1 /*
2  *
3  * Copyright (c) 2001 Gert Doering.  All rights reserved.
4  * Copyright (c) 2003,2004,2005 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 "buffer.h"
31 #include "key.h"
32 #include "hostfile.h"
33 #include "auth.h"
34 #include "ssh.h"
35 #include "log.h"
36 
37 #ifdef _AIX
38 
39 #include <errno.h>
40 #if defined(HAVE_NETDB_H)
41 # include <netdb.h>
42 #endif
43 #include <uinfo.h>
44 #include <string.h>
45 #include <unistd.h>
46 #include <sys/socket.h>
47 #include "port-aix.h"
48 
49 # ifdef HAVE_SETAUTHDB
50 static char old_registry[REGISTRY_SIZE] = "";
51 # endif
52 
53 /*
54  * AIX has a "usrinfo" area where logname and other stuff is stored -
55  * a few applications actually use this and die if it's not set
56  *
57  * NOTE: TTY= should be set, but since no one uses it and it's hard to
58  * acquire due to privsep code.  We will just drop support.
59  */
60 void
61 aix_usrinfo(struct passwd *pw)
62 {
63 	u_int i;
64 	size_t len;
65 	char *cp;
66 
67 	len = sizeof("LOGNAME= NAME= ") + (2 * strlen(pw->pw_name));
68 	cp = xmalloc(len);
69 
70 	i = snprintf(cp, len, "LOGNAME=%s%cNAME=%s%c", pw->pw_name, '\0',
71 	    pw->pw_name, '\0');
72 	if (usrinfo(SETUINFO, cp, i) == -1)
73 		fatal("Couldn't set usrinfo: %s", strerror(errno));
74 	debug3("AIX/UsrInfo: set len %d", i);
75 
76 	xfree(cp);
77 }
78 
79 # ifdef WITH_AIXAUTHENTICATE
80 /*
81  * Remove embedded newlines in string (if any).
82  * Used before logging messages returned by AIX authentication functions
83  * so the message is logged on one line.
84  */
85 void
86 aix_remove_embedded_newlines(char *p)
87 {
88 	if (p == NULL)
89 		return;
90 
91 	for (; *p; p++) {
92 		if (*p == '\n')
93 			*p = ' ';
94 	}
95 	/* Remove trailing whitespace */
96 	if (*--p == ' ')
97 		*p = '\0';
98 }
99 
100 /*
101  * Test specifically for the case where SYSTEM == NONE and AUTH1 contains
102  * anything other than NONE or SYSTEM, which indicates that the admin has
103  * configured the account for purely AUTH1-type authentication.
104  *
105  * Since authenticate() doesn't check AUTH1, and sshd can't sanely support
106  * AUTH1 itself, in such a case authenticate() will allow access without
107  * authentation, which is almost certainly not what the admin intends.
108  *
109  * (The native tools, eg login, will process the AUTH1 list in addition to
110  * the SYSTEM list by using ckuserID(), however ckuserID() and AUTH1 methods
111  * have been deprecated since AIX 4.2.x and would be very difficult for sshd
112  * to support.
113  *
114  * Returns 0 if an unsupportable combination is found, 1 otherwise.
115  */
116 static int
117 aix_valid_authentications(const char *user)
118 {
119 	char *auth1, *sys, *p;
120 	int valid = 1;
121 
122 	if (getuserattr((char *)user, S_AUTHSYSTEM, &sys, SEC_CHAR) != 0) {
123 		logit("Can't retrieve attribute SYSTEM for %s: %.100s",
124 		    user, strerror(errno));
125 		return 0;
126 	}
127 
128 	debug3("AIX SYSTEM attribute %s", sys);
129 	if (strcmp(sys, "NONE") != 0)
130 		return 1;	/* not "NONE", so is OK */
131 
132 	if (getuserattr((char *)user, S_AUTH1, &auth1, SEC_LIST) != 0) {
133 		logit("Can't retrieve attribute auth1 for %s: %.100s",
134 		    user, strerror(errno));
135 		return 0;
136 	}
137 
138 	p = auth1;
139 	/* A SEC_LIST is concatenated strings, ending with two NULs. */
140 	while (p[0] != '\0' && p[1] != '\0') {
141 		debug3("AIX auth1 attribute list member %s", p);
142 		if (strcmp(p, "NONE") != 0 && strcmp(p, "SYSTEM")) {
143 			logit("Account %s has unsupported auth1 value '%s'",
144 			    user, p);
145 			valid = 0;
146 		}
147 		p += strlen(p) + 1;
148 	}
149 
150 	return (valid);
151 }
152 
153 /*
154  * Do authentication via AIX's authenticate routine.  We loop until the
155  * reenter parameter is 0, but normally authenticate is called only once.
156  *
157  * Note: this function returns 1 on success, whereas AIX's authenticate()
158  * returns 0.
159  */
160 int
161 sys_auth_passwd(Authctxt *ctxt, const char *password)
162 {
163 	char *authmsg = NULL, *msg = NULL, *name = ctxt->pw->pw_name;
164 	int authsuccess = 0, expired, reenter, result;
165 
166 	do {
167 		result = authenticate((char *)name, (char *)password, &reenter,
168 		    &authmsg);
169 		aix_remove_embedded_newlines(authmsg);
170 		debug3("AIX/authenticate result %d, authmsg %.100s", result,
171 		    authmsg);
172 	} while (reenter);
173 
174 	if (!aix_valid_authentications(name))
175 		result = -1;
176 
177 	if (result == 0) {
178 		authsuccess = 1;
179 
180 		/*
181 		 * Record successful login.  We don't have a pty yet, so just
182 		 * label the line as "ssh"
183 		 */
184 		aix_setauthdb(name);
185 
186 		/*
187 		 * Check if the user's password is expired.
188 		 */
189 		expired = passwdexpired(name, &msg);
190 		if (msg && *msg) {
191 			buffer_append(ctxt->loginmsg, msg, strlen(msg));
192 			aix_remove_embedded_newlines(msg);
193 		}
194 		debug3("AIX/passwdexpired returned %d msg %.100s", expired, msg);
195 
196 		switch (expired) {
197 		case 0: /* password not expired */
198 			break;
199 		case 1: /* expired, password change required */
200 			ctxt->force_pwchange = 1;
201 			break;
202 		default: /* user can't change(2) or other error (-1) */
203 			logit("Password can't be changed for user %s: %.100s",
204 			    name, msg);
205 			if (msg)
206 				xfree(msg);
207 			authsuccess = 0;
208 		}
209 
210 		aix_restoreauthdb();
211 	}
212 
213 	if (authmsg != NULL)
214 		xfree(authmsg);
215 
216 	return authsuccess;
217 }
218 
219 /*
220  * Check if specified account is permitted to log in.
221  * Returns 1 if login is allowed, 0 if not allowed.
222  */
223 int
224 sys_auth_allowed_user(struct passwd *pw, Buffer *loginmsg)
225 {
226 	char *msg = NULL;
227 	int result, permitted = 0;
228 	struct stat st;
229 
230 	/*
231 	 * Don't perform checks for root account (PermitRootLogin controls
232 	 * logins via * ssh) or if running as non-root user (since
233 	 * loginrestrictions will always fail due to insufficient privilege).
234 	 */
235 	if (pw->pw_uid == 0 || geteuid() != 0) {
236 		debug3("%s: not checking", __func__);
237 		return 1;
238 	}
239 
240 	result = loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &msg);
241 	if (result == 0)
242 		permitted = 1;
243 	/*
244 	 * If restricted because /etc/nologin exists, the login will be denied
245 	 * in session.c after the nologin message is sent, so allow for now
246 	 * and do not append the returned message.
247 	 */
248 	if (result == -1 && errno == EPERM && stat(_PATH_NOLOGIN, &st) == 0)
249 		permitted = 1;
250 	else if (msg != NULL)
251 		buffer_append(loginmsg, msg, strlen(msg));
252 	if (msg == NULL)
253 		msg = xstrdup("(none)");
254 	aix_remove_embedded_newlines(msg);
255 	debug3("AIX/loginrestrictions returned %d msg %.100s", result, msg);
256 
257 	if (!permitted)
258 		logit("Login restricted for %s: %.100s", pw->pw_name, msg);
259 	xfree(msg);
260 	return permitted;
261 }
262 
263 int
264 sys_auth_record_login(const char *user, const char *host, const char *ttynm,
265     Buffer *loginmsg)
266 {
267 	char *msg = NULL;
268 	int success = 0;
269 
270 	aix_setauthdb(user);
271 	if (loginsuccess((char *)user, (char *)host, (char *)ttynm, &msg) == 0) {
272 		success = 1;
273 		if (msg != NULL) {
274 			debug("AIX/loginsuccess: msg %s", msg);
275 			buffer_append(loginmsg, msg, strlen(msg));
276 			xfree(msg);
277 		}
278 	}
279 	aix_restoreauthdb();
280 	return (success);
281 }
282 
283 #  ifdef CUSTOM_FAILED_LOGIN
284 /*
285  * record_failed_login: generic "login failed" interface function
286  */
287 void
288 record_failed_login(const char *user, const char *hostname, const char *ttyname)
289 {
290 	if (geteuid() != 0)
291 		return;
292 
293 	aix_setauthdb(user);
294 #   ifdef AIX_LOGINFAILED_4ARG
295 	loginfailed((char *)user, (char *)hostname, (char *)ttyname,
296 	    AUDIT_FAIL_AUTH);
297 #   else
298 	loginfailed((char *)user, (char *)hostname, (char *)ttyname);
299 #   endif
300 	aix_restoreauthdb();
301 }
302 #  endif /* CUSTOM_FAILED_LOGIN */
303 
304 /*
305  * If we have setauthdb, retrieve the password registry for the user's
306  * account then feed it to setauthdb.  This will mean that subsequent AIX auth
307  * functions will only use the specified loadable module.  If we don't have
308  * setauthdb this is a no-op.
309  */
310 void
311 aix_setauthdb(const char *user)
312 {
313 #  ifdef HAVE_SETAUTHDB
314 	char *registry;
315 
316 	if (setuserdb(S_READ) == -1) {
317 		debug3("%s: Could not open userdb to read", __func__);
318 		return;
319 	}
320 
321 	if (getuserattr((char *)user, S_REGISTRY, &registry, SEC_CHAR) == 0) {
322 		if (setauthdb(registry, old_registry) == 0)
323 			debug3("AIX/setauthdb set registry '%s'", registry);
324 		else
325 			debug3("AIX/setauthdb set registry '%s' failed: %s",
326 			    registry, strerror(errno));
327 	} else
328 		debug3("%s: Could not read S_REGISTRY for user: %s", __func__,
329 		    strerror(errno));
330 	enduserdb();
331 #  endif /* HAVE_SETAUTHDB */
332 }
333 
334 /*
335  * Restore the user's registry settings from old_registry.
336  * Note that if the first aix_setauthdb fails, setauthdb("") is still safe
337  * (it restores the system default behaviour).  If we don't have setauthdb,
338  * this is a no-op.
339  */
340 void
341 aix_restoreauthdb(void)
342 {
343 #  ifdef HAVE_SETAUTHDB
344 	if (setauthdb(old_registry, NULL) == 0)
345 		debug3("%s: restoring old registry '%s'", __func__,
346 		    old_registry);
347 	else
348 		debug3("%s: failed to restore old registry %s", __func__,
349 		    old_registry);
350 #  endif /* HAVE_SETAUTHDB */
351 }
352 
353 # endif /* WITH_AIXAUTHENTICATE */
354 
355 # if defined(AIX_GETNAMEINFO_HACK) && !defined(BROKEN_ADDRINFO)
356 # undef getnameinfo
357 /*
358  * For some reason, AIX's getnameinfo will refuse to resolve the all-zeros
359  * IPv6 address into its textual representation ("::"), so we wrap it
360  * with a function that will.
361  */
362 int
363 sshaix_getnameinfo(const struct sockaddr *sa, size_t salen, char *host,
364     size_t hostlen, char *serv, size_t servlen, int flags)
365 {
366 	struct sockaddr_in6 *sa6;
367 	u_int32_t *a6;
368 
369 	if (flags & (NI_NUMERICHOST|NI_NUMERICSERV) &&
370 	    sa->sa_family == AF_INET6) {
371 		sa6 = (struct sockaddr_in6 *)sa;
372 		a6 = sa6->sin6_addr.u6_addr.u6_addr32;
373 
374 		if (a6[0] == 0 && a6[1] == 0 && a6[2] == 0 && a6[3] == 0) {
375 			strlcpy(host, "::", hostlen);
376 			snprintf(serv, servlen, "%d", sa6->sin6_port);
377 			return 0;
378 		}
379 	}
380 	return getnameinfo(sa, salen, host, hostlen, serv, servlen, flags);
381 }
382 # endif /* AIX_GETNAMEINFO_HACK */
383 
384 #endif /* _AIX */
385