From a4a473516ef24e46bfe07639300869414b3e49ce Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?= Date: Fri, 15 May 2015 15:14:54 +0200 Subject: [PATCH] Rename & move ticket functions to ticket module --- include/mbedtls/ssl_ticket.h | 7 + library/ssl_srv.c | 315 +---------------------------------- library/ssl_ticket.c | 298 +++++++++++++++++++++++++++++++++ 3 files changed, 310 insertions(+), 310 deletions(-) diff --git a/include/mbedtls/ssl_ticket.h b/include/mbedtls/ssl_ticket.h index 297548f45..914302437 100644 --- a/include/mbedtls/ssl_ticket.h +++ b/include/mbedtls/ssl_ticket.h @@ -30,6 +30,13 @@ extern "C" { #endif +/* Temporary, WIP */ +int mbedtls_ssl_ticket_write( mbedtls_ssl_context *ssl, size_t *tlen ); + +/* Temporary, WIP */ +int mbedtls_ssl_ticket_parse( mbedtls_ssl_context *ssl, + unsigned char *buf, + size_t len ); #ifdef __cplusplus } diff --git a/library/ssl_srv.c b/library/ssl_srv.c index 62c520d3f..5b7cbeb14 100644 --- a/library/ssl_srv.c +++ b/library/ssl_srv.c @@ -50,314 +50,9 @@ #endif #if defined(MBEDTLS_SSL_SESSION_TICKETS) -/* Implementation that should never be optimized out by the compiler */ -static void mbedtls_zeroize( void *v, size_t n ) { - volatile unsigned char *p = v; while( n-- ) *p++ = 0; -} - -/* - * Serialize a session in the following format: - * 0 . n-1 session structure, n = sizeof(mbedtls_ssl_session) - * n . n+2 peer_cert length = m (0 if no certificate) - * n+3 . n+2+m peer cert ASN.1 - * - * Assumes ticket is NULL (always true on server side). - */ -static int ssl_save_session( const mbedtls_ssl_session *session, - unsigned char *buf, size_t buf_len, - size_t *olen ) -{ - unsigned char *p = buf; - size_t left = buf_len; -#if defined(MBEDTLS_X509_CRT_PARSE_C) - size_t cert_len; -#endif /* MBEDTLS_X509_CRT_PARSE_C */ - - if( left < sizeof( mbedtls_ssl_session ) ) - return( -1 ); - - memcpy( p, session, sizeof( mbedtls_ssl_session ) ); - p += sizeof( mbedtls_ssl_session ); - left -= sizeof( mbedtls_ssl_session ); - -#if defined(MBEDTLS_X509_CRT_PARSE_C) - if( session->peer_cert == NULL ) - cert_len = 0; - else - cert_len = session->peer_cert->raw.len; - - if( left < 3 + cert_len ) - return( -1 ); - - *p++ = (unsigned char)( cert_len >> 16 & 0xFF ); - *p++ = (unsigned char)( cert_len >> 8 & 0xFF ); - *p++ = (unsigned char)( cert_len & 0xFF ); - - if( session->peer_cert != NULL ) - memcpy( p, session->peer_cert->raw.p, cert_len ); - - p += cert_len; -#endif /* MBEDTLS_X509_CRT_PARSE_C */ - - *olen = p - buf; - - return( 0 ); -} - -/* - * Unserialise session, see ssl_save_session() - */ -static int ssl_load_session( mbedtls_ssl_session *session, - const unsigned char *buf, size_t len ) -{ - const unsigned char *p = buf; - const unsigned char * const end = buf + len; -#if defined(MBEDTLS_X509_CRT_PARSE_C) - size_t cert_len; -#endif /* MBEDTLS_X509_CRT_PARSE_C */ - - if( p + sizeof( mbedtls_ssl_session ) > end ) - return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); - - memcpy( session, p, sizeof( mbedtls_ssl_session ) ); - p += sizeof( mbedtls_ssl_session ); - -#if defined(MBEDTLS_X509_CRT_PARSE_C) - if( p + 3 > end ) - return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); - - cert_len = ( p[0] << 16 ) | ( p[1] << 8 ) | p[2]; - p += 3; - - if( cert_len == 0 ) - { - session->peer_cert = NULL; - } - else - { - int ret; - - if( p + cert_len > end ) - return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); - - session->peer_cert = mbedtls_malloc( sizeof( mbedtls_x509_crt ) ); - - if( session->peer_cert == NULL ) - return( MBEDTLS_ERR_SSL_MALLOC_FAILED ); - - mbedtls_x509_crt_init( session->peer_cert ); - - if( ( ret = mbedtls_x509_crt_parse_der( session->peer_cert, - p, cert_len ) ) != 0 ) - { - mbedtls_x509_crt_free( session->peer_cert ); - mbedtls_free( session->peer_cert ); - session->peer_cert = NULL; - return( ret ); - } - - p += cert_len; - } -#endif /* MBEDTLS_X509_CRT_PARSE_C */ - - if( p != end ) - return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); - - return( 0 ); -} - -/* - * Create session ticket, secured as recommended in RFC 5077 section 4: - * - * struct { - * opaque key_name[16]; - * opaque iv[16]; - * opaque encrypted_state<0..2^16-1>; - * opaque mac[32]; - * } ticket; - * - * (the internal state structure differs, however). - */ -static int ssl_write_ticket( mbedtls_ssl_context *ssl, size_t *tlen ) -{ - int ret; - unsigned char * const start = ssl->out_msg + 10; - unsigned char *p = start; - unsigned char *state; - unsigned char iv[16]; - size_t clear_len, enc_len, pad_len, i; - - *tlen = 0; - - if( ssl->conf->ticket_keys == NULL ) - return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); - - /* Write key name */ - memcpy( p, ssl->conf->ticket_keys->key_name, 16 ); - p += 16; - - /* Generate and write IV (with a copy for aes_crypt) */ - if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng, p, 16 ) ) != 0 ) - return( ret ); - memcpy( iv, p, 16 ); - p += 16; - - /* - * Dump session state - * - * After the session state itself, we still need room for 16 bytes of - * padding and 32 bytes of MAC, so there's only so much room left - */ - state = p + 2; - if( ssl_save_session( ssl->session_negotiate, state, - MBEDTLS_SSL_MAX_CONTENT_LEN - ( state - ssl->out_msg ) - 48, - &clear_len ) != 0 ) - { - return( MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE ); - } - MBEDTLS_SSL_DEBUG_BUF( 3, "session ticket cleartext", state, clear_len ); - - /* Apply PKCS padding */ - pad_len = 16 - clear_len % 16; - enc_len = clear_len + pad_len; - for( i = clear_len; i < enc_len; i++ ) - state[i] = (unsigned char) pad_len; - - /* Encrypt */ - if( ( ret = mbedtls_aes_crypt_cbc( &ssl->conf->ticket_keys->enc, MBEDTLS_AES_ENCRYPT, - enc_len, iv, state, state ) ) != 0 ) - { - return( ret ); - } - - /* Write length */ - *p++ = (unsigned char)( ( enc_len >> 8 ) & 0xFF ); - *p++ = (unsigned char)( ( enc_len ) & 0xFF ); - p = state + enc_len; - - /* Compute and write MAC( key_name + iv + enc_state_len + enc_state ) */ - if( ( ret = mbedtls_md_hmac( mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), - ssl->conf->ticket_keys->mac_key, 16, - start, p - start, p ) ) != 0 ) - { - return( ret ); - } - p += 32; - - *tlen = p - start; - - MBEDTLS_SSL_DEBUG_BUF( 3, "session ticket structure", start, *tlen ); - - return( 0 ); -} - -/* - * Load session ticket (see ssl_write_ticket for structure) - */ -static int ssl_parse_ticket( mbedtls_ssl_context *ssl, - unsigned char *buf, - size_t len ) -{ - int ret; - mbedtls_ssl_session session; - unsigned char *key_name = buf; - unsigned char *iv = buf + 16; - unsigned char *enc_len_p = iv + 16; - unsigned char *ticket = enc_len_p + 2; - unsigned char *mac; - unsigned char computed_mac[32]; - size_t enc_len, clear_len, i; - unsigned char pad_len, diff; - - MBEDTLS_SSL_DEBUG_BUF( 3, "session ticket structure", buf, len ); - - if( len < 34 || ssl->conf->ticket_keys == NULL ) - return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); - - enc_len = ( enc_len_p[0] << 8 ) | enc_len_p[1]; - mac = ticket + enc_len; - - if( len != enc_len + 66 ) - return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); - - /* Check name, in constant time though it's not a big secret */ - diff = 0; - for( i = 0; i < 16; i++ ) - diff |= key_name[i] ^ ssl->conf->ticket_keys->key_name[i]; - /* don't return yet, check the MAC anyway */ - - /* Check mac, with constant-time buffer comparison */ - if( ( ret = mbedtls_md_hmac( mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), - ssl->conf->ticket_keys->mac_key, 16, - buf, len - 32, computed_mac ) ) != 0 ) - { - return( ret ); - } - - for( i = 0; i < 32; i++ ) - diff |= mac[i] ^ computed_mac[i]; - - /* Now return if ticket is not authentic, since we want to avoid - * decrypting arbitrary attacker-chosen data */ - if( diff != 0 ) - return( MBEDTLS_ERR_SSL_INVALID_MAC ); - - /* Decrypt */ - if( ( ret = mbedtls_aes_crypt_cbc( &ssl->conf->ticket_keys->dec, MBEDTLS_AES_DECRYPT, - enc_len, iv, ticket, ticket ) ) != 0 ) - { - return( ret ); - } - - /* Check PKCS padding */ - pad_len = ticket[enc_len - 1]; - - ret = 0; - for( i = 2; i < pad_len; i++ ) - if( ticket[enc_len - i] != pad_len ) - ret = MBEDTLS_ERR_SSL_BAD_INPUT_DATA; - if( ret != 0 ) - return( ret ); - - clear_len = enc_len - pad_len; - - MBEDTLS_SSL_DEBUG_BUF( 3, "session ticket cleartext", ticket, clear_len ); - - /* Actually load session */ - if( ( ret = ssl_load_session( &session, ticket, clear_len ) ) != 0 ) - { - MBEDTLS_SSL_DEBUG_MSG( 1, ( "failed to parse ticket content" ) ); - mbedtls_ssl_session_free( &session ); - return( ret ); - } - -#if defined(MBEDTLS_HAVE_TIME) - /* Check if still valid */ - if( (int) ( time( NULL) - session.start ) > ssl->conf->ticket_lifetime ) - { - MBEDTLS_SSL_DEBUG_MSG( 1, ( "session ticket expired" ) ); - mbedtls_ssl_session_free( &session ); - return( MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED ); - } +#include "mbedtls/ssl_ticket.h" #endif - /* - * Keep the session ID sent by the client, since we MUST send it back to - * inform him we're accepting the ticket (RFC 5077 section 3.4) - */ - session.length = ssl->session_negotiate->length; - memcpy( &session.id, ssl->session_negotiate->id, session.length ); - - mbedtls_ssl_session_free( ssl->session_negotiate ); - memcpy( ssl->session_negotiate, &session, sizeof( mbedtls_ssl_session ) ); - - /* Zeroize instead of free as we copied the content */ - mbedtls_zeroize( &session, sizeof( mbedtls_ssl_session ) ); - - return( 0 ); -} -#endif /* MBEDTLS_SSL_SESSION_TICKETS */ - #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) int mbedtls_ssl_set_client_transport_id( mbedtls_ssl_context *ssl, const unsigned char *info, @@ -734,9 +429,9 @@ static int ssl_parse_session_ticket_ext( mbedtls_ssl_context *ssl, /* * Failures are ok: just ignore the ticket and proceed. */ - if( ( ret = ssl_parse_ticket( ssl, buf, len ) ) != 0 ) + if( ( ret = mbedtls_ssl_ticket_parse( ssl, buf, len ) ) != 0 ) { - MBEDTLS_SSL_DEBUG_RET( 1, "ssl_parse_ticket", ret ); + MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_ticket_parse", ret ); return( 0 ); } @@ -3814,9 +3509,9 @@ static int ssl_write_new_session_ticket( mbedtls_ssl_context *ssl ) ssl->out_msg[6] = ( lifetime >> 8 ) & 0xFF; ssl->out_msg[7] = ( lifetime ) & 0xFF; - if( ( ret = ssl_write_ticket( ssl, &tlen ) ) != 0 ) + if( ( ret = mbedtls_ssl_ticket_write( ssl, &tlen ) ) != 0 ) { - MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_ticket", ret ); + MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_ticket_write", ret ); tlen = 0; } diff --git a/library/ssl_ticket.c b/library/ssl_ticket.c index e6e38fef5..6709c688c 100644 --- a/library/ssl_ticket.c +++ b/library/ssl_ticket.c @@ -39,4 +39,302 @@ #include +/* Implementation that should never be optimized out by the compiler */ +static void mbedtls_zeroize( void *v, size_t n ) { + volatile unsigned char *p = v; while( n-- ) *p++ = 0; +} + +/* + * Serialize a session in the following format: + * 0 . n-1 session structure, n = sizeof(mbedtls_ssl_session) + * n . n+2 peer_cert length = m (0 if no certificate) + * n+3 . n+2+m peer cert ASN.1 + * + * Assumes ticket is NULL (always true on server side). + */ +static int ssl_save_session( const mbedtls_ssl_session *session, + unsigned char *buf, size_t buf_len, + size_t *olen ) +{ + unsigned char *p = buf; + size_t left = buf_len; +#if defined(MBEDTLS_X509_CRT_PARSE_C) + size_t cert_len; +#endif /* MBEDTLS_X509_CRT_PARSE_C */ + + if( left < sizeof( mbedtls_ssl_session ) ) + return( -1 ); + + memcpy( p, session, sizeof( mbedtls_ssl_session ) ); + p += sizeof( mbedtls_ssl_session ); + left -= sizeof( mbedtls_ssl_session ); + +#if defined(MBEDTLS_X509_CRT_PARSE_C) + if( session->peer_cert == NULL ) + cert_len = 0; + else + cert_len = session->peer_cert->raw.len; + + if( left < 3 + cert_len ) + return( -1 ); + + *p++ = (unsigned char)( cert_len >> 16 & 0xFF ); + *p++ = (unsigned char)( cert_len >> 8 & 0xFF ); + *p++ = (unsigned char)( cert_len & 0xFF ); + + if( session->peer_cert != NULL ) + memcpy( p, session->peer_cert->raw.p, cert_len ); + + p += cert_len; +#endif /* MBEDTLS_X509_CRT_PARSE_C */ + + *olen = p - buf; + + return( 0 ); +} + +/* + * Unserialise session, see ssl_save_session() + */ +static int ssl_load_session( mbedtls_ssl_session *session, + const unsigned char *buf, size_t len ) +{ + const unsigned char *p = buf; + const unsigned char * const end = buf + len; +#if defined(MBEDTLS_X509_CRT_PARSE_C) + size_t cert_len; +#endif /* MBEDTLS_X509_CRT_PARSE_C */ + + if( p + sizeof( mbedtls_ssl_session ) > end ) + return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); + + memcpy( session, p, sizeof( mbedtls_ssl_session ) ); + p += sizeof( mbedtls_ssl_session ); + +#if defined(MBEDTLS_X509_CRT_PARSE_C) + if( p + 3 > end ) + return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); + + cert_len = ( p[0] << 16 ) | ( p[1] << 8 ) | p[2]; + p += 3; + + if( cert_len == 0 ) + { + session->peer_cert = NULL; + } + else + { + int ret; + + if( p + cert_len > end ) + return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); + + session->peer_cert = mbedtls_malloc( sizeof( mbedtls_x509_crt ) ); + + if( session->peer_cert == NULL ) + return( MBEDTLS_ERR_SSL_MALLOC_FAILED ); + + mbedtls_x509_crt_init( session->peer_cert ); + + if( ( ret = mbedtls_x509_crt_parse_der( session->peer_cert, + p, cert_len ) ) != 0 ) + { + mbedtls_x509_crt_free( session->peer_cert ); + mbedtls_free( session->peer_cert ); + session->peer_cert = NULL; + return( ret ); + } + + p += cert_len; + } +#endif /* MBEDTLS_X509_CRT_PARSE_C */ + + if( p != end ) + return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); + + return( 0 ); +} + +/* + * Create session ticket, secured as recommended in RFC 5077 section 4: + * + * struct { + * opaque key_name[16]; + * opaque iv[16]; + * opaque encrypted_state<0..2^16-1>; + * opaque mac[32]; + * } ticket; + * + * (the internal state structure differs, however). + */ +int mbedtls_ssl_ticket_write( mbedtls_ssl_context *ssl, size_t *tlen ) +{ + int ret; + unsigned char * const start = ssl->out_msg + 10; + unsigned char *p = start; + unsigned char *state; + unsigned char iv[16]; + size_t clear_len, enc_len, pad_len, i; + + *tlen = 0; + + if( ssl->conf->ticket_keys == NULL ) + return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); + + /* Write key name */ + memcpy( p, ssl->conf->ticket_keys->key_name, 16 ); + p += 16; + + /* Generate and write IV (with a copy for aes_crypt) */ + if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng, p, 16 ) ) != 0 ) + return( ret ); + memcpy( iv, p, 16 ); + p += 16; + + /* + * Dump session state + * + * After the session state itself, we still need room for 16 bytes of + * padding and 32 bytes of MAC, so there's only so much room left + */ + state = p + 2; + if( ssl_save_session( ssl->session_negotiate, state, + MBEDTLS_SSL_MAX_CONTENT_LEN - ( state - ssl->out_msg ) - 48, + &clear_len ) != 0 ) + { + return( MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE ); + } + + /* Apply PKCS padding */ + pad_len = 16 - clear_len % 16; + enc_len = clear_len + pad_len; + for( i = clear_len; i < enc_len; i++ ) + state[i] = (unsigned char) pad_len; + + /* Encrypt */ + if( ( ret = mbedtls_aes_crypt_cbc( &ssl->conf->ticket_keys->enc, MBEDTLS_AES_ENCRYPT, + enc_len, iv, state, state ) ) != 0 ) + { + return( ret ); + } + + /* Write length */ + *p++ = (unsigned char)( ( enc_len >> 8 ) & 0xFF ); + *p++ = (unsigned char)( ( enc_len ) & 0xFF ); + p = state + enc_len; + + /* Compute and write MAC( key_name + iv + enc_state_len + enc_state ) */ + if( ( ret = mbedtls_md_hmac( mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), + ssl->conf->ticket_keys->mac_key, 16, + start, p - start, p ) ) != 0 ) + { + return( ret ); + } + p += 32; + + *tlen = p - start; + + return( 0 ); +} + +/* + * Load session ticket (see mbedtls_ssl_ticket_write for structure) + */ +int mbedtls_ssl_ticket_parse( mbedtls_ssl_context *ssl, + unsigned char *buf, + size_t len ) +{ + int ret; + mbedtls_ssl_session session; + unsigned char *key_name = buf; + unsigned char *iv = buf + 16; + unsigned char *enc_len_p = iv + 16; + unsigned char *ticket = enc_len_p + 2; + unsigned char *mac; + unsigned char computed_mac[32]; + size_t enc_len, clear_len, i; + unsigned char pad_len, diff; + + if( len < 34 || ssl->conf->ticket_keys == NULL ) + return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); + + enc_len = ( enc_len_p[0] << 8 ) | enc_len_p[1]; + mac = ticket + enc_len; + + if( len != enc_len + 66 ) + return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); + + /* Check name, in constant time though it's not a big secret */ + diff = 0; + for( i = 0; i < 16; i++ ) + diff |= key_name[i] ^ ssl->conf->ticket_keys->key_name[i]; + /* don't return yet, check the MAC anyway */ + + /* Check mac, with constant-time buffer comparison */ + if( ( ret = mbedtls_md_hmac( mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), + ssl->conf->ticket_keys->mac_key, 16, + buf, len - 32, computed_mac ) ) != 0 ) + { + return( ret ); + } + + for( i = 0; i < 32; i++ ) + diff |= mac[i] ^ computed_mac[i]; + + /* Now return if ticket is not authentic, since we want to avoid + * decrypting arbitrary attacker-chosen data */ + if( diff != 0 ) + return( MBEDTLS_ERR_SSL_INVALID_MAC ); + + /* Decrypt */ + if( ( ret = mbedtls_aes_crypt_cbc( &ssl->conf->ticket_keys->dec, MBEDTLS_AES_DECRYPT, + enc_len, iv, ticket, ticket ) ) != 0 ) + { + return( ret ); + } + + /* Check PKCS padding */ + pad_len = ticket[enc_len - 1]; + + ret = 0; + for( i = 2; i < pad_len; i++ ) + if( ticket[enc_len - i] != pad_len ) + ret = MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + if( ret != 0 ) + return( ret ); + + clear_len = enc_len - pad_len; + + /* Actually load session */ + if( ( ret = ssl_load_session( &session, ticket, clear_len ) ) != 0 ) + { + mbedtls_ssl_session_free( &session ); + return( ret ); + } + +#if defined(MBEDTLS_HAVE_TIME) + /* Check if still valid */ + if( (int) ( time( NULL) - session.start ) > ssl->conf->ticket_lifetime ) + { + mbedtls_ssl_session_free( &session ); + return( MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED ); + } +#endif + + /* + * Keep the session ID sent by the client, since we MUST send it back to + * inform him we're accepting the ticket (RFC 5077 section 3.4) + */ + session.length = ssl->session_negotiate->length; + memcpy( &session.id, ssl->session_negotiate->id, session.length ); + + mbedtls_ssl_session_free( ssl->session_negotiate ); + memcpy( ssl->session_negotiate, &session, sizeof( mbedtls_ssl_session ) ); + + /* Zeroize instead of free as we copied the content */ + mbedtls_zeroize( &session, sizeof( mbedtls_ssl_session ) ); + + return( 0 ); +} + #endif /* MBEDTLS_SSL_TICKET_C */