1209 lines
30 KiB
C
1209 lines
30 KiB
C
/*
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* su(1) for Linux. Run a shell with substitute user and group IDs.
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*
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* Copyright (C) 1992-2006 Free Software Foundation, Inc.
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* Copyright (C) 2012 SUSE Linux Products GmbH, Nuernberg
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* Copyright (C) 2016-2017 Karel Zak <kzak@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2, or (at your option) any later
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* version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details. You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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* USA.
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*
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*
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* Based on an implementation by David MacKenzie <djm@gnu.ai.mit.edu>.
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*/
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#include <stdio.h>
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#include <getopt.h>
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#include <sys/types.h>
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#include <pwd.h>
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#include <grp.h>
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#include <security/pam_appl.h>
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#ifdef HAVE_SECURITY_PAM_MISC_H
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# include <security/pam_misc.h>
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#elif defined(HAVE_SECURITY_OPENPAM_H)
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# include <security/openpam.h>
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#endif
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#include <signal.h>
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#include <sys/wait.h>
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#include <syslog.h>
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#include <utmpx.h>
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#ifdef HAVE_PTY
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# include <pty.h>
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# include <poll.h>
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# include <sys/signalfd.h>
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# include "pty-session.h"
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# define USE_PTY
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#endif
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#include "err.h"
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#include <stdbool.h>
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#include "c.h"
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#include "xalloc.h"
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#include "nls.h"
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#include "pathnames.h"
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#include "env.h"
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#include "closestream.h"
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#include "strv.h"
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#include "strutils.h"
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#include "ttyutils.h"
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#include "pwdutils.h"
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#include "optutils.h"
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#include "logindefs.h"
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#include "su-common.h"
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#include "debug.h"
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UL_DEBUG_DEFINE_MASK(su);
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UL_DEBUG_DEFINE_MASKNAMES(su) = UL_DEBUG_EMPTY_MASKNAMES;
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#define SU_DEBUG_INIT (1 << 1)
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#define SU_DEBUG_PAM (1 << 2)
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#define SU_DEBUG_PARENT (1 << 3)
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#define SU_DEBUG_TTY (1 << 4)
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#define SU_DEBUG_LOG (1 << 5)
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#define SU_DEBUG_MISC (1 << 6)
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#define SU_DEBUG_SIG (1 << 7)
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#define SU_DEBUG_PTY (1 << 8)
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#define SU_DEBUG_ALL 0xFFFF
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#define DBG(m, x) __UL_DBG(su, SU_DEBUG_, m, x)
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#define ON_DBG(m, x) __UL_DBG_CALL(su, SU_DEBUG_, m, x)
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/* name of the pam configuration files. separate configs for su and su - */
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#define PAM_SRVNAME_SU "su"
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#define PAM_SRVNAME_SU_L "su-l"
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#define PAM_SRVNAME_RUNUSER "runuser"
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#define PAM_SRVNAME_RUNUSER_L "runuser-l"
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#define _PATH_LOGINDEFS_SU "/etc/default/su"
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#define _PATH_LOGINDEFS_RUNUSER "/etc/default/runuser"
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#define is_pam_failure(_rc) ((_rc) != PAM_SUCCESS)
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/* The shell to run if none is given in the user's passwd entry. */
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#define DEFAULT_SHELL "/bin/sh"
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/* The user to become if none is specified. */
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#define DEFAULT_USER "root"
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#ifndef HAVE_ENVIRON_DECL
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extern char **environ;
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#endif
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enum {
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SIGTERM_IDX = 0,
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SIGINT_IDX,
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SIGQUIT_IDX,
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SIGNALS_IDX_COUNT
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};
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/*
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* su/runuser control struct
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*/
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struct su_context {
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pam_handle_t *pamh; /* PAM handler */
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struct pam_conv conv; /* PAM conversation */
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struct passwd *pwd; /* new user info */
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char *pwdbuf; /* pwd strings */
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const char *tty_name; /* tty_path without /dev prefix */
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const char *tty_number; /* end of the tty_path */
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char *new_user; /* wanted user */
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char *old_user; /* original user */
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pid_t child; /* fork() baby */
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int childstatus; /* wait() status */
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char **env_whitelist_names; /* environment whitelist */
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char **env_whitelist_vals;
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struct sigaction oldact[SIGNALS_IDX_COUNT]; /* original sigactions indexed by SIG*_IDX */
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#ifdef USE_PTY
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struct ul_pty *pty; /* pseudo terminal handler (for --pty) */
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#endif
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unsigned int runuser :1, /* flase=su, true=runuser */
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runuser_uopt :1, /* runuser -u specified */
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isterm :1, /* is stdin terminal? */
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fast_startup :1, /* pass the `-f' option to the subshell. */
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simulate_login :1, /* simulate a login instead of just starting a shell. */
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change_environment :1, /* change some environment vars to indicate the user su'd to.*/
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same_session :1, /* don't call setsid() with a command. */
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suppress_pam_info:1, /* don't print PAM info messages (Last login, etc.). */
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pam_has_session :1, /* PAM session opened */
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pam_has_cred :1, /* PAM cred established */
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force_pty :1, /* create pseudo-terminal */
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restricted :1; /* false for root user */
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};
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static sig_atomic_t volatile caught_signal = false;
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/* Signal handler for parent process. */
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static void
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su_catch_sig(int sig)
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{
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caught_signal = sig;
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}
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static void su_init_debug(void)
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{
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__UL_INIT_DEBUG_FROM_ENV(su, SU_DEBUG_, 0, SU_DEBUG);
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}
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static void init_tty(struct su_context *su)
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{
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su->isterm = isatty(STDIN_FILENO) ? 1 : 0;
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DBG(TTY, ul_debug("initialize [is-term=%s]", su->isterm ? "true" : "false"));
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if (su->isterm)
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get_terminal_name(NULL, &su->tty_name, &su->tty_number);
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}
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/*
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* Note, this function has to be possible call more than once. If the child is
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* already dead than it returns saved result from the previous call.
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*/
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static int wait_for_child(struct su_context *su)
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{
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pid_t pid = (pid_t) -1;
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int status = 0;
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if (su->child == (pid_t) -1)
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return su->childstatus;
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if (su->child != (pid_t) -1) {
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/*
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* The "su" parent process spends all time here in waitpid(),
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* but "su --pty" uses pty_proxy_master() and waitpid() is only
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* called to pick up child status or to react to SIGSTOP.
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*/
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DBG(SIG, ul_debug("waiting for child [%d]...", su->child));
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for (;;) {
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pid = waitpid(su->child, &status, WUNTRACED);
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if (pid != (pid_t) - 1 && WIFSTOPPED(status)) {
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DBG(SIG, ul_debug(" child got SIGSTOP -- stop all session"));
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kill(getpid(), SIGSTOP);
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/* once we get here, we must have resumed */
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kill(pid, SIGCONT);
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DBG(SIG, ul_debug(" session resumed -- continue"));
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#ifdef USE_PTY
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/* Let's go back to pty_proxy_master() */
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if (su->force_pty && ul_pty_is_running(su->pty)) {
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DBG(SIG, ul_debug(" leaving on child SIGSTOP"));
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return 0;
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}
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#endif
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} else
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break;
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}
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}
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if (pid != (pid_t) -1) {
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if (WIFSIGNALED(status)) {
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fprintf(stderr, "%s%s\n",
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strsignal(WTERMSIG(status)),
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WCOREDUMP(status) ? _(" (core dumped)")
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: "");
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status = WTERMSIG(status) + 128;
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} else
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status = WEXITSTATUS(status);
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DBG(SIG, ul_debug("child %d is dead", su->child));
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su->child = (pid_t) -1; /* Don't use the PID anymore! */
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su->childstatus = status;
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#ifdef USE_PTY
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/* inform pty suff that we have no child anymore */
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if (su->force_pty)
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ul_pty_set_child(su->pty, (pid_t) -1);
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#endif
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} else if (caught_signal)
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status = caught_signal + 128;
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else
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status = 1;
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DBG(SIG, ul_debug("child status=%d", status));
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return status;
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}
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#ifdef USE_PTY
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static void wait_for_child_cb(
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void *data,
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pid_t child __attribute__((__unused__)))
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{
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wait_for_child((struct su_context *) data);
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}
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#endif
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/* Log the fact that someone has run su to the user given by PW;
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if SUCCESSFUL is true, they gave the correct password, etc. */
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static void log_syslog(struct su_context *su, bool successful)
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{
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DBG(LOG, ul_debug("syslog logging"));
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openlog(program_invocation_short_name, 0, LOG_AUTH);
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syslog(LOG_NOTICE, "%s(to %s) %s on %s",
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successful ? "" :
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su->runuser ? "FAILED RUNUSER " : "FAILED SU ",
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su->new_user, su->old_user ? : "",
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su->tty_name ? : "none");
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closelog();
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}
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/*
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* Log failed login attempts in _PATH_BTMP if that exists.
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*/
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static void log_btmp(struct su_context *su)
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{
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struct utmpx ut;
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struct timeval tv;
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DBG(LOG, ul_debug("btmp logging"));
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memset(&ut, 0, sizeof(ut));
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str2memcpy(ut.ut_user,
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su->pwd && su->pwd->pw_name ? su->pwd->pw_name : "(unknown)",
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sizeof(ut.ut_user));
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if (su->tty_number)
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str2memcpy(ut.ut_id, su->tty_number, sizeof(ut.ut_id));
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if (su->tty_name)
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str2memcpy(ut.ut_line, su->tty_name, sizeof(ut.ut_line));
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gettimeofday(&tv, NULL);
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ut.ut_tv.tv_sec = tv.tv_sec;
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ut.ut_tv.tv_usec = tv.tv_usec;
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ut.ut_type = LOGIN_PROCESS; /* XXX doesn't matter */
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ut.ut_pid = getpid();
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updwtmpx(_PATH_BTMP, &ut);
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}
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static int supam_conv( int num_msg,
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const struct pam_message **msg,
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struct pam_response **resp,
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void *data)
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{
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struct su_context *su = (struct su_context *) data;
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if (su->suppress_pam_info
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&& num_msg == 1
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&& msg && msg[0]->msg_style == PAM_TEXT_INFO)
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return PAM_SUCCESS;
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#ifdef HAVE_SECURITY_PAM_MISC_H
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return misc_conv(num_msg, msg, resp, data);
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#elif defined(HAVE_SECURITY_OPENPAM_H)
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return openpam_ttyconv(num_msg, msg, resp, data);
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#endif
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}
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static void supam_cleanup(struct su_context *su, int retcode)
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{
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const int errsv = errno;
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DBG(PAM, ul_debug("cleanup"));
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if (su->pam_has_session)
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pam_close_session(su->pamh, 0);
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if (su->pam_has_cred)
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pam_setcred(su->pamh, PAM_DELETE_CRED | PAM_SILENT);
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pam_end(su->pamh, retcode);
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errno = errsv;
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}
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static void supam_export_environment(struct su_context *su)
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{
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char **env;
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DBG(PAM, ul_debug("init environ[]"));
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/* This is a copy but don't care to free as we exec later anyways. */
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env = pam_getenvlist(su->pamh);
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while (env && *env) {
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if (putenv(*env) != 0)
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err(EXIT_FAILURE, _("failed to modify environment"));
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env++;
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}
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}
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static void supam_authenticate(struct su_context *su)
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{
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const char *srvname = NULL;
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int rc;
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srvname = su->runuser ?
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(su->simulate_login ? PAM_SRVNAME_RUNUSER_L : PAM_SRVNAME_RUNUSER) :
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(su->simulate_login ? PAM_SRVNAME_SU_L : PAM_SRVNAME_SU);
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DBG(PAM, ul_debug("start [name: %s]", srvname));
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rc = pam_start(srvname, su->pwd->pw_name, &su->conv, &su->pamh);
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if (is_pam_failure(rc))
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goto done;
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if (su->tty_name) {
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rc = pam_set_item(su->pamh, PAM_TTY, su->tty_name);
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if (is_pam_failure(rc))
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goto done;
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}
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if (su->old_user) {
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rc = pam_set_item(su->pamh, PAM_RUSER, (const void *) su->old_user);
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if (is_pam_failure(rc))
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goto done;
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}
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if (su->runuser) {
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/*
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* This is the only difference between runuser(1) and su(1). The command
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* runuser(1) does not required authentication, because user is root.
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*/
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if (su->restricted)
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errx(EXIT_FAILURE, _("may not be used by non-root users"));
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return;
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}
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rc = pam_authenticate(su->pamh, 0);
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if (is_pam_failure(rc))
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goto done;
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/* Check password expiration and offer option to change it. */
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rc = pam_acct_mgmt(su->pamh, 0);
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if (rc == PAM_NEW_AUTHTOK_REQD)
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rc = pam_chauthtok(su->pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
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done:
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log_syslog(su, !is_pam_failure(rc));
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if (is_pam_failure(rc)) {
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const char *msg;
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DBG(PAM, ul_debug("authentication failed"));
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log_btmp(su);
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msg = pam_strerror(su->pamh, rc);
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pam_end(su->pamh, rc);
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sleep(getlogindefs_num("FAIL_DELAY", 1));
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errx(EXIT_FAILURE, "%s", msg ? msg : _("authentication failed"));
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}
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}
|
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|
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static void supam_open_session(struct su_context *su)
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{
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int rc;
|
|
|
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DBG(PAM, ul_debug("opening session"));
|
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|
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rc = pam_open_session(su->pamh, 0);
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if (is_pam_failure(rc)) {
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supam_cleanup(su, rc);
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errx(EXIT_FAILURE, _("cannot open session: %s"),
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pam_strerror(su->pamh, rc));
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} else
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su->pam_has_session = 1;
|
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}
|
|
|
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static void parent_setup_signals(struct su_context *su)
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{
|
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sigset_t ourset;
|
|
|
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/*
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* Signals setup
|
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*
|
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* 1) block all signals
|
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*/
|
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DBG(SIG, ul_debug("initialize signals"));
|
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|
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sigfillset(&ourset);
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if (sigprocmask(SIG_BLOCK, &ourset, NULL)) {
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warn(_("cannot block signals"));
|
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caught_signal = true;
|
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}
|
|
|
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if (!caught_signal) {
|
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struct sigaction action;
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action.sa_handler = su_catch_sig;
|
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sigemptyset(&action.sa_mask);
|
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action.sa_flags = 0;
|
|
|
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sigemptyset(&ourset);
|
|
|
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/* 2a) add wanted signals to the mask (for session) */
|
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if (!su->same_session
|
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&& (sigaddset(&ourset, SIGINT)
|
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|| sigaddset(&ourset, SIGQUIT))) {
|
|
|
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warn(_("cannot initialize signal mask for session"));
|
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caught_signal = true;
|
|
}
|
|
/* 2b) add wanted generic signals to the mask */
|
|
if (!caught_signal
|
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&& (sigaddset(&ourset, SIGTERM)
|
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|| sigaddset(&ourset, SIGALRM))) {
|
|
|
|
warn(_("cannot initialize signal mask"));
|
|
caught_signal = true;
|
|
}
|
|
|
|
/* 3a) set signal handlers (for session) */
|
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if (!caught_signal
|
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&& !su->same_session
|
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&& (sigaction(SIGINT, &action, &su->oldact[SIGINT_IDX])
|
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|| sigaction(SIGQUIT, &action, &su->oldact[SIGQUIT_IDX]))) {
|
|
|
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warn(_("cannot set signal handler for session"));
|
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caught_signal = true;
|
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}
|
|
|
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/* 3b) set signal handlers */
|
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if (!caught_signal
|
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&& sigaction(SIGTERM, &action, &su->oldact[SIGTERM_IDX])) {
|
|
|
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warn(_("cannot set signal handler"));
|
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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"));
|
|
logindefs_load_file(_PATH_LOGINDEFS);
|
|
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)
|
|
&& 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]);
|
|
}
|