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
);