Support fragments from different sources

Prevent fragments with different source-destination pairs from
conflicting with each other.

Test:
    - ipv6_test.TestReceiveIPv6Fragments
    - ipv4_test.TestReceiveIPv6Fragments
PiperOrigin-RevId: 324283246

4 files changed, 45 insertions, 29 deletions

diff --git a/pkg/tcpip/network/fragmentation/fragmentation.go b/pkg/tcpip/network/fragmentation/fragmentation.go
index ffbadb6e2..1827666c5 100644
--- a/pkg/tcpip/network/fragmentation/fragmentation.go
+++ b/pkg/tcpip/network/fragmentation/fragmentation.go
@@ -23,6 +23,7 @@ import (
 	"time"
 
 	"gvisor.dev/gvisor/pkg/sync"
+	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 )
 
@@ -52,13 +53,30 @@ var (
 	ErrInvalidArgs = errors.New("invalid args")
 )
 
+// FragmentID is the identifier for a fragment.
+type FragmentID struct {
+	// Source is the source address of the fragment.
+	Source tcpip.Address
+
+	// Destination is the destination address of the fragment.
+	Destination tcpip.Address
+
+	// ID is the identification value of the fragment.
+	//
+	// This is a uint32 because IPv6 uses a 32-bit identification value.
+	ID uint32
+
+	// The protocol for the packet.
+	Protocol uint8
+}
+
 // Fragmentation is the main structure that other modules
 // of the stack should use to implement IP Fragmentation.
 type Fragmentation struct {
 	mu           sync.Mutex
 	highLimit    int
 	lowLimit     int
-	reassemblers map[uint32]*reassembler
+	reassemblers map[FragmentID]*reassembler
 	rList        reassemblerList
 	size         int
 	timeout      time.Duration
@@ -93,7 +111,7 @@ func NewFragmentation(blockSize uint16, highMemoryLimit, lowMemoryLimit int, rea
 	}
 
 	return &Fragmentation{
-		reassemblers: make(map[uint32]*reassembler),
+		reassemblers: make(map[FragmentID]*reassembler),
 		highLimit:    highMemoryLimit,
 		lowLimit:     lowMemoryLimit,
 		timeout:      reassemblingTimeout,
@@ -109,7 +127,7 @@ func NewFragmentation(blockSize uint16, highMemoryLimit, lowMemoryLimit int, rea
 // first must be a multiple of the block size f is configured with. The size
 // of the fragment data must be a multiple of the block size, unless there are
 // no fragments following this fragment (more set to false).
-func (f *Fragmentation) Process(id uint32, first, last uint16, more bool, vv buffer.VectorisedView) (buffer.VectorisedView, bool, error) {
+func (f *Fragmentation) Process(id FragmentID, first, last uint16, more bool, vv buffer.VectorisedView) (buffer.VectorisedView, bool, error) {
 	if first > last {
 		return buffer.VectorisedView{}, false, fmt.Errorf("first=%d is greater than last=%d: %w", first, last, ErrInvalidArgs)
 	}
diff --git a/pkg/tcpip/network/fragmentation/fragmentation_test.go b/pkg/tcpip/network/fragmentation/fragmentation_test.go
index ebc3232e5..9eedd33c4 100644
--- a/pkg/tcpip/network/fragmentation/fragmentation_test.go
+++ b/pkg/tcpip/network/fragmentation/fragmentation_test.go
@@ -34,7 +34,7 @@ func vv(size int, pieces ...string) buffer.VectorisedView {
 }
 
 type processInput struct {
-	id    uint32
+	id    FragmentID
 	first uint16
 	last  uint16
 	more  bool
@@ -54,8 +54,8 @@ var processTestCases = []struct {
 	{
 		comment: "One ID",
 		in: []processInput{
-			{id: 0, first: 0, last: 1, more: true, vv: vv(2, "01")},
-			{id: 0, first: 2, last: 3, more: false, vv: vv(2, "23")},
+			{id: FragmentID{ID: 0}, first: 0, last: 1, more: true, vv: vv(2, "01")},
+			{id: FragmentID{ID: 0}, first: 2, last: 3, more: false, vv: vv(2, "23")},
 		},
 		out: []processOutput{
 			{vv: buffer.VectorisedView{}, done: false},
@@ -65,10 +65,10 @@ var processTestCases = []struct {
 	{
 		comment: "Two IDs",
 		in: []processInput{
-			{id: 0, first: 0, last: 1, more: true, vv: vv(2, "01")},
-			{id: 1, first: 0, last: 1, more: true, vv: vv(2, "ab")},
-			{id: 1, first: 2, last: 3, more: false, vv: vv(2, "cd")},
-			{id: 0, first: 2, last: 3, more: false, vv: vv(2, "23")},
+			{id: FragmentID{ID: 0}, first: 0, last: 1, more: true, vv: vv(2, "01")},
+			{id: FragmentID{ID: 1}, first: 0, last: 1, more: true, vv: vv(2, "ab")},
+			{id: FragmentID{ID: 1}, first: 2, last: 3, more: false, vv: vv(2, "cd")},
+			{id: FragmentID{ID: 0}, first: 2, last: 3, more: false, vv: vv(2, "23")},
 		},
 		out: []processOutput{
 			{vv: buffer.VectorisedView{}, done: false},
@@ -113,12 +113,12 @@ func TestReassemblingTimeout(t *testing.T) {
 	timeout := time.Millisecond
 	f := NewFragmentation(minBlockSize, 1024, 512, timeout)
 	// Send first fragment with id = 0, first = 0, last = 0, and more = true.
-	f.Process(0, 0, 0, true, vv(1, "0"))
+	f.Process(FragmentID{}, 0, 0, true, vv(1, "0"))
 	// Sleep more than the timeout.
 	time.Sleep(2 * timeout)
 	// Send another fragment that completes a packet.
 	// However, no packet should be reassembled because the fragment arrived after the timeout.
-	_, done, err := f.Process(0, 1, 1, false, vv(1, "1"))
+	_, done, err := f.Process(FragmentID{}, 1, 1, false, vv(1, "1"))
 	if err != nil {
 		t.Fatalf("f.Process(0, 1, 1, false, vv(1, \"1\")) failed: %v", err)
 	}
@@ -130,23 +130,23 @@ func TestReassemblingTimeout(t *testing.T) {
 func TestMemoryLimits(t *testing.T) {
 	f := NewFragmentation(minBlockSize, 3, 1, DefaultReassembleTimeout)
 	// Send first fragment with id = 0.
-	f.Process(0, 0, 0, true, vv(1, "0"))
+	f.Process(FragmentID{ID: 0}, 0, 0, true, vv(1, "0"))
 	// Send first fragment with id = 1.
-	f.Process(1, 0, 0, true, vv(1, "1"))
+	f.Process(FragmentID{ID: 1}, 0, 0, true, vv(1, "1"))
 	// Send first fragment with id = 2.
-	f.Process(2, 0, 0, true, vv(1, "2"))
+	f.Process(FragmentID{ID: 2}, 0, 0, true, vv(1, "2"))
 
 	// Send first fragment with id = 3. This should caused id = 0 and id = 1 to be
 	// evicted.
-	f.Process(3, 0, 0, true, vv(1, "3"))
+	f.Process(FragmentID{ID: 3}, 0, 0, true, vv(1, "3"))
 
-	if _, ok := f.reassemblers[0]; ok {
+	if _, ok := f.reassemblers[FragmentID{ID: 0}]; ok {
 		t.Errorf("Memory limits are not respected: id=0 has not been evicted.")
 	}
-	if _, ok := f.reassemblers[1]; ok {
+	if _, ok := f.reassemblers[FragmentID{ID: 1}]; ok {
 		t.Errorf("Memory limits are not respected: id=1 has not been evicted.")
 	}
-	if _, ok := f.reassemblers[3]; !ok {
+	if _, ok := f.reassemblers[FragmentID{ID: 3}]; !ok {
 		t.Errorf("Implementation of memory limits is wrong: id=3 is not present.")
 	}
 }
@@ -154,9 +154,9 @@ func TestMemoryLimits(t *testing.T) {
 func TestMemoryLimitsIgnoresDuplicates(t *testing.T) {
 	f := NewFragmentation(minBlockSize, 1, 0, DefaultReassembleTimeout)
 	// Send first fragment with id = 0.
-	f.Process(0, 0, 0, true, vv(1, "0"))
+	f.Process(FragmentID{}, 0, 0, true, vv(1, "0"))
 	// Send the same packet again.
-	f.Process(0, 0, 0, true, vv(1, "0"))
+	f.Process(FragmentID{}, 0, 0, true, vv(1, "0"))
 
 	got := f.size
 	want := 1
@@ -166,8 +166,6 @@ func TestMemoryLimitsIgnoresDuplicates(t *testing.T) {
 }
 
 func TestErrors(t *testing.T) {
-	const fragID = 5
-
 	tests := []struct {
 		name      string
 		blockSize uint16
@@ -250,12 +248,12 @@ func TestErrors(t *testing.T) {
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
 			f := NewFragmentation(test.blockSize, HighFragThreshold, LowFragThreshold, DefaultReassembleTimeout)
-			_, done, err := f.Process(fragID, test.first, test.last, test.more, vv(len(test.data), test.data))
+			_, done, err := f.Process(FragmentID{}, test.first, test.last, test.more, vv(len(test.data), test.data))
 			if !errors.Is(err, test.err) {
-				t.Errorf("got Proceess(%d, %d, %d, %t, %q) = (_, _, %v), want = (_, _, %v)", fragID, test.first, test.last, test.more, test.data, err, test.err)
+				t.Errorf("got Proceess(_, %d, %d, %t, %q) = (_, _, %v), want = (_, _, %v)", test.first, test.last, test.more, test.data, err, test.err)
 			}
 			if done {
-				t.Errorf("got Proceess(%d, %d, %d, %t, %q) = (_, true, _), want = (_, false, _)", fragID, test.first, test.last, test.more, test.data)
+				t.Errorf("got Proceess(_, %d, %d, %t, %q) = (_, true, _), want = (_, false, _)", test.first, test.last, test.more, test.data)
 			}
 		})
 	}
diff --git a/pkg/tcpip/network/fragmentation/reassembler.go b/pkg/tcpip/network/fragmentation/reassembler.go
index 0a83d81f2..50d30bbf0 100644
--- a/pkg/tcpip/network/fragmentation/reassembler.go
+++ b/pkg/tcpip/network/fragmentation/reassembler.go
@@ -32,7 +32,7 @@ type hole struct {
 
 type reassembler struct {
 	reassemblerEntry
-	id           uint32
+	id           FragmentID
 	size         int
 	mu           sync.Mutex
 	holes        []hole
@@ -42,7 +42,7 @@ type reassembler struct {
 	creationTime time.Time
 }
 
-func newReassembler(id uint32) *reassembler {
+func newReassembler(id FragmentID) *reassembler {
 	r := &reassembler{
 		id:           id,
 		holes:        make([]hole, 0, 16),
diff --git a/pkg/tcpip/network/fragmentation/reassembler_test.go b/pkg/tcpip/network/fragmentation/reassembler_test.go
index 7eee0710d..dff7c9dcb 100644
--- a/pkg/tcpip/network/fragmentation/reassembler_test.go
+++ b/pkg/tcpip/network/fragmentation/reassembler_test.go
@@ -94,7 +94,7 @@ var holesTestCases = []struct {
 
 func TestUpdateHoles(t *testing.T) {
 	for _, c := range holesTestCases {
-		r := newReassembler(0)
+		r := newReassembler(FragmentID{})
 		for _, i := range c.in {
 			r.updateHoles(i.first, i.last, i.more)
 		}