From ec636f3bdd04c9257623bfd5f7695ab20192608e Mon Sep 17 00:00:00 2001 From: Paul Bakker Date: Sun, 9 Sep 2012 19:17:02 +0000 Subject: [PATCH] - Removed handling for SSLv2 Client Hello (as per RFC 5246 recommendation) --- ChangeLog | 1 + library/ssl_srv.c | 436 ++++++++++++++++------------------------------ 2 files changed, 155 insertions(+), 282 deletions(-) diff --git a/ChangeLog b/ChangeLog index 8292eb617..fc19198a8 100644 --- a/ChangeLog +++ b/ChangeLog @@ -35,6 +35,7 @@ Changes to not match CN if subjectAltName extension is present (Closes ticket #56) * Cipher layer cipher_mode_t POLARSSL_MODE_CFB128 is renamed to POLARSSL_MODE_CFB, to also handle different block size CFB modes. + * Removed handling for SSLv2 Client Hello (as per RFC 5246 recommendation) Bugfix * Fixed handling error in mpi_cmp_mpi() on longer B values (found by diff --git a/library/ssl_srv.c b/library/ssl_srv.c index e4de68e8d..d54e3eca7 100644 --- a/library/ssl_srv.c +++ b/library/ssl_srv.c @@ -44,7 +44,7 @@ static int ssl_parse_client_hello( ssl_context *ssl ) unsigned int i, j; size_t n; unsigned int ciph_len, sess_len; - unsigned int chal_len, comp_len; + unsigned int comp_len; unsigned char *buf, *p; SSL_DEBUG_MSG( 2, ( "=> parse client hello" ) ); @@ -57,297 +57,169 @@ static int ssl_parse_client_hello( ssl_context *ssl ) buf = ssl->in_hdr; - if( ( buf[0] & 0x80 ) != 0 ) + SSL_DEBUG_BUF( 4, "record header", buf, 5 ); + + SSL_DEBUG_MSG( 3, ( "client hello v3, message type: %d", + buf[0] ) ); + SSL_DEBUG_MSG( 3, ( "client hello v3, message len.: %d", + ( buf[3] << 8 ) | buf[4] ) ); + SSL_DEBUG_MSG( 3, ( "client hello v3, protocol ver: [%d:%d]", + buf[1], buf[2] ) ); + + /* + * SSLv3 Client Hello + * + * Record layer: + * 0 . 0 message type + * 1 . 2 protocol version + * 3 . 4 message length + */ + if( buf[0] != SSL_MSG_HANDSHAKE || + buf[1] != SSL_MAJOR_VERSION_3 ) { - SSL_DEBUG_BUF( 4, "record header", buf, 5 ); + SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); + return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); + } - SSL_DEBUG_MSG( 3, ( "client hello v2, message type: %d", - buf[2] ) ); - SSL_DEBUG_MSG( 3, ( "client hello v2, message len.: %d", - ( ( buf[0] & 0x7F ) << 8 ) | buf[1] ) ); - SSL_DEBUG_MSG( 3, ( "client hello v2, max. version: [%d:%d]", - buf[3], buf[4] ) ); + n = ( buf[3] << 8 ) | buf[4]; - /* - * SSLv2 Client Hello - * - * Record layer: - * 0 . 1 message length - * - * SSL layer: - * 2 . 2 message type - * 3 . 4 protocol version - */ - if( buf[2] != SSL_HS_CLIENT_HELLO || - buf[3] != SSL_MAJOR_VERSION_3 ) + if( n < 45 || n > 512 ) + { + SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); + return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); + } + + if( ( ret = ssl_fetch_input( ssl, 5 + n ) ) != 0 ) + { + SSL_DEBUG_RET( 1, "ssl_fetch_input", ret ); + return( ret ); + } + + buf = ssl->in_msg; + n = ssl->in_left - 5; + + ssl->update_checksum( ssl, buf, n ); + + /* + * SSL layer: + * 0 . 0 handshake type + * 1 . 3 handshake length + * 4 . 5 protocol version + * 6 . 9 UNIX time() + * 10 . 37 random bytes + * 38 . 38 session id length + * 39 . 38+x session id + * 39+x . 40+x ciphersuitelist length + * 41+x . .. ciphersuitelist + * .. . .. compression alg. + * .. . .. extensions + */ + SSL_DEBUG_BUF( 4, "record contents", buf, n ); + + SSL_DEBUG_MSG( 3, ( "client hello v3, handshake type: %d", + buf[0] ) ); + SSL_DEBUG_MSG( 3, ( "client hello v3, handshake len.: %d", + ( buf[1] << 16 ) | ( buf[2] << 8 ) | buf[3] ) ); + SSL_DEBUG_MSG( 3, ( "client hello v3, max. version: [%d:%d]", + buf[4], buf[5] ) ); + + /* + * Check the handshake type and protocol version + */ + if( buf[0] != SSL_HS_CLIENT_HELLO || + buf[4] != SSL_MAJOR_VERSION_3 ) + { + SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); + return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); + } + + ssl->major_ver = SSL_MAJOR_VERSION_3; + ssl->minor_ver = ( buf[5] <= SSL_MINOR_VERSION_3 ) + ? buf[5] : SSL_MINOR_VERSION_3; + + ssl->max_major_ver = buf[4]; + ssl->max_minor_ver = buf[5]; + + memcpy( ssl->randbytes, buf + 6, 32 ); + + /* + * Check the handshake message length + */ + if( buf[1] != 0 || n != (unsigned int) 4 + ( ( buf[2] << 8 ) | buf[3] ) ) + { + SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); + return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); + } + + /* + * Check the session length + */ + sess_len = buf[38]; + + if( sess_len > 32 ) + { + SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); + return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); + } + + ssl->session->length = sess_len; + memset( ssl->session->id, 0, sizeof( ssl->session->id ) ); + memcpy( ssl->session->id, buf + 39 , ssl->session->length ); + + /* + * Check the ciphersuitelist length + */ + ciph_len = ( buf[39 + sess_len] << 8 ) + | ( buf[40 + sess_len] ); + + if( ciph_len < 2 || ciph_len > 256 || ( ciph_len % 2 ) != 0 ) + { + SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); + return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); + } + + /* + * Check the compression algorithms length + */ + comp_len = buf[41 + sess_len + ciph_len]; + + if( comp_len < 1 || comp_len > 16 ) + { + SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); + return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); + } + + ssl->session->compression = SSL_COMPRESS_NULL; +#if defined(POLARSSL_ZLIB_SUPPORT) + for( i = 0; i < comp_len; ++i ) + { + if( buf[41 + sess_len + ciph_len + i] == SSL_COMPRESS_DEFLATE ) { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - n = ( ( buf[0] << 8 ) | buf[1] ) & 0x7FFF; - - if( n < 17 || n > 512 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - ssl->max_major_ver = buf[3]; - ssl->max_minor_ver = buf[4]; - - ssl->major_ver = SSL_MAJOR_VERSION_3; - ssl->minor_ver = ( buf[4] <= SSL_MINOR_VERSION_3 ) - ? buf[4] : SSL_MINOR_VERSION_3; - - if( ( ret = ssl_fetch_input( ssl, 2 + n ) ) != 0 ) - { - SSL_DEBUG_RET( 1, "ssl_fetch_input", ret ); - return( ret ); - } - - ssl->update_checksum( ssl, buf + 2, n ); - - buf = ssl->in_msg; - n = ssl->in_left - 5; - - /* - * 0 . 1 ciphersuitelist length - * 2 . 3 session id length - * 4 . 5 challenge length - * 6 . .. ciphersuitelist - * .. . .. session id - * .. . .. challenge - */ - SSL_DEBUG_BUF( 4, "record contents", buf, n ); - - ciph_len = ( buf[0] << 8 ) | buf[1]; - sess_len = ( buf[2] << 8 ) | buf[3]; - chal_len = ( buf[4] << 8 ) | buf[5]; - - SSL_DEBUG_MSG( 3, ( "ciph_len: %d, sess_len: %d, chal_len: %d", - ciph_len, sess_len, chal_len ) ); - - /* - * Make sure each parameter length is valid - */ - if( ciph_len < 3 || ( ciph_len % 3 ) != 0 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - if( sess_len > 32 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - if( chal_len < 8 || chal_len > 32 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - if( n != 6 + ciph_len + sess_len + chal_len ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - SSL_DEBUG_BUF( 3, "client hello, ciphersuitelist", - buf + 6, ciph_len ); - SSL_DEBUG_BUF( 3, "client hello, session id", - buf + 6 + ciph_len, sess_len ); - SSL_DEBUG_BUF( 3, "client hello, challenge", - buf + 6 + ciph_len + sess_len, chal_len ); - - p = buf + 6 + ciph_len; - ssl->session->length = sess_len; - memset( ssl->session->id, 0, sizeof( ssl->session->id ) ); - memcpy( ssl->session->id, p, ssl->session->length ); - - p += sess_len; - memset( ssl->randbytes, 0, 64 ); - memcpy( ssl->randbytes + 32 - chal_len, p, chal_len ); - - for( i = 0; ssl->ciphersuites[i] != 0; i++ ) - { - for( j = 0, p = buf + 6; j < ciph_len; j += 3, p += 3 ) - { - if( p[0] == 0 && - p[1] == 0 && - p[2] == ssl->ciphersuites[i] ) - goto have_ciphersuite; - } + ssl->session->compression = SSL_COMPRESS_DEFLATE; + break; } } - else - { - SSL_DEBUG_BUF( 4, "record header", buf, 5 ); - - SSL_DEBUG_MSG( 3, ( "client hello v3, message type: %d", - buf[0] ) ); - SSL_DEBUG_MSG( 3, ( "client hello v3, message len.: %d", - ( buf[3] << 8 ) | buf[4] ) ); - SSL_DEBUG_MSG( 3, ( "client hello v3, protocol ver: [%d:%d]", - buf[1], buf[2] ) ); - - /* - * SSLv3 Client Hello - * - * Record layer: - * 0 . 0 message type - * 1 . 2 protocol version - * 3 . 4 message length - */ - if( buf[0] != SSL_MSG_HANDSHAKE || - buf[1] != SSL_MAJOR_VERSION_3 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - n = ( buf[3] << 8 ) | buf[4]; - - if( n < 45 || n > 512 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - if( ( ret = ssl_fetch_input( ssl, 5 + n ) ) != 0 ) - { - SSL_DEBUG_RET( 1, "ssl_fetch_input", ret ); - return( ret ); - } - - buf = ssl->in_msg; - n = ssl->in_left - 5; - - ssl->update_checksum( ssl, buf, n ); - - /* - * SSL layer: - * 0 . 0 handshake type - * 1 . 3 handshake length - * 4 . 5 protocol version - * 6 . 9 UNIX time() - * 10 . 37 random bytes - * 38 . 38 session id length - * 39 . 38+x session id - * 39+x . 40+x ciphersuitelist length - * 41+x . .. ciphersuitelist - * .. . .. compression alg. - * .. . .. extensions - */ - SSL_DEBUG_BUF( 4, "record contents", buf, n ); - - SSL_DEBUG_MSG( 3, ( "client hello v3, handshake type: %d", - buf[0] ) ); - SSL_DEBUG_MSG( 3, ( "client hello v3, handshake len.: %d", - ( buf[1] << 16 ) | ( buf[2] << 8 ) | buf[3] ) ); - SSL_DEBUG_MSG( 3, ( "client hello v3, max. version: [%d:%d]", - buf[4], buf[5] ) ); - - /* - * Check the handshake type and protocol version - */ - if( buf[0] != SSL_HS_CLIENT_HELLO || - buf[4] != SSL_MAJOR_VERSION_3 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - ssl->major_ver = SSL_MAJOR_VERSION_3; - ssl->minor_ver = ( buf[5] <= SSL_MINOR_VERSION_3 ) - ? buf[5] : SSL_MINOR_VERSION_3; - - ssl->max_major_ver = buf[4]; - ssl->max_minor_ver = buf[5]; - - memcpy( ssl->randbytes, buf + 6, 32 ); - - /* - * Check the handshake message length - */ - if( buf[1] != 0 || n != (unsigned int) 4 + ( ( buf[2] << 8 ) | buf[3] ) ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - /* - * Check the session length - */ - sess_len = buf[38]; - - if( sess_len > 32 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - ssl->session->length = sess_len; - memset( ssl->session->id, 0, sizeof( ssl->session->id ) ); - memcpy( ssl->session->id, buf + 39 , ssl->session->length ); - - /* - * Check the ciphersuitelist length - */ - ciph_len = ( buf[39 + sess_len] << 8 ) - | ( buf[40 + sess_len] ); - - if( ciph_len < 2 || ciph_len > 256 || ( ciph_len % 2 ) != 0 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - /* - * Check the compression algorithms length - */ - comp_len = buf[41 + sess_len + ciph_len]; - - if( comp_len < 1 || comp_len > 16 ) - { - SSL_DEBUG_MSG( 1, ( "bad client hello message" ) ); - return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO ); - } - - ssl->session->compression = SSL_COMPRESS_NULL; -#if defined(POLARSSL_ZLIB_SUPPORT) - for( i = 0; i < comp_len; ++i ) - { - if( buf[41 + sess_len + ciph_len + i] == SSL_COMPRESS_DEFLATE ) - { - ssl->session->compression = SSL_COMPRESS_DEFLATE; - break; - } - } #endif - SSL_DEBUG_BUF( 3, "client hello, random bytes", - buf + 6, 32 ); - SSL_DEBUG_BUF( 3, "client hello, session id", - buf + 38, sess_len ); - SSL_DEBUG_BUF( 3, "client hello, ciphersuitelist", - buf + 41 + sess_len, ciph_len ); - SSL_DEBUG_BUF( 3, "client hello, compression", - buf + 42 + sess_len + ciph_len, comp_len ); + SSL_DEBUG_BUF( 3, "client hello, random bytes", + buf + 6, 32 ); + SSL_DEBUG_BUF( 3, "client hello, session id", + buf + 38, sess_len ); + SSL_DEBUG_BUF( 3, "client hello, ciphersuitelist", + buf + 41 + sess_len, ciph_len ); + SSL_DEBUG_BUF( 3, "client hello, compression", + buf + 42 + sess_len + ciph_len, comp_len ); - /* - * Search for a matching ciphersuite - */ - for( i = 0; ssl->ciphersuites[i] != 0; i++ ) + /* + * Search for a matching ciphersuite + */ + for( i = 0; ssl->ciphersuites[i] != 0; i++ ) + { + for( j = 0, p = buf + 41 + sess_len; j < ciph_len; + j += 2, p += 2 ) { - for( j = 0, p = buf + 41 + sess_len; j < ciph_len; - j += 2, p += 2 ) - { - if( p[0] == 0 && p[1] == ssl->ciphersuites[i] ) - goto have_ciphersuite; - } + if( p[0] == 0 && p[1] == ssl->ciphersuites[i] ) + goto have_ciphersuite; } }