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
31 #include "cifs_spnego.h"
33 const char *CIFSSPNEGO_VERSION = "1.3";
34 static const char *prog = "cifs.upcall";
35 typedef enum _sectype {
42 * given a process ID, get the value of the KRB5CCNAME environment variable
43 * in the context of that process. On error, just return NULL.
46 get_krb5_ccname(pid_t pid)
52 * FIXME: sysconf for ARG_MAX instead? Kernel seems to be limited to a
53 * page however, so it may not matter.
56 char *p, *value = NULL;
59 snprintf(buf, 4095, "/proc/%d/environ", pid);
60 fd = open(buf, O_RDONLY);
62 syslog(LOG_DEBUG, "%s: unable to open %s: %d", __func__, buf,
67 /* FIXME: don't assume that we get it all in the first read? */
68 len = read(fd, buf, 4096);
71 syslog(LOG_DEBUG, "%s: unable to read from /proc/%d/environ: "
72 "%d", __func__, pid, errno);
79 /* can't have valid KRB5CCNAME if there are < 13 bytes left */
81 if (strncmp("KRB5CCNAME=", p, 11)) {
82 p += strnlen(p, left);
89 value = SMB_STRNDUP(p, left);
92 syslog(LOG_DEBUG, "%s: KRB5CCNAME=%s", __func__,
93 value ? value : "(null)");
98 * Prepares AP-REQ data for mechToken and gets session key
99 * Uses credentials from cache. It will not ask for password
100 * you should receive credentials for yuor name manually using
101 * kinit or whatever you wish.
104 * oid - string with OID/ Could be OID_KERBEROS5
105 * or OID_KERBEROS5_OLD
106 * principal - Service name.
107 * Could be "cifs/FQDN" for KRB5 OID
108 * or for MS_KRB5 OID style server principal
109 * like "pdc$@YOUR.REALM.NAME"
112 * secblob - pointer for spnego wrapped AP-REQ data to be stored
113 * sess_key- pointer for SessionKey data to be stored
115 * ret: 0 - success, others - failure
118 handle_krb5_mech(const char *oid, const char *principal, DATA_BLOB *secblob,
119 DATA_BLOB *sess_key, const char *ccname)
122 DATA_BLOB tkt, tkt_wrapped;
124 syslog(LOG_DEBUG, "%s: getting service ticket for %s", __func__,
127 /* get a kerberos ticket for the service and extract the session key */
128 retval = cli_krb5_get_ticket(principal, 0, &tkt, sess_key, 0, ccname,
132 syslog(LOG_DEBUG, "%s: failed to obtain service ticket (%d)",
137 syslog(LOG_DEBUG, "%s: obtained service ticket", __func__);
139 /* wrap that up in a nice GSS-API wrapping */
140 tkt_wrapped = spnego_gen_krb5_wrap(tkt, TOK_ID_KRB_AP_REQ);
142 /* and wrap that in a shiny SPNEGO wrapper */
143 *secblob = gen_negTokenInit(oid, tkt_wrapped);
145 data_blob_free(&tkt_wrapped);
146 data_blob_free(&tkt);
150 #define DKD_HAVE_HOSTNAME 0x1
151 #define DKD_HAVE_VERSION 0x2
152 #define DKD_HAVE_SEC 0x4
153 #define DKD_HAVE_IPV4 0x8
154 #define DKD_HAVE_IPV6 0x10
155 #define DKD_HAVE_UID 0x20
156 #define DKD_HAVE_PID 0x40
157 #define DKD_MUSTHAVE_SET (DKD_HAVE_HOSTNAME|DKD_HAVE_VERSION|DKD_HAVE_SEC)
159 static struct decoded_args {
168 decode_key_description(const char *desc, struct decoded_args *arg)
172 const char *tkn = desc;
175 pos = index(tkn, ';');
176 if (strncmp(tkn, "host=", 5) == 0) {
185 SAFE_FREE(arg->hostname);
186 arg->hostname = SMB_XMALLOC_ARRAY(char, len);
187 strlcpy(arg->hostname, tkn + 5, len);
188 retval |= DKD_HAVE_HOSTNAME;
189 } else if (strncmp(tkn, "ipv4=", 5) == 0) {
190 /* BB: do we need it if we have hostname already? */
191 } else if (strncmp(tkn, "ipv6=", 5) == 0) {
192 /* BB: do we need it if we have hostname already? */
193 } else if (strncmp(tkn, "pid=", 4) == 0) {
195 arg->pid = strtol(tkn + 4, NULL, 0);
197 syslog(LOG_ERR, "Invalid pid format: %s",
201 retval |= DKD_HAVE_PID;
203 } else if (strncmp(tkn, "sec=", 4) == 0) {
204 if (strncmp(tkn + 4, "krb5", 4) == 0) {
205 retval |= DKD_HAVE_SEC;
207 } else if (strncmp(tkn + 4, "mskrb5", 6) == 0) {
208 retval |= DKD_HAVE_SEC;
211 } else if (strncmp(tkn, "uid=", 4) == 0) {
213 arg->uid = strtol(tkn + 4, NULL, 16);
215 syslog(LOG_ERR, "Invalid uid format: %s",
219 retval |= DKD_HAVE_UID;
221 } else if (strncmp(tkn, "ver=", 4) == 0) { /* if version */
223 arg->ver = strtol(tkn + 4, NULL, 16);
225 syslog(LOG_ERR, "Invalid version format: %s",
229 retval |= DKD_HAVE_VERSION;
240 cifs_resolver(const key_serial_t key, const char *key_descr)
243 struct addrinfo *addr;
244 char ip[INET6_ADDRSTRLEN];
246 const char *keyend = key_descr;
247 /* skip next 4 ';' delimiters to get to description */
248 for (c = 1; c <= 4; c++) {
249 keyend = index(keyend+1, ';');
251 syslog(LOG_ERR, "invalid key description: %s",
258 /* resolve name to ip */
259 c = getaddrinfo(keyend, NULL, NULL, &addr);
261 syslog(LOG_ERR, "unable to resolve hostname: %s [%s]",
262 keyend, gai_strerror(c));
266 /* conver ip to string form */
267 if (addr->ai_family == AF_INET)
268 p = &(((struct sockaddr_in *)addr->ai_addr)->sin_addr);
270 p = &(((struct sockaddr_in6 *)addr->ai_addr)->sin6_addr);
272 if (!inet_ntop(addr->ai_family, p, ip, sizeof(ip))) {
273 syslog(LOG_ERR, "%s: inet_ntop: %s", __func__, strerror(errno));
279 c = keyctl_instantiate(key, ip, strlen(ip)+1, 0);
281 syslog(LOG_ERR, "%s: keyctl_instantiate: %s", __func__,
294 syslog(LOG_INFO, "Usage: %s [-v] key_serial", prog);
295 fprintf(stderr, "Usage: %s [-v] key_serial\n", prog);
298 int main(const int argc, char *const argv[])
300 struct cifs_spnego_msg *keydata = NULL;
301 DATA_BLOB secblob = data_blob_null;
302 DATA_BLOB sess_key = data_blob_null;
303 key_serial_t key = 0;
308 char *buf, *princ, *ccname = NULL;
309 struct decoded_args arg = { };
312 openlog(prog, 0, LOG_DAEMON);
314 while ((c = getopt(argc, argv, "cv")) != -1) {
317 /* legacy option -- skip it */
320 printf("version: %s\n", CIFSSPNEGO_VERSION);
323 syslog(LOG_ERR, "unknown option: %c", c);
328 /* is there a key? */
329 if (argc <= optind) {
334 /* get key and keyring values */
336 key = strtol(argv[optind], NULL, 10);
339 syslog(LOG_ERR, "Invalid key format: %s", strerror(errno));
343 rc = keyctl_describe_alloc(key, &buf);
345 syslog(LOG_ERR, "keyctl_describe_alloc failed: %s",
351 syslog(LOG_DEBUG, "key description: %s", buf);
353 if ((strncmp(buf, "cifs.resolver", sizeof("cifs.resolver")-1) == 0) ||
354 (strncmp(buf, "dns_resolver", sizeof("dns_resolver")-1) == 0)) {
355 rc = cifs_resolver(key, buf);
359 have = decode_key_description(buf, &arg);
361 if ((have & DKD_MUSTHAVE_SET) != DKD_MUSTHAVE_SET) {
362 syslog(LOG_ERR, "unable to get necessary params from key "
363 "description (0x%x)", have);
368 if (arg.ver > CIFS_SPNEGO_UPCALL_VERSION) {
369 syslog(LOG_ERR, "incompatible kernel upcall version: 0x%x",
375 if (have & DKD_HAVE_UID) {
376 rc = setuid(arg.uid);
378 syslog(LOG_ERR, "setuid: %s", strerror(errno));
383 if (have & DKD_HAVE_PID)
384 ccname = get_krb5_ccname(arg.pid);
386 // do mech specific authorization
390 /* for "cifs/" service name + terminating 0 */
391 datalen = strlen(arg.hostname) + 5 + 1;
392 princ = SMB_XMALLOC_ARRAY(char, datalen);
398 if (arg.sec == MS_KRB5)
399 oid = OID_KERBEROS5_OLD;
404 * try getting a cifs/ principal first and then fall back to
405 * getting a host/ principal if that doesn't work.
407 strlcpy(princ, "cifs/", datalen);
408 strlcpy(princ + 5, arg.hostname, datalen - 5);
409 rc = handle_krb5_mech(oid, princ, &secblob, &sess_key, ccname);
411 memcpy(princ, "host/", 5);
412 rc = handle_krb5_mech(oid, princ, &secblob, &sess_key,
418 syslog(LOG_ERR, "sectype: %d is not implemented", arg.sec);
426 /* pack SecurityBLob and SessionKey into downcall packet */
428 sizeof(struct cifs_spnego_msg) + secblob.length + sess_key.length;
429 keydata = (struct cifs_spnego_msg*)SMB_XMALLOC_ARRAY(char, datalen);
434 keydata->version = arg.ver;
436 keydata->sesskey_len = sess_key.length;
437 keydata->secblob_len = secblob.length;
438 memcpy(&(keydata->data), sess_key.data, sess_key.length);
439 memcpy(&(keydata->data) + keydata->sesskey_len,
440 secblob.data, secblob.length);
443 rc = keyctl_instantiate(key, keydata, datalen, 0);
445 syslog(LOG_ERR, "keyctl_instantiate: %s", strerror(errno));
449 /* BB: maybe we need use timeout for key: for example no more then
450 * ticket lifietime? */
451 /* keyctl_set_timeout( key, 60); */
454 * on error, negatively instantiate the key ourselves so that we can
455 * make sure the kernel doesn't hang it off of a searchable keyring
456 * and interfere with the next attempt to instantiate the key.
458 if (rc != 0 && key == 0)
459 keyctl_negate(key, 1, KEY_REQKEY_DEFL_DEFAULT);
460 data_blob_free(&secblob);
461 data_blob_free(&sess_key);
463 SAFE_FREE(arg.hostname);