2 * $Id: uams_gss.c,v 1.5 2009-09-17 08:35:08 franklahm 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 int 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;
323 LOG(log_debug, logtype_uams,
324 "acquire credentials: acquiring credentials (uid = %d, keytab = %s)",
325 (int)geteuid(), getenv( "KRB5_KTNAME") );
327 * Acquire credentials usable for accepting context negotiations.
328 * Credentials are for server_name, have an indefinite lifetime,
329 * have no specific mechanisms, are to be used for accepting context
330 * negotiations and are to be placed in server_creds.
331 * We don't care about the mechanisms or about the time for which they are valid.
333 major_status = gss_acquire_cred( &minor_status, *server_name,
334 GSS_C_INDEFINITE, GSS_C_NO_OID_SET, GSS_C_ACCEPT,
335 server_creds, NULL, NULL );
337 if (major_status != GSS_S_COMPLETE) {
338 log_status( "acquire_cred", major_status, minor_status );
346 static int accept_sec_context (gss_ctx_id_t *context, gss_cred_id_t server_creds,
347 gss_buffer_desc *ticket_buffer, gss_name_t *client_name,
348 gss_buffer_desc *authenticator_buff)
350 OM_uint32 major_status = 0, minor_status = 0, ret_flags;
352 /* Initialize autheticator buffer. */
353 authenticator_buff->length = 0;
354 authenticator_buff->value = NULL;
356 LOG(log_debug, logtype_uams, "accept_context: accepting context (ticketlen: %u)",
357 ticket_buffer->length);
360 * Try to accept the secondary context using the tocken in ticket_buffer.
361 * We don't care about the mechanisms used, nor for the time.
362 * We don't act as a proxy either.
364 major_status = gss_accept_sec_context( &minor_status, context,
365 server_creds, ticket_buffer, GSS_C_NO_CHANNEL_BINDINGS,
366 client_name, NULL, authenticator_buff,
367 &ret_flags, NULL, NULL );
369 if (major_status != GSS_S_COMPLETE) {
370 log_status( "accept_sec_context", major_status, minor_status );
373 log_ctx_flags( ret_flags );
378 /* return 0 on success */
379 static int do_gss_auth(void *obj, char *ibuf, int ticket_len,
380 char *rbuf, int *rbuflen, char *username, int ulen,
381 struct session_info *sinfo )
383 OM_uint32 status = 0;
384 gss_name_t server_name, client_name;
385 gss_cred_id_t server_creds;
386 gss_ctx_id_t context_handle = GSS_C_NO_CONTEXT;
387 gss_buffer_desc ticket_buffer, authenticator_buff;
390 /* import our principal name from afpd */
391 if (get_afpd_principal(obj, &server_name) != 0) {
394 log_principal(server_name);
396 /* Now we have to acquire our credentials */
397 if ((ret = acquire_credentials (&server_name, &server_creds)))
401 * Try to accept the secondary context, using the ticket/token the
402 * client sent us. Ticket is stored at current ibuf position.
403 * Don't try to release ticket_buffer later, it points into ibuf!
405 ticket_buffer.length = ticket_len;
406 ticket_buffer.value = ibuf;
408 ret = accept_sec_context (&context_handle, server_creds, &ticket_buffer,
409 &client_name, &authenticator_buff);
412 /* We succesfully acquired the secondary context, now get the
413 username for afpd and gss_wrap the sessionkey */
414 if ( 0 == (ret = get_client_username(username, ulen, &client_name)) ) {
415 ret = wrap_sessionkey(context_handle, sinfo);
419 /* FIXME: Is copying the authenticator really necessary?
420 Where is this documented? */
421 u_int16_t auth_len = htons( authenticator_buff.length );
423 /* copy the authenticator length into the reply buffer */
424 memcpy( rbuf, &auth_len, sizeof(auth_len) );
425 *rbuflen += sizeof(auth_len);
426 rbuf += sizeof(auth_len);
428 /* copy the authenticator value into the reply buffer */
429 memcpy( rbuf, authenticator_buff.value, authenticator_buff.length );
430 *rbuflen += authenticator_buff.length;
433 /* Clean up after ourselves */
434 gss_release_name( &status, &client_name );
435 if ( authenticator_buff.value)
436 gss_release_buffer( &status, &authenticator_buff );
438 gss_delete_sec_context( &status, &context_handle, NULL );
440 gss_release_cred( &status, &server_creds );
443 gss_release_name( &status, &server_name );
448 /* -------------------------- */
449 static int gss_login(void *obj, struct passwd **uam_pwd,
450 char *ibuf, int ibuflen,
451 char *rbuf, int *rbuflen)
458 /* The reply contains a two-byte ID value - note
459 * that Apple's implementation seems to always return 1 as well
462 memcpy(rbuf, &temp16, sizeof(temp16));
463 *rbuflen += sizeof(temp16);
464 return AFPERR_AUTHCONT;
467 static int gss_logincont(void *obj, struct passwd **uam_pwd,
468 char *ibuf, int ibuflen,
469 char *rbuf, int *rbuflen)
471 struct passwd *pwd = NULL;
474 u_int16_t ticket_len;
478 struct session_info *sinfo;
480 /* Apple's AFP 3.1 documentation specifies that this command
481 * takes the following format:
483 * id returned in LoginExt response (u_int16_t)
484 * username (format unspecified) padded, when necessary, to end on an even boundary
485 * ticket length (u_int16_t)
489 /* Observation of AFP clients in the wild indicate that the actual
490 * format of this request is as follows:
491 * pad (byte) [consumed before login_ext is called]
492 * ?? (byte) - always observed to be 0
493 * id returned in LoginExt response (u_int16_t)
494 * username, encoding unspecified, null terminated C string,
495 * padded when the terminating null is an even numbered byte.
496 * The packet is formated such that the username begins on an
497 * odd numbered byte. Eg if the username is 3 characters and the
498 * terminating null makes 4, expect to pad the the result.
499 * The encoding of this string is unknown.
500 * ticket length (u_int16_t)
504 rblen = *rbuflen = 0;
507 LOG(log_info, logtype_uams, "uams_gss.c :LoginCont: received incomplete packet");
510 ibuf++, ibuflen--; /* ?? */
512 /* 2 byte ID from LoginExt -- always '00 01' in this implementation */
513 memcpy( &login_id, ibuf, sizeof(login_id) );
514 ibuf += sizeof(login_id), ibuflen -= sizeof(login_id);
515 login_id = ntohs( login_id );
517 /* get the username buffer from apfd */
518 if (uam_afpserver_option(obj, UAM_OPTION_USERNAME, (void *) &username, &userlen) < 0)
521 /* get the session_info structure from afpd. We need the session key */
522 if (uam_afpserver_option(obj, UAM_OPTION_SESSIONINFO, (void *)&sinfo, NULL) < 0)
525 if (sinfo->sessionkey == NULL || sinfo->sessionkey_len == 0) {
526 /* Should never happen. Most likely way too old afpd version */
527 LOG(log_info, logtype_uams, "internal error: afpd's sessionkey not set");
531 /* We skip past the 'username' parameter because all that matters is the ticket */
533 while( *ibuf && ibuflen ) { ibuf++, ibuflen--; }
535 LOG(log_info, logtype_uams, "uams_gss.c :LoginCont: user is %s, no ticket", p);
539 ibuf++, ibuflen--; /* null termination */
541 if ((ibuf - p + 1) % 2) ibuf++, ibuflen--; /* deal with potential padding */
543 LOG(log_info, logtype_uams, "uams_gss.c :LoginCont: client thinks user is %s", p);
545 /* get the length of the ticket the client sends us */
546 memcpy(&ticket_len, ibuf, sizeof(ticket_len));
547 ibuf += sizeof(ticket_len); ibuflen -= sizeof(ticket_len);
548 ticket_len = ntohs( ticket_len );
550 /* a little bounds checking */
551 if (ticket_len > ibuflen) {
552 LOG(log_info, logtype_uams,
553 "uams_gss.c :LoginCont: invalid ticket length (%u > %u)", ticket_len, ibuflen);
557 /* now try to authenticate */
558 if (!do_gss_auth(obj, ibuf, ticket_len, rbuf, &rblen, username, userlen, sinfo)) {
559 /* We use the username we got back from the gssapi client_name.
560 Should we compare this to the username the client sent in the clear?
561 We know the character encoding of the cleartext username (UTF8), what
562 encoding is the gssapi name in? */
563 if((pwd = uam_getname( obj, username, userlen )) == NULL) {
564 LOG(log_info, logtype_uams, "uam_getname() failed for %s", username);
567 if (uam_checkuser(pwd) < 0) {
568 LOG(log_info, logtype_uams, "%s not a valid user", username);
569 return AFPERR_NOTAUTH;
575 LOG(log_info, logtype_uams, "do_gss_auth failed" );
582 * For the krb5 uam, this function only needs to return a two-byte
583 * login-session id. None of the data provided by the client up to this
584 * point is trustworthy as we'll have a signed ticket to parse in logincont.
586 static int gss_login_ext(void *obj, char *uname, struct passwd **uam_pwd,
587 char *ibuf, int ibuflen,
588 char *rbuf, int *rbuflen)
594 /* The reply contains a two-byte ID value - note
595 * that Apple's implementation seems to always return 1 as well
598 memcpy(rbuf, &temp16, sizeof(temp16));
599 *rbuflen += sizeof(temp16);
600 return AFPERR_AUTHCONT;
604 static void gss_logout() {
607 int uam_setup(const char *path)
609 if (uam_register(UAM_SERVER_LOGIN_EXT, path, "Client Krb v2",
610 gss_login, gss_logincont, gss_logout, gss_login_ext) < 0)
611 if (uam_register(UAM_SERVER_LOGIN, path, "Client Krb v2",
612 gss_login, gss_logincont, gss_logout) < 0)
618 static void uam_cleanup(void)
620 uam_unregister(UAM_SERVER_LOGIN_EXT, "Client Krb v2");
623 UAM_MODULE_EXPORT struct uam_export uams_gss = {
626 uam_setup, uam_cleanup