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
|
/**
* Copyright (C) 2017 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.
*/
#pragma once
#include <boost/optional.hpp>
#include <string>
#include "mongo/crypto/mechanism_scram.h"
#include "mongo/platform/unordered_map.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/net/hostandport.h"
namespace mongo {
/**
* A cache for the intermediate steps of the SCRAM-SHA-1 computation.
*
* Clients wishing to authenticate to a server using SCRAM-SHA-1
* must produce a set of credential objects from their password,
* a salt, and an iteration count. The computation to generate these
* is very expensive, proportional to the iteration count. The high
* cost of this computation prevents brute force attacks on
* intercepted SCRAM authentication data, or a stolen password
* database. The inputs to the function are unlikely to frequently
* change. Caching the relationship between the inputs and the
* resulting output should make repeated authentication attempts
* to a single server much faster.
*
* This is explicitly permitted by RFC5802, section 5.1:
*
* "Note that a client implementation MAY cache
* ClientKey&ServerKey (or just SaltedPassword) for later
* reauthentication to the same service, as it is likely that the
* server is going to advertise the same salt value upon
* reauthentication. This might be useful for mobile clients where
* CPU usage is a concern."
*/
class SCRAMSHA1ClientCache {
public:
/**
* Returns precomputed SCRAMSecrets, if one has already been
* stored for the specified hostname and the provided presecrets
* match those recorded for the hostname. Otherwise, no secrets
* are returned.
*/
boost::optional<scram::SCRAMSecrets> getCachedSecrets(
const HostAndPort& target, const scram::SCRAMPresecrets& presecrets) const;
/**
* Records a set of precomputed SCRAMSecrets for the specified
* host, along with the presecrets used to generate them.
*/
void setCachedSecrets(HostAndPort target,
scram::SCRAMPresecrets presecrets,
scram::SCRAMSecrets secrets);
private:
mutable stdx::mutex _hostToSecretsMutex;
std::unordered_map<HostAndPort, std::pair<scram::SCRAMPresecrets, scram::SCRAMSecrets>>
_hostToSecrets;
};
} // namespace mongo
|
