From 34921cd9c0f6d40377fcee27e41aa76cac5da950 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
 <marmarek@invisiblethingslab.com>
Date: Sun, 6 Oct 2019 05:32:41 +0200
Subject: [PATCH] network: don't fail the whole vif setup if IPv6 is disabled

Detect if IPv6 is disabled in the kernel (like it is in Whonix Gateway)
and skip setting IPv6 in that case. Otherwise 'ip' call would fail and
since the script is with 'set -e', it would interrupt setting IPv4 too.
Log error message in that case anyway.

Fixes QubesOS/qubes-issues#5110
---
 network/vif-route-qubes | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/network/vif-route-qubes b/network/vif-route-qubes
index 81313c4..724d22a 100755
--- a/network/vif-route-qubes
+++ b/network/vif-route-qubes
@@ -100,12 +100,15 @@ case "$command" in
         ipcmd='add'
         iptables_cmd='-I PREROUTING 1'
         cmdprefix=''
+        ipv6_disabled=$(cat /proc/sys/net/ipv6/conf/"${vif}"/disable_ipv6 || echo 1)
         ;;
     offline)
         do_without_error ifdown "${vif}"
         ipcmd='del'
         iptables_cmd='-D PREROUTING'
         cmdprefix='do_without_error'
+        # cleanup IPv6 config even if _now_ it is disabled
+        ipv6_disabled=0
         ;;
 esac
 
@@ -115,11 +118,16 @@ domid=${domid/.*/}
 #  32752 is max XID aka domid
 metric=$(( 32752 - domid ))
 
+
 if [ "${ip}" ]; then
     # If we've been given a list of IP addresses, then add routes from dom0 to
     # the guest using those addresses.
     for addr in ${ip};
     do
+        if [[ "$addr" = *:* ]] && [[ "$ipv6_disabled" = 1 ]]; then
+            log error "Cannot set IPv6 route to ${addr}, IPv6 disabled in the kernel"
+            continue
+        fi
         ${cmdprefix} ip route "${ipcmd}" "${addr}" dev "${vif}" metric "$metric"
         if [[ "$addr" = *:* ]]; then
             ipt=ip6tables-restore
@@ -137,7 +145,7 @@ if [ "${ip}" ]; then
             ${cmdprefix} ip6tables-restore --noflush $ipt_arg
     fi
     ${cmdprefix} ip addr "${ipcmd}" "${back_ip}/32" dev "${vif}"
-    if [ "${back_ip6}" ] && [[ "${back_ip6}" != "fe80:"* ]]; then
+    if [ "${back_ip6}" ] && [[ "${back_ip6}" != "fe80:"* ]] && [[ "$ipv6_disabled" != 1 ]]; then
         ${cmdprefix} ip addr "${ipcmd}" "${back_ip6}/128" dev "${vif}"
     fi
 else