talloc_stack: Call talloc destructors while frame is still around

[Samba.git] / lib / audit_logging / audit_logging.c

/*
   common routines for audit logging

   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2018

   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/>.
*/

/*
 * Error handling:
 *
 * The json_object structure contains a boolean 'error'.  This is set whenever
 * an error is detected. All the library functions check this flag and return
 * immediately if it is set.
 *
 *      if (object->error) {
 *              return;
 *      }
 *
 * This allows the operations to be sequenced naturally with out the clutter
 * of error status checks.
 *
 *      audit = json_new_object();
 *      json_add_version(&audit, OPERATION_MAJOR, OPERATION_MINOR);
 *      json_add_int(&audit, "statusCode", ret);
 *      json_add_string(&audit, "status", ldb_strerror(ret));
 *      json_add_string(&audit, "operation", operation);
 *      json_add_address(&audit, "remoteAddress", remote);
 *      json_add_sid(&audit, "userSid", sid);
 *      json_add_string(&audit, "dn", dn);
 *      json_add_guid(&audit, "transactionId", &ac->transaction_guid);
 *      json_add_guid(&audit, "sessionId", unique_session_token);
 *
 * The assumptions are that errors will be rare, and that the audit logging
 * code should not cause failures. So errors are logged but processing
 * continues on a best effort basis.
 */

#include "includes.h"

#include "librpc/ndr/libndr.h"
#include "lib/tsocket/tsocket.h"
#include "libcli/security/dom_sid.h"
#include "lib/messaging/messaging.h"
#include "auth/common_auth.h"
#include "audit_logging.h"

/*
 * @brief Get a human readable timestamp.
 *
 * Returns the current time formatted as
 *  "Tue, 14 Mar 2017 08:38:42.209028 NZDT"
 *
 * The returned string is allocated by talloc in the supplied context.
 * It is the callers responsibility to free it.
 *
 * @param mem_ctx talloc memory context that owns the returned string.
 *
 * @return a human readable time stamp.
 *
 */
char* audit_get_timestamp(TALLOC_CTX *frame)
{
        char buffer[40];        /* formatted time less usec and timezone */
        char tz[10];            /* formatted time zone                   */
        struct tm* tm_info;     /* current local time                    */
        struct timeval tv;      /* current system time                   */
        int r;                  /* response code from gettimeofday       */
        char * ts;              /* formatted time stamp                  */

        r = gettimeofday(&tv, NULL);
        if (r) {
                DBG_ERR("Unable to get time of day: (%d) %s\n",
                        errno,
                        strerror(errno));
                return NULL;
        }

        tm_info = localtime(&tv.tv_sec);
        if (tm_info == NULL) {
                DBG_ERR("Unable to determine local time\n");
                return NULL;
        }

        strftime(buffer, sizeof(buffer)-1, "%a, %d %b %Y %H:%M:%S", tm_info);
        strftime(tz, sizeof(tz)-1, "%Z", tm_info);
        ts = talloc_asprintf(frame, "%s.%06ld %s", buffer, tv.tv_usec, tz);
        if (ts == NULL) {
                DBG_ERR("Out of memory formatting time stamp\n");
        }
        return ts;
}

/*
 * @brief write an audit message to the audit logs.
 *
 * Write a human readable text audit message to the samba logs.
 *
 * @param prefix Text to be printed at the start of the log line
 * @param message The content of the log line.
 * @param debub_class The debug class to log the message with.
 * @param debug_level The debug level to log the message with.
 */
void audit_log_human_text(const char* prefix,
                          const char* message,
                          int debug_class,
                          int debug_level)
{
        DEBUGC(debug_class, debug_level, ("%s %s\n", prefix, message));
}

#ifdef HAVE_JANSSON
/*
 * @brief write a json object to the samba audit logs.
 *
 * Write the json object to the audit logs as a formatted string
 *
 * @param prefix Text to be printed at the start of the log line
 * @param message The content of the log line.
 * @param debub_class The debug class to log the message with.
 * @param debug_level The debug level to log the message with.
 */
void audit_log_json(const char* prefix,
                    struct json_object* message,
                    int debug_class,
                    int debug_level)
{
        TALLOC_CTX *ctx = talloc_new(NULL);
        char *s = json_to_string(ctx, message);
        DEBUGC(debug_class, debug_level, ("JSON %s: %s\n", prefix, s));
        TALLOC_FREE(ctx);
}

/*
 * @brief get a connection to the messaging event server.
 *
 * Get a connection to the messaging event server registered by server_name.
 *
 * @param msg_ctx a valid imessaging_context.
 * @param server_name name of messaging event server to connect to.
 * @param server_id The event server details to populate
 *
 * @return NTSTATUS
 */
static NTSTATUS get_event_server(
        struct imessaging_context *msg_ctx,
        const char *server_name,
        struct server_id *event_server)
{
        NTSTATUS status;
        TALLOC_CTX *frame = talloc_stackframe();
        unsigned num_servers, i;
        struct server_id *servers;

        status = irpc_servers_byname(
                msg_ctx,
                frame,
                server_name,
                &num_servers,
                &servers);

        if (!NT_STATUS_IS_OK(status)) {
                DBG_NOTICE(
                        "Failed to find '%s' registered on the message bus to "
                        "send audit events to: %s\n",
                        server_name,
                        nt_errstr(status));
                TALLOC_FREE(frame);
                return status;
        }

        /*
         * Select the first server that is listening, because we get
         * connection refused as NT_STATUS_OBJECT_NAME_NOT_FOUND
         * without waiting
         */
        for (i = 0; i < num_servers; i++) {
                status = imessaging_send(
                        msg_ctx,
                        servers[i],
                        MSG_PING,
                        &data_blob_null);
                if (NT_STATUS_IS_OK(status)) {
                        *event_server = servers[i];
                        TALLOC_FREE(frame);
                        return NT_STATUS_OK;
                }
        }
        DBG_NOTICE(
                "Failed to find '%s' registered on the message bus to "
                "send audit events to: %s\n",
                server_name,
                nt_errstr(status));
        TALLOC_FREE(frame);
        return NT_STATUS_OBJECT_NAME_NOT_FOUND;
}

/*
 * @brief send an audit message to a messaging event server.
 *
 * Send the message to a registered and listening event server.
 * Note: Any errors are logged, and the message is not sent.  This is to ensure
 *       that a poorly behaved event server does not impact Samba.
 *
 *       As it is possible to lose messages, especially during server
 *       shut down, currently this function is primarily intended for use
 *       in integration tests.
 *
 * @param msg_ctx an imessaging_context, can be NULL in which case no message
 *                will be sent.
 * @param server_name the naname of the event server to send the message to.
 * @param messag_type A message type defined in librpc/idl/messaging.idl
 * @param message The message to send.
 *
 */
void audit_message_send(
        struct imessaging_context *msg_ctx,
        const char *server_name,
        uint32_t message_type,
        struct json_object *message)
{
        struct server_id event_server;
        NTSTATUS status;

        const char *message_string = NULL;
        DATA_BLOB message_blob = data_blob_null;
        TALLOC_CTX *ctx = talloc_new(NULL);

        if (msg_ctx == NULL) {
                DBG_DEBUG("No messaging context\n");
                TALLOC_FREE(ctx);
                return;
        }

        /* Need to refetch the address each time as the destination server may
         * have disconnected and reconnected in the interim, in which case
         * messages may get lost
         */
        status = get_event_server(msg_ctx, server_name, &event_server);
        if (!NT_STATUS_IS_OK(status) &&
            !NT_STATUS_EQUAL(status, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
                DBG_ERR("get_event_server for %s returned (%s)\n",
                        server_name,
                        nt_errstr(status));
                TALLOC_FREE(ctx);
                return;
        }

        message_string = json_to_string(ctx, message);
        message_blob = data_blob_string_const(message_string);
        status = imessaging_send(
                msg_ctx,
                event_server,
                message_type,
                &message_blob);

        /*
         * If the server crashed, try to find it again
         */
        if (NT_STATUS_EQUAL(status, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
                status = get_event_server(msg_ctx, server_name, &event_server);
                if (!NT_STATUS_IS_OK(status) &&
                    !NT_STATUS_EQUAL(status, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
                        DBG_ERR("get_event_server for %s returned (%s)\n",
                                server_name,
                                nt_errstr(status));
                        TALLOC_FREE(ctx);
                        return;
                }
                imessaging_send(
                        msg_ctx,
                        event_server,
                        message_type,
                        &message_blob);
        }
        TALLOC_FREE(ctx);
}

/*
 * @brief Create a new struct json_object, wrapping a JSON Object.
 *
 * Create a new json object, the json_object wraps the underlying json
 * implementations JSON Object representation.
 *
 * Free with a call to json_free_object, note that the jansson inplementation
 * allocates memory with malloc and not talloc.
 *
 * @return a struct json_object, error will be set to true if the object
 *         could not be created.
 *
 */
struct json_object json_new_object(void) {

        struct json_object object;
        object.error = false;

        object.root = json_object();
        if (object.root == NULL) {
                object.error = true;
                DBG_ERR("Unable to create json_object\n");
        }
        return object;
}

/*
 * @brief Create a new struct json_object wrapping a JSON Array.
 *
 * Create a new json object, the json_object wraps the underlying json
 * implementations JSON Array representation.
 *
 * Free with a call to json_free_object, note that the jansson inplementation
 * allocates memory with malloc and not talloc.
 *
 * @return a struct json_object, error will be set to true if the array
 *         could not be created.
 *
 */
struct json_object json_new_array(void) {

        struct json_object array;
        array.error = false;

        array.root = json_array();
        if (array.root == NULL) {
                array.error = true;
                DBG_ERR("Unable to create json_array\n");
        }
        return array;
}


/*
 * @brief free and invalidate a previously created JSON object.
 *
 * Release any resources owned by a json_object, and then mark the structure
 * as invalid.  It is safe to call this multiple times on an object.
 *
 */
void json_free(struct json_object *object)
{
        if (object->root != NULL) {
                json_decref(object->root);
        }
        object->root = NULL;
        object->error = true;
}

/*
 * @brief is the current JSON object invalid?
 *
 * Check the state of the object to determine if it is invalid.
 *
 * @return is the object valid?
 *
 */
bool json_is_invalid(struct json_object *object)
{
        return object->error;
}

/*
 * @brief Add an integer value to a JSON object.
 *
 * Add an integer value named 'name' to the json object.
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 * @param name the name of the value.
 * @param value the value.
 *
 */
void json_add_int(struct json_object *object,
                  const char* name,
                  const int value)
{
        int rc = 0;

        if (object->error) {
                return;
        }

        rc = json_object_set_new(object->root, name, json_integer(value));
        if (rc) {
                DBG_ERR("Unable to set name [%s] value [%d]\n", name, value);
                object->error = true;
        }
}

/*
 * @brief Add a boolean value to a JSON object.
 *
 * Add a boolean value named 'name' to the json object.
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 * @param name the name.
 * @param value the value.
 *
 */
void json_add_bool(struct json_object *object,
                   const char* name,
                   const bool value)
{
        int rc = 0;

        if (object->error) {
                return;
        }

        rc = json_object_set_new(object->root, name, json_boolean(value));
        if (rc) {
                DBG_ERR("Unable to set name [%s] value [%d]\n", name, value);
                object->error = true;
        }

}

/*
 * @brief Add a string value to a JSON object.
 *
 * Add a string value named 'name' to the json object.
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 * @param name the name.
 * @param value the value.
 *
 */
void json_add_string(struct json_object *object,
                     const char* name,
                     const char* value)
{
        int rc = 0;

        if (object->error) {
                return;
        }

        if (value) {
                rc = json_object_set_new(
                        object->root,
                        name,
                        json_string(value));
        } else {
                rc = json_object_set_new(object->root, name, json_null());
        }
        if (rc) {
                DBG_ERR("Unable to set name [%s] value [%s]\n", name, value);
                object->error = true;
        }
}

/*
 * @brief Assert that the current JSON object is an array.
 *
 * Check that the current object is a JSON array, and if not
 * invalidate the object. We also log an error message as this indicates
 * bug in the calling code.
 *
 * @param object the JSON object to be validated.
 */
void json_assert_is_array(struct json_object *array) {

        if (array->error) {
                return;
        }

        if (json_is_array(array->root) == false) {
                DBG_ERR("JSON object is not an array\n");
                array->error = true;
                return;
        }
}

/*
 * @brief Add a JSON object to a JSON object.
 *
 * Add a JSON object named 'name' to the json object.
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 * @param name the name.
 * @param value the value.
 *
 */
void json_add_object(struct json_object *object,
                     const char* name,
                     struct json_object *value)
{
        int rc = 0;
        json_t *jv = NULL;

        if (object->error) {
                return;
        }

        if (value != NULL && value->error) {
                object->error = true;
                return;
        }

        jv = value == NULL ? json_null() : value->root;

        if (json_is_array(object->root)) {
                rc = json_array_append_new(object->root, jv);
        } else if (json_is_object(object->root)) {
                rc = json_object_set_new(object->root, name,  jv);
        } else {
                DBG_ERR("Invalid JSON object type\n");
                object->error = true;
        }
        if (rc) {
                DBG_ERR("Unable to add object [%s]\n", name);
                object->error = true;
        }
}

/*
 * @brief Add a string to a JSON object, truncating if necessary.
 *
 *
 * Add a string value named 'name' to the json object, the string will be
 * truncated if it is more than len characters long. If len is 0 the value
 * is encoded as a JSON null.
 *
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 * @param name the name.
 * @param value the value.
 * @param len the maximum number of characters to be copied.
 *
 */
void json_add_stringn(struct json_object *object,
                      const char *name,
                      const char *value,
                      const size_t len)
{

        int rc = 0;
        if (object->error) {
                return;
        }

        if (value != NULL && len > 0) {
                char buffer[len+1];
                strncpy(buffer, value, len);
                buffer[len] = '\0';
                rc = json_object_set_new(object->root,
                                         name,
                                         json_string(buffer));
        } else {
                rc = json_object_set_new(object->root, name, json_null());
        }
        if (rc) {
                DBG_ERR("Unable to set name [%s] value [%s]\n", name, value);
                object->error = true;
        }
}

/*
 * @brief Add a version object to a JSON object
 *
 * Add a version object to the JSON object
 *      "version":{"major":1, "minor":0}
 *
 * The version tag is intended to aid the processing of the JSON messages
 * The major version number should change when an attribute is:
 *  - renamed
 *  - removed
 *  - its meaning changes
 *  - its contents change format
 * The minor version should change whenever a new attribute is added and for
 * minor bug fixes to an attributes content.
 *
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 * @param major the major version number
 * @param minor the minor version number
 */
void json_add_version(struct json_object *object, int major, int minor)
{
        struct json_object version = json_new_object();
        json_add_int(&version, "major", major);
        json_add_int(&version, "minor", minor);
        json_add_object(object, "version", &version);
}

/*
 * @brief add an ISO 8601 timestamp to the object.
 *
 * Add the current date and time as a timestamp in ISO 8601 format
 * to a JSON object
 *
 * "timestamp":"2017-03-06T17:18:04.455081+1300"
 *
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 */
void json_add_timestamp(struct json_object *object)
{
        char buffer[40];        /* formatted time less usec and timezone */
        char timestamp[65];     /* the formatted ISO 8601 time stamp     */
        char tz[10];            /* formatted time zone                   */
        struct tm* tm_info;     /* current local time                    */
        struct timeval tv;      /* current system time                   */
        int r;                  /* response code from gettimeofday       */

        if (object->error) {
                return;
        }

        r = gettimeofday(&tv, NULL);
        if (r) {
                DBG_ERR("Unable to get time of day: (%d) %s\n",
                        errno,
                        strerror(errno));
                object->error = true;
                return;
        }

        tm_info = localtime(&tv.tv_sec);
        if (tm_info == NULL) {
                DBG_ERR("Unable to determine local time\n");
                object->error = true;
                return;
        }

        strftime(buffer, sizeof(buffer)-1, "%Y-%m-%dT%T", tm_info);
        strftime(tz, sizeof(tz)-1, "%z", tm_info);
        snprintf(
                timestamp,
                sizeof(timestamp),
                "%s.%06ld%s",
                buffer,
                tv.tv_usec,
                tz);
        json_add_string(object, "timestamp", timestamp);
}


/*
 *@brief Add a tsocket_address to a JSON object
 *
 * Add the string representation of a Samba tsocket_address to the object.
 *
 * "localAddress":"ipv6::::0"
 *
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 * @param name the name.
 * @param address the tsocket_address.
 *
 */
void json_add_address(struct json_object *object,
                      const char *name,
                      const struct tsocket_address *address)
{

        if (object->error) {
                return;
        }
        if (address == NULL) {
                int rc = json_object_set_new(object->root, name, json_null());
                if (rc) {
                        DBG_ERR("Unable to set address [%s] to null\n", name);
                        object->error = true;
                }
        } else {
                TALLOC_CTX *ctx = talloc_new(NULL);
                char *s = NULL;

                s = tsocket_address_string(address, ctx);
                json_add_string(object, name, s);
                TALLOC_FREE(ctx);
        }
}

/*
 * @brief Add a formatted string representation of a sid to a json object.
 *
 * Add the string representation of a Samba sid to the object.
 *
 * "sid":"S-1-5-18"
 *
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 * @param name the name.
 * @param sid the sid
 *
 */
void json_add_sid(struct json_object *object,
                  const char *name,
                  const struct dom_sid *sid)
{

        if (object->error) {
                return;
        }
        if (sid == NULL) {
                int rc = json_object_set_new(object->root, name, json_null());
                if (rc) {
                        DBG_ERR("Unable to set SID [%s] to null\n", name);
                        object->error = true;
                }
        } else {
                char sid_buf[DOM_SID_STR_BUFLEN];

                dom_sid_string_buf(sid, sid_buf, sizeof(sid_buf));
                json_add_string(object, name, sid_buf);
        }
}

/*
 * @brief Add a formatted string representation of a guid to a json object.
 *
 * Add the string representation of a Samba GUID to the object.
 *
 * "guid":"1fb9f2ee-2a4d-4bf8-af8b-cb9d4529a9ab"
 *
 * In the event of an error object will be invalidated.
 *
 * @param object the JSON object to be updated.
 * @param name the name.
 * @param guid the guid.
 *
 *
 */
void json_add_guid(struct json_object *object,
                   const char *name,
                   const struct GUID *guid)
{


        if (object->error) {
                return;
        }
        if (guid == NULL) {
                int rc = json_object_set_new(object->root, name, json_null());
                if (rc) {
                        DBG_ERR("Unable to set GUID [%s] to null\n", name);
                        object->error = true;
                }
        } else {
                char *guid_str;
                struct GUID_txt_buf guid_buff;

                guid_str = GUID_buf_string(guid, &guid_buff);
                json_add_string(object, name, guid_str);
        }
}


/*
 * @brief Convert a JSON object into a string
 *
 * Convert the jsom object into a string suitable for printing on a log line,
 * i.e. with no embedded line breaks.
 *
 * If the object is invalid it returns NULL.
 *
 * @param mem_ctx the talloc memory context owning the returned string
 * @param object the json object.
 *
 * @return A string representation of the object or NULL if the object
 *         is invalid.
 */
char *json_to_string(TALLOC_CTX *mem_ctx,
                     struct json_object *object)
{
        char *json = NULL;
        char *json_string = NULL;

        if (object->error) {
                return NULL;
        }

        /*
         * json_dumps uses malloc, so need to call free(json) to release
         * the memory
         */
        json = json_dumps(object->root, 0);
        if (json == NULL) {
                DBG_ERR("Unable to convert JSON object to string\n");
                return NULL;
        }

        json_string = talloc_strdup(mem_ctx, json);
        if (json_string == NULL) {
                free(json);
                DBG_ERR("Unable to copy JSON object string to talloc string\n");
                return NULL;
        }
        free(json);

        return json_string;
}

/*
 * @brief get a json array named "name" from the json object.
 *
 * Get the array attribute named name, creating it if it does not exist.
 *
 * @param object the json object.
 * @param name the name of the array attribute
 *
 * @return The array object, will be created if it did not exist.
 */
struct json_object json_get_array(struct json_object *object,
                                  const char* name)
{

        struct json_object array = json_new_array();
        json_t *a = NULL;

        if (object->error) {
                array.error = true;
                return array;
        }

        a = json_object_get(object->root, name);
        if (a == NULL) {
                return array;
        }
        json_array_extend(array.root, a);

        return array;
}

/*
 * @brief get a json object named "name" from the json object.
 *
 * Get the object attribute named name, creating it if it does not exist.
 *
 * @param object the json object.
 * @param name the name of the object attribute
 *
 * @return The object, will be created if it did not exist.
 */
struct json_object json_get_object(struct json_object *object,
                                   const char* name)
{

        struct json_object o = json_new_object();
        json_t *v = NULL;

        if (object->error) {
                o.error = true;
                return o;
        }

        v = json_object_get(object->root, name);
        if (v == NULL) {
                return o;
        }
        json_object_update(o.root, v);

        return o;
}
#endif