From a6dbafc0031b54f4f30a265a9469f08aefec03fa Mon Sep 17 00:00:00 2001
From: millert <millert@openbsd.org>
Date: Fri, 21 Sep 2018 19:13:49 +0000
Subject: [PATCH] Use password/group cache functions and avoid stashing a
 pointer to the return value of getgrgid(3) or getgrnam(3) which relies on
 undefined behavior.  The rdist server will now use getgroups(2) to determine
 group membership of the invoking user.  In addition, there is now one
 implementation of tilde expansion instead of two. OK tb@ tim@

---
 usr.bin/rdistd/server.c | 52 ++++++++++++++++-------------------------
 1 file changed, 20 insertions(+), 32 deletions(-)

diff --git a/usr.bin/rdistd/server.c b/usr.bin/rdistd/server.c
index 21f1d4145fb..8f95ceee1ec 100644
--- a/usr.bin/rdistd/server.c
+++ b/usr.bin/rdistd/server.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: server.c,v 1.44 2018/09/09 13:53:11 millert Exp $	*/
+/*	$OpenBSD: server.c,v 1.45 2018/09/21 19:13:49 millert Exp $	*/
 
 /*
  * Copyright (c) 1983 Regents of the University of California.
@@ -177,7 +177,6 @@ setfilemode(char *file, int fd, int mode, int islink)
 static int
 fchog(int fd, char *file, char *owner, char *group, int mode)
 {
-	static struct group *gr = NULL;
 	int i;
 	struct stat st;
 	uid_t uid;
@@ -189,9 +188,7 @@ fchog(int fd, char *file, char *owner, char *group, int mode)
 		if (*owner == ':') {
 			uid = (uid_t) atoi(owner + 1);
 		} else if (strcmp(owner, locuser) != 0) {
-			struct passwd *pw;
-
-			if ((pw = getpwnam(owner)) == NULL) {
+			if (uid_from_user(owner, &uid) == -1) {
 				if (mode != -1 && IS_ON(mode, S_ISUID)) {
 					message(MT_NOTICE,
 			      "%s: unknown login name \"%s\", clearing setuid",
@@ -202,8 +199,7 @@ fchog(int fd, char *file, char *owner, char *group, int mode)
 					message(MT_NOTICE,
 					"%s: unknown login name \"%s\"",
 						target, owner);
-			} else
-				uid = pw->pw_uid;
+			}
 		} else {
 			uid = userid;
 			primegid = groupid;
@@ -213,8 +209,6 @@ fchog(int fd, char *file, char *owner, char *group, int mode)
 			goto ok;
 		}
 	} else {	/* not root, setuid only if user==owner */
-		struct passwd *lupw;
-
 		if (mode != -1) {
 			if (IS_ON(mode, S_ISUID) && 
 			    strcmp(locuser, owner) != 0)
@@ -222,35 +216,29 @@ fchog(int fd, char *file, char *owner, char *group, int mode)
 			if (mode)
 				mode &= ~S_ISVTX; /* and strip sticky too */
 		}
-
-		if ((lupw = getpwnam(locuser)) != NULL)
-			primegid = lupw->pw_gid;
+		primegid = groupid;
 	}
 
 	gid = (gid_t)-1;
-	if (gr == NULL || strcmp(group, gr->gr_name) != 0) {
-		if ((*group == ':' && 
-		     (getgrgid(gid = atoi(group + 1)) == NULL))
-		    || ((gr = (struct group *)getgrnam(group)) == NULL)) {
-			if (mode != -1 && IS_ON(mode, S_ISGID)) {
-				message(MT_NOTICE, 
-				"%s: unknown group \"%s\", clearing setgid",
-					target, group);
-				mode &= ~S_ISGID;
-			} else
-				message(MT_NOTICE, 
-					"%s: unknown group \"%s\"",
-					target, group);
+	if (*group == ':') {
+		gid = (gid_t) atoi(group + 1);
+	} else if (gid_from_group(group, &gid) == -1) {
+		if (mode != -1 && IS_ON(mode, S_ISGID)) {
+			message(MT_NOTICE, 
+			"%s: unknown group \"%s\", clearing setgid",
+				target, group);
+			mode &= ~S_ISGID;
 		} else
-			gid = gr->gr_gid;
-	} else
-		gid = gr->gr_gid;
+			message(MT_NOTICE, 
+				"%s: unknown group \"%s\"",
+				target, group);
+	}
 
 	if (userid && gid != (gid_t)-1 && gid != primegid) {
-		if (gr)
-			for (i = 0; gr->gr_mem[i] != NULL; i++)
-				if (strcmp(locuser, gr->gr_mem[i]) == 0)
-					goto ok;
+		for (i = 0; i < gidsetlen; i++) {
+			if (gid == gidset[i])
+				goto ok;
+		}
 		if (mode != -1 && IS_ON(mode, S_ISGID)) {
 			message(MT_NOTICE, 
 				"%s: user %s not in group %s, clearing setgid",
-- 
2.20.1