path: root/source4/kdc/mit_samba.c

/*
   MIT-Samba4 library

   Copyright (c) 2010, Simo Sorce <idra@samba.org>
   Copyright (c) 2014-2015 Guenther Deschner <gd@samba.org>
   Copyright (c) 2014-2016 Andreas Schneider <asn@samba.org>

   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 3 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, see <http://www.gnu.org/licenses/>.
 */

#define TEVENT_DEPRECATED 1

#include "includes.h"
#include "param/param.h"
#include "dsdb/samdb/samdb.h"
#include "system/kerberos.h"
#include "lib/replace/system/filesys.h"
#include <com_err.h>
#include <kdb.h>
#include <kadm5/kadm_err.h>
#include "kdc/sdb.h"
#include "kdc/sdb_kdb.h"
#include "auth/kerberos/kerberos.h"
#include "auth/kerberos/pac_utils.h"
#include "kdc/samba_kdc.h"
#include "kdc/pac-glue.h"
#include "kdc/db-glue.h"
#include "auth/auth.h"
#include "kdc/kpasswd_glue.h"
#include "auth/auth_sam.h"

#include "mit_samba.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_KERBEROS

void mit_samba_context_free(struct mit_samba_context *ctx)
{
	/* free MIT's krb5_context */
	if (ctx->context) {
		krb5_free_context(ctx->context);
	}

	/* then free everything else */
	talloc_free(ctx);
}

/*
 * Implement a callback to log to the MIT KDC log facility
 *
 * http://web.mit.edu/kerberos/krb5-devel/doc/plugindev/general.html#logging-from-kdc-and-kadmind-plugin-modules
 */
static void mit_samba_debug(void *private_ptr, int msg_level, const char *msg)
{
	int is_error = errno;

	if (msg_level > 0) {
		is_error = 0;
	}

	com_err("mitkdc", is_error, "%s", msg);
}

krb5_error_code mit_samba_context_init(struct mit_samba_context **_ctx)
{
	NTSTATUS status;
	struct mit_samba_context *ctx;
	const char *s4_conf_file;
	krb5_error_code ret;
	struct samba_kdc_base_context base_ctx;

	ctx = talloc_zero(NULL, struct mit_samba_context);
	if (!ctx) {
		ret = ENOMEM;
		goto done;
	}

	base_ctx.ev_ctx = tevent_context_init(ctx);
	if (!base_ctx.ev_ctx) {
		ret = ENOMEM;
		goto done;
	}
	tevent_loop_allow_nesting(base_ctx.ev_ctx);
	base_ctx.lp_ctx = loadparm_init_global(false);
	if (!base_ctx.lp_ctx) {
		ret = ENOMEM;
		goto done;
	}

	debug_set_callback(NULL, mit_samba_debug);

	/* init s4 configuration */
	s4_conf_file = lpcfg_configfile(base_ctx.lp_ctx);
	if (s4_conf_file != NULL) {
		char *p = talloc_strdup(ctx, s4_conf_file);
		if (p == NULL) {
			ret = ENOMEM;
			goto done;
		}
		lpcfg_load(base_ctx.lp_ctx, p);
		TALLOC_FREE(p);
	} else {
		lpcfg_load_default(base_ctx.lp_ctx);
	}

	status = samba_kdc_setup_db_ctx(ctx, &base_ctx, &ctx->db_ctx);
	if (!NT_STATUS_IS_OK(status)) {
		ret = EINVAL;
		goto done;
	}

	/* init MIT's krb_context and log facilities */
	ret = smb_krb5_init_context_basic(ctx,
					  ctx->db_ctx->lp_ctx,
					  &ctx->context);
	if (ret) {
		goto done;
	}

	ret = 0;

done:
	if (ret) {
		mit_samba_context_free(ctx);
	} else {
		*_ctx = ctx;
	}
	return ret;
}

int mit_samba_generate_salt(krb5_data *salt)
{
	if (salt == NULL) {
		return EINVAL;
	}

	salt->length = 16;
	salt->data = malloc(salt->length);
	if (salt->data == NULL) {
		return ENOMEM;
	}

	generate_random_buffer((uint8_t *)salt->data, salt->length);

	return 0;
}

int mit_samba_generate_random_password(krb5_data *pwd)
{
	TALLOC_CTX *tmp_ctx;
	char *password;
	char *data = NULL;
	const unsigned length = 24;

	if (pwd == NULL) {
		return EINVAL;
	}

	tmp_ctx = talloc_named(NULL,
			       0,
			       "mit_samba_generate_random_password context");
	if (tmp_ctx == NULL) {
		return ENOMEM;
	}

	password = generate_random_password(tmp_ctx, length, length);
	if (password == NULL) {
		talloc_free(tmp_ctx);
		return ENOMEM;
	}

	data = strdup(password);
	talloc_free(tmp_ctx);
	if (data == NULL) {
		return ENOMEM;
	}

	*pwd = smb_krb5_make_data(data, length);

	return 0;
}

krb5_error_code mit_samba_get_principal(struct mit_samba_context *ctx,
					krb5_const_principal principal,
					unsigned int kflags,
					krb5_db_entry **_kentry)
{
	struct sdb_entry sentry = {};
	krb5_db_entry *kentry;
	krb5_error_code ret;
	uint32_t sflags = 0;
	krb5_principal referral_principal = NULL;

	kentry = calloc(1, sizeof(krb5_db_entry));
	if (kentry == NULL) {
		return ENOMEM;
	}

	/*
	 * The MIT KDC code that wants the canonical name in all lookups, and
	 * takes care to canonicalize only when appropriate.
	 */
	sflags |= SDB_F_FORCE_CANON;

	if (kflags & KRB5_KDB_FLAG_REFERRAL_OK) {
		sflags |= SDB_F_CANON;
	}

	if (kflags & KRB5_KDB_FLAG_CLIENT) {
		sflags |= SDB_F_GET_CLIENT;
		sflags |= SDB_F_FOR_AS_REQ;
	} else {
		int equal = smb_krb5_principal_is_tgs(ctx->context, principal);
		if (equal == -1) {
			return ENOMEM;
		}

		if (equal) {
			sflags |= SDB_F_GET_KRBTGT;
		} else {
			sflags |= SDB_F_GET_SERVER;
			sflags |= SDB_F_FOR_TGS_REQ;
		}
	}

	/* always set this or the created_by data will not be populated by samba's
	 * backend and we will fail to parse the entry later */
	sflags |= SDB_F_ADMIN_DATA;


fetch_referral_principal:
	ret = samba_kdc_fetch(ctx->context, ctx->db_ctx,
			      principal, sflags, 0, &sentry);
	switch (ret) {
	case 0:
		break;
	case SDB_ERR_NOENTRY:
		ret = KRB5_KDB_NOENTRY;
		goto done;
	case SDB_ERR_WRONG_REALM: {
		char *dest_realm = NULL;
		const char *our_realm = lpcfg_realm(ctx->db_ctx->lp_ctx);

		if (sflags & SDB_F_FOR_AS_REQ) {
			/*
			 * If this is a request for a TGT, we are done. The KDC
			 * will return the correct error to the client.
			 */
			ret = 0;
			break;
		}

		if (referral_principal != NULL) {
			sdb_entry_free(&sentry);
			ret = KRB5_KDB_NOENTRY;
			goto done;
		}

		/*
		 * We get a TGS request
		 *
		 *     cifs/dc7.SAMBA2008R2.EXAMPLE.COM@ADDOM.SAMBA.EXAMPLE.COM
		 *
		 * to our DC for the realm
		 *
		 *     ADDOM.SAMBA.EXAMPLE.COM
		 *
		 * We look up if we have an entry in the database and get an
		 * entry with the principal:
		 *
		 *     cifs/dc7.SAMBA2008R2.EXAMPLE.COM@SAMBA2008R2.EXAMPLE.COM
		 *
		 * and the error: SDB_ERR_WRONG_REALM.
		 *
		 * In the case of a TGS-REQ we need to return a referral ticket
		 * for the next trust hop to the client. This ticket will have
		 * the following principal:
		 *
		 *     krbtgt/SAMBA2008R2.EXAMPLE.COM@ADDOM.SAMBA.EXAMPLE.COM
		 *
		 * We just redo the lookup in the database with the referral
		 * principal and return success.
		 */
		dest_realm = smb_krb5_principal_get_realm(
			ctx, ctx->context, sentry.principal);
		sdb_entry_free(&sentry);
		if (dest_realm == NULL) {
			ret = KRB5_KDB_NOENTRY;
			goto done;
		}

		ret = smb_krb5_make_principal(ctx->context,
					      &referral_principal,
					      our_realm,
					      KRB5_TGS_NAME,
					      dest_realm,
					      NULL);
		TALLOC_FREE(dest_realm);
		if (ret != 0) {
			goto done;
		}

		principal = referral_principal;
		goto fetch_referral_principal;
	}
	case SDB_ERR_NOT_FOUND_HERE:
		/* FIXME: RODC support */
	default:
		goto done;
	}

	ret = sdb_entry_to_krb5_db_entry(ctx->context, &sentry, kentry);

	sdb_entry_free(&sentry);

done:
	krb5_free_principal(ctx->context, referral_principal);
	referral_principal = NULL;

	if (ret) {
		free(kentry);
	} else {
		*_kentry = kentry;
	}
	return ret;
}

krb5_error_code mit_samba_get_firstkey(struct mit_samba_context *ctx,
				       krb5_db_entry **_kentry)
{
	struct sdb_entry sentry = {};
	krb5_db_entry *kentry;
	krb5_error_code ret;

	kentry = malloc(sizeof(krb5_db_entry));
	if (kentry == NULL) {
		return ENOMEM;
	}

	ret = samba_kdc_firstkey(ctx->context, ctx->db_ctx, &sentry);
	switch (ret) {
	case 0:
		break;
	case SDB_ERR_NOENTRY:
		free(kentry);
		return KRB5_KDB_NOENTRY;
	case SDB_ERR_NOT_FOUND_HERE:
		/* FIXME: RODC support */
	default:
		free(kentry);
		return ret;
	}

	ret = sdb_entry_to_krb5_db_entry(ctx->context, &sentry, kentry);

	sdb_entry_free(&sentry);

	if (ret) {
		free(kentry);
	} else {
		*_kentry = kentry;
	}
	return ret;
}

krb5_error_code mit_samba_get_nextkey(struct mit_samba_context *ctx,
				      krb5_db_entry **_kentry)
{
	struct sdb_entry sentry = {};
	krb5_db_entry *kentry;
	krb5_error_code ret;

	kentry = malloc(sizeof(krb5_db_entry));
	if (kentry == NULL) {
		return ENOMEM;
	}

	ret = samba_kdc_nextkey(ctx->context, ctx->db_ctx, &sentry);
	switch (ret) {
	case 0:
		break;
	case SDB_ERR_NOENTRY:
		free(kentry);
		return KRB5_KDB_NOENTRY;
	case SDB_ERR_NOT_FOUND_HERE:
		/* FIXME: RODC support */
	default:
		free(kentry);
		return ret;
	}

	ret = sdb_entry_to_krb5_db_entry(ctx->context, &sentry, kentry);

	sdb_entry_free(&sentry);

	if (ret) {
		free(kentry);
	} else {
		*_kentry = kentry;
	}
	return ret;
}

krb5_error_code mit_samba_get_pac(struct mit_samba_context *smb_ctx,
				  krb5_context context,
				  uint32_t flags,
				  krb5_db_entry *client,
				  krb5_db_entry *server,
				  krb5_keyblock *replaced_reply_key,
				  krb5_pac *pac)
{
	TALLOC_CTX *tmp_ctx;
	const struct auth_user_info_dc *user_info_dc = NULL;
	struct auth_user_info_dc *user_info_dc_shallow_copy = NULL;
	DATA_BLOB *logon_info_blob = NULL;
	DATA_BLOB *upn_dns_info_blob = NULL;
	DATA_BLOB *cred_ndr = NULL;
	DATA_BLOB **cred_ndr_ptr = NULL;
	DATA_BLOB cred_blob = data_blob_null;
	DATA_BLOB *pcred_blob = NULL;
	DATA_BLOB *pac_attrs_blob = NULL;
	DATA_BLOB *requester_sid_blob = NULL;
	const DATA_BLOB *client_claims_blob = NULL;
	NTSTATUS nt_status;
	krb5_error_code code;
	struct samba_kdc_entry *skdc_entry;
	struct samba_kdc_entry *server_entry = NULL;
	bool is_krbtgt;
	/* Only include resource groups in a service ticket. */
	enum auth_group_inclusion group_inclusion;
	enum samba_asserted_identity asserted_identity =
		(flags & KRB5_KDB_FLAG_PROTOCOL_TRANSITION) ?
			SAMBA_ASSERTED_IDENTITY_SERVICE :
			SAMBA_ASSERTED_IDENTITY_AUTHENTICATION_AUTHORITY;

	if (client == NULL) {
		return EINVAL;
	}
	skdc_entry = talloc_get_type_abort(client->e_data,
					   struct samba_kdc_entry);

	if (server == NULL) {
		return EINVAL;
	}
	{
		int result = smb_krb5_principal_is_tgs(smb_ctx->context, server->princ);
		if (result == -1) {
			return ENOMEM;
		}

		is_krbtgt = result;
	}
	server_entry = talloc_get_type_abort(server->e_data,
					     struct samba_kdc_entry);

	/* Only include resource groups in a service ticket. */
	if (is_krbtgt) {
		group_inclusion = AUTH_EXCLUDE_RESOURCE_GROUPS;
	} else if (server_entry->supported_enctypes & KERB_ENCTYPE_RESOURCE_SID_COMPRESSION_DISABLED) {
		group_inclusion = AUTH_INCLUDE_RESOURCE_GROUPS;
	} else {
		group_inclusion = AUTH_INCLUDE_RESOURCE_GROUPS_COMPRESSED;
	}

	tmp_ctx = talloc_named(smb_ctx,
			       0,
			       "mit_samba_get_pac context");
	if (tmp_ctx == NULL) {
		return ENOMEM;
	}

	/* Check if we have a PREAUTH key */
	if (replaced_reply_key != NULL) {
		cred_ndr_ptr = &cred_ndr;
	}

	code = samba_kdc_get_user_info_from_db(tmp_ctx,
					       server_entry->kdc_db_ctx->samdb,
					       skdc_entry,
					       skdc_entry->msg,
					       &user_info_dc);
	if (code) {
		talloc_free(tmp_ctx);
		return code;
	}

	/* Make a shallow copy of the user_info_dc structure. */
	nt_status = authsam_shallow_copy_user_info_dc(tmp_ctx,
						      user_info_dc,
						      &user_info_dc_shallow_copy);
	user_info_dc = NULL;

	if (!NT_STATUS_IS_OK(nt_status)) {
		DBG_ERR("Failed to allocate shallow copy of user_info_dc: %s\n",
			nt_errstr(nt_status));
		talloc_free(tmp_ctx);
		return map_errno_from_nt_status(nt_status);
	}


	nt_status = samba_kdc_add_asserted_identity(asserted_identity,
						    user_info_dc_shallow_copy);
	if (!NT_STATUS_IS_OK(nt_status)) {
		DBG_ERR("Failed to add asserted identity: %s\n",
			nt_errstr(nt_status));
		talloc_free(tmp_ctx);
		return EINVAL;
	}

	nt_status = samba_kdc_add_claims_valid(user_info_dc_shallow_copy);
	if (!NT_STATUS_IS_OK(nt_status)) {
		DBG_ERR("Failed to add Claims Valid: %s\n",
			nt_errstr(nt_status));
		talloc_free(tmp_ctx);
		return EINVAL;
	}

	/* We no longer need to modify this, so assign to const variable */
	user_info_dc = user_info_dc_shallow_copy;

	nt_status = samba_kdc_get_logon_info_blob(tmp_ctx,
						  user_info_dc,
						  group_inclusion,
						  &logon_info_blob);
	if (!NT_STATUS_IS_OK(nt_status)) {
		talloc_free(tmp_ctx);
		return EINVAL;
	}

	if (cred_ndr_ptr != NULL) {
		nt_status = samba_kdc_get_cred_ndr_blob(tmp_ctx,
							skdc_entry,
							cred_ndr_ptr);
		if (!NT_STATUS_IS_OK(nt_status)) {
			talloc_free(tmp_ctx);
			return EINVAL;
		}
	}

	nt_status = samba_kdc_get_upn_info_blob(tmp_ctx,
						user_info_dc,
						&upn_dns_info_blob);
	if (!NT_STATUS_IS_OK(nt_status)) {
		talloc_free(tmp_ctx);
		return EINVAL;
	}

	if (is_krbtgt) {
		nt_status = samba_kdc_get_pac_attrs_blob(tmp_ctx,
							 PAC_ATTRIBUTE_FLAG_PAC_WAS_GIVEN_IMPLICITLY,
							 &pac_attrs_blob);
		if (!NT_STATUS_IS_OK(nt_status)) {
			talloc_free(tmp_ctx);
			return EINVAL;
		}

		nt_status = samba_kdc_get_requester_sid_blob(tmp_ctx,
							     user_info_dc,
							     &requester_sid_blob);
		if (!NT_STATUS_IS_OK(nt_status)) {
			talloc_free(tmp_ctx);
			return EINVAL;
		}
	}

	nt_status = samba_kdc_get_claims_blob(tmp_ctx,
					      skdc_entry,
					      &client_claims_blob);
	if (!NT_STATUS_IS_OK(nt_status)) {
		talloc_free(tmp_ctx);
		return EINVAL;
	}

	if (replaced_reply_key != NULL && cred_ndr != NULL) {
		code = samba_kdc_encrypt_pac_credentials(context,
							 replaced_reply_key,
							 cred_ndr,
							 tmp_ctx,
							 &cred_blob);
		if (code != 0) {
			talloc_free(tmp_ctx);
			return code;
		}
		pcred_blob = &cred_blob;
	}

	code = samba_make_krb5_pac(context,
				   logon_info_blob,
				   pcred_blob,
				   upn_dns_info_blob,
				   pac_attrs_blob,
				   requester_sid_blob,
				   NULL /* deleg_blob */,
				   client_claims_blob,
				   NULL /* device_info_blob */,
				   NULL /* device_claims_blob */,
				   *pac);

	talloc_free(tmp_ctx);
	return code;
}

krb5_error_code mit_samba_update_pac(struct mit_samba_context *ctx,
				    krb5_context context,
				    int kdc_flags,
				    krb5_db_entry *client,
				    krb5_db_entry *server,
				    krb5_db_entry *krbtgt,
				    krb5_pac old_pac,
				    krb5_pac new_pac)
{
	TALLOC_CTX *tmp_ctx = NULL;
	krb5_error_code code;
	struct samba_kdc_entry *client_skdc_entry = NULL;
	struct samba_kdc_entry *server_skdc_entry = NULL;
	struct samba_kdc_entry *krbtgt_skdc_entry = NULL;
	struct samba_kdc_entry_pac client_pac_entry = {};
	bool is_in_db = false;
	bool is_trusted = false;
	uint32_t flags = 0;

	/* Create a memory context early so code can use talloc_stackframe() */
	tmp_ctx = talloc_named(ctx, 0, "mit_samba_update_pac context");
	if (tmp_ctx == NULL) {
		return ENOMEM;
	}

	if (client != NULL) {
		client_skdc_entry =
			talloc_get_type_abort(client->e_data,
					      struct samba_kdc_entry);
	}

	if (krbtgt == NULL) {
		code = EINVAL;
		goto done;
	}
	krbtgt_skdc_entry =
		talloc_get_type_abort(krbtgt->e_data,
				      struct samba_kdc_entry);

	if (server == NULL) {
		code = EINVAL;
		goto done;
	}
	server_skdc_entry =
		talloc_get_type_abort(server->e_data,
				      struct samba_kdc_entry);

	/*
	 * If the krbtgt was generated by an RODC, and we are not that
	 * RODC, then we need to regenerate the PAC - we can't trust
	 * it, and confirm that the RODC was permitted to print this ticket
	 *
	 * Because of the samba_kdc_validate_pac_blob() step we can be
	 * sure that the record in 'client' or 'server' matches the SID in the
	 * original PAC.
	 */
	code = samba_krbtgt_is_in_db(krbtgt_skdc_entry,
				     &is_in_db,
				     &is_trusted);
	if (code != 0) {
		goto done;
	}

	if (kdc_flags & KRB5_KDB_FLAG_PROTOCOL_TRANSITION) {
		flags |= SAMBA_KDC_FLAG_PROTOCOL_TRANSITION;
	}

	if (kdc_flags & KRB5_KDB_FLAG_CONSTRAINED_DELEGATION) {
		flags |= SAMBA_KDC_FLAG_CONSTRAINED_DELEGATION;
	}

	client_pac_entry = samba_kdc_entry_pac_from_trusted(old_pac,
							    client_skdc_entry,
							    samba_kdc_entry_is_trust(krbtgt_skdc_entry),
							    is_trusted);

	code = samba_kdc_verify_pac(tmp_ctx,
				    context,
				    krbtgt_skdc_entry->kdc_db_ctx->samdb,
				    flags,
				    client_pac_entry,
				    krbtgt_skdc_entry);
	if (code != 0) {
		goto done;
	}

	code = samba_kdc_update_pac(tmp_ctx,
				    context,
				    krbtgt_skdc_entry->kdc_db_ctx->samdb,
				    krbtgt_skdc_entry->kdc_db_ctx->lp_ctx,
				    flags,
				    client_pac_entry,
				    server->princ,
				    server_skdc_entry,
				    NULL /* delegated_proxy_principal */,
				    (struct samba_kdc_entry_pac) {} /* delegated_proxy */,
				    (struct samba_kdc_entry_pac) {} /* device */,
				    new_pac,
				    NULL /* server_audit_info_out */,
				    NULL /* status_out */);
	if (code != 0) {
		if (code == ENOATTR) {
			/*
			 * We can't tell the KDC to not issue a PAC. It will
			 * just return the newly allocated empty PAC.
			 */
			code = 0;
		}
	}

done:
	talloc_free(tmp_ctx);
	return code;
}

/* provide header, function is exported but there are no public headers */

krb5_error_code encode_krb5_padata_sequence(krb5_pa_data *const *rep, krb5_data **code);

/* this function allocates 'data' using malloc.
 * The caller is responsible for freeing it */
static void samba_kdc_build_edata_reply(NTSTATUS nt_status, DATA_BLOB *e_data)
{
	krb5_error_code ret = 0;
	krb5_pa_data pa, *ppa[2];
	krb5_data *d = NULL;

	if (!e_data)
		return;

	e_data->data   = NULL;
	e_data->length = 0;

	pa.magic		= KV5M_PA_DATA;
	pa.pa_type		= KRB5_PADATA_PW_SALT /* KERB_ERR_TYPE_EXTENDED */;
	pa.length		= 12;
	pa.contents		= malloc(pa.length);
	if (!pa.contents) {
		return;
	}

	SIVAL(pa.contents, 0, NT_STATUS_V(nt_status));
	SIVAL(pa.contents, 4, 0);
	SIVAL(pa.contents, 8, 1);

	ppa[0] = &pa;
	ppa[1] = NULL;

	ret = encode_krb5_padata_sequence(ppa, &d);
	free(pa.contents);
	if (ret) {
		return;
	}

	e_data->data   = (uint8_t *)d->data;
	e_data->length = d->length;

	/* free d, not d->data - gd */
	free(d);

	return;
}

krb5_error_code mit_samba_check_client_access(struct mit_samba_context *ctx,
					      krb5_db_entry *client,
					      const char *client_name,
					      krb5_db_entry *server,
					      const char *server_name,
					      const char *netbios_name,
					      bool password_change,
					      DATA_BLOB *e_data)
{
	struct samba_kdc_entry *skdc_entry;
	NTSTATUS nt_status;

	skdc_entry = talloc_get_type(client->e_data, struct samba_kdc_entry);

	nt_status = samba_kdc_check_client_access(skdc_entry,
						  client_name,
						  netbios_name,
						  password_change);

	if (!NT_STATUS_IS_OK(nt_status)) {
		if (NT_STATUS_EQUAL(nt_status, NT_STATUS_NO_MEMORY)) {
			return ENOMEM;
		}

		samba_kdc_build_edata_reply(nt_status, e_data);

		return samba_kdc_map_policy_err(nt_status);
	}

	return 0;
}

krb5_error_code mit_samba_check_s4u2proxy(struct mit_samba_context *ctx,
					  const krb5_db_entry *server,
					  krb5_const_principal target_principal)
{
	struct samba_kdc_entry *server_skdc_entry =
		talloc_get_type_abort(server->e_data, struct samba_kdc_entry);
	krb5_error_code code;

	code = samba_kdc_check_s4u2proxy(ctx->context,
					 ctx->db_ctx,
					 server_skdc_entry,
					 target_principal);

	return code;
}

krb5_error_code mit_samba_check_allowed_to_delegate_from(
		struct mit_samba_context *ctx,
		krb5_const_principal client_principal,
		krb5_const_principal server_principal,
		krb5_pac header_pac,
		const krb5_db_entry *proxy)
{
	struct samba_kdc_entry *proxy_skdc_entry =
		talloc_get_type_abort(proxy->e_data, struct samba_kdc_entry);
	struct auth_user_info_dc *user_info_dc = NULL;
	TALLOC_CTX *mem_ctx = NULL;
	krb5_error_code code;

	mem_ctx = talloc_new(NULL);
	if (mem_ctx == NULL) {
		return ENOMEM;
	}

	/*
	 * FIXME: If ever we support RODCs, we must check that the PAC has not
	 * been issued by an RODC (other than ourselves) — otherwise the PAC
	 * cannot be trusted. Because the plugin interface does not give us the
	 * client entry, we cannot look up its groups in the database.
	 */
	code = kerberos_pac_to_user_info_dc(mem_ctx,
					    header_pac,
					    ctx->context,
					    &user_info_dc,
					    AUTH_INCLUDE_RESOURCE_GROUPS,
					    NULL,
					    NULL,
					    NULL);
	if (code != 0) {
		goto out;
	}

	code = samba_kdc_check_s4u2proxy_rbcd(ctx->context,
					      ctx->db_ctx,
					      client_principal,
					      server_principal,
					      user_info_dc,
					      NULL /* device_info_dc */,
					      (struct auth_claims) {},
					      proxy_skdc_entry);
out:
	talloc_free(mem_ctx);
	return code;
}

static krb5_error_code mit_samba_change_pwd_error(krb5_context context,
						  NTSTATUS result,
						  enum samPwdChangeReason reject_reason,
						  struct samr_DomInfo1 *dominfo)
{
	krb5_error_code code = KADM5_PASS_Q_GENERIC;

	if (NT_STATUS_EQUAL(result, NT_STATUS_NO_SUCH_USER)) {
		code = KADM5_BAD_PRINCIPAL;
		krb5_set_error_message(context,
				       code,
				       "No such user when changing password");
	}
	if (NT_STATUS_EQUAL(result, NT_STATUS_ACCESS_DENIED)) {
		code = KADM5_PASS_Q_GENERIC;
		krb5_set_error_message(context,
				       code,
				       "Not permitted to change password");
	}
	if (NT_STATUS_EQUAL(result, NT_STATUS_PASSWORD_RESTRICTION) &&
	    dominfo != NULL) {
		switch (reject_reason) {
		case SAM_PWD_CHANGE_PASSWORD_TOO_SHORT:
			code = KADM5_PASS_Q_TOOSHORT;
			krb5_set_error_message(context,
					       code,
					       "Password too short, password "
					       "must be at least %d characters "
					       "long.",
					       dominfo->min_password_length);
			break;
		case SAM_PWD_CHANGE_NOT_COMPLEX:
			code = KADM5_PASS_Q_DICT;
			krb5_set_error_message(context,
					       code,
					       "Password does not meet "
					       "complexity requirements");
			break;
		case SAM_PWD_CHANGE_PWD_IN_HISTORY:
			code = KADM5_PASS_TOOSOON;
			krb5_set_error_message(context,
					       code,
					       "Password is already in password "
					       "history. New password must not "
					       "match any of your %d previous "
					       "passwords.",
					       dominfo->password_history_length);
			break;
		default:
			code = KADM5_PASS_Q_GENERIC;
			krb5_set_error_message(context,
					       code,
					       "Password change rejected, "
					       "password changes may not be "
					       "permitted on this account, or "
					       "the minimum password age may "
					       "not have elapsed.");
			break;
		}
	}

	return code;
}

krb5_error_code mit_samba_kpasswd_change_password(struct mit_samba_context *ctx,
						  char *pwd,
						  krb5_db_entry *db_entry)
{
	NTSTATUS status;
	NTSTATUS result = NT_STATUS_UNSUCCESSFUL;
	TALLOC_CTX *tmp_ctx;
	DATA_BLOB password;
	enum samPwdChangeReason reject_reason;
	struct samr_DomInfo1 *dominfo;
	const char *error_string = NULL;
	const struct auth_user_info_dc *user_info_dc = NULL;
	struct samba_kdc_entry *p =
		talloc_get_type_abort(db_entry->e_data, struct samba_kdc_entry);
	krb5_error_code code = 0;

#ifdef DEBUG_PASSWORD
	DBG_WARNING("mit_samba_kpasswd_change_password called with: %s\n", pwd);
#endif

	tmp_ctx = talloc_named(ctx, 0, "mit_samba_kpasswd_change_password");
	if (tmp_ctx == NULL) {
		return ENOMEM;
	}

	code = samba_kdc_get_user_info_from_db(tmp_ctx,
					       ctx->db_ctx->samdb,
					       p,
					       p->msg,
					       &user_info_dc);
	if (code) {
		const char *krb5err = krb5_get_error_message(ctx->context, code);
		DBG_WARNING("samba_kdc_get_user_info_from_db failed: %s\n",
			krb5err != NULL ? krb5err : "<unknown>");
		krb5_free_error_message(ctx->context, krb5err);

		goto out;
	}

	status = auth_generate_session_info(tmp_ctx,
					    ctx->db_ctx->lp_ctx,
					    ctx->db_ctx->samdb,
					    user_info_dc,
					    0, /* session_info_flags */
					    &ctx->session_info);

	if (!NT_STATUS_IS_OK(status)) {
		DBG_WARNING("auth_generate_session_info failed: %s\n",
			    nt_errstr(status));
		code = EINVAL;
		goto out;
	}

	/* password is expected as UTF16 */

	if (!convert_string_talloc(tmp_ctx, CH_UTF8, CH_UTF16,
				   pwd, strlen(pwd),
				   &password.data, &password.length)) {
		DBG_WARNING("convert_string_talloc failed\n");
		code = EINVAL;
		goto out;
	}

	status = samdb_kpasswd_change_password(tmp_ctx,
					       ctx->db_ctx->lp_ctx,
					       ctx->db_ctx->ev_ctx,
					       ctx->session_info,
					       &password,
					       &reject_reason,
					       &dominfo,
					       &error_string,
					       &result);
	if (!NT_STATUS_IS_OK(status)) {
		DBG_WARNING("samdb_kpasswd_change_password failed: %s\n",
			    nt_errstr(status));
		code = KADM5_PASS_Q_GENERIC;
		krb5_set_error_message(ctx->context, code, "%s", error_string);
		goto out;
	}

	if (!NT_STATUS_IS_OK(result)) {
		code = mit_samba_change_pwd_error(ctx->context,
						  result,
						  reject_reason,
						  dominfo);
	}

out:
	talloc_free(tmp_ctx);

	return code;
}

void mit_samba_zero_bad_password_count(krb5_db_entry *db_entry)
{
	/* struct netr_SendToSamBase *send_to_sam = NULL; */
	struct samba_kdc_entry *p =
		talloc_get_type_abort(db_entry->e_data, struct samba_kdc_entry);
	struct ldb_dn *domain_dn;

	domain_dn = ldb_get_default_basedn(p->kdc_db_ctx->samdb);

	authsam_logon_success_accounting(p->kdc_db_ctx->samdb,
					 p->msg,
					 domain_dn,
					 true,
					 NULL, NULL);
	/* TODO: RODC support */
}


void mit_samba_update_bad_password_count(krb5_db_entry *db_entry)
{
	struct samba_kdc_entry *p =
		talloc_get_type_abort(db_entry->e_data, struct samba_kdc_entry);

	authsam_update_bad_pwd_count(p->kdc_db_ctx->samdb,
				     p->msg,
				     ldb_get_default_basedn(p->kdc_db_ctx->samdb));
}

bool mit_samba_princ_needs_pac(krb5_db_entry *db_entry)
{
	struct samba_kdc_entry *skdc_entry =
		talloc_get_type_abort(db_entry->e_data, struct samba_kdc_entry);

	return samba_princ_needs_pac(skdc_entry);
}