| /* 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 <openssl/ssl.h> |
| |
| #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 = 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) { |
| assert(fixed_iv_len <= sizeof(aead_ctx->fixed_nonce)); |
| memcpy(aead_ctx->fixed_nonce, fixed_iv, fixed_iv_len); |
| aead_ctx->fixed_nonce_len = fixed_iv_len; |
| |
| if (cipher->algorithm_enc & SSL_CHACHA20POLY1305) { |
| /* The fixed nonce into the actual nonce (the sequence number). */ |
| aead_ctx->xor_fixed_nonce = 1; |
| aead_ctx->variable_nonce_len = 8; |
| } else { |
| /* The fixed IV is prepended to the nonce. */ |
| assert(fixed_iv_len <= aead_ctx->variable_nonce_len); |
| aead_ctx->variable_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; |
| |
| /* Prepend the fixed nonce, or left-pad with zeros if XORing. */ |
| if (aead->xor_fixed_nonce) { |
| nonce_len = aead->fixed_nonce_len - aead->variable_nonce_len; |
| memset(nonce, 0, nonce_len); |
| } else { |
| memcpy(nonce, aead->fixed_nonce, aead->fixed_nonce_len); |
| nonce_len += aead->fixed_nonce_len; |
| } |
| |
| /* Add the variable nonce. */ |
| 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; |
| |
| /* XOR the fixed nonce, if necessary. */ |
| if (aead->xor_fixed_nonce) { |
| assert(nonce_len == aead->fixed_nonce_len); |
| size_t i; |
| for (i = 0; i < aead->fixed_nonce_len; i++) { |
| nonce[i] ^= aead->fixed_nonce[i]; |
| } |
| } |
| |
| 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; |
| |
| /* Prepend the fixed nonce, or left-pad with zeros if XORing. */ |
| if (aead->xor_fixed_nonce) { |
| nonce_len = aead->fixed_nonce_len - aead->variable_nonce_len; |
| memset(nonce, 0, nonce_len); |
| } else { |
| memcpy(nonce, aead->fixed_nonce, aead->fixed_nonce_len); |
| nonce_len += aead->fixed_nonce_len; |
| } |
| |
| /* Select the variable nonce. */ |
| 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, seqnum, 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) { |
| assert(!aead->xor_fixed_nonce); |
| 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; |
| } |
| |
| /* XOR the fixed nonce, if necessary. */ |
| if (aead->xor_fixed_nonce) { |
| assert(nonce_len == aead->fixed_nonce_len); |
| size_t i; |
| for (i = 0; i < aead->fixed_nonce_len; i++) { |
| nonce[i] ^= aead->fixed_nonce[i]; |
| } |
| } |
| |
| 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; |
| } |