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[vfs] kernfs: Do not hold reference on the inode when opening FD.

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The FD should hold a reference on the dentry they were opened on which in turn
holds a reference on the inode it points to.

PiperOrigin-RevId: 333589223
This commit is contained in:
Ayush Ranjan
2020-09-24 13:48:01 -07:00
committed by gVisor bot
parent 5f8c653542
commit 832d91b805
4 changed files with 48 additions and 54 deletions
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pkg/sentry/fsimpl/devpts/master.go
-3
View File
@@ -58,14 +58,12 @@ func (mi *masterInode) Open(ctx context.Context, rp *vfs.ResolvingPath, d *kernf
return nil, err
}
mi.IncRef()
fd := &masterFileDescription{
inode: mi,
t: t,
}
fd.LockFD.Init(&mi.locks)
if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), d.VFSDentry(), &vfs.FileDescriptionOptions{}); err != nil {
mi.DecRef(ctx)
return nil, err
}
return &fd.vfsfd, nil
@@ -106,7 +104,6 @@ var _ vfs.FileDescriptionImpl = (*masterFileDescription)(nil)
// Release implements vfs.FileDescriptionImpl.Release.
func (mfd *masterFileDescription) Release(ctx context.Context) {
mfd.inode.root.masterClose(mfd.t)
mfd.inode.DecRef(ctx)
}
// EventRegister implements waiter.Waitable.EventRegister.
pkg/sentry/fsimpl/devpts/replica.go
+45 -49
View File
@@ -54,14 +54,12 @@ type replicaInode struct {
var _ kernfs.Inode = (*replicaInode)(nil)
// Open implements kernfs.Inode.Open.
func (si *replicaInode) Open(ctx context.Context, rp *vfs.ResolvingPath, d *kernfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
si.IncRef()
func (ri *replicaInode) Open(ctx context.Context, rp *vfs.ResolvingPath, d *kernfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
fd := &replicaFileDescription{
inode: si,
inode: ri,
}
fd.LockFD.Init(&si.locks)
fd.LockFD.Init(&ri.locks)
if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), d.VFSDentry(), &vfs.FileDescriptionOptions{}); err != nil {
si.DecRef(ctx)
return nil, err
}
return &fd.vfsfd, nil
@@ -69,32 +67,32 @@ func (si *replicaInode) Open(ctx context.Context, rp *vfs.ResolvingPath, d *kern
}
// Valid implements kernfs.Inode.Valid.
func (si *replicaInode) Valid(context.Context) bool {
func (ri *replicaInode) Valid(context.Context) bool {
// Return valid if the replica still exists.
si.root.mu.Lock()
defer si.root.mu.Unlock()
_, ok := si.root.replicas[si.t.n]
ri.root.mu.Lock()
defer ri.root.mu.Unlock()
_, ok := ri.root.replicas[ri.t.n]
return ok
}
// Stat implements kernfs.Inode.Stat.
func (si *replicaInode) Stat(ctx context.Context, vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
statx, err := si.InodeAttrs.Stat(ctx, vfsfs, opts)
func (ri *replicaInode) Stat(ctx context.Context, vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
statx, err := ri.InodeAttrs.Stat(ctx, vfsfs, opts)
if err != nil {
return linux.Statx{}, err
}
statx.Blksize = 1024
statx.RdevMajor = linux.UNIX98_PTY_REPLICA_MAJOR
statx.RdevMinor = si.t.n
statx.RdevMinor = ri.t.n
return statx, nil
}
// SetStat implements kernfs.Inode.SetStat
func (si *replicaInode) SetStat(ctx context.Context, vfsfs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error {
func (ri *replicaInode) SetStat(ctx context.Context, vfsfs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error {
if opts.Stat.Mask&linux.STATX_SIZE != 0 {
return syserror.EINVAL
}
return si.InodeAttrs.SetStat(ctx, vfsfs, creds, opts)
return ri.InodeAttrs.SetStat(ctx, vfsfs, creds, opts)
}
// +stateify savable
@@ -109,37 +107,35 @@ type replicaFileDescription struct {
var _ vfs.FileDescriptionImpl = (*replicaFileDescription)(nil)
// Release implements fs.FileOperations.Release.
func (sfd *replicaFileDescription) Release(ctx context.Context) {
sfd.inode.DecRef(ctx)
}
func (rfd *replicaFileDescription) Release(ctx context.Context) {}
// EventRegister implements waiter.Waitable.EventRegister.
func (sfd *replicaFileDescription) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
sfd.inode.t.ld.replicaWaiter.EventRegister(e, mask)
func (rfd *replicaFileDescription) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
rfd.inode.t.ld.replicaWaiter.EventRegister(e, mask)
}
// EventUnregister implements waiter.Waitable.EventUnregister.
func (sfd *replicaFileDescription) EventUnregister(e *waiter.Entry) {
sfd.inode.t.ld.replicaWaiter.EventUnregister(e)
func (rfd *replicaFileDescription) EventUnregister(e *waiter.Entry) {
rfd.inode.t.ld.replicaWaiter.EventUnregister(e)
}
// Readiness implements waiter.Waitable.Readiness.
func (sfd *replicaFileDescription) Readiness(mask waiter.EventMask) waiter.EventMask {
return sfd.inode.t.ld.replicaReadiness()
func (rfd *replicaFileDescription) Readiness(mask waiter.EventMask) waiter.EventMask {
return rfd.inode.t.ld.replicaReadiness()
}
// Read implements vfs.FileDescriptionImpl.Read.
func (sfd *replicaFileDescription) Read(ctx context.Context, dst usermem.IOSequence, _ vfs.ReadOptions) (int64, error) {
return sfd.inode.t.ld.inputQueueRead(ctx, dst)
func (rfd *replicaFileDescription) Read(ctx context.Context, dst usermem.IOSequence, _ vfs.ReadOptions) (int64, error) {
return rfd.inode.t.ld.inputQueueRead(ctx, dst)
}
// Write implements vfs.FileDescriptionImpl.Write.
func (sfd *replicaFileDescription) Write(ctx context.Context, src usermem.IOSequence, _ vfs.WriteOptions) (int64, error) {
return sfd.inode.t.ld.outputQueueWrite(ctx, src)
func (rfd *replicaFileDescription) Write(ctx context.Context, src usermem.IOSequence, _ vfs.WriteOptions) (int64, error) {
return rfd.inode.t.ld.outputQueueWrite(ctx, src)
}
// Ioctl implements vfs.FileDescriptionImpl.Ioctl.
func (sfd *replicaFileDescription) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
func (rfd *replicaFileDescription) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
t := kernel.TaskFromContext(ctx)
if t == nil {
// ioctl(2) may only be called from a task goroutine.
@@ -149,35 +145,35 @@ func (sfd *replicaFileDescription) Ioctl(ctx context.Context, io usermem.IO, arg
switch cmd := args[1].Uint(); cmd {
case linux.FIONREAD: // linux.FIONREAD == linux.TIOCINQ
// Get the number of bytes in the input queue read buffer.
return 0, sfd.inode.t.ld.inputQueueReadSize(t, io, args)
return 0, rfd.inode.t.ld.inputQueueReadSize(t, io, args)
case linux.TCGETS:
return sfd.inode.t.ld.getTermios(t, args)
return rfd.inode.t.ld.getTermios(t, args)
case linux.TCSETS:
return sfd.inode.t.ld.setTermios(t, args)
return rfd.inode.t.ld.setTermios(t, args)
case linux.TCSETSW:
// TODO(b/29356795): This should drain the output queue first.
return sfd.inode.t.ld.setTermios(t, args)
return rfd.inode.t.ld.setTermios(t, args)
case linux.TIOCGPTN:
nP := primitive.Uint32(sfd.inode.t.n)
nP := primitive.Uint32(rfd.inode.t.n)
_, err := nP.CopyOut(t, args[2].Pointer())
return 0, err
case linux.TIOCGWINSZ:
return 0, sfd.inode.t.ld.windowSize(t, args)
return 0, rfd.inode.t.ld.windowSize(t, args)
case linux.TIOCSWINSZ:
return 0, sfd.inode.t.ld.setWindowSize(t, args)
return 0, rfd.inode.t.ld.setWindowSize(t, args)
case linux.TIOCSCTTY:
// Make the given terminal the controlling terminal of the
// calling process.
return 0, sfd.inode.t.setControllingTTY(ctx, args, false /* isMaster */)
return 0, rfd.inode.t.setControllingTTY(ctx, args, false /* isMaster */)
case linux.TIOCNOTTY:
// Release this process's controlling terminal.
return 0, sfd.inode.t.releaseControllingTTY(ctx, args, false /* isMaster */)
return 0, rfd.inode.t.releaseControllingTTY(ctx, args, false /* isMaster */)
case linux.TIOCGPGRP:
// Get the foreground process group.
return sfd.inode.t.foregroundProcessGroup(ctx, args, false /* isMaster */)
return rfd.inode.t.foregroundProcessGroup(ctx, args, false /* isMaster */)
case linux.TIOCSPGRP:
// Set the foreground process group.
return sfd.inode.t.setForegroundProcessGroup(ctx, args, false /* isMaster */)
return rfd.inode.t.setForegroundProcessGroup(ctx, args, false /* isMaster */)
default:
maybeEmitUnimplementedEvent(ctx, cmd)
return 0, syserror.ENOTTY
@@ -185,24 +181,24 @@ func (sfd *replicaFileDescription) Ioctl(ctx context.Context, io usermem.IO, arg
}
// SetStat implements vfs.FileDescriptionImpl.SetStat.
func (sfd *replicaFileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
func (rfd *replicaFileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
creds := auth.CredentialsFromContext(ctx)
fs := sfd.vfsfd.VirtualDentry().Mount().Filesystem()
return sfd.inode.SetStat(ctx, fs, creds, opts)
fs := rfd.vfsfd.VirtualDentry().Mount().Filesystem()
return rfd.inode.SetStat(ctx, fs, creds, opts)
}
// Stat implements vfs.FileDescriptionImpl.Stat.
func (sfd *replicaFileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
fs := sfd.vfsfd.VirtualDentry().Mount().Filesystem()
return sfd.inode.Stat(ctx, fs, opts)
func (rfd *replicaFileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
fs := rfd.vfsfd.VirtualDentry().Mount().Filesystem()
return rfd.inode.Stat(ctx, fs, opts)
}
// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
func (sfd *replicaFileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
return sfd.Locks().LockPOSIX(ctx, &sfd.vfsfd, uid, t, start, length, whence, block)
func (rfd *replicaFileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
return rfd.Locks().LockPOSIX(ctx, &rfd.vfsfd, uid, t, start, length, whence, block)
}
// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
func (sfd *replicaFileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
return sfd.Locks().UnlockPOSIX(ctx, &sfd.vfsfd, uid, start, length, whence)
func (rfd *replicaFileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
return rfd.Locks().UnlockPOSIX(ctx, &rfd.vfsfd, uid, start, length, whence)
}
pkg/sentry/fsimpl/kernfs/filesystem.go
+2 -1
View File
@@ -132,7 +132,8 @@ func (fs *Filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.Vir
if err != nil {
return nil, err
}
// Reference on childVFSD dropped by a corresponding Valid.
// Reference on c (provided by Lookup) will be dropped when the dentry
// fails validation.
parent.InsertChildLocked(name, c)
child = c
}
pkg/sentry/fsimpl/kernfs/kernfs.go
+1 -1
View File
@@ -350,7 +350,7 @@ type Inode interface {
// Open creates a file description for the filesystem object represented by
// this inode. The returned file description should hold a reference on the
// inode for its lifetime.
// dentry for its lifetime.
//
// Precondition: rp.Done(). vfsd.Impl() must be the kernfs Dentry containing
// the inode on which Open() is being called.