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Diffstat (limited to '')
| -rw-r--r-- | credentials.cc | 483 |
1 files changed, 483 insertions, 0 deletions
diff --git a/credentials.cc b/credentials.cc new file mode 100644 index 0000000..137f1b7 --- /dev/null +++ b/credentials.cc @@ -0,0 +1,483 @@ +/* + * This file is part of PowerDNS or dnsdist. + * Copyright -- PowerDNS.COM B.V. and its contributors + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of version 2 of the GNU General Public License as + * published by the Free Software Foundation. + * + * In addition, for the avoidance of any doubt, permission is granted to + * link this program with OpenSSL and to (re)distribute the binaries + * produced as the result of such linking. + * + * 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, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ +#include "config.h" + +#include <cmath> +#include <stdexcept> + +#ifdef HAVE_LIBSODIUM +#include <sodium.h> +#endif + +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) +#include <openssl/evp.h> +#include <openssl/kdf.h> +#include <openssl/opensslv.h> +#include <openssl/rand.h> +#endif + +#include <fcntl.h> +#include <sys/stat.h> +#include <unistd.h> + +#include "base64.hh" +#include "credentials.hh" +#include "misc.hh" + +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) +static size_t const pwhash_max_size = 128U; /* maximum size of the output */ +static size_t const pwhash_output_size = 32U; /* size of the hashed output (before base64 encoding) */ +static unsigned int const pwhash_salt_size = 16U; /* size of the salt (before base64 encoding */ +static uint64_t const pwhash_max_work_factor = 32768U; /* max N for interactive login purposes */ + +/* PHC string format, storing N as log2(N) as done by passlib. + for now we only support one algo but we might have to change that later */ +static std::string const pwhash_prefix = "$scrypt$"; +static size_t const pwhash_prefix_size = pwhash_prefix.size(); +#endif + +uint64_t const CredentialsHolder::s_defaultWorkFactor{1024U}; /* N */ +uint64_t const CredentialsHolder::s_defaultParallelFactor{1U}; /* p */ +uint64_t const CredentialsHolder::s_defaultBlockSize{8U}; /* r */ + +SensitiveData::SensitiveData(std::string&& data) : + d_data(std::move(data)) +{ + data.clear(); +#ifdef HAVE_LIBSODIUM + sodium_mlock(d_data.data(), d_data.size()); +#endif +} + +SensitiveData& SensitiveData::operator=(SensitiveData&& rhs) +{ + d_data = std::move(rhs.d_data); + rhs.clear(); + return *this; +} + +SensitiveData::SensitiveData(size_t bytes) +{ + d_data.resize(bytes); +#ifdef HAVE_LIBSODIUM + sodium_mlock(d_data.data(), d_data.size()); +#endif +} + +SensitiveData::~SensitiveData() +{ + clear(); +} + +void SensitiveData::clear() +{ +#ifdef HAVE_LIBSODIUM + sodium_munlock(d_data.data(), d_data.size()); +#endif + d_data.clear(); +} + +static std::string hashPasswordInternal(const std::string& password, const std::string& salt, uint64_t workFactor, uint64_t parallelFactor, uint64_t blockSize) +{ +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) + auto pctx = std::unique_ptr<EVP_PKEY_CTX, void (*)(EVP_PKEY_CTX*)>(EVP_PKEY_CTX_new_id(EVP_PKEY_SCRYPT, nullptr), EVP_PKEY_CTX_free); + if (!pctx) { + throw std::runtime_error("Error getting a scrypt context to hash the supplied password"); + } + + if (EVP_PKEY_derive_init(pctx.get()) <= 0) { + throw std::runtime_error("Error intializing the scrypt context to hash the supplied password"); + } + + // OpenSSL 3.0 changed the string arg to const unsigned char*, other versions use const char * +#if OPENSSL_VERSION_MAJOR >= 3 + auto passwordData = reinterpret_cast<const char*>(password.data()); +#else + auto passwordData = reinterpret_cast<const unsigned char*>(password.data()); +#endif + if (EVP_PKEY_CTX_set1_pbe_pass(pctx.get(), passwordData, password.size()) <= 0) { + throw std::runtime_error("Error adding the password to the scrypt context to hash the supplied password"); + } + + if (EVP_PKEY_CTX_set1_scrypt_salt(pctx.get(), reinterpret_cast<const unsigned char*>(salt.data()), salt.size()) <= 0) { + throw std::runtime_error("Error adding the salt to the scrypt context to hash the supplied password"); + } + + if (EVP_PKEY_CTX_set_scrypt_N(pctx.get(), workFactor) <= 0) { + throw std::runtime_error("Error setting the work factor to the scrypt context to hash the supplied password"); + } + + if (EVP_PKEY_CTX_set_scrypt_r(pctx.get(), blockSize) <= 0) { + throw std::runtime_error("Error setting the block size to the scrypt context to hash the supplied password"); + } + + if (EVP_PKEY_CTX_set_scrypt_p(pctx.get(), parallelFactor) <= 0) { + throw std::runtime_error("Error setting the parallel factor to the scrypt context to hash the supplied password"); + } + + std::string out; + out.resize(pwhash_output_size); + size_t outlen = out.size(); + + if (EVP_PKEY_derive(pctx.get(), reinterpret_cast<unsigned char*>(out.data()), &outlen) <= 0 || outlen != pwhash_output_size) { + throw std::runtime_error("Error deriving the output from the scrypt context to hash the supplied password"); + } + + return out; +#else + throw std::runtime_error("Hashing support is not available"); +#endif +} + +static std::string generateRandomSalt() +{ +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) + /* generate a random salt */ + std::string salt; + salt.resize(pwhash_salt_size); + + if (RAND_bytes(reinterpret_cast<unsigned char*>(salt.data()), salt.size()) != 1) { + throw std::runtime_error("Error while generating a salt to hash the supplied password"); + } + + return salt; +#else + throw std::runtime_error("Generating a salted password requires scrypt support in OpenSSL, and it is not available"); +#endif +} + +std::string hashPassword(const std::string& password, uint64_t workFactor, uint64_t parallelFactor, uint64_t blockSize) +{ +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) + if (workFactor == 0) { + throw std::runtime_error("Invalid work factor of " + std::to_string(workFactor) + " passed to hashPassword()"); + } + + std::string result; + result.reserve(pwhash_max_size); + + result.append(pwhash_prefix); + result.append("ln="); + result.append(std::to_string(static_cast<uint64_t>(std::log2(workFactor)))); + result.append(",p="); + result.append(std::to_string(parallelFactor)); + result.append(",r="); + result.append(std::to_string(blockSize)); + result.append("$"); + auto salt = generateRandomSalt(); + result.append(Base64Encode(salt)); + result.append("$"); + + auto out = hashPasswordInternal(password, salt, workFactor, parallelFactor, blockSize); + + result.append(Base64Encode(out)); + + return result; +#else + throw std::runtime_error("Hashing a password requires scrypt support in OpenSSL, and it is not available"); +#endif +} + +std::string hashPassword(const std::string& password) +{ +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) + return hashPassword(password, CredentialsHolder::s_defaultWorkFactor, CredentialsHolder::s_defaultParallelFactor, CredentialsHolder::s_defaultBlockSize); +#else + throw std::runtime_error("Hashing a password requires scrypt support in OpenSSL, and it is not available"); +#endif +} + +bool verifyPassword(const std::string& binaryHash, const std::string& salt, uint64_t workFactor, uint64_t parallelFactor, uint64_t blockSize, const std::string& binaryPassword) +{ +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) + auto expected = hashPasswordInternal(binaryPassword, salt, workFactor, parallelFactor, blockSize); + return constantTimeStringEquals(expected, binaryHash); +#else + throw std::runtime_error("Hashing a password requires scrypt support in OpenSSL, and it is not available"); +#endif +} + +/* parse a hashed password in PHC string format */ +static void parseHashed(const std::string& hash, std::string& salt, std::string& hashedPassword, uint64_t& workFactor, uint64_t& parallelFactor, uint64_t& blockSize) +{ +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) + auto parametersEnd = hash.find('$', pwhash_prefix.size()); + if (parametersEnd == std::string::npos || parametersEnd == hash.size()) { + throw std::runtime_error("Invalid hashed password format, no parameters"); + } + + auto parametersStr = hash.substr(pwhash_prefix.size(), parametersEnd); + std::vector<std::string> parameters; + parameters.reserve(3); + stringtok(parameters, parametersStr, ","); + if (parameters.size() != 3) { + throw std::runtime_error("Invalid hashed password format, expecting 3 parameters, got " + std::to_string(parameters.size())); + } + + if (!boost::starts_with(parameters.at(0), "ln=")) { + throw std::runtime_error("Invalid hashed password format, ln= parameter not found"); + } + + if (!boost::starts_with(parameters.at(1), "p=")) { + throw std::runtime_error("Invalid hashed password format, p= parameter not found"); + } + + if (!boost::starts_with(parameters.at(2), "r=")) { + throw std::runtime_error("Invalid hashed password format, r= parameter not found"); + } + + auto saltPos = parametersEnd + 1; + auto saltEnd = hash.find('$', saltPos); + if (saltEnd == std::string::npos || saltEnd == hash.size()) { + throw std::runtime_error("Invalid hashed password format"); + } + + try { + workFactor = pdns::checked_stoi<uint64_t>(parameters.at(0).substr(3)); + workFactor = static_cast<uint64_t>(1) << workFactor; + if (workFactor > pwhash_max_work_factor) { + throw std::runtime_error("Invalid work factor of " + std::to_string(workFactor) + " in hashed password string, maximum is " + std::to_string(pwhash_max_work_factor)); + } + + parallelFactor = pdns::checked_stoi<uint64_t>(parameters.at(1).substr(2)); + blockSize = pdns::checked_stoi<uint64_t>(parameters.at(2).substr(2)); + + auto b64Salt = hash.substr(saltPos, saltEnd - saltPos); + salt.reserve(pwhash_salt_size); + B64Decode(b64Salt, salt); + + if (salt.size() != pwhash_salt_size) { + throw std::runtime_error("Invalid salt in hashed password string"); + } + + hashedPassword.reserve(pwhash_output_size); + B64Decode(hash.substr(saltEnd + 1), hashedPassword); + + if (hashedPassword.size() != pwhash_output_size) { + throw std::runtime_error("Invalid hash in hashed password string"); + } + } + catch (const std::exception& e) { + throw std::runtime_error("Invalid hashed password format, unable to parse parameters"); + } +#endif +} + +bool verifyPassword(const std::string& hash, const std::string& password) +{ + if (!isPasswordHashed(hash)) { + return false; + } + +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) + std::string salt; + std::string hashedPassword; + uint64_t workFactor = 0; + uint64_t parallelFactor = 0; + uint64_t blockSize = 0; + parseHashed(hash, salt, hashedPassword, workFactor, parallelFactor, blockSize); + + auto expected = hashPasswordInternal(password, salt, workFactor, parallelFactor, blockSize); + + return constantTimeStringEquals(expected, hashedPassword); +#else + throw std::runtime_error("Verifying a hashed password requires scrypt support in OpenSSL, and it is not available"); +#endif +} + +bool isPasswordHashed(const std::string& password) +{ +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) + if (password.size() < pwhash_prefix_size || password.size() > pwhash_max_size) { + return false; + } + + if (!boost::starts_with(password, pwhash_prefix)) { + return false; + } + + auto parametersEnd = password.find('$', pwhash_prefix.size()); + if (parametersEnd == std::string::npos || parametersEnd == password.size()) { + return false; + } + + size_t parametersSize = parametersEnd - pwhash_prefix.size(); + /* ln=X,p=Y,r=Z */ + if (parametersSize < 12) { + return false; + } + + auto saltEnd = password.find('$', parametersEnd + 1); + if (saltEnd == std::string::npos || saltEnd == password.size()) { + return false; + } + + /* the salt is base64 encoded so it has to be larger than that */ + if ((saltEnd - parametersEnd - 1) < pwhash_salt_size) { + return false; + } + + /* the hash base64 encoded so it has to be larger than that */ + if ((password.size() - saltEnd - 1) < pwhash_output_size) { + return false; + } + + return true; +#else + return false; +#endif +} + +/* if the password is in cleartext and hashing is available, + the hashed form will be kept in memory */ +CredentialsHolder::CredentialsHolder(std::string&& password, bool hashPlaintext) : + d_credentials(std::move(password)) +{ + if (isHashingAvailable()) { + if (!isPasswordHashed(d_credentials.getString())) { + if (hashPlaintext) { + d_salt = generateRandomSalt(); + d_workFactor = s_defaultWorkFactor; + d_parallelFactor = s_defaultParallelFactor; + d_blockSize = s_defaultBlockSize; + d_credentials = SensitiveData(hashPasswordInternal(d_credentials.getString(), d_salt, d_workFactor, d_parallelFactor, d_blockSize)); + d_isHashed = true; + } + } + else { + d_wasHashed = true; + d_isHashed = true; + std::string hashedPassword; + parseHashed(d_credentials.getString(), d_salt, hashedPassword, d_workFactor, d_parallelFactor, d_blockSize); + d_credentials = SensitiveData(std::move(hashedPassword)); + } + } + + if (!d_isHashed) { + d_fallbackHashPerturb = random(); + d_fallbackHash = burtle(reinterpret_cast<const unsigned char*>(d_credentials.getString().data()), d_credentials.getString().size(), d_fallbackHashPerturb); + } +} + +CredentialsHolder::~CredentialsHolder() +{ + d_fallbackHashPerturb = 0; + d_fallbackHash = 0; +} + +bool CredentialsHolder::matches(const std::string& password) const +{ + if (d_isHashed) { + return verifyPassword(d_credentials.getString(), d_salt, d_workFactor, d_parallelFactor, d_blockSize, password); + } + else { + uint32_t fallback = burtle(reinterpret_cast<const unsigned char*>(password.data()), password.size(), d_fallbackHashPerturb); + if (fallback != d_fallbackHash) { + return false; + } + + return constantTimeStringEquals(password, d_credentials.getString()); + } +} + +bool CredentialsHolder::isHashingAvailable() +{ +#if !defined(DISABLE_HASHED_CREDENTIALS) && defined(HAVE_EVP_PKEY_CTX_SET1_SCRYPT_SALT) + return true; +#else + return false; +#endif +} + +#include <csignal> +#include <termios.h> + +SensitiveData CredentialsHolder::readFromTerminal() +{ + struct termios term; + struct termios oterm; + bool restoreTermSettings = false; + int termAction = TCSAFLUSH; +#ifdef TCSASOFT + termAction |= TCSASOFT; +#endif + + FDWrapper input(open("/dev/tty", O_RDONLY)); + if (int(input) != -1) { + if (tcgetattr(input, &oterm) == 0) { + memcpy(&term, &oterm, sizeof(term)); + term.c_lflag &= ~(ECHO | ECHONL); + tcsetattr(input, termAction, &term); + restoreTermSettings = true; + } + } + else { + input = FDWrapper(dup(STDIN_FILENO)); + restoreTermSettings = false; + } + + FDWrapper output(open("/dev/tty", O_WRONLY)); + if (int(output) == -1) { + output = FDWrapper(dup(STDERR_FILENO)); + } + + struct std::map<int, struct sigaction> signals; + struct sigaction sa; + sigemptyset(&sa.sa_mask); + sa.sa_flags = 0; + sa.sa_handler = [](int /* s */) {}; + sigaction(SIGALRM, &sa, &signals[SIGALRM]); + sigaction(SIGHUP, &sa, &signals[SIGHUP]); + sigaction(SIGINT, &sa, &signals[SIGINT]); + sigaction(SIGPIPE, &sa, &signals[SIGPIPE]); + sigaction(SIGQUIT, &sa, &signals[SIGQUIT]); + sigaction(SIGTERM, &sa, &signals[SIGTERM]); + sigaction(SIGTSTP, &sa, &signals[SIGTSTP]); + sigaction(SIGTTIN, &sa, &signals[SIGTTIN]); + sigaction(SIGTTOU, &sa, &signals[SIGTTOU]); + + std::string buffer; + /* let's allocate a huge buffer now to prevent reallocation, + which would leave parts of the buffer around */ + buffer.reserve(512); + + for (;;) { + char ch = '\0'; + auto got = read(input, &ch, 1); + if (got == 1 && ch != '\n' && ch != '\r') { + buffer.push_back(ch); + } + else { + break; + } + } + + if (restoreTermSettings) { + tcsetattr(input, termAction, &oterm); + } + + for (const auto& sig : signals) { + sigaction(sig.first, &sig.second, nullptr); + } + + return SensitiveData(std::move(buffer)); +} |