Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 1 | /* ==================================================================== |
| 2 | * Copyright (c) 2012 The OpenSSL Project. All rights reserved. |
| 3 | * |
| 4 | * Redistribution and use in source and binary forms, with or without |
| 5 | * modification, are permitted provided that the following conditions |
| 6 | * are met: |
| 7 | * |
| 8 | * 1. Redistributions of source code must retain the above copyright |
| 9 | * notice, this list of conditions and the following disclaimer. |
| 10 | * |
| 11 | * 2. Redistributions in binary form must reproduce the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer in |
| 13 | * the documentation and/or other materials provided with the |
| 14 | * distribution. |
| 15 | * |
| 16 | * 3. All advertising materials mentioning features or use of this |
| 17 | * software must display the following acknowledgment: |
| 18 | * "This product includes software developed by the OpenSSL Project |
| 19 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" |
| 20 | * |
| 21 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to |
| 22 | * endorse or promote products derived from this software without |
| 23 | * prior written permission. For written permission, please contact |
| 24 | * openssl-core@openssl.org. |
| 25 | * |
| 26 | * 5. Products derived from this software may not be called "OpenSSL" |
| 27 | * nor may "OpenSSL" appear in their names without prior written |
| 28 | * permission of the OpenSSL Project. |
| 29 | * |
| 30 | * 6. Redistributions of any form whatsoever must retain the following |
| 31 | * acknowledgment: |
| 32 | * "This product includes software developed by the OpenSSL Project |
| 33 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" |
| 34 | * |
| 35 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY |
| 36 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 37 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 38 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR |
| 39 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 40 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 41 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 42 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 43 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| 44 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 45 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| 46 | * OF THE POSSIBILITY OF SUCH DAMAGE. |
| 47 | * ==================================================================== |
| 48 | * |
| 49 | * This product includes cryptographic software written by Eric Young |
| 50 | * (eay@cryptsoft.com). This product includes software written by Tim |
| 51 | * Hudson (tjh@cryptsoft.com). */ |
| 52 | |
| 53 | #include <assert.h> |
| 54 | #include <string.h> |
| 55 | |
| 56 | #include <openssl/digest.h> |
David Benjamin | 4969cc9 | 2016-04-22 15:02:23 -0400 | [diff] [blame] | 57 | #include <openssl/nid.h> |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 58 | #include <openssl/sha.h> |
| 59 | |
| 60 | #include "../internal.h" |
David Benjamin | 4969cc9 | 2016-04-22 15:02:23 -0400 | [diff] [blame] | 61 | #include "internal.h" |
Robert Sloan | 8ff0355 | 2017-06-14 12:40:58 -0700 | [diff] [blame] | 62 | #include "../fipsmodule/cipher/internal.h" |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 63 | |
| 64 | |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 65 | /* MAX_HASH_BIT_COUNT_BYTES is the maximum number of bytes in the hash's length |
| 66 | * field. (SHA-384/512 have 128-bit length.) */ |
| 67 | #define MAX_HASH_BIT_COUNT_BYTES 16 |
| 68 | |
| 69 | /* MAX_HASH_BLOCK_SIZE is the maximum hash block size that we'll support. |
| 70 | * Currently SHA-384/512 has a 128-byte block size and that's the largest |
| 71 | * supported by TLS.) */ |
| 72 | #define MAX_HASH_BLOCK_SIZE 128 |
| 73 | |
Robert Sloan | 9254e68 | 2017-04-24 09:42:06 -0700 | [diff] [blame] | 74 | int EVP_tls_cbc_remove_padding(crypto_word_t *out_padding_ok, size_t *out_len, |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 75 | const uint8_t *in, size_t in_len, |
| 76 | size_t block_size, size_t mac_size) { |
| 77 | const size_t overhead = 1 /* padding length byte */ + mac_size; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 78 | |
| 79 | /* These lengths are all public so we can test them in non-constant time. */ |
| 80 | if (overhead > in_len) { |
| 81 | return 0; |
| 82 | } |
| 83 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 84 | size_t padding_length = in[in_len - 1]; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 85 | |
Robert Sloan | 9254e68 | 2017-04-24 09:42:06 -0700 | [diff] [blame] | 86 | crypto_word_t good = constant_time_ge_w(in_len, overhead + padding_length); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 87 | /* The padding consists of a length byte at the end of the record and |
| 88 | * then that many bytes of padding, all with the same value as the |
| 89 | * length byte. Thus, with the length byte included, there are i+1 |
| 90 | * bytes of padding. |
| 91 | * |
| 92 | * We can't check just |padding_length+1| bytes because that leaks |
| 93 | * decrypted information. Therefore we always have to check the maximum |
| 94 | * amount of padding possible. (Again, the length of the record is |
| 95 | * public information so we can use it.) */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 96 | size_t to_check = 256; /* maximum amount of padding, inc length byte. */ |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 97 | if (to_check > in_len) { |
| 98 | to_check = in_len; |
| 99 | } |
| 100 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 101 | for (size_t i = 0; i < to_check; i++) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 102 | uint8_t mask = constant_time_ge_8(padding_length, i); |
| 103 | uint8_t b = in[in_len - 1 - i]; |
| 104 | /* The final |padding_length+1| bytes should all have the value |
| 105 | * |padding_length|. Therefore the XOR should be zero. */ |
| 106 | good &= ~(mask & (padding_length ^ b)); |
| 107 | } |
| 108 | |
| 109 | /* If any of the final |padding_length+1| bytes had the wrong value, |
| 110 | * one or more of the lower eight bits of |good| will be cleared. */ |
Robert Sloan | 9254e68 | 2017-04-24 09:42:06 -0700 | [diff] [blame] | 111 | good = constant_time_eq_w(0xff, good & 0xff); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 112 | |
| 113 | /* Always treat |padding_length| as zero on error. If, assuming block size of |
| 114 | * 16, a padding of [<15 arbitrary bytes> 15] treated |padding_length| as 16 |
| 115 | * and returned -1, distinguishing good MAC and bad padding from bad MAC and |
| 116 | * bad padding would give POODLE's padding oracle. */ |
| 117 | padding_length = good & (padding_length + 1); |
| 118 | *out_len = in_len - padding_length; |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 119 | *out_padding_ok = good; |
| 120 | return 1; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 121 | } |
| 122 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 123 | void EVP_tls_cbc_copy_mac(uint8_t *out, size_t md_size, const uint8_t *in, |
| 124 | size_t in_len, size_t orig_len) { |
David Benjamin | 7c0d06c | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 125 | uint8_t rotated_mac1[EVP_MAX_MD_SIZE], rotated_mac2[EVP_MAX_MD_SIZE]; |
| 126 | uint8_t *rotated_mac = rotated_mac1; |
| 127 | uint8_t *rotated_mac_tmp = rotated_mac2; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 128 | |
| 129 | /* mac_end is the index of |in| just after the end of the MAC. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 130 | size_t mac_end = in_len; |
| 131 | size_t mac_start = mac_end - md_size; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 132 | |
| 133 | assert(orig_len >= in_len); |
| 134 | assert(in_len >= md_size); |
| 135 | assert(md_size <= EVP_MAX_MD_SIZE); |
| 136 | |
David Benjamin | 1b24967 | 2016-12-06 18:25:50 -0500 | [diff] [blame] | 137 | /* scan_start contains the number of bytes that we can ignore because |
| 138 | * the MAC's position can only vary by 255 bytes. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 139 | size_t scan_start = 0; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 140 | /* This information is public so it's safe to branch based on it. */ |
| 141 | if (orig_len > md_size + 255 + 1) { |
| 142 | scan_start = orig_len - (md_size + 255 + 1); |
| 143 | } |
David Benjamin | 4969cc9 | 2016-04-22 15:02:23 -0400 | [diff] [blame] | 144 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 145 | size_t rotate_offset = 0; |
David Benjamin | 1b24967 | 2016-12-06 18:25:50 -0500 | [diff] [blame] | 146 | uint8_t mac_started = 0; |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 147 | OPENSSL_memset(rotated_mac, 0, md_size); |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 148 | for (size_t i = scan_start, j = 0; i < orig_len; i++, j++) { |
David Benjamin | 1b24967 | 2016-12-06 18:25:50 -0500 | [diff] [blame] | 149 | if (j >= md_size) { |
| 150 | j -= md_size; |
| 151 | } |
Robert Sloan | 9254e68 | 2017-04-24 09:42:06 -0700 | [diff] [blame] | 152 | crypto_word_t is_mac_start = constant_time_eq_w(i, mac_start); |
David Benjamin | 1b24967 | 2016-12-06 18:25:50 -0500 | [diff] [blame] | 153 | mac_started |= is_mac_start; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 154 | uint8_t mac_ended = constant_time_ge_8(i, mac_end); |
David Benjamin | 1b24967 | 2016-12-06 18:25:50 -0500 | [diff] [blame] | 155 | rotated_mac[j] |= in[i] & mac_started & ~mac_ended; |
| 156 | /* Save the offset that |mac_start| is mapped to. */ |
| 157 | rotate_offset |= j & is_mac_start; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 158 | } |
| 159 | |
David Benjamin | 7c0d06c | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 160 | /* Now rotate the MAC. We rotate in log(md_size) steps, one for each bit |
| 161 | * position. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 162 | for (size_t offset = 1; offset < md_size; offset <<= 1, rotate_offset >>= 1) { |
David Benjamin | 7c0d06c | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 163 | /* Rotate by |offset| iff the corresponding bit is set in |
| 164 | * |rotate_offset|, placing the result in |rotated_mac_tmp|. */ |
| 165 | const uint8_t skip_rotate = (rotate_offset & 1) - 1; |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 166 | for (size_t i = 0, j = offset; i < md_size; i++, j++) { |
David Benjamin | 7c0d06c | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 167 | if (j >= md_size) { |
| 168 | j -= md_size; |
| 169 | } |
| 170 | rotated_mac_tmp[i] = |
| 171 | constant_time_select_8(skip_rotate, rotated_mac[i], rotated_mac[j]); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 172 | } |
David Benjamin | 7c0d06c | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 173 | |
| 174 | /* Swap pointers so |rotated_mac| contains the (possibly) rotated value. |
| 175 | * Note the number of iterations and thus the identity of these pointers is |
| 176 | * public information. */ |
| 177 | uint8_t *tmp = rotated_mac; |
| 178 | rotated_mac = rotated_mac_tmp; |
| 179 | rotated_mac_tmp = tmp; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 180 | } |
David Benjamin | 7c0d06c | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 181 | |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 182 | OPENSSL_memcpy(out, rotated_mac, md_size); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 183 | } |
| 184 | |
| 185 | /* u32toBE serialises an unsigned, 32-bit number (n) as four bytes at (p) in |
| 186 | * big-endian order. The value of p is advanced by four. */ |
David Benjamin | 95add82 | 2016-10-19 01:09:12 -0400 | [diff] [blame] | 187 | #define u32toBE(n, p) \ |
| 188 | do { \ |
| 189 | *((p)++) = (uint8_t)((n) >> 24); \ |
| 190 | *((p)++) = (uint8_t)((n) >> 16); \ |
| 191 | *((p)++) = (uint8_t)((n) >> 8); \ |
| 192 | *((p)++) = (uint8_t)((n)); \ |
| 193 | } while (0) |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 194 | |
| 195 | /* u64toBE serialises an unsigned, 64-bit number (n) as eight bytes at (p) in |
| 196 | * big-endian order. The value of p is advanced by eight. */ |
David Benjamin | 95add82 | 2016-10-19 01:09:12 -0400 | [diff] [blame] | 197 | #define u64toBE(n, p) \ |
| 198 | do { \ |
| 199 | *((p)++) = (uint8_t)((n) >> 56); \ |
| 200 | *((p)++) = (uint8_t)((n) >> 48); \ |
| 201 | *((p)++) = (uint8_t)((n) >> 40); \ |
| 202 | *((p)++) = (uint8_t)((n) >> 32); \ |
| 203 | *((p)++) = (uint8_t)((n) >> 24); \ |
| 204 | *((p)++) = (uint8_t)((n) >> 16); \ |
| 205 | *((p)++) = (uint8_t)((n) >> 8); \ |
| 206 | *((p)++) = (uint8_t)((n)); \ |
| 207 | } while (0) |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 208 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 209 | typedef union { |
| 210 | SHA_CTX sha1; |
| 211 | SHA256_CTX sha256; |
| 212 | SHA512_CTX sha512; |
| 213 | } HASH_CTX; |
| 214 | |
| 215 | static void tls1_sha1_transform(HASH_CTX *ctx, const uint8_t *block) { |
| 216 | SHA1_Transform(&ctx->sha1, block); |
| 217 | } |
| 218 | |
| 219 | static void tls1_sha256_transform(HASH_CTX *ctx, const uint8_t *block) { |
| 220 | SHA256_Transform(&ctx->sha256, block); |
| 221 | } |
| 222 | |
| 223 | static void tls1_sha512_transform(HASH_CTX *ctx, const uint8_t *block) { |
| 224 | SHA512_Transform(&ctx->sha512, block); |
| 225 | } |
| 226 | |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 227 | /* These functions serialize the state of a hash and thus perform the standard |
| 228 | * "final" operation without adding the padding and length that such a function |
| 229 | * typically does. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 230 | static void tls1_sha1_final_raw(HASH_CTX *ctx, uint8_t *md_out) { |
| 231 | SHA_CTX *sha1 = &ctx->sha1; |
Adam Langley | fad6327 | 2015-11-12 12:15:39 -0800 | [diff] [blame] | 232 | u32toBE(sha1->h[0], md_out); |
| 233 | u32toBE(sha1->h[1], md_out); |
| 234 | u32toBE(sha1->h[2], md_out); |
| 235 | u32toBE(sha1->h[3], md_out); |
| 236 | u32toBE(sha1->h[4], md_out); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 237 | } |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 238 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 239 | static void tls1_sha256_final_raw(HASH_CTX *ctx, uint8_t *md_out) { |
| 240 | SHA256_CTX *sha256 = &ctx->sha256; |
| 241 | for (unsigned i = 0; i < 8; i++) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 242 | u32toBE(sha256->h[i], md_out); |
| 243 | } |
| 244 | } |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 245 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 246 | static void tls1_sha512_final_raw(HASH_CTX *ctx, uint8_t *md_out) { |
| 247 | SHA512_CTX *sha512 = &ctx->sha512; |
| 248 | for (unsigned i = 0; i < 8; i++) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 249 | u64toBE(sha512->h[i], md_out); |
| 250 | } |
| 251 | } |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 252 | |
| 253 | int EVP_tls_cbc_record_digest_supported(const EVP_MD *md) { |
| 254 | switch (EVP_MD_type(md)) { |
| 255 | case NID_sha1: |
| 256 | case NID_sha256: |
| 257 | case NID_sha384: |
| 258 | return 1; |
| 259 | |
| 260 | default: |
| 261 | return 0; |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | int EVP_tls_cbc_digest_record(const EVP_MD *md, uint8_t *md_out, |
| 266 | size_t *md_out_size, const uint8_t header[13], |
| 267 | const uint8_t *data, size_t data_plus_mac_size, |
| 268 | size_t data_plus_mac_plus_padding_size, |
| 269 | const uint8_t *mac_secret, |
| 270 | unsigned mac_secret_length) { |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 271 | HASH_CTX md_state; |
| 272 | void (*md_final_raw)(HASH_CTX *ctx, uint8_t *md_out); |
| 273 | void (*md_transform)(HASH_CTX *ctx, const uint8_t *block); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 274 | unsigned md_size, md_block_size = 64; |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 275 | /* md_length_size is the number of bytes in the length field that terminates |
| 276 | * the hash. */ |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 277 | unsigned md_length_size = 8; |
| 278 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 279 | /* Bound the acceptable input so we can forget about many possible overflows |
| 280 | * later in this function. This is redundant with the record size limits in |
| 281 | * TLS. */ |
| 282 | if (data_plus_mac_plus_padding_size >= 1024 * 1024) { |
| 283 | assert(0); |
| 284 | return 0; |
| 285 | } |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 286 | |
| 287 | switch (EVP_MD_type(md)) { |
| 288 | case NID_sha1: |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 289 | SHA1_Init(&md_state.sha1); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 290 | md_final_raw = tls1_sha1_final_raw; |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 291 | md_transform = tls1_sha1_transform; |
| 292 | md_size = SHA_DIGEST_LENGTH; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 293 | break; |
| 294 | |
| 295 | case NID_sha256: |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 296 | SHA256_Init(&md_state.sha256); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 297 | md_final_raw = tls1_sha256_final_raw; |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 298 | md_transform = tls1_sha256_transform; |
| 299 | md_size = SHA256_DIGEST_LENGTH; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 300 | break; |
| 301 | |
| 302 | case NID_sha384: |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 303 | SHA384_Init(&md_state.sha512); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 304 | md_final_raw = tls1_sha512_final_raw; |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 305 | md_transform = tls1_sha512_transform; |
| 306 | md_size = SHA384_DIGEST_LENGTH; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 307 | md_block_size = 128; |
| 308 | md_length_size = 16; |
| 309 | break; |
| 310 | |
| 311 | default: |
| 312 | /* EVP_tls_cbc_record_digest_supported should have been called first to |
| 313 | * check that the hash function is supported. */ |
| 314 | assert(0); |
| 315 | *md_out_size = 0; |
| 316 | return 0; |
| 317 | } |
| 318 | |
| 319 | assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES); |
| 320 | assert(md_block_size <= MAX_HASH_BLOCK_SIZE); |
| 321 | assert(md_size <= EVP_MAX_MD_SIZE); |
| 322 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 323 | static const size_t kHeaderLength = 13; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 324 | |
| 325 | /* kVarianceBlocks is the number of blocks of the hash that we have to |
| 326 | * calculate in constant time because they could be altered by the |
| 327 | * padding value. |
| 328 | * |
| 329 | * TLSv1 has MACs up to 48 bytes long (SHA-384) and the padding is not |
| 330 | * required to be minimal. Therefore we say that the final six blocks |
| 331 | * can vary based on the padding. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 332 | static const size_t kVarianceBlocks = 6; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 333 | |
| 334 | /* From now on we're dealing with the MAC, which conceptually has 13 |
| 335 | * bytes of `header' before the start of the data. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 336 | size_t len = data_plus_mac_plus_padding_size + kHeaderLength; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 337 | /* max_mac_bytes contains the maximum bytes of bytes in the MAC, including |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 338 | * |header|, assuming that there's no padding. */ |
| 339 | size_t max_mac_bytes = len - md_size - 1; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 340 | /* num_blocks is the maximum number of hash blocks. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 341 | size_t num_blocks = |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 342 | (max_mac_bytes + 1 + md_length_size + md_block_size - 1) / md_block_size; |
| 343 | /* In order to calculate the MAC in constant time we have to handle |
| 344 | * the final blocks specially because the padding value could cause the |
| 345 | * end to appear somewhere in the final |kVarianceBlocks| blocks and we |
| 346 | * can't leak where. However, |num_starting_blocks| worth of data can |
| 347 | * be hashed right away because no padding value can affect whether |
| 348 | * they are plaintext. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 349 | size_t num_starting_blocks = 0; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 350 | /* k is the starting byte offset into the conceptual header||data where |
| 351 | * we start processing. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 352 | size_t k = 0; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 353 | /* mac_end_offset is the index just past the end of the data to be |
| 354 | * MACed. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 355 | size_t mac_end_offset = data_plus_mac_size + kHeaderLength - md_size; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 356 | /* c is the index of the 0x80 byte in the final hash block that |
| 357 | * contains application data. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 358 | size_t c = mac_end_offset % md_block_size; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 359 | /* index_a is the hash block number that contains the 0x80 terminating |
| 360 | * value. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 361 | size_t index_a = mac_end_offset / md_block_size; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 362 | /* index_b is the hash block number that contains the 64-bit hash |
| 363 | * length, in bits. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 364 | size_t index_b = (mac_end_offset + md_length_size) / md_block_size; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 365 | |
| 366 | if (num_blocks > kVarianceBlocks) { |
| 367 | num_starting_blocks = num_blocks - kVarianceBlocks; |
| 368 | k = md_block_size * num_starting_blocks; |
| 369 | } |
| 370 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 371 | /* bits is the hash-length in bits. It includes the additional hash |
| 372 | * block for the masked HMAC key. */ |
| 373 | size_t bits = 8 * mac_end_offset; /* at most 18 bits to represent */ |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 374 | |
| 375 | /* Compute the initial HMAC block. */ |
| 376 | bits += 8 * md_block_size; |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 377 | /* hmac_pad is the masked HMAC key. */ |
| 378 | uint8_t hmac_pad[MAX_HASH_BLOCK_SIZE]; |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 379 | OPENSSL_memset(hmac_pad, 0, md_block_size); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 380 | assert(mac_secret_length <= sizeof(hmac_pad)); |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 381 | OPENSSL_memcpy(hmac_pad, mac_secret, mac_secret_length); |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 382 | for (size_t i = 0; i < md_block_size; i++) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 383 | hmac_pad[i] ^= 0x36; |
| 384 | } |
| 385 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 386 | md_transform(&md_state, hmac_pad); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 387 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 388 | /* The length check means |bits| fits in four bytes. */ |
| 389 | uint8_t length_bytes[MAX_HASH_BIT_COUNT_BYTES]; |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 390 | OPENSSL_memset(length_bytes, 0, md_length_size - 4); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 391 | length_bytes[md_length_size - 4] = (uint8_t)(bits >> 24); |
| 392 | length_bytes[md_length_size - 3] = (uint8_t)(bits >> 16); |
| 393 | length_bytes[md_length_size - 2] = (uint8_t)(bits >> 8); |
| 394 | length_bytes[md_length_size - 1] = (uint8_t)bits; |
| 395 | |
| 396 | if (k > 0) { |
| 397 | /* k is a multiple of md_block_size. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 398 | uint8_t first_block[MAX_HASH_BLOCK_SIZE]; |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 399 | OPENSSL_memcpy(first_block, header, 13); |
| 400 | OPENSSL_memcpy(first_block + 13, data, md_block_size - 13); |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 401 | md_transform(&md_state, first_block); |
| 402 | for (size_t i = 1; i < k / md_block_size; i++) { |
| 403 | md_transform(&md_state, data + md_block_size * i - 13); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 404 | } |
| 405 | } |
| 406 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 407 | uint8_t mac_out[EVP_MAX_MD_SIZE]; |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 408 | OPENSSL_memset(mac_out, 0, sizeof(mac_out)); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 409 | |
| 410 | /* We now process the final hash blocks. For each block, we construct |
| 411 | * it in constant time. If the |i==index_a| then we'll include the 0x80 |
| 412 | * bytes and zero pad etc. For each block we selectively copy it, in |
| 413 | * constant time, to |mac_out|. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 414 | for (size_t i = num_starting_blocks; |
| 415 | i <= num_starting_blocks + kVarianceBlocks; i++) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 416 | uint8_t block[MAX_HASH_BLOCK_SIZE]; |
| 417 | uint8_t is_block_a = constant_time_eq_8(i, index_a); |
| 418 | uint8_t is_block_b = constant_time_eq_8(i, index_b); |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 419 | for (size_t j = 0; j < md_block_size; j++) { |
| 420 | uint8_t b = 0; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 421 | if (k < kHeaderLength) { |
| 422 | b = header[k]; |
| 423 | } else if (k < data_plus_mac_plus_padding_size + kHeaderLength) { |
| 424 | b = data[k - kHeaderLength]; |
| 425 | } |
| 426 | k++; |
| 427 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 428 | uint8_t is_past_c = is_block_a & constant_time_ge_8(j, c); |
| 429 | uint8_t is_past_cp1 = is_block_a & constant_time_ge_8(j, c + 1); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 430 | /* If this is the block containing the end of the |
| 431 | * application data, and we are at the offset for the |
| 432 | * 0x80 value, then overwrite b with 0x80. */ |
| 433 | b = constant_time_select_8(is_past_c, 0x80, b); |
| 434 | /* If this the the block containing the end of the |
| 435 | * application data and we're past the 0x80 value then |
| 436 | * just write zero. */ |
| 437 | b = b & ~is_past_cp1; |
| 438 | /* If this is index_b (the final block), but not |
| 439 | * index_a (the end of the data), then the 64-bit |
| 440 | * length didn't fit into index_a and we're having to |
| 441 | * add an extra block of zeros. */ |
| 442 | b &= ~is_block_b | is_block_a; |
| 443 | |
| 444 | /* The final bytes of one of the blocks contains the |
| 445 | * length. */ |
| 446 | if (j >= md_block_size - md_length_size) { |
| 447 | /* If this is index_b, write a length byte. */ |
| 448 | b = constant_time_select_8( |
| 449 | is_block_b, length_bytes[j - (md_block_size - md_length_size)], b); |
| 450 | } |
| 451 | block[j] = b; |
| 452 | } |
| 453 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 454 | md_transform(&md_state, block); |
| 455 | md_final_raw(&md_state, block); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 456 | /* If this is index_b, copy the hash value to |mac_out|. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 457 | for (size_t j = 0; j < md_size; j++) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 458 | mac_out[j] |= block[j] & is_block_b; |
| 459 | } |
| 460 | } |
| 461 | |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 462 | EVP_MD_CTX md_ctx; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 463 | EVP_MD_CTX_init(&md_ctx); |
| 464 | if (!EVP_DigestInit_ex(&md_ctx, md, NULL /* engine */)) { |
| 465 | EVP_MD_CTX_cleanup(&md_ctx); |
| 466 | return 0; |
| 467 | } |
| 468 | |
| 469 | /* Complete the HMAC in the standard manner. */ |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 470 | for (size_t i = 0; i < md_block_size; i++) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 471 | hmac_pad[i] ^= 0x6a; |
| 472 | } |
| 473 | |
| 474 | EVP_DigestUpdate(&md_ctx, hmac_pad, md_block_size); |
| 475 | EVP_DigestUpdate(&md_ctx, mac_out, md_size); |
Robert Sloan | 6f79a50 | 2017-04-03 09:16:40 -0700 | [diff] [blame] | 476 | unsigned md_out_size_u; |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 477 | EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u); |
| 478 | *md_out_size = md_out_size_u; |
| 479 | EVP_MD_CTX_cleanup(&md_ctx); |
| 480 | |
| 481 | return 1; |
| 482 | } |