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-rw-r--r--ssl/record/methods/ssl3_cbc.c504
1 files changed, 504 insertions, 0 deletions
diff --git a/ssl/record/methods/ssl3_cbc.c b/ssl/record/methods/ssl3_cbc.c
new file mode 100644
index 0000000000..a254489769
--- /dev/null
+++ b/ssl/record/methods/ssl3_cbc.c
@@ -0,0 +1,504 @@
+/*
+ * Copyright 2012-2021 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License"). You may not use
+ * this file except in compliance with the License. You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/*
+ * This file has no dependencies on the rest of libssl because it is shared
+ * with the providers. It contains functions for low level MAC calculations.
+ * Responsibility for this lies with the HMAC implementation in the
+ * providers. However there are legacy code paths in libssl which also need to
+ * do this. In time those legacy code paths can be removed and this file can be
+ * moved out of libssl.
+ */
+
+
+/*
+ * MD5 and SHA-1 low level APIs are deprecated for public use, but still ok for
+ * internal use.
+ */
+#include "internal/deprecated.h"
+
+#include "recmethod_local.h"
+
+#include "internal/constant_time.h"
+#include "internal/cryptlib.h"
+
+#include <openssl/evp.h>
+#ifndef FIPS_MODULE
+# include <openssl/md5.h>
+#endif
+#include <openssl/sha.h>
+
+# define l2n(l,c) (*((c)++)=(unsigned char)(((l)>>24)&0xff), \
+ *((c)++)=(unsigned char)(((l)>>16)&0xff), \
+ *((c)++)=(unsigned char)(((l)>> 8)&0xff), \
+ *((c)++)=(unsigned char)(((l) )&0xff))
+
+# define l2n6(l,c) (*((c)++)=(unsigned char)(((l)>>40)&0xff), \
+ *((c)++)=(unsigned char)(((l)>>32)&0xff), \
+ *((c)++)=(unsigned char)(((l)>>24)&0xff), \
+ *((c)++)=(unsigned char)(((l)>>16)&0xff), \
+ *((c)++)=(unsigned char)(((l)>> 8)&0xff), \
+ *((c)++)=(unsigned char)(((l) )&0xff))
+
+# define l2n8(l,c) (*((c)++)=(unsigned char)(((l)>>56)&0xff), \
+ *((c)++)=(unsigned char)(((l)>>48)&0xff), \
+ *((c)++)=(unsigned char)(((l)>>40)&0xff), \
+ *((c)++)=(unsigned char)(((l)>>32)&0xff), \
+ *((c)++)=(unsigned char)(((l)>>24)&0xff), \
+ *((c)++)=(unsigned char)(((l)>>16)&0xff), \
+ *((c)++)=(unsigned char)(((l)>> 8)&0xff), \
+ *((c)++)=(unsigned char)(((l) )&0xff))
+
+/*
+ * 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.
+ * Currently SHA-384/512 has a 128-byte block size and that's the largest
+ * supported by TLS.)
+ */
+#define MAX_HASH_BLOCK_SIZE 128
+
+#ifndef FIPS_MODULE
+/*
+ * u32toLE serializes 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);
+}
+#endif /* FIPS_MODULE */
+
+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);
+}
+
+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);
+ }
+}
+
+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
+
+/*-
+ * 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.
+ * ssl3_cbc_record_digest_supported must return true for this EVP_MD_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 preceding explicit IV.
+ * data_size: the secret, reported length of the data once the MAC and padding
+ * has been removed.
+ * data_plus_mac_plus_padding_size: the public length of the whole
+ * record, including MAC and padding.
+ * is_sslv3: non-zero if we are to use SSLv3. Otherwise, TLS.
+ *
+ * On entry: we know that data is data_plus_mac_plus_padding_size in length
+ * Returns 1 on success or 0 on error
+ */
+int ssl3_cbc_digest_record(const EVP_MD *md,
+ unsigned char *md_out,
+ size_t *md_out_size,
+ const unsigned char *header,
+ const unsigned char *data,
+ size_t data_size,
+ size_t data_plus_mac_plus_padding_size,
+ const unsigned char *mac_secret,
+ size_t mac_secret_length, char is_sslv3)
+{
+ union {
+ OSSL_UNION_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);
+ size_t md_size, md_block_size = 64;
+ size_t 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;
+ size_t 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];
+ size_t i, j;
+ unsigned md_out_size_u;
+ EVP_MD_CTX *md_ctx = NULL;
+ /*
+ * mdLengthSize is the number of bytes in the length field that
+ * terminates * the hash.
+ */
+ size_t md_length_size = 8;
+ char length_is_big_endian = 1;
+ int ret = 0;
+
+ /*
+ * This is a, hopefully redundant, check that allows us to forget about
+ * many possible overflows later in this function.
+ */
+ if (!ossl_assert(data_plus_mac_plus_padding_size < 1024 * 1024))
+ return 0;
+
+ if (EVP_MD_is_a(md, "MD5")) {
+#ifdef FIPS_MODULE
+ return 0;
+#else
+ 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;
+ md_size = 16;
+ sslv3_pad_length = 48;
+ length_is_big_endian = 0;
+#endif
+ } else if (EVP_MD_is_a(md, "SHA1")) {
+ 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;
+ } else if (EVP_MD_is_a(md, "SHA2-224")) {
+ 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;
+ } else if (EVP_MD_is_a(md, "SHA2-256")) {
+ 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;
+ } else if (EVP_MD_is_a(md, "SHA2-384")) {
+ 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;
+ md_size = 384 / 8;
+ md_block_size = 128;
+ md_length_size = 16;
+ } else if (EVP_MD_is_a(md, "SHA2-512")) {
+ 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;
+ md_size = 64;
+ md_block_size = 128;
+ md_length_size = 16;
+ } else {
+ /*
+ * ssl3_cbc_record_digest_supported should have been called first to
+ * check that the hash function is supported.
+ */
+ if (md_out_size != NULL)
+ *md_out_size = 0;
+ return ossl_assert(0);
+ }
+
+ if (!ossl_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES)
+ || !ossl_assert(md_block_size <= MAX_HASH_BLOCK_SIZE)
+ || !ossl_assert(md_size <= EVP_MAX_MD_SIZE))
+ return 0;
+
+ 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 |variance_blocks|
+ * 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 : ( ((255 + 1 + md_size + md_block_size - 1) / md_block_size) + 1);
+ /*
+ * 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_size + header_length;
+ /*
+ * 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);
+ if (!ossl_assert(mac_secret_length <= sizeof(hmac_pad)))
+ return 0;
+ 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) {
+ size_t 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). 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
+ */
+ 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);
+ 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_s(i, index_a);
+ unsigned char is_block_b = constant_time_eq_8_s(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_s(j, c);
+ is_past_cp1 = is_block_a & constant_time_ge_8_s(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 block contains 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;
+ }
+
+ md_ctx = EVP_MD_CTX_new();
+ if (md_ctx == NULL)
+ goto err;
+
+ if (EVP_DigestInit_ex(md_ctx, md, 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);
+
+ 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;
+
+ 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);
+ if (ret && md_out_size)
+ *md_out_size = md_out_size_u;
+
+ ret = 1;
+ err:
+ EVP_MD_CTX_free(md_ctx);
+ return ret;
+}
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