su.c revision 3702 
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 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
41static char sccsid[] = "@(#)su.c	8.3 (Berkeley) 4/2/94";
42#endif /* not lint */
43
44#include <sys/param.h>
45#include <sys/time.h>
46#include <sys/resource.h>
47
48#include <err.h>
49#include <errno.h>
50#include <grp.h>
51#include <paths.h>
52#include <pwd.h>
53#include <stdio.h>
54#include <stdlib.h>
55#include <string.h>
56#include <syslog.h>
57#include <unistd.h>
58
59#ifdef	SKEY
60#include <skey.h>
61#endif
62
63#ifdef KERBEROS
64#include <kerberosIV/des.h>
65#include <kerberosIV/krb.h>
66#include <netdb.h>
67
68#define	ARGSTR	"-Kflm"
69
70int use_kerberos = 1;
71#else
72#define	ARGSTR	"-flm"
73#endif
74
75char   *ontty __P((void));
76int	chshell __P((char *));
77
78int
79main(argc, argv)
80	int argc;
81	char **argv;
82{
83	extern char **environ;
84	struct passwd *pwd;
85	char *p, **g, *user, *shell, *username, *cleanenv[2], *nargv[4], **np;
86	struct group *gr;
87	uid_t ruid;
88	int asme, ch, asthem, fastlogin, prio;
89	enum { UNSET, YES, NO } iscsh = UNSET;
90	char shellbuf[MAXPATHLEN];
91
92	np = &nargv[3];
93	*np-- = NULL;
94	asme = asthem = fastlogin = 0;
95	while ((ch = getopt(argc, argv, ARGSTR)) != EOF)
96		switch((char)ch) {
97#ifdef KERBEROS
98		case 'K':
99			use_kerberos = 0;
100			break;
101#endif
102		case 'f':
103			fastlogin = 1;
104			break;
105		case '-':
106		case 'l':
107			asme = 0;
108			asthem = 1;
109			break;
110		case 'm':
111			asme = 1;
112			asthem = 0;
113			break;
114		case '?':
115		default:
116			(void)fprintf(stderr, "usage: su [%s] [login]\n",
117			    ARGSTR);
118			exit(1);
119		}
120	argv += optind;
121
122	errno = 0;
123	prio = getpriority(PRIO_PROCESS, 0);
124	if (errno)
125		prio = 0;
126	(void)setpriority(PRIO_PROCESS, 0, -2);
127	openlog("su", LOG_CONS, 0);
128
129	/* get current login name and shell */
130	ruid = getuid();
131	username = getlogin();
132	if (username == NULL || (pwd = getpwnam(username)) == NULL ||
133	    pwd->pw_uid != ruid)
134		pwd = getpwuid(ruid);
135	if (pwd == NULL)
136		errx(1, "who are you?");
137	username = strdup(pwd->pw_name);
138	if (username == NULL)
139		err(1, NULL);
140	if (asme)
141		if (pwd->pw_shell && *pwd->pw_shell)
142			shell = strcpy(shellbuf,  pwd->pw_shell);
143		else {
144			shell = _PATH_BSHELL;
145			iscsh = NO;
146		}
147
148	/* get target login information, default to root */
149	user = *argv ? *argv : "root";
150	if ((pwd = getpwnam(user)) == NULL) {
151		fprintf(stderr, "su: unknown login %s\n", user);
152		exit(1);
153	}
154
155	if (ruid) {
156#ifdef KERBEROS
157	    if (!use_kerberos || kerberos(username, user, pwd->pw_uid))
158#endif
159	    {
160		/* only allow those in group zero to su to root. */
161		if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)))
162			for (g = gr->gr_mem;; ++g) {
163				if (!*g)
164					errx(1,
165			    "you are not in the correct group to su %s.",
166					    user);
167				if (strcmp(username, *g) == 0)
168					break;
169		}
170		/* if target requires a password, verify it */
171		if (*pwd->pw_passwd) {
172#ifdef	SKEY
173			p = skey_getpass("Password:", pwd, 1);
174			if (strcmp(pwd->pw_passwd,
175				   skey_crypt(p, pwd->pw_passwd, pwd, 1))) {
176#else
177			p = getpass("Password:");
178			if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
179#endif
180				fprintf(stderr, "Sorry\n");
181				syslog(LOG_AUTH|LOG_WARNING,
182					"BAD SU %s to %s%s", username,
183					user, ontty());
184				exit(1);
185			}
186		}
187	    }
188	}
189
190	if (asme) {
191		/* if asme and non-standard target shell, must be root */
192		if (!chshell(pwd->pw_shell) && ruid)
193			errx(1, "permission denied (shell).");
194	} else if (pwd->pw_shell && *pwd->pw_shell) {
195		shell = pwd->pw_shell;
196		iscsh = UNSET;
197	} else {
198		shell = _PATH_BSHELL;
199		iscsh = NO;
200	}
201
202	/* if we're forking a csh, we want to slightly muck the args */
203	if (iscsh == UNSET) {
204		if (p = strrchr(shell, '/'))
205			++p;
206		else
207			p = shell;
208		iscsh = strcmp(p, "csh") ? NO : YES;
209	}
210
211	/* set permissions */
212	if (setgid(pwd->pw_gid) < 0)
213		err(1, "setgid");
214	if (initgroups(user, pwd->pw_gid))
215		errx(1, "initgroups failed");
216	if (setuid(pwd->pw_uid) < 0)
217		err(1, "setuid");
218
219	if (!asme) {
220		if (asthem) {
221			p = getenv("TERM");
222			cleanenv[0] = _PATH_DEFPATH;
223			cleanenv[1] = NULL;
224			environ = cleanenv;
225			(void)setenv("TERM", p, 1);
226			if (chdir(pwd->pw_dir) < 0)
227				errx(1, "no directory");
228		}
229		if (asthem || pwd->pw_uid)
230			(void)setenv("USER", pwd->pw_name, 1);
231		(void)setenv("HOME", pwd->pw_dir, 1);
232		(void)setenv("SHELL", shell, 1);
233	}
234
235	if (iscsh == YES) {
236		if (fastlogin)
237			*np-- = "-f";
238		if (asme)
239			*np-- = "-m";
240	}
241
242	/* csh strips the first character... */
243	*np = asthem ? "-su" : iscsh == YES ? "_su" : "su";
244
245	if (ruid != 0)
246		syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
247		    username, user, ontty());
248
249	(void)setpriority(PRIO_PROCESS, 0, prio);
250
251	execv(shell, np);
252	err(1, "%s", shell);
253}
254
255int
256chshell(sh)
257	char *sh;
258{
259	char *cp;
260
261	while ((cp = getusershell()) != NULL)
262		if (strcmp(cp, sh) == 0)
263			return (1);
264	return (0);
265}
266
267char *
268ontty()
269{
270	char *p;
271	static char buf[MAXPATHLEN + 4];
272
273	buf[0] = 0;
274	if (p = ttyname(STDERR_FILENO))
275		snprintf(buf, sizeof(buf), " on %s", p);
276	return (buf);
277}
278
279#ifdef KERBEROS
280kerberos(username, user, uid)
281	char *username, *user;
282	int uid;
283{
284	extern char *krb_err_txt[];
285	KTEXT_ST ticket;
286	AUTH_DAT authdata;
287	struct hostent *hp;
288	char *p;
289	int kerno;
290	u_long faddr;
291	char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN];
292	char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
293	char *krb_get_phost();
294
295	if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
296		return (1);
297	if (koktologin(username, lrealm, user) && !uid) {
298		warnx("kerberos: not in %s's ACL.", user);
299		return (1);
300	}
301	(void)sprintf(krbtkfile, "%s_%s_%d", TKT_ROOT, user, getuid());
302
303	(void)setenv("KRBTKFILE", krbtkfile, 1);
304	(void)krb_set_tkt_string(krbtkfile);
305	/*
306	 * Set real as well as effective ID to 0 for the moment,
307	 * to make the kerberos library do the right thing.
308	 */
309	if (setuid(0) < 0) {
310		warn("setuid");
311		return (1);
312	}
313
314	/*
315	 * Little trick here -- if we are su'ing to root,
316	 * we need to get a ticket for "xxx.root", where xxx represents
317	 * the name of the person su'ing.  Otherwise (non-root case),
318	 * we need to get a ticket for "yyy.", where yyy represents
319	 * the name of the person being su'd to, and the instance is null
320	 *
321	 * We should have a way to set the ticket lifetime,
322	 * with a system default for root.
323	 */
324	kerno = krb_get_pw_in_tkt((uid == 0 ? username : user),
325		(uid == 0 ? "root" : ""), lrealm,
326	    	"krbtgt", lrealm, DEFAULT_TKT_LIFE, 0);
327
328	if (kerno != KSUCCESS) {
329		if (kerno == KDC_PR_UNKNOWN) {
330			warnx("kerberos: principal unknown: %s.%s@%s",
331				(uid == 0 ? username : user),
332				(uid == 0 ? "root" : ""), lrealm);
333			return (1);
334		}
335		warnx("kerberos: unable to su: %s", krb_err_txt[kerno]);
336		syslog(LOG_NOTICE|LOG_AUTH,
337		    "BAD Kerberos SU: %s to %s%s: %s",
338		    username, user, ontty(), krb_err_txt[kerno]);
339		return (1);
340	}
341
342	if (chown(krbtkfile, uid, -1) < 0) {
343		warn("chown");
344		(void)unlink(krbtkfile);
345		return (1);
346	}
347
348	(void)setpriority(PRIO_PROCESS, 0, -2);
349
350	if (gethostname(hostname, sizeof(hostname)) == -1) {
351		warn("gethostname");
352		dest_tkt();
353		return (1);
354	}
355
356	(void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost));
357	savehost[sizeof(savehost) - 1] = '\0';
358
359	kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33);
360
361	if (kerno == KDC_PR_UNKNOWN) {
362		warnx("Warning: TGT not verified.");
363		syslog(LOG_NOTICE|LOG_AUTH,
364		    "%s to %s%s, TGT not verified (%s); %s.%s not registered?",
365		    username, user, ontty(), krb_err_txt[kerno],
366		    "rcmd", savehost);
367	} else if (kerno != KSUCCESS) {
368		warnx("Unable to use TGT: %s", krb_err_txt[kerno]);
369		syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s",
370		    username, user, ontty(), krb_err_txt[kerno]);
371		dest_tkt();
372		return (1);
373	} else {
374		if (!(hp = gethostbyname(hostname))) {
375			warnx("can't get addr of %s", hostname);
376			dest_tkt();
377			return (1);
378		}
379		memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr));
380
381		if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
382		    &authdata, "")) != KSUCCESS) {
383			warnx("kerberos: unable to verify rcmd ticket: %s\n",
384			    krb_err_txt[kerno]);
385			syslog(LOG_NOTICE|LOG_AUTH,
386			    "failed su: %s to %s%s: %s", username,
387			     user, ontty(), krb_err_txt[kerno]);
388			dest_tkt();
389			return (1);
390		}
391	}
392	return (0);
393}
394
395koktologin(name, realm, toname)
396	char *name, *realm, *toname;
397{
398	AUTH_DAT *kdata;
399	AUTH_DAT kdata_st;
400
401	kdata = &kdata_st;
402	memset((char *)kdata, 0, sizeof(*kdata));
403	(void)strcpy(kdata->pname, name);
404	(void)strcpy(kdata->pinst,
405	    ((strcmp(toname, "root") == 0) ? "root" : ""));
406	(void)strcpy(kdata->prealm, realm);
407	return (kuserok(kdata, toname));
408}
409#endif
410