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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 : :
56 : : #include "ssl_locl.h"
57 : :
58 : : #include <openssl/md5.h>
59 : : #include <openssl/sha.h>
60 : :
61 : : /* MAX_HASH_BIT_COUNT_BYTES is the maximum number of bytes in the hash's length
62 : : * field. (SHA-384/512 have 128-bit length.) */
63 : : #define MAX_HASH_BIT_COUNT_BYTES 16
64 : :
65 : : /* MAX_HASH_BLOCK_SIZE is the maximum hash block size that we'll support.
66 : : * Currently SHA-384/512 has a 128-byte block size and that's the largest
67 : : * supported by TLS.) */
68 : : #define MAX_HASH_BLOCK_SIZE 128
69 : :
70 : : /* Some utility functions are needed:
71 : : *
72 : : * These macros return the given value with the MSB copied to all the other
73 : : * bits. They use the fact that arithmetic shift shifts-in the sign bit.
74 : : * However, this is not ensured by the C standard so you may need to replace
75 : : * them with something else on odd CPUs. */
76 : : #define DUPLICATE_MSB_TO_ALL(x) ( (unsigned)( (int)(x) >> (sizeof(int)*8-1) ) )
77 : : #define DUPLICATE_MSB_TO_ALL_8(x) ((unsigned char)(DUPLICATE_MSB_TO_ALL(x)))
78 : :
79 : : /* constant_time_lt returns 0xff if a<b and 0x00 otherwise. */
80 : 169840 : static unsigned constant_time_lt(unsigned a, unsigned b)
81 : : {
82 : 169840 : a -= b;
83 : 169840 : return DUPLICATE_MSB_TO_ALL(a);
84 : : }
85 : :
86 : : /* constant_time_ge returns 0xff if a>=b and 0x00 otherwise. */
87 : 3364456 : static unsigned constant_time_ge(unsigned a, unsigned b)
88 : : {
89 : 3364456 : a -= b;
90 : 3364456 : return DUPLICATE_MSB_TO_ALL(~a);
91 : : }
92 : :
93 : : /* constant_time_eq_8 returns 0xff if a==b and 0x00 otherwise. */
94 : 7128 : static unsigned char constant_time_eq_8(unsigned a, unsigned b)
95 : : {
96 : 7128 : unsigned c = a ^ b;
97 : 7128 : c--;
98 : 7128 : return DUPLICATE_MSB_TO_ALL_8(c);
99 : : }
100 : :
101 : : /* ssl3_cbc_remove_padding removes padding from the decrypted, SSLv3, CBC
102 : : * record in |rec| by updating |rec->length| in constant time.
103 : : *
104 : : * block_size: the block size of the cipher used to encrypt the record.
105 : : * returns:
106 : : * 0: (in non-constant time) if the record is publicly invalid.
107 : : * 1: if the padding was valid
108 : : * -1: otherwise. */
109 : 1188 : int ssl3_cbc_remove_padding(const SSL* s,
110 : : SSL3_RECORD *rec,
111 : : unsigned block_size,
112 : : unsigned mac_size)
113 : : {
114 : : unsigned padding_length, good;
115 : 1188 : const unsigned overhead = 1 /* padding length byte */ + mac_size;
116 : :
117 : : /* These lengths are all public so we can test them in non-constant
118 : : * time. */
119 [ + - ]: 1188 : if (overhead > rec->length)
120 : : return 0;
121 : :
122 : 1188 : padding_length = rec->data[rec->length-1];
123 : 1188 : good = constant_time_ge(rec->length, padding_length+overhead);
124 : : /* SSLv3 requires that the padding is minimal. */
125 : 1188 : good &= constant_time_ge(block_size, padding_length+1);
126 : 1188 : rec->length -= good & (padding_length+1);
127 : 1188 : return (int)((good & 1) | (~good & -1));
128 : : }
129 : :
130 : : /* tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC
131 : : * record in |rec| in constant time and returns 1 if the padding is valid and
132 : : * -1 otherwise. It also removes any explicit IV from the start of the record
133 : : * without leaking any timing about whether there was enough space after the
134 : : * padding was removed.
135 : : *
136 : : * block_size: the block size of the cipher used to encrypt the record.
137 : : * returns:
138 : : * 0: (in non-constant time) if the record is publicly invalid.
139 : : * 1: if the padding was valid
140 : : * -1: otherwise. */
141 : 12789 : int tls1_cbc_remove_padding(const SSL* s,
142 : : SSL3_RECORD *rec,
143 : : unsigned block_size,
144 : : unsigned mac_size)
145 : : {
146 : : unsigned padding_length, good, to_check, i;
147 : 12789 : const unsigned overhead = 1 /* padding length byte */ + mac_size;
148 : : /* Check if version requires explicit IV */
149 [ + + ]: 12789 : if (SSL_USE_EXPLICIT_IV(s))
150 : : {
151 : : /* These lengths are all public so we can test them in
152 : : * non-constant time.
153 : : */
154 [ + - ]: 8972 : if (overhead + block_size > rec->length)
155 : : return 0;
156 : : /* We can now safely skip explicit IV */
157 : 8972 : rec->data += block_size;
158 : 8972 : rec->input += block_size;
159 : 8972 : rec->length -= block_size;
160 : 8972 : rec->orig_len -= block_size;
161 : : }
162 [ + - ]: 3817 : else if (overhead > rec->length)
163 : : return 0;
164 : :
165 : 12789 : padding_length = rec->data[rec->length-1];
166 : :
167 : : /* NB: if compression is in operation the first packet may not be of
168 : : * even length so the padding bug check cannot be performed. This bug
169 : : * workaround has been around since SSLeay so hopefully it is either
170 : : * fixed now or no buggy implementation supports compression [steve]
171 : : */
172 [ - + ][ # # ]: 12789 : if ( (s->options&SSL_OP_TLS_BLOCK_PADDING_BUG) && !s->expand)
173 : : {
174 : : /* First packet is even in size, so check */
175 [ # # ][ # # ]: 0 : if ((memcmp(s->s3->read_sequence, "\0\0\0\0\0\0\0\0",8) == 0) &&
176 : 0 : !(padding_length & 1))
177 : : {
178 : 0 : s->s3->flags|=TLS1_FLAGS_TLS_PADDING_BUG;
179 : : }
180 [ # # ][ # # ]: 0 : if ((s->s3->flags & TLS1_FLAGS_TLS_PADDING_BUG) &&
181 : : padding_length > 0)
182 : : {
183 : 0 : padding_length--;
184 : : }
185 : : }
186 : :
187 [ + + ]: 12789 : if (EVP_CIPHER_flags(s->enc_read_ctx->cipher)&EVP_CIPH_FLAG_AEAD_CIPHER)
188 : : {
189 : : /* padding is already verified */
190 : 396 : rec->length -= padding_length + 1;
191 : 396 : return 1;
192 : : }
193 : :
194 : 12393 : good = constant_time_ge(rec->length, overhead+padding_length);
195 : : /* The padding consists of a length byte at the end of the record and
196 : : * then that many bytes of padding, all with the same value as the
197 : : * length byte. Thus, with the length byte included, there are i+1
198 : : * bytes of padding.
199 : : *
200 : : * We can't check just |padding_length+1| bytes because that leaks
201 : : * decrypted information. Therefore we always have to check the maximum
202 : : * amount of padding possible. (Again, the length of the record is
203 : : * public information so we can use it.) */
204 : 12393 : to_check = 255; /* maximum amount of padding. */
205 [ + + ]: 12393 : if (to_check > rec->length-1)
206 : 2445 : to_check = rec->length-1;
207 : :
208 [ + + ]: 2613200 : for (i = 0; i < to_check; i++)
209 : : {
210 : 2600807 : unsigned char mask = constant_time_ge(padding_length, i);
211 : 2600807 : unsigned char b = rec->data[rec->length-1-i];
212 : : /* The final |padding_length+1| bytes should all have the value
213 : : * |padding_length|. Therefore the XOR should be zero. */
214 : 2600807 : good &= ~(mask&(padding_length ^ b));
215 : : }
216 : :
217 : : /* If any of the final |padding_length+1| bytes had the wrong value,
218 : : * one or more of the lower eight bits of |good| will be cleared. We
219 : : * AND the bottom 8 bits together and duplicate the result to all the
220 : : * bits. */
221 : 12393 : good &= good >> 4;
222 : 12393 : good &= good >> 2;
223 : 12393 : good &= good >> 1;
224 : 12393 : good <<= sizeof(good)*8-1;
225 : 12393 : good = DUPLICATE_MSB_TO_ALL(good);
226 : :
227 : 12393 : rec->length -= good & (padding_length+1);
228 : :
229 : 12393 : return (int)((good & 1) | (~good & -1));
230 : : }
231 : :
232 : : /* ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in
233 : : * constant time (independent of the concrete value of rec->length, which may
234 : : * vary within a 256-byte window).
235 : : *
236 : : * ssl3_cbc_remove_padding or tls1_cbc_remove_padding must be called prior to
237 : : * this function.
238 : : *
239 : : * On entry:
240 : : * rec->orig_len >= md_size
241 : : * md_size <= EVP_MAX_MD_SIZE
242 : : *
243 : : * If CBC_MAC_ROTATE_IN_PLACE is defined then the rotation is performed with
244 : : * variable accesses in a 64-byte-aligned buffer. Assuming that this fits into
245 : : * a single or pair of cache-lines, then the variable memory accesses don't
246 : : * actually affect the timing. CPUs with smaller cache-lines [if any] are
247 : : * not multi-core and are not considered vulnerable to cache-timing attacks.
248 : : */
249 : : #define CBC_MAC_ROTATE_IN_PLACE
250 : :
251 : 1188 : void ssl3_cbc_copy_mac(unsigned char* out,
252 : : const SSL3_RECORD *rec,
253 : : unsigned md_size)
254 : : {
255 : : #if defined(CBC_MAC_ROTATE_IN_PLACE)
256 : : unsigned char rotated_mac_buf[64+EVP_MAX_MD_SIZE];
257 : : unsigned char *rotated_mac;
258 : : #else
259 : : unsigned char rotated_mac[EVP_MAX_MD_SIZE];
260 : : #endif
261 : :
262 : : /* mac_end is the index of |rec->data| just after the end of the MAC. */
263 : 1188 : unsigned mac_end = rec->length;
264 : 1188 : unsigned mac_start = mac_end - md_size;
265 : : /* scan_start contains the number of bytes that we can ignore because
266 : : * the MAC's position can only vary by 255 bytes. */
267 : 1188 : unsigned scan_start = 0;
268 : : unsigned i, j;
269 : : unsigned div_spoiler;
270 : : unsigned rotate_offset;
271 : :
272 [ - + ]: 1188 : OPENSSL_assert(rec->orig_len >= md_size);
273 [ - + ]: 1188 : OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE);
274 : :
275 : : #if defined(CBC_MAC_ROTATE_IN_PLACE)
276 : 1188 : rotated_mac = rotated_mac_buf + ((0-(size_t)rotated_mac_buf)&63);
277 : : #endif
278 : :
279 : : /* This information is public so it's safe to branch based on it. */
280 [ + + ]: 1188 : if (rec->orig_len > md_size + 255 + 1)
281 : 396 : scan_start = rec->orig_len - (md_size + 255 + 1);
282 : : /* div_spoiler contains a multiple of md_size that is used to cause the
283 : : * modulo operation to be constant time. Without this, the time varies
284 : : * based on the amount of padding when running on Intel chips at least.
285 : : *
286 : : * The aim of right-shifting md_size is so that the compiler doesn't
287 : : * figure out that it can remove div_spoiler as that would require it
288 : : * to prove that md_size is always even, which I hope is beyond it. */
289 : 1188 : div_spoiler = md_size >> 1;
290 : 1188 : div_spoiler <<= (sizeof(div_spoiler)-1)*8;
291 : 1188 : rotate_offset = (div_spoiler + mac_start - scan_start) % md_size;
292 : :
293 : 1188 : memset(rotated_mac, 0, md_size);
294 [ + + ]: 147532 : for (i = scan_start, j = 0; i < rec->orig_len; i++)
295 : : {
296 : 146344 : unsigned char mac_started = constant_time_ge(i, mac_start);
297 : 146344 : unsigned char mac_ended = constant_time_ge(i, mac_end);
298 : 146344 : unsigned char b = rec->data[i];
299 : 146344 : rotated_mac[j++] |= b & mac_started & ~mac_ended;
300 : 146344 : j &= constant_time_lt(j,md_size);
301 : : }
302 : :
303 : : /* Now rotate the MAC */
304 : : #if defined(CBC_MAC_ROTATE_IN_PLACE)
305 : : j = 0;
306 [ + + ]: 24684 : for (i = 0; i < md_size; i++)
307 : : {
308 : : /* in case cache-line is 32 bytes, touch second line */
309 : 23496 : ((volatile unsigned char *)rotated_mac)[rotate_offset^32];
310 : 23496 : out[j++] = rotated_mac[rotate_offset++];
311 : 23496 : rotate_offset &= constant_time_lt(rotate_offset,md_size);
312 : : }
313 : : #else
314 : : memset(out, 0, md_size);
315 : : rotate_offset = md_size - rotate_offset;
316 : : rotate_offset &= constant_time_lt(rotate_offset,md_size);
317 : : for (i = 0; i < md_size; i++)
318 : : {
319 : : for (j = 0; j < md_size; j++)
320 : : out[j] |= rotated_mac[i] & constant_time_eq_8(j, rotate_offset);
321 : : rotate_offset++;
322 : : rotate_offset &= constant_time_lt(rotate_offset,md_size);
323 : : }
324 : : #endif
325 : 1188 : }
326 : :
327 : : /* u32toLE serialises an unsigned, 32-bit number (n) as four bytes at (p) in
328 : : * little-endian order. The value of p is advanced by four. */
329 : : #define u32toLE(n, p) \
330 : : (*((p)++)=(unsigned char)(n), \
331 : : *((p)++)=(unsigned char)(n>>8), \
332 : : *((p)++)=(unsigned char)(n>>16), \
333 : : *((p)++)=(unsigned char)(n>>24))
334 : :
335 : : /* These functions serialize the state of a hash and thus perform the standard
336 : : * "final" operation without adding the padding and length that such a function
337 : : * typically does. */
338 : 198 : static void tls1_md5_final_raw(void* ctx, unsigned char *md_out)
339 : : {
340 : 198 : MD5_CTX *md5 = ctx;
341 : 198 : u32toLE(md5->A, md_out);
342 : 198 : u32toLE(md5->B, md_out);
343 : 198 : u32toLE(md5->C, md_out);
344 : 198 : u32toLE(md5->D, md_out);
345 : 198 : }
346 : :
347 : 3366 : static void tls1_sha1_final_raw(void* ctx, unsigned char *md_out)
348 : : {
349 : 3366 : SHA_CTX *sha1 = ctx;
350 : 3366 : l2n(sha1->h0, md_out);
351 : 3366 : l2n(sha1->h1, md_out);
352 : 3366 : l2n(sha1->h2, md_out);
353 : 3366 : l2n(sha1->h3, md_out);
354 : 3366 : l2n(sha1->h4, md_out);
355 : 3366 : }
356 : : #define LARGEST_DIGEST_CTX SHA_CTX
357 : :
358 : : #ifndef OPENSSL_NO_SHA256
359 : 0 : static void tls1_sha256_final_raw(void* ctx, unsigned char *md_out)
360 : : {
361 : 0 : SHA256_CTX *sha256 = ctx;
362 : : unsigned i;
363 : :
364 [ # # ]: 0 : for (i = 0; i < 8; i++)
365 : : {
366 : 0 : l2n(sha256->h[i], md_out);
367 : : }
368 : 0 : }
369 : : #undef LARGEST_DIGEST_CTX
370 : : #define LARGEST_DIGEST_CTX SHA256_CTX
371 : : #endif
372 : :
373 : : #ifndef OPENSSL_NO_SHA512
374 : 0 : static void tls1_sha512_final_raw(void* ctx, unsigned char *md_out)
375 : : {
376 : 0 : SHA512_CTX *sha512 = ctx;
377 : : unsigned i;
378 : :
379 [ # # ]: 0 : for (i = 0; i < 8; i++)
380 : : {
381 : 0 : l2n8(sha512->h[i], md_out);
382 : : }
383 : 0 : }
384 : : #undef LARGEST_DIGEST_CTX
385 : : #define LARGEST_DIGEST_CTX SHA512_CTX
386 : : #endif
387 : :
388 : : /* ssl3_cbc_record_digest_supported returns 1 iff |ctx| uses a hash function
389 : : * which ssl3_cbc_digest_record supports. */
390 : 1188 : char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx)
391 : : {
392 : : #ifdef OPENSSL_FIPS
393 : : if (FIPS_mode())
394 : : return 0;
395 : : #endif
396 [ - + ]: 1188 : switch (EVP_MD_CTX_type(ctx))
397 : : {
398 : : case NID_md5:
399 : : case NID_sha1:
400 : : #ifndef OPENSSL_NO_SHA256
401 : : case NID_sha224:
402 : : case NID_sha256:
403 : : #endif
404 : : #ifndef OPENSSL_NO_SHA512
405 : : case NID_sha384:
406 : : case NID_sha512:
407 : : #endif
408 : : return 1;
409 : : default:
410 : 0 : return 0;
411 : : }
412 : : }
413 : :
414 : : /* ssl3_cbc_digest_record computes the MAC of a decrypted, padded SSLv3/TLS
415 : : * record.
416 : : *
417 : : * ctx: the EVP_MD_CTX from which we take the hash function.
418 : : * ssl3_cbc_record_digest_supported must return true for this EVP_MD_CTX.
419 : : * md_out: the digest output. At most EVP_MAX_MD_SIZE bytes will be written.
420 : : * md_out_size: if non-NULL, the number of output bytes is written here.
421 : : * header: the 13-byte, TLS record header.
422 : : * data: the record data itself, less any preceding explicit IV.
423 : : * data_plus_mac_size: the secret, reported length of the data and MAC
424 : : * once the padding has been removed.
425 : : * data_plus_mac_plus_padding_size: the public length of the whole
426 : : * record, including padding.
427 : : * is_sslv3: non-zero if we are to use SSLv3. Otherwise, TLS.
428 : : *
429 : : * On entry: by virtue of having been through one of the remove_padding
430 : : * functions, above, we know that data_plus_mac_size is large enough to contain
431 : : * a padding byte and MAC. (If the padding was invalid, it might contain the
432 : : * padding too. ) */
433 : 1188 : void ssl3_cbc_digest_record(
434 : : const EVP_MD_CTX *ctx,
435 : : unsigned char* md_out,
436 : : size_t* md_out_size,
437 : : const unsigned char header[13],
438 : : const unsigned char *data,
439 : : size_t data_plus_mac_size,
440 : : size_t data_plus_mac_plus_padding_size,
441 : : const unsigned char *mac_secret,
442 : : unsigned mac_secret_length,
443 : : char is_sslv3)
444 : : {
445 : : union { double align;
446 : : unsigned char c[sizeof(LARGEST_DIGEST_CTX)]; } md_state;
447 : : void (*md_final_raw)(void *ctx, unsigned char *md_out);
448 : : void (*md_transform)(void *ctx, const unsigned char *block);
449 : 1188 : unsigned md_size, md_block_size = 64;
450 : 1188 : unsigned sslv3_pad_length = 40, header_length, variance_blocks,
451 : : len, max_mac_bytes, num_blocks,
452 : : num_starting_blocks, k, mac_end_offset, c, index_a, index_b;
453 : : unsigned int bits; /* at most 18 bits */
454 : : unsigned char length_bytes[MAX_HASH_BIT_COUNT_BYTES];
455 : : /* hmac_pad is the masked HMAC key. */
456 : : unsigned char hmac_pad[MAX_HASH_BLOCK_SIZE];
457 : : unsigned char first_block[MAX_HASH_BLOCK_SIZE];
458 : : unsigned char mac_out[EVP_MAX_MD_SIZE];
459 : : unsigned i, j, md_out_size_u;
460 : : EVP_MD_CTX md_ctx;
461 : : /* mdLengthSize is the number of bytes in the length field that terminates
462 : : * the hash. */
463 : 1188 : unsigned md_length_size = 8;
464 : 1188 : char length_is_big_endian = 1;
465 : : int ret;
466 : :
467 : : /* This is a, hopefully redundant, check that allows us to forget about
468 : : * many possible overflows later in this function. */
469 [ - + ]: 1188 : OPENSSL_assert(data_plus_mac_plus_padding_size < 1024*1024);
470 : :
471 [ + + - - : 1188 : switch (EVP_MD_CTX_type(ctx))
- - - ]
472 : : {
473 : : case NID_md5:
474 : 66 : MD5_Init((MD5_CTX*)md_state.c);
475 : 66 : md_final_raw = tls1_md5_final_raw;
476 : 66 : md_transform = (void(*)(void *ctx, const unsigned char *block)) MD5_Transform;
477 : 66 : md_size = 16;
478 : 66 : sslv3_pad_length = 48;
479 : 66 : length_is_big_endian = 0;
480 : 66 : break;
481 : : case NID_sha1:
482 : 1122 : SHA1_Init((SHA_CTX*)md_state.c);
483 : 1122 : md_final_raw = tls1_sha1_final_raw;
484 : 1122 : md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA1_Transform;
485 : 1122 : md_size = 20;
486 : 1122 : break;
487 : : #ifndef OPENSSL_NO_SHA256
488 : : case NID_sha224:
489 : 0 : SHA224_Init((SHA256_CTX*)md_state.c);
490 : 0 : md_final_raw = tls1_sha256_final_raw;
491 : 0 : md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA256_Transform;
492 : 0 : md_size = 224/8;
493 : 0 : break;
494 : : case NID_sha256:
495 : 0 : SHA256_Init((SHA256_CTX*)md_state.c);
496 : 0 : md_final_raw = tls1_sha256_final_raw;
497 : 0 : md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA256_Transform;
498 : 0 : md_size = 32;
499 : 0 : break;
500 : : #endif
501 : : #ifndef OPENSSL_NO_SHA512
502 : : case NID_sha384:
503 : 0 : SHA384_Init((SHA512_CTX*)md_state.c);
504 : 0 : md_final_raw = tls1_sha512_final_raw;
505 : 0 : md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA512_Transform;
506 : 0 : md_size = 384/8;
507 : 0 : md_block_size = 128;
508 : 0 : md_length_size = 16;
509 : 0 : break;
510 : : case NID_sha512:
511 : 0 : SHA512_Init((SHA512_CTX*)md_state.c);
512 : 0 : md_final_raw = tls1_sha512_final_raw;
513 : 0 : md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA512_Transform;
514 : 0 : md_size = 64;
515 : 0 : md_block_size = 128;
516 : 0 : md_length_size = 16;
517 : 0 : break;
518 : : #endif
519 : : default:
520 : : /* ssl3_cbc_record_digest_supported should have been
521 : : * called first to check that the hash function is
522 : : * supported. */
523 : 0 : OPENSSL_assert(0);
524 [ # # ]: 0 : if (md_out_size)
525 : 0 : *md_out_size = -1;
526 : 0 : return;
527 : : }
528 : :
529 [ - + ]: 1188 : OPENSSL_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES);
530 [ - + ]: 1188 : OPENSSL_assert(md_block_size <= MAX_HASH_BLOCK_SIZE);
531 [ - + ]: 1188 : OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE);
532 : :
533 : 1188 : header_length = 13;
534 [ + - ]: 1188 : if (is_sslv3)
535 : : {
536 : 1188 : header_length =
537 : 1188 : mac_secret_length +
538 : : sslv3_pad_length +
539 : : 8 /* sequence number */ +
540 : : 1 /* record type */ +
541 : : 2 /* record length */;
542 : : }
543 : :
544 : : /* variance_blocks is the number of blocks of the hash that we have to
545 : : * calculate in constant time because they could be altered by the
546 : : * padding value.
547 : : *
548 : : * In SSLv3, the padding must be minimal so the end of the plaintext
549 : : * varies by, at most, 15+20 = 35 bytes. (We conservatively assume that
550 : : * the MAC size varies from 0..20 bytes.) In case the 9 bytes of hash
551 : : * termination (0x80 + 64-bit length) don't fit in the final block, we
552 : : * say that the final two blocks can vary based on the padding.
553 : : *
554 : : * TLSv1 has MACs up to 48 bytes long (SHA-384) and the padding is not
555 : : * required to be minimal. Therefore we say that the final six blocks
556 : : * can vary based on the padding.
557 : : *
558 : : * Later in the function, if the message is short and there obviously
559 : : * cannot be this many blocks then variance_blocks can be reduced. */
560 [ - + ]: 1188 : variance_blocks = is_sslv3 ? 2 : 6;
561 : : /* From now on we're dealing with the MAC, which conceptually has 13
562 : : * bytes of `header' before the start of the data (TLS) or 71/75 bytes
563 : : * (SSLv3) */
564 : 1188 : len = data_plus_mac_plus_padding_size + header_length;
565 : : /* max_mac_bytes contains the maximum bytes of bytes in the MAC, including
566 : : * |header|, assuming that there's no padding. */
567 : 1188 : max_mac_bytes = len - md_size - 1;
568 : : /* num_blocks is the maximum number of hash blocks. */
569 : 1188 : num_blocks = (max_mac_bytes + 1 + md_length_size + md_block_size - 1) / md_block_size;
570 : : /* In order to calculate the MAC in constant time we have to handle
571 : : * the final blocks specially because the padding value could cause the
572 : : * end to appear somewhere in the final |variance_blocks| blocks and we
573 : : * can't leak where. However, |num_starting_blocks| worth of data can
574 : : * be hashed right away because no padding value can affect whether
575 : : * they are plaintext. */
576 : 1188 : num_starting_blocks = 0;
577 : : /* k is the starting byte offset into the conceptual header||data where
578 : : * we start processing. */
579 : 1188 : k = 0;
580 : : /* mac_end_offset is the index just past the end of the data to be
581 : : * MACed. */
582 : 1188 : mac_end_offset = data_plus_mac_size + header_length - md_size;
583 : : /* c is the index of the 0x80 byte in the final hash block that
584 : : * contains application data. */
585 : 1188 : c = mac_end_offset % md_block_size;
586 : : /* index_a is the hash block number that contains the 0x80 terminating
587 : : * value. */
588 : 1188 : index_a = mac_end_offset / md_block_size;
589 : : /* index_b is the hash block number that contains the 64-bit hash
590 : : * length, in bits. */
591 : 1188 : index_b = (mac_end_offset + md_length_size) / md_block_size;
592 : : /* bits is the hash-length in bits. It includes the additional hash
593 : : * block for the masked HMAC key, or whole of |header| in the case of
594 : : * SSLv3. */
595 : :
596 : : /* For SSLv3, if we're going to have any starting blocks then we need
597 : : * at least two because the header is larger than a single block. */
598 [ - + ][ + + ]: 1188 : if (num_blocks > variance_blocks + (is_sslv3 ? 1 : 0))
599 : : {
600 : 396 : num_starting_blocks = num_blocks - variance_blocks;
601 : 396 : k = md_block_size*num_starting_blocks;
602 : : }
603 : :
604 : 1188 : bits = 8*mac_end_offset;
605 [ - + ]: 1188 : if (!is_sslv3)
606 : : {
607 : : /* Compute the initial HMAC block. For SSLv3, the padding and
608 : : * secret bytes are included in |header| because they take more
609 : : * than a single block. */
610 : 0 : bits += 8*md_block_size;
611 : 0 : memset(hmac_pad, 0, md_block_size);
612 [ # # ]: 0 : OPENSSL_assert(mac_secret_length <= sizeof(hmac_pad));
613 : 0 : memcpy(hmac_pad, mac_secret, mac_secret_length);
614 [ # # ]: 0 : for (i = 0; i < md_block_size; i++)
615 : 0 : hmac_pad[i] ^= 0x36;
616 : :
617 : 0 : md_transform(md_state.c, hmac_pad);
618 : : }
619 : :
620 [ + + ]: 1188 : if (length_is_big_endian)
621 : : {
622 : 1122 : memset(length_bytes,0,md_length_size-4);
623 : 1122 : length_bytes[md_length_size-4] = (unsigned char)(bits>>24);
624 : 1122 : length_bytes[md_length_size-3] = (unsigned char)(bits>>16);
625 : 1122 : length_bytes[md_length_size-2] = (unsigned char)(bits>>8);
626 : 1122 : length_bytes[md_length_size-1] = (unsigned char)bits;
627 : : }
628 : : else
629 : : {
630 : 66 : memset(length_bytes,0,md_length_size);
631 : 66 : length_bytes[md_length_size-5] = (unsigned char)(bits>>24);
632 : 66 : length_bytes[md_length_size-6] = (unsigned char)(bits>>16);
633 : 66 : length_bytes[md_length_size-7] = (unsigned char)(bits>>8);
634 : 66 : length_bytes[md_length_size-8] = (unsigned char)bits;
635 : : }
636 : :
637 [ + + ]: 1188 : if (k > 0)
638 : : {
639 [ + - ]: 396 : if (is_sslv3)
640 : : {
641 : : /* The SSLv3 header is larger than a single block.
642 : : * overhang is the number of bytes beyond a single
643 : : * block that the header consumes: either 7 bytes
644 : : * (SHA1) or 11 bytes (MD5). */
645 : 396 : unsigned overhang = header_length-md_block_size;
646 : 396 : md_transform(md_state.c, header);
647 : 396 : memcpy(first_block, header + md_block_size, overhang);
648 : 396 : memcpy(first_block + overhang, data, md_block_size-overhang);
649 : 396 : md_transform(md_state.c, first_block);
650 [ + + ]: 1188 : for (i = 1; i < k/md_block_size - 1; i++)
651 : 792 : md_transform(md_state.c, data + md_block_size*i - overhang);
652 : : }
653 : : else
654 : : {
655 : : /* k is a multiple of md_block_size. */
656 : : memcpy(first_block, header, 13);
657 : 0 : memcpy(first_block+13, data, md_block_size-13);
658 : 0 : md_transform(md_state.c, first_block);
659 [ # # ]: 0 : for (i = 1; i < k/md_block_size; i++)
660 : 0 : md_transform(md_state.c, data + md_block_size*i - 13);
661 : : }
662 : : }
663 : :
664 : : memset(mac_out, 0, sizeof(mac_out));
665 : :
666 : : /* We now process the final hash blocks. For each block, we construct
667 : : * it in constant time. If the |i==index_a| then we'll include the 0x80
668 : : * bytes and zero pad etc. For each block we selectively copy it, in
669 : : * constant time, to |mac_out|. */
670 [ + + ]: 4752 : for (i = num_starting_blocks; i <= num_starting_blocks+variance_blocks; i++)
671 : : {
672 : : unsigned char block[MAX_HASH_BLOCK_SIZE];
673 : 3564 : unsigned char is_block_a = constant_time_eq_8(i, index_a);
674 : 3564 : unsigned char is_block_b = constant_time_eq_8(i, index_b);
675 [ + + ]: 231660 : for (j = 0; j < md_block_size; j++)
676 : : {
677 : 228096 : unsigned char b = 0, is_past_c, is_past_cp1;
678 [ + + ]: 228096 : if (k < header_length)
679 : 56408 : b = header[k];
680 [ + + ]: 171688 : else if (k < data_plus_mac_plus_padding_size + header_length)
681 : 77132 : b = data[k-header_length];
682 : 228096 : k++;
683 : :
684 : 228096 : is_past_c = is_block_a & constant_time_ge(j, c);
685 : 228096 : is_past_cp1 = is_block_a & constant_time_ge(j, c+1);
686 : : /* If this is the block containing the end of the
687 : : * application data, and we are at the offset for the
688 : : * 0x80 value, then overwrite b with 0x80. */
689 : 228096 : b = (b&~is_past_c) | (0x80&is_past_c);
690 : : /* If this the the block containing the end of the
691 : : * application data and we're past the 0x80 value then
692 : : * just write zero. */
693 : 228096 : b = b&~is_past_cp1;
694 : : /* If this is index_b (the final block), but not
695 : : * index_a (the end of the data), then the 64-bit
696 : : * length didn't fit into index_a and we're having to
697 : : * add an extra block of zeros. */
698 : 228096 : b &= ~is_block_b | is_block_a;
699 : :
700 : : /* The final bytes of one of the blocks contains the
701 : : * length. */
702 [ + + ]: 228096 : if (j >= md_block_size - md_length_size)
703 : : {
704 : : /* If this is index_b, write a length byte. */
705 : 28512 : b = (b&~is_block_b) | (is_block_b&length_bytes[j-(md_block_size-md_length_size)]);
706 : : }
707 : 228096 : block[j] = b;
708 : : }
709 : :
710 : 3564 : md_transform(md_state.c, block);
711 : 3564 : md_final_raw(md_state.c, block);
712 : : /* If this is index_b, copy the hash value to |mac_out|. */
713 [ + + ]: 74052 : for (j = 0; j < md_size; j++)
714 : 70488 : mac_out[j] |= block[j]&is_block_b;
715 : : }
716 : :
717 : 1188 : EVP_MD_CTX_init(&md_ctx);
718 : 1188 : EVP_DigestInit_ex(&md_ctx, ctx->digest, NULL /* engine */);
719 [ - + ]: 1188 : if (is_sslv3)
720 : : {
721 : : /* We repurpose |hmac_pad| to contain the SSLv3 pad2 block. */
722 : 1188 : memset(hmac_pad, 0x5c, sslv3_pad_length);
723 : :
724 : 1188 : EVP_DigestUpdate(&md_ctx, mac_secret, mac_secret_length);
725 : 1188 : EVP_DigestUpdate(&md_ctx, hmac_pad, sslv3_pad_length);
726 : 1188 : EVP_DigestUpdate(&md_ctx, mac_out, md_size);
727 : : }
728 : : else
729 : : {
730 : : /* Complete the HMAC in the standard manner. */
731 [ # # ]: 0 : for (i = 0; i < md_block_size; i++)
732 : 0 : hmac_pad[i] ^= 0x6a;
733 : :
734 : 0 : EVP_DigestUpdate(&md_ctx, hmac_pad, md_block_size);
735 : 0 : EVP_DigestUpdate(&md_ctx, mac_out, md_size);
736 : : }
737 : 1188 : ret = EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u);
738 [ + - ]: 1188 : if (ret && md_out_size)
739 : 1188 : *md_out_size = md_out_size_u;
740 : 1188 : EVP_MD_CTX_cleanup(&md_ctx);
741 : : }
742 : :
743 : : #ifdef OPENSSL_FIPS
744 : :
745 : : /* Due to the need to use EVP in FIPS mode we can't reimplement digests but
746 : : * we can ensure the number of blocks processed is equal for all cases
747 : : * by digesting additional data.
748 : : */
749 : :
750 : : void tls_fips_digest_extra(
751 : : const EVP_CIPHER_CTX *cipher_ctx, EVP_MD_CTX *mac_ctx,
752 : : const unsigned char *data, size_t data_len, size_t orig_len)
753 : : {
754 : : size_t block_size, digest_pad, blocks_data, blocks_orig;
755 : : if (EVP_CIPHER_CTX_mode(cipher_ctx) != EVP_CIPH_CBC_MODE)
756 : : return;
757 : : block_size = EVP_MD_CTX_block_size(mac_ctx);
758 : : /* We are in FIPS mode if we get this far so we know we have only SHA*
759 : : * digests and TLS to deal with.
760 : : * Minimum digest padding length is 17 for SHA384/SHA512 and 9
761 : : * otherwise.
762 : : * Additional header is 13 bytes. To get the number of digest blocks
763 : : * processed round up the amount of data plus padding to the nearest
764 : : * block length. Block length is 128 for SHA384/SHA512 and 64 otherwise.
765 : : * So we have:
766 : : * blocks = (payload_len + digest_pad + 13 + block_size - 1)/block_size
767 : : * equivalently:
768 : : * blocks = (payload_len + digest_pad + 12)/block_size + 1
769 : : * HMAC adds a constant overhead.
770 : : * We're ultimately only interested in differences so this becomes
771 : : * blocks = (payload_len + 29)/128
772 : : * for SHA384/SHA512 and
773 : : * blocks = (payload_len + 21)/64
774 : : * otherwise.
775 : : */
776 : : digest_pad = block_size == 64 ? 21 : 29;
777 : : blocks_orig = (orig_len + digest_pad)/block_size;
778 : : blocks_data = (data_len + digest_pad)/block_size;
779 : : /* MAC enough blocks to make up the difference between the original
780 : : * and actual lengths plus one extra block to ensure this is never a
781 : : * no op. The "data" pointer should always have enough space to
782 : : * perform this operation as it is large enough for a maximum
783 : : * length TLS buffer.
784 : : */
785 : : EVP_DigestSignUpdate(mac_ctx, data,
786 : : (blocks_orig - blocks_data + 1) * block_size);
787 : : }
788 : : #endif
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