mirror of https://github.com/ipxe/ipxe.git
[tls] Support fragmentation of transmitted records
Large transmitted records may arise if we have long client certificate chains or if a client sends a large block of data (such as a large HTTP POST payload). Fragment records as needed to comply with the value that we advertise via the max_fragment_length extension. Signed-off-by: Michael Brown <mcb30@ipxe.org>pull/448/merge
Michael Brown
parent
f115cfcf99
commit
a289b4b8c2
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@ -465,6 +465,17 @@ struct tls_connection {
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struct tls_server server;
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};
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/** Advertised maximum fragment length */
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#define TLS_MAX_FRAGMENT_LENGTH_VALUE TLS_MAX_FRAGMENT_LENGTH_4096
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/** TX maximum fragment length
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*
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* TLS requires us to limit our transmitted records to the maximum
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* fragment length that we attempt to negotiate, even if the server
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* does not respect this choice.
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*/
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#define TLS_TX_BUFSIZE 4096
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/** RX I/O buffer size
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*
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* The maximum fragment length extension is optional, and many common
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197
src/net/tls.c
197
src/net/tls.c
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@ -1256,7 +1256,7 @@ static int tls_client_hello ( struct tls_connection *tls,
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max_fragment_length_ext->type = htons ( TLS_MAX_FRAGMENT_LENGTH );
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max_fragment_length_ext->len
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= htons ( sizeof ( max_fragment_length_ext->data ) );
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max_fragment_length_ext->data.max = TLS_MAX_FRAGMENT_LENGTH_4096;
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max_fragment_length_ext->data.max = TLS_MAX_FRAGMENT_LENGTH_VALUE;
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/* Construct supported signature algorithms extension */
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signature_algorithms_ext = &extensions->signature_algorithms;
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@ -2923,7 +2923,34 @@ static void tls_hmac_list ( struct tls_cipherspec *cipherspec,
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}
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/**
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* Allocate I/O buffer for transmitted record
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* Calculate maximum additional length required for transmitted record(s)
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*
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* @v tls TLS connection
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* @v len I/O buffer payload length
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* @ret reserve Maximum additional length to reserve
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*/
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static size_t tls_iob_reserved ( struct tls_connection *tls, size_t len ) {
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struct tls_cipherspec *cipherspec = &tls->tx.cipherspec.active;
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struct tls_cipher_suite *suite = cipherspec->suite;
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struct cipher_algorithm *cipher = suite->cipher;
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struct tls_header *tlshdr;
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unsigned int count;
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size_t each;
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/* Calculate number of records (allowing for zero-length records) */
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count = ( len ? ( ( len + TLS_TX_BUFSIZE - 1 ) / TLS_TX_BUFSIZE ) : 1 );
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/* Calculate maximum additional length per record */
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each = ( sizeof ( *tlshdr ) + suite->record_iv_len + suite->mac_len +
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( is_block_cipher ( cipher ) ? cipher->blocksize : 0 ) +
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cipher->authsize );
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/* Calculate maximum total additional length */
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return ( count * each );
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}
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/**
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* Allocate I/O buffer for transmitted record(s)
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*
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* @v tls TLS connection
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* @v len I/O buffer payload length
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@ -2931,41 +2958,25 @@ static void tls_hmac_list ( struct tls_cipherspec *cipherspec,
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*/
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static struct io_buffer * tls_alloc_iob ( struct tls_connection *tls,
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size_t len ) {
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struct tls_cipherspec *cipherspec = &tls->tx.cipherspec.active;
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struct tls_cipher_suite *suite = cipherspec->suite;
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struct cipher_algorithm *cipher = suite->cipher;
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struct tls_header *tlshdr;
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struct io_buffer *iobuf;
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size_t pre_len;
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size_t padded_len;
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size_t post_len;
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size_t reserve;
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/* Calculate length of padded data */
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padded_len = ( len + suite->mac_len );
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if ( is_block_cipher ( cipher ) ) {
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padded_len = ( ( padded_len + 1 + cipher->blocksize - 1 ) &
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~( cipher->blocksize - 1 ) );
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assert ( padded_len > ( len + suite->mac_len ) );
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}
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/* Calculate lengths before and after padded data */
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pre_len = ( sizeof ( *tlshdr ) + suite->record_iv_len );
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post_len = cipher->authsize;
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/* Calculate maximum additional length to reserve */
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reserve = tls_iob_reserved ( tls, len );
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/* Allocate I/O buffer */
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iobuf = xfer_alloc_iob ( &tls->cipherstream,
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( pre_len + padded_len + post_len ) );
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iobuf = xfer_alloc_iob ( &tls->cipherstream, ( reserve + len ) );
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if ( ! iobuf )
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return NULL;
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/* Reserve space */
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iob_reserve ( iobuf, pre_len );
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iob_reserve ( iobuf, reserve );
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return iobuf;
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}
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/**
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* Send plaintext record
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* Send plaintext record(s)
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*
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* @v tls TLS connection
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* @v type Record type
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@ -2980,71 +2991,114 @@ static int tls_send_record ( struct tls_connection *tls, unsigned int type,
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struct digest_algorithm *digest = suite->digest;
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struct {
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uint8_t fixed[suite->fixed_iv_len];
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uint8_t record[suite->record_iv_len];
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uint8_t rec[suite->record_iv_len];
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} __attribute__ (( packed )) iv;
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struct tls_auth_header authhdr;
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struct tls_header *tlshdr;
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uint8_t mac[digest->digestsize];
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const void *plaintext;
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const void *encrypt;
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void *ciphertext;
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size_t record_len;
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size_t encrypt_len;
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size_t pad_len;
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size_t len;
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int rc;
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/* Record plaintext pointer and length */
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plaintext = iobuf->data;
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len = iob_len ( iobuf );
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/* Add to handshake digest if applicable */
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if ( type == TLS_TYPE_HANDSHAKE )
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tls_add_handshake ( tls, iobuf->data, iob_len ( iobuf ) );
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tls_add_handshake ( tls, plaintext, len );
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/* Construct initialisation vector */
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memcpy ( iv.fixed, cipherspec->fixed_iv, sizeof ( iv.fixed ) );
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if ( ( rc = tls_generate_random ( tls, iv.record,
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sizeof ( iv.record ) ) ) != 0 ) {
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goto err_random;
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}
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/* Start constructing ciphertext at start of reserved space */
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iob_push ( iobuf, tls_iob_reserved ( tls, len ) );
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iob_unput ( iobuf, iob_len ( iobuf ) );
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/* Construct authentication data */
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authhdr.seq = cpu_to_be64 ( tls->tx.seq );
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authhdr.header.type = type;
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authhdr.header.version = htons ( tls->version );
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authhdr.header.length = htons ( iob_len ( iobuf ) );
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/* Construct records */
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do {
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/* Limit length of this record (may be zero) */
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record_len = len;
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if ( record_len > TLS_TX_BUFSIZE )
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record_len = TLS_TX_BUFSIZE;
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/* Append MAC, if applicable */
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if ( suite->mac_len ) {
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tls_hmac ( cipherspec, &authhdr, iobuf->data,
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iob_len ( iobuf ), mac );
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/* Construct and set initialisation vector */
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memcpy ( iv.fixed, cipherspec->fixed_iv, sizeof ( iv.fixed ) );
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if ( ( rc = tls_generate_random ( tls, iv.rec,
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sizeof ( iv.rec ) ) ) != 0 ) {
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goto err_random;
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}
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cipher_setiv ( cipher, cipherspec->cipher_ctx, &iv,
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sizeof ( iv ) );
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/* Construct and process authentication data */
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authhdr.seq = cpu_to_be64 ( tls->tx.seq );
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authhdr.header.type = type;
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authhdr.header.version = htons ( tls->version );
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authhdr.header.length = htons ( record_len );
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if ( suite->mac_len ) {
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tls_hmac ( cipherspec, &authhdr, plaintext, record_len,
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mac );
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}
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if ( is_auth_cipher ( cipher ) ) {
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cipher_encrypt ( cipher, cipherspec->cipher_ctx,
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&authhdr, NULL, sizeof ( authhdr ) );
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}
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/* Calculate encryption length */
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encrypt_len = ( record_len + suite->mac_len );
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if ( is_block_cipher ( cipher ) ) {
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pad_len = ( ( ( cipher->blocksize - 1 ) &
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-( encrypt_len + 1 ) ) + 1 );
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} else {
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pad_len = 0;
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}
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encrypt_len += pad_len;
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/* Add record header */
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tlshdr = iob_put ( iobuf, sizeof ( *tlshdr ) );
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tlshdr->type = type;
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tlshdr->version = htons ( tls->version );
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tlshdr->length = htons ( sizeof ( iv.rec ) + encrypt_len +
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cipher->authsize );
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/* Add record initialisation vector, if applicable */
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memcpy ( iob_put ( iobuf, sizeof ( iv.rec ) ), iv.rec,
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sizeof ( iv.rec ) );
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/* Copy plaintext data if necessary */
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ciphertext = iob_put ( iobuf, record_len );
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assert ( ciphertext <= plaintext );
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if ( encrypt_len > record_len ) {
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memmove ( ciphertext, plaintext, record_len );
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encrypt = ciphertext;
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} else {
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encrypt = plaintext;
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}
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/* Add MAC, if applicable */
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memcpy ( iob_put ( iobuf, suite->mac_len ), mac,
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suite->mac_len );
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}
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/* Append padding, if applicable */
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if ( is_block_cipher ( cipher ) ) {
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pad_len = ( ( ( cipher->blocksize - 1 ) &
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-( iob_len ( iobuf ) + 1 ) ) + 1 );
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/* Add padding, if applicable */
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memset ( iob_put ( iobuf, pad_len ), ( pad_len - 1 ), pad_len );
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assert ( ! ( iob_len ( iobuf ) & ( cipher->blocksize - 1 ) ) );
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}
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DBGC2 ( tls, "Sending plaintext data:\n" );
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DBGC2_HDA ( tls, 0, iobuf->data, iob_len ( iobuf ) );
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/* Set initialisation vector */
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cipher_setiv ( cipher, cipherspec->cipher_ctx, &iv, sizeof ( iv ) );
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/* Encrypt data and append authentication tag */
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DBGC2 ( tls, "Sending plaintext data:\n" );
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DBGC2_HDA ( tls, 0, encrypt, encrypt_len );
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cipher_encrypt ( cipher, cipherspec->cipher_ctx, encrypt,
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ciphertext, encrypt_len );
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cipher_auth ( cipher, cipherspec->cipher_ctx,
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iob_put ( iobuf, cipher->authsize ) );
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/* Process authentication data, if applicable */
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if ( is_auth_cipher ( cipher ) ) {
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cipher_encrypt ( cipher, cipherspec->cipher_ctx, &authhdr,
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NULL, sizeof ( authhdr ) );
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}
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/* Move to next record */
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tls->tx.seq += 1;
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plaintext += record_len;
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len -= record_len;
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/* Encrypt data to be transmitted and append authentication tag */
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cipher_encrypt ( cipher, cipherspec->cipher_ctx, iobuf->data,
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iobuf->data, iob_len ( iobuf ) );
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cipher_auth ( cipher, cipherspec->cipher_ctx,
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iob_put ( iobuf, cipher->authsize ) );
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/* Prepend record header and initialisation vector */
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memcpy ( iob_push ( iobuf, sizeof ( iv.record ) ), iv.record,
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sizeof ( iv.record ) );
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tlshdr = iob_push ( iobuf, sizeof ( *tlshdr ) );
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tlshdr->type = type;
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tlshdr->version = htons ( tls->version );
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tlshdr->length = htons ( iob_len ( iobuf ) - sizeof ( *tlshdr ) );
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} while ( len );
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/* Send ciphertext */
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if ( ( rc = xfer_deliver_iob ( &tls->cipherstream,
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@ -3054,9 +3108,6 @@ static int tls_send_record ( struct tls_connection *tls, unsigned int type,
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goto err_deliver;
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}
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/* Update TX state machine to next record */
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tls->tx.seq += 1;
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assert ( iobuf == NULL );
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return 0;
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