summaryrefslogtreecommitdiff
path: root/src/mongo/client/sasl_scram_client_conversation.cpp
blob: 6c2fa950e2280df961eb876f09cd708bc21e78d8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
/*
 *    Copyright (C) 2014 MongoDB Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    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 Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    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 GNU Affero General 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/mongoutils/str.h"
#include "mongo/util/password_digest.h"
#include "mongo/util/text.h"

namespace mongo {

using std::unique_ptr;
using std::string;

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,
                mongoutils::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
    const int nonceLenQWords = 3;
    uint64_t binaryNonce[nonceLenQWords];

    unique_ptr<SecureRandom> sr(SecureRandom::create());

    binaryNonce[0] = sr->nextInt64();
    binaryNonce[1] = sr->nextInt64();
    binaryNonce[2] = sr->nextInt64();

    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 = parseNumberFromStringWithBase(input[2].substr(2), 10, &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