2 * Copyright (c) 1990,1993 Regents of The University of Michigan.
3 * Copyright (c) 1999 Adrian Sun (asun@u.washington.edu)
4 * Copyright (c) 2003 The Reed Institute
5 * Copyright (c) 2004 Bjoern Fernhomberg
6 * All Rights Reserved. See COPYRIGHT.
11 #endif /* HAVE_CONFIG_H */
17 #endif /* HAVE_UNISTD_H */
20 #include <arpa/inet.h>
22 #include <atalk/logger.h>
23 #include <atalk/afp.h>
24 #include <atalk/uam.h>
25 #include <atalk/util.h>
26 #include <atalk/compat.h>
28 /* Kerberos includes */
34 #if HAVE_GSSAPI_GSSAPI_H
35 #include <gssapi/gssapi.h>
38 #if HAVE_GSSAPI_GSSAPI_GENERIC_H
39 #include <gssapi/gssapi_generic.h>
42 #if HAVE_GSSAPI_GSSAPI_KRB5_H
43 #include <gssapi/gssapi_krb5.h>
50 /* We work around something I don't entirely understand... */
51 /* BF: This is a Heimdal/MIT compatibility fix */
52 #ifndef HAVE_GSS_C_NT_HOSTBASED_SERVICE
53 #define GSS_C_NT_HOSTBASED_SERVICE gss_nt_service_name
60 #define MIN(a, b) ((a > b) ? b : a)
62 static void log_status( char *s, OM_uint32 major_status,
63 OM_uint32 minor_status )
65 gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
66 OM_uint32 min_status, maj_status;
67 OM_uint32 maj_ctx = 0, min_ctx = 0;
70 maj_status = gss_display_status( &min_status, major_status,
71 GSS_C_GSS_CODE, GSS_C_NULL_OID,
73 LOG(log_info, logtype_uams, "uams_gss.c :do_gss_auth: %s %.*s (error %s)", s,
74 (int)msg.length, msg.value, strerror(errno));
75 gss_release_buffer(&min_status, &msg);
81 maj_status = gss_display_status( &min_status, minor_status,
82 GSS_C_MECH_CODE, GSS_C_NULL_OID, // gss_mech_krb5,
84 LOG(log_info, logtype_uams, "uams_gss.c :do_gss_auth: %s %.*s (error %s)", s,
85 (int)msg.length, msg.value, strerror(errno));
86 gss_release_buffer(&min_status, &msg);
94 static void log_ctx_flags( OM_uint32 flags )
97 if (flags & GSS_C_DELEG_FLAG)
98 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_DELEG_FLAG" );
99 if (flags & GSS_C_MUTUAL_FLAG)
100 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_MUTUAL_FLAG" );
101 if (flags & GSS_C_REPLAY_FLAG)
102 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_REPLAY_FLAG" );
103 if (flags & GSS_C_SEQUENCE_FLAG)
104 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_SEQUENCE_FLAG" );
105 if (flags & GSS_C_CONF_FLAG)
106 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_CONF_FLAG" );
107 if (flags & GSS_C_INTEG_FLAG)
108 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_INTEG_FLAG" );
112 static void log_principal(gss_name_t server_name)
115 if (server_name == GSS_C_NO_NAME)
117 /* FIXME: must call gss_canonicalize_name before gss_export_name */
118 OM_uint32 major_status = 0, minor_status = 0;
119 gss_buffer_desc exported_name;
121 /* Only for debugging purposes, check the gssapi internal representation */
122 major_status = gss_export_name(&minor_status, server_name, &exported_name);
123 LOG(log_debug, logtype_uams, "log_principal: exported server name is %s", (char*) exported_name.value);
124 gss_release_buffer( &minor_status, &exported_name );
128 /* get the principal from afpd and import it into server_name */
129 static int get_afpd_principal(void *obj, gss_name_t *server_name)
131 OM_uint32 major_status = 0, minor_status = 0;
132 char *fqdn, *service, *principal, *p;
133 size_t fqdnlen=0, servicelen=0;
134 size_t principal_length;
135 gss_buffer_desc s_princ_buffer;
137 /* get information from afpd */
138 if (uam_afpserver_option(obj, UAM_OPTION_FQDN, (void*) &fqdn, &fqdnlen) < 0)
140 LOG(log_debug, logtype_uams, "get_afpd_principal: fqdn: %s", fqdn);
142 if (uam_afpserver_option(obj, UAM_OPTION_KRB5SERVICE, (void *)&service, &servicelen) < 0)
144 LOG(log_debug, logtype_uams, "get_afpd_principal: service: %s", service);
146 /* if we don't have all the info, log that and return GSS_C_NO_NAME */
147 if (!service || !servicelen || !fqdn || !fqdnlen) {
148 LOG(log_note, logtype_uams,
149 "get_afpd_principal: could not retrieve information from afpd, using default service principal(s)");
151 *server_name = GSS_C_NO_NAME;
155 /* allocate memory to hold the temporary principal string */
156 principal_length = servicelen + 1 + fqdnlen + 1;
157 if ( NULL == (principal = (char*) malloc( principal_length)) ) {
158 LOG(log_error, logtype_uams,
159 "get_afpd_principal: out of memory allocating %u bytes",
165 * Build the principal string.
166 * Format: 'service@fqdn'
168 strlcpy( principal, service, principal_length);
169 strlcat( principal, "@", principal_length);
172 * The fqdn we get from afpd may contain a port.
173 * We need to strip the port from fqdn for principal.
175 if ((p = strchr(fqdn, ':')))
178 strlcat( principal, fqdn, principal_length);
182 * Import our principal into the gssapi internal representation
183 * stored in server_name.
185 s_princ_buffer.value = principal;
186 s_princ_buffer.length = strlen( principal ) + 1;
188 LOG(log_debug, logtype_uams, "get_afpd_principal: importing principal `%s'", principal);
189 major_status = gss_import_name( &minor_status,
191 GSS_C_NT_HOSTBASED_SERVICE,
195 * Get rid of malloc'ed memmory.
196 * Don't release the s_princ_buffer, we free principal instead.
200 if (major_status != GSS_S_COMPLETE) {
201 /* Importing our service principal failed, bail out. */
202 log_status( "import_principal", major_status, minor_status );
209 /* get the username */
210 static int get_client_username(char *username, int ulen, gss_name_t *client_name)
212 OM_uint32 major_status = 0, minor_status = 0;
213 gss_buffer_desc client_name_buffer;
218 * To extract the unix username, use gss_display_name on client_name.
219 * We do rely on gss_display_name returning a zero terminated string.
220 * The username returned contains the realm and possibly an instance.
221 * We only want the username for afpd, so we have to strip those from
222 * the username before copying it to afpd's buffer.
225 major_status = gss_display_name( &minor_status, *client_name,
226 &client_name_buffer, (gss_OID *)NULL );
227 if (major_status != GSS_S_COMPLETE) {
228 log_status( "display_name", major_status, minor_status );
232 LOG(log_debug, logtype_uams, "get_client_username: user is `%s'", client_name_buffer.value);
235 p = strchr( client_name_buffer.value, '@' );
238 /* FIXME: chop off instance? */
239 p = strchr( client_name_buffer.value, '/' );
243 /* check if this username fits into afpd's username buffer */
244 namelen = strlen(client_name_buffer.value);
245 if ( namelen >= ulen ) {
246 /* The username is too long for afpd's buffer, bail out */
247 LOG(log_error, logtype_uams,
248 "get_client_username: username `%s' too long", client_name_buffer.value);
252 /* copy stripped username to afpd's buffer */
253 strlcpy(username, client_name_buffer.value, ulen);
256 /* we're done with client_name_buffer, release it */
257 gss_release_buffer(&minor_status, &client_name_buffer );
262 /* wrap afpd's sessionkey */
263 static int wrap_sessionkey(gss_ctx_id_t context, struct session_info *sinfo)
265 OM_uint32 status = 0;
267 gss_buffer_desc sesskey_buff, wrap_buff;
270 * gss_wrap afpd's session_key.
271 * This is needed fo OS X 10.3 clients. They request this information
272 * with type 8 (kGetKerberosSessionKey) on FPGetSession.
273 * See AFP 3.1 specs, page 77.
276 sesskey_buff.value = sinfo->sessionkey;
277 sesskey_buff.length = sinfo->sessionkey_len;
279 /* gss_wrap the session key with the default machanism.
280 Require both confidentiality and integrity services */
281 gss_wrap (&status, context, 1, GSS_C_QOP_DEFAULT, &sesskey_buff, NULL, &wrap_buff);
283 if ( status != GSS_S_COMPLETE) {
284 LOG(log_error, logtype_uams, "wrap_sessionkey: failed to gss_wrap sessionkey");
285 log_status( "GSS wrap", 0, status );
289 /* store the wrapped session key in afpd's session_info struct */
290 if ( NULL == (sinfo->cryptedkey = malloc ( wrap_buff.length )) ) {
291 LOG(log_error, logtype_uams,
292 "wrap_sessionkey: out of memory tyring to allocate %u bytes",
296 /* cryptedkey is binary data */
297 memcpy (sinfo->cryptedkey, wrap_buff.value, wrap_buff.length);
298 sinfo->cryptedkey_len = wrap_buff.length;
301 /* we're done with buffer, release */
302 gss_release_buffer( &status, &wrap_buff );
308 static int acquire_credentials (gss_name_t *server_name, gss_cred_id_t *server_creds)
310 OM_uint32 major_status = 0, minor_status = 0;
313 if ((envp = getenv("KRB5_KTNAME")))
314 LOG(log_debug, logtype_uams,
315 "acquire credentials: acquiring credentials (uid = %d, keytab = %s)",
316 (int)geteuid(), envp);
318 LOG(log_debug, logtype_uams,
319 "acquire credentials: acquiring credentials (uid = %d) - $KRB5_KTNAME not found in env",
323 * Acquire credentials usable for accepting context negotiations.
324 * Credentials are for server_name, have an indefinite lifetime,
325 * have no specific mechanisms, are to be used for accepting context
326 * negotiations and are to be placed in server_creds.
327 * We don't care about the mechanisms or about the time for which they are valid.
329 major_status = gss_acquire_cred( &minor_status, *server_name,
330 GSS_C_INDEFINITE, GSS_C_NO_OID_SET, GSS_C_ACCEPT,
331 server_creds, NULL, NULL );
333 if (major_status != GSS_S_COMPLETE) {
334 log_status( "acquire_cred", major_status, minor_status );
342 static int accept_sec_context (gss_ctx_id_t *context, gss_cred_id_t server_creds,
343 gss_buffer_desc *ticket_buffer, gss_name_t *client_name,
344 gss_buffer_desc *authenticator_buff)
346 OM_uint32 major_status = 0, minor_status = 0, ret_flags;
348 /* Initialize autheticator buffer. */
349 authenticator_buff->length = 0;
350 authenticator_buff->value = NULL;
352 LOG(log_debug, logtype_uams, "accept_context: accepting context (ticketlen: %u)",
353 ticket_buffer->length);
356 * Try to accept the secondary context using the tocken in ticket_buffer.
357 * We don't care about the mechanisms used, nor for the time.
358 * We don't act as a proxy either.
360 major_status = gss_accept_sec_context( &minor_status, context,
361 server_creds, ticket_buffer, GSS_C_NO_CHANNEL_BINDINGS,
362 client_name, NULL, authenticator_buff,
363 &ret_flags, NULL, NULL );
365 if (major_status != GSS_S_COMPLETE) {
366 log_status( "accept_sec_context", major_status, minor_status );
369 log_ctx_flags( ret_flags );
374 /* return 0 on success */
375 static int do_gss_auth(void *obj, char *ibuf, int ticket_len,
376 char *rbuf, int *rbuflen, char *username, int ulen,
377 struct session_info *sinfo )
379 OM_uint32 status = 0;
380 gss_name_t server_name, client_name;
381 gss_cred_id_t server_creds;
382 gss_ctx_id_t context_handle = GSS_C_NO_CONTEXT;
383 gss_buffer_desc ticket_buffer, authenticator_buff;
386 /* import our principal name from afpd */
387 if (get_afpd_principal(obj, &server_name) != 0) {
390 log_principal(server_name);
392 /* Now we have to acquire our credentials */
393 if ((ret = acquire_credentials (&server_name, &server_creds)))
397 * Try to accept the secondary context, using the ticket/token the
398 * client sent us. Ticket is stored at current ibuf position.
399 * Don't try to release ticket_buffer later, it points into ibuf!
401 ticket_buffer.length = ticket_len;
402 ticket_buffer.value = ibuf;
404 ret = accept_sec_context (&context_handle, server_creds, &ticket_buffer,
405 &client_name, &authenticator_buff);
408 /* We succesfully acquired the secondary context, now get the
409 username for afpd and gss_wrap the sessionkey */
410 if ( 0 == (ret = get_client_username(username, ulen, &client_name)) ) {
411 ret = wrap_sessionkey(context_handle, sinfo);
415 /* FIXME: Is copying the authenticator really necessary?
416 Where is this documented? */
417 uint16_t auth_len = htons( authenticator_buff.length );
419 /* copy the authenticator length into the reply buffer */
420 memcpy( rbuf, &auth_len, sizeof(auth_len) );
421 *rbuflen += sizeof(auth_len);
422 rbuf += sizeof(auth_len);
424 /* copy the authenticator value into the reply buffer */
425 memcpy( rbuf, authenticator_buff.value, authenticator_buff.length );
426 *rbuflen += authenticator_buff.length;
429 /* Clean up after ourselves */
430 gss_release_name( &status, &client_name );
431 if ( authenticator_buff.value)
432 gss_release_buffer( &status, &authenticator_buff );
434 gss_delete_sec_context( &status, &context_handle, NULL );
436 gss_release_cred( &status, &server_creds );
439 if (server_name != GSS_C_NO_NAME)
440 gss_release_name( &status, &server_name );
445 /* -------------------------- */
446 static int gss_login(void *obj, struct passwd **uam_pwd,
447 char *ibuf, size_t ibuflen,
448 char *rbuf, size_t *rbuflen)
455 /* The reply contains a two-byte ID value - note
456 * that Apple's implementation seems to always return 1 as well
459 memcpy(rbuf, &temp16, sizeof(temp16));
460 *rbuflen += sizeof(temp16);
461 return AFPERR_AUTHCONT;
464 static int gss_logincont(void *obj, struct passwd **uam_pwd,
465 char *ibuf, size_t ibuflen,
466 char *rbuf, size_t *rbuflen)
468 struct passwd *pwd = NULL;
475 struct session_info *sinfo;
477 /* Apple's AFP 3.1 documentation specifies that this command
478 * takes the following format:
480 * id returned in LoginExt response (uint16_t)
481 * username (format unspecified) padded, when necessary, to end on an even boundary
482 * ticket length (uint16_t)
486 /* Observation of AFP clients in the wild indicate that the actual
487 * format of this request is as follows:
488 * pad (byte) [consumed before login_ext is called]
489 * ?? (byte) - always observed to be 0
490 * id returned in LoginExt response (uint16_t)
491 * username, encoding unspecified, null terminated C string,
492 * padded when the terminating null is an even numbered byte.
493 * The packet is formated such that the username begins on an
494 * odd numbered byte. Eg if the username is 3 characters and the
495 * terminating null makes 4, expect to pad the the result.
496 * The encoding of this string is unknown.
497 * ticket length (uint16_t)
501 rblen = *rbuflen = 0;
503 if (ibuflen < 1 +sizeof(login_id)) {
504 LOG(log_info, logtype_uams, "uams_gss.c :LoginCont: received incomplete packet");
507 ibuf++, ibuflen--; /* ?? */
509 /* 2 byte ID from LoginExt -- always '00 01' in this implementation */
510 memcpy( &login_id, ibuf, sizeof(login_id) );
511 ibuf += sizeof(login_id), ibuflen -= sizeof(login_id);
512 login_id = ntohs( login_id );
514 /* get the username buffer from apfd */
515 if (uam_afpserver_option(obj, UAM_OPTION_USERNAME, (void *) &username, &userlen) < 0)
518 /* get the session_info structure from afpd. We need the session key */
519 if (uam_afpserver_option(obj, UAM_OPTION_SESSIONINFO, (void *)&sinfo, NULL) < 0)
522 if (sinfo->sessionkey == NULL || sinfo->sessionkey_len == 0) {
523 /* Should never happen. Most likely way too old afpd version */
524 LOG(log_info, logtype_uams, "internal error: afpd's sessionkey not set");
528 /* We skip past the 'username' parameter because all that matters is the ticket */
530 while( *ibuf && ibuflen ) { ibuf++, ibuflen--; }
532 LOG(log_info, logtype_uams, "uams_gss.c :LoginCont: user is %s, no ticket", p);
536 ibuf++, ibuflen--; /* null termination */
538 if ((ibuf - p + 1) % 2) ibuf++, ibuflen--; /* deal with potential padding */
540 LOG(log_debug, logtype_uams, "uams_gss.c :LoginCont: client thinks user is %s", p);
542 /* get the length of the ticket the client sends us */
543 memcpy(&ticket_len, ibuf, sizeof(ticket_len));
544 ibuf += sizeof(ticket_len); ibuflen -= sizeof(ticket_len);
545 ticket_len = ntohs( ticket_len );
547 /* a little bounds checking */
548 if (ticket_len > ibuflen) {
549 LOG(log_info, logtype_uams,
550 "uams_gss.c :LoginCont: invalid ticket length (%u > %u)", ticket_len, ibuflen);
554 /* now try to authenticate */
555 if (!do_gss_auth(obj, ibuf, ticket_len, rbuf, &rblen, username, userlen, sinfo)) {
556 /* We use the username we got back from the gssapi client_name.
557 Should we compare this to the username the client sent in the clear?
558 We know the character encoding of the cleartext username (UTF8), what
559 encoding is the gssapi name in? */
560 if((pwd = uam_getname( obj, username, userlen )) == NULL) {
561 LOG(log_info, logtype_uams, "uam_getname() failed for %s", username);
562 return AFPERR_NOTAUTH;
564 if (uam_checkuser(pwd) < 0) {
565 LOG(log_info, logtype_uams, "%s not a valid user", username);
566 return AFPERR_NOTAUTH;
572 LOG(log_info, logtype_uams, "do_gss_auth failed" );
579 * For the krb5 uam, this function only needs to return a two-byte
580 * login-session id. None of the data provided by the client up to this
581 * point is trustworthy as we'll have a signed ticket to parse in logincont.
583 static int gss_login_ext(void *obj, char *uname, struct passwd **uam_pwd,
584 char *ibuf, size_t ibuflen,
585 char *rbuf, size_t *rbuflen)
591 /* The reply contains a two-byte ID value - note
592 * that Apple's implementation seems to always return 1 as well
595 memcpy(rbuf, &temp16, sizeof(temp16));
596 *rbuflen += sizeof(temp16);
597 return AFPERR_AUTHCONT;
601 static void gss_logout() {
604 int uam_setup(const char *path)
606 if (uam_register(UAM_SERVER_LOGIN_EXT, path, "Client Krb v2",
607 gss_login, gss_logincont, gss_logout, gss_login_ext) < 0)
608 if (uam_register(UAM_SERVER_LOGIN, path, "Client Krb v2",
609 gss_login, gss_logincont, gss_logout) < 0)
615 static void uam_cleanup(void)
617 uam_unregister(UAM_SERVER_LOGIN_EXT, "Client Krb v2");
620 UAM_MODULE_EXPORT struct uam_export uams_gss = {
623 uam_setup, uam_cleanup