From 4feb5c7c263de2310608d1a0e608d4ffd5e2990f Mon Sep 17 00:00:00 2001
From: Dean Deng <deandeng@google.com>
Date: Sat, 24 Oct 2020 07:46:30 -0700
Subject: Add leak checking to vfs2 structures that cannot use the refs_vfs2
 template.

Updates #1486.

PiperOrigin-RevId: 338832085
---
 pkg/sentry/fsimpl/overlay/BUILD           |  2 ++
 pkg/sentry/fsimpl/overlay/overlay.go      | 13 +++++++++++++
 pkg/sentry/fsimpl/overlay/save_restore.go | 27 +++++++++++++++++++++++++++
 3 files changed, 42 insertions(+)
 create mode 100644 pkg/sentry/fsimpl/overlay/save_restore.go

(limited to 'pkg/sentry/fsimpl/overlay')

diff --git a/pkg/sentry/fsimpl/overlay/BUILD b/pkg/sentry/fsimpl/overlay/BUILD
index 1e11b0428..fd6c55921 100644
--- a/pkg/sentry/fsimpl/overlay/BUILD
+++ b/pkg/sentry/fsimpl/overlay/BUILD
@@ -23,6 +23,7 @@ go_library(
         "fstree.go",
         "overlay.go",
         "regular_file.go",
+        "save_restore.go",
     ],
     visibility = ["//pkg/sentry:internal"],
     deps = [
@@ -30,6 +31,7 @@ go_library(
         "//pkg/context",
         "//pkg/fspath",
         "//pkg/log",
+        "//pkg/refsvfs2",
         "//pkg/sentry/arch",
         "//pkg/sentry/fs/lock",
         "//pkg/sentry/kernel/auth",
diff --git a/pkg/sentry/fsimpl/overlay/overlay.go b/pkg/sentry/fsimpl/overlay/overlay.go
index f28411b5b..6fe97c57b 100644
--- a/pkg/sentry/fsimpl/overlay/overlay.go
+++ b/pkg/sentry/fsimpl/overlay/overlay.go
@@ -33,12 +33,14 @@
 package overlay
 
 import (
+	"fmt"
 	"strings"
 	"sync/atomic"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/fspath"
+	"gvisor.dev/gvisor/pkg/refsvfs2"
 	fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
@@ -484,6 +486,9 @@ func (fs *filesystem) newDentry() *dentry {
 	}
 	d.lowerVDs = d.inlineLowerVDs[:0]
 	d.vfsd.Init(d)
+	if refsvfs2.LeakCheckEnabled() {
+		refsvfs2.Register(d, "overlay.dentry")
+	}
 	return d
 }
 
@@ -583,6 +588,14 @@ func (d *dentry) destroyLocked(ctx context.Context) {
 			panic("overlay.dentry.DecRef() called without holding a reference")
 		}
 	}
+	if refsvfs2.LeakCheckEnabled() {
+		refsvfs2.Unregister(d, "overlay.dentry")
+	}
+}
+
+// LeakMessage implements refsvfs2.CheckedObject.LeakMessage.
+func (d *dentry) LeakMessage() string {
+	return fmt.Sprintf("[overlay.dentry %p] reference count of %d instead of -1", d, atomic.LoadInt64(&d.refs))
 }
 
 // InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
diff --git a/pkg/sentry/fsimpl/overlay/save_restore.go b/pkg/sentry/fsimpl/overlay/save_restore.go
new file mode 100644
index 000000000..054e17b17
--- /dev/null
+++ b/pkg/sentry/fsimpl/overlay/save_restore.go
@@ -0,0 +1,27 @@
+// 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 overlay
+
+import (
+	"sync/atomic"
+
+	"gvisor.dev/gvisor/pkg/refsvfs2"
+)
+
+func (d *dentry) afterLoad() {
+	if refsvfs2.LeakCheckEnabled() && atomic.LoadInt64(&d.refs) != -1 {
+		refsvfs2.Register(d, "overlay.dentry")
+	}
+}
-- 
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