File: [local] / src / usr.bin / su / su.c (download)
Revision 1.34.2.1, Fri Dec 8 09:03:15 2000 UTC (23 years, 5 months ago) by hin
Branch: OPENBSD_2_8
Changes since 1.34: +22 -5 lines
Bring recent kerberos fix into -stable
|
/* $OpenBSD: su.c,v 1.34.2.1 2000/12/08 09:03:15 hin 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
/*static char sccsid[] = "from: @(#)su.c 5.26 (Berkeley) 7/6/91";*/
static char rcsid[] = "$OpenBSD: su.c,v 1.34.2.1 2000/12/08 09:03:15 hin Exp $";
#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 <login_cap.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <fcntl.h>
#ifdef SKEY
#include <skey.h>
#endif
#ifdef KERBEROS
#include <des.h>
#include <kerberosIV/krb.h>
#include <netdb.h>
int kerberos __P((char *username, char *user, int uid));
#define ARGSTR "-Kc:flm"
int use_kerberos = 1;
char krbtkfile[MAXPATHLEN];
char lrealm[REALM_SZ];
int ksettkfile(char *);
#else
#define ARGSTR "-c:flm"
#endif
char *ontty __P((void));
int chshell __P((char *));
int
main(argc, argv)
int argc;
char **argv;
{
extern char **environ;
register struct passwd *pwd;
register char *p, **g;
struct group *gr;
uid_t ruid;
login_cap_t *lc;
int asme, ch, asthem, fastlogin, prio;
enum { UNSET, YES, NO } iscsh;
char *user, *shell, *avshell, *username, *class, **np;
char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN];
iscsh = UNSET;
shell = class = NULL;
asme = asthem = fastlogin = 0;
while ((ch = getopt(argc, argv, ARGSTR)) != -1)
switch((char)ch) {
#ifdef KERBEROS
case 'K':
use_kerberos = 0;
break;
#endif
case 'c':
class = optarg;
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,
"usage: su [%s] [login [shell arguments]]\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)
errx(1, "who are you?");
if ((username = strdup(pwd->pw_name)) == NULL)
err(1, "can't allocate memory");
if (asme) {
if (pwd->pw_shell && *pwd->pw_shell) {
shell = strncpy(shellbuf, pwd->pw_shell, sizeof(shellbuf) - 1);
shellbuf[sizeof(shellbuf) - 1] = '\0';
} 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 ((user = strdup(pwd->pw_name)) == NULL)
err(1, "can't allocate memory");
/* If the user specified a login class and we are root, use it */
if (ruid && class)
errx(1, "only the superuser may specify a login class");
if (class)
pwd->pw_class = class;
if ((lc = login_getclass(pwd->pw_class)) == NULL)
errx(1, "no such login class: %s",
class ? class : LOGIN_DEFCLASS);
#if KERBEROS
if (ksettkfile(user))
use_kerberos = 0;
#endif
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))
&& gr->gr_mem && *(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) == 0)
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_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 (pwd->pw_expire && time(NULL) >= pwd->pw_expire) {
fprintf(stderr, "Sorry - account expired\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 = strcmp(avshell, "csh") ? NO : YES;
if (!asme) {
if (asthem) {
p = getenv("TERM");
if ((environ = calloc(1, sizeof (char *))) == NULL)
errx(1, "calloc");
if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH))
err(1, "unable to set user context");
if (p) {
if (setenv("TERM", p, 1) == -1)
err(1, "unable to set environment");
}
seteuid(pwd->pw_uid);
setegid(pwd->pw_gid);
if (chdir(pwd->pw_dir) < 0)
err(1, "%s", pwd->pw_dir);
seteuid(0);
setegid(0); /* XXX use a saved gid instead? */
} else if (pwd->pw_uid == 0) {
/* XXX - this seems questionable to me */
if (setusercontext(lc,
pwd, pwd->pw_uid, LOGIN_SETPATH|LOGIN_SETUMASK))
err(1, "unable to set user context");
}
if (asthem || pwd->pw_uid) {
if (setenv("LOGNAME", pwd->pw_name, 1) == -1 ||
setenv("USER", pwd->pw_name, 1) == -1)
err(1, "unable to set environment");
}
if (setenv("HOME", pwd->pw_dir, 1) == -1 ||
setenv("SHELL", shell, 1) == -1)
err(1, "unable to set environment");
}
#ifdef KERBEROS
if (*krbtkfile) {
if (setenv("KRBTKFILE", krbtkfile, 1) == -1)
err(1, "unable to set environment");
}
#endif
if (iscsh == YES) {
if (fastlogin)
*np-- = "-f";
if (asme)
*np-- = "-m";
}
if (asthem) {
avshellbuf[0] = '-';
strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2);
avshellbuf[sizeof(avshellbuf) - 1] = '\0';
avshell = avshellbuf;
} else if (iscsh == YES) {
/* csh strips the first character... */
avshellbuf[0] = '_';
strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2);
avshellbuf[sizeof(avshellbuf) - 1] = '\0';
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);
if (setusercontext(lc, pwd, pwd->pw_uid,
(asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) |
LOGIN_SETRESOURCES | LOGIN_SETGROUP | LOGIN_SETUSER))
err(1, "unable to set user context");
execv(shell, np);
err(1, "%s", shell);
}
int
chshell(sh)
char *sh;
{
register char *cp;
while ((cp = getusershell()) != NULL)
if (strcmp(cp, sh) == 0)
return (1);
return (0);
}
char *
ontty()
{
char *p, *ttyname();
static char buf[MAXPATHLEN + 4];
buf[0] = 0;
if ((p = ttyname(STDERR_FILENO)))
snprintf(buf, sizeof(buf), " on %s", p);
return (buf);
}
#ifdef KERBEROS
int koktologin __P((char *, char *, char *));
int
kerberos(username, user, uid)
char *username, *user;
int uid;
{
KTEXT_ST ticket;
AUTH_DAT authdata;
struct hostent *hp;
int kerno, fd;
in_addr_t faddr;
char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
char *ontty(), *krb_get_phost();
/* Don't bother with Kerberos if there is no srvtab file */
if ((fd = open(KEYFILE, O_RDONLY, 0)) < 0)
return (1);
close(fd);
if (koktologin(username, lrealm, user) && !uid) {
(void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user);
return (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
*/
printf("%s%s@%s's ", (uid == 0 ? username : user),
(uid == 0 ? ".root" : ""), lrealm);
fflush(stdout);
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("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);
}
/*
* Set the owner of the ticket file to root but bail if someone
* has nefariously swapped a link in place of the file.
*/
fd = open(krbtkfile, O_RDWR|O_NOFOLLOW, 0);
if (fd == -1) {
warn("unable to open ticket file");
(void)unlink(krbtkfile);
return (1);
}
if (fchown(fd, uid, -1) < 0) {
warn("fchown");
(void)unlink(krbtkfile);
return (1);
}
close(fd);
(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) - 1);
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);
}
(void)memcpy((void *)&faddr, (void *)hp->h_addr, sizeof(faddr));
if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
&authdata, "")) != KSUCCESS) {
warnx("unable to verify rcmd ticket: %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);
}
}
return (0);
}
int
koktologin(name, realm, toname)
char *name, *realm, *toname;
{
register AUTH_DAT *kdata;
AUTH_DAT kdata_st;
memset((void *)&kdata_st, 0, sizeof(kdata_st));
kdata = &kdata_st;
(void)strncpy(kdata->pname, name, sizeof(kdata->pname) - 1);
kdata->pname[sizeof(kdata->pname) - 1] = '\0';
(void)strncpy(kdata->pinst,
((strcmp(toname, "root") == 0) ? "root" : ""), sizeof(kdata->pinst) - 1);
kdata->pinst[sizeof(kdata->pinst) -1] = '\0';
(void)strncpy(kdata->prealm, realm, sizeof(kdata->prealm) - 1);
kdata->prealm[sizeof(kdata->prealm) -1] = '\0';
return (kuserok(kdata, toname));
}
int
ksettkfile(user)
char *user;
{
if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
return (1);
(void)snprintf(krbtkfile, sizeof(krbtkfile), "%s_%s_%u", TKT_ROOT,
user, getuid());
return (0);
}
#endif