summaryrefslogtreecommitdiffstats
path: root/login-utils/su-common.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 13:14:44 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 13:14:44 +0000
commit30ff6afe596eddafacf22b1a5b2d1a3d6254ea15 (patch)
tree9b788335f92174baf7ee18f03ca8330b8c19ce2b /login-utils/su-common.c
parentInitial commit. (diff)
downloadutil-linux-30ff6afe596eddafacf22b1a5b2d1a3d6254ea15.tar.xz
util-linux-30ff6afe596eddafacf22b1a5b2d1a3d6254ea15.zip
Adding upstream version 2.36.1.upstream/2.36.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'login-utils/su-common.c')
-rw-r--r--login-utils/su-common.c1215
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]);
+}