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NetBSD/usr.bin/su/su.c

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/* $NetBSD: su.c,v 1.16 1997/03/04 00:21:13 explorer 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 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
char copyright[] =
"@(#) Copyright (c) 1988 The Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94";*/
#else
static char rcsid[] = "$NetBSD: su.c,v 1.16 1997/03/04 00:21:13 explorer Exp $";
#endif
#endif /* not lint */
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <syslog.h>
#include <stdio.h>
#include <err.h>
#include <errno.h>
#include <stdlib.h>
#include <pwd.h>
#include <grp.h>
#include <string.h>
#include <unistd.h>
#include <paths.h>
#ifdef KERBEROS
#include <kerberosIV/des.h>
#include <kerberosIV/krb.h>
#include <netdb.h>
#define ARGSTR "-Kflm"
int use_kerberos = 1;
static int kerberos __P((char *, char *, int));
static int koktologin __P((char *, char *, char *));
#else
#define ARGSTR "-flm"
#endif
int main __P((int, char **));
static int chshell __P((char *));
static char *ontty __P((void));
int
main(argc, argv)
int argc;
char **argv;
{
extern char *__progname;
extern char **environ;
struct passwd *pwd;
char *p, **g;
struct group *gr;
uid_t ruid;
int asme, ch, asthem, fastlogin, prio;
enum { UNSET, YES, NO } iscsh = UNSET;
char *user, *shell, *avshell, *username, *cleanenv[10], **np;
char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN];
asme = asthem = fastlogin = 0;
while ((ch = getopt(argc, argv, ARGSTR)) != EOF)
switch((char)ch) {
#ifdef KERBEROS
case 'K':
use_kerberos = 0;
break;
#endif
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,
"Usage: %s [%s] [login [shell arguments]]\n",
__progname, ARGSTR);
exit(1);
}
argv += optind;
errno = 0;
prio = getpriority(PRIO_PROCESS, 0);
if (errno)
prio = 0;
(void)setpriority(PRIO_PROCESS, 0, -2);
openlog("su", LOG_CONS, 0);
/* 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(1, "who are you?");
}
username = strdup(pwd->pw_name);
if (asme)
if (pwd->pw_shell && *pwd->pw_shell)
shell = strncpy(shellbuf, pwd->pw_shell,
sizeof(shellbuf) + 1);
else {
shell = _PATH_BSHELL;
iscsh = NO;
}
/* get target login information, default to root */
user = *argv ? *argv : "root";
np = *argv ? argv : argv-1;
if ((pwd = getpwnam(user)) == NULL) {
errx(1, "unknown login %s", user);
}
if (ruid) {
#ifdef KERBEROS
if (!use_kerberos || kerberos(username, user, pwd->pw_uid))
#endif
{
/* only allow those in group zero to su to root, if group
* zero has any members. */
if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)) &&
*gr->gr_mem) {
for (g = gr->gr_mem;; ++g) {
if (!*g)
errx(1,
"you are not in the correct group to su %s.",
user);
if (!strcmp(username, *g))
break;
}
}
/* if target requires a password, verify it */
if (*pwd->pw_passwd) {
p = getpass("Password:");
#ifdef SKEY
if (strcasecmp(p, "s/key") == 0) {
if (skey_haskey(user))
errx(1, "Sorry, you have no s/key.");
else {
if (skey_authenticate(user)) {
goto badlogin;
}
}
} else
#endif
if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
badlogin:
fprintf(stderr, "Sorry\n");
syslog(LOG_AUTH|LOG_WARNING,
"BAD SU %s to %s%s", username,
user, ontty());
exit(1);
}
}
}
}
if (asme) {
/* if asme and non-standard target shell, must be root */
if (!chshell(pwd->pw_shell) && ruid)
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 (p = strrchr(shell, '/'))
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 */
if (setgid(pwd->pw_gid) < 0)
err(1, "setgid");
if (initgroups(user, pwd->pw_gid))
errx(1, "initgroups failed");
if (setuid(pwd->pw_uid) < 0)
err(1, "setuid");
if (!asme) {
if (asthem) {
p = getenv("TERM");
cleanenv[0] = NULL;
environ = cleanenv;
(void)setenv("PATH", _PATH_DEFPATH, 1);
if (p)
(void)setenv("TERM", p, 1);
if (chdir(pwd->pw_dir) < 0)
errx(1, "no directory");
}
if (asthem || pwd->pw_uid)
(void)setenv("USER", pwd->pw_name, 1);
(void)setenv("HOME", pwd->pw_dir, 1);
(void)setenv("SHELL", shell, 1);
}
if (iscsh == YES) {
if (fastlogin)
*np-- = "-f";
if (asme)
*np-- = "-m";
}
if (asthem) {
avshellbuf[0] = '-';
(void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2);
avshell = avshellbuf;
} else if (iscsh == YES) {
/* csh strips the first character... */
avshellbuf[0] = '_';
(void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2);
avshell = avshellbuf;
}
*np = avshell;
if (ruid != 0)
syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
username, user, ontty());
(void)setpriority(PRIO_PROCESS, 0, prio);
execv(shell, np);
err(1, "%s", shell);
}
static int
chshell(sh)
char *sh;
{
char *cp;
char *getusershell();
while ((cp = getusershell()) != NULL)
if (!strcmp(cp, sh))
return (1);
return (0);
}
static char *
ontty()
{
char *p, *ttyname();
static char buf[MAXPATHLEN + 4];
buf[0] = 0;
if (p = ttyname(STDERR_FILENO))
(void)snprintf(buf, sizeof buf, " on %s", p);
return (buf);
}
#ifdef KERBEROS
static int
kerberos(username, user, uid)
char *username, *user;
int uid;
{
KTEXT_ST ticket;
AUTH_DAT authdata;
struct hostent *hp;
register char *p;
int kerno;
u_long faddr;
char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN];
char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
char *ontty(), *krb_get_phost();
if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
return (1);
if (koktologin(username, lrealm, user) && !uid) {
warnx("kerberos: not in %s's ACL.", user);
return (1);
}
(void)(void)snprintf(krbtkfile, sizeof krbtkfile, "%s_%s_%d", TKT_ROOT,
user, getuid());
(void)setenv("KRBTKFILE", krbtkfile, 1);
(void)krb_set_tkt_string(krbtkfile);
/*
* Set real as well as effective ID to 0 for the moment,
* to make the kerberos library do the right thing.
*/
if (setuid(0) < 0) {
warn("setuid");
return (1);
}
/*
* Little trick here -- if we are su'ing to root,
* we need to get a ticket for "xxx.root", where xxx represents
* the name of the person su'ing. Otherwise (non-root case),
* we need to get a ticket for "yyy.", where yyy represents
* the name of the person being su'd to, and the instance is null
*
* We should have a way to set the ticket lifetime,
* with a system default for root.
*/
kerno = krb_get_pw_in_tkt((uid == 0 ? username : user),
(uid == 0 ? "root" : ""), lrealm,
"krbtgt", lrealm, DEFAULT_TKT_LIFE, 0);
if (kerno != KSUCCESS) {
if (kerno == KDC_PR_UNKNOWN) {
warnx("kerberos: principal unknown: %s.%s@%s",
(uid == 0 ? username : user),
(uid == 0 ? "root" : ""), lrealm);
return (1);
}
warnx("kerberos: unable to su: %s", krb_err_txt[kerno]);
syslog(LOG_NOTICE|LOG_AUTH,
"BAD Kerberos SU: %s to %s%s: %s",
username, user, ontty(), krb_err_txt[kerno]);
return (1);
}
if (chown(krbtkfile, uid, -1) < 0) {
warn("chown");
(void)unlink(krbtkfile);
return (1);
}
(void)setpriority(PRIO_PROCESS, 0, -2);
if (gethostname(hostname, sizeof(hostname)) == -1) {
warn("gethostname");
dest_tkt();
return (1);
}
(void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost));
savehost[sizeof(savehost) - 1] = '\0';
kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33);
if (kerno == KDC_PR_UNKNOWN) {
warnx("Warning: TGT not verified.");
syslog(LOG_NOTICE|LOG_AUTH,
"%s to %s%s, TGT not verified (%s); %s.%s not registered?",
username, user, ontty(), krb_err_txt[kerno],
"rcmd", savehost);
} else if (kerno != KSUCCESS) {
warnx("Unable to use TGT: %s", krb_err_txt[kerno]);
syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s",
username, user, ontty(), krb_err_txt[kerno]);
dest_tkt();
return (1);
} else {
if (!(hp = gethostbyname(hostname))) {
warnx("can't get addr of %s", hostname);
dest_tkt();
return (1);
}
memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr));
if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
&authdata, "")) != KSUCCESS) {
warnx("kerberos: unable to verify rcmd ticket: %s\n",
krb_err_txt[kerno]);
syslog(LOG_NOTICE|LOG_AUTH,
"failed su: %s to %s%s: %s", username,
user, ontty(), krb_err_txt[kerno]);
dest_tkt();
return (1);
}
}
return (0);
}
static int
koktologin(name, realm, toname)
char *name, *realm, *toname;
{
register AUTH_DAT *kdata;
AUTH_DAT kdata_st;
kdata = &kdata_st;
memset((char *)kdata, 0, sizeof(*kdata));
(void)strncpy(kdata->pname, name, sizeof(kdata->pname) - 1);
(void)strncpy(kdata->pinst,
((strcmp(toname, "root") == 0) ? "root" : ""), sizeof(kdata->pinst) - 1);
(void)strncpy(kdata->prealm, realm, sizeof(kdata->prealm) - 1);
return (kuserok(kdata, toname));
}
#endif
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