cron(8): convert vfork() usage to fork()

vfork() is error-prone, and the usage here definitely grew to not be clearly OK given vfork-semantics; e.g. setusercontext(3) within the child. Rip out vfork() and the rest of the references to it. fork is heavier, but it's unclear that the difference will be all that obvious. Reported by: Andrew Gierth and [email protected]
nhuff · Feb 10, 2020 · 9b36723 · 9b36723
1 parent 9ce1504
commit 9b36723
Show file tree

Hide file tree

Showing 5 changed files with 8 additions and 31 deletions.
diff --git a/usr.sbin/cron/cron/compat.h b/usr.sbin/cron/cron/compat.h
@@ -76,10 +76,6 @@
 
 /*****************************************************************/
 
-#if !defined(BSD) && !defined(HPUX) && !defined(CONVEX) && !defined(__linux)
-# define NEED_VFORK
-#endif
-
 #if (!defined(BSD) || (BSD < 198902)) && !defined(__linux) && \
 	!defined(IRIX) && !defined(NeXT) && !defined(HPUX)
 # define NEED_STRCASECMP

diff --git a/usr.sbin/cron/cron/do_command.c b/usr.sbin/cron/cron/do_command.c
@@ -58,9 +58,6 @@ do_command(e, u)
 	/* fork to become asynchronous -- parent process is done immediately,
 	 * and continues to run the normal cron code, which means return to
 	 * tick().  the child and grandchild don't leave this function, alive.
-	 *
-	 * vfork() is unsuitable, since we have much to do, and the parent
-	 * needs to be able to run off and fork other processes.
 	 */
 	switch ((pid = fork())) {
 	case -1:
@@ -222,13 +219,13 @@ child_process(e, u)
 
 	/* fork again, this time so we can exec the user's command.
 	 */
-	switch (jobpid = vfork()) {
+	switch (jobpid = fork()) {
 	case -1:
-		log_it("CRON",getpid(),"error","can't vfork");
+		log_it("CRON",getpid(),"error","can't fork");
 		exit(ERROR_EXIT);
 		/*NOTREACHED*/
 	case 0:
-		Debug(DPROC, ("[%d] grandchild process Vfork()'ed\n",
+		Debug(DPROC, ("[%d] grandchild process fork()'ed\n",
 			      getpid()))
 
 		if (e->uid == ROOT_UID)
@@ -315,24 +312,24 @@ child_process(e, u)
 			if (setgid(e->gid) != 0) {
 				log_it(usernm, getpid(),
 				    "error", "setgid failed");
-				exit(ERROR_EXIT);
+				_exit(ERROR_EXIT);
 			}
 # if defined(BSD)
 			if (initgroups(usernm, e->gid) != 0) {
 				log_it(usernm, getpid(),
 				    "error", "initgroups failed");
-				exit(ERROR_EXIT);
+				_exit(ERROR_EXIT);
 			}
 # endif
 			if (setlogin(usernm) != 0) {
 				log_it(usernm, getpid(),
 				    "error", "setlogin failed");
-				exit(ERROR_EXIT);
+				_exit(ERROR_EXIT);
 			}
 			if (setuid(e->uid) != 0) {
 				log_it(usernm, getpid(),
 				    "error", "setuid failed");
-				exit(ERROR_EXIT);
+				_exit(ERROR_EXIT);
 			}
 			/* we aren't root after this..*/
 #if defined(LOGIN_CAP)

diff --git a/usr.sbin/cron/cron/externs.h b/usr.sbin/cron/cron/externs.h
@@ -141,7 +141,3 @@ extern	int		getdtablesize(void);
 #ifdef NEED_SETENV
 extern	int		setenv(char *, char *, int);
 #endif
-
-#ifdef NEED_VFORK
-extern	PID_T		vfork(void);
-#endif
diff --git a/usr.sbin/cron/cron/popen.c b/usr.sbin/cron/cron/popen.c
@@ -112,7 +112,7 @@ cron_popen(program, type, e, pidptr)
 #endif
 
 	iop = NULL;
-	switch(pid = vfork()) {
+	switch(pid = fork()) {
 	case -1:			/* error */
 		(void)close(pdes[0]);
 		(void)close(pdes[1]);

diff --git a/usr.sbin/cron/lib/compat.c b/usr.sbin/cron/lib/compat.c
@@ -35,18 +35,6 @@ static char rcsid[] = "$FreeBSD$";
 #include <paths.h>
 
 
-/* the code does not depend on any of vfork's
- * side-effects; it just uses it as a quick
- * fork-and-exec.
- */
-#ifdef NEED_VFORK
-PID_T
-vfork() {
-	return (fork());
-}
-#endif
-
-
 #ifdef NEED_STRDUP
 char *
 strdup(str)