From b798ea88ac6e924363b7b12b6b847b302a76fb31 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 4 Aug 2017 11:07:10 -0400 Subject: [PATCH] Disallow SSL session tickets. We don't actually support session tickets, since we do not create an SSL session identifier. But it seems that OpenSSL will issue a session ticket on-demand anyway, which will then fail when used. This results in reconnection failures when using ticket-aware client-side SSL libraries (such as the Npgsql .NET driver), as reported by Shay Rojansky. To fix, just tell OpenSSL not to issue tickets. At some point in the far future, we might consider enabling tickets instead. But the security implications of that aren't entirely clear; and besides it would have little benefit except for very short-lived database connections, which is Something We're Bad At anyhow. It would take a lot of other work to get to a point where that would really be an exciting thing to do. While at it, also tell OpenSSL not to use a session cache. This doesn't really do anything, since a backend would never populate the cache anyway, but it might gain some micro-efficiencies and/or reduce security exposures. Patch by me, per discussion with Heikki Linnakangas and Shay Rojansky. Back-patch to all supported versions. Discussion: https://postgr.es/m/CADT4RqBU8N-csyZuzaook-c795dt22Zcwg1aHWB6tfVdAkodZA@mail.gmail.com --- src/backend/libpq/be-secure-openssl.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/backend/libpq/be-secure-openssl.c b/src/backend/libpq/be-secure-openssl.c index 2ff9d1cf85..5a174bbe84 100644 --- a/src/backend/libpq/be-secure-openssl.c +++ b/src/backend/libpq/be-secure-openssl.c @@ -270,6 +270,14 @@ be_tls_init(void) SSL_OP_SINGLE_DH_USE | SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3); + /* disallow SSL session tickets */ +#ifdef SSL_OP_NO_TICKET /* added in openssl 0.9.8f */ + SSL_CTX_set_options(SSL_context, SSL_OP_NO_TICKET); +#endif + + /* disallow SSL session caching, too */ + SSL_CTX_set_session_cache_mode(SSL_context, SSL_SESS_CACHE_OFF); + /* set up ephemeral ECDH keys */ initialize_ecdh();