summaryrefslogtreecommitdiff
path: root/src/openvpn/ntlm.c
blob: e3707484d593801945a1dc51e75401a25c38f67b (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
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
/*
 *  ntlm proxy support for OpenVPN
 *
 *  Copyright (C) 2004 William Preston
 *
 *  *NTLMv2 support and domain name parsing by Miroslav Zajic, Nextsoft s.r.o.*
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_MSC_VER)
#include "config-msvc.h"
#endif

#include "syshead.h"

#if NTLM

#include "common.h"
#include "buffer.h"
#include "misc.h"
#include "socket.h"
#include "fdmisc.h"
#include "proxy.h"
#include "ntlm.h"
#include "base64.h"
#include "crypto.h"

#include "memdbg.h"


/* 64bit datatype macros */
#ifdef _MSC_VER
/* MS compilers */
#define UINTEGER64 __int64
#define UINT64(c) c ## Ui64
#else
/* Non MS compilers */
#define UINTEGER64 unsigned long long
#define UINT64(c) c ## LL
#endif



static void
create_des_keys(const unsigned char *hash, unsigned char *key)
{
    key[0] = hash[0];
    key[1] = ((hash[0] & 1) << 7) | (hash[1] >> 1);
    key[2] = ((hash[1] & 3) << 6) | (hash[2] >> 2);
    key[3] = ((hash[2] & 7) << 5) | (hash[3] >> 3);
    key[4] = ((hash[3] & 15) << 4) | (hash[4] >> 4);
    key[5] = ((hash[4] & 31) << 3) | (hash[5] >> 5);
    key[6] = ((hash[5] & 63) << 2) | (hash[6] >> 6);
    key[7] = ((hash[6] & 127) << 1);
    key_des_fixup(key, 8, 1);
}

static void
gen_md4_hash(const uint8_t *data, int data_len, uint8_t *result)
{
    /* result is 16 byte md4 hash */
    const md_kt_t *md4_kt = md_kt_get("MD4");
    uint8_t md[MD4_DIGEST_LENGTH];

    md_full(md4_kt, data, data_len, md);
    memcpy(result, md, MD4_DIGEST_LENGTH);
}

static void
gen_hmac_md5(const uint8_t *data, int data_len, const uint8_t *key, int key_len,
             uint8_t *result)
{
    const md_kt_t *md5_kt = md_kt_get("MD5");
    hmac_ctx_t *hmac_ctx = hmac_ctx_new();

    hmac_ctx_init(hmac_ctx, key, key_len, md5_kt);
    hmac_ctx_update(hmac_ctx, data, data_len);
    hmac_ctx_final(hmac_ctx, result);
    hmac_ctx_cleanup(hmac_ctx);
    hmac_ctx_free(hmac_ctx);
}

static void
gen_timestamp(uint8_t *timestamp)
{
    /* Copies 8 bytes long timestamp into "timestamp" buffer.
     * Timestamp is Little-endian, 64-bit signed value representing the
     * number of tenths of a microsecond since January 1, 1601.
     */

    UINTEGER64 timestamp_ull;

    timestamp_ull = openvpn_time(NULL);
    timestamp_ull = (timestamp_ull + UINT64(11644473600)) * UINT64(10000000);

    /* store little endian value */
    timestamp[0] = timestamp_ull & UINT64(0xFF);
    timestamp[1] = (timestamp_ull  >> 8)  & UINT64(0xFF);
    timestamp[2] = (timestamp_ull  >> 16) & UINT64(0xFF);
    timestamp[3] = (timestamp_ull  >> 24) & UINT64(0xFF);
    timestamp[4] = (timestamp_ull  >> 32) & UINT64(0xFF);
    timestamp[5] = (timestamp_ull  >> 40) & UINT64(0xFF);
    timestamp[6] = (timestamp_ull  >> 48) & UINT64(0xFF);
    timestamp[7] = (timestamp_ull  >> 56) & UINT64(0xFF);
}

static void
gen_nonce(unsigned char *nonce)
{
    /* Generates 8 random bytes to be used as client nonce */
    int i;

    for (i = 0; i<8; i++)
    {
        nonce[i] = (unsigned char)get_random();
    }
}

static void
my_strupr(char *str)
{
    /* converts string to uppercase in place */

    while (*str)
    {
        *str = toupper(*str);
        str++;
    }
}

static int
unicodize(char *dst, const char *src)
{
    /* not really unicode... */
    int i = 0;
    do
    {
        dst[i++] = *src;
        dst[i++] = 0;
    } while (*src++);

    return i;
}

static void
add_security_buffer(int sb_offset, void *data, int length,
                    unsigned char *msg_buf, int *msg_bufpos)
{
    /* Adds security buffer data to a message and sets security buffer's
     * offset and length */
    msg_buf[sb_offset] = (unsigned char)length;
    msg_buf[sb_offset + 2] = msg_buf[sb_offset];
    msg_buf[sb_offset + 4] = (unsigned char)(*msg_bufpos & 0xff);
    msg_buf[sb_offset + 5] = (unsigned char)((*msg_bufpos >> 8) & 0xff);
    memcpy(&msg_buf[*msg_bufpos], data, msg_buf[sb_offset]);
    *msg_bufpos += length;
}

const char *
ntlm_phase_1(const struct http_proxy_info *p, struct gc_arena *gc)
{
    struct buffer out = alloc_buf_gc(96, gc);
    /* try a minimal NTLM handshake
     *
     * http://davenport.sourceforge.net/ntlm.html
     *
     * This message contains only the NTLMSSP signature,
     * the NTLM message type,
     * and the minimal set of flags (Negotiate NTLM and Negotiate OEM).
     *
     */
    buf_printf(&out, "%s", "TlRMTVNTUAABAAAAAgIAAA==");
    return (BSTR(&out));
}

const char *
ntlm_phase_3(const struct http_proxy_info *p, const char *phase_2,
             struct gc_arena *gc)
{
    /* NTLM handshake
     *
     * http://davenport.sourceforge.net/ntlm.html
     *
     */

    char pwbuf[sizeof(p->up.password) * 2]; /* for unicode password */
    uint8_t buf2[128]; /* decoded reply from proxy */
    uint8_t phase3[464];

    uint8_t md4_hash[MD4_DIGEST_LENGTH + 5];
    uint8_t challenge[8], ntlm_response[24];
    int i, ret_val;

    uint8_t ntlmv2_response[144];
    char userdomain_u[256];     /* for uppercase unicode username and domain */
    char userdomain[128];       /* the same as previous but ascii */
    uint8_t ntlmv2_hash[MD5_DIGEST_LENGTH];
    uint8_t ntlmv2_hmacmd5[16];
    uint8_t *ntlmv2_blob = ntlmv2_response + 16;     /* inside ntlmv2_response, length: 128 */
    int ntlmv2_blob_size = 0;
    int phase3_bufpos = 0x40;     /* offset to next security buffer data to be added */
    size_t len;

    char domain[128];
    char username[128];
    char *separator;

    bool ntlmv2_enabled = (p->auth_method == HTTP_AUTH_NTLM2);

    CLEAR(buf2);

    ASSERT(strlen(p->up.username) > 0);
    ASSERT(strlen(p->up.password) > 0);

    /* username parsing */
    separator = strchr(p->up.username, '\\');
    if (separator == NULL)
    {
        strncpy(username, p->up.username, sizeof(username)-1);
        username[sizeof(username)-1] = 0;
        domain[0] = 0;
    }
    else
    {
        strncpy(username, separator+1, sizeof(username)-1);
        username[sizeof(username)-1] = 0;
        len = separator - p->up.username;
        if (len > sizeof(domain) - 1)
        {
            len = sizeof(domain) - 1;
        }
        strncpy(domain, p->up.username,  len);
        domain[len] = 0;
    }


    /* fill 1st 16 bytes with md4 hash, disregard terminating null */
    int unicode_len = unicodize(pwbuf, p->up.password) - 2;
    gen_md4_hash((uint8_t *)pwbuf, unicode_len, md4_hash);

    /* pad to 21 bytes */
    memset(md4_hash + MD4_DIGEST_LENGTH, 0, 5);

    ret_val = openvpn_base64_decode(phase_2, buf2, -1);
    if (ret_val < 0)
    {
        return NULL;
    }

    /* we can be sure that phase_2 is less than 128
     * therefore buf2 needs to be (3/4 * 128) */

    /* extract the challenge from bytes 24-31 */
    for (i = 0; i<8; i++)
    {
        challenge[i] = buf2[i+24];
    }

    if (ntlmv2_enabled)      /* Generate NTLMv2 response */
    {
        int tib_len;

        /* NTLMv2 hash */
        strcpy(userdomain, username);
        my_strupr(userdomain);
        if (strlen(username) + strlen(domain) < sizeof(userdomain))
        {
            strcat(userdomain, domain);
        }
        else
        {
            msg(M_INFO, "Warning: Username or domain too long");
        }
        unicodize(userdomain_u, userdomain);
        gen_hmac_md5((uint8_t *)userdomain_u, 2 * strlen(userdomain), md4_hash,
                     MD5_DIGEST_LENGTH, ntlmv2_hash);

        /* NTLMv2 Blob */
        memset(ntlmv2_blob, 0, 128);                        /* Clear blob buffer */
        ntlmv2_blob[0x00] = 1;                              /* Signature */
        ntlmv2_blob[0x01] = 1;                              /* Signature */
        ntlmv2_blob[0x04] = 0;                              /* Reserved */
        gen_timestamp(&ntlmv2_blob[0x08]);                  /* 64-bit Timestamp */
        gen_nonce(&ntlmv2_blob[0x10]);                      /* 64-bit Client Nonce */
        ntlmv2_blob[0x18] = 0;                              /* Unknown, zero should work */

        /* Add target information block to the blob */

        /* Check for Target Information block */
        /* The NTLM spec instructs to interpret these 4 consecutive bytes as a
         * 32bit long integer. However, no endianness is specified.
         * The code here and that found in other NTLM implementations point
         * towards the assumption that the byte order on the wire has to
         * match the order on the sending and receiving hosts. Probably NTLM has
         * been thought to be always running on x86_64/i386 machine thus
         * implying Little-Endian everywhere.
         *
         * This said, in case of future changes, we should keep in mind that the
         * byte order on the wire for the NTLM header is LE.
         */
        const size_t hoff = 0x14;
        unsigned long flags = buf2[hoff] | (buf2[hoff + 1] << 8)
                              |(buf2[hoff + 2] << 16) | (buf2[hoff + 3] << 24);
        if ((flags & 0x00800000) == 0x00800000)
        {
            tib_len = buf2[0x28];            /* Get Target Information block size */
            if (tib_len > 96)
            {
                tib_len = 96;
            }

            {
                uint8_t *tib_ptr;
                uint8_t tib_pos = buf2[0x2c];
                if (tib_pos + tib_len > sizeof(buf2))
                {
                    return NULL;
                }
                /* Get Target Information block pointer */
                tib_ptr = buf2 + tib_pos;
                /* Copy Target Information block into the blob */
                memcpy(&ntlmv2_blob[0x1c], tib_ptr, tib_len);
            }
        }
        else
        {
            tib_len = 0;
        }

        /* Unknown, zero works */
        ntlmv2_blob[0x1c + tib_len] = 0;

        /* Get blob length */
        ntlmv2_blob_size = 0x20 + tib_len;

        /* Add challenge from message 2 */
        memcpy(&ntlmv2_response[8], challenge, 8);

        /* hmac-md5 */
        gen_hmac_md5(&ntlmv2_response[8], ntlmv2_blob_size + 8, ntlmv2_hash,
                     MD5_DIGEST_LENGTH, ntlmv2_hmacmd5);

        /* Add hmac-md5 result to the blob.
         * Note: This overwrites challenge previously written at
         * ntlmv2_response[8..15] */
        memcpy(ntlmv2_response, ntlmv2_hmacmd5, MD5_DIGEST_LENGTH);
    }
    else /* Generate NTLM response */
    {
        unsigned char key1[DES_KEY_LENGTH], key2[DES_KEY_LENGTH];
        unsigned char key3[DES_KEY_LENGTH];

        create_des_keys(md4_hash, key1);
        cipher_des_encrypt_ecb(key1, challenge, ntlm_response);

        create_des_keys(&md4_hash[DES_KEY_LENGTH - 1], key2);
        cipher_des_encrypt_ecb(key2, challenge, &ntlm_response[DES_KEY_LENGTH]);

        create_des_keys(&md4_hash[2 * (DES_KEY_LENGTH - 1)], key3);
        cipher_des_encrypt_ecb(key3, challenge,
                               &ntlm_response[DES_KEY_LENGTH * 2]);
    }


    memset(phase3, 0, sizeof(phase3));       /* clear reply */

    strcpy((char *)phase3, "NTLMSSP\0");      /* signature */
    phase3[8] = 3;     /* type 3 */

    if (ntlmv2_enabled)      /* NTLMv2 response */
    {
        add_security_buffer(0x14, ntlmv2_response, ntlmv2_blob_size + 16,
                            phase3, &phase3_bufpos);
    }
    else       /* NTLM response */
    {
        add_security_buffer(0x14, ntlm_response, 24, phase3, &phase3_bufpos);
    }

    /* username in ascii */
    add_security_buffer(0x24, username, strlen(username), phase3,
                        &phase3_bufpos);

    /* Set domain. If <domain> is empty, default domain will be used
     * (i.e. proxy's domain) */
    add_security_buffer(0x1c, domain, strlen(domain), phase3, &phase3_bufpos);

    /* other security buffers will be empty */
    phase3[0x10] = phase3_bufpos;     /* lm not used */
    phase3[0x30] = phase3_bufpos;     /* no workstation name supplied */
    phase3[0x38] = phase3_bufpos;     /* no session key */

    /* flags */
    phase3[0x3c] = 0x02; /* negotiate oem */
    phase3[0x3d] = 0x02; /* negotiate ntlm */

    return ((const char *)make_base64_string2((unsigned char *)phase3,
                                              phase3_bufpos, gc));
}

#else  /* if NTLM */
static void
dummy(void)
{
}
#endif /* if NTLM */