su.c revision 28612 
1/*
2 * Copyright (c) 1988, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#ifndef lint
35static const char copyright[] =
36"@(#) Copyright (c) 1988, 1993, 1994\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41#if 0
42static char sccsid[] = "@(#)su.c	8.3 (Berkeley) 4/2/94";
43#endif
44static const char rcsid[] =
45	"$Id: su.c,v 1.21 1997/08/12 06:45:43 charnier Exp $";
46#endif /* not lint */
47
48#include <sys/param.h>
49#include <sys/time.h>
50#include <sys/resource.h>
51
52#include <err.h>
53#include <errno.h>
54#include <grp.h>
55#include <paths.h>
56#include <pwd.h>
57#include <stdio.h>
58#include <stdlib.h>
59#include <string.h>
60#include <syslog.h>
61#include <unistd.h>
62
63#ifdef LOGIN_CAP
64#include <login_cap.h>
65#ifdef LOGIN_CAP_AUTH
66#undef SKEY
67#undef KERBEROS
68#endif
69#endif
70
71#ifdef	SKEY
72#include <skey.h>
73#endif
74
75#ifdef KERBEROS
76#include <des.h>
77#include <kerberosIV/krb.h>
78#include <netdb.h>
79
80#define	ARGSTR	"-Kflm"
81
82static int kerberos(char *username, char *user, int uid, char *pword);
83static int koktologin(char *name, char *toname);
84
85int use_kerberos = 1;
86#else /* !KERBEROS */
87#define	ARGSTR	"-flm"
88#endif /* KERBEROS */
89
90char   *ontty __P((void));
91int	chshell __P((char *));
92static void usage __P((void));
93
94int
95main(argc, argv)
96	int argc;
97	char **argv;
98{
99	extern char **environ;
100	struct passwd *pwd;
101#ifdef WHEELSU
102	char *targetpass;
103	int iswheelsu;
104#endif /* WHEELSU */
105	char *p, **g, *user, *shell=NULL, *username, *cleanenv[20], **nargv, **np;
106	struct group *gr;
107	uid_t ruid;
108	int asme, ch, asthem, fastlogin, prio, i;
109	enum { UNSET, YES, NO } iscsh = UNSET;
110#ifdef LOGIN_CAP
111	login_cap_t *lc;
112	int setwhat;
113#ifdef LOGIN_CAP_AUTH
114	char *style, *approvep, *auth_method = NULL;
115#endif
116#endif
117	char shellbuf[MAXPATHLEN];
118
119#ifdef WHEELSU
120	iswheelsu =
121#endif /* WHEELSU */
122	asme = asthem = fastlogin = 0;
123	user = "root";
124	while(optind < argc)
125	    if((ch = getopt(argc, argv, ARGSTR)) != -1)
126		switch((char)ch) {
127#ifdef KERBEROS
128		case 'K':
129			use_kerberos = 0;
130			break;
131#endif
132		case 'f':
133			fastlogin = 1;
134			break;
135		case '-':
136		case 'l':
137			asme = 0;
138			asthem = 1;
139			break;
140		case 'm':
141			asme = 1;
142			asthem = 0;
143			break;
144		case '?':
145		default:
146			usage();
147		}
148	    else
149	    {
150		user = argv[optind++];
151		break;
152	    }
153
154	if (user == NULL)
155		usage();
156
157	if ((nargv = malloc (sizeof (char *) * (argc + 4))) == NULL) {
158	    errx(1, "malloc failure");
159	}
160
161	nargv[argc + 3] = NULL;
162	for (i = argc; i >= optind; i--)
163	    nargv[i + 3] = argv[i];
164	np = &nargv[i + 3];
165
166	argv += optind;
167
168	errno = 0;
169	prio = getpriority(PRIO_PROCESS, 0);
170	if (errno)
171		prio = 0;
172	(void)setpriority(PRIO_PROCESS, 0, -2);
173	openlog("su", LOG_CONS, 0);
174
175	/* get current login name and shell */
176	ruid = getuid();
177	username = getlogin();
178	if (username == NULL || (pwd = getpwnam(username)) == NULL ||
179	    pwd->pw_uid != ruid)
180		pwd = getpwuid(ruid);
181	if (pwd == NULL)
182		errx(1, "who are you?");
183	username = strdup(pwd->pw_name);
184	if (username == NULL)
185		err(1, NULL);
186	if (asme) {
187		if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') {
188			/* copy: pwd memory is recycled */
189			shell = strncpy(shellbuf,  pwd->pw_shell, sizeof shellbuf);
190			shellbuf[sizeof shellbuf - 1] = '\0';
191		} else {
192			shell = _PATH_BSHELL;
193			iscsh = NO;
194		}
195	}
196
197#ifdef LOGIN_CAP_AUTH
198	if (auth_method = strchr(user, ':')) {
199		*auth_method = '\0';
200		auth_method++;
201		if (*auth_method == '\0')
202			auth_method = NULL;
203	}
204#endif /* !LOGIN_CAP_AUTH */
205
206	/* get target login information, default to root */
207	if ((pwd = getpwnam(user)) == NULL) {
208		errx(1, "unknown login: %s", user);
209	}
210#ifdef LOGIN_CAP
211	lc = login_getpwclass(pwd);
212#endif
213
214#ifdef WHEELSU
215	targetpass = strdup(pwd->pw_passwd);
216#endif /* WHEELSU */
217
218	if (ruid) {
219#ifdef KERBEROS
220		if (use_kerberos && koktologin(username, user)
221		    && !pwd->pw_uid) {
222			warnx("kerberos: not in %s's ACL.", user);
223			use_kerberos = 0;
224		}
225#endif
226		{
227			/* only allow those in group zero to su to root. */
228			if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)) &&
229			    gr->gr_mem && *(gr->gr_mem))
230				for (g = gr->gr_mem;; ++g) {
231					if (!*g)
232						errx(1,
233			    "you are not in the correct group to su %s.",
234						    user);
235					if (strcmp(username, *g) == 0) {
236#ifdef WHEELSU
237						iswheelsu = 1;
238#endif /* WHEELSU */
239						break;
240					}
241				}
242		}
243		/* if target requires a password, verify it */
244		if (*pwd->pw_passwd) {
245#ifdef LOGIN_CAP_AUTH
246		/*
247		 * This hands off authorisation to an authorisation program,
248		 * depending on the styles available for the "auth-su",
249		 * authorisation styles.
250		 */
251		if ((style = login_getstyle(lc, auth_method, "su")) == NULL)
252			errx(1, "auth method available for su.\n");
253		if (authenticate(user, lc ? lc->lc_class : "default", style, "su") != 0) {
254#ifdef WHEELSU
255			if (!iswheelsu || authenticate(username, lc ? lc->lc_class : "default", style, "su") != 0) {
256#endif /* WHEELSU */
257			{
258			fprintf(stderr, "Sorry\n");
259			syslog(LOG_AUTH|LOG_WARNING,"BAD SU %s to %s%s", username, user, ontty());
260			exit(1);
261			}
262		}
263
264		/*
265		 * If authentication succeeds, run any approval
266		 * program, if applicable for this class.
267		 */
268		approvep = login_getcapstr(lc, "approve", NULL, NULL);
269		if (approvep==NULL || auth_script(approvep, approvep, username, lc->lc_class, 0) == 0) {
270			int     r = auth_scan(AUTH_OKAY);
271			/* See what the authorise program says */
272			if (!(r & AUTH_ROOTOKAY) && pwd->pw_uid == 0) {
273				fprintf(stderr, "Sorry\n");
274				syslog(LOG_AUTH|LOG_WARNING,"UNAPPROVED ROOT SU %s%s", user, ontty());
275				exit(1);
276			}
277		}
278#else /* !LOGIN_CAP_AUTH */
279#ifdef	SKEY
280#ifdef WHEELSU
281			if (iswheelsu) {
282				pwd = getpwnam(username);
283			}
284#endif /* WHEELSU */
285			p = skey_getpass("Password:", pwd, 1);
286			if (!(!strcmp(pwd->pw_passwd, skey_crypt(p, pwd->pw_passwd, pwd, 1))
287#ifdef WHEELSU
288			      || (iswheelsu && !strcmp(targetpass, crypt(p,targetpass)))
289#endif /* WHEELSU */
290			      )) {
291#else
292			p = getpass("Password:");
293			if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
294#endif
295#ifdef KERBEROS
296	    			if (!use_kerberos || (use_kerberos && kerberos(username, user, pwd->pw_uid, p)))
297#endif
298					{
299					fprintf(stderr, "Sorry\n");
300					syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s%s", username, user, ontty());
301					exit(1);
302				}
303			}
304#ifdef WHEELSU
305			if (iswheelsu) {
306				pwd = getpwnam(user);
307			}
308#endif /* WHEELSU */
309#endif /* LOGIN_CAP_AUTH */
310		}
311		if (pwd->pw_expire && time(NULL) >= pwd->pw_expire) {
312			fprintf(stderr, "Sorry - account expired\n");
313			syslog(LOG_AUTH|LOG_WARNING,
314				"BAD SU %s to %s%s", username,
315				user, ontty());
316			exit(1);
317		}
318	}
319
320	if (asme) {
321		/* if asme and non-standard target shell, must be root */
322		if (!chshell(pwd->pw_shell) && ruid)
323			errx(1, "permission denied (shell).");
324	} else if (pwd->pw_shell && *pwd->pw_shell) {
325		shell = pwd->pw_shell;
326		iscsh = UNSET;
327	} else {
328		shell = _PATH_BSHELL;
329		iscsh = NO;
330	}
331
332	/* if we're forking a csh, we want to slightly muck the args */
333	if (iscsh == UNSET) {
334		p = strrchr(shell, '/');
335		if (p)
336			++p;
337		else
338			p = shell;
339		if ((iscsh = strcmp(p, "csh") ? NO : YES) == NO)
340		    iscsh = strcmp(p, "tcsh") ? NO : YES;
341	}
342
343	(void)setpriority(PRIO_PROCESS, 0, prio);
344
345#ifdef LOGIN_CAP
346	/* Set everything now except the environment & umask */
347	setwhat = LOGIN_SETUSER|LOGIN_SETGROUP|LOGIN_SETRESOURCES|LOGIN_SETPRIORITY;
348	/*
349	 * Don't touch resource/priority settings if -m has been
350	 * used or -l hasn't, and we're not su'ing to root.
351	 */
352        if ((asme || !asthem) && pwd->pw_uid)
353		setwhat &= ~(LOGIN_SETPRIORITY|LOGIN_SETRESOURCES);
354	if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0)
355		err(1, "setusercontext");
356#else
357	/* set permissions */
358	if (setgid(pwd->pw_gid) < 0)
359		err(1, "setgid");
360	if (initgroups(user, pwd->pw_gid))
361		errx(1, "initgroups failed");
362	if (setuid(pwd->pw_uid) < 0)
363		err(1, "setuid");
364#endif
365
366	if (!asme) {
367		if (asthem) {
368			p = getenv("TERM");
369			cleanenv[0] = NULL;
370			environ = cleanenv;
371#ifdef LOGIN_CAP
372			/* set the su'd user's environment & umask */
373			setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH|LOGIN_SETUMASK|LOGIN_SETENV);
374#else
375			(void)setenv("PATH", _PATH_DEFPATH, 1);
376#endif
377			if (p)
378				(void)setenv("TERM", p, 1);
379			if (chdir(pwd->pw_dir) < 0)
380				errx(1, "no directory");
381		}
382		if (asthem || pwd->pw_uid)
383			(void)setenv("USER", pwd->pw_name, 1);
384		(void)setenv("HOME", pwd->pw_dir, 1);
385		(void)setenv("SHELL", shell, 1);
386	}
387	if (iscsh == YES) {
388		if (fastlogin)
389			*np-- = "-f";
390		if (asme)
391			*np-- = "-m";
392	}
393
394	/* csh strips the first character... */
395	*np = asthem ? "-su" : iscsh == YES ? "_su" : "su";
396
397	if (ruid != 0)
398		syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
399		    username, user, ontty());
400
401	login_close(lc);
402
403	execv(shell, np);
404	err(1, "%s", shell);
405}
406
407static void
408usage()
409{
410	(void)fprintf(stderr, "usage: su [%s] [login [args]]\n", ARGSTR);
411	exit(1);
412}
413
414int
415chshell(sh)
416	char *sh;
417{
418	int  r = 0;
419	char *cp;
420
421	setusershell();
422	while (!r && (cp = getusershell()) != NULL)
423		r = strcmp(cp, sh) == 0;
424	endusershell();
425	return r;
426}
427
428char *
429ontty()
430{
431	char *p;
432	static char buf[MAXPATHLEN + 4];
433
434	buf[0] = 0;
435	p = ttyname(STDERR_FILENO);
436	if (p)
437		snprintf(buf, sizeof(buf), " on %s", p);
438	return (buf);
439}
440
441#ifdef KERBEROS
442int
443kerberos(username, user, uid, pword)
444	char *username, *user;
445	int uid;
446	char *pword;
447{
448	extern char *krb_err_txt[];
449	KTEXT_ST ticket;
450	AUTH_DAT authdata;
451	int kerno;
452	u_long faddr;
453	struct sockaddr_in local_addr;
454	char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN];
455	char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
456	char *krb_get_phost();
457
458	if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
459		return (1);
460	(void)sprintf(krbtkfile, "%s_%s_%lu", TKT_ROOT, user,
461	    (unsigned long)getuid());
462
463	(void)setenv("KRBTKFILE", krbtkfile, 1);
464	(void)krb_set_tkt_string(krbtkfile);
465	/*
466	 * Set real as well as effective ID to 0 for the moment,
467	 * to make the kerberos library do the right thing.
468	 */
469	if (setuid(0) < 0) {
470		warn("setuid");
471		return (1);
472	}
473
474	/*
475	 * Little trick here -- if we are su'ing to root,
476	 * we need to get a ticket for "xxx.root", where xxx represents
477	 * the name of the person su'ing.  Otherwise (non-root case),
478	 * we need to get a ticket for "yyy.", where yyy represents
479	 * the name of the person being su'd to, and the instance is null
480	 *
481	 * We should have a way to set the ticket lifetime,
482	 * with a system default for root.
483	 */
484	kerno = krb_get_pw_in_tkt((uid == 0 ? username : user),
485		(uid == 0 ? "root" : ""), lrealm,
486	    	"krbtgt", lrealm, DEFAULT_TKT_LIFE, pword);
487
488	if (kerno != KSUCCESS) {
489		if (kerno == KDC_PR_UNKNOWN) {
490			warnx("kerberos: principal unknown: %s.%s@%s",
491				(uid == 0 ? username : user),
492				(uid == 0 ? "root" : ""), lrealm);
493			return (1);
494		}
495		warnx("kerberos: unable to su: %s", krb_err_txt[kerno]);
496		syslog(LOG_NOTICE|LOG_AUTH,
497		    "BAD Kerberos SU: %s to %s%s: %s",
498		    username, user, ontty(), krb_err_txt[kerno]);
499		return (1);
500	}
501
502	if (chown(krbtkfile, uid, -1) < 0) {
503		warn("chown");
504		(void)unlink(krbtkfile);
505		return (1);
506	}
507
508	(void)setpriority(PRIO_PROCESS, 0, -2);
509
510	if (gethostname(hostname, sizeof(hostname)) == -1) {
511		warn("gethostname");
512		dest_tkt();
513		return (1);
514	}
515
516	(void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost));
517	savehost[sizeof(savehost) - 1] = '\0';
518
519	kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33);
520
521	if (kerno == KDC_PR_UNKNOWN) {
522		warnx("Warning: TGT not verified.");
523		syslog(LOG_NOTICE|LOG_AUTH,
524		    "%s to %s%s, TGT not verified (%s); %s.%s not registered?",
525		    username, user, ontty(), krb_err_txt[kerno],
526		    "rcmd", savehost);
527	} else if (kerno != KSUCCESS) {
528		warnx("Unable to use TGT: %s", krb_err_txt[kerno]);
529		syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s",
530		    username, user, ontty(), krb_err_txt[kerno]);
531		dest_tkt();
532		return (1);
533	} else {
534		if ((kerno = krb_get_local_addr(&local_addr)) != KSUCCESS) {
535			warnx("Unable to get our local address: %s",
536			      krb_err_txt[kerno]);
537			dest_tkt();
538			return (1);
539		}
540		faddr = local_addr.sin_addr.s_addr;
541		if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
542		    &authdata, "")) != KSUCCESS) {
543			warnx("kerberos: unable to verify rcmd ticket: %s\n",
544			    krb_err_txt[kerno]);
545			syslog(LOG_NOTICE|LOG_AUTH,
546			    "failed su: %s to %s%s: %s", username,
547			     user, ontty(), krb_err_txt[kerno]);
548			dest_tkt();
549			return (1);
550		}
551	}
552	return (0);
553}
554
555int
556koktologin(name, toname)
557	char *name, *toname;
558{
559	AUTH_DAT *kdata;
560	AUTH_DAT kdata_st;
561	char realm[REALM_SZ];
562
563	if (krb_get_lrealm(realm, 1) != KSUCCESS)
564		return (1);
565	kdata = &kdata_st;
566	memset((char *)kdata, 0, sizeof(*kdata));
567	(void)strncpy(kdata->pname, name, sizeof kdata->pname - 1);
568	(void)strncpy(kdata->pinst,
569	    ((strcmp(toname, "root") == 0) ? "root" : ""), sizeof kdata->pinst - 1);
570	(void)strncpy(kdata->prealm, realm, sizeof kdata->prealm - 1);
571	return (kuserok(kdata, toname));
572}
573#endif
574