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
|
/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
/* CRAM-MD5 SASL authentication, see RFC-2195
Joshua Goodall <joshua@roughtrade.net> */
#include "auth-common.h"
#include "ioloop.h"
#include "buffer.h"
#include "hex-binary.h"
#include "hmac-cram-md5.h"
#include "hmac.h"
#include "md5.h"
#include "randgen.h"
#include "mech.h"
#include "passdb.h"
#include "hostpid.h"
#include <time.h>
struct cram_auth_request {
struct auth_request auth_request;
pool_t pool;
/* requested: */
char *challenge;
/* received: */
char *username;
char *response;
unsigned long maxbuf;
};
static const char *get_cram_challenge(void)
{
unsigned char buf[17];
size_t i;
random_fill(buf, sizeof(buf)-1);
for (i = 0; i < sizeof(buf)-1; i++)
buf[i] = (buf[i] % 10) + '0';
buf[sizeof(buf)-1] = '\0';
return t_strdup_printf("<%s.%s@%s>", (const char *)buf,
dec2str(ioloop_time), my_hostname);
}
static bool verify_credentials(struct cram_auth_request *request,
const unsigned char *credentials, size_t size)
{
unsigned char digest[MD5_RESULTLEN];
struct hmac_context ctx;
const char *response_hex;
if (size != CRAM_MD5_CONTEXTLEN) {
e_error(request->auth_request.mech_event,
"invalid credentials length");
return FALSE;
}
hmac_init(&ctx, NULL, 0, &hash_method_md5);
hmac_md5_set_cram_context(&ctx, credentials);
hmac_update(&ctx, request->challenge, strlen(request->challenge));
hmac_final(&ctx, digest);
response_hex = binary_to_hex(digest, sizeof(digest));
if (!mem_equals_timing_safe(response_hex, request->response, sizeof(digest)*2)) {
e_info(request->auth_request.mech_event,
AUTH_LOG_MSG_PASSWORD_MISMATCH);
return FALSE;
}
return TRUE;
}
static bool parse_cram_response(struct cram_auth_request *request,
const unsigned char *data, size_t size,
const char **error_r)
{
size_t i, space;
*error_r = NULL;
/* <username> SPACE <response>. Username may contain spaces, so assume
the rightmost space is the response separator. */
for (i = space = 0; i < size; i++) {
if (data[i] == '\0') {
*error_r = "NULs in response";
return FALSE;
}
if (data[i] == ' ')
space = i;
}
if (space == 0) {
*error_r = "missing digest";
return FALSE;
}
request->username = p_strndup(request->pool, data, space);
space++;
request->response =
p_strndup(request->pool, data + space, size - space);
return TRUE;
}
static void credentials_callback(enum passdb_result result,
const unsigned char *credentials, size_t size,
struct auth_request *auth_request)
{
struct cram_auth_request *request =
(struct cram_auth_request *)auth_request;
switch (result) {
case PASSDB_RESULT_OK:
if (verify_credentials(request, credentials, size))
auth_request_success(auth_request, "", 0);
else
auth_request_fail(auth_request);
break;
case PASSDB_RESULT_INTERNAL_FAILURE:
auth_request_internal_failure(auth_request);
break;
default:
auth_request_fail(auth_request);
break;
}
}
static void
mech_cram_md5_auth_continue(struct auth_request *auth_request,
const unsigned char *data, size_t data_size)
{
struct cram_auth_request *request =
(struct cram_auth_request *)auth_request;
const char *error;
if (parse_cram_response(request, data, data_size, &error)) {
if (auth_request_set_username(auth_request, request->username,
&error)) {
auth_request_lookup_credentials(auth_request,
"CRAM-MD5", credentials_callback);
return;
}
}
if (error == NULL)
error = "authentication failed";
e_info(auth_request->mech_event, "%s", error);
auth_request_fail(auth_request);
}
static void
mech_cram_md5_auth_initial(struct auth_request *auth_request,
const unsigned char *data ATTR_UNUSED,
size_t data_size ATTR_UNUSED)
{
struct cram_auth_request *request =
(struct cram_auth_request *)auth_request;
request->challenge = p_strdup(request->pool, get_cram_challenge());
auth_request_handler_reply_continue(auth_request, request->challenge,
strlen(request->challenge));
}
static struct auth_request *mech_cram_md5_auth_new(void)
{
struct cram_auth_request *request;
pool_t pool;
pool = pool_alloconly_create(MEMPOOL_GROWING"cram_md5_auth_request", 2048);
request = p_new(pool, struct cram_auth_request, 1);
request->pool = pool;
request->auth_request.pool = pool;
return &request->auth_request;
}
const struct mech_module mech_cram_md5 = {
"CRAM-MD5",
.flags = MECH_SEC_DICTIONARY | MECH_SEC_ACTIVE,
.passdb_need = MECH_PASSDB_NEED_VERIFY_RESPONSE,
mech_cram_md5_auth_new,
mech_cram_md5_auth_initial,
mech_cram_md5_auth_continue,
mech_generic_auth_free
};
|
