2 * $Id: uams_gss.c,v 1.8 2009-10-15 11:39:48 didg Exp $
4 * Copyright (c) 1990,1993 Regents of The University of Michigan.
5 * Copyright (c) 1999 Adrian Sun (asun@u.washington.edu)
6 * Copyright (c) 2003 The Reed Institute
7 * Copyright (c) 2004 Bjoern Fernhomberg
8 * All Rights Reserved. See COPYRIGHT.
13 #endif /* HAVE_CONFIG_H */
19 #endif /* HAVE_UNISTD_H */
24 #else /* STDC_HEADERS */
28 #endif /* HAVE_STRCHR */
29 char *strchr (), *strrchr ();
31 #define memcpy(d,s,n) bcopy ((s), (d), (n))
32 #define memmove(d,s,n) bcopy ((s), (d), (n))
33 #endif /* ! HAVE_MEMCPY */
34 #endif /* STDC_HEADERS */
37 #include <atalk/logger.h>
38 #include <atalk/afp.h>
39 #include <atalk/uam.h>
40 #include <atalk/util.h>
42 /* Kerberos includes */
48 #if HAVE_GSSAPI_GSSAPI_H
49 #include <gssapi/gssapi.h>
52 #if HAVE_GSSAPI_GSSAPI_GENERIC_H
53 #include <gssapi/gssapi_generic.h>
56 #if HAVE_GSSAPI_GSSAPI_KRB5_H
57 #include <gssapi/gssapi_krb5.h>
64 /* We work around something I don't entirely understand... */
65 /* BF: This is a Heimdal/MIT compatibility fix */
66 #ifndef HAVE_GSS_C_NT_HOSTBASED_SERVICE
67 #define GSS_C_NT_HOSTBASED_SERVICE gss_nt_service_name
74 #define MIN(a, b) ((a > b) ? b : a)
76 static void log_status( char *s, OM_uint32 major_status,
77 OM_uint32 minor_status )
79 gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
80 OM_uint32 min_status, maj_status;
81 OM_uint32 maj_ctx = 0, min_ctx = 0;
84 maj_status = gss_display_status( &min_status, major_status,
85 GSS_C_GSS_CODE, GSS_C_NULL_OID,
87 LOG(log_info, logtype_uams, "uams_gss.c :do_gss_auth: %s %.*s (error %s)", s,
88 (int)msg.length, msg.value, strerror(errno));
89 gss_release_buffer(&min_status, &msg);
95 maj_status = gss_display_status( &min_status, minor_status,
96 GSS_C_MECH_CODE, GSS_C_NULL_OID, // gss_mech_krb5,
98 LOG(log_info, logtype_uams, "uams_gss.c :do_gss_auth: %s %.*s (error %s)", s,
99 (int)msg.length, msg.value, strerror(errno));
100 gss_release_buffer(&min_status, &msg);
108 static void log_ctx_flags( OM_uint32 flags )
111 if (flags & GSS_C_DELEG_FLAG)
112 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_DELEG_FLAG" );
113 if (flags & GSS_C_MUTUAL_FLAG)
114 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_MUTUAL_FLAG" );
115 if (flags & GSS_C_REPLAY_FLAG)
116 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_REPLAY_FLAG" );
117 if (flags & GSS_C_SEQUENCE_FLAG)
118 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_SEQUENCE_FLAG" );
119 if (flags & GSS_C_CONF_FLAG)
120 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_CONF_FLAG" );
121 if (flags & GSS_C_INTEG_FLAG)
122 LOG(log_debug, logtype_uams, "uams_gss.c :context flag: GSS_C_INTEG_FLAG" );
126 static void log_principal(gss_name_t server_name)
129 OM_uint32 major_status = 0, minor_status = 0;
130 gss_buffer_desc exported_name;
132 /* Only for debugging purposes, check the gssapi internal representation */
133 major_status = gss_export_name(&minor_status, server_name, &exported_name);
134 LOG(log_debug, logtype_uams, "log_principal: exported server name is %s", (char*) exported_name.value);
135 gss_release_buffer( &minor_status, &exported_name );
139 /* get the principal from afpd and import it into server_name */
140 static int get_afpd_principal(void *obj, gss_name_t *server_name)
142 OM_uint32 major_status = 0, minor_status = 0;
143 char *realm, *fqdn, *service, *principal, *p;
144 size_t realmlen=0, fqdnlen=0, servicelen=0;
145 size_t principal_length;
146 gss_buffer_desc s_princ_buffer;
148 /* get all the required information from afpd */
149 if (uam_afpserver_option(obj, UAM_OPTION_KRB5REALM, (void*) &realm, &realmlen) < 0)
151 if (uam_afpserver_option(obj, UAM_OPTION_FQDN, (void*) &fqdn, &fqdnlen) < 0)
153 if (uam_afpserver_option(obj, UAM_OPTION_KRB5SERVICE, (void *)&service, &servicelen) < 0)
156 /* we need all the info, log error and return if one's missing */
157 if (!service || !servicelen || !fqdn || !fqdnlen || !realm || !realmlen) {
158 LOG(log_error, logtype_uams,
159 "get_afpd_principal: could not retrieve required information from afpd.");
163 /* allocate memory to hold the temporary principal string */
164 principal_length = servicelen + 1 + fqdnlen + 1 + realmlen + 1;
165 if ( NULL == (principal = (char*) malloc( principal_length)) ) {
166 LOG(log_error, logtype_uams,
167 "get_afpd_principal: out of memory allocating %u bytes",
173 * Build the principal string.
174 * Format: 'service/fqdn@realm'
176 strlcpy( principal, service, principal_length);
177 strlcat( principal, "/", principal_length);
180 * The fqdn we get from afpd may contain a port.
181 * We need to strip the port from fqdn for principal.
183 p = strchr(fqdn, ':');
186 strlcat( principal, fqdn, principal_length);
189 strlcat( principal, "@", principal_length);
190 strlcat( principal, realm, principal_length);
193 * Import our principal into the gssapi internal representation
194 * stored in server_name.
196 s_princ_buffer.value = principal;
197 s_princ_buffer.length = strlen( principal ) + 1;
199 LOG(log_debug, logtype_uams, "get_afpd_principal: importing principal `%s'", principal);
200 major_status = gss_import_name( &minor_status,
206 * Get rid of malloc'ed memmory.
207 * Don't release the s_princ_buffer, we free principal instead.
211 if (major_status != GSS_S_COMPLETE) {
212 /* Importing our service principal failed, bail out. */
213 log_status( "import_principal", major_status, minor_status );
220 /* get the username */
221 static int get_client_username(char *username, int ulen, gss_name_t *client_name)
223 OM_uint32 major_status = 0, minor_status = 0;
224 gss_buffer_desc client_name_buffer;
229 * To extract the unix username, use gss_display_name on client_name.
230 * We do rely on gss_display_name returning a zero terminated string.
231 * The username returned contains the realm and possibly an instance.
232 * We only want the username for afpd, so we have to strip those from
233 * the username before copying it to afpd's buffer.
236 major_status = gss_display_name( &minor_status, *client_name,
237 &client_name_buffer, (gss_OID *)NULL );
238 if (major_status != GSS_S_COMPLETE) {
239 log_status( "display_name", major_status, minor_status );
243 LOG(log_debug, logtype_uams, "get_client_username: user is `%s'", client_name_buffer.value);
246 p = strchr( client_name_buffer.value, '@' );
249 /* FIXME: chop off instance? */
250 p = strchr( client_name_buffer.value, '/' );
254 /* check if this username fits into afpd's username buffer */
255 namelen = strlen(client_name_buffer.value);
256 if ( namelen >= ulen ) {
257 /* The username is too long for afpd's buffer, bail out */
258 LOG(log_error, logtype_uams,
259 "get_client_username: username `%s' too long", client_name_buffer.value);
263 /* copy stripped username to afpd's buffer */
264 strlcpy(username, client_name_buffer.value, ulen);
267 /* we're done with client_name_buffer, release it */
268 gss_release_buffer(&minor_status, &client_name_buffer );
273 /* wrap afpd's sessionkey */
274 static int wrap_sessionkey(gss_ctx_id_t context, struct session_info *sinfo)
276 OM_uint32 status = 0;
278 gss_buffer_desc sesskey_buff, wrap_buff;
281 * gss_wrap afpd's session_key.
282 * This is needed fo OS X 10.3 clients. They request this information
283 * with type 8 (kGetKerberosSessionKey) on FPGetSession.
284 * See AFP 3.1 specs, page 77.
287 sesskey_buff.value = sinfo->sessionkey;
288 sesskey_buff.length = sinfo->sessionkey_len;
290 /* gss_wrap the session key with the default machanism.
291 Require both confidentiality and integrity services */
292 gss_wrap (&status, context, 1, GSS_C_QOP_DEFAULT, &sesskey_buff, NULL, &wrap_buff);
294 if ( status != GSS_S_COMPLETE) {
295 LOG(log_error, logtype_uams, "wrap_sessionkey: failed to gss_wrap sessionkey");
296 log_status( "GSS wrap", 0, status );
300 /* store the wrapped session key in afpd's session_info struct */
301 if ( NULL == (sinfo->cryptedkey = malloc ( wrap_buff.length )) ) {
302 LOG(log_error, logtype_uams,
303 "wrap_sessionkey: out of memory tyring to allocate %u bytes",
307 /* cryptedkey is binary data */
308 memcpy (sinfo->cryptedkey, wrap_buff.value, wrap_buff.length);
309 sinfo->cryptedkey_len = wrap_buff.length;
312 /* we're done with buffer, release */
313 gss_release_buffer( &status, &wrap_buff );
319 static int acquire_credentials (gss_name_t *server_name, gss_cred_id_t *server_creds)
321 OM_uint32 major_status = 0, minor_status = 0;
324 if (envp = getenv("KRB5_KTNAME"))
325 LOG(log_debug, logtype_uams,
326 "acquire credentials: acquiring credentials (uid = %d, keytab = %s)",
327 (int)geteuid(), envp);
329 LOG(log_debug, logtype_uams,
330 "acquire credentials: acquiring credentials (uid = %d) - $KRB5_KTNAME not found in env",
334 * Acquire credentials usable for accepting context negotiations.
335 * Credentials are for server_name, have an indefinite lifetime,
336 * have no specific mechanisms, are to be used for accepting context
337 * negotiations and are to be placed in server_creds.
338 * We don't care about the mechanisms or about the time for which they are valid.
340 major_status = gss_acquire_cred( &minor_status, *server_name,
341 GSS_C_INDEFINITE, GSS_C_NO_OID_SET, GSS_C_ACCEPT,
342 server_creds, NULL, NULL );
344 if (major_status != GSS_S_COMPLETE) {
345 log_status( "acquire_cred", major_status, minor_status );
353 static int accept_sec_context (gss_ctx_id_t *context, gss_cred_id_t server_creds,
354 gss_buffer_desc *ticket_buffer, gss_name_t *client_name,
355 gss_buffer_desc *authenticator_buff)
357 OM_uint32 major_status = 0, minor_status = 0, ret_flags;
359 /* Initialize autheticator buffer. */
360 authenticator_buff->length = 0;
361 authenticator_buff->value = NULL;
363 LOG(log_debug, logtype_uams, "accept_context: accepting context (ticketlen: %u)",
364 ticket_buffer->length);
367 * Try to accept the secondary context using the tocken in ticket_buffer.
368 * We don't care about the mechanisms used, nor for the time.
369 * We don't act as a proxy either.
371 major_status = gss_accept_sec_context( &minor_status, context,
372 server_creds, ticket_buffer, GSS_C_NO_CHANNEL_BINDINGS,
373 client_name, NULL, authenticator_buff,
374 &ret_flags, NULL, NULL );
376 if (major_status != GSS_S_COMPLETE) {
377 log_status( "accept_sec_context", major_status, minor_status );
380 log_ctx_flags( ret_flags );
385 /* return 0 on success */
386 static int do_gss_auth(void *obj, char *ibuf, int ticket_len,
387 char *rbuf, int *rbuflen, char *username, int ulen,
388 struct session_info *sinfo )
390 OM_uint32 status = 0;
391 gss_name_t server_name, client_name;
392 gss_cred_id_t server_creds;
393 gss_ctx_id_t context_handle = GSS_C_NO_CONTEXT;
394 gss_buffer_desc ticket_buffer, authenticator_buff;
397 /* import our principal name from afpd */
398 if (get_afpd_principal(obj, &server_name) != 0) {
401 log_principal(server_name);
403 /* Now we have to acquire our credentials */
404 if ((ret = acquire_credentials (&server_name, &server_creds)))
408 * Try to accept the secondary context, using the ticket/token the
409 * client sent us. Ticket is stored at current ibuf position.
410 * Don't try to release ticket_buffer later, it points into ibuf!
412 ticket_buffer.length = ticket_len;
413 ticket_buffer.value = ibuf;
415 ret = accept_sec_context (&context_handle, server_creds, &ticket_buffer,
416 &client_name, &authenticator_buff);
419 /* We succesfully acquired the secondary context, now get the
420 username for afpd and gss_wrap the sessionkey */
421 if ( 0 == (ret = get_client_username(username, ulen, &client_name)) ) {
422 ret = wrap_sessionkey(context_handle, sinfo);
426 /* FIXME: Is copying the authenticator really necessary?
427 Where is this documented? */
428 u_int16_t auth_len = htons( authenticator_buff.length );
430 /* copy the authenticator length into the reply buffer */
431 memcpy( rbuf, &auth_len, sizeof(auth_len) );
432 *rbuflen += sizeof(auth_len);
433 rbuf += sizeof(auth_len);
435 /* copy the authenticator value into the reply buffer */
436 memcpy( rbuf, authenticator_buff.value, authenticator_buff.length );
437 *rbuflen += authenticator_buff.length;
440 /* Clean up after ourselves */
441 gss_release_name( &status, &client_name );
442 if ( authenticator_buff.value)
443 gss_release_buffer( &status, &authenticator_buff );
445 gss_delete_sec_context( &status, &context_handle, NULL );
447 gss_release_cred( &status, &server_creds );
450 gss_release_name( &status, &server_name );
455 /* -------------------------- */
456 static int gss_login(void *obj, struct passwd **uam_pwd,
457 char *ibuf, size_t ibuflen,
458 char *rbuf, size_t *rbuflen)
465 /* The reply contains a two-byte ID value - note
466 * that Apple's implementation seems to always return 1 as well
469 memcpy(rbuf, &temp16, sizeof(temp16));
470 *rbuflen += sizeof(temp16);
471 return AFPERR_AUTHCONT;
474 static int gss_logincont(void *obj, struct passwd **uam_pwd,
475 char *ibuf, size_t ibuflen,
476 char *rbuf, size_t *rbuflen)
478 struct passwd *pwd = NULL;
481 u_int16_t ticket_len;
485 struct session_info *sinfo;
487 /* Apple's AFP 3.1 documentation specifies that this command
488 * takes the following format:
490 * id returned in LoginExt response (u_int16_t)
491 * username (format unspecified) padded, when necessary, to end on an even boundary
492 * ticket length (u_int16_t)
496 /* Observation of AFP clients in the wild indicate that the actual
497 * format of this request is as follows:
498 * pad (byte) [consumed before login_ext is called]
499 * ?? (byte) - always observed to be 0
500 * id returned in LoginExt response (u_int16_t)
501 * username, encoding unspecified, null terminated C string,
502 * padded when the terminating null is an even numbered byte.
503 * The packet is formated such that the username begins on an
504 * odd numbered byte. Eg if the username is 3 characters and the
505 * terminating null makes 4, expect to pad the the result.
506 * The encoding of this string is unknown.
507 * ticket length (u_int16_t)
511 rblen = *rbuflen = 0;
513 if (ibuflen < 1 +sizeof(login_id)) {
514 LOG(log_info, logtype_uams, "uams_gss.c :LoginCont: received incomplete packet");
517 ibuf++, ibuflen--; /* ?? */
519 /* 2 byte ID from LoginExt -- always '00 01' in this implementation */
520 memcpy( &login_id, ibuf, sizeof(login_id) );
521 ibuf += sizeof(login_id), ibuflen -= sizeof(login_id);
522 login_id = ntohs( login_id );
524 /* get the username buffer from apfd */
525 if (uam_afpserver_option(obj, UAM_OPTION_USERNAME, (void *) &username, &userlen) < 0)
528 /* get the session_info structure from afpd. We need the session key */
529 if (uam_afpserver_option(obj, UAM_OPTION_SESSIONINFO, (void *)&sinfo, NULL) < 0)
532 if (sinfo->sessionkey == NULL || sinfo->sessionkey_len == 0) {
533 /* Should never happen. Most likely way too old afpd version */
534 LOG(log_info, logtype_uams, "internal error: afpd's sessionkey not set");
538 /* We skip past the 'username' parameter because all that matters is the ticket */
540 while( *ibuf && ibuflen ) { ibuf++, ibuflen--; }
542 LOG(log_info, logtype_uams, "uams_gss.c :LoginCont: user is %s, no ticket", p);
546 ibuf++, ibuflen--; /* null termination */
548 if ((ibuf - p + 1) % 2) ibuf++, ibuflen--; /* deal with potential padding */
550 LOG(log_info, logtype_uams, "uams_gss.c :LoginCont: client thinks user is %s", p);
552 /* get the length of the ticket the client sends us */
553 memcpy(&ticket_len, ibuf, sizeof(ticket_len));
554 ibuf += sizeof(ticket_len); ibuflen -= sizeof(ticket_len);
555 ticket_len = ntohs( ticket_len );
557 /* a little bounds checking */
558 if (ticket_len > ibuflen) {
559 LOG(log_info, logtype_uams,
560 "uams_gss.c :LoginCont: invalid ticket length (%u > %u)", ticket_len, ibuflen);
564 /* now try to authenticate */
565 if (!do_gss_auth(obj, ibuf, ticket_len, rbuf, &rblen, username, userlen, sinfo)) {
566 /* We use the username we got back from the gssapi client_name.
567 Should we compare this to the username the client sent in the clear?
568 We know the character encoding of the cleartext username (UTF8), what
569 encoding is the gssapi name in? */
570 if((pwd = uam_getname( obj, username, userlen )) == NULL) {
571 LOG(log_info, logtype_uams, "uam_getname() failed for %s", username);
574 if (uam_checkuser(pwd) < 0) {
575 LOG(log_info, logtype_uams, "%s not a valid user", username);
576 return AFPERR_NOTAUTH;
582 LOG(log_info, logtype_uams, "do_gss_auth failed" );
589 * For the krb5 uam, this function only needs to return a two-byte
590 * login-session id. None of the data provided by the client up to this
591 * point is trustworthy as we'll have a signed ticket to parse in logincont.
593 static int gss_login_ext(void *obj, char *uname, struct passwd **uam_pwd,
594 char *ibuf, size_t ibuflen,
595 char *rbuf, size_t *rbuflen)
601 /* The reply contains a two-byte ID value - note
602 * that Apple's implementation seems to always return 1 as well
605 memcpy(rbuf, &temp16, sizeof(temp16));
606 *rbuflen += sizeof(temp16);
607 return AFPERR_AUTHCONT;
611 static void gss_logout() {
614 int uam_setup(const char *path)
616 if (uam_register(UAM_SERVER_LOGIN_EXT, path, "Client Krb v2",
617 gss_login, gss_logincont, gss_logout, gss_login_ext) < 0)
618 if (uam_register(UAM_SERVER_LOGIN, path, "Client Krb v2",
619 gss_login, gss_logincont, gss_logout) < 0)
625 static void uam_cleanup(void)
627 uam_unregister(UAM_SERVER_LOGIN_EXT, "Client Krb v2");
630 UAM_MODULE_EXPORT struct uam_export uams_gss = {
633 uam_setup, uam_cleanup