From c97e457d53441c6cb377cdda08905203db8afa0f Mon Sep 17 00:00:00 2001
From: "Dr. Stephen Henson" <steve@openssl.org>
Date: Fri, 16 May 2014 12:49:48 +0100
Subject: [PATCH] Fix for CVE-2014-0224
Only accept change cipher spec when it is expected instead of at any
time. This prevents premature setting of session keys before the master
secret is determined which an attacker could use as a MITM attack.
Thanks to KIKUCHI Masashi (Lepidum Co. Ltd.) for reporting this issue
and providing the initial fix this patch is based on.
---
ssl/s3_clnt.c | 2 ++
ssl/s3_pkt.c | 9 +++++++++
ssl/s3_srvr.c | 2 ++
ssl/ssl3.h | 1 +
4 files changed, 14 insertions(+)
diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c
index f1f9c219e..450d55928 100644
--- a/ssl/s3_clnt.c
+++ b/ssl/s3_clnt.c
@@ -516,6 +516,7 @@ int ssl3_connect(SSL *s)
case SSL3_ST_CR_FINISHED_A:
case SSL3_ST_CR_FINISHED_B:
+ s->s3->flags |= SSL3_FLAGS_CCS_OK;
ret=ssl3_get_finished(s,SSL3_ST_CR_FINISHED_A,
SSL3_ST_CR_FINISHED_B);
if (ret <= 0) goto end;
@@ -829,6 +830,7 @@ int ssl3_get_server_hello(SSL *s)
SSLerr(SSL_F_SSL3_GET_SERVER_HELLO,SSL_R_ATTEMPT_TO_REUSE_SESSION_IN_DIFFERENT_CONTEXT);
goto f_err;
}
+ s->s3->flags |= SSL3_FLAGS_CCS_OK;
s->hit=1;
}
else /* a miss or crap from the other end */
diff --git a/ssl/s3_pkt.c b/ssl/s3_pkt.c
index 988bfe570..8950e902a 100644
--- a/ssl/s3_pkt.c
+++ b/ssl/s3_pkt.c
@@ -1258,6 +1258,15 @@ start:
goto f_err;
}
+ if (!(s->s3->flags & SSL3_FLAGS_CCS_OK))
+ {
+ al=SSL_AD_UNEXPECTED_MESSAGE;
+ SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_CCS_RECEIVED_EARLY);
+ goto f_err;
+ }
+
+ s->s3->flags &= ~SSL3_FLAGS_CCS_OK;
+
rr->length=0;
if (s->msg_callback)
diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index b4ec01011..9c29cdfe0 100644
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -578,6 +578,7 @@ int ssl3_accept(SSL *s)
case SSL3_ST_SR_CERT_VRFY_A:
case SSL3_ST_SR_CERT_VRFY_B:
+ s->s3->flags |= SSL3_FLAGS_CCS_OK;
/* we should decide if we expected this one */
ret=ssl3_get_cert_verify(s);
if (ret <= 0) goto end;
@@ -588,6 +589,7 @@ int ssl3_accept(SSL *s)
case SSL3_ST_SR_FINISHED_A:
case SSL3_ST_SR_FINISHED_B:
+ s->s3->flags |= SSL3_FLAGS_CCS_OK;
ret=ssl3_get_finished(s,SSL3_ST_SR_FINISHED_A,
SSL3_ST_SR_FINISHED_B);
if (ret <= 0) goto end;
diff --git a/ssl/ssl3.h b/ssl/ssl3.h
index 7686472a0..9664a8b14 100644
--- a/ssl/ssl3.h
+++ b/ssl/ssl3.h
@@ -379,6 +379,7 @@ typedef struct ssl3_buffer_st
#define SSL3_FLAGS_POP_BUFFER 0x0004
#define TLS1_FLAGS_TLS_PADDING_BUG 0x0008
#define TLS1_FLAGS_SKIP_CERT_VERIFY 0x0010
+#define SSL3_FLAGS_CCS_OK 0x0080
/* SSL3_FLAGS_SGC_RESTART_DONE is set when we
* restart a handshake because of MS SGC and so prevents us