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freebsd/usr.bin/su/su.c
1997-03-29 04:34:07 +00:00

565 lines
14 KiB
C

/*
* 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.
* 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 const char copyright[] =
"@(#) Copyright (c) 1988, 1993, 1994\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
/*
static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94";
*/
static const char rcsid[] =
"$Id: su.c,v 1.18 1997/02/24 20:32:24 guido 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 <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#ifdef LOGIN_CAP
#include <login_cap.h>
#ifdef LOGIN_CAP_AUTH
#undef SKEY
#undef KERBEROS
#endif
#endif
#ifdef SKEY
#include <skey.h>
#endif
#ifdef KERBEROS
#include <des.h>
#include <kerberosIV/krb.h>
#include <netdb.h>
#define ARGSTR "-Kflm"
static int kerberos(char *username, char *user, int uid, char *pword);
static int koktologin(char *name, char *toname);
int use_kerberos = 1;
#else /* !KERBEROS */
#define ARGSTR "-flm"
#endif /* KERBEROS */
char *ontty __P((void));
int chshell __P((char *));
int
main(argc, argv)
int argc;
char **argv;
{
extern char **environ;
struct passwd *pwd;
#ifdef WHEELSU
char *targetpass;
int iswheelsu;
#endif /* WHEELSU */
char *p, **g, *user, *shell=NULL, *username, *cleanenv[20], **nargv, **np;
struct group *gr;
uid_t ruid;
int asme, ch, asthem, fastlogin, prio, i;
enum { UNSET, YES, NO } iscsh = UNSET;
#ifdef LOGIN_CAP
login_cap_t *lc;
int setwhat;
#ifdef LOGIN_CAP_AUTH
char *style, *approvep, *auth_method = NULL;
#endif
#endif
char shellbuf[MAXPATHLEN];
#ifdef WHEELSU
iswheelsu =
#endif /* WHEELSU */
asme = asthem = fastlogin = 0;
user = "root";
while(optind < argc)
if((ch = getopt(argc, argv, ARGSTR)) != -1)
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);
}
else
{
user = argv[optind++];
break;
}
if((nargv = malloc (sizeof (char *) * (argc + 4))) == NULL) {
errx(1, "malloc failure");
}
nargv[argc + 3] = NULL;
for (i = argc; i >= optind; i--)
nargv[i + 3] = argv[i];
np = &nargv[i + 3];
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 (username == NULL)
err(1, NULL);
if (asme) {
if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') {
/* copy: pwd memory is recycled */
shell = strncpy(shellbuf, pwd->pw_shell, sizeof shellbuf);
shellbuf[sizeof shellbuf - 1] = '\0';
} else {
shell = _PATH_BSHELL;
iscsh = NO;
}
}
#ifdef LOGIN_CAP_AUTH
if (auth_method = strchr(user, ':')) {
*auth_method = '\0';
auth_method++;
if (*auth_method == '\0')
auth_method = NULL;
}
#endif /* !LOGIN_CAP_AUTH */
/* get target login information, default to root */
if ((pwd = getpwnam(user)) == NULL) {
errx(1, "unknown login: %s", user);
}
#ifdef LOGIN_CAP
lc = login_getclass(pwd);
#endif
#ifdef WHEELSU
targetpass = strdup(pwd->pw_passwd);
#endif /* WHEELSU */
if (ruid) {
#ifdef KERBEROS
if (use_kerberos && koktologin(username, user)
&& !pwd->pw_uid) {
warnx("kerberos: not in %s's ACL.", user);
use_kerberos = 0;
}
#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) {
#ifdef WHEELSU
iswheelsu = 1;
#endif /* WHEELSU */
break;
}
}
}
/* if target requires a password, verify it */
if (*pwd->pw_passwd) {
#ifdef LOGIN_CAP_AUTH
/*
* This hands off authorisation to an authorisation program,
* depending on the styles available for the "auth-su",
* authorisation styles.
*/
if ((style = login_getstyle(lc, auth_method, "su")) == NULL)
errx(1, "auth method available for su.\n");
if (authenticate(user, lc ? lc->lc_class : "default", style, "su") != 0) {
#ifdef WHEELSU
if (!iswheelsu || authenticate(username, lc ? lc->lc_class : "default", style, "su") != 0) {
#endif /* WHEELSU */
{
fprintf(stderr, "Sorry\n");
syslog(LOG_AUTH|LOG_WARNING,"BAD SU %s to %s%s", username, user, ontty());
exit(1);
}
}
/*
* If authentication succeeds, run any approval
* program, if applicable for this class.
*/
approvep = login_getcapstr(lc, "approve", NULL, NULL);
if (approvep==NULL || auth_script(approvep, approvep, username, lc->lc_class, 0) == 0) {
int r = auth_scan(AUTH_OKAY);
/* See what the authorise program says */
if (!(r & AUTH_ROOTOKAY) && pwd->pw_uid == 0) {
fprintf(stderr, "Sorry\n");
syslog(LOG_AUTH|LOG_WARNING,"UNAPPROVED ROOT SU %s%s", user, ontty());
exit(1);
}
}
#else /* !LOGIN_CAP_AUTH */
#ifdef SKEY
#ifdef WHEELSU
if (iswheelsu) {
pwd = getpwnam(username);
}
#endif /* WHEELSU */
p = skey_getpass("Password:", pwd, 1);
if (!(!strcmp(pwd->pw_passwd, skey_crypt(p, pwd->pw_passwd, pwd, 1))
#ifdef WHEELSU
|| (iswheelsu && !strcmp(targetpass, crypt(p,targetpass)))
#endif /* WHEELSU */
)) {
#else
p = getpass("Password:");
if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
#endif
#ifdef KERBEROS
if (!use_kerberos || (use_kerberos && kerberos(username, user, pwd->pw_uid, p)))
#endif
{
fprintf(stderr, "Sorry\n");
syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s%s", username, user, ontty());
exit(1);
}
}
#ifdef WHEELSU
if (iswheelsu) {
pwd = getpwnam(user);
}
#endif /* WHEELSU */
#endif /* LOGIN_CAP_AUTH */
}
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 we're forking a csh, we want to slightly muck the args */
if (iscsh == UNSET) {
p = strrchr(shell, '/');
if (p)
++p;
else
p = shell;
if ((iscsh = strcmp(p, "csh") ? NO : YES) == NO)
iscsh = strcmp(p, "tcsh") ? NO : YES;
}
(void)setpriority(PRIO_PROCESS, 0, prio);
#ifdef LOGIN_CAP
/* Set everything now except the environment & umask */
setwhat = LOGIN_SETUSER|LOGIN_SETGROUP|LOGIN_SETRESOURCES|LOGIN_SETPRIORITY;
/*
* Don't touch resource/priority settings if -m has been
* used or -l hasn't, and we're not su'ing to root.
*/
if ((asme || !asthem) && pwd->pw_uid)
setwhat &= ~(LOGIN_SETPRIORITY|LOGIN_SETRESOURCES);
if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0)
err(1, "setusercontext");
#else
/* 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");
#endif
if (!asme) {
if (asthem) {
p = getenv("TERM");
cleanenv[0] = NULL;
environ = cleanenv;
#ifdef LOGIN_CAP
/* set the su'd user's environment & umask */
setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH|LOGIN_SETUMASK|LOGIN_SETENV);
#else
(void)setenv("PATH", _PATH_DEFPATH, 1);
#endif
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";
}
/* 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());
login_close(lc);
execv(shell, np);
err(1, "%s", shell);
}
int
chshell(sh)
char *sh;
{
int r = 0;
char *cp;
setusershell();
while (!r && (cp = getusershell()) != NULL)
r = strcmp(cp, sh) == 0;
endusershell();
return r;
}
char *
ontty()
{
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);
}
#ifdef KERBEROS
int
kerberos(username, user, uid, pword)
char *username, *user;
int uid;
char *pword;
{
extern char *krb_err_txt[];
KTEXT_ST ticket;
AUTH_DAT authdata;
int kerno;
u_long faddr;
struct sockaddr_in local_addr;
char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN];
char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
char *krb_get_phost();
if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
return (1);
(void)sprintf(krbtkfile, "%s_%s_%lu", TKT_ROOT, user,
(unsigned long)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, pword);
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 ((kerno = krb_get_local_addr(&local_addr)) != KSUCCESS) {
warnx("Unable to get our local address: %s",
krb_err_txt[kerno]);
dest_tkt();
return (1);
}
faddr = local_addr.sin_addr.s_addr;
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);
}
int
koktologin(name, toname)
char *name, *toname;
{
AUTH_DAT *kdata;
AUTH_DAT kdata_st;
char realm[REALM_SZ];
if (krb_get_lrealm(realm, 1) != KSUCCESS)
return (1);
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