Use new reference count utility throughout gvisor.

This uses the refs_vfs2 template in vfs2 as well as objects common to vfs1 and
vfs2. Note that vfs1-only refcounts are not replaced, since vfs1 will be deleted
soon anyway.

The following structs now use the new tool, with leak check enabled:
devpts:rootInode
fuse:inode
kernfs:Dentry
kernfs:dir
kernfs:readonlyDir
kernfs:StaticDirectory
proc:fdDirInode
proc:fdInfoDirInode
proc:subtasksInode
proc:taskInode
proc:tasksInode
vfs:FileDescription
vfs:MountNamespace
vfs:Filesystem
sys:dir
kernel:FSContext
kernel:ProcessGroup
kernel:Session
shm:Shm
mm:aioMappable
mm:SpecialMappable
transport:queue

And the following use the template, but because they currently are not leak
checked, a TODO is left instead of enabling leak check in this patch:
kernel:FDTable
tun:tunEndpoint

Updates #1486.

PiperOrigin-RevId: 328460377

6 files changed, 100 insertions, 5 deletions

diff --git a/pkg/sentry/fsimpl/proc/BUILD b/pkg/sentry/fsimpl/proc/BUILD
index 14ecfd300..a45b44440 100644
--- a/pkg/sentry/fsimpl/proc/BUILD
+++ b/pkg/sentry/fsimpl/proc/BUILD
@@ -1,18 +1,79 @@
 load("//tools:defs.bzl", "go_library", "go_test")
+load("//tools/go_generics:defs.bzl", "go_template_instance")
 
 licenses(["notice"])
 
+go_template_instance(
+    name = "fd_dir_inode_refs",
+    out = "fd_dir_inode_refs.go",
+    package = "proc",
+    prefix = "fdDirInode",
+    template = "//pkg/refs_vfs2:refs_template",
+    types = {
+        "T": "fdDirInode",
+    },
+)
+
+go_template_instance(
+    name = "fd_info_dir_inode_refs",
+    out = "fd_info_dir_inode_refs.go",
+    package = "proc",
+    prefix = "fdInfoDirInode",
+    template = "//pkg/refs_vfs2:refs_template",
+    types = {
+        "T": "fdInfoDirInode",
+    },
+)
+
+go_template_instance(
+    name = "subtasks_inode_refs",
+    out = "subtasks_inode_refs.go",
+    package = "proc",
+    prefix = "subtasksInode",
+    template = "//pkg/refs_vfs2:refs_template",
+    types = {
+        "T": "subtasksInode",
+    },
+)
+
+go_template_instance(
+    name = "task_inode_refs",
+    out = "task_inode_refs.go",
+    package = "proc",
+    prefix = "taskInode",
+    template = "//pkg/refs_vfs2:refs_template",
+    types = {
+        "T": "taskInode",
+    },
+)
+
+go_template_instance(
+    name = "tasks_inode_refs",
+    out = "tasks_inode_refs.go",
+    package = "proc",
+    prefix = "tasksInode",
+    template = "//pkg/refs_vfs2:refs_template",
+    types = {
+        "T": "tasksInode",
+    },
+)
+
 go_library(
     name = "proc",
     srcs = [
+        "fd_dir_inode_refs.go",
+        "fd_info_dir_inode_refs.go",
         "filesystem.go",
         "subtasks.go",
+        "subtasks_inode_refs.go",
         "task.go",
         "task_fds.go",
         "task_files.go",
+        "task_inode_refs.go",
         "task_net.go",
         "tasks.go",
         "tasks_files.go",
+        "tasks_inode_refs.go",
         "tasks_sys.go",
     ],
     visibility = ["//pkg/sentry:internal"],
diff --git a/pkg/sentry/fsimpl/proc/subtasks.go b/pkg/sentry/fsimpl/proc/subtasks.go
index f25747da3..01c0efb3a 100644
--- a/pkg/sentry/fsimpl/proc/subtasks.go
+++ b/pkg/sentry/fsimpl/proc/subtasks.go
@@ -31,6 +31,7 @@ import (
 //
 // +stateify savable
 type subtasksInode struct {
+	subtasksInodeRefs
 	kernfs.InodeNotSymlink
 	kernfs.InodeDirectoryNoNewChildren
 	kernfs.InodeAttrs
@@ -57,6 +58,7 @@ func (fs *filesystem) newSubtasks(task *kernel.Task, pidns *kernel.PIDNamespace,
 	// Note: credentials are overridden by taskOwnedInode.
 	subInode.InodeAttrs.Init(task.Credentials(), linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), linux.ModeDirectory|0555)
 	subInode.OrderedChildren.Init(kernfs.OrderedChildrenOptions{})
+	subInode.EnableLeakCheck()
 
 	inode := &taskOwnedInode{Inode: subInode, owner: task}
 	dentry := &kernfs.Dentry{}
@@ -182,3 +184,8 @@ func (i *subtasksInode) Stat(ctx context.Context, vsfs *vfs.Filesystem, opts vfs
 func (*subtasksInode) SetStat(context.Context, *vfs.Filesystem, *auth.Credentials, vfs.SetStatOptions) error {
 	return syserror.EPERM
 }
+
+// DecRef implements kernfs.Inode.
+func (i *subtasksInode) DecRef(context.Context) {
+	i.subtasksInodeRefs.DecRef(i.Destroy)
+}
diff --git a/pkg/sentry/fsimpl/proc/task.go b/pkg/sentry/fsimpl/proc/task.go
index 109b31b4c..66b557abd 100644
--- a/pkg/sentry/fsimpl/proc/task.go
+++ b/pkg/sentry/fsimpl/proc/task.go
@@ -32,6 +32,7 @@ import (
 //
 // +stateify savable
 type taskInode struct {
+	taskInodeRefs
 	kernfs.InodeNotSymlink
 	kernfs.InodeDirectoryNoNewChildren
 	kernfs.InodeNoDynamicLookup
@@ -84,6 +85,7 @@ func (fs *filesystem) newTaskInode(task *kernel.Task, pidns *kernel.PIDNamespace
 	taskInode := &taskInode{task: task}
 	// Note: credentials are overridden by taskOwnedInode.
 	taskInode.InodeAttrs.Init(task.Credentials(), linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), linux.ModeDirectory|0555)
+	taskInode.EnableLeakCheck()
 
 	inode := &taskOwnedInode{Inode: taskInode, owner: task}
 	dentry := &kernfs.Dentry{}
@@ -119,6 +121,11 @@ func (*taskInode) SetStat(context.Context, *vfs.Filesystem, *auth.Credentials, v
 	return syserror.EPERM
 }
 
+// DecRef implements kernfs.Inode.
+func (i *taskInode) DecRef(context.Context) {
+	i.taskInodeRefs.DecRef(i.Destroy)
+}
+
 // taskOwnedInode implements kernfs.Inode and overrides inode owner with task
 // effective user and group.
 type taskOwnedInode struct {
@@ -147,6 +154,7 @@ func (fs *filesystem) newTaskOwnedDir(task *kernel.Task, ino uint64, perm linux.
 	dir.Init(task.Credentials(), linux.UNNAMED_MAJOR, fs.devMinor, ino, perm, kernfs.GenericDirectoryFDOptions{
 		SeekEnd: kernfs.SeekEndZero,
 	})
+	dir.EnableLeakCheck()
 
 	inode := &taskOwnedInode{Inode: dir, owner: task}
 	d := &kernfs.Dentry{}
diff --git a/pkg/sentry/fsimpl/proc/task_fds.go b/pkg/sentry/fsimpl/proc/task_fds.go
index e8fcb9aa1..0527b2de8 100644
--- a/pkg/sentry/fsimpl/proc/task_fds.go
+++ b/pkg/sentry/fsimpl/proc/task_fds.go
@@ -22,7 +22,6 @@ import (
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
-	"gvisor.dev/gvisor/pkg/refs"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
@@ -101,6 +100,7 @@ func (i *fdDir) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback, off
 //
 // +stateify savable
 type fdDirInode struct {
+	fdDirInodeRefs
 	kernfs.InodeNotSymlink
 	kernfs.InodeDirectoryNoNewChildren
 	kernfs.InodeAttrs
@@ -120,6 +120,7 @@ func (fs *filesystem) newFDDirInode(task *kernel.Task) *kernfs.Dentry {
 		},
 	}
 	inode.InodeAttrs.Init(task.Credentials(), linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), linux.ModeDirectory|0555)
+	inode.EnableLeakCheck()
 
 	dentry := &kernfs.Dentry{}
 	dentry.Init(inode)
@@ -175,6 +176,11 @@ func (i *fdDirInode) CheckPermissions(ctx context.Context, creds *auth.Credentia
 	return err
 }
 
+// DecRef implements kernfs.Inode.
+func (i *fdDirInode) DecRef(context.Context) {
+	i.fdDirInodeRefs.DecRef(i.Destroy)
+}
+
 // fdSymlink is an symlink for the /proc/[pid]/fd/[fd] file.
 //
 // +stateify savable
@@ -227,6 +233,7 @@ func (s *fdSymlink) Getlink(ctx context.Context, mnt *vfs.Mount) (vfs.VirtualDen
 //
 // +stateify savable
 type fdInfoDirInode struct {
+	fdInfoDirInodeRefs
 	kernfs.InodeNotSymlink
 	kernfs.InodeDirectoryNoNewChildren
 	kernfs.InodeAttrs
@@ -245,6 +252,7 @@ func (fs *filesystem) newFDInfoDirInode(task *kernel.Task) *kernfs.Dentry {
 		},
 	}
 	inode.InodeAttrs.Init(task.Credentials(), linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), linux.ModeDirectory|0555)
+	inode.EnableLeakCheck()
 
 	dentry := &kernfs.Dentry{}
 	dentry.Init(inode)
@@ -282,12 +290,16 @@ func (i *fdInfoDirInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *
 	return fd.VFSFileDescription(), nil
 }
 
+// DecRef implements kernfs.Inode.
+func (i *fdInfoDirInode) DecRef(context.Context) {
+	i.fdInfoDirInodeRefs.DecRef(i.Destroy)
+}
+
 // fdInfoData implements vfs.DynamicBytesSource for /proc/[pid]/fdinfo/[fd].
 //
 // +stateify savable
 type fdInfoData struct {
 	kernfs.DynamicBytesFile
-	refs.AtomicRefCount
 
 	task *kernel.Task
 	fd   int32
diff --git a/pkg/sentry/fsimpl/proc/task_net.go b/pkg/sentry/fsimpl/proc/task_net.go
index a4c884bf9..4e69782c7 100644
--- a/pkg/sentry/fsimpl/proc/task_net.go
+++ b/pkg/sentry/fsimpl/proc/task_net.go
@@ -262,7 +262,7 @@ func (n *netUnixData) Generate(ctx context.Context, buf *bytes.Buffer) error {
 		// For now, we always redact this pointer.
 		fmt.Fprintf(buf, "%#016p: %08X %08X %08X %04X %02X %8d",
 			(*unix.SocketOperations)(nil), // Num, pointer to kernel socket struct.
-			s.Refs()-1,                    // RefCount, don't count our own ref.
+			s.ReadRefs()-1,                // RefCount, don't count our own ref.
 			0,                             // Protocol, always 0 for UDS.
 			sockFlags,                     // Flags.
 			sops.Endpoint().Type(),        // Type.
@@ -430,7 +430,7 @@ func commonGenerateTCP(ctx context.Context, buf *bytes.Buffer, k *kernel.Kernel,
 
 		// Field: refcount. Don't count the ref we obtain while deferencing
 		// the weakref to this socket.
-		fmt.Fprintf(buf, "%d ", s.Refs()-1)
+		fmt.Fprintf(buf, "%d ", s.ReadRefs()-1)
 
 		// Field: Socket struct address. Redacted due to the same reason as
 		// the 'Num' field in /proc/net/unix, see netUnix.ReadSeqFileData.
@@ -589,7 +589,7 @@ func (d *netUDPData) Generate(ctx context.Context, buf *bytes.Buffer) error {
 
 		// Field: ref; reference count on the socket inode. Don't count the ref
 		// we obtain while deferencing the weakref to this socket.
-		fmt.Fprintf(buf, "%d ", s.Refs()-1)
+		fmt.Fprintf(buf, "%d ", s.ReadRefs()-1)
 
 		// Field: Socket struct address. Redacted due to the same reason as
 		// the 'Num' field in /proc/net/unix, see netUnix.ReadSeqFileData.
diff --git a/pkg/sentry/fsimpl/proc/tasks.go b/pkg/sentry/fsimpl/proc/tasks.go
index 1391992b7..863c4467e 100644
--- a/pkg/sentry/fsimpl/proc/tasks.go
+++ b/pkg/sentry/fsimpl/proc/tasks.go
@@ -37,6 +37,7 @@ const (
 //
 // +stateify savable
 type tasksInode struct {
+	tasksInodeRefs
 	kernfs.InodeNotSymlink
 	kernfs.InodeDirectoryNoNewChildren
 	kernfs.InodeAttrs
@@ -84,6 +85,7 @@ func (fs *filesystem) newTasksInode(k *kernel.Kernel, pidns *kernel.PIDNamespace
 		cgroupControllers: cgroupControllers,
 	}
 	inode.InodeAttrs.Init(root, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), linux.ModeDirectory|0555)
+	inode.EnableLeakCheck()
 
 	dentry := &kernfs.Dentry{}
 	dentry.Init(inode)
@@ -226,6 +228,11 @@ func (i *tasksInode) Stat(ctx context.Context, vsfs *vfs.Filesystem, opts vfs.St
 	return stat, nil
 }
 
+// DecRef implements kernfs.Inode.
+func (i *tasksInode) DecRef(context.Context) {
+	i.tasksInodeRefs.DecRef(i.Destroy)
+}
+
 // staticFileSetStat implements a special static file that allows inode
 // attributes to be set. This is to support /proc files that are readonly, but
 // allow attributes to be set.