/*
-
-uidswap.c
-
-Author: Tatu Ylonen <ylo@cs.hut.fi>
-
-Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
- All rights reserved
-
-Created: Sat Sep 9 01:56:14 1995 ylo
-
-Code for uid-swapping.
-
-*/
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ * All rights reserved
+ * Code for uid-swapping.
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose. Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ */
#include "includes.h"
-RCSID("$Id$");
+RCSID("$OpenBSD: uidswap.c,v 1.16 2001/04/20 16:32:22 markus Exp $");
-#include "ssh.h"
+#include "log.h"
#include "uidswap.h"
-/* Note: all these functions must work in all of the following cases:
-
- 1. euid=0, ruid=0
- 2. euid=0, ruid!=0
- 3. euid!=0, ruid!=0
-
- Additionally, they must work regardless of whether the system has
- POSIX saved uids or not. */
-
-#ifdef _POSIX_SAVED_IDS
+/*
+ * Note: all these functions must work in all of the following cases:
+ * 1. euid=0, ruid=0
+ * 2. euid=0, ruid!=0
+ * 3. euid!=0, ruid!=0
+ * Additionally, they must work regardless of whether the system has
+ * POSIX saved uids or not.
+ */
+
+#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
-#endif /* _POSIX_SAVED_IDS */
-
/* Saved effective uid. */
-static uid_t saved_euid = 0;
+static uid_t saved_euid = 0;
+static gid_t saved_egid = 0;
+#endif
-/* Temporarily changes to the given uid. If the effective user id is not
- root, this does nothing. This call cannot be nested. */
+/* Saved effective uid. */
+static int privileged = 0;
+static int temporarily_use_uid_effective = 0;
+static gid_t saved_egroups[NGROUPS_MAX], user_groups[NGROUPS_MAX];
+static int saved_egroupslen = -1, user_groupslen = -1;
-void temporarily_use_uid(uid_t uid)
+/*
+ * 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(struct passwd *pw)
{
+ /* Save the current euid, and egroups. */
#ifdef SAVED_IDS_WORK_WITH_SETEUID
-
- /* Save the current euid. */
- saved_euid = geteuid();
-
- /* Set the effective uid to the given (unprivileged) uid. */
- if (seteuid(uid) == -1)
- debug("seteuid %d: %.100s", (int)uid, strerror(errno));
-
-#else /* SAVED_IDS_WORK_WITH_SETUID */
-
- /* Propagate the privileged uid to all of our uids. */
- if (setuid(geteuid()) < 0)
- debug("setuid %d: %.100s", (int)geteuid(), strerror(errno));
-
- /* Set the effective uid to the given (unprivileged) uid. */
- if (seteuid(uid) == -1)
- debug("seteuid %d: %.100s", (int)uid, strerror(errno));
-
+ saved_euid = geteuid();
+ saved_egid = getegid();
+ debug("temporarily_use_uid: %d/%d (e=%d)",
+ pw->pw_uid, pw->pw_gid, saved_euid);
+ if (saved_euid != 0) {
+ privileged = 0;
+ return;
+ }
+#else
+ if (geteuid() != 0) {
+ privileged = 0;
+ return;
+ }
#endif /* SAVED_IDS_WORK_WITH_SETEUID */
+ privileged = 1;
+ temporarily_use_uid_effective = 1;
+ saved_egroupslen = getgroups(NGROUPS_MAX, saved_egroups);
+ if (saved_egroupslen < 0)
+ fatal("getgroups: %.100s", strerror(errno));
+
+ /* 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(NGROUPS_MAX, user_groups);
+ if (user_groupslen < 0)
+ fatal("getgroups: %.100s", strerror(errno));
+ }
+#ifndef HAVE_CYGWIN
+ /* Set the effective uid to the given (unprivileged) uid. */
+ if (setgroups(user_groupslen, user_groups) < 0)
+ fatal("setgroups: %.100s", strerror(errno));
+#endif /* !HAVE_CYWIN */
+#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));
+#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));
}
-/* Restores to the original uid. */
-
-void restore_uid()
+/*
+ * Restores to the original (privileged) uid.
+ */
+void
+restore_uid(void)
{
-#ifdef SAVED_IDS_WORK_WITH_SETEUID
-
- /* Set the effective uid back to the saved uid. */
- if (seteuid(saved_euid) < 0)
- debug("seteuid %d: %.100s", (int)saved_euid, strerror(errno));
+ debug("restore_uid");
+ /* it's a no-op unless privileged */
+ if (!privileged)
+ 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 privileged uid. */
+ if (seteuid(saved_euid) < 0)
+ 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. */
- /* Propagate the real uid (usually more privileged) to effective uid
- as well. */
- setuid(getuid());
-
+ /*
+ * We are unable to restore the real uid to its unprivileged value.
+ * Propagate the real uid (usually more privileged) to effective uid
+ * as well.
+ */
+ setuid(getuid());
+ setgid(getgid());
#endif /* SAVED_IDS_WORK_WITH_SETEUID */
-}
-/* Permanently sets all uids to the given uid. This cannot be called while
- temporarily_use_uid is effective. */
+#ifndef HAVE_CYGWIN
+ if (setgroups(saved_egroupslen, saved_egroups) < 0)
+ fatal("setgroups: %.100s", strerror(errno));
+#endif /* !HAVE_CYGWIN */
+ temporarily_use_uid_effective = 0;
+}
-void permanently_set_uid(uid_t uid)
+/*
+ * Permanently sets all uids to the given uid. This cannot be
+ * called while temporarily_use_uid is effective.
+ */
+void
+permanently_set_uid(struct passwd *pw)
{
- if (setuid(uid) < 0)
- debug("setuid %d: %.100s", (int)uid, strerror(errno));
+ if (temporarily_use_uid_effective)
+ fatal("restore_uid: temporarily_use_uid effective");
+ if (setgid(pw->pw_gid) < 0)
+ fatal("setgid %u: %.100s", (u_int) pw->pw_gid, strerror(errno));
+ if (setuid(pw->pw_uid) < 0)
+ fatal("setuid %u: %.100s", (u_int) pw->pw_uid, strerror(errno));
}
andersk / openssh.git / blobdiff