strongswan: add upstream security patches

Fixes:

CVE-2017-9022 - RSA public keys passed to the gmp plugin aren't
validated sufficiently before attempting signature verification, so that
invalid input might lead to a floating point exception and crash of the
process.  A certificate with an appropriately prepared public key sent by a
peer could be used for a denial-of-service attack.

https://www.strongswan.org/blog/2017/05/30/strongswan-vulnerability-%28cve-2017-9022%29.html

CVE-2017-9023 - ASN.1 CHOICE types are not correctly handled by the ASN.1
parser when parsing X.509 certificates with extensions that use such types.
This could lead to infinite looping of the thread parsing a specifically
crafted certificate.

https://www.strongswan.org/blog/2017/05/30/strongswan-vulnerability-%28cve-2017-9023%29.html

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/strongswan/strongswan.hash

@@ -2,3 +2,6 @@
 md5	9d7c77b0da9b69f859624897e5e9ebbf	strongswan-5.4.0.tar.bz2
 # Calculated based on the hash above
 sha256	f8288faaea6a9cd8a7d413c0b76b7922be5da3dfcd01fd05cb30d2c55d3bbe89	strongswan-5.4.0.tar.bz2
+# Locally calculated
+sha256	f5ba7f46cf7ae81dd81bc86f9e4cfa0c5c7c6987149b3bc9c0b8bf08598a1063  strongswan-4.4.0-5.5.2_gmp_mpz_powm_sec.patch
+sha256	03db8c7a4133e877e8992e155c046dd27ec4810d50f239abf55595f0280caf31  strongswan-5.0.0-5.5.2_asn1_choice.patch

package/strongswan/strongswan.mk

@@ -7,6 +7,9 @@
 STRONGSWAN_VERSION = 5.4.0
 STRONGSWAN_SOURCE = strongswan-$(STRONGSWAN_VERSION).tar.bz2
 STRONGSWAN_SITE = http://download.strongswan.org
+STRONGSWAN_PATCH = \
+	$(STRONGSWAN_SITE)/patches/21_gmp_mpz_powm_sec_patch/strongswan-4.4.0-5.5.2_gmp_mpz_powm_sec.patch \
+	$(STRONGSWAN_SITE)/patches/22_asn1_choice_patch/strongswan-5.0.0-5.5.2_asn1_choice.patch
 STRONGSWAN_LICENSE = GPL-2.0+
 STRONGSWAN_LICENSE_FILES = COPYING LICENSE
 STRONGSWAN_DEPENDENCIES = host-pkgconf