5 files changed, 118 insertions, 7 deletions
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index 131da332f..850482a19 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -1039,6 +1039,18 @@ func (d *dentry) decRefLocked() {
 	}
 }
 
+// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
+//
+// TODO(gvisor.dev/issue/1479): Implement inotify.
+func (d *dentry) InotifyWithParent(events uint32, cookie uint32) {}
+
+// Watches implements vfs.DentryImpl.Watches.
+//
+// TODO(gvisor.dev/issue/1479): Implement inotify.
+func (d *dentry) Watches() *vfs.Watches {
+	return nil
+}
+
 // checkCachingLocked should be called after d's reference count becomes 0 or it
 // becomes disowned.
 //
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go
index a83151ad3..682545994 100644
--- a/pkg/sentry/fsimpl/kernfs/kernfs.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs.go
@@ -225,6 +225,18 @@ func (d *Dentry) destroy() {
 	}
 }
 
+// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
+//
+// TODO(gvisor.dev/issue/1479): Implement inotify.
+func (d *Dentry) InotifyWithParent(events uint32, cookie uint32) {}
+
+// Watches implements vfs.DentryImpl.Watches.
+//
+// TODO(gvisor.dev/issue/1479): Implement inotify.
+func (d *Dentry) Watches() *vfs.Watches {
+	return nil
+}
+
 // InsertChild inserts child into the vfs dentry cache with the given name under
 // this dentry. This does not update the directory inode, so calling this on
 // it's own isn't sufficient to insert a child into a directory. InsertChild
diff --git a/pkg/sentry/fsimpl/tmpfs/directory.go b/pkg/sentry/fsimpl/tmpfs/directory.go
index f2399981b..8bc475f88 100644
--- a/pkg/sentry/fsimpl/tmpfs/directory.go
+++ b/pkg/sentry/fsimpl/tmpfs/directory.go
@@ -112,6 +112,7 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba
 	dir.iterMu.Lock()
 	defer dir.iterMu.Unlock()
 
+	fd.dentry().InotifyWithParent(linux.IN_ACCESS, 0)
 	fd.inode().touchAtime(fd.vfsfd.Mount())
 
 	if fd.off == 0 {
diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go
index 7c04570f1..b4159f904 100644
--- a/pkg/sentry/fsimpl/tmpfs/filesystem.go
+++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go
@@ -177,6 +177,12 @@ func (fs *filesystem) doCreateAt(rp *vfs.ResolvingPath, dir bool, create func(pa
 	if err := create(parentDir, name); err != nil {
 		return err
 	}
+
+	ev := linux.IN_CREATE
+	if dir {
+		ev |= linux.IN_ISDIR
+	}
+	parentDir.inode.watches.Notify(name, uint32(ev), 0)
 	parentDir.inode.touchCMtime()
 	return nil
 }
@@ -241,6 +247,7 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.
 			return syserror.EMLINK
 		}
 		d.inode.incLinksLocked()
+		d.inode.watches.Notify("", linux.IN_ATTRIB, 0)
 		parentDir.insertChildLocked(fs.newDentry(d.inode), name)
 		return nil
 	})
@@ -354,6 +361,7 @@ afterTrailingSymlink:
 		if err != nil {
 			return nil, err
 		}
+		parentDir.inode.watches.Notify(name, linux.IN_CREATE, 0)
 		parentDir.inode.touchCMtime()
 		return fd, nil
 	}
@@ -559,6 +567,8 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 		newParentDir.inode.touchCMtime()
 	}
 	renamed.inode.touchCtime()
+
+	vfs.InotifyRename(ctx, &renamed.inode.watches, &oldParentDir.inode.watches, &newParentDir.inode.watches, oldName, newName, renamed.inode.isDir())
 	return nil
 }
 
@@ -603,6 +613,7 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
 		return err
 	}
 	parentDir.removeChildLocked(child)
+	parentDir.inode.watches.Notify(name, linux.IN_DELETE|linux.IN_ISDIR, 0)
 	// Remove links for child, child/., and child/..
 	child.inode.decLinksLocked()
 	child.inode.decLinksLocked()
@@ -620,7 +631,14 @@ func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts
 	if err != nil {
 		return err
 	}
-	return d.inode.setStat(ctx, rp.Credentials(), &opts.Stat)
+	if err := d.inode.setStat(ctx, rp.Credentials(), &opts.Stat); err != nil {
+		return err
+	}
+
+	if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 {
+		d.InotifyWithParent(ev, 0)
+	}
+	return nil
 }
 
 // StatAt implements vfs.FilesystemImpl.StatAt.
@@ -700,6 +718,12 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error
 	if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil {
 		return err
 	}
+
+	// Generate inotify events. Note that this must take place before the link
+	// count of the child is decremented, or else the watches may be dropped
+	// before these events are added.
+	vfs.InotifyRemoveChild(&child.inode.watches, &parentDir.inode.watches, name)
+
 	parentDir.removeChildLocked(child)
 	child.inode.decLinksLocked()
 	vfsObj.CommitDeleteDentry(&child.vfsd)
@@ -756,7 +780,12 @@ func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt
 	if err != nil {
 		return err
 	}
-	return d.inode.setxattr(rp.Credentials(), &opts)
+	if err := d.inode.setxattr(rp.Credentials(), &opts); err != nil {
+		return err
+	}
+
+	d.InotifyWithParent(linux.IN_ATTRIB, 0)
+	return nil
 }
 
 // RemovexattrAt implements vfs.FilesystemImpl.RemovexattrAt.
@@ -767,7 +796,12 @@ func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath,
 	if err != nil {
 		return err
 	}
-	return d.inode.removexattr(rp.Credentials(), name)
+	if err := d.inode.removexattr(rp.Credentials(), name); err != nil {
+		return err
+	}
+
+	d.InotifyWithParent(linux.IN_ATTRIB, 0)
+	return nil
 }
 
 // PrependPath implements vfs.FilesystemImpl.PrependPath.
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index b739095b7..1d83b6840 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -201,6 +201,26 @@ func (d *dentry) DecRef() {
 	d.inode.decRef()
 }
 
+// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
+func (d *dentry) InotifyWithParent(events uint32, cookie uint32) {
+	if d.inode.isDir() {
+		events |= linux.IN_ISDIR
+	}
+
+	// The ordering below is important, Linux always notifies the parent first.
+	if d.parent != nil {
+		// Note that d.parent or d.name may be stale if there is a concurrent
+		// rename operation. Inotify does not provide consistency guarantees.
+		d.parent.inode.watches.Notify(d.name, events, cookie)
+	}
+	d.inode.watches.Notify("", events, cookie)
+}
+
+// Watches implements vfs.DentryImpl.Watches.
+func (d *dentry) Watches() *vfs.Watches {
+	return &d.inode.watches
+}
+
 // inode represents a filesystem object.
 type inode struct {
 	// fs is the owning filesystem. fs is immutable.
@@ -236,6 +256,9 @@ type inode struct {
 	// Advisory file locks, which lock at the inode level.
 	locks lock.FileLocks
 
+	// Inotify watches for this inode.
+	watches vfs.Watches
+
 	impl interface{} // immutable
 }
 
@@ -257,6 +280,7 @@ func (i *inode) init(impl interface{}, fs *filesystem, creds *auth.Credentials,
 	i.ctime = now
 	i.mtime = now
 	// i.nlink initialized by caller
+	i.watches = vfs.Watches{}
 	i.impl = impl
 }
 
@@ -307,6 +331,7 @@ func (i *inode) tryIncRef() bool {
 
 func (i *inode) decRef() {
 	if refs := atomic.AddInt64(&i.refs, -1); refs == 0 {
+		i.watches.HandleDeletion()
 		if regFile, ok := i.impl.(*regularFile); ok {
 			// Release memory used by regFile to store data. Since regFile is
 			// no longer usable, we don't need to grab any locks or update any
@@ -628,8 +653,12 @@ func (fd *fileDescription) filesystem() *filesystem {
 	return fd.vfsfd.Mount().Filesystem().Impl().(*filesystem)
 }
 
+func (fd *fileDescription) dentry() *dentry {
+	return fd.vfsfd.Dentry().Impl().(*dentry)
+}
+
 func (fd *fileDescription) inode() *inode {
-	return fd.vfsfd.Dentry().Impl().(*dentry).inode
+	return fd.dentry().inode
 }
 
 // Stat implements vfs.FileDescriptionImpl.Stat.
@@ -642,7 +671,16 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu
 // SetStat implements vfs.FileDescriptionImpl.SetStat.
 func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
 	creds := auth.CredentialsFromContext(ctx)
-	return fd.inode().setStat(ctx, creds, &opts.Stat)
+	d := fd.dentry()
+	if err := d.inode.setStat(ctx, creds, &opts.Stat); err != nil {
+		return err
+	}
+
+	// Generate inotify events.
+	if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 {
+		d.InotifyWithParent(ev, 0)
+	}
+	return nil
 }
 
 // Listxattr implements vfs.FileDescriptionImpl.Listxattr.
@@ -657,12 +695,26 @@ func (fd *fileDescription) Getxattr(ctx context.Context, opts vfs.GetxattrOption
 
 // Setxattr implements vfs.FileDescriptionImpl.Setxattr.
 func (fd *fileDescription) Setxattr(ctx context.Context, opts vfs.SetxattrOptions) error {
-	return fd.inode().setxattr(auth.CredentialsFromContext(ctx), &opts)
+	d := fd.dentry()
+	if err := d.inode.setxattr(auth.CredentialsFromContext(ctx), &opts); err != nil {
+		return err
+	}
+
+	// Generate inotify events.
+	d.InotifyWithParent(linux.IN_ATTRIB, 0)
+	return nil
 }
 
 // Removexattr implements vfs.FileDescriptionImpl.Removexattr.
 func (fd *fileDescription) Removexattr(ctx context.Context, name string) error {
-	return fd.inode().removexattr(auth.CredentialsFromContext(ctx), name)
+	d := fd.dentry()
+	if err := d.inode.removexattr(auth.CredentialsFromContext(ctx), name); err != nil {
+		return err
+	}
+
+	// Generate inotify events.
+	d.InotifyWithParent(linux.IN_ATTRIB, 0)
+	return nil
 }
 
 // NewMemfd creates a new tmpfs regular file and file description that can back