docs(README): correct badge link path to fix docs rendering

Signed-off-by: Leonardo Grasso <me@leonardograsso.com>

CMakeLists.txt

@@ -19,6 +19,15 @@ option(BUILD_WARNINGS_AS_ERRORS "Enable building with -Wextra -Werror flags" OFF
 option(MINIMAL_BUILD "Build a minimal version of Falco, containing only the engine and basic input/output (EXPERIMENTAL)" OFF)
 option(MUSL_OPTIMIZED_BUILD "Enable if you want a musl optimized build" OFF)
 
+# We shouldn't need to set this, see https://gitlab.kitware.com/cmake/cmake/-/issues/16419
+option(EP_UPDATE_DISCONNECTED "ExternalProject update disconnected" OFF)
+if (${EP_UPDATE_DISCONNECTED})
+  set_property(
+    DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    PROPERTY EP_UPDATE_DISCONNECTED TRUE)
+endif()
+
+
 # Elapsed time
 # set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CMAKE_COMMAND} -E time") # TODO(fntlnz, leodido): add a flag to enable this
 
@@ -94,9 +103,6 @@ set(CMD_MAKE make)
 
 include(ExternalProject)
 
-# spdlog
-include(spdlog)
-
 # jq
 include(jq)
 

README.md

@@ -3,7 +3,7 @@
 
 <hr>
 
-[![Build Status](https://img.shields.io/circleci/build/github/falcosecurity/falco/master?style=for-the-badge)](https://circleci.com/gh/falcosecurity/falco) [![CII Best Practices Summary](https://img.shields.io/cii/summary/2317?label=CCI%20Best%20Practices&style=for-the-badge)](https://bestpractices.coreinfrastructure.org/projects/2317) [![GitHub](https://img.shields.io/github/license/falcosecurity/falco?style=for-the-badge)](COPYING)
+[![Build Status](https://img.shields.io/circleci/build/github/falcosecurity/falco/master?style=for-the-badge)](https://circleci.com/gh/falcosecurity/falco) [![CII Best Practices Summary](https://img.shields.io/cii/summary/2317?label=CCI%20Best%20Practices&style=for-the-badge)](https://bestpractices.coreinfrastructure.org/projects/2317) [![GitHub](https://img.shields.io/github/license/falcosecurity/falco?style=for-the-badge)](./COPYING)
 
 Want to talk? Join us on the [#falco](https://kubernetes.slack.com/archives/CMWH3EH32) channel in the [Kubernetes Slack](https://slack.k8s.io).
 
@@ -33,9 +33,9 @@ If you would like to run Falco in **production** please adhere to the [official
 | Tool     | Link                                                                                       | Note                                                               |
 |----------|--------------------------------------------------------------------------------------------|--------------------------------------------------------------------|
 | Helm     | [Chart Repository](https://github.com/falcosecurity/charts/tree/master/falco#introduction) | The Falco community offers regular helm chart releases.            |
-| Minikube | [Tutorial](https://falco.org/docs/third-party/#minikube)                                   | The Falco driver has been baked into minikube for easy deployment. |
-| Kind     | [Tutorial](https://falco.org/docs/third-party/#kind)                                       | Running Falco with kind requires a driver on the host system.      |
-| GKE      | [Tutorial](https://falco.org/docs/third-party/#gke)                                        | We suggest using the eBPF driver for running Falco on GKE.         |
+| Minikube | [Tutorial](https://falco.org/docs/getting-started/third-party/#minikube)                                   | The Falco driver has been baked into minikube for easy deployment. |
+| Kind     | [Tutorial](https://falco.org/docs/getting-started/third-party/#kind)                                       | Running Falco with kind requires a driver on the host system.      |
+| GKE      | [Tutorial](https://falco.org/docs/getting-started/third-party/#gke)                                        | We suggest using the eBPF driver for running Falco on GKE.         |
 
 ### Developing
 

cmake/modules/CPM.cmake

@@ -0,0 +1,19 @@
+set(CPM_DOWNLOAD_VERSION 0.27.2)
+
+if(CPM_SOURCE_CACHE)
+  set(CPM_DOWNLOAD_LOCATION "${CPM_SOURCE_CACHE}/cpm/CPM_${CPM_DOWNLOAD_VERSION}.cmake")
+elseif(DEFINED ENV{CPM_SOURCE_CACHE})
+  set(CPM_DOWNLOAD_LOCATION "$ENV{CPM_SOURCE_CACHE}/cpm/CPM_${CPM_DOWNLOAD_VERSION}.cmake")
+else()
+  set(CPM_DOWNLOAD_LOCATION "${CMAKE_BINARY_DIR}/cmake/CPM_${CPM_DOWNLOAD_VERSION}.cmake")
+endif()
+
+if(NOT (EXISTS ${CPM_DOWNLOAD_LOCATION}))
+  message(STATUS "Downloading CPM.cmake to ${CPM_DOWNLOAD_LOCATION}")
+  file(DOWNLOAD
+       https://github.com/TheLartians/CPM.cmake/releases/download/v${CPM_DOWNLOAD_VERSION}/CPM.cmake
+       ${CPM_DOWNLOAD_LOCATION}
+  )
+endif()
+
+include(${CPM_DOWNLOAD_LOCATION})

cmake/modules/OpenSSL.cmake

@@ -10,6 +10,7 @@
 # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 # specific language governing permissions and limitations under the License.
 #
+mark_as_advanced(OPENSSL_BINARY)
 if(NOT USE_BUNDLED_DEPS)
   find_package(OpenSSL REQUIRED)
   message(STATUS "Found openssl: include: ${OPENSSL_INCLUDE_DIR}, lib: ${OPENSSL_LIBRARIES}")
@@ -20,6 +21,8 @@ if(NOT USE_BUNDLED_DEPS)
     message(STATUS "Found openssl: binary: ${OPENSSL_BINARY}")
   endif()
 else()
+  mark_as_advanced(OPENSSL_BUNDLE_DIR OPENSSL_INSTALL_DIR OPENSSL_INCLUDE_DIR
+    OPENSSL_LIBRARY_SSL OPENSSL_LIBRARY_CRYPTO)
   set(OPENSSL_BUNDLE_DIR "${PROJECT_BINARY_DIR}/openssl-prefix/src/openssl")
   set(OPENSSL_INSTALL_DIR "${OPENSSL_BUNDLE_DIR}/target")
   set(OPENSSL_INCLUDE_DIR "${PROJECT_BINARY_DIR}/openssl-prefix/src/openssl/include")

cmake/modules/gRPC.cmake

@@ -22,6 +22,7 @@ if(NOT USE_BUNDLED_DEPS)
   endif()
 
   # c-ares
+  mark_as_advanced(CARES_INCLUDE CARES_LIB)
   find_path(CARES_INCLUDE NAMES ares.h)
   find_library(CARES_LIB NAMES libcares.so)
   if(CARES_INCLUDE AND CARES_LIB)
@@ -31,6 +32,7 @@ if(NOT USE_BUNDLED_DEPS)
   endif()
 
   # protobuf
+  mark_as_advanced(PROTOC PROTOBUF_INCLUDE PROTOBUF_LIB)
   find_program(PROTOC NAMES protoc)
   find_path(PROTOBUF_INCLUDE NAMES google/protobuf/message.h)
   find_library(PROTOBUF_LIB NAMES libprotobuf.so)
@@ -43,6 +45,7 @@ if(NOT USE_BUNDLED_DEPS)
   endif()
 
   # gpr
+  mark_as_advanced(GPR_LIB)
   find_library(GPR_LIB NAMES gpr)
 
   if(GPR_LIB)
@@ -52,12 +55,16 @@ if(NOT USE_BUNDLED_DEPS)
   endif()
 
   # gRPC todo(fntlnz, leodido): check that gRPC version is greater or equal than 1.8.0
+  mark_as_advanced(GRPC_INCLUDE GRPC_SRC
+    GRPC_LIB GRPC_LIBS_ABSOLUTE  GRPCPP_LIB GRPC_CPP_PLUGIN)
   find_path(GRPCXX_INCLUDE NAMES grpc++/grpc++.h)
   if(GRPCXX_INCLUDE)
     set(GRPC_INCLUDE ${GRPCXX_INCLUDE})
+    unset(GRPCXX_INCLUDE CACHE)
   else()
     find_path(GRPCPP_INCLUDE NAMES grpcpp/grpcpp.h)
     set(GRPC_INCLUDE ${GRPCPP_INCLUDE})
+    unset(GRPCPP_INCLUDE CACHE)
     add_definitions(-DGRPC_INCLUDE_IS_GRPCPP=1)
   endif()
   find_library(GRPC_LIB NAMES grpc)

cmake/modules/jq.cmake

@@ -10,6 +10,7 @@
 # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 # specific language governing permissions and limitations under the License.
 #
+mark_as_advanced(JQ_INCLUDE JQ_LIB)
 if (NOT USE_BUNDLED_DEPS)
     find_path(JQ_INCLUDE jq.h PATH_SUFFIXES jq)
     find_library(JQ_LIB NAMES jq)

cmake/modules/spdlog.cmake

@@ -1,25 +0,0 @@
-#
-# Copyright (C) 2020 The Falco Authors.
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
-# the License. You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
-# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
-# specific language governing permissions and limitations under the License.
-#
-
-
-set(SPDLOG_PREFIX "${PROJECT_BINARY_DIR}/spdlog-prefix")
-set(SPDLOG_INCLUDE_DIR "${SPDLOG_PREFIX}/src/spdlog/include")
-message(STATUS "Using bundled spdlog in '${SPDLOG_INCLUDE_DIR}'")
-
-ExternalProject_Add(
-  spdlog
-  URL "https://github.com/gabime/spdlog/archive/v1.8.1.tar.gz"
-  URL_HASH "SHA256=5197b3147cfcfaa67dd564db7b878e4a4b3d9f3443801722b3915cdeced656cb"
-  BUILD_COMMAND ""
-  INSTALL_COMMAND ""
-)

cmake/modules/static-analysis.cmake

@@ -3,6 +3,7 @@ file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/static-analysis-reports)
 file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/static-analysis-reports/cppcheck)
 
 # cppcheck
+mark_as_advanced(CPPCHECK CPPCHECK_HTMLREPORT)
 find_program(CPPCHECK cppcheck)
 find_program(CPPCHECK_HTMLREPORT cppcheck-htmlreport)
 

cmake/modules/yaml-cpp.cmake

@@ -10,6 +10,7 @@
 # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 # specific language governing permissions and limitations under the License.
 #
+mark_as_advanced(YAMLCPP_INCLUDE_DIR YAMLCPP_LIB)
 if(NOT USE_BUNDLED_DEPS)
   find_path(YAMLCPP_INCLUDE_DIR NAMES yaml-cpp/yaml.h)
   find_library(YAMLCPP_LIB NAMES yaml-cpp)

documentation/CMakeLists.txt

@@ -0,0 +1,35 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+project(FalcoDocs)
+
+# Dependencies
+
+include(../cmake/modules/CPM.cmake)
+
+CPMAddPackage(NAME Falco SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/..)
+
+CPMAddPackage(
+  NAME MCSS
+  DOWNLOAD_ONLY YES
+  GITHUB_REPOSITORY mosra/m.css
+  GIT_TAG 42d4a9a48f31f5df6e246c948403b54b50574a2a
+)
+
+# Doxygen variables
+
+set(DOXYGEN_PROJECT_NAME Falco)
+set(DOXYGEN_PROJECT_VERSION ${FALCO_VERSION})
+set(DOXYGEN_PROJECT_ROOT "${CMAKE_CURRENT_LIST_DIR}/..")
+set(DOXYGEN_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/doxygen")
+
+configure_file(${CMAKE_CURRENT_LIST_DIR}/Doxyfile ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
+
+configure_file(${CMAKE_CURRENT_LIST_DIR}/conf.py ${CMAKE_CURRENT_BINARY_DIR}/conf.py)
+
+add_custom_target(
+  GenerateDocs
+  ${CMAKE_COMMAND} -E make_directory "${DOXYGEN_OUTPUT_DIRECTORY}"
+  COMMAND "${MCSS_SOURCE_DIR}/documentation/doxygen.py" "${CMAKE_CURRENT_BINARY_DIR}/conf.py"
+  COMMAND echo "Docs written to: ${DOXYGEN_OUTPUT_DIRECTORY}"
+  WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
+)

documentation/Doxyfile

@@ -0,0 +1,31 @@
+# Configuration for Doxygen for use with CMake
+# Only options that deviate from the default are included
+# To create a new Doxyfile containing all available options, call `doxygen -g`
+
+# Get Project name and version from CMake
+PROJECT_NAME = @DOXYGEN_PROJECT_NAME@
+PROJECT_NUMBER = @DOXYGEN_PROJECT_VERSION@
+
+# Add sources
+INPUT = @DOXYGEN_PROJECT_ROOT@/README.md @DOXYGEN_PROJECT_ROOT@/userspace @DOXYGEN_PROJECT_ROOT@/documentation/pages
+EXTRACT_ALL = YES
+RECURSIVE = YES
+OUTPUT_DIRECTORY = @DOXYGEN_OUTPUT_DIRECTORY@
+
+# Use the README as a main page
+USE_MDFILE_AS_MAINPAGE = @DOXYGEN_PROJECT_ROOT@/README.md
+
+# Set relative include paths
+FULL_PATH_NAMES = YES
+STRIP_FROM_PATH = @DOXYGEN_PROJECT_ROOT@/userspace @DOXYGEN_PROJECT_ROOT@
+
+# We only need XML output because use m.css to generate the html documentation
+GENERATE_XML = YES
+GENERATE_HTML = NO
+GENERATE_LATEX = NO
+XML_PROGRAMLISTING = NO
+CREATE_SUBDIRS = NO
+
+# Include all directories, files and namespaces in the documentation
+# Disable to include only explicitly documented objects
+M_SHOW_UNDOCUMENTED = YES

documentation/conf.py

@@ -0,0 +1,19 @@
+DOXYFILE = 'Doxyfile'
+
+LINKS_NAVBAR1 = [
+    (None, 'pages', [(None, 'about')]),
+    (None, 'namespaces', []),
+]
+
+# Add your own navbar links using the code below.
+# To find the valid link names, you can inspect the URL of a generated documentation site.
+
+# LINKS_NAVBAR1 = [
+#     (None, 'pages', [(None, 'about')]),
+#     (None, 'namespaces', [(None, 'namespacexyz')]),
+# ]
+#
+# LINKS_NAVBAR2 = [
+#     (None, 'annotated', [(None, 'classxyz_1_1_xyz')]),
+#     (None, 'files', [(None, 'xyz_8h')]),
+# ]

documentation/pages/about.dox

@@ -0,0 +1,4 @@
+/** @page about About
+  @section doc Falco Documentation
+  This is the documentation for the Falco project.
+*/

falco.yaml

@@ -87,6 +87,23 @@ syscall_event_drops:
   rate: .03333
   max_burst: 10
 
+# Falco continuously monitors outputs performance. When an output channel does not allow
+# to deliver an alert within a given deadline, an error is reported indicating
+# which output is blocking notifications.
+# The timeout error will be reported to the log according to the above log_* settings.
+# Note that the notification will not be discarded from the output queue; thus,
+# output channels may indefinitely remain blocked.
+# An output timeout error indeed indicate a misconfiguration issue or I/O problems
+# that cannot be recovered by Falco and should be fixed by the user.
+#
+# The "output_timeout" value specifies the duration in milliseconds to wait before
+# considering the deadline exceed.
+#
+# With a 2000ms default, the notification consumer can block the Falco output
+# for up to 2 seconds without reaching the timeout.
+
+output_timeout: 2000
+
 # A throttling mechanism implemented as a token bucket limits the
 # rate of falco notifications. This throttling is controlled by the following configuration
 # options:

rules/falco_rules.yaml

@@ -1612,7 +1612,7 @@
 # to change thread namespace without having to copy and override the
 # entire change thread namespace rule.
 - list: user_known_change_thread_namespace_binaries
-  items: []
+  items: [crio, multus]
 
 - macro: user_known_change_thread_namespace_activities
   condition: (never_true)
@@ -3070,6 +3070,22 @@
   priority: WARNING
   tags: [process]
 
+- list: run_as_root_image_list
+  items: []
+
+- macro: user_known_run_as_root_container
+  condition: (container.image.repository in (run_as_root_image_list))
+
+# The rule is disabled by default and should be enabled when non-root container policy has been applied.
+# Note the rule will not work as expected when usernamespace is applied, e.g. userns-remap is enabled.
+- rule: Container Run as Root User
+  desc: Detected container running as root user
+  condition: spawned_process and container and proc.vpid=1 and user.uid=0 and not user_known_run_as_root_container
+  enabled: false
+  output: Container launched with root user privilege (uid=%user.uid container_id=%container.id container_name=%container.name image=%container.image.repository:%container.image.tag)
+  priority: INFO
+  tags: [container, process]
+
 # Application rules have moved to application_rules.yaml. Please look
 # there if you want to enable them by adding to
 # falco_rules.local.yaml.

userspace/falco/CMakeLists.txt

@@ -33,7 +33,6 @@ set(
   "${PROJECT_SOURCE_DIR}/userspace/engine"
   "${PROJECT_BINARY_DIR}/userspace/falco"
   "${PROJECT_BINARY_DIR}/driver/src"
-  "${SPDLOG_INCLUDE_DIR}"
   "${STRING_VIEW_LITE_INCLUDE}"
   "${YAMLCPP_INCLUDE_DIR}"
   "${CMAKE_CURRENT_BINARY_DIR}"
@@ -42,7 +41,6 @@ set(
 
 set(
   FALCO_DEPENDENCIES
-  spdlog
   string-view-lite
   libyaml
   b64

userspace/falco/configuration.cpp

@@ -47,16 +47,6 @@ falco_configuration::~falco_configuration()
 	}
 }
 
-// If we don't have a configuration file, we just use stdout output and all other defaults
-void falco_configuration::init(list<string> &cmdline_options)
-{
-	init_cmdline_options(cmdline_options);
-
-	falco::outputs::config stdout_output;
-	stdout_output.name = "stdout";
-	m_outputs.push_back(stdout_output);
-}
-
 void falco_configuration::init(string conf_filename, list<string> &cmdline_options)
 {
 	string m_config_file = conf_filename;
@@ -176,6 +166,8 @@ void falco_configuration::init(string conf_filename, list<string> &cmdline_optio
 
 	falco_logger::set_level(m_log_level);
 
+	m_output_timeout = m_config->get_scalar<uint32_t>("output_timeout", 2000);
+
 	m_notifications_rate = m_config->get_scalar<uint32_t>("outputs", "rate", 1);
 	m_notifications_max_burst = m_config->get_scalar<uint32_t>("outputs", "max_burst", 1000);
 
@@ -346,4 +338,4 @@ void falco_configuration::set_cmdline_option(const string &opt)
 	{
 		m_config->set_scalar(keyval.first, keyval.second);
 	}
-}
+}

userspace/falco/configuration.h

@@ -204,6 +204,7 @@ public:
 
 	bool m_buffered_outputs;
 	bool m_time_format_iso_8601;
+	uint32_t m_output_timeout;
 
 	bool m_grpc_enabled;
 	uint32_t m_grpc_threadiness;

userspace/falco/falco.cpp

@@ -794,7 +794,7 @@ int falco_init(int argc, char **argv)
 				}
 				else
 				{
-					conf_filename = "";
+					throw std::invalid_argument("You must create a config file at " FALCO_SOURCE_CONF_FILE ", " FALCO_INSTALL_CONF_FILE " or by passing -c\n");
 				}
 			}
 		}
@@ -836,12 +836,7 @@ int falco_init(int argc, char **argv)
 		}
 		else
 		{
-			config.init(cmdline_options);
-			falco_logger::set_time_format_iso_8601(config.m_time_format_iso_8601);
-
-			// log after config init because config determines where logs go
-			falco_logger::log(LOG_INFO, "Falco version " + std::string(FALCO_VERSION) + " (driver version " + std::string(DRIVER_VERSION) + ")\n");
-			falco_logger::log(LOG_INFO, "Falco initialized. No configuration file found, proceeding with defaults\n");
+			throw std::runtime_error("Could not find configuration file at " + conf_filename);
 		}
 
 		if (rules_filenames.size())
@@ -972,6 +967,7 @@ int falco_init(int argc, char **argv)
 
 		outputs->init(config.m_json_output,
 			      config.m_json_include_output_property,
+			      config.m_output_timeout,
 			      config.m_notifications_rate, config.m_notifications_max_burst,
 			      config.m_buffered_outputs,
 			      config.m_time_format_iso_8601,

userspace/falco/falco_outputs.cpp

@@ -24,6 +24,7 @@ limitations under the License.
 
 #include "formats.h"
 #include "logger.h"
+#include "watchdog.h"
 
 #include "outputs_file.h"
 #include "outputs_program.h"
@@ -51,18 +52,26 @@ falco_outputs::~falco_outputs()
 {
 	if(m_initialized)
 	{
-		for(auto it = m_outputs.cbegin(); it != m_outputs.cend(); ++it)
+		this->stop_worker();
+		for(auto o : m_outputs)
 		{
-			(*it)->cleanup();
+			delete o;
 		}
 	}
 }
 
 void falco_outputs::init(bool json_output,
-			 bool json_include_output_property,
-			 uint32_t rate, uint32_t max_burst, bool buffered,
-			 bool time_format_iso_8601, string hostname)
+		  bool json_include_output_property,
+		  uint32_t timeout,
+		  uint32_t rate, uint32_t max_burst, bool buffered,
+		  bool time_format_iso_8601, std::string hostname)
 {
+	// Cannot be initialized more than one time.
+	if(m_initialized)
+	{
+		throw falco_exception("falco_outputs already initialized");
+	}
+
 	m_json_output = json_output;
 
 	// Note that falco_formats is already initialized by the engine,
@@ -71,17 +80,29 @@ void falco_outputs::init(bool json_output,
 	falco_formats::s_json_output = json_output;
 	falco_formats::s_json_include_output_property = json_include_output_property;
 
+	m_timeout = std::chrono::milliseconds(timeout);
+
 	m_notifications_tb.init(rate, max_burst);
 
 	m_buffered = buffered;
 	m_time_format_iso_8601 = time_format_iso_8601;
 	m_hostname = hostname;
 
+	m_worker_thread = std::thread(&falco_outputs::worker, this);
+
 	m_initialized = true;
 }
 
+// This function has to be called after init() since some configuration settings
+// need to be passed to the output plugins. Then, although the worker has started,
+// the worker is still on hold, waiting for a message.
+// Thus it is still safe to call add_output() before any message has been enqueued.
 void falco_outputs::add_output(falco::outputs::config oc)
 {
+	if(!m_initialized)
+	{
+		throw falco_exception("cannot add output: falco_outputs not initialized yet");
+	}
 
 	falco::outputs::abstract_output *oo;
 
@@ -129,6 +150,12 @@ void falco_outputs::handle_event(gen_event *evt, string &rule, string &source,
 		return;
 	}
 
+	falco_outputs::ctrl_msg cmsg = {};
+	cmsg.ts = evt->get_ts();
+	cmsg.priority = priority;
+	cmsg.source = source;
+	cmsg.rule = rule;
+
 	string sformat;
 	if(source == "syscall")
 	{
@@ -163,35 +190,38 @@ void falco_outputs::handle_event(gen_event *evt, string &rule, string &source,
 		sformat += " " + format;
 	}
 
-	string msg;
-	msg = falco_formats::format_event(evt, rule, source, falco_common::priority_names[priority], sformat);
+	cmsg.msg = falco_formats::format_event(evt, rule, source, falco_common::priority_names[priority], sformat);
+	cmsg.fields = falco_formats::resolve_tokens(evt, source, sformat);
 
-	for(auto it = m_outputs.cbegin(); it != m_outputs.cend(); ++it)
-	{
-		(*it)->output_event(evt, rule, source, priority, sformat, msg);
-	}
+	cmsg.type = ctrl_msg_type::CTRL_MSG_OUTPUT;
+	m_queue.push(cmsg);
 }
 
-void falco_outputs::handle_msg(uint64_t now,
+void falco_outputs::handle_msg(uint64_t ts,
 			       falco_common::priority_type priority,
 			       std::string &msg,
 			       std::string &rule,
 			       std::map<std::string, std::string> &output_fields)
 {
-	std::string full_msg;
+	falco_outputs::ctrl_msg cmsg = {};
+	cmsg.ts = ts;
+	cmsg.priority = priority;
+	cmsg.source = "internal";
+	cmsg.rule = rule;
+	cmsg.fields = output_fields;
 
 	if(m_json_output)
 	{
 		nlohmann::json jmsg;
 
 		// Convert the time-as-nanoseconds to a more json-friendly ISO8601.
-		time_t evttime = now / 1000000000;
+		time_t evttime = ts / 1000000000;
 		char time_sec[20]; // sizeof "YYYY-MM-DDTHH:MM:SS"
 		char time_ns[12];  // sizeof ".sssssssssZ"
 		string iso8601evttime;
 
 		strftime(time_sec, sizeof(time_sec), "%FT%T", gmtime(&evttime));
-		snprintf(time_ns, sizeof(time_ns), ".%09luZ", now % 1000000000);
+		snprintf(time_ns, sizeof(time_ns), ".%09luZ", ts % 1000000000);
 		iso8601evttime = time_sec;
 		iso8601evttime += time_ns;
 
@@ -201,15 +231,15 @@ void falco_outputs::handle_msg(uint64_t now,
 		jmsg["time"] = iso8601evttime;
 		jmsg["output_fields"] = output_fields;
 
-		full_msg = jmsg.dump();
+		cmsg.msg = jmsg.dump();
 	}
 	else
 	{
 		std::string timestr;
 		bool first = true;
 
-		sinsp_utils::ts_to_string(now, &timestr, false, true);
-		full_msg = timestr + ": " + falco_common::priority_names[priority] + " " + msg + " (";
+		sinsp_utils::ts_to_string(ts, &timestr, false, true);
+		cmsg.msg = timestr + ": " + falco_common::priority_names[priority] + " " + msg + " (";
 		for(auto &pair : output_fields)
 		{
 			if(first)
@@ -218,23 +248,95 @@ void falco_outputs::handle_msg(uint64_t now,
 			}
 			else
 			{
-				full_msg += " ";
+				cmsg.msg += " ";
 			}
-			full_msg += pair.first + "=" + pair.second;
+			cmsg.msg += pair.first + "=" + pair.second;
 		}
-		full_msg += ")";
+		cmsg.msg += ")";
 	}
 
-	for(auto it = m_outputs.cbegin(); it != m_outputs.cend(); ++it)
-	{
-		(*it)->output_msg(priority, full_msg);
-	}
+	cmsg.type = ctrl_msg_type::CTRL_MSG_OUTPUT;
+	m_queue.push(cmsg);
+}
+
+void falco_outputs::cleanup_outputs()
+{
+	this->push(falco_outputs::ctrl_msg_type::CTRL_MSG_CLEANUP);
 }
 
 void falco_outputs::reopen_outputs()
 {
-	for(auto it = m_outputs.cbegin(); it != m_outputs.cend(); ++it)
+	this->push(falco_outputs::ctrl_msg_type::CTRL_MSG_REOPEN);
+}
+
+void falco_outputs::stop_worker()
+{
+	watchdog<void *> wd;
+	wd.start([&](void *) -> void {
+		falco_logger::log(LOG_NOTICE, "output channels still blocked, discarding all remaining notifications\n");
+		m_queue.clear();
+		this->push(falco_outputs::ctrl_msg_type::CTRL_MSG_STOP);
+	});
+	wd.set_timeout(m_timeout, nullptr);
+
+	this->push(falco_outputs::ctrl_msg_type::CTRL_MSG_STOP);
+	if(m_worker_thread.joinable())
 	{
-		(*it)->reopen();
+		m_worker_thread.join();
 	}
 }
+
+inline void falco_outputs::push(ctrl_msg_type cmt)
+{
+	falco_outputs::ctrl_msg cmsg = {};
+	cmsg.type = cmt;
+	m_queue.push(cmsg);
+}
+
+// todo(leogr,leodido): this function is not supposed to throw exceptions, and with "noexcept",
+// the program is terminated if that occurs. Although that's the wanted behavior,
+// we still need to improve the error reporting since some inner functions can throw exceptions.
+void falco_outputs::worker() noexcept
+{
+	watchdog<std::string> wd;
+	wd.start([&](std::string payload) -> void {
+		falco_logger::log(LOG_CRIT, "\"" + payload + "\" output timeout, all output channels are blocked\n");
+	});
+
+	auto timeout = m_timeout;
+
+	falco_outputs::ctrl_msg cmsg;
+	do
+	{
+		// Block until a message becomes available.
+		m_queue.pop(cmsg);
+
+		for(const auto o : m_outputs)
+		{
+			wd.set_timeout(timeout, o->get_name());
+			try
+			{
+				switch(cmsg.type)
+				{
+					case ctrl_msg_type::CTRL_MSG_OUTPUT:
+						o->output(&cmsg);
+						break;
+					case ctrl_msg_type::CTRL_MSG_CLEANUP:
+					case ctrl_msg_type::CTRL_MSG_STOP:
+						o->cleanup();
+						break;
+					case ctrl_msg_type::CTRL_MSG_REOPEN:
+						o->reopen();
+						break;
+					default:
+						falco_logger::log(LOG_DEBUG, "Outputs worker received an unknown message type\n");	
+				}
+			}
+			catch(const exception &e)
+			{
+				falco_logger::log(LOG_ERR, o->get_name() + ": " + string(e.what()) + "\n");
+			}
+		}
+		wd.cancel_timeout();
+	} while(cmsg.type != ctrl_msg_type::CTRL_MSG_STOP);
+}

userspace/falco/falco_outputs.h

@@ -25,6 +25,7 @@ limitations under the License.
 #include "token_bucket.h"
 #include "falco_engine.h"
 #include "outputs.h"
+#include "tbb/concurrent_queue.h"
 
 //
 // This class acts as the primary interface between a program and the
@@ -39,25 +40,25 @@ public:
 
 	void init(bool json_output,
 		  bool json_include_output_property,
+		  uint32_t timeout,
 		  uint32_t rate, uint32_t max_burst, bool buffered,
 		  bool time_format_iso_8601, std::string hostname);
 
 	void add_output(falco::outputs::config oc);
 
-	//
-	// evt is an event that has matched some rule. Pass the event
-	// to all configured outputs.
-	//
+	// Format then send the event to all configured outputs (`evt` is an event that has matched some rule).
 	void handle_event(gen_event *evt, std::string &rule, std::string &source,
 			  falco_common::priority_type priority, std::string &format);
 
-	// Send a generic message to all outputs. Not necessarily associated with any event.
+	// Format then send a generic message to all outputs. Not necessarily associated with any event.
 	void handle_msg(uint64_t now,
 			falco_common::priority_type priority,
 			std::string &msg,
 			std::string &rule,
 			std::map<std::string, std::string> &output_fields);
 
+	void cleanup_outputs();
+
 	void reopen_outputs();
 
 private:
@@ -71,5 +72,28 @@ private:
 	bool m_buffered;
 	bool m_json_output;
 	bool m_time_format_iso_8601;
+	std::chrono::milliseconds m_timeout;
 	std::string m_hostname;
+
+	enum ctrl_msg_type
+	{
+		CTRL_MSG_STOP = 0,
+		CTRL_MSG_OUTPUT = 1,
+		CTRL_MSG_CLEANUP = 2,
+		CTRL_MSG_REOPEN = 3,
+	};
+
+	struct ctrl_msg : falco::outputs::message
+	{
+		ctrl_msg_type type;
+	};
+
+	typedef tbb::concurrent_bounded_queue<ctrl_msg> falco_outputs_cbq;
+
+	falco_outputs_cbq m_queue;
+
+	std::thread m_worker_thread;
+	inline void push(ctrl_msg_type cmt);
+	void worker() noexcept;
+	void stop_worker();
 };

userspace/falco/grpc_server_impl.cpp

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 #include "config_falco.h"
+#include "falco_engine_version.h"
 #include "grpc_server_impl.h"
 #include "grpc_queue.h"
 #include "logger.h"
@@ -75,6 +76,9 @@ void falco::grpc::server_impl::version(const context& ctx, const version::reques
 	auto& version = *res.mutable_version();
 	version = FALCO_VERSION;
 
+	res.set_engine_version(FALCO_ENGINE_VERSION);
+	res.set_engine_fields_checksum(FALCO_FIELDS_CHECKSUM); 
+
 	res.set_major(FALCO_VERSION_MAJOR);
 	res.set_minor(FALCO_VERSION_MINOR);
 	res.set_patch(FALCO_VERSION_PATCH);

userspace/falco/outputs.h

@@ -37,6 +37,21 @@ struct config
 	std::map<std::string, std::string> options;
 };
 
+//
+// The message to be outputted. It can either refer to:
+//  - an event that has matched some rule,
+//  - or a generic message (e.g., a drop alert).
+//
+struct message
+{
+	uint64_t ts;
+	falco_common::priority_type priority;
+	std::string msg;
+	std::string rule;
+	std::string source;
+	map<std::string, std::string> fields;
+};
+
 //
 // This class acts as the primary interface for implementing
 // a Falco output class.
@@ -45,6 +60,8 @@ struct config
 class abstract_output
 {
 public:
+	virtual ~abstract_output() {}
+
 	void init(config oc, bool buffered, std::string hostname)
 	{
 		m_oc = oc;
@@ -52,15 +69,19 @@ public:
 		m_hostname = hostname;
 	}
 
-	// Output an event that has matched some rule.
-	virtual void output_event(gen_event *evt, std::string &rule, std::string &source,
-				  falco_common::priority_type priority, std::string &format, std::string &msg) = 0;
+	// Return the output's name as per its configuration.
+	const std::string get_name() const
+	{
+		return m_oc.name;
+	}
 
-	// Output a generic message. Not necessarily associated with any event.
-	virtual void output_msg(falco_common::priority_type priority, std::string &msg) = 0;
+	// Output a message.
+	virtual void output(const message *msg) = 0;
 
+	// Possibly close the output and open it again.
 	virtual void reopen() {}
 
+	// Possibly flush the output.
 	virtual void cleanup() {}
 
 protected:

userspace/falco/outputs_file.cpp

@@ -31,16 +31,10 @@ void falco::outputs::output_file::open_file()
 	}
 }
 
-void falco::outputs::output_file::output_event(gen_event *evt, std::string &rule, std::string &source,
-					       falco_common::priority_type priority, std::string &format, std::string &msg)
-{
-	output_msg(priority, msg);
-}
-
-void falco::outputs::output_file::output_msg(falco_common::priority_type priority, std::string &msg)
+void falco::outputs::output_file::output(const message *msg)
 {
 	open_file();
-	m_outfile << msg + "\n";
+	m_outfile << msg->msg + "\n";
 
 	if(m_oc.options["keep_alive"] != "true")
 	{

userspace/falco/outputs_file.h

@@ -27,10 +27,7 @@ namespace outputs
 
 class output_file : public abstract_output
 {
-	void output_event(gen_event *evt, std::string &rule, std::string &source,
-			  falco_common::priority_type priority, std::string &format, std::string &msg);
-
-	void output_msg(falco_common::priority_type priority, std::string &msg);
+	void output(const message *msg);
 
 	void cleanup();
 

userspace/falco/outputs_grpc.cpp

@@ -21,44 +21,41 @@ limitations under the License.
 #include "formats.h"
 #include "banned.h" // This raises a compilation error when certain functions are used
 
-void falco::outputs::output_grpc::output_event(gen_event *evt, std::string &rule, std::string &source,
-					       falco_common::priority_type priority, std::string &format,
-					       std::string &msg)
+void falco::outputs::output_grpc::output(const message *msg)
 {
 	falco::outputs::response grpc_res;
 
 	// time
 	auto timestamp = grpc_res.mutable_time();
-	*timestamp = google::protobuf::util::TimeUtil::NanosecondsToTimestamp(evt->get_ts());
+	*timestamp = google::protobuf::util::TimeUtil::NanosecondsToTimestamp(msg->ts);
 
 	// rule
 	auto r = grpc_res.mutable_rule();
-	*r = rule;
+	*r = msg->rule;
 
 	// source
 	falco::schema::source s = falco::schema::source::SYSCALL;
-	if(!falco::schema::source_Parse(source, &s))
+	if(!falco::schema::source_Parse(msg->source, &s))
 	{
-		throw falco_exception("Unknown source passed to output_grpc::output_event()");
+		throw falco_exception("Unknown source passed to output_grpc::output()");
 	}
 	grpc_res.set_source(s);
 
 	// priority
 	falco::schema::priority p = falco::schema::priority::EMERGENCY;
-	if(!falco::schema::priority_Parse(falco_common::priority_names[priority], &p))
+	if(!falco::schema::priority_Parse(falco_common::priority_names[msg->priority], &p))
 	{
-		throw falco_exception("Unknown priority passed to output_grpc::output_event()");
+		throw falco_exception("Unknown priority passed to output_grpc::output()");
 	}
 	grpc_res.set_priority(p);
 
 	// output
 	auto output = grpc_res.mutable_output();
-	*output = msg;
+	*output = msg->msg;
 
 	// output fields
 	auto &fields = *grpc_res.mutable_output_fields();
-	auto resolvedTkns = falco_formats::resolve_tokens(evt, source, format);
-	for(const auto &kv : resolvedTkns)
+	for(const auto &kv : msg->fields)
 	{
 		fields[kv.first] = kv.second;
 	}
@@ -68,9 +65,4 @@ void falco::outputs::output_grpc::output_event(gen_event *evt, std::string &rule
 	*host = m_hostname;
 
 	falco::grpc::queue::get().push(grpc_res);
-}
-
-void falco::outputs::output_grpc::output_msg(falco_common::priority_type priority, std::string &msg)
-{
-	// todo(fntlnz, leodido, leogr) > gRPC does not support subscribing to dropped events yet
 }

userspace/falco/outputs_grpc.h

@@ -25,10 +25,7 @@ namespace outputs
 
 class output_grpc : public abstract_output
 {
-	void output_event(gen_event *evt, std::string &rule, std::string &source,
-			  falco_common::priority_type priority, std::string &format, std::string &msg);
-
-	void output_msg(falco_common::priority_type priority, std::string &msg);
+	void output(const message *msg);
 };
 
 } // namespace outputs

userspace/falco/outputs_http.cpp

@@ -18,13 +18,7 @@ limitations under the License.
 #include "logger.h"
 #include "banned.h" // This raises a compilation error when certain functions are used
 
-void falco::outputs::output_http::output_event(gen_event *evt, std::string &rule, std::string &source,
-					       falco_common::priority_type priority, std::string &format, std::string &msg)
-{
-	output_msg(priority, msg);
-}
-
-void falco::outputs::output_http::output_msg(falco_common::priority_type priority, std::string &msg)
+void falco::outputs::output_http::output(const message *msg)
 {
 	CURL *curl = NULL;
 	CURLcode res = CURLE_FAILED_INIT;
@@ -37,7 +31,7 @@ void falco::outputs::output_http::output_msg(falco_common::priority_type priorit
 		slist1 = curl_slist_append(slist1, "Content-Type: application/json");
 		curl_easy_setopt(curl, CURLOPT_HTTPHEADER, slist1);
 		curl_easy_setopt(curl, CURLOPT_URL, m_oc.options["url"].c_str());
-		curl_easy_setopt(curl, CURLOPT_POSTFIELDS, msg.c_str());
+		curl_easy_setopt(curl, CURLOPT_POSTFIELDS, msg->msg.c_str());
 		curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, -1L);
 
 		res = curl_easy_perform(curl);

userspace/falco/outputs_http.h

@@ -25,10 +25,7 @@ namespace outputs
 
 class output_http : public abstract_output
 {
-	void output_event(gen_event *evt, std::string &rule, std::string &source,
-			  falco_common::priority_type priority, std::string &format, std::string &msg);
-
-	void output_msg(falco_common::priority_type priority, std::string &msg);
+	void output(const message *msg);
 };
 
 } // namespace outputs

userspace/falco/outputs_program.cpp

@@ -31,17 +31,11 @@ void falco::outputs::output_program::open_pfile()
 	}
 }
 
-void falco::outputs::output_program::output_event(gen_event *evt, std::string &rule, std::string &source,
-						  falco_common::priority_type priority, std::string &format, std::string &msg)
-{
-	output_msg(priority, msg);
-}
-
-void falco::outputs::output_program::output_msg(falco_common::priority_type priority, std::string &msg)
+void falco::outputs::output_program::output(const message *msg)
 {
 	open_pfile();
 
-	fprintf(m_pfile, "%s\n", msg.c_str());
+	fprintf(m_pfile, "%s\n", msg->msg.c_str());
 
 	if(m_oc.options["keep_alive"] != "true")
 	{

userspace/falco/outputs_program.h

@@ -25,10 +25,7 @@ namespace outputs
 
 class output_program : public abstract_output
 {
-	void output_event(gen_event *evt, std::string &rule, std::string &source,
-			  falco_common::priority_type priority, std::string &format, std::string &msg);
-
-	void output_msg(falco_common::priority_type priority, std::string &msg);
+	void output(const message *msg);
 
 	void cleanup();
 

userspace/falco/outputs_stdout.cpp

@@ -18,16 +18,10 @@ limitations under the License.
 #include <iostream>
 #include "banned.h" // This raises a compilation error when certain functions are used
 
-void falco::outputs::output_stdout::output_event(gen_event *evt, std::string &rule, std::string &source,
-						 falco_common::priority_type priority, std::string &format, std::string &msg)
-{
-	output_msg(priority, msg);
-}
-
-void falco::outputs::output_stdout::output_msg(falco_common::priority_type priority, std::string &msg)
+void falco::outputs::output_stdout::output(const message *msg)
 {
 	//
-	// By default, the stdout stream is fully buffered or line buffered 
+	// By default, the stdout stream is fully buffered or line buffered
 	// (if the stream can be determined to refer to an interactive device, e.g. in a TTY).
 	// Just enable automatic flushing when unbuffered output is desired.
 	// Note that it is set every time since other writings to the stdout can disable it.
@@ -36,7 +30,7 @@ void falco::outputs::output_stdout::output_msg(falco_common::priority_type prior
 	{
 		std::cout << std::unitbuf;
 	}
-	std::cout << msg + "\n";
+	std::cout << msg->msg + "\n";
 }
 
 void falco::outputs::output_stdout::cleanup()

userspace/falco/outputs_stdout.h

@@ -25,10 +25,7 @@ namespace outputs
 
 class output_stdout : public abstract_output
 {
-	void output_event(gen_event *evt, std::string &rule, std::string &source,
-			  falco_common::priority_type priority, std::string &format, std::string &msg);
-
-	void output_msg(falco_common::priority_type priority, std::string &msg);
+	void output(const message *msg);
 
 	void cleanup();
 };

userspace/falco/outputs_syslog.cpp

@@ -18,14 +18,8 @@ limitations under the License.
 #include <syslog.h>
 #include "banned.h" // This raises a compilation error when certain functions are used
 
-void falco::outputs::output_syslog::output_event(gen_event *evt, std::string &rule, std::string &source,
-						 falco_common::priority_type priority, std::string &format, std::string &msg)
-{
-	output_msg(priority, msg);
-}
-
-void falco::outputs::output_syslog::output_msg(falco_common::priority_type priority, std::string &msg)
+void falco::outputs::output_syslog::output(const message *msg)
 {
 	// Syslog output should not have any trailing newline
-	::syslog(priority, "%s", msg.c_str());
+	::syslog(msg->priority, "%s", msg->msg.c_str());
 }

userspace/falco/outputs_syslog.h

@@ -25,10 +25,7 @@ namespace outputs
 
 class output_syslog : public abstract_output
 {
-	void output_event(gen_event *evt, std::string &rule, std::string &source,
-			  falco_common::priority_type priority, std::string &format, std::string &msg);
-
-	void output_msg(falco_common::priority_type priority, std::string &msg);
+	void output(const message *msg);
 };
 
 } // namespace outputs

userspace/falco/schema.proto

@@ -57,4 +57,7 @@ enum source {
   k8s_audit = 1;
   K8s_audit = 1;
   K8S_audit = 1;
+  INTERNAL = 2;
+  internal = 2;
+  Internal = 2;
 }

userspace/falco/version.proto

@@ -36,10 +36,14 @@ message request
 // its parts as per semver 2.0 specification (https://semver.org).
 message response
 {
+// falco version
   string version = 1;
   uint32 major = 2;
   uint32 minor = 3;
   uint32 patch = 4;
   string prerelease = 5;
   string build = 6;
-}
+// falco engine version
+  uint32 engine_version = 7;
+  string engine_fields_checksum = 8;
+}

userspace/falco/watchdog.h

@@ -0,0 +1,96 @@
+/*
+Copyright (C) 2020 The Falco Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+#include <chrono>
+#include <thread>
+#include <functional>
+#include <atomic>
+
+template<typename _T>
+class watchdog
+{
+public:
+	watchdog():
+		m_timeout(nullptr),
+		m_is_running(false)
+	{
+	}
+
+	~watchdog()
+	{
+		stop();
+	}
+
+	void start(std::function<void(_T)> cb,
+		   std::chrono::milliseconds resolution = std::chrono::milliseconds(100))
+	{
+		stop();
+		m_is_running.store(true, std::memory_order_release);
+		m_thread = std::thread([this, cb, resolution]() {
+			const auto no_deadline = time_point{};
+			timeout_data curr;
+			while(m_is_running.load(std::memory_order_acquire))
+			{
+				auto t = m_timeout.exchange(nullptr, std::memory_order_release);
+				if(t)
+				{
+					curr = *t;
+					delete t;
+				}
+				if(curr.deadline != no_deadline && curr.deadline < std::chrono::steady_clock::now())
+				{
+					cb(curr.payload);
+					curr.deadline = no_deadline;
+				}
+				std::this_thread::sleep_for(resolution);
+			}
+		});
+	}
+
+	void stop()
+	{
+		if(m_is_running.load(std::memory_order_acquire))
+		{
+			m_is_running.store(false, std::memory_order_release);
+			if(m_thread.joinable())
+			{
+				m_thread.join();
+			}
+			delete m_timeout.exchange(nullptr, std::memory_order_release);
+		}
+	}
+
+	inline void set_timeout(std::chrono::milliseconds timeout, _T payload) noexcept
+	{
+		delete m_timeout.exchange(new timeout_data{std::chrono::steady_clock::now() + timeout, payload}, std::memory_order_release);
+	}
+
+	inline void cancel_timeout() noexcept
+	{
+		delete m_timeout.exchange(new timeout_data, std::memory_order_release);
+	}
+
+private:
+	typedef std::chrono::time_point<std::chrono::steady_clock> time_point;
+	struct timeout_data
+	{
+		time_point deadline;
+		_T payload;
+	};
+	std::atomic<timeout_data *> m_timeout;
+	std::atomic<bool> m_is_running;
+	std::thread m_thread;
+};