X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=ssl%2Fs3_cbc.c;h=73e12b6799b3e95d02773ac772f7a81225666b7c;hp=e9b112c1b589510aff18ef39cace825b4529ce2b;hb=5f8e9a477a18551052f2019c1f374061acbaa5e6;hpb=a693ead6dc75455f7f5bbbd631b3a0e7ee457965 diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c index e9b112c1b5..73e12b6799 100644 --- a/ssl/s3_cbc.c +++ b/ssl/s3_cbc.c @@ -53,8 +53,6 @@ * */ -#include - #include "ssl_locl.h" #include @@ -78,6 +76,13 @@ #define DUPLICATE_MSB_TO_ALL(x) ( (unsigned)( (int)(x) >> (sizeof(int)*8-1) ) ) #define DUPLICATE_MSB_TO_ALL_8(x) ((unsigned char)(DUPLICATE_MSB_TO_ALL(x))) +/* constant_time_lt returns 0xff if a=b and 0x00 otherwise. */ static unsigned constant_time_ge(unsigned a, unsigned b) { @@ -86,7 +91,7 @@ static unsigned constant_time_ge(unsigned a, unsigned b) } /* constant_time_eq_8 returns 0xff if a==b and 0x00 otherwise. */ -static unsigned char constant_time_eq_8(unsigned char a, unsigned char b) +static unsigned char constant_time_eq_8(unsigned a, unsigned b) { unsigned c = a ^ b; c--; @@ -139,15 +144,22 @@ int tls1_cbc_remove_padding(const SSL* s, unsigned mac_size) { unsigned padding_length, good, to_check, i; - const char has_explicit_iv = - s->version >= TLS1_1_VERSION || s->version == DTLS1_VERSION; - const unsigned overhead = 1 /* padding length byte */ + - mac_size + - (has_explicit_iv ? block_size : 0); - - /* These lengths are all public so we can test them in non-constant - * time. */ - if (overhead > rec->length) + const unsigned overhead = 1 /* padding length byte */ + mac_size; + /* Check if version requires explicit IV */ + if (SSL_USE_EXPLICIT_IV(s)) + { + /* 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; + rec->orig_len -= block_size; + } + else if (overhead > rec->length) return 0; padding_length = rec->data[rec->length-1]; @@ -172,6 +184,13 @@ int tls1_cbc_remove_padding(const SSL* s, } } + 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 @@ -207,29 +226,9 @@ int tls1_cbc_remove_padding(const SSL* s, rec->length -= good & (padding_length+1); - /* We can always safely skip the explicit IV. We check at the beginning - * of this function that the record has at least enough space for the - * IV, MAC and padding length byte. (These can be checked in - * non-constant time because it's all public information.) So, if the - * padding was invalid, then we didn't change |rec->length| and this is - * safe. If the padding was valid then we know that we have at least - * overhead+padding_length bytes of space and so this is still safe - * because overhead accounts for the explicit IV. */ - if (has_explicit_iv) - { - rec->data += block_size; - rec->input += block_size; - rec->length -= block_size; - rec->orig_len -= block_size; - } - return (int)((good & 1) | (~good & -1)); } -#if defined(_M_AMD64) || defined(__x86_64__) -#define CBC_MAC_ROTATE_IN_PLACE -#endif - /* 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). @@ -243,15 +242,18 @@ int tls1_cbc_remove_padding(const SSL* s, * * If CBC_MAC_ROTATE_IN_PLACE is defined then the rotation is performed with * variable accesses in a 64-byte-aligned buffer. Assuming that this fits into - * a single cache-line, then the variable memory accesses don't actually affect - * the timing. This has been tested to be true on Intel amd64 chips. + * a single or pair of cache-lines, then the variable memory accesses don't + * actually affect the timing. CPUs with smaller cache-lines [if any] are + * not multi-core and are not considered vulnerable to cache-timing attacks. */ +#define CBC_MAC_ROTATE_IN_PLACE + void ssl3_cbc_copy_mac(unsigned char* out, const SSL3_RECORD *rec, unsigned md_size) { #if defined(CBC_MAC_ROTATE_IN_PLACE) - unsigned char rotated_mac_buf[EVP_MAX_MD_SIZE*2]; + unsigned char rotated_mac_buf[64+EVP_MAX_MD_SIZE]; unsigned char *rotated_mac; #else unsigned char rotated_mac[EVP_MAX_MD_SIZE]; @@ -271,7 +273,7 @@ void ssl3_cbc_copy_mac(unsigned char* out, OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); #if defined(CBC_MAC_ROTATE_IN_PLACE) - rotated_mac = (unsigned char*) (((intptr_t)(rotated_mac_buf + 64)) & ~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. */ @@ -289,16 +291,13 @@ void ssl3_cbc_copy_mac(unsigned char* out, rotate_offset = (div_spoiler + mac_start - scan_start) % md_size; memset(rotated_mac, 0, md_size); - for (i = scan_start; i < rec->orig_len;) + for (i = scan_start, j = 0; i < rec->orig_len; i++) { - for (j = 0; j < md_size && i < rec->orig_len; i++, j++) - { - unsigned char mac_started = constant_time_ge(i, mac_start); - unsigned char mac_ended = constant_time_ge(i, mac_end); - unsigned char b = 0; - b = rec->data[i]; - rotated_mac[j] |= b & mac_started & ~mac_ended; - } + unsigned char mac_started = constant_time_ge(i, mac_start); + unsigned char mac_ended = constant_time_ge(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 */ @@ -306,30 +305,43 @@ void ssl3_cbc_copy_mac(unsigned char* out, j = 0; for (i = 0; i < md_size; i++) { - unsigned char offset = (div_spoiler + rotate_offset + i) % md_size; - out[j++] = rotated_mac[offset]; + /* 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++) { - unsigned char offset = (div_spoiler + md_size - rotate_offset + i) % md_size; for (j = 0; j < md_size; j++) - out[j] |= rotated_mac[i] & constant_time_eq_8(j, offset); + 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. */ +#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; - l2n(md5->A, md_out); - l2n(md5->B, md_out); - l2n(md5->C, md_out); - l2n(md5->D, md_out); + 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) @@ -341,7 +353,9 @@ static void tls1_sha1_final_raw(void* ctx, unsigned char *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; @@ -352,7 +366,11 @@ static void tls1_sha256_final_raw(void* ctx, unsigned char *md_out) 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; @@ -363,19 +381,30 @@ static void tls1_sha512_final_raw(void* ctx, unsigned char *md_out) 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. */ char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) { - switch (ctx->digest->type) +#ifdef OPENSSL_FIPS + if (FIPS_mode()) + return 0; +#endif + switch (EVP_MD_CTX_type(ctx)) { case NID_md5: case NID_sha1: +#ifndef OPENSSL_NO_SHA256 case NID_sha224: case NID_sha256: +#endif +#ifndef OPENSSL_NO_SHA512 case NID_sha384: case NID_sha512: +#endif return 1; default: return 0; @@ -390,7 +419,7 @@ char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) * md_out: the digest output. At most EVP_MAX_MD_SIZE bytes will be written. * md_out_size: if non-NULL, the number of output bytes is written here. * header: the 13-byte, TLS record header. - * data: the record data itself, less any preceeding explicit IV. + * data: the record data itself, less any preceding explicit IV. * data_plus_mac_size: the secret, reported length of the data and MAC * once the padding has been removed. * data_plus_mac_plus_padding_size: the public length of the whole @@ -413,14 +442,15 @@ void ssl3_cbc_digest_record( unsigned mac_secret_length, char is_sslv3) { - unsigned char md_state[sizeof(SHA512_CTX)]; + 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; - uint64_t bits; + 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]; @@ -431,40 +461,46 @@ void ssl3_cbc_digest_record( /* 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; + int ret; /* 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 (ctx->digest->type) + switch (EVP_MD_CTX_type(ctx)) { case NID_md5: - MD5_Init((MD5_CTX*)md_state); + 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); + 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); + 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); + 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); + 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; @@ -472,13 +508,14 @@ void ssl3_cbc_digest_record( md_length_size = 16; break; case NID_sha512: - SHA512_Init((SHA512_CTX*)md_state); + 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 @@ -577,17 +614,25 @@ void ssl3_cbc_digest_record( for (i = 0; i < md_block_size; i++) hmac_pad[i] ^= 0x36; - md_transform(md_state, hmac_pad); + md_transform(md_state.c, hmac_pad); } - j = 0; - if (md_length_size == 16) + if (length_is_big_endian) { - memset(length_bytes, 0, 8); - j = 8; + 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; } - for (i = 0; i < 8; i++) - length_bytes[i+j] = bits >> (8*(7-i)); if (k > 0) { @@ -598,21 +643,21 @@ void ssl3_cbc_digest_record( * block that the header consumes: either 7 bytes * (SHA1) or 11 bytes (MD5). */ unsigned overhang = header_length-md_block_size; - md_transform(md_state, header); + 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, first_block); + md_transform(md_state.c, first_block); for (i = 1; i < k/md_block_size - 1; i++) - md_transform(md_state, data + md_block_size*i - overhang); + 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, first_block); + md_transform(md_state.c, first_block); for (i = 1; i < k/md_block_size; i++) - md_transform(md_state, data + md_block_size*i - 13); + md_transform(md_state.c, data + md_block_size*i - 13); } } @@ -662,8 +707,8 @@ void ssl3_cbc_digest_record( block[j] = b; } - md_transform(md_state, block); - md_final_raw(md_state, block); + 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; @@ -689,8 +734,55 @@ void ssl3_cbc_digest_record( 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) + ret = EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u); + if (ret && 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. + */ + +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