Basic support for ip link/addr and ifconfig

Closes #94

PiperOrigin-RevId: 207997580
Change-Id: I19b426f1586b5ec12f8b0cd5884d5b401d334924

2 files changed, 71 insertions, 8 deletions

diff --git a/pkg/sentry/socket/netlink/route/protocol.go b/pkg/sentry/socket/netlink/route/protocol.go
index 55a76e916..70322b9ed 100644
--- a/pkg/sentry/socket/netlink/route/protocol.go
+++ b/pkg/sentry/socket/netlink/route/protocol.go
@@ -16,6 +16,8 @@
 package route
 
 import (
+	"bytes"
+
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/inet"
@@ -97,9 +99,18 @@ func (p *Protocol) dumpLinks(ctx context.Context, hdr linux.NetlinkMessageHeader
 		})
 
 		m.PutAttrString(linux.IFLA_IFNAME, i.Name)
+		m.PutAttr(linux.IFLA_MTU, i.MTU)
+
+		mac := make([]byte, 6)
+		brd := mac
+		if len(i.Addr) > 0 {
+			mac = i.Addr
+			brd = bytes.Repeat([]byte{0xff}, len(i.Addr))
+		}
+		m.PutAttr(linux.IFLA_ADDRESS, mac)
+		m.PutAttr(linux.IFLA_BROADCAST, brd)
 
-		// TODO: There are many more attributes, such as
-		// MAC address.
+		// TODO: There are many more attributes.
 	}
 
 	return nil
diff --git a/pkg/sentry/socket/netlink/socket.go b/pkg/sentry/socket/netlink/socket.go
index e15d1546c..f3b2c7256 100644
--- a/pkg/sentry/socket/netlink/socket.go
+++ b/pkg/sentry/socket/netlink/socket.go
@@ -16,6 +16,7 @@
 package netlink
 
 import (
+	"math"
 	"sync"
 
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
@@ -39,8 +40,18 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/waiter"
 )
 
-// defaultSendBufferSize is the default size for the send buffer.
-const defaultSendBufferSize = 16 * 1024
+const sizeOfInt32 int = 4
+
+const (
+	// minBufferSize is the smallest size of a send buffer.
+	minSendBufferSize = 4 << 10 // 4096 bytes.
+
+	// defaultSendBufferSize is the default size for the send buffer.
+	defaultSendBufferSize = 16 * 1024
+
+	// maxBufferSize is the largest size a send buffer can grow to.
+	maxSendBufferSize = 4 << 20 // 4MB
+)
 
 // netlinkSocketDevice is the netlink socket virtual device.
 var netlinkSocketDevice = device.NewAnonDevice()
@@ -86,7 +97,7 @@ type Socket struct {
 
 	// sendBufferSize is the send buffer "size". We don't actually have a
 	// fixed buffer but only consume this many bytes.
-	sendBufferSize uint64
+	sendBufferSize uint32
 }
 
 var _ socket.Socket = (*Socket)(nil)
@@ -273,13 +284,54 @@ func (s *Socket) Shutdown(t *kernel.Task, how int) *syserr.Error {
 
 // GetSockOpt implements socket.Socket.GetSockOpt.
 func (s *Socket) GetSockOpt(t *kernel.Task, level int, name int, outLen int) (interface{}, *syserr.Error) {
-	// TODO: no sockopts supported.
+	switch level {
+	case linux.SOL_SOCKET:
+		switch name {
+		case linux.SO_SNDBUF:
+			if outLen < sizeOfInt32 {
+				return nil, syserr.ErrInvalidArgument
+			}
+			return int32(s.sendBufferSize), nil
+
+		case linux.SO_RCVBUF:
+			if outLen < sizeOfInt32 {
+				return nil, syserr.ErrInvalidArgument
+			}
+			// We don't have limit on receiving size.
+			return math.MaxInt32, nil
+		}
+	}
+	// TODO: other sockopts are not supported.
 	return nil, syserr.ErrProtocolNotAvailable
 }
 
 // SetSockOpt implements socket.Socket.SetSockOpt.
 func (s *Socket) SetSockOpt(t *kernel.Task, level int, name int, opt []byte) *syserr.Error {
-	// TODO: no sockopts supported.
+	switch level {
+	case linux.SOL_SOCKET:
+		switch name {
+		case linux.SO_SNDBUF:
+			if len(opt) < sizeOfInt32 {
+				return syserr.ErrInvalidArgument
+			}
+			size := usermem.ByteOrder.Uint32(opt)
+			if size < minSendBufferSize {
+				size = minSendBufferSize
+			} else if size > maxSendBufferSize {
+				size = maxSendBufferSize
+			}
+			s.sendBufferSize = size
+			return nil
+		case linux.SO_RCVBUF:
+			if len(opt) < sizeOfInt32 {
+				return syserr.ErrInvalidArgument
+			}
+			// We don't have limit on receiving size. So just accept anything as
+			// valid for compatibility.
+			return nil
+		}
+	}
+	// TODO: other sockopts are not supported.
 	return syserr.ErrProtocolNotAvailable
 }
 
@@ -489,7 +541,7 @@ func (s *Socket) sendMsg(ctx context.Context, src usermem.IOSequence, to []byte,
 
 	// For simplicity, and consistency with Linux, we copy in the entire
 	// message up front.
-	if uint64(src.NumBytes()) > s.sendBufferSize {
+	if src.NumBytes() > int64(s.sendBufferSize) {
 		return 0, syserr.ErrMessageTooLong
 	}