Fixes for procfs

- Return ENOENT for /proc/[pid]/task if task is zoombied or terminated
- Allow directory to be Seek() to the end
- Construct synthetic files for /proc/[pid]/ns/*
- Changed GenericDirectoryFD.Init to not register with FileDescription,
  otherwise other implementation cannot change behavior.

Updates #1195,1193

PiperOrigin-RevId: 308294649

1 files changed, 9 insertions, 5 deletions

diff --git a/pkg/sentry/fsimpl/proc/task_fds.go b/pkg/sentry/fsimpl/proc/task_fds.go
index 046265eca..a7622f1b6 100644
--- a/pkg/sentry/fsimpl/proc/task_fds.go
+++ b/pkg/sentry/fsimpl/proc/task_fds.go
@@ -143,8 +143,10 @@ func (i *fdDirInode) Lookup(ctx context.Context, name string) (*vfs.Dentry, erro
 
 // Open implements kernfs.Inode.
 func (i *fdDirInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
-	fd := &kernfs.GenericDirectoryFD{}
-	fd.Init(rp.Mount(), vfsd, &i.OrderedChildren, &opts)
+	fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts)
+	if err != nil {
+		return nil, err
+	}
 	return fd.VFSFileDescription(), nil
 }
 
@@ -207,7 +209,7 @@ func (s *fdSymlink) Readlink(ctx context.Context) (string, error) {
 	return s.task.Kernel().VFS().PathnameWithDeleted(ctx, root, file.VirtualDentry())
 }
 
-func (s *fdSymlink) Getlink(ctx context.Context) (vfs.VirtualDentry, string, error) {
+func (s *fdSymlink) Getlink(ctx context.Context, mnt *vfs.Mount) (vfs.VirtualDentry, string, error) {
 	file, _ := getTaskFD(s.task, s.fd)
 	if file == nil {
 		return vfs.VirtualDentry{}, "", syserror.ENOENT
@@ -268,8 +270,10 @@ func (i *fdInfoDirInode) Lookup(ctx context.Context, name string) (*vfs.Dentry,
 
 // Open implements kernfs.Inode.
 func (i *fdInfoDirInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
-	fd := &kernfs.GenericDirectoryFD{}
-	fd.Init(rp.Mount(), vfsd, &i.OrderedChildren, &opts)
+	fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts)
+	if err != nil {
+		return nil, err
+	}
 	return fd.VFSFileDescription(), nil
 }