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820988a0 BL |
1 | /* ssl/s3_cbc.c */ |
2 | /* ==================================================================== | |
3 | * Copyright (c) 2012 The OpenSSL Project. All rights reserved. | |
4 | * | |
5 | * Redistribution and use in source and binary forms, with or without | |
6 | * modification, are permitted provided that the following conditions | |
7 | * are met: | |
8 | * | |
9 | * 1. Redistributions of source code must retain the above copyright | |
10 | * notice, this list of conditions and the following disclaimer. | |
11 | * | |
12 | * 2. Redistributions in binary form must reproduce the above copyright | |
13 | * notice, this list of conditions and the following disclaimer in | |
14 | * the documentation and/or other materials provided with the | |
15 | * distribution. | |
16 | * | |
17 | * 3. All advertising materials mentioning features or use of this | |
18 | * software must display the following acknowledgment: | |
19 | * "This product includes software developed by the OpenSSL Project | |
20 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" | |
21 | * | |
22 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to | |
23 | * endorse or promote products derived from this software without | |
24 | * prior written permission. For written permission, please contact | |
25 | * openssl-core@openssl.org. | |
26 | * | |
27 | * 5. Products derived from this software may not be called "OpenSSL" | |
28 | * nor may "OpenSSL" appear in their names without prior written | |
29 | * permission of the OpenSSL Project. | |
30 | * | |
31 | * 6. Redistributions of any form whatsoever must retain the following | |
32 | * acknowledgment: | |
33 | * "This product includes software developed by the OpenSSL Project | |
34 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" | |
35 | * | |
36 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY | |
37 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
38 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
39 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR | |
40 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
41 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
42 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
43 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
44 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
45 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
46 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
47 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
48 | * ==================================================================== | |
49 | * | |
50 | * This product includes cryptographic software written by Eric Young | |
51 | * (eay@cryptsoft.com). This product includes software written by Tim | |
52 | * Hudson (tjh@cryptsoft.com). | |
53 | * | |
54 | */ | |
55 | ||
9a9b0c04 | 56 | #include "../crypto/constant_time_locl.h" |
820988a0 BL |
57 | #include "ssl_locl.h" |
58 | ||
59 | #include <openssl/md5.h> | |
60 | #include <openssl/sha.h> | |
61 | ||
ae5c8664 MC |
62 | /* |
63 | * MAX_HASH_BIT_COUNT_BYTES is the maximum number of bytes in the hash's | |
64 | * length field. (SHA-384/512 have 128-bit length.) | |
65 | */ | |
820988a0 BL |
66 | #define MAX_HASH_BIT_COUNT_BYTES 16 |
67 | ||
ae5c8664 MC |
68 | /* |
69 | * MAX_HASH_BLOCK_SIZE is the maximum hash block size that we'll support. | |
820988a0 | 70 | * Currently SHA-384/512 has a 128-byte block size and that's the largest |
ae5c8664 MC |
71 | * supported by TLS.) |
72 | */ | |
820988a0 BL |
73 | #define MAX_HASH_BLOCK_SIZE 128 |
74 | ||
6977c7e2 TH |
75 | /*- |
76 | * ssl3_cbc_remove_padding removes padding from the decrypted, SSLv3, CBC | |
820988a0 BL |
77 | * record in |rec| by updating |rec->length| in constant time. |
78 | * | |
79 | * block_size: the block size of the cipher used to encrypt the record. | |
80 | * returns: | |
81 | * 0: (in non-constant time) if the record is publicly invalid. | |
82 | * 1: if the padding was valid | |
ae5c8664 | 83 | * -1: otherwise. |
6977c7e2 | 84 | */ |
ae5c8664 MC |
85 | int ssl3_cbc_remove_padding(const SSL *s, |
86 | SSL3_RECORD *rec, | |
87 | unsigned block_size, unsigned mac_size) | |
88 | { | |
89 | unsigned padding_length, good; | |
90 | const unsigned overhead = 1 /* padding length byte */ + mac_size; | |
91 | ||
92 | /* | |
93 | * These lengths are all public so we can test them in non-constant time. | |
94 | */ | |
95 | if (overhead > rec->length) | |
96 | return 0; | |
97 | ||
98 | padding_length = rec->data[rec->length - 1]; | |
99 | good = constant_time_ge(rec->length, padding_length + overhead); | |
100 | /* SSLv3 requires that the padding is minimal. */ | |
101 | good &= constant_time_ge(block_size, padding_length + 1); | |
102 | padding_length = good & (padding_length + 1); | |
103 | rec->length -= padding_length; | |
104 | rec->type |= padding_length << 8; /* kludge: pass padding length */ | |
105 | return constant_time_select_int(good, 1, -1); | |
106 | } | |
107 | ||
108 | /*- | |
6977c7e2 | 109 | * tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC |
820988a0 BL |
110 | * record in |rec| in constant time and returns 1 if the padding is valid and |
111 | * -1 otherwise. It also removes any explicit IV from the start of the record | |
112 | * without leaking any timing about whether there was enough space after the | |
113 | * padding was removed. | |
114 | * | |
115 | * block_size: the block size of the cipher used to encrypt the record. | |
116 | * returns: | |
117 | * 0: (in non-constant time) if the record is publicly invalid. | |
118 | * 1: if the padding was valid | |
ae5c8664 | 119 | * -1: otherwise. |
6977c7e2 | 120 | */ |
ae5c8664 MC |
121 | int tls1_cbc_remove_padding(const SSL *s, |
122 | SSL3_RECORD *rec, | |
123 | unsigned block_size, unsigned mac_size) | |
124 | { | |
125 | unsigned padding_length, good, to_check, i; | |
126 | const unsigned overhead = 1 /* padding length byte */ + mac_size; | |
127 | /* Check if version requires explicit IV */ | |
128 | if (SSL_USE_EXPLICIT_IV(s)) { | |
129 | /* | |
130 | * These lengths are all public so we can test them in non-constant | |
131 | * time. | |
132 | */ | |
133 | if (overhead + block_size > rec->length) | |
134 | return 0; | |
135 | /* We can now safely skip explicit IV */ | |
136 | rec->data += block_size; | |
137 | rec->input += block_size; | |
138 | rec->length -= block_size; | |
139 | } else if (overhead > rec->length) | |
140 | return 0; | |
141 | ||
142 | padding_length = rec->data[rec->length - 1]; | |
143 | ||
144 | /* | |
145 | * NB: if compression is in operation the first packet may not be of even | |
146 | * length so the padding bug check cannot be performed. This bug | |
147 | * workaround has been around since SSLeay so hopefully it is either | |
148 | * fixed now or no buggy implementation supports compression [steve] | |
149 | */ | |
150 | if ((s->options & SSL_OP_TLS_BLOCK_PADDING_BUG) && !s->expand) { | |
151 | /* First packet is even in size, so check */ | |
05627d57 | 152 | if ((CRYPTO_memcmp(s->s3->read_sequence, "\0\0\0\0\0\0\0\0", 8) == 0) && |
ae5c8664 MC |
153 | !(padding_length & 1)) { |
154 | s->s3->flags |= TLS1_FLAGS_TLS_PADDING_BUG; | |
155 | } | |
156 | if ((s->s3->flags & TLS1_FLAGS_TLS_PADDING_BUG) && padding_length > 0) { | |
157 | padding_length--; | |
158 | } | |
159 | } | |
160 | ||
161 | if (EVP_CIPHER_flags(s->enc_read_ctx->cipher) & EVP_CIPH_FLAG_AEAD_CIPHER) { | |
162 | /* padding is already verified */ | |
163 | rec->length -= padding_length + 1; | |
164 | return 1; | |
165 | } | |
166 | ||
167 | good = constant_time_ge(rec->length, overhead + padding_length); | |
168 | /* | |
169 | * The padding consists of a length byte at the end of the record and | |
170 | * then that many bytes of padding, all with the same value as the length | |
171 | * byte. Thus, with the length byte included, there are i+1 bytes of | |
172 | * padding. We can't check just |padding_length+1| bytes because that | |
173 | * leaks decrypted information. Therefore we always have to check the | |
174 | * maximum amount of padding possible. (Again, the length of the record | |
175 | * is public information so we can use it.) | |
176 | */ | |
177 | to_check = 255; /* maximum amount of padding. */ | |
178 | if (to_check > rec->length - 1) | |
179 | to_check = rec->length - 1; | |
180 | ||
181 | for (i = 0; i < to_check; i++) { | |
182 | unsigned char mask = constant_time_ge_8(padding_length, i); | |
183 | unsigned char b = rec->data[rec->length - 1 - i]; | |
184 | /* | |
185 | * The final |padding_length+1| bytes should all have the value | |
186 | * |padding_length|. Therefore the XOR should be zero. | |
187 | */ | |
188 | good &= ~(mask & (padding_length ^ b)); | |
189 | } | |
190 | ||
191 | /* | |
192 | * If any of the final |padding_length+1| bytes had the wrong value, one | |
193 | * or more of the lower eight bits of |good| will be cleared. | |
194 | */ | |
195 | good = constant_time_eq(0xff, good & 0xff); | |
196 | padding_length = good & (padding_length + 1); | |
197 | rec->length -= padding_length; | |
198 | rec->type |= padding_length << 8; /* kludge: pass padding length */ | |
199 | ||
200 | return constant_time_select_int(good, 1, -1); | |
201 | } | |
820988a0 | 202 | |
6977c7e2 TH |
203 | /*- |
204 | * ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in | |
820988a0 BL |
205 | * constant time (independent of the concrete value of rec->length, which may |
206 | * vary within a 256-byte window). | |
207 | * | |
208 | * ssl3_cbc_remove_padding or tls1_cbc_remove_padding must be called prior to | |
209 | * this function. | |
210 | * | |
211 | * On entry: | |
212 | * rec->orig_len >= md_size | |
213 | * md_size <= EVP_MAX_MD_SIZE | |
214 | * | |
215 | * If CBC_MAC_ROTATE_IN_PLACE is defined then the rotation is performed with | |
216 | * variable accesses in a 64-byte-aligned buffer. Assuming that this fits into | |
919eab8a AP |
217 | * a single or pair of cache-lines, then the variable memory accesses don't |
218 | * actually affect the timing. CPUs with smaller cache-lines [if any] are | |
219 | * not multi-core and are not considered vulnerable to cache-timing attacks. | |
820988a0 | 220 | */ |
919eab8a AP |
221 | #define CBC_MAC_ROTATE_IN_PLACE |
222 | ||
ae5c8664 MC |
223 | void ssl3_cbc_copy_mac(unsigned char *out, |
224 | const SSL3_RECORD *rec, | |
225 | unsigned md_size, unsigned orig_len) | |
226 | { | |
820988a0 | 227 | #if defined(CBC_MAC_ROTATE_IN_PLACE) |
ae5c8664 MC |
228 | unsigned char rotated_mac_buf[64 + EVP_MAX_MD_SIZE]; |
229 | unsigned char *rotated_mac; | |
820988a0 | 230 | #else |
ae5c8664 | 231 | unsigned char rotated_mac[EVP_MAX_MD_SIZE]; |
820988a0 BL |
232 | #endif |
233 | ||
ae5c8664 MC |
234 | /* |
235 | * mac_end is the index of |rec->data| just after the end of the MAC. | |
236 | */ | |
237 | unsigned mac_end = rec->length; | |
238 | unsigned mac_start = mac_end - md_size; | |
239 | /* | |
240 | * scan_start contains the number of bytes that we can ignore because the | |
241 | * MAC's position can only vary by 255 bytes. | |
242 | */ | |
243 | unsigned scan_start = 0; | |
244 | unsigned i, j; | |
245 | unsigned div_spoiler; | |
246 | unsigned rotate_offset; | |
247 | ||
248 | OPENSSL_assert(orig_len >= md_size); | |
249 | OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); | |
820988a0 BL |
250 | |
251 | #if defined(CBC_MAC_ROTATE_IN_PLACE) | |
ae5c8664 | 252 | rotated_mac = rotated_mac_buf + ((0 - (size_t)rotated_mac_buf) & 63); |
820988a0 BL |
253 | #endif |
254 | ||
ae5c8664 MC |
255 | /* This information is public so it's safe to branch based on it. */ |
256 | if (orig_len > md_size + 255 + 1) | |
257 | scan_start = orig_len - (md_size + 255 + 1); | |
258 | /* | |
259 | * div_spoiler contains a multiple of md_size that is used to cause the | |
260 | * modulo operation to be constant time. Without this, the time varies | |
261 | * based on the amount of padding when running on Intel chips at least. | |
262 | * The aim of right-shifting md_size is so that the compiler doesn't | |
263 | * figure out that it can remove div_spoiler as that would require it to | |
264 | * prove that md_size is always even, which I hope is beyond it. | |
265 | */ | |
266 | div_spoiler = md_size >> 1; | |
267 | div_spoiler <<= (sizeof(div_spoiler) - 1) * 8; | |
268 | rotate_offset = (div_spoiler + mac_start - scan_start) % md_size; | |
269 | ||
270 | memset(rotated_mac, 0, md_size); | |
271 | for (i = scan_start, j = 0; i < orig_len; i++) { | |
272 | unsigned char mac_started = constant_time_ge_8(i, mac_start); | |
273 | unsigned char mac_ended = constant_time_ge_8(i, mac_end); | |
274 | unsigned char b = rec->data[i]; | |
275 | rotated_mac[j++] |= b & mac_started & ~mac_ended; | |
276 | j &= constant_time_lt(j, md_size); | |
277 | } | |
278 | ||
279 | /* Now rotate the MAC */ | |
820988a0 | 280 | #if defined(CBC_MAC_ROTATE_IN_PLACE) |
ae5c8664 MC |
281 | j = 0; |
282 | for (i = 0; i < md_size; i++) { | |
283 | /* in case cache-line is 32 bytes, touch second line */ | |
284 | ((volatile unsigned char *)rotated_mac)[rotate_offset ^ 32]; | |
285 | out[j++] = rotated_mac[rotate_offset++]; | |
286 | rotate_offset &= constant_time_lt(rotate_offset, md_size); | |
287 | } | |
820988a0 | 288 | #else |
ae5c8664 MC |
289 | memset(out, 0, md_size); |
290 | rotate_offset = md_size - rotate_offset; | |
291 | rotate_offset &= constant_time_lt(rotate_offset, md_size); | |
292 | for (i = 0; i < md_size; i++) { | |
293 | for (j = 0; j < md_size; j++) | |
294 | out[j] |= rotated_mac[i] & constant_time_eq_8(j, rotate_offset); | |
295 | rotate_offset++; | |
296 | rotate_offset &= constant_time_lt(rotate_offset, md_size); | |
297 | } | |
820988a0 | 298 | #endif |
ae5c8664 | 299 | } |
820988a0 | 300 | |
ae5c8664 MC |
301 | /* |
302 | * u32toLE serialises an unsigned, 32-bit number (n) as four bytes at (p) in | |
303 | * little-endian order. The value of p is advanced by four. | |
304 | */ | |
0462eedf | 305 | #define u32toLE(n, p) \ |
ae5c8664 MC |
306 | (*((p)++)=(unsigned char)(n), \ |
307 | *((p)++)=(unsigned char)(n>>8), \ | |
308 | *((p)++)=(unsigned char)(n>>16), \ | |
309 | *((p)++)=(unsigned char)(n>>24)) | |
310 | ||
311 | /* | |
312 | * These functions serialize the state of a hash and thus perform the | |
313 | * standard "final" operation without adding the padding and length that such | |
314 | * a function typically does. | |
315 | */ | |
316 | static void tls1_md5_final_raw(void *ctx, unsigned char *md_out) | |
317 | { | |
318 | MD5_CTX *md5 = ctx; | |
319 | u32toLE(md5->A, md_out); | |
320 | u32toLE(md5->B, md_out); | |
321 | u32toLE(md5->C, md_out); | |
322 | u32toLE(md5->D, md_out); | |
323 | } | |
324 | ||
325 | static void tls1_sha1_final_raw(void *ctx, unsigned char *md_out) | |
326 | { | |
327 | SHA_CTX *sha1 = ctx; | |
328 | l2n(sha1->h0, md_out); | |
329 | l2n(sha1->h1, md_out); | |
330 | l2n(sha1->h2, md_out); | |
331 | l2n(sha1->h3, md_out); | |
332 | l2n(sha1->h4, md_out); | |
333 | } | |
334 | ||
7d9e781a | 335 | #define LARGEST_DIGEST_CTX SHA_CTX |
820988a0 | 336 | |
7d9e781a | 337 | #ifndef OPENSSL_NO_SHA256 |
ae5c8664 MC |
338 | static void tls1_sha256_final_raw(void *ctx, unsigned char *md_out) |
339 | { | |
340 | SHA256_CTX *sha256 = ctx; | |
341 | unsigned i; | |
342 | ||
343 | for (i = 0; i < 8; i++) { | |
344 | l2n(sha256->h[i], md_out); | |
345 | } | |
346 | } | |
347 | ||
348 | # undef LARGEST_DIGEST_CTX | |
349 | # define LARGEST_DIGEST_CTX SHA256_CTX | |
7d9e781a | 350 | #endif |
820988a0 | 351 | |
7d9e781a | 352 | #ifndef OPENSSL_NO_SHA512 |
ae5c8664 MC |
353 | static void tls1_sha512_final_raw(void *ctx, unsigned char *md_out) |
354 | { | |
355 | SHA512_CTX *sha512 = ctx; | |
356 | unsigned i; | |
357 | ||
358 | for (i = 0; i < 8; i++) { | |
359 | l2n8(sha512->h[i], md_out); | |
360 | } | |
361 | } | |
362 | ||
363 | # undef LARGEST_DIGEST_CTX | |
364 | # define LARGEST_DIGEST_CTX SHA512_CTX | |
7d9e781a | 365 | #endif |
820988a0 | 366 | |
ae5c8664 MC |
367 | /* |
368 | * ssl3_cbc_record_digest_supported returns 1 iff |ctx| uses a hash function | |
369 | * which ssl3_cbc_digest_record supports. | |
370 | */ | |
820988a0 | 371 | char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) |
ae5c8664 | 372 | { |
d91d9acc | 373 | #ifdef OPENSSL_FIPS |
ae5c8664 MC |
374 | if (FIPS_mode()) |
375 | return 0; | |
d91d9acc | 376 | #endif |
ae5c8664 MC |
377 | switch (EVP_MD_CTX_type(ctx)) { |
378 | case NID_md5: | |
379 | case NID_sha1: | |
7d9e781a | 380 | #ifndef OPENSSL_NO_SHA256 |
ae5c8664 MC |
381 | case NID_sha224: |
382 | case NID_sha256: | |
7d9e781a AP |
383 | #endif |
384 | #ifndef OPENSSL_NO_SHA512 | |
ae5c8664 MC |
385 | case NID_sha384: |
386 | case NID_sha512: | |
7d9e781a | 387 | #endif |
ae5c8664 MC |
388 | return 1; |
389 | default: | |
390 | return 0; | |
391 | } | |
392 | } | |
820988a0 | 393 | |
6977c7e2 TH |
394 | /*- |
395 | * ssl3_cbc_digest_record computes the MAC of a decrypted, padded SSLv3/TLS | |
820988a0 BL |
396 | * record. |
397 | * | |
398 | * ctx: the EVP_MD_CTX from which we take the hash function. | |
399 | * ssl3_cbc_record_digest_supported must return true for this EVP_MD_CTX. | |
400 | * md_out: the digest output. At most EVP_MAX_MD_SIZE bytes will be written. | |
401 | * md_out_size: if non-NULL, the number of output bytes is written here. | |
402 | * header: the 13-byte, TLS record header. | |
403 | * data: the record data itself, less any preceeding explicit IV. | |
404 | * data_plus_mac_size: the secret, reported length of the data and MAC | |
405 | * once the padding has been removed. | |
406 | * data_plus_mac_plus_padding_size: the public length of the whole | |
407 | * record, including padding. | |
408 | * is_sslv3: non-zero if we are to use SSLv3. Otherwise, TLS. | |
409 | * | |
410 | * On entry: by virtue of having been through one of the remove_padding | |
411 | * functions, above, we know that data_plus_mac_size is large enough to contain | |
412 | * a padding byte and MAC. (If the padding was invalid, it might contain the | |
ae5c8664 | 413 | * padding too. ) |
56d91346 | 414 | * Returns 1 on success or 0 on error |
6977c7e2 | 415 | */ |
56d91346 | 416 | int ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, |
ae5c8664 MC |
417 | unsigned char *md_out, |
418 | size_t *md_out_size, | |
419 | const unsigned char header[13], | |
420 | const unsigned char *data, | |
421 | size_t data_plus_mac_size, | |
422 | size_t data_plus_mac_plus_padding_size, | |
423 | const unsigned char *mac_secret, | |
424 | unsigned mac_secret_length, char is_sslv3) | |
425 | { | |
426 | union { | |
427 | double align; | |
428 | unsigned char c[sizeof(LARGEST_DIGEST_CTX)]; | |
429 | } md_state; | |
430 | void (*md_final_raw) (void *ctx, unsigned char *md_out); | |
431 | void (*md_transform) (void *ctx, const unsigned char *block); | |
432 | unsigned md_size, md_block_size = 64; | |
433 | unsigned sslv3_pad_length = 40, header_length, variance_blocks, | |
434 | len, max_mac_bytes, num_blocks, | |
435 | num_starting_blocks, k, mac_end_offset, c, index_a, index_b; | |
436 | unsigned int bits; /* at most 18 bits */ | |
437 | unsigned char length_bytes[MAX_HASH_BIT_COUNT_BYTES]; | |
438 | /* hmac_pad is the masked HMAC key. */ | |
439 | unsigned char hmac_pad[MAX_HASH_BLOCK_SIZE]; | |
440 | unsigned char first_block[MAX_HASH_BLOCK_SIZE]; | |
441 | unsigned char mac_out[EVP_MAX_MD_SIZE]; | |
442 | unsigned i, j, md_out_size_u; | |
443 | EVP_MD_CTX md_ctx; | |
444 | /* | |
445 | * mdLengthSize is the number of bytes in the length field that | |
446 | * terminates * the hash. | |
447 | */ | |
448 | unsigned md_length_size = 8; | |
449 | char length_is_big_endian = 1; | |
450 | ||
451 | /* | |
452 | * This is a, hopefully redundant, check that allows us to forget about | |
453 | * many possible overflows later in this function. | |
454 | */ | |
455 | OPENSSL_assert(data_plus_mac_plus_padding_size < 1024 * 1024); | |
456 | ||
457 | switch (EVP_MD_CTX_type(ctx)) { | |
458 | case NID_md5: | |
56d91346 MC |
459 | if (MD5_Init((MD5_CTX *)md_state.c) <= 0) |
460 | return 0; | |
ae5c8664 MC |
461 | md_final_raw = tls1_md5_final_raw; |
462 | md_transform = | |
463 | (void (*)(void *ctx, const unsigned char *block))MD5_Transform; | |
464 | md_size = 16; | |
465 | sslv3_pad_length = 48; | |
466 | length_is_big_endian = 0; | |
467 | break; | |
468 | case NID_sha1: | |
56d91346 MC |
469 | if (SHA1_Init((SHA_CTX *)md_state.c) <= 0) |
470 | return 0; | |
ae5c8664 MC |
471 | md_final_raw = tls1_sha1_final_raw; |
472 | md_transform = | |
473 | (void (*)(void *ctx, const unsigned char *block))SHA1_Transform; | |
474 | md_size = 20; | |
475 | break; | |
7d9e781a | 476 | #ifndef OPENSSL_NO_SHA256 |
ae5c8664 | 477 | case NID_sha224: |
56d91346 MC |
478 | if (SHA224_Init((SHA256_CTX *)md_state.c) <= 0) |
479 | return 0; | |
ae5c8664 MC |
480 | md_final_raw = tls1_sha256_final_raw; |
481 | md_transform = | |
482 | (void (*)(void *ctx, const unsigned char *block))SHA256_Transform; | |
483 | md_size = 224 / 8; | |
484 | break; | |
485 | case NID_sha256: | |
56d91346 MC |
486 | if (SHA256_Init((SHA256_CTX *)md_state.c) <= 0) |
487 | return 0; | |
ae5c8664 MC |
488 | md_final_raw = tls1_sha256_final_raw; |
489 | md_transform = | |
490 | (void (*)(void *ctx, const unsigned char *block))SHA256_Transform; | |
491 | md_size = 32; | |
492 | break; | |
7d9e781a AP |
493 | #endif |
494 | #ifndef OPENSSL_NO_SHA512 | |
ae5c8664 | 495 | case NID_sha384: |
56d91346 MC |
496 | if (SHA384_Init((SHA512_CTX *)md_state.c) <= 0) |
497 | return 0; | |
ae5c8664 MC |
498 | md_final_raw = tls1_sha512_final_raw; |
499 | md_transform = | |
500 | (void (*)(void *ctx, const unsigned char *block))SHA512_Transform; | |
501 | md_size = 384 / 8; | |
502 | md_block_size = 128; | |
503 | md_length_size = 16; | |
504 | break; | |
505 | case NID_sha512: | |
56d91346 MC |
506 | if (SHA512_Init((SHA512_CTX *)md_state.c) <= 0) |
507 | return 0; | |
ae5c8664 MC |
508 | md_final_raw = tls1_sha512_final_raw; |
509 | md_transform = | |
510 | (void (*)(void *ctx, const unsigned char *block))SHA512_Transform; | |
511 | md_size = 64; | |
512 | md_block_size = 128; | |
513 | md_length_size = 16; | |
514 | break; | |
7d9e781a | 515 | #endif |
ae5c8664 MC |
516 | default: |
517 | /* | |
518 | * ssl3_cbc_record_digest_supported should have been called first to | |
519 | * check that the hash function is supported. | |
520 | */ | |
521 | OPENSSL_assert(0); | |
522 | if (md_out_size) | |
03bf7127 | 523 | *md_out_size = 0; |
56d91346 | 524 | return 0; |
ae5c8664 MC |
525 | } |
526 | ||
527 | OPENSSL_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES); | |
528 | OPENSSL_assert(md_block_size <= MAX_HASH_BLOCK_SIZE); | |
529 | OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); | |
530 | ||
531 | header_length = 13; | |
532 | if (is_sslv3) { | |
533 | header_length = mac_secret_length + sslv3_pad_length + 8 /* sequence | |
534 | * number */ + | |
535 | 1 /* record type */ + | |
536 | 2 /* record length */ ; | |
537 | } | |
538 | ||
539 | /* | |
540 | * variance_blocks is the number of blocks of the hash that we have to | |
541 | * calculate in constant time because they could be altered by the | |
542 | * padding value. In SSLv3, the padding must be minimal so the end of | |
543 | * the plaintext varies by, at most, 15+20 = 35 bytes. (We conservatively | |
544 | * assume that the MAC size varies from 0..20 bytes.) In case the 9 bytes | |
545 | * of hash termination (0x80 + 64-bit length) don't fit in the final | |
546 | * block, we say that the final two blocks can vary based on the padding. | |
547 | * TLSv1 has MACs up to 48 bytes long (SHA-384) and the padding is not | |
548 | * required to be minimal. Therefore we say that the final six blocks can | |
549 | * vary based on the padding. Later in the function, if the message is | |
550 | * short and there obviously cannot be this many blocks then | |
551 | * variance_blocks can be reduced. | |
552 | */ | |
553 | variance_blocks = is_sslv3 ? 2 : 6; | |
554 | /* | |
555 | * From now on we're dealing with the MAC, which conceptually has 13 | |
556 | * bytes of `header' before the start of the data (TLS) or 71/75 bytes | |
557 | * (SSLv3) | |
558 | */ | |
559 | len = data_plus_mac_plus_padding_size + header_length; | |
560 | /* | |
561 | * max_mac_bytes contains the maximum bytes of bytes in the MAC, | |
562 | * including * |header|, assuming that there's no padding. | |
563 | */ | |
564 | max_mac_bytes = len - md_size - 1; | |
565 | /* num_blocks is the maximum number of hash blocks. */ | |
566 | num_blocks = | |
567 | (max_mac_bytes + 1 + md_length_size + md_block_size - | |
568 | 1) / md_block_size; | |
569 | /* | |
570 | * In order to calculate the MAC in constant time we have to handle the | |
571 | * final blocks specially because the padding value could cause the end | |
572 | * to appear somewhere in the final |variance_blocks| blocks and we can't | |
573 | * leak where. However, |num_starting_blocks| worth of data can be hashed | |
574 | * right away because no padding value can affect whether they are | |
575 | * plaintext. | |
576 | */ | |
577 | num_starting_blocks = 0; | |
578 | /* | |
579 | * k is the starting byte offset into the conceptual header||data where | |
580 | * we start processing. | |
581 | */ | |
582 | k = 0; | |
583 | /* | |
584 | * mac_end_offset is the index just past the end of the data to be MACed. | |
585 | */ | |
586 | mac_end_offset = data_plus_mac_size + header_length - md_size; | |
587 | /* | |
588 | * c is the index of the 0x80 byte in the final hash block that contains | |
589 | * application data. | |
590 | */ | |
591 | c = mac_end_offset % md_block_size; | |
592 | /* | |
593 | * index_a is the hash block number that contains the 0x80 terminating | |
594 | * value. | |
595 | */ | |
596 | index_a = mac_end_offset / md_block_size; | |
597 | /* | |
598 | * index_b is the hash block number that contains the 64-bit hash length, | |
599 | * in bits. | |
600 | */ | |
601 | index_b = (mac_end_offset + md_length_size) / md_block_size; | |
602 | /* | |
603 | * bits is the hash-length in bits. It includes the additional hash block | |
604 | * for the masked HMAC key, or whole of |header| in the case of SSLv3. | |
605 | */ | |
606 | ||
607 | /* | |
608 | * For SSLv3, if we're going to have any starting blocks then we need at | |
609 | * least two because the header is larger than a single block. | |
610 | */ | |
611 | if (num_blocks > variance_blocks + (is_sslv3 ? 1 : 0)) { | |
612 | num_starting_blocks = num_blocks - variance_blocks; | |
613 | k = md_block_size * num_starting_blocks; | |
614 | } | |
615 | ||
616 | bits = 8 * mac_end_offset; | |
617 | if (!is_sslv3) { | |
618 | /* | |
619 | * Compute the initial HMAC block. For SSLv3, the padding and secret | |
620 | * bytes are included in |header| because they take more than a | |
621 | * single block. | |
622 | */ | |
623 | bits += 8 * md_block_size; | |
624 | memset(hmac_pad, 0, md_block_size); | |
625 | OPENSSL_assert(mac_secret_length <= sizeof(hmac_pad)); | |
626 | memcpy(hmac_pad, mac_secret, mac_secret_length); | |
627 | for (i = 0; i < md_block_size; i++) | |
628 | hmac_pad[i] ^= 0x36; | |
629 | ||
630 | md_transform(md_state.c, hmac_pad); | |
631 | } | |
632 | ||
633 | if (length_is_big_endian) { | |
634 | memset(length_bytes, 0, md_length_size - 4); | |
635 | length_bytes[md_length_size - 4] = (unsigned char)(bits >> 24); | |
636 | length_bytes[md_length_size - 3] = (unsigned char)(bits >> 16); | |
637 | length_bytes[md_length_size - 2] = (unsigned char)(bits >> 8); | |
638 | length_bytes[md_length_size - 1] = (unsigned char)bits; | |
639 | } else { | |
640 | memset(length_bytes, 0, md_length_size); | |
641 | length_bytes[md_length_size - 5] = (unsigned char)(bits >> 24); | |
642 | length_bytes[md_length_size - 6] = (unsigned char)(bits >> 16); | |
643 | length_bytes[md_length_size - 7] = (unsigned char)(bits >> 8); | |
644 | length_bytes[md_length_size - 8] = (unsigned char)bits; | |
645 | } | |
646 | ||
647 | if (k > 0) { | |
648 | if (is_sslv3) { | |
99ceb2d4 MC |
649 | unsigned overhang; |
650 | ||
ae5c8664 MC |
651 | /* |
652 | * The SSLv3 header is larger than a single block. overhang is | |
653 | * the number of bytes beyond a single block that the header | |
99ceb2d4 MC |
654 | * consumes: either 7 bytes (SHA1) or 11 bytes (MD5). There are no |
655 | * ciphersuites in SSLv3 that are not SHA1 or MD5 based and | |
656 | * therefore we can be confident that the header_length will be | |
657 | * greater than |md_block_size|. However we add a sanity check just | |
658 | * in case | |
ae5c8664 | 659 | */ |
99ceb2d4 MC |
660 | if (header_length <= md_block_size) { |
661 | /* Should never happen */ | |
56d91346 | 662 | return 0; |
99ceb2d4 MC |
663 | } |
664 | overhang = header_length - md_block_size; | |
ae5c8664 MC |
665 | md_transform(md_state.c, header); |
666 | memcpy(first_block, header + md_block_size, overhang); | |
667 | memcpy(first_block + overhang, data, md_block_size - overhang); | |
668 | md_transform(md_state.c, first_block); | |
669 | for (i = 1; i < k / md_block_size - 1; i++) | |
670 | md_transform(md_state.c, data + md_block_size * i - overhang); | |
671 | } else { | |
672 | /* k is a multiple of md_block_size. */ | |
673 | memcpy(first_block, header, 13); | |
674 | memcpy(first_block + 13, data, md_block_size - 13); | |
675 | md_transform(md_state.c, first_block); | |
676 | for (i = 1; i < k / md_block_size; i++) | |
677 | md_transform(md_state.c, data + md_block_size * i - 13); | |
678 | } | |
679 | } | |
680 | ||
681 | memset(mac_out, 0, sizeof(mac_out)); | |
682 | ||
683 | /* | |
684 | * We now process the final hash blocks. For each block, we construct it | |
685 | * in constant time. If the |i==index_a| then we'll include the 0x80 | |
686 | * bytes and zero pad etc. For each block we selectively copy it, in | |
687 | * constant time, to |mac_out|. | |
688 | */ | |
689 | for (i = num_starting_blocks; i <= num_starting_blocks + variance_blocks; | |
690 | i++) { | |
691 | unsigned char block[MAX_HASH_BLOCK_SIZE]; | |
692 | unsigned char is_block_a = constant_time_eq_8(i, index_a); | |
693 | unsigned char is_block_b = constant_time_eq_8(i, index_b); | |
694 | for (j = 0; j < md_block_size; j++) { | |
695 | unsigned char b = 0, is_past_c, is_past_cp1; | |
696 | if (k < header_length) | |
697 | b = header[k]; | |
698 | else if (k < data_plus_mac_plus_padding_size + header_length) | |
699 | b = data[k - header_length]; | |
700 | k++; | |
701 | ||
702 | is_past_c = is_block_a & constant_time_ge_8(j, c); | |
703 | is_past_cp1 = is_block_a & constant_time_ge_8(j, c + 1); | |
704 | /* | |
705 | * If this is the block containing the end of the application | |
706 | * data, and we are at the offset for the 0x80 value, then | |
707 | * overwrite b with 0x80. | |
708 | */ | |
709 | b = constant_time_select_8(is_past_c, 0x80, b); | |
710 | /* | |
711 | * If this the the block containing the end of the application | |
712 | * data and we're past the 0x80 value then just write zero. | |
713 | */ | |
714 | b = b & ~is_past_cp1; | |
715 | /* | |
716 | * If this is index_b (the final block), but not index_a (the end | |
717 | * of the data), then the 64-bit length didn't fit into index_a | |
718 | * and we're having to add an extra block of zeros. | |
719 | */ | |
720 | b &= ~is_block_b | is_block_a; | |
721 | ||
722 | /* | |
723 | * The final bytes of one of the blocks contains the length. | |
724 | */ | |
725 | if (j >= md_block_size - md_length_size) { | |
726 | /* If this is index_b, write a length byte. */ | |
727 | b = constant_time_select_8(is_block_b, | |
728 | length_bytes[j - | |
729 | (md_block_size - | |
730 | md_length_size)], b); | |
731 | } | |
732 | block[j] = b; | |
733 | } | |
734 | ||
735 | md_transform(md_state.c, block); | |
736 | md_final_raw(md_state.c, block); | |
737 | /* If this is index_b, copy the hash value to |mac_out|. */ | |
738 | for (j = 0; j < md_size; j++) | |
739 | mac_out[j] |= block[j] & is_block_b; | |
740 | } | |
741 | ||
742 | EVP_MD_CTX_init(&md_ctx); | |
56d91346 MC |
743 | if (EVP_DigestInit_ex(&md_ctx, ctx->digest, NULL /* engine */ ) <= 0) |
744 | goto err; | |
ae5c8664 MC |
745 | if (is_sslv3) { |
746 | /* We repurpose |hmac_pad| to contain the SSLv3 pad2 block. */ | |
747 | memset(hmac_pad, 0x5c, sslv3_pad_length); | |
748 | ||
56d91346 MC |
749 | if (EVP_DigestUpdate(&md_ctx, mac_secret, mac_secret_length) <= 0 |
750 | || EVP_DigestUpdate(&md_ctx, hmac_pad, sslv3_pad_length) <= 0 | |
751 | || EVP_DigestUpdate(&md_ctx, mac_out, md_size) <= 0) | |
752 | goto err; | |
ae5c8664 MC |
753 | } else { |
754 | /* Complete the HMAC in the standard manner. */ | |
755 | for (i = 0; i < md_block_size; i++) | |
756 | hmac_pad[i] ^= 0x6a; | |
757 | ||
56d91346 MC |
758 | if (EVP_DigestUpdate(&md_ctx, hmac_pad, md_block_size) <= 0 |
759 | || EVP_DigestUpdate(&md_ctx, mac_out, md_size) <= 0) | |
760 | goto err; | |
ae5c8664 MC |
761 | } |
762 | EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u); | |
763 | if (md_out_size) | |
764 | *md_out_size = md_out_size_u; | |
765 | EVP_MD_CTX_cleanup(&md_ctx); | |
56d91346 MC |
766 | |
767 | return 1; | |
768 | err: | |
769 | EVP_MD_CTX_cleanup(&md_ctx); | |
770 | return 0; | |
ae5c8664 | 771 | } |
d91d9acc | 772 | |
e5cb7743 | 773 | #ifdef OPENSSL_FIPS |
d91d9acc | 774 | |
ae5c8664 MC |
775 | /* |
776 | * Due to the need to use EVP in FIPS mode we can't reimplement digests but | |
777 | * we can ensure the number of blocks processed is equal for all cases by | |
778 | * digesting additional data. | |
d91d9acc DSH |
779 | */ |
780 | ||
ae5c8664 MC |
781 | void tls_fips_digest_extra(const EVP_CIPHER_CTX *cipher_ctx, |
782 | EVP_MD_CTX *mac_ctx, const unsigned char *data, | |
783 | size_t data_len, size_t orig_len) | |
784 | { | |
785 | size_t block_size, digest_pad, blocks_data, blocks_orig; | |
786 | if (EVP_CIPHER_CTX_mode(cipher_ctx) != EVP_CIPH_CBC_MODE) | |
787 | return; | |
788 | block_size = EVP_MD_CTX_block_size(mac_ctx); | |
83975c80 MC |
789 | /*- |
790 | * We are in FIPS mode if we get this far so we know we have only SHA* | |
791 | * digests and TLS to deal with. | |
792 | * Minimum digest padding length is 17 for SHA384/SHA512 and 9 | |
793 | * otherwise. | |
794 | * Additional header is 13 bytes. To get the number of digest blocks | |
795 | * processed round up the amount of data plus padding to the nearest | |
796 | * block length. Block length is 128 for SHA384/SHA512 and 64 otherwise. | |
797 | * So we have: | |
798 | * blocks = (payload_len + digest_pad + 13 + block_size - 1)/block_size | |
799 | * equivalently: | |
800 | * blocks = (payload_len + digest_pad + 12)/block_size + 1 | |
801 | * HMAC adds a constant overhead. | |
802 | * We're ultimately only interested in differences so this becomes | |
803 | * blocks = (payload_len + 29)/128 | |
804 | * for SHA384/SHA512 and | |
805 | * blocks = (payload_len + 21)/64 | |
806 | * otherwise. | |
807 | */ | |
ae5c8664 MC |
808 | digest_pad = block_size == 64 ? 21 : 29; |
809 | blocks_orig = (orig_len + digest_pad) / block_size; | |
810 | blocks_data = (data_len + digest_pad) / block_size; | |
811 | /* | |
812 | * MAC enough blocks to make up the difference between the original and | |
813 | * actual lengths plus one extra block to ensure this is never a no op. | |
814 | * The "data" pointer should always have enough space to perform this | |
815 | * operation as it is large enough for a maximum length TLS buffer. | |
816 | */ | |
817 | EVP_DigestSignUpdate(mac_ctx, data, | |
818 | (blocks_orig - blocks_data + 1) * block_size); | |
819 | } | |
d91d9acc | 820 | #endif |