+/* $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
*/
#include "includes.h"
-RCSID("$OpenBSD: uidswap.c,v 1.12 2000/12/29 10:48:56 markus Exp $");
-#include "ssh.h"
+#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"
+#include "xmalloc.h"
/*
* Note: all these functions must work in all of the following cases:
* POSIX saved uids or not.
*/
-#ifdef _POSIX_SAVED_IDS
+#if defined(_POSIX_SAVED_IDS) && !defined(BROKEN_SAVED_UIDS)
/* Lets assume that posix saved ids also work with seteuid, even though that
is not part of the posix specification. */
#define SAVED_IDS_WORK_WITH_SETEUID
-
/* Saved effective uid. */
-static uid_t saved_euid = 0;
+static uid_t saved_euid = 0;
+static gid_t saved_egid = 0;
+#endif
-#endif /* _POSIX_SAVED_IDS */
+/* Saved effective uid. */
+static int privileged = 0;
+static int temporarily_use_uid_effective = 0;
+static gid_t *saved_egroups = NULL, *user_groups = NULL;
+static int saved_egroupslen = -1, user_groupslen = -1;
/*
* Temporarily changes to the given uid. If the effective user
* id is not root, this does nothing. This call cannot be nested.
*/
void
-temporarily_use_uid(uid_t uid)
+temporarily_use_uid(struct passwd *pw)
{
+ /* Save the current euid, and egroups. */
#ifdef SAVED_IDS_WORK_WITH_SETEUID
- /* Save the current euid. */
saved_euid = geteuid();
+ saved_egid = getegid();
+ debug("temporarily_use_uid: %u/%u (e=%u/%u)",
+ (u_int)pw->pw_uid, (u_int)pw->pw_gid,
+ (u_int)saved_euid, (u_int)saved_egid);
+#ifndef HAVE_CYGWIN
+ if (saved_euid != 0) {
+ privileged = 0;
+ return;
+ }
+#endif
+#else
+ if (geteuid() != 0) {
+ privileged = 0;
+ return;
+ }
+#endif /* SAVED_IDS_WORK_WITH_SETEUID */
+
+ privileged = 1;
+ temporarily_use_uid_effective = 1;
+
+ saved_egroupslen = getgroups(0, NULL);
+ if (saved_egroupslen < 0)
+ fatal("getgroups: %.100s", strerror(errno));
+ if (saved_egroupslen > 0) {
+ saved_egroups = xrealloc(saved_egroups,
+ saved_egroupslen, sizeof(gid_t));
+ if (getgroups(saved_egroupslen, saved_egroups) < 0)
+ fatal("getgroups: %.100s", strerror(errno));
+ } else { /* saved_egroupslen == 0 */
+ if (saved_egroups != NULL)
+ xfree(saved_egroups);
+ }
+
+ /* set and save the user's groups */
+ if (user_groupslen == -1) {
+ if (initgroups(pw->pw_name, pw->pw_gid) < 0)
+ fatal("initgroups: %s: %.100s", pw->pw_name,
+ strerror(errno));
+ user_groupslen = getgroups(0, NULL);
+ if (user_groupslen < 0)
+ fatal("getgroups: %.100s", strerror(errno));
+ if (user_groupslen > 0) {
+ user_groups = xrealloc(user_groups,
+ user_groupslen, sizeof(gid_t));
+ if (getgroups(user_groupslen, user_groups) < 0)
+ fatal("getgroups: %.100s", strerror(errno));
+ } else { /* user_groupslen == 0 */
+ if (user_groups)
+ xfree(user_groups);
+ }
+ }
/* Set the effective uid to the given (unprivileged) uid. */
- if (seteuid(uid) == -1)
- debug("seteuid %u: %.100s", (u_int) uid, strerror(errno));
-#else /* SAVED_IDS_WORK_WITH_SETEUID */
+ if (setgroups(user_groupslen, user_groups) < 0)
+ fatal("setgroups: %.100s", strerror(errno));
+#ifndef SAVED_IDS_WORK_WITH_SETEUID
+ /* Propagate the privileged gid to all of our gids. */
+ if (setgid(getegid()) < 0)
+ debug("setgid %u: %.100s", (u_int) getegid(), strerror(errno));
/* Propagate the privileged uid to all of our uids. */
if (setuid(geteuid()) < 0)
debug("setuid %u: %.100s", (u_int) geteuid(), strerror(errno));
-
- /* Set the effective uid to the given (unprivileged) uid. */
- if (seteuid(uid) == -1)
- debug("seteuid %u: %.100s", (u_int) uid, strerror(errno));
#endif /* SAVED_IDS_WORK_WITH_SETEUID */
+ if (setegid(pw->pw_gid) < 0)
+ fatal("setegid %u: %.100s", (u_int)pw->pw_gid,
+ strerror(errno));
+ if (seteuid(pw->pw_uid) == -1)
+ fatal("seteuid %u: %.100s", (u_int)pw->pw_uid,
+ 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 uid.
+ * Restores to the original (privileged) uid.
*/
void
restore_uid(void)
{
+ /* it's a no-op unless privileged */
+ if (!privileged) {
+ debug("restore_uid: (unprivileged)");
+ return;
+ }
+ if (!temporarily_use_uid_effective)
+ fatal("restore_uid: temporarily_use_uid not effective");
+
#ifdef SAVED_IDS_WORK_WITH_SETEUID
- /* Set the effective uid back to the saved uid. */
+ debug("restore_uid: %u/%u", (u_int)saved_euid, (u_int)saved_egid);
+ /* Set the effective uid back to the saved privileged uid. */
if (seteuid(saved_euid) < 0)
- debug("seteuid %u: %.100s", (u_int) saved_euid, strerror(errno));
+ fatal("seteuid %u: %.100s", (u_int)saved_euid, strerror(errno));
+ if (setegid(saved_egid) < 0)
+ fatal("setegid %u: %.100s", (u_int)saved_egid, strerror(errno));
#else /* SAVED_IDS_WORK_WITH_SETEUID */
/*
* We are unable to restore the real uid to its unprivileged value.
* as well.
*/
setuid(getuid());
+ setgid(getgid());
#endif /* SAVED_IDS_WORK_WITH_SETEUID */
+
+ if (setgroups(saved_egroupslen, saved_egroups) < 0)
+ fatal("setgroups: %.100s", strerror(errno));
+ temporarily_use_uid_effective = 0;
}
/*
* called while temporarily_use_uid is effective.
*/
void
-permanently_set_uid(uid_t uid)
+permanently_set_uid(struct passwd *pw)
{
- if (setuid(uid) < 0)
- debug("setuid %u: %.100s", (u_int) uid, strerror(errno));
+ 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,
+ (u_int)pw->pw_gid);
+
+#if defined(HAVE_SETRESGID) && !defined(BROKEN_SETRESGID)
+ if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) < 0)
+ fatal("setresgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
+#elif defined(HAVE_SETREGID) && !defined(BROKEN_SETREGID)
+ if (setregid(pw->pw_gid, pw->pw_gid) < 0)
+ fatal("setregid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
+#else
+ if (setegid(pw->pw_gid) < 0)
+ fatal("setegid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
+ if (setgid(pw->pw_gid) < 0)
+ fatal("setgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
+#endif
+
+#ifdef __APPLE__
+ /*
+ * OS X requires initgroups after setgid to opt back into
+ * memberd support for >16 supplemental groups.
+ */
+ if (initgroups(pw->pw_name, pw->pw_gid) < 0)
+ fatal("initgroups %.100s %u: %.100s",
+ pw->pw_name, (u_int)pw->pw_gid, strerror(errno));
+#endif
+
+#if defined(HAVE_SETRESUID) && !defined(BROKEN_SETRESUID)
+ if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) < 0)
+ fatal("setresuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
+#elif defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID)
+ if (setreuid(pw->pw_uid, pw->pw_uid) < 0)
+ fatal("setreuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
+#else
+# ifndef SETEUID_BREAKS_SETUID
+ if (seteuid(pw->pw_uid) < 0)
+ fatal("seteuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
+# endif
+ if (setuid(pw->pw_uid) < 0)
+ fatal("setuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
+#endif
+
+#ifndef HAVE_CYGWIN
+ /* Try restoration of GID if changed (test clearing of saved gid) */
+ if (old_gid != pw->pw_gid && pw->pw_uid != 0 &&
+ (setgid(old_gid) != -1 || setegid(old_gid) != -1))
+ fatal("%s: was able to restore old [e]gid", __func__);
+#endif
+
+ /* Verify GID drop was successful */
+ if (getgid() != pw->pw_gid || getegid() != pw->pw_gid) {
+ fatal("%s: egid incorrect gid:%u egid:%u (should be %u)",
+ __func__, (u_int)getgid(), (u_int)getegid(),
+ (u_int)pw->pw_gid);
+ }
+
+#ifndef HAVE_CYGWIN
+ /* Try restoration of UID if changed (test clearing of saved uid) */
+ if (old_uid != pw->pw_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() != pw->pw_uid || geteuid() != pw->pw_uid) {
+ fatal("%s: euid incorrect uid:%u euid:%u (should be %u)",
+ __func__, (u_int)getuid(), (u_int)geteuid(),
+ (u_int)pw->pw_uid);
+ }
}
andersk / openssh.git / blobdiff