477 lines
14 KiB
C
477 lines
14 KiB
C
/*
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* Copyright (c) 2007, Cameron Rich
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* * Neither the name of the axTLS project nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include "ssl.h"
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static const uint8_t g_hello_done[] = { HS_SERVER_HELLO_DONE, 0, 0, 0 };
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static int process_client_hello(SSL *ssl);
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static int send_server_hello_sequence(SSL *ssl);
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static int send_server_hello(SSL *ssl);
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static int send_server_hello_done(SSL *ssl);
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static int process_client_key_xchg(SSL *ssl);
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#ifdef CONFIG_SSL_CERT_VERIFICATION
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static int send_certificate_request(SSL *ssl);
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static int process_cert_verify(SSL *ssl);
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#endif
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/*
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* Establish a new SSL connection to an SSL client.
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*/
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EXP_FUNC SSL * STDCALL ssl_server_new(SSL_CTX *ssl_ctx, int client_fd)
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{
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SSL *ssl;
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ssl = ssl_new(ssl_ctx, client_fd);
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ssl->next_state = HS_CLIENT_HELLO;
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#ifdef CONFIG_SSL_FULL_MODE
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if (ssl_ctx->chain_length == 0)
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printf("Warning - no server certificate defined\n"); TTY_FLUSH();
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#endif
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return ssl;
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}
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/*
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* Process the handshake record.
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*/
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int do_svr_handshake(SSL *ssl, int handshake_type, uint8_t *buf, int hs_len)
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{
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int ret = SSL_OK;
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ssl->hs_status = SSL_NOT_OK; /* not connected */
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/* To get here the state must be valid */
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switch (handshake_type)
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{
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case HS_CLIENT_HELLO:
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if ((ret = process_client_hello(ssl)) == SSL_OK)
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ret = send_server_hello_sequence(ssl);
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break;
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#ifdef CONFIG_SSL_CERT_VERIFICATION
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case HS_CERTIFICATE:/* the client sends its cert */
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ret = process_certificate(ssl, &ssl->x509_ctx);
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if (ret == SSL_OK) /* verify the cert */
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{
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int cert_res;
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cert_res = x509_verify(
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ssl->ssl_ctx->ca_cert_ctx, ssl->x509_ctx);
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ret = (cert_res == 0) ? SSL_OK : SSL_X509_ERROR(cert_res);
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}
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break;
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case HS_CERT_VERIFY:
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ret = process_cert_verify(ssl);
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add_packet(ssl, buf, hs_len); /* needs to be done after */
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break;
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#endif
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case HS_CLIENT_KEY_XCHG:
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ret = process_client_key_xchg(ssl);
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break;
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case HS_FINISHED:
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ret = process_finished(ssl, hs_len);
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disposable_free(ssl); /* free up some memory */
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break;
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}
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return ret;
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}
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/*
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* Process a client hello message.
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*/
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static int process_client_hello(SSL *ssl)
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{
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uint8_t *buf = ssl->bm_data;
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uint8_t *record_buf = ssl->hmac_header;
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int pkt_size = ssl->bm_index;
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int i, j, cs_len, id_len, offset = 6 + SSL_RANDOM_SIZE;
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int version = (record_buf[1] << 4) + record_buf[2];
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int ret = SSL_OK;
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/* should be v3.1 (TLSv1) or better - we'll send in v3.1 mode anyway */
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if (version < 0x31)
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{
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ret = SSL_ERROR_INVALID_VERSION;
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ssl_display_error(ret);
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goto error;
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}
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memcpy(ssl->dc->client_random, &buf[6], SSL_RANDOM_SIZE);
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/* process the session id */
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id_len = buf[offset++];
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if (id_len > SSL_SESSION_ID_SIZE)
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{
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return SSL_ERROR_INVALID_SESSION;
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}
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#ifndef CONFIG_SSL_SKELETON_MODE
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ssl->session = ssl_session_update(ssl->ssl_ctx->num_sessions,
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ssl->ssl_ctx->ssl_sessions, ssl, id_len ? &buf[offset] : NULL);
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#endif
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offset += id_len;
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cs_len = (buf[offset]<<8) + buf[offset+1];
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offset += 3; /* add 1 due to all cipher suites being 8 bit */
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PARANOIA_CHECK(pkt_size, offset);
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/* work out what cipher suite we are going to use */
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for (j = 0; j < NUM_PROTOCOLS; j++)
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{
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for (i = 0; i < cs_len; i += 2)
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{
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if (ssl_prot_prefs[j] == buf[offset+i]) /* got a match? */
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{
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ssl->cipher = ssl_prot_prefs[j];
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goto do_state;
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}
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}
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}
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/* ouch! protocol is not supported */
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ret = SSL_ERROR_NO_CIPHER;
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do_state:
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error:
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return ret;
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}
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#ifdef CONFIG_SSL_ENABLE_V23_HANDSHAKE
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/*
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* Some browsers use a hybrid SSLv2 "client hello"
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*/
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int process_sslv23_client_hello(SSL *ssl)
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{
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uint8_t *buf = ssl->bm_data;
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int bytes_needed = ((buf[0] & 0x7f) << 8) + buf[1];
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int version = (buf[3] << 4) + buf[4];
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int ret = SSL_OK;
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/* we have already read 3 extra bytes so far */
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int read_len = SOCKET_READ(ssl->client_fd, buf, bytes_needed-3);
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int cs_len = buf[1];
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int id_len = buf[3];
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int ch_len = buf[5];
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int i, j, offset = 8; /* start at first cipher */
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int random_offset = 0;
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DISPLAY_BYTES(ssl, "received %d bytes", buf, read_len, read_len);
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/* should be v3.1 (TLSv1) or better - we'll send in v3.1 mode anyway */
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if (version < 0x31)
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{
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return SSL_ERROR_INVALID_VERSION;
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}
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add_packet(ssl, buf, read_len);
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/* connection has gone, so die */
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if (bytes_needed < 0)
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{
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return SSL_ERROR_CONN_LOST;
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}
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/* now work out what cipher suite we are going to use */
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for (j = 0; j < NUM_PROTOCOLS; j++)
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{
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for (i = 0; i < cs_len; i += 3)
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{
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if (ssl_prot_prefs[j] == buf[offset+i])
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{
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ssl->cipher = ssl_prot_prefs[j];
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goto server_hello;
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}
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}
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}
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/* ouch! protocol is not supported */
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ret = SSL_ERROR_NO_CIPHER;
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goto error;
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server_hello:
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/* get the session id */
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offset += cs_len - 2; /* we've gone 2 bytes past the end */
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#ifndef CONFIG_SSL_SKELETON_MODE
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ssl->session = ssl_session_update(ssl->ssl_ctx->num_sessions,
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ssl->ssl_ctx->ssl_sessions, ssl, id_len ? &buf[offset] : NULL);
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#endif
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/* get the client random data */
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offset += id_len;
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/* random can be anywhere between 16 and 32 bytes long - so it is padded
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* with 0's to the left */
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if (ch_len == 0x10)
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{
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random_offset += 0x10;
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}
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memcpy(&ssl->dc->client_random[random_offset], &buf[offset], ch_len);
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ret = send_server_hello_sequence(ssl);
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error:
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return ret;
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}
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#endif
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/*
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* Send the entire server hello sequence
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*/
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static int send_server_hello_sequence(SSL *ssl)
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{
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int ret;
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if ((ret = send_server_hello(ssl)) == SSL_OK)
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{
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#ifndef CONFIG_SSL_SKELETON_MODE
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/* resume handshake? */
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if (IS_SET_SSL_FLAG(SSL_SESSION_RESUME))
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{
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if ((ret = send_change_cipher_spec(ssl)) == SSL_OK)
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{
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ret = send_finished(ssl);
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ssl->next_state = HS_FINISHED;
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}
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}
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else
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#endif
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if ((ret = send_certificate(ssl)) == SSL_OK)
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{
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#ifdef CONFIG_SSL_CERT_VERIFICATION
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/* ask the client for its certificate */
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if (IS_SET_SSL_FLAG(SSL_CLIENT_AUTHENTICATION))
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{
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if ((ret = send_certificate_request(ssl)) == SSL_OK)
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{
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ret = send_server_hello_done(ssl);
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ssl->next_state = HS_CERTIFICATE;
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}
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}
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else
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#endif
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{
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ret = send_server_hello_done(ssl);
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ssl->next_state = HS_CLIENT_KEY_XCHG;
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}
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}
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}
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return ret;
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}
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/*
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* Send a server hello message.
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*/
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static int send_server_hello(SSL *ssl)
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{
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uint8_t *buf = ssl->bm_data;
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int offset = 0;
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buf[0] = HS_SERVER_HELLO;
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buf[1] = 0;
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buf[2] = 0;
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/* byte 3 is calculated later */
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buf[4] = 0x03;
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buf[5] = 0x01;
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/* server random value */
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get_random(SSL_RANDOM_SIZE, &buf[6]);
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memcpy(ssl->dc->server_random, &buf[6], SSL_RANDOM_SIZE);
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offset = 6 + SSL_RANDOM_SIZE;
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#ifndef CONFIG_SSL_SKELETON_MODE
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if (IS_SET_SSL_FLAG(SSL_SESSION_RESUME))
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{
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/* retrieve id from session cache */
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buf[offset++] = SSL_SESSION_ID_SIZE;
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memcpy(&buf[offset], ssl->session->session_id, SSL_SESSION_ID_SIZE);
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memcpy(ssl->session_id, ssl->session->session_id, SSL_SESSION_ID_SIZE);
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ssl->sess_id_size = SSL_SESSION_ID_SIZE;
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offset += SSL_SESSION_ID_SIZE;
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}
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else /* generate our own session id */
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#endif
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{
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#ifndef CONFIG_SSL_SKELETON_MODE
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buf[offset++] = SSL_SESSION_ID_SIZE;
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get_random(SSL_SESSION_ID_SIZE, &buf[offset]);
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memcpy(ssl->session_id, &buf[offset], SSL_SESSION_ID_SIZE);
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ssl->sess_id_size = SSL_SESSION_ID_SIZE;
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/* store id in session cache */
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if (ssl->ssl_ctx->num_sessions)
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{
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memcpy(ssl->session->session_id,
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ssl->session_id, SSL_SESSION_ID_SIZE);
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}
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offset += SSL_SESSION_ID_SIZE;
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#else
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buf[offset++] = 0; /* don't bother with session id in skelton mode */
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#endif
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}
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buf[offset++] = 0; /* cipher we are using */
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buf[offset++] = ssl->cipher;
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buf[offset++] = 0; /* no compression */
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buf[3] = offset - 4; /* handshake size */
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return send_packet(ssl, PT_HANDSHAKE_PROTOCOL, NULL, offset);
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}
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/*
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* Send the server hello done message.
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*/
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static int send_server_hello_done(SSL *ssl)
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{
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return send_packet(ssl, PT_HANDSHAKE_PROTOCOL,
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g_hello_done, sizeof(g_hello_done));
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}
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/*
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* Pull apart a client key exchange message. Decrypt the pre-master key (using
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* our RSA private key) and then work out the master key. Initialise the
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* ciphers.
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*/
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static int process_client_key_xchg(SSL *ssl)
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{
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uint8_t *buf = &ssl->bm_data[ssl->dc->bm_proc_index];
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int pkt_size = ssl->bm_index;
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int premaster_size, secret_length = (buf[2] << 8) + buf[3];
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uint8_t premaster_secret[MAX_KEY_BYTE_SIZE];
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RSA_CTX *rsa_ctx = ssl->ssl_ctx->rsa_ctx;
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int offset = 4;
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int ret = SSL_OK;
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if (rsa_ctx == NULL)
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{
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ret = SSL_ERROR_NO_CERT_DEFINED;
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goto error;
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}
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/* is there an extra size field? */
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if ((secret_length - 2) == rsa_ctx->num_octets)
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offset += 2;
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PARANOIA_CHECK(pkt_size, rsa_ctx->num_octets+offset);
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/* rsa_ctx->bi_ctx is not thread-safe */
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SSL_CTX_LOCK(ssl->ssl_ctx->mutex);
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premaster_size = RSA_decrypt(rsa_ctx, &buf[offset], premaster_secret, 1);
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SSL_CTX_UNLOCK(ssl->ssl_ctx->mutex);
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if (premaster_size != SSL_SECRET_SIZE ||
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premaster_secret[0] != 0x03 || /* check version is 3.1 (TLS) */
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premaster_secret[1] != 0x01)
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{
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/* guard against a Bleichenbacher attack */
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memset(premaster_secret, 0, SSL_SECRET_SIZE);
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/* and continue - will die eventually when checking the mac */
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}
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#if 0
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print_blob("pre-master", premaster_secret, SSL_SECRET_SIZE);
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#endif
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generate_master_secret(ssl, premaster_secret);
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#ifdef CONFIG_SSL_CERT_VERIFICATION
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ssl->next_state = IS_SET_SSL_FLAG(SSL_CLIENT_AUTHENTICATION) ?
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HS_CERT_VERIFY : HS_FINISHED;
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#else
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ssl->next_state = HS_FINISHED;
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#endif
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error:
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ssl->dc->bm_proc_index += rsa_ctx->num_octets+offset;
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return ret;
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}
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#ifdef CONFIG_SSL_CERT_VERIFICATION
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static const uint8_t g_cert_request[] = { HS_CERT_REQ, 0, 0, 4, 1, 0, 0, 0 };
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/*
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* Send the certificate request message.
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*/
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static int send_certificate_request(SSL *ssl)
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{
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return send_packet(ssl, PT_HANDSHAKE_PROTOCOL,
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g_cert_request, sizeof(g_cert_request));
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}
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/*
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* Ensure the client has the private key by first decrypting the packet and
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* then checking the packet digests.
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*/
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static int process_cert_verify(SSL *ssl)
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{
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uint8_t *buf = &ssl->bm_data[ssl->dc->bm_proc_index];
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int pkt_size = ssl->bm_index;
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uint8_t dgst_buf[MAX_KEY_BYTE_SIZE];
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uint8_t dgst[MD5_SIZE+SHA1_SIZE];
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X509_CTX *x509_ctx = ssl->x509_ctx;
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int ret = SSL_OK;
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int n;
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PARANOIA_CHECK(pkt_size, x509_ctx->rsa_ctx->num_octets+6);
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DISPLAY_RSA(ssl, x509_ctx->rsa_ctx);
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/* rsa_ctx->bi_ctx is not thread-safe */
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SSL_CTX_LOCK(ssl->ssl_ctx->mutex);
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n = RSA_decrypt(x509_ctx->rsa_ctx, &buf[6], dgst_buf, 0);
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SSL_CTX_UNLOCK(ssl->ssl_ctx->mutex);
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if (n != SHA1_SIZE + MD5_SIZE)
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{
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ret = SSL_ERROR_INVALID_KEY;
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goto end_cert_vfy;
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}
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finished_digest(ssl, NULL, dgst); /* calculate the digest */
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if (memcmp(dgst_buf, dgst, MD5_SIZE + SHA1_SIZE))
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{
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ret = SSL_ERROR_INVALID_KEY;
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}
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end_cert_vfy:
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ssl->next_state = HS_FINISHED;
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error:
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return ret;
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}
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#endif
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