252 lines
7.3 KiB
Go
252 lines
7.3 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package proc implements a partial in-memory file system for profs.
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package proc
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import (
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"fmt"
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"sort"
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"strconv"
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"gvisor.dev/gvisor/pkg/sentry/context"
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"gvisor.dev/gvisor/pkg/sentry/fs"
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"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
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"gvisor.dev/gvisor/pkg/sentry/fs/proc/device"
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"gvisor.dev/gvisor/pkg/sentry/fs/proc/seqfile"
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"gvisor.dev/gvisor/pkg/sentry/fs/ramfs"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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"gvisor.dev/gvisor/pkg/sentry/socket/rpcinet"
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"gvisor.dev/gvisor/pkg/syserror"
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)
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// proc is a root proc node.
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//
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// +stateify savable
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type proc struct {
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ramfs.Dir
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// k is the Kernel containing this proc node.
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k *kernel.Kernel
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// pidns is the PID namespace of the task that mounted the proc filesystem
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// that this node represents.
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pidns *kernel.PIDNamespace
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// cgroupControllers is a map of controller name to directory in the
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// cgroup hierarchy. These controllers are immutable and will be listed
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// in /proc/pid/cgroup if not nil.
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cgroupControllers map[string]string
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}
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// New returns the root node of a partial simple procfs.
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func New(ctx context.Context, msrc *fs.MountSource, cgroupControllers map[string]string) (*fs.Inode, error) {
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k := kernel.KernelFromContext(ctx)
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if k == nil {
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return nil, fmt.Errorf("procfs requires a kernel")
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}
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pidns := kernel.PIDNamespaceFromContext(ctx)
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if pidns == nil {
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return nil, fmt.Errorf("procfs requires a PID namespace")
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}
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// Note that these are just the static members. There are dynamic
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// members populated in Readdir and Lookup below.
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contents := map[string]*fs.Inode{
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"cpuinfo": newCPUInfo(ctx, msrc),
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"filesystems": seqfile.NewSeqFileInode(ctx, &filesystemsData{}, msrc),
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"loadavg": seqfile.NewSeqFileInode(ctx, &loadavgData{}, msrc),
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"meminfo": seqfile.NewSeqFileInode(ctx, &meminfoData{k}, msrc),
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"mounts": newProcInode(ctx, ramfs.NewSymlink(ctx, fs.RootOwner, "self/mounts"), msrc, fs.Symlink, nil),
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"self": newSelf(ctx, pidns, msrc),
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"stat": seqfile.NewSeqFileInode(ctx, &statData{k}, msrc),
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"thread-self": newThreadSelf(ctx, pidns, msrc),
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"uptime": newUptime(ctx, msrc),
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"version": seqfile.NewSeqFileInode(ctx, &versionData{k}, msrc),
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}
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// Construct the proc InodeOperations.
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p := &proc{
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Dir: *ramfs.NewDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555)),
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k: k,
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pidns: pidns,
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cgroupControllers: cgroupControllers,
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}
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// Add more contents that need proc to be initialized.
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p.AddChild(ctx, "sys", p.newSysDir(ctx, msrc))
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// If we're using rpcinet we will let it manage /proc/net.
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if _, ok := p.k.NetworkStack().(*rpcinet.Stack); ok {
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p.AddChild(ctx, "net", newRPCInetProcNet(ctx, msrc))
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} else {
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p.AddChild(ctx, "net", p.newNetDir(ctx, k, msrc))
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}
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return newProcInode(ctx, p, msrc, fs.SpecialDirectory, nil), nil
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}
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// self is a magical link.
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//
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// +stateify savable
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type self struct {
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ramfs.Symlink
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pidns *kernel.PIDNamespace
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}
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// newSelf returns a new "self" node.
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func newSelf(ctx context.Context, pidns *kernel.PIDNamespace, msrc *fs.MountSource) *fs.Inode {
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s := &self{
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Symlink: *ramfs.NewSymlink(ctx, fs.RootOwner, ""),
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pidns: pidns,
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}
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return newProcInode(ctx, s, msrc, fs.Symlink, nil)
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}
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// newThreadSelf returns a new "threadSelf" node.
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func newThreadSelf(ctx context.Context, pidns *kernel.PIDNamespace, msrc *fs.MountSource) *fs.Inode {
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s := &threadSelf{
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Symlink: *ramfs.NewSymlink(ctx, fs.RootOwner, ""),
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pidns: pidns,
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}
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return newProcInode(ctx, s, msrc, fs.Symlink, nil)
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}
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// Readlink implements fs.InodeOperations.Readlink.
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func (s *self) Readlink(ctx context.Context, inode *fs.Inode) (string, error) {
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if t := kernel.TaskFromContext(ctx); t != nil {
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tgid := s.pidns.IDOfThreadGroup(t.ThreadGroup())
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if tgid == 0 {
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return "", syserror.ENOENT
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}
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return strconv.FormatUint(uint64(tgid), 10), nil
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}
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// Who is reading this link?
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return "", syserror.EINVAL
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}
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// threadSelf is more magical than "self" link.
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//
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// +stateify savable
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type threadSelf struct {
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ramfs.Symlink
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pidns *kernel.PIDNamespace
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}
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// Readlink implements fs.InodeOperations.Readlink.
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func (s *threadSelf) Readlink(ctx context.Context, inode *fs.Inode) (string, error) {
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if t := kernel.TaskFromContext(ctx); t != nil {
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tgid := s.pidns.IDOfThreadGroup(t.ThreadGroup())
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tid := s.pidns.IDOfTask(t)
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if tid == 0 || tgid == 0 {
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return "", syserror.ENOENT
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}
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return fmt.Sprintf("%d/task/%d", tgid, tid), nil
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}
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// Who is reading this link?
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return "", syserror.EINVAL
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}
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// Lookup loads an Inode at name into a Dirent.
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func (p *proc) Lookup(ctx context.Context, dir *fs.Inode, name string) (*fs.Dirent, error) {
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dirent, walkErr := p.Dir.Lookup(ctx, dir, name)
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if walkErr == nil {
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return dirent, nil
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}
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// Try to lookup a corresponding task.
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tid, err := strconv.ParseUint(name, 10, 64)
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if err != nil {
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// Ignore the parse error and return the original.
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return nil, walkErr
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}
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// Grab the other task.
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otherTask := p.pidns.TaskWithID(kernel.ThreadID(tid))
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if otherTask == nil {
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// Per above.
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return nil, walkErr
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}
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// Wrap it in a taskDir.
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td := p.newTaskDir(otherTask, dir.MountSource, true)
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return fs.NewDirent(ctx, td, name), nil
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}
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// GetFile implements fs.InodeOperations.
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func (p *proc) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
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return fs.NewFile(ctx, dirent, flags, &rootProcFile{iops: p}), nil
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}
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// rootProcFile implements fs.FileOperations for the proc directory.
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//
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// +stateify savable
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type rootProcFile struct {
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fsutil.DirFileOperations `state:"nosave"`
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fsutil.FileUseInodeUnstableAttr `state:"nosave"`
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iops *proc
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}
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var _ fs.FileOperations = (*rootProcFile)(nil)
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// Readdir implements fs.FileOperations.Readdir.
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func (rpf *rootProcFile) Readdir(ctx context.Context, file *fs.File, ser fs.DentrySerializer) (int64, error) {
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offset := file.Offset()
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dirCtx := &fs.DirCtx{
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Serializer: ser,
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}
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// Get normal directory contents from ramfs dir.
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names, m := rpf.iops.Dir.Children()
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// Add dot and dotdot.
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root := fs.RootFromContext(ctx)
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if root != nil {
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defer root.DecRef()
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}
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dot, dotdot := file.Dirent.GetDotAttrs(root)
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names = append(names, ".", "..")
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m["."] = dot
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m[".."] = dotdot
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// Collect tasks.
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// Per linux we only include it in directory listings if it's the leader.
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// But for whatever crazy reason, you can still walk to the given node.
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for _, tg := range rpf.iops.pidns.ThreadGroups() {
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if leader := tg.Leader(); leader != nil {
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name := strconv.FormatUint(uint64(tg.ID()), 10)
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m[name] = fs.GenericDentAttr(fs.SpecialDirectory, device.ProcDevice)
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names = append(names, name)
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}
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}
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if offset >= int64(len(m)) {
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return offset, nil
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}
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sort.Strings(names)
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names = names[offset:]
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for _, name := range names {
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if err := dirCtx.DirEmit(name, m[name]); err != nil {
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return offset, err
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}
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offset++
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}
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return offset, nil
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}
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