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+From 29ee67c205855e848a0a26e6d0e4f65b6b943e0a Mon Sep 17 00:00:00 2001
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+From: Daiki Ueno <ueno@gnu.org>
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+Date: Sat, 22 Aug 2020 17:19:39 +0200
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+Subject: [PATCH] handshake: reject no_renegotiation alert if handshake is
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+ incomplete
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+
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+If the initial handshake is incomplete and the server sends a
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+no_renegotiation alert, the client should treat it as a fatal error
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+even if its level is warning. Otherwise the same handshake
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+state (e.g., DHE parameters) are reused in the next gnutls_handshake
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+call, if it is called in the loop idiom:
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+
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+ do {
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+ ret = gnutls_handshake(session);
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+ } while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
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+
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+Signed-off-by: Daiki Ueno <ueno@gnu.org>
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+CVE: CVE-2020-24659
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+Upstream-Status: Backport [https://gitlab.com/gnutls/gnutls.git]
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+Signed-off-by: Zhixiong Chi <zhixiong.chi@windriver.com>
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+---
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+ lib/gnutls_int.h | 1 +
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+ lib/handshake.c | 48 +++++++++++++-----
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+ 2 files changed, 36 insertions(+), 13 deletions(-)
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+
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+diff --git a/lib/gnutls_int.h b/lib/gnutls_int.h
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+index bb6c19713..31cec5c0c 100644
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+--- a/lib/gnutls_int.h
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++++ b/lib/gnutls_int.h
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+@@ -1370,6 +1370,7 @@ typedef struct {
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+ #define HSK_RECORD_SIZE_LIMIT_RECEIVED (1<<26) /* server: record_size_limit extension was seen but not accepted yet */
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+ #define HSK_OCSP_REQUESTED (1<<27) /* server: client requested OCSP stapling */
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+ #define HSK_CLIENT_OCSP_REQUESTED (1<<28) /* client: server requested OCSP stapling */
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++#define HSK_SERVER_HELLO_RECEIVED (1<<29) /* client: Server Hello message has been received */
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+
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+ /* The hsk_flags are for use within the ongoing handshake;
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+ * they are reset to zero prior to handshake start by gnutls_handshake. */
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+diff --git a/lib/handshake.c b/lib/handshake.c
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+index b40f84b3d..ce2d160e2 100644
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+--- a/lib/handshake.c
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++++ b/lib/handshake.c
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+@@ -2051,6 +2051,8 @@ read_server_hello(gnutls_session_t session,
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+ if (ret < 0)
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+ return gnutls_assert_val(ret);
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+
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++ session->internals.hsk_flags |= HSK_SERVER_HELLO_RECEIVED;
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++
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+ return 0;
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+ }
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+
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+@@ -2575,16 +2577,42 @@ int gnutls_rehandshake(gnutls_session_t session)
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+ return 0;
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+ }
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+
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++/* This function checks whether the error code should be treated fatal
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++ * or not, and also does the necessary state transition. In
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++ * particular, in the case of a rehandshake abort it resets the
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++ * handshake's internal state.
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++ */
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+ inline static int
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+ _gnutls_abort_handshake(gnutls_session_t session, int ret)
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+ {
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+- if (((ret == GNUTLS_E_WARNING_ALERT_RECEIVED) &&
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+- (gnutls_alert_get(session) == GNUTLS_A_NO_RENEGOTIATION))
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+- || ret == GNUTLS_E_GOT_APPLICATION_DATA)
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+- return 0;
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++ switch (ret) {
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++ case GNUTLS_E_WARNING_ALERT_RECEIVED:
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++ if (gnutls_alert_get(session) == GNUTLS_A_NO_RENEGOTIATION) {
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++ /* The server always toleretes a "no_renegotiation" alert. */
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++ if (session->security_parameters.entity == GNUTLS_SERVER) {
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++ STATE = STATE0;
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++ return ret;
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++ }
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++
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++ /* The client should tolerete a "no_renegotiation" alert only if:
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++ * - the initial handshake has completed, or
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++ * - a Server Hello is not yet received
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++ */
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++ if (session->internals.initial_negotiation_completed ||
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++ !(session->internals.hsk_flags & HSK_SERVER_HELLO_RECEIVED)) {
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++ STATE = STATE0;
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++ return ret;
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++ }
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+
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+- /* this doesn't matter */
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+- return GNUTLS_E_INTERNAL_ERROR;
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++ return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET);
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++ }
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++ return ret;
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++ case GNUTLS_E_GOT_APPLICATION_DATA:
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++ STATE = STATE0;
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++ return ret;
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++ default:
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++ return ret;
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++ }
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+ }
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+
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+
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+@@ -2747,13 +2774,7 @@ int gnutls_handshake(gnutls_session_t session)
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+ }
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+
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+ if (ret < 0) {
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+- /* In the case of a rehandshake abort
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+- * we should reset the handshake's internal state.
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+- */
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+- if (_gnutls_abort_handshake(session, ret) == 0)
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+- STATE = STATE0;
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+-
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+- return ret;
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++ return _gnutls_abort_handshake(session, ret);
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+ }
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+
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+ /* clear handshake buffer */
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+--
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+2.17.0
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+
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