X-Git-Url: https://git.openssl.org/?p=openssl.git;a=blobdiff_plain;f=ssl%2Fs3_cbc.c;h=8df32ba326aa2758327b69a42d6809133d90c416;hp=a926c895a2017f6f9c8552e1f46032239d446da0;hb=54bb8f74bd3931f801472e86c481c80f868c2b91;hpb=0f113f3ee4d629ef9a4a30911b22b224772085e5 diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c index a926c895a2..8df32ba326 100644 --- a/ssl/s3_cbc.c +++ b/ssl/s3_cbc.c @@ -1,4 +1,3 @@ -/* ssl/s3_cbc.c */ /* ==================================================================== * Copyright (c) 2012 The OpenSSL Project. All rights reserved. * @@ -53,7 +52,7 @@ * */ -#include "../crypto/constant_time_locl.h" +#include "internal/constant_time_locl.h" #include "ssl_locl.h" #include @@ -72,227 +71,7 @@ */ #define MAX_HASH_BLOCK_SIZE 128 -/*- - * 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); - rec->length -= good & (padding_length + 1); - 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 - * padding was removed. - * - * 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 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 (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]; - - /* - * 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); - rec->length -= good & (padding_length + 1); - - 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). - * - * ssl3_cbc_remove_padding or tls1_cbc_remove_padding must be called prior to - * this function. - * - * On entry: - * rec->orig_len >= md_size - * md_size <= EVP_MAX_MD_SIZE - * - * 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 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[64 + EVP_MAX_MD_SIZE]; - unsigned char *rotated_mac; -#else - 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(rec->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); -#endif - - /* This information is public so it's safe to branch based on it. */ - if (rec->orig_len > md_size + 255 + 1) - scan_start = rec->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 < rec->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); - } -#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); - } -#endif -} /* * u32toLE serialises an unsigned, 32-bit number (n) as four bytes at (p) in @@ -328,9 +107,6 @@ static void tls1_sha1_final_raw(void *ctx, unsigned char *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; @@ -341,11 +117,6 @@ static void tls1_sha256_final_raw(void *ctx, unsigned char *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; @@ -356,9 +127,8 @@ static void tls1_sha512_final_raw(void *ctx, unsigned char *md_out) } } -# undef LARGEST_DIGEST_CTX -# define LARGEST_DIGEST_CTX SHA512_CTX -#endif +#undef LARGEST_DIGEST_CTX +#define LARGEST_DIGEST_CTX SHA512_CTX /* * ssl3_cbc_record_digest_supported returns 1 iff |ctx| uses a hash function @@ -371,14 +141,10 @@ char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) 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; @@ -405,8 +171,9 @@ char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) * 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. ) + * Returns 1 on success or 0 on error */ -void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, +int ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, unsigned char *md_out, size_t *md_out_size, const unsigned char header[13], @@ -433,7 +200,7 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, 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; + EVP_MD_CTX *md_ctx = NULL; /* * mdLengthSize is the number of bytes in the length field that * terminates * the hash. @@ -450,7 +217,8 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, switch (EVP_MD_CTX_type(ctx)) { case NID_md5: - MD5_Init((MD5_CTX *)md_state.c); + if (MD5_Init((MD5_CTX *)md_state.c) <= 0) + return 0; md_final_raw = tls1_md5_final_raw; md_transform = (void (*)(void *ctx, const unsigned char *block))MD5_Transform; @@ -459,31 +227,32 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, length_is_big_endian = 0; break; case NID_sha1: - SHA1_Init((SHA_CTX *)md_state.c); + if (SHA1_Init((SHA_CTX *)md_state.c) <= 0) + return 0; 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); + if (SHA224_Init((SHA256_CTX *)md_state.c) <= 0) + return 0; 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); + if (SHA256_Init((SHA256_CTX *)md_state.c) <= 0) + return 0; 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); + if (SHA384_Init((SHA512_CTX *)md_state.c) <= 0) + return 0; md_final_raw = tls1_sha512_final_raw; md_transform = (void (*)(void *ctx, const unsigned char *block))SHA512_Transform; @@ -492,7 +261,8 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, md_length_size = 16; break; case NID_sha512: - SHA512_Init((SHA512_CTX *)md_state.c); + if (SHA512_Init((SHA512_CTX *)md_state.c) <= 0) + return 0; md_final_raw = tls1_sha512_final_raw; md_transform = (void (*)(void *ctx, const unsigned char *block))SHA512_Transform; @@ -500,7 +270,6 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, md_block_size = 128; md_length_size = 16; break; -#endif default: /* * ssl3_cbc_record_digest_supported should have been called first to @@ -508,8 +277,8 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, */ OPENSSL_assert(0); if (md_out_size) - *md_out_size = -1; - return; + *md_out_size = 0; + return 0; } OPENSSL_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES); @@ -634,12 +403,22 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, if (k > 0) { if (is_sslv3) { + unsigned overhang; + /* * 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). + * consumes: either 7 bytes (SHA1) or 11 bytes (MD5). There are no + * ciphersuites in SSLv3 that are not SHA1 or MD5 based and + * therefore we can be confident that the header_length will be + * greater than |md_block_size|. However we add a sanity check just + * in case */ - unsigned overhang = header_length - md_block_size; + if (header_length <= md_block_size) { + /* Should never happen */ + return 0; + } + 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); @@ -717,27 +496,37 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, mac_out[j] |= block[j] & is_block_b; } - EVP_MD_CTX_init(&md_ctx); - EVP_DigestInit_ex(&md_ctx, ctx->digest, NULL /* engine */ ); + md_ctx = EVP_MD_CTX_new(); + if (md_ctx == NULL) + goto err; + if (EVP_DigestInit_ex(md_ctx, EVP_MD_CTX_md(ctx), NULL /* engine */ ) <= 0) + goto err; 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); + if (EVP_DigestUpdate(md_ctx, mac_secret, mac_secret_length) <= 0 + || EVP_DigestUpdate(md_ctx, hmac_pad, sslv3_pad_length) <= 0 + || EVP_DigestUpdate(md_ctx, mac_out, md_size) <= 0) + goto err; } 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); + if (EVP_DigestUpdate(md_ctx, hmac_pad, md_block_size) <= 0 + || EVP_DigestUpdate(md_ctx, mac_out, md_size) <= 0) + goto err; } - ret = EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u); + 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); + EVP_MD_CTX_free(md_ctx); + + return 1; +err: + EVP_MD_CTX_free(md_ctx); + return 0; } /* @@ -754,25 +543,25 @@ void tls_fips_digest_extra(const EVP_CIPHER_CTX *cipher_ctx, 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. - */ + /*- + * 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;