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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/client/sasl_scram_client_conversation.h"
#include <boost/algorithm/string/replace.hpp>
#include "mongo/base/parse_number.h"
#include "mongo/client/scram_client_cache.h"
#include "mongo/platform/random.h"
#include "mongo/util/base64.h"
#include "mongo/util/password_digest.h"
#include "mongo/util/str.h"
#include "mongo/util/text.h"
namespace mongo {
using std::string;
using std::unique_ptr;
StatusWith<bool> SaslSCRAMClientConversation::step(StringData inputData, std::string* outputData) {
_step++;
switch (_step) {
case 1:
return _firstStep(outputData);
case 2:
return _secondStep(inputData, outputData);
case 3:
return _thirdStep(inputData, outputData);
default:
return StatusWith<bool>(ErrorCodes::AuthenticationFailed,
str::stream()
<< "Invalid SCRAM authentication step: " << _step);
}
}
/*
* RFC 5802 specifies that in SCRAM user names characters ',' and '=' are encoded as
* =2C and =3D respectively.
*/
static void encodeSCRAMUsername(std::string& user) {
boost::replace_all(user, "=", "=3D");
boost::replace_all(user, ",", "=2C");
}
/*
* Generate client-first-message of the form:
* n,a=authzid,n=encoded-username,r=client-nonce
*/
StatusWith<bool> SaslSCRAMClientConversation::_firstStep(std::string* outputData) {
if (_saslClientSession->getParameter(SaslClientSession::parameterPassword).empty()) {
return Status(ErrorCodes::BadValue, "Empty client password provided");
}
// Create text-based nonce as base64 encoding of a binary blob of length multiple of 3
static constexpr size_t nonceLenQWords = 3;
uint64_t binaryNonce[nonceLenQWords];
SecureRandom().fill(binaryNonce, sizeof(binaryNonce));
std::string user =
_saslClientSession->getParameter(SaslClientSession::parameterUser).toString();
encodeSCRAMUsername(user);
_clientNonce = base64::encode(reinterpret_cast<char*>(binaryNonce), sizeof(binaryNonce));
// Append client-first-message-bare to authMessage
_authMessage = "n=" + user + ",r=" + _clientNonce;
StringBuilder sb;
sb << "n,," << _authMessage;
*outputData = sb.str();
return false;
}
/**
* Parse server-first-message on the form:
* [reserved-mext ',']r=client-nonce|server-nonce,s=user-salt,i=iteration-count[,extensions]
*
* Generate client-final-message of the form:
* c=channel-binding(base64),r=client-nonce|server-nonce,p=ClientProof
*
**/
StatusWith<bool> SaslSCRAMClientConversation::_secondStep(StringData inputData,
std::string* outputData) {
if (inputData.startsWith("m=")) {
return Status(ErrorCodes::BadValue, "SCRAM required extensions not supported");
}
const auto input = StringSplitter::split(inputData.toString(), ",");
if (input.size() < 3) {
return Status(ErrorCodes::BadValue,
str::stream()
<< "Incorrect number of arguments for first SCRAM server message, got "
<< input.size() << " expected at least 3");
}
if (!str::startsWith(input[0], "r=") || input[0].size() < 3) {
return Status(ErrorCodes::BadValue,
str::stream() << "Incorrect SCRAM client|server nonce: " << input[0]);
}
const auto nonce = input[0].substr(2);
if (!str::startsWith(nonce, _clientNonce)) {
return Status(ErrorCodes::BadValue,
str::stream() << "Server SCRAM nonce does not match client nonce: " << nonce);
}
if (!str::startsWith(input[1], "s=") || input[1].size() < 6) {
return Status(ErrorCodes::BadValue, str::stream() << "Incorrect SCRAM salt: " << input[1]);
}
const auto salt64 = input[1].substr(2);
if (!str::startsWith(input[2], "i=") || input[2].size() < 3) {
return Status(ErrorCodes::BadValue,
str::stream() << "Incorrect SCRAM iteration count: " << input[2]);
}
size_t iterationCount;
Status status = NumberParser().base(10)(input[2].substr(2), &iterationCount);
if (!status.isOK()) {
return Status(ErrorCodes::BadValue,
str::stream() << "Failed to parse SCRAM iteration count: " << input[2]);
}
// Append server-first-message and client-final-message-without-proof.
_authMessage += "," + inputData.toString() + ",c=biws,r=" + nonce;
std::string decodedSalt, clientProof;
try {
decodedSalt = base64::decode(salt64);
clientProof = generateClientProof(
std::vector<std::uint8_t>(decodedSalt.begin(), decodedSalt.end()), iterationCount);
} catch (const DBException& ex) {
return ex.toStatus();
}
StringBuilder sb;
sb << "c=biws,r=" << nonce << ",p=" << clientProof;
*outputData = sb.str();
return false;
}
/**
* Verify server-final-message on the form:
* v=ServerSignature
*
* or failed authentication server-final-message on the form:
* e=message
**/
StatusWith<bool> SaslSCRAMClientConversation::_thirdStep(StringData inputData,
std::string* outputData) {
const auto input = StringSplitter::split(inputData.toString(), ",");
if (input.empty()) {
return Status(
ErrorCodes::BadValue,
"Incorrect number of arguments for final SCRAM server message, got 0 expected 1");
}
if (input[0].size() < 3) {
return Status(ErrorCodes::BadValue,
str::stream() << "Incorrect SCRAM server message length: " << input[0]);
}
if (str::startsWith(input[0], "e=")) {
return Status(ErrorCodes::AuthenticationFailed,
str::stream() << "SCRAM authentication failure: " << input[0].substr(2));
}
if (!str::startsWith(input[0], "v=")) {
return Status(ErrorCodes::BadValue,
str::stream() << "Incorrect SCRAM ServerSignature: " << input[0]);
}
if (!verifyServerSignature(base64::decode(input[0].substr(2)))) {
*outputData = "e=Invalid server signature";
return Status(ErrorCodes::BadValue,
str::stream() << "Client failed to verify SCRAM ServerSignature, received "
<< input[0].substr(2));
}
*outputData = "";
return true;
}
} // namespace mongo
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