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-rw-r--r--pkg/sentry/fsimpl/proc/tasks.go235
1 files changed, 235 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/proc/tasks.go b/pkg/sentry/fsimpl/proc/tasks.go
new file mode 100644
index 000000000..a97b1753a
--- /dev/null
+++ b/pkg/sentry/fsimpl/proc/tasks.go
@@ -0,0 +1,235 @@
+// 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/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 (
+ 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
+
+ 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
+}
+
+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": 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),
+ "meminfo": newDentry(root, inoGen.NextIno(), 0444, &meminfoData{}),
+ "mounts": kernfs.NewStaticSymlink(root, inoGen.NextIno(), "self/mounts"),
+ "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(), 0444, pidns).VFSDentry(),
+ threadSelfSymlink: newThreadSelfSymlink(root, inoGen.NextIno(), 0444, pidns).VFSDentry(),
+ }
+ 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)
+ return taskDentry.VFSDentry(), nil
+}
+
+// Valid implements kernfs.inodeDynamicLookup.
+func (i *tasksInode) Valid(ctx context.Context) bool {
+ return true
+}
+
+// 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 !cb.Handle(dirent) {
+ return offset, nil
+ }
+ offset++
+ }
+ if offset == FIRST_PROCESS_ENTRY+1 {
+ dirent := vfs.Dirent{
+ Name: threadSelfName,
+ Type: linux.DT_LNK,
+ Ino: i.inoGen.NextIno(),
+ NextOff: offset + 1,
+ }
+ if !cb.Handle(dirent) {
+ return offset, nil
+ }
+ 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 !cb.Handle(dirent) {
+ return offset, nil
+ }
+ offset++
+ }
+ return maxTaskID, 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
+}
+
+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))
+}