4.4BSD/usr/src/usr.bin/su/su.c
/*
* Copyright (c) 1988, 1993
* 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
static char copyright[] =
"@(#) Copyright (c) 1988, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char sccsid[] = "@(#)su.c 8.1 (Berkeley) 6/6/93";
#endif /* not lint */
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <syslog.h>
#include <stdio.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;
#else
#define ARGSTR "-flm"
#endif
main(argc, argv)
int argc;
char **argv;
{
extern char **environ;
extern int errno, optind;
register struct passwd *pwd;
register char *p, **g;
struct group *gr;
uid_t ruid, getuid();
int asme, ch, asthem, fastlogin, prio;
enum { UNSET, YES, NO } iscsh = UNSET;
char *user, *shell, *username, *cleanenv[2], *nargv[4], **np;
char shellbuf[MAXPATHLEN];
char *crypt(), *getpass(), *getenv(), *getlogin(), *ontty();
np = &nargv[3];
*np-- = NULL;
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: su [%s] [login]\n",
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) {
fprintf(stderr, "su: who are you?\n");
exit(1);
}
username = strdup(pwd->pw_name);
if (asme)
if (pwd->pw_shell && *pwd->pw_shell)
shell = strcpy(shellbuf, pwd->pw_shell);
else {
shell = _PATH_BSHELL;
iscsh = NO;
}
/* get target login information, default to root */
user = *argv ? *argv : "root";
if ((pwd = getpwnam(user)) == NULL) {
fprintf(stderr, "su: unknown login %s\n", user);
exit(1);
}
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 (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)))
for (g = gr->gr_mem;; ++g) {
if (!*g) {
(void)fprintf(stderr,
"su: you are not in the correct group to su %s.\n",
user);
exit(1);
}
if (!strcmp(username, *g))
break;
}
/* if target requires a password, verify it */
if (*pwd->pw_passwd) {
p = getpass("Password:");
if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
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) {
(void)fprintf(stderr,
"su: permission denied (shell).\n");
exit(1);
}
} 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) {
if (p = rindex(shell, '/'))
++p;
else
p = shell;
iscsh = strcmp(p, "csh") ? NO : YES;
}
/* set permissions */
if (setgid(pwd->pw_gid) < 0) {
perror("su: setgid");
exit(1);
}
if (initgroups(user, pwd->pw_gid)) {
(void)fprintf(stderr, "su: initgroups failed.\n");
exit(1);
}
if (setuid(pwd->pw_uid) < 0) {
perror("su: setuid");
exit(1);
}
if (!asme) {
if (asthem) {
p = getenv("TERM");
cleanenv[0] = _PATH_DEFPATH;
cleanenv[1] = NULL;
environ = cleanenv;
(void)setenv("TERM", p, 1);
if (chdir(pwd->pw_dir) < 0) {
fprintf(stderr, "su: no directory\n");
exit(1);
}
}
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";
}
/* csh strips the first character... */
*np = asthem ? "-su" : iscsh == YES ? "_su" : "su";
if (ruid != 0)
syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
username, user, ontty());
(void)setpriority(PRIO_PROCESS, 0, prio);
execv(shell, np);
(void)fprintf(stderr, "su: %s not found.\n", shell);
exit(1);
}
chshell(sh)
char *sh;
{
register char *cp;
char *getusershell();
while ((cp = getusershell()) != NULL)
if (!strcmp(cp, sh))
return (1);
return (0);
}
char *
ontty()
{
char *p, *ttyname();
static char buf[MAXPATHLEN + 4];
buf[0] = 0;
if (p = ttyname(STDERR_FILENO))
sprintf(buf, " on %s", p);
return (buf);
}
#ifdef KERBEROS
kerberos(username, user, uid)
char *username, *user;
int uid;
{
extern char *krb_err_txt[];
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) {
(void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user);
return (1);
}
(void)sprintf(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) {
perror("su: 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) {
fprintf(stderr, "principal unknown: %s.%s@%s\n",
(uid == 0 ? username : user),
(uid == 0 ? "root" : ""), lrealm);
return (1);
}
(void)fprintf(stderr, "su: unable to su: %s\n",
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) {
perror("su: chown:");
(void)unlink(krbtkfile);
return (1);
}
(void)setpriority(PRIO_PROCESS, 0, -2);
if (gethostname(hostname, sizeof(hostname)) == -1) {
perror("su: 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) {
(void)fprintf(stderr, "Warning: TGT not verified.\n");
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) {
(void)fprintf(stderr, "Unable to use TGT: %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);
} else {
if (!(hp = gethostbyname(hostname))) {
(void)fprintf(stderr, "su: can't get addr of %s\n",
hostname);
dest_tkt();
return (1);
}
(void)bcopy((char *)hp->h_addr, (char *)&faddr, sizeof(faddr));
if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
&authdata, "")) != KSUCCESS) {
(void)fprintf(stderr,
"su: 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);
}
koktologin(name, realm, toname)
char *name, *realm, *toname;
{
register AUTH_DAT *kdata;
AUTH_DAT kdata_st;
kdata = &kdata_st;
bzero((caddr_t) kdata, sizeof(*kdata));
(void)strcpy(kdata->pname, name);
(void)strcpy(kdata->pinst,
((strcmp(toname, "root") == 0) ? "root" : ""));
(void)strcpy(kdata->prealm, realm);
return (kuserok(kdata, toname));
}
#endif