2 files changed, 21 insertions, 9 deletions

diff --git a/usr.bin/su/su.1 b/usr.bin/su/su.1
index de68040c57a6..e6232ccfa789 100644
--- a/usr.bin/su/su.1
+++ b/usr.bin/su/su.1
@@ -30,7 +30,7 @@
 .\" SUCH DAMAGE.
 .\"
 .\"	@(#)su.1	8.2 (Berkeley) 4/18/94
-.\"	$Id$
+.\"	$Id: su.1,v 1.3.2.6 1998/02/18 12:15:58 markm Exp $
 .\"
 .\" this is for hilit19's braindeadness: "
 .Dd April 18, 1994
@@ -152,13 +152,16 @@ option as understood by most shells.  Note that
 usually expects a single argument only; you have to quote it when
 passing multiple words.
 .Pp
-Only users listed in group 0 (normally
+Only users who are a member of group 0 (normally
 .Dq wheel )
 can
 .Nm
 to
-.Dq root ,
-unless this group is empty.
+.Dq root .
+\ If group 0 is missing or empty, any user can
+.Nm
+to
+.Dq root .
 .Pp
 By default (unless the prompt is reset by a startup file) the super-user
 prompt is set to
diff --git a/usr.bin/su/su.c b/usr.bin/su/su.c
index a5bc1b3ce95e..fd7cdb18c934 100644
--- a/usr.bin/su/su.c
+++ b/usr.bin/su/su.c
@@ -42,7 +42,7 @@ static const char copyright[] =
 static char sccsid[] = "@(#)su.c	8.3 (Berkeley) 4/2/94";
 #endif
 static const char rcsid[] =
-	"$Id: su.c,v 1.14.2.6 1998/02/18 12:16:03 markm Exp $";
+	"$Id: su.c,v 1.14.2.7 1998/05/26 06:28:30 danny Exp $";
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -113,6 +113,7 @@ main(argc, argv)
 	char *p, **g, *user, *shell=NULL, *username, **cleanenv, **nargv, **np;
 	struct group *gr;
 	uid_t ruid;
+	gid_t gid;
 	int asme, ch, asthem, fastlogin, prio, i;
 	enum { UNSET, YES, NO } iscsh = UNSET;
 #ifdef LOGIN_CAP
@@ -203,6 +204,7 @@ main(argc, argv)
 	if (pwd == NULL)
 		errx(1, "who are you?");
 	username = strdup(pwd->pw_name);
+	gid = pwd->pw_gid;
 	if (username == NULL)
 		err(1, NULL);
 	if (asme) {
@@ -254,14 +256,21 @@ main(argc, argv)
 		}
 #endif
 		{
-			/* only allow those in group zero to su to root. */
+			/*
+			 * Only allow those with pw_gid==0 or those listed in
+			 * group zero to su to root.  If group zero entry is
+			 * missing or empty, then allow anyone to su to root.
+			 * iswheelsu will only be set if the user is EXPLICITLY
+			 * listed in group zero.
+			 */
 			if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)) &&
 			    gr->gr_mem && *(gr->gr_mem))
 				for (g = gr->gr_mem;; ++g) {
 					if (!*g)
-						errx(1,
-			    "you are not in the correct group to su %s.",
-						    user);
+						if (gid == 0)
+							break;
+						else
+							errx(1, "you are not in the correct group to su %s.", user);
 					if (strcmp(username, *g) == 0) {
 #ifdef WHEELSU
 						iswheelsu = 1;