Line data Source code
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 :
40 : /**
41 : * \ingroup libtds
42 : * \defgroup auth Authentication
43 : * Functions for handling authentication.
44 : */
45 :
46 : /**
47 : * \addtogroup auth
48 : * @{
49 : */
50 :
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
78 : nettle_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
84 : nettle_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
107 : asn1_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
129 : asn1_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
143 : rsa_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
151 : rsa_public_key_clear(struct rsa_public_key *key)
152 : {
153 : mpz_clear(key->n);
154 : mpz_clear(key->e);
155 : }
156 :
157 : static int
158 : rsa_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
178 : sha1(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
184 0 : sha1(uint8_t *hash, const void *data, size_t len)
185 : {
186 : struct sha1_ctx ctx;
187 0 : sha1_init(&ctx);
188 0 : sha1_update(&ctx, len, (const uint8_t *) data);
189 0 : sha1_digest(&ctx, 20, hash);
190 0 : }
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
207 : memxor(uint8_t *dest, const uint8_t *src, size_t len)
208 : {
209 : size_t n;
210 0 : for (n = 0; n < len; ++n)
211 0 : dest[n] = dest[n] ^ src[n];
212 : }
213 :
214 : static void
215 0 : mgf_mask(uint8_t *dest, size_t dest_len, const uint8_t *mask, size_t mask_len)
216 0 : {
217 0 : unsigned n = 0;
218 : uint8_t hash[hash_len];
219 0 : uint8_t seed[mask_len + 4];
220 :
221 0 : memcpy(seed, mask, mask_len);
222 : /* we always have some data and check is done internally */
223 : for (;;) {
224 0 : TDS_PUT_UA4BE(seed+mask_len, n);
225 :
226 0 : hash_func(hash, seed, sizeof(seed));
227 0 : if (dest_len <= hash_len) {
228 0 : memxor(dest, hash, dest_len);
229 : break;
230 : }
231 :
232 0 : memxor(dest, hash, hash_len);
233 0 : dest += hash_len;
234 0 : dest_len -= hash_len;
235 0 : ++n;
236 : }
237 0 : }
238 :
239 : static int
240 0 : oaep_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 0 : const unsigned db_len = key_size - hash_len - 1;
249 :
250 0 : if (length + hash_len * 2 + 2 > key_size)
251 : /* Message too long for this key. */
252 : return 0;
253 :
254 : /* create db */
255 0 : memset(&em, 0, sizeof(em));
256 0 : hash_func(em.db, label, strlen(label));
257 0 : em.all[key_size - length - 1] = 0x1;
258 0 : memcpy(em.all+(key_size - length), message, length);
259 0 : dumpl(em.db, db_len);
260 :
261 : /* create ros */
262 0 : tds_random_buffer(em.ros, hash_len);
263 0 : dump(em.ros);
264 :
265 : /* mask db */
266 0 : mgf_mask(em.db, db_len, em.ros, hash_len);
267 0 : dumpl(em.db, db_len);
268 :
269 : /* mask ros */
270 0 : mgf_mask(em.ros, hash_len, em.db, db_len);
271 0 : dump(em.ros);
272 :
273 0 : nettle_mpz_set_str_256_u(m, key_size, em.all);
274 :
275 0 : return 1;
276 : }
277 :
278 : static int
279 0 : rsa_encrypt_oaep(const struct rsa_public_key *key,
280 : size_t length, const uint8_t *message, mpz_t gibberish)
281 : {
282 0 : if (!oaep_encrypt(key->size, length, message, gibberish))
283 : return 0;
284 :
285 0 : mpz_powm(gibberish, gibberish, key->e, key->n);
286 0 : return 1;
287 : }
288 :
289 : static void*
290 0 : tds5_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 0 : 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 0 : uint8_t *em = NULL;
300 : unsigned char der_buf[2048];
301 0 : size_t size = sizeof(der_buf);
302 :
303 0 : mpz_init(p);
304 0 : rsa_public_key_init(&pubkey);
305 :
306 0 : pwd_len = strlen(pwd);
307 0 : message_len = nonce_len + pwd_len;
308 0 : message = tds_new(uint8_t, message_len);
309 0 : if (!message)
310 : return NULL;
311 0 : memcpy(message, nonce, nonce_len);
312 0 : memcpy(message + nonce_len, pwd, pwd_len);
313 :
314 : /* use nettle directly */
315 : /* parse PEM, get DER */
316 0 : ret = gnutls_pem_base64_decode("RSA PUBLIC KEY", &pubkey_datum, der_buf, &size);
317 0 : if (ret) {
318 0 : 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 0 : ret = asn1_der_iterator_first(&der, size, der_buf);
324 0 : if (ret != ASN1_ITERATOR_CONSTRUCTED || der.type != ASN1_SEQUENCE) {
325 0 : tdsdump_log(TDS_DBG_ERROR, "Invalid DER content\n");
326 : goto error;
327 : }
328 :
329 0 : ret = rsa_public_key_from_der_iterator(&pubkey, key_size_max * 8, &der);
330 0 : if (!ret) {
331 0 : tdsdump_log(TDS_DBG_ERROR, "Invalid DER content\n");
332 : goto error;
333 : }
334 :
335 : /* get password encrypted */
336 0 : ret = rsa_encrypt_oaep(&pubkey, message_len, message, p);
337 0 : if (!ret) {
338 0 : tdsdump_log(TDS_DBG_ERROR, "Error encrypting message\n");
339 : goto error;
340 : }
341 :
342 0 : em = tds_new(uint8_t, pubkey.size);
343 0 : *em_size = pubkey.size;
344 0 : if (!em)
345 : goto error;
346 :
347 0 : nettle_mpz_get_str_256(pubkey.size, em, p);
348 :
349 0 : tdsdump_dump_buf(TDS_DBG_INFO1, "em", em, pubkey.size);
350 :
351 0 : error:
352 0 : free(message);
353 0 : rsa_public_key_clear(&pubkey);
354 0 : mpz_clear(p);
355 0 : return em;
356 : }
357 :
358 : /** @} */
359 :
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