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authorBhasker Hariharan <bhaskerh@google.com>2019-10-10 15:13:39 -0700
committergVisor bot <gvisor-bot@google.com>2019-10-10 15:14:55 -0700
commitc7e901f47a09eaac56bd4813227edff016fa6bff (patch)
tree2f249032583fb43b92e24e89774ece0e542ec3e5 /pkg/tcpip/network/ipv4
parent065339193e4309a8c771ba88058c3b2d96c07e78 (diff)
Fix bugs in fragment handling.
Strengthen the header.IPv4.IsValid check to correctly check for IHL/TotalLength fields. Also add a check to make sure fragmentOffsets + size of the fragment do not cause a wrap around for the end of the fragment. PiperOrigin-RevId: 274049313
Diffstat (limited to 'pkg/tcpip/network/ipv4')
-rw-r--r--pkg/tcpip/network/ipv4/ipv4.go16
-rw-r--r--pkg/tcpip/network/ipv4/ipv4_test.go104
2 files changed, 120 insertions, 0 deletions
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 162aa1b4d..fb6358fbb 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -296,6 +296,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, vv buffer.VectorisedView) {
headerView := vv.First()
h := header.IPv4(headerView)
if !h.IsValid(vv.Size()) {
+ r.Stats().IP.MalformedPacketsReceived.Increment()
return
}
@@ -306,8 +307,23 @@ func (e *endpoint) HandlePacket(r *stack.Route, vv buffer.VectorisedView) {
more := (h.Flags() & header.IPv4FlagMoreFragments) != 0
if more || h.FragmentOffset() != 0 {
+ if vv.Size() == 0 {
+ // Drop the packet as it's marked as a fragment but has
+ // no payload.
+ r.Stats().IP.MalformedPacketsReceived.Increment()
+ r.Stats().IP.MalformedFragmentsReceived.Increment()
+ return
+ }
// The packet is a fragment, let's try to reassemble it.
last := h.FragmentOffset() + uint16(vv.Size()) - 1
+ // Drop the packet if the fragmentOffset is incorrect. i.e the
+ // combination of fragmentOffset and vv.size() causes a wrap
+ // around resulting in last being less than the offset.
+ if last < h.FragmentOffset() {
+ r.Stats().IP.MalformedPacketsReceived.Increment()
+ r.Stats().IP.MalformedFragmentsReceived.Increment()
+ return
+ }
var ready bool
vv, ready = e.fragmentation.Process(hash.IPv4FragmentHash(h), h.FragmentOffset(), last, more, vv)
if !ready {
diff --git a/pkg/tcpip/network/ipv4/ipv4_test.go b/pkg/tcpip/network/ipv4/ipv4_test.go
index 8b7500095..3dcb503e2 100644
--- a/pkg/tcpip/network/ipv4/ipv4_test.go
+++ b/pkg/tcpip/network/ipv4/ipv4_test.go
@@ -366,3 +366,107 @@ func TestFragmentationErrors(t *testing.T) {
})
}
}
+
+func TestInvalidFragments(t *testing.T) {
+ // These packets have both IHL and TotalLength set to 0.
+ testCases := []struct {
+ name string
+ packets [][]byte
+ wantMalformedIPPackets uint64
+ wantMalformedFragments uint64
+ }{
+ {
+ "ihl_totallen_zero_valid_frag_offset",
+ [][]byte{
+ {0x40, 0x30, 0x00, 0x00, 0x6c, 0x74, 0x7d, 0x30, 0x30, 0x30, 0x30, 0x30, 0x39, 0x32, 0x39, 0x33, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ },
+ 1,
+ 0,
+ },
+ {
+ "ihl_totallen_zero_invalid_frag_offset",
+ [][]byte{
+ {0x40, 0x30, 0x00, 0x00, 0x6c, 0x74, 0x20, 0x00, 0x30, 0x30, 0x30, 0x30, 0x39, 0x32, 0x39, 0x33, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ },
+ 1,
+ 0,
+ },
+ {
+ // Total Length of 37(20 bytes IP header + 17 bytes of
+ // payload)
+ // Frag Offset of 0x1ffe = 8190*8 = 65520
+ // Leading to the fragment end to be past 65535.
+ "ihl_totallen_valid_invalid_frag_offset_1",
+ [][]byte{
+ {0x45, 0x30, 0x00, 0x25, 0x6c, 0x74, 0x1f, 0xfe, 0x30, 0x30, 0x30, 0x30, 0x39, 0x32, 0x39, 0x33, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ },
+ 1,
+ 1,
+ },
+ // The following 3 tests were found by running a fuzzer and were
+ // triggering a panic in the IPv4 reassembler code.
+ {
+ "ihl_less_than_ipv4_minimum_size_1",
+ [][]byte{
+ {0x42, 0x30, 0x0, 0x30, 0x30, 0x40, 0x0, 0xf3, 0x30, 0x1, 0x30, 0x30, 0x73, 0x73, 0x69, 0x6e, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ {0x42, 0x30, 0x0, 0x8, 0x30, 0x40, 0x20, 0x0, 0x30, 0x1, 0x30, 0x30, 0x73, 0x73, 0x69, 0x6e, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ },
+ 2,
+ 0,
+ },
+ {
+ "ihl_less_than_ipv4_minimum_size_2",
+ [][]byte{
+ {0x42, 0x30, 0x0, 0x30, 0x30, 0x40, 0xb3, 0x12, 0x30, 0x6, 0x30, 0x30, 0x73, 0x73, 0x69, 0x6e, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ {0x42, 0x30, 0x0, 0x8, 0x30, 0x40, 0x20, 0x0, 0x30, 0x6, 0x30, 0x30, 0x73, 0x73, 0x69, 0x6e, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ },
+ 2,
+ 0,
+ },
+ {
+ "ihl_less_than_ipv4_minimum_size_3",
+ [][]byte{
+ {0x42, 0x30, 0x0, 0x30, 0x30, 0x40, 0xb3, 0x30, 0x30, 0x6, 0x30, 0x30, 0x73, 0x73, 0x69, 0x6e, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ {0x42, 0x30, 0x0, 0x8, 0x30, 0x40, 0x20, 0x0, 0x30, 0x6, 0x30, 0x30, 0x73, 0x73, 0x69, 0x6e, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ },
+ 2,
+ 0,
+ },
+ {
+ "fragment_with_short_total_len_extra_payload",
+ [][]byte{
+ {0x46, 0x30, 0x00, 0x30, 0x30, 0x40, 0x0e, 0x12, 0x30, 0x06, 0x30, 0x30, 0x73, 0x73, 0x69, 0x6e, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ {0x46, 0x30, 0x00, 0x18, 0x30, 0x40, 0x20, 0x00, 0x30, 0x06, 0x30, 0x30, 0x73, 0x73, 0x69, 0x6e, 0xff, 0xff, 0xff, 0xff, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30},
+ },
+ 1,
+ 1,
+ },
+ }
+
+ for _, tc := range testCases {
+ t.Run(tc.name, func(t *testing.T) {
+ const nicid tcpip.NICID = 42
+ s := stack.New(stack.Options{
+ NetworkProtocols: []stack.NetworkProtocol{
+ ipv4.NewProtocol(),
+ },
+ })
+
+ var linkAddr = tcpip.LinkAddress([]byte{0x30, 0x30, 0x30, 0x30, 0x30, 0x30})
+ var remoteLinkAddr = tcpip.LinkAddress([]byte{0x30, 0x30, 0x30, 0x30, 0x30, 0x31})
+ ep := channel.New(10, 1500, linkAddr)
+ s.CreateNIC(nicid, sniffer.New(ep))
+
+ for _, pkt := range tc.packets {
+ ep.InjectLinkAddr(header.IPv4ProtocolNumber, remoteLinkAddr, buffer.NewVectorisedView(len(pkt), []buffer.View{pkt}))
+ }
+
+ if got, want := s.Stats().IP.MalformedPacketsReceived.Value(), tc.wantMalformedIPPackets; got != want {
+ t.Errorf("incorrect Stats.IP.MalformedPacketsReceived, got: %d, want: %d", got, want)
+ }
+ if got, want := s.Stats().IP.MalformedFragmentsReceived.Value(), tc.wantMalformedFragments; got != want {
+ t.Errorf("incorrect Stats.IP.MalformedFragmentsReceived, got: %d, want: %d", got, want)
+ }
+ })
+ }
+}