12 files changed, 211 insertions, 53 deletions

diff --git a/pkg/sentry/fsimpl/host/control.go b/pkg/sentry/fsimpl/host/control.go
index b9082a20f..b9082a20f 100755..100644
--- a/pkg/sentry/fsimpl/host/control.go
+++ b/pkg/sentry/fsimpl/host/control.go
diff --git a/pkg/sentry/fsimpl/host/host.go b/pkg/sentry/fsimpl/host/host.go
index 8caf55a1b..18b127521 100755..100644
--- a/pkg/sentry/fsimpl/host/host.go
+++ b/pkg/sentry/fsimpl/host/host.go
@@ -86,15 +86,13 @@ func NewFD(ctx context.Context, mnt *vfs.Mount, hostFD int, opts *NewFDOptions)
 
 	i := &inode{
 		hostFD:     hostFD,
-		seekable:   seekable,
+		ino:        fs.NextIno(),
 		isTTY:      opts.IsTTY,
-		canMap:     canMap(uint32(fileType)),
 		wouldBlock: wouldBlock(uint32(fileType)),
-		ino:        fs.NextIno(),
-		// For simplicity, set offset to 0. Technically, we should use the existing
-		// offset on the host if the file is seekable.
-		offset: 0,
+		seekable:   seekable,
+		canMap:     canMap(uint32(fileType)),
 	}
+	i.pf.inode = i
 
 	// Non-seekable files can't be memory mapped, assert this.
 	if !i.seekable && i.canMap {
@@ -117,6 +115,10 @@ func NewFD(ctx context.Context, mnt *vfs.Mount, hostFD int, opts *NewFDOptions)
 
 	// i.open will take a reference on d.
 	defer d.DecRef()
+
+	// For simplicity, fileDescription.offset is set to 0. Technically, we
+	// should only set to 0 on files that are not seekable (sockets, pipes,
+	// etc.), and use the offset from the host fd otherwise when importing.
 	return i.open(ctx, d.VFSDentry(), mnt, flags)
 }
 
@@ -189,11 +191,15 @@ type inode struct {
 	// This field is initialized at creation time and is immutable.
 	hostFD int
 
-	// wouldBlock is true if the host FD would return EWOULDBLOCK for
-	// operations that would block.
+	// ino is an inode number unique within this filesystem.
 	//
 	// This field is initialized at creation time and is immutable.
-	wouldBlock bool
+	ino uint64
+
+	// isTTY is true if this file represents a TTY.
+	//
+	// This field is initialized at creation time and is immutable.
+	isTTY bool
 
 	// seekable is false if the host fd points to a file representing a stream,
 	// e.g. a socket or a pipe. Such files are not seekable and can return
@@ -202,29 +208,29 @@ type inode struct {
 	// This field is initialized at creation time and is immutable.
 	seekable bool
 
-	// isTTY is true if this file represents a TTY.
+	// wouldBlock is true if the host FD would return EWOULDBLOCK for
+	// operations that would block.
 	//
 	// This field is initialized at creation time and is immutable.
-	isTTY bool
+	wouldBlock bool
+
+	// Event queue for blocking operations.
+	queue waiter.Queue
 
 	// canMap specifies whether we allow the file to be memory mapped.
 	//
 	// This field is initialized at creation time and is immutable.
 	canMap bool
 
-	// ino is an inode number unique within this filesystem.
-	//
-	// This field is initialized at creation time and is immutable.
-	ino uint64
+	// mapsMu protects mappings.
+	mapsMu sync.Mutex
 
-	// offsetMu protects offset.
-	offsetMu sync.Mutex
-
-	// offset specifies the current file offset.
-	offset int64
+	// If canMap is true, mappings tracks mappings of hostFD into
+	// memmap.MappingSpaces.
+	mappings memmap.MappingSet
 
-	// Event queue for blocking operations.
-	queue waiter.Queue
+	// pf implements platform.File for mappings of hostFD.
+	pf inodePlatformFile
 }
 
 // CheckPermissions implements kernfs.Inode.
@@ -388,6 +394,21 @@ func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Cre
 		if err := syscall.Ftruncate(i.hostFD, int64(s.Size)); err != nil {
 			return err
 		}
+		oldSize := uint64(hostStat.Size)
+		if s.Size < oldSize {
+			oldpgend, _ := usermem.PageRoundUp(oldSize)
+			newpgend, _ := usermem.PageRoundUp(s.Size)
+			if oldpgend != newpgend {
+				i.mapsMu.Lock()
+				i.mappings.Invalidate(memmap.MappableRange{newpgend, oldpgend}, memmap.InvalidateOpts{
+					// Compare Linux's mm/truncate.c:truncate_setsize() =>
+					// truncate_pagecache() =>
+					// mm/memory.c:unmap_mapping_range(evencows=1).
+					InvalidatePrivate: true,
+				})
+				i.mapsMu.Unlock()
+			}
+		}
 	}
 	if m&(linux.STATX_ATIME|linux.STATX_MTIME) != 0 {
 		ts := [2]syscall.Timespec{
@@ -464,9 +485,6 @@ func (i *inode) open(ctx context.Context, d *vfs.Dentry, mnt *vfs.Mount, flags u
 		return vfsfd, nil
 	}
 
-	// For simplicity, set offset to 0. Technically, we should
-	// only set to 0 on files that are not seekable (sockets, pipes, etc.),
-	// and use the offset from the host fd otherwise.
 	fd := &fileDescription{inode: i}
 	vfsfd := &fd.vfsfd
 	if err := vfsfd.Init(fd, flags, mnt, d, &vfs.FileDescriptionOptions{}); err != nil {
@@ -487,6 +505,13 @@ type fileDescription struct {
 	//
 	// inode is immutable after fileDescription creation.
 	inode *inode
+
+	// offsetMu protects offset.
+	offsetMu sync.Mutex
+
+	// offset specifies the current file offset. It is only meaningful when
+	// inode.seekable is true.
+	offset int64
 }
 
 // SetStat implements vfs.FileDescriptionImpl.
@@ -532,10 +557,10 @@ func (f *fileDescription) Read(ctx context.Context, dst usermem.IOSequence, opts
 		return n, err
 	}
 	// TODO(gvisor.dev/issue/1672): Cache pages, when forced to do so.
-	i.offsetMu.Lock()
-	n, err := readFromHostFD(ctx, i.hostFD, dst, i.offset, opts.Flags)
-	i.offset += n
-	i.offsetMu.Unlock()
+	f.offsetMu.Lock()
+	n, err := readFromHostFD(ctx, i.hostFD, dst, f.offset, opts.Flags)
+	f.offset += n
+	f.offsetMu.Unlock()
 	return n, err
 }
 
@@ -572,10 +597,10 @@ func (f *fileDescription) Write(ctx context.Context, src usermem.IOSequence, opt
 	}
 	// TODO(gvisor.dev/issue/1672): Cache pages, when forced to do so.
 	// TODO(gvisor.dev/issue/1672): Write to end of file and update offset if O_APPEND is set on this file.
-	i.offsetMu.Lock()
-	n, err := writeToHostFD(ctx, i.hostFD, src, i.offset, opts.Flags)
-	i.offset += n
-	i.offsetMu.Unlock()
+	f.offsetMu.Lock()
+	n, err := writeToHostFD(ctx, i.hostFD, src, f.offset, opts.Flags)
+	f.offset += n
+	f.offsetMu.Unlock()
 	return n, err
 }
 
@@ -600,41 +625,41 @@ func (f *fileDescription) Seek(_ context.Context, offset int64, whence int32) (i
 		return 0, syserror.ESPIPE
 	}
 
-	i.offsetMu.Lock()
-	defer i.offsetMu.Unlock()
+	f.offsetMu.Lock()
+	defer f.offsetMu.Unlock()
 
 	switch whence {
 	case linux.SEEK_SET:
 		if offset < 0 {
-			return i.offset, syserror.EINVAL
+			return f.offset, syserror.EINVAL
 		}
-		i.offset = offset
+		f.offset = offset
 
 	case linux.SEEK_CUR:
-		// Check for overflow. Note that underflow cannot occur, since i.offset >= 0.
-		if offset > math.MaxInt64-i.offset {
-			return i.offset, syserror.EOVERFLOW
+		// Check for overflow. Note that underflow cannot occur, since f.offset >= 0.
+		if offset > math.MaxInt64-f.offset {
+			return f.offset, syserror.EOVERFLOW
 		}
-		if i.offset+offset < 0 {
-			return i.offset, syserror.EINVAL
+		if f.offset+offset < 0 {
+			return f.offset, syserror.EINVAL
 		}
-		i.offset += offset
+		f.offset += offset
 
 	case linux.SEEK_END:
 		var s syscall.Stat_t
 		if err := syscall.Fstat(i.hostFD, &s); err != nil {
-			return i.offset, err
+			return f.offset, err
 		}
 		size := s.Size
 
 		// Check for overflow. Note that underflow cannot occur, since size >= 0.
 		if offset > math.MaxInt64-size {
-			return i.offset, syserror.EOVERFLOW
+			return f.offset, syserror.EOVERFLOW
 		}
 		if size+offset < 0 {
-			return i.offset, syserror.EINVAL
+			return f.offset, syserror.EINVAL
 		}
-		i.offset = size + offset
+		f.offset = size + offset
 
 	case linux.SEEK_DATA, linux.SEEK_HOLE:
 		// Modifying the offset in the host file table should not matter, since
@@ -643,16 +668,16 @@ func (f *fileDescription) Seek(_ context.Context, offset int64, whence int32) (i
 		// For reading and writing, we always rely on our internal offset.
 		n, err := unix.Seek(i.hostFD, offset, int(whence))
 		if err != nil {
-			return i.offset, err
+			return f.offset, err
 		}
-		i.offset = n
+		f.offset = n
 
 	default:
 		// Invalid whence.
-		return i.offset, syserror.EINVAL
+		return f.offset, syserror.EINVAL
 	}
 
-	return i.offset, nil
+	return f.offset, nil
 }
 
 // Sync implements FileDescriptionImpl.
@@ -666,8 +691,9 @@ func (f *fileDescription) ConfigureMMap(_ context.Context, opts *memmap.MMapOpts
 	if !f.inode.canMap {
 		return syserror.ENODEV
 	}
-	// TODO(gvisor.dev/issue/1672): Implement ConfigureMMap and Mappable interface.
-	return syserror.ENODEV
+	i := f.inode
+	i.pf.fileMapperInitOnce.Do(i.pf.fileMapper.Init)
+	return vfs.GenericConfigureMMap(&f.vfsfd, i, opts)
 }
 
 // EventRegister implements waiter.Waitable.EventRegister.
diff --git a/pkg/sentry/fsimpl/host/host_state_autogen.go b/pkg/sentry/fsimpl/host/host_state_autogen.go
index 28bc79d04..28bc79d04 100755..100644
--- a/pkg/sentry/fsimpl/host/host_state_autogen.go
+++ b/pkg/sentry/fsimpl/host/host_state_autogen.go
diff --git a/pkg/sentry/fsimpl/host/host_unsafe_state_autogen.go b/pkg/sentry/fsimpl/host/host_unsafe_state_autogen.go
index b2d8c661f..b2d8c661f 100755..100644
--- a/pkg/sentry/fsimpl/host/host_unsafe_state_autogen.go
+++ b/pkg/sentry/fsimpl/host/host_unsafe_state_autogen.go
diff --git a/pkg/sentry/fsimpl/host/ioctl_unsafe.go b/pkg/sentry/fsimpl/host/ioctl_unsafe.go
index 0983bf7d8..0983bf7d8 100755..100644
--- a/pkg/sentry/fsimpl/host/ioctl_unsafe.go
+++ b/pkg/sentry/fsimpl/host/ioctl_unsafe.go
diff --git a/pkg/sentry/fsimpl/host/mmap.go b/pkg/sentry/fsimpl/host/mmap.go
new file mode 100644
index 000000000..8545a82f0
--- /dev/null
+++ b/pkg/sentry/fsimpl/host/mmap.go
@@ -0,0 +1,132 @@
+// 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.
+
+package host
+
+import (
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/safemem"
+	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
+	"gvisor.dev/gvisor/pkg/sentry/memmap"
+	"gvisor.dev/gvisor/pkg/sentry/platform"
+	"gvisor.dev/gvisor/pkg/sync"
+	"gvisor.dev/gvisor/pkg/usermem"
+)
+
+// inodePlatformFile implements platform.File. It exists solely because inode
+// cannot implement both kernfs.Inode.IncRef and platform.File.IncRef.
+//
+// inodePlatformFile should only be used if inode.canMap is true.
+type inodePlatformFile struct {
+	*inode
+
+	// fdRefsMu protects fdRefs.
+	fdRefsMu sync.Mutex
+
+	// fdRefs counts references on platform.File offsets. It is used solely for
+	// memory accounting.
+	fdRefs fsutil.FrameRefSet
+
+	// fileMapper caches mappings of the host file represented by this inode.
+	fileMapper fsutil.HostFileMapper
+
+	// fileMapperInitOnce is used to lazily initialize fileMapper.
+	fileMapperInitOnce sync.Once
+}
+
+// IncRef implements platform.File.IncRef.
+//
+// Precondition: i.inode.canMap must be true.
+func (i *inodePlatformFile) IncRef(fr platform.FileRange) {
+	i.fdRefsMu.Lock()
+	i.fdRefs.IncRefAndAccount(fr)
+	i.fdRefsMu.Unlock()
+}
+
+// DecRef implements platform.File.DecRef.
+//
+// Precondition: i.inode.canMap must be true.
+func (i *inodePlatformFile) DecRef(fr platform.FileRange) {
+	i.fdRefsMu.Lock()
+	i.fdRefs.DecRefAndAccount(fr)
+	i.fdRefsMu.Unlock()
+}
+
+// MapInternal implements platform.File.MapInternal.
+//
+// Precondition: i.inode.canMap must be true.
+func (i *inodePlatformFile) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
+	return i.fileMapper.MapInternal(fr, i.hostFD, at.Write)
+}
+
+// FD implements platform.File.FD.
+func (i *inodePlatformFile) FD() int {
+	return i.hostFD
+}
+
+// AddMapping implements memmap.Mappable.AddMapping.
+//
+// Precondition: i.inode.canMap must be true.
+func (i *inode) AddMapping(ctx context.Context, ms memmap.MappingSpace, ar usermem.AddrRange, offset uint64, writable bool) error {
+	i.mapsMu.Lock()
+	mapped := i.mappings.AddMapping(ms, ar, offset, writable)
+	for _, r := range mapped {
+		i.pf.fileMapper.IncRefOn(r)
+	}
+	i.mapsMu.Unlock()
+	return nil
+}
+
+// RemoveMapping implements memmap.Mappable.RemoveMapping.
+//
+// Precondition: i.inode.canMap must be true.
+func (i *inode) RemoveMapping(ctx context.Context, ms memmap.MappingSpace, ar usermem.AddrRange, offset uint64, writable bool) {
+	i.mapsMu.Lock()
+	unmapped := i.mappings.RemoveMapping(ms, ar, offset, writable)
+	for _, r := range unmapped {
+		i.pf.fileMapper.DecRefOn(r)
+	}
+	i.mapsMu.Unlock()
+}
+
+// CopyMapping implements memmap.Mappable.CopyMapping.
+//
+// Precondition: i.inode.canMap must be true.
+func (i *inode) CopyMapping(ctx context.Context, ms memmap.MappingSpace, srcAR, dstAR usermem.AddrRange, offset uint64, writable bool) error {
+	return i.AddMapping(ctx, ms, dstAR, offset, writable)
+}
+
+// Translate implements memmap.Mappable.Translate.
+//
+// Precondition: i.inode.canMap must be true.
+func (i *inode) Translate(ctx context.Context, required, optional memmap.MappableRange, at usermem.AccessType) ([]memmap.Translation, error) {
+	mr := optional
+	return []memmap.Translation{
+		{
+			Source: mr,
+			File:   &i.pf,
+			Offset: mr.Start,
+			Perms:  usermem.AnyAccess,
+		},
+	}, nil
+}
+
+// InvalidateUnsavable implements memmap.Mappable.InvalidateUnsavable.
+//
+// Precondition: i.inode.canMap must be true.
+func (i *inode) InvalidateUnsavable(ctx context.Context) error {
+	// We expect the same host fd across save/restore, so all translations
+	// should be valid.
+	return nil
+}
diff --git a/pkg/sentry/fsimpl/host/socket.go b/pkg/sentry/fsimpl/host/socket.go
index 38f1fbfba..38f1fbfba 100755..100644
--- a/pkg/sentry/fsimpl/host/socket.go
+++ b/pkg/sentry/fsimpl/host/socket.go
diff --git a/pkg/sentry/fsimpl/host/socket_iovec.go b/pkg/sentry/fsimpl/host/socket_iovec.go
index 584c247d2..584c247d2 100755..100644
--- a/pkg/sentry/fsimpl/host/socket_iovec.go
+++ b/pkg/sentry/fsimpl/host/socket_iovec.go
diff --git a/pkg/sentry/fsimpl/host/socket_unsafe.go b/pkg/sentry/fsimpl/host/socket_unsafe.go
index 35ded24bc..35ded24bc 100755..100644
--- a/pkg/sentry/fsimpl/host/socket_unsafe.go
+++ b/pkg/sentry/fsimpl/host/socket_unsafe.go
diff --git a/pkg/sentry/fsimpl/host/tty.go b/pkg/sentry/fsimpl/host/tty.go
index 68af6e5af..68af6e5af 100755..100644
--- a/pkg/sentry/fsimpl/host/tty.go
+++ b/pkg/sentry/fsimpl/host/tty.go
diff --git a/pkg/sentry/fsimpl/host/util.go b/pkg/sentry/fsimpl/host/util.go
index 2bc757b1a..2bc757b1a 100755..100644
--- a/pkg/sentry/fsimpl/host/util.go
+++ b/pkg/sentry/fsimpl/host/util.go
diff --git a/pkg/sentry/fsimpl/host/util_unsafe.go b/pkg/sentry/fsimpl/host/util_unsafe.go
index 5136ac844..5136ac844 100755..100644
--- a/pkg/sentry/fsimpl/host/util_unsafe.go
+++ b/pkg/sentry/fsimpl/host/util_unsafe.go