From d140d0828e9bf4cc7e59c015c74d9b1923746a96 Mon Sep 17 00:00:00 2001 From: Hanno Becker Date: Sat, 17 Nov 2018 21:18:01 +0000 Subject: [PATCH] Introduce macros for constants in SSL ticket implementation --- library/ssl_ticket.c | 56 ++++++++++++++++++++++++++++++-------------- 1 file changed, 38 insertions(+), 18 deletions(-) diff --git a/library/ssl_ticket.c b/library/ssl_ticket.c index 985b7cd50..6692187a0 100644 --- a/library/ssl_ticket.c +++ b/library/ssl_ticket.c @@ -54,6 +54,19 @@ void mbedtls_ssl_ticket_init( mbedtls_ssl_ticket_context *ctx ) #define MAX_KEY_BYTES 32 /* 256 bits */ +#define TICKET_KEY_NAME_BYTES 4 +#define TICKET_IV_BYTES 12 +#define TICKET_CRYPT_LEN_BYTES 2 +#define TICKET_AUTH_TAG_BYTES 16 + +#define TICKET_MIN_LEN ( TICKET_KEY_NAME_BYTES + \ + TICKET_IV_BYTES + \ + TICKET_CRYPT_LEN_BYTES + \ + TICKET_AUTH_TAG_BYTES ) +#define TICKET_ADD_DATA_LEN ( TICKET_KEY_NAME_BYTES + \ + TICKET_IV_BYTES + \ + TICKET_CRYPT_LEN_BYTES ) + /* * Generate/update a key */ @@ -278,6 +291,7 @@ static int ssl_load_session( mbedtls_ssl_session *session, * The key_name, iv, and length of encrypted_state are the additional * authenticated data. */ + int mbedtls_ssl_ticket_write( void *p_ticket, const mbedtls_ssl_session *session, unsigned char *start, @@ -289,9 +303,9 @@ int mbedtls_ssl_ticket_write( void *p_ticket, mbedtls_ssl_ticket_context *ctx = p_ticket; mbedtls_ssl_ticket_key *key; unsigned char *key_name = start; - unsigned char *iv = start + 4; - unsigned char *state_len_bytes = iv + 12; - unsigned char *state = state_len_bytes + 2; + unsigned char *iv = start + TICKET_KEY_NAME_BYTES; + unsigned char *state_len_bytes = iv + TICKET_IV_BYTES; + unsigned char *state = state_len_bytes + TICKET_CRYPT_LEN_BYTES; unsigned char *tag; size_t clear_len, ciph_len; @@ -302,7 +316,7 @@ int mbedtls_ssl_ticket_write( void *p_ticket, /* We need at least 4 bytes for key_name, 12 for IV, 2 for len 16 for tag, * in addition to session itself, that will be checked when writing it. */ - if( end - start < 4 + 12 + 2 + 16 ) + if( end - start < TICKET_MIN_LEN ) return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ); #if defined(MBEDTLS_THREADING_C) @@ -317,9 +331,9 @@ int mbedtls_ssl_ticket_write( void *p_ticket, *ticket_lifetime = ctx->ticket_lifetime; - memcpy( key_name, key->name, 4 ); + memcpy( key_name, key->name, TICKET_KEY_NAME_BYTES ); - if( ( ret = ctx->f_rng( ctx->p_rng, iv, 12 ) ) != 0 ) + if( ( ret = ctx->f_rng( ctx->p_rng, iv, TICKET_IV_BYTES ) ) != 0 ) goto cleanup; /* Dump session state */ @@ -335,8 +349,11 @@ int mbedtls_ssl_ticket_write( void *p_ticket, /* Encrypt and authenticate */ tag = state + clear_len; if( ( ret = mbedtls_cipher_auth_encrypt( &key->ctx, - iv, 12, key_name, 4 + 12 + 2, - state, clear_len, state, &ciph_len, tag, 16 ) ) != 0 ) + iv, TICKET_IV_BYTES, + /* Additional data: key name, IV and length */ + key_name, TICKET_ADD_DATA_LEN, + state, clear_len, state, &ciph_len, + tag, TICKET_AUTH_TAG_BYTES ) ) != 0 ) { goto cleanup; } @@ -346,7 +363,7 @@ int mbedtls_ssl_ticket_write( void *p_ticket, goto cleanup; } - *tlen = 4 + 12 + 2 + 16 + ciph_len; + *tlen = TICKET_MIN_LEN + ciph_len; cleanup: #if defined(MBEDTLS_THREADING_C) @@ -385,17 +402,16 @@ int mbedtls_ssl_ticket_parse( void *p_ticket, mbedtls_ssl_ticket_context *ctx = p_ticket; mbedtls_ssl_ticket_key *key; unsigned char *key_name = buf; - unsigned char *iv = buf + 4; - unsigned char *enc_len_p = iv + 12; - unsigned char *ticket = enc_len_p + 2; + unsigned char *iv = buf + TICKET_KEY_NAME_BYTES; + unsigned char *enc_len_p = iv + TICKET_IV_BYTES; + unsigned char *ticket = enc_len_p + TICKET_CRYPT_LEN_BYTES; unsigned char *tag; size_t enc_len, clear_len; if( ctx == NULL || ctx->f_rng == NULL ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); - /* See mbedtls_ssl_ticket_write() */ - if( len < 4 + 12 + 2 + 16 ) + if( len < TICKET_MIN_LEN ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); #if defined(MBEDTLS_THREADING_C) @@ -409,7 +425,7 @@ int mbedtls_ssl_ticket_parse( void *p_ticket, enc_len = ( enc_len_p[0] << 8 ) | enc_len_p[1]; tag = ticket + enc_len; - if( len != 4 + 12 + 2 + enc_len + 16 ) + if( len != TICKET_MIN_LEN + enc_len ) { ret = MBEDTLS_ERR_SSL_BAD_INPUT_DATA; goto cleanup; @@ -425,9 +441,13 @@ int mbedtls_ssl_ticket_parse( void *p_ticket, } /* Decrypt and authenticate */ - if( ( ret = mbedtls_cipher_auth_decrypt( &key->ctx, iv, 12, - key_name, 4 + 12 + 2, ticket, enc_len, - ticket, &clear_len, tag, 16 ) ) != 0 ) + if( ( ret = mbedtls_cipher_auth_decrypt( &key->ctx, + iv, TICKET_IV_BYTES, + /* Additional data: key name, IV and length */ + key_name, TICKET_ADD_DATA_LEN, + ticket, enc_len, + ticket, &clear_len, + tag, TICKET_AUTH_TAG_BYTES ) ) != 0 ) { if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED ) ret = MBEDTLS_ERR_SSL_INVALID_MAC;