s4-kdc Add common setup, handle RODC setup case

This means we just set up the system_session etc in one place
and don't diverge between the MIT and Heimdal plugins.

We also now determine if we are an RODC and store some details
that we will need later.

Andrew Bartlett

1 files changed, 135 insertions, 0 deletions

diff --git a/source4/kdc/db-glue.c b/source4/kdc/db-glue.c
index bad32535029..2cda04bca8f 100644
--- a/source4/kdc/db-glue.c
+++ b/source4/kdc/db-glue.c
@@ -1565,3 +1565,138 @@ samba_kdc_check_pkinit_ms_upn_match(krb5_context context,
 	return ret;
 }
 
+NTSTATUS samba_kdc_setup_db_ctx(TALLOC_CTX *mem_ctx, struct samba_kdc_base_context *base_ctx,
+				struct samba_kdc_db_context **kdc_db_ctx_out)
+{
+	NTSTATUS nt_status;
+	int ldb_ret;
+	struct ldb_message *msg;
+	struct auth_session_info *session_info;
+	struct samba_kdc_db_context *kdc_db_ctx;
+	/* The idea here is very simple.  Using Kerberos to
+	 * authenticate the KDC to the LDAP server is higly likely to
+	 * be circular.
+	 *
+	 * In future we may set this up to use EXERNAL and SSL
+	 * certificates, for now it will almost certainly be NTLMSSP_SET_USERNAME
+	*/
+
+	kdc_db_ctx = talloc_zero(mem_ctx, struct samba_kdc_db_context);
+	if (kdc_db_ctx == NULL) {
+		return NT_STATUS_NO_MEMORY;
+	}
+	kdc_db_ctx->ev_ctx = base_ctx->ev_ctx;
+	kdc_db_ctx->lp_ctx = base_ctx->lp_ctx;
+
+#if 1
+	/* we would prefer to use system_session(), as that would
+	 * allow us to share the samdb backend context with other parts of the
+	 * system. For now we can't as we need to override the
+	 * credentials to set CRED_DONT_USE_KERBEROS, which would
+	 * break other users of the system_session */
+	DEBUG(0,("FIXME: Using new system session for hdb\n"));
+	nt_status = auth_system_session_info(kdc_db_ctx, base_ctx->lp_ctx, &session_info);
+	if (!NT_STATUS_IS_OK(nt_status)) {
+	       return nt_status;
+	}
+#else
+	session_info = system_session(kdc_db_ctx->lp_ctx);
+	if (session_info == NULL) {
+		return NT_STATUS_INTERNAL_ERROR;
+	}
+#endif
+
+	cli_credentials_set_kerberos_state(session_info->credentials,
+					   CRED_DONT_USE_KERBEROS);
+
+	/* Setup the link to LDB */
+	kdc_db_ctx->samdb = samdb_connect(kdc_db_ctx, base_ctx->ev_ctx,
+					  base_ctx->lp_ctx, session_info);
+	if (kdc_db_ctx->samdb == NULL) {
+		DEBUG(1, ("hdb_samba4_create: Cannot open samdb for KDC backend!"));
+		talloc_free(kdc_db_ctx);
+		return NT_STATUS_CANT_ACCESS_DOMAIN_INFO;
+	}
+
+	/* Find out our own krbtgt kvno */
+	ldb_ret = samdb_rodc(kdc_db_ctx->samdb, &kdc_db_ctx->rodc);
+	if (ldb_ret != LDB_SUCCESS) {
+		DEBUG(1, ("hdb_samba4_create: Cannot determine if we are an RODC in KDC backend: %s\n",
+			  ldb_errstring(kdc_db_ctx->samdb)));
+		talloc_free(kdc_db_ctx);
+		return NT_STATUS_CANT_ACCESS_DOMAIN_INFO;
+	}
+	if (kdc_db_ctx->rodc) {
+		int my_krbtgt_number;
+		const char *secondary_keytab[] = { "msDS-SecondaryKrbTgtNumber", NULL };
+		struct ldb_dn *account_dn;
+		struct ldb_dn *server_dn = samdb_server_dn(kdc_db_ctx->samdb, kdc_db_ctx);
+		if (!server_dn) {
+			DEBUG(1, ("hdb_samba4_create: Cannot determine server DN in KDC backend: %s\n",
+				  ldb_errstring(kdc_db_ctx->samdb)));
+			talloc_free(kdc_db_ctx);
+			return NT_STATUS_CANT_ACCESS_DOMAIN_INFO;
+		}
+
+		ldb_ret = samdb_reference_dn(kdc_db_ctx->samdb, kdc_db_ctx, server_dn,
+					     "serverReference", &account_dn);
+		if (ldb_ret != LDB_SUCCESS) {
+			DEBUG(1, ("hdb_samba4_create: Cannot determine server account in KDC backend: %s\n",
+				  ldb_errstring(kdc_db_ctx->samdb)));
+			talloc_free(kdc_db_ctx);
+			return NT_STATUS_CANT_ACCESS_DOMAIN_INFO;
+		}
+
+		ldb_ret = samdb_reference_dn(kdc_db_ctx->samdb, kdc_db_ctx, account_dn,
+					     "msDS-KrbTgtLink", &kdc_db_ctx->krbtgt_dn);
+		talloc_free(account_dn);
+		if (ldb_ret != LDB_SUCCESS) {
+			DEBUG(1, ("hdb_samba4_create: Cannot determine RODC krbtgt account in KDC backend: %s\n",
+				  ldb_errstring(kdc_db_ctx->samdb)));
+			talloc_free(kdc_db_ctx);
+			return NT_STATUS_CANT_ACCESS_DOMAIN_INFO;
+		}
+
+		ldb_ret = dsdb_search_one(kdc_db_ctx->samdb, kdc_db_ctx,
+					  &msg, kdc_db_ctx->krbtgt_dn, LDB_SCOPE_BASE,
+					  secondary_keytab,
+					  0,
+					  "(&(objectClass=user)(msDS-SecondaryKrbTgtNumber=*))");
+		if (ldb_ret != LDB_SUCCESS) {
+			DEBUG(1, ("hdb_samba4_create: Cannot read krbtgt account %s in KDC backend to get msDS-SecondaryKrbTgtNumber: %s: %s\n",
+				  ldb_dn_get_linearized(kdc_db_ctx->krbtgt_dn),
+				  ldb_errstring(kdc_db_ctx->samdb),
+				  ldb_strerror(ldb_ret)));
+			talloc_free(kdc_db_ctx);
+			return NT_STATUS_CANT_ACCESS_DOMAIN_INFO;
+		}
+		my_krbtgt_number = ldb_msg_find_attr_as_int(msg, "msDS-SecondaryKrbTgtNumber", -1);
+		if (my_krbtgt_number == -1) {
+			DEBUG(1, ("hdb_samba4_create: Cannot read msDS-SecondaryKrbTgtNumber from krbtgt account %s in KDC backend: got %d\n",
+				  ldb_dn_get_linearized(kdc_db_ctx->krbtgt_dn),
+				  my_krbtgt_number));
+			talloc_free(kdc_db_ctx);
+			return NT_STATUS_CANT_ACCESS_DOMAIN_INFO;
+		}
+		kdc_db_ctx->my_krbtgt_number = my_krbtgt_number;
+
+	} else {
+		kdc_db_ctx->my_krbtgt_number = 0;
+		ldb_ret = dsdb_search_one(kdc_db_ctx->samdb, kdc_db_ctx,
+					  &msg, NULL, LDB_SCOPE_SUBTREE,
+					  krbtgt_attrs,
+					  DSDB_SEARCH_SHOW_EXTENDED_DN,
+					  "(&(objectClass=user)(samAccountName=krbtgt))");
+
+		if (ldb_ret != LDB_SUCCESS) {
+			DEBUG(1, ("samba_kdc_fetch: could not find own KRBTGT in DB: %s\n", ldb_errstring(kdc_db_ctx->samdb)));
+			talloc_free(kdc_db_ctx);
+			return NT_STATUS_CANT_ACCESS_DOMAIN_INFO;
+		}
+		kdc_db_ctx->krbtgt_dn = talloc_steal(kdc_db_ctx, msg->dn);
+		kdc_db_ctx->my_krbtgt_number = 0;
+		talloc_free(msg);
+	}
+	*kdc_db_ctx_out = kdc_db_ctx;
+	return NT_STATUS_OK;
+}