2 * CIFS user-space helper.
3 * Copyright (C) Igor Mammedov (niallain@gmail.com) 2007
4 * Copyright (C) Jeff Layton (jlayton@redhat.com) 2009
6 * Used by /sbin/request-key for handling
7 * cifs upcall for kerberos authorization of access to share and
8 * cifs upcall for DFS srver name resolving (IPv4/IPv6 aware).
9 * You should have keyutils installed and add something like the
10 * following lines to /etc/request-key.conf file:
12 create cifs.spnego * * /usr/local/sbin/cifs.upcall %k
13 create dns_resolver * * /usr/local/sbin/cifs.upcall %k
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2 of the License, or
18 * (at your option) any later version.
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to the Free Software
25 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
29 #include "../libcli/auth/spnego.h"
34 #include "cifs_spnego.h"
36 #define CIFS_DEFAULT_KRB5_DIR "/tmp"
37 #define CIFS_DEFAULT_KRB5_PREFIX "krb5cc_"
39 #define MAX_CCNAME_LEN PATH_MAX + 5
42 * samba forces the build to fail if strncasecmp is used, disable that for now
48 const char *CIFSSPNEGO_VERSION = "1.3";
49 static const char *prog = "cifs.upcall";
50 typedef enum _sectype {
57 * smb_krb5_principal_get_realm
59 * @brief Get realm of a principal
61 * @param[in] context The krb5_context
62 * @param[in] principal The principal
63 * @return pointer to the realm
67 static char *cifs_krb5_principal_get_realm(krb5_context context,
68 krb5_principal principal)
70 #ifdef HAVE_KRB5_PRINCIPAL_GET_REALM /* Heimdal */
71 return krb5_principal_get_realm(context, principal);
72 #elif defined(krb5_princ_realm) /* MIT */
74 realm = krb5_princ_realm(context, principal);
75 return (char *)realm->data;
81 #if !defined(HAVE_KRB5_FREE_UNPARSED_NAME)
82 void krb5_free_unparsed_name(krb5_context context, char *val)
88 /* does the ccache have a valid TGT? */
90 get_tgt_time(const char *ccname) {
95 krb5_principal principal;
99 if (krb5_init_context(&context)) {
100 syslog(LOG_DEBUG, "%s: unable to init krb5 context", __func__);
104 if (krb5_cc_resolve(context, ccname, &ccache)) {
105 syslog(LOG_DEBUG, "%s: unable to resolve krb5 cache", __func__);
109 if (krb5_cc_set_flags(context, ccache, 0)) {
110 syslog(LOG_DEBUG, "%s: unable to set flags", __func__);
114 if (krb5_cc_get_principal(context, ccache, &principal)) {
115 syslog(LOG_DEBUG, "%s: unable to get principal", __func__);
119 if (krb5_cc_start_seq_get(context, ccache, &cur)) {
120 syslog(LOG_DEBUG, "%s: unable to seq start", __func__);
124 if ((realm = cifs_krb5_principal_get_realm(context, principal)) == NULL) {
125 syslog(LOG_DEBUG, "%s: unable to get realm", __func__);
129 while (!credtime && !krb5_cc_next_cred(context, ccache, &cur, &creds)) {
131 if (krb5_unparse_name(context, creds.server, &name)) {
132 syslog(LOG_DEBUG, "%s: unable to unparse name", __func__);
135 if (krb5_realm_compare(context, creds.server, principal) &&
136 !strncasecmp(name, KRB5_TGS_NAME, KRB5_TGS_NAME_SIZE) &&
137 !strncasecmp(name+KRB5_TGS_NAME_SIZE+1, realm, strlen(realm)) &&
138 creds.times.endtime > time(NULL))
139 credtime = creds.times.endtime;
140 krb5_free_cred_contents(context, &creds);
141 krb5_free_unparsed_name(context, name);
144 krb5_cc_end_seq_get(context, ccache, &cur);
146 krb5_free_principal(context, principal);
148 #if defined(KRB5_TC_OPENCLOSE)
149 krb5_cc_set_flags(context, ccache, KRB5_TC_OPENCLOSE);
151 krb5_cc_close(context, ccache);
153 krb5_free_context(context);
158 krb5cc_filter(const struct dirent *dirent)
160 if (strstr(dirent->d_name, CIFS_DEFAULT_KRB5_PREFIX))
166 /* search for a credcache that looks like a likely candidate */
168 find_krb5_cc(const char *dirname, uid_t uid)
170 struct dirent **namelist;
172 char ccname[MAX_CCNAME_LEN], *credpath, *best_cache = NULL;
174 time_t cred_time, best_time = 0;
176 n = scandir(dirname, &namelist, krb5cc_filter, NULL);
178 syslog(LOG_DEBUG, "%s: scandir error on directory '%s': %s",
179 __func__, dirname, strerror(errno));
183 for (i = 0; i < n; i++) {
184 snprintf(ccname, sizeof(ccname), "FILE:%s/%s", dirname,
185 namelist[i]->d_name);
186 credpath = ccname + 5;
187 syslog(LOG_DEBUG, "%s: considering %s", __func__, credpath);
189 if (lstat(credpath, &sbuf)) {
190 syslog(LOG_DEBUG, "%s: stat error on '%s': %s",
191 __func__, credpath, strerror(errno));
195 if (sbuf.st_uid != uid) {
196 syslog(LOG_DEBUG, "%s: %s is owned by %u, not %u",
197 __func__, credpath, sbuf.st_uid, uid);
201 if (!S_ISREG(sbuf.st_mode)) {
202 syslog(LOG_DEBUG, "%s: %s is not a regular file",
207 if (!(cred_time = get_tgt_time(ccname))) {
208 syslog(LOG_DEBUG, "%s: %s is not a valid credcache.",
214 if (cred_time <= best_time) {
215 syslog(LOG_DEBUG, "%s: %s expires sooner than current "
216 "best.", __func__, ccname);
221 syslog(LOG_DEBUG, "%s: %s is valid ccache", __func__, ccname);
223 best_cache = strndup(ccname, MAX_CCNAME_LEN);
224 best_time = cred_time;
233 cifs_krb5_get_req(const char *principal, const char *ccname,
234 DATA_BLOB *mechtoken, DATA_BLOB *sess_key)
238 krb5_context context;
240 krb5_creds in_creds = { }, *out_creds;
241 krb5_data apreq_pkt, in_data;
242 krb5_auth_context auth_context = NULL;
244 ret = krb5_init_context(&context);
246 syslog(LOG_DEBUG, "%s: unable to init krb5 context", __func__);
250 ret = krb5_cc_resolve(context, ccname, &ccache);
252 syslog(LOG_DEBUG, "%s: unable to resolve %s to ccache\n",
254 goto out_free_context;
257 ret = krb5_cc_get_principal(context, ccache, &in_creds.client);
259 syslog(LOG_DEBUG, "%s: unable to get client principal name",
261 goto out_free_ccache;
264 ret = krb5_parse_name(context, principal, &in_creds.server);
266 syslog(LOG_DEBUG, "%s: unable to parse principal (%s).",
267 __func__, principal);
268 goto out_free_principal;
271 in_creds.keyblock.enctype = 0;
272 ret = krb5_get_credentials(context, 0, ccache, &in_creds, &out_creds);
273 krb5_free_principal(context, in_creds.server);
275 syslog(LOG_DEBUG, "%s: unable to get credentials for %s",
276 __func__, principal);
277 goto out_free_principal;
280 apreq_pkt.data = NULL;
282 ret = krb5_mk_req_extended(context, &auth_context, AP_OPTS_USE_SUBKEY,
283 &in_data, out_creds, &apreq_pkt);
285 syslog(LOG_DEBUG, "%s: unable to make AP-REQ for %s",
286 __func__, principal);
290 ret = krb5_auth_con_getsendsubkey(context, auth_context, &tokb);
292 syslog(LOG_DEBUG, "%s: unable to get session key for %s",
293 __func__, principal);
297 *mechtoken = data_blob(apreq_pkt.data, apreq_pkt.length);
298 *sess_key = data_blob(tokb->contents, tokb->length);
300 krb5_free_keyblock(context, tokb);
302 krb5_free_creds(context, out_creds);
304 krb5_free_principal(context, in_creds.client);
306 #if defined(KRB5_TC_OPENCLOSE)
307 krb5_cc_set_flags(context, ccache, KRB5_TC_OPENCLOSE);
309 krb5_cc_close(context, ccache);
311 krb5_free_context(context);
316 * Prepares AP-REQ data for mechToken and gets session key
317 * Uses credentials from cache. It will not ask for password
318 * you should receive credentials for yuor name manually using
319 * kinit or whatever you wish.
322 * oid - string with OID/ Could be OID_KERBEROS5
323 * or OID_KERBEROS5_OLD
324 * principal - Service name.
325 * Could be "cifs/FQDN" for KRB5 OID
326 * or for MS_KRB5 OID style server principal
327 * like "pdc$@YOUR.REALM.NAME"
330 * secblob - pointer for spnego wrapped AP-REQ data to be stored
331 * sess_key- pointer for SessionKey data to be stored
333 * ret: 0 - success, others - failure
336 handle_krb5_mech(const char *oid, const char *principal, DATA_BLOB *secblob,
337 DATA_BLOB *sess_key, const char *ccname)
340 DATA_BLOB tkt, tkt_wrapped;
342 syslog(LOG_DEBUG, "%s: getting service ticket for %s", __func__,
345 /* get a kerberos ticket for the service and extract the session key */
346 retval = cifs_krb5_get_req(principal, ccname, &tkt, sess_key);
348 syslog(LOG_DEBUG, "%s: failed to obtain service ticket (%d)",
353 syslog(LOG_DEBUG, "%s: obtained service ticket", __func__);
355 /* wrap that up in a nice GSS-API wrapping */
356 tkt_wrapped = spnego_gen_krb5_wrap(tkt, TOK_ID_KRB_AP_REQ);
358 /* and wrap that in a shiny SPNEGO wrapper */
359 *secblob = gen_negTokenInit(oid, tkt_wrapped);
361 data_blob_free(&tkt_wrapped);
362 data_blob_free(&tkt);
366 #define DKD_HAVE_HOSTNAME 0x1
367 #define DKD_HAVE_VERSION 0x2
368 #define DKD_HAVE_SEC 0x4
369 #define DKD_HAVE_IP 0x8
370 #define DKD_HAVE_UID 0x10
371 #define DKD_HAVE_PID 0x20
372 #define DKD_MUSTHAVE_SET (DKD_HAVE_HOSTNAME|DKD_HAVE_VERSION|DKD_HAVE_SEC)
374 struct decoded_args {
384 decode_key_description(const char *desc, struct decoded_args *arg)
389 const char *tkn = desc;
392 pos = index(tkn, ';');
393 if (strncmp(tkn, "host=", 5) == 0) {
401 SAFE_FREE(arg->hostname);
402 arg->hostname = SMB_XMALLOC_ARRAY(char, len);
403 strlcpy(arg->hostname, tkn + 5, len);
404 retval |= DKD_HAVE_HOSTNAME;
405 } else if (!strncmp(tkn, "ip4=", 4) ||
406 !strncmp(tkn, "ip6=", 4)) {
414 arg->ip = SMB_XMALLOC_ARRAY(char, len);
415 strlcpy(arg->ip, tkn + 4, len);
416 retval |= DKD_HAVE_IP;
417 } else if (strncmp(tkn, "pid=", 4) == 0) {
419 arg->pid = strtol(tkn + 4, NULL, 0);
421 syslog(LOG_ERR, "Invalid pid format: %s",
425 retval |= DKD_HAVE_PID;
427 } else if (strncmp(tkn, "sec=", 4) == 0) {
428 if (strncmp(tkn + 4, "krb5", 4) == 0) {
429 retval |= DKD_HAVE_SEC;
431 } else if (strncmp(tkn + 4, "mskrb5", 6) == 0) {
432 retval |= DKD_HAVE_SEC;
435 } else if (strncmp(tkn, "uid=", 4) == 0) {
437 arg->uid = strtol(tkn + 4, NULL, 16);
439 syslog(LOG_ERR, "Invalid uid format: %s",
443 retval |= DKD_HAVE_UID;
445 } else if (strncmp(tkn, "ver=", 4) == 0) { /* if version */
447 arg->ver = strtol(tkn + 4, NULL, 16);
449 syslog(LOG_ERR, "Invalid version format: %s",
453 retval |= DKD_HAVE_VERSION;
464 cifs_resolver(const key_serial_t key, const char *key_descr)
467 struct addrinfo *addr;
468 char ip[INET6_ADDRSTRLEN];
470 const char *keyend = key_descr;
471 /* skip next 4 ';' delimiters to get to description */
472 for (c = 1; c <= 4; c++) {
473 keyend = index(keyend+1, ';');
475 syslog(LOG_ERR, "invalid key description: %s",
482 /* resolve name to ip */
483 c = getaddrinfo(keyend, NULL, NULL, &addr);
485 syslog(LOG_ERR, "unable to resolve hostname: %s [%s]",
486 keyend, gai_strerror(c));
490 /* conver ip to string form */
491 if (addr->ai_family == AF_INET)
492 p = &(((struct sockaddr_in *)addr->ai_addr)->sin_addr);
494 p = &(((struct sockaddr_in6 *)addr->ai_addr)->sin6_addr);
496 if (!inet_ntop(addr->ai_family, p, ip, sizeof(ip))) {
497 syslog(LOG_ERR, "%s: inet_ntop: %s", __func__, strerror(errno));
503 c = keyctl_instantiate(key, ip, strlen(ip)+1, 0);
505 syslog(LOG_ERR, "%s: keyctl_instantiate: %s", __func__,
516 * Older kernels sent IPv6 addresses without colons. Well, at least
517 * they're fixed-length strings. Convert these addresses to have colon
518 * delimiters to make getaddrinfo happy.
521 convert_inet6_addr(const char *from, char *to)
527 if (!(i++ % 4) && *from)
534 ip_to_fqdn(const char *addrstr, char *host, size_t hostlen)
537 struct addrinfo hints = { .ai_flags = AI_NUMERICHOST };
538 struct addrinfo *res;
539 const char *ipaddr = addrstr;
540 char converted[INET6_ADDRSTRLEN + 1];
542 if ((strlen(ipaddr) > INET_ADDRSTRLEN) && !strchr(ipaddr, ':')) {
543 convert_inet6_addr(ipaddr, converted);
547 rc = getaddrinfo(ipaddr, NULL, &hints, &res);
549 syslog(LOG_DEBUG, "%s: failed to resolve %s to "
550 "ipaddr: %s", __func__, ipaddr,
551 rc == EAI_SYSTEM ? strerror(errno) : gai_strerror(rc));
555 rc = getnameinfo(res->ai_addr, res->ai_addrlen, host, hostlen,
556 NULL, 0, NI_NAMEREQD);
559 syslog(LOG_DEBUG, "%s: failed to resolve %s to fqdn: %s",
561 rc == EAI_SYSTEM ? strerror(errno) : gai_strerror(rc));
565 syslog(LOG_DEBUG, "%s: resolved %s to %s", __func__, ipaddr, host);
572 syslog(LOG_INFO, "Usage: %s [-t] [-v] key_serial", prog);
573 fprintf(stderr, "Usage: %s [-t] [-v] key_serial\n", prog);
576 const struct option long_options[] = {
577 { "trust-dns", 0, NULL, 't' },
578 { "version", 0, NULL, 'v' },
582 int main(const int argc, char *const argv[])
584 struct cifs_spnego_msg *keydata = NULL;
585 DATA_BLOB secblob = data_blob_null;
586 DATA_BLOB sess_key = data_blob_null;
587 key_serial_t key = 0;
592 char *buf, *princ = NULL, *ccname = NULL;
593 char hostbuf[NI_MAXHOST], *host;
594 struct decoded_args arg = { };
599 openlog(prog, 0, LOG_DAEMON);
601 while ((c = getopt_long(argc, argv, "ctv", long_options, NULL)) != -1) {
604 /* legacy option -- skip it */
610 printf("version: %s\n", CIFSSPNEGO_VERSION);
613 syslog(LOG_ERR, "unknown option: %c", c);
618 /* is there a key? */
619 if (argc <= optind) {
624 /* get key and keyring values */
626 key = strtol(argv[optind], NULL, 10);
629 syslog(LOG_ERR, "Invalid key format: %s", strerror(errno));
633 rc = keyctl_describe_alloc(key, &buf);
635 syslog(LOG_ERR, "keyctl_describe_alloc failed: %s",
641 syslog(LOG_DEBUG, "key description: %s", buf);
643 if ((strncmp(buf, "cifs.resolver", sizeof("cifs.resolver")-1) == 0) ||
644 (strncmp(buf, "dns_resolver", sizeof("dns_resolver")-1) == 0)) {
645 rc = cifs_resolver(key, buf);
649 have = decode_key_description(buf, &arg);
651 if ((have & DKD_MUSTHAVE_SET) != DKD_MUSTHAVE_SET) {
652 syslog(LOG_ERR, "unable to get necessary params from key "
653 "description (0x%x)", have);
658 if (arg.ver > CIFS_SPNEGO_UPCALL_VERSION) {
659 syslog(LOG_ERR, "incompatible kernel upcall version: 0x%x",
665 if (have & DKD_HAVE_UID) {
666 rc = setuid(arg.uid);
668 syslog(LOG_ERR, "setuid: %s", strerror(errno));
672 ccname = find_krb5_cc(CIFS_DEFAULT_KRB5_DIR, arg.uid);
677 // do mech specific authorization
682 /* for "cifs/" service name + terminating 0 */
683 datalen = strlen(host) + 5 + 1;
684 princ = SMB_XMALLOC_ARRAY(char, datalen);
690 if (arg.sec == MS_KRB5)
691 oid = OID_KERBEROS5_OLD;
696 * try getting a cifs/ principal first and then fall back to
697 * getting a host/ principal if that doesn't work.
699 strlcpy(princ, "cifs/", datalen);
700 strlcpy(princ + 5, host, datalen - 5);
701 rc = handle_krb5_mech(oid, princ, &secblob, &sess_key, ccname);
705 memcpy(princ, "host/", 5);
706 rc = handle_krb5_mech(oid, princ, &secblob, &sess_key, ccname);
710 if (!try_dns || !(have & DKD_HAVE_IP))
713 rc = ip_to_fqdn(arg.ip, hostbuf, sizeof(hostbuf));
720 goto retry_new_hostname;
722 syslog(LOG_ERR, "sectype: %d is not implemented", arg.sec);
732 /* pack SecurityBLob and SessionKey into downcall packet */
734 sizeof(struct cifs_spnego_msg) + secblob.length + sess_key.length;
735 keydata = (struct cifs_spnego_msg*)SMB_XMALLOC_ARRAY(char, datalen);
740 keydata->version = arg.ver;
742 keydata->sesskey_len = sess_key.length;
743 keydata->secblob_len = secblob.length;
744 memcpy(&(keydata->data), sess_key.data, sess_key.length);
745 memcpy(&(keydata->data) + keydata->sesskey_len,
746 secblob.data, secblob.length);
749 rc = keyctl_instantiate(key, keydata, datalen, 0);
751 syslog(LOG_ERR, "keyctl_instantiate: %s", strerror(errno));
755 /* BB: maybe we need use timeout for key: for example no more then
756 * ticket lifietime? */
757 /* keyctl_set_timeout( key, 60); */
760 * on error, negatively instantiate the key ourselves so that we can
761 * make sure the kernel doesn't hang it off of a searchable keyring
762 * and interfere with the next attempt to instantiate the key.
764 if (rc != 0 && key == 0)
765 keyctl_negate(key, 1, KEY_REQKEY_DEFL_DEFAULT);
766 data_blob_free(&secblob);
767 data_blob_free(&sess_key);
769 SAFE_FREE(arg.hostname);