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
32 #include "cifs_spnego.h"
34 #define CIFS_DEFAULT_KRB5_DIR "/tmp"
35 #define CIFS_DEFAULT_KRB5_PREFIX "krb5cc_"
37 #define MAX_CCNAME_LEN PATH_MAX + 5
39 const char *CIFSSPNEGO_VERSION = "1.3";
40 static const char *prog = "cifs.upcall";
41 typedef enum _sectype {
48 k5_data_equal(krb5_data d1, krb5_data d2, unsigned int length)
53 return (d1.length == length &&
54 d1.length == d2.length &&
55 memcmp(d1.data, d2.data, length) == 0);
59 /* does the ccache have a valid TGT? */
61 get_tgt_time(const char *ccname) {
66 krb5_principal principal;
67 krb5_data tgt = { .data = "krbtgt",
71 if (krb5_init_context(&context)) {
72 syslog(LOG_DEBUG, "%s: unable to init krb5 context", __func__);
76 if (krb5_cc_resolve(context, ccname, &ccache)) {
77 syslog(LOG_DEBUG, "%s: unable to resolve krb5 cache", __func__);
81 if (krb5_cc_set_flags(context, ccache, 0)) {
82 syslog(LOG_DEBUG, "%s: unable to set flags", __func__);
86 if (krb5_cc_get_principal(context, ccache, &principal)) {
87 syslog(LOG_DEBUG, "%s: unable to get principal", __func__);
91 if (krb5_cc_start_seq_get(context, ccache, &cur)) {
92 syslog(LOG_DEBUG, "%s: unable to seq start", __func__);
96 while (!credtime && !krb5_cc_next_cred(context, ccache, &cur, &creds)) {
97 if (k5_data_equal(creds.server->realm, principal->realm, 0) &&
98 k5_data_equal(creds.server->data[0], tgt, tgt.length) &&
99 k5_data_equal(creds.server->data[1], principal->realm, 0) &&
100 creds.times.endtime > time(NULL))
101 credtime = creds.times.endtime;
102 krb5_free_cred_contents(context, &creds);
104 krb5_cc_end_seq_get(context, ccache, &cur);
107 krb5_free_principal(context, principal);
109 krb5_cc_set_flags(context, ccache, KRB5_TC_OPENCLOSE);
110 krb5_cc_close(context, ccache);
112 krb5_free_context(context);
117 krb5cc_filter(const struct dirent *dirent)
119 if (strstr(dirent->d_name, CIFS_DEFAULT_KRB5_PREFIX))
125 /* search for a credcache that looks like a likely candidate */
127 find_krb5_cc(const char *dirname, uid_t uid)
129 struct dirent **namelist;
131 char ccname[MAX_CCNAME_LEN], *credpath, *best_cache = NULL;
133 time_t cred_time, best_time = 0;
135 n = scandir(dirname, &namelist, krb5cc_filter, NULL);
137 syslog(LOG_DEBUG, "%s: scandir error on directory '%s': %s",
138 __func__, dirname, strerror(errno));
142 for (i = 0; i < n; i++) {
143 snprintf(ccname, sizeof(ccname), "FILE:%s/%s", dirname,
144 namelist[i]->d_name);
145 credpath = ccname + 5;
146 syslog(LOG_DEBUG, "%s: considering %s", __func__, credpath);
148 if (lstat(credpath, &sbuf)) {
149 syslog(LOG_DEBUG, "%s: stat error on '%s': %s",
150 __func__, credpath, strerror(errno));
154 if (sbuf.st_uid != uid) {
155 syslog(LOG_DEBUG, "%s: %s is owned by %u, not %u",
156 __func__, credpath, sbuf.st_uid, uid);
160 if (!S_ISREG(sbuf.st_mode)) {
161 syslog(LOG_DEBUG, "%s: %s is not a regular file",
166 if (!(cred_time = get_tgt_time(ccname))) {
167 syslog(LOG_DEBUG, "%s: %s is not a valid credcache.",
173 if (cred_time <= best_time) {
174 syslog(LOG_DEBUG, "%s: %s expires sooner than current "
175 "best.", __func__, ccname);
180 syslog(LOG_DEBUG, "%s: %s is valid ccache", __func__, ccname);
182 best_cache = SMB_STRNDUP(ccname, MAX_CCNAME_LEN);
183 best_time = cred_time;
192 * Prepares AP-REQ data for mechToken and gets session key
193 * Uses credentials from cache. It will not ask for password
194 * you should receive credentials for yuor name manually using
195 * kinit or whatever you wish.
198 * oid - string with OID/ Could be OID_KERBEROS5
199 * or OID_KERBEROS5_OLD
200 * principal - Service name.
201 * Could be "cifs/FQDN" for KRB5 OID
202 * or for MS_KRB5 OID style server principal
203 * like "pdc$@YOUR.REALM.NAME"
206 * secblob - pointer for spnego wrapped AP-REQ data to be stored
207 * sess_key- pointer for SessionKey data to be stored
209 * ret: 0 - success, others - failure
212 handle_krb5_mech(const char *oid, const char *principal, DATA_BLOB *secblob,
213 DATA_BLOB *sess_key, const char *ccname)
216 DATA_BLOB tkt, tkt_wrapped;
218 syslog(LOG_DEBUG, "%s: getting service ticket for %s", __func__,
221 /* get a kerberos ticket for the service and extract the session key */
222 retval = cli_krb5_get_ticket(principal, 0, &tkt, sess_key, 0, ccname,
226 syslog(LOG_DEBUG, "%s: failed to obtain service ticket (%d)",
231 syslog(LOG_DEBUG, "%s: obtained service ticket", __func__);
233 /* wrap that up in a nice GSS-API wrapping */
234 tkt_wrapped = spnego_gen_krb5_wrap(tkt, TOK_ID_KRB_AP_REQ);
236 /* and wrap that in a shiny SPNEGO wrapper */
237 *secblob = gen_negTokenInit(oid, tkt_wrapped);
239 data_blob_free(&tkt_wrapped);
240 data_blob_free(&tkt);
244 #define DKD_HAVE_HOSTNAME 0x1
245 #define DKD_HAVE_VERSION 0x2
246 #define DKD_HAVE_SEC 0x4
247 #define DKD_HAVE_IP 0x8
248 #define DKD_HAVE_UID 0x10
249 #define DKD_HAVE_PID 0x20
250 #define DKD_MUSTHAVE_SET (DKD_HAVE_HOSTNAME|DKD_HAVE_VERSION|DKD_HAVE_SEC)
252 struct decoded_args {
262 decode_key_description(const char *desc, struct decoded_args *arg)
267 const char *tkn = desc;
270 pos = index(tkn, ';');
271 if (strncmp(tkn, "host=", 5) == 0) {
279 SAFE_FREE(arg->hostname);
280 arg->hostname = SMB_XMALLOC_ARRAY(char, len);
281 strlcpy(arg->hostname, tkn + 5, len);
282 retval |= DKD_HAVE_HOSTNAME;
283 } else if (!strncmp(tkn, "ip4=", 4) ||
284 !strncmp(tkn, "ip6=", 4)) {
292 arg->ip = SMB_XMALLOC_ARRAY(char, len);
293 strlcpy(arg->ip, tkn + 4, len);
294 retval |= DKD_HAVE_IP;
295 } else if (strncmp(tkn, "pid=", 4) == 0) {
297 arg->pid = strtol(tkn + 4, NULL, 0);
299 syslog(LOG_ERR, "Invalid pid format: %s",
303 retval |= DKD_HAVE_PID;
305 } else if (strncmp(tkn, "sec=", 4) == 0) {
306 if (strncmp(tkn + 4, "krb5", 4) == 0) {
307 retval |= DKD_HAVE_SEC;
309 } else if (strncmp(tkn + 4, "mskrb5", 6) == 0) {
310 retval |= DKD_HAVE_SEC;
313 } else if (strncmp(tkn, "uid=", 4) == 0) {
315 arg->uid = strtol(tkn + 4, NULL, 16);
317 syslog(LOG_ERR, "Invalid uid format: %s",
321 retval |= DKD_HAVE_UID;
323 } else if (strncmp(tkn, "ver=", 4) == 0) { /* if version */
325 arg->ver = strtol(tkn + 4, NULL, 16);
327 syslog(LOG_ERR, "Invalid version format: %s",
331 retval |= DKD_HAVE_VERSION;
342 cifs_resolver(const key_serial_t key, const char *key_descr)
345 struct addrinfo *addr;
346 char ip[INET6_ADDRSTRLEN];
348 const char *keyend = key_descr;
349 /* skip next 4 ';' delimiters to get to description */
350 for (c = 1; c <= 4; c++) {
351 keyend = index(keyend+1, ';');
353 syslog(LOG_ERR, "invalid key description: %s",
360 /* resolve name to ip */
361 c = getaddrinfo(keyend, NULL, NULL, &addr);
363 syslog(LOG_ERR, "unable to resolve hostname: %s [%s]",
364 keyend, gai_strerror(c));
368 /* conver ip to string form */
369 if (addr->ai_family == AF_INET)
370 p = &(((struct sockaddr_in *)addr->ai_addr)->sin_addr);
372 p = &(((struct sockaddr_in6 *)addr->ai_addr)->sin6_addr);
374 if (!inet_ntop(addr->ai_family, p, ip, sizeof(ip))) {
375 syslog(LOG_ERR, "%s: inet_ntop: %s", __func__, strerror(errno));
381 c = keyctl_instantiate(key, ip, strlen(ip)+1, 0);
383 syslog(LOG_ERR, "%s: keyctl_instantiate: %s", __func__,
394 * Older kernels sent IPv6 addresses without colons. Well, at least
395 * they're fixed-length strings. Convert these addresses to have colon
396 * delimiters to make getaddrinfo happy.
399 convert_inet6_addr(const char *from, char *to)
405 if (!(i++ % 4) && *from)
412 ip_to_fqdn(const char *addrstr, char *host, size_t hostlen)
415 struct addrinfo hints = { .ai_flags = AI_NUMERICHOST };
416 struct addrinfo *res;
417 const char *ipaddr = addrstr;
418 char converted[INET6_ADDRSTRLEN + 1];
420 if ((strlen(ipaddr) > INET_ADDRSTRLEN) && !strchr(ipaddr, ':')) {
421 convert_inet6_addr(ipaddr, converted);
425 rc = getaddrinfo(ipaddr, NULL, &hints, &res);
427 syslog(LOG_DEBUG, "%s: failed to resolve %s to "
428 "ipaddr: %s", __func__, ipaddr,
429 rc == EAI_SYSTEM ? strerror(errno) : gai_strerror(rc));
433 rc = getnameinfo(res->ai_addr, res->ai_addrlen, host, hostlen,
434 NULL, 0, NI_NAMEREQD);
437 syslog(LOG_DEBUG, "%s: failed to resolve %s to fqdn: %s",
439 rc == EAI_SYSTEM ? strerror(errno) : gai_strerror(rc));
443 syslog(LOG_DEBUG, "%s: resolved %s to %s", __func__, ipaddr, host);
450 syslog(LOG_INFO, "Usage: %s [-t] [-v] key_serial", prog);
451 fprintf(stderr, "Usage: %s [-t] [-v] key_serial\n", prog);
454 const struct option long_options[] = {
455 { "trust-dns", 0, NULL, 't' },
456 { "version", 0, NULL, 'v' },
460 int main(const int argc, char *const argv[])
462 struct cifs_spnego_msg *keydata = NULL;
463 DATA_BLOB secblob = data_blob_null;
464 DATA_BLOB sess_key = data_blob_null;
465 key_serial_t key = 0;
470 char *buf, *princ = NULL, *ccname = NULL;
471 char hostbuf[NI_MAXHOST], *host;
472 struct decoded_args arg = { };
477 openlog(prog, 0, LOG_DAEMON);
479 while ((c = getopt_long(argc, argv, "ctv", long_options, NULL)) != -1) {
482 /* legacy option -- skip it */
488 printf("version: %s\n", CIFSSPNEGO_VERSION);
491 syslog(LOG_ERR, "unknown option: %c", c);
496 /* is there a key? */
497 if (argc <= optind) {
502 /* get key and keyring values */
504 key = strtol(argv[optind], NULL, 10);
507 syslog(LOG_ERR, "Invalid key format: %s", strerror(errno));
511 rc = keyctl_describe_alloc(key, &buf);
513 syslog(LOG_ERR, "keyctl_describe_alloc failed: %s",
519 syslog(LOG_DEBUG, "key description: %s", buf);
521 if ((strncmp(buf, "cifs.resolver", sizeof("cifs.resolver")-1) == 0) ||
522 (strncmp(buf, "dns_resolver", sizeof("dns_resolver")-1) == 0)) {
523 rc = cifs_resolver(key, buf);
527 have = decode_key_description(buf, &arg);
529 if ((have & DKD_MUSTHAVE_SET) != DKD_MUSTHAVE_SET) {
530 syslog(LOG_ERR, "unable to get necessary params from key "
531 "description (0x%x)", have);
536 if (arg.ver > CIFS_SPNEGO_UPCALL_VERSION) {
537 syslog(LOG_ERR, "incompatible kernel upcall version: 0x%x",
543 if (have & DKD_HAVE_UID) {
544 rc = setuid(arg.uid);
546 syslog(LOG_ERR, "setuid: %s", strerror(errno));
550 ccname = find_krb5_cc(CIFS_DEFAULT_KRB5_DIR, arg.uid);
555 // do mech specific authorization
560 /* for "cifs/" service name + terminating 0 */
561 datalen = strlen(host) + 5 + 1;
562 princ = SMB_XMALLOC_ARRAY(char, datalen);
568 if (arg.sec == MS_KRB5)
569 oid = OID_KERBEROS5_OLD;
574 * try getting a cifs/ principal first and then fall back to
575 * getting a host/ principal if that doesn't work.
577 strlcpy(princ, "cifs/", datalen);
578 strlcpy(princ + 5, host, datalen - 5);
579 rc = handle_krb5_mech(oid, princ, &secblob, &sess_key, ccname);
583 memcpy(princ, "host/", 5);
584 rc = handle_krb5_mech(oid, princ, &secblob, &sess_key, ccname);
588 if (!try_dns || !(have & DKD_HAVE_IP))
591 rc = ip_to_fqdn(arg.ip, hostbuf, sizeof(hostbuf));
598 goto retry_new_hostname;
600 syslog(LOG_ERR, "sectype: %d is not implemented", arg.sec);
610 /* pack SecurityBLob and SessionKey into downcall packet */
612 sizeof(struct cifs_spnego_msg) + secblob.length + sess_key.length;
613 keydata = (struct cifs_spnego_msg*)SMB_XMALLOC_ARRAY(char, datalen);
618 keydata->version = arg.ver;
620 keydata->sesskey_len = sess_key.length;
621 keydata->secblob_len = secblob.length;
622 memcpy(&(keydata->data), sess_key.data, sess_key.length);
623 memcpy(&(keydata->data) + keydata->sesskey_len,
624 secblob.data, secblob.length);
627 rc = keyctl_instantiate(key, keydata, datalen, 0);
629 syslog(LOG_ERR, "keyctl_instantiate: %s", strerror(errno));
633 /* BB: maybe we need use timeout for key: for example no more then
634 * ticket lifietime? */
635 /* keyctl_set_timeout( key, 60); */
638 * on error, negatively instantiate the key ourselves so that we can
639 * make sure the kernel doesn't hang it off of a searchable keyring
640 * and interfere with the next attempt to instantiate the key.
642 if (rc != 0 && key == 0)
643 keyctl_negate(key, 1, KEY_REQKEY_DEFL_DEFAULT);
644 data_blob_free(&secblob);
645 data_blob_free(&sess_key);
647 SAFE_FREE(arg.hostname);