Re: problems in get_rfc1413_data()

Arkadiusz Mi¶kiewicz (misiek@misiek.eu.org)
Mon, 23 Aug 1999 11:48:28 +0200

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On Fri, 20 Aug 1999, Arkadiusz Mi¶kiewicz wrote:

> Fix for this tomorow.

I fixed this posibly security hole (DoS attack) using POSIX siglongjmp()
and sigsetjmp(). Now alarm() breaks read() after timeout...

Also I created basic autoconf/automake support (but not yet
finished - I have no time to do this).

ps. I missed one thing :-( in main.c
if (getnameinfo((struct sockaddr *)&socket_addr,
                SA_LEN((struct sockaddr *)&socket_addr),
                remote_addr, sizeof(remote_addr), NULL, 0,
- 0) != 0) {
+ NI_NAMEREQD) != 0) {
getnameinfo((struct sockaddr *)&socket_addr,
                SA_LEN((struct sockaddr *)&socket_addr),
                remote_addr, sizeof(remote_addr), NULL, 0,
                NI_NUMERICHOST);

full patch at:
http://www(.ipv6).misiek.eu.org/ipv6/cfingerd-1.4.0-ipv6-210899.patch.gz

-- 
+ Arkadiusz Mi¶kiewicz \/ PLD/Linux  IPv6 ready +
+ misiek@misiek.eu.org /\ http://www.pld.org.pl +

Index: rfc1413.c
===================================================================
RCS file: /CVSROOT/cfingerd/src/rfc1413.c,v
retrieving revision 1.17
retrieving revision 1.20
diff -u -r1.17 -r1.20
--- rfc1413.c	1999/08/19 12:29:25	1.17
+++ rfc1413.c	1999/08/20 18:02:57	1.20
@@ -16,10 +16,11 @@
 
 #include "cfingerd.h"
 
+static jmp_buf ident_alarm;
+
 void rfc1413_alarm(int signal)
 {
-    if (signal == SIGALRM)
-	ident_user = "unknown@alarm.signal";
+    siglongjmp(ident_alarm, 1);
 }
 
 /* Self contained RFC1413 implementation.  Thanks to Joel Katz for parts of
@@ -29,7 +30,8 @@
 #define BUFLEN	256
 char *get_rfc1413_data( struct sockaddr_storage local_addr )
 {
-    int j, err, errcon = -1;
+    
+    static int j = -1, err = -1;
     char buffer[1024], buf[BUFLEN], uname[64], *bleah;
     char *cp, *xp;
     struct addrinfo hints, *res, *res0;
@@ -43,7 +45,12 @@
     if((err = getaddrinfo(ip_address, "113", &hints, &res0)) < 0) {
 	    syslog(LOG_ERR, "rfc1413-getaddrinfo: %s", gai_strerror(err));
 	    snprintf(bleah, BUFLEN, "unknown@%s", remote_addr);
-	    alarm(0);
+	    return(bleah);
+    }
+    err = -1;
+    
+    if (sigsetjmp(ident_alarm, 1) != 0) {
+	    snprintf(bleah, BUFLEN, "alarm.signal@%s", remote_addr);
 	    return(bleah);
     }
     signal(SIGALRM, rfc1413_alarm);
@@ -64,12 +71,12 @@
 	    if (connect(j, res->ai_addr, res->ai_addrlen) < 0)
 		    close(j);
 	    else {
-		    errcon = 0;
+		    err = 0;
 		    break;
 	    }
     }
     freeaddrinfo(res0);
-    if (errcon < 0) {
+    if (err < 0) {
 	    syslog(LOG_ERR, "rfc1413-socket-or-connect problem");
 	    snprintf(bleah, BUFLEN, "unknown@%s", remote_addr);
 	    alarm(0);
Index: cfingerd.h
===================================================================
RCS file: /CVSROOT/cfingerd/src/cfingerd.h,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- cfingerd.h	1999/08/17 22:32:08	1.2
+++ cfingerd.h	1999/08/20 18:02:57	1.3
@@ -28,6 +28,7 @@
 #include <ctype.h>
 #include <time.h>
 #include <pwd.h>
+#include <setjmp.h>
 
 #include <netinet/in.h>
 #include <sys/socket.h>



application/x-gunzip attachment: cfingerd.tar.gz

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