diff options
Diffstat (limited to 'ssl/s3_cbc.c')
| -rw-r--r-- | ssl/s3_cbc.c | 1242 |
1 files changed, 641 insertions, 601 deletions
diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c index 11f13ad..598d27e 100644 --- a/ssl/s3_cbc.c +++ b/ssl/s3_cbc.c @@ -59,47 +59,54 @@ #include <openssl/md5.h> #include <openssl/sha.h> -/* MAX_HASH_BIT_COUNT_BYTES is the maximum number of bytes in the hash's length - * field. (SHA-384/512 have 128-bit length.) */ +/* + * MAX_HASH_BIT_COUNT_BYTES is the maximum number of bytes in the hash's + * length field. (SHA-384/512 have 128-bit length.) + */ #define MAX_HASH_BIT_COUNT_BYTES 16 -/* MAX_HASH_BLOCK_SIZE is the maximum hash block size that we'll support. +/* + * MAX_HASH_BLOCK_SIZE is the maximum hash block size that we'll support. * Currently SHA-384/512 has a 128-byte block size and that's the largest - * supported by TLS.) */ + * supported by TLS.) + */ #define MAX_HASH_BLOCK_SIZE 128 -/* ssl3_cbc_remove_padding removes padding from the decrypted, SSLv3, CBC +/*- + * ssl3_cbc_remove_padding removes padding from the decrypted, SSLv3, CBC * record in |rec| by updating |rec->length| in constant time. * * block_size: the block size of the cipher used to encrypt the record. * returns: * 0: (in non-constant time) if the record is publicly invalid. * 1: if the padding was valid - * -1: otherwise. */ -int ssl3_cbc_remove_padding(const SSL* s, - SSL3_RECORD *rec, - unsigned block_size, - unsigned mac_size) - { - unsigned padding_length, good; - const unsigned overhead = 1 /* padding length byte */ + mac_size; - - /* These lengths are all public so we can test them in non-constant - * time. */ - if (overhead > rec->length) - return 0; - - padding_length = rec->data[rec->length-1]; - good = constant_time_ge(rec->length, padding_length+overhead); - /* SSLv3 requires that the padding is minimal. */ - good &= constant_time_ge(block_size, padding_length+1); - padding_length = good & (padding_length+1); - rec->length -= padding_length; - rec->type |= padding_length<<8; /* kludge: pass padding length */ - return constant_time_select_int(good, 1, -1); - } - -/* tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC + * -1: otherwise. + */ +int ssl3_cbc_remove_padding(const SSL *s, + SSL3_RECORD *rec, + unsigned block_size, unsigned mac_size) +{ + unsigned padding_length, good; + const unsigned overhead = 1 /* padding length byte */ + mac_size; + + /* + * These lengths are all public so we can test them in non-constant time. + */ + if (overhead > rec->length) + return 0; + + padding_length = rec->data[rec->length - 1]; + good = constant_time_ge(rec->length, padding_length + overhead); + /* SSLv3 requires that the padding is minimal. */ + good &= constant_time_ge(block_size, padding_length + 1); + padding_length = good & (padding_length + 1); + rec->length -= padding_length; + rec->type |= padding_length << 8; /* kludge: pass padding length */ + return constant_time_select_int(good, 1, -1); +} + +/*- + * tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC * record in |rec| in constant time and returns 1 if the padding is valid and * -1 otherwise. It also removes any explicit IV from the start of the record * without leaking any timing about whether there was enough space after the @@ -109,94 +116,92 @@ int ssl3_cbc_remove_padding(const SSL* s, * returns: * 0: (in non-constant time) if the record is publicly invalid. * 1: if the padding was valid - * -1: otherwise. */ -int tls1_cbc_remove_padding(const SSL* s, - SSL3_RECORD *rec, - unsigned block_size, - unsigned mac_size) - { - unsigned padding_length, good, to_check, i; - const unsigned overhead = 1 /* padding length byte */ + mac_size; - /* Check if version requires explicit IV */ - if (s->version >= TLS1_1_VERSION || s->version == DTLS1_BAD_VER) - { - /* These lengths are all public so we can test them in - * non-constant time. - */ - if (overhead + block_size > rec->length) - return 0; - /* We can now safely skip explicit IV */ - rec->data += block_size; - rec->input += block_size; - rec->length -= block_size; - } - else if (overhead > rec->length) - return 0; - - padding_length = rec->data[rec->length-1]; - - /* NB: if compression is in operation the first packet may not be of - * even length so the padding bug check cannot be performed. This bug - * workaround has been around since SSLeay so hopefully it is either - * fixed now or no buggy implementation supports compression [steve] - */ - if ( (s->options&SSL_OP_TLS_BLOCK_PADDING_BUG) && !s->expand) - { - /* First packet is even in size, so check */ - if ((memcmp(s->s3->read_sequence, "\0\0\0\0\0\0\0\0",8) == 0) && - !(padding_length & 1)) - { - s->s3->flags|=TLS1_FLAGS_TLS_PADDING_BUG; - } - if ((s->s3->flags & TLS1_FLAGS_TLS_PADDING_BUG) && - padding_length > 0) - { - padding_length--; - } - } - - if (EVP_CIPHER_flags(s->enc_read_ctx->cipher)&EVP_CIPH_FLAG_AEAD_CIPHER) - { - /* padding is already verified */ - rec->length -= padding_length + 1; - return 1; - } - - good = constant_time_ge(rec->length, overhead+padding_length); - /* The padding consists of a length byte at the end of the record and - * then that many bytes of padding, all with the same value as the - * length byte. Thus, with the length byte included, there are i+1 - * bytes of padding. - * - * We can't check just |padding_length+1| bytes because that leaks - * decrypted information. Therefore we always have to check the maximum - * amount of padding possible. (Again, the length of the record is - * public information so we can use it.) */ - to_check = 255; /* maximum amount of padding. */ - if (to_check > rec->length-1) - to_check = rec->length-1; - - for (i = 0; i < to_check; i++) - { - unsigned char mask = constant_time_ge_8(padding_length, i); - unsigned char b = rec->data[rec->length-1-i]; - /* The final |padding_length+1| bytes should all have the value - * |padding_length|. Therefore the XOR should be zero. */ - good &= ~(mask&(padding_length ^ b)); - } - - /* If any of the final |padding_length+1| bytes had the wrong value, - * one or more of the lower eight bits of |good| will be cleared. - */ - good = constant_time_eq(0xff, good & 0xff); - padding_length = good & (padding_length+1); - rec->length -= padding_length; - rec->type |= padding_length<<8; /* kludge: pass padding length */ - - return constant_time_select_int(good, 1, -1); - } - -/* ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in + * -1: otherwise. + */ +int tls1_cbc_remove_padding(const SSL *s, + SSL3_RECORD *rec, + unsigned block_size, unsigned mac_size) +{ + unsigned padding_length, good, to_check, i; + const unsigned overhead = 1 /* padding length byte */ + mac_size; + /* Check if version requires explicit IV */ + if (s->version >= TLS1_1_VERSION || s->version == DTLS1_BAD_VER) { + /* + * These lengths are all public so we can test them in non-constant + * time. + */ + if (overhead + block_size > rec->length) + return 0; + /* We can now safely skip explicit IV */ + rec->data += block_size; + rec->input += block_size; + rec->length -= block_size; + } else if (overhead > rec->length) + return 0; + + padding_length = rec->data[rec->length - 1]; + + /* + * NB: if compression is in operation the first packet may not be of even + * length so the padding bug check cannot be performed. This bug + * workaround has been around since SSLeay so hopefully it is either + * fixed now or no buggy implementation supports compression [steve] + */ + if ((s->options & SSL_OP_TLS_BLOCK_PADDING_BUG) && !s->expand) { + /* First packet is even in size, so check */ + if ((memcmp(s->s3->read_sequence, "\0\0\0\0\0\0\0\0", 8) == 0) && + !(padding_length & 1)) { + s->s3->flags |= TLS1_FLAGS_TLS_PADDING_BUG; + } + if ((s->s3->flags & TLS1_FLAGS_TLS_PADDING_BUG) && padding_length > 0) { + padding_length--; + } + } + + if (EVP_CIPHER_flags(s->enc_read_ctx->cipher) & EVP_CIPH_FLAG_AEAD_CIPHER) { + /* padding is already verified */ + rec->length -= padding_length + 1; + return 1; + } + + good = constant_time_ge(rec->length, overhead + padding_length); + /* + * The padding consists of a length byte at the end of the record and + * then that many bytes of padding, all with the same value as the length + * byte. Thus, with the length byte included, there are i+1 bytes of + * padding. We can't check just |padding_length+1| bytes because that + * leaks decrypted information. Therefore we always have to check the + * maximum amount of padding possible. (Again, the length of the record + * is public information so we can use it.) + */ + to_check = 255; /* maximum amount of padding. */ + if (to_check > rec->length - 1) + to_check = rec->length - 1; + + for (i = 0; i < to_check; i++) { + unsigned char mask = constant_time_ge_8(padding_length, i); + unsigned char b = rec->data[rec->length - 1 - i]; + /* + * The final |padding_length+1| bytes should all have the value + * |padding_length|. Therefore the XOR should be zero. + */ + good &= ~(mask & (padding_length ^ b)); + } + + /* + * If any of the final |padding_length+1| bytes had the wrong value, one + * or more of the lower eight bits of |good| will be cleared. + */ + good = constant_time_eq(0xff, good & 0xff); + padding_length = good & (padding_length + 1); + rec->length -= padding_length; + rec->type |= padding_length << 8; /* kludge: pass padding length */ + + return constant_time_select_int(good, 1, -1); +} + +/*- + * ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in * constant time (independent of the concrete value of rec->length, which may * vary within a 256-byte window). * @@ -215,170 +220,179 @@ int tls1_cbc_remove_padding(const SSL* s, */ #define CBC_MAC_ROTATE_IN_PLACE -void ssl3_cbc_copy_mac(unsigned char* out, - const SSL3_RECORD *rec, - unsigned md_size,unsigned orig_len) - { +void ssl3_cbc_copy_mac(unsigned char *out, + const SSL3_RECORD *rec, + unsigned md_size, unsigned orig_len) +{ #if defined(CBC_MAC_ROTATE_IN_PLACE) - unsigned char rotated_mac_buf[64+EVP_MAX_MD_SIZE]; - unsigned char *rotated_mac; + unsigned char rotated_mac_buf[64 + EVP_MAX_MD_SIZE]; + unsigned char *rotated_mac; #else - unsigned char rotated_mac[EVP_MAX_MD_SIZE]; + unsigned char rotated_mac[EVP_MAX_MD_SIZE]; #endif - /* mac_end is the index of |rec->data| just after the end of the MAC. */ - unsigned mac_end = rec->length; - unsigned mac_start = mac_end - md_size; - /* scan_start contains the number of bytes that we can ignore because - * the MAC's position can only vary by 255 bytes. */ - unsigned scan_start = 0; - unsigned i, j; - unsigned div_spoiler; - unsigned rotate_offset; - - OPENSSL_assert(orig_len >= md_size); - OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); + /* + * mac_end is the index of |rec->data| just after the end of the MAC. + */ + unsigned mac_end = rec->length; + unsigned mac_start = mac_end - md_size; + /* + * scan_start contains the number of bytes that we can ignore because the + * MAC's position can only vary by 255 bytes. + */ + unsigned scan_start = 0; + unsigned i, j; + unsigned div_spoiler; + unsigned rotate_offset; + + OPENSSL_assert(orig_len >= md_size); + OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); #if defined(CBC_MAC_ROTATE_IN_PLACE) - rotated_mac = rotated_mac_buf + ((0-(size_t)rotated_mac_buf)&63); + rotated_mac = rotated_mac_buf + ((0 - (size_t)rotated_mac_buf) & 63); #endif - /* This information is public so it's safe to branch based on it. */ - if (orig_len > md_size + 255 + 1) - scan_start = orig_len - (md_size + 255 + 1); - /* div_spoiler contains a multiple of md_size that is used to cause the - * modulo operation to be constant time. Without this, the time varies - * based on the amount of padding when running on Intel chips at least. - * - * The aim of right-shifting md_size is so that the compiler doesn't - * figure out that it can remove div_spoiler as that would require it - * to prove that md_size is always even, which I hope is beyond it. */ - div_spoiler = md_size >> 1; - div_spoiler <<= (sizeof(div_spoiler)-1)*8; - rotate_offset = (div_spoiler + mac_start - scan_start) % md_size; - - memset(rotated_mac, 0, md_size); - for (i = scan_start, j = 0; i < orig_len; i++) - { - unsigned char mac_started = constant_time_ge_8(i, mac_start); - unsigned char mac_ended = constant_time_ge_8(i, mac_end); - unsigned char b = rec->data[i]; - rotated_mac[j++] |= b & mac_started & ~mac_ended; - j &= constant_time_lt(j,md_size); - } - - /* Now rotate the MAC */ + /* This information is public so it's safe to branch based on it. */ + if (orig_len > md_size + 255 + 1) + scan_start = orig_len - (md_size + 255 + 1); + /* + * div_spoiler contains a multiple of md_size that is used to cause the + * modulo operation to be constant time. Without this, the time varies + * based on the amount of padding when running on Intel chips at least. + * The aim of right-shifting md_size is so that the compiler doesn't + * figure out that it can remove div_spoiler as that would require it to + * prove that md_size is always even, which I hope is beyond it. + */ + div_spoiler = md_size >> 1; + div_spoiler <<= (sizeof(div_spoiler) - 1) * 8; + rotate_offset = (div_spoiler + mac_start - scan_start) % md_size; + + memset(rotated_mac, 0, md_size); + for (i = scan_start, j = 0; i < orig_len; i++) { + unsigned char mac_started = constant_time_ge_8(i, mac_start); + unsigned char mac_ended = constant_time_ge_8(i, mac_end); + unsigned char b = rec->data[i]; + rotated_mac[j++] |= b & mac_started & ~mac_ended; + j &= constant_time_lt(j, md_size); + } + + /* Now rotate the MAC */ #if defined(CBC_MAC_ROTATE_IN_PLACE) - j = 0; - for (i = 0; i < md_size; i++) - { - /* in case cache-line is 32 bytes, touch second line */ - ((volatile unsigned char *)rotated_mac)[rotate_offset^32]; - out[j++] = rotated_mac[rotate_offset++]; - rotate_offset &= constant_time_lt(rotate_offset,md_size); - } + j = 0; + for (i = 0; i < md_size; i++) { + /* in case cache-line is 32 bytes, touch second line */ + ((volatile unsigned char *)rotated_mac)[rotate_offset ^ 32]; + out[j++] = rotated_mac[rotate_offset++]; + rotate_offset &= constant_time_lt(rotate_offset, md_size); + } #else - memset(out, 0, md_size); - rotate_offset = md_size - rotate_offset; - rotate_offset &= constant_time_lt(rotate_offset,md_size); - for (i = 0; i < md_size; i++) - { - for (j = 0; j < md_size; j++) - out[j] |= rotated_mac[i] & constant_time_eq_8(j, rotate_offset); - rotate_offset++; - rotate_offset &= constant_time_lt(rotate_offset,md_size); - } + memset(out, 0, md_size); + rotate_offset = md_size - rotate_offset; + rotate_offset &= constant_time_lt(rotate_offset, md_size); + for (i = 0; i < md_size; i++) { + for (j = 0; j < md_size; j++) + out[j] |= rotated_mac[i] & constant_time_eq_8(j, rotate_offset); + rotate_offset++; + rotate_offset &= constant_time_lt(rotate_offset, md_size); + } #endif - } +} -/* u32toLE serialises an unsigned, 32-bit number (n) as four bytes at (p) in - * little-endian order. The value of p is advanced by four. */ +/* + * u32toLE serialises an unsigned, 32-bit number (n) as four bytes at (p) in + * little-endian order. The value of p is advanced by four. + */ #define u32toLE(n, p) \ - (*((p)++)=(unsigned char)(n), \ - *((p)++)=(unsigned char)(n>>8), \ - *((p)++)=(unsigned char)(n>>16), \ - *((p)++)=(unsigned char)(n>>24)) - -/* These functions serialize the state of a hash and thus perform the standard - * "final" operation without adding the padding and length that such a function - * typically does. */ -static void tls1_md5_final_raw(void* ctx, unsigned char *md_out) - { - MD5_CTX *md5 = ctx; - u32toLE(md5->A, md_out); - u32toLE(md5->B, md_out); - u32toLE(md5->C, md_out); - u32toLE(md5->D, md_out); - } - -static void tls1_sha1_final_raw(void* ctx, unsigned char *md_out) - { - SHA_CTX *sha1 = ctx; - l2n(sha1->h0, md_out); - l2n(sha1->h1, md_out); - l2n(sha1->h2, md_out); - l2n(sha1->h3, md_out); - l2n(sha1->h4, md_out); - } + (*((p)++)=(unsigned char)(n), \ + *((p)++)=(unsigned char)(n>>8), \ + *((p)++)=(unsigned char)(n>>16), \ + *((p)++)=(unsigned char)(n>>24)) + +/* + * These functions serialize the state of a hash and thus perform the + * standard "final" operation without adding the padding and length that such + * a function typically does. + */ +static void tls1_md5_final_raw(void *ctx, unsigned char *md_out) +{ + MD5_CTX *md5 = ctx; + u32toLE(md5->A, md_out); + u32toLE(md5->B, md_out); + u32toLE(md5->C, md_out); + u32toLE(md5->D, md_out); +} + +static void tls1_sha1_final_raw(void *ctx, unsigned char *md_out) +{ + SHA_CTX *sha1 = ctx; + l2n(sha1->h0, md_out); + l2n(sha1->h1, md_out); + l2n(sha1->h2, md_out); + l2n(sha1->h3, md_out); + l2n(sha1->h4, md_out); +} + #define LARGEST_DIGEST_CTX SHA_CTX #ifndef OPENSSL_NO_SHA256 -static void tls1_sha256_final_raw(void* ctx, unsigned char *md_out) - { - SHA256_CTX *sha256 = ctx; - unsigned i; - - for (i = 0; i < 8; i++) - { - l2n(sha256->h[i], md_out); - } - } -#undef LARGEST_DIGEST_CTX -#define LARGEST_DIGEST_CTX SHA256_CTX +static void tls1_sha256_final_raw(void *ctx, unsigned char *md_out) +{ + SHA256_CTX *sha256 = ctx; + unsigned i; + + for (i = 0; i < 8; i++) { + l2n(sha256->h[i], md_out); + } +} + +# undef LARGEST_DIGEST_CTX +# define LARGEST_DIGEST_CTX SHA256_CTX #endif #ifndef OPENSSL_NO_SHA512 -static void tls1_sha512_final_raw(void* ctx, unsigned char *md_out) - { - SHA512_CTX *sha512 = ctx; - unsigned i; - - for (i = 0; i < 8; i++) - { - l2n8(sha512->h[i], md_out); - } - } -#undef LARGEST_DIGEST_CTX -#define LARGEST_DIGEST_CTX SHA512_CTX +static void tls1_sha512_final_raw(void *ctx, unsigned char *md_out) +{ + SHA512_CTX *sha512 = ctx; + unsigned i; + + for (i = 0; i < 8; i++) { + l2n8(sha512->h[i], md_out); + } +} + +# undef LARGEST_DIGEST_CTX +# define LARGEST_DIGEST_CTX SHA512_CTX #endif -/* ssl3_cbc_record_digest_supported returns 1 iff |ctx| uses a hash function - * which ssl3_cbc_digest_record supports. */ +/* + * ssl3_cbc_record_digest_supported returns 1 iff |ctx| uses a hash function + * which ssl3_cbc_digest_record supports. + */ char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) - { +{ #ifdef OPENSSL_FIPS - if (FIPS_mode()) - return 0; + if (FIPS_mode()) + return 0; #endif - switch (EVP_MD_CTX_type(ctx)) - { - case NID_md5: - case NID_sha1: + switch (EVP_MD_CTX_type(ctx)) { + case NID_md5: + case NID_sha1: #ifndef OPENSSL_NO_SHA256 - case NID_sha224: - case NID_sha256: + case NID_sha224: + case NID_sha256: #endif #ifndef OPENSSL_NO_SHA512 - case NID_sha384: - case NID_sha512: + case NID_sha384: + case NID_sha512: #endif - return 1; - default: - return 0; - } - } - -/* ssl3_cbc_digest_record computes the MAC of a decrypted, padded SSLv3/TLS + return 1; + default: + return 0; + } +} + +/*- + * ssl3_cbc_digest_record computes the MAC of a decrypted, padded SSLv3/TLS * record. * * ctx: the EVP_MD_CTX from which we take the hash function. @@ -396,360 +410,386 @@ char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) * On entry: by virtue of having been through one of the remove_padding * functions, above, we know that data_plus_mac_size is large enough to contain * a padding byte and MAC. (If the padding was invalid, it might contain the - * padding too. ) */ -void ssl3_cbc_digest_record( - const EVP_MD_CTX *ctx, - unsigned char* md_out, - size_t* md_out_size, - const unsigned char header[13], - const unsigned char *data, - size_t data_plus_mac_size, - size_t data_plus_mac_plus_padding_size, - const unsigned char *mac_secret, - unsigned mac_secret_length, - char is_sslv3) - { - union { double align; - unsigned char c[sizeof(LARGEST_DIGEST_CTX)]; } md_state; - void (*md_final_raw)(void *ctx, unsigned char *md_out); - void (*md_transform)(void *ctx, const unsigned char *block); - unsigned md_size, md_block_size = 64; - unsigned sslv3_pad_length = 40, header_length, variance_blocks, - len, max_mac_bytes, num_blocks, - num_starting_blocks, k, mac_end_offset, c, index_a, index_b; - unsigned int bits; /* at most 18 bits */ - unsigned char length_bytes[MAX_HASH_BIT_COUNT_BYTES]; - /* hmac_pad is the masked HMAC key. */ - unsigned char hmac_pad[MAX_HASH_BLOCK_SIZE]; - unsigned char first_block[MAX_HASH_BLOCK_SIZE]; - unsigned char mac_out[EVP_MAX_MD_SIZE]; - unsigned i, j, md_out_size_u; - EVP_MD_CTX md_ctx; - /* mdLengthSize is the number of bytes in the length field that terminates - * the hash. */ - unsigned md_length_size = 8; - char length_is_big_endian = 1; - - /* This is a, hopefully redundant, check that allows us to forget about - * many possible overflows later in this function. */ - OPENSSL_assert(data_plus_mac_plus_padding_size < 1024*1024); - - switch (EVP_MD_CTX_type(ctx)) - { - case NID_md5: - MD5_Init((MD5_CTX*)md_state.c); - md_final_raw = tls1_md5_final_raw; - md_transform = (void(*)(void *ctx, const unsigned char *block)) MD5_Transform; - md_size = 16; - sslv3_pad_length = 48; - length_is_big_endian = 0; - break; - case NID_sha1: - SHA1_Init((SHA_CTX*)md_state.c); - md_final_raw = tls1_sha1_final_raw; - md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA1_Transform; - md_size = 20; - break; + * padding too. ) + */ +void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, + unsigned char *md_out, + size_t *md_out_size, + const unsigned char header[13], + const unsigned char *data, + size_t data_plus_mac_size, + size_t data_plus_mac_plus_padding_size, + const unsigned char *mac_secret, + unsigned mac_secret_length, char is_sslv3) +{ + union { + double align; + unsigned char c[sizeof(LARGEST_DIGEST_CTX)]; + } md_state; + void (*md_final_raw) (void *ctx, unsigned char *md_out); + void (*md_transform) (void *ctx, const unsigned char *block); + unsigned md_size, md_block_size = 64; + unsigned sslv3_pad_length = 40, header_length, variance_blocks, + len, max_mac_bytes, num_blocks, + num_starting_blocks, k, mac_end_offset, c, index_a, index_b; + unsigned int bits; /* at most 18 bits */ + unsigned char length_bytes[MAX_HASH_BIT_COUNT_BYTES]; + /* hmac_pad is the masked HMAC key. */ + unsigned char hmac_pad[MAX_HASH_BLOCK_SIZE]; + unsigned char first_block[MAX_HASH_BLOCK_SIZE]; + unsigned char mac_out[EVP_MAX_MD_SIZE]; + unsigned i, j, md_out_size_u; + EVP_MD_CTX md_ctx; + /* + * mdLengthSize is the number of bytes in the length field that + * terminates * the hash. + */ + unsigned md_length_size = 8; + char length_is_big_endian = 1; + + /* + * This is a, hopefully redundant, check that allows us to forget about + * many possible overflows later in this function. + */ + OPENSSL_assert(data_plus_mac_plus_padding_size < 1024 * 1024); + + switch (EVP_MD_CTX_type(ctx)) { + case NID_md5: + MD5_Init((MD5_CTX *)md_state.c); + md_final_raw = tls1_md5_final_raw; + md_transform = + (void (*)(void *ctx, const unsigned char *block))MD5_Transform; + md_size = 16; + sslv3_pad_length = 48; + length_is_big_endian = 0; + break; + case NID_sha1: + SHA1_Init((SHA_CTX *)md_state.c); + md_final_raw = tls1_sha1_final_raw; + md_transform = + (void (*)(void *ctx, const unsigned char *block))SHA1_Transform; + md_size = 20; + break; #ifndef OPENSSL_NO_SHA256 - case NID_sha224: - SHA224_Init((SHA256_CTX*)md_state.c); - md_final_raw = tls1_sha256_final_raw; - md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA256_Transform; - md_size = 224/8; - break; - case NID_sha256: - SHA256_Init((SHA256_CTX*)md_state.c); - md_final_raw = tls1_sha256_final_raw; - md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA256_Transform; - md_size = 32; - break; + case NID_sha224: + SHA224_Init((SHA256_CTX *)md_state.c); + md_final_raw = tls1_sha256_final_raw; + md_transform = + (void (*)(void *ctx, const unsigned char *block))SHA256_Transform; + md_size = 224 / 8; + break; + case NID_sha256: + SHA256_Init((SHA256_CTX *)md_state.c); + md_final_raw = tls1_sha256_final_raw; + md_transform = + (void (*)(void *ctx, const unsigned char *block))SHA256_Transform; + md_size = 32; + break; #endif #ifndef OPENSSL_NO_SHA512 - case NID_sha384: - SHA384_Init((SHA512_CTX*)md_state.c); - md_final_raw = tls1_sha512_final_raw; - md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA512_Transform; - md_size = 384/8; - md_block_size = 128; - md_length_size = 16; - break; - case NID_sha512: - SHA512_Init((SHA512_CTX*)md_state.c); - md_final_raw = tls1_sha512_final_raw; - md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA512_Transform; - md_size = 64; - md_block_size = 128; - md_length_size = 16; - break; + case NID_sha384: + SHA384_Init((SHA512_CTX *)md_state.c); + md_final_raw = tls1_sha512_final_raw; + md_transform = + (void (*)(void *ctx, const unsigned char *block))SHA512_Transform; + md_size = 384 / 8; + md_block_size = 128; + md_length_size = 16; + break; + case NID_sha512: + SHA512_Init((SHA512_CTX *)md_state.c); + md_final_raw = tls1_sha512_final_raw; + md_transform = + (void (*)(void *ctx, const unsigned char *block))SHA512_Transform; + md_size = 64; + md_block_size = 128; + md_length_size = 16; + break; #endif - default: - /* ssl3_cbc_record_digest_supported should have been - * called first to check that the hash function is - * supported. */ - OPENSSL_assert(0); - if (md_out_size) - *md_out_size = -1; - return; - } - - OPENSSL_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES); - OPENSSL_assert(md_block_size <= MAX_HASH_BLOCK_SIZE); - OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); - - header_length = 13; - if (is_sslv3) - { - header_length = - mac_secret_length + - sslv3_pad_length + - 8 /* sequence number */ + - 1 /* record type */ + - 2 /* record length */; - } - - /* variance_blocks is the number of blocks of the hash that we have to - * calculate in constant time because they could be altered by the - * padding value. - * - * In SSLv3, the padding must be minimal so the end of the plaintext - * varies by, at most, 15+20 = 35 bytes. (We conservatively assume that - * the MAC size varies from 0..20 bytes.) In case the 9 bytes of hash - * termination (0x80 + 64-bit length) don't fit in the final block, we - * say that the final two blocks can vary based on the padding. - * - * TLSv1 has MACs up to 48 bytes long (SHA-384) and the padding is not - * required to be minimal. Therefore we say that the final six blocks - * can vary based on the padding. - * - * Later in the function, if the message is short and there obviously - * cannot be this many blocks then variance_blocks can be reduced. */ - variance_blocks = is_sslv3 ? 2 : 6; - /* From now on we're dealing with the MAC, which conceptually has 13 - * bytes of `header' before the start of the data (TLS) or 71/75 bytes - * (SSLv3) */ - len = data_plus_mac_plus_padding_size + header_length; - /* max_mac_bytes contains the maximum bytes of bytes in the MAC, including - * |header|, assuming that there's no padding. */ - max_mac_bytes = len - md_size - 1; - /* num_blocks is the maximum number of hash blocks. */ - num_blocks = (max_mac_bytes + 1 + md_length_size + md_block_size - 1) / md_block_size; - /* In order to calculate the MAC in constant time we have to handle - * the final blocks specially because the padding value could cause the - * end to appear somewhere in the final |variance_blocks| blocks and we - * can't leak where. However, |num_starting_blocks| worth of data can - * be hashed right away because no padding value can affect whether - * they are plaintext. */ - num_starting_blocks = 0; - /* k is the starting byte offset into the conceptual header||data where - * we start processing. */ - k = 0; - /* mac_end_offset is the index just past the end of the data to be - * MACed. */ - mac_end_offset = data_plus_mac_size + header_length - md_size; - /* c is the index of the 0x80 byte in the final hash block that - * contains application data. */ - c = mac_end_offset % md_block_size; - /* index_a is the hash block number that contains the 0x80 terminating - * value. */ - index_a = mac_end_offset / md_block_size; - /* index_b is the hash block number that contains the 64-bit hash - * length, in bits. */ - index_b = (mac_end_offset + md_length_size) / md_block_size; - /* bits is the hash-length in bits. It includes the additional hash - * block for the masked HMAC key, or whole of |header| in the case of - * SSLv3. */ - - /* For SSLv3, if we're going to have any starting blocks then we need - * at least two because the header is larger than a single block. */ - if (num_blocks > variance_blocks + (is_sslv3 ? 1 : 0)) - { - num_starting_blocks = num_blocks - variance_blocks; - k = md_block_size*num_starting_blocks; - } - - bits = 8*mac_end_offset; - if (!is_sslv3) - { - /* Compute the initial HMAC block. For SSLv3, the padding and - * secret bytes are included in |header| because they take more - * than a single block. */ - bits += 8*md_block_size; - memset(hmac_pad, 0, md_block_size); - OPENSSL_assert(mac_secret_length <= sizeof(hmac_pad)); - memcpy(hmac_pad, mac_secret, mac_secret_length); - for (i = 0; i < md_block_size; i++) - hmac_pad[i] ^= 0x36; - - md_transform(md_state.c, hmac_pad); - } - - if (length_is_big_endian) - { - memset(length_bytes,0,md_length_size-4); - length_bytes[md_length_size-4] = (unsigned char)(bits>>24); - length_bytes[md_length_size-3] = (unsigned char)(bits>>16); - length_bytes[md_length_size-2] = (unsigned char)(bits>>8); - length_bytes[md_length_size-1] = (unsigned char)bits; - } - else - { - memset(length_bytes,0,md_length_size); - length_bytes[md_length_size-5] = (unsigned char)(bits>>24); - length_bytes[md_length_size-6] = (unsigned char)(bits>>16); - length_bytes[md_length_size-7] = (unsigned char)(bits>>8); - length_bytes[md_length_size-8] = (unsigned char)bits; - } - - if (k > 0) - { - if (is_sslv3) - { - /* The SSLv3 header is larger than a single block. - * overhang is the number of bytes beyond a single - * block that the header consumes: either 7 bytes - * (SHA1) or 11 bytes (MD5). */ - unsigned overhang = header_length-md_block_size; - md_transform(md_state.c, header); - memcpy(first_block, header + md_block_size, overhang); - memcpy(first_block + overhang, data, md_block_size-overhang); - md_transform(md_state.c, first_block); - for (i = 1; i < k/md_block_size - 1; i++) - md_transform(md_state.c, data + md_block_size*i - overhang); - } - else - { - /* k is a multiple of md_block_size. */ - memcpy(first_block, header, 13); - memcpy(first_block+13, data, md_block_size-13); - md_transform(md_state.c, first_block); - for (i = 1; i < k/md_block_size; i++) - md_transform(md_state.c, data + md_block_size*i - 13); - } - } - - memset(mac_out, 0, sizeof(mac_out)); - - /* We now process the final hash blocks. For each block, we construct - * it in constant time. If the |i==index_a| then we'll include the 0x80 - * bytes and zero pad etc. For each block we selectively copy it, in - * constant time, to |mac_out|. */ - for (i = num_starting_blocks; i <= num_starting_blocks+variance_blocks; i++) - { - unsigned char block[MAX_HASH_BLOCK_SIZE]; - unsigned char is_block_a = constant_time_eq_8(i, index_a); - unsigned char is_block_b = constant_time_eq_8(i, index_b); - for (j = 0; j < md_block_size; j++) - { - unsigned char b = 0, is_past_c, is_past_cp1; - if (k < header_length) - b = header[k]; - else if (k < data_plus_mac_plus_padding_size + header_length) - b = data[k-header_length]; - k++; - - is_past_c = is_block_a & constant_time_ge_8(j, c); - is_past_cp1 = is_block_a & constant_time_ge_8(j, c+1); - /* If this is the block containing the end of the - * application data, and we are at the offset for the - * 0x80 value, then overwrite b with 0x80. */ - b = constant_time_select_8(is_past_c, 0x80, b); - /* If this the the block containing the end of the - * application data and we're past the 0x80 value then - * just write zero. */ - b = b&~is_past_cp1; - /* If this is index_b (the final block), but not - * index_a (the end of the data), then the 64-bit - * length didn't fit into index_a and we're having to - * add an extra block of zeros. */ - b &= ~is_block_b | is_block_a; - - /* The final bytes of one of the blocks contains the - * length. */ - if (j >= md_block_size - md_length_size) - { - /* If this is index_b, write a length byte. */ - b = constant_time_select_8( - is_block_b, length_bytes[j-(md_block_size-md_length_size)], b); - } - block[j] = b; - } - - md_transform(md_state.c, block); - md_final_raw(md_state.c, block); - /* If this is index_b, copy the hash value to |mac_out|. */ - for (j = 0; j < md_size; j++) - mac_out[j] |= block[j]&is_block_b; - } - - EVP_MD_CTX_init(&md_ctx); - EVP_DigestInit_ex(&md_ctx, ctx->digest, NULL /* engine */); - if (is_sslv3) - { - /* We repurpose |hmac_pad| to contain the SSLv3 pad2 block. */ - memset(hmac_pad, 0x5c, sslv3_pad_length); - - EVP_DigestUpdate(&md_ctx, mac_secret, mac_secret_length); - EVP_DigestUpdate(&md_ctx, hmac_pad, sslv3_pad_length); - EVP_DigestUpdate(&md_ctx, mac_out, md_size); - } - else - { - /* Complete the HMAC in the standard manner. */ - for (i = 0; i < md_block_size; i++) - hmac_pad[i] ^= 0x6a; - - EVP_DigestUpdate(&md_ctx, hmac_pad, md_block_size); - EVP_DigestUpdate(&md_ctx, mac_out, md_size); - } - EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u); - if (md_out_size) - *md_out_size = md_out_size_u; - EVP_MD_CTX_cleanup(&md_ctx); - } + default: + /* + * ssl3_cbc_record_digest_supported should have been called first to + * check that the hash function is supported. + */ + OPENSSL_assert(0); + if (md_out_size) + *md_out_size = -1; + return; + } + + OPENSSL_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES); + OPENSSL_assert(md_block_size <= MAX_HASH_BLOCK_SIZE); + OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); + + header_length = 13; + if (is_sslv3) { + header_length = mac_secret_length + sslv3_pad_length + 8 /* sequence + * number */ + + 1 /* record type */ + + 2 /* record length */ ; + } + + /* + * variance_blocks is the number of blocks of the hash that we have to + * calculate in constant time because they could be altered by the + * padding value. In SSLv3, the padding must be minimal so the end of + * the plaintext varies by, at most, 15+20 = 35 bytes. (We conservatively + * assume that the MAC size varies from 0..20 bytes.) In case the 9 bytes + * of hash termination (0x80 + 64-bit length) don't fit in the final + * block, we say that the final two blocks can vary based on the padding. + * TLSv1 has MACs up to 48 bytes long (SHA-384) and the padding is not + * required to be minimal. Therefore we say that the final six blocks can + * vary based on the padding. Later in the function, if the message is + * short and there obviously cannot be this many blocks then + * variance_blocks can be reduced. + */ + variance_blocks = is_sslv3 ? 2 : 6; + /* + * From now on we're dealing with the MAC, which conceptually has 13 + * bytes of `header' before the start of the data (TLS) or 71/75 bytes + * (SSLv3) + */ + len = data_plus_mac_plus_padding_size + header_length; + /* + * max_mac_bytes contains the maximum bytes of bytes in the MAC, + * including * |header|, assuming that there's no padding. + */ + max_mac_bytes = len - md_size - 1; + /* num_blocks is the maximum number of hash blocks. */ + num_blocks = + (max_mac_bytes + 1 + md_length_size + md_block_size - + 1) / md_block_size; + /* + * In order to calculate the MAC in constant time we have to handle the + * final blocks specially because the padding value could cause the end + * to appear somewhere in the final |variance_blocks| blocks and we can't + * leak where. However, |num_starting_blocks| worth of data can be hashed + * right away because no padding value can affect whether they are + * plaintext. + */ + num_starting_blocks = 0; + /* + * k is the starting byte offset into the conceptual header||data where + * we start processing. + */ + k = 0; + /* + * mac_end_offset is the index just past the end of the data to be MACed. + */ + mac_end_offset = data_plus_mac_size + header_length - md_size; + /* + * c is the index of the 0x80 byte in the final hash block that contains + * application data. + */ + c = mac_end_offset % md_block_size; + /* + * index_a is the hash block number that contains the 0x80 terminating + * value. + */ + index_a = mac_end_offset / md_block_size; + /* + * index_b is the hash block number that contains the 64-bit hash length, + * in bits. + */ + index_b = (mac_end_offset + md_length_size) / md_block_size; + /* + * bits is the hash-length in bits. It includes the additional hash block + * for the masked HMAC key, or whole of |header| in the case of SSLv3. + */ + + /* + * For SSLv3, if we're going to have any starting blocks then we need at + * least two because the header is larger than a single block. + */ + if (num_blocks > variance_blocks + (is_sslv3 ? 1 : 0)) { + num_starting_blocks = num_blocks - variance_blocks; + k = md_block_size * num_starting_blocks; + } + + bits = 8 * mac_end_offset; + if (!is_sslv3) { + /* + * Compute the initial HMAC block. For SSLv3, the padding and secret + * bytes are included in |header| because they take more than a + * single block. + */ + bits += 8 * md_block_size; + memset(hmac_pad, 0, md_block_size); + OPENSSL_assert(mac_secret_length <= sizeof(hmac_pad)); + memcpy(hmac_pad, mac_secret, mac_secret_length); + for (i = 0; i < md_block_size; i++) + hmac_pad[i] ^= 0x36; + + md_transform(md_state.c, hmac_pad); + } + + if (length_is_big_endian) { + memset(length_bytes, 0, md_length_size - 4); + length_bytes[md_length_size - 4] = (unsigned char)(bits >> 24); + length_bytes[md_length_size - 3] = (unsigned char)(bits >> 16); + length_bytes[md_length_size - 2] = (unsigned char)(bits >> 8); + length_bytes[md_length_size - 1] = (unsigned char)bits; + } else { + memset(length_bytes, 0, md_length_size); + length_bytes[md_length_size - 5] = (unsigned char)(bits >> 24); + length_bytes[md_length_size - 6] = (unsigned char)(bits >> 16); + length_bytes[md_length_size - 7] = (unsigned char)(bits >> 8); + length_bytes[md_length_size - 8] = (unsigned char)bits; + } + + if (k > 0) { + if (is_sslv3) { + /* + * The SSLv3 header is larger than a single block. overhang is + * the number of bytes beyond a single block that the header + * consumes: either 7 bytes (SHA1) or 11 bytes (MD5). + */ + unsigned overhang = header_length - md_block_size; + md_transform(md_state.c, header); + memcpy(first_block, header + md_block_size, overhang); + memcpy(first_block + overhang, data, md_block_size - overhang); + md_transform(md_state.c, first_block); + for (i = 1; i < k / md_block_size - 1; i++) + md_transform(md_state.c, data + md_block_size * i - overhang); + } else { + /* k is a multiple of md_block_size. */ + memcpy(first_block, header, 13); + memcpy(first_block + 13, data, md_block_size - 13); + md_transform(md_state.c, first_block); + for (i = 1; i < k / md_block_size; i++) + md_transform(md_state.c, data + md_block_size * i - 13); + } + } + + memset(mac_out, 0, sizeof(mac_out)); + + /* + * We now process the final hash blocks. For each block, we construct it + * in constant time. If the |i==index_a| then we'll include the 0x80 + * bytes and zero pad etc. For each block we selectively copy it, in + * constant time, to |mac_out|. + */ + for (i = num_starting_blocks; i <= num_starting_blocks + variance_blocks; + i++) { + unsigned char block[MAX_HASH_BLOCK_SIZE]; + unsigned char is_block_a = constant_time_eq_8(i, index_a); + unsigned char is_block_b = constant_time_eq_8(i, index_b); + for (j = 0; j < md_block_size; j++) { + unsigned char b = 0, is_past_c, is_past_cp1; + if (k < header_length) + b = header[k]; + else if (k < data_plus_mac_plus_padding_size + header_length) + b = data[k - header_length]; + k++; + + is_past_c = is_block_a & constant_time_ge_8(j, c); + is_past_cp1 = is_block_a & constant_time_ge_8(j, c + 1); + /* + * If this is the block containing the end of the application + * data, and we are at the offset for the 0x80 value, then + * overwrite b with 0x80. + */ + b = constant_time_select_8(is_past_c, 0x80, b); + /* + * If this the the block containing the end of the application + * data and we're past the 0x80 value then just write zero. + */ + b = b & ~is_past_cp1; + /* + * If this is index_b (the final block), but not index_a (the end + * of the data), then the 64-bit length didn't fit into index_a + * and we're having to add an extra block of zeros. + */ + b &= ~is_block_b | is_block_a; + + /* + * The final bytes of one of the blocks contains the length. + */ + if (j >= md_block_size - md_length_size) { + /* If this is index_b, write a length byte. */ + b = constant_time_select_8(is_block_b, + length_bytes[j - + (md_block_size - + md_length_size)], b); + } + block[j] = b; + } + + md_transform(md_state.c, block); + md_final_raw(md_state.c, block); + /* If this is index_b, copy the hash value to |mac_out|. */ + for (j = 0; j < md_size; j++) + mac_out[j] |= block[j] & is_block_b; + } + + EVP_MD_CTX_init(&md_ctx); + EVP_DigestInit_ex(&md_ctx, ctx->digest, NULL /* engine */ ); + if (is_sslv3) { + /* We repurpose |hmac_pad| to contain the SSLv3 pad2 block. */ + memset(hmac_pad, 0x5c, sslv3_pad_length); + + EVP_DigestUpdate(&md_ctx, mac_secret, mac_secret_length); + EVP_DigestUpdate(&md_ctx, hmac_pad, sslv3_pad_length); + EVP_DigestUpdate(&md_ctx, mac_out, md_size); + } else { + /* Complete the HMAC in the standard manner. */ + for (i = 0; i < md_block_size; i++) + hmac_pad[i] ^= 0x6a; + + EVP_DigestUpdate(&md_ctx, hmac_pad, md_block_size); + EVP_DigestUpdate(&md_ctx, mac_out, md_size); + } + EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u); + if (md_out_size) + *md_out_size = md_out_size_u; + EVP_MD_CTX_cleanup(&md_ctx); +} #ifdef OPENSSL_FIPS -/* Due to the need to use EVP in FIPS mode we can't reimplement digests but - * we can ensure the number of blocks processed is equal for all cases - * by digesting additional data. +/* + * Due to the need to use EVP in FIPS mode we can't reimplement digests but + * we can ensure the number of blocks processed is equal for all cases by + * digesting additional data. */ -void tls_fips_digest_extra( - const EVP_CIPHER_CTX *cipher_ctx, EVP_MD_CTX *mac_ctx, - const unsigned char *data, size_t data_len, size_t orig_len) - { - size_t block_size, digest_pad, blocks_data, blocks_orig; - if (EVP_CIPHER_CTX_mode(cipher_ctx) != EVP_CIPH_CBC_MODE) - return; - block_size = EVP_MD_CTX_block_size(mac_ctx); - /* We are in FIPS mode if we get this far so we know we have only SHA* - * digests and TLS to deal with. - * Minimum digest padding length is 17 for SHA384/SHA512 and 9 - * otherwise. - * Additional header is 13 bytes. To get the number of digest blocks - * processed round up the amount of data plus padding to the nearest - * block length. Block length is 128 for SHA384/SHA512 and 64 otherwise. - * So we have: - * blocks = (payload_len + digest_pad + 13 + block_size - 1)/block_size - * equivalently: - * blocks = (payload_len + digest_pad + 12)/block_size + 1 - * HMAC adds a constant overhead. - * We're ultimately only interested in differences so this becomes - * blocks = (payload_len + 29)/128 - * for SHA384/SHA512 and - * blocks = (payload_len + 21)/64 - * otherwise. - */ - digest_pad = block_size == 64 ? 21 : 29; - blocks_orig = (orig_len + digest_pad)/block_size; - blocks_data = (data_len + digest_pad)/block_size; - /* MAC enough blocks to make up the difference between the original - * and actual lengths plus one extra block to ensure this is never a - * no op. The "data" pointer should always have enough space to - * perform this operation as it is large enough for a maximum - * length TLS buffer. - */ - EVP_DigestSignUpdate(mac_ctx, data, - (blocks_orig - blocks_data + 1) * block_size); - } +void tls_fips_digest_extra(const EVP_CIPHER_CTX *cipher_ctx, + EVP_MD_CTX *mac_ctx, const unsigned char *data, + size_t data_len, size_t orig_len) +{ + size_t block_size, digest_pad, blocks_data, blocks_orig; + if (EVP_CIPHER_CTX_mode(cipher_ctx) != EVP_CIPH_CBC_MODE) + return; + block_size = EVP_MD_CTX_block_size(mac_ctx); + /*- + * We are in FIPS mode if we get this far so we know we have only SHA* + * digests and TLS to deal with. + * Minimum digest padding length is 17 for SHA384/SHA512 and 9 + * otherwise. + * Additional header is 13 bytes. To get the number of digest blocks + * processed round up the amount of data plus padding to the nearest + * block length. Block length is 128 for SHA384/SHA512 and 64 otherwise. + * So we have: + * blocks = (payload_len + digest_pad + 13 + block_size - 1)/block_size + * equivalently: + * blocks = (payload_len + digest_pad + 12)/block_size + 1 + * HMAC adds a constant overhead. + * We're ultimately only interested in differences so this becomes + * blocks = (payload_len + 29)/128 + * for SHA384/SHA512 and + * blocks = (payload_len + 21)/64 + * otherwise. + */ + digest_pad = block_size == 64 ? 21 : 29; + blocks_orig = (orig_len + digest_pad) / block_size; + blocks_data = (data_len + digest_pad) / block_size; + /* + * MAC enough blocks to make up the difference between the original and + * actual lengths plus one extra block to ensure this is never a no op. + * The "data" pointer should always have enough space to perform this + * operation as it is large enough for a maximum length TLS buffer. + */ + EVP_DigestSignUpdate(mac_ctx, data, + (blocks_orig - blocks_data + 1) * block_size); +} #endif |