NetBSD-5.0.2/usr.bin/su/su.c
/* $NetBSD: su.c,v 1.68 2008/07/21 14:19:26 lukem Exp $ */
/*
* Copyright (c) 1988 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.
* 3. 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.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1988\
The Regents of the University of California. All rights reserved.");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94";*/
#else
__RCSID("$NetBSD: su.c,v 1.68 2008/07/21 14:19:26 lukem Exp $");
#endif
#endif /* not lint */
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <err.h>
#include <errno.h>
#include <grp.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#ifdef SKEY
#include <skey.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <tzfile.h>
#include <unistd.h>
#include <util.h>
#ifdef LOGIN_CAP
#include <login_cap.h>
#endif
#ifdef KERBEROS5
#include <krb5.h>
#endif
#ifdef ALLOW_GROUP_CHANGE
#include "grutil.h"
#endif
#include "suutil.h"
#ifdef KERBEROS5
#define ARGSTRX "-Kdflm"
static int kerberos5(char *, const char *, uid_t);
int use_kerberos = 1;
#else
#define ARGSTRX "-dflm"
#endif
#ifndef SU_GROUP
#define SU_GROUP "wheel"
#endif
#define GROUP_PASSWORD "Group Password:"
#ifdef LOGIN_CAP
#define ARGSTR ARGSTRX "c:"
#else
#define ARGSTR ARGSTRX
#endif
static int check_ingroup(int, const char *, const char *, int);
int
main(int argc, char **argv)
{
extern char **environ;
struct passwd *pwd;
char *p;
#ifdef BSD4_4
struct timeval tp;
#endif
uid_t ruid;
int asme, ch, asthem, fastlogin, prio, gohome;
enum { UNSET, YES, NO } iscsh = UNSET;
const char *user, *shell, *avshell;
char *username, **np;
char *userpass, *class;
char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN];
time_t pw_warntime = _PASSWORD_WARNDAYS * SECSPERDAY;
#ifdef LOGIN_CAP
login_cap_t *lc;
#endif
#ifdef ALLOW_GROUP_CHANGE
char *gname;
#endif
(void)setprogname(argv[0]);
asme = asthem = fastlogin = 0;
gohome = 1;
shell = class = NULL;
while ((ch = getopt(argc, argv, ARGSTR)) != -1)
switch((char)ch) {
#ifdef KERBEROS5
case 'K':
use_kerberos = 0;
break;
#endif
#ifdef LOGIN_CAP
case 'c':
class = optarg;
break;
#endif
case 'd':
asme = 0;
asthem = 1;
gohome = 0;
break;
case 'f':
fastlogin = 1;
break;
case '-':
case 'l':
asme = 0;
asthem = 1;
break;
case 'm':
asme = 1;
asthem = 0;
break;
case '?':
default:
(void)fprintf(stderr,
#ifdef ALLOW_GROUP_CHANGE
"usage: %s [%s] [login[:group] [shell arguments]]\n",
#else
"usage: %s [%s] [login [shell arguments]]\n",
#endif
getprogname(), ARGSTR);
exit(EXIT_FAILURE);
}
argv += optind;
/* Lower the priority so su runs faster */
errno = 0;
prio = getpriority(PRIO_PROCESS, 0);
if (errno)
prio = 0;
if (prio > -2)
(void)setpriority(PRIO_PROCESS, 0, -2);
openlog("su", 0, LOG_AUTH);
/* get current login name and shell */
ruid = getuid();
username = getlogin();
if (username == NULL || (pwd = getpwnam(username)) == NULL ||
pwd->pw_uid != ruid)
pwd = getpwuid(ruid);
if (pwd == NULL)
errx(EXIT_FAILURE, "who are you?");
username = estrdup(pwd->pw_name);
userpass = estrdup(pwd->pw_passwd);
if (asme) {
if (pwd->pw_shell && *pwd->pw_shell) {
(void)estrlcpy(shellbuf, pwd->pw_shell, sizeof(shellbuf));
shell = shellbuf;
} else {
shell = _PATH_BSHELL;
iscsh = NO;
}
}
/* get target login information, default to root */
user = *argv ? *argv : "root";
np = *argv ? argv : argv - 1;
#ifdef ALLOW_GROUP_CHANGE
if ((p = strchr(user, ':')) != NULL) {
*p = '\0';
gname = ++p;
}
else
gname = NULL;
#ifdef ALLOW_EMPTY_USER
if (user[0] == '\0' && gname != NULL)
user = username;
#endif
#endif
if ((pwd = getpwnam(user)) == NULL)
errx(EXIT_FAILURE, "unknown login `%s'", user);
#ifdef LOGIN_CAP
/* force the usage of specified class */
if (class) {
if (ruid)
errx(EXIT_FAILURE, "Only root may use -c");
pwd->pw_class = class;
}
if ((lc = login_getclass(pwd->pw_class)) == NULL)
errx(EXIT_FAILURE, "Unknown class %s\n", pwd->pw_class);
pw_warntime = (time_t)login_getcaptime(lc, "password-warn",
_PASSWORD_WARNDAYS * SECSPERDAY,
_PASSWORD_WARNDAYS * SECSPERDAY);
#endif
if (ruid
#ifdef KERBEROS5
&& (!use_kerberos || kerberos5(username, user, pwd->pw_uid))
#endif
) {
char *pass = pwd->pw_passwd;
int ok = pwd->pw_uid != 0;
#ifdef SU_ROOTAUTH
/*
* Allow those in group rootauth to su to root, by supplying
* their own password.
*/
if (!ok) {
if ((ok = check_ingroup(-1, SU_ROOTAUTH, username, 0))) {
pass = userpass;
user = username;
}
}
#endif
/*
* Only allow those in group SU_GROUP to su to root,
* but only if that group has any members.
* If SU_GROUP has no members, allow anyone to su root
*/
if (!ok)
ok = check_ingroup(-1, SU_GROUP, username, 1);
if (!ok)
errx(EXIT_FAILURE,
"you are not listed in the correct secondary group (%s) to su %s.",
SU_GROUP, user);
/* if target requires a password, verify it */
if (*pass && pwd->pw_uid != ruid) { /* XXX - OK? */
p = getpass("Password:");
#ifdef SKEY
if (strcasecmp(p, "s/key") == 0) {
if (skey_haskey(user))
errx(EXIT_FAILURE,
"Sorry, you have no s/key.");
else {
if (skey_authenticate(user)) {
goto badlogin;
}
}
} else
#endif
if (strcmp(pass, crypt(p, pass)) != 0) {
#ifdef SKEY
badlogin:
#endif
(void)fprintf(stderr, "Sorry\n");
syslog(LOG_WARNING,
"BAD SU %s to %s%s", username,
pwd->pw_name, ontty());
exit(EXIT_FAILURE);
}
}
}
if (asme) {
/* if asme and non-standard target shell, must be root */
if (chshell(pwd->pw_shell) == 0 && ruid)
errx(EXIT_FAILURE, "permission denied (shell).");
} else if (pwd->pw_shell && *pwd->pw_shell) {
shell = pwd->pw_shell;
iscsh = UNSET;
} else {
shell = _PATH_BSHELL;
iscsh = NO;
}
if ((p = strrchr(shell, '/')) != NULL)
avshell = p+1;
else
avshell = shell;
/* if we're forking a csh, we want to slightly muck the args */
if (iscsh == UNSET)
iscsh = strstr(avshell, "csh") ? YES : NO;
/* set permissions */
#ifdef LOGIN_CAP
# ifdef ALLOW_GROUP_CHANGE
/* if we aren't changing users, keep the current group members */
if (ruid != pwd->pw_uid &&
setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) == -1)
err(EXIT_FAILURE, "setting user context");
addgroup(lc, gname, pwd, ruid, GROUP_PASSWORD);
if (setusercontext(lc, pwd, pwd->pw_uid,
(u_int)(asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) |
LOGIN_SETRESOURCES | LOGIN_SETUSER) == -1)
err(EXIT_FAILURE, "setting user context");
# else
if (setusercontext(lc, pwd, pwd->pw_uid,
(u_int)(asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) |
LOGIN_SETRESOURCES | LOGIN_SETGROUP | LOGIN_SETUSER) == -1)
err(EXIT_FAILURE, "setting user context");
# endif
#else
if (setgid(pwd->pw_gid) == -1)
err(EXIT_FAILURE, "setgid");
/* if we aren't changing users, keep the current group members */
if (ruid != pwd->pw_uid && initgroups(user, pwd->pw_gid) != 0)
errx(EXIT_FAILURE, "initgroups failed");
# ifdef ALLOW_GROUP_CHANGE
addgroup(/*EMPTY*/, gname, pwd, ruid, GROUP_PASSWORD);
# endif
if (setuid(pwd->pw_uid) == -1)
err(EXIT_FAILURE, "setuid");
#endif
if (!asme) {
if (asthem) {
p = getenv("TERM");
/* Create an empty environment */
environ = emalloc(sizeof(char *));
environ[0] = NULL;
#ifdef LOGIN_CAP
if (setusercontext(lc, pwd, pwd->pw_uid,
LOGIN_SETPATH) == -1)
err(EXIT_FAILURE, "setting user context");
#else
(void)setenv("PATH", _PATH_DEFPATH, 1);
#endif
if (p)
(void)setenv("TERM", p, 1);
if (gohome && chdir(pwd->pw_dir) == -1)
errx(EXIT_FAILURE, "no directory");
}
if (asthem || pwd->pw_uid) {
(void)setenv("LOGNAME", pwd->pw_name, 1);
(void)setenv("USER", pwd->pw_name, 1);
}
(void)setenv("HOME", pwd->pw_dir, 1);
(void)setenv("SHELL", shell, 1);
}
(void)setenv("SU_FROM", username, 1);
if (iscsh == YES) {
if (fastlogin)
*np-- = __UNCONST("-f");
if (asme)
*np-- = __UNCONST("-m");
} else {
if (fastlogin)
(void)unsetenv("ENV");
}
if (asthem) {
avshellbuf[0] = '-';
(void)estrlcpy(avshellbuf + 1, avshell, sizeof(avshellbuf) - 1);
avshell = avshellbuf;
} else if (iscsh == YES) {
/* csh strips the first character... */
avshellbuf[0] = '_';
(void)estrlcpy(avshellbuf + 1, avshell, sizeof(avshellbuf) - 1);
avshell = avshellbuf;
}
*np = __UNCONST(avshell);
#ifdef BSD4_4
if (pwd->pw_change || pwd->pw_expire)
(void)gettimeofday(&tp, (struct timezone *)NULL);
if (pwd->pw_change) {
if (tp.tv_sec >= pwd->pw_change) {
(void)printf("%s -- %s's password has expired.\n",
(ruid ? "Sorry" : "Note"), user);
if (ruid != 0)
exit(EXIT_FAILURE);
} else if (pwd->pw_change - tp.tv_sec < pw_warntime)
(void)printf("Warning: %s's password expires on %s",
user, ctime(&pwd->pw_change));
}
if (pwd->pw_expire) {
if (tp.tv_sec >= pwd->pw_expire) {
(void)printf("%s -- %s's account has expired.\n",
(ruid ? "Sorry" : "Note"), user);
if (ruid != 0)
exit(EXIT_FAILURE);
} else if (pwd->pw_expire - tp.tv_sec <
_PASSWORD_WARNDAYS * SECSPERDAY)
(void)printf("Warning: %s's account expires on %s",
user, ctime(&pwd->pw_expire));
}
#endif
if (ruid != 0)
syslog(LOG_NOTICE, "%s to %s%s",
username, pwd->pw_name, ontty());
/* Raise our priority back to what we had before */
(void)setpriority(PRIO_PROCESS, 0, prio);
(void)execv(shell, np);
err(EXIT_FAILURE, "%s", shell);
/* NOTREACHED */
}
#ifdef KERBEROS5
static int
kerberos5(char *username, const char *user, uid_t uid)
{
krb5_error_code ret;
krb5_context context;
krb5_principal princ = NULL;
krb5_ccache ccache, ccache2;
char *cc_name;
const char *filename;
ret = krb5_init_context(&context);
if (ret)
return 1;
if (strcmp(user, "root") == 0)
ret = krb5_make_principal(context, &princ,
NULL, username, "root", NULL);
else
ret = krb5_make_principal(context, &princ,
NULL, user, NULL);
if (ret)
goto fail;
if (!krb5_kuserok(context, princ, user) && !uid) {
warnx("kerberos5: not in %s's ACL.", user);
goto fail;
}
ret = krb5_cc_gen_new(context, &krb5_mcc_ops, &ccache);
if (ret)
goto fail;
ret = krb5_verify_user_lrealm(context, princ, ccache, NULL, TRUE,
NULL);
if (ret) {
krb5_cc_destroy(context, ccache);
switch (ret) {
case KRB5_LIBOS_PWDINTR :
break;
case KRB5KRB_AP_ERR_BAD_INTEGRITY:
case KRB5KRB_AP_ERR_MODIFIED:
krb5_warnx(context, "Password incorrect");
break;
default :
krb5_warn(context, ret, "krb5_verify_user");
break;
}
goto fail;
}
ret = krb5_cc_gen_new(context, &krb5_fcc_ops, &ccache2);
if (ret) {
krb5_cc_destroy(context, ccache);
goto fail;
}
ret = krb5_cc_copy_cache(context, ccache, ccache2);
if (ret) {
krb5_cc_destroy(context, ccache);
krb5_cc_destroy(context, ccache2);
goto fail;
}
filename = krb5_cc_get_name(context, ccache2);
(void)easprintf(&cc_name, "%s:%s", krb5_cc_get_type(context, ccache2),
filename);
if (chown(filename, uid, NOGROUP) == -1) {
warn("chown %s", filename);
free(cc_name);
krb5_cc_destroy(context, ccache);
krb5_cc_destroy(context, ccache2);
goto fail;
}
(void)setenv("KRB5CCNAME", cc_name, 1);
free(cc_name);
krb5_cc_close(context, ccache2);
krb5_cc_destroy(context, ccache);
return 0;
fail:
if (princ != NULL)
krb5_free_principal(context, princ);
krb5_free_context(context);
return 1;
}
#endif /* KERBEROS5 */
static int
check_ingroup(int gid, const char *gname, const char *user, int ifempty)
{
struct group *gr;
char **g;
#ifdef SU_INDIRECT_GROUP
char **gr_mem;
int n = 0;
int i = 0;
#endif
int ok = 0;
if (gname == NULL)
gr = getgrgid((gid_t) gid);
else
gr = getgrnam(gname);
/*
* XXX we are relying on the fact that we only set ifempty when
* calling to check for SU_GROUP and that is the only time a
* missing group is acceptable.
*/
if (gr == NULL)
return ifempty;
if (!*gr->gr_mem) /* empty */
return ifempty;
/*
* Ok, first see if user is in gr_mem
*/
for (g = gr->gr_mem; *g; ++g) {
if (strcmp(*g, user) == 0)
return 1; /* ok */
#ifdef SU_INDIRECT_GROUP
++n; /* count them */
#endif
}
#ifdef SU_INDIRECT_GROUP
/*
* No.
* Now we need to duplicate the gr_mem list, and recurse for
* each member to see if it is a group, and if so whether user is
* in it.
*/
gr_mem = emalloc((n + 1) * sizeof (char *));
for (g = gr->gr_mem, i = 0; *g; ++g) {
gr_mem[i] = estrdup(*g);
i++;
}
gr_mem[i++] = NULL;
for (g = gr_mem; ok == 0 && *g; ++g) {
/*
* If we get this far we don't accept empty/missing groups.
*/
ok = check_ingroup(-1, *g, user, 0);
}
for (g = gr_mem; *g; ++g) {
free(*g);
}
free(gr_mem);
#endif
return ok;
}