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Validate legacy_version

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The spec says that a client MUST set legacy_version to TLSv1.2, and
requires servers to verify that it isn't SSLv3.

Fixes #6600

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6747)
This commit is contained in:
Matt Caswell 2018-07-19 16:51:58 +01:00
parent d6ce9da49b
commit d8434cf856
5 changed files with 28 additions and 5 deletions
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1
crypto/err/openssl.txt
View file

@ -2581,6 +2581,7 @@ SSL_R_BAD_HELLO_REQUEST:105:bad hello request
SSL_R_BAD_HRR_VERSION:263:bad hrr version
SSL_R_BAD_KEY_SHARE:108:bad key share
SSL_R_BAD_KEY_UPDATE:122:bad key update
SSL_R_BAD_LEGACY_VERSION:292:bad legacy version
SSL_R_BAD_LENGTH:271:bad length
SSL_R_BAD_PACKET:240:bad packet
SSL_R_BAD_PACKET_LENGTH:115:bad packet length

1
include/openssl/sslerr.h
View file

@ -471,6 +471,7 @@ int ERR_load_SSL_strings(void);
# define SSL_R_BAD_HRR_VERSION 263
# define SSL_R_BAD_KEY_SHARE 108
# define SSL_R_BAD_KEY_UPDATE 122
# define SSL_R_BAD_LEGACY_VERSION 292
# define SSL_R_BAD_LENGTH 271
# define SSL_R_BAD_PACKET 240
# define SSL_R_BAD_PACKET_LENGTH 115

1
ssl/ssl_err.c
View file

@ -757,6 +757,7 @@ static const ERR_STRING_DATA SSL_str_reasons[] = {
{ERR_PACK(ERR_LIB_SSL, 0, SSL_R_BAD_HRR_VERSION), "bad hrr version"},
{ERR_PACK(ERR_LIB_SSL, 0, SSL_R_BAD_KEY_SHARE), "bad key share"},
{ERR_PACK(ERR_LIB_SSL, 0, SSL_R_BAD_KEY_UPDATE), "bad key update"},
{ERR_PACK(ERR_LIB_SSL, 0, SSL_R_BAD_LEGACY_VERSION), "bad legacy version"},
{ERR_PACK(ERR_LIB_SSL, 0, SSL_R_BAD_LENGTH), "bad length"},
{ERR_PACK(ERR_LIB_SSL, 0, SSL_R_BAD_PACKET), "bad packet"},
{ERR_PACK(ERR_LIB_SSL, 0, SSL_R_BAD_PACKET_LENGTH), "bad packet length"},

12
ssl/statem/statem_lib.c
View file

@ -1753,6 +1753,18 @@ int ssl_choose_server_version(SSL *s, CLIENTHELLO_MSG *hello, DOWNGRADE *dgrd)
return SSL_R_LENGTH_MISMATCH;
}
/*
* The TLSv1.3 spec says the client MUST set this to TLS1_2_VERSION.
* The spec only requires servers to check that it isn't SSLv3:
* "Any endpoint receiving a Hello message with
* ClientHello.legacy_version or ServerHello.legacy_version set to
* 0x0300 MUST abort the handshake with a "protocol_version" alert."
* We are slightly stricter and require that it isn't SSLv3 or lower.
* We tolerate TLSv1 and TLSv1.1.
*/
if (client_version <= SSL3_VERSION)
return SSL_R_BAD_LEGACY_VERSION;
while (PACKET_get_net_2(&versionslist, &candidate_vers)) {
/* TODO(TLS1.3): Remove this before release */
if (candidate_vers == TLS1_3_VERSION_DRAFT

18
test/recipes/70-test_sslversions.t
View file

@ -18,7 +18,8 @@ use constant {
NO_EXTENSION => 3,
EMPTY_EXTENSION => 4,
TLS1_1_AND_1_0_ONLY => 5,
WITH_TLS1_4 => 6
WITH_TLS1_4 => 6,
BAD_LEGACY_VERSION => 7
};
my $testtype;
@ -55,7 +56,7 @@ my $proxy = TLSProxy::Proxy->new(
$testtype = EMPTY_EXTENSION;
$proxy->filter(\&modify_supported_versions_filter);
$proxy->start() or plan skip_all => "Unable to start up Proxy for tests";
plan tests => 7;
plan tests => 8;
ok(TLSProxy::Message->fail(), "Empty supported versions");
#Test 2: supported_versions extension with no recognised versions should not
@ -111,6 +112,12 @@ ok(TLSProxy::Message->success()
&& TLSProxy::Proxy->is_tls13(),
"TLS1.4 in supported versions extension");
#Test 8: Set the legacy version to SSLv3 with supported versions. Should fail
$proxy->clear();
$testtype = BAD_LEGACY_VERSION;
$proxy->start();
ok(TLSProxy::Message->fail(), "Legacy version is SSLv3 with supported versions");
sub modify_supported_versions_filter
{
my $proxy = shift;
@ -165,14 +172,15 @@ sub modify_supported_versions_filter
} elsif ($testtype == EMPTY_EXTENSION) {
$message->set_extension(
TLSProxy::Message::EXT_SUPPORTED_VERSIONS, "");
} else {
} elsif ($testtype == NO_EXTENSION) {
$message->delete_extension(
TLSProxy::Message::EXT_SUPPORTED_VERSIONS);
} else {
# BAD_LEGACY_VERSION
$message->client_version(TLSProxy::Record::VERS_SSL_3_0);
}
$message->repack();
}
}
}