The branch OpenSSL_1_1_0-stable has been updated
via 12492580ffd561764111b5efbafde17125b91e92 (commit)
from c6a351a54c8a9fbcdf07ae2171ab8f6dd4416a5d (commit)
- Log -----------------------------------------------------------------
commit 12492580ffd561764111b5efbafde17125b91e92
Author: Matt Caswell <m...@openssl.org>
Date: Mon Jan 29 14:55:44 2018 +0000
Make sure we check an incoming reneg ClientHello in DTLS
In TLS we have a check to make sure an incoming reneg ClientHello is
acceptable. The equivalent check is missing in the DTLS code. This means
that if a client does not signal the ability to handle secure reneg in the
initial handshake, then a subsequent reneg handshake should be rejected by
the server. In the DTLS case the reneg was being allowed if the the 2nd
ClientHello had a renegotiation_info extension. This is incorrect.
While incorrect, this does not represent a security issue because if
the renegotiation_info extension is present in the second ClientHello it
also has to be *correct*. Therefore this will only work if both the client
and server believe they are renegotiating, and both know the previous
Finished result. This is not the case in an insecure rengotiation attack.
I have also tidied up the check in the TLS code and given a better check
for determining whether we are renegotiating or not.
Reviewed-by: Rich Salz <rs...@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5191)
-----------------------------------------------------------------------
Summary of changes:
ssl/record/rec_layer_d1.c | 17 +++++++++++++++++
ssl/record/rec_layer_s3.c | 19 +++++++++----------
2 files changed, 26 insertions(+), 10 deletions(-)
diff --git a/ssl/record/rec_layer_d1.c b/ssl/record/rec_layer_d1.c
index f674b79..e7c4814 100644
--- a/ssl/record/rec_layer_d1.c
+++ b/ssl/record/rec_layer_d1.c
@@ -686,6 +686,23 @@ int dtls1_read_bytes(SSL *s, int type, int *recvd_type,
unsigned char *buf,
goto start;
}
+ /*
+ * If we are a server and get a client hello when renegotiation isn't
+ * allowed send back a no renegotiation alert and carry on.
+ */
+ if (s->server
+ && SSL_is_init_finished(s)
+ && !s->s3->send_connection_binding
+ && s->rlayer.d->handshake_fragment_len >= DTLS1_HM_HEADER_LENGTH
+ && s->rlayer.d->handshake_fragment[0] == SSL3_MT_CLIENT_HELLO
+ && s->s3->previous_client_finished_len != 0
+ && (s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION) == 0) {
+ s->rlayer.d->handshake_fragment_len = 0;
+ SSL3_RECORD_set_length(rr, 0);
+ ssl3_send_alert(s, SSL3_AL_WARNING, SSL_AD_NO_RENEGOTIATION);
+ goto start;
+ }
+
if (s->rlayer.d->alert_fragment_len >= DTLS1_AL_HEADER_LENGTH) {
int alert_level = s->rlayer.d->alert_fragment[0];
int alert_descr = s->rlayer.d->alert_fragment[1];
diff --git a/ssl/record/rec_layer_s3.c b/ssl/record/rec_layer_s3.c
index ce3f93d..0aad575 100644
--- a/ssl/record/rec_layer_s3.c
+++ b/ssl/record/rec_layer_s3.c
@@ -1330,17 +1330,16 @@ int ssl3_read_bytes(SSL *s, int type, int *recvd_type,
unsigned char *buf,
}
/*
* If we are a server and get a client hello when renegotiation isn't
- * allowed send back a no renegotiation alert and carry on. WARNING:
- * experimental code, needs reviewing (steve)
+ * allowed send back a no renegotiation alert and carry on.
*/
- if (s->server &&
- SSL_is_init_finished(s) &&
- !s->s3->send_connection_binding &&
- (s->version > SSL3_VERSION) &&
- (s->rlayer.handshake_fragment_len >= 4) &&
- (s->rlayer.handshake_fragment[0] == SSL3_MT_CLIENT_HELLO) &&
- (s->session != NULL) && (s->session->cipher != NULL) &&
- !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
+ if (s->server
+ && SSL_is_init_finished(s)
+ && !s->s3->send_connection_binding
+ && s->version > SSL3_VERSION
+ && s->rlayer.handshake_fragment_len >= SSL3_HM_HEADER_LENGTH
+ && s->rlayer.handshake_fragment[0] == SSL3_MT_CLIENT_HELLO
+ && s->s3->previous_client_finished_len != 0
+ && (s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION) == 0) {
SSL3_RECORD_set_length(rr, 0);
SSL3_RECORD_set_read(rr);
ssl3_send_alert(s, SSL3_AL_WARNING, SSL_AD_NO_RENEGOTIATION);
_____
openssl-commits mailing list
To unsubscribe: https://mta.openssl.org/mailman/listinfo/openssl-commits
