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 0x00000080L + /* 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