ssl/ssl_buffer.c - boringssl - Git at Google

 /* 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 <limits.h>
 #include <stdlib.h>
 #include <string.h>

 #include <openssl/bio.h>
 #include <openssl/err.h>
 #include <openssl/mem.h>
 #include <openssl/type_check.h>

 #include "internal.h"


 OPENSSL_COMPILE_ASSERT(0xffff <= INT_MAX, uint16_fits_in_int);

 OPENSSL_COMPILE_ASSERT((SSL3_ALIGN_PAYLOAD & (SSL3_ALIGN_PAYLOAD - 1)) == 0,
                        align_to_a_power_of_two);

 /* setup_buffer initializes |buf| with capacity |cap|, aligned such that data
  * written after |header_len| is aligned to a |SSL3_ALIGN_PAYLOAD|-byte
  * boundary. It returns one on success and zero on error. */
 static int setup_buffer(SSL3_BUFFER *buf, size_t header_len, size_t cap) {
   if (buf->buf != NULL || cap > 0xffff) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return 0;
   }

   /* Add up to |SSL3_ALIGN_PAYLOAD| - 1 bytes of slack for alignment. */
   buf->buf = OPENSSL_malloc(cap + SSL3_ALIGN_PAYLOAD - 1);
   if (buf->buf == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return 0;
   }

   /* Arrange the buffer such that the record body is aligned. */
   buf->offset = (0 - header_len - (uintptr_t)buf->buf) &
                 (SSL3_ALIGN_PAYLOAD - 1);
   buf->len = 0;
   buf->cap = cap;
   return 1;
 }

 static void consume_buffer(SSL3_BUFFER *buf, size_t len) {
   if (len > buf->len) {
     abort();
   }
   buf->offset += (uint16_t)len;
   buf->len -= (uint16_t)len;
   buf->cap -= (uint16_t)len;
 }

 static void clear_buffer(SSL3_BUFFER *buf) {
   OPENSSL_free(buf->buf);
   memset(buf, 0, sizeof(SSL3_BUFFER));
 }

 OPENSSL_COMPILE_ASSERT(DTLS1_RT_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH <=
                            0xffff,
                        maximum_read_buffer_too_large);

 /* setup_read_buffer initializes the read buffer if not already initialized. It
  * returns one on success and zero on failure. */
 static int setup_read_buffer(SSL *ssl) {
   SSL3_BUFFER *buf = &ssl->s3->read_buffer;

   if (buf->buf != NULL) {
     return 1;
   }

   size_t header_len = ssl_record_prefix_len(ssl);
   size_t cap = SSL3_RT_MAX_ENCRYPTED_LENGTH;
   if (SSL_IS_DTLS(ssl)) {
     cap += DTLS1_RT_HEADER_LENGTH;
   } else {
     cap += SSL3_RT_HEADER_LENGTH;
   }

   return setup_buffer(buf, header_len, cap);
 }

 uint8_t *ssl_read_buffer(SSL *ssl) {
   return ssl->s3->read_buffer.buf + ssl->s3->read_buffer.offset;
 }

 size_t ssl_read_buffer_len(const SSL *ssl) {
   return ssl->s3->read_buffer.len;
 }

 static int dtls_read_buffer_next_packet(SSL *ssl) {
   SSL3_BUFFER *buf = &ssl->s3->read_buffer;

   if (buf->len > 0) {
     /* It is an error to call |dtls_read_buffer_extend| when the read buffer is
      * not empty. */
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return -1;
   }

   /* Read a single packet from |ssl->rbio|. |buf->cap| must fit in an int. */
   ssl->rwstate = SSL_READING;
   int ret = BIO_read(ssl->rbio, buf->buf + buf->offset, (int)buf->cap);
   if (ret <= 0) {
     return ret;
   }
   ssl->rwstate = SSL_NOTHING;
   /* |BIO_read| was bound by |buf->cap|, so this cannot overflow. */
   buf->len = (uint16_t)ret;
   return 1;
 }

 static int tls_read_buffer_extend_to(SSL *ssl, size_t len) {
   SSL3_BUFFER *buf = &ssl->s3->read_buffer;

   if (len > buf->cap) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
     return -1;
   }

   /* Read until the target length is reached. */
   while (buf->len < len) {
     /* The amount of data to read is bounded by |buf->cap|, which must fit in an
      * int. */
     ssl->rwstate = SSL_READING;
     int ret = BIO_read(ssl->rbio, buf->buf + buf->offset + buf->len,
                        (int)(len - buf->len));
     if (ret <= 0) {
       return ret;
     }
     ssl->rwstate = SSL_NOTHING;
     /* |BIO_read| was bound by |buf->cap - buf->len|, so this cannot
      * overflow. */
     buf->len += (uint16_t)ret;
   }

   return 1;
 }

 int ssl_read_buffer_extend_to(SSL *ssl, size_t len) {
   /* |ssl_read_buffer_extend_to| implicitly discards any consumed data. */
   ssl_read_buffer_discard(ssl);

   if (!setup_read_buffer(ssl)) {
     return -1;
   }

   if (ssl->rbio == NULL) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_BIO_NOT_SET);
     return -1;
   }

   ERR_clear_system_error();

   int ret;
   if (SSL_IS_DTLS(ssl)) {
     /* |len| is ignored for a datagram transport. */
     ret = dtls_read_buffer_next_packet(ssl);
   } else {
     ret = tls_read_buffer_extend_to(ssl, len);
   }

   if (ret <= 0) {
     /* If the buffer was empty originally and remained empty after attempting to
      * extend it, release the buffer until the next attempt. */
     ssl_read_buffer_discard(ssl);
   }
   return ret;
 }

 void ssl_read_buffer_consume(SSL *ssl, size_t len) {
   SSL3_BUFFER *buf = &ssl->s3->read_buffer;

   consume_buffer(buf, len);
   if (!SSL_IS_DTLS(ssl)) {
     /* The TLS stack never reads beyond the current record, so there will never
      * be unconsumed data. If read-ahead is ever reimplemented,
      * |ssl_read_buffer_discard| will require a |memcpy| to shift the excess
      * back to the front of the buffer, to ensure there is enough space for the
      * next record. */
      assert(buf->len == 0);
   }
 }

 void ssl_read_buffer_discard(SSL *ssl) {
   if (ssl->s3->read_buffer.len == 0) {
     ssl_read_buffer_clear(ssl);
   }
 }

 void ssl_read_buffer_clear(SSL *ssl) {
   clear_buffer(&ssl->s3->read_buffer);
 }


 int ssl_write_buffer_is_pending(const SSL *ssl) {
   return ssl->s3->write_buffer.len > 0;
 }

 OPENSSL_COMPILE_ASSERT(SSL3_RT_HEADER_LENGTH * 2 +
                            SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD * 2 +
                            SSL3_RT_MAX_PLAIN_LENGTH <= 0xffff,
                        maximum_tls_write_buffer_too_large);

 OPENSSL_COMPILE_ASSERT(DTLS1_RT_HEADER_LENGTH +
                            SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD +
                            SSL3_RT_MAX_PLAIN_LENGTH <= 0xffff,
                        maximum_dtls_write_buffer_too_large);

 int ssl_write_buffer_init(SSL *ssl, uint8_t **out_ptr, size_t max_len) {
   SSL3_BUFFER *buf = &ssl->s3->write_buffer;

   if (buf->buf != NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return 0;
   }

   size_t header_len = ssl_seal_prefix_len(ssl);

   /* TODO(davidben): This matches the original behavior in keeping the malloc
    * size consistent. Does this matter? |cap| could just be |max_len|. */
   size_t cap = SSL3_RT_MAX_PLAIN_LENGTH + SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD;
   if (SSL_IS_DTLS(ssl)) {
     cap += DTLS1_RT_HEADER_LENGTH;
   } else {
     cap += SSL3_RT_HEADER_LENGTH;
     if (ssl->mode & SSL_MODE_CBC_RECORD_SPLITTING) {
       cap += SSL3_RT_HEADER_LENGTH + SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD;
     }
   }

   if (max_len > cap) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
     return 0;
   }

   if (!setup_buffer(buf, header_len, cap)) {
     return 0;
   }
   *out_ptr = buf->buf + buf->offset;
   return 1;
 }

 void ssl_write_buffer_set_len(SSL *ssl, size_t len) {
   SSL3_BUFFER *buf = &ssl->s3->write_buffer;

   if (len > buf->cap) {
     abort();
   }
   buf->len = len;
 }

 static int tls_write_buffer_flush(SSL *ssl) {
   SSL3_BUFFER *buf = &ssl->s3->write_buffer;

   while (buf->len > 0) {
     ssl->rwstate = SSL_WRITING;
     int ret = BIO_write(ssl->wbio, buf->buf + buf->offset, buf->len);
     if (ret <= 0) {
       return ret;
     }
     ssl->rwstate = SSL_NOTHING;
     consume_buffer(buf, (size_t)ret);
   }
   ssl_write_buffer_clear(ssl);
   return 1;
 }

 static int dtls_write_buffer_flush(SSL *ssl) {
   SSL3_BUFFER *buf = &ssl->s3->write_buffer;
   if (buf->len == 0) {
     return 1;
   }

   ssl->rwstate = SSL_WRITING;
   int ret = BIO_write(ssl->wbio, buf->buf + buf->offset, buf->len);
   if (ret <= 0) {
     /* If the write failed, drop the write buffer anyway. Datagram transports
      * can't write half a packet, so the caller is expected to retry from the
      * top. */
     ssl_write_buffer_clear(ssl);
     return ret;
   }
   ssl->rwstate = SSL_NOTHING;
   ssl_write_buffer_clear(ssl);
   return 1;
 }

 int ssl_write_buffer_flush(SSL *ssl) {
   if (ssl->wbio == NULL) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_BIO_NOT_SET);
     return -1;
   }
   ERR_clear_system_error();

   if (SSL_IS_DTLS(ssl)) {
     return dtls_write_buffer_flush(ssl);
   } else {
     return tls_write_buffer_flush(ssl);
   }
 }

 void ssl_write_buffer_clear(SSL *ssl) {
   clear_buffer(&ssl->s3->write_buffer);
 }
	/* 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 <limits.h>
	#include <stdlib.h>
	#include <string.h>

	#include <openssl/bio.h>
	#include <openssl/err.h>
	#include <openssl/mem.h>
	#include <openssl/type_check.h>

	#include "internal.h"


	OPENSSL_COMPILE_ASSERT(0xffff <= INT_MAX, uint16_fits_in_int);

	OPENSSL_COMPILE_ASSERT((SSL3_ALIGN_PAYLOAD & (SSL3_ALIGN_PAYLOAD - 1)) == 0,
	align_to_a_power_of_two);

	/* setup_buffer initializes \|buf\| with capacity \|cap\|, aligned such that data
	* written after \|header_len\| is aligned to a \|SSL3_ALIGN_PAYLOAD\|-byte
	* boundary. It returns one on success and zero on error. */
	static int setup_buffer(SSL3_BUFFER *buf, size_t header_len, size_t cap) {
	if (buf->buf != NULL \|\| cap > 0xffff) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return 0;
	}

	/* Add up to \|SSL3_ALIGN_PAYLOAD\| - 1 bytes of slack for alignment. */
	buf->buf = OPENSSL_malloc(cap + SSL3_ALIGN_PAYLOAD - 1);
	if (buf->buf == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return 0;
	}

	/* Arrange the buffer such that the record body is aligned. */
	buf->offset = (0 - header_len - (uintptr_t)buf->buf) &
	(SSL3_ALIGN_PAYLOAD - 1);
	buf->len = 0;
	buf->cap = cap;
	return 1;
	}

	static void consume_buffer(SSL3_BUFFER *buf, size_t len) {
	if (len > buf->len) {
	abort();
	}
	buf->offset += (uint16_t)len;
	buf->len -= (uint16_t)len;
	buf->cap -= (uint16_t)len;
	}

	static void clear_buffer(SSL3_BUFFER *buf) {
	OPENSSL_free(buf->buf);
	memset(buf, 0, sizeof(SSL3_BUFFER));
	}

	OPENSSL_COMPILE_ASSERT(DTLS1_RT_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH <=
	0xffff,
	maximum_read_buffer_too_large);

	/* setup_read_buffer initializes the read buffer if not already initialized. It
	* returns one on success and zero on failure. */
	static int setup_read_buffer(SSL *ssl) {
	SSL3_BUFFER *buf = &ssl->s3->read_buffer;

	if (buf->buf != NULL) {
	return 1;
	}

	size_t header_len = ssl_record_prefix_len(ssl);
	size_t cap = SSL3_RT_MAX_ENCRYPTED_LENGTH;
	if (SSL_IS_DTLS(ssl)) {
	cap += DTLS1_RT_HEADER_LENGTH;
	} else {
	cap += SSL3_RT_HEADER_LENGTH;
	}

	return setup_buffer(buf, header_len, cap);
	}

	uint8_t ssl_read_buffer(SSL ssl) {
	return ssl->s3->read_buffer.buf + ssl->s3->read_buffer.offset;
	}

	size_t ssl_read_buffer_len(const SSL *ssl) {
	return ssl->s3->read_buffer.len;
	}

	static int dtls_read_buffer_next_packet(SSL *ssl) {
	SSL3_BUFFER *buf = &ssl->s3->read_buffer;

	if (buf->len > 0) {
	/* It is an error to call \|dtls_read_buffer_extend\| when the read buffer is
	* not empty. */
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return -1;
	}

	/* Read a single packet from \|ssl->rbio\|. \|buf->cap\| must fit in an int. */
	ssl->rwstate = SSL_READING;
	int ret = BIO_read(ssl->rbio, buf->buf + buf->offset, (int)buf->cap);
	if (ret <= 0) {
	return ret;
	}
	ssl->rwstate = SSL_NOTHING;
	/* \|BIO_read\| was bound by \|buf->cap\|, so this cannot overflow. */
	buf->len = (uint16_t)ret;
	return 1;
	}

	static int tls_read_buffer_extend_to(SSL *ssl, size_t len) {
	SSL3_BUFFER *buf = &ssl->s3->read_buffer;

	if (len > buf->cap) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
	return -1;
	}

	/* Read until the target length is reached. */
	while (buf->len < len) {
	/* The amount of data to read is bounded by \|buf->cap\|, which must fit in an
	* int. */
	ssl->rwstate = SSL_READING;
	int ret = BIO_read(ssl->rbio, buf->buf + buf->offset + buf->len,
	(int)(len - buf->len));
	if (ret <= 0) {
	return ret;
	}
	ssl->rwstate = SSL_NOTHING;
	/* \|BIO_read\| was bound by \|buf->cap - buf->len\|, so this cannot
	* overflow. */
	buf->len += (uint16_t)ret;
	}

	return 1;
	}

	int ssl_read_buffer_extend_to(SSL *ssl, size_t len) {
	/* \|ssl_read_buffer_extend_to\| implicitly discards any consumed data. */
	ssl_read_buffer_discard(ssl);

	if (!setup_read_buffer(ssl)) {
	return -1;
	}

	if (ssl->rbio == NULL) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_BIO_NOT_SET);
	return -1;
	}

	ERR_clear_system_error();

	int ret;
	if (SSL_IS_DTLS(ssl)) {
	/* \|len\| is ignored for a datagram transport. */
	ret = dtls_read_buffer_next_packet(ssl);
	} else {
	ret = tls_read_buffer_extend_to(ssl, len);
	}

	if (ret <= 0) {
	/* If the buffer was empty originally and remained empty after attempting to
	* extend it, release the buffer until the next attempt. */
	ssl_read_buffer_discard(ssl);
	}
	return ret;
	}

	void ssl_read_buffer_consume(SSL *ssl, size_t len) {
	SSL3_BUFFER *buf = &ssl->s3->read_buffer;

	consume_buffer(buf, len);
	if (!SSL_IS_DTLS(ssl)) {
	/* The TLS stack never reads beyond the current record, so there will never
	* be unconsumed data. If read-ahead is ever reimplemented,
	* \|ssl_read_buffer_discard\| will require a \|memcpy\| to shift the excess
	* back to the front of the buffer, to ensure there is enough space for the
	* next record. */
	assert(buf->len == 0);
	}
	}

	void ssl_read_buffer_discard(SSL *ssl) {
	if (ssl->s3->read_buffer.len == 0) {
	ssl_read_buffer_clear(ssl);
	}
	}

	void ssl_read_buffer_clear(SSL *ssl) {
	clear_buffer(&ssl->s3->read_buffer);
	}


	int ssl_write_buffer_is_pending(const SSL *ssl) {
	return ssl->s3->write_buffer.len > 0;
	}

	OPENSSL_COMPILE_ASSERT(SSL3_RT_HEADER_LENGTH * 2 +
	SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD * 2 +
	SSL3_RT_MAX_PLAIN_LENGTH <= 0xffff,
	maximum_tls_write_buffer_too_large);

	OPENSSL_COMPILE_ASSERT(DTLS1_RT_HEADER_LENGTH +
	SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD +
	SSL3_RT_MAX_PLAIN_LENGTH <= 0xffff,
	maximum_dtls_write_buffer_too_large);

	int ssl_write_buffer_init(SSL ssl, uint8_t *out_ptr, size_t max_len) {
	SSL3_BUFFER *buf = &ssl->s3->write_buffer;

	if (buf->buf != NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return 0;
	}

	size_t header_len = ssl_seal_prefix_len(ssl);

	/* TODO(davidben): This matches the original behavior in keeping the malloc
	* size consistent. Does this matter? \|cap\| could just be \|max_len\|. */
	size_t cap = SSL3_RT_MAX_PLAIN_LENGTH + SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD;
	if (SSL_IS_DTLS(ssl)) {
	cap += DTLS1_RT_HEADER_LENGTH;
	} else {
	cap += SSL3_RT_HEADER_LENGTH;
	if (ssl->mode & SSL_MODE_CBC_RECORD_SPLITTING) {
	cap += SSL3_RT_HEADER_LENGTH + SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD;
	}
	}

	if (max_len > cap) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
	return 0;
	}

	if (!setup_buffer(buf, header_len, cap)) {
	return 0;
	}
	*out_ptr = buf->buf + buf->offset;
	return 1;
	}

	void ssl_write_buffer_set_len(SSL *ssl, size_t len) {
	SSL3_BUFFER *buf = &ssl->s3->write_buffer;

	if (len > buf->cap) {
	abort();
	}
	buf->len = len;
	}

	static int tls_write_buffer_flush(SSL *ssl) {
	SSL3_BUFFER *buf = &ssl->s3->write_buffer;

	while (buf->len > 0) {
	ssl->rwstate = SSL_WRITING;
	int ret = BIO_write(ssl->wbio, buf->buf + buf->offset, buf->len);
	if (ret <= 0) {
	return ret;
	}
	ssl->rwstate = SSL_NOTHING;
	consume_buffer(buf, (size_t)ret);
	}
	ssl_write_buffer_clear(ssl);
	return 1;
	}

	static int dtls_write_buffer_flush(SSL *ssl) {
	SSL3_BUFFER *buf = &ssl->s3->write_buffer;
	if (buf->len == 0) {
	return 1;
	}

	ssl->rwstate = SSL_WRITING;
	int ret = BIO_write(ssl->wbio, buf->buf + buf->offset, buf->len);
	if (ret <= 0) {
	/* If the write failed, drop the write buffer anyway. Datagram transports
	* can't write half a packet, so the caller is expected to retry from the
	* top. */
	ssl_write_buffer_clear(ssl);
	return ret;
	}
	ssl->rwstate = SSL_NOTHING;
	ssl_write_buffer_clear(ssl);
	return 1;
	}

	int ssl_write_buffer_flush(SSL *ssl) {
	if (ssl->wbio == NULL) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_BIO_NOT_SET);
	return -1;
	}
	ERR_clear_system_error();

	if (SSL_IS_DTLS(ssl)) {
	return dtls_write_buffer_flush(ssl);
	} else {
	return tls_write_buffer_flush(ssl);
	}
	}

	void ssl_write_buffer_clear(SSL *ssl) {
	clear_buffer(&ssl->s3->write_buffer);
	}