From: Daniel Gustafsson <daniel@yesql.se>
Message-Id: <4FEAF57B-FFCD-4A91-BE4E-9F17C01AF7C5@yesql.se>
Content-Type: multipart/mixed;
	boundary="Apple-Mail=_8668B109-EB2A-4530-B834-3F4EE98353A0"
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.500.171.1.1\))
Subject: Re: tls 1.3: sending multiple tickets
Date: Tue, 18 Jun 2024 15:11:33 +0200
In-Reply-To: <20240617173803.6alnafnxpiqvlh3g@awork3.anarazel.de>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
To: Andres Freund <andres@anarazel.de>
References: <20240617173803.6alnafnxpiqvlh3g@awork3.anarazel.de>
Archived-At: <https://www.postgresql.org/message-id/4FEAF57B-FFCD-4A91-BE4E-9F17C01AF7C5%40yesql.se>
Precedence: bulk


--Apple-Mail=_8668B109-EB2A-4530-B834-3F4EE98353A0
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=us-ascii

> On 17 Jun 2024, at 19:38, Andres Freund <andres@anarazel.de> 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


--Apple-Mail=_8668B109-EB2A-4530-B834-3F4EE98353A0
Content-Disposition: attachment;
	filename=v1-0001-Disable-all-TLS-session-tickets.patch
Content-Type: application/octet-stream;
	x-unix-mode=0644;
	name="v1-0001-Disable-all-TLS-session-tickets.patch"
Content-Transfer-Encoding: quoted-printable

=46rom=205c21ebe072d1c877d7fe8f676879b9a8af76eb1c=20Mon=20Sep=2017=20=
00:00:00=202001=0AFrom:=20Daniel=20Gustafsson=20=
<dgustafsson@postgresql.org>=0ADate:=20Tue,=2018=20Jun=202024=2014:50:39=20=
+0200=0ASubject:=20[PATCH=20v1]=20Disable=20all=20TLS=20session=20=
tickets=0A=0AOpenSSL=20supports=20two=20types=20of=20session=20tickets=20=
for=20TLSv1.3,=20stateless=0Aand=20stateful.=20The=20option=20we've=20=
used=20only=20turns=20off=20stateless=20tickets=0Aleaving=20stateful=20=
tickets=20active.=20Use=20the=20new=20API=20introduced=20in=201.1.1=0Ato=20=
disable=20all=20types=20of=20tickets.=0A=0AReported-by:=20Andres=20=
Freund=20<andres@anarazel.de>=0ADiscussion:=20=
https://postgr.es/m/20240617173803.6alnafnxpiqvlh3g@awork3.anarazel.de=0A=
---=0A=20configure=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20|=20=209=20+++++----=0A=20configure.ac=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
|=20=202=20+-=0A=20meson.build=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20|=20=201=20+=0A=20=
src/backend/libpq/be-secure-openssl.c=20|=2014=20+++++++++++++-=0A=20=
src/include/pg_config.h.in=20=20=20=20=20=20=20=20=20=20=20=20|=20=203=20=
+++=0A=205=20files=20changed,=2023=20insertions(+),=206=20deletions(-)=0A=
=0Adiff=20--git=20a/configure=20b/configure=0Aindex=20=
7b03db56a6..519a2e5ce6=20100755=0A---=20a/configure=0A+++=20b/configure=0A=
@@=20-12591,12=20+12591,13=20@@=20fi=0A=20done=0A=20=0A=20=20=20#=20=
Function=20introduced=20in=20OpenSSL=201.1.1.=0A-=20=20for=20ac_func=20=
in=20X509_get_signature_info=0A+=20=20for=20ac_func=20in=20=
X509_get_signature_info=20SSL_CTX_set_num_tickets=0A=20do=20:=0A-=20=20=
ac_fn_c_check_func=20"$LINENO"=20"X509_get_signature_info"=20=
"ac_cv_func_X509_get_signature_info"=0A-if=20test=20=
"x$ac_cv_func_X509_get_signature_info"=20=3D=20xyes;=20then=20:=0A+=20=20=
as_ac_var=3D`$as_echo=20"ac_cv_func_$ac_func"=20|=20$as_tr_sh`=0A=
+ac_fn_c_check_func=20"$LINENO"=20"$ac_func"=20"$as_ac_var"=0A+if=20eval=20=
test=20\"x\$"$as_ac_var"\"=20=3D=20x"yes";=20then=20:=0A=20=20=20cat=20=
>>confdefs.h=20<<_ACEOF=0A-#define=20HAVE_X509_GET_SIGNATURE_INFO=201=0A=
+#define=20`$as_echo=20"HAVE_$ac_func"=20|=20$as_tr_cpp`=201=0A=20_ACEOF=0A=
=20=0A=20fi=0Adiff=20--git=20a/configure.ac=20b/configure.ac=0Aindex=20=
63e7be3847..6e28c2d04c=20100644=0A---=20a/configure.ac=0A+++=20=
b/configure.ac=0A@@=20-1358,7=20+1358,7=20@@=20if=20test=20"$with_ssl"=20=
=3D=20openssl=20;=20then=0A=20=20=20#=20function=20was=20removed.=0A=20=20=
=20AC_CHECK_FUNCS([CRYPTO_lock])=0A=20=20=20#=20Function=20introduced=20=
in=20OpenSSL=201.1.1.=0A-=20=20AC_CHECK_FUNCS([X509_get_signature_info])=0A=
+=20=20AC_CHECK_FUNCS([X509_get_signature_info=20=
SSL_CTX_set_num_tickets])=0A=20=20=20AC_DEFINE([USE_OPENSSL],=201,=20=
[Define=20to=201=20to=20build=20with=20OpenSSL=20support.=20=
(--with-ssl=3Dopenssl)])=0A=20elif=20test=20"$with_ssl"=20!=3D=20no=20;=20=
then=0A=20=20=20AC_MSG_ERROR([--with-ssl=20must=20specify=20openssl])=0A=
diff=20--git=20a/meson.build=20b/meson.build=0Aindex=20=
2767abd19e..e21f88b529=20100644=0A---=20a/meson.build=0A+++=20=
b/meson.build=0A@@=20-1293,6=20+1293,7=20@@=20if=20sslopt=20in=20=
['auto',=20'openssl']=0A=20=0A=20=20=20=20=20=20=20#=20Function=20=
introduced=20in=20OpenSSL=201.1.1=0A=20=20=20=20=20=20=20=
['X509_get_signature_info'],=0A+=20=20=20=20=20=20=
['SSL_CTX_set_num_tickets'],=0A=20=20=20=20=20]=0A=20=0A=20=20=20=20=20=
are_openssl_funcs_complete=20=3D=20true=0Adiff=20--git=20=
a/src/backend/libpq/be-secure-openssl.c=20=
b/src/backend/libpq/be-secure-openssl.c=0Aindex=2039b1a66236..d257b93104=20=
100644=0A---=20a/src/backend/libpq/be-secure-openssl.c=0A+++=20=
b/src/backend/libpq/be-secure-openssl.c=0A@@=20-258,8=20+258,20=20@@=20=
be_tls_init(bool=20isServerStart)=0A=20=09=09}=0A=20=09}=0A=20=0A-=09/*=20=
disallow=20SSL=20session=20tickets=20*/=0A+=09/*=0A+=09=20*=20Disallow=20=
SSL=20session=20tickets.=20OpenSSL=20use=20both=20stateful=20and=20=
stateless=0A+=09=20*=20tickets=20for=20TLSv1.3,=20and=20stateless=20=
ticket=20for=20TLSv1.2.=20SSL_OP_NO_TICKET=0A+=09=20*=20is=20available=20=
since=201.0.0=20but=20only=20turns=20off=20stateless=20tickets.=20In=20=
order=0A+=09=20*=20to=20turn=20off=20stateful=20tickets=20we=20also=20=
need=20SSL_CTX_set_num_tickets,=20which=0A+=09=20*=20is=20available=20=
since=20OpenSSL=201.1.1.=20LibreSSL=203.5.4=20(from=20OpenBSD=207.1)=0A+=09=
=20*=20introduced=20this=20API=20for=20compatibility,=20but=20doesn't=20=
support=20session=0A+=09=20*=20tickets=20at=20all=20so=20it's=20a=20=
no-op=20there.=0A+=09=20*/=0A+#ifdef=20HAVE_SSL_CTX_SET_NUM_TICKETS=0A+=09=
SSL_CTX_set_num_tickets(context,=200);=0A+#else=0A=20=09=
SSL_CTX_set_options(context,=20SSL_OP_NO_TICKET);=0A+#endif=0A=20=0A=20=09=
/*=20disallow=20SSL=20session=20caching,=20too=20*/=0A=20=09=
SSL_CTX_set_session_cache_mode(context,=20SSL_SESS_CACHE_OFF);=0Adiff=20=
--git=20a/src/include/pg_config.h.in=20b/src/include/pg_config.h.in=0A=
index=20f8d3e3b6b8..e2834912f8=20100644=0A---=20=
a/src/include/pg_config.h.in=0A+++=20b/src/include/pg_config.h.in=0A@@=20=
-510,6=20+510,9=20@@=0A=20/*=20Define=20to=201=20if=20you=20have=20the=20=
`X509_get_signature_info'=20function.=20*/=0A=20#undef=20=
HAVE_X509_GET_SIGNATURE_INFO=0A=20=0A+/*=20Define=20to=201=20if=20you=20=
have=20the=20`SSL_CTX_set_num_tickets'=20function.=20*/=0A+#undef=20=
HAVE_SSL_CTX_SET_NUM_TICKETS=0A+=0A=20/*=20Define=20to=201=20if=20the=20=
assembler=20supports=20X86_64's=20POPCNTQ=20instruction.=20*/=0A=20=
#undef=20HAVE_X86_64_POPCNTQ=0A=20=0A--=20=0A2.39.3=20(Apple=20Git-146)=0A=
=0A=

--Apple-Mail=_8668B109-EB2A-4530-B834-3F4EE98353A0--