Implemented _POSIX_SAVED_IDS behaviour according to 1003.1-1990, with

allowed extension from Appendix B, section 4.2.2.

3 files changed, 37 insertions, 24 deletions

diff --git a/lib/libc/sys/setuid.2 b/lib/libc/sys/setuid.2
index deca532b388..b271097c84b 100644
--- a/lib/libc/sys/setuid.2
+++ b/lib/libc/sys/setuid.2
@@ -62,8 +62,11 @@ user IDs and the saved set-user-ID of the current process
 to the specified value.
 The
 .Fn setuid
-function is permitted if the specified ID is equal to the real user ID
-of the process, or if the effective user ID is that of the super user.
+function is permitted if the effective user ID is that of the super user,
+or if the specified user ID is the same as the effective user ID.  If
+not, but the specified user ID is the same as the real user ID,
+.Fn setuid
+will set the effective user ID to the real user ID.
 .Pp
 The
 .Fn setgid
@@ -73,8 +76,11 @@ group IDs and the saved set-group-ID of the current process
 to the specified value.
 The
 .Fn setgid
-function is permitted if the specified ID is equal to the real group ID
-of the process, or if the effective user ID is that of the super user.
+function is permitted if the effective user ID is that of the super user,
+or if the specified group ID is the same as the effective group ID.  If
+not, but the specified group ID is the same as the real group ID,
+.Fn setgid
+will set the effective group ID to the real group ID.
 .Pp
 The
 .Fn seteuid
@@ -109,10 +115,10 @@ The
 and
 .Fn setgid
 functions are compliant with the
-.St -p1003.1-88
+.St -p1003.1-90
 specification with
 .Li _POSIX_SAVED_IDS
-not defined.
+defined, with the extensions allowed in section B.4.2.2.
 The
 .Fn seteuid
 and
diff --git a/sys/kern/kern_prot.c b/sys/kern/kern_prot.c
index f957ecbccb3..fe386801da0 100644
--- a/sys/kern/kern_prot.c
+++ b/sys/kern/kern_prot.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_prot.c,v 1.2 1996/03/03 17:19:52 niklas Exp $	*/
+/*	$OpenBSD: kern_prot.c,v 1.3 1996/08/01 05:26:02 tholo Exp $	*/
 /*	$NetBSD: kern_prot.c,v 1.33 1996/02/09 18:59:42 christos Exp $	*/
 
 /*
@@ -275,19 +275,29 @@ sys_setuid(p, v, retval)
 	uid = SCARG(uap, uid);
 #endif
 	if (uid != pc->p_ruid &&
+	    uid != pc->pc_ucred->cr_uid &&
 	    (error = suser(pc->pc_ucred, &p->p_acflag)))
 		return (error);
 	/*
 	 * Everything's okay, do it.
-	 * Transfer proc count to new user.
+	 */
+	if (uid == pc->pc_ucred->cr_uid ||
+	    suser(pc->pc_ucred, &p->p_acflag) == 0) {
+		/*
+		 * Transfer proc count to new user.
+		 */
+		if (uid != pc->p_ruid) {
+			(void)chgproccnt(pc->p_ruid, -1);
+			(void)chgproccnt(uid, 1);
+		}
+		pc->p_ruid = uid;
+		pc->p_svuid = uid;
+	}
+	/*
 	 * Copy credentials so other references do not see our changes.
 	 */
-	(void)chgproccnt(pc->p_ruid, -1);
-	(void)chgproccnt(uid, 1);
 	pc->pc_ucred = crcopy(pc->pc_ucred);
 	pc->pc_ucred->cr_uid = uid;
-	pc->p_ruid = uid;
-	pc->p_svuid = uid;
 	p->p_flag |= P_SUGID;
 	return (0);
 }
@@ -343,12 +353,17 @@ sys_setgid(p, v, retval)
 #else
 	gid = SCARG(uap, gid);
 #endif
-	if (gid != pc->p_rgid && (error = suser(pc->pc_ucred, &p->p_acflag)))
+	if (gid != pc->p_rgid &&
+	    gid != pc->pc_ucred->cr_gid &&
+	    (error = suser(pc->pc_ucred, &p->p_acflag)))
 		return (error);
+	if (gid == pc->pc_ucred->cr_gid ||
+	    suser(pc->pc_ucred, &p->p_acflag) == 0) {
+		pc->p_rgid = gid;
+		pc->p_svgid = gid;
+	}
 	pc->pc_ucred = crcopy(pc->pc_ucred);
 	pc->pc_ucred->cr_gid = gid;
-	pc->p_rgid = gid;
-	pc->p_svgid = gid;		/* ??? */
 	p->p_flag |= P_SUGID;
 	return (0);
 }
diff --git a/sys/sys/unistd.h b/sys/sys/unistd.h
index ec861cea36d..2a58fdf7f49 100644
--- a/sys/sys/unistd.h
+++ b/sys/sys/unistd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: unistd.h,v 1.2 1996/03/03 12:12:40 niklas Exp $	*/
+/*	$OpenBSD: unistd.h,v 1.3 1996/08/01 05:26:03 tholo Exp $	*/
 /*	$NetBSD: unistd.h,v 1.10 1994/06/29 06:46:06 cgd Exp $	*/
 
 /*
@@ -42,15 +42,7 @@
 /* compile-time symbolic constants */
 #define	_POSIX_JOB_CONTROL	/* implementation supports job control */
 
-/*
- * Although we have saved user/group IDs, we do not use them in setuid
- * as described in POSIX 1003.1, because the feature does not work for
- * root.  We use the saved IDs in seteuid/setegid, which are not currently
- * part of the POSIX 1003.1 specification.
- */
-#ifdef	_NOT_AVAILABLE
 #define	_POSIX_SAVED_IDS	/* saved set-user-ID and set-group-ID */
-#endif
 
 #define	_POSIX_VERSION		198808L
 #define	_POSIX2_VERSION		199212L