Merge release-20200921.0-71-g4a428b13b (automated)

2 files changed, 71 insertions, 0 deletions

diff --git a/pkg/sentry/fs/proc/proc_state_autogen.go b/pkg/sentry/fs/proc/proc_state_autogen.go
index f7f65fa43..de5e7de5e 100644
--- a/pkg/sentry/fs/proc/proc_state_autogen.go
+++ b/pkg/sentry/fs/proc/proc_state_autogen.go
@@ -1037,6 +1037,32 @@ func (x *exe) StateLoad(m state.Source) {
 	m.Load(1, &x.t)
 }
 
+func (x *cwd) StateTypeName() string {
+	return "pkg/sentry/fs/proc.cwd"
+}
+
+func (x *cwd) StateFields() []string {
+	return []string{
+		"Symlink",
+		"t",
+	}
+}
+
+func (x *cwd) beforeSave() {}
+
+func (x *cwd) StateSave(m state.Sink) {
+	x.beforeSave()
+	m.Save(0, &x.Symlink)
+	m.Save(1, &x.t)
+}
+
+func (x *cwd) afterLoad() {}
+
+func (x *cwd) StateLoad(m state.Source) {
+	m.Load(0, &x.Symlink)
+	m.Load(1, &x.t)
+}
+
 func (x *namespaceSymlink) StateTypeName() string {
 	return "pkg/sentry/fs/proc.namespaceSymlink"
 }
@@ -1527,6 +1553,7 @@ func init() {
 	state.Register((*subtasks)(nil))
 	state.Register((*subtasksFile)(nil))
 	state.Register((*exe)(nil))
+	state.Register((*cwd)(nil))
 	state.Register((*namespaceSymlink)(nil))
 	state.Register((*mapsData)(nil))
 	state.Register((*smapsData)(nil))
diff --git a/pkg/sentry/fs/proc/task.go b/pkg/sentry/fs/proc/task.go
index 103bfc600..22d658acf 100644
--- a/pkg/sentry/fs/proc/task.go
+++ b/pkg/sentry/fs/proc/task.go
@@ -84,6 +84,7 @@ func (p *proc) newTaskDir(t *kernel.Task, msrc *fs.MountSource, isThreadGroup bo
 		"auxv":          newAuxvec(t, msrc),
 		"cmdline":       newExecArgInode(t, msrc, cmdlineExecArg),
 		"comm":          newComm(t, msrc),
+		"cwd":           newCwd(t, msrc),
 		"environ":       newExecArgInode(t, msrc, environExecArg),
 		"exe":           newExe(t, msrc),
 		"fd":            newFdDir(t, msrc),
@@ -300,6 +301,49 @@ func (e *exe) Readlink(ctx context.Context, inode *fs.Inode) (string, error) {
 	return exec.PathnameWithDeleted(ctx), nil
 }
 
+// cwd is an fs.InodeOperations symlink for the /proc/PID/cwd file.
+//
+// +stateify savable
+type cwd struct {
+	ramfs.Symlink
+
+	t *kernel.Task
+}
+
+func newCwd(t *kernel.Task, msrc *fs.MountSource) *fs.Inode {
+	cwdSymlink := &cwd{
+		Symlink: *ramfs.NewSymlink(t, fs.RootOwner, ""),
+		t:       t,
+	}
+	return newProcInode(t, cwdSymlink, msrc, fs.Symlink, t)
+}
+
+// Readlink implements fs.InodeOperations.
+func (e *cwd) Readlink(ctx context.Context, inode *fs.Inode) (string, error) {
+	if !kernel.ContextCanTrace(ctx, e.t, false) {
+		return "", syserror.EACCES
+	}
+	if err := checkTaskState(e.t); err != nil {
+		return "", err
+	}
+	cwd := e.t.FSContext().WorkingDirectory()
+	if cwd == nil {
+		// It could have raced with process deletion.
+		return "", syserror.ESRCH
+	}
+	defer cwd.DecRef(ctx)
+
+	root := fs.RootFromContext(ctx)
+	if root == nil {
+		// It could have raced with process deletion.
+		return "", syserror.ESRCH
+	}
+	defer root.DecRef(ctx)
+
+	name, _ := cwd.FullName(root)
+	return name, nil
+}
+
 // namespaceSymlink represents a symlink in the namespacefs, such as the files
 // in /proc/<pid>/ns.
 //