Forbid EMS from changing during renegotation.
Changing parameters on renegotiation makes all our APIs confusing. This
one has no reason to change, so lock it down. In particular, our
preference to forbid Token Binding + renego may be overridden at the
IETF, even though it's insane. Loosening it will be a bit less of a
headache if EMS can't change.
https://www.ietf.org/mail-archive/web/unbearable/current/msg00690.html
claims that this is already in the specification and enforced by NSS. I
can't find anything to this effect in the specification. It just says
the client MUST disable renegotiation when EMS is missing, which is
wishful thinking. At a glance, NSS doesn't seem to check, though I could
be misunderstanding the code.
Nonetheless, locking this down is a good idea anyway. Accurate or not,
take the email as an implicit endorsement of this from Mozilla.
Change-Id: I236b05991d28bed199763dcf2f47bbfb9d0322d7
Reviewed-on: https://boringssl-review.googlesource.com/10721
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 4a88488..9787bcb 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -4811,6 +4811,7 @@
#define SSL_R_TOO_MANY_KEY_UPDATES 260
#define SSL_R_BLOCK_CIPHER_PAD_IS_WRONG 261
#define SSL_R_NO_CIPHERS_SPECIFIED 262
+#define SSL_R_RENEGOTIATION_EMS_MISMATCH 263
#define SSL_R_SSLV3_ALERT_CLOSE_NOTIFY 1000
#define SSL_R_SSLV3_ALERT_UNEXPECTED_MESSAGE 1010
#define SSL_R_SSLV3_ALERT_BAD_RECORD_MAC 1020