1 /*
2 * Copyright (c) 1988 The Regents of the University of California.
3 * 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
35 char copyright[] =
36 "@(#) Copyright (c) 1988 The Regents of the University of California.\n\
37 All rights reserved.\n";
38 #endif /* not lint */
39
40 #ifndef lint
41 static char sccsid[] = "@(#)su.c 5.26 (Berkeley) 7/6/91";
42 #endif /* not lint */
43
44 #include <sys/param.h>
45 #include <sys/time.h>
46 #include <sys/resource.h>
47 #include <syslog.h>
48 #include <stdio.h>
49 #include <pwd.h>
50 #include <grp.h>
51 #include <string.h>
52 #include <unistd.h>
53 #include <paths.h>
54
55 #ifdef KERBEROS
56 #include <kerberosIV/des.h>
57 #include <kerberosIV/krb.h>
58 #include <netdb.h>
59
60 #define ARGSTR "-Kflm"
61
62 int use_kerberos = 1;
63 #else
64 #define ARGSTR "-flm"
65 #endif
66
main(argc,argv)67 main(argc, argv)
68 int argc;
69 char **argv;
70 {
71 extern char **environ;
72 extern int errno, optind;
73 register struct passwd *pwd;
74 register char *p, **g;
75 struct group *gr;
76 uid_t ruid, getuid();
77 int asme, ch, asthem, fastlogin, prio;
78 enum { UNSET, YES, NO } iscsh = UNSET;
79 char *user, *shell, *username, *cleanenv[2], *nargv[4], **np;
80 char shellbuf[PATH_MAX];
81 char *crypt(), *getpass(), *getenv(), *getlogin(), *ontty();
82
83 np = &nargv[3];
84 *np-- = NULL;
85 asme = asthem = fastlogin = 0;
86 while ((ch = getopt(argc, argv, ARGSTR)) != EOF)
87 switch((char)ch) {
88 #ifdef KERBEROS
89 case 'K':
90 use_kerberos = 0;
91 break;
92 #endif
93 case 'f':
94 fastlogin = 1;
95 break;
96 case '-':
97 case 'l':
98 asme = 0;
99 asthem = 1;
100 break;
101 case 'm':
102 asme = 1;
103 asthem = 0;
104 break;
105 case '?':
106 default:
107 (void)fprintf(stderr, "usage: su [%s] [login]\n",
108 ARGSTR);
109 exit(1);
110 }
111 argv += optind;
112
113 errno = 0;
114 prio = getpriority(PRIO_PROCESS, 0);
115 if (errno)
116 prio = 0;
117 (void)setpriority(PRIO_PROCESS, 0, -2);
118 openlog("su", LOG_CONS, 0);
119
120 /* get current login name and shell */
121 ruid = getuid();
122 username = getlogin();
123 if (username == NULL || (pwd = getpwnam(username)) == NULL ||
124 pwd->pw_uid != ruid)
125 pwd = getpwuid(ruid);
126 if (pwd == NULL) {
127 fprintf(stderr, "su: who are you?\n");
128 exit(1);
129 }
130 username = strdup(pwd->pw_name);
131 if (asme)
132 if (pwd->pw_shell && *pwd->pw_shell)
133 shell = strcpy(shellbuf, pwd->pw_shell);
134 else {
135 shell = _PATH_BSHELL;
136 iscsh = NO;
137 }
138
139 /* get target login information, default to root */
140 user = *argv ? *argv : "root";
141 if ((pwd = getpwnam(user)) == NULL) {
142 fprintf(stderr, "su: unknown login %s\n", user);
143 exit(1);
144 }
145
146 if (ruid) {
147 #ifdef KERBEROS
148 if (!use_kerberos || kerberos(username, user, pwd->pw_uid))
149 #endif
150 {
151 /* only allow those in group zero to su to root. */
152 if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)))
153 for (g = gr->gr_mem;; ++g) {
154 if (!*g) {
155 (void)fprintf(stderr,
156 "su: you are not in the correct group to su %s.\n",
157 user);
158 exit(1);
159 }
160 if (!strcmp(username, *g))
161 break;
162 }
163 /* if target requires a password, verify it */
164 if (*pwd->pw_passwd) {
165 p = getpass("Password:");
166 #ifdef DES
167 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
168 #else
169 if (strcmp(pwd->pw_passwd, p)) {
170 #endif
171 fprintf(stderr, "Sorry\n");
172 syslog(LOG_AUTH|LOG_WARNING,
173 "BAD SU %s to %s%s", username,
174 user, ontty());
175 exit(1);
176 }
177 }
178 }
179 }
180
181 if (asme) {
182 /* if asme and non-standard target shell, must be root */
183 if (!chshell(pwd->pw_shell) && ruid) {
184 (void)fprintf(stderr,
185 "su: permission denied (shell).\n");
186 exit(1);
187 }
188 } else if (pwd->pw_shell && *pwd->pw_shell) {
189 shell = pwd->pw_shell;
190 iscsh = UNSET;
191 } else {
192 shell = _PATH_BSHELL;
193 iscsh = NO;
194 }
195
196 /* if we're forking a csh, we want to slightly muck the args */
197 if (iscsh == UNSET) {
198 if (p = rindex(shell, '/'))
199 ++p;
200 else
201 p = shell;
202 iscsh = strcmp(p, "csh") ? NO : YES;
203 }
204
205 /* set permissions */
206 if (setgid(pwd->pw_gid) < 0) {
207 perror("su: setgid");
208 exit(1);
209 }
210 if (initgroups(user, pwd->pw_gid)) {
211 (void)fprintf(stderr, "su: initgroups failed.\n");
212 exit(1);
213 }
214 if (setuid(pwd->pw_uid) < 0) {
215 perror("su: setuid");
216 exit(1);
217 }
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 fprintf(stderr, "su: no directory\n");
228 exit(1);
229 }
230 }
231 if (asthem || pwd->pw_uid)
232 (void)setenv("USER", pwd->pw_name, 1);
233 (void)setenv("HOME", pwd->pw_dir, 1);
234 (void)setenv("SHELL", shell, 1);
235 }
236
237 if (iscsh == YES) {
238 if (fastlogin)
239 *np-- = "-f";
240 if (asme)
241 *np-- = "-m";
242 }
243
244 /* csh strips the first character... */
245 *np = asthem ? "-su" : iscsh == YES ? "_su" : "su";
246
247 if (ruid != 0)
248 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
249 username, user, ontty());
250
251 (void)setpriority(PRIO_PROCESS, 0, prio);
252
253 execv(shell, np);
254 (void)fprintf(stderr, "su: %s not found.\n", shell);
255 exit(1);
256 }
257
chshell(sh)258 chshell(sh)
259 char *sh;
260 {
261 register char *cp;
262 char *getusershell();
263
264 while ((cp = getusershell()) != NULL)
265 if (!strcmp(cp, sh))
266 return (1);
267 return (0);
268 }
269
270 char *
ontty()271 ontty()
272 {
273 char *p, *ttyname();
274 static char buf[PATH_MAX + 4];
275
276 buf[0] = 0;
277 if (p = ttyname(STDERR_FILENO))
278 sprintf(buf, " on %s", p);
279 return (buf);
280 }
281
282 #ifdef KERBEROS
kerberos(username,user,uid)283 kerberos(username, user, uid)
284 char *username, *user;
285 int uid;
286 {
287 extern char *krb_err_txt[];
288 KTEXT_ST ticket;
289 AUTH_DAT authdata;
290 struct hostent *hp;
291 register char *p;
292 int kerno;
293 u_long faddr;
294 char lrealm[REALM_SZ], krbtkfile[PATH_MAX];
295 char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
296 char *ontty(), *krb_get_phost();
297
298 if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
299 return (1);
300 if (koktologin(username, lrealm, user) && !uid) {
301 (void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user);
302 return (1);
303 }
304 (void)sprintf(krbtkfile, "%s_%s_%d", TKT_ROOT, user, getuid());
305
306 (void)setenv("KRBTKFILE", krbtkfile, 1);
307 (void)krb_set_tkt_string(krbtkfile);
308 /*
309 * Set real as well as effective ID to 0 for the moment,
310 * to make the kerberos library do the right thing.
311 */
312 if (setuid(0) < 0) {
313 perror("su: setuid");
314 return (1);
315 }
316
317 /*
318 * Little trick here -- if we are su'ing to root,
319 * we need to get a ticket for "xxx.root", where xxx represents
320 * the name of the person su'ing. Otherwise (non-root case),
321 * we need to get a ticket for "yyy.", where yyy represents
322 * the name of the person being su'd to, and the instance is null
323 *
324 * We should have a way to set the ticket lifetime,
325 * with a system default for root.
326 */
327 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user),
328 (uid == 0 ? "root" : ""), lrealm,
329 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0);
330
331 if (kerno != KSUCCESS) {
332 if (kerno == KDC_PR_UNKNOWN) {
333 fprintf(stderr, "principal unknown: %s.%s@%s\n",
334 (uid == 0 ? username : user),
335 (uid == 0 ? "root" : ""), lrealm);
336 return (1);
337 }
338 (void)fprintf(stderr, "su: unable to su: %s\n",
339 krb_err_txt[kerno]);
340 syslog(LOG_NOTICE|LOG_AUTH,
341 "BAD Kerberos SU: %s to %s%s: %s",
342 username, user, ontty(), krb_err_txt[kerno]);
343 return (1);
344 }
345
346 if (chown(krbtkfile, uid, -1) < 0) {
347 perror("su: chown:");
348 (void)unlink(krbtkfile);
349 return (1);
350 }
351
352 (void)setpriority(PRIO_PROCESS, 0, -2);
353
354 if (gethostname(hostname, sizeof(hostname)) == -1) {
355 perror("su: gethostname");
356 dest_tkt();
357 return (1);
358 }
359
360 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost));
361 savehost[sizeof(savehost) - 1] = '\0';
362
363 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33);
364
365 if (kerno == KDC_PR_UNKNOWN) {
366 (void)fprintf(stderr, "Warning: TGT not verified.\n");
367 syslog(LOG_NOTICE|LOG_AUTH,
368 "%s to %s%s, TGT not verified (%s); %s.%s not registered?",
369 username, user, ontty(), krb_err_txt[kerno],
370 "rcmd", savehost);
371 } else if (kerno != KSUCCESS) {
372 (void)fprintf(stderr, "Unable to use TGT: %s\n",
373 krb_err_txt[kerno]);
374 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s",
375 username, user, ontty(), krb_err_txt[kerno]);
376 dest_tkt();
377 return (1);
378 } else {
379 if (!(hp = gethostbyname(hostname))) {
380 (void)fprintf(stderr, "su: can't get addr of %s\n",
381 hostname);
382 dest_tkt();
383 return (1);
384 }
385 (void)bcopy((char *)hp->h_addr, (char *)&faddr, sizeof(faddr));
386
387 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
388 &authdata, "")) != KSUCCESS) {
389 (void)fprintf(stderr,
390 "su: unable to verify rcmd ticket: %s\n",
391 krb_err_txt[kerno]);
392 syslog(LOG_NOTICE|LOG_AUTH,
393 "failed su: %s to %s%s: %s", username,
394 user, ontty(), krb_err_txt[kerno]);
395 dest_tkt();
396 return (1);
397 }
398 }
399 return (0);
400 }
401
koktologin(name,realm,toname)402 koktologin(name, realm, toname)
403 char *name, *realm, *toname;
404 {
405 register AUTH_DAT *kdata;
406 AUTH_DAT kdata_st;
407
408 kdata = &kdata_st;
409 bzero((caddr_t) kdata, sizeof(*kdata));
410 (void)strcpy(kdata->pname, name);
411 (void)strcpy(kdata->pinst,
412 ((strcmp(toname, "root") == 0) ? "root" : ""));
413 (void)strcpy(kdata->prealm, realm);
414 return (kuserok(kdata, toname));
415 }
416 #endif
417