1 files changed, 49 insertions, 3 deletions

diff --git a/uidswap.c b/uidswap.c
index aab7064eb..91d878c30 100644
--- a/uidswap.c
+++ b/uidswap.c
@@ -1,3 +1,4 @@
+/* $OpenBSD: uidswap.c,v 1.35 2006/08/03 03:34:42 deraadt Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -12,7 +13,15 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: uidswap.c,v 1.24 2003/05/29 16:58:45 deraadt Exp $");
+
+#include <sys/param.h>
+#include <errno.h>
+#include <pwd.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdarg.h>
+
+#include <grp.h>
 
 #include "log.h"
 #include "uidswap.h"
@@ -77,7 +86,7 @@ temporarily_use_uid(struct passwd *pw)
                 fatal("getgroups: %.100s", strerror(errno));
         if (saved_egroupslen > 0) {
                 saved_egroups = xrealloc(saved_egroups,
-                    saved_egroupslen * sizeof(gid_t));
+                    saved_egroupslen, sizeof(gid_t));
                 if (getgroups(saved_egroupslen, saved_egroups) < 0)
                         fatal("getgroups: %.100s", strerror(errno));
         } else { /* saved_egroupslen == 0 */
@@ -96,7 +105,7 @@ temporarily_use_uid(struct passwd *pw)
                         fatal("getgroups: %.100s", strerror(errno));
                 if (user_groupslen > 0) {
                         user_groups = xrealloc(user_groups,
-                            user_groupslen * sizeof(gid_t));
+                            user_groupslen, sizeof(gid_t));
                         if (getgroups(user_groupslen, user_groups) < 0)
                                 fatal("getgroups: %.100s", strerror(errno));
                 } else { /* user_groupslen == 0 */
@@ -123,6 +132,41 @@ temporarily_use_uid(struct passwd *pw)
                     strerror(errno));
 }
 
+void
+permanently_drop_suid(uid_t uid)
+{
+        uid_t old_uid = getuid();
+
+        debug("permanently_drop_suid: %u", (u_int)uid);
+#if defined(HAVE_SETRESUID) && !defined(BROKEN_SETRESUID)
+        if (setresuid(uid, uid, uid) < 0)
+                fatal("setresuid %u: %.100s", (u_int)uid, strerror(errno));
+#elif defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID)
+        if (setreuid(uid, uid) < 0)
+                fatal("setreuid %u: %.100s", (u_int)uid, strerror(errno));
+#else
+# ifndef SETEUID_BREAKS_SETUID
+        if (seteuid(uid) < 0)
+                fatal("seteuid %u: %.100s", (u_int)uid, strerror(errno));
+# endif
+        if (setuid(uid) < 0)
+                fatal("setuid %u: %.100s", (u_int)uid, strerror(errno));
+#endif
+
+#ifndef HAVE_CYGWIN
+        /* Try restoration of UID if changed (test clearing of saved uid) */
+        if (old_uid != uid &&
+            (setuid(old_uid) != -1 || seteuid(old_uid) != -1))
+                fatal("%s: was able to restore old [e]uid", __func__);
+#endif
+
+        /* Verify UID drop was successful */
+        if (getuid() != uid || geteuid() != uid) {
+                fatal("%s: euid incorrect uid:%u euid:%u (should be %u)",
+                    __func__, (u_int)getuid(), (u_int)geteuid(), (u_int)uid);
+        }
+}
+
 /*
  * Restores to the original (privileged) uid.
  */
@@ -169,6 +213,8 @@ permanently_set_uid(struct passwd *pw)
         uid_t old_uid = getuid();
         gid_t old_gid = getgid();
 
+        if (pw == NULL)
+                fatal("permanently_set_uid: no user given");
         if (temporarily_use_uid_effective)
                 fatal("permanently_set_uid: temporarily_use_uid effective");
         debug("permanently_set_uid: %u/%u", (u_int)pw->pw_uid,