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Merge pull request #931 from AndrzejKurek/clihlo_cookie_pxy_fix

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Add a client hello cookie_len overflow test
This commit is contained in:
Gilles Peskine
2022-06-20 19:35:54 +02:00
committed by GitHub
parent 4ccd226cbf 755ddff25c
commit e0469b5908
6 changed files with 158 additions and 46 deletions
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84
library/ssl_msg.c
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@ -3139,8 +3139,8 @@ void mbedtls_ssl_dtls_replay_update( mbedtls_ssl_context *ssl )
#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
/*
* Without any SSL context, check if a datagram looks like a ClientHello with
* a valid cookie, and if it doesn't, generate a HelloVerifyRequest message.
* Check if a datagram looks like a ClientHello with a valid cookie,
* and if it doesn't, generate a HelloVerifyRequest message.
* Both input and output include full DTLS headers.
*
* - if cookie is valid, return 0
@ -3149,15 +3149,14 @@ void mbedtls_ssl_dtls_replay_update( mbedtls_ssl_context *ssl )
* return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED
* - otherwise return a specific error code
*/
static int ssl_check_dtls_clihlo_cookie(
mbedtls_ssl_cookie_write_t *f_cookie_write,
mbedtls_ssl_cookie_check_t *f_cookie_check,
void *p_cookie,
MBEDTLS_STATIC_TESTABLE
int mbedtls_ssl_check_dtls_clihlo_cookie(
mbedtls_ssl_context *ssl,
const unsigned char *cli_id, size_t cli_id_len,
const unsigned char *in, size_t in_len,
unsigned char *obuf, size_t buf_len, size_t *olen )
{
size_t sid_len, cookie_len;
size_t sid_len, cookie_len, epoch, fragment_offset;
unsigned char *p;
/*
@ -3186,26 +3185,55 @@ static int ssl_check_dtls_clihlo_cookie(
*
* Minimum length is 61 bytes.
*/
if( in_len < 61 ||
in[0] != MBEDTLS_SSL_MSG_HANDSHAKE ||
in[3] != 0 || in[4] != 0 ||
in[19] != 0 || in[20] != 0 || in[21] != 0 )
MBEDTLS_SSL_DEBUG_MSG( 4, ( "check cookie: in_len=%u",
(unsigned) in_len ) );
MBEDTLS_SSL_DEBUG_BUF( 4, "cli_id", cli_id, cli_id_len );
if( in_len < 61 )
{
MBEDTLS_SSL_DEBUG_MSG( 4, ( "check cookie: record too short" ) );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
epoch = MBEDTLS_GET_UINT16_BE( in, 3 );
fragment_offset = MBEDTLS_GET_UINT24_BE( in, 19 );
if( in[0] != MBEDTLS_SSL_MSG_HANDSHAKE || epoch != 0 ||
fragment_offset != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 4, ( "check cookie: not a good ClientHello" ) );
MBEDTLS_SSL_DEBUG_MSG( 4, ( " type=%u epoch=%u fragment_offset=%u",
in[0], (unsigned) epoch,
(unsigned) fragment_offset ) );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
sid_len = in[59];
if( sid_len > in_len - 61 )
if( 59 + 1 + sid_len + 1 > in_len )
{
MBEDTLS_SSL_DEBUG_MSG( 4, ( "check cookie: sid_len=%u > %u",
(unsigned) sid_len,
(unsigned) in_len - 61 ) );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
MBEDTLS_SSL_DEBUG_BUF( 4, "sid received from network",
in + 60, sid_len );
cookie_len = in[60 + sid_len];
if( cookie_len > in_len - 60 )
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
if( f_cookie_check( p_cookie, in + sid_len + 61, cookie_len,
cli_id, cli_id_len ) == 0 )
if( 59 + 1 + sid_len + 1 + cookie_len > in_len )
{
/* Valid cookie */
MBEDTLS_SSL_DEBUG_MSG( 4, ( "check cookie: cookie_len=%u > %u",
(unsigned) cookie_len,
(unsigned) ( in_len - sid_len - 61 ) ) );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
MBEDTLS_SSL_DEBUG_BUF( 4, "cookie received from network",
in + sid_len + 61, cookie_len );
if( ssl->conf->f_cookie_check( ssl->conf->p_cookie,
in + sid_len + 61, cookie_len,
cli_id, cli_id_len ) == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 4, ( "check cookie: valid" ) );
return( 0 );
}
@ -3240,8 +3268,9 @@ static int ssl_check_dtls_clihlo_cookie(
/* Generate and write actual cookie */
p = obuf + 28;
if( f_cookie_write( p_cookie,
&p, obuf + buf_len, cli_id, cli_id_len ) != 0 )
if( ssl->conf->f_cookie_write( ssl->conf->p_cookie,
&p, obuf + buf_len,
cli_id, cli_id_len ) != 0 )
{
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
@ -3295,15 +3324,13 @@ static int ssl_handle_possible_reconnect( mbedtls_ssl_context *ssl )
return( 0 );
}
ret = ssl_check_dtls_clihlo_cookie(
ssl->conf->f_cookie_write,
ssl->conf->f_cookie_check,
ssl->conf->p_cookie,
ret = mbedtls_ssl_check_dtls_clihlo_cookie(
ssl,
ssl->cli_id, ssl->cli_id_len,
ssl->in_buf, ssl->in_left,
ssl->out_buf, MBEDTLS_SSL_OUT_CONTENT_LEN, &len );
MBEDTLS_SSL_DEBUG_RET( 2, "ssl_check_dtls_clihlo_cookie", ret );
MBEDTLS_SSL_DEBUG_RET( 2, "mbedtls_ssl_check_dtls_clihlo_cookie", ret );
if( ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED )
{
@ -3481,7 +3508,6 @@ static int ssl_parse_record_header( mbedtls_ssl_context const *ssl,
/*
* Parse and validate record version
*/
rec->ver[0] = buf[ rec_hdr_version_offset + 0 ];
rec->ver[1] = buf[ rec_hdr_version_offset + 1 ];
tls_version = mbedtls_ssl_read_version( buf + rec_hdr_version_offset,
@ -3489,10 +3515,12 @@ static int ssl_parse_record_header( mbedtls_ssl_context const *ssl,
if( tls_version > ssl->conf->max_tls_version )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS version mismatch" ) );
MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS version mismatch: got %u, expected max %u",
(unsigned) tls_version,
(unsigned) ssl->conf->max_tls_version) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
/*
* Parse/Copy record sequence number.
*/