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
|
|
@ -465,6 +465,17 @@ struct tls_connection {
|
|||
struct tls_server server;
|
||||
};
|
||||
|
||||
/** Advertised maximum fragment length */
|
||||
#define TLS_MAX_FRAGMENT_LENGTH_VALUE TLS_MAX_FRAGMENT_LENGTH_4096
|
||||
|
||||
/** TX maximum fragment length
|
||||
*
|
||||
* TLS requires us to limit our transmitted records to the maximum
|
||||
* fragment length that we attempt to negotiate, even if the server
|
||||
* does not respect this choice.
|
||||
*/
|
||||
#define TLS_TX_BUFSIZE 4096
|
||||
|
||||
/** RX I/O buffer size
|
||||
*
|
||||
* The maximum fragment length extension is optional, and many common
|
||||
|
|
|
|||
181
src/net/tls.c
181
src/net/tls.c
|
|
@ -1256,7 +1256,7 @@ static int tls_client_hello ( struct tls_connection *tls,
|
|||
max_fragment_length_ext->type = htons ( TLS_MAX_FRAGMENT_LENGTH );
|
||||
max_fragment_length_ext->len
|
||||
= htons ( sizeof ( max_fragment_length_ext->data ) );
|
||||
max_fragment_length_ext->data.max = TLS_MAX_FRAGMENT_LENGTH_4096;
|
||||
max_fragment_length_ext->data.max = TLS_MAX_FRAGMENT_LENGTH_VALUE;
|
||||
|
||||
/* Construct supported signature algorithms extension */
|
||||
signature_algorithms_ext = &extensions->signature_algorithms;
|
||||
|
|
@ -2923,7 +2923,34 @@ static void tls_hmac_list ( struct tls_cipherspec *cipherspec,
|
|||
}
|
||||
|
||||
/**
|
||||
* Allocate I/O buffer for transmitted record
|
||||
* Calculate maximum additional length required for transmitted record(s)
|
||||
*
|
||||
* @v tls TLS connection
|
||||
* @v len I/O buffer payload length
|
||||
* @ret reserve Maximum additional length to reserve
|
||||
*/
|
||||
static size_t tls_iob_reserved ( struct tls_connection *tls, size_t len ) {
|
||||
struct tls_cipherspec *cipherspec = &tls->tx.cipherspec.active;
|
||||
struct tls_cipher_suite *suite = cipherspec->suite;
|
||||
struct cipher_algorithm *cipher = suite->cipher;
|
||||
struct tls_header *tlshdr;
|
||||
unsigned int count;
|
||||
size_t each;
|
||||
|
||||
/* Calculate number of records (allowing for zero-length records) */
|
||||
count = ( len ? ( ( len + TLS_TX_BUFSIZE - 1 ) / TLS_TX_BUFSIZE ) : 1 );
|
||||
|
||||
/* Calculate maximum additional length per record */
|
||||
each = ( sizeof ( *tlshdr ) + suite->record_iv_len + suite->mac_len +
|
||||
( is_block_cipher ( cipher ) ? cipher->blocksize : 0 ) +
|
||||
cipher->authsize );
|
||||
|
||||
/* Calculate maximum total additional length */
|
||||
return ( count * each );
|
||||
}
|
||||
|
||||
/**
|
||||
* Allocate I/O buffer for transmitted record(s)
|
||||
*
|
||||
* @v tls TLS connection
|
||||
* @v len I/O buffer payload length
|
||||
|
|
@ -2931,41 +2958,25 @@ static void tls_hmac_list ( struct tls_cipherspec *cipherspec,
|
|||
*/
|
||||
static struct io_buffer * tls_alloc_iob ( struct tls_connection *tls,
|
||||
size_t len ) {
|
||||
struct tls_cipherspec *cipherspec = &tls->tx.cipherspec.active;
|
||||
struct tls_cipher_suite *suite = cipherspec->suite;
|
||||
struct cipher_algorithm *cipher = suite->cipher;
|
||||
struct tls_header *tlshdr;
|
||||
struct io_buffer *iobuf;
|
||||
size_t pre_len;
|
||||
size_t padded_len;
|
||||
size_t post_len;
|
||||
size_t reserve;
|
||||
|
||||
/* Calculate length of padded data */
|
||||
padded_len = ( len + suite->mac_len );
|
||||
if ( is_block_cipher ( cipher ) ) {
|
||||
padded_len = ( ( padded_len + 1 + cipher->blocksize - 1 ) &
|
||||
~( cipher->blocksize - 1 ) );
|
||||
assert ( padded_len > ( len + suite->mac_len ) );
|
||||
}
|
||||
|
||||
/* Calculate lengths before and after padded data */
|
||||
pre_len = ( sizeof ( *tlshdr ) + suite->record_iv_len );
|
||||
post_len = cipher->authsize;
|
||||
/* Calculate maximum additional length to reserve */
|
||||
reserve = tls_iob_reserved ( tls, len );
|
||||
|
||||
/* Allocate I/O buffer */
|
||||
iobuf = xfer_alloc_iob ( &tls->cipherstream,
|
||||
( pre_len + padded_len + post_len ) );
|
||||
iobuf = xfer_alloc_iob ( &tls->cipherstream, ( reserve + len ) );
|
||||
if ( ! iobuf )
|
||||
return NULL;
|
||||
|
||||
/* Reserve space */
|
||||
iob_reserve ( iobuf, pre_len );
|
||||
iob_reserve ( iobuf, reserve );
|
||||
|
||||
return iobuf;
|
||||
}
|
||||
|
||||
/**
|
||||
* Send plaintext record
|
||||
* Send plaintext record(s)
|
||||
*
|
||||
* @v tls TLS connection
|
||||
* @v type Record type
|
||||
|
|
@ -2980,71 +2991,114 @@ static int tls_send_record ( struct tls_connection *tls, unsigned int type,
|
|||
struct digest_algorithm *digest = suite->digest;
|
||||
struct {
|
||||
uint8_t fixed[suite->fixed_iv_len];
|
||||
uint8_t record[suite->record_iv_len];
|
||||
uint8_t rec[suite->record_iv_len];
|
||||
} __attribute__ (( packed )) iv;
|
||||
struct tls_auth_header authhdr;
|
||||
struct tls_header *tlshdr;
|
||||
uint8_t mac[digest->digestsize];
|
||||
const void *plaintext;
|
||||
const void *encrypt;
|
||||
void *ciphertext;
|
||||
size_t record_len;
|
||||
size_t encrypt_len;
|
||||
size_t pad_len;
|
||||
size_t len;
|
||||
int rc;
|
||||
|
||||
/* Record plaintext pointer and length */
|
||||
plaintext = iobuf->data;
|
||||
len = iob_len ( iobuf );
|
||||
|
||||
/* Add to handshake digest if applicable */
|
||||
if ( type == TLS_TYPE_HANDSHAKE )
|
||||
tls_add_handshake ( tls, iobuf->data, iob_len ( iobuf ) );
|
||||
tls_add_handshake ( tls, plaintext, len );
|
||||
|
||||
/* Construct initialisation vector */
|
||||
/* Start constructing ciphertext at start of reserved space */
|
||||
iob_push ( iobuf, tls_iob_reserved ( tls, len ) );
|
||||
iob_unput ( iobuf, iob_len ( iobuf ) );
|
||||
|
||||
/* Construct records */
|
||||
do {
|
||||
/* Limit length of this record (may be zero) */
|
||||
record_len = len;
|
||||
if ( record_len > TLS_TX_BUFSIZE )
|
||||
record_len = TLS_TX_BUFSIZE;
|
||||
|
||||
/* Construct and set initialisation vector */
|
||||
memcpy ( iv.fixed, cipherspec->fixed_iv, sizeof ( iv.fixed ) );
|
||||
if ( ( rc = tls_generate_random ( tls, iv.record,
|
||||
sizeof ( iv.record ) ) ) != 0 ) {
|
||||
if ( ( rc = tls_generate_random ( tls, iv.rec,
|
||||
sizeof ( iv.rec ) ) ) != 0 ) {
|
||||
goto err_random;
|
||||
}
|
||||
cipher_setiv ( cipher, cipherspec->cipher_ctx, &iv,
|
||||
sizeof ( iv ) );
|
||||
|
||||
/* Construct authentication data */
|
||||
/* Construct and process authentication data */
|
||||
authhdr.seq = cpu_to_be64 ( tls->tx.seq );
|
||||
authhdr.header.type = type;
|
||||
authhdr.header.version = htons ( tls->version );
|
||||
authhdr.header.length = htons ( iob_len ( iobuf ) );
|
||||
|
||||
/* Append MAC, if applicable */
|
||||
authhdr.header.length = htons ( record_len );
|
||||
if ( suite->mac_len ) {
|
||||
tls_hmac ( cipherspec, &authhdr, iobuf->data,
|
||||
iob_len ( iobuf ), mac );
|
||||
memcpy ( iob_put ( iobuf, suite->mac_len ), mac,
|
||||
suite->mac_len );
|
||||
tls_hmac ( cipherspec, &authhdr, plaintext, record_len,
|
||||
mac );
|
||||
}
|
||||
if ( is_auth_cipher ( cipher ) ) {
|
||||
cipher_encrypt ( cipher, cipherspec->cipher_ctx,
|
||||
&authhdr, NULL, sizeof ( authhdr ) );
|
||||
}
|
||||
|
||||
/* Append padding, if applicable */
|
||||
/* Calculate encryption length */
|
||||
encrypt_len = ( record_len + suite->mac_len );
|
||||
if ( is_block_cipher ( cipher ) ) {
|
||||
pad_len = ( ( ( cipher->blocksize - 1 ) &
|
||||
-( iob_len ( iobuf ) + 1 ) ) + 1 );
|
||||
-( encrypt_len + 1 ) ) + 1 );
|
||||
} else {
|
||||
pad_len = 0;
|
||||
}
|
||||
encrypt_len += pad_len;
|
||||
|
||||
/* Add record header */
|
||||
tlshdr = iob_put ( iobuf, sizeof ( *tlshdr ) );
|
||||
tlshdr->type = type;
|
||||
tlshdr->version = htons ( tls->version );
|
||||
tlshdr->length = htons ( sizeof ( iv.rec ) + encrypt_len +
|
||||
cipher->authsize );
|
||||
|
||||
/* Add record initialisation vector, if applicable */
|
||||
memcpy ( iob_put ( iobuf, sizeof ( iv.rec ) ), iv.rec,
|
||||
sizeof ( iv.rec ) );
|
||||
|
||||
/* Copy plaintext data if necessary */
|
||||
ciphertext = iob_put ( iobuf, record_len );
|
||||
assert ( ciphertext <= plaintext );
|
||||
if ( encrypt_len > record_len ) {
|
||||
memmove ( ciphertext, plaintext, record_len );
|
||||
encrypt = ciphertext;
|
||||
} else {
|
||||
encrypt = plaintext;
|
||||
}
|
||||
|
||||
/* Add MAC, if applicable */
|
||||
memcpy ( iob_put ( iobuf, suite->mac_len ), mac,
|
||||
suite->mac_len );
|
||||
|
||||
/* Add padding, if applicable */
|
||||
memset ( iob_put ( iobuf, pad_len ), ( pad_len - 1 ), pad_len );
|
||||
assert ( ! ( iob_len ( iobuf ) & ( cipher->blocksize - 1 ) ) );
|
||||
}
|
||||
|
||||
/* Encrypt data and append authentication tag */
|
||||
DBGC2 ( tls, "Sending plaintext data:\n" );
|
||||
DBGC2_HDA ( tls, 0, iobuf->data, iob_len ( iobuf ) );
|
||||
|
||||
/* Set initialisation vector */
|
||||
cipher_setiv ( cipher, cipherspec->cipher_ctx, &iv, sizeof ( iv ) );
|
||||
|
||||
/* Process authentication data, if applicable */
|
||||
if ( is_auth_cipher ( cipher ) ) {
|
||||
cipher_encrypt ( cipher, cipherspec->cipher_ctx, &authhdr,
|
||||
NULL, sizeof ( authhdr ) );
|
||||
}
|
||||
|
||||
/* Encrypt data to be transmitted and append authentication tag */
|
||||
cipher_encrypt ( cipher, cipherspec->cipher_ctx, iobuf->data,
|
||||
iobuf->data, iob_len ( iobuf ) );
|
||||
DBGC2_HDA ( tls, 0, encrypt, encrypt_len );
|
||||
cipher_encrypt ( cipher, cipherspec->cipher_ctx, encrypt,
|
||||
ciphertext, encrypt_len );
|
||||
cipher_auth ( cipher, cipherspec->cipher_ctx,
|
||||
iob_put ( iobuf, cipher->authsize ) );
|
||||
|
||||
/* Prepend record header and initialisation vector */
|
||||
memcpy ( iob_push ( iobuf, sizeof ( iv.record ) ), iv.record,
|
||||
sizeof ( iv.record ) );
|
||||
tlshdr = iob_push ( iobuf, sizeof ( *tlshdr ) );
|
||||
tlshdr->type = type;
|
||||
tlshdr->version = htons ( tls->version );
|
||||
tlshdr->length = htons ( iob_len ( iobuf ) - sizeof ( *tlshdr ) );
|
||||
/* Move to next record */
|
||||
tls->tx.seq += 1;
|
||||
plaintext += record_len;
|
||||
len -= record_len;
|
||||
|
||||
} while ( len );
|
||||
|
||||
/* Send ciphertext */
|
||||
if ( ( rc = xfer_deliver_iob ( &tls->cipherstream,
|
||||
|
|
@ -3054,9 +3108,6 @@ static int tls_send_record ( struct tls_connection *tls, unsigned int type,
|
|||
goto err_deliver;
|
||||
}
|
||||
|
||||
/* Update TX state machine to next record */
|
||||
tls->tx.seq += 1;
|
||||
|
||||
assert ( iobuf == NULL );
|
||||
return 0;
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue