[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

6 files changed, 38 insertions, 18 deletions

diff --git a/pkg/tcpip/socketops.go b/pkg/tcpip/socketops.go
index 2a6c7c7c0..e1b0d6354 100644
--- a/pkg/tcpip/socketops.go
+++ b/pkg/tcpip/socketops.go
@@ -15,31 +15,49 @@
 package tcpip
 
 import (
-	"gvisor.dev/gvisor/pkg/sync"
+	"sync/atomic"
 )
 
-// SocketOptions contains all the variables which store values for socket
+// SocketOptions contains all the variables which store values for SOL_SOCKET
 // level options.
 //
 // +stateify savable
 type SocketOptions struct {
-	// mu protects fields below.
-	mu               sync.Mutex `state:"nosave"`
-	broadcastEnabled bool
+	// These fields are accessed and modified using atomic operations.
+
+	// broadcastEnabled determines whether datagram sockets are allowed to send
+	// packets to a broadcast address.
+	broadcastEnabled uint32
+
+	// passCredEnabled determines whether SCM_CREDENTIALS socket control messages
+	// are enabled.
+	passCredEnabled uint32
+}
+
+func storeAtomicBool(addr *uint32, v bool) {
+	var val uint32
+	if v {
+		val = 1
+	}
+	atomic.StoreUint32(addr, val)
 }
 
 // GetBroadcast gets value for SO_BROADCAST option.
 func (so *SocketOptions) GetBroadcast() bool {
-	so.mu.Lock()
-	defer so.mu.Unlock()
-
-	return so.broadcastEnabled
+	return atomic.LoadUint32(&so.broadcastEnabled) != 0
 }
 
 // SetBroadcast sets value for SO_BROADCAST option.
 func (so *SocketOptions) SetBroadcast(v bool) {
-	so.mu.Lock()
-	defer so.mu.Unlock()
+	storeAtomicBool(&so.broadcastEnabled, v)
+}
+
+// GetPassCred gets value for SO_PASSCRED option.
+func (so *SocketOptions) GetPassCred() bool {
+	return atomic.LoadUint32(&so.passCredEnabled) != 0
+}
 
-	so.broadcastEnabled = v
+// SetPassCred sets value for SO_PASSCRED option.
+func (so *SocketOptions) SetPassCred(v bool) {
+	storeAtomicBool(&so.passCredEnabled, v)
 }
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index f9e83dd1c..09361360f 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -721,12 +721,6 @@ const (
 	// whether UDP checksum is disabled for this socket.
 	NoChecksumOption
 
-	// PasscredOption is used by SetSockOptBool/GetSockOptBool to specify
-	// whether SCM_CREDENTIALS socket control messages are enabled.
-	//
-	// Only supported on Unix sockets.
-	PasscredOption
-
 	// QuickAckOption is stubbed out in SetSockOptBool/GetSockOptBool.
 	QuickAckOption
 
diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index 440cb0352..fe6514bcd 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -857,6 +857,7 @@ func (*endpoint) LastError() *tcpip.Error {
 	return nil
 }
 
+// SocketOptions implements tcpip.Endpoint.SocketOptions.
 func (e *endpoint) SocketOptions() *tcpip.SocketOptions {
 	return &e.ops
 }
diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go
index 4ae1f92ab..0a1e1fbb3 100644
--- a/pkg/tcpip/transport/raw/endpoint.go
+++ b/pkg/tcpip/transport/raw/endpoint.go
@@ -756,10 +756,12 @@ func (e *endpoint) Stats() tcpip.EndpointStats {
 // Wait implements stack.TransportEndpoint.Wait.
 func (*endpoint) Wait() {}
 
+// LastError implements tcpip.Endpoint.LastError.
 func (*endpoint) LastError() *tcpip.Error {
 	return nil
 }
 
+// SocketOptions implements tcpip.Endpoint.SocketOptions.
 func (e *endpoint) SocketOptions() *tcpip.SocketOptions {
 	return &e.ops
 }
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 173cd28ec..36b915510 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -1279,6 +1279,7 @@ func (e *endpoint) ModerateRecvBuf(copied int) {
 	e.rcvListMu.Unlock()
 }
 
+// SetOwner implements tcpip.Endpoint.SetOwner.
 func (e *endpoint) SetOwner(owner tcpip.PacketOwner) {
 	e.owner = owner
 }
@@ -1299,6 +1300,7 @@ func (e *endpoint) lastErrorLocked() *tcpip.Error {
 	return err
 }
 
+// LastError implements tcpip.Endpoint.LastError.
 func (e *endpoint) LastError() *tcpip.Error {
 	e.LockUser()
 	defer e.UnlockUser()
@@ -3213,6 +3215,7 @@ func (e *endpoint) Wait() {
 	}
 }
 
+// SocketOptions implements tcpip.Endpoint.SocketOptions.
 func (e *endpoint) SocketOptions() *tcpip.SocketOptions {
 	return &e.ops
 }
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 835dcc54e..81601f559 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -1535,10 +1535,12 @@ func isBroadcastOrMulticast(a tcpip.Address) bool {
 	return a == header.IPv4Broadcast || header.IsV4MulticastAddress(a) || header.IsV6MulticastAddress(a)
 }
 
+// SetOwner implements tcpip.Endpoint.SetOwner.
 func (e *endpoint) SetOwner(owner tcpip.PacketOwner) {
 	e.owner = owner
 }
 
+// SocketOptions implements tcpip.Endpoint.SocketOptions.
 func (e *endpoint) SocketOptions() *tcpip.SocketOptions {
 	return &e.ops
 }