Merge fbbb2f7e (automated)

6 files changed, 100 insertions, 59 deletions

diff --git a/pkg/sentry/platform/ring0/defs_impl.go b/pkg/sentry/platform/ring0/defs_impl.go
index d4bfc5a4a..8efc3825f 100755
--- a/pkg/sentry/platform/ring0/defs_impl.go
+++ b/pkg/sentry/platform/ring0/defs_impl.go
@@ -1,14 +1,14 @@
 package ring0
 
 import (
-	"syscall"
-
 	"fmt"
 	"gvisor.dev/gvisor/pkg/cpuid"
 	"gvisor.dev/gvisor/pkg/sentry/platform/ring0/pagetables"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"io"
 	"reflect"
+	"syscall"
+
+	"gvisor.dev/gvisor/pkg/sentry/usermem"
 )
 
 var (
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index ae56e0ffd..43719085e 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -36,13 +36,13 @@ type NIC struct {
 
 	demux *transportDemuxer
 
-	mu          sync.RWMutex
-	spoofing    bool
-	promiscuous bool
-	primary     map[tcpip.NetworkProtocolNumber]*ilist.List
-	endpoints   map[NetworkEndpointID]*referencedNetworkEndpoint
-	subnets     []tcpip.Subnet
-	mcastJoins  map[NetworkEndpointID]int32
+	mu            sync.RWMutex
+	spoofing      bool
+	promiscuous   bool
+	primary       map[tcpip.NetworkProtocolNumber]*ilist.List
+	endpoints     map[NetworkEndpointID]*referencedNetworkEndpoint
+	addressRanges []tcpip.Subnet
+	mcastJoins    map[NetworkEndpointID]int32
 
 	stats NICStats
 }
@@ -224,7 +224,17 @@ func (n *NIC) getRefOrCreateTemp(protocol tcpip.NetworkProtocolNumber, address t
 	// the caller or if the address is found in the NIC's subnets.
 	createTempEP := spoofingOrPromiscuous
 	if !createTempEP {
-		for _, sn := range n.subnets {
+		for _, sn := range n.addressRanges {
+			// Skip the subnet address.
+			if address == sn.ID() {
+				continue
+			}
+			// For now just skip the broadcast address, until we support it.
+			// FIXME(b/137608825): Add support for sending/receiving directed
+			// (subnet) broadcast.
+			if address == sn.Broadcast() {
+				continue
+			}
 			if sn.Contains(address) {
 				createTempEP = true
 				break
@@ -381,45 +391,38 @@ func (n *NIC) Addresses() []tcpip.ProtocolAddress {
 	return addrs
 }
 
-// AddSubnet adds a new subnet to n, so that it starts accepting packets
-// targeted at the given address and network protocol.
-func (n *NIC) AddSubnet(protocol tcpip.NetworkProtocolNumber, subnet tcpip.Subnet) {
+// AddAddressRange adds a range of addresses to n, so that it starts accepting
+// packets targeted at the given addresses and network protocol. The range is
+// given by a subnet address, and all addresses contained in the subnet are
+// used except for the subnet address itself and the subnet's broadcast
+// address.
+func (n *NIC) AddAddressRange(protocol tcpip.NetworkProtocolNumber, subnet tcpip.Subnet) {
 	n.mu.Lock()
-	n.subnets = append(n.subnets, subnet)
+	n.addressRanges = append(n.addressRanges, subnet)
 	n.mu.Unlock()
 }
 
-// RemoveSubnet removes the given subnet from n.
-func (n *NIC) RemoveSubnet(subnet tcpip.Subnet) {
+// RemoveAddressRange removes the given address range from n.
+func (n *NIC) RemoveAddressRange(subnet tcpip.Subnet) {
 	n.mu.Lock()
 
 	// Use the same underlying array.
-	tmp := n.subnets[:0]
-	for _, sub := range n.subnets {
+	tmp := n.addressRanges[:0]
+	for _, sub := range n.addressRanges {
 		if sub != subnet {
 			tmp = append(tmp, sub)
 		}
 	}
-	n.subnets = tmp
+	n.addressRanges = tmp
 
 	n.mu.Unlock()
 }
 
-// ContainsSubnet reports whether this NIC contains the given subnet.
-func (n *NIC) ContainsSubnet(subnet tcpip.Subnet) bool {
-	for _, s := range n.Subnets() {
-		if s == subnet {
-			return true
-		}
-	}
-	return false
-}
-
 // Subnets returns the Subnets associated with this NIC.
-func (n *NIC) Subnets() []tcpip.Subnet {
+func (n *NIC) AddressRanges() []tcpip.Subnet {
 	n.mu.RLock()
 	defer n.mu.RUnlock()
-	sns := make([]tcpip.Subnet, 0, len(n.subnets)+len(n.endpoints))
+	sns := make([]tcpip.Subnet, 0, len(n.addressRanges)+len(n.endpoints))
 	for nid := range n.endpoints {
 		sn, err := tcpip.NewSubnet(nid.LocalAddress, tcpip.AddressMask(strings.Repeat("\xff", len(nid.LocalAddress))))
 		if err != nil {
@@ -429,7 +432,7 @@ func (n *NIC) Subnets() []tcpip.Subnet {
 		}
 		sns = append(sns, sn)
 	}
-	return append(sns, n.subnets...)
+	return append(sns, n.addressRanges...)
 }
 
 func (n *NIC) removeEndpointLocked(r *referencedNetworkEndpoint) {
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index 1d5e84a8b..6beca6ae8 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -702,14 +702,14 @@ func (s *Stack) CheckNIC(id tcpip.NICID) bool {
 }
 
 // NICSubnets returns a map of NICIDs to their associated subnets.
-func (s *Stack) NICSubnets() map[tcpip.NICID][]tcpip.Subnet {
+func (s *Stack) NICAddressRanges() map[tcpip.NICID][]tcpip.Subnet {
 	s.mu.RLock()
 	defer s.mu.RUnlock()
 
 	nics := map[tcpip.NICID][]tcpip.Subnet{}
 
 	for id, nic := range s.nics {
-		nics[id] = append(nics[id], nic.Subnets()...)
+		nics[id] = append(nics[id], nic.AddressRanges()...)
 	}
 	return nics
 }
@@ -810,45 +810,35 @@ func (s *Stack) AddProtocolAddressWithOptions(id tcpip.NICID, protocolAddress tc
 	return nic.AddAddress(protocolAddress, peb)
 }
 
-// AddSubnet adds a subnet range to the specified NIC.
-func (s *Stack) AddSubnet(id tcpip.NICID, protocol tcpip.NetworkProtocolNumber, subnet tcpip.Subnet) *tcpip.Error {
+// AddAddressRange adds a range of addresses to the specified NIC. The range is
+// given by a subnet address, and all addresses contained in the subnet are
+// used except for the subnet address itself and the subnet's broadcast
+// address.
+func (s *Stack) AddAddressRange(id tcpip.NICID, protocol tcpip.NetworkProtocolNumber, subnet tcpip.Subnet) *tcpip.Error {
 	s.mu.RLock()
 	defer s.mu.RUnlock()
 
 	if nic, ok := s.nics[id]; ok {
-		nic.AddSubnet(protocol, subnet)
+		nic.AddAddressRange(protocol, subnet)
 		return nil
 	}
 
 	return tcpip.ErrUnknownNICID
 }
 
-// RemoveSubnet removes the subnet range from the specified NIC.
-func (s *Stack) RemoveSubnet(id tcpip.NICID, subnet tcpip.Subnet) *tcpip.Error {
+// RemoveAddressRange removes the range of addresses from the specified NIC.
+func (s *Stack) RemoveAddressRange(id tcpip.NICID, subnet tcpip.Subnet) *tcpip.Error {
 	s.mu.RLock()
 	defer s.mu.RUnlock()
 
 	if nic, ok := s.nics[id]; ok {
-		nic.RemoveSubnet(subnet)
+		nic.RemoveAddressRange(subnet)
 		return nil
 	}
 
 	return tcpip.ErrUnknownNICID
 }
 
-// ContainsSubnet reports whether the specified NIC contains the specified
-// subnet.
-func (s *Stack) ContainsSubnet(id tcpip.NICID, subnet tcpip.Subnet) (bool, *tcpip.Error) {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-
-	if nic, ok := s.nics[id]; ok {
-		return nic.ContainsSubnet(subnet), nil
-	}
-
-	return false, tcpip.ErrUnknownNICID
-}
-
 // RemoveAddress removes an existing network-layer address from the specified
 // NIC.
 func (s *Stack) RemoveAddress(id tcpip.NICID, addr tcpip.Address) *tcpip.Error {
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 05aa42c98..418e771d2 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -219,6 +219,15 @@ func (s *Subnet) Mask() AddressMask {
 	return s.mask
 }
 
+// Broadcast returns the subnet's broadcast address.
+func (s *Subnet) Broadcast() Address {
+	addr := []byte(s.address)
+	for i := range addr {
+		addr[i] |= ^s.mask[i]
+	}
+	return Address(addr)
+}
+
 // NICID is a number that uniquely identifies a NIC.
 type NICID int32
 
diff --git a/pkg/tcpip/transport/tcp/accept.go b/pkg/tcpip/transport/tcp/accept.go
index e9c5099ea..0802e984e 100644
--- a/pkg/tcpip/transport/tcp/accept.go
+++ b/pkg/tcpip/transport/tcp/accept.go
@@ -143,6 +143,15 @@ func decSynRcvdCount() {
 	synRcvdCount.Unlock()
 }
 
+// synCookiesInUse() returns true if the synRcvdCount is greater than
+// SynRcvdCountThreshold.
+func synCookiesInUse() bool {
+	synRcvdCount.Lock()
+	v := synRcvdCount.value
+	synRcvdCount.Unlock()
+	return v >= SynRcvdCountThreshold
+}
+
 // newListenContext creates a new listen context.
 func newListenContext(stk *stack.Stack, listenEP *endpoint, rcvWnd seqnum.Size, v6only bool, netProto tcpip.NetworkProtocolNumber) *listenContext {
 	l := &listenContext{
@@ -446,6 +455,27 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) {
 			return
 		}
 
+		if !synCookiesInUse() {
+			// Send a reset as this is an ACK for which there is no
+			// half open connections and we are not using cookies
+			// yet.
+			//
+			// The only time we should reach here when a connection
+			// was opened and closed really quickly and a delayed
+			// ACK was received from the sender.
+			replyWithReset(s)
+			return
+		}
+
+		// Since SYN cookies are in use this is potentially an ACK to a
+		// SYN-ACK we sent but don't have a half open connection state
+		// as cookies are being used to protect against a potential SYN
+		// flood. In such cases validate the cookie and if valid create
+		// a fully connected endpoint and deliver to the accept queue.
+		//
+		// If not, silently drop the ACK to avoid leaking information
+		// when under a potential syn flood attack.
+		//
 		// Validate the cookie.
 		data, ok := ctx.isCookieValid(s.id, s.ackNumber-1, s.sequenceNumber-1)
 		if !ok || int(data) >= len(mssTable) {
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go
index 00d2ae524..21038a65a 100644
--- a/pkg/tcpip/transport/tcp/connect.go
+++ b/pkg/tcpip/transport/tcp/connect.go
@@ -720,13 +720,18 @@ func (e *endpoint) handleClose() *tcpip.Error {
 	return nil
 }
 
-// resetConnectionLocked sends a RST segment and puts the endpoint in an error
-// state with the given error code. This method must only be called from the
-// protocol goroutine.
+// resetConnectionLocked puts the endpoint in an error state with the given
+// error code and sends a RST if and only if the error is not ErrConnectionReset
+// indicating that the connection is being reset due to receiving a RST. This
+// method must only be called from the protocol goroutine.
 func (e *endpoint) resetConnectionLocked(err *tcpip.Error) {
-	e.sendRaw(buffer.VectorisedView{}, header.TCPFlagAck|header.TCPFlagRst, e.snd.sndUna, e.rcv.rcvNxt, 0)
+	// Only send a reset if the connection is being aborted for a reason
+	// other than receiving a reset.
 	e.state = StateError
 	e.hardError = err
+	if err != tcpip.ErrConnectionReset {
+		e.sendRaw(buffer.VectorisedView{}, header.TCPFlagAck|header.TCPFlagRst, e.snd.sndUna, e.rcv.rcvNxt, 0)
+	}
 }
 
 // completeWorkerLocked is called by the worker goroutine when it's about to
@@ -806,7 +811,7 @@ func (e *endpoint) keepaliveTimerExpired() *tcpip.Error {
 
 	if e.keepalive.unacked >= e.keepalive.count {
 		e.keepalive.Unlock()
-		return tcpip.ErrConnectionReset
+		return tcpip.ErrTimeout
 	}
 
 	// RFC1122 4.2.3.6: TCP keepalive is a dataless ACK with
@@ -1068,6 +1073,10 @@ func (e *endpoint) protocolMainLoop(handshake bool) *tcpip.Error {
 		e.workMu.Lock()
 		if err := funcs[v].f(); err != nil {
 			e.mu.Lock()
+			// Ensure we release all endpoint registration and route
+			// references as the connection is now in an error
+			// state.
+			e.workerCleanup = true
 			e.resetConnectionLocked(err)
 			// Lock released below.
 			epilogue()