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| Current File : //compat/linux/proc/self/root/usr/src/usr.bin/su/su.c |
/*
* Copyright (c) 2002, 2005 Networks Associates Technologies, Inc.
* All rights reserved.
*
* Portions of this software were developed for the FreeBSD Project by
* ThinkSec AS and NAI Labs, the Security Research Division of Network
* Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
* ("CBOSS"), as part of the DARPA CHATS research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*-
* Copyright (c) 1988, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1988, 1993, 1994\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#if 0
#ifndef lint
static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94";
#endif /* not lint */
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/usr.bin/su/su.c 220055 2011-03-27 12:53:20Z ume $");
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#ifdef USE_BSM_AUDIT
#include <bsm/libbsm.h>
#include <bsm/audit_uevents.h>
#endif
#include <err.h>
#include <errno.h>
#include <grp.h>
#include <login_cap.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <stdarg.h>
#include <security/pam_appl.h>
#include <security/openpam.h>
#define PAM_END() do { \
int local_ret; \
if (pamh != NULL) { \
local_ret = pam_setcred(pamh, PAM_DELETE_CRED); \
if (local_ret != PAM_SUCCESS) \
syslog(LOG_ERR, "pam_setcred: %s", \
pam_strerror(pamh, local_ret)); \
if (asthem) { \
local_ret = pam_close_session(pamh, 0); \
if (local_ret != PAM_SUCCESS) \
syslog(LOG_ERR, "pam_close_session: %s",\
pam_strerror(pamh, local_ret)); \
} \
local_ret = pam_end(pamh, local_ret); \
if (local_ret != PAM_SUCCESS) \
syslog(LOG_ERR, "pam_end: %s", \
pam_strerror(pamh, local_ret)); \
} \
} while (0)
#define PAM_SET_ITEM(what, item) do { \
int local_ret; \
local_ret = pam_set_item(pamh, what, item); \
if (local_ret != PAM_SUCCESS) { \
syslog(LOG_ERR, "pam_set_item(" #what "): %s", \
pam_strerror(pamh, local_ret)); \
errx(1, "pam_set_item(" #what "): %s", \
pam_strerror(pamh, local_ret)); \
/* NOTREACHED */ \
} \
} while (0)
enum tristate { UNSET, YES, NO };
static pam_handle_t *pamh = NULL;
static char **environ_pam;
static char *ontty(void);
static int chshell(const char *);
static void usage(void) __dead2;
static void export_pam_environment(void);
static int ok_to_export(const char *);
extern char **environ;
int
main(int argc, char *argv[])
{
static char *cleanenv;
struct passwd *pwd = NULL;
struct pam_conv conv = { openpam_ttyconv, NULL };
enum tristate iscsh;
login_cap_t *lc;
union {
const char **a;
char * const *b;
} np;
uid_t ruid;
pid_t child_pid, child_pgrp, pid;
int asme, ch, asthem, fastlogin, prio, i, retcode,
statusp, setmaclabel;
u_int setwhat;
char *username, *class, shellbuf[MAXPATHLEN];
const char *p, *user, *shell, *mytty, **nargv;
const void *v;
struct sigaction sa, sa_int, sa_quit, sa_pipe;
int temp, fds[2];
#ifdef USE_BSM_AUDIT
const char *aerr;
au_id_t auid;
#endif
shell = class = cleanenv = NULL;
asme = asthem = fastlogin = statusp = 0;
user = "root";
iscsh = UNSET;
setmaclabel = 0;
while ((ch = getopt(argc, argv, "-flmsc:")) != -1)
switch ((char)ch) {
case 'f':
fastlogin = 1;
break;
case '-':
case 'l':
asme = 0;
asthem = 1;
break;
case 'm':
asme = 1;
asthem = 0;
break;
case 's':
setmaclabel = 1;
break;
case 'c':
class = optarg;
break;
case '?':
default:
usage();
/* NOTREACHED */
}
if (optind < argc)
user = argv[optind++];
if (user == NULL)
usage();
/* NOTREACHED */
/*
* Try to provide more helpful debugging output if su(1) is running
* non-setuid, or was run from a file system not mounted setuid.
*/
if (geteuid() != 0)
errx(1, "not running setuid");
#ifdef USE_BSM_AUDIT
if (getauid(&auid) < 0 && errno != ENOSYS) {
syslog(LOG_AUTH | LOG_ERR, "getauid: %s", strerror(errno));
errx(1, "Permission denied");
}
#endif
if (strlen(user) > MAXLOGNAME - 1) {
#ifdef USE_BSM_AUDIT
if (audit_submit(AUE_su, auid,
EPERM, 1, "username too long: '%s'", user))
errx(1, "Permission denied");
#endif
errx(1, "username too long");
}
nargv = malloc(sizeof(char *) * (size_t)(argc + 4));
if (nargv == NULL)
errx(1, "malloc failure");
nargv[argc + 3] = NULL;
for (i = argc; i >= optind; i--)
nargv[i + 3] = argv[i];
np.a = &nargv[i + 3];
argv += optind;
errno = 0;
prio = getpriority(PRIO_PROCESS, 0);
if (errno)
prio = 0;
setpriority(PRIO_PROCESS, 0, -2);
openlog("su", LOG_CONS, LOG_AUTH);
/* get current login name, real uid and shell */
ruid = getuid();
username = getlogin();
if (username != NULL)
pwd = getpwnam(username);
if (pwd == NULL || pwd->pw_uid != ruid)
pwd = getpwuid(ruid);
if (pwd == NULL) {
#ifdef USE_BSM_AUDIT
if (audit_submit(AUE_su, auid, EPERM, 1,
"unable to determine invoking subject: '%s'", username))
errx(1, "Permission denied");
#endif
errx(1, "who are you?");
}
username = strdup(pwd->pw_name);
if (username == NULL)
err(1, "strdup failure");
if (asme) {
if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') {
/* must copy - pwd memory is recycled */
shell = strncpy(shellbuf, pwd->pw_shell,
sizeof(shellbuf));
shellbuf[sizeof(shellbuf) - 1] = '\0';
}
else {
shell = _PATH_BSHELL;
iscsh = NO;
}
}
/* Do the whole PAM startup thing */
retcode = pam_start("su", user, &conv, &pamh);
if (retcode != PAM_SUCCESS) {
syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, retcode));
errx(1, "pam_start: %s", pam_strerror(pamh, retcode));
}
PAM_SET_ITEM(PAM_RUSER, username);
mytty = ttyname(STDERR_FILENO);
if (!mytty)
mytty = "tty";
PAM_SET_ITEM(PAM_TTY, mytty);
retcode = pam_authenticate(pamh, 0);
if (retcode != PAM_SUCCESS) {
#ifdef USE_BSM_AUDIT
if (audit_submit(AUE_su, auid, EPERM, 1, "bad su %s to %s on %s",
username, user, mytty))
errx(1, "Permission denied");
#endif
syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s on %s",
username, user, mytty);
errx(1, "Sorry");
}
#ifdef USE_BSM_AUDIT
if (audit_submit(AUE_su, auid, 0, 0, "successful authentication"))
errx(1, "Permission denied");
#endif
retcode = pam_get_item(pamh, PAM_USER, &v);
if (retcode == PAM_SUCCESS)
user = v;
else
syslog(LOG_ERR, "pam_get_item(PAM_USER): %s",
pam_strerror(pamh, retcode));
pwd = getpwnam(user);
if (pwd == NULL) {
#ifdef USE_BSM_AUDIT
if (audit_submit(AUE_su, auid, EPERM, 1,
"unknown subject: %s", user))
errx(1, "Permission denied");
#endif
errx(1, "unknown login: %s", user);
}
retcode = pam_acct_mgmt(pamh, 0);
if (retcode == PAM_NEW_AUTHTOK_REQD) {
retcode = pam_chauthtok(pamh,
PAM_CHANGE_EXPIRED_AUTHTOK);
if (retcode != PAM_SUCCESS) {
#ifdef USE_BSM_AUDIT
aerr = pam_strerror(pamh, retcode);
if (aerr == NULL)
aerr = "Unknown PAM error";
if (audit_submit(AUE_su, auid, EPERM, 1,
"pam_chauthtok: %s", aerr))
errx(1, "Permission denied");
#endif
syslog(LOG_ERR, "pam_chauthtok: %s",
pam_strerror(pamh, retcode));
errx(1, "Sorry");
}
}
if (retcode != PAM_SUCCESS) {
#ifdef USE_BSM_AUDIT
if (audit_submit(AUE_su, auid, EPERM, 1, "pam_acct_mgmt: %s",
pam_strerror(pamh, retcode)))
errx(1, "Permission denied");
#endif
syslog(LOG_ERR, "pam_acct_mgmt: %s",
pam_strerror(pamh, retcode));
errx(1, "Sorry");
}
/* get target login information */
if (class == NULL)
lc = login_getpwclass(pwd);
else {
if (ruid != 0) {
#ifdef USE_BSM_AUDIT
if (audit_submit(AUE_su, auid, EPERM, 1,
"only root may use -c"))
errx(1, "Permission denied");
#endif
errx(1, "only root may use -c");
}
lc = login_getclass(class);
if (lc == NULL)
errx(1, "unknown class: %s", class);
}
/* if asme and non-standard target shell, must be root */
if (asme) {
if (ruid != 0 && !chshell(pwd->pw_shell))
errx(1, "permission denied (shell)");
}
else if (pwd->pw_shell && *pwd->pw_shell) {
shell = pwd->pw_shell;
iscsh = UNSET;
}
else {
shell = _PATH_BSHELL;
iscsh = NO;
}
/* if we're forking a csh, we want to slightly muck the args */
if (iscsh == UNSET) {
p = strrchr(shell, '/');
if (p)
++p;
else
p = shell;
iscsh = strcmp(p, "csh") ? (strcmp(p, "tcsh") ? NO : YES) : YES;
}
setpriority(PRIO_PROCESS, 0, prio);
/*
* PAM modules might add supplementary groups in pam_setcred(), so
* initialize them first.
*/
if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0)
err(1, "setusercontext");
retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
if (retcode != PAM_SUCCESS) {
syslog(LOG_ERR, "pam_setcred: %s",
pam_strerror(pamh, retcode));
errx(1, "failed to establish credentials.");
}
if (asthem) {
retcode = pam_open_session(pamh, 0);
if (retcode != PAM_SUCCESS) {
syslog(LOG_ERR, "pam_open_session: %s",
pam_strerror(pamh, retcode));
errx(1, "failed to open session.");
}
}
/*
* We must fork() before setuid() because we need to call
* pam_setcred(pamh, PAM_DELETE_CRED) as root.
*/
sa.sa_flags = SA_RESTART;
sa.sa_handler = SIG_IGN;
sigemptyset(&sa.sa_mask);
sigaction(SIGINT, &sa, &sa_int);
sigaction(SIGQUIT, &sa, &sa_quit);
sigaction(SIGPIPE, &sa, &sa_pipe);
sa.sa_handler = SIG_DFL;
sigaction(SIGTSTP, &sa, NULL);
statusp = 1;
if (pipe(fds) == -1) {
PAM_END();
err(1, "pipe");
}
child_pid = fork();
switch (child_pid) {
default:
sa.sa_handler = SIG_IGN;
sigaction(SIGTTOU, &sa, NULL);
close(fds[0]);
setpgid(child_pid, child_pid);
if (tcgetpgrp(STDERR_FILENO) == getpgrp())
tcsetpgrp(STDERR_FILENO, child_pid);
close(fds[1]);
sigaction(SIGPIPE, &sa_pipe, NULL);
while ((pid = waitpid(child_pid, &statusp, WUNTRACED)) != -1) {
if (WIFSTOPPED(statusp)) {
child_pgrp = getpgid(child_pid);
if (tcgetpgrp(STDERR_FILENO) == child_pgrp)
tcsetpgrp(STDERR_FILENO, getpgrp());
kill(getpid(), SIGSTOP);
if (tcgetpgrp(STDERR_FILENO) == getpgrp()) {
child_pgrp = getpgid(child_pid);
tcsetpgrp(STDERR_FILENO, child_pgrp);
}
kill(child_pid, SIGCONT);
statusp = 1;
continue;
}
break;
}
tcsetpgrp(STDERR_FILENO, getpgrp());
if (pid == -1)
err(1, "waitpid");
PAM_END();
exit(WEXITSTATUS(statusp));
case -1:
PAM_END();
err(1, "fork");
case 0:
close(fds[1]);
read(fds[0], &temp, 1);
close(fds[0]);
sigaction(SIGPIPE, &sa_pipe, NULL);
sigaction(SIGINT, &sa_int, NULL);
sigaction(SIGQUIT, &sa_quit, NULL);
/*
* Set all user context except for: Environmental variables
* Umask Login records (wtmp, etc) Path
*/
setwhat = LOGIN_SETALL & ~(LOGIN_SETENV | LOGIN_SETUMASK |
LOGIN_SETLOGIN | LOGIN_SETPATH | LOGIN_SETGROUP |
LOGIN_SETMAC);
/*
* If -s is present, also set the MAC label.
*/
if (setmaclabel)
setwhat |= LOGIN_SETMAC;
/*
* Don't touch resource/priority settings if -m has been used
* or -l and -c hasn't, and we're not su'ing to root.
*/
if ((asme || (!asthem && class == NULL)) && pwd->pw_uid)
setwhat &= ~(LOGIN_SETPRIORITY | LOGIN_SETRESOURCES);
if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0)
err(1, "setusercontext");
if (!asme) {
if (asthem) {
p = getenv("TERM");
environ = &cleanenv;
}
if (asthem || pwd->pw_uid)
setenv("USER", pwd->pw_name, 1);
setenv("HOME", pwd->pw_dir, 1);
setenv("SHELL", shell, 1);
if (asthem) {
/*
* Add any environmental variables that the
* PAM modules may have set.
*/
environ_pam = pam_getenvlist(pamh);
if (environ_pam)
export_pam_environment();
/* set the su'd user's environment & umask */
setusercontext(lc, pwd, pwd->pw_uid,
LOGIN_SETPATH | LOGIN_SETUMASK |
LOGIN_SETENV);
if (p)
setenv("TERM", p, 1);
p = pam_getenv(pamh, "HOME");
if (chdir(p ? p : pwd->pw_dir) < 0)
errx(1, "no directory");
}
}
login_close(lc);
if (iscsh == YES) {
if (fastlogin)
*np.a-- = "-f";
if (asme)
*np.a-- = "-m";
}
/* csh strips the first character... */
*np.a = asthem ? "-su" : iscsh == YES ? "_su" : "su";
if (ruid != 0)
syslog(LOG_NOTICE, "%s to %s%s", username, user,
ontty());
execv(shell, np.b);
err(1, "%s", shell);
}
}
static void
export_pam_environment(void)
{
char **pp;
char *p;
for (pp = environ_pam; *pp != NULL; pp++) {
if (ok_to_export(*pp)) {
p = strchr(*pp, '=');
*p = '\0';
setenv(*pp, p + 1, 1);
}
free(*pp);
}
}
/*
* Sanity checks on PAM environmental variables:
* - Make sure there is an '=' in the string.
* - Make sure the string doesn't run on too long.
* - Do not export certain variables. This list was taken from the
* Solaris pam_putenv(3) man page.
* Note that if the user is chrooted, PAM may have a better idea than we
* do of where her home directory is.
*/
static int
ok_to_export(const char *s)
{
static const char *noexport[] = {
"SHELL", /* "HOME", */ "LOGNAME", "MAIL", "CDPATH",
"IFS", "PATH", NULL
};
const char **pp;
size_t n;
if (strlen(s) > 1024 || strchr(s, '=') == NULL)
return 0;
if (strncmp(s, "LD_", 3) == 0)
return 0;
for (pp = noexport; *pp != NULL; pp++) {
n = strlen(*pp);
if (s[n] == '=' && strncmp(s, *pp, n) == 0)
return 0;
}
return 1;
}
static void
usage(void)
{
fprintf(stderr, "usage: su [-] [-flms] [-c class] [login [args]]\n");
exit(1);
/* NOTREACHED */
}
static int
chshell(const char *sh)
{
int r;
char *cp;
r = 0;
setusershell();
while ((cp = getusershell()) != NULL && !r)
r = (strcmp(cp, sh) == 0);
endusershell();
return r;
}
static char *
ontty(void)
{
char *p;
static char buf[MAXPATHLEN + 4];
buf[0] = 0;
p = ttyname(STDERR_FILENO);
if (p)
snprintf(buf, sizeof(buf), " on %s", p);
return buf;
}