[linux-cifs-client] [PATCH 2/2] try#2 cifs.spnego helper in samba:
helper source code
Q (Igor Mammedov)
qwerty0987654321 at mail.ru
Thu Nov 15 18:33:52 GMT 2007
Signed-off-by: Igor Mammedov <niallain at gmail.com>
---
source/client/cifs.spnego.c | 302
+++++++++++++++++++++++++++++++++++++++++++
source/client/cifs_spnego.h | 46 +++++++
2 files changed, 348 insertions(+), 0 deletions(-)
create mode 100644 source/client/cifs.spnego.c
create mode 100644 source/client/cifs_spnego.h
diff --git a/source/client/cifs.spnego.c b/source/client/cifs.spnego.c
new file mode 100644
index 0000000..d70cb3f
--- /dev/null
+++ b/source/client/cifs.spnego.c
@@ -0,0 +1,302 @@
+
+/*
+* CIFS SPNEGO user-space helper. Used by /sbin/request-key for handling
+* cifs upcall for kerberos authorization of access to share.
+* You should have keyutils installed and add following line to
+* /etc/request-key.conf file
+
+create cifs.spnego * * /usr/local/sbin/cifs.spnego [-c] %k
+
+*
+* Author(s): Igor Mammedov (niallain at gmail.com)
+*
+* This program is free software; you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation; either version 2 of the License, or
+* (at your option) any later version.
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU General Public License for more details.
+* You should have received a copy of the GNU General Public License
+* along with this program; if not, write to the Free Software
+* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include "includes.h"
+#include <keyutils.h>
+
+#include "cifs_spnego.h"
+
+static const char *prog = "cifs.spnego";
+typedef enum _secType {
+ KRB5,
+ MS_KRB5
+} secType_t;
+
+/*
+ * Prepares AP-REQ data for mechToken and gets session key
+ * Uses credentials from cache. It will not ask for password
+ * you should receive credentials for yuor name manually using
+ * kinit or whatever you wish.
+ *
+ * in:
+ * oid - string with OID/ Could be OID_KERBEROS5
+ * or OID_KERBEROS5_OLD
+ * principal - Service name.
+ * Could be "cifs/FQDN" for KRB5 OID
+ * or for MS_KRB5 OID style server principal
+ * like "pdc$@YOUR.REALM.NAME"
+ *
+ * out:
+ * secblob - pointer for spnego wrapped AP-REQ data to be stored
+ * sess_key- pointer for SessionKey data to be stored
+ *
+ * ret: 0 - success, others - failure
+*/
+int handle_krb5_mech(const char *oid, const char *principal,
+ DATA_BLOB * secblob, DATA_BLOB * sess_key)
+{
+ int retval;
+ DATA_BLOB tkt, tkt_wrapped;
+ const char *krb_mechs[] = { OID_KERBEROS5, NULL };
+
+ /* get a kerberos ticket for the service and extract the session key */
+ retval = cli_krb5_get_ticket(principal, 0,
+ &tkt, sess_key, 0, NULL, NULL);
+
+ if (retval)
+ return retval;
+
+ /* wrap that up in a nice GSS-API wrapping */
+ tkt_wrapped = spnego_gen_krb5_wrap(tkt, TOK_ID_KRB_AP_REQ);
+
+ /* and wrap that in a shiny SPNEGO wrapper */
+ *secblob = gen_negTokenInit(OID_KERBEROS5, tkt_wrapped);
+
+ data_blob_free(&tkt_wrapped);
+ data_blob_free(&tkt);
+ return retval;
+}
+
+#define DKD_HAVE_HOSTNAME 1
+#define DKD_HAVE_VERSION 2
+#define DKD_HAVE_SEC 4
+#define DKD_HAVE_IPV4 8
+#define DKD_HAVE_IPV6 16
+#define DKD_HAVE_UID 32
+#define DKD_MUSTHAVE_SET (DKD_HAVE_HOSTNAME|DKD_HAVE_VERSION|DKD_HAVE_SEC)
+
+int decode_key_description(const char *desc, int *ver, secType_t * sec,
+ char **hostname, uid_t * uid)
+{
+ int retval = 0;
+ char *pos;
+ const char *tkn = desc;
+ int skip;
+
+ do {
+ pos = index(tkn, ';');
+ if (strncmp(tkn, "host=", 5) == 0) {
+ int len;
+
+ if (pos == NULL) {
+ len = strlen(tkn);
+ } else {
+ len = pos - tkn;
+ }
+ len -= 5;
+ if (*hostname)
+ free(*hostname);
+ *hostname = malloc(len + 1);
+ strncpy(*hostname, tkn + 5, len);
+ (*hostname)[len] = '\0';
+ retval |= DKD_HAVE_HOSTNAME;
+ } else if (strncmp(tkn, "ipv4=", 5) == 0) {
+ /* BB: do we need it if we have hostname already? */
+ } else if (strncmp(tkn, "ipv6=", 5) == 0) {
+ /* BB: do we need it if we have hostname already? */
+ } else if (strncmp(tkn, "sec=", 4) == 0) {
+ if (strncmp(tkn + 4, "krb5", 4) == 0) {
+ retval |= DKD_HAVE_SEC;
+ *sec = KRB5;
+ }
+ } else if (strncmp(tkn, "uid=", 4) == 0) {
+ errno = 0;
+ *uid = strtol(tkn + 4, NULL, 16);
+ if (errno != 0) {
+ syslog(LOG_WARNING, "Invalid uid format: %s",
+ strerror(errno));
+ return 1;
+ } else {
+ retval |= DKD_HAVE_UID;
+ }
+ } else if (strncmp(tkn, "ver=", 4) == 0) { /* if version */
+ errno = 0;
+ *ver = strtol(tkn + 4, NULL, 16);
+ if (errno != 0) {
+ syslog(LOG_WARNING,
+ "Invalid version format: %s",
+ strerror(errno));
+ return 1;
+ } else {
+ retval |= DKD_HAVE_VERSION;
+ }
+ }
+ if (pos == NULL)
+ break;
+ tkn = pos + 1;
+ } while (tkn);
+ return retval;
+}
+
+int main(const int argc, char *const argv[])
+{
+ struct cifs_spnego_msg *keydata;
+ DATA_BLOB secblob = data_blob_null;
+ DATA_BLOB sess_key = data_blob_null;
+ secType_t sectype;
+ key_serial_t key;
+ size_t datalen;
+ long rc = 1;
+ uid_t uid;
+ int kernel_upcall_version;
+ int c, use_cifs_service_prefix = 0;
+ char *buf, *hostname = NULL;
+
+ openlog(prog, 0, LOG_DAEMON);
+ if (argc < 1) {
+ syslog(LOG_WARNING, "Usage: %s [-c] key_serial", prog);
+ goto out;
+ }
+
+ while ((c = getopt(argc, argv, "c")) != -1) {
+ switch (c) {
+ case 'c':{
+ use_cifs_service_prefix = 1;
+ break;
+ }
+ default:{
+ syslog(LOG_WARNING, "unknow option: %c", c);
+ goto out;
+ }
+ }
+ }
+ /* get key and keyring values */
+ errno = 0;
+ key = strtol(argv[optind], NULL, 10);
+ if (errno != 0) {
+ syslog(LOG_WARNING, "Invalid key format: %s", strerror(errno));
+ goto out;
+ }
+
+ rc = keyctl_describe_alloc(key, &buf);
+ if (rc == -1) {
+ syslog(LOG_WARNING, "keyctl_describe_alloc failed: %s",
+ strerror(errno));
+ rc = 1;
+ goto out;
+ }
+
+ rc = decode_key_description(buf, &kernel_upcall_version, §ype,
+ &hostname, &uid);
+ if ((rc & DKD_MUSTHAVE_SET) != DKD_MUSTHAVE_SET) {
+ syslog(LOG_WARNING,
+ "unable to get from description necessary params");
+ rc = 1;
+ free(buf);
+ goto out;
+ }
+ free(buf);
+
+ if (kernel_upcall_version != CIFS_SPNEGO_UPCALL_VERSION) {
+ syslog(LOG_WARNING,
+ "incompatible kernel upcall version: 0x%x",
+ kernel_upcall_version);
+ rc = 1;
+ goto out;
+ }
+
+ if (rc & DKD_HAVE_UID) {
+ rc = setuid(uid);
+ if (rc == -1) {
+ syslog(LOG_WARNING, "setuid: %s", strerror(errno));
+ goto out;
+ }
+ }
+
+ /* BB: someday upcall SPNEGO blob could be checked here to decide
+ * what mech to use */
+
+ // do mech specific authorization
+ switch (sectype) {
+ case KRB5:{
+ char *princ;
+ size_t len;
+
+ /* for "cifs/" service name + terminating 0 */
+ len = strlen(hostname) + 6;
+ princ = malloc(len);
+ if (!princ) {
+ rc = 1;
+ break;
+ }
+ if (use_cifs_service_prefix) {
+ strncpy(princ, "cifs/", len);
+ } else {
+ strncpy(princ, "host/", len);
+ }
+ strncpy(princ + 5, hostname, len - 5);
+
+ rc = handle_krb5_mech(OID_KERBEROS5, princ,
+ &secblob, &sess_key);
+ free(princ);
+ break;
+ }
+ default:{
+ syslog(LOG_WARNING, "sectype: %d is not implemented",
+ sectype);
+ rc = 1;
+ break;
+ }
+ }
+
+ if (rc) {
+ goto out;
+ }
+
+ /* pack SecurityBLob and SessionKey into downcall packet */
+ datalen =
+ sizeof(struct cifs_spnego_msg) + secblob.length + sess_key.length;
+ keydata = malloc(datalen);
+ if (!keydata) {
+ rc = 1;
+ goto out;
+ }
+ keydata->version = CIFS_SPNEGO_UPCALL_VERSION;
+ keydata->flags = 0;
+ keydata->sesskey_len = sess_key.length;
+ keydata->secblob_len = secblob.length;
+ memcpy(&(keydata->data), sess_key.data, sess_key.length);
+ memcpy(&(keydata->data) + keydata->sesskey_len,
+ secblob.data, secblob.length);
+
+ /* setup key */
+ rc = keyctl_instantiate(key, keydata, datalen, 0);
+ if (rc == -1) {
+ syslog(LOG_WARNING, "keyctl_instantiate: %s", strerror(errno));
+ goto out;
+ }
+
+ /* BB: maybe we need use timeout for key: for example no more then
+ * ticket lifietime? */
+ /* keyctl_set_timeout( key, 60); */
+ out:
+ data_blob_free(&secblob);
+ data_blob_free(&sess_key);
+ if (hostname)
+ free(hostname);
+ if (keydata)
+ free(keydata);
+ return rc;
+}
diff --git a/source/client/cifs_spnego.h b/source/client/cifs_spnego.h
new file mode 100644
index 0000000..13909dd
--- /dev/null
+++ b/source/client/cifs_spnego.h
@@ -0,0 +1,46 @@
+/*
+ * fs/cifs/cifs_spnego.h -- SPNEGO upcall management for CIFS
+ *
+ * Copyright (c) 2007 Red Hat, Inc.
+ * Author(s): Jeff Layton (jlayton at redhat.com)
+ * Steve French (sfrench at us.ibm.com)
+ *
+ * This library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
published
+ * by the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
License
+ * along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA
+ */
+
+#ifndef _CIFS_SPNEGO_H
+#define _CIFS_SPNEGO_H
+
+#define CIFS_SPNEGO_UPCALL_VERSION 1
+
+/*
+ * The version field should always be set to CIFS_SPNEGO_UPCALL_VERSION.
+ * The flags field is for future use. The request-key callout should set
+ * sesskey_len and secblob_len, and then concatenate the SessKey+SecBlob
+ * and stuff it in the data field.
+ */
+struct cifs_spnego_msg {
+ uint32_t version;
+ uint32_t flags;
+ uint32_t sesskey_len;
+ uint32_t secblob_len;
+ uint8_t data[1];
+};
+
+#ifdef __KERNEL__
+extern struct key_type cifs_spnego_key_type;
+#endif /* KERNEL */
+
+#endif /* _CIFS_SPNEGO_H */
-- 1.5.2.1
------------------------
Best regards,
-------------------------
Igor Mammedov,
niallain "at" gmail.com
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