[netstack] Move SO_PASSCRED option to SocketOptions.

This change also makes the following fixes:
- Make SocketOptions use atomic operations instead of having to acquire/drop
  locks upon each get/set option.
- Make documentation more consistent.
- Remove tcpip.SocketOptions from socketOpsCommon because it already exists
  in transport.Endpoint.
- Refactors get/set socket options tests to be easily extendable.

PiperOrigin-RevId: 343103780

4 files changed, 14 insertions, 45 deletions

diff --git a/pkg/sentry/socket/netlink/socket.go b/pkg/sentry/socket/netlink/socket.go
index 3baad098b..057f4d294 100644
--- a/pkg/sentry/socket/netlink/socket.go
+++ b/pkg/sentry/socket/netlink/socket.go
@@ -120,9 +120,6 @@ type socketOpsCommon struct {
 	// fixed buffer but only consume this many bytes.
 	sendBufferSize uint32
 
-	// passcred indicates if this socket wants SCM credentials.
-	passcred bool
-
 	// filter indicates that this socket has a BPF filter "installed".
 	//
 	// TODO(gvisor.dev/issue/1119): We don't actually support filtering,
@@ -201,10 +198,7 @@ func (s *socketOpsCommon) EventUnregister(e *waiter.Entry) {
 
 // Passcred implements transport.Credentialer.Passcred.
 func (s *socketOpsCommon) Passcred() bool {
-	s.mu.Lock()
-	passcred := s.passcred
-	s.mu.Unlock()
-	return passcred
+	return s.ep.SocketOptions().GetPassCred()
 }
 
 // ConnectedPasscred implements transport.Credentialer.ConnectedPasscred.
@@ -419,9 +413,7 @@ func (s *socketOpsCommon) SetSockOpt(t *kernel.Task, level int, name int, opt []
 			}
 			passcred := usermem.ByteOrder.Uint32(opt)
 
-			s.mu.Lock()
-			s.passcred = passcred != 0
-			s.mu.Unlock()
+			s.ep.SocketOptions().SetPassCred(passcred != 0)
 			return nil
 
 		case linux.SO_ATTACH_FILTER:
diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index 5afe77858..9c927efa0 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -260,10 +260,12 @@ type commonEndpoint interface {
 	// transport.Endpoint.GetSockOpt.
 	GetSockOptInt(opt tcpip.SockOptInt) (int, *tcpip.Error)
 
-	// LastError implements tcpip.Endpoint.LastError.
+	// LastError implements tcpip.Endpoint.LastError and
+	// transport.Endpoint.LastError.
 	LastError() *tcpip.Error
 
-	// SocketOptions implements tcpip.Endpoint.SocketOptions.
+	// SocketOptions implements tcpip.Endpoint.SocketOptions and
+	// transport.Endpoint.SocketOptions.
 	SocketOptions() *tcpip.SocketOptions
 }
 
@@ -1068,13 +1070,8 @@ func getSockOptSocket(t *kernel.Task, s socket.SocketOps, ep commonEndpoint, fam
 			return nil, syserr.ErrInvalidArgument
 		}
 
-		v, err := ep.GetSockOptBool(tcpip.PasscredOption)
-		if err != nil {
-			return nil, syserr.TranslateNetstackError(err)
-		}
-
-		vP := primitive.Int32(boolToInt32(v))
-		return &vP, nil
+		v := primitive.Int32(boolToInt32(ep.SocketOptions().GetPassCred()))
+		return &v, nil
 
 	case linux.SO_SNDBUF:
 		if outLen < sizeOfInt32 {
@@ -1923,7 +1920,8 @@ func setSockOptSocket(t *kernel.Task, s socket.SocketOps, ep commonEndpoint, nam
 		}
 
 		v := usermem.ByteOrder.Uint32(optVal)
-		return syserr.TranslateNetstackError(ep.SetSockOptBool(tcpip.PasscredOption, v != 0))
+		ep.SocketOptions().SetPassCred(v != 0)
+		return nil
 
 	case linux.SO_KEEPALIVE:
 		if len(optVal) < sizeOfInt32 {
diff --git a/pkg/sentry/socket/unix/transport/unix.go b/pkg/sentry/socket/unix/transport/unix.go
index 18a50e9f8..0324dcd93 100644
--- a/pkg/sentry/socket/unix/transport/unix.go
+++ b/pkg/sentry/socket/unix/transport/unix.go
@@ -16,8 +16,6 @@
 package transport
 
 import (
-	"sync/atomic"
-
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/log"
@@ -203,10 +201,11 @@ type Endpoint interface {
 	// procfs.
 	State() uint32
 
-	// LastError implements tcpip.Endpoint.LastError.
+	// LastError clears and returns the last error reported by the endpoint.
 	LastError() *tcpip.Error
 
-	// SocketOptions implements tcpip.Endpoint.SocketOptions.
+	// SocketOptions returns the structure which contains all the socket
+	// level options.
 	SocketOptions() *tcpip.SocketOptions
 }
 
@@ -740,10 +739,6 @@ func (e *connectedEndpoint) CloseUnread() {
 type baseEndpoint struct {
 	*waiter.Queue
 
-	// passcred specifies whether SCM_CREDENTIALS socket control messages are
-	// enabled on this endpoint. Must be accessed atomically.
-	passcred int32
-
 	// Mutex protects the below fields.
 	sync.Mutex `state:"nosave"`
 
@@ -786,7 +781,7 @@ func (e *baseEndpoint) EventUnregister(we *waiter.Entry) {
 
 // Passcred implements Credentialer.Passcred.
 func (e *baseEndpoint) Passcred() bool {
-	return atomic.LoadInt32(&e.passcred) != 0
+	return e.SocketOptions().GetPassCred()
 }
 
 // ConnectedPasscred implements Credentialer.ConnectedPasscred.
@@ -796,14 +791,6 @@ func (e *baseEndpoint) ConnectedPasscred() bool {
 	return e.connected != nil && e.connected.Passcred()
 }
 
-func (e *baseEndpoint) setPasscred(pc bool) {
-	if pc {
-		atomic.StoreInt32(&e.passcred, 1)
-	} else {
-		atomic.StoreInt32(&e.passcred, 0)
-	}
-}
-
 // Connected implements ConnectingEndpoint.Connected.
 func (e *baseEndpoint) Connected() bool {
 	return e.receiver != nil && e.connected != nil
@@ -870,8 +857,6 @@ func (e *baseEndpoint) SetSockOpt(opt tcpip.SettableSocketOption) *tcpip.Error {
 
 func (e *baseEndpoint) SetSockOptBool(opt tcpip.SockOptBool, v bool) *tcpip.Error {
 	switch opt {
-	case tcpip.PasscredOption:
-		e.setPasscred(v)
 	case tcpip.ReuseAddressOption:
 	default:
 		log.Warningf("Unsupported socket option: %d", opt)
@@ -894,9 +879,6 @@ func (e *baseEndpoint) GetSockOptBool(opt tcpip.SockOptBool) (bool, *tcpip.Error
 	case tcpip.KeepaliveEnabledOption, tcpip.AcceptConnOption:
 		return false, nil
 
-	case tcpip.PasscredOption:
-		return e.Passcred(), nil
-
 	default:
 		log.Warningf("Unsupported socket option: %d", opt)
 		return false, tcpip.ErrUnknownProtocolOption
diff --git a/pkg/sentry/socket/unix/unix.go b/pkg/sentry/socket/unix/unix.go
index 3e520d2ee..b32bb7ba8 100644
--- a/pkg/sentry/socket/unix/unix.go
+++ b/pkg/sentry/socket/unix/unix.go
@@ -115,9 +115,6 @@ type socketOpsCommon struct {
 	// bound, they cannot be modified.
 	abstractName      string
 	abstractNamespace *kernel.AbstractSocketNamespace
-
-	// ops is used to get socket level options.
-	ops tcpip.SocketOptions
 }
 
 func (s *socketOpsCommon) isPacket() bool {