Store more information in the kernel socket table.

Store enough information in the kernel socket table to distinguish
between different types of sockets. Previously we were only storing
the socket family, but this isn't enough to classify sockets. For
example, TCPv4 and UDPv4 sockets are both AF_INET, and ICMP sockets
are SOCK_DGRAM sockets with a particular protocol.

Instead of creating more sub-tables, flatten the socket table and
provide a filtering mechanism based on the socket entry.

Also generate and store a socket entry index ("sl" in linux) which
allows us to output entries in a stable order from procfs.

PiperOrigin-RevId: 252495895

2 files changed, 12 insertions, 2 deletions

diff --git a/pkg/sentry/socket/netlink/provider.go b/pkg/sentry/socket/netlink/provider.go
index 863edc241..5dc103877 100644
--- a/pkg/sentry/socket/netlink/provider.go
+++ b/pkg/sentry/socket/netlink/provider.go
@@ -82,7 +82,7 @@ func (*socketProvider) Socket(t *kernel.Task, stype linux.SockType, protocol int
 		return nil, err
 	}
 
-	s, err := NewSocket(t, p)
+	s, err := NewSocket(t, stype, p)
 	if err != nil {
 		return nil, err
 	}
diff --git a/pkg/sentry/socket/netlink/socket.go b/pkg/sentry/socket/netlink/socket.go
index 16c79aa33..62659784a 100644
--- a/pkg/sentry/socket/netlink/socket.go
+++ b/pkg/sentry/socket/netlink/socket.go
@@ -80,6 +80,10 @@ type Socket struct {
 	// protocol is the netlink protocol implementation.
 	protocol Protocol
 
+	// skType is the socket type. This is either SOCK_DGRAM or SOCK_RAW for
+	// netlink sockets.
+	skType linux.SockType
+
 	// ep is a datagram unix endpoint used to buffer messages sent from the
 	// kernel to userspace. RecvMsg reads messages from this endpoint.
 	ep transport.Endpoint
@@ -105,7 +109,7 @@ type Socket struct {
 var _ socket.Socket = (*Socket)(nil)
 
 // NewSocket creates a new Socket.
-func NewSocket(t *kernel.Task, protocol Protocol) (*Socket, *syserr.Error) {
+func NewSocket(t *kernel.Task, skType linux.SockType, protocol Protocol) (*Socket, *syserr.Error) {
 	// Datagram endpoint used to buffer kernel -> user messages.
 	ep := transport.NewConnectionless()
 
@@ -126,6 +130,7 @@ func NewSocket(t *kernel.Task, protocol Protocol) (*Socket, *syserr.Error) {
 	return &Socket{
 		ports:          t.Kernel().NetlinkPorts(),
 		protocol:       protocol,
+		skType:         skType,
 		ep:             ep,
 		connection:     connection,
 		sendBufferSize: defaultSendBufferSize,
@@ -621,3 +626,8 @@ func (s *Socket) Write(ctx context.Context, _ *fs.File, src usermem.IOSequence,
 func (s *Socket) State() uint32 {
 	return s.ep.State()
 }
+
+// Type implements socket.Socket.Type.
+func (s *Socket) Type() (family int, skType linux.SockType, protocol int) {
+	return linux.AF_NETLINK, s.skType, s.protocol.Protocol()
+}