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commit    3f8072be8a71b5bd3dc838a4ba03ccdaff2d975e
Author:   Michael Paquier <michael@paquier.xyz>
Date:     Tue May 25 01:11:17 2021 +0000
First released in: 14.0, 9.6.23, 10.18, 11.13, 12.8, 13.4

    Disallow SSL renegotiation
    
    SSL renegotiation is already disabled as of 48d23c72, however this does
    not prevent the server to comply with a client willing to use
    renegotiation.  In the last couple of years, renegotiation had its set
    of security issues and flaws (like the recent CVE-2021-3449), and it
    could be possible to crash the backend with a client attempting
    renegotiation.
    
    This commit takes one extra step by disabling renegotiation in the
    backend in the same way as SSL compression (f9264d15) or tickets
    (97d3a0b0).  OpenSSL 1.1.0h has added an option named
    SSL_OP_NO_RENEGOTIATION able to achieve that.  In older versions
    there is an option called SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS that
    was undocumented, and could be set within the SSL object created when
    the TLS connection opens, but I have decided not to use it, as it feels
    trickier to rely on, and it is not official.  Note that this option is
    not usable in OpenSSL < 1.1.0h as the internal contents of the *SSL
    object are hidden to applications.
    
    SSL renegotiation concerns protocols up to TLSv1.2.
    
    Per original report from Robert Haas, with a patch based on a suggestion
    by Andres Freund.
    
    Author: Michael Paquier
    Reviewed-by: Daniel Gustafsson
    Discussion: https://postgr.es/m/YKZBXx7RhU74FlTE@paquier.xyz
    Backpatch-through: 9.6


 src/backend/libpq/be-secure-openssl.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/backend/libpq/be-secure-openssl.c b/src/backend/libpq/be-secure-openssl.c
index 2536af8b3b8..2743443f3f1 100644
--- a/src/backend/libpq/be-secure-openssl.c
+++ b/src/backend/libpq/be-secure-openssl.c
@@ -233,6 +233,16 @@ be_tls_init(bool isServerStart)
 	/* disallow SSL session caching, too */
 	SSL_CTX_set_session_cache_mode(context, SSL_SESS_CACHE_OFF);
 
+#ifdef SSL_OP_NO_RENEGOTIATION
+
+	/*
+	 * Disallow SSL renegotiation, option available since 1.1.0h.  This
+	 * concerns only TLSv1.2 and older protocol versions, as TLSv1.3 has no
+	 * support for renegotiation.
+	 */
+	SSL_CTX_set_options(context, SSL_OP_NO_RENEGOTIATION);
+#endif
+
 	/* set up ephemeral DH and ECDH keys */
 	if (!initialize_dh(context, isServerStart))
 		goto error;


[parent: 61feb8670824]