text: /*
  * CIFS user-space helper.
  * Copyright (C) Igor Mammedov (niallain@gmail.com) 2007
  *
  * Used by /sbin/request-key for handling
  * cifs upcall for kerberos authorization of access to share and
  * cifs upcall for DFS srver name resolving (IPv4/IPv6 aware).
  * You should have keyutils installed and add something like the
  * following lines to /etc/request-key.conf file:
  
  create cifs.spnego * * /usr/local/sbin/cifs.upcall %k
  create dns_resolver * * /usr/local/sbin/cifs.upcall %k
  
  * 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"
  
  const char *CIFSSPNEGO_VERSION = "1.2";
  static const char *prog = "cifs.upcall";
  typedef enum _secType {
  	NONE = 0,
  	KRB5,
  	MS_KRB5
  } secType_t;
  const DATA_BLOB data_blob_null = { NULL, 0, NULL };
  
  /*
   * 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
  */
  static int
  handle_krb5_mech(const char *oid, const char *principal,
  		     DATA_BLOB * secblob, DATA_BLOB * sess_key)
  {
  	int retval;
  	DATA_BLOB tkt, tkt_wrapped;
  
  	/* 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, 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)
  
  static 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;
  
  	do {
  		pos = index(tkn, ';');
  		if (strncmp(tkn, "host=", 5) == 0) {
  			int len;
  
  			if (pos == NULL) {
  				len = strlen(tkn);
  			} else {
  				len = pos - tkn;
  			}
  			len -= 4;
  			SAFE_FREE(*hostname);
  			*hostname = SMB_XMALLOC_ARRAY(char, len);
  			strlcpy(*hostname, tkn + 5, len);
  			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 + 4, "mskrb5", 6) == 0) {
  				retval |= DKD_HAVE_SEC;
  				*sec = MS_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;
  }
  
  static int
  cifs_resolver(const key_serial_t key, const char *key_descr)
  {
  	int c;
  	struct addrinfo *addr;
  	char ip[INET6_ADDRSTRLEN];
  	void *p;
  	const char *keyend = key_descr;
  	/* skip next 4 ';' delimiters to get to description */
  	for (c = 1; c <= 4; c++) {
  		keyend = index(keyend+1, ';');
  		if (!keyend) {
  			syslog(LOG_WARNING, "invalid key description: %s",
  					key_descr);
  			return 1;
  		}
  	}
  	keyend++;
  
  	/* resolve name to ip */
  	c = getaddrinfo(keyend, NULL, NULL, &addr);
  	if (c) {
  		syslog(LOG_WARNING, "unable to resolve hostname: %s [%s]",
  				keyend, gai_strerror(c));
  		return 1;
  	}
  
  	/* conver ip to string form */
  	if (addr->ai_family == AF_INET) {
  		p = &(((struct sockaddr_in *)addr->ai_addr)->sin_addr);
  	} else {
  		p = &(((struct sockaddr_in6 *)addr->ai_addr)->sin6_addr);
  	}
  	if (!inet_ntop(addr->ai_family, p, ip, sizeof(ip))) {
  		syslog(LOG_WARNING, "%s: inet_ntop: %s",
  				__FUNCTION__, strerror(errno));
  		freeaddrinfo(addr);
  		return 1;
  	}
  
  	/* setup key */
  	c = keyctl_instantiate(key, ip, strlen(ip)+1, 0);
  	if (c == -1) {
  		syslog(LOG_WARNING, "%s: keyctl_instantiate: %s",
  				__FUNCTION__, strerror(errno));
  		freeaddrinfo(addr);
  		return 1;
  	}
  
  	freeaddrinfo(addr);
  	return 0;
  }
  
  static void
  usage(void)
  {
  	syslog(LOG_WARNING, "Usage: %s [-c] [-v] key_serial", prog);
  	fprintf(stderr, "Usage: %s [-c] [-v] key_serial\n", prog);
  }
  
  int main(const int argc, char *const argv[])
  {
  	struct cifs_spnego_msg *keydata = NULL;
  	DATA_BLOB secblob = data_blob_null;
  	DATA_BLOB sess_key = data_blob_null;
  	secType_t sectype = NONE;
  	key_serial_t key = 0;
  	size_t datalen;
  	long rc = 1;
  	uid_t uid = 0;
  	int kernel_upcall_version = 0;
  	int c, use_cifs_service_prefix = 0;
  	char *buf, *hostname = NULL;
  	const char *oid;
  
  	openlog(prog, 0, LOG_DAEMON);
  
  	while ((c = getopt(argc, argv, "cv")) != -1) {
  		switch (c) {
  		case 'c':{
  			use_cifs_service_prefix = 1;
  			break;
  			}
  		case 'v':{
  			printf("version: %s\n", CIFSSPNEGO_VERSION);
  			goto out;
  			}
  		default:{
  			syslog(LOG_WARNING, "unknown option: %c", c);
  			goto out;
  			}
  		}
  	}
  
  	/* is there a key? */
  	if (argc <= optind) {
  		usage();
  		goto out;
  	}
  
  	/* get key and keyring values */
  	errno = 0;
  	key = strtol(argv[optind], NULL, 10);
  	if (errno != 0) {
  		key = 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;
  	}
  
  	if ((strncmp(buf, "cifs.resolver", sizeof("cifs.resolver")-1) == 0) ||
  	    (strncmp(buf, "dns_resolver", sizeof("dns_resolver")-1) == 0)) {
  		rc = cifs_resolver(key, buf);
  		goto out;
  	}
  
  	rc = decode_key_description(buf, &kernel_upcall_version, &sectype,
  				    &hostname, &uid);
  	if ((rc & DKD_MUSTHAVE_SET) != DKD_MUSTHAVE_SET) {
  		syslog(LOG_WARNING,
  		       "unable to get from description necessary params");
  		rc = 1;
  		SAFE_FREE(buf);
  		goto out;
  	}
  	SAFE_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 MS_KRB5:
  	case KRB5:{
  			char *princ;
  			size_t len;
  
  			/* for "cifs/" service name + terminating 0 */
  			len = strlen(hostname) + 5 + 1;
  			princ = SMB_XMALLOC_ARRAY(char, len);
  			if (!princ) {
  				rc = 1;
  				break;
  			}
  			if (use_cifs_service_prefix) {
  				strlcpy(princ, "cifs/", len);
  			} else {
  				strlcpy(princ, "host/", len);
  			}
  			strlcpy(princ + 5, hostname, len - 5);
  
  			if (sectype == MS_KRB5)
  				oid = OID_KERBEROS5_OLD;
  			else
  				oid = OID_KERBEROS5;
  
  			rc = handle_krb5_mech(oid, princ, &secblob, &sess_key);
  			SAFE_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 = (struct cifs_spnego_msg*)SMB_XMALLOC_ARRAY(char, datalen);
  	if (!keydata) {
  		rc = 1;
  		goto out;
  	}
  	keydata->version = kernel_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:
  	/*
  	 * on error, negatively instantiate the key ourselves so that we can
  	 * make sure the kernel doesn't hang it off of a searchable keyring
  	 * and interfere with the next attempt to instantiate the key.
  	 */
  	if (rc != 0  && key == 0)
  		keyctl_negate(key, 1, KEY_REQKEY_DEFL_DEFAULT);
  	data_blob_free(&secblob);
  	data_blob_free(&sess_key);
  	SAFE_FREE(hostname);
  	SAFE_FREE(keydata);
  	return rc;
  }
  