From 89d11b4d96b0c40e373f14ba72d570c9b894f976 Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Thu, 9 Jan 2020 13:41:52 -0800
Subject: Added a test that we don't pass yet

---
 pkg/sentry/socket/netfilter/netfilter.go | 37 +++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

(limited to 'pkg/sentry')

diff --git a/pkg/sentry/socket/netfilter/netfilter.go b/pkg/sentry/socket/netfilter/netfilter.go
index 014dfa625..f30461936 100644
--- a/pkg/sentry/socket/netfilter/netfilter.go
+++ b/pkg/sentry/socket/netfilter/netfilter.go
@@ -323,10 +323,9 @@ func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error {
 
 		// TODO(gvisor.dev/issue/170): We should support IPTIP
 		// filtering. We reject any nonzero IPTIP values for now.
-		emptyIPTIP := linux.IPTIP{}
-		if entry.IP != emptyIPTIP {
-			log.Warningf("netfilter: non-empty struct iptip found")
-			return syserr.ErrInvalidArgument
+		filter, err := filterFromIPTIP(entry.IP)
+		if err != nil {
+			return err
 		}
 
 		// Get the target of the rule.
@@ -336,7 +335,10 @@ func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error {
 		}
 		optVal = optVal[consumed:]
 
-		table.Rules = append(table.Rules, iptables.Rule{Target: target})
+		table.Rules = append(table.Rules, iptables.Rule{
+			Filter: filter,
+			Target: target,
+		})
 		offsets = append(offsets, offset)
 		offset += linux.SizeOfIPTEntry + consumed
 	}
@@ -447,6 +449,31 @@ func parseTarget(optVal []byte) (iptables.Target, uint32, *syserr.Error) {
 	return nil, 0, syserr.ErrInvalidArgument
 }
 
+func filterFromIPTIP(iptip linux.IPTIP) (iptables.IPHeaderFilter, *syserr.Error) {
+	if containsUnsupportedFields(iptip) {
+		log.Warningf("netfilter: unsupported fields in struct iptip: %+v")
+		return iptables.IPHeaderFilter{}, syserr.ErrInvalidArgument
+	}
+	return iptables.IPHeaderFilter{
+		Protocol: iptip.Protocol,
+	}, nil
+}
+
+func containsUnsupportedFields(iptip linux.IPTIP) bool {
+	// Currently we check that everything except protocol is zeroed.
+	var emptyInetAddr = linux.InetAddr{}
+	var emptyInterface = [linux.IFNAMSIZ]byte{}
+	return iptip.Dst != emptyInetAddr ||
+		iptip.SrcMask != emptyInetAddr ||
+		iptip.DstMask != emptyInetAddr ||
+		iptip.InputInterface != emptyInterface ||
+		iptip.OutputInterface != emptyInterface ||
+		iptip.InputInterfaceMask != emptyInterface ||
+		iptip.OutputInterfaceMask != emptyInterface ||
+		iptip.Flags != 0 ||
+		iptip.InverseFlags != 0
+}
+
 func hookFromLinux(hook int) iptables.Hook {
 	switch hook {
 	case linux.NF_INET_PRE_ROUTING:
-- 
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