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- /* Copyright (c) 2015, Google Inc.
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
- * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
- * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
- * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
-
- #include <assert.h>
- #include <string.h>
-
- #include <openssl/aead.h>
- #include <openssl/err.h>
- #include <openssl/rand.h>
- #include <openssl/type_check.h>
-
- #include "internal.h"
-
-
- OPENSSL_COMPILE_ASSERT(EVP_AEAD_MAX_NONCE_LENGTH < 256,
- variable_nonce_len_doesnt_fit_in_uint8_t);
-
- SSL_AEAD_CTX *SSL_AEAD_CTX_new(enum evp_aead_direction_t direction,
- uint16_t version, const SSL_CIPHER *cipher,
- const uint8_t *enc_key, size_t enc_key_len,
- const uint8_t *mac_key, size_t mac_key_len,
- const uint8_t *fixed_iv, size_t fixed_iv_len) {
- const EVP_AEAD *aead;
- size_t discard;
- if (!ssl_cipher_get_evp_aead(&aead, &discard, &discard, cipher, version)) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
- return 0;
- }
-
- uint8_t merged_key[EVP_AEAD_MAX_KEY_LENGTH];
- if (mac_key_len > 0) {
- /* This is a "stateful" AEAD (for compatibility with pre-AEAD cipher
- * suites). */
- if (mac_key_len + enc_key_len + fixed_iv_len > sizeof(merged_key)) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
- return 0;
- }
- memcpy(merged_key, mac_key, mac_key_len);
- memcpy(merged_key + mac_key_len, enc_key, enc_key_len);
- memcpy(merged_key + mac_key_len + enc_key_len, fixed_iv, fixed_iv_len);
- enc_key = merged_key;
- enc_key_len += mac_key_len;
- enc_key_len += fixed_iv_len;
- }
-
- SSL_AEAD_CTX *aead_ctx = (SSL_AEAD_CTX *)OPENSSL_malloc(sizeof(SSL_AEAD_CTX));
- if (aead_ctx == NULL) {
- OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
- return NULL;
- }
- memset(aead_ctx, 0, sizeof(SSL_AEAD_CTX));
- aead_ctx->cipher = cipher;
-
- if (!EVP_AEAD_CTX_init_with_direction(
- &aead_ctx->ctx, aead, enc_key, enc_key_len,
- EVP_AEAD_DEFAULT_TAG_LENGTH, direction)) {
- OPENSSL_free(aead_ctx);
- return NULL;
- }
-
- assert(EVP_AEAD_nonce_length(aead) <= EVP_AEAD_MAX_NONCE_LENGTH);
- aead_ctx->variable_nonce_len = (uint8_t)EVP_AEAD_nonce_length(aead);
- if (mac_key_len == 0) {
- /* For a real AEAD, the IV is the fixed part of the nonce. */
- if (fixed_iv_len > sizeof(aead_ctx->fixed_nonce) ||
- fixed_iv_len > aead_ctx->variable_nonce_len) {
- SSL_AEAD_CTX_free(aead_ctx);
- OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
- return 0;
- }
- aead_ctx->variable_nonce_len -= fixed_iv_len;
-
- memcpy(aead_ctx->fixed_nonce, fixed_iv, fixed_iv_len);
- aead_ctx->fixed_nonce_len = fixed_iv_len;
- /* AES-GCM uses an explicit nonce. */
- if (cipher->algorithm_enc & (SSL_AES128GCM | SSL_AES256GCM)) {
- aead_ctx->variable_nonce_included_in_record = 1;
- }
- } else {
- aead_ctx->variable_nonce_included_in_record = 1;
- aead_ctx->random_variable_nonce = 1;
- aead_ctx->omit_length_in_ad = 1;
- aead_ctx->omit_version_in_ad = (version == SSL3_VERSION);
- }
-
- return aead_ctx;
- }
-
- void SSL_AEAD_CTX_free(SSL_AEAD_CTX *aead) {
- if (aead == NULL) {
- return;
- }
- EVP_AEAD_CTX_cleanup(&aead->ctx);
- OPENSSL_free(aead);
- }
-
- size_t SSL_AEAD_CTX_explicit_nonce_len(SSL_AEAD_CTX *aead) {
- if (aead != NULL && aead->variable_nonce_included_in_record) {
- return aead->variable_nonce_len;
- }
- return 0;
- }
-
- size_t SSL_AEAD_CTX_max_overhead(SSL_AEAD_CTX *aead) {
- if (aead == NULL) {
- return 0;
- }
- return EVP_AEAD_max_overhead(aead->ctx.aead) +
- SSL_AEAD_CTX_explicit_nonce_len(aead);
- }
-
- /* ssl_aead_ctx_get_ad writes the additional data for |aead| into |out| and
- * returns the number of bytes written. */
- static size_t ssl_aead_ctx_get_ad(SSL_AEAD_CTX *aead, uint8_t out[13],
- uint8_t type, uint16_t wire_version,
- const uint8_t seqnum[8],
- size_t plaintext_len) {
- memcpy(out, seqnum, 8);
- size_t len = 8;
- out[len++] = type;
- if (!aead->omit_version_in_ad) {
- out[len++] = (uint8_t)(wire_version >> 8);
- out[len++] = (uint8_t)wire_version;
- }
- if (!aead->omit_length_in_ad) {
- out[len++] = (uint8_t)(plaintext_len >> 8);
- out[len++] = (uint8_t)plaintext_len;
- }
- return len;
- }
-
- int SSL_AEAD_CTX_open(SSL_AEAD_CTX *aead, uint8_t *out, size_t *out_len,
- size_t max_out, uint8_t type, uint16_t wire_version,
- const uint8_t seqnum[8], const uint8_t *in,
- size_t in_len) {
- if (aead == NULL) {
- /* Handle the initial NULL cipher. */
- if (in_len > max_out) {
- OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
- return 0;
- }
- memmove(out, in, in_len);
- *out_len = in_len;
- return 1;
- }
-
- /* TLS 1.2 AEADs include the length in the AD and are assumed to have fixed
- * overhead. Otherwise the parameter is unused. */
- size_t plaintext_len = 0;
- if (!aead->omit_length_in_ad) {
- size_t overhead = SSL_AEAD_CTX_max_overhead(aead);
- if (in_len < overhead) {
- /* Publicly invalid. */
- OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_PACKET_LENGTH);
- return 0;
- }
- plaintext_len = in_len - overhead;
- }
- uint8_t ad[13];
- size_t ad_len = ssl_aead_ctx_get_ad(aead, ad, type, wire_version, seqnum,
- plaintext_len);
-
- /* Assemble the nonce. */
- uint8_t nonce[EVP_AEAD_MAX_NONCE_LENGTH];
- size_t nonce_len = 0;
- memcpy(nonce, aead->fixed_nonce, aead->fixed_nonce_len);
- nonce_len += aead->fixed_nonce_len;
- if (aead->variable_nonce_included_in_record) {
- if (in_len < aead->variable_nonce_len) {
- /* Publicly invalid. */
- OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_PACKET_LENGTH);
- return 0;
- }
- memcpy(nonce + nonce_len, in, aead->variable_nonce_len);
- in += aead->variable_nonce_len;
- in_len -= aead->variable_nonce_len;
- } else {
- assert(aead->variable_nonce_len == 8);
- memcpy(nonce + nonce_len, seqnum, aead->variable_nonce_len);
- }
- nonce_len += aead->variable_nonce_len;
-
- return EVP_AEAD_CTX_open(&aead->ctx, out, out_len, max_out, nonce, nonce_len,
- in, in_len, ad, ad_len);
- }
-
- int SSL_AEAD_CTX_seal(SSL_AEAD_CTX *aead, uint8_t *out, size_t *out_len,
- size_t max_out, uint8_t type, uint16_t wire_version,
- const uint8_t seqnum[8], const uint8_t *in,
- size_t in_len) {
- if (aead == NULL) {
- /* Handle the initial NULL cipher. */
- if (in_len > max_out) {
- OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
- return 0;
- }
- memmove(out, in, in_len);
- *out_len = in_len;
- return 1;
- }
-
- uint8_t ad[13];
- size_t ad_len = ssl_aead_ctx_get_ad(aead, ad, type, wire_version, seqnum,
- in_len);
-
- /* Assemble the nonce. */
- uint8_t nonce[EVP_AEAD_MAX_NONCE_LENGTH];
- size_t nonce_len = 0;
- memcpy(nonce, aead->fixed_nonce, aead->fixed_nonce_len);
- nonce_len += aead->fixed_nonce_len;
- if (aead->random_variable_nonce) {
- assert(aead->variable_nonce_included_in_record);
- if (!RAND_bytes(nonce + nonce_len, aead->variable_nonce_len)) {
- return 0;
- }
- } else {
- /* When sending we use the sequence number as the variable part of the
- * nonce. */
- assert(aead->variable_nonce_len == 8);
- memcpy(nonce + nonce_len, ad, aead->variable_nonce_len);
- }
- nonce_len += aead->variable_nonce_len;
-
- /* Emit the variable nonce if included in the record. */
- size_t extra_len = 0;
- if (aead->variable_nonce_included_in_record) {
- if (max_out < aead->variable_nonce_len) {
- OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
- return 0;
- }
- if (out < in + in_len && in < out + aead->variable_nonce_len) {
- OPENSSL_PUT_ERROR(SSL, SSL_R_OUTPUT_ALIASES_INPUT);
- return 0;
- }
- memcpy(out, nonce + aead->fixed_nonce_len, aead->variable_nonce_len);
- extra_len = aead->variable_nonce_len;
- out += aead->variable_nonce_len;
- max_out -= aead->variable_nonce_len;
- }
-
- if (!EVP_AEAD_CTX_seal(&aead->ctx, out, out_len, max_out, nonce, nonce_len,
- in, in_len, ad, ad_len)) {
- return 0;
- }
- *out_len += extra_len;
- return 1;
- }
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