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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/sentry/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"
)
const defaultPermission = 0444
// InoGenerator generates unique inode numbers for a given filesystem.
type InoGenerator interface {
NextIno() uint64
}
// tasksInode represents the inode for /proc/ directory.
//
// +stateify savable
type tasksInode struct {
kernfs.InodeNotSymlink
kernfs.InodeDirectoryNoNewChildren
kernfs.InodeAttrs
kernfs.OrderedChildren
inoGen InoGenerator
pidns *kernel.PIDNamespace
}
var _ kernfs.Inode = (*tasksInode)(nil)
func newTasksInode(inoGen InoGenerator, k *kernel.Kernel, pidns *kernel.PIDNamespace) (*tasksInode, *kernfs.Dentry) {
root := auth.NewRootCredentials(pidns.UserNamespace())
contents := map[string]*kernfs.Dentry{
//"cpuinfo": newCPUInfo(ctx, msrc),
//"filesystems": seqfile.NewSeqFileInode(ctx, &filesystemsData{}, msrc),
"loadavg": newDentry(root, inoGen.NextIno(), defaultPermission, &loadavgData{}),
"meminfo": newDentry(root, inoGen.NextIno(), defaultPermission, &meminfoData{k: k}),
"mounts": kernfs.NewStaticSymlink(root, inoGen.NextIno(), defaultPermission, "self/mounts"),
"self": newSelfSymlink(root, inoGen.NextIno(), defaultPermission, pidns),
"stat": newDentry(root, inoGen.NextIno(), defaultPermission, &statData{k: k}),
"thread-self": newThreadSelfSymlink(root, inoGen.NextIno(), defaultPermission, pidns),
//"uptime": newUptime(ctx, msrc),
//"version": newVersionData(root, inoGen.NextIno(), k),
"version": newDentry(root, inoGen.NextIno(), defaultPermission, &versionData{k: k}),
}
inode := &tasksInode{
pidns: pidns,
inoGen: inoGen,
}
inode.InodeAttrs.Init(root, inoGen.NextIno(), linux.ModeDirectory|0555)
dentry := &kernfs.Dentry{}
dentry.Init(inode)
inode.OrderedChildren.Init(kernfs.OrderedChildrenOptions{})
links := inode.OrderedChildren.Populate(dentry, contents)
inode.IncLinks(links)
return inode, dentry
}
// Lookup implements kernfs.inodeDynamicLookup.
func (i *tasksInode) Lookup(ctx context.Context, name string) (*vfs.Dentry, error) {
// Try to lookup a corresponding task.
tid, err := strconv.ParseUint(name, 10, 64)
if err != nil {
return nil, syserror.ENOENT
}
task := i.pidns.TaskWithID(kernel.ThreadID(tid))
if task == nil {
return nil, syserror.ENOENT
}
taskDentry := newTaskInode(i.inoGen, task, i.pidns, true)
return taskDentry.VFSDentry(), nil
}
// Valid implements kernfs.inodeDynamicLookup.
func (i *tasksInode) Valid(ctx context.Context) bool {
return true
}
// IterDirents implements kernfs.inodeDynamicLookup.
//
// TODO(gvisor.dev/issue/1195): Use tgid N offset = TGID_OFFSET + N.
func (i *tasksInode) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback, offset, relOffset int64) (int64, error) {
var tids []int
// Collect all tasks. Per linux we only include it in directory listings if
// it's the leader. But for whatever crazy reason, you can still walk to the
// given node.
for _, tg := range i.pidns.ThreadGroups() {
if leader := tg.Leader(); leader != nil {
tids = append(tids, int(i.pidns.IDOfThreadGroup(tg)))
}
}
if len(tids) == 0 {
return offset, nil
}
if relOffset >= int64(len(tids)) {
return offset, nil
}
sort.Ints(tids)
for _, tid := range tids[relOffset:] {
dirent := vfs.Dirent{
Name: strconv.FormatUint(uint64(tid), 10),
Type: linux.DT_DIR,
Ino: i.inoGen.NextIno(),
NextOff: offset + 1,
}
if !cb.Handle(dirent) {
return offset, nil
}
offset++
}
return offset, nil
}
// Open implements kernfs.Inode.
func (i *tasksInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, flags uint32) (*vfs.FileDescription, error) {
fd := &kernfs.GenericDirectoryFD{}
fd.Init(rp.Mount(), vfsd, &i.OrderedChildren, flags)
return fd.VFSFileDescription(), nil
}
func (i *tasksInode) Stat(vsfs *vfs.Filesystem) linux.Statx {
stat := i.InodeAttrs.Stat(vsfs)
// Add dynamic children to link count.
for _, tg := range i.pidns.ThreadGroups() {
if leader := tg.Leader(); leader != nil {
stat.Nlink++
}
}
return stat
}
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