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Merge branch 'fb-scsv' into dtls

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* fb-scsv:
  Update Changelog for FALLBACK_SCSV
  Implement FALLBACK_SCSV server-side
  Implement FALLBACK_SCSV client-side
This commit is contained in:
Manuel Pégourié-Gonnard 2014-11-05 16:12:09 +01:00
commit fedba98ede
8 changed files with 239 additions and 1 deletions
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7
ChangeLog
View file

@ -10,6 +10,13 @@ API Changes
* ssl_set_bio() now requires that p_send == p_recv.
* ssl_set_bio() is deprecated in favor of ssl_set_bio_timeout().
= 1.3 branch
Reminder: bump SONAME for ABI change (FALLBACK_SCSV)
Features
* Add support for FALLBACK_SCSV (draft-ietf-tls-downgrade-scsv)
= PolarSSL 1.3.9 released 2014-10-20
Security
* Lowest common hash was selected from signature_algorithms extension in

17
include/polarssl/config.h
View file

@ -811,6 +811,23 @@
*/
//#define POLARSSL_SSL_DEBUG_ALL
/**
* \def POLARSSL_SSL_FALLBACK_SCSV
*
* Enable support for FALLBACK_SCSV (draft-ietf-tls-downgrade-scsv-00).
*
* For servers, it is recommended to always enable this, unless you support
* only one version of TLS, or know for sure that none of your clients
* implements a fallback strategy.
*
* For clients, you only need this if you're using a fallback strategy, which
* is not recommended in the first place, unless you absolutely need it to
* interoperate with buggy (version-intolerant) servers.
*
* Comment this macro to disable support for FALLBACK_SCSV
*/
#define POLARSSL_SSL_FALLBACK_SCSV
/**
* \def POLARSSL_SSL_HW_RECORD_ACCEL
*

33
include/polarssl/ssl.h
View file

@ -215,6 +215,9 @@
#define SSL_IS_CLIENT 0
#define SSL_IS_SERVER 1
#define SSL_IS_NOT_FALLBACK 0
#define SSL_IS_FALLBACK 1
#define SSL_COMPRESS_NULL 0
#define SSL_COMPRESS_DEFLATE 1
@ -340,6 +343,7 @@
* Signaling ciphersuite values (SCSV)
*/
#define SSL_EMPTY_RENEGOTIATION_INFO 0xFF /**< renegotiation info ext */
#define SSL_FALLBACK_SCSV 0x5600 /**< draft-ietf-tls-downgrade-scsv-00 */
/*
* Supported Signature and Hash algorithms (For TLS 1.2)
@ -397,6 +401,7 @@
#define SSL_ALERT_MSG_PROTOCOL_VERSION 70 /* 0x46 */
#define SSL_ALERT_MSG_INSUFFICIENT_SECURITY 71 /* 0x47 */
#define SSL_ALERT_MSG_INTERNAL_ERROR 80 /* 0x50 */
#define SSL_ALERT_MSG_INAPROPRIATE_FALLBACK 86 /* 0x56 */
#define SSL_ALERT_MSG_USER_CANCELED 90 /* 0x5A */
#define SSL_ALERT_MSG_NO_RENEGOTIATION 100 /* 0x64 */
#define SSL_ALERT_MSG_UNSUPPORTED_EXT 110 /* 0x6E */
@ -779,6 +784,10 @@ struct _ssl_context
unsigned badmac_seen; /*!< records with a bad MAC received */
#endif
#if defined(POLARSSL_SSL_FALLBACK_SCSV) && defined(POLARSSL_SSL_CLI_C)
char fallback; /*!< flag for fallback connections */
#endif
/*
* Callbacks (RNG, debug, I/O, verification)
*/
@ -1695,7 +1704,6 @@ const char *ssl_get_alpn_protocol( const ssl_context *ssl );
*/
int ssl_set_max_version( ssl_context *ssl, int major, int minor );
/**
* \brief Set the minimum accepted SSL/TLS protocol version
* (Default: SSL_MIN_MAJOR_VERSION, SSL_MIN_MINOR_VERSION)
@ -1712,6 +1720,29 @@ int ssl_set_max_version( ssl_context *ssl, int major, int minor );
*/
int ssl_set_min_version( ssl_context *ssl, int major, int minor );
#if defined(POLARSSL_SSL_FALLBACK_SCSV) && defined(POLARSSL_SSL_CLI_C)
/**
* \brief Set the fallback flag (client-side only).
* (Default: SSL_IS_NOT_FALLBACK).
*
* \note Set to SSL_IS_FALLBACK when preparing a fallback
* connection, that is a connection with max_version set to a
* lower value than the value you're willing to use. Such
* fallback connections are not recommended but are sometimes
* necessary to interoperate with buggy (version-intolerant)
* servers.
*
* \warning You should NOT set this to SSL_IS_FALLBACK for
* non-fallback connections! This would appear to work for a
* while, then cause failures when the server is upgraded to
* support a newer TLS version.
*
* \param ssl SSL context
* \param fallback SSL_IS_NOT_FALLBACK or SSL_IS_FALLBACK
*/
void ssl_set_fallback( ssl_context *ssl, char fallback );
#endif /* POLARSSL_SSL_FALLBACK_SCSV && POLARSSL_SSL_CLI_C */
#if defined(POLARSSL_SSL_MAX_FRAGMENT_LENGTH)
/**
* \brief Set the maximum fragment length to emit and/or negotiate

11
library/ssl_cli.c
View file

@ -658,6 +658,17 @@ static int ssl_write_client_hello( ssl_context *ssl )
*p++ = (unsigned char)( ciphersuites[i] );
}
/* Some versions of OpenSSL don't handle it correctly if not at end */
#if defined(POLARSSL_SSL_FALLBACK_SCSV)
if( ssl->fallback == SSL_IS_FALLBACK )
{
SSL_DEBUG_MSG( 3, ( "adding FALLBACK_SCSV" ) );
*p++ = (unsigned char)( SSL_FALLBACK_SCSV >> 8 );
*p++ = (unsigned char)( SSL_FALLBACK_SCSV );
n++;
}
#endif
*q++ = (unsigned char)( n >> 7 );
*q++ = (unsigned char)( n << 1 );

47
library/ssl_srv.c
View file

@ -1088,6 +1088,30 @@ static int ssl_parse_client_hello_v2( ssl_context *ssl )
}
}
#if defined(POLARSSL_SSL_FALLBACK_SCSV)
for( i = 0, p = buf + 6; i < ciph_len; i += 3, p += 3 )
{
if( p[0] == 0 &&
p[1] == (unsigned char)( ( SSL_FALLBACK_SCSV >> 8 ) & 0xff ) &&
p[2] == (unsigned char)( ( SSL_FALLBACK_SCSV ) & 0xff ) )
{
SSL_DEBUG_MSG( 3, ( "received FALLBACK_SCSV" ) );
if( ssl->minor_ver < ssl->max_minor_ver )
{
SSL_DEBUG_MSG( 1, ( "inapropriate fallback" ) );
ssl_send_alert_message( ssl, SSL_ALERT_LEVEL_FATAL,
SSL_ALERT_MSG_INAPROPRIATE_FALLBACK );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
break;
}
}
#endif /* POLARSSL_SSL_FALLBACK_SCSV */
ciphersuites = ssl->ciphersuite_list[ssl->minor_ver];
ciphersuite_info = NULL;
#if defined(POLARSSL_SSL_SRV_RESPECT_CLIENT_PREFERENCE)
@ -1719,6 +1743,29 @@ read_record_header:
}
}
#if defined(POLARSSL_SSL_FALLBACK_SCSV)
for( i = 0, p = buf + 41 + sess_len; i < ciph_len; i += 2, p += 2 )
{
if( p[0] == (unsigned char)( ( SSL_FALLBACK_SCSV >> 8 ) & 0xff ) &&
p[1] == (unsigned char)( ( SSL_FALLBACK_SCSV ) & 0xff ) )
{
SSL_DEBUG_MSG( 0, ( "received FALLBACK_SCSV" ) );
if( ssl->minor_ver < ssl->max_minor_ver )
{
SSL_DEBUG_MSG( 0, ( "inapropriate fallback" ) );
ssl_send_alert_message( ssl, SSL_ALERT_LEVEL_FATAL,
SSL_ALERT_MSG_INAPROPRIATE_FALLBACK );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
break;
}
}
#endif /* POLARSSL_SSL_FALLBACK_SCSV */
/*
* Check for TLS_EMPTY_RENEGOTIATION_INFO_SCSV
*/

7
library/ssl_tls.c
View file

@ -5411,6 +5411,13 @@ int ssl_set_min_version( ssl_context *ssl, int major, int minor )
return( 0 );
}
#if defined(POLARSSL_SSL_FALLBACK_SCSV) && defined(POLARSSL_SSL_CLI_C)
void ssl_set_fallback( ssl_context *ssl, char fallback )
{
ssl->fallback = fallback;
}
#endif
#if defined(POLARSSL_SSL_MAX_FRAGMENT_LENGTH)
int ssl_set_max_frag_len( ssl_context *ssl, unsigned char mfl_code )
{

25
programs/ssl/ssl_client2.c
View file

@ -100,6 +100,7 @@ int main( int argc, char *argv[] )
#define DFL_TRANSPORT SSL_TRANSPORT_STREAM
#define DFL_HS_TO_MIN 0
#define DFL_HS_TO_MAX 0
#define DFL_FALLBACK -1
#define GET_REQUEST "GET %s HTTP/1.0\r\nExtra-header: "
#define GET_REQUEST_END "\r\n\r\n"
@ -142,6 +143,7 @@ struct options
int transport; /* TLS or DTLS? */
uint32_t hs_to_min; /* Initial value of DTLS handshake timer */
uint32_t hs_to_max; /* Max value of DTLS handshake timer */
int fallback; /* is this a fallback connection? */
} opt;
static void my_debug( void *ctx, int level, const char *str )
@ -303,6 +305,13 @@ static int my_verify( void *data, x509_crt *crt, int depth, int *flags )
#define USAGE_DTLS ""
#endif
#if defined(POLARSSL_SSL_FALLBACK_SCSV)
#define USAGE_FALLBACK \
" fallback=0/1 default: (library default: off)\n"
#else
#define USAGE_FALLBACK ""
#endif
#define USAGE \
"\n usage: ssl_client2 param=<>...\n" \
"\n acceptable parameters:\n" \
@ -336,6 +345,7 @@ static int my_verify( void *data, x509_crt *crt, int depth, int *flags )
USAGE_MAX_FRAG_LEN \
USAGE_TRUNC_HMAC \
USAGE_ALPN \
USAGE_FALLBACK \
"\n" \
" min_version=%%s default: \"\" (ssl3)\n" \
" max_version=%%s default: \"\" (tls1_2)\n" \
@ -441,6 +451,7 @@ int main( int argc, char *argv[] )
opt.transport = DFL_TRANSPORT;
opt.hs_to_min = DFL_HS_TO_MIN;
opt.hs_to_max = DFL_HS_TO_MAX;
opt.fallback = DFL_FALLBACK;
for( i = 1; i < argc; i++ )
{
@ -565,6 +576,15 @@ int main( int argc, char *argv[] )
{
opt.alpn_string = q;
}
else if( strcmp( p, "fallback" ) == 0 )
{
switch( atoi( q ) )
{
case 0: opt.fallback = SSL_IS_NOT_FALLBACK; break;
case 1: opt.fallback = SSL_IS_FALLBACK; break;
default: goto usage;
}
}
else if( strcmp( p, "min_version" ) == 0 )
{
if( strcmp( q, "ssl3" ) == 0 )
@ -1070,6 +1090,11 @@ int main( int argc, char *argv[] )
}
}
#if defined(POLARSSL_SSL_FALLBACK_SCSV)
if( opt.fallback != DFL_FALLBACK )
ssl_set_fallback( &ssl, opt.fallback );
#endif
printf( " ok\n" );
/*

93
tests/ssl-opt.sh
View file

@ -82,6 +82,21 @@ requires_openssl_with_sslv2() {
fi
}
# skip next test if OpenSSL doesn't support FALLBACK_SCSV
requires_openssl_with_fallback_scsv() {
if [ -z "${OPENSSL_HAS_FBSCSV:-}" ]; then
if $OPENSSL_CMD s_client -help 2>&1 | grep fallback_scsv >/dev/null
then
OPENSSL_HAS_FBSCSV="YES"
else
OPENSSL_HAS_FBSCSV="NO"
fi
fi
if [ "$OPENSSL_HAS_FBSCSV" = "NO" ]; then
SKIP_NEXT="YES"
fi
}
# skip next test if GnuTLS isn't available
requires_gnutls() {
if [ -z "${GNUTLS_AVAILABLE:-}" ]; then
@ -552,6 +567,84 @@ run_test "Truncated HMAC: actual test" \
0 \
-s "dumping 'computed mac' (10 bytes)"
# Tests for FALLBACK_SCSV
run_test "Fallback SCSV: default" \
"$P_SRV" \
"$P_CLI debug_level=3 force_version=tls1_1" \
0 \
-C "adding FALLBACK_SCSV" \
-S "received FALLBACK_SCSV" \
-S "inapropriate fallback" \
-C "is a fatal alert message (msg 86)"
run_test "Fallback SCSV: explicitly disabled" \
"$P_SRV" \
"$P_CLI debug_level=3 force_version=tls1_1 fallback=0" \
0 \
-C "adding FALLBACK_SCSV" \
-S "received FALLBACK_SCSV" \
-S "inapropriate fallback" \
-C "is a fatal alert message (msg 86)"
run_test "Fallback SCSV: enabled" \
"$P_SRV" \
"$P_CLI debug_level=3 force_version=tls1_1 fallback=1" \
1 \
-c "adding FALLBACK_SCSV" \
-s "received FALLBACK_SCSV" \
-s "inapropriate fallback" \
-c "is a fatal alert message (msg 86)"
run_test "Fallback SCSV: enabled, max version" \
"$P_SRV" \
"$P_CLI debug_level=3 fallback=1" \
0 \
-c "adding FALLBACK_SCSV" \
-s "received FALLBACK_SCSV" \
-S "inapropriate fallback" \
-C "is a fatal alert message (msg 86)"
requires_openssl_with_fallback_scsv
run_test "Fallback SCSV: default, openssl server" \
"$O_SRV" \
"$P_CLI debug_level=3 force_version=tls1_1 fallback=0" \
0 \
-C "adding FALLBACK_SCSV" \
-C "is a fatal alert message (msg 86)"
requires_openssl_with_fallback_scsv
run_test "Fallback SCSV: enabled, openssl server" \
"$O_SRV" \
"$P_CLI debug_level=3 force_version=tls1_1 fallback=1" \
1 \
-c "adding FALLBACK_SCSV" \
-c "is a fatal alert message (msg 86)"
requires_openssl_with_fallback_scsv
run_test "Fallback SCSV: disabled, openssl client" \
"$P_SRV" \
"$O_CLI -tls1_1" \
0 \
-S "received FALLBACK_SCSV" \
-S "inapropriate fallback"
requires_openssl_with_fallback_scsv
run_test "Fallback SCSV: enabled, openssl client" \
"$P_SRV" \
"$O_CLI -tls1_1 -fallback_scsv" \
1 \
-s "received FALLBACK_SCSV" \
-s "inapropriate fallback"
requires_openssl_with_fallback_scsv
run_test "Fallback SCSV: enabled, max version, openssl client" \
"$P_SRV" \
"$O_CLI -fallback_scsv" \
0 \
-s "received FALLBACK_SCSV" \
-S "inapropriate fallback"
# Tests for Session Tickets
run_test "Session resume using tickets: basic" \