From 34779155d5b69b51aa301e7c111f95ea9c840589 Mon Sep 17 00:00:00 2001 From: flu0r1ne Date: Thu, 17 Aug 2023 15:56:11 -0500 Subject: init commit --- src/wg2sd.cpp | 503 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 503 insertions(+) create mode 100644 src/wg2sd.cpp (limited to 'src/wg2sd.cpp') diff --git a/src/wg2sd.cpp b/src/wg2sd.cpp new file mode 100644 index 0000000..2571908 --- /dev/null +++ b/src/wg2sd.cpp @@ -0,0 +1,503 @@ +#include "wg2sd.hpp" + +#include +#include +#include +#include + +#include + +std::string hashed_keyfile_name(std::string const & priv_key) { + constexpr uint8_t const SALT[] = { + 0x1, 0x6, 0x1, 0x5, 0x5, 0x8, 0x3, 0xd, 0x2, 0x7, + 0x5, 0xc, 0x8, 0x8, 0x7, 0x2, 0x7, 0xa, 0xf, 0x5, + 0xa, 0x6, 0xc, 0x5, 0xf, 0xe, 0x6, 0x7, 0xf, 0xd, + 0x1, 0x5 + }; + + uint8_t const * key = reinterpret_cast(priv_key.c_str()); + uint32_t keylen = priv_key.size(); + + uint8_t t_cost = 2; // 2-pass computation + uint32_t m_cost = 1 << 17; // 128 mebibytes memory + uint32_t parallelism = 1; // single thread + + constexpr size_t HASHLEN = 32; + + uint8_t hash[HASHLEN]; + + argon2i_hash_raw(t_cost, m_cost, parallelism, key, keylen, SALT, sizeof(SALT), hash, HASHLEN); + + constexpr char KEYFILE_EXT[] = ".keyfile"; + + char filename[HASHLEN + sizeof(KEYFILE_EXT)]; + + constexpr char const HEX[] = "0123456789abcdefghijklmnopqrstuv"; + + for(size_t i = 0; i < HASHLEN; i++) { + filename[i] = HEX[hash[i] & 0x1F]; + } + + // copy null terminator + for(size_t i = 0; i < sizeof(KEYFILE_EXT); i++) { + filename[HASHLEN + i] = KEYFILE_EXT[i]; + } + + return std::string { filename } ; +} + + +namespace wg2sd { + + std::string interface_name_from_filename(std::filesystem::path config_path) { + std::string interface_name = config_path.filename().string(); + interface_name = interface_name.substr( + 0, interface_name.size() - config_path.extension().string().size() + ); + return interface_name; + } + + bool _is_default_route(std::string const & cidr) { + static std::regex ipv4_wildcard("0(\\.0){0,3}\\/0"); + static std::regex ipv6_wildcard("(0{0,4}:){0,7}0{0,4}\\/0{1,4}"); + + return std::regex_match(cidr, ipv4_wildcard) or std::regex_match(cidr, ipv6_wildcard); + } + + bool _is_ipv4_route(std::string const & cidr) { + static std::regex ipv4("\\d{1,3}(\\.\\d{1,3}){0,3}(\\/\\d{1,2})?"); + + return std::regex_match(cidr, ipv4); + } + + constexpr uint32_t MAIN_TABLE = 254; + constexpr uint32_t LOCAL_TABLE = 255; + + // Parse the wireguard configuration from an input stream + // into a Config object. If an invalid key or section occurs, + // exists, a ParsingException is thrown. + Config parse_config(std::string const & interface_name, std::istream & stream) { + Config cfg; + + cfg.intf.name = interface_name; + cfg.has_default_route = false; + cfg.intf.should_create_routes = true; + + std::string line; + uint64_t line_no = 0; + + enum class Section { + Interface, + Peer, + None + }; + + Section section = Section::None; + + bool peer_has_default_route = false; + + while (std::getline(stream, line)) { + ++line_no; + + // Strip whitespace (\t) from line in-place + { + size_t i = 0, j = 0; + for(; i < line.size(); i++) { + if(line[i] != ' ' and line[i] != '\t') { + line[j] = line[i]; + j++; + } + } + line.erase(j); + } + + // Remove content exceeding a comment + size_t comment_start = line.find('#'); + if(comment_start != std::string::npos) { + line.erase(comment_start); + } + + // Ignore empty lines + if (line.empty()) { + continue; + } + + // Handle section: [Interface] or [Peer] specifies further + // configuration concerns an interface or peer respectively + + bool interface_sec_wanted = line == "[Interface]"; + bool peer_sec_wanted = line == "[Peer]"; + + if(interface_sec_wanted || peer_sec_wanted) { + cfg.has_default_route = cfg.has_default_route or peer_has_default_route; + peer_has_default_route = false; + } + + if (interface_sec_wanted) { + section = Section::Interface; + continue; + } else if (peer_sec_wanted) { + section = Section::Peer; + cfg.peers.emplace_back(); + continue; + } + + // Split key + size_t pos = line.find('='); + if(pos == std::string::npos) { + throw ParsingException("Expected key-value pair, got \"" + line + "\"", line_no); + } + + std::string key = line.substr(0, pos); + std::string value = line.substr(pos + 1); + + // Read keys according to corresponding section + switch (section) { + case Section::Interface: { + if (key == "PrivateKey") { + cfg.intf.private_key = value; + } else if (key == "DNS") { + std::istringstream dnsStream(value); + std::string dnsIp; + while (std::getline(dnsStream, dnsIp, ',')) { + cfg.intf.DNS.push_back(dnsIp); + } + } else if (key == "Address") { + std::istringstream addressStream(value); + std::string address; + while (std::getline(addressStream, address, ',')) { + cfg.intf.addresses.push_back(address); + } + } else if (key == "Table") { + if(value == "off") { + cfg.intf.table = 0; + cfg.intf.should_create_routes = false; + } else { + cfg.intf.should_create_routes = true; + if(value == "auto") { + cfg.intf.table = 0; + } else if(value == "main") { + cfg.intf.table = MAIN_TABLE; + } else if(value == "local") { + cfg.intf.table = LOCAL_TABLE; + } else { + long long table; + try { + table = std::stoll(value); + } catch(std::exception const & e) { + table = -1; + } + + if(table < 1 || table > UINT32_MAX) { + throw ParsingException("Invalid option to \"Table\", must be one of \"off\", \"auto\" or a table number", line_no); + } + + cfg.intf.table = table; + } + } + } else if (key == "ListenPort") { + int port; + try { + port = std::stoi(value); + } catch(std::exception & e) { + port = -1; + } + + if(port < 0 || port > UINT16_MAX) { + throw ParsingException("Invalid port: " + key, line_no); + } + + cfg.intf.listen_port = port; + } else { + throw ParsingException("Invalid key in [Interface] section: " + key, line_no); + } + break; + } + case Section::Peer: { + if (key == "Endpoint") { + cfg.peers.back().endpoint = value; + } else if (key == "AllowedIPs") { + std::istringstream allowedIpsStream(value); + std::string allowedIp; + + while (std::getline(allowedIpsStream, allowedIp, ',')) { + bool is_default_route = _is_default_route(allowedIp); + + if(is_default_route and cfg.has_default_route) { + throw ParsingException("Default routes exist on multiple peers"); + } + + cfg.peers.back().allowed_ips.push_back(Cidr { + .route = allowedIp, + .is_default_route = is_default_route, + .is_ipv4 = _is_ipv4_route(allowedIp), + }); + + peer_has_default_route = peer_has_default_route or is_default_route; + } + + } else if (key == "PublicKey") { + cfg.peers.back().public_key = value; + } else if (key == "PersistentKeepalive") { + cfg.peers.back().persistent_keepalive = value; + } else if (key == "PresharedKey") { + cfg.peers.back().preshared_key = value; + } else { + throw ParsingException("Invalid key in [Peer] section: " + key, line_no); + } + break; + } + case Section::None: + throw ParsingException("Unexpected key outside of section: " + key, line_no); + } + } + + cfg.has_default_route = cfg.has_default_route or peer_has_default_route; + +#define MissingField(section, key) \ + ConfigurationException("[" section "] section missing essential field \"" key "\"") + + // Ensure PrivateKey, Address, PublicKey, and AllowedIPs are present + + if(cfg.intf.private_key.empty()) { + throw MissingField("Interface", "PrivateKey"); + } + + if(cfg.intf.addresses.empty()) { + throw MissingField("Interface", "Address"); + } + + for(Peer const & peer : cfg.peers) { + if(peer.public_key.empty()) { + throw MissingField("Peer", "PublicKey"); + } + + if(peer.allowed_ips.empty()) { + throw MissingField("Peer", "AllowedIPs"); + } + } + +#undef MissingField + + return cfg; + } + + static std::string _gen_netdev_cfg(Config const & cfg, uint32_t fwd_table, std::string const & private_keyfile, + std::vector & symmetric_keyfiles, std::string const & output_path) { + std::stringstream netdev; + + netdev << "# Autogenerated by wg2sd\n"; + netdev << "[NetDev]\n"; + netdev << "Name = " << cfg.intf.name << "\n"; + netdev << "Kind = wireguard\n"; + netdev << "Description = " << cfg.intf.name << " - wireguard tunnel\n"; + + if(!cfg.intf.mtu.empty()) { + netdev << "MTUBytes = " << cfg.intf.mtu << "\n"; + } + + netdev << "\n"; + + netdev << "[WireGuard]\n"; + netdev << "PrivateKeyFile = " << output_path; + + if(output_path.back() != '/') { + netdev << "/"; + } + + netdev << private_keyfile << "\n"; + + if(cfg.intf.should_create_routes and cfg.intf.table != 0) { + netdev << "RouteTable = "; + + switch(cfg.intf.table) { + case LOCAL_TABLE: + netdev << "local"; + break; + case MAIN_TABLE: + netdev << "main"; + break; + default: + netdev << cfg.intf.table; + break; + } + + netdev << "\n"; + } + + if(cfg.intf.should_create_routes and cfg.has_default_route) { + netdev << "FirewallMark = 0x" << std::hex << fwd_table << std::dec << "\n"; + } + + netdev << "\n"; + + for(Peer const & peer : cfg.peers) { + netdev << "[WireGuardPeer]\n"; + + netdev << "Endpoint = " << peer.endpoint << "\n"; + netdev << "PublicKey = " << peer.public_key << "\n"; + + if(!peer.preshared_key.empty()) { + std::string filename = hashed_keyfile_name(peer.preshared_key); + + symmetric_keyfiles.push_back(SystemdFilespec { + .name = filename, + .contents = peer.preshared_key + "\n", + }); + + netdev << "PresharedKeyFile = " << filename << "\n"; + } + + for(Cidr const & cidr : peer.allowed_ips) { + netdev << "AllowedIPs = " << cidr.route << "\n"; + } + + if(!peer.persistent_keepalive.empty()) { + netdev << "PersistentKeepalive = " << peer.persistent_keepalive << "\n"; + } + + netdev << "\n"; + } + + return netdev.str(); + } + + static std::string _gen_network_cfg(Config const & cfg, uint32_t fwd_table) { + std::stringstream network; + + network << "# Autogenerated by wg2sd\n"; + network << "[Match]\n"; + network << "Name = " << cfg.intf.name << "\n"; + network << "\n"; + + network << "[Network]\n"; + for(std::string const & addr : cfg.intf.addresses) { + network << "Address = " << addr << "\n"; + } + + for(std::string const & dns : cfg.intf.DNS) { + network << "DNS = " << dns << "\n"; + } + + if(cfg.has_default_route and cfg.intf.DNS.size() > 0) { + network << "Domains = ~." << "\n"; + } + + network << "\n"; + + if(!cfg.intf.should_create_routes) { + return network.str(); + } + + constexpr uint8_t POLICY_ROUTE_NONE = 0; + constexpr uint8_t POLICY_ROUTE_V4 = 1 << 0; + constexpr uint8_t POLICY_ROUTE_V6 = 1 << 1; + constexpr uint8_t POLICY_ROUTE_BOTH = POLICY_ROUTE_V4 | POLICY_ROUTE_V6; + + uint8_t policy_route = POLICY_ROUTE_NONE; + + for(Peer const & peer : cfg.peers) { + for(Cidr const & cidr : peer.allowed_ips) { + if(cidr.is_default_route) { + policy_route |= cidr.is_ipv4 ? POLICY_ROUTE_V4 : POLICY_ROUTE_V6; + } + + network << "[Route]\n"; + network << "Destination = " << cidr.route << "\n"; + uint32_t table = cfg.has_default_route ? fwd_table : cfg.intf.table; + if(table) { + network << "Table = " << table << "\n"; + } + network << "\n"; + } + } + + if(policy_route != POLICY_ROUTE_NONE) { + + char const * family = nullptr; + + switch(policy_route) { + case POLICY_ROUTE_V4: + family = "ipv6"; + break; + case POLICY_ROUTE_V6: + family = "ipv4"; + break; + case POLICY_ROUTE_BOTH: + family = "both"; + break; + } + + network << "[RoutingPolicyRule]\n"; + network << "SuppressPrefixLength = 0\n"; + network << "Family = " << family << "\n"; + network << "Priority = 32764\n"; + network << "\n"; + + network << "[RoutingPolicyRule]\n"; + network << "FirewallMark = 0x" << std::hex << fwd_table << std::dec << "\n"; + network << "InvertRule = true\n"; + network << "Table = " << fwd_table << "\n"; + network << "Family = " << family << "\n"; + network << "Priority = 32765\n"; + network << "\n"; + + } + + return network.str(); + } + + static uint32_t _random_table() { + std::random_device rd; + std::mt19937 rng { rd() }; + + uint32_t table = 0; + while(table == 0 or table == MAIN_TABLE or table == LOCAL_TABLE) { + table = rng() % UINT32_MAX; + } + + return table; + } + + SystemdConfig gen_systemd_config(Config const & cfg, std::string const & output_path) { + + // If the table is explicitly specified with Table=, + // all routes are added to this table. + // + // If Table=auto and a default route exists, this + // table is used by the default route to supersede + // non-encrypted traffic traveling to /0 routes in the + // main routing table by using suppress_prefix policy rules. + // These routes match a fwmark which is identical to the + // table name. All other routes are placed in the main routing + // table. + // + // If Table=off, no routes are added. + uint32_t fwd_table = _random_table(); + + std::vector symmetric_keyfiles; + + std::string private_keyfile = hashed_keyfile_name(cfg.intf.private_key); + + return SystemdConfig { + .netdev = { + .name = cfg.intf.name + ".netdev", + .contents = _gen_netdev_cfg(cfg, fwd_table, private_keyfile, symmetric_keyfiles, output_path), + }, + .network = { + .name = cfg.intf.name + ".network", + .contents = _gen_network_cfg(cfg, fwd_table) + }, + .private_keyfile = { + .name = private_keyfile, + .contents = cfg.intf.private_key + "\n", + }, + .symmetric_keyfiles = std::move(symmetric_keyfiles) + }; + } + + SystemdConfig wg2sd(std::string const & interface_name, std::istream & stream, std::string const & output_path) { + return gen_systemd_config(parse_config(interface_name, stream), output_path); + } + +} -- cgit v1.2.3