - 0x5f
+	"|||||||||||||||||||||||||||||||." // 0x60 - 0x7F
+	"????????????????????????????????" // 0x80 - 0x9F
+	"????????????????????????????????" // 0xA0 - 0xBF
+	"????????????????????????????????" // 0xC0 - 0xDF
+	"????????????????????????????????" // 0xE0 - 0xFF
+};
+
+static void esc_all(unsigned char *str)
+{
+	// if bad locale/corrupt str, replace non-printing stuff
+	while (*str) {
+		unsigned char c = ESC_tab[*str];
+
+		if (c != '|')
+			*str = c;
+		++str;
+	}
+}
+
+static void esc_ctl(unsigned char *str, int len)
+{
+	int i;
+
+	for (i = 0; i < len;) {
+		// even with a proper locale, strings might be corrupt
+		int n = UTF_tab[*str];
+
+		if (n < 0 || i + n > len) {
+			esc_all(str);
+			return;
+		}
+		// and eliminate those non-printing control characters
+		if (*str < 0x20 || *str == 0x7f)
+			*str = '?';
+		str += n;
+		i += n;
+	}
+}
+
+int escape_str(char *dst, const char *src, int bufsize)
+{
+	static int utf_sw;
+
+	if (utf_sw == 0) {
+		char *enc = nl_langinfo(CODESET);
+
+		utf_sw = enc && strcasecmp(enc, "UTF-8") == 0 ? 1 : -1;
+	}
+
+	int n = strlcpy(dst, src, bufsize);
+
+	if (utf_sw < 0)
+		esc_all((unsigned char *)dst);
+	else
+		esc_ctl((unsigned char *)dst, n);
+	return n;
+}

netstat.c

@@ -96,6 +96,7 @@
 #include "interface.h"
 #include "util.h"
 #include "proc.h"
+#include "escape.h"
 
 #if HAVE_SELINUX
 #include <selinux/selinux.h>
@@ -397,7 +398,7 @@ static void prg_cache_load(void)
 {
     char line[LINE_MAX], eacces=0;
     int procfdlen, fd, cmdllen, lnamelen;
-    char lname[30], cmdlbuf[512], finbuf[PROGNAME_WIDTH];
+    char lname[30], cmdlbuf[512], ecmdlbuf[512], finbuf[PROGNAME_WIDTH];
     unsigned long inode;
     const char *cs, *cmdlp;
     DIR *dirproc = NULL, *dirfd = NULL;
@@ -467,10 +468,11 @@ static void prg_cache_load(void)
 		    cmdlp++;
 		else
 		    cmdlp = cmdlbuf;
+		escape_str (ecmdlbuf, cmdlp, 512);
 	    }
 	    // pid can be up to 10, use rest from commandline start.
 	    // #pragma GCC diagnostic ignored "-Wformat-truncation"?
-	    snprintf(finbuf, sizeof(finbuf), "%s/%s", direproc->d_name, cmdlp);
+	    snprintf(finbuf, sizeof(finbuf), "%s/%s", direproc->d_name, ecmdlbuf);
 #if HAVE_SELINUX
 	    if (getpidcon(atoi(direproc->d_name), &scon) == -1) {
 		    scon=xstrdup("-");