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// Copyright 2019 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 proc
import (
"sort"
"strconv"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
)
// subtasksInode represents the inode for /proc/[pid]/task/ directory.
//
// +stateify savable
type subtasksInode struct {
kernfs.InodeNotSymlink
kernfs.InodeDirectoryNoNewChildren
kernfs.InodeAttrs
kernfs.OrderedChildren
kernfs.AlwaysValid
locks vfs.FileLocks
fs *filesystem
task *kernel.Task
pidns *kernel.PIDNamespace
cgroupControllers map[string]string
}
var _ kernfs.Inode = (*subtasksInode)(nil)
func (fs *filesystem) newSubtasks(task *kernel.Task, pidns *kernel.PIDNamespace, cgroupControllers map[string]string) *kernfs.Dentry {
subInode := &subtasksInode{
fs: fs,
task: task,
pidns: pidns,
cgroupControllers: cgroupControllers,
}
// 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{})
inode := &taskOwnedInode{Inode: subInode, owner: task}
dentry := &kernfs.Dentry{}
dentry.Init(inode)
return dentry
}
// Lookup implements kernfs.inodeDynamicLookup.
func (i *subtasksInode) Lookup(ctx context.Context, name string) (*vfs.Dentry, error) {
tid, err := strconv.ParseUint(name, 10, 32)
if err != nil {
return nil, syserror.ENOENT
}
subTask := i.pidns.TaskWithID(kernel.ThreadID(tid))
if subTask == nil {
return nil, syserror.ENOENT
}
if subTask.ThreadGroup() != i.task.ThreadGroup() {
return nil, syserror.ENOENT
}
subTaskDentry := i.fs.newTaskInode(subTask, i.pidns, false, i.cgroupControllers)
return subTaskDentry.VFSDentry(), nil
}
// IterDirents implements kernfs.inodeDynamicLookup.
func (i *subtasksInode) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback, offset, relOffset int64) (int64, error) {
tasks := i.task.ThreadGroup().MemberIDs(i.pidns)
if len(tasks) == 0 {
return offset, syserror.ENOENT
}
if relOffset >= int64(len(tasks)) {
return offset, nil
}
tids := make([]int, 0, len(tasks))
for _, tid := range tasks {
tids = append(tids, int(tid))
}
sort.Ints(tids)
for _, tid := range tids[relOffset:] {
dirent := vfs.Dirent{
Name: strconv.FormatUint(uint64(tid), 10),
Type: linux.DT_DIR,
Ino: i.fs.NextIno(),
NextOff: offset + 1,
}
if err := cb.Handle(dirent); err != nil {
return offset, err
}
offset++
}
return offset, nil
}
type subtasksFD struct {
kernfs.GenericDirectoryFD
task *kernel.Task
}
func (fd *subtasksFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback) error {
if fd.task.ExitState() >= kernel.TaskExitZombie {
return syserror.ENOENT
}
return fd.GenericDirectoryFD.IterDirents(ctx, cb)
}
// Seek implements vfs.FileDescriptionImpl.Seek.
func (fd *subtasksFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
if fd.task.ExitState() >= kernel.TaskExitZombie {
return 0, syserror.ENOENT
}
return fd.GenericDirectoryFD.Seek(ctx, offset, whence)
}
// Stat implements vfs.FileDescriptionImpl.Stat.
func (fd *subtasksFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
if fd.task.ExitState() >= kernel.TaskExitZombie {
return linux.Statx{}, syserror.ENOENT
}
return fd.GenericDirectoryFD.Stat(ctx, opts)
}
// SetStat implements vfs.FileDescriptionImpl.SetStat.
func (fd *subtasksFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
if fd.task.ExitState() >= kernel.TaskExitZombie {
return syserror.ENOENT
}
return fd.GenericDirectoryFD.SetStat(ctx, opts)
}
// Open implements kernfs.Inode.
func (i *subtasksInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
fd := &subtasksFD{task: i.task}
if err := fd.Init(&i.OrderedChildren, &i.locks, &opts, kernfs.GenericDirectoryFDOptions{
SeekEnd: kernfs.SeekEndZero,
}); err != nil {
return nil, err
}
if err := fd.VFSFileDescription().Init(fd, opts.Flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{}); err != nil {
return nil, err
}
return fd.VFSFileDescription(), nil
}
// Stat implements kernfs.Inode.
func (i *subtasksInode) Stat(ctx context.Context, vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
stat, err := i.InodeAttrs.Stat(ctx, vsfs, opts)
if err != nil {
return linux.Statx{}, err
}
if opts.Mask&linux.STATX_NLINK != 0 {
stat.Nlink += uint32(i.task.ThreadGroup().Count())
}
return stat, nil
}
// SetStat implements Inode.SetStat not allowing inode attributes to be changed.
func (*subtasksInode) SetStat(context.Context, *vfs.Filesystem, *auth.Credentials, vfs.SetStatOptions) error {
return syserror.EPERM
}
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