From 4c654523c703645f8b517389b6da537c5a9e5168 Mon Sep 17 00:00:00 2001
From: Adam Langley <agl@chromium.org>
Date: Thu, 24 Jan 2013 16:22:07 -0500
Subject: [PATCH] handshake_cutthrough
Enables SSL3+ clients to send application data immediately following the
Finished message even when negotiating full-handshakes. With this
patch, clients can negotiate SSL connections in 1-RTT even when
performing full-handshakes.
---
apps/s_client.c | 13 +++++++++++++
ssl/s3_clnt.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++------
ssl/s3_lib.c | 15 ++++++++++++++-
ssl/ssl.h | 10 +++++++++-
ssl/ssl3.h | 1 +
ssl/ssl_lib.c | 42 ++++++++++++++++++++++++++++++++++++++++++
ssl/ssl_locl.h | 2 ++
ssl/ssltest.c | 12 ++++++++++++
test/testssl | 3 +++
9 files changed, 144 insertions(+), 8 deletions(-)
diff --git a/apps/s_client.c b/apps/s_client.c
index 3ba6605..791e277 100644
--- a/apps/s_client.c
+++ b/apps/s_client.c
@@ -361,6 +361,7 @@ static void sc_usage(void)
BIO_printf(bio_err," -nextprotoneg arg - enable NPN extension, considering named protocols supported (comma-separated list)\n");
# endif
#endif
+ BIO_printf(bio_err," -cutthrough - enable 1-RTT full-handshake for strong ciphers\n");
BIO_printf(bio_err," -legacy_renegotiation - enable use of legacy renegotiation (dangerous)\n");
#ifndef OPENSSL_NO_SRTP
BIO_printf(bio_err," -use_srtp profiles - Offer SRTP key management with a colon-separated profile list\n");
@@ -577,6 +578,7 @@ int MAIN(int argc, char **argv)
EVP_PKEY *key = NULL;
char *CApath=NULL,*CAfile=NULL,*cipher=NULL;
int reconnect=0,badop=0,verify=SSL_VERIFY_NONE,bugs=0;
+ int cutthrough=0;
int crlf=0;
int write_tty,read_tty,write_ssl,read_ssl,tty_on,ssl_pending;
SSL_CTX *ctx=NULL;
@@ -883,6 +885,8 @@ int MAIN(int argc, char **argv)
}
# endif
#endif
+ else if (strcmp(*argv,"-cutthrough") == 0)
+ cutthrough=1;
else if (strcmp(*argv,"-serverpref") == 0)
off|=SSL_OP_CIPHER_SERVER_PREFERENCE;
else if (strcmp(*argv,"-legacy_renegotiation") == 0)
@@ -1158,6 +1162,15 @@ bad:
SSL_CTX_set_next_proto_select_cb(ctx, next_proto_cb, &next_proto);
#endif
+ /* Enable handshake cutthrough for client connections using
+ * strong ciphers. */
+ if (cutthrough)
+ {
+ int ssl_mode = SSL_CTX_get_mode(ctx);
+ ssl_mode |= SSL_MODE_HANDSHAKE_CUTTHROUGH;
+ SSL_CTX_set_mode(ctx, ssl_mode);
+ }
+
if (state) SSL_CTX_set_info_callback(ctx,apps_ssl_info_callback);
if (cipher != NULL)
if(!SSL_CTX_set_cipher_list(ctx,cipher)) {
diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c
index a6b3c01..3d3fd64 100644
--- a/ssl/s3_clnt.c
+++ b/ssl/s3_clnt.c
@@ -215,6 +215,12 @@ int ssl3_connect(SSL *s)
}
#endif
+ if (SSL_get_mode(s) & SSL_MODE_HANDSHAKE_CUTTHROUGH)
+ {
+ /* Send app data along with CCS/Finished */
+ s->s3->flags |= SSL3_FLAGS_DELAY_CLIENT_FINISHED;
+ }
+
for (;;)
{
state=s->state;
@@ -526,14 +532,32 @@ int ssl3_connect(SSL *s)
}
else
{
-#ifndef OPENSSL_NO_TLSEXT
- /* Allow NewSessionTicket if ticket expected */
- if (s->tlsext_ticket_expected)
- s->s3->tmp.next_state=SSL3_ST_CR_SESSION_TICKET_A;
+ if ((SSL_get_mode(s) & SSL_MODE_HANDSHAKE_CUTTHROUGH)
+ && ssl3_can_cutthrough(s)
+ && s->s3->previous_server_finished_len == 0 /* no cutthrough on renegotiation (would complicate the state machine) */
+ )
+ {
+ if (s->s3->flags & SSL3_FLAGS_DELAY_CLIENT_FINISHED)
+ {
+ s->state=SSL3_ST_CUTTHROUGH_COMPLETE;
+ s->s3->flags|=SSL3_FLAGS_POP_BUFFER;
+ s->s3->delay_buf_pop_ret=0;
+ }
+ else
+ {
+ s->s3->tmp.next_state=SSL3_ST_CUTTHROUGH_COMPLETE;
+ }
+ }
else
+ {
+#ifndef OPENSSL_NO_TLSEXT
+ /* Allow NewSessionTicket if ticket expected */
+ if (s->tlsext_ticket_expected)
+ s->s3->tmp.next_state=SSL3_ST_CR_SESSION_TICKET_A;
+ else
#endif
-
- s->s3->tmp.next_state=SSL3_ST_CR_FINISHED_A;
+ s->s3->tmp.next_state=SSL3_ST_CR_FINISHED_A;
+ }
}
s->init_num=0;
break;
@@ -581,6 +605,24 @@ int ssl3_connect(SSL *s)
s->state=s->s3->tmp.next_state;
break;
+ case SSL3_ST_CUTTHROUGH_COMPLETE:
+#ifndef OPENSSL_NO_TLSEXT
+ /* Allow NewSessionTicket if ticket expected */
+ if (s->tlsext_ticket_expected)
+ s->state=SSL3_ST_CR_SESSION_TICKET_A;
+ else
+#endif
+ s->state=SSL3_ST_CR_FINISHED_A;
+
+ /* SSL_write() will take care of flushing buffered data if
+ * DELAY_CLIENT_FINISHED is set.
+ */
+ if (!(s->s3->flags & SSL3_FLAGS_DELAY_CLIENT_FINISHED))
+ ssl_free_wbio_buffer(s);
+ ret = 1;
+ goto end;
+ /* break; */
+
case SSL_ST_OK:
/* clean a few things up */
ssl3_cleanup_key_block(s);
diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index c4ef273..1865c70 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -4211,9 +4211,22 @@ int ssl3_write(SSL *s, const void *buf, int len)
static int ssl3_read_internal(SSL *s, void *buf, int len, int peek)
{
- int ret;
+ int n,ret;
clear_sys_error();
+ if ((s->s3->flags & SSL3_FLAGS_POP_BUFFER) && (s->wbio == s->bbio))
+ {
+ /* Deal with an application that calls SSL_read() when handshake data
+ * is yet to be written.
+ */
+ if (BIO_wpending(s->wbio) > 0)
+ {
+ s->rwstate=SSL_WRITING;
+ n=BIO_flush(s->wbio);
+ if (n <= 0) return(n);
+ s->rwstate=SSL_NOTHING;
+ }
+ }
if (s->s3->renegotiate) ssl3_renegotiate_check(s);
s->s3->in_read_app_data=1;
ret=s->method->ssl_read_bytes(s,SSL3_RT_APPLICATION_DATA,buf,len,peek);
diff --git a/ssl/ssl.h b/ssl/ssl.h
index 1f255c3..3e31fb5 100644
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -644,6 +644,7 @@ struct ssl_session_st
* TLS only.) "Released" buffers are put onto a free-list in the context
* or just freed (depending on the context's setting for freelist_max_len). */
#define SSL_MODE_RELEASE_BUFFERS 0x00000010L
+
/* Send the current time in the Random fields of the ClientHello and
* ServerHello records for compatibility with hypothetical implementations
* that require it.
@@ -651,6 +652,11 @@ struct ssl_session_st
#define SSL_MODE_SEND_CLIENTHELLO_TIME 0x00000020L
#define SSL_MODE_SEND_SERVERHELLO_TIME 0x00000040L
+/* When set, clients may send application data before receipt of CCS
+ * and Finished. This mode enables full-handshakes to 'complete' in
+ * one RTT. */
+#define SSL_MODE_HANDSHAKE_CUTTHROUGH 0x00000200L
+
/* Note: SSL[_CTX]_set_{options,mode} use |= op on the previous value,
* they cannot be used to clear bits. */
@@ -1424,10 +1430,12 @@ extern "C" {
/* Is the SSL_connection established? */
#define SSL_get_state(a) SSL_state(a)
#define SSL_is_init_finished(a) (SSL_state(a) == SSL_ST_OK)
-#define SSL_in_init(a) (SSL_state(a)&SSL_ST_INIT)
+#define SSL_in_init(a) ((SSL_state(a)&SSL_ST_INIT) && \
+ !SSL_cutthrough_complete(a))
#define SSL_in_before(a) (SSL_state(a)&SSL_ST_BEFORE)
#define SSL_in_connect_init(a) (SSL_state(a)&SSL_ST_CONNECT)
#define SSL_in_accept_init(a) (SSL_state(a)&SSL_ST_ACCEPT)
+int SSL_cutthrough_complete(const SSL *s);
/* The following 2 states are kept in ssl->rstate when reads fail,
* you should not need these */
diff --git a/ssl/ssl3.h b/ssl/ssl3.h
index cb8b249..9a61b71 100644
--- a/ssl/ssl3.h
+++ b/ssl/ssl3.h
@@ -556,6 +556,7 @@ typedef struct ssl3_state_st
/*client */
/* extra state */
#define SSL3_ST_CW_FLUSH (0x100|SSL_ST_CONNECT)
+#define SSL3_ST_CUTTHROUGH_COMPLETE (0x101|SSL_ST_CONNECT)
#ifndef OPENSSL_NO_SCTP
#define DTLS1_SCTP_ST_CW_WRITE_SOCK (0x310|SSL_ST_CONNECT)
#define DTLS1_SCTP_ST_CR_READ_SOCK (0x320|SSL_ST_CONNECT)
diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 6dbc3c1..7892928 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -3225,6 +3225,48 @@ void SSL_set_msg_callback(SSL *ssl, void (*cb)(int write_p, int version, int con
SSL_callback_ctrl(ssl, SSL_CTRL_SET_MSG_CALLBACK, (void (*)(void))cb);
}
+int SSL_cutthrough_complete(const SSL *s)
+ {
+ return (!s->server && /* cutthrough only applies to clients */
+ !s->hit && /* full-handshake */
+ s->version >= SSL3_VERSION &&
+ s->s3->in_read_app_data == 0 && /* cutthrough only applies to write() */
+ (SSL_get_mode((SSL*)s) & SSL_MODE_HANDSHAKE_CUTTHROUGH) && /* cutthrough enabled */
+ ssl3_can_cutthrough(s) && /* cutthrough allowed */
+ s->s3->previous_server_finished_len == 0 && /* not a renegotiation handshake */
+ (s->state == SSL3_ST_CR_SESSION_TICKET_A || /* ready to write app-data*/
+ s->state == SSL3_ST_CR_FINISHED_A));
+ }
+
+int ssl3_can_cutthrough(const SSL *s)
+ {
+ const SSL_CIPHER *c;
+
+ /* require a strong enough cipher */
+ if (SSL_get_cipher_bits(s, NULL) < 128)
+ return 0;
+
+ /* require ALPN or NPN extension */
+ if (!s->s3->alpn_selected
+#ifndef OPENSSL_NO_NEXTPROTONEG
+ && !s->s3->next_proto_neg_seen
+#endif
+ )
+ {
+ return 0;
+ }
+
+ /* require a forward-secret cipher */
+ c = SSL_get_current_cipher(s);
+ if (!c || (c->algorithm_mkey != SSL_kEDH &&
+ c->algorithm_mkey != SSL_kEECDH))
+ {
+ return 0;
+ }
+
+ return 1;
+ }
+
/* Allocates new EVP_MD_CTX and sets pointer to it into given pointer
* vairable, freeing EVP_MD_CTX previously stored in that variable, if
* any. If EVP_MD pointer is passed, initializes ctx with this md
diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index e485907..3b1d644 100644
--- a/ssl/ssl_locl.h
+++ b/ssl/ssl_locl.h
@@ -1126,6 +1126,8 @@ int tls12_get_sigid(const EVP_PKEY *pk);
const EVP_MD *tls12_get_hash(unsigned char hash_alg);
#endif
+
+int ssl3_can_cutthrough(const SSL *s);
EVP_MD_CTX* ssl_replace_hash(EVP_MD_CTX **hash,const EVP_MD *md) ;
void ssl_clear_hash_ctx(EVP_MD_CTX **hash);
int ssl_add_serverhello_renegotiate_ext(SSL *s, unsigned char *p, int *len,
diff --git a/ssl/ssltest.c b/ssl/ssltest.c
index 4f80be8..28fa223 100644
--- a/ssl/ssltest.c
+++ b/ssl/ssltest.c
@@ -369,6 +369,7 @@ static void sv_usage(void)
" (default is sect163r2).\n");
#endif
fprintf(stderr," -test_cipherlist - verifies the order of the ssl cipher lists\n");
+ fprintf(stderr," -cutthrough - enable 1-RTT full-handshake for strong ciphers\n");
}
static void print_details(SSL *c_ssl, const char *prefix)
@@ -549,6 +550,7 @@ int main(int argc, char *argv[])
#ifdef OPENSSL_FIPS
int fips_mode=0;
#endif
+ int cutthrough = 0;
verbose = 0;
debug = 0;
@@ -765,6 +767,10 @@ int main(int argc, char *argv[])
{
test_cipherlist = 1;
}
+ else if (strcmp(*argv, "-cutthrough") == 0)
+ {
+ cutthrough = 1;
+ }
else
{
fprintf(stderr,"unknown option %s\n",*argv);
@@ -906,6 +912,12 @@ bad:
SSL_CTX_set_cipher_list(c_ctx,cipher);
SSL_CTX_set_cipher_list(s_ctx,cipher);
}
+ if (cutthrough)
+ {
+ int ssl_mode = SSL_CTX_get_mode(c_ctx);
+ ssl_mode |= SSL_MODE_HANDSHAKE_CUTTHROUGH;
+ SSL_CTX_set_mode(c_ctx, ssl_mode);
+ }
#ifndef OPENSSL_NO_DH
if (!no_dhe)
diff --git a/test/testssl b/test/testssl
index 4e8542b..b5f90ba 100644
--- a/test/testssl
+++ b/test/testssl
@@ -70,6 +70,9 @@ $ssltest -client_auth $CA $extra || exit 1
echo test sslv2/sslv3 with both client and server authentication
$ssltest -server_auth -client_auth $CA $extra || exit 1
+echo test sslv2/sslv3 with both client and server authentication and handshake cutthrough
+$ssltest -server_auth -client_auth -cutthrough $CA $extra || exit 1
+
echo test sslv2 via BIO pair
$ssltest -bio_pair -ssl2 $extra || exit 1
--
1.9.1.423.g4596e3a