| // Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include <openssl/ssl.h> |
| |
| #include <assert.h> |
| #include <string.h> |
| |
| #include <openssl/bytestring.h> |
| #include <openssl/err.h> |
| #include <openssl/mem.h> |
| |
| #include "../crypto/internal.h" |
| #include "internal.h" |
| |
| |
| BSSL_NAMESPACE_BEGIN |
| |
| // kMaxEmptyRecords is the number of consecutive, empty records that will be |
| // processed. Without this limit an attacker could send empty records at a |
| // faster rate than we can process and cause record processing to loop |
| // forever. |
| static const uint8_t kMaxEmptyRecords = 32; |
| |
| // kMaxEarlyDataSkipped is the maximum number of rejected early data bytes that |
| // will be skipped. Without this limit an attacker could send records at a |
| // faster rate than we can process and cause trial decryption to loop forever. |
| // This value should be slightly above kMaxEarlyDataAccepted, which is measured |
| // in plaintext. |
| static const size_t kMaxEarlyDataSkipped = 16384; |
| |
| // kMaxWarningAlerts is the number of consecutive warning alerts that will be |
| // processed. |
| static const uint8_t kMaxWarningAlerts = 4; |
| |
| // ssl_needs_record_splitting returns one if |ssl|'s current outgoing cipher |
| // state needs record-splitting and zero otherwise. |
| bool ssl_needs_record_splitting(const SSL *ssl) { |
| #if !defined(BORINGSSL_UNSAFE_FUZZER_MODE) |
| return !ssl->s3->aead_write_ctx->is_null_cipher() && |
| ssl_protocol_version(ssl) < TLS1_1_VERSION && |
| (ssl->mode & SSL_MODE_CBC_RECORD_SPLITTING) != 0 && |
| SSL_CIPHER_is_block_cipher(ssl->s3->aead_write_ctx->cipher()); |
| #else |
| return false; |
| #endif |
| } |
| |
| size_t ssl_record_prefix_len(const SSL *ssl) { |
| assert(!SSL_is_dtls(ssl)); |
| return SSL3_RT_HEADER_LENGTH + ssl->s3->aead_read_ctx->ExplicitNonceLen(); |
| } |
| |
| static ssl_open_record_t skip_early_data(SSL *ssl, uint8_t *out_alert, |
| size_t consumed) { |
| ssl->s3->early_data_skipped += consumed; |
| if (ssl->s3->early_data_skipped < consumed) { |
| ssl->s3->early_data_skipped = kMaxEarlyDataSkipped + 1; |
| } |
| |
| if (ssl->s3->early_data_skipped > kMaxEarlyDataSkipped) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_TOO_MUCH_SKIPPED_EARLY_DATA); |
| *out_alert = SSL_AD_UNEXPECTED_MESSAGE; |
| return ssl_open_record_error; |
| } |
| |
| return ssl_open_record_discard; |
| } |
| |
| static uint16_t tls_record_version(const SSL *ssl) { |
| if (ssl->s3->version == 0) { |
| // Before the version is determined, outgoing records use TLS 1.0 for |
| // historical compatibility requirements. |
| return TLS1_VERSION; |
| } |
| |
| // TLS 1.3 freezes the record version at TLS 1.2. Previous ones use the |
| // version itself. |
| return ssl_protocol_version(ssl) >= TLS1_3_VERSION ? TLS1_2_VERSION |
| : ssl->s3->version; |
| } |
| |
| ssl_open_record_t tls_open_record(SSL *ssl, uint8_t *out_type, |
| Span<uint8_t> *out, size_t *out_consumed, |
| uint8_t *out_alert, Span<uint8_t> in) { |
| *out_consumed = 0; |
| if (ssl->s3->read_shutdown == ssl_shutdown_close_notify) { |
| return ssl_open_record_close_notify; |
| } |
| |
| // If there is an unprocessed handshake message or we are already buffering |
| // too much, stop before decrypting another handshake record. |
| if (!tls_can_accept_handshake_data(ssl, out_alert)) { |
| return ssl_open_record_error; |
| } |
| |
| CBS cbs = CBS(in); |
| |
| // Decode the record header. |
| uint8_t type; |
| uint16_t version, ciphertext_len; |
| if (!CBS_get_u8(&cbs, &type) || // |
| !CBS_get_u16(&cbs, &version) || // |
| !CBS_get_u16(&cbs, &ciphertext_len)) { |
| *out_consumed = SSL3_RT_HEADER_LENGTH; |
| return ssl_open_record_partial; |
| } |
| |
| bool version_ok; |
| if (ssl->s3->aead_read_ctx->is_null_cipher()) { |
| // Only check the first byte. Enforcing beyond that can prevent decoding |
| // version negotiation failure alerts. |
| version_ok = (version >> 8) == SSL3_VERSION_MAJOR; |
| } else { |
| version_ok = version == tls_record_version(ssl); |
| } |
| |
| if (!version_ok) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_VERSION_NUMBER); |
| *out_alert = SSL_AD_PROTOCOL_VERSION; |
| return ssl_open_record_error; |
| } |
| |
| // Check the ciphertext length. |
| if (ciphertext_len > SSL3_RT_MAX_ENCRYPTED_LENGTH) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_ENCRYPTED_LENGTH_TOO_LONG); |
| *out_alert = SSL_AD_RECORD_OVERFLOW; |
| return ssl_open_record_error; |
| } |
| |
| // Extract the body. |
| CBS body; |
| if (!CBS_get_bytes(&cbs, &body, ciphertext_len)) { |
| *out_consumed = SSL3_RT_HEADER_LENGTH + (size_t)ciphertext_len; |
| return ssl_open_record_partial; |
| } |
| |
| Span<const uint8_t> header = in.subspan(0, SSL3_RT_HEADER_LENGTH); |
| ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HEADER, header); |
| |
| *out_consumed = in.size() - CBS_len(&cbs); |
| |
| // In TLS 1.3, during the handshake, skip ChangeCipherSpec records. |
| static const uint8_t kChangeCipherSpec[] = {SSL3_MT_CCS}; |
| if (ssl_has_final_version(ssl) && |
| ssl_protocol_version(ssl) >= TLS1_3_VERSION && SSL_in_init(ssl) && |
| type == SSL3_RT_CHANGE_CIPHER_SPEC && |
| Span<const uint8_t>(body) == kChangeCipherSpec) { |
| ssl->s3->empty_record_count++; |
| if (ssl->s3->empty_record_count > kMaxEmptyRecords) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_TOO_MANY_EMPTY_FRAGMENTS); |
| *out_alert = SSL_AD_UNEXPECTED_MESSAGE; |
| return ssl_open_record_error; |
| } |
| return ssl_open_record_discard; |
| } |
| |
| // Skip early data received when expecting a second ClientHello if we rejected |
| // 0RTT. |
| if (ssl->s3->skip_early_data && // |
| ssl->s3->aead_read_ctx->is_null_cipher() && // |
| type == SSL3_RT_APPLICATION_DATA) { |
| return skip_early_data(ssl, out_alert, *out_consumed); |
| } |
| |
| // Ensure the sequence number update does not overflow. |
| if (ssl->s3->read_sequence + 1 == 0) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); |
| *out_alert = SSL_AD_INTERNAL_ERROR; |
| return ssl_open_record_error; |
| } |
| |
| // Decrypt the body in-place. |
| if (!ssl->s3->aead_read_ctx->Open( |
| out, type, version, ssl->s3->read_sequence, header, |
| Span(const_cast<uint8_t *>(CBS_data(&body)), CBS_len(&body)))) { |
| if (ssl->s3->skip_early_data && !ssl->s3->aead_read_ctx->is_null_cipher()) { |
| ERR_clear_error(); |
| return skip_early_data(ssl, out_alert, *out_consumed); |
| } |
| |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC); |
| *out_alert = SSL_AD_BAD_RECORD_MAC; |
| return ssl_open_record_error; |
| } |
| |
| ssl->s3->skip_early_data = false; |
| ssl->s3->read_sequence++; |
| |
| // TLS 1.3 hides the record type inside the encrypted data. |
| bool has_padding = !ssl->s3->aead_read_ctx->is_null_cipher() && |
| ssl_protocol_version(ssl) >= TLS1_3_VERSION; |
| |
| // If there is padding, the plaintext limit includes the padding, but includes |
| // extra room for the inner content type. |
| size_t plaintext_limit = |
| has_padding ? SSL3_RT_MAX_PLAIN_LENGTH + 1 : SSL3_RT_MAX_PLAIN_LENGTH; |
| if (out->size() > plaintext_limit) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DATA_LENGTH_TOO_LONG); |
| *out_alert = SSL_AD_RECORD_OVERFLOW; |
| return ssl_open_record_error; |
| } |
| |
| if (has_padding) { |
| // The outer record type is always application_data. |
| if (type != SSL3_RT_APPLICATION_DATA) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_OUTER_RECORD_TYPE); |
| *out_alert = SSL_AD_DECODE_ERROR; |
| return ssl_open_record_error; |
| } |
| |
| do { |
| if (out->empty()) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC); |
| *out_alert = SSL_AD_DECRYPT_ERROR; |
| return ssl_open_record_error; |
| } |
| type = out->back(); |
| *out = out->subspan(0, out->size() - 1); |
| } while (type == 0); |
| } |
| |
| // Limit the number of consecutive empty records. |
| if (out->empty()) { |
| ssl->s3->empty_record_count++; |
| if (ssl->s3->empty_record_count > kMaxEmptyRecords) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_TOO_MANY_EMPTY_FRAGMENTS); |
| *out_alert = SSL_AD_UNEXPECTED_MESSAGE; |
| return ssl_open_record_error; |
| } |
| // Apart from the limit, empty records are returned up to the caller. This |
| // allows the caller to reject records of the wrong type. |
| } else { |
| ssl->s3->empty_record_count = 0; |
| } |
| |
| if (type == SSL3_RT_ALERT) { |
| return ssl_process_alert(ssl, out_alert, *out); |
| } |
| |
| // Handshake messages may not interleave with any other record type. |
| if (type != SSL3_RT_HANDSHAKE && // |
| tls_has_unprocessed_handshake_data(ssl)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); |
| *out_alert = SSL_AD_UNEXPECTED_MESSAGE; |
| return ssl_open_record_error; |
| } |
| |
| ssl->s3->warning_alert_count = 0; |
| |
| *out_type = type; |
| return ssl_open_record_success; |
| } |
| |
| static bool do_seal_record(SSL *ssl, uint8_t *out_prefix, uint8_t *out, |
| uint8_t *out_suffix, uint8_t type, const uint8_t *in, |
| const size_t in_len) { |
| SSLAEADContext *aead = ssl->s3->aead_write_ctx.get(); |
| uint8_t *extra_in = NULL; |
| size_t extra_in_len = 0; |
| if (!aead->is_null_cipher() && ssl_protocol_version(ssl) >= TLS1_3_VERSION) { |
| // TLS 1.3 hides the actual record type inside the encrypted data. |
| extra_in = &type; |
| extra_in_len = 1; |
| } |
| |
| size_t suffix_len, ciphertext_len; |
| if (!aead->SuffixLen(&suffix_len, in_len, extra_in_len) || |
| !aead->CiphertextLen(&ciphertext_len, in_len, extra_in_len)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_RECORD_TOO_LARGE); |
| return false; |
| } |
| |
| assert(in == out || !buffers_alias(in, in_len, out, in_len)); |
| assert(!buffers_alias(in, in_len, out_prefix, ssl_record_prefix_len(ssl))); |
| assert(!buffers_alias(in, in_len, out_suffix, suffix_len)); |
| |
| if (extra_in_len) { |
| out_prefix[0] = SSL3_RT_APPLICATION_DATA; |
| } else { |
| out_prefix[0] = type; |
| } |
| |
| uint16_t record_version = tls_record_version(ssl); |
| out_prefix[1] = record_version >> 8; |
| out_prefix[2] = record_version & 0xff; |
| out_prefix[3] = ciphertext_len >> 8; |
| out_prefix[4] = ciphertext_len & 0xff; |
| Span<const uint8_t> header = Span(out_prefix, SSL3_RT_HEADER_LENGTH); |
| |
| // Ensure the sequence number update does not overflow. |
| if (ssl->s3->write_sequence + 1 == 0) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); |
| return false; |
| } |
| |
| if (!aead->SealScatter(out_prefix + SSL3_RT_HEADER_LENGTH, out, out_suffix, |
| out_prefix[0], record_version, ssl->s3->write_sequence, |
| header, in, in_len, extra_in, extra_in_len)) { |
| return false; |
| } |
| |
| ssl->s3->write_sequence++; |
| ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_HEADER, header); |
| return true; |
| } |
| |
| static size_t tls_seal_scatter_prefix_len(const SSL *ssl, uint8_t type, |
| size_t in_len) { |
| size_t ret = SSL3_RT_HEADER_LENGTH; |
| if (type == SSL3_RT_APPLICATION_DATA && in_len > 1 && |
| ssl_needs_record_splitting(ssl)) { |
| // In the case of record splitting, the 1-byte record (of the 1/n-1 split) |
| // will be placed in the prefix, as will four of the five bytes of the |
| // record header for the main record. The final byte will replace the first |
| // byte of the plaintext that was used in the small record. |
| ret += ssl_cipher_get_record_split_len(ssl->s3->aead_write_ctx->cipher()); |
| ret += SSL3_RT_HEADER_LENGTH - 1; |
| } else { |
| ret += ssl->s3->aead_write_ctx->ExplicitNonceLen(); |
| } |
| return ret; |
| } |
| |
| static bool tls_seal_scatter_suffix_len(const SSL *ssl, size_t *out_suffix_len, |
| uint8_t type, size_t in_len) { |
| size_t extra_in_len = 0; |
| if (!ssl->s3->aead_write_ctx->is_null_cipher() && |
| ssl_protocol_version(ssl) >= TLS1_3_VERSION) { |
| // TLS 1.3 adds an extra byte for encrypted record type. |
| extra_in_len = 1; |
| } |
| // clang-format off |
| if (type == SSL3_RT_APPLICATION_DATA && |
| in_len > 1 && |
| ssl_needs_record_splitting(ssl)) { |
| // With record splitting enabled, the first byte gets sealed into a separate |
| // record which is written into the prefix. |
| in_len -= 1; |
| } |
| // clang-format on |
| return ssl->s3->aead_write_ctx->SuffixLen(out_suffix_len, in_len, |
| extra_in_len); |
| } |
| |
| // tls_seal_scatter_record seals a new record of type |type| and body |in| and |
| // splits it between |out_prefix|, |out|, and |out_suffix|. Exactly |
| // |tls_seal_scatter_prefix_len| bytes are written to |out_prefix|, |in_len| |
| // bytes to |out|, and |tls_seal_scatter_suffix_len| bytes to |out_suffix|. It |
| // returns one on success and zero on error. If enabled, |
| // |tls_seal_scatter_record| implements TLS 1.0 CBC 1/n-1 record splitting and |
| // may write two records concatenated. |
| static bool tls_seal_scatter_record(SSL *ssl, uint8_t *out_prefix, uint8_t *out, |
| uint8_t *out_suffix, uint8_t type, |
| const uint8_t *in, size_t in_len) { |
| if (type == SSL3_RT_APPLICATION_DATA && in_len > 1 && |
| ssl_needs_record_splitting(ssl)) { |
| assert(ssl->s3->aead_write_ctx->ExplicitNonceLen() == 0); |
| const size_t prefix_len = SSL3_RT_HEADER_LENGTH; |
| |
| // Write the 1-byte fragment into |out_prefix|. |
| uint8_t *split_body = out_prefix + prefix_len; |
| uint8_t *split_suffix = split_body + 1; |
| |
| if (!do_seal_record(ssl, out_prefix, split_body, split_suffix, type, in, |
| 1)) { |
| return false; |
| } |
| |
| size_t split_record_suffix_len; |
| if (!ssl->s3->aead_write_ctx->SuffixLen(&split_record_suffix_len, 1, 0)) { |
| assert(false); |
| return false; |
| } |
| const size_t split_record_len = prefix_len + 1 + split_record_suffix_len; |
| assert(SSL3_RT_HEADER_LENGTH + ssl_cipher_get_record_split_len( |
| ssl->s3->aead_write_ctx->cipher()) == |
| split_record_len); |
| |
| // Write the n-1-byte fragment. The header gets split between |out_prefix| |
| // (header[:-1]) and |out| (header[-1:]). |
| uint8_t tmp_prefix[SSL3_RT_HEADER_LENGTH]; |
| if (!do_seal_record(ssl, tmp_prefix, out + 1, out_suffix, type, in + 1, |
| in_len - 1)) { |
| return false; |
| } |
| assert(tls_seal_scatter_prefix_len(ssl, type, in_len) == |
| split_record_len + SSL3_RT_HEADER_LENGTH - 1); |
| OPENSSL_memcpy(out_prefix + split_record_len, tmp_prefix, |
| SSL3_RT_HEADER_LENGTH - 1); |
| OPENSSL_memcpy(out, tmp_prefix + SSL3_RT_HEADER_LENGTH - 1, 1); |
| return true; |
| } |
| |
| return do_seal_record(ssl, out_prefix, out, out_suffix, type, in, in_len); |
| } |
| |
| bool tls_seal_record(SSL *ssl, uint8_t *out, size_t *out_len, |
| size_t max_out_len, uint8_t type, const uint8_t *in, |
| size_t in_len) { |
| if (buffers_alias(in, in_len, out, max_out_len)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_OUTPUT_ALIASES_INPUT); |
| return false; |
| } |
| |
| const size_t prefix_len = tls_seal_scatter_prefix_len(ssl, type, in_len); |
| size_t suffix_len; |
| if (!tls_seal_scatter_suffix_len(ssl, &suffix_len, type, in_len)) { |
| return false; |
| } |
| if (in_len + prefix_len < in_len || |
| prefix_len + in_len + suffix_len < prefix_len + in_len) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_RECORD_TOO_LARGE); |
| return false; |
| } |
| if (max_out_len < in_len + prefix_len + suffix_len) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL); |
| return false; |
| } |
| |
| uint8_t *prefix = out; |
| uint8_t *body = out + prefix_len; |
| uint8_t *suffix = body + in_len; |
| if (!tls_seal_scatter_record(ssl, prefix, body, suffix, type, in, in_len)) { |
| return false; |
| } |
| |
| *out_len = prefix_len + in_len + suffix_len; |
| return true; |
| } |
| |
| enum ssl_open_record_t ssl_process_alert(SSL *ssl, uint8_t *out_alert, |
| Span<const uint8_t> in) { |
| // Alerts records may not contain fragmented or multiple alerts. |
| if (in.size() != 2) { |
| *out_alert = SSL_AD_DECODE_ERROR; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ALERT); |
| return ssl_open_record_error; |
| } |
| |
| ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_ALERT, in); |
| |
| const uint8_t alert_level = in[0]; |
| const uint8_t alert_descr = in[1]; |
| |
| uint16_t alert = (alert_level << 8) | alert_descr; |
| ssl_do_info_callback(ssl, SSL_CB_READ_ALERT, alert); |
| |
| if (alert_level == SSL3_AL_WARNING) { |
| if (alert_descr == SSL_AD_CLOSE_NOTIFY) { |
| ssl->s3->read_shutdown = ssl_shutdown_close_notify; |
| return ssl_open_record_close_notify; |
| } |
| |
| // Warning alerts do not exist in TLS 1.3, but RFC 8446 section 6.1 |
| // continues to define user_canceled as a signal to cancel the handshake, |
| // without specifying how to handle it. JDK11 misuses it to signal |
| // full-duplex connection close after the handshake. As a workaround, skip |
| // user_canceled as in TLS 1.2. This matches NSS and OpenSSL. |
| if (ssl_has_final_version(ssl) && |
| ssl_protocol_version(ssl) >= TLS1_3_VERSION && |
| alert_descr != SSL_AD_USER_CANCELLED) { |
| *out_alert = SSL_AD_DECODE_ERROR; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ALERT); |
| return ssl_open_record_error; |
| } |
| |
| ssl->s3->warning_alert_count++; |
| if (ssl->s3->warning_alert_count > kMaxWarningAlerts) { |
| *out_alert = SSL_AD_UNEXPECTED_MESSAGE; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_TOO_MANY_WARNING_ALERTS); |
| return ssl_open_record_error; |
| } |
| return ssl_open_record_discard; |
| } |
| |
| if (alert_level == SSL3_AL_FATAL) { |
| OPENSSL_PUT_ERROR(SSL, SSL_AD_REASON_OFFSET + alert_descr); |
| ERR_add_error_dataf("SSL alert number %d", alert_descr); |
| *out_alert = 0; // No alert to send back to the peer. |
| return ssl_open_record_error; |
| } |
| |
| *out_alert = SSL_AD_ILLEGAL_PARAMETER; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_ALERT_TYPE); |
| return ssl_open_record_error; |
| } |
| |
| BSSL_NAMESPACE_END |
| |
| using namespace bssl; |
| |
| size_t SSL_max_seal_overhead(const SSL *ssl) { |
| if (SSL_is_dtls(ssl)) { |
| // TODO(crbug.com/381113363): Use the 0-RTT epoch if writing 0-RTT. |
| return dtls_max_seal_overhead(ssl, ssl->d1->write_epoch.epoch()); |
| } |
| |
| size_t ret = SSL3_RT_HEADER_LENGTH; |
| ret += ssl->s3->aead_write_ctx->MaxOverhead(); |
| // TLS 1.3 needs an extra byte for the encrypted record type. |
| if (!ssl->s3->aead_write_ctx->is_null_cipher() && |
| ssl_protocol_version(ssl) >= TLS1_3_VERSION) { |
| ret += 1; |
| } |
| if (ssl_needs_record_splitting(ssl)) { |
| ret *= 2; |
| } |
| return ret; |
| } |