Add some extra checks to make sure that a child ypserv process doesn't

try to fork() a child of its own, which could result in several children
ypservs running at once. I'm still not sure exactly what leads to this
condition, but these fixes should stop it from causing trouble. A new
function, yp_fork() checks to see if the current process is already a
child of the parent ypserv, and returns failure (and logs an error message)
rather than spawning another child.

3 files changed, 30 insertions, 18 deletions

diff --git a/usr.sbin/ypserv/yp_extern.h b/usr.sbin/ypserv/yp_extern.h
index 0aaee26..4786cca 100644
--- a/usr.sbin/ypserv/yp_extern.h
+++ b/usr.sbin/ypserv/yp_extern.h
@@ -29,7 +29,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: yp_extern.h,v 1.11 1997/02/22 16:15:11 peter Exp $
+ *	$Id: yp_extern.h,v 1.12 1997/10/29 07:25:03 charnier Exp $
  */
 
 #include <db.h>
@@ -68,6 +68,8 @@ extern int	children;
 extern int	resfd;
 extern char 	*progname;
 extern char	*yp_dir;
+extern pid_t	yp_pid;
+
 extern enum ypstat	yp_errno;
 extern void	yp_error __P((const char *, ...));
 #ifdef DB_CACHE
diff --git a/usr.sbin/ypserv/yp_main.c b/usr.sbin/ypserv/yp_main.c
index f20ccb3..dbd38fe 100644
--- a/usr.sbin/ypserv/yp_main.c
+++ b/usr.sbin/ypserv/yp_main.c
@@ -32,7 +32,7 @@
 
 #ifndef lint
 static const char rcsid[] =
-	"$Id: yp_main.c,v 1.18 1998/06/04 15:11:14 wpaul Exp $";
+	"$Id: yp_main.c,v 1.19 1999/02/10 16:16:14 wpaul Exp $";
 #endif /* not lint */
 
 /*
@@ -99,6 +99,8 @@ void _msgout(char* msg)
 		syslog(LOG_ERR, msg);
 }
 
+pid_t	yp_pid;
+
 static void
 yp_svc_run()
 {
@@ -108,12 +110,11 @@ yp_svc_run()
 	int readfds;
 #endif /* def FD_SETSIZE */
 	extern int forked;
-	int pid;
 	int fd_setsize = _rpc_dtablesize();
 	struct timeval timeout;
 
 	/* Establish the identity of the parent ypserv process. */
-	pid = getpid();
+	yp_pid = getpid();
 
 	for (;;) {
 #ifdef FD_SETSIZE
@@ -135,16 +136,19 @@ yp_svc_run()
 			warn("svc_run: - select failed");
 			return;
 		case 0:
-			yp_prune_dnsq();
+			if (getpid() == yp_pid)
+				yp_prune_dnsq();
 			break;
 		default:
-			if (FD_ISSET(resfd, &readfds)) {
-				yp_run_dnsq();
-				FD_CLR(resfd, &readfds);
+			if (getpid() == yp_pid) {
+				if (FD_ISSET(resfd, &readfds)) {
+					yp_run_dnsq();
+					FD_CLR(resfd, &readfds);
+				}
+				svc_getreqset(&readfds);
 			}
-			svc_getreqset(&readfds);
 		}
-		if (forked && pid != getpid())
+		if (yp_pid != getpid())
 			_exit(0);
 	}
 }
diff --git a/usr.sbin/ypserv/yp_server.c b/usr.sbin/ypserv/yp_server.c
index 76cb5ea..b771468 100644
--- a/usr.sbin/ypserv/yp_server.c
+++ b/usr.sbin/ypserv/yp_server.c
@@ -33,7 +33,7 @@
 
 #ifndef lint
 static const char rcsid[] =
-	"$Id: yp_server.c,v 1.26 1998/02/11 19:15:32 wpaul Exp $";
+	"$Id: yp_server.c,v 1.27 1999/02/10 16:16:14 wpaul Exp $";
 #endif /* not lint */
 
 #include "yp.h"
@@ -49,7 +49,6 @@ static const char rcsid[] =
 #include <arpa/inet.h>
 #include <rpc/rpc.h>
 
-int forked = 0;
 int children = 0;
 
 #define	MASTER_STRING	"YP_MASTER_NAME"
@@ -57,6 +56,17 @@ int children = 0;
 #define	ORDER_STRING	"YP_LAST_MODIFIED"
 #define	ORDER_SZ	sizeof(ORDER_STRING) - 1
 
+static pid_t yp_fork()
+{
+	if (yp_pid != getpid()) {
+		yp_error("child %d trying to fork!", getpid());
+		errno = EEXIST;
+		return(-1);
+	}
+
+	return(fork());
+}
+
 /*
  * NIS v2 support. This is where most of the action happens.
  */
@@ -350,7 +360,7 @@ ypproc_xfr_2_svc(ypreq_xfr *argp, struct svc_req *rqstp)
 		YPXFR_RETURN(YPXFR_REFUSED)
 	}
 
-	switch(fork()) {
+	switch(yp_fork()) {
 	case 0:
 	{
 		char g[11], t[11], p[11];
@@ -380,7 +390,6 @@ ypproc_xfr_2_svc(ypreq_xfr *argp, struct svc_req *rqstp)
 			p, argp->map_parms.map,
 		      	NULL);
 		}
-		forked++;
 		yp_error("ypxfr execl(%s): %s", ypxfr_command, strerror(errno));
 		YPXFR_RETURN(YPXFR_XFRERR)
 		break;
@@ -392,7 +401,6 @@ ypproc_xfr_2_svc(ypreq_xfr *argp, struct svc_req *rqstp)
 	default:
 		result.xfrstat = YPXFR_SUCC;
 		children++;
-		forked = 0;
 		break;
 	}
 
@@ -507,9 +515,8 @@ ypproc_all_2_svc(ypreq_nokey *argp, struct svc_req *rqstp)
 	 * async socket I/O?)
 	 */
 	if (!debug) {
-		switch(fork()) {
+		switch(yp_fork()) {
 		case 0:
-			forked++;
 			break;
 		case -1:
 			yp_error("ypall fork(): %s", strerror(errno));
@@ -518,7 +525,6 @@ ypproc_all_2_svc(ypreq_nokey *argp, struct svc_req *rqstp)
 			break;
 		default:
 			children++;
-			forked = 0;
 			return (NULL);
 			break;
 		}