Merge release-20200622.1-164-gdb653bb34 (automated)

7 files changed, 111 insertions, 88 deletions

diff --git a/pkg/abi/linux/linux_abi_autogen_unsafe.go b/pkg/abi/linux/linux_abi_autogen_unsafe.go
index ac656f14c..1de7cc5c8 100644
--- a/pkg/abi/linux/linux_abi_autogen_unsafe.go
+++ b/pkg/abi/linux/linux_abi_autogen_unsafe.go
@@ -138,7 +138,7 @@ func (s *Statx) MarshalUnsafe(dst []byte) {
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
 func (s *Statx) UnmarshalUnsafe(src []byte) {
-    if s.Atime.Packed() && s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() {
+    if s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() && s.Atime.Packed() {
         safecopy.CopyOut(unsafe.Pointer(s), src)
     } else {
         s.UnmarshalBytes(src)
@@ -178,7 +178,7 @@ func (s *Statx) CopyOut(task marshal.Task, addr usermem.Addr) (int, error) {
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
 func (s *Statx) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) {
-    if !s.Atime.Packed() && s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() {
+    if !s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() && s.Atime.Packed() {
         // Type Statx doesn't have a packed layout in memory, fall back to UnmarshalBytes.
         buf := task.CopyScratchBuffer(s.SizeBytes()) // escapes: okay.
         length, err := task.CopyInBytes(addr, buf) // escapes: okay.
diff --git a/pkg/iovec/iovec.go b/pkg/iovec/iovec.go
new file mode 100644
index 000000000..dd70fe80f
--- /dev/null
+++ b/pkg/iovec/iovec.go
@@ -0,0 +1,75 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build linux
+
+// Package iovec provides helpers to interact with vectorized I/O on host
+// system.
+package iovec
+
+import (
+	"syscall"
+
+	"gvisor.dev/gvisor/pkg/abi/linux"
+)
+
+// MaxIovs is the maximum number of iovecs host platform can accept.
+var MaxIovs = linux.UIO_MAXIOV
+
+// Builder is a builder for slice of syscall.Iovec.
+type Builder struct {
+	iovec   []syscall.Iovec
+	storage [8]syscall.Iovec
+
+	// overflow tracks the last buffer when iovec length is at MaxIovs.
+	overflow []byte
+}
+
+// Add adds buf to b preparing to be written. Zero-length buf won't be added.
+func (b *Builder) Add(buf []byte) {
+	if len(buf) == 0 {
+		return
+	}
+	if b.iovec == nil {
+		b.iovec = b.storage[:0]
+	}
+	if len(b.iovec) >= MaxIovs {
+		b.addByAppend(buf)
+		return
+	}
+	b.iovec = append(b.iovec, syscall.Iovec{
+		Base: &buf[0],
+		Len:  uint64(len(buf)),
+	})
+	// Keep the last buf if iovec is at max capacity. We will need to append to it
+	// for later bufs.
+	if len(b.iovec) == MaxIovs {
+		n := len(buf)
+		b.overflow = buf[:n:n]
+	}
+}
+
+func (b *Builder) addByAppend(buf []byte) {
+	b.overflow = append(b.overflow, buf...)
+	b.iovec[len(b.iovec)-1] = syscall.Iovec{
+		Base: &b.overflow[0],
+		Len:  uint64(len(b.overflow)),
+	}
+}
+
+// Build returns the final Iovec slice. The length of returned iovec will not
+// excceed MaxIovs.
+func (b *Builder) Build() []syscall.Iovec {
+	return b.iovec
+}
diff --git a/pkg/iovec/iovec_state_autogen.go b/pkg/iovec/iovec_state_autogen.go
new file mode 100644
index 000000000..c2e428cbe
--- /dev/null
+++ b/pkg/iovec/iovec_state_autogen.go
@@ -0,0 +1,5 @@
+// automatically generated by stateify.
+
+// +build linux
+
+package iovec
diff --git a/pkg/sentry/fs/host/socket_iovec.go b/pkg/sentry/fs/host/socket_iovec.go
index 5c18dbd5e..905afb50d 100644
--- a/pkg/sentry/fs/host/socket_iovec.go
+++ b/pkg/sentry/fs/host/socket_iovec.go
@@ -17,15 +17,12 @@ package host
 import (
 	"syscall"
 
-	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/iovec"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
 
 // LINT.IfChange
 
-// maxIovs is the maximum number of iovecs to pass to the host.
-var maxIovs = linux.UIO_MAXIOV
-
 // copyToMulti copies as many bytes from src to dst as possible.
 func copyToMulti(dst [][]byte, src []byte) {
 	for _, d := range dst {
@@ -76,7 +73,7 @@ func buildIovec(bufs [][]byte, maxlen int64, truncate bool) (length int64, iovec
 		}
 	}
 
-	if iovsRequired > maxIovs {
+	if iovsRequired > iovec.MaxIovs {
 		// The kernel will reject our call if we pass this many iovs.
 		// Use a single intermediate buffer instead.
 		b := make([]byte, stopLen)
diff --git a/pkg/sentry/fsimpl/host/socket_iovec.go b/pkg/sentry/fsimpl/host/socket_iovec.go
index 584c247d2..fc0d5fd38 100644
--- a/pkg/sentry/fsimpl/host/socket_iovec.go
+++ b/pkg/sentry/fsimpl/host/socket_iovec.go
@@ -17,13 +17,10 @@ package host
 import (
 	"syscall"
 
-	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/iovec"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
 
-// maxIovs is the maximum number of iovecs to pass to the host.
-var maxIovs = linux.UIO_MAXIOV
-
 // copyToMulti copies as many bytes from src to dst as possible.
 func copyToMulti(dst [][]byte, src []byte) {
 	for _, d := range dst {
@@ -74,7 +71,7 @@ func buildIovec(bufs [][]byte, maxlen int64, truncate bool) (length int64, iovec
 		}
 	}
 
-	if iovsRequired > maxIovs {
+	if iovsRequired > iovec.MaxIovs {
 		// The kernel will reject our call if we pass this many iovs.
 		// Use a single intermediate buffer instead.
 		b := make([]byte, stopLen)
diff --git a/pkg/tcpip/link/fdbased/endpoint.go b/pkg/tcpip/link/fdbased/endpoint.go
index 32abe2a13..6aa1badc7 100644
--- a/pkg/tcpip/link/fdbased/endpoint.go
+++ b/pkg/tcpip/link/fdbased/endpoint.go
@@ -45,6 +45,7 @@ import (
 
 	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/pkg/binary"
+	"gvisor.dev/gvisor/pkg/iovec"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
@@ -406,6 +407,8 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.Ne
 		eth.Encode(ethHdr)
 	}
 
+	var builder iovec.Builder
+
 	fd := e.fds[pkt.Hash%uint32(len(e.fds))]
 	if e.Capabilities()&stack.CapabilityHardwareGSO != 0 {
 		vnetHdr := virtioNetHdr{}
@@ -430,29 +433,25 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.Ne
 		}
 
 		vnetHdrBuf := binary.Marshal(make([]byte, 0, virtioNetHdrSize), binary.LittleEndian, vnetHdr)
-		return rawfile.NonBlockingWrite3(fd, vnetHdrBuf, pkt.Header.View(), pkt.Data.ToView())
+		builder.Add(vnetHdrBuf)
 	}
 
-	if pkt.Data.Size() == 0 {
-		return rawfile.NonBlockingWrite(fd, pkt.Header.View())
-	}
-	if pkt.Header.UsedLength() == 0 {
-		return rawfile.NonBlockingWrite(fd, pkt.Data.ToView())
+	builder.Add(pkt.Header.View())
+	for _, v := range pkt.Data.Views() {
+		builder.Add(v)
 	}
 
-	return rawfile.NonBlockingWrite3(fd, pkt.Header.View(), pkt.Data.ToView(), nil)
+	return rawfile.NonBlockingWriteIovec(fd, builder.Build())
 }
 
 func (e *endpoint) sendBatch(batchFD int, batch []*stack.PacketBuffer) (int, *tcpip.Error) {
 	// Send a batch of packets through batchFD.
 	mmsgHdrs := make([]rawfile.MMsgHdr, 0, len(batch))
 	for _, pkt := range batch {
-		var ethHdrBuf []byte
-		iovLen := 0
+		var eth header.Ethernet
 		if e.hdrSize > 0 {
 			// Add ethernet header if needed.
-			ethHdrBuf = make([]byte, header.EthernetMinimumSize)
-			eth := header.Ethernet(ethHdrBuf)
+			eth = make(header.Ethernet, header.EthernetMinimumSize)
 			ethHdr := &header.EthernetFields{
 				DstAddr: pkt.EgressRoute.RemoteLinkAddress,
 				Type:    pkt.NetworkProtocolNumber,
@@ -465,12 +464,11 @@ func (e *endpoint) sendBatch(batchFD int, batch []*stack.PacketBuffer) (int, *tc
 				ethHdr.SrcAddr = e.addr
 			}
 			eth.Encode(ethHdr)
-			iovLen++
 		}
 
-		vnetHdr := virtioNetHdr{}
 		var vnetHdrBuf []byte
 		if e.Capabilities()&stack.CapabilityHardwareGSO != 0 {
+			vnetHdr := virtioNetHdr{}
 			if pkt.GSOOptions != nil {
 				vnetHdr.hdrLen = uint16(pkt.Header.UsedLength())
 				if pkt.GSOOptions.NeedsCsum {
@@ -491,45 +489,20 @@ func (e *endpoint) sendBatch(batchFD int, batch []*stack.PacketBuffer) (int, *tc
 				}
 			}
 			vnetHdrBuf = binary.Marshal(make([]byte, 0, virtioNetHdrSize), binary.LittleEndian, vnetHdr)
-			iovLen++
 		}
 
-		iovecs := make([]syscall.Iovec, iovLen+1+len(pkt.Data.Views()))
+		var builder iovec.Builder
+		builder.Add(vnetHdrBuf)
+		builder.Add(eth)
+		builder.Add(pkt.Header.View())
+		for _, v := range pkt.Data.Views() {
+			builder.Add(v)
+		}
+		iovecs := builder.Build()
+
 		var mmsgHdr rawfile.MMsgHdr
 		mmsgHdr.Msg.Iov = &iovecs[0]
-		iovecIdx := 0
-		if vnetHdrBuf != nil {
-			v := &iovecs[iovecIdx]
-			v.Base = &vnetHdrBuf[0]
-			v.Len = uint64(len(vnetHdrBuf))
-			iovecIdx++
-		}
-		if ethHdrBuf != nil {
-			v := &iovecs[iovecIdx]
-			v.Base = &ethHdrBuf[0]
-			v.Len = uint64(len(ethHdrBuf))
-			iovecIdx++
-		}
-		pktSize := uint64(0)
-		// Encode L3 Header
-		v := &iovecs[iovecIdx]
-		hdr := &pkt.Header
-		hdrView := hdr.View()
-		v.Base = &hdrView[0]
-		v.Len = uint64(len(hdrView))
-		pktSize += v.Len
-		iovecIdx++
-
-		// Now encode the Transport Payload.
-		pktViews := pkt.Data.Views()
-		for i := range pktViews {
-			vec := &iovecs[iovecIdx]
-			iovecIdx++
-			vec.Base = &pktViews[i][0]
-			vec.Len = uint64(len(pktViews[i]))
-			pktSize += vec.Len
-		}
-		mmsgHdr.Msg.Iovlen = uint64(iovecIdx)
+		mmsgHdr.Msg.Iovlen = uint64(len(iovecs))
 		mmsgHdrs = append(mmsgHdrs, mmsgHdr)
 	}
 
diff --git a/pkg/tcpip/link/rawfile/rawfile_unsafe.go b/pkg/tcpip/link/rawfile/rawfile_unsafe.go
index 69de6eb3e..f4c32c2da 100644
--- a/pkg/tcpip/link/rawfile/rawfile_unsafe.go
+++ b/pkg/tcpip/link/rawfile/rawfile_unsafe.go
@@ -66,38 +66,14 @@ func NonBlockingWrite(fd int, buf []byte) *tcpip.Error {
 	return nil
 }
 
-// NonBlockingWrite3 writes up to three byte slices to a file descriptor in a
-// single syscall. It fails if partial data is written.
-func NonBlockingWrite3(fd int, b1, b2, b3 []byte) *tcpip.Error {
-	// If there is no second and third buffer, issue a regular write.
-	if len(b2) == 0 && len(b3) == 0 {
-		return NonBlockingWrite(fd, b1)
-	}
-
-	// Build the iovec that represents them and issue a writev syscall.
-	iovec := [3]syscall.Iovec{
-		{
-			Base: &b1[0],
-			Len:  uint64(len(b1)),
-		},
-		{
-			Base: &b2[0],
-			Len:  uint64(len(b2)),
-		},
-	}
-	iovecLen := uintptr(2)
-
-	if len(b3) > 0 {
-		iovecLen++
-		iovec[2].Base = &b3[0]
-		iovec[2].Len = uint64(len(b3))
-	}
-
+// NonBlockingWriteIovec writes iovec to a file descriptor in a single syscall.
+// It fails if partial data is written.
+func NonBlockingWriteIovec(fd int, iovec []syscall.Iovec) *tcpip.Error {
+	iovecLen := uintptr(len(iovec))
 	_, _, e := syscall.RawSyscall(syscall.SYS_WRITEV, uintptr(fd), uintptr(unsafe.Pointer(&iovec[0])), iovecLen)
 	if e != 0 {
 		return TranslateErrno(e)
 	}
-
 	return nil
 }