Adding upstream version 2.36.1.upstream/2.36.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1215 insertions, 0 deletions

diff --git a/login-utils/su-common.c b/login-utils/su-common.c
new file mode 100644
index 0000000..563f6c7
--- /dev/null
+++ b/login-utils/su-common.c
@@ -0,0 +1,1215 @@
+/*
+ * su(1) for Linux.  Run a shell with substitute user and group IDs.
+ *
+ * Copyright (C) 1992-2006 Free Software Foundation, Inc.
+ * Copyright (C) 2012 SUSE Linux Products GmbH, Nuernberg
+ * Copyright (C) 2016-2017 Karel Zak <kzak@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2, or (at your option) any later
+ * version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.  You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ *
+ *
+ * Based on an implementation by David MacKenzie <djm@gnu.ai.mit.edu>.
+ */
+#include <stdio.h>
+#include <getopt.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+#include <security/pam_appl.h>
+#ifdef HAVE_SECURITY_PAM_MISC_H
+# include <security/pam_misc.h>
+#elif defined(HAVE_SECURITY_OPENPAM_H)
+# include <security/openpam.h>
+#endif
+#include <signal.h>
+#include <sys/wait.h>
+#include <syslog.h>
+#include <utmpx.h>
+
+#ifdef HAVE_PTY
+# include <pty.h>
+# include <poll.h>
+# include <sys/signalfd.h>
+# include "pty-session.h"
+# define USE_PTY
+#endif
+
+#include "err.h"
+
+#include <stdbool.h>
+
+#include "c.h"
+#include "xalloc.h"
+#include "nls.h"
+#include "pathnames.h"
+#include "env.h"
+#include "closestream.h"
+#include "strv.h"
+#include "strutils.h"
+#include "ttyutils.h"
+#include "pwdutils.h"
+#include "optutils.h"
+
+#include "logindefs.h"
+#include "su-common.h"
+
+#include "debug.h"
+
+UL_DEBUG_DEFINE_MASK(su);
+UL_DEBUG_DEFINE_MASKNAMES(su) = UL_DEBUG_EMPTY_MASKNAMES;
+
+#define SU_DEBUG_INIT		(1 << 1)
+#define SU_DEBUG_PAM		(1 << 2)
+#define SU_DEBUG_PARENT		(1 << 3)
+#define SU_DEBUG_TTY		(1 << 4)
+#define SU_DEBUG_LOG		(1 << 5)
+#define SU_DEBUG_MISC		(1 << 6)
+#define SU_DEBUG_SIG		(1 << 7)
+#define SU_DEBUG_PTY		(1 << 8)
+#define SU_DEBUG_ALL		0xFFFF
+
+#define DBG(m, x)       __UL_DBG(su, SU_DEBUG_, m, x)
+#define ON_DBG(m, x)    __UL_DBG_CALL(su, SU_DEBUG_, m, x)
+
+
+/* name of the pam configuration files. separate configs for su and su -  */
+#define PAM_SRVNAME_SU "su"
+#define PAM_SRVNAME_SU_L "su-l"
+
+#define PAM_SRVNAME_RUNUSER "runuser"
+#define PAM_SRVNAME_RUNUSER_L "runuser-l"
+
+#ifdef HAVE_LIBECONF
+#define _PATH_LOGINDEFS_SU	"default/su"
+#define _PATH_LOGINDEFS_RUNUSER "default/runuser"
+#else
+#define _PATH_LOGINDEFS_SU	"/etc/default/su"
+#define _PATH_LOGINDEFS_RUNUSER "/etc/default/runuser"
+#endif
+
+#define is_pam_failure(_rc)	((_rc) != PAM_SUCCESS)
+
+/* The shell to run if none is given in the user's passwd entry.  */
+#define DEFAULT_SHELL "/bin/sh"
+
+/* The user to become if none is specified.  */
+#define DEFAULT_USER "root"
+
+#ifndef HAVE_ENVIRON_DECL
+extern char **environ;
+#endif
+
+enum {
+	SIGTERM_IDX = 0,
+	SIGINT_IDX,
+	SIGQUIT_IDX,
+
+	SIGNALS_IDX_COUNT
+};
+
+/*
+ * su/runuser control struct
+ */
+struct su_context {
+	pam_handle_t	*pamh;			/* PAM handler */
+	struct pam_conv conv;			/* PAM conversation */
+
+	struct passwd	*pwd;			/* new user info */
+	char		*pwdbuf;		/* pwd strings */
+
+	const char	*tty_name;		/* tty_path without /dev prefix */
+	const char	*tty_number;		/* end of the tty_path */
+
+	char		*new_user;		/* wanted user */
+	char		*old_user;		/* original user */
+
+	pid_t		child;			/* fork() baby */
+	int		childstatus;		/* wait() status */
+
+	char		**env_whitelist_names;	/* environment whitelist */
+	char		**env_whitelist_vals;
+
+	struct sigaction oldact[SIGNALS_IDX_COUNT];	/* original sigactions indexed by SIG*_IDX */
+#ifdef USE_PTY
+	struct ul_pty	*pty;			/* pseudo terminal handler (for --pty) */
+#endif
+	unsigned int runuser :1,		/* flase=su, true=runuser */
+		     runuser_uopt :1,		/* runuser -u specified */
+		     isterm :1,			/* is stdin terminal? */
+		     fast_startup :1,		/* pass the `-f' option to the subshell. */
+		     simulate_login :1,		/* simulate a login instead of just starting a shell. */
+		     change_environment :1,	/* change some environment vars to indicate the user su'd to.*/
+		     same_session :1,		/* don't call setsid() with a command. */
+		     suppress_pam_info:1,	/* don't print PAM info messages (Last login, etc.). */
+		     pam_has_session :1,	/* PAM session opened */
+		     pam_has_cred :1,		/* PAM cred established */
+		     force_pty :1,		/* create pseudo-terminal */
+		     restricted :1;		/* false for root user */
+};
+
+
+static sig_atomic_t volatile caught_signal = false;
+
+/* Signal handler for parent process.  */
+static void
+su_catch_sig(int sig)
+{
+	caught_signal = sig;
+}
+
+static void su_init_debug(void)
+{
+	__UL_INIT_DEBUG_FROM_ENV(su, SU_DEBUG_, 0, SU_DEBUG);
+}
+
+static void init_tty(struct su_context *su)
+{
+	su->isterm = isatty(STDIN_FILENO) ? 1 : 0;
+	DBG(TTY, ul_debug("initialize [is-term=%s]", su->isterm ? "true" : "false"));
+	if (su->isterm)
+		get_terminal_name(NULL, &su->tty_name, &su->tty_number);
+}
+
+/*
+ * Note, this function has to be possible call more than once. If the child is
+ * already dead than it returns saved result from the previous call.
+ */
+static int wait_for_child(struct su_context *su)
+{
+	pid_t pid = (pid_t) -1;
+	int status = 0;
+
+	if (su->child == (pid_t) -1)
+		return su->childstatus;
+
+	if (su->child != (pid_t) -1) {
+		/*
+		 * The "su" parent process spends all time here in waitpid(),
+		 * but "su --pty" uses pty_proxy_master() and waitpid() is only
+		 * called to pick up child status or to react to SIGSTOP.
+		 */
+		DBG(SIG, ul_debug("waiting for child [%d]...", su->child));
+		for (;;) {
+			pid = waitpid(su->child, &status, WUNTRACED);
+
+			if (pid != (pid_t) - 1 && WIFSTOPPED(status)) {
+				DBG(SIG, ul_debug(" child got SIGSTOP -- stop all session"));
+				kill(getpid(), SIGSTOP);
+				/* once we get here, we must have resumed */
+				kill(pid, SIGCONT);
+				DBG(SIG, ul_debug(" session resumed -- continue"));
+#ifdef USE_PTY
+				/* Let's go back to pty_proxy_master() */
+				if (su->force_pty && ul_pty_is_running(su->pty)) {
+					DBG(SIG, ul_debug(" leaving on child SIGSTOP"));
+					return 0;
+				}
+#endif
+			} else
+				break;
+		}
+	}
+	if (pid != (pid_t) -1) {
+		if (WIFSIGNALED(status)) {
+			fprintf(stderr, "%s%s\n",
+				strsignal(WTERMSIG(status)),
+				WCOREDUMP(status) ? _(" (core dumped)")
+				: "");
+			status = WTERMSIG(status) + 128;
+		} else
+			status = WEXITSTATUS(status);
+
+		DBG(SIG, ul_debug("child %d is dead", su->child));
+		su->child = (pid_t) -1;	/* Don't use the PID anymore! */
+		su->childstatus = status;
+#ifdef USE_PTY
+		/* inform pty suff that we have no child anymore */
+		if (su->force_pty)
+			ul_pty_set_child(su->pty, (pid_t) -1);
+#endif
+	} else if (caught_signal)
+		status = caught_signal + 128;
+	else
+		status = 1;
+
+	DBG(SIG, ul_debug("child status=%d", status));
+	return status;
+}
+
+#ifdef USE_PTY
+static void wait_for_child_cb(
+			void *data,
+			pid_t child __attribute__((__unused__)))
+{
+	wait_for_child((struct su_context *) data);
+}
+#endif
+
+/* Log the fact that someone has run su to the user given by PW;
+   if SUCCESSFUL is true, they gave the correct password, etc.  */
+
+static void log_syslog(struct su_context *su, bool successful)
+{
+	DBG(LOG, ul_debug("syslog logging"));
+
+	openlog(program_invocation_short_name, 0, LOG_AUTH);
+	syslog(LOG_NOTICE, "%s(to %s) %s on %s",
+	       successful ? "" :
+	       su->runuser ? "FAILED RUNUSER " : "FAILED SU ",
+	       su->new_user, su->old_user ? : "",
+	       su->tty_name ? : "none");
+	closelog();
+}
+
+/*
+ * Log failed login attempts in _PATH_BTMP if that exists.
+ */
+static void log_btmp(struct su_context *su)
+{
+	struct utmpx ut;
+	struct timeval tv;
+
+	DBG(LOG, ul_debug("btmp logging"));
+
+	memset(&ut, 0, sizeof(ut));
+	str2memcpy(ut.ut_user,
+		su->pwd && su->pwd->pw_name ? su->pwd->pw_name : "(unknown)",
+		sizeof(ut.ut_user));
+
+	if (su->tty_number)
+		str2memcpy(ut.ut_id, su->tty_number, sizeof(ut.ut_id));
+	if (su->tty_name)
+		str2memcpy(ut.ut_line, su->tty_name, sizeof(ut.ut_line));
+
+	gettimeofday(&tv, NULL);
+	ut.ut_tv.tv_sec = tv.tv_sec;
+	ut.ut_tv.tv_usec = tv.tv_usec;
+	ut.ut_type = LOGIN_PROCESS;	/* XXX doesn't matter */
+	ut.ut_pid = getpid();
+
+	updwtmpx(_PATH_BTMP, &ut);
+}
+
+static int supam_conv(	int num_msg,
+			const struct pam_message **msg,
+			struct pam_response **resp,
+			void *data)
+{
+	struct su_context *su = (struct su_context *) data;
+
+	if (su->suppress_pam_info
+	    && num_msg == 1
+	    && msg && msg[0]->msg_style == PAM_TEXT_INFO)
+		return PAM_SUCCESS;
+
+#ifdef HAVE_SECURITY_PAM_MISC_H
+	return misc_conv(num_msg, msg, resp, data);
+#elif defined(HAVE_SECURITY_OPENPAM_H)
+	return openpam_ttyconv(num_msg, msg, resp, data);
+#endif
+}
+
+static void supam_cleanup(struct su_context *su, int retcode)
+{
+	const int errsv = errno;
+
+	DBG(PAM, ul_debug("cleanup"));
+
+	if (su->pam_has_session)
+		pam_close_session(su->pamh, 0);
+	if (su->pam_has_cred)
+		pam_setcred(su->pamh, PAM_DELETE_CRED | PAM_SILENT);
+	pam_end(su->pamh, retcode);
+	errno = errsv;
+}
+
+
+static void supam_export_environment(struct su_context *su)
+{
+	char **env;
+
+	DBG(PAM, ul_debug("init environ[]"));
+
+	/* This is a copy but don't care to free as we exec later anyways.  */
+	env = pam_getenvlist(su->pamh);
+
+	while (env && *env) {
+		if (putenv(*env) != 0)
+			err(EXIT_FAILURE, _("failed to modify environment"));
+		env++;
+	}
+}
+
+static void supam_authenticate(struct su_context *su)
+{
+	const char *srvname = NULL;
+	int rc;
+
+	srvname = su->runuser ?
+		   (su->simulate_login ? PAM_SRVNAME_RUNUSER_L : PAM_SRVNAME_RUNUSER) :
+		   (su->simulate_login ? PAM_SRVNAME_SU_L : PAM_SRVNAME_SU);
+
+	DBG(PAM, ul_debug("start [name: %s]", srvname));
+
+	rc = pam_start(srvname, su->pwd->pw_name, &su->conv, &su->pamh);
+	if (is_pam_failure(rc))
+		goto done;
+
+	if (su->tty_name) {
+		rc = pam_set_item(su->pamh, PAM_TTY, su->tty_name);
+		if (is_pam_failure(rc))
+			goto done;
+	}
+	if (su->old_user) {
+		rc = pam_set_item(su->pamh, PAM_RUSER, (const void *) su->old_user);
+		if (is_pam_failure(rc))
+			goto done;
+	}
+	if (su->runuser) {
+		/*
+		 * This is the only difference between runuser(1) and su(1). The command
+		 * runuser(1) does not required authentication, because user is root.
+		 */
+		if (su->restricted)
+			errx(EXIT_FAILURE, _("may not be used by non-root users"));
+		return;
+	}
+
+	rc = pam_authenticate(su->pamh, 0);
+	if (is_pam_failure(rc))
+		goto done;
+
+	/* Check password expiration and offer option to change it.  */
+	rc = pam_acct_mgmt(su->pamh, 0);
+	if (rc == PAM_NEW_AUTHTOK_REQD)
+		rc = pam_chauthtok(su->pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
+ done:
+	log_syslog(su, !is_pam_failure(rc));
+
+	if (is_pam_failure(rc)) {
+		const char *msg;
+
+		DBG(PAM, ul_debug("authentication failed"));
+		log_btmp(su);
+
+		msg = pam_strerror(su->pamh, rc);
+		pam_end(su->pamh, rc);
+		sleep(getlogindefs_num("FAIL_DELAY", 1));
+		errx(EXIT_FAILURE, "%s", msg ? msg : _("authentication failed"));
+	}
+}
+
+static void supam_open_session(struct su_context *su)
+{
+	int rc;
+
+	DBG(PAM, ul_debug("opening session"));
+
+	rc = pam_open_session(su->pamh, 0);
+	if (is_pam_failure(rc)) {
+		supam_cleanup(su, rc);
+		errx(EXIT_FAILURE, _("cannot open session: %s"),
+		     pam_strerror(su->pamh, rc));
+	} else
+		su->pam_has_session = 1;
+}
+
+static void parent_setup_signals(struct su_context *su)
+{
+	sigset_t ourset;
+
+	/*
+	 * Signals setup
+	 *
+	 * 1) block all signals
+	 */
+	DBG(SIG, ul_debug("initialize signals"));
+
+	sigfillset(&ourset);
+	if (sigprocmask(SIG_BLOCK, &ourset, NULL)) {
+		warn(_("cannot block signals"));
+		caught_signal = true;
+	}
+
+	if (!caught_signal) {
+		struct sigaction action;
+		action.sa_handler = su_catch_sig;
+		sigemptyset(&action.sa_mask);
+		action.sa_flags = 0;
+
+		sigemptyset(&ourset);
+
+		/* 2a) add wanted signals to the mask (for session) */
+		if (!su->same_session
+		    && (sigaddset(&ourset, SIGINT)
+		       || sigaddset(&ourset, SIGQUIT))) {
+
+			warn(_("cannot initialize signal mask for session"));
+			caught_signal = true;
+		}
+		/* 2b) add wanted generic signals to the mask */
+		if (!caught_signal
+		    && (sigaddset(&ourset, SIGTERM)
+		       || sigaddset(&ourset, SIGALRM))) {
+
+			warn(_("cannot initialize signal mask"));
+			caught_signal = true;
+		}
+
+		/* 3a) set signal handlers (for session) */
+		if (!caught_signal
+		    && !su->same_session
+		    && (sigaction(SIGINT, &action, &su->oldact[SIGINT_IDX])
+		       || sigaction(SIGQUIT, &action, &su->oldact[SIGQUIT_IDX]))) {
+
+			warn(_("cannot set signal handler for session"));
+			caught_signal = true;
+		}
+
+		/* 3b) set signal handlers */
+		if (!caught_signal
+		     && sigaction(SIGTERM, &action, &su->oldact[SIGTERM_IDX])) {
+
+			warn(_("cannot set signal handler"));
+			caught_signal = true;
+		}
+
+		/* 4) unblock wanted signals */
+		if (!caught_signal
+		    && sigprocmask(SIG_UNBLOCK, &ourset, NULL)) {
+
+			warn(_("cannot set signal mask"));
+			caught_signal = true;
+		}
+	}
+}
+
+
+static void create_watching_parent(struct su_context *su)
+{
+	int status;
+
+	DBG(MISC, ul_debug("forking..."));
+#ifdef USE_PTY
+	if (su->force_pty) {
+		struct ul_pty_callbacks *cb;
+
+		/* set callbacks */
+		ul_pty_set_callback_data(su->pty, (void *) su);
+
+		cb = ul_pty_get_callbacks(su->pty);
+		cb->child_wait    = wait_for_child_cb;
+		cb->child_sigstop = wait_for_child_cb;
+
+		/* create pty */
+		if (ul_pty_setup(su->pty))
+			err(EXIT_FAILURE, _("failed to create pseudo-terminal"));
+	}
+#endif
+	fflush(stdout);			/* ??? */
+
+	switch ((int) (su->child = fork())) {
+	case -1: /* error */
+		supam_cleanup(su, PAM_ABORT);
+#ifdef USE_PTY
+		if (su->force_pty)
+			ul_pty_cleanup(su->pty);
+#endif
+		err(EXIT_FAILURE, _("cannot create child process"));
+		break;
+
+	case 0: /* child */
+		return;
+
+	default: /* parent */
+		DBG(MISC, ul_debug("child [pid=%d]", (int) su->child));
+		break;
+	}
+
+	/* free unnecessary stuff */
+	free_getlogindefs_data();
+
+	/* In the parent watch the child.  */
+
+	/* su without pam support does not have a helper that keeps
+	   sitting on any directory so let's go to /.  */
+	if (chdir("/") != 0)
+		warn(_("cannot change directory to %s"), "/");
+#ifdef USE_PTY
+	if (su->force_pty) {
+		ul_pty_set_child(su->pty, su->child);
+
+		if (ul_pty_proxy_master(su->pty) != 0)
+			caught_signal = true;
+
+		/* ul_pty_proxy_master() keeps classic signal handler are out of game */
+		caught_signal = ul_pty_get_delivered_signal(su->pty);
+
+		ul_pty_cleanup(su->pty);
+	} else
+#endif
+		parent_setup_signals(su);
+
+	/*
+	 * Wait for child
+	 */
+	if (!caught_signal)
+		status = wait_for_child(su);
+	else
+		status = 1;
+
+	DBG(SIG, ul_debug("final child status=%d", status));
+
+	if (caught_signal && su->child != (pid_t)-1) {
+		fprintf(stderr, _("\nSession terminated, killing shell..."));
+		kill(su->child, SIGTERM);
+	}
+
+	supam_cleanup(su, PAM_SUCCESS);
+
+	if (caught_signal) {
+		if (su->child != (pid_t)-1) {
+			DBG(SIG, ul_debug("killing child"));
+			sleep(2);
+			kill(su->child, SIGKILL);
+			fprintf(stderr, _(" ...killed.\n"));
+		}
+
+		/* Let's terminate itself with the received signal.
+		 *
+		 * It seems that shells use WIFSIGNALED() rather than our exit status
+		 * value to detect situations when is necessary to cleanup (reset)
+		 * terminal settings (kzak -- Jun 2013).
+		 */
+		DBG(SIG, ul_debug("restore signals setting"));
+		switch (caught_signal) {
+		case SIGTERM:
+			sigaction(SIGTERM, &su->oldact[SIGTERM_IDX], NULL);
+			break;
+		case SIGINT:
+			sigaction(SIGINT, &su->oldact[SIGINT_IDX], NULL);
+			break;
+		case SIGQUIT:
+			sigaction(SIGQUIT, &su->oldact[SIGQUIT_IDX], NULL);
+			break;
+		default:
+			/* just in case that signal stuff initialization failed and
+			 * caught_signal = true */
+			caught_signal = SIGKILL;
+			break;
+		}
+		DBG(SIG, ul_debug("self-send %d signal", caught_signal));
+		kill(getpid(), caught_signal);
+	}
+
+	DBG(MISC, ul_debug("exiting [rc=%d]", status));
+	exit(status);
+}
+
+/* Adds @name from the current environment to the whitelist. If @name is not
+ * set then nothing is added to the whitelist and returns 1.
+ */
+static int env_whitelist_add(struct su_context *su, const char *name)
+{
+	const char *env = getenv(name);
+
+	if (!env)
+		return 1;
+	if (strv_extend(&su->env_whitelist_names, name))
+                err_oom();
+	if (strv_extend(&su->env_whitelist_vals, env))
+                err_oom();
+	return 0;
+}
+
+static int env_whitelist_setenv(struct su_context *su, int overwrite)
+{
+	char **one;
+	size_t i = 0;
+	int rc;
+
+	STRV_FOREACH(one, su->env_whitelist_names) {
+		rc = setenv(*one, su->env_whitelist_vals[i], overwrite);
+		if (rc)
+			return rc;
+		i++;
+	}
+
+	return 0;
+}
+
+/* Creates (add to) whitelist from comma delimited string */
+static int env_whitelist_from_string(struct su_context *su, const char *str)
+{
+	char **all = strv_split(str, ",");
+	char **one;
+
+	if (!all) {
+		if (errno == ENOMEM)
+			err_oom();
+		return -EINVAL;
+	}
+
+	STRV_FOREACH(one, all)
+		env_whitelist_add(su, *one);
+	strv_free(all);
+	return 0;
+}
+
+static void setenv_path(const struct passwd *pw)
+{
+	int rc;
+
+	DBG(MISC, ul_debug("setting PATH"));
+
+	if (pw->pw_uid)
+		rc = logindefs_setenv("PATH", "ENV_PATH", _PATH_DEFPATH);
+
+	else if ((rc = logindefs_setenv("PATH", "ENV_SUPATH", NULL)) != 0)
+		rc = logindefs_setenv("PATH", "ENV_ROOTPATH", _PATH_DEFPATH_ROOT);
+
+	if (rc)
+		err(EXIT_FAILURE, _("failed to set the PATH environment variable"));
+}
+
+static void modify_environment(struct su_context *su, const char *shell)
+{
+	const struct passwd *pw = su->pwd;
+
+
+	DBG(MISC, ul_debug("modify environ[]"));
+
+	/* Leave TERM unchanged.  Set HOME, SHELL, USER, LOGNAME, PATH.
+	 *
+	 * Unset all other environment variables, but follow
+	 * --whitelist-environment if specified.
+	 */
+	if (su->simulate_login) {
+		/* leave TERM unchanged */
+		env_whitelist_add(su, "TERM");
+
+		/* Note that original su(1) has allocated environ[] by malloc
+		 * to the number of expected variables. This seems unnecessary
+		 * optimization as libc later re-alloc(current_size+2) and for
+		 * empty environ[] the curren_size is zero. It seems better to
+		 * keep all logic around environment in glibc's hands.
+		 *                                           --kzak [Aug 2018]
+		 */
+#ifdef HAVE_CLEARENV
+		clearenv();
+#else
+		environ = NULL;
+#endif
+		/* always reset */
+		if (shell)
+			xsetenv("SHELL", shell, 1);
+
+		setenv_path(pw);
+
+		xsetenv("HOME", pw->pw_dir, 1);
+		xsetenv("USER", pw->pw_name, 1);
+		xsetenv("LOGNAME", pw->pw_name, 1);
+
+		/* apply all from whitelist, but no overwrite */
+		env_whitelist_setenv(su, 0);
+
+	/* Set HOME, SHELL, and (if not becoming a superuser) USER and LOGNAME.
+	 */
+	} else if (su->change_environment) {
+		xsetenv("HOME", pw->pw_dir, 1);
+		if (shell)
+			xsetenv("SHELL", shell, 1);
+
+		if (getlogindefs_bool("ALWAYS_SET_PATH", 0))
+			setenv_path(pw);
+
+		if (pw->pw_uid) {
+			xsetenv("USER", pw->pw_name, 1);
+			xsetenv("LOGNAME", pw->pw_name, 1);
+		}
+	}
+
+	supam_export_environment(su);
+}
+
+static void init_groups(struct su_context *su, gid_t *groups, size_t ngroups)
+{
+	int rc;
+
+	DBG(MISC, ul_debug("initialize groups"));
+
+	errno = 0;
+	if (ngroups)
+		rc = setgroups(ngroups, groups);
+	else
+		rc = initgroups(su->pwd->pw_name, su->pwd->pw_gid);
+
+	if (rc == -1) {
+		supam_cleanup(su, PAM_ABORT);
+		err(EXIT_FAILURE, _("cannot set groups"));
+	}
+	endgrent();
+
+	rc = pam_setcred(su->pamh, PAM_ESTABLISH_CRED);
+	if (is_pam_failure(rc))
+		errx(EXIT_FAILURE, _("failed to establish user credentials: %s"),
+					pam_strerror(su->pamh, rc));
+	su->pam_has_cred = 1;
+}
+
+static void change_identity(const struct passwd *pw)
+{
+	DBG(MISC, ul_debug("changing identity [GID=%d, UID=%d]", pw->pw_gid, pw->pw_uid));
+
+	if (setgid(pw->pw_gid))
+		err(EXIT_FAILURE, _("cannot set group id"));
+	if (setuid(pw->pw_uid))
+		err(EXIT_FAILURE, _("cannot set user id"));
+}
+
+/* Run SHELL, if COMMAND is nonzero, pass it to the shell with the -c option.
+ * Pass ADDITIONAL_ARGS to the shell as more arguments; there are
+ * N_ADDITIONAL_ARGS extra arguments.
+ */
+static void run_shell(
+		struct su_context *su,
+		char const *shell, char const *command, char **additional_args,
+		size_t n_additional_args)
+{
+	size_t n_args = 1 + su->fast_startup + 2 * ! !command + n_additional_args + 1;
+	const char **args = xcalloc(n_args, sizeof *args);
+	size_t argno = 1;
+
+	DBG(MISC, ul_debug("starting shell [shell=%s, command=\"%s\"%s%s]",
+				shell, command,
+				su->simulate_login ? " login" : "",
+				su->fast_startup ? " fast-start" : ""));
+
+	if (su->simulate_login) {
+		char *arg0;
+		char *shell_basename;
+
+		shell_basename = basename(shell);
+		arg0 = xmalloc(strlen(shell_basename) + 2);
+		arg0[0] = '-';
+		strcpy(arg0 + 1, shell_basename);
+		args[0] = arg0;
+	} else
+		args[0] = basename(shell);
+
+	if (su->fast_startup)
+		args[argno++] = "-f";
+	if (command) {
+		args[argno++] = "-c";
+		args[argno++] = command;
+	}
+
+	memcpy(args + argno, additional_args, n_additional_args * sizeof *args);
+	args[argno + n_additional_args] = NULL;
+	execv(shell, (char **)args);
+	errexec(shell);
+}
+
+/* Return true if SHELL is a restricted shell (one not returned by
+ * getusershell), else false, meaning it is a standard shell.
+ */
+static bool is_restricted_shell(const char *shell)
+{
+	char *line;
+
+	setusershell();
+	while ((line = getusershell()) != NULL) {
+		if (*line != '#' && !strcmp(line, shell)) {
+			endusershell();
+			return false;
+		}
+	}
+	endusershell();
+
+	DBG(MISC, ul_debug("%s is restricted shell (not in /etc/shells)", shell));
+	return true;
+}
+
+static void usage_common(void)
+{
+	fputs(_(" -m, -p, --preserve-environment      do not reset environment variables\n"), stdout);
+	fputs(_(" -w, --whitelist-environment <list>  don't reset specified variables\n"), stdout);
+	fputs(USAGE_SEPARATOR, stdout);
+
+	fputs(_(" -g, --group <group>             specify the primary group\n"), stdout);
+	fputs(_(" -G, --supp-group <group>        specify a supplemental group\n"), stdout);
+	fputs(USAGE_SEPARATOR, stdout);
+
+	fputs(_(" -, -l, --login                  make the shell a login shell\n"), stdout);
+	fputs(_(" -c, --command <command>         pass a single command to the shell with -c\n"), stdout);
+	fputs(_(" --session-command <command>     pass a single command to the shell with -c\n"
+	        "                                   and do not create a new session\n"), stdout);
+	fputs(_(" -f, --fast                      pass -f to the shell (for csh or tcsh)\n"), stdout);
+	fputs(_(" -s, --shell <shell>             run <shell> if /etc/shells allows it\n"), stdout);
+	fputs(_(" -P, --pty                       create a new pseudo-terminal\n"), stdout);
+
+	fputs(USAGE_SEPARATOR, stdout);
+	printf(USAGE_HELP_OPTIONS(33));
+}
+
+static void usage_runuser(void)
+{
+	fputs(USAGE_HEADER, stdout);
+	fprintf(stdout,
+		_(" %1$s [options] -u <user> [[--] <command>]\n"
+	          " %1$s [options] [-] [<user> [<argument>...]]\n"),
+		program_invocation_short_name);
+
+	fputs(USAGE_SEPARATOR, stdout);
+	fputs(_("Run <command> with the effective user ID and group ID of <user>.  If -u is\n"
+	       "not given, fall back to su(1)-compatible semantics and execute standard shell.\n"
+	       "The options -c, -f, -l, and -s are mutually exclusive with -u.\n"), stdout);
+
+	fputs(USAGE_OPTIONS, stdout);
+	fputs(_(" -u, --user <user>               username\n"), stdout);
+	usage_common();
+	fputs(USAGE_SEPARATOR, stdout);
+
+	fprintf(stdout, USAGE_MAN_TAIL("runuser(1)"));
+}
+
+static void usage_su(void)
+{
+	fputs(USAGE_HEADER, stdout);
+	fprintf(stdout,
+		_(" %s [options] [-] [<user> [<argument>...]]\n"),
+		program_invocation_short_name);
+
+	fputs(USAGE_SEPARATOR, stdout);
+	fputs(_("Change the effective user ID and group ID to that of <user>.\n"
+		"A mere - implies -l.  If <user> is not given, root is assumed.\n"), stdout);
+
+	fputs(USAGE_OPTIONS, stdout);
+	usage_common();
+
+	fprintf(stdout, USAGE_MAN_TAIL("su(1)"));
+}
+
+static void __attribute__((__noreturn__)) usage(int mode)
+{
+	if (mode == SU_MODE)
+		usage_su();
+	else
+		usage_runuser();
+
+	exit(EXIT_SUCCESS);
+}
+
+static void load_config(void *data)
+{
+	struct su_context *su = (struct su_context *) data;
+
+	DBG(MISC, ul_debug("loading logindefs"));
+#ifndef HAVE_LIBECONF
+	logindefs_load_file(_PATH_LOGINDEFS);
+#endif
+	logindefs_load_file(su->runuser ? _PATH_LOGINDEFS_RUNUSER : _PATH_LOGINDEFS_SU);
+}
+
+/*
+ * Returns 1 if the current user is not root
+ */
+static int is_not_root(void)
+{
+	const uid_t ruid = getuid();
+	const uid_t euid = geteuid();
+
+	/* if we're really root and aren't running setuid */
+	return (uid_t) 0 == ruid && ruid == euid ? 0 : 1;
+}
+
+static gid_t add_supp_group(const char *name, gid_t **groups, size_t *ngroups)
+{
+	struct group *gr;
+
+	if (*ngroups >= NGROUPS_MAX)
+		errx(EXIT_FAILURE,
+		     P_("specifying more than %d supplemental group is not possible",
+		        "specifying more than %d supplemental groups is not possible",
+			NGROUPS_MAX - 1), NGROUPS_MAX - 1);
+
+	gr = getgrnam(name);
+	if (!gr)
+		errx(EXIT_FAILURE, _("group %s does not exist"), name);
+
+	DBG(MISC, ul_debug("add %s group [name=%s, GID=%d]", name, gr->gr_name, (int) gr->gr_gid));
+
+	*groups = xrealloc(*groups, sizeof(gid_t) * (*ngroups + 1));
+	(*groups)[*ngroups] = gr->gr_gid;
+	(*ngroups)++;
+
+	return gr->gr_gid;
+}
+
+int su_main(int argc, char **argv, int mode)
+{
+	struct su_context _su = {
+		.conv			= { supam_conv, NULL },
+		.runuser		= (mode == RUNUSER_MODE ? 1 : 0),
+		.change_environment	= 1,
+		.new_user		= DEFAULT_USER
+	}, *su = &_su;
+
+	int optc;
+	char *command = NULL;
+	int request_same_session = 0;
+	char *shell = NULL;
+
+	gid_t *groups = NULL;
+	size_t ngroups = 0;
+	bool use_supp = false;
+	bool use_gid = false;
+	gid_t gid = 0;
+
+	static const struct option longopts[] = {
+		{"command", required_argument, NULL, 'c'},
+		{"session-command", required_argument, NULL, 'C'},
+		{"fast", no_argument, NULL, 'f'},
+		{"login", no_argument, NULL, 'l'},
+		{"preserve-environment", no_argument, NULL, 'p'},
+		{"pty", no_argument, NULL, 'P'},
+		{"shell", required_argument, NULL, 's'},
+		{"group", required_argument, NULL, 'g'},
+		{"supp-group", required_argument, NULL, 'G'},
+		{"user", required_argument, NULL, 'u'},	/* runuser only */
+		{"whitelist-environment", required_argument, NULL, 'w'},
+		{"help", no_argument, 0, 'h'},
+		{"version", no_argument, 0, 'V'},
+		{NULL, 0, NULL, 0}
+	};
+	static const ul_excl_t excl[] = {	/* rows and cols in ASCII order */
+		{ 'm', 'w' },			/* preserve-environment, whitelist-environment */
+		{ 'p', 'w' },			/* preserve-environment, whitelist-environment */
+		{ 0 }
+	};
+	int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
+
+	setlocale(LC_ALL, "");
+	bindtextdomain(PACKAGE, LOCALEDIR);
+	textdomain(PACKAGE);
+	close_stdout_atexit();
+
+	su_init_debug();
+	su->conv.appdata_ptr = (void *) su;
+
+	while ((optc =
+		getopt_long(argc, argv, "c:fg:G:lmpPs:u:hVw:", longopts,
+			    NULL)) != -1) {
+
+		err_exclusive_options(optc, longopts, excl, excl_st);
+
+		switch (optc) {
+		case 'c':
+			command = optarg;
+			break;
+
+		case 'C':
+			command = optarg;
+			request_same_session = 1;
+			break;
+
+		case 'f':
+			su->fast_startup = true;
+			break;
+
+		case 'g':
+			use_gid = true;
+			gid = add_supp_group(optarg, &groups, &ngroups);
+			break;
+
+		case 'G':
+			use_supp = true;
+			add_supp_group(optarg, &groups, &ngroups);
+			break;
+
+		case 'l':
+			su->simulate_login = true;
+			break;
+
+		case 'm':
+		case 'p':
+			su->change_environment = false;
+			break;
+
+		case 'w':
+			env_whitelist_from_string(su, optarg);
+			break;
+
+		case 'P':
+#ifdef USE_PTY
+			su->force_pty = 1;
+#else
+			errx(EXIT_FAILURE, _("--pty is not supported for your system"));
+#endif
+			break;
+
+		case 's':
+			shell = optarg;
+			break;
+
+		case 'u':
+			if (!su->runuser)
+				errtryhelp(EXIT_FAILURE);
+			su->runuser_uopt = 1;
+			su->new_user = optarg;
+			break;
+
+		case 'h':
+			usage(mode);
+
+		case 'V':
+			print_version(EXIT_SUCCESS);
+		default:
+			errtryhelp(EXIT_FAILURE);
+		}
+	}
+
+	su->restricted = is_not_root();
+
+	if (optind < argc && !strcmp(argv[optind], "-")) {
+		su->simulate_login = true;
+		++optind;
+	}
+
+	if (su->simulate_login && !su->change_environment) {
+		warnx(_
+		      ("ignoring --preserve-environment, it's mutually exclusive with --login"));
+		su->change_environment = true;
+	}
+
+	switch (mode) {
+	case RUNUSER_MODE:
+		/* runuser -u <user> <command>
+		 *
+		 * If -u <user> is not specified, then follow traditional su(1) behavior and
+		 * fallthrough
+		 */
+		if (su->runuser_uopt) {
+			if (shell || su->fast_startup || command || su->simulate_login)
+				errx(EXIT_FAILURE,
+				     _("options --{shell,fast,command,session-command,login} and "
+				      "--user are mutually exclusive"));
+			if (optind == argc)
+				errx(EXIT_FAILURE, _("no command was specified"));
+			break;
+		}
+		/* fallthrough */
+	case SU_MODE:
+		if (optind < argc)
+			su->new_user = argv[optind++];
+		break;
+	}
+
+	if ((use_supp || use_gid) && su->restricted)
+		errx(EXIT_FAILURE,
+		     _("only root can specify alternative groups"));
+
+	logindefs_set_loader(load_config, (void *) su);
+	init_tty(su);
+
+	su->pwd = xgetpwnam(su->new_user, &su->pwdbuf);
+	if (!su->pwd
+	    || !su->pwd->pw_passwd
+	    || !su->pwd->pw_name || !*su->pwd->pw_name
+	    || !su->pwd->pw_dir  || !*su->pwd->pw_dir)
+		errx(EXIT_FAILURE,
+		     _("user %s does not exist or the user entry does not "
+		       "contain all the required fields"), su->new_user);
+
+	su->new_user = su->pwd->pw_name;
+	su->old_user = xgetlogin();
+
+	if (!su->pwd->pw_shell || !*su->pwd->pw_shell)
+		su->pwd->pw_shell = DEFAULT_SHELL;
+
+	if (use_supp && !use_gid)
+		su->pwd->pw_gid = groups[0];
+	else if (use_gid)
+		su->pwd->pw_gid = gid;
+
+	supam_authenticate(su);
+
+	if (request_same_session || !command || !su->pwd->pw_uid)
+		su->same_session = 1;
+
+	/* initialize shell variable only if "-u <user>" not specified */
+	if (su->runuser_uopt) {
+		shell = NULL;
+	} else {
+		if (!shell && !su->change_environment)
+			shell = getenv("SHELL");
+
+		if (shell
+		    && strcmp(shell, su->pwd->pw_shell) != 0
+		    && getuid() != 0
+		    && is_restricted_shell(su->pwd->pw_shell)) {
+			/* The user being su'd to has a nonstandard shell, and
+			 * so is probably a uucp account or has restricted
+			 * access.  Don't compromise the account by allowing
+			 * access with a standard shell.
+			 */
+			warnx(_("using restricted shell %s"), su->pwd->pw_shell);
+			shell = NULL;
+		}
+		shell = xstrdup(shell ? shell : su->pwd->pw_shell);
+	}
+
+	init_groups(su, groups, ngroups);
+
+	if (!su->simulate_login || command)
+		su->suppress_pam_info = 1;	/* don't print PAM info messages */
+
+	supam_open_session(su);
+
+#ifdef USE_PTY
+	if (su->force_pty) {
+		ON_DBG(PTY, ul_pty_init_debug(0xffff));
+
+		su->pty = ul_new_pty(su->isterm);
+		if (!su->pty)
+			err(EXIT_FAILURE, _("failed to allocate pty handler"));
+	}
+#endif
+	create_watching_parent(su);
+	/* Now we're in the child.  */
+
+	change_identity(su->pwd);
+	if (!su->same_session) {
+		/* note that on --pty we call setsid() in ul_pty_init_slave() */
+		DBG(MISC, ul_debug("call setsid()"));
+		setsid();
+	}
+#ifdef USE_PTY
+	if (su->force_pty)
+		ul_pty_init_slave(su->pty);
+#endif
+	/* Set environment after pam_open_session, which may put KRB5CCNAME
+	   into the pam_env, etc.  */
+
+	modify_environment(su, shell);
+
+	if (su->simulate_login && chdir(su->pwd->pw_dir) != 0)
+		warn(_("warning: cannot change directory to %s"), su->pwd->pw_dir);
+
+	if (shell)
+		run_shell(su, shell, command, argv + optind, max(0, argc - optind));
+
+	execvp(argv[optind], &argv[optind]);
+	err(EXIT_FAILURE, _("failed to execute %s"), argv[optind]);
+}