From af4afdc0e0482fd6f4d6d8da77df30527b75e421 Mon Sep 17 00:00:00 2001
From: Ayush Ranjan <ayushranjan@google.com>
Date: Fri, 11 Dec 2020 10:32:03 -0800
Subject: [netstack] Decouple tcpip.ControlMessages from the IP control
 messges.

tcpip.ControlMessages can not contain Linux specific structures which makes it
painful to convert back and forth from Linux to tcpip back to Linux when passing
around control messages in hostinet and raw sockets.

Now we convert to the Linux version of the control message as soon as we are
out of tcpip.

PiperOrigin-RevId: 347027065
---
 pkg/sentry/socket/control/control.go | 53 +++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 28 deletions(-)

(limited to 'pkg/sentry/socket/control/control.go')

diff --git a/pkg/sentry/socket/control/control.go b/pkg/sentry/socket/control/control.go
index c284efde5..5b81e8379 100644
--- a/pkg/sentry/socket/control/control.go
+++ b/pkg/sentry/socket/control/control.go
@@ -26,7 +26,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/socket"
 	"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
 	"gvisor.dev/gvisor/pkg/syserror"
-	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
@@ -344,32 +343,32 @@ func PackTClass(t *kernel.Task, tClass uint32, buf []byte) []byte {
 }
 
 // PackIPPacketInfo packs an IP_PKTINFO socket control message.
-func PackIPPacketInfo(t *kernel.Task, packetInfo tcpip.IPPacketInfo, buf []byte) []byte {
-	var p linux.ControlMessageIPPacketInfo
-	p.NIC = int32(packetInfo.NIC)
-	copy(p.LocalAddr[:], []byte(packetInfo.LocalAddr))
-	copy(p.DestinationAddr[:], []byte(packetInfo.DestinationAddr))
-
+func PackIPPacketInfo(t *kernel.Task, packetInfo *linux.ControlMessageIPPacketInfo, buf []byte) []byte {
 	return putCmsgStruct(
 		buf,
 		linux.SOL_IP,
 		linux.IP_PKTINFO,
 		t.Arch().Width(),
-		p,
+		packetInfo,
 	)
 }
 
 // PackOriginalDstAddress packs an IP_RECVORIGINALDSTADDR socket control message.
-func PackOriginalDstAddress(t *kernel.Task, family int, originalDstAddress tcpip.FullAddress, buf []byte) []byte {
-	p, _ := socket.ConvertAddress(family, originalDstAddress)
-	level := uint32(linux.SOL_IP)
-	optType := uint32(linux.IP_RECVORIGDSTADDR)
-	if family == linux.AF_INET6 {
+func PackOriginalDstAddress(t *kernel.Task, originalDstAddress linux.SockAddr, buf []byte) []byte {
+	var level uint32
+	var optType uint32
+	switch originalDstAddress.(type) {
+	case *linux.SockAddrInet:
+		level = linux.SOL_IP
+		optType = linux.IP_RECVORIGDSTADDR
+	case *linux.SockAddrInet6:
 		level = linux.SOL_IPV6
 		optType = linux.IPV6_RECVORIGDSTADDR
+	default:
+		panic("invalid address type, must be an IP address for IP_RECVORIGINALDSTADDR cmsg")
 	}
 	return putCmsgStruct(
-		buf, level, optType, t.Arch().Width(), p)
+		buf, level, optType, t.Arch().Width(), originalDstAddress)
 }
 
 // PackControlMessages packs control messages into the given buffer.
@@ -378,7 +377,7 @@ func PackOriginalDstAddress(t *kernel.Task, family int, originalDstAddress tcpip
 //
 // Note that some control messages may be truncated if they do not fit under
 // the capacity of buf.
-func PackControlMessages(t *kernel.Task, family int, cmsgs socket.ControlMessages, buf []byte) []byte {
+func PackControlMessages(t *kernel.Task, cmsgs socket.ControlMessages, buf []byte) []byte {
 	if cmsgs.IP.HasTimestamp {
 		buf = PackTimestamp(t, cmsgs.IP.Timestamp, buf)
 	}
@@ -397,11 +396,11 @@ func PackControlMessages(t *kernel.Task, family int, cmsgs socket.ControlMessage
 	}
 
 	if cmsgs.IP.HasIPPacketInfo {
-		buf = PackIPPacketInfo(t, cmsgs.IP.PacketInfo, buf)
+		buf = PackIPPacketInfo(t, &cmsgs.IP.PacketInfo, buf)
 	}
 
-	if cmsgs.IP.HasOriginalDstAddress {
-		buf = PackOriginalDstAddress(t, family, cmsgs.IP.OriginalDstAddress, buf)
+	if cmsgs.IP.OriginalDstAddress != nil {
+		buf = PackOriginalDstAddress(t, cmsgs.IP.OriginalDstAddress, buf)
 	}
 
 	return buf
@@ -433,17 +432,15 @@ func CmsgsSpace(t *kernel.Task, cmsgs socket.ControlMessages) int {
 		space += cmsgSpace(t, linux.SizeOfControlMessageTClass)
 	}
 
-	return space
-}
+	if cmsgs.IP.HasIPPacketInfo {
+		space += cmsgSpace(t, linux.SizeOfControlMessageIPPacketInfo)
+	}
 
-// NewIPPacketInfo returns the IPPacketInfo struct.
-func NewIPPacketInfo(packetInfo linux.ControlMessageIPPacketInfo) tcpip.IPPacketInfo {
-	var p tcpip.IPPacketInfo
-	p.NIC = tcpip.NICID(packetInfo.NIC)
-	copy([]byte(p.LocalAddr), packetInfo.LocalAddr[:])
-	copy([]byte(p.DestinationAddr), packetInfo.DestinationAddr[:])
+	if cmsgs.IP.OriginalDstAddress != nil {
+		space += cmsgSpace(t, cmsgs.IP.OriginalDstAddress.SizeBytes())
+	}
 
-	return p
+	return space
 }
 
 // Parse parses a raw socket control message into portable objects.
@@ -529,7 +526,7 @@ func Parse(t *kernel.Task, socketOrEndpoint interface{}, buf []byte) (socket.Con
 				var packetInfo linux.ControlMessageIPPacketInfo
 				binary.Unmarshal(buf[i:i+linux.SizeOfControlMessageIPPacketInfo], usermem.ByteOrder, &packetInfo)
 
-				cmsgs.IP.PacketInfo = NewIPPacketInfo(packetInfo)
+				cmsgs.IP.PacketInfo = packetInfo
 				i += binary.AlignUp(length, width)
 
 			default:
-- 
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