configuration.cpp

/*
Copyright (C) 2022 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 <algorithm>

#include <list>
#include <set>
#include <string>
#include <unordered_set>

#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "falco_utils.h"

#include "configuration.h"
#include "logger.h"
#include "banned.h" // This raises a compilation error when certain functions are used

falco_configuration::falco_configuration():
	m_json_output(false),
	m_json_include_output_property(true),
	m_json_include_tags_property(true),
	m_notifications_rate(0),
	m_notifications_max_burst(1000),
	m_watch_config_files(true),
	m_rule_matching(falco_common::rule_matching::FIRST),
	m_buffered_outputs(false),
	m_time_format_iso_8601(false),
	m_output_timeout(2000),
	m_grpc_enabled(false),
	m_grpc_threadiness(0),
	m_webserver_enabled(false),
	m_webserver_threadiness(0),
	m_webserver_listen_port(8765),
	m_webserver_k8s_healthz_endpoint("/healthz"),
	m_webserver_ssl_enabled(false),
	m_syscall_evt_drop_threshold(.1),
	m_syscall_evt_drop_rate(.03333),
	m_syscall_evt_drop_max_burst(1),
	m_syscall_evt_simulate_drops(false),
	m_syscall_evt_timeout_max_consecutives(1000),
	m_metadata_download_max_mb(100),
	m_metadata_download_chunk_wait_us(1000),
	m_metadata_download_watch_freq_sec(1),
	m_syscall_buf_size_preset(4),
	m_cpus_for_each_syscall_buffer(2),
	m_syscall_drop_failed_exit(false),
	m_base_syscalls_repair(false),
	m_metrics_enabled(false),
	m_metrics_interval_str("5000"),
	m_metrics_interval(5000),
	m_metrics_stats_rule_enabled(false),
	m_metrics_output_file(""),
	m_metrics_resource_utilization_enabled(true),
	m_metrics_kernel_event_counters_enabled(true),
	m_metrics_libbpf_stats_enabled(true),
	m_metrics_convert_memory_to_mb(true),
	m_metrics_include_empty_values(false)
{
	init({});
}

void falco_configuration::init(const std::vector<std::string>& cmdline_options)
{
	yaml_helper config;
	config.load_from_string("");
	init_cmdline_options(config, cmdline_options);
	load_yaml("default", config);
}

void falco_configuration::init(const std::string& conf_filename, const std::vector<std::string> &cmdline_options)
{
	yaml_helper config;
	try
	{
		config.load_from_file(conf_filename);
	}
	catch(const std::exception& e)
	{
		std::cerr << "Cannot read config file (" + conf_filename + "): " + e.what() + "\n";
		throw e;
	}

	init_cmdline_options(config, cmdline_options);
	load_yaml(conf_filename, config);
}

void falco_configuration::load_yaml(const std::string& config_name, const yaml_helper& config)
{
	std::list<std::string> rules_files;

	config.get_sequence<std::list<std::string>>(rules_files, std::string("rules_file"));

	m_rules_filenames.clear();
	m_loaded_rules_filenames.clear();
	m_loaded_rules_folders.clear();
	for(auto &file : rules_files)
	{
		// Here, we only include files that exist
		struct stat buffer;
		if(stat(file.c_str(), &buffer) == 0)
		{
			m_rules_filenames.push_back(file);
		}
	}

	m_json_output = config.get_scalar<bool>("json_output", false);
	m_json_include_output_property = config.get_scalar<bool>("json_include_output_property", true);
	m_json_include_tags_property = config.get_scalar<bool>("json_include_tags_property", true);

	m_outputs.clear();
	falco::outputs::config file_output;
	file_output.name = "file";
	if(config.get_scalar<bool>("file_output.enabled", false))
	{
		std::string filename, keep_alive;
		filename = config.get_scalar<std::string>("file_output.filename", "");
		if(filename == std::string(""))
		{
			throw std::logic_error("Error reading config file (" + config_name + "): file output enabled but no filename in configuration block");
		}
		file_output.options["filename"] = filename;

		keep_alive = config.get_scalar<std::string>("file_output.keep_alive", "");
		file_output.options["keep_alive"] = keep_alive;

		m_outputs.push_back(file_output);
	}

	falco::outputs::config stdout_output;
	stdout_output.name = "stdout";
	if(config.get_scalar<bool>("stdout_output.enabled", false))
	{
		m_outputs.push_back(stdout_output);
	}

	falco::outputs::config syslog_output;
	syslog_output.name = "syslog";
	if(config.get_scalar<bool>("syslog_output.enabled", false))
	{
		m_outputs.push_back(syslog_output);
	}

	falco::outputs::config program_output;
	program_output.name = "program";
	if(config.get_scalar<bool>("program_output.enabled", false))
	{
		std::string program, keep_alive;
		program = config.get_scalar<std::string>("program_output.program", "");
		if(program == std::string(""))
		{
			throw std::logic_error("Error reading config file (" + config_name + "): program output enabled but no program in configuration block");
		}
		program_output.options["program"] = program;

		keep_alive = config.get_scalar<std::string>("program_output.keep_alive", "");
		program_output.options["keep_alive"] = keep_alive;

		m_outputs.push_back(program_output);
	}

	falco::outputs::config http_output;
	http_output.name = "http";
	if(config.get_scalar<bool>("http_output.enabled", false))
	{
		std::string url;
		url = config.get_scalar<std::string>("http_output.url", "");

		if(url == std::string(""))
		{
			throw std::logic_error("Error reading config file (" + config_name + "): http output enabled but no url in configuration block");
		}
		http_output.options["url"] = url;

		std::string user_agent;
		user_agent = config.get_scalar<std::string>("http_output.user_agent","falcosecurity/falco");
		http_output.options["user_agent"] = user_agent;

		bool insecure;
		insecure = config.get_scalar<bool>("http_output.insecure", false);
		http_output.options["insecure"] = insecure? std::string("true") : std::string("false");

		bool echo;
		echo = config.get_scalar<bool>("http_output.echo", false);
		http_output.options["echo"] = echo? std::string("true") : std::string("false");
		
		std::string ca_cert;
		ca_cert = config.get_scalar<std::string>("http_output.ca_cert", "");
		http_output.options["ca_cert"] = ca_cert;

		std::string ca_bundle;
		ca_bundle = config.get_scalar<std::string>("http_output.ca_bundle", "");
		http_output.options["ca_bundle"] = ca_bundle;

		std::string ca_path;
		ca_path = config.get_scalar<std::string>("http_output.ca_path", "/etc/ssl/certs");
		http_output.options["ca_path"] = ca_path;

		bool mtls;
		mtls = config.get_scalar<bool>("http_output.mtls", false);
		http_output.options["mtls"] = mtls? std::string("true") : std::string("false");

		std::string client_cert;
		client_cert = config.get_scalar<std::string>("http_output.client_cert", "/etc/ssl/certs/client.crt");
		http_output.options["client_cert"] = client_cert;

		std::string client_key;
		client_key = config.get_scalar<std::string>("http_output.client_key", "/etc/ssl/certs/client.key");
		http_output.options["client_key"] = client_key;

		m_outputs.push_back(http_output);
	}

	m_grpc_enabled = config.get_scalar<bool>("grpc.enabled", false);
	m_grpc_bind_address = config.get_scalar<std::string>("grpc.bind_address", "0.0.0.0:5060");
	m_grpc_threadiness = config.get_scalar<uint32_t>("grpc.threadiness", 0);
	if(m_grpc_threadiness == 0)
	{
		m_grpc_threadiness = falco::utils::hardware_concurrency();
	}
	// todo > else limit threadiness to avoid oversubscription?
	m_grpc_private_key = config.get_scalar<std::string>("grpc.private_key", "/etc/falco/certs/server.key");
	m_grpc_cert_chain = config.get_scalar<std::string>("grpc.cert_chain", "/etc/falco/certs/server.crt");
	m_grpc_root_certs = config.get_scalar<std::string>("grpc.root_certs", "/etc/falco/certs/ca.crt");

	falco::outputs::config grpc_output;
	grpc_output.name = "grpc";
	// gRPC output is enabled only if gRPC server is enabled too
	if(config.get_scalar<bool>("grpc_output.enabled", true) && m_grpc_enabled)
	{
		m_outputs.push_back(grpc_output);
	}

	m_log_level = config.get_scalar<std::string>("log_level", "info");

	falco_logger::set_level(m_log_level);


	falco_logger::set_sinsp_logging(
		config.get_scalar<bool>("libs_logger.enabled", false),
		config.get_scalar<std::string>("libs_logger.severity", "debug"),
		"[libs]: ");

	falco_logger::log_stderr = config.get_scalar<bool>("log_stderr", false);
	falco_logger::log_syslog = config.get_scalar<bool>("log_syslog", true);

	m_output_timeout = config.get_scalar<uint32_t>("output_timeout", 2000);

	m_notifications_rate = config.get_scalar<uint32_t>("outputs.rate", 0);
	if(m_notifications_rate != 0)
	{
		falco_logger::log(LOG_WARNING, "'output.rate' config is deprecated and it will be removed in Falco 0.37\n");
	}
	m_notifications_max_burst = config.get_scalar<uint32_t>("outputs.max_burst", 1000);

	std::string rule_matching = config.get_scalar<std::string>("rule_matching", "first");
	if (!falco_common::parse_rule_matching(rule_matching, m_rule_matching))
	{
		throw std::logic_error("Unknown rule matching strategy \"" + rule_matching + "\"--must be one of first, all");
	}

	std::string priority = config.get_scalar<std::string>("priority", "debug");
	if (!falco_common::parse_priority(priority, m_min_priority))
	{
		throw std::logic_error("Unknown priority \"" + priority + "\"--must be one of emergency, alert, critical, error, warning, notice, informational, debug");
	}

	m_buffered_outputs = config.get_scalar<bool>("buffered_outputs", false);
	m_time_format_iso_8601 = config.get_scalar<bool>("time_format_iso_8601", false);

	m_webserver_enabled = config.get_scalar<bool>("webserver.enabled", false);
	m_webserver_threadiness = config.get_scalar<uint32_t>("webserver.threadiness", 0);
	m_webserver_listen_port = config.get_scalar<uint32_t>("webserver.listen_port", 8765);
	m_webserver_k8s_healthz_endpoint = config.get_scalar<std::string>("webserver.k8s_healthz_endpoint", "/healthz");
	m_webserver_ssl_enabled = config.get_scalar<bool>("webserver.ssl_enabled", false);
	m_webserver_ssl_certificate = config.get_scalar<std::string>("webserver.ssl_certificate", "/etc/falco/falco.pem");
	if(m_webserver_threadiness == 0)
	{
		m_webserver_threadiness = falco::utils::hardware_concurrency();
	}

	std::list<std::string> syscall_event_drop_acts;
	config.get_sequence(syscall_event_drop_acts, "syscall_event_drops.actions");

	m_syscall_evt_drop_actions.clear();
	for(std::string &act : syscall_event_drop_acts)
	{
		if(act == "ignore")
		{
			m_syscall_evt_drop_actions.insert(syscall_evt_drop_action::IGNORE);
		}
		else if(act == "log")
		{
			if(m_syscall_evt_drop_actions.count(syscall_evt_drop_action::IGNORE))
			{
				throw std::logic_error("Error reading config file (" + config_name + "): syscall event drop action \"" + act + "\" does not make sense with the \"ignore\" action");
			}
			m_syscall_evt_drop_actions.insert(syscall_evt_drop_action::LOG);
		}
		else if(act == "alert")
		{
			if(m_syscall_evt_drop_actions.count(syscall_evt_drop_action::IGNORE))
			{
				throw std::logic_error("Error reading config file (" + config_name + "): syscall event drop action \"" + act + "\" does not make sense with the \"ignore\" action");
			}
			m_syscall_evt_drop_actions.insert(syscall_evt_drop_action::ALERT);
		}
		else if(act == "exit")
		{
			m_syscall_evt_drop_actions.insert(syscall_evt_drop_action::EXIT);
		}
		else
		{
			throw std::logic_error("Error reading config file (" + config_name + "): available actions for syscall event drops are \"ignore\", \"log\", \"alert\", and \"exit\"");
		}
	}

	if(m_syscall_evt_drop_actions.empty())
	{
		m_syscall_evt_drop_actions.insert(syscall_evt_drop_action::IGNORE);
	}

	m_syscall_evt_drop_threshold = config.get_scalar<double>("syscall_event_drops.threshold", .1);
	if(m_syscall_evt_drop_threshold < 0 || m_syscall_evt_drop_threshold > 1)
	{
		throw std::logic_error("Error reading config file (" + config_name + "): syscall event drops threshold must be a double in the range [0, 1]");
	}
	m_syscall_evt_drop_rate = config.get_scalar<double>("syscall_event_drops.rate", .03333);
	m_syscall_evt_drop_max_burst = config.get_scalar<double>("syscall_event_drops.max_burst", 1);
	m_syscall_evt_simulate_drops = config.get_scalar<bool>("syscall_event_drops.simulate_drops", false);

	m_syscall_evt_timeout_max_consecutives = config.get_scalar<uint32_t>("syscall_event_timeouts.max_consecutives", 1000);
	if(m_syscall_evt_timeout_max_consecutives == 0)
	{
		throw std::logic_error("Error reading config file(" + config_name + "): the maximum consecutive timeouts without an event must be an unsigned integer > 0");
	}

	m_metadata_download_max_mb = config.get_scalar<uint32_t>("metadata_download.max_mb", 100);
	if(m_metadata_download_max_mb > 1024)
	{
		throw std::logic_error("Error reading config file(" + config_name + "): metadata download maximum size should be < 1024 Mb");
	}
	m_metadata_download_chunk_wait_us = config.get_scalar<uint32_t>("metadata_download.chunk_wait_us", 1000);
	m_metadata_download_watch_freq_sec = config.get_scalar<uint32_t>("metadata_download.watch_freq_sec", 1);
	if(m_metadata_download_watch_freq_sec == 0)
	{
		throw std::logic_error("Error reading config file(" + config_name + "): metadata download watch frequency seconds must be an unsigned integer > 0");
	}

	/* We put this value in the configuration file because in this way we can change the dimension at every reload.
	 * The default value is `4` -> 8 MB.
	 */
	m_syscall_buf_size_preset = config.get_scalar<uint16_t>("syscall_buf_size_preset", 4);

	m_cpus_for_each_syscall_buffer = config.get_scalar<uint16_t>("modern_bpf.cpus_for_each_syscall_buffer", 2);

	m_syscall_drop_failed_exit = config.get_scalar<bool>("syscall_drop_failed_exit", false);

	m_base_syscalls_custom_set.clear();
	config.get_sequence<std::unordered_set<std::string>>(m_base_syscalls_custom_set, std::string("base_syscalls.custom_set"));
	m_base_syscalls_repair = config.get_scalar<bool>("base_syscalls.repair", false);

	m_metrics_enabled = config.get_scalar<bool>("metrics.enabled", false);
	m_metrics_interval_str = config.get_scalar<std::string>("metrics.interval", "5000");
	m_metrics_interval = falco::utils::parse_prometheus_interval(m_metrics_interval_str);
	m_metrics_stats_rule_enabled = config.get_scalar<bool>("metrics.output_rule", false);
	m_metrics_output_file = config.get_scalar<std::string>("metrics.output_file", "");
	m_metrics_resource_utilization_enabled = config.get_scalar<bool>("metrics.resource_utilization_enabled", true);
	m_metrics_kernel_event_counters_enabled = config.get_scalar<bool>("metrics.kernel_event_counters_enabled", true);
	m_metrics_libbpf_stats_enabled = config.get_scalar<bool>("metrics.libbpf_stats_enabled", true);
	m_metrics_convert_memory_to_mb = config.get_scalar<bool>("metrics.convert_memory_to_mb", true);
	m_metrics_include_empty_values = config.get_scalar<bool>("metrics.include_empty_values", false);

	std::vector<std::string> load_plugins;

	bool load_plugins_node_defined = config.is_defined("load_plugins");

	config.get_sequence<std::vector<std::string>>(load_plugins, "load_plugins");

	std::list<falco_configuration::plugin_config> plugins;
	try
	{
		if (config.is_defined("plugins"))
		{
			config.get_sequence<std::list<falco_configuration::plugin_config>>(plugins, std::string("plugins"));
		}
	}
	catch (std::exception &e)
	{
		// Might be thrown due to not being able to open files
		throw std::logic_error("Error reading config file(" + config_name + "): could not load plugins config: " + e.what());
	}

	// If load_plugins was specified, only save plugins matching those in values
	m_plugins.clear();
	if (!load_plugins_node_defined)
	{
		// If load_plugins was not specified at all, every plugin is added.
		// The loading order is the same as the sequence in the YAML config.
		m_plugins = { plugins.begin(), plugins.end() };
	}
	else
	{
		// If load_plugins is specified, only plugins contained in its list
		// are added, with the same order as in the list.
		for (const auto& pname : load_plugins)
		{
			bool found = false;
			for (const auto& p : plugins)
			{
				if (pname == p.m_name)
				{
					m_plugins.push_back(p);
					found = true;
					break;
				}
			}
			if (!found)
			{
				throw std::logic_error("Cannot load plugin '" + pname + "': plugin config not found for given name");
			}
		}
	}

	m_watch_config_files = config.get_scalar<bool>("watch_config_files", true);
}

void falco_configuration::read_rules_file_directory(const std::string &path, std::list<std::string> &rules_filenames, std::list<std::string> &rules_folders)
{
	struct stat st;

	int rc = stat(path.c_str(), &st);

	if(rc != 0)
	{
		std::cerr << "Could not get info on rules file " << path << ": " << strerror(errno) << std::endl;
		exit(-1);
	}

	if(st.st_mode & S_IFDIR)
	{
		rules_folders.push_back(path);

		// It's a directory. Read the contents, sort
		// alphabetically, and add every path to
		// rules_filenames
		std::vector<std::string> dir_filenames;

		DIR *dir = opendir(path.c_str());

		if(!dir)
		{
			std::cerr << "Could not get read contents of directory " << path << ": " << strerror(errno) << std::endl;
			exit(-1);
		}

		for(struct dirent *ent = readdir(dir); ent; ent = readdir(dir))
		{
			std::string efile = path + "/" + ent->d_name;

			rc = stat(efile.c_str(), &st);

			if(rc != 0)
			{
				std::cerr << "Could not get info on rules file " << efile << ": " << strerror(errno) << std::endl;
				exit(-1);
			}

			if(st.st_mode & S_IFREG)
			{
				dir_filenames.push_back(efile);
			}
		}

		closedir(dir);

		std::sort(dir_filenames.begin(),
			  dir_filenames.end());

		for(std::string &ent : dir_filenames)
		{
			rules_filenames.push_back(ent);
		}
	}
	else
	{
		// Assume it's a file and just add to
		// rules_filenames. If it can't be opened/etc that
		// will be reported later..
		rules_filenames.push_back(path);
	}
}

static bool split(const std::string &str, char delim, std::pair<std::string, std::string> &parts)
{
	size_t pos;

	if((pos = str.find_first_of(delim)) == std::string::npos)
	{
		return false;
	}
	parts.first = str.substr(0, pos);
	parts.second = str.substr(pos + 1);

	return true;
}

void falco_configuration::init_cmdline_options(yaml_helper& config, const std::vector<std::string> &cmdline_options)
{
	for(const std::string &option : cmdline_options)
	{
		set_cmdline_option(config, option);
	}
}

void falco_configuration::set_cmdline_option(yaml_helper& config, const std::string &opt)
{
	std::pair<std::string, std::string> keyval;

	if(!split(opt, '=', keyval))
	{
		throw std::logic_error("Error parsing config option \"" + opt + "\". Must be of the form key=val or key.subkey=val");
	}

	config.set_scalar(keyval.first, keyval.second);
}