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 <stdarg.h>
45 #include <string.h>
46 #include <unistd.h>
47 #include <sys/socket.h>
48 #include "port-aix.h"
49 
50 # ifdef HAVE_SETAUTHDB
51 static char old_registry[REGISTRY_SIZE] = "";
52 # endif
53 
54 /*
55  * AIX has a "usrinfo" area where logname and other stuff is stored -
56  * a few applications actually use this and die if it's not set
57  *
58  * NOTE: TTY= should be set, but since no one uses it and it's hard to
59  * acquire due to privsep code.  We will just drop support.
60  */
61 void
62 aix_usrinfo(struct passwd *pw)
63 {
64 	u_int i;
65 	size_t len;
66 	char *cp;
67 
68 	len = sizeof("LOGNAME= NAME= ") + (2 * strlen(pw->pw_name));
69 	cp = xmalloc(len);
70 
71 	i = snprintf(cp, len, "LOGNAME=%s%cNAME=%s%c", pw->pw_name, '\0',
72 	    pw->pw_name, '\0');
73 	if (usrinfo(SETUINFO, cp, i) == -1)
74 		fatal("Couldn't set usrinfo: %s", strerror(errno));
75 	debug3("AIX/UsrInfo: set len %d", i);
76 
77 	xfree(cp);
78 }
79 
80 # ifdef WITH_AIXAUTHENTICATE
81 /*
82  * Remove embedded newlines in string (if any).
83  * Used before logging messages returned by AIX authentication functions
84  * so the message is logged on one line.
85  */
86 void
87 aix_remove_embedded_newlines(char *p)
88 {
89 	if (p == NULL)
90 		return;
91 
92 	for (; *p; p++) {
93 		if (*p == '\n')
94 			*p = ' ';
95 	}
96 	/* Remove trailing whitespace */
97 	if (*--p == ' ')
98 		*p = '\0';
99 }
100 
101 /*
102  * Test specifically for the case where SYSTEM == NONE and AUTH1 contains
103  * anything other than NONE or SYSTEM, which indicates that the admin has
104  * configured the account for purely AUTH1-type authentication.
105  *
106  * Since authenticate() doesn't check AUTH1, and sshd can't sanely support
107  * AUTH1 itself, in such a case authenticate() will allow access without
108  * authentation, which is almost certainly not what the admin intends.
109  *
110  * (The native tools, eg login, will process the AUTH1 list in addition to
111  * the SYSTEM list by using ckuserID(), however ckuserID() and AUTH1 methods
112  * have been deprecated since AIX 4.2.x and would be very difficult for sshd
113  * to support.
114  *
115  * Returns 0 if an unsupportable combination is found, 1 otherwise.
116  */
117 static int
118 aix_valid_authentications(const char *user)
119 {
120 	char *auth1, *sys, *p;
121 	int valid = 1;
122 
123 	if (getuserattr((char *)user, S_AUTHSYSTEM, &sys, SEC_CHAR) != 0) {
124 		logit("Can't retrieve attribute SYSTEM for %s: %.100s",
125 		    user, strerror(errno));
126 		return 0;
127 	}
128 
129 	debug3("AIX SYSTEM attribute %s", sys);
130 	if (strcmp(sys, "NONE") != 0)
131 		return 1;	/* not "NONE", so is OK */
132 
133 	if (getuserattr((char *)user, S_AUTH1, &auth1, SEC_LIST) != 0) {
134 		logit("Can't retrieve attribute auth1 for %s: %.100s",
135 		    user, strerror(errno));
136 		return 0;
137 	}
138 
139 	p = auth1;
140 	/* A SEC_LIST is concatenated strings, ending with two NULs. */
141 	while (p[0] != '\0' && p[1] != '\0') {
142 		debug3("AIX auth1 attribute list member %s", p);
143 		if (strcmp(p, "NONE") != 0 && strcmp(p, "SYSTEM")) {
144 			logit("Account %s has unsupported auth1 value '%s'",
145 			    user, p);
146 			valid = 0;
147 		}
148 		p += strlen(p) + 1;
149 	}
150 
151 	return (valid);
152 }
153 
154 /*
155  * Do authentication via AIX's authenticate routine.  We loop until the
156  * reenter parameter is 0, but normally authenticate is called only once.
157  *
158  * Note: this function returns 1 on success, whereas AIX's authenticate()
159  * returns 0.
160  */
161 int
162 sys_auth_passwd(Authctxt *ctxt, const char *password)
163 {
164 	char *authmsg = NULL, *msg = NULL, *name = ctxt->pw->pw_name;
165 	int authsuccess = 0, expired, reenter, result;
166 
167 	do {
168 		result = authenticate((char *)name, (char *)password, &reenter,
169 		    &authmsg);
170 		aix_remove_embedded_newlines(authmsg);
171 		debug3("AIX/authenticate result %d, authmsg %.100s", result,
172 		    authmsg);
173 	} while (reenter);
174 
175 	if (!aix_valid_authentications(name))
176 		result = -1;
177 
178 	if (result == 0) {
179 		authsuccess = 1;
180 
181 		/*
182 		 * Record successful login.  We don't have a pty yet, so just
183 		 * label the line as "ssh"
184 		 */
185 		aix_setauthdb(name);
186 
187 		/*
188 		 * Check if the user's password is expired.
189 		 */
190 		expired = passwdexpired(name, &msg);
191 		if (msg && *msg) {
192 			buffer_append(ctxt->loginmsg, msg, strlen(msg));
193 			aix_remove_embedded_newlines(msg);
194 		}
195 		debug3("AIX/passwdexpired returned %d msg %.100s", expired, msg);
196 
197 		switch (expired) {
198 		case 0: /* password not expired */
199 			break;
200 		case 1: /* expired, password change required */
201 			ctxt->force_pwchange = 1;
202 			break;
203 		default: /* user can't change(2) or other error (-1) */
204 			logit("Password can't be changed for user %s: %.100s",
205 			    name, msg);
206 			if (msg)
207 				xfree(msg);
208 			authsuccess = 0;
209 		}
210 
211 		aix_restoreauthdb();
212 	}
213 
214 	if (authmsg != NULL)
215 		xfree(authmsg);
216 
217 	return authsuccess;
218 }
219 
220 /*
221  * Check if specified account is permitted to log in.
222  * Returns 1 if login is allowed, 0 if not allowed.
223  */
224 int
225 sys_auth_allowed_user(struct passwd *pw, Buffer *loginmsg)
226 {
227 	char *msg = NULL;
228 	int result, permitted = 0;
229 	struct stat st;
230 
231 	/*
232 	 * Don't perform checks for root account (PermitRootLogin controls
233 	 * logins via * ssh) or if running as non-root user (since
234 	 * loginrestrictions will always fail due to insufficient privilege).
235 	 */
236 	if (pw->pw_uid == 0 || geteuid() != 0) {
237 		debug3("%s: not checking", __func__);
238 		return 1;
239 	}
240 
241 	result = loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &msg);
242 	if (result == 0)
243 		permitted = 1;
244 	/*
245 	 * If restricted because /etc/nologin exists, the login will be denied
246 	 * in session.c after the nologin message is sent, so allow for now
247 	 * and do not append the returned message.
248 	 */
249 	if (result == -1 && errno == EPERM && stat(_PATH_NOLOGIN, &st) == 0)
250 		permitted = 1;
251 	else if (msg != NULL)
252 		buffer_append(loginmsg, msg, strlen(msg));
253 	if (msg == NULL)
254 		msg = xstrdup("(none)");
255 	aix_remove_embedded_newlines(msg);
256 	debug3("AIX/loginrestrictions returned %d msg %.100s", result, msg);
257 
258 	if (!permitted)
259 		logit("Login restricted for %s: %.100s", pw->pw_name, msg);
260 	xfree(msg);
261 	return permitted;
262 }
263 
264 int
265 sys_auth_record_login(const char *user, const char *host, const char *ttynm,
266     Buffer *loginmsg)
267 {
268 	char *msg = NULL;
269 	static int msg_done = 0;
270 	int success = 0;
271 
272 	aix_setauthdb(user);
273 	if (loginsuccess((char *)user, (char *)host, (char *)ttynm, &msg) == 0) {
274 		success = 1;
275 		if (msg != NULL && loginmsg != NULL && !msg_done) {
276 			debug("AIX/loginsuccess: msg %s", msg);
277 			buffer_append(loginmsg, msg, strlen(msg));
278 			xfree(msg);
279 			msg_done = 1;
280 		}
281 	}
282 	aix_restoreauthdb();
283 	return (success);
284 }
285 
286 #  ifdef CUSTOM_FAILED_LOGIN
287 /*
288  * record_failed_login: generic "login failed" interface function
289  */
290 void
291 record_failed_login(const char *user, const char *hostname, const char *ttyname)
292 {
293 	if (geteuid() != 0)
294 		return;
295 
296 	aix_setauthdb(user);
297 #   ifdef AIX_LOGINFAILED_4ARG
298 	loginfailed((char *)user, (char *)hostname, (char *)ttyname,
299 	    AUDIT_FAIL_AUTH);
300 #   else
301 	loginfailed((char *)user, (char *)hostname, (char *)ttyname);
302 #   endif
303 	aix_restoreauthdb();
304 }
305 #  endif /* CUSTOM_FAILED_LOGIN */
306 
307 /*
308  * If we have setauthdb, retrieve the password registry for the user's
309  * account then feed it to setauthdb.  This will mean that subsequent AIX auth
310  * functions will only use the specified loadable module.  If we don't have
311  * setauthdb this is a no-op.
312  */
313 void
314 aix_setauthdb(const char *user)
315 {
316 #  ifdef HAVE_SETAUTHDB
317 	char *registry;
318 
319 	if (setuserdb(S_READ) == -1) {
320 		debug3("%s: Could not open userdb to read", __func__);
321 		return;
322 	}
323 
324 	if (getuserattr((char *)user, S_REGISTRY, &registry, SEC_CHAR) == 0) {
325 		if (setauthdb(registry, old_registry) == 0)
326 			debug3("AIX/setauthdb set registry '%s'", registry);
327 		else
328 			debug3("AIX/setauthdb set registry '%s' failed: %s",
329 			    registry, strerror(errno));
330 	} else
331 		debug3("%s: Could not read S_REGISTRY for user: %s", __func__,
332 		    strerror(errno));
333 	enduserdb();
334 #  endif /* HAVE_SETAUTHDB */
335 }
336 
337 /*
338  * Restore the user's registry settings from old_registry.
339  * Note that if the first aix_setauthdb fails, setauthdb("") is still safe
340  * (it restores the system default behaviour).  If we don't have setauthdb,
341  * this is a no-op.
342  */
343 void
344 aix_restoreauthdb(void)
345 {
346 #  ifdef HAVE_SETAUTHDB
347 	if (setauthdb(old_registry, NULL) == 0)
348 		debug3("%s: restoring old registry '%s'", __func__,
349 		    old_registry);
350 	else
351 		debug3("%s: failed to restore old registry %s", __func__,
352 		    old_registry);
353 #  endif /* HAVE_SETAUTHDB */
354 }
355 
356 # endif /* WITH_AIXAUTHENTICATE */
357 
358 # if defined(AIX_GETNAMEINFO_HACK) && !defined(BROKEN_ADDRINFO)
359 # undef getnameinfo
360 /*
361  * For some reason, AIX's getnameinfo will refuse to resolve the all-zeros
362  * IPv6 address into its textual representation ("::"), so we wrap it
363  * with a function that will.
364  */
365 int
366 sshaix_getnameinfo(const struct sockaddr *sa, size_t salen, char *host,
367     size_t hostlen, char *serv, size_t servlen, int flags)
368 {
369 	struct sockaddr_in6 *sa6;
370 	u_int32_t *a6;
371 
372 	if (flags & (NI_NUMERICHOST|NI_NUMERICSERV) &&
373 	    sa->sa_family == AF_INET6) {
374 		sa6 = (struct sockaddr_in6 *)sa;
375 		a6 = sa6->sin6_addr.u6_addr.u6_addr32;
376 
377 		if (a6[0] == 0 && a6[1] == 0 && a6[2] == 0 && a6[3] == 0) {
378 			strlcpy(host, "::", hostlen);
379 			snprintf(serv, servlen, "%d", sa6->sin6_port);
380 			return 0;
381 		}
382 	}
383 	return getnameinfo(sa, salen, host, hostlen, serv, servlen, flags);
384 }
385 # endif /* AIX_GETNAMEINFO_HACK */
386 
387 #endif /* _AIX */
388