FreeTDS API

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sec_negotiate_gnutls.h
1/* FreeTDS - Library of routines accessing Sybase and Microsoft databases
2 * Copyright (C) 2015 Frediano Ziglio
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
18 */
19
20#include <gnutls/gnutls.h>
21#include <gnutls/crypto.h>
22#ifdef HAVE_GNUTLS_ABSTRACT_H
23# include <gnutls/abstract.h>
24#endif
25
26#if !defined(HAVE_NETTLE) || !defined(HAVE_GMP) || !defined(HAVE_GNUTLS_RND)
27# include <gcrypt.h>
28#endif
29
30#ifndef HAVE_NETTLE
31# include <libtasn1.h>
32#endif
33
34#ifdef HAVE_NETTLE
35# include <nettle/asn1.h>
36# include <nettle/rsa.h>
37# include <nettle/bignum.h>
38#endif
39
51#ifndef HAVE_GNUTLS
52#error HAVE_GNUTLS not defined, this file should not be included
53#endif
54
55/* emulate GMP if not present */
56#ifndef HAVE_GMP
57#define HAVE_GMP 1
58
59 typedef struct {
60 gcry_mpi_t num;
61} mpz_t[1];
62
63#define mpz_powm(w,n,e,m) \
64 gcry_mpi_powm((w)->num, (n)->num, (e)->num, (m)->num);
65#define mpz_init(n) do { (n)->num = NULL; } while(0)
66#define mpz_clear(n) gcry_mpi_release((n)->num)
67
68#endif
69
70
71/* emulate Nettle if not present */
72#ifndef HAVE_NETTLE
73#define HAVE_NETTLE 1
74
75 typedef void nettle_random_func(void *ctx, size_t len, uint8_t *out);
76
77 static inline void
78nettle_mpz_set_str_256_u(mpz_t x, unsigned length, const uint8_t *s)
79{
80 gcry_mpi_scan(&x->num, GCRYMPI_FMT_USG, s, length, NULL);
81}
82
83 static inline void
84nettle_mpz_get_str_256(unsigned length, uint8_t *s, const mpz_t x)
85{
86 gcry_mpi_print(GCRYMPI_FMT_USG, s, length, NULL, x->num);
87}
88
89 struct asn1_der_iterator {
90 const unsigned char *data, *data_end;
91 unsigned long length;
92 unsigned long type;
93};
94
95 enum asn1_iterator_result {
96 ASN1_ITERATOR_ERROR,
97 ASN1_ITERATOR_PRIMITIVE,
98 ASN1_ITERATOR_CONSTRUCTED,
99 ASN1_ITERATOR_END,
100};
101
102 enum {
103 ASN1_SEQUENCE = ASN1_TAG_SEQUENCE,
104};
105
106 static enum asn1_iterator_result
107asn1_der_iterator_next(struct asn1_der_iterator *der)
108{
109 unsigned char cls;
110 unsigned long tag;
111 int len;
112 long l;
113
114 if (asn1_get_tag_der(der->data, der->data_end - der->data, &cls, &len, &tag) != ASN1_SUCCESS)
115 return ASN1_ITERATOR_ERROR;
116 der->type = tag;
117 der->data += len;
118 l = asn1_get_length_der(der->data, der->data_end - der->data, &len);
119 if (l < 0)
120 return ASN1_ITERATOR_ERROR;
121 der->data += len;
122 der->length = l;
123 if (cls == ASN1_CLASS_STRUCTURED)
124 return ASN1_ITERATOR_CONSTRUCTED;
125 return ASN1_ITERATOR_PRIMITIVE;
126}
127
128 static enum asn1_iterator_result
129asn1_der_iterator_first(struct asn1_der_iterator *der, int size, const void *der_buf)
130{
131 der->data = (const unsigned char *) der_buf;
132 der->data_end = der->data + size;
133
134 return asn1_der_iterator_next(der);
135}
136
137 struct rsa_public_key {
138 unsigned size;
139 mpz_t n, e;
140};
141
142 static void
143rsa_public_key_init(struct rsa_public_key *key)
144{
145 key->size = 0;
146 mpz_init(key->n);
147 mpz_init(key->e);
148}
149
150 static void
151rsa_public_key_clear(struct rsa_public_key *key)
152{
153 mpz_clear(key->n);
154 mpz_clear(key->e);
155}
156
157 static int
158rsa_public_key_from_der_iterator(struct rsa_public_key *key, unsigned key_bits, struct asn1_der_iterator *der)
159{
160 enum asn1_iterator_result ret;
161
162 ret = asn1_der_iterator_next(der);
163 if (ret != ASN1_ITERATOR_PRIMITIVE || der->type != ASN1_TAG_INTEGER)
164 return 0;
165 gcry_mpi_scan(&key->n->num, GCRYMPI_FMT_USG, der->data, der->length, NULL);
166 key->size = (gcry_mpi_get_nbits(key->n->num)+7)/8;
167 der->data += der->length;
168
169 ret = asn1_der_iterator_next(der);
170 if (ret != ASN1_ITERATOR_PRIMITIVE || der->type != ASN1_TAG_INTEGER)
171 return 0;
172 gcry_mpi_scan(&key->e->num, GCRYMPI_FMT_USG, der->data, der->length, NULL);
173
174 return 1;
175}
176
177 static void
178sha1(uint8_t *hash, const void *data, size_t len)
179{
180 gcry_md_hash_buffer(GCRY_MD_SHA1, hash, data, len);
181}
182#else
183 static void
184sha1(uint8_t *hash, const void *data, size_t len)
185{
186 struct sha1_ctx ctx;
187 sha1_init(&ctx);
188 sha1_update(&ctx, len, (const uint8_t *) data);
189 sha1_digest(&ctx, 20, hash);
190}
191#endif
192
193
194#define dumpl(b,l) tdsdump_dump_buf(TDS_DBG_INFO1, #b, b, l)
195#ifndef dumpl
196#define dumpl(b,l) do {} while(0)
197#endif
198#define dump(b) dumpl(b, sizeof(b))
199
200/* OAEP configuration parameters */
201#define hash_func sha1
202 enum { hash_len = 20 }; /* sha1 length */
203 enum { key_size_max = 1024 }; /* max key in bytes */
204 static const char label[] = "";
205
206 static void
207memxor(uint8_t *dest, const uint8_t *src, size_t len)
208{
209 size_t n;
210 for (n = 0; n < len; ++n)
211 dest[n] = dest[n] ^ src[n];
212}
213
214 static void
215mgf_mask(uint8_t *dest, size_t dest_len, const uint8_t *mask, size_t mask_len)
216{
217 unsigned n = 0;
218 uint8_t hash[hash_len];
219 uint8_t seed[mask_len + 4];
220
221 memcpy(seed, mask, mask_len);
222 /* we always have some data and check is done internally */
223 for (;;) {
224 TDS_PUT_UA4BE(seed+mask_len, n);
225
226 hash_func(hash, seed, sizeof(seed));
227 if (dest_len <= hash_len) {
228 memxor(dest, hash, dest_len);
229 break;
230 }
231
232 memxor(dest, hash, hash_len);
233 dest += hash_len;
234 dest_len -= hash_len;
235 ++n;
236 }
237}
238
239 static int
240oaep_encrypt(size_t key_size, size_t length, const uint8_t *message, mpz_t m)
241{
242 /* EM: 0x00 ROS (HASH 0x00.. 0x01 message) */
243 struct {
244 uint8_t all[1]; /* zero but used to access all data */
245 uint8_t ros[hash_len];
246 uint8_t db[key_size_max - hash_len - 1];
247 } em;
248 const unsigned db_len = key_size - hash_len - 1;
249
250 if (length + hash_len * 2 + 2 > key_size)
251 /* Message too long for this key. */
252 return 0;
253
254 /* create db */
255 memset(&em, 0, sizeof(em));
256 hash_func(em.db, label, strlen(label));
257 em.all[key_size - length - 1] = 0x1;
258 memcpy(em.all+(key_size - length), message, length);
259 dumpl(em.db, db_len);
260
261 /* create ros */
262 tds_random_buffer(em.ros, hash_len);
263 dump(em.ros);
264
265 /* mask db */
266 mgf_mask(em.db, db_len, em.ros, hash_len);
267 dumpl(em.db, db_len);
268
269 /* mask ros */
270 mgf_mask(em.ros, hash_len, em.db, db_len);
271 dump(em.ros);
272
273 nettle_mpz_set_str_256_u(m, key_size, em.all);
274
275 return 1;
276}
277
278 static int
279rsa_encrypt_oaep(const struct rsa_public_key *key,
280 size_t length, const uint8_t *message, mpz_t gibberish)
281{
282 if (!oaep_encrypt(key->size, length, message, gibberish))
283 return 0;
284
285 mpz_powm(gibberish, gibberish, key->e, key->n);
286 return 1;
287}
288
289 static void*
290tds5_rsa_encrypt(const void *key, size_t key_len, const void *nonce, size_t nonce_len, const char *pwd, size_t *em_size)
291{
292 int ret;
293 mpz_t p;
294 gnutls_datum_t pubkey_datum = { (unsigned char *) key, key_len };
295 struct asn1_der_iterator der;
296 struct rsa_public_key pubkey;
297 uint8_t *message;
298 size_t message_len, pwd_len;
299 uint8_t *em = NULL;
300 unsigned char der_buf[2048];
301 size_t size = sizeof(der_buf);
302
303 mpz_init(p);
304 rsa_public_key_init(&pubkey);
305
306 pwd_len = strlen(pwd);
307 message_len = nonce_len + pwd_len;
308 message = tds_new(uint8_t, message_len);
309 if (!message)
310 return NULL;
311 memcpy(message, nonce, nonce_len);
312 memcpy(message + nonce_len, pwd, pwd_len);
313
314 /* use nettle directly */
315 /* parse PEM, get DER */
316 ret = gnutls_pem_base64_decode("RSA PUBLIC KEY", &pubkey_datum, der_buf, &size);
317 if (ret) {
318 tdsdump_log(TDS_DBG_ERROR, "Error %d decoding public key: %s\n", ret, gnutls_strerror(ret));
319 goto error;
320 }
321
322 /* get key with nettle using DER */
323 ret = asn1_der_iterator_first(&der, size, der_buf);
324 if (ret != ASN1_ITERATOR_CONSTRUCTED || der.type != ASN1_SEQUENCE) {
325 tdsdump_log(TDS_DBG_ERROR, "Invalid DER content\n");
326 goto error;
327 }
328
329 ret = rsa_public_key_from_der_iterator(&pubkey, key_size_max * 8, &der);
330 if (!ret) {
331 tdsdump_log(TDS_DBG_ERROR, "Invalid DER content\n");
332 goto error;
333 }
334
335 /* get password encrypted */
336 ret = rsa_encrypt_oaep(&pubkey, message_len, message, p);
337 if (!ret) {
338 tdsdump_log(TDS_DBG_ERROR, "Error encrypting message\n");
339 goto error;
340 }
341
342 em = tds_new(uint8_t, pubkey.size);
343 *em_size = pubkey.size;
344 if (!em)
345 goto error;
346
347 nettle_mpz_get_str_256(pubkey.size, em, p);
348
349 tdsdump_dump_buf(TDS_DBG_INFO1, "em", em, pubkey.size);
350
351error:
352 free(message);
353 rsa_public_key_clear(&pubkey);
354 mpz_clear(p);
355 return em;
356}
357
mpz_t
Definition sec_negotiate_gnutls.h:59
asn1_der_iterator
Definition sec_negotiate_gnutls.h:89
rsa_public_key
Definition sec_negotiate_gnutls.h:137