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-rw-r--r--pkg/sentry/control/proc.go4
-rw-r--r--pkg/sentry/fs/user/path.go1
-rw-r--r--pkg/sentry/fs/user/user.go1
-rw-r--r--pkg/sentry/fsimpl/devtmpfs/devtmpfs.go5
-rw-r--r--pkg/sentry/kernel/kernel.go29
-rw-r--r--pkg/sentry/kernel/task.go2
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/execve.go3
-rw-r--r--pkg/sentry/vfs/mount.go4
8 files changed, 25 insertions, 24 deletions
diff --git a/pkg/sentry/control/proc.go b/pkg/sentry/control/proc.go
index 668f47802..1d88db12f 100644
--- a/pkg/sentry/control/proc.go
+++ b/pkg/sentry/control/proc.go
@@ -183,9 +183,9 @@ func (proc *Proc) execAsync(args *ExecArgs) (*kernel.ThreadGroup, kernel.ThreadI
if initArgs.MountNamespaceVFS2 == nil {
// Set initArgs so that 'ctx' returns the namespace.
//
- // MountNamespaceVFS2 adds a reference to the namespace, which is
- // transferred to the new process.
+ // Add a reference to the namespace, which is transferred to the new process.
initArgs.MountNamespaceVFS2 = proc.Kernel.GlobalInit().Leader().MountNamespaceVFS2()
+ initArgs.MountNamespaceVFS2.IncRef()
}
} else {
if initArgs.MountNamespace == nil {
diff --git a/pkg/sentry/fs/user/path.go b/pkg/sentry/fs/user/path.go
index 2f5a43b84..124bc95ed 100644
--- a/pkg/sentry/fs/user/path.go
+++ b/pkg/sentry/fs/user/path.go
@@ -121,6 +121,7 @@ func resolve(ctx context.Context, mns *fs.MountNamespace, paths []string, name s
func resolveVFS2(ctx context.Context, creds *auth.Credentials, mns *vfs.MountNamespace, paths []string, name string) (string, error) {
root := mns.Root()
+ root.IncRef()
defer root.DecRef(ctx)
for _, p := range paths {
if !path.IsAbs(p) {
diff --git a/pkg/sentry/fs/user/user.go b/pkg/sentry/fs/user/user.go
index 936fd3932..1f8684dc6 100644
--- a/pkg/sentry/fs/user/user.go
+++ b/pkg/sentry/fs/user/user.go
@@ -105,6 +105,7 @@ func getExecUserHomeVFS2(ctx context.Context, mns *vfs.MountNamespace, uid auth.
const defaultHome = "/"
root := mns.Root()
+ root.IncRef()
defer root.DecRef(ctx)
creds := auth.CredentialsFromContext(ctx)
diff --git a/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go b/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go
index ed729e480..e6fe0fc0d 100644
--- a/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go
+++ b/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go
@@ -95,10 +95,13 @@ func NewAccessor(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth
if err != nil {
return nil, err
}
+ // Pass a reference on root to the Accessor.
+ root := mntns.Root()
+ root.IncRef()
return &Accessor{
vfsObj: vfsObj,
mntns: mntns,
- root: mntns.Root(),
+ root: root,
creds: creds,
}, nil
}
diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go
index d635c9e73..675506269 100644
--- a/pkg/sentry/kernel/kernel.go
+++ b/pkg/sentry/kernel/kernel.go
@@ -841,14 +841,16 @@ func (ctx *createProcessContext) Value(key interface{}) interface{} {
if ctx.args.MountNamespaceVFS2 == nil {
return nil
}
- // MountNamespaceVFS2.Root() takes a reference on the root dirent for us.
- return ctx.args.MountNamespaceVFS2.Root()
+ root := ctx.args.MountNamespaceVFS2.Root()
+ root.IncRef()
+ return root
case vfs.CtxMountNamespace:
if ctx.k.globalInit == nil {
return nil
}
- // MountNamespaceVFS2 takes a reference for us.
- return ctx.k.GlobalInit().Leader().MountNamespaceVFS2()
+ mntns := ctx.k.GlobalInit().Leader().MountNamespaceVFS2()
+ mntns.IncRef()
+ return mntns
case fs.CtxDirentCacheLimiter:
return ctx.k.DirentCacheLimiter
case inet.CtxStack:
@@ -904,14 +906,13 @@ func (k *Kernel) CreateProcess(args CreateProcessArgs) (*ThreadGroup, ThreadID,
if VFS2Enabled {
mntnsVFS2 = args.MountNamespaceVFS2
if mntnsVFS2 == nil {
- // MountNamespaceVFS2 adds a reference to the namespace, which is
- // transferred to the new process.
+ // Add a reference to the namespace, which is transferred to the new process.
mntnsVFS2 = k.globalInit.Leader().MountNamespaceVFS2()
+ mntnsVFS2.IncRef()
}
// Get the root directory from the MountNamespace.
root := mntnsVFS2.Root()
- // The call to newFSContext below will take a reference on root, so we
- // don't need to hold this one.
+ root.IncRef()
defer root.DecRef(ctx)
// Grab the working directory.
@@ -1648,16 +1649,16 @@ func (ctx supervisorContext) Value(key interface{}) interface{} {
if ctx.k.globalInit == nil {
return vfs.VirtualDentry{}
}
- mntns := ctx.k.GlobalInit().Leader().MountNamespaceVFS2()
- defer mntns.DecRef(ctx)
- // Root() takes a reference on the root dirent for us.
- return mntns.Root()
+ root := ctx.k.GlobalInit().Leader().MountNamespaceVFS2().Root()
+ root.IncRef()
+ return root
case vfs.CtxMountNamespace:
if ctx.k.globalInit == nil {
return nil
}
- // MountNamespaceVFS2() takes a reference for us.
- return ctx.k.GlobalInit().Leader().MountNamespaceVFS2()
+ mntns := ctx.k.GlobalInit().Leader().MountNamespaceVFS2()
+ mntns.IncRef()
+ return mntns
case fs.CtxDirentCacheLimiter:
return ctx.k.DirentCacheLimiter
case inet.CtxStack:
diff --git a/pkg/sentry/kernel/task.go b/pkg/sentry/kernel/task.go
index f796e0fa3..e90a19cfb 100644
--- a/pkg/sentry/kernel/task.go
+++ b/pkg/sentry/kernel/task.go
@@ -735,7 +735,6 @@ func (t *Task) SyscallRestartBlock() SyscallRestartBlock {
func (t *Task) IsChrooted() bool {
if VFS2Enabled {
realRoot := t.mountNamespaceVFS2.Root()
- defer realRoot.DecRef(t)
root := t.fsContext.RootDirectoryVFS2()
defer root.DecRef(t)
return root != realRoot
@@ -868,7 +867,6 @@ func (t *Task) MountNamespace() *fs.MountNamespace {
func (t *Task) MountNamespaceVFS2() *vfs.MountNamespace {
t.mu.Lock()
defer t.mu.Unlock()
- t.mountNamespaceVFS2.IncRef()
return t.mountNamespaceVFS2
}
diff --git a/pkg/sentry/syscalls/linux/vfs2/execve.go b/pkg/sentry/syscalls/linux/vfs2/execve.go
index 066ee0863..c8ce2aabc 100644
--- a/pkg/sentry/syscalls/linux/vfs2/execve.go
+++ b/pkg/sentry/syscalls/linux/vfs2/execve.go
@@ -110,8 +110,7 @@ func execveat(t *kernel.Task, dirfd int32, pathnameAddr, argvAddr, envvAddr user
}
// Load the new TaskContext.
- mntns := t.MountNamespaceVFS2() // FIXME(jamieliu): useless refcount change
- defer mntns.DecRef(t)
+ mntns := t.MountNamespaceVFS2()
wd := t.FSContext().WorkingDirectoryVFS2()
defer wd.DecRef(t)
remainingTraversals := uint(linux.MaxSymlinkTraversals)
diff --git a/pkg/sentry/vfs/mount.go b/pkg/sentry/vfs/mount.go
index 79a2d8c41..78f115bfa 100644
--- a/pkg/sentry/vfs/mount.go
+++ b/pkg/sentry/vfs/mount.go
@@ -727,14 +727,12 @@ func (mnt *Mount) Root() *Dentry {
return mnt.root
}
-// Root returns mntns' root. A reference is taken on the returned
-// VirtualDentry.
+// Root returns mntns' root. It does not take a reference on the returned Dentry.
func (mntns *MountNamespace) Root() VirtualDentry {
vd := VirtualDentry{
mount: mntns.root,
dentry: mntns.root.root,
}
- vd.IncRef()
return vd
}