[openwrt/openwrt] firewall: backport patch for mss clamping in both directions

[LEDE Commits]

yousong pushed a commit to openwrt/openwrt.git, branch openwrt-18.06:
https://git.openwrt.org/7bd437cc9f4943e7769b9494b73e86a14373c916

commit 7bd437cc9f4943e7769b9494b73e86a14373c916
Author: Yousong Zhou <yszhou4tech at gmail.com>
AuthorDate: Sun Jul 26 22:34:49 2020 +0800

    firewall: backport patch for mss clamping in both directions
    
    Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
---
 package/network/config/firewall/Makefile           |  2 +-
 ...ply-tcp-mss-clamping-also-on-ingress-path.patch | 33 ++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/package/network/config/firewall/Makefile b/package/network/config/firewall/Makefile
index 830a1b268f..7a91924d01 100644
--- a/package/network/config/firewall/Makefile
+++ b/package/network/config/firewall/Makefile
@@ -9,7 +9,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=firewall
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL=$(PROJECT_GIT)/project/firewall3.git
diff --git a/package/network/config/firewall/patches/0001-zones-apply-tcp-mss-clamping-also-on-ingress-path.patch b/package/network/config/firewall/patches/0001-zones-apply-tcp-mss-clamping-also-on-ingress-path.patch
new file mode 100644
index 0000000000..816bca35d0
--- /dev/null
+++ b/package/network/config/firewall/patches/0001-zones-apply-tcp-mss-clamping-also-on-ingress-path.patch
@@ -0,0 +1,33 @@
+From c9f48cb3bd0e14fec8ad71c3baef7c280a390b4f Mon Sep 17 00:00:00 2001
+From: Yousong Zhou <yszhou4tech at gmail.com>
+Date: Fri, 24 Jul 2020 12:52:59 +0800
+Subject: [PATCH] zones: apply tcp mss clamping also on ingress path
+
+Fixes FS#3231
+
+Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
+Acked-by: Jo-Philipp Wich <jo at mein.io>
+(cherry picked from commit e9b90dfac2225927c035f6a76277b850c282dc9a)
+---
+ zones.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+diff --git a/zones.c b/zones.c
+index 505ab20..4656f88 100644
+--- a/zones.c
++++ b/zones.c
+@@ -553,6 +553,14 @@ print_interface_rule(struct fw3_ipt_handle *handle, struct fw3_state *state,
+ 			fw3_ipt_rule_target(r, "TCPMSS");
+ 			fw3_ipt_rule_addarg(r, false, "--clamp-mss-to-pmtu", NULL);
+ 			fw3_ipt_rule_replace(r, "FORWARD");
++
++			r = fw3_ipt_rule_create(handle, &tcp, dev, NULL, sub, NULL);
++			fw3_ipt_rule_addarg(r, false, "--tcp-flags", "SYN,RST");
++			fw3_ipt_rule_addarg(r, false, "SYN", NULL);
++			fw3_ipt_rule_comment(r, "Zone %s MTU fixing", zone->name);
++			fw3_ipt_rule_target(r, "TCPMSS");
++			fw3_ipt_rule_addarg(r, false, "--clamp-mss-to-pmtu", NULL);
++			fw3_ipt_rule_replace(r, "FORWARD");
+ 		}
+ 	}
+ 	else if (handle->table == FW3_TABLE_RAW)