1 /*
2  *
3  * Copyright (c) 2001 Gert Doering.  All rights reserved.
4  * Copyright (c) 2003,2004,2005,2006 Darren Tucker.  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  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  *
26  */
27 #include "includes.h"
28 
29 #include "xmalloc.h"
30 #include "sshbuf.h"
31 #include "ssherr.h"
32 #include "sshkey.h"
33 #include "hostfile.h"
34 #include "auth.h"
35 #include "ssh.h"
36 #include "ssh_api.h"
37 #include "log.h"
38 
39 #ifdef _AIX
40 
41 #include <errno.h>
42 #if defined(HAVE_NETDB_H)
43 # include <netdb.h>
44 #endif
45 #include <uinfo.h>
46 #include <stdarg.h>
47 #include <string.h>
48 #include <unistd.h>
49 #include <sys/socket.h>
50 
51 #ifdef WITH_AIXAUTHENTICATE
52 # include <login.h>
53 # include <userpw.h>
54 # if defined(HAVE_SYS_AUDIT_H) && defined(AIX_LOGINFAILED_4ARG)
55 #  include <sys/audit.h>
56 # endif
57 # include <usersec.h>
58 #endif
59 
60 #include "port-aix.h"
61 
62 static char *lastlogin_msg = NULL;
63 
64 # ifdef HAVE_SETAUTHDB
65 static char old_registry[REGISTRY_SIZE] = "";
66 # endif
67 
68 /*
69  * AIX has a "usrinfo" area where logname and other stuff is stored -
70  * a few applications actually use this and die if it's not set
71  *
72  * NOTE: TTY= should be set, but since no one uses it and it's hard to
73  * acquire due to privsep code.  We will just drop support.
74  */
75 void
76 aix_usrinfo(struct passwd *pw)
77 {
78 	u_int i;
79 	size_t len;
80 	char *cp;
81 
82 	len = sizeof("LOGNAME= NAME= ") + (2 * strlen(pw->pw_name));
83 	cp = xmalloc(len);
84 
85 	i = snprintf(cp, len, "LOGNAME=%s%cNAME=%s%c", pw->pw_name, '\0',
86 	    pw->pw_name, '\0');
87 	if (usrinfo(SETUINFO, cp, i) == -1)
88 		fatal("Couldn't set usrinfo: %s", strerror(errno));
89 	debug3("AIX/UsrInfo: set len %d", i);
90 
91 	free(cp);
92 }
93 
94 # ifdef WITH_AIXAUTHENTICATE
95 /*
96  * Remove embedded newlines in string (if any).
97  * Used before logging messages returned by AIX authentication functions
98  * so the message is logged on one line.
99  */
100 void
101 aix_remove_embedded_newlines(char *p)
102 {
103 	if (p == NULL)
104 		return;
105 
106 	for (; *p; p++) {
107 		if (*p == '\n')
108 			*p = ' ';
109 	}
110 	/* Remove trailing whitespace */
111 	if (*--p == ' ')
112 		*p = '\0';
113 }
114 
115 /*
116  * Test specifically for the case where SYSTEM == NONE and AUTH1 contains
117  * anything other than NONE or SYSTEM, which indicates that the admin has
118  * configured the account for purely AUTH1-type authentication.
119  *
120  * Since authenticate() doesn't check AUTH1, and sshd can't sanely support
121  * AUTH1 itself, in such a case authenticate() will allow access without
122  * authentation, which is almost certainly not what the admin intends.
123  *
124  * (The native tools, eg login, will process the AUTH1 list in addition to
125  * the SYSTEM list by using ckuserID(), however ckuserID() and AUTH1 methods
126  * have been deprecated since AIX 4.2.x and would be very difficult for sshd
127  * to support.
128  *
129  * Returns 0 if an unsupportable combination is found, 1 otherwise.
130  */
131 static int
132 aix_valid_authentications(const char *user)
133 {
134 	char *auth1, *sys, *p;
135 	int valid = 1;
136 
137 	if (getuserattr((char *)user, S_AUTHSYSTEM, &sys, SEC_CHAR) != 0) {
138 		logit("Can't retrieve attribute SYSTEM for %s: %.100s",
139 		    user, strerror(errno));
140 		return 0;
141 	}
142 
143 	debug3("AIX SYSTEM attribute %s", sys);
144 	if (strcmp(sys, "NONE") != 0)
145 		return 1;	/* not "NONE", so is OK */
146 
147 	if (getuserattr((char *)user, S_AUTH1, &auth1, SEC_LIST) != 0) {
148 		logit("Can't retrieve attribute auth1 for %s: %.100s",
149 		    user, strerror(errno));
150 		return 0;
151 	}
152 
153 	p = auth1;
154 	/* A SEC_LIST is concatenated strings, ending with two NULs. */
155 	while (p[0] != '\0' && p[1] != '\0') {
156 		debug3("AIX auth1 attribute list member %s", p);
157 		if (strcmp(p, "NONE") != 0 && strcmp(p, "SYSTEM")) {
158 			logit("Account %s has unsupported auth1 value '%s'",
159 			    user, p);
160 			valid = 0;
161 		}
162 		p += strlen(p) + 1;
163 	}
164 
165 	return (valid);
166 }
167 
168 /*
169  * Do authentication via AIX's authenticate routine.  We loop until the
170  * reenter parameter is 0, but normally authenticate is called only once.
171  *
172  * Note: this function returns 1 on success, whereas AIX's authenticate()
173  * returns 0.
174  */
175 int
176 sys_auth_passwd(struct ssh *ssh, const char *password)
177 {
178 	Authctxt *ctxt = ssh->authctxt;
179 	char *authmsg = NULL, *msg = NULL, *name = ctxt->pw->pw_name;
180 	int r, authsuccess = 0, expired, reenter, result;
181 
182 	do {
183 		result = authenticate((char *)name, (char *)password, &reenter,
184 		    &authmsg);
185 		aix_remove_embedded_newlines(authmsg);
186 		debug3("AIX/authenticate result %d, authmsg %.100s", result,
187 		    authmsg);
188 	} while (reenter);
189 
190 	if (!aix_valid_authentications(name))
191 		result = -1;
192 
193 	if (result == 0) {
194 		authsuccess = 1;
195 
196 		/*
197 		 * Record successful login.  We don't have a pty yet, so just
198 		 * label the line as "ssh"
199 		 */
200 		aix_setauthdb(name);
201 
202 		/*
203 		 * Check if the user's password is expired.
204 		 */
205 		expired = passwdexpired(name, &msg);
206 		if (msg && *msg) {
207 			if ((r = sshbuf_put(ctxt->loginmsg,
208 			    msg, strlen(msg))) != 0)
209 				fatal("%s: buffer error: %s",
210 				    __func__, ssh_err(r));
211 			aix_remove_embedded_newlines(msg);
212 		}
213 		debug3("AIX/passwdexpired returned %d msg %.100s", expired, msg);
214 
215 		switch (expired) {
216 		case 0: /* password not expired */
217 			break;
218 		case 1: /* expired, password change required */
219 			ctxt->force_pwchange = 1;
220 			break;
221 		default: /* user can't change(2) or other error (-1) */
222 			logit("Password can't be changed for user %s: %.100s",
223 			    name, msg);
224 			free(msg);
225 			authsuccess = 0;
226 		}
227 
228 		aix_restoreauthdb();
229 	}
230 
231 	free(authmsg);
232 
233 	return authsuccess;
234 }
235 
236 /*
237  * Check if specified account is permitted to log in.
238  * Returns 1 if login is allowed, 0 if not allowed.
239  */
240 int
241 sys_auth_allowed_user(struct passwd *pw, struct sshbuf *loginmsg)
242 {
243 	char *msg = NULL;
244 	int r, result, permitted = 0;
245 	struct stat st;
246 
247 	/*
248 	 * Don't perform checks for root account (PermitRootLogin controls
249 	 * logins via ssh) or if running as non-root user (since
250 	 * loginrestrictions will always fail due to insufficient privilege).
251 	 */
252 	if (pw->pw_uid == 0 || geteuid() != 0) {
253 		debug3("%s: not checking", __func__);
254 		return 1;
255 	}
256 
257 	result = loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &msg);
258 	if (result == 0)
259 		permitted = 1;
260 	/*
261 	 * If restricted because /etc/nologin exists, the login will be denied
262 	 * in session.c after the nologin message is sent, so allow for now
263 	 * and do not append the returned message.
264 	 */
265 	if (result == -1 && errno == EPERM && stat(_PATH_NOLOGIN, &st) == 0)
266 		permitted = 1;
267 	else if (msg != NULL) {
268 		if ((r = sshbuf_put(loginmsg, msg, strlen(msg))) != 0)
269 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
270 	}
271 	if (msg == NULL)
272 		msg = xstrdup("(none)");
273 	aix_remove_embedded_newlines(msg);
274 	debug3("AIX/loginrestrictions returned %d msg %.100s", result, msg);
275 
276 	if (!permitted)
277 		logit("Login restricted for %s: %.100s", pw->pw_name, msg);
278 	free(msg);
279 	return permitted;
280 }
281 
282 int
283 sys_auth_record_login(const char *user, const char *host, const char *ttynm,
284     struct sshbuf *loginmsg)
285 {
286 	char *msg = NULL;
287 	int success = 0;
288 
289 	aix_setauthdb(user);
290 	if (loginsuccess((char *)user, (char *)host, (char *)ttynm, &msg) == 0) {
291 		success = 1;
292 		if (msg != NULL) {
293 			debug("AIX/loginsuccess: msg %s", msg);
294 			if (lastlogin_msg == NULL)
295 				lastlogin_msg = msg;
296 		}
297 	}
298 	aix_restoreauthdb();
299 	return (success);
300 }
301 
302 char *
303 sys_auth_get_lastlogin_msg(const char *user, uid_t uid)
304 {
305 	char *msg = lastlogin_msg;
306 
307 	lastlogin_msg = NULL;
308 	return msg;
309 }
310 
311 #  ifdef CUSTOM_FAILED_LOGIN
312 /*
313  * record_failed_login: generic "login failed" interface function
314  */
315 void
316 record_failed_login(struct ssh *ssh, const char *user, const char *hostname,
317     const char *ttyname)
318 {
319 	if (geteuid() != 0)
320 		return;
321 
322 	aix_setauthdb(user);
323 #   ifdef AIX_LOGINFAILED_4ARG
324 	loginfailed((char *)user, (char *)hostname, (char *)ttyname,
325 	    AUDIT_FAIL_AUTH);
326 #   else
327 	loginfailed((char *)user, (char *)hostname, (char *)ttyname);
328 #   endif
329 	aix_restoreauthdb();
330 }
331 #  endif /* CUSTOM_FAILED_LOGIN */
332 
333 /*
334  * If we have setauthdb, retrieve the password registry for the user's
335  * account then feed it to setauthdb.  This will mean that subsequent AIX auth
336  * functions will only use the specified loadable module.  If we don't have
337  * setauthdb this is a no-op.
338  */
339 void
340 aix_setauthdb(const char *user)
341 {
342 #  ifdef HAVE_SETAUTHDB
343 	char *registry;
344 
345 	if (setuserdb(S_READ) == -1) {
346 		debug3("%s: Could not open userdb to read", __func__);
347 		return;
348 	}
349 
350 	if (getuserattr((char *)user, S_REGISTRY, &registry, SEC_CHAR) == 0) {
351 		if (setauthdb(registry, old_registry) == 0)
352 			debug3("AIX/setauthdb set registry '%s'", registry);
353 		else
354 			debug3("AIX/setauthdb set registry '%s' failed: %s",
355 			    registry, strerror(errno));
356 	} else
357 		debug3("%s: Could not read S_REGISTRY for user: %s", __func__,
358 		    strerror(errno));
359 	enduserdb();
360 #  endif /* HAVE_SETAUTHDB */
361 }
362 
363 /*
364  * Restore the user's registry settings from old_registry.
365  * Note that if the first aix_setauthdb fails, setauthdb("") is still safe
366  * (it restores the system default behaviour).  If we don't have setauthdb,
367  * this is a no-op.
368  */
369 void
370 aix_restoreauthdb(void)
371 {
372 #  ifdef HAVE_SETAUTHDB
373 	if (setauthdb(old_registry, NULL) == 0)
374 		debug3("%s: restoring old registry '%s'", __func__,
375 		    old_registry);
376 	else
377 		debug3("%s: failed to restore old registry %s", __func__,
378 		    old_registry);
379 #  endif /* HAVE_SETAUTHDB */
380 }
381 
382 # endif /* WITH_AIXAUTHENTICATE */
383 
384 # ifdef USE_AIX_KRB_NAME
385 /*
386  * aix_krb5_get_principal_name: returns the user's kerberos client principal name if
387  * configured, otherwise NULL.  Caller must free returned string.
388  */
389 char *
390 aix_krb5_get_principal_name(char *pw_name)
391 {
392 	char *authname = NULL, *authdomain = NULL, *principal = NULL;
393 
394 	setuserdb(S_READ);
395 	if (getuserattr(pw_name, S_AUTHDOMAIN, &authdomain, SEC_CHAR) != 0)
396 		debug("AIX getuserattr S_AUTHDOMAIN: %s", strerror(errno));
397 	if (getuserattr(pw_name, S_AUTHNAME, &authname, SEC_CHAR) != 0)
398 		debug("AIX getuserattr S_AUTHNAME: %s", strerror(errno));
399 
400 	if (authdomain != NULL)
401 		xasprintf(&principal, "%s@%s", authname ? authname : pw_name, authdomain);
402 	else if (authname != NULL)
403 		principal = xstrdup(authname);
404 	enduserdb();
405 	return principal;
406 }
407 # endif /* USE_AIX_KRB_NAME */
408 
409 # if defined(AIX_GETNAMEINFO_HACK) && !defined(BROKEN_ADDRINFO)
410 # undef getnameinfo
411 /*
412  * For some reason, AIX's getnameinfo will refuse to resolve the all-zeros
413  * IPv6 address into its textual representation ("::"), so we wrap it
414  * with a function that will.
415  */
416 int
417 sshaix_getnameinfo(const struct sockaddr *sa, size_t salen, char *host,
418     size_t hostlen, char *serv, size_t servlen, int flags)
419 {
420 	struct sockaddr_in6 *sa6;
421 	u_int32_t *a6;
422 
423 	if (flags & (NI_NUMERICHOST|NI_NUMERICSERV) &&
424 	    sa->sa_family == AF_INET6) {
425 		sa6 = (struct sockaddr_in6 *)sa;
426 		a6 = sa6->sin6_addr.u6_addr.u6_addr32;
427 
428 		if (a6[0] == 0 && a6[1] == 0 && a6[2] == 0 && a6[3] == 0) {
429 			strlcpy(host, "::", hostlen);
430 			snprintf(serv, servlen, "%d", sa6->sin6_port);
431 			return 0;
432 		}
433 	}
434 	return getnameinfo(sa, salen, host, hostlen, serv, servlen, flags);
435 }
436 # endif /* AIX_GETNAMEINFO_HACK */
437 
438 # if defined(USE_GETGRSET)
439 #  include <stdlib.h>
440 int
441 getgrouplist(const char *user, gid_t pgid, gid_t *groups, int *grpcnt)
442 {
443 	char *cp, *grplist, *grp;
444 	gid_t gid;
445 	int ret = 0, ngroups = 0, maxgroups;
446 	long l;
447 
448 	maxgroups = *grpcnt;
449 
450 	if ((cp = grplist = getgrset(user)) == NULL)
451 		return -1;
452 
453 	/* handle zero-length case */
454 	if (maxgroups <= 0) {
455 		*grpcnt = 0;
456 		return -1;
457 	}
458 
459 	/* copy primary group */
460 	groups[ngroups++] = pgid;
461 
462 	/* copy each entry from getgrset into group list */
463 	while ((grp = strsep(&grplist, ",")) != NULL) {
464 		l = strtol(grp, NULL, 10);
465 		if (ngroups >= maxgroups || l == LONG_MIN || l == LONG_MAX) {
466 			ret = -1;
467 			goto out;
468 		}
469 		gid = (gid_t)l;
470 		if (gid == pgid)
471 			continue;	/* we have already added primary gid */
472 		groups[ngroups++] = gid;
473 	}
474 out:
475 	free(cp);
476 	*grpcnt = ngroups;
477 	return ret;
478 }
479 # endif	/* USE_GETGRSET */
480 
481 #endif /* _AIX */
482