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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 (
"bytes"
"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"
)
const (
selfName = "self"
threadSelfName = "thread-self"
)
// 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
kernfs.AlwaysValid
inoGen InoGenerator
pidns *kernel.PIDNamespace
// '/proc/self' and '/proc/thread-self' have custom directory offsets in
// Linux. So handle them outside of OrderedChildren.
selfSymlink *vfs.Dentry
threadSelfSymlink *vfs.Dentry
// cgroupControllers is a map of controller name to directory in the
// cgroup hierarchy. These controllers are immutable and will be listed
// in /proc/pid/cgroup if not nil.
cgroupControllers map[string]string
}
var _ kernfs.Inode = (*tasksInode)(nil)
func newTasksInode(inoGen InoGenerator, k *kernel.Kernel, pidns *kernel.PIDNamespace, cgroupControllers map[string]string) (*tasksInode, *kernfs.Dentry) {
root := auth.NewRootCredentials(pidns.UserNamespace())
contents := map[string]*kernfs.Dentry{
"cpuinfo": newDentry(root, inoGen.NextIno(), 0444, newStaticFile(cpuInfoData(k))),
"filesystems": newDentry(root, inoGen.NextIno(), 0444, &filesystemsData{}),
"loadavg": newDentry(root, inoGen.NextIno(), 0444, &loadavgData{}),
"sys": newSysDir(root, inoGen, k),
"meminfo": newDentry(root, inoGen.NextIno(), 0444, &meminfoData{}),
"mounts": kernfs.NewStaticSymlink(root, inoGen.NextIno(), "self/mounts"),
"net": kernfs.NewStaticSymlink(root, inoGen.NextIno(), "self/net"),
"stat": newDentry(root, inoGen.NextIno(), 0444, &statData{}),
"uptime": newDentry(root, inoGen.NextIno(), 0444, &uptimeData{}),
"version": newDentry(root, inoGen.NextIno(), 0444, &versionData{}),
}
inode := &tasksInode{
pidns: pidns,
inoGen: inoGen,
selfSymlink: newSelfSymlink(root, inoGen.NextIno(), pidns).VFSDentry(),
threadSelfSymlink: newThreadSelfSymlink(root, inoGen.NextIno(), pidns).VFSDentry(),
cgroupControllers: cgroupControllers,
}
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 {
// If it failed to parse, check if it's one of the special handled files.
switch name {
case selfName:
return i.selfSymlink, nil
case threadSelfName:
return i.threadSelfSymlink, 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, i.cgroupControllers)
return taskDentry.VFSDentry(), nil
}
// IterDirents implements kernfs.inodeDynamicLookup.
func (i *tasksInode) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback, offset, _ int64) (int64, error) {
// fs/proc/internal.h: #define FIRST_PROCESS_ENTRY 256
const FIRST_PROCESS_ENTRY = 256
// Use maxTaskID to shortcut searches that will result in 0 entries.
const maxTaskID = kernel.TasksLimit + 1
if offset >= maxTaskID {
return offset, nil
}
// According to Linux (fs/proc/base.c:proc_pid_readdir()), process directories
// start at offset FIRST_PROCESS_ENTRY with '/proc/self', followed by
// '/proc/thread-self' and then '/proc/[pid]'.
if offset < FIRST_PROCESS_ENTRY {
offset = FIRST_PROCESS_ENTRY
}
if offset == FIRST_PROCESS_ENTRY {
dirent := vfs.Dirent{
Name: selfName,
Type: linux.DT_LNK,
Ino: i.inoGen.NextIno(),
NextOff: offset + 1,
}
if err := cb.Handle(dirent); err != nil {
return offset, err
}
offset++
}
if offset == FIRST_PROCESS_ENTRY+1 {
dirent := vfs.Dirent{
Name: threadSelfName,
Type: linux.DT_LNK,
Ino: i.inoGen.NextIno(),
NextOff: offset + 1,
}
if err := cb.Handle(dirent); err != nil {
return offset, err
}
offset++
}
// Collect all tasks that TGIDs are greater than the offset specified. Per
// Linux we only include in directory listings if it's the leader. But for
// whatever crazy reason, you can still walk to the given node.
var tids []int
startTid := offset - FIRST_PROCESS_ENTRY - 2
for _, tg := range i.pidns.ThreadGroups() {
tid := i.pidns.IDOfThreadGroup(tg)
if int64(tid) < startTid {
continue
}
if leader := tg.Leader(); leader != nil {
tids = append(tids, int(tid))
}
}
if len(tids) == 0 {
return offset, nil
}
sort.Ints(tids)
for _, tid := range tids {
dirent := vfs.Dirent{
Name: strconv.FormatUint(uint64(tid), 10),
Type: linux.DT_DIR,
Ino: i.inoGen.NextIno(),
NextOff: FIRST_PROCESS_ENTRY + 2 + int64(tid) + 1,
}
if err := cb.Handle(dirent); err != nil {
return offset, err
}
offset++
}
return maxTaskID, nil
}
// Open implements kernfs.Inode.
func (i *tasksInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
fd := &kernfs.GenericDirectoryFD{}
fd.Init(rp.Mount(), vfsd, &i.OrderedChildren, &opts)
return fd.VFSFileDescription(), nil
}
func (i *tasksInode) Stat(vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
stat, err := i.InodeAttrs.Stat(vsfs, opts)
if err != nil {
return linux.Statx{}, err
}
if opts.Mask&linux.STATX_NLINK != 0 {
// Add dynamic children to link count.
for _, tg := range i.pidns.ThreadGroups() {
if leader := tg.Leader(); leader != nil {
stat.Nlink++
}
}
}
return stat, nil
}
func cpuInfoData(k *kernel.Kernel) string {
features := k.FeatureSet()
if features == nil {
// Kernel is always initialized with a FeatureSet.
panic("cpuinfo read with nil FeatureSet")
}
var buf bytes.Buffer
for i, max := uint(0), k.ApplicationCores(); i < max; i++ {
features.WriteCPUInfoTo(i, &buf)
}
return buf.String()
}
func shmData(v uint64) dynamicInode {
return newStaticFile(strconv.FormatUint(v, 10))
}
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