From 47515f475167ffa23267ca0b9d1b39e7907587d6 Mon Sep 17 00:00:00 2001 From: Ting-Yu Wang Date: Thu, 13 Aug 2020 13:07:03 -0700 Subject: Migrate to PacketHeader API for PacketBuffer. Formerly, when a packet is constructed or parsed, all headers are set by the client code. This almost always involved prepending to pk.Header buffer or trimming pk.Data portion. This is known to prone to bugs, due to the complexity and number of the invariants assumed across netstack to maintain. In the new PacketHeader API, client will call Push()/Consume() method to construct/parse an outgoing/incoming packet. All invariants, such as slicing and trimming, are maintained by the API itself. NewPacketBuffer() is introduced to create new PacketBuffer. Zero value is no longer valid. PacketBuffer now assumes the packet is a concatenation of following portions: * LinkHeader * NetworkHeader * TransportHeader * Data Any of them could be empty, or zero-length. PiperOrigin-RevId: 326507688 --- pkg/tcpip/transport/tcp/connect.go | 30 ++++++++++------------ pkg/tcpip/transport/tcp/protocol.go | 17 ++++++------ pkg/tcpip/transport/tcp/segment.go | 2 +- pkg/tcpip/transport/tcp/testing/context/context.go | 28 +++++++++++--------- 4 files changed, 38 insertions(+), 39 deletions(-) (limited to 'pkg/tcpip/transport/tcp') diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index 46702906b..290172ac9 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -746,11 +746,7 @@ func (e *endpoint) sendTCP(r *stack.Route, tf tcpFields, data buffer.VectorisedV func buildTCPHdr(r *stack.Route, tf tcpFields, pkt *stack.PacketBuffer, gso *stack.GSO) { optLen := len(tf.opts) - hdr := &pkt.Header - packetSize := pkt.Data.Size() - // Initialize the header. - tcp := header.TCP(hdr.Prepend(header.TCPMinimumSize + optLen)) - pkt.TransportHeader = buffer.View(tcp) + tcp := header.TCP(pkt.TransportHeader().Push(header.TCPMinimumSize + optLen)) tcp.Encode(&header.TCPFields{ SrcPort: tf.id.LocalPort, DstPort: tf.id.RemotePort, @@ -762,8 +758,7 @@ func buildTCPHdr(r *stack.Route, tf tcpFields, pkt *stack.PacketBuffer, gso *sta }) copy(tcp[header.TCPMinimumSize:], tf.opts) - length := uint16(hdr.UsedLength() + packetSize) - xsum := r.PseudoHeaderChecksum(ProtocolNumber, length) + xsum := r.PseudoHeaderChecksum(ProtocolNumber, uint16(pkt.Size())) // Only calculate the checksum if offloading isn't supported. if gso != nil && gso.NeedsCsum { // This is called CHECKSUM_PARTIAL in the Linux kernel. We @@ -801,17 +796,18 @@ func sendTCPBatch(r *stack.Route, tf tcpFields, data buffer.VectorisedView, gso packetSize = size } size -= packetSize - var pkt stack.PacketBuffer - pkt.Header = buffer.NewPrependable(hdrSize) + pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ + ReserveHeaderBytes: hdrSize, + }) pkt.Hash = tf.txHash pkt.Owner = owner pkt.EgressRoute = r pkt.GSOOptions = gso pkt.NetworkProtocolNumber = r.NetworkProtocolNumber() data.ReadToVV(&pkt.Data, packetSize) - buildTCPHdr(r, tf, &pkt, gso) + buildTCPHdr(r, tf, pkt, gso) tf.seq = tf.seq.Add(seqnum.Size(packetSize)) - pkts.PushBack(&pkt) + pkts.PushBack(pkt) } if tf.ttl == 0 { @@ -837,12 +833,12 @@ func sendTCP(r *stack.Route, tf tcpFields, data buffer.VectorisedView, gso *stac return sendTCPBatch(r, tf, data, gso, owner) } - pkt := &stack.PacketBuffer{ - Header: buffer.NewPrependable(header.TCPMinimumSize + int(r.MaxHeaderLength()) + optLen), - Data: data, - Hash: tf.txHash, - Owner: owner, - } + pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ + ReserveHeaderBytes: header.TCPMinimumSize + int(r.MaxHeaderLength()) + optLen, + Data: data, + }) + pkt.Hash = tf.txHash + pkt.Owner = owner buildTCPHdr(r, tf, pkt, gso) if tf.ttl == 0 { diff --git a/pkg/tcpip/transport/tcp/protocol.go b/pkg/tcpip/transport/tcp/protocol.go index 49a673b42..c5afa2680 100644 --- a/pkg/tcpip/transport/tcp/protocol.go +++ b/pkg/tcpip/transport/tcp/protocol.go @@ -21,7 +21,6 @@ package tcp import ( - "fmt" "runtime" "strings" "time" @@ -547,22 +546,22 @@ func (p *protocol) SynRcvdCounter() *synRcvdCounter { // Parse implements stack.TransportProtocol.Parse. func (*protocol) Parse(pkt *stack.PacketBuffer) bool { - hdr, ok := pkt.Data.PullUp(header.TCPMinimumSize) + // TCP header is variable length, peek at it first. + hdrLen := header.TCPMinimumSize + hdr, ok := pkt.Data.PullUp(hdrLen) if !ok { return false } // If the header has options, pull those up as well. if offset := int(header.TCP(hdr).DataOffset()); offset > header.TCPMinimumSize && offset <= pkt.Data.Size() { - hdr, ok = pkt.Data.PullUp(offset) - if !ok { - panic(fmt.Sprintf("There should be at least %d bytes in pkt.Data.", offset)) - } + // TODO(gvisor.dev/issue/2404): Figure out whether to reject this kind of + // packets. + hdrLen = offset } - pkt.TransportHeader = hdr - pkt.Data.TrimFront(len(hdr)) - return true + _, ok = pkt.TransportHeader().Consume(hdrLen) + return ok } // NewProtocol returns a TCP transport protocol. diff --git a/pkg/tcpip/transport/tcp/segment.go b/pkg/tcpip/transport/tcp/segment.go index bb60dc29d..94307d31a 100644 --- a/pkg/tcpip/transport/tcp/segment.go +++ b/pkg/tcpip/transport/tcp/segment.go @@ -68,7 +68,7 @@ func newSegment(r *stack.Route, id stack.TransportEndpointID, pkt *stack.PacketB route: r.Clone(), } s.data = pkt.Data.Clone(s.views[:]) - s.hdr = header.TCP(pkt.TransportHeader) + s.hdr = header.TCP(pkt.TransportHeader().View()) s.rcvdTime = time.Now() return s } diff --git a/pkg/tcpip/transport/tcp/testing/context/context.go b/pkg/tcpip/transport/tcp/testing/context/context.go index 37e7767d6..927bc71e0 100644 --- a/pkg/tcpip/transport/tcp/testing/context/context.go +++ b/pkg/tcpip/transport/tcp/testing/context/context.go @@ -257,8 +257,8 @@ func (c *Context) GetPacket() []byte { c.t.Fatalf("Bad network protocol: got %v, wanted %v", p.Proto, ipv4.ProtocolNumber) } - hdr := p.Pkt.Header.View() - b := append(hdr[:len(hdr):len(hdr)], p.Pkt.Data.ToView()...) + vv := buffer.NewVectorisedView(p.Pkt.Size(), p.Pkt.Views()) + b := vv.ToView() if p.GSO != nil && p.GSO.L3HdrLen != header.IPv4MinimumSize { c.t.Errorf("L3HdrLen %v (expected %v)", p.GSO.L3HdrLen, header.IPv4MinimumSize) @@ -284,8 +284,8 @@ func (c *Context) GetPacketNonBlocking() []byte { c.t.Fatalf("Bad network protocol: got %v, wanted %v", p.Proto, ipv4.ProtocolNumber) } - hdr := p.Pkt.Header.View() - b := append(hdr[:len(hdr):len(hdr)], p.Pkt.Data.ToView()...) + vv := buffer.NewVectorisedView(p.Pkt.Size(), p.Pkt.Views()) + b := vv.ToView() checker.IPv4(c.t, b, checker.SrcAddr(StackAddr), checker.DstAddr(TestAddr)) return b @@ -318,9 +318,10 @@ func (c *Context) SendICMPPacket(typ header.ICMPv4Type, code uint8, p1, p2 []byt copy(icmp[header.ICMPv4PayloadOffset:], p2) // Inject packet. - c.linkEP.InjectInbound(ipv4.ProtocolNumber, &stack.PacketBuffer{ + pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ Data: buf.ToVectorisedView(), }) + c.linkEP.InjectInbound(ipv4.ProtocolNumber, pkt) } // BuildSegment builds a TCP segment based on the given Headers and payload. @@ -374,26 +375,29 @@ func (c *Context) BuildSegmentWithAddrs(payload []byte, h *Headers, src, dst tcp // SendSegment sends a TCP segment that has already been built and written to a // buffer.VectorisedView. func (c *Context) SendSegment(s buffer.VectorisedView) { - c.linkEP.InjectInbound(ipv4.ProtocolNumber, &stack.PacketBuffer{ + pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ Data: s, }) + c.linkEP.InjectInbound(ipv4.ProtocolNumber, pkt) } // SendPacket builds and sends a TCP segment(with the provided payload & TCP // headers) in an IPv4 packet via the link layer endpoint. func (c *Context) SendPacket(payload []byte, h *Headers) { - c.linkEP.InjectInbound(ipv4.ProtocolNumber, &stack.PacketBuffer{ + pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ Data: c.BuildSegment(payload, h), }) + c.linkEP.InjectInbound(ipv4.ProtocolNumber, pkt) } // SendPacketWithAddrs builds and sends a TCP segment(with the provided payload // & TCPheaders) in an IPv4 packet via the link layer endpoint using the // provided source and destination IPv4 addresses. func (c *Context) SendPacketWithAddrs(payload []byte, h *Headers, src, dst tcpip.Address) { - c.linkEP.InjectInbound(ipv4.ProtocolNumber, &stack.PacketBuffer{ + pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ Data: c.BuildSegmentWithAddrs(payload, h, src, dst), }) + c.linkEP.InjectInbound(ipv4.ProtocolNumber, pkt) } // SendAck sends an ACK packet. @@ -514,9 +518,8 @@ func (c *Context) GetV6Packet() []byte { if p.Proto != ipv6.ProtocolNumber { c.t.Fatalf("Bad network protocol: got %v, wanted %v", p.Proto, ipv6.ProtocolNumber) } - b := make([]byte, p.Pkt.Header.UsedLength()+p.Pkt.Data.Size()) - copy(b, p.Pkt.Header.View()) - copy(b[p.Pkt.Header.UsedLength():], p.Pkt.Data.ToView()) + vv := buffer.NewVectorisedView(p.Pkt.Size(), p.Pkt.Views()) + b := vv.ToView() checker.IPv6(c.t, b, checker.SrcAddr(StackV6Addr), checker.DstAddr(TestV6Addr)) return b @@ -566,9 +569,10 @@ func (c *Context) SendV6PacketWithAddrs(payload []byte, h *Headers, src, dst tcp t.SetChecksum(^t.CalculateChecksum(xsum)) // Inject packet. - c.linkEP.InjectInbound(ipv6.ProtocolNumber, &stack.PacketBuffer{ + pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ Data: buf.ToVectorisedView(), }) + c.linkEP.InjectInbound(ipv6.ProtocolNumber, pkt) } // CreateConnected creates a connected TCP endpoint. -- cgit v1.2.3