upstream: invalidate supplemental group cache used by

temporarily_use_uid() when the target uid differs; could cause failure to
read authorized_keys under some configurations. patch by Jakub Jelen via
bz2873; ok dtucker, markus

OpenBSD-Commit-ID: 48a345f0ee90f6c465a078eb5e89566b23abd8a1

1 files changed, 6 insertions, 2 deletions

diff --git a/uidswap.c b/uidswap.c
index 8bf6b244e..1430b822a 100644
--- a/uidswap.c
+++ b/uidswap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: uidswap.c,v 1.39 2015/06/24 01:49:19 dtucker Exp $ */
+/* $OpenBSD: uidswap.c,v 1.40 2018/06/15 07:01:11 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -49,6 +49,7 @@ static gid_t	saved_egid = 0;
 /* Saved effective uid. */
 static int      privileged = 0;
 static int      temporarily_use_uid_effective = 0;
+static uid_t    user_groups_uid;
 static gid_t    *saved_egroups = NULL, *user_groups = NULL;
 static int      saved_egroupslen = -1, user_groupslen = -1;
 
@@ -92,10 +93,11 @@ temporarily_use_uid(struct passwd *pw)
                         fatal("getgroups: %.100s", strerror(errno));
         } else { /* saved_egroupslen == 0 */
                 free(saved_egroups);
+                saved_egroups = NULL;
         }
 
         /* set and save the user's groups */
-        if (user_groupslen == -1) {
+        if (user_groupslen == -1 || user_groups_uid != pw->pw_uid) {
                 if (initgroups(pw->pw_name, pw->pw_gid) < 0)
                         fatal("initgroups: %s: %.100s", pw->pw_name,
                             strerror(errno));
@@ -110,7 +112,9 @@ temporarily_use_uid(struct passwd *pw)
                                 fatal("getgroups: %.100s", strerror(errno));
                 } else { /* user_groupslen == 0 */
                         free(user_groups);
+                        user_groups = NULL;
                 }
+                user_groups_uid = pw->pw_uid;
         }
         /* Set the effective uid to the given (unprivileged) uid. */
         if (setgroups(user_groupslen, user_groups) < 0)