xref: /freebsd/crypto/heimdal/appl/su/su.c (revision 41466b50c1d5bfd1cf6adaae547a579a75d7c04e)
1 /*
2  * Copyright (c) 1999 - 2001 Kungliga Tekniska H�gskolan
3  * (Royal Institute of Technology, Stockholm, Sweden).
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  *
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  *
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * 3. Neither the name of KTH nor the names of its contributors may be
18  *    used to endorse or promote products derived from this software without
19  *    specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY KTH AND ITS CONTRIBUTORS ``AS IS'' AND ANY
22  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL KTH OR ITS CONTRIBUTORS BE
25  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
28  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
29  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
30  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
31  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
32 
33 #include <config.h>
34 
35 RCSID("$Id: su.c,v 1.20 2001/02/20 01:44:48 assar Exp $");
36 
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <string.h>
40 
41 #include <syslog.h>
42 
43 #ifdef HAVE_PATHS_H
44 #include <paths.h>
45 #endif
46 
47 #ifdef HAVE_SHADOW_H
48 #include <shadow.h>
49 #endif
50 
51 #include <pwd.h>
52 
53 #ifdef HAVE_OPENSSL_DES_H
54 #include <openssl/des.h>
55 #else
56 #include <des.h>
57 #endif
58 #include <krb5.h>
59 #include <kafs.h>
60 #include <err.h>
61 #include <roken.h>
62 #include <getarg.h>
63 #include <kafs.h>
64 
65 #ifndef _PATH_DEFPATH
66 #define _PATH_DEFPATH "/usr/bin:/bin"
67 #endif
68 
69 #ifndef _PATH_BSHELL
70 #define _PATH_BSHELL "/bin/sh"
71 #endif
72 
73 int kerberos_flag = 1;
74 int csh_f_flag;
75 int full_login;
76 int env_flag;
77 char *kerberos_instance = "root";
78 int help_flag;
79 int version_flag;
80 char *cmd;
81 
82 struct getargs args[] = {
83     { "kerberos", 'K', arg_negative_flag, &kerberos_flag,
84       "don't use kerberos" },
85     { NULL,	  'f', arg_flag,	  &csh_f_flag,
86       "don't read .cshrc" },
87     { "full",	  'l', arg_flag,          &full_login,
88       "simulate full login" },
89     { NULL,	  'm', arg_flag,          &env_flag,
90       "leave environment unmodified" },
91     { "instance", 'i', arg_string,        &kerberos_instance,
92       "root instance to use" },
93     { "command",  'c', arg_string,        &cmd,
94       "command to execute" },
95     { "help", 	  'h', arg_flag,          &help_flag },
96     { "version",  0,   arg_flag,          &version_flag },
97 };
98 
99 
100 static void
101 usage (int ret)
102 {
103     arg_printusage (args,
104 		    sizeof(args)/sizeof(*args),
105 		    NULL,
106 		    "[login [shell arguments]]");
107     exit (ret);
108 }
109 
110 static struct passwd*
111 make_info(struct passwd *pwd)
112 {
113     struct passwd *info;
114     info = malloc(sizeof(*info));
115     if(info == NULL)
116 	return NULL;
117     info->pw_name = strdup(pwd->pw_name);
118     info->pw_passwd = strdup(pwd->pw_passwd);
119     info->pw_uid = pwd->pw_uid;
120     info->pw_gid = pwd->pw_gid;
121     info->pw_dir = strdup(pwd->pw_dir);
122     info->pw_shell = strdup(pwd->pw_shell);
123     if(info->pw_name == NULL || info->pw_passwd == NULL ||
124        info->pw_dir == NULL || info->pw_shell == NULL)
125 	return NULL;
126     return info;
127 }
128 
129 #ifdef KRB5
130 static krb5_context context;
131 static krb5_ccache ccache;
132 #endif
133 
134 static int
135 krb5_verify(struct passwd *login_info, struct passwd *su_info,
136 	    const char *kerberos_instance)
137 {
138 #ifdef KRB5
139     krb5_error_code ret;
140     krb5_principal p;
141 
142     ret = krb5_init_context (&context);
143     if (ret) {
144 #if 0
145 	warnx("krb5_init_context failed: %d", ret);
146 #endif
147 	return 1;
148     }
149 
150     if (strcmp (su_info->pw_name, "root") == 0)
151 	ret = krb5_make_principal(context, &p, NULL,
152 				  login_info->pw_name,
153 				  kerberos_instance,
154 				  NULL);
155     else
156 	ret = krb5_make_principal(context, &p, NULL,
157 				  su_info->pw_name,
158 				  NULL);
159     if(ret)
160 	return 1;
161 
162     if(su_info->pw_uid != 0 || krb5_kuserok(context, p, su_info->pw_name)) {
163 	ret = krb5_cc_gen_new(context, &krb5_mcc_ops, &ccache);
164 	if(ret) {
165 #if 1
166 	    krb5_warn(context, ret, "krb5_cc_gen_new");
167 #endif
168 	    krb5_free_principal (context, p);
169 	    return 1;
170 	}
171 	ret = krb5_verify_user_lrealm(context, p, ccache, NULL, TRUE, NULL);
172 	krb5_free_principal (context, p);
173 	if(ret) {
174 	    krb5_cc_destroy(context, ccache);
175 	    switch (ret) {
176 	    case KRB5_LIBOS_PWDINTR :
177 		break;
178 	    case KRB5KRB_AP_ERR_BAD_INTEGRITY:
179 	    case KRB5KRB_AP_ERR_MODIFIED:
180 		krb5_warnx(context, "Password incorrect");
181 		break;
182 	    default :
183 		krb5_warn(context, ret, "krb5_verify_user");
184 		break;
185 	    }
186 	    return 1;
187 	}
188 	return 0;
189     }
190     krb5_free_principal (context, p);
191 #endif
192     return 1;
193 }
194 
195 #ifdef KRB5
196 static int
197 krb5_start_session(void)
198 {
199     krb5_ccache ccache2;
200     char *cc_name;
201     int ret;
202 
203     ret = krb5_cc_gen_new(context, &krb5_fcc_ops, &ccache2);
204     if (ret) {
205 	krb5_cc_destroy(context, ccache);
206 	return 1;
207     }
208 
209     ret = krb5_cc_copy_cache(context, ccache, ccache2);
210 
211     asprintf(&cc_name, "%s:%s", krb5_cc_get_type(context, ccache2),
212 	     krb5_cc_get_name(context, ccache2));
213     esetenv("KRB5CCNAME", cc_name, 1);
214 
215     /* we want to export this even if we don't directly support KRB4 */
216     {
217 #ifndef TKT_ROOT
218 #define TKT_ROOT "/tmp/tkt"
219 #endif
220 	int fd;
221 	char tkfile[256];
222 	strlcpy(tkfile, TKT_ROOT, sizeof(tkfile));
223 	strlcat(tkfile, "_XXXXXX", sizeof(tkfile));
224 	fd = mkstemp(tkfile);
225 	if(fd >= 0) {
226 	    close(fd);
227 	    esetenv("KRBTKFILE", tkfile, 1);
228 	}
229     }
230 
231 #ifdef KRB4
232     /* convert creds? */
233     if(k_hasafs()) {
234 	if (k_setpag() == 0)
235 	    krb5_afslog(context, ccache2, NULL, NULL);
236     }
237 #endif
238 
239     krb5_cc_close(context, ccache2);
240     krb5_cc_destroy(context, ccache);
241     return 0;
242 }
243 #endif
244 
245 static int
246 verify_unix(struct passwd *su)
247 {
248     char prompt[128];
249     char pw_buf[1024];
250     char *pw;
251     int r;
252     if(su->pw_passwd != NULL && *su->pw_passwd != '\0') {
253 	snprintf(prompt, sizeof(prompt), "%s's password: ", su->pw_name);
254 	r = des_read_pw_string(pw_buf, sizeof(pw_buf), prompt, 0);
255 	if(r != 0)
256 	    exit(0);
257 	pw = crypt(pw_buf, su->pw_passwd);
258 	memset(pw_buf, 0, sizeof(pw_buf));
259 	if(strcmp(pw, su->pw_passwd) != 0)
260 	    return 1;
261     }
262     return 0;
263 }
264 
265 int
266 main(int argc, char **argv)
267 {
268     int i, optind = 0;
269     char *su_user;
270     struct passwd *su_info;
271     char *login_user = NULL;
272     struct passwd *login_info;
273 
274     struct passwd *pwd;
275 
276     char *shell;
277 
278     int ok = 0;
279     int kerberos_error=1;
280 
281     setprogname (argv[0]);
282 
283     if(getarg(args, sizeof(args) / sizeof(args[0]), argc, argv, &optind))
284 	usage(1);
285 
286     for (i=0; i < optind; i++)
287       if (strcmp(argv[i], "-") == 0) {
288 	 full_login = 1;
289 	 break;
290       }
291 
292     if(help_flag)
293 	usage(0);
294     if(version_flag) {
295 	print_version(NULL);
296 	exit(0);
297     }
298     if(optind >= argc)
299 	su_user = "root";
300     else
301 	su_user = argv[optind++];
302 
303     pwd = k_getpwnam(su_user);
304     if(pwd == NULL)
305 	errx (1, "unknown login %s", su_user);
306     if (pwd->pw_uid == 0 && strcmp ("root", su_user) != 0) {
307 	syslog (LOG_ALERT, "NIS attack, user %s has uid 0", su_user);
308 	errx (1, "unknown login %s", su_user);
309     }
310     su_info = make_info(pwd);
311 
312 #if defined(HAVE_GETLOGIN) && !defined(POSIX_GETLOGIN)
313     login_user = getlogin();
314 #endif
315     if(login_user == NULL || (pwd = getpwnam(login_user)) == NULL)
316 	pwd = getpwuid(getuid());
317     if(pwd == NULL)
318 	errx(1, "who are you?");
319     login_info = make_info(pwd);
320     if(env_flag)
321 	shell = login_info->pw_shell;
322     else
323 	shell = su_info->pw_shell;
324     if(shell == NULL || *shell == '\0')
325 	shell = _PATH_BSHELL;
326 
327     if(kerberos_flag && ok == 0 &&
328       (kerberos_error=krb5_verify(login_info, su_info, kerberos_instance)) == 0)
329 	ok++;
330 
331     if(ok == 0 && login_info->pw_uid && verify_unix(su_info) != 0) {
332 	printf("Sorry!\n");
333 	exit(1);
334     }
335 
336 #ifdef HAVE_GETSPNAM
337    {  struct spwd *sp;
338       long    today;
339 
340     sp = getspnam(su_info->pw_name);
341     if (sp != NULL) {
342 	today = time(0)/(24L * 60 * 60);
343 	if (sp->sp_expire > 0) {
344 	    if (today >= sp->sp_expire) {
345 		if (login_info->pw_uid)
346 		    errx(1,"Your account has expired.");
347 		else
348 		    printf("Your account has expired.");
349             }
350             else if (sp->sp_expire - today < 14)
351                 printf("Your account will expire in %d days.\n",
352 		       (int)(sp->sp_expire - today));
353 	}
354 	if (sp->sp_max > 0) {
355 	    if (today >= sp->sp_lstchg + sp->sp_max) {
356 		if (login_info->pw_uid)
357 		    errx(1,"Your password has expired. Choose a new one.");
358 		else
359 		    printf("Your password has expired. Choose a new one.");
360 	    }
361 	    else if (today >= sp->sp_lstchg + sp->sp_max - sp->sp_warn)
362 		printf("Your account will expire in %d days.\n",
363 		       (int)(sp->sp_lstchg + sp->sp_max -today));
364 	}
365     }
366     }
367 #endif
368     {
369 	char *tty = ttyname (STDERR_FILENO);
370 	syslog (LOG_NOTICE | LOG_AUTH, tty ? "%s to %s" : "%s to %s on %s",
371 		login_info->pw_name, su_info->pw_name, tty);
372     }
373 
374 
375     if(!env_flag) {
376 	if(full_login) {
377 	    char *t = getenv ("TERM");
378 
379 	    environ = malloc (10 * sizeof (char *));
380 	    if (environ == NULL)
381 		err (1, "malloc");
382 	    environ[0] = NULL;
383 	    esetenv ("PATH", _PATH_DEFPATH, 1);
384 	    if (t)
385 		esetenv ("TERM", t, 1);
386 	    if (chdir (su_info->pw_dir) < 0)
387 		errx (1, "no directory");
388 	}
389 	if (full_login || su_info->pw_uid)
390 	    esetenv ("USER", su_info->pw_name, 1);
391 	esetenv("HOME", su_info->pw_dir, 1);
392 	esetenv("SHELL", shell, 1);
393     }
394 
395     {
396 	int i;
397 	char **args;
398 	char *p;
399 
400 	p = strrchr(shell, '/');
401 	if(p)
402 	    p++;
403 	else
404 	    p = shell;
405 
406 	if (strcmp(p, "csh") != 0)
407 	    csh_f_flag = 0;
408 
409         args = malloc(((cmd ? 2 : 0) + 1 + argc - optind + 1 + csh_f_flag) * sizeof(*args));
410 	if (args == NULL)
411 	    err (1, "malloc");
412 	i = 0;
413 	if(full_login)
414 	    asprintf(&args[i++], "-%s", p);
415 	else
416 	    args[i++] = p;
417 	if (cmd) {
418 	   args[i++] = "-c";
419 	   args[i++] = cmd;
420 	}
421 
422 	if (csh_f_flag)
423 	    args[i++] = "-f";
424 
425 	for (argv += optind; *argv; ++argv)
426 	   args[i++] = *argv;
427 	args[i] = NULL;
428 
429 	if(setgid(su_info->pw_gid) < 0)
430 	    err(1, "setgid");
431 	if (initgroups (su_info->pw_name, su_info->pw_gid) < 0)
432 	    err (1, "initgroups");
433 	if(setuid(su_info->pw_uid) < 0
434 	   || (su_info->pw_uid != 0 && setuid(0) == 0))
435 	    err(1, "setuid");
436 
437 #ifdef KRB5
438         if (!kerberos_error)
439            krb5_start_session();
440 #endif
441 	execv(shell, args);
442     }
443 
444     exit(1);
445 }
446