/*

* CIFS user-space helper.

* Copyright (C) Igor Mammedov (niallain@gmail.com) 2007

* Copyright (C) Jeff Layton (jlayton@samba.org) 2010

*

* 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

*/

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif /* HAVE_CONFIG_H */

#include <string.h>

#include <getopt.h>

#ifdef HAVE_KRB5_KRB5_H

#include <krb5/krb5.h>

#elif defined(HAVE_KRB5_H)

#include <krb5.h>

#endif

#include <syslog.h>

#include <dirent.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <unistd.h>

#include <keyutils.h>

#include <time.h>

#include <netdb.h>

#include <arpa/inet.h>

#include <ctype.h>

#include <pwd.h>

#include <grp.h>

#include <stdbool.h>

#include <errno.h>

#include "data_blob.h"

#include "spnego.h"

#include "cifs_spnego.h"

#ifdef HAVE_LIBCAP_NG

#include <cap-ng.h>

#endif

static krb5_context	context;

static const char	*prog = "cifs.upcall";

typedef enum _sectype {

	NONE = 0,

	KRB5,

	MS_KRB5

} sectype_t;

/* These macros unify the keyblock handling of Heimdal and MIT somewhat */

#ifdef HAVE_KRB5_KEYBLOCK_KEYVALUE /* Heimdal */

#define KRB5_KEY_TYPE(k)        ((k)->keytype)

#define KRB5_KEY_LENGTH(k)      ((k)->keyvalue.length)

#define KRB5_KEY_DATA(k)        ((k)->keyvalue.data)

#define KRB5_KEY_DATA_CAST      void

#else /* MIT */

#define KRB5_KEY_TYPE(k)        ((k)->enctype)

#define KRB5_KEY_LENGTH(k)      ((k)->length)

#define KRB5_KEY_DATA(k)        ((k)->contents)

#define KRB5_KEY_DATA_CAST      krb5_octet

#endif

#ifdef HAVE_LIBCAP_NG

static int

trim_capabilities(bool need_environ)

{

	capng_clear(CAPNG_SELECT_BOTH);

	/* SETUID and SETGID to change uid, gid, and grouplist */

	if (capng_updatev(CAPNG_ADD, CAPNG_PERMITTED|CAPNG_EFFECTIVE,

			CAP_SETUID, CAP_SETGID, -1)) {

		syslog(LOG_ERR, "%s: Unable to update capability set: %m\n", __func__);

		return 1;

	}

	 /* Need PTRACE and READ_SEARCH for /proc/pid/environ scraping */

	if (need_environ &&

	    capng_updatev(CAPNG_ADD, CAPNG_PERMITTED|CAPNG_EFFECTIVE,

			CAP_SYS_PTRACE, CAP_DAC_READ_SEARCH, -1)) {

		syslog(LOG_ERR, "%s: Unable to update capability set: %m\n", __func__);

		return 1;

	}

	if (capng_apply(CAPNG_SELECT_BOTH)) {

		syslog(LOG_ERR, "%s: Unable to apply capability set: %m\n", __func__);

		return 1;

	}

	return 0;

}

static int

drop_all_capabilities(void)

{

	capng_clear(CAPNG_SELECT_BOTH);

	if (capng_apply(CAPNG_SELECT_BOTH)) {

		syslog(LOG_ERR, "%s: Unable to apply capability set: %m\n", __func__);

		return 1;

	}

	return 0;

}

#else /* HAVE_LIBCAP_NG */

static int

trim_capabilities(bool unused)

{

	return 0;

}

static int

drop_all_capabilities(void)

{

	return 0;

}

#endif /* HAVE_LIBCAP_NG */

/*

 * smb_krb5_principal_get_realm

 *

 * @brief Get realm of a principal

 *

 * @param[in] context		The krb5_context

 * @param[in] principal		The principal

 * @return pointer to the realm

 *

 */

static char *cifs_krb5_principal_get_realm(krb5_principal principal)

{

#ifdef HAVE_KRB5_PRINCIPAL_GET_REALM	/* Heimdal */

	return krb5_principal_get_realm(context, principal);

#elif defined(krb5_princ_realm)	/* MIT */

	krb5_data *realm;

	realm = krb5_princ_realm(context, principal);

	return (char *)realm->data;

#else

	return NULL;

#endif

}

#if !defined(HAVE_KRB5_FREE_UNPARSED_NAME)

static void krb5_free_unparsed_name(krb5_context context, char *val)

{

	free(val);

}

#endif

#if !defined(HAVE_KRB5_AUTH_CON_GETSENDSUBKEY)	/* Heimdal */

static krb5_error_code

krb5_auth_con_getsendsubkey(krb5_context context,

			    krb5_auth_context auth_context,

			    krb5_keyblock **keyblock)

{

	return krb5_auth_con_getlocalsubkey(context, auth_context, keyblock);

}

#endif

/* does the ccache have a valid TGT? */

static time_t get_tgt_time(krb5_ccache ccache)

{

	krb5_cc_cursor cur;

	krb5_creds creds;

	krb5_principal principal;

	time_t credtime = 0;

	char *realm = NULL;

	if (krb5_cc_set_flags(context, ccache, 0)) {

		syslog(LOG_DEBUG, "%s: unable to set flags", __func__);

		goto err_cache;

	}

	if (krb5_cc_get_principal(context, ccache, &principal)) {

		syslog(LOG_DEBUG, "%s: unable to get principal", __func__);

		goto err_cache;

	}

	if (krb5_cc_start_seq_get(context, ccache, &cur)) {

		syslog(LOG_DEBUG, "%s: unable to seq start", __func__);

		goto err_ccstart;

	}

	if ((realm = cifs_krb5_principal_get_realm(principal)) == NULL) {

		syslog(LOG_DEBUG, "%s: unable to get realm", __func__);

		goto err_ccstart;

	}

	while (!credtime && !krb5_cc_next_cred(context, ccache, &cur, &creds)) {

		char *name;

		if (krb5_unparse_name(context, creds.server, &name)) {

			syslog(LOG_DEBUG, "%s: unable to unparse name",

			       __func__);

			goto err_endseq;

		}

		if (krb5_realm_compare(context, creds.server, principal) &&

		    !strncasecmp(name, KRB5_TGS_NAME, KRB5_TGS_NAME_SIZE) &&

		    !strncasecmp(name + KRB5_TGS_NAME_SIZE + 1, realm,

				 strlen(realm))

		    && creds.times.endtime > time(NULL))

			credtime = creds.times.endtime;

		krb5_free_cred_contents(context, &creds);

		krb5_free_unparsed_name(context, name);

	}

err_endseq:

	krb5_cc_end_seq_get(context, ccache, &cur);

err_ccstart:

	krb5_free_principal(context, principal);

err_cache:

	return credtime;

}

#define	ENV_PATH_FMT			"/proc/%d/environ"

#define	ENV_PATH_MAXLEN			(6 + 10 + 8 + 1)

#define	ENV_NAME			"KRB5CCNAME"

#define	ENV_PREFIX			"KRB5CCNAME="

#define	ENV_PREFIX_LEN			11

#define	ENV_BUF_START			(4096)

#define	ENV_BUF_MAX			(131072)

/**

 * get_cachename_from_process_env - scrape value of $KRB5CCNAME out of the

 * 				    initiating process' environment.

 * @pid: initiating pid value from the upcall string

 *

 * Open the /proc/<pid>/environ file for the given pid, and scrape it for

 * KRB5CCNAME entries.

 *

 * We start with a page-size buffer, and then progressively double it until

 * we can slurp in the whole thing.

 *

 * Note that this is not entirely reliable. If the process is sitting in a

 * container or something, then this is almost certainly not going to point

 * where you expect.

 *

 * Probably it just won't work, but could a user use this to trick cifs.upcall

 * into reading a file outside the container, by setting KRB5CCNAME in a

 * crafty way?

 */

static char *

get_cachename_from_process_env(pid_t pid)

{

	int fd, ret;

	ssize_t buflen;

	ssize_t bufsize = ENV_BUF_START;

	char pathname[ENV_PATH_MAXLEN];

	char *cachename = NULL;

	char *buf = NULL, *pos;

	if (!pid) {

		syslog(LOG_DEBUG, "%s: pid == 0\n", __func__);

		return NULL;

	}

	pathname[ENV_PATH_MAXLEN - 1] = '\0';

	ret = snprintf(pathname, ENV_PATH_MAXLEN, ENV_PATH_FMT, pid);

	if (ret >= ENV_PATH_MAXLEN) {

		syslog(LOG_DEBUG, "%s: unterminated path!\n", __func__);

		return NULL;

	}

	syslog(LOG_DEBUG, "%s: pathname=%s\n", __func__, pathname);

	fd = open(pathname, O_RDONLY);

	if (fd < 0) {

		syslog(LOG_DEBUG, "%s: open failed: %d\n", __func__, errno);

		return NULL;

	}

retry:

	if (bufsize > ENV_BUF_MAX) {

		syslog(LOG_DEBUG, "%s: buffer too big: %zd\n",

							__func__, bufsize);

		goto out_close;

	}

	buf = malloc(bufsize);

	if (!buf) {

		syslog(LOG_DEBUG, "%s: malloc failure\n", __func__);

		goto out_close;

	}

	buflen = read(fd, buf, bufsize);

	if (buflen < 0) {

		syslog(LOG_DEBUG, "%s: read failed: %d\n", __func__, errno);

		goto out_close;

	}

	if (buflen >= bufsize) {

		/* We read to the end of the buffer. Double and try again */

		syslog(LOG_DEBUG, "%s: read to end of buffer (%zu bytes)\n",

					__func__, bufsize);

		free(buf);

		bufsize *= 2;

		if (lseek(fd, 0, SEEK_SET) < 0)

			goto out_close;

		goto retry;

	}

	pos = buf;

	while (buflen > 0) {

		size_t len = strnlen(pos, buflen);

		if (len > ENV_PREFIX_LEN &&

		    !memcmp(pos, ENV_PREFIX, ENV_PREFIX_LEN)) {

			cachename = strndup(pos + ENV_PREFIX_LEN,

							len - ENV_PREFIX_LEN);

			syslog(LOG_DEBUG, "%s: cachename = %s\n",

							__func__, cachename);

			break;

		}

		buflen -= (len + 1);

		pos += (len + 1);

	}

out_close:

	free(buf);

	close(fd);

	return cachename;

}

static krb5_ccache

get_existing_cc(const char *env_cachename)

{

	krb5_error_code ret;

	krb5_ccache cc;

	char *cachename;

	if (env_cachename) {

		if (setenv(ENV_NAME, env_cachename, 1))

			syslog(LOG_DEBUG, "%s: failed to setenv %d\n", __func__, errno);

	}

	ret = krb5_cc_default(context, &cc);

	if (ret) {

		syslog(LOG_DEBUG, "%s: krb5_cc_default returned %d", __func__, ret);

		return NULL;

	}

	ret = krb5_cc_get_full_name(context, cc, &cachename);

	if (ret) {

		syslog(LOG_DEBUG, "%s: krb5_cc_get_full_name failed: %d\n", __func__, ret);

	} else {

		syslog(LOG_DEBUG, "%s: default ccache is %s\n", __func__, cachename);

		krb5_free_string(context, cachename);

	}

	if (!get_tgt_time(cc)) {

		krb5_cc_close(context, cc);

		cc = NULL;

	}

	return cc;

}

static krb5_ccache

init_cc_from_keytab(const char *keytab_name, const char *user)

{

	krb5_error_code ret;

	krb5_creds my_creds;

	krb5_keytab keytab = NULL;

	krb5_principal me = NULL;

	krb5_ccache cc = NULL;

	memset((char *) &my_creds, 0, sizeof(my_creds));

	/*

	 * Unset the environment variable, if any. If we're creating our own

	 * credcache here, stick it in the default location.

	 */

	unsetenv(ENV_NAME);

	if (keytab_name)

		ret = krb5_kt_resolve(context, keytab_name, &keytab);

	else

		ret = krb5_kt_default(context, &keytab);

	if (ret) {

		syslog(LOG_DEBUG, "%s: %d",

			keytab_name ? "krb5_kt_resolve" : "krb5_kt_default",

			(int)ret);

		goto icfk_cleanup;

	}

	ret = krb5_parse_name(context, user, &me);

	if (ret) {

		syslog(LOG_DEBUG, "krb5_parse_name: %d", (int)ret);

		goto icfk_cleanup;

	}

	ret = krb5_get_init_creds_keytab(context, &my_creds, me,

			keytab, 0, NULL, NULL);

	if (ret) {

		syslog(LOG_DEBUG, "krb5_get_init_creds_keytab: %d", (int)ret);

		goto icfk_cleanup;

	}

	ret = krb5_cc_resolve(context, "MEMORY:", &cc);

	if (ret) {

		syslog(LOG_DEBUG, "krb5_cc_resolve: %d", (int)ret);

		goto icfk_cleanup;

	}

	ret = krb5_cc_initialize(context, cc, me);

	if (ret) {

		syslog(LOG_DEBUG, "krb5_cc_initialize: %d", (int)ret);

		goto icfk_cleanup;

	}

	ret = krb5_cc_store_cred(context, cc, &my_creds);

	if (ret) {

		syslog(LOG_DEBUG, "krb5_cc_store_cred: %d", (int)ret);

		goto icfk_cleanup;

	}

out:

	my_creds.client = (krb5_principal)0;

	krb5_free_cred_contents(context, &my_creds);

	if (me)

		krb5_free_principal(context, me);

	if (keytab)

		krb5_kt_close(context, keytab);

	return cc;

icfk_cleanup:

	if (cc) {

		krb5_cc_close(context, cc);

		cc = NULL;

	}

	goto out;

}

static int

cifs_krb5_get_req(const char *host, krb5_ccache ccache,

		  DATA_BLOB * mechtoken, DATA_BLOB * sess_key)

{

	krb5_error_code ret;

	krb5_keyblock *tokb;

	krb5_creds in_creds, *out_creds;

	krb5_data apreq_pkt, in_data;

	krb5_auth_context auth_context = NULL;

#if defined(HAVE_KRB5_AUTH_CON_SETADDRS) && defined(HAVE_KRB5_AUTH_CON_SET_REQ_CKSUMTYPE)

	static char gss_cksum[24] = { 0x10, 0x00, /* ... */};

#endif

	memset(&in_creds, 0, sizeof(in_creds));

	ret = krb5_cc_get_principal(context, ccache, &in_creds.client);

	if (ret) {

		syslog(LOG_DEBUG, "%s: unable to get client principal name",

		       __func__);

		return ret;

	}

	ret = krb5_sname_to_principal(context, host, "cifs", KRB5_NT_UNKNOWN,

					&in_creds.server);

	if (ret) {

		syslog(LOG_DEBUG, "%s: unable to convert sname to princ (%s).",

		       __func__, host);

		goto out_free_principal;

	}

	ret = krb5_get_credentials(context, 0, ccache, &in_creds, &out_creds);

	krb5_free_principal(context, in_creds.server);

	if (ret) {

		syslog(LOG_DEBUG, "%s: unable to get credentials for %s",

		       __func__, host);

		goto out_free_principal;

	}

	in_data.length = 0;

	in_data.data = NULL;

	ret = krb5_auth_con_init(context, &auth_context);

	if (ret) {

		syslog(LOG_DEBUG, "%s: unable to create auth_context: %d",

		       __func__, ret);

		goto out_free_creds;

	}

#if defined(HAVE_KRB5_AUTH_CON_SETADDRS) && defined(HAVE_KRB5_AUTH_CON_SET_REQ_CKSUMTYPE)

	/* Ensure we will get an addressless ticket. */

	ret = krb5_auth_con_setaddrs(context, auth_context, NULL, NULL);

	if (ret) {

		syslog(LOG_DEBUG, "%s: unable to set NULL addrs: %d",

		       __func__, ret);

		goto out_free_auth;

	}

	/*

	 * Create a GSSAPI checksum (0x8003), see RFC 4121.

	 *

	 * The current layout is

	 *

	 * 0x10, 0x00, 0x00, 0x00 - length = 16

	 * 0x00, 0x00, 0x00, 0x00 - channel binding info - 16 zero bytes

	 * 0x00, 0x00, 0x00, 0x00

	 * 0x00, 0x00, 0x00, 0x00

	 * 0x00, 0x00, 0x00, 0x00

	 * 0x00, 0x00, 0x00, 0x00 - flags

	 *

	 * GSS_C_NO_CHANNEL_BINDINGS means 16 zero bytes,

	 * this is needed to work against some closed source

	 * SMB servers.

	 *

	 * See https://bugzilla.samba.org/show_bug.cgi?id=7890

	 */

	in_data.data = gss_cksum;

	in_data.length = 24;

	/* MIT krb5 < 1.7 is missing the prototype, but still has the symbol */

#if !HAVE_DECL_KRB5_AUTH_CON_SET_REQ_CKSUMTYPE

	krb5_error_code krb5_auth_con_set_req_cksumtype(

		krb5_auth_context auth_context,

		krb5_cksumtype    cksumtype);

#endif

	ret = krb5_auth_con_set_req_cksumtype(context, auth_context, 0x8003);

	if (ret) {

		syslog(LOG_DEBUG, "%s: unable to set 0x8003 checksum",

		       __func__);

		goto out_free_auth;

	}

#endif

	apreq_pkt.length = 0;

	apreq_pkt.data = NULL;

	ret = krb5_mk_req_extended(context, &auth_context, AP_OPTS_USE_SUBKEY,

				   &in_data, out_creds, &apreq_pkt);

	if (ret) {

		syslog(LOG_DEBUG, "%s: unable to make AP-REQ for %s",

		       __func__, host);

		goto out_free_auth;

	}

	ret = krb5_auth_con_getsendsubkey(context, auth_context, &tokb);

	if (ret) {

		syslog(LOG_DEBUG, "%s: unable to get session key for %s",

		       __func__, host);

		goto out_free_auth;

	}

	*mechtoken = data_blob(apreq_pkt.data, apreq_pkt.length);

	*sess_key = data_blob(KRB5_KEY_DATA(tokb), KRB5_KEY_LENGTH(tokb));

	krb5_free_keyblock(context, tokb);

out_free_auth:

	krb5_auth_con_free(context, auth_context);

out_free_creds:

	krb5_free_creds(context, out_creds);

out_free_principal:

	krb5_free_principal(context, in_creds.client);

	return ret;

}

/*

 * 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 *host, DATA_BLOB * secblob,

		 DATA_BLOB * sess_key, krb5_ccache ccache)

{

	int retval;

	DATA_BLOB tkt, tkt_wrapped;

	syslog(LOG_DEBUG, "%s: getting service ticket for %s", __func__, host);

	/* get a kerberos ticket for the service and extract the session key */

	retval = cifs_krb5_get_req(host, ccache, &tkt, sess_key);

	if (retval) {

		syslog(LOG_DEBUG, "%s: failed to obtain service ticket (%d)",

		       __func__, retval);

		return retval;

	}

	syslog(LOG_DEBUG, "%s: obtained service ticket", __func__);

	/* 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	0x1

#define DKD_HAVE_VERSION	0x2

#define DKD_HAVE_SEC		0x4

#define DKD_HAVE_IP		0x8

#define DKD_HAVE_UID		0x10

#define DKD_HAVE_PID		0x20

#define DKD_HAVE_CREDUID	0x40

#define DKD_HAVE_USERNAME	0x80

#define DKD_MUSTHAVE_SET (DKD_HAVE_HOSTNAME|DKD_HAVE_VERSION|DKD_HAVE_SEC)

struct decoded_args {

	int ver;

	char *hostname;

	char *ip;

	char *username;

	uid_t uid;

	uid_t creduid;

	pid_t pid;

	sectype_t sec;

};

static unsigned int

decode_key_description(const char *desc, struct decoded_args *arg)

{

	int len;

	int retval = 0;

	char *pos;

	const char *tkn = desc;

	do {

		pos = index(tkn, ';');

		if (strncmp(tkn, "host=", 5) == 0) {

			if (pos == NULL)

				len = strlen(tkn);

			else

				len = pos - tkn;

			len -= 5;

			free(arg->hostname);

			arg->hostname = strndup(tkn + 5, len);

			if (arg->hostname == NULL) {

				syslog(LOG_ERR, "Unable to allocate memory");

				return 1;

			}

			retval |= DKD_HAVE_HOSTNAME;

			syslog(LOG_DEBUG, "host=%s", arg->hostname);

		} else if (!strncmp(tkn, "ip4=", 4) || !strncmp(tkn, "ip6=", 4)) {

			if (pos == NULL)

				len = strlen(tkn);

			else

				len = pos - tkn;

			len -= 4;

			free(arg->ip);

			arg->ip = strndup(tkn + 4, len);

			if (arg->ip == NULL) {

				syslog(LOG_ERR, "Unable to allocate memory");

				return 1;

			}

			retval |= DKD_HAVE_IP;

			syslog(LOG_DEBUG, "ip=%s", arg->ip);

		} else if (strncmp(tkn, "user=", 5) == 0) {

			if (pos == NULL)

				len = strlen(tkn);

			else

				len = pos - tkn;

			len -= 5;

			free(arg->username);

			arg->username = strndup(tkn + 5, len);

			if (arg->username == NULL) {

				syslog(LOG_ERR, "Unable to allocate memory");

				return 1;

			}

			retval |= DKD_HAVE_USERNAME;

			syslog(LOG_DEBUG, "user=%s", arg->username);

		} else if (strncmp(tkn, "pid=", 4) == 0) {

			errno = 0;

			arg->pid = strtol(tkn + 4, NULL, 0);

			if (errno != 0) {

				syslog(LOG_ERR, "Invalid pid format: %s",

				       strerror(errno));

				return 1;

			}

			syslog(LOG_DEBUG, "pid=%u", arg->pid);

			retval |= DKD_HAVE_PID;

		} else if (strncmp(tkn, "sec=", 4) == 0) {

			if (strncmp(tkn + 4, "krb5", 4) == 0) {

				retval |= DKD_HAVE_SEC;

				arg->sec = KRB5;

			} else if (strncmp(tkn + 4, "mskrb5", 6) == 0) {

				retval |= DKD_HAVE_SEC;

				arg->sec = MS_KRB5;

			}

			syslog(LOG_DEBUG, "sec=%d", arg->sec);

		} else if (strncmp(tkn, "uid=", 4) == 0) {

			errno = 0;

			arg->uid = strtol(tkn + 4, NULL, 16);

			if (errno != 0) {

				syslog(LOG_ERR, "Invalid uid format: %s",

				       strerror(errno));

				return 1;

			}

			retval |= DKD_HAVE_UID;

			syslog(LOG_DEBUG, "uid=%u", arg->uid);

		} else if (strncmp(tkn, "creduid=", 8) == 0) {

			errno = 0;

			arg->creduid = strtol(tkn + 8, NULL, 16);

			if (errno != 0) {

				syslog(LOG_ERR, "Invalid creduid format: %s",

				       strerror(errno));

				return 1;

			}

			retval |= DKD_HAVE_CREDUID;

			syslog(LOG_DEBUG, "creduid=%u", arg->creduid);

		} else if (strncmp(tkn, "ver=", 4) == 0) {	/* if version */

			errno = 0;

			arg->ver = strtol(tkn + 4, NULL, 16);

			if (errno != 0) {

				syslog(LOG_ERR, "Invalid version format: %s",

				       strerror(errno));

				return 1;

			}

			retval |= DKD_HAVE_VERSION;

			syslog(LOG_DEBUG, "ver=%d", arg->ver);

		}

		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_ERR, "invalid key description: %s",

			       key_descr);

			return 1;

		}

	}

	keyend++;

	/* resolve name to ip */

	c = getaddrinfo(keyend, NULL, NULL, &addr);

	if (c) {

		syslog(LOG_ERR, "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_ERR, "%s: inet_ntop: %s", __func__, strerror(errno));

		freeaddrinfo(addr);

		return 1;

	}

	/* setup key */

	c = keyctl_instantiate(key, ip, strlen(ip) + 1, 0);

	if (c == -1) {

		syslog(LOG_ERR, "%s: keyctl_instantiate: %s", __func__,

		       strerror(errno));

		freeaddrinfo(addr);

		return 1;

	}

	freeaddrinfo(addr);

	return 0;

}

/*

 * Older kernels sent IPv6 addresses without colons. Well, at least

 * they're fixed-length strings. Convert these addresses to have colon

 * delimiters to make getaddrinfo happy.

 */

static void convert_inet6_addr(const char *from, char *to)

{

	int i = 1;

	while (*from) {

		*to++ = *from++;

		if (!(i++ % 4) && *from)

			*to++ = ':';

	}

	*to = 0;

}

static int ip_to_fqdn(const char *addrstr, char *host, size_t hostlen)

{

	int rc;

	struct addrinfo hints = {.ai_flags = AI_NUMERICHOST };

	struct addrinfo *res;

	const char *ipaddr = addrstr;

	char converted[INET6_ADDRSTRLEN + 1];

	if ((strlen(ipaddr) > INET_ADDRSTRLEN) && !strchr(ipaddr, ':')) {

		convert_inet6_addr(ipaddr, converted);

		ipaddr = converted;

	}

	rc = getaddrinfo(ipaddr, NULL, &hints, &res;;

	if (rc) {

		syslog(LOG_DEBUG, "%s: failed to resolve %s to "

		       "ipaddr: %s", __func__, ipaddr,

		       rc == EAI_SYSTEM ? strerror(errno) : gai_strerror(rc));

		return rc;

	}

	rc = getnameinfo(res->ai_addr, res->ai_addrlen, host, hostlen,

			 NULL, 0, NI_NAMEREQD);

	freeaddrinfo(res);

	if (rc) {

		syslog(LOG_DEBUG, "%s: failed to resolve %s to fqdn: %s",

		       __func__, ipaddr,

		       rc == EAI_SYSTEM ? strerror(errno) : gai_strerror(rc));

		return rc;

	}

	syslog(LOG_DEBUG, "%s: resolved %s to %s", __func__, ipaddr, host);

	return 0;

}

/* walk a string and lowercase it in-place */

static void

lowercase_string(char *c)

{

	while(*c) {

		*c = tolower(*c);

		++c;

	}

}

static void usage(void)

{

	fprintf(stderr, "Usage: %s [ -K /path/to/keytab] [-k /path/to/krb5.conf] [-E] [-t] [-v] [-l] key_serial\n", prog);

}

static const struct option long_options[] = {

	{"no-env-probe", 0, NULL, 'E'},

	{"krb5conf", 1, NULL, 'k'},

	{"legacy-uid", 0, NULL, 'l'},

	{"trust-dns", 0, NULL, 't'},

	{"keytab", 1, NULL, 'K'},

	{"version", 0, NULL, 'v'},

	{NULL, 0, NULL, 0}

};

int main(const int argc, char *const argv[])