1 /* Copyright (c) 2015, Google Inc. 2 * 3 * Permission to use, copy, modify, and/or distribute this software for any 4 * purpose with or without fee is hereby granted, provided that the above 5 * copyright notice and this permission notice appear in all copies. 6 * 7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ 14 15 #include <openssl/ssl.h> 16 17 #include <assert.h> 18 #include <limits.h> 19 #include <stdlib.h> 20 #include <string.h> 21 22 #include <openssl/bio.h> 23 #include <openssl/err.h> 24 #include <openssl/mem.h> 25 26 #include "../crypto/internal.h" 27 #include "internal.h" 28 29 30 namespace bssl { 31 32 // BIO uses int instead of size_t. No lengths will exceed uint16_t, so this will 33 // not overflow. 34 static_assert(0xffff <= INT_MAX, "uint16_t does not fit in int"); 35 36 static_assert((SSL3_ALIGN_PAYLOAD & (SSL3_ALIGN_PAYLOAD - 1)) == 0, 37 "SSL3_ALIGN_PAYLOAD must be a power of 2"); 38 39 void SSLBuffer::Clear() { 40 free(buf_); // Allocated with malloc(). 41 buf_ = nullptr; 42 offset_ = 0; 43 size_ = 0; 44 cap_ = 0; 45 } 46 47 bool SSLBuffer::EnsureCap(size_t header_len, size_t new_cap) { 48 if (new_cap > 0xffff) { 49 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 50 return false; 51 } 52 53 if (cap_ >= new_cap) { 54 return true; 55 } 56 57 // Add up to |SSL3_ALIGN_PAYLOAD| - 1 bytes of slack for alignment. 58 // 59 // Since this buffer gets allocated quite frequently and doesn't contain any 60 // sensitive data, we allocate with malloc rather than |OPENSSL_malloc| and 61 // avoid zeroing on free. 62 uint8_t *new_buf = (uint8_t *)malloc(new_cap + SSL3_ALIGN_PAYLOAD - 1); 63 if (new_buf == NULL) { 64 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 65 return false; 66 } 67 68 // Offset the buffer such that the record body is aligned. 69 size_t new_offset = 70 (0 - header_len - (uintptr_t)new_buf) & (SSL3_ALIGN_PAYLOAD - 1); 71 72 if (buf_ != NULL) { 73 OPENSSL_memcpy(new_buf + new_offset, buf_ + offset_, size_); 74 free(buf_); // Allocated with malloc(). 75 } 76 77 buf_ = new_buf; 78 offset_ = new_offset; 79 cap_ = new_cap; 80 return true; 81 } 82 83 void SSLBuffer::DidWrite(size_t new_size) { 84 if (new_size > cap() - size()) { 85 abort(); 86 } 87 size_ += new_size; 88 } 89 90 void SSLBuffer::Consume(size_t len) { 91 if (len > size_) { 92 abort(); 93 } 94 offset_ += (uint16_t)len; 95 size_ -= (uint16_t)len; 96 cap_ -= (uint16_t)len; 97 } 98 99 void SSLBuffer::DiscardConsumed() { 100 if (size_ == 0) { 101 Clear(); 102 } 103 } 104 105 static int dtls_read_buffer_next_packet(SSL *ssl) { 106 SSLBuffer *buf = &ssl->s3->read_buffer; 107 108 if (!buf->empty()) { 109 // It is an error to call |dtls_read_buffer_extend| when the read buffer is 110 // not empty. 111 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 112 return -1; 113 } 114 115 // Read a single packet from |ssl->rbio|. |buf->cap()| must fit in an int. 116 int ret = BIO_read(ssl->rbio, buf->data(), static_cast<int>(buf->cap())); 117 if (ret <= 0) { 118 ssl->s3->rwstate = SSL_READING; 119 return ret; 120 } 121 buf->DidWrite(static_cast<size_t>(ret)); 122 return 1; 123 } 124 125 static int tls_read_buffer_extend_to(SSL *ssl, size_t len) { 126 SSLBuffer *buf = &ssl->s3->read_buffer; 127 128 if (len > buf->cap()) { 129 OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL); 130 return -1; 131 } 132 133 // Read until the target length is reached. 134 while (buf->size() < len) { 135 // The amount of data to read is bounded by |buf->cap|, which must fit in an 136 // int. 137 int ret = BIO_read(ssl->rbio, buf->data() + buf->size(), 138 static_cast<int>(len - buf->size())); 139 if (ret <= 0) { 140 ssl->s3->rwstate = SSL_READING; 141 return ret; 142 } 143 buf->DidWrite(static_cast<size_t>(ret)); 144 } 145 146 return 1; 147 } 148 149 int ssl_read_buffer_extend_to(SSL *ssl, size_t len) { 150 // |ssl_read_buffer_extend_to| implicitly discards any consumed data. 151 ssl->s3->read_buffer.DiscardConsumed(); 152 153 if (SSL_is_dtls(ssl)) { 154 static_assert( 155 DTLS1_RT_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH <= 0xffff, 156 "DTLS read buffer is too large"); 157 158 // The |len| parameter is ignored in DTLS. 159 len = DTLS1_RT_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH; 160 } 161 162 if (!ssl->s3->read_buffer.EnsureCap(ssl_record_prefix_len(ssl), len)) { 163 return -1; 164 } 165 166 if (ssl->rbio == NULL) { 167 OPENSSL_PUT_ERROR(SSL, SSL_R_BIO_NOT_SET); 168 return -1; 169 } 170 171 int ret; 172 if (SSL_is_dtls(ssl)) { 173 // |len| is ignored for a datagram transport. 174 ret = dtls_read_buffer_next_packet(ssl); 175 } else { 176 ret = tls_read_buffer_extend_to(ssl, len); 177 } 178 179 if (ret <= 0) { 180 // If the buffer was empty originally and remained empty after attempting to 181 // extend it, release the buffer until the next attempt. 182 ssl->s3->read_buffer.DiscardConsumed(); 183 } 184 return ret; 185 } 186 187 int ssl_handle_open_record(SSL *ssl, bool *out_retry, ssl_open_record_t ret, 188 size_t consumed, uint8_t alert) { 189 *out_retry = false; 190 if (ret != ssl_open_record_partial) { 191 ssl->s3->read_buffer.Consume(consumed); 192 } 193 if (ret != ssl_open_record_success) { 194 // Nothing was returned to the caller, so discard anything marked consumed. 195 ssl->s3->read_buffer.DiscardConsumed(); 196 } 197 switch (ret) { 198 case ssl_open_record_success: 199 return 1; 200 201 case ssl_open_record_partial: { 202 int read_ret = ssl_read_buffer_extend_to(ssl, consumed); 203 if (read_ret <= 0) { 204 return read_ret; 205 } 206 *out_retry = true; 207 return 1; 208 } 209 210 case ssl_open_record_discard: 211 *out_retry = true; 212 return 1; 213 214 case ssl_open_record_close_notify: 215 return 0; 216 217 case ssl_open_record_error: 218 if (alert != 0) { 219 ssl_send_alert(ssl, SSL3_AL_FATAL, alert); 220 } 221 return -1; 222 } 223 assert(0); 224 return -1; 225 } 226 227 228 static_assert(SSL3_RT_HEADER_LENGTH * 2 + 229 SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD * 2 + 230 SSL3_RT_MAX_PLAIN_LENGTH <= 231 0xffff, 232 "maximum TLS write buffer is too large"); 233 234 static_assert(DTLS1_RT_HEADER_LENGTH + SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD + 235 SSL3_RT_MAX_PLAIN_LENGTH <= 236 0xffff, 237 "maximum DTLS write buffer is too large"); 238 239 static int tls_write_buffer_flush(SSL *ssl) { 240 SSLBuffer *buf = &ssl->s3->write_buffer; 241 242 while (!buf->empty()) { 243 int ret = BIO_write(ssl->wbio, buf->data(), buf->size()); 244 if (ret <= 0) { 245 ssl->s3->rwstate = SSL_WRITING; 246 return ret; 247 } 248 buf->Consume(static_cast<size_t>(ret)); 249 } 250 buf->Clear(); 251 return 1; 252 } 253 254 static int dtls_write_buffer_flush(SSL *ssl) { 255 SSLBuffer *buf = &ssl->s3->write_buffer; 256 if (buf->empty()) { 257 return 1; 258 } 259 260 int ret = BIO_write(ssl->wbio, buf->data(), buf->size()); 261 if (ret <= 0) { 262 ssl->s3->rwstate = SSL_WRITING; 263 // If the write failed, drop the write buffer anyway. Datagram transports 264 // can't write half a packet, so the caller is expected to retry from the 265 // top. 266 buf->Clear(); 267 return ret; 268 } 269 buf->Clear(); 270 return 1; 271 } 272 273 int ssl_write_buffer_flush(SSL *ssl) { 274 if (ssl->wbio == NULL) { 275 OPENSSL_PUT_ERROR(SSL, SSL_R_BIO_NOT_SET); 276 return -1; 277 } 278 279 if (SSL_is_dtls(ssl)) { 280 return dtls_write_buffer_flush(ssl); 281 } else { 282 return tls_write_buffer_flush(ssl); 283 } 284 } 285 286 } // namespace bssl 287
