mirror of https://github.com/ipxe/ipxe.git
[tls] Add support for Ephemeral Diffie-Hellman key exchange
Signed-off-by: Michael Brown <mcb30@ipxe.org>pull/785/head
Michael Brown
parent
ea33ea33c0
commit
6b2c94d3a7
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@ -403,6 +403,7 @@ struct tls_connection {
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#define TLS_RX_ALIGN 16
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extern struct tls_key_exchange_algorithm tls_pubkey_exchange_algorithm;
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extern struct tls_key_exchange_algorithm tls_dhe_exchange_algorithm;
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extern int add_tls ( struct interface *xfer, const char *name,
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struct x509_root *root, struct private_key *key );
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246
src/net/tls.c
246
src/net/tls.c
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@ -49,6 +49,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
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#include <ipxe/rbg.h>
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#include <ipxe/validator.h>
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#include <ipxe/job.h>
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#include <ipxe/dhe.h>
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#include <ipxe/tls.h>
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#include <config/crypto.h>
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@ -109,6 +110,10 @@ FILE_LICENCE ( GPL2_OR_LATER );
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#define EINFO_EINVAL_TICKET \
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__einfo_uniqify ( EINFO_EINVAL, 0x0e, \
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"Invalid New Session Ticket record")
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#define EINVAL_KEY_EXCHANGE __einfo_error ( EINFO_EINVAL_KEY_EXCHANGE )
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#define EINFO_EINVAL_KEY_EXCHANGE \
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__einfo_uniqify ( EINFO_EINVAL, 0x0f, \
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"Invalid Server Key Exchange record" )
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#define EIO_ALERT __einfo_error ( EINFO_EIO_ALERT )
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#define EINFO_EIO_ALERT \
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__einfo_uniqify ( EINFO_EIO, 0x01, \
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@ -177,6 +182,10 @@ FILE_LICENCE ( GPL2_OR_LATER );
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#define EINFO_EPERM_RENEG_VERIFY \
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__einfo_uniqify ( EINFO_EPERM, 0x05, \
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"Secure renegotiation verification failed" )
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#define EPERM_KEY_EXCHANGE __einfo_error ( EINFO_EPERM_KEY_EXCHANGE )
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#define EINFO_EPERM_KEY_EXCHANGE \
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__einfo_uniqify ( EINFO_EPERM, 0x06, \
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"ServerKeyExchange verification failed" )
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#define EPROTO_VERSION __einfo_error ( EINFO_EPROTO_VERSION )
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#define EINFO_EPROTO_VERSION \
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__einfo_uniqify ( EINFO_EPROTO, 0x01, \
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@ -915,6 +924,44 @@ tls_signature_hash_algorithm ( struct pubkey_algorithm *pubkey,
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return NULL;
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}
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/**
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* Find TLS signature algorithm
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*
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* @v code Signature and hash algorithm identifier
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* @ret pubkey Public key algorithm, or NULL
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*/
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static struct pubkey_algorithm *
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tls_signature_hash_pubkey ( struct tls_signature_hash_id code ) {
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struct tls_signature_hash_algorithm *sig_hash;
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/* Identify signature and hash algorithm */
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for_each_table_entry ( sig_hash, TLS_SIG_HASH_ALGORITHMS ) {
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if ( sig_hash->code.signature == code.signature )
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return sig_hash->pubkey;
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}
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return NULL;
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}
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/**
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* Find TLS hash algorithm
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*
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* @v code Signature and hash algorithm identifier
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* @ret digest Digest algorithm, or NULL
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*/
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static struct digest_algorithm *
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tls_signature_hash_digest ( struct tls_signature_hash_id code ) {
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struct tls_signature_hash_algorithm *sig_hash;
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/* Identify signature and hash algorithm */
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for_each_table_entry ( sig_hash, TLS_SIG_HASH_ALGORITHMS ) {
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if ( sig_hash->code.hash == code.hash )
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return sig_hash->digest;
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}
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return NULL;
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}
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/******************************************************************************
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*
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* Handshake verification
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@ -1277,6 +1324,205 @@ struct tls_key_exchange_algorithm tls_pubkey_exchange_algorithm = {
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.exchange = tls_send_client_key_exchange_pubkey,
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};
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/**
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* Transmit Client Key Exchange record using DHE key exchange
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*
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* @v tls TLS connection
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* @ret rc Return status code
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*/
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static int tls_send_client_key_exchange_dhe ( struct tls_connection *tls ) {
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struct tls_cipherspec *cipherspec = &tls->tx_cipherspec_pending;
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struct pubkey_algorithm *pubkey;
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struct digest_algorithm *digest;
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int use_sig_hash = tls_version ( tls, TLS_VERSION_TLS_1_2 );
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uint8_t private[ sizeof ( tls->client_random.random ) ];
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const struct {
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uint16_t len;
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uint8_t data[0];
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} __attribute__ (( packed )) *dh_val[3];
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const struct {
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struct tls_signature_hash_id sig_hash[use_sig_hash];
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uint16_t signature_len;
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uint8_t signature[0];
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} __attribute__ (( packed )) *sig;
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const void *data;
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size_t remaining;
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size_t frag_len;
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unsigned int i;
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int rc;
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/* Parse ServerKeyExchange */
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data = tls->server_key;
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remaining = tls->server_key_len;
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for ( i = 0 ; i < ( sizeof ( dh_val ) / sizeof ( dh_val[0] ) ) ; i++ ){
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dh_val[i] = data;
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if ( ( sizeof ( *dh_val[i] ) > remaining ) ||
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( ntohs ( dh_val[i]->len ) > ( remaining -
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sizeof ( *dh_val[i] ) ) )){
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DBGC ( tls, "TLS %p received underlength "
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"ServerKeyExchange\n", tls );
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DBGC_HDA ( tls, 0, tls->server_key,
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tls->server_key_len );
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rc = -EINVAL_KEY_EXCHANGE;
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goto err_header;
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}
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frag_len = ( sizeof ( *dh_val[i] ) + ntohs ( dh_val[i]->len ));
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data += frag_len;
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remaining -= frag_len;
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}
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sig = data;
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if ( ( sizeof ( *sig ) > remaining ) ||
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( ntohs ( sig->signature_len ) > ( remaining -
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sizeof ( *sig ) ) ) ) {
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DBGC ( tls, "TLS %p received underlength ServerKeyExchange\n",
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tls );
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DBGC_HDA ( tls, 0, tls->server_key, tls->server_key_len );
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rc = -EINVAL_KEY_EXCHANGE;
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goto err_header;
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}
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/* Identify signature and hash algorithm */
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if ( use_sig_hash ) {
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pubkey = tls_signature_hash_pubkey ( sig->sig_hash[0] );
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digest = tls_signature_hash_digest ( sig->sig_hash[0] );
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if ( ( ! pubkey ) || ( ! digest ) ) {
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DBGC ( tls, "TLS %p ServerKeyExchange unsupported "
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"signature and hash algorithm\n", tls );
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rc = -ENOTSUP_SIG_HASH;
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goto err_sig_hash;
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}
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if ( pubkey != cipherspec->suite->pubkey ) {
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DBGC ( tls, "TLS %p ServerKeyExchange incorrect "
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"signature algorithm %s (expected %s)\n", tls,
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pubkey->name, cipherspec->suite->pubkey->name );
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rc = -EPERM_KEY_EXCHANGE;
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goto err_sig_hash;
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}
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} else {
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pubkey = cipherspec->suite->pubkey;
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digest = &md5_sha1_algorithm;
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}
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/* Verify signature */
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{
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const void *signature = sig->signature;
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size_t signature_len = ntohs ( sig->signature_len );
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uint8_t ctx[digest->ctxsize];
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uint8_t hash[digest->digestsize];
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/* Calculate digest */
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digest_init ( digest, ctx );
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digest_update ( digest, ctx, &tls->client_random,
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sizeof ( tls->client_random ) );
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digest_update ( digest, ctx, tls->server_random,
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sizeof ( tls->server_random ) );
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digest_update ( digest, ctx, tls->server_key,
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( tls->server_key_len - remaining ) );
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digest_final ( digest, ctx, hash );
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/* Verify signature */
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if ( ( rc = pubkey_verify ( pubkey, cipherspec->pubkey_ctx,
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digest, hash, signature,
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signature_len ) ) != 0 ) {
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DBGC ( tls, "TLS %p ServerKeyExchange failed "
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"verification\n", tls );
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DBGC_HDA ( tls, 0, tls->server_key,
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tls->server_key_len );
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rc = -EPERM_KEY_EXCHANGE;
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goto err_verify;
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}
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}
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/* Generate Diffie-Hellman private key */
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if ( ( rc = tls_generate_random ( tls, private,
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sizeof ( private ) ) ) != 0 ) {
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goto err_random;
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}
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/* Construct pre-master secret and ClientKeyExchange record */
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{
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typeof ( dh_val[0] ) dh_p = dh_val[0];
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typeof ( dh_val[1] ) dh_g = dh_val[1];
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typeof ( dh_val[2] ) dh_ys = dh_val[2];
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size_t len = ntohs ( dh_p->len );
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struct {
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uint32_t type_length;
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uint16_t dh_xs_len;
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uint8_t dh_xs[len];
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} __attribute__ (( packed )) *key_xchg;
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struct {
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uint8_t pre_master_secret[len];
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typeof ( *key_xchg ) key_xchg;
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} *dynamic;
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uint8_t *pre_master_secret;
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/* Allocate space */
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dynamic = malloc ( sizeof ( *dynamic ) );
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if ( ! dynamic ) {
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rc = -ENOMEM;
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goto err_alloc;
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}
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pre_master_secret = dynamic->pre_master_secret;
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key_xchg = &dynamic->key_xchg;
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key_xchg->type_length =
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( cpu_to_le32 ( TLS_CLIENT_KEY_EXCHANGE ) |
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htonl ( sizeof ( *key_xchg ) -
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sizeof ( key_xchg->type_length ) ) );
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key_xchg->dh_xs_len = htons ( len );
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/* Calculate pre-master secret and client public value */
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if ( ( rc = dhe_key ( dh_p->data, len,
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dh_g->data, ntohs ( dh_g->len ),
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dh_ys->data, ntohs ( dh_ys->len ),
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private, sizeof ( private ),
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key_xchg->dh_xs,
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pre_master_secret ) ) != 0 ) {
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DBGC ( tls, "TLS %p could not calculate DHE key: %s\n",
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tls, strerror ( rc ) );
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goto err_dhe_key;
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}
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/* Strip leading zeroes from pre-master secret */
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while ( len && ( ! *pre_master_secret ) ) {
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pre_master_secret++;
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len--;
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}
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/* Generate master secret */
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tls_generate_master_secret ( tls, pre_master_secret, len );
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/* Generate keys */
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if ( ( rc = tls_generate_keys ( tls ) ) != 0 ) {
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DBGC ( tls, "TLS %p could not generate keys: %s\n",
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tls, strerror ( rc ) );
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goto err_generate_keys;
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}
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/* Transmit Client Key Exchange record */
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if ( ( rc = tls_send_handshake ( tls, key_xchg,
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sizeof ( *key_xchg ) ) ) !=0){
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goto err_send_handshake;
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}
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err_send_handshake:
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err_generate_keys:
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err_dhe_key:
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free ( dynamic );
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}
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err_alloc:
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err_random:
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err_verify:
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err_sig_hash:
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err_header:
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return rc;
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}
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/** Ephemeral Diffie-Hellman key exchange algorithm */
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struct tls_key_exchange_algorithm tls_dhe_exchange_algorithm = {
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.name = "dhe",
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.exchange = tls_send_client_key_exchange_dhe,
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};
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/**
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* Transmit Client Key Exchange record
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*
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