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