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
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
|
/*
* Copyright (C) 2006-2008 Stig Venaas <venaas@uninett.no>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*/
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include "list.h"
#include "tlv11.h"
#include "radmsg.h"
#include "debug.h"
#include <pthread.h>
#include <openssl/hmac.h>
#define RADLEN(x) ntohs(((uint16_t *)(x))[1])
void radmsg_free(struct radmsg *msg) {
if (msg) {
freetlvlist(msg->attrs);
free(msg);
}
}
struct radmsg *radmsg_init(uint8_t code, uint8_t id, uint8_t *auth) {
struct radmsg *msg;
msg = malloc(sizeof(struct radmsg));
if (!msg)
return NULL;
msg->attrs = list_create();
if (!msg->attrs) {
free(msg);
return NULL;
}
msg->code = code;
msg->id = id;
memcpy(msg->auth, auth, 16);
return msg;
}
int radmsg_add(struct radmsg *msg, struct tlv *attr) {
if (!msg || !msg->attrs)
return 1;
if (!attr)
return 0;
return list_push(msg->attrs, attr);
}
/* returns first tlv of the given type */
struct tlv *radmsg_gettype(struct radmsg *msg, uint8_t type) {
struct list_node *node;
struct tlv *tlv;
if (!msg)
return NULL;
for (node = list_first(msg->attrs); node; node = list_next(node)) {
tlv = (struct tlv *)node->data;
if (tlv->t == type)
return tlv;
}
return NULL;
}
uint8_t *radmsg2buf(struct radmsg *msg) {
struct list_node *node;
struct tlv *tlv;
int size;
uint8_t *buf, *p;
if (!msg || !msg->attrs)
return NULL;
size = 20;
for (node = list_first(msg->attrs); node; node = list_next(node))
size += 2 + ((struct tlv *)node->data)->l;
if (size > 65535)
return NULL;
buf = malloc(size);
if (!buf)
return NULL;
p = buf;
*p++ = msg->code;
*p++ = msg->id;
*(uint16_t *)p = htons(size);
p += 2;
memcpy(p, msg->auth, 16);
p += 16;
for (node = list_first(msg->attrs); node; node = list_next(node)) {
tlv = (struct tlv *)node->data;
p = tlv2buf(p, tlv);
p[-1] += 2;
p += tlv->l;
}
return buf;
}
int _checkmsgauth(unsigned char *rad, uint8_t *authattr, uint8_t *secret) {
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
static unsigned char first = 1;
static HMAC_CTX hmacctx;
unsigned int md_len;
uint8_t auth[16], hash[EVP_MAX_MD_SIZE];
pthread_mutex_lock(&lock);
if (first) {
HMAC_CTX_init(&hmacctx);
first = 0;
}
memcpy(auth, authattr, 16);
memset(authattr, 0, 16);
md_len = 0;
HMAC_Init_ex(&hmacctx, secret, strlen((char *)secret), EVP_md5(), NULL);
HMAC_Update(&hmacctx, rad, RADLEN(rad));
HMAC_Final(&hmacctx, hash, &md_len);
memcpy(authattr, auth, 16);
if (md_len != 16) {
debug(DBG_WARN, "message auth computation failed");
pthread_mutex_unlock(&lock);
return 0;
}
if (memcmp(auth, hash, 16)) {
debug(DBG_WARN, "message authenticator, wrong value");
pthread_mutex_unlock(&lock);
return 0;
}
pthread_mutex_unlock(&lock);
return 1;
}
int _validauth(unsigned char *rad, unsigned char *reqauth, unsigned char *sec) {
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
static unsigned char first = 1;
static EVP_MD_CTX mdctx;
unsigned char hash[EVP_MAX_MD_SIZE];
unsigned int len;
int result;
pthread_mutex_lock(&lock);
if (first) {
EVP_MD_CTX_init(&mdctx);
first = 0;
}
len = RADLEN(rad);
result = (EVP_DigestInit_ex(&mdctx, EVP_md5(), NULL) &&
EVP_DigestUpdate(&mdctx, rad, 4) &&
EVP_DigestUpdate(&mdctx, reqauth, 16) &&
(len <= 20 || EVP_DigestUpdate(&mdctx, rad + 20, len - 20)) &&
EVP_DigestUpdate(&mdctx, sec, strlen((char *)sec)) &&
EVP_DigestFinal_ex(&mdctx, hash, &len) &&
len == 16 &&
!memcmp(hash, rad + 4, 16));
pthread_mutex_unlock(&lock);
return result;
}
/* if secret set we also validate message authenticator if present */
struct radmsg *buf2radmsg(uint8_t *buf, uint8_t *secret, uint8_t *rqauth) {
struct radmsg *msg;
uint8_t t, l, *v, *p, auth[16];
uint16_t len;
struct tlv *attr;
len = RADLEN(buf);
if (len < 20)
return NULL;
if (secret && buf[0] == RAD_Accounting_Request) {
memset(auth, 0, 16);
if (!_validauth(buf, auth, secret)) {
debug(DBG_WARN, "buf2radmsg: Accounting-Request message authentication failed");
return NULL;
}
}
if (rqauth && !_validauth(buf, rqauth, secret)) {
debug(DBG_WARN, "buf2radmsg: Invalid auth, ignoring reply");
return NULL;
}
msg = radmsg_init(buf[0], buf[1], (uint8_t *)buf + 4);
if (!msg)
return NULL;
p = buf + 20;
while (p - buf + 2 <= len) {
t = *p++;
l = *p++;
if (l < 2) {
debug(DBG_WARN, "buf2radmsg: invalid attribute length %d", l);
radmsg_free(msg);
return NULL;
}
l -= 2;
if (l) {
if (p - buf + l > len) {
debug(DBG_WARN, "buf2radmsg: attribute length %d exceeds packet length", l + 2);
radmsg_free(msg);
return NULL;
}
v = p;
p += l;
}
if (t == RAD_Attr_Message_Authenticator && secret) {
if (rqauth)
memcpy(buf + 4, rqauth, 16);
if (l != 16 || !_checkmsgauth(buf, v, secret)) {
debug(DBG_WARN, "buf2radmsg: message authentication failed");
if (rqauth)
memcpy(buf + 4, msg->auth, 16);
radmsg_free(msg);
return NULL;
}
if (rqauth)
memcpy(buf + 4, msg->auth, 16);
debug(DBG_DBG, "buf2radmsg: message auth ok");
}
attr = maketlv(t, l, v);
if (!attr || !radmsg_add(msg, attr)) {
freetlv(attr);
radmsg_free(msg);
return NULL;
}
}
return msg;
}
|
