tls1_clnt.c

00001 /*
00002  * Copyright (c) 2007, Cameron Rich
00003  * 
00004  * All rights reserved.
00005  * 
00006  * Redistribution and use in source and binary forms, with or without 
00007  * modification, are permitted provided that the following conditions are met:
00008  *
00009  * * Redistributions of source code must retain the above copyright notice, 
00010  *   this list of conditions and the following disclaimer.
00011  * * Redistributions in binary form must reproduce the above copyright notice, 
00012  *   this list of conditions and the following disclaimer in the documentation 
00013  *   and/or other materials provided with the distribution.
00014  * * Neither the name of the axTLS project nor the names of its contributors 
00015  *   may be used to endorse or promote products derived from this software 
00016  *   without specific prior written permission.
00017  *
00018  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00019  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00020  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
00021  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
00022  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00023  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
00024  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00025  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00026  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00027  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00028  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00029  */
00030 
00031 #include <stdlib.h>
00032 #include <string.h>
00033 #include <time.h>
00034 #include <stdio.h>
00035 #include "os_port.h"
00036 #include "ssl.h"
00037 
00038 #ifdef CONFIG_SSL_ENABLE_CLIENT        /* all commented out if no client */
00039 
00040 static int send_client_hello(SSL *ssl);
00041 static int process_server_hello(SSL *ssl);
00042 static int process_server_hello_done(SSL *ssl);
00043 static int send_client_key_xchg(SSL *ssl);
00044 static int process_cert_req(SSL *ssl);
00045 static int send_cert_verify(SSL *ssl);
00046 
00047 /*
00048  * Establish a new SSL connection to an SSL server.
00049  */
00050 EXP_FUNC SSL * STDCALL ssl_client_new(SSL *ssl, int client_fd, const
00051         uint8_t *session_id, uint8_t sess_id_size)
00052 {
00053     SSL_CTX *ssl_ctx = ssl->ssl_ctx;
00054     ssl_new(ssl, client_fd);
00055     ssl->version = SSL_PROTOCOL_VERSION_MAX; /* try top version first */
00056 
00057     if (session_id && ssl_ctx->num_sessions)
00058     {
00059         if (sess_id_size > SSL_SESSION_ID_SIZE) /* validity check */
00060         {
00061             ssl_free(ssl);
00062             return NULL;
00063         }
00064 
00065         memcpy(ssl->session_id, session_id, sess_id_size);
00066         ssl->sess_id_size = sess_id_size;
00067         SET_SSL_FLAG(SSL_SESSION_RESUME);   /* just flag for later */
00068     }
00069 
00070     SET_SSL_FLAG(SSL_IS_CLIENT);
00071     do_client_connect(ssl);
00072     return ssl;
00073 }
00074 
00075 /*
00076  * Process the handshake record.
00077  */
00078 int do_clnt_handshake(SSL *ssl, int handshake_type, uint8_t *buf, int hs_len)
00079 {
00080     int ret;
00081 
00082     /* To get here the state must be valid */
00083     switch (handshake_type)
00084     {
00085         case HS_SERVER_HELLO:
00086             ret = process_server_hello(ssl);
00087             break;
00088 
00089         case HS_CERTIFICATE:
00090             ret = process_certificate(ssl, &ssl->x509_ctx);
00091             break;
00092 
00093         case HS_SERVER_HELLO_DONE:
00094             if ((ret = process_server_hello_done(ssl)) == SSL_OK)
00095             {
00096                 if (IS_SET_SSL_FLAG(SSL_HAS_CERT_REQ))
00097                 {
00098                     if ((ret = send_certificate(ssl)) == SSL_OK &&
00099                         (ret = send_client_key_xchg(ssl)) == SSL_OK)
00100                     {
00101                         send_cert_verify(ssl);
00102                     }
00103                 }
00104                 else
00105                 {
00106                     ret = send_client_key_xchg(ssl);
00107                 }
00108 
00109                 if (ret == SSL_OK && 
00110                      (ret = send_change_cipher_spec(ssl)) == SSL_OK)
00111                 {
00112                     ret = send_finished(ssl);
00113                 }
00114             }
00115             break;
00116 
00117         case HS_CERT_REQ:
00118             ret = process_cert_req(ssl);
00119             break;
00120 
00121         case HS_FINISHED:
00122             ret = process_finished(ssl, buf, hs_len);
00123             disposable_free(ssl);   /* free up some memory */
00124             /* note: client renegotiation is not allowed after this */
00125             break;
00126 
00127         case HS_HELLO_REQUEST:
00128             disposable_new(ssl);
00129             ret = do_client_connect(ssl);
00130             break;
00131 
00132         default:
00133             ret = SSL_ERROR_INVALID_HANDSHAKE;
00134             break;
00135     }
00136 
00137     return ret;
00138 }
00139 
00140 /*
00141  * Do the handshaking from the beginning.
00142  */
00143 int do_client_connect(SSL *ssl)
00144 {
00145     int ret = SSL_OK;
00146 
00147     send_client_hello(ssl);                 /* send the client hello */
00148     ssl->bm_remaining_bytes = 0;
00149     ssl->next_state = HS_SERVER_HELLO;
00150     ssl->hs_status = SSL_NOT_OK;            /* not connected */
00151 
00152     /* sit in a loop until it all looks good */
00153     if (!IS_SET_SSL_FLAG(SSL_CONNECT_IN_PARTS))
00154     {
00155         while (ssl->hs_status != SSL_OK)
00156         {
00157             ret = read_record(ssl);
00158             if (ret < SSL_OK)
00159                 break;
00160             ret = process_data(ssl, NULL, 0);
00161             if (ret < SSL_OK)
00162                 break;    
00163         }
00164         ssl->hs_status = ret;            /* connected? */    
00165     }
00166     return ret;
00167 }
00168 
00169 /*
00170  * Send the initial client hello.
00171  */
00172 static int send_client_hello(SSL *ssl)
00173 {
00174     uint8_t *buf = ssl->bm_data;
00175     time_t tm = time(NULL);
00176     uint8_t *tm_ptr = &buf[6]; /* time will go here */
00177     int i, offset;
00178 
00179     buf[0] = HS_CLIENT_HELLO;
00180     buf[1] = 0;
00181     buf[2] = 0;
00182     /* byte 3 is calculated later */
00183     buf[4] = 0x03;
00184     buf[5] = ssl->version & 0x0f;
00185 
00186     /* client random value - spec says that 1st 4 bytes are big endian time */
00187     *tm_ptr++ = (uint8_t)(((long)tm & 0xff000000) >> 24);
00188     *tm_ptr++ = (uint8_t)(((long)tm & 0x00ff0000) >> 16);
00189     *tm_ptr++ = (uint8_t)(((long)tm & 0x0000ff00) >> 8);
00190     *tm_ptr++ = (uint8_t)(((long)tm & 0x000000ff));
00191     get_random(SSL_RANDOM_SIZE-4, &buf[10]);
00192     memcpy(ssl->dc->client_random, &buf[6], SSL_RANDOM_SIZE);
00193     offset = 6 + SSL_RANDOM_SIZE;
00194 
00195     /* give session resumption a go */
00196     if (IS_SET_SSL_FLAG(SSL_SESSION_RESUME))    /* set initially by user */
00197     {
00198         buf[offset++] = ssl->sess_id_size;
00199         memcpy(&buf[offset], ssl->session_id, ssl->sess_id_size);
00200         offset += ssl->sess_id_size;
00201         CLR_SSL_FLAG(SSL_SESSION_RESUME);       /* clear so we can set later */
00202     }
00203     else
00204     {
00205         /* no session id - because no session resumption just yet */
00206         buf[offset++] = 0;
00207     }
00208 
00209     buf[offset++] = 0;              /* number of ciphers */
00210     buf[offset++] = NUM_PROTOCOLS*2;/* number of ciphers */
00211 
00212     /* put all our supported protocols in our request */
00213     for (i = 0; i < NUM_PROTOCOLS; i++)
00214     {
00215         buf[offset++] = 0;          /* cipher we are using */
00216         buf[offset++] = ssl_prot_prefs[i];
00217     }
00218 
00219     buf[offset++] = 1;              /* no compression */
00220     buf[offset++] = 0;
00221     buf[3] = offset - 4;            /* handshake size */
00222 
00223     return send_packet(ssl, PT_HANDSHAKE_PROTOCOL, NULL, offset);
00224 }
00225 
00226 /*
00227  * Process the server hello.
00228  */
00229 static int process_server_hello(SSL *ssl)
00230 {
00231     uint8_t *buf = ssl->bm_data;
00232     int pkt_size = ssl->bm_index;
00233     int num_sessions = ssl->ssl_ctx->num_sessions;
00234     uint8_t sess_id_size;
00235     int offset, ret = SSL_OK;
00236 
00237     /* check that we are talking to a TLSv1 server */
00238     uint8_t version = (buf[0] << 4) + buf[1];
00239     if (version > SSL_PROTOCOL_VERSION_MAX)
00240     {
00241         version = SSL_PROTOCOL_VERSION_MAX;
00242     }
00243     else if (ssl->version < SSL_PROTOCOL_MIN_VERSION)
00244     {
00245         ret = SSL_ERROR_INVALID_VERSION;
00246         ssl_display_error(ret);
00247         goto error;
00248     }
00249 
00250     ssl->version = version;
00251 
00252     /* get the server random value */
00253     memcpy(ssl->dc->server_random, &buf[2], SSL_RANDOM_SIZE);
00254     offset = 2 + SSL_RANDOM_SIZE; /* skip of session id size */
00255     sess_id_size = buf[offset++];
00256 
00257     if (sess_id_size > SSL_SESSION_ID_SIZE)
00258     {
00259         ret = SSL_ERROR_INVALID_SESSION;
00260         goto error;
00261     }
00262 
00263     if (num_sessions)
00264     {
00265         ssl->session = ssl_session_update(num_sessions,
00266                 ssl->ssl_ctx->ssl_sessions, ssl, &buf[offset]);
00267         memcpy(ssl->session->session_id, &buf[offset], sess_id_size);
00268 
00269         /* pad the rest with 0's */
00270         if (sess_id_size < SSL_SESSION_ID_SIZE)
00271         {
00272             memset(&ssl->session->session_id[sess_id_size], 0,
00273                 SSL_SESSION_ID_SIZE-sess_id_size);
00274         }
00275     }
00276 
00277     memcpy(ssl->session_id, &buf[offset], sess_id_size);
00278     ssl->sess_id_size = sess_id_size;
00279     offset += sess_id_size;
00280 
00281     /* get the real cipher we are using */
00282     ssl->cipher = buf[++offset];
00283     ssl->next_state = IS_SET_SSL_FLAG(SSL_SESSION_RESUME) ? 
00284                                         HS_FINISHED : HS_CERTIFICATE;
00285 
00286     offset++;   // skip the compr
00287     PARANOIA_CHECK(pkt_size, offset);
00288     ssl->dc->bm_proc_index = offset+1; 
00289 
00290 error:
00291     return ret;
00292 }
00293 
00294 /**
00295  * Process the server hello done message.
00296  */
00297 static int process_server_hello_done(SSL *ssl)
00298 {
00299     ssl->next_state = HS_FINISHED;
00300     return SSL_OK;
00301 }
00302 
00303 /*
00304  * Send a client key exchange message.
00305  */
00306 static int send_client_key_xchg(SSL *ssl)
00307 {
00308     uint8_t *buf = ssl->bm_data;
00309     uint8_t premaster_secret[SSL_SECRET_SIZE];
00310     int enc_secret_size = -1;
00311 
00312     buf[0] = HS_CLIENT_KEY_XCHG;
00313     buf[1] = 0;
00314 
00315     premaster_secret[0] = 0x03; /* encode the version number */
00316     premaster_secret[1] = SSL_PROTOCOL_MINOR_VERSION; /* must be TLS 1.1 */
00317     get_random(SSL_SECRET_SIZE-2, &premaster_secret[2]);
00318     DISPLAY_RSA(ssl, ssl->x509_ctx->rsa_ctx);
00319 
00320     /* rsa_ctx->bi_ctx is not thread-safe */
00321     SSL_CTX_LOCK(ssl->ssl_ctx->mutex);
00322     enc_secret_size = RSA_encrypt(ssl->x509_ctx->rsa_ctx, premaster_secret,
00323             SSL_SECRET_SIZE, &buf[6], 0);
00324     SSL_CTX_UNLOCK(ssl->ssl_ctx->mutex);
00325 
00326     buf[2] = (enc_secret_size + 2) >> 8;
00327     buf[3] = (enc_secret_size + 2) & 0xff;
00328     buf[4] = enc_secret_size >> 8;
00329     buf[5] = enc_secret_size & 0xff;
00330 
00331     generate_master_secret(ssl, premaster_secret);
00332 
00333     return send_packet(ssl, PT_HANDSHAKE_PROTOCOL, NULL, enc_secret_size+6);
00334 }
00335 
00336 /*
00337  * Process the certificate request.
00338  */
00339 static int process_cert_req(SSL *ssl)
00340 {
00341     uint8_t *buf = &ssl->bm_data[ssl->dc->bm_proc_index];
00342     int ret = SSL_OK;
00343     int offset = (buf[2] << 4) + buf[3];
00344     int pkt_size = ssl->bm_index;
00345 
00346     /* don't do any processing - we will send back an RSA certificate anyway */
00347     ssl->next_state = HS_SERVER_HELLO_DONE;
00348     SET_SSL_FLAG(SSL_HAS_CERT_REQ);
00349     ssl->dc->bm_proc_index += offset;
00350     PARANOIA_CHECK(pkt_size, offset);
00351 error:
00352     return ret;
00353 }
00354 
00355 /*
00356  * Send a certificate verify message.
00357  */
00358 static int send_cert_verify(SSL *ssl)
00359 {
00360     uint8_t *buf = ssl->bm_data;
00361     uint8_t dgst[MD5_SIZE+SHA1_SIZE];
00362     RSA_CTX *rsa_ctx = ssl->ssl_ctx->rsa_ctx;
00363     int n = 0, ret;
00364 
00365     DISPLAY_RSA(ssl, rsa_ctx);
00366 
00367     buf[0] = HS_CERT_VERIFY;
00368     buf[1] = 0;
00369 
00370     finished_digest(ssl, NULL, dgst);   /* calculate the digest */
00371 
00372     /* rsa_ctx->bi_ctx is not thread-safe */
00373     if (rsa_ctx)
00374     {
00375         SSL_CTX_LOCK(ssl->ssl_ctx->mutex);
00376         n = RSA_encrypt(rsa_ctx, dgst, sizeof(dgst), &buf[6], 1);
00377         SSL_CTX_UNLOCK(ssl->ssl_ctx->mutex);
00378 
00379         if (n == 0)
00380         {
00381             ret = SSL_ERROR_INVALID_KEY;
00382             goto error;
00383         }
00384     }
00385     
00386     buf[4] = n >> 8;        /* add the RSA size (not officially documented) */
00387     buf[5] = n & 0xff;
00388     n += 2;
00389     buf[2] = n >> 8;
00390     buf[3] = n & 0xff;
00391     ret = send_packet(ssl, PT_HANDSHAKE_PROTOCOL, NULL, n+4);
00392 
00393 error:
00394     return ret;
00395 }
00396 
00397 #endif      /* CONFIG_SSL_ENABLE_CLIENT */
00398 
00399