su.c revision 29923 
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	"$Id$";
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 <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, **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#ifdef KERBEROS
118	char *k;
119#endif
120	char shellbuf[MAXPATHLEN];
121
122#ifdef WHEELSU
123	iswheelsu =
124#endif /* WHEELSU */
125	asme = asthem = fastlogin = 0;
126	user = "root";
127	while(optind < argc)
128	    if((ch = getopt(argc, argv, ARGSTR)) != -1)
129		switch((char)ch) {
130#ifdef KERBEROS
131		case 'K':
132			use_kerberos = 0;
133			break;
134#endif
135		case 'f':
136			fastlogin = 1;
137			break;
138		case '-':
139		case 'l':
140			asme = 0;
141			asthem = 1;
142			break;
143		case 'm':
144			asme = 1;
145			asthem = 0;
146			break;
147		case '?':
148		default:
149			usage();
150		}
151	    else
152	    {
153		user = argv[optind++];
154		break;
155	    }
156
157	if (user == NULL)
158		usage();
159
160	if ((nargv = malloc (sizeof (char *) * (argc + 4))) == NULL) {
161	    errx(1, "malloc failure");
162	}
163
164	nargv[argc + 3] = NULL;
165	for (i = argc; i >= optind; i--)
166	    nargv[i + 3] = argv[i];
167	np = &nargv[i + 3];
168
169	argv += optind;
170
171	errno = 0;
172	prio = getpriority(PRIO_PROCESS, 0);
173	if (errno)
174		prio = 0;
175	(void)setpriority(PRIO_PROCESS, 0, -2);
176	openlog("su", LOG_CONS, 0);
177
178	/* get current login name and shell */
179	ruid = getuid();
180	username = getlogin();
181	if (username == NULL || (pwd = getpwnam(username)) == NULL ||
182	    pwd->pw_uid != ruid)
183		pwd = getpwuid(ruid);
184	if (pwd == NULL)
185		errx(1, "who are you?");
186	username = strdup(pwd->pw_name);
187	if (username == NULL)
188		err(1, NULL);
189	if (asme) {
190		if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') {
191			/* copy: pwd memory is recycled */
192			shell = strncpy(shellbuf,  pwd->pw_shell, sizeof shellbuf);
193			shellbuf[sizeof shellbuf - 1] = '\0';
194		} else {
195			shell = _PATH_BSHELL;
196			iscsh = NO;
197		}
198	}
199
200#ifdef LOGIN_CAP_AUTH
201	if (auth_method = strchr(user, ':')) {
202		*auth_method = '\0';
203		auth_method++;
204		if (*auth_method == '\0')
205			auth_method = NULL;
206	}
207#endif /* !LOGIN_CAP_AUTH */
208
209	/* get target login information, default to root */
210	if ((pwd = getpwnam(user)) == NULL) {
211		errx(1, "unknown login: %s", user);
212	}
213#ifdef LOGIN_CAP
214	lc = login_getpwclass(pwd);
215#endif
216
217#ifdef WHEELSU
218	targetpass = strdup(pwd->pw_passwd);
219#endif /* WHEELSU */
220
221	if (ruid) {
222#ifdef KERBEROS
223		if (use_kerberos && koktologin(username, user)
224		    && !pwd->pw_uid) {
225			warnx("kerberos: not in %s's ACL.", user);
226			use_kerberos = 0;
227		}
228#endif
229		{
230			/* only allow those in group zero to su to root. */
231			if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)) &&
232			    gr->gr_mem && *(gr->gr_mem))
233				for (g = gr->gr_mem;; ++g) {
234					if (!*g)
235						errx(1,
236			    "you are not in the correct group to su %s.",
237						    user);
238					if (strcmp(username, *g) == 0) {
239#ifdef WHEELSU
240						iswheelsu = 1;
241#endif /* WHEELSU */
242						break;
243					}
244				}
245		}
246		/* if target requires a password, verify it */
247		if (*pwd->pw_passwd) {
248#ifdef LOGIN_CAP_AUTH
249		/*
250		 * This hands off authorisation to an authorisation program,
251		 * depending on the styles available for the "auth-su",
252		 * authorisation styles.
253		 */
254		if ((style = login_getstyle(lc, auth_method, "su")) == NULL)
255			errx(1, "auth method available for su.\n");
256		if (authenticate(user, lc ? lc->lc_class : "default", style, "su") != 0) {
257#ifdef WHEELSU
258			if (!iswheelsu || authenticate(username, lc ? lc->lc_class : "default", style, "su") != 0) {
259#endif /* WHEELSU */
260			{
261			fprintf(stderr, "Sorry\n");
262			syslog(LOG_AUTH|LOG_WARNING,"BAD SU %s to %s%s", username, user, ontty());
263			exit(1);
264			}
265		}
266
267		/*
268		 * If authentication succeeds, run any approval
269		 * program, if applicable for this class.
270		 */
271		approvep = login_getcapstr(lc, "approve", NULL, NULL);
272		if (approvep==NULL || auth_script(approvep, approvep, username, lc->lc_class, 0) == 0) {
273			int     r = auth_scan(AUTH_OKAY);
274			/* See what the authorise program says */
275			if (!(r & AUTH_ROOTOKAY) && pwd->pw_uid == 0) {
276				fprintf(stderr, "Sorry\n");
277				syslog(LOG_AUTH|LOG_WARNING,"UNAPPROVED ROOT SU %s%s", user, ontty());
278				exit(1);
279			}
280		}
281#else /* !LOGIN_CAP_AUTH */
282#ifdef	SKEY
283#ifdef WHEELSU
284			if (iswheelsu) {
285				pwd = getpwnam(username);
286			}
287#endif /* WHEELSU */
288			p = skey_getpass("Password:", pwd, 1);
289			if (!(!strcmp(pwd->pw_passwd, skey_crypt(p, pwd->pw_passwd, pwd, 1))
290#ifdef WHEELSU
291			      || (iswheelsu && !strcmp(targetpass, crypt(p,targetpass)))
292#endif /* WHEELSU */
293			      )) {
294#else
295			p = getpass("Password:");
296			if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
297#endif
298#ifdef KERBEROS
299	    			if (!use_kerberos || (use_kerberos && kerberos(username, user, pwd->pw_uid, p)))
300#endif
301					{
302					fprintf(stderr, "Sorry\n");
303					syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s%s", username, user, ontty());
304					exit(1);
305				}
306			}
307#ifdef WHEELSU
308			if (iswheelsu) {
309				pwd = getpwnam(user);
310			}
311#endif /* WHEELSU */
312#endif /* LOGIN_CAP_AUTH */
313		}
314		if (pwd->pw_expire && time(NULL) >= pwd->pw_expire) {
315			fprintf(stderr, "Sorry - account expired\n");
316			syslog(LOG_AUTH|LOG_WARNING,
317				"BAD SU %s to %s%s", username,
318				user, ontty());
319			exit(1);
320		}
321	}
322
323	if (asme) {
324		/* if asme and non-standard target shell, must be root */
325		if (!chshell(pwd->pw_shell) && ruid)
326			errx(1, "permission denied (shell).");
327	} else if (pwd->pw_shell && *pwd->pw_shell) {
328		shell = pwd->pw_shell;
329		iscsh = UNSET;
330	} else {
331		shell = _PATH_BSHELL;
332		iscsh = NO;
333	}
334
335	/* if we're forking a csh, we want to slightly muck the args */
336	if (iscsh == UNSET) {
337		p = strrchr(shell, '/');
338		if (p)
339			++p;
340		else
341			p = shell;
342		if ((iscsh = strcmp(p, "csh") ? NO : YES) == NO)
343		    iscsh = strcmp(p, "tcsh") ? NO : YES;
344	}
345
346	(void)setpriority(PRIO_PROCESS, 0, prio);
347
348#ifdef LOGIN_CAP
349	/* Set everything now except the environment & umask */
350	setwhat = LOGIN_SETUSER|LOGIN_SETGROUP|LOGIN_SETRESOURCES|LOGIN_SETPRIORITY;
351	/*
352	 * Don't touch resource/priority settings if -m has been
353	 * used or -l hasn't, and we're not su'ing to root.
354	 */
355        if ((asme || !asthem) && pwd->pw_uid)
356		setwhat &= ~(LOGIN_SETPRIORITY|LOGIN_SETRESOURCES);
357	if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0)
358		err(1, "setusercontext");
359#else
360	/* set permissions */
361	if (setgid(pwd->pw_gid) < 0)
362		err(1, "setgid");
363	if (initgroups(user, pwd->pw_gid))
364		errx(1, "initgroups failed");
365	if (setuid(pwd->pw_uid) < 0)
366		err(1, "setuid");
367#endif
368
369	if (!asme) {
370		if (asthem) {
371			p = getenv("TERM");
372#ifdef KERBEROS
373			k = getenv("KRBTKFILE");
374#endif
375			if ((cleanenv = calloc(20, sizeof(char*))) == NULL)
376				errx(1, "calloc");
377			cleanenv[0] = NULL;
378			environ = cleanenv;
379#ifdef LOGIN_CAP
380			/* set the su'd user's environment & umask */
381			setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH|LOGIN_SETUMASK|LOGIN_SETENV);
382#else
383			(void)setenv("PATH", _PATH_DEFPATH, 1);
384#endif
385			if (p)
386				(void)setenv("TERM", p, 1);
387#ifdef KERBEROS
388			if (k)
389				(void)setenv("KRBTKFILE", k, 1);
390#endif
391			if (chdir(pwd->pw_dir) < 0)
392				errx(1, "no directory");
393		}
394		if (asthem || pwd->pw_uid)
395			(void)setenv("USER", pwd->pw_name, 1);
396		(void)setenv("HOME", pwd->pw_dir, 1);
397		(void)setenv("SHELL", shell, 1);
398	}
399	if (iscsh == YES) {
400		if (fastlogin)
401			*np-- = "-f";
402		if (asme)
403			*np-- = "-m";
404	}
405
406	/* csh strips the first character... */
407	*np = asthem ? "-su" : iscsh == YES ? "_su" : "su";
408
409	if (ruid != 0)
410		syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
411		    username, user, ontty());
412
413	login_close(lc);
414
415	execv(shell, np);
416	err(1, "%s", shell);
417}
418
419static void
420usage()
421{
422	(void)fprintf(stderr, "usage: su [%s] [login [args]]\n", ARGSTR);
423	exit(1);
424}
425
426int
427chshell(sh)
428	char *sh;
429{
430	int  r = 0;
431	char *cp;
432
433	setusershell();
434	while (!r && (cp = getusershell()) != NULL)
435		r = strcmp(cp, sh) == 0;
436	endusershell();
437	return r;
438}
439
440char *
441ontty()
442{
443	char *p;
444	static char buf[MAXPATHLEN + 4];
445
446	buf[0] = 0;
447	p = ttyname(STDERR_FILENO);
448	if (p)
449		snprintf(buf, sizeof(buf), " on %s", p);
450	return (buf);
451}
452
453#ifdef KERBEROS
454int
455kerberos(username, user, uid, pword)
456	char *username, *user;
457	int uid;
458	char *pword;
459{
460	KTEXT_ST ticket;
461	AUTH_DAT authdata;
462	int kerno;
463	u_long faddr;
464	char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN];
465	char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
466	char *krb_get_phost();
467	struct hostent *hp;
468
469	if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
470		return (1);
471	(void)sprintf(krbtkfile, "%s_%s_%lu", TKT_ROOT, user,
472	    (unsigned long)getuid());
473
474	(void)setenv("KRBTKFILE", krbtkfile, 1);
475	(void)krb_set_tkt_string(krbtkfile);
476	/*
477	 * Set real as well as effective ID to 0 for the moment,
478	 * to make the kerberos library do the right thing.
479	 */
480	if (setuid(0) < 0) {
481		warn("setuid");
482		return (1);
483	}
484
485	/*
486	 * Little trick here -- if we are su'ing to root,
487	 * we need to get a ticket for "xxx.root", where xxx represents
488	 * the name of the person su'ing.  Otherwise (non-root case),
489	 * we need to get a ticket for "yyy.", where yyy represents
490	 * the name of the person being su'd to, and the instance is null
491	 *
492	 * We should have a way to set the ticket lifetime,
493	 * with a system default for root.
494	 */
495	kerno = krb_get_pw_in_tkt((uid == 0 ? username : user),
496		(uid == 0 ? "root" : ""), lrealm,
497	    	"krbtgt", lrealm, DEFAULT_TKT_LIFE, pword);
498
499	if (kerno != KSUCCESS) {
500		if (kerno == KDC_PR_UNKNOWN) {
501			warnx("kerberos: principal unknown: %s.%s@%s",
502				(uid == 0 ? username : user),
503				(uid == 0 ? "root" : ""), lrealm);
504			return (1);
505		}
506		warnx("kerberos: unable to su: %s", krb_err_txt[kerno]);
507		syslog(LOG_NOTICE|LOG_AUTH,
508		    "BAD Kerberos SU: %s to %s%s: %s",
509		    username, user, ontty(), krb_err_txt[kerno]);
510		return (1);
511	}
512
513	if (chown(krbtkfile, uid, -1) < 0) {
514		warn("chown");
515		(void)unlink(krbtkfile);
516		return (1);
517	}
518
519	(void)setpriority(PRIO_PROCESS, 0, -2);
520
521	if (gethostname(hostname, sizeof(hostname)) == -1) {
522		warn("gethostname");
523		dest_tkt();
524		return (1);
525	}
526
527	(void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost));
528	savehost[sizeof(savehost) - 1] = '\0';
529
530	kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33);
531
532	if (kerno == KDC_PR_UNKNOWN) {
533		warnx("Warning: TGT not verified.");
534		syslog(LOG_NOTICE|LOG_AUTH,
535		    "%s to %s%s, TGT not verified (%s); %s.%s not registered?",
536		    username, user, ontty(), krb_err_txt[kerno],
537		    "rcmd", savehost);
538	} else if (kerno != KSUCCESS) {
539		warnx("Unable to use TGT: %s", krb_err_txt[kerno]);
540		syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s",
541		    username, user, ontty(), krb_err_txt[kerno]);
542		dest_tkt();
543		return (1);
544	} else {
545		if (!(hp = gethostbyname(hostname))) {
546			warnx("can't get addr of %s", hostname);
547			dest_tkt();
548			return (1);
549		}
550		memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr));
551
552		if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
553		    &authdata, "")) != KSUCCESS) {
554			warnx("kerberos: unable to verify rcmd ticket: %s\n",
555			    krb_err_txt[kerno]);
556			syslog(LOG_NOTICE|LOG_AUTH,
557			    "failed su: %s to %s%s: %s", username,
558			     user, ontty(), krb_err_txt[kerno]);
559			dest_tkt();
560			return (1);
561		}
562	}
563	return (0);
564}
565
566int
567koktologin(name, toname)
568	char *name, *toname;
569{
570	AUTH_DAT *kdata;
571	AUTH_DAT kdata_st;
572	char realm[REALM_SZ];
573
574	if (krb_get_lrealm(realm, 1) != KSUCCESS)
575		return (1);
576	kdata = &kdata_st;
577	memset((char *)kdata, 0, sizeof(*kdata));
578	(void)strncpy(kdata->pname, name, sizeof kdata->pname - 1);
579	(void)strncpy(kdata->pinst,
580	    ((strcmp(toname, "root") == 0) ? "root" : ""), sizeof kdata->pinst - 1);
581	(void)strncpy(kdata->prealm, realm, sizeof kdata->prealm - 1);
582	return (kuserok(kdata, toname));
583}
584#endif
585