Commit e9030817 authored by Manuel Pégourié-Gonnard's avatar Manuel Pégourié-Gonnard Committed by Paul Bakker

Add timestamp/serial to cookies, with timeout

parent 445a1ec6
......@@ -48,7 +48,10 @@ extern "C" {
*/
typedef struct
{
md_context_t hmac_ctx;
md_context_t hmac_ctx; /*!< context for the HMAC portion */
#if !defined(POLARSSL_HAVE_TIME)
unsigned long serial; /*!< serial number for expiration */
#endif
} ssl_cookie_ctx;
/**
......
......@@ -55,24 +55,35 @@ static void polarssl_zeroize( void *v, size_t n ) {
* with max 32 bytes of cookie for DTLS 1.0
*/
#if defined(POLARSSL_SHA256_C)
#define COOKIE_MD POLARSSL_MD_SHA224
#define COOKIE_MD_LEN 32
#define COOKIE_MD_USE 28
#define COOKIE_MD POLARSSL_MD_SHA224
#define COOKIE_MD_OUTLEN 32
#define COOKIE_HMAC_LEN 28
#elif defined(POLARSSL_SHA512_C)
#define COOKIE_MD POLARSSL_MD_SHA384
#define COOKIE_MD_LEN 48
#define COOKIE_MD_USE 28
#define COOKIE_MD POLARSSL_MD_SHA384
#define COOKIE_MD_OUTLEN 48
#define COOKIE_HMAC_LEN 28
#elif defined(POLARSSL_SHA1_C)
#define COOKIE_MD POLARSSL_MD_SHA1
#define COOKIE_MD_LEN 20
#define COOKIE_MD_USE 20
#define COOKIE_MD POLARSSL_MD_SHA1
#define COOKIE_MD_OUTLEN 20
#define COOKIE_HMAC_LEN 20
#else
#error "DTLS hello verify needs SHA-1 or SHA-2"
#endif
/*
* Cookies are formed of a 4-bytes timestamp (or serial number) and
* an HMAC of timestemp and client ID.
*/
#define COOKIE_LEN ( 4 + COOKIE_HMAC_LEN )
#define COOKIE_TIMEOUT 60
void ssl_cookie_init( ssl_cookie_ctx *ctx )
{
md_init( &ctx->hmac_ctx );
#if !defined(POLARSSL_HAVE_TIME)
ctx->serial = 0;
#endif
}
void ssl_cookie_free( ssl_cookie_ctx *ctx )
......@@ -85,7 +96,7 @@ int ssl_cookie_setup( ssl_cookie_ctx *ctx,
void *p_rng )
{
int ret;
unsigned char key[COOKIE_MD_LEN];
unsigned char key[COOKIE_MD_OUTLEN];
if( ( ret = f_rng( p_rng, key, sizeof( key ) ) ) != 0 )
return( ret );
......@@ -103,6 +114,34 @@ int ssl_cookie_setup( ssl_cookie_ctx *ctx,
return( 0 );
}
/*
* Generate the HMAC part of a cookie
*/
static int ssl_cookie_hmac( md_context_t *hmac_ctx,
const unsigned char time[4],
unsigned char **p, unsigned char *end,
const unsigned char *cli_id, size_t cli_id_len )
{
int ret;
unsigned char hmac_out[COOKIE_MD_OUTLEN];
if( (size_t)( end - *p ) < COOKIE_HMAC_LEN )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
if( ( ret = md_hmac_reset( hmac_ctx ) ) != 0 ||
( ret = md_hmac_update( hmac_ctx, time, 4 ) ) != 0 ||
( ret = md_hmac_update( hmac_ctx, cli_id, cli_id_len ) ) != 0 ||
( ret = md_hmac_finish( hmac_ctx, hmac_out ) ) != 0 )
{
return( POLARSSL_ERR_SSL_INTERNAL_ERROR );
}
memcpy( *p, hmac_out, COOKIE_HMAC_LEN );
*p += COOKIE_HMAC_LEN;
return( 0 );
}
/*
* Generate cookie for DTLS ClientHello verification
*/
......@@ -110,27 +149,29 @@ int ssl_cookie_write( void *p_ctx,
unsigned char **p, unsigned char *end,
const unsigned char *cli_id, size_t cli_id_len )
{
int ret;
unsigned char hmac_out[COOKIE_MD_LEN];
ssl_cookie_ctx *ctx = (ssl_cookie_ctx *) p_ctx;
unsigned long t;
if( ctx == NULL || cli_id == NULL )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
if( (size_t)( end - *p ) < COOKIE_MD_USE )
if( (size_t)( end - *p ) < COOKIE_LEN )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
if( ( ret = md_hmac_reset( &ctx->hmac_ctx ) ) != 0 ||
( ret = md_hmac_update( &ctx->hmac_ctx, cli_id, cli_id_len ) ) != 0 ||
( ret = md_hmac_finish( &ctx->hmac_ctx, hmac_out ) ) != 0 )
{
return( POLARSSL_ERR_SSL_INTERNAL_ERROR );
}
#if defined(POLARSSL_HAVE_TIME)
t = (unsigned long) time( NULL );
#else
t = ctx->serial++;
#endif
memcpy( *p, hmac_out, COOKIE_MD_USE );
*p += COOKIE_MD_USE;
(*p)[0] = (unsigned char)( t >> 24 );
(*p)[1] = (unsigned char)( t >> 16 );
(*p)[2] = (unsigned char)( t >> 8 );
(*p)[3] = (unsigned char)( t );
*p += 4;
return( 0 );
return( ssl_cookie_hmac( &ctx->hmac_ctx, *p - 4,
p, end, cli_id, cli_id_len ) );
}
/*
......@@ -140,18 +181,37 @@ int ssl_cookie_check( void *p_ctx,
const unsigned char *cookie, size_t cookie_len,
const unsigned char *cli_id, size_t cli_id_len )
{
unsigned char ref_cookie[COOKIE_MD_USE];
unsigned char *p = ref_cookie;
unsigned char ref_hmac[COOKIE_HMAC_LEN];
unsigned char *p = ref_hmac;
ssl_cookie_ctx *ctx = (ssl_cookie_ctx *) p_ctx;
unsigned long cur_time, cookie_time;
if( cookie_len != COOKIE_MD_USE )
if( ctx == NULL || cli_id == NULL )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
if( cookie_len != COOKIE_LEN )
return( -1 );
if( ssl_cookie_hmac( &ctx->hmac_ctx, cookie,
&p, p + sizeof( ref_hmac ),
cli_id, cli_id_len ) != 0 )
return( -1 );
if( ssl_cookie_write( p_ctx,
&p, p + sizeof( ref_cookie ),
cli_id, cli_id_len ) != 0 )
if( safer_memcmp( cookie + 4, ref_hmac, sizeof( ref_hmac ) ) != 0 )
return( -1 );
if( safer_memcmp( cookie, ref_cookie, sizeof( ref_cookie ) ) != 0 )
#if defined(POLARSSL_HAVE_TIME)
cur_time = (unsigned long) time( NULL );
#else
cur_time = ctx->serial;
#endif
cookie_time = ( (unsigned long) cookie[0] << 24 ) |
( (unsigned long) cookie[1] << 16 ) |
( (unsigned long) cookie[2] << 8 ) |
( (unsigned long) cookie[3] );
if( cur_time - cookie_time > COOKIE_TIMEOUT )
return( -1 );
return( 0 );
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment