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help / color / mirror / Atom feedFrom: Daniel Gustafsson <[email protected]>
To: Andres Freund <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Subject: Re: tls 1.3: sending multiple tickets
Date: Tue, 18 Jun 2024 15:11:33 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
> On 17 Jun 2024, at 19:38, Andres Freund <[email protected]> wrote:
> Note the second to last paragraph: Because we use SSL_OP_NO_TICKET we trigger
> use of stateful tickets. Which afaict are never going to be useful, because we
> don't share the necessary state.
Nice catch, I learned something new today. I was under the impression that the
flag turned of all tickets but clearly not.
> I guess openssl really could have inferred this from the fact that we *do*
> call SSL_CTX_set_session_cache_mode(SSL_SESS_CACHE_OFF), b
Every day with the OpenSSL API is an adventure.
> Seems we ought to use SSL_CTX_set_num_tickets() to prevent issuing the useless
> tickets?
Agreed, in 1.1.1 and above as the API was only introduced then. LibreSSL added
the API in 3.5.4 but only for compatibility since it doesn't support TLS
tickets at all.
> It seems like a buglet in openssl that it forces each session tickets to be
> sent in its own packet (it does an explicit BIO_flush(), so even if we
> buffered between openssl and OS, as I think we should, we'd still send it
> separately), but I don't really understand most of this stuff.
I don't see anything in the RFCs so not sure.
The attached applies this, and I think this is backpatching material since we
arguably fail to do what we say in the code. AFAIK we don't have a hard rule
against backpatching changes to autoconf/meson?
--
Daniel Gustafsson
Attachments:
[application/octet-stream] v1-0001-Disable-all-TLS-session-tickets.patch (4.1K, ../[email protected]/2-v1-0001-Disable-all-TLS-session-tickets.patch)
download | inline diff:
From 5c21ebe072d1c877d7fe8f676879b9a8af76eb1c Mon Sep 17 00:00:00 2001
From: Daniel Gustafsson <[email protected]>
Date: Tue, 18 Jun 2024 14:50:39 +0200
Subject: [PATCH v1] Disable all TLS session tickets
OpenSSL supports two types of session tickets for TLSv1.3, stateless
and stateful. The option we've used only turns off stateless tickets
leaving stateful tickets active. Use the new API introduced in 1.1.1
to disable all types of tickets.
Reported-by: Andres Freund <[email protected]>
Discussion: https://postgr.es/m/[email protected]
---
configure | 9 +++++----
configure.ac | 2 +-
meson.build | 1 +
src/backend/libpq/be-secure-openssl.c | 14 +++++++++++++-
src/include/pg_config.h.in | 3 +++
5 files changed, 23 insertions(+), 6 deletions(-)
diff --git a/configure b/configure
index 7b03db56a6..519a2e5ce6 100755
--- a/configure
+++ b/configure
@@ -12591,12 +12591,13 @@ fi
done
# Function introduced in OpenSSL 1.1.1.
- for ac_func in X509_get_signature_info
+ for ac_func in X509_get_signature_info SSL_CTX_set_num_tickets
do :
- ac_fn_c_check_func "$LINENO" "X509_get_signature_info" "ac_cv_func_X509_get_signature_info"
-if test "x$ac_cv_func_X509_get_signature_info" = xyes; then :
+ as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
+ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
+if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
cat >>confdefs.h <<_ACEOF
-#define HAVE_X509_GET_SIGNATURE_INFO 1
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
_ACEOF
fi
diff --git a/configure.ac b/configure.ac
index 63e7be3847..6e28c2d04c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1358,7 +1358,7 @@ if test "$with_ssl" = openssl ; then
# function was removed.
AC_CHECK_FUNCS([CRYPTO_lock])
# Function introduced in OpenSSL 1.1.1.
- AC_CHECK_FUNCS([X509_get_signature_info])
+ AC_CHECK_FUNCS([X509_get_signature_info SSL_CTX_set_num_tickets])
AC_DEFINE([USE_OPENSSL], 1, [Define to 1 to build with OpenSSL support. (--with-ssl=openssl)])
elif test "$with_ssl" != no ; then
AC_MSG_ERROR([--with-ssl must specify openssl])
diff --git a/meson.build b/meson.build
index 2767abd19e..e21f88b529 100644
--- a/meson.build
+++ b/meson.build
@@ -1293,6 +1293,7 @@ if sslopt in ['auto', 'openssl']
# Function introduced in OpenSSL 1.1.1
['X509_get_signature_info'],
+ ['SSL_CTX_set_num_tickets'],
]
are_openssl_funcs_complete = true
diff --git a/src/backend/libpq/be-secure-openssl.c b/src/backend/libpq/be-secure-openssl.c
index 39b1a66236..d257b93104 100644
--- a/src/backend/libpq/be-secure-openssl.c
+++ b/src/backend/libpq/be-secure-openssl.c
@@ -258,8 +258,20 @@ be_tls_init(bool isServerStart)
}
}
- /* disallow SSL session tickets */
+ /*
+ * Disallow SSL session tickets. OpenSSL use both stateful and stateless
+ * tickets for TLSv1.3, and stateless ticket for TLSv1.2. SSL_OP_NO_TICKET
+ * is available since 1.0.0 but only turns off stateless tickets. In order
+ * to turn off stateful tickets we also need SSL_CTX_set_num_tickets, which
+ * is available since OpenSSL 1.1.1. LibreSSL 3.5.4 (from OpenBSD 7.1)
+ * introduced this API for compatibility, but doesn't support session
+ * tickets at all so it's a no-op there.
+ */
+#ifdef HAVE_SSL_CTX_SET_NUM_TICKETS
+ SSL_CTX_set_num_tickets(context, 0);
+#else
SSL_CTX_set_options(context, SSL_OP_NO_TICKET);
+#endif
/* disallow SSL session caching, too */
SSL_CTX_set_session_cache_mode(context, SSL_SESS_CACHE_OFF);
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index f8d3e3b6b8..e2834912f8 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -510,6 +510,9 @@
/* Define to 1 if you have the `X509_get_signature_info' function. */
#undef HAVE_X509_GET_SIGNATURE_INFO
+/* Define to 1 if you have the `SSL_CTX_set_num_tickets' function. */
+#undef HAVE_SSL_CTX_SET_NUM_TICKETS
+
/* Define to 1 if the assembler supports X86_64's POPCNTQ instruction. */
#undef HAVE_X86_64_POPCNTQ
--
2.39.3 (Apple Git-146)
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