From 2cc0fd42f462f3942230c4b33ca2825e2a28765d Mon Sep 17 00:00:00 2001 From: Fabricio Voznika Date: Fri, 24 Apr 2020 11:43:49 -0700 Subject: Fixes for procfs - Return ENOENT for /proc/[pid]/task if task is zoombied or terminated - Allow directory to be Seek() to the end - Construct synthetic files for /proc/[pid]/ns/* - Changed GenericDirectoryFD.Init to not register with FileDescription, otherwise other implementation cannot change behavior. Updates #1195,1193 PiperOrigin-RevId: 308294649 --- pkg/sentry/fsimpl/proc/subtasks.go | 49 +++++++++++++++++++++- pkg/sentry/fsimpl/proc/task.go | 7 +++- pkg/sentry/fsimpl/proc/task_fds.go | 14 ++++--- pkg/sentry/fsimpl/proc/task_files.go | 76 +++++++++++++++++++++++++++++++++-- pkg/sentry/fsimpl/proc/tasks.go | 6 ++- pkg/sentry/fsimpl/proc/tasks_files.go | 4 +- 6 files changed, 140 insertions(+), 16 deletions(-) (limited to 'pkg/sentry/fsimpl/proc') diff --git a/pkg/sentry/fsimpl/proc/subtasks.go b/pkg/sentry/fsimpl/proc/subtasks.go index a21313666..28ec2484a 100644 --- a/pkg/sentry/fsimpl/proc/subtasks.go +++ b/pkg/sentry/fsimpl/proc/subtasks.go @@ -88,6 +88,9 @@ func (i *subtasksInode) IterDirents(ctx context.Context, cb vfs.IterDirentsCallb 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 { @@ -110,10 +113,52 @@ func (i *subtasksInode) IterDirents(ctx context.Context, cb vfs.IterDirentsCallb 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.FileDecriptionImpl.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(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd := &kernfs.GenericDirectoryFD{} - fd.Init(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + fd := &subtasksFD{task: i.task} + if err := fd.Init(&i.OrderedChildren, &opts); 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 } diff --git a/pkg/sentry/fsimpl/proc/task.go b/pkg/sentry/fsimpl/proc/task.go index 888afc0fd..e2790d35b 100644 --- a/pkg/sentry/fsimpl/proc/task.go +++ b/pkg/sentry/fsimpl/proc/task.go @@ -44,6 +44,7 @@ type taskInode struct { var _ kernfs.Inode = (*taskInode)(nil) func newTaskInode(inoGen InoGenerator, task *kernel.Task, pidns *kernel.PIDNamespace, isThreadGroup bool, cgroupControllers map[string]string) *kernfs.Dentry { + // TODO(gvisor.dev/issue/164): Fail with ESRCH if task exited. contents := map[string]*kernfs.Dentry{ "auxv": newTaskOwnedFile(task, inoGen.NextIno(), 0444, &auxvData{task: task}), "cmdline": newTaskOwnedFile(task, inoGen.NextIno(), 0444, &cmdlineData{task: task, arg: cmdlineDataArg}), @@ -102,8 +103,10 @@ func (i *taskInode) Valid(ctx context.Context) bool { // Open implements kernfs.Inode. func (i *taskInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd := &kernfs.GenericDirectoryFD{} - fd.Init(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + if err != nil { + return nil, err + } return fd.VFSFileDescription(), nil } diff --git a/pkg/sentry/fsimpl/proc/task_fds.go b/pkg/sentry/fsimpl/proc/task_fds.go index 046265eca..a7622f1b6 100644 --- a/pkg/sentry/fsimpl/proc/task_fds.go +++ b/pkg/sentry/fsimpl/proc/task_fds.go @@ -143,8 +143,10 @@ func (i *fdDirInode) Lookup(ctx context.Context, name string) (*vfs.Dentry, erro // Open implements kernfs.Inode. func (i *fdDirInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd := &kernfs.GenericDirectoryFD{} - fd.Init(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + if err != nil { + return nil, err + } return fd.VFSFileDescription(), nil } @@ -207,7 +209,7 @@ func (s *fdSymlink) Readlink(ctx context.Context) (string, error) { return s.task.Kernel().VFS().PathnameWithDeleted(ctx, root, file.VirtualDentry()) } -func (s *fdSymlink) Getlink(ctx context.Context) (vfs.VirtualDentry, string, error) { +func (s *fdSymlink) Getlink(ctx context.Context, mnt *vfs.Mount) (vfs.VirtualDentry, string, error) { file, _ := getTaskFD(s.task, s.fd) if file == nil { return vfs.VirtualDentry{}, "", syserror.ENOENT @@ -268,8 +270,10 @@ func (i *fdInfoDirInode) Lookup(ctx context.Context, name string) (*vfs.Dentry, // Open implements kernfs.Inode. func (i *fdInfoDirInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd := &kernfs.GenericDirectoryFD{} - fd.Init(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + if err != nil { + return nil, err + } return fd.VFSFileDescription(), nil } diff --git a/pkg/sentry/fsimpl/proc/task_files.go b/pkg/sentry/fsimpl/proc/task_files.go index f3173e197..410cc3552 100644 --- a/pkg/sentry/fsimpl/proc/task_files.go +++ b/pkg/sentry/fsimpl/proc/task_files.go @@ -622,7 +622,7 @@ func (s *exeSymlink) Readlink(ctx context.Context) (string, error) { } // Getlink implements kernfs.Inode.Getlink. -func (s *exeSymlink) Getlink(ctx context.Context) (vfs.VirtualDentry, string, error) { +func (s *exeSymlink) Getlink(ctx context.Context, _ *vfs.Mount) (vfs.VirtualDentry, string, error) { if !kernel.ContextCanTrace(ctx, s.task, false) { return vfs.VirtualDentry{}, "", syserror.EACCES } @@ -754,9 +754,79 @@ func (s *namespaceSymlink) Readlink(ctx context.Context) (string, error) { } // Getlink implements Inode.Getlink. -func (s *namespaceSymlink) Getlink(ctx context.Context) (vfs.VirtualDentry, string, error) { +func (s *namespaceSymlink) Getlink(ctx context.Context, mnt *vfs.Mount) (vfs.VirtualDentry, string, error) { if err := checkTaskState(s.task); err != nil { return vfs.VirtualDentry{}, "", err } - return s.StaticSymlink.Getlink(ctx) + + // Create a synthetic inode to represent the namespace. + dentry := &kernfs.Dentry{} + dentry.Init(&namespaceInode{}) + vd := vfs.MakeVirtualDentry(mnt, dentry.VFSDentry()) + vd.IncRef() + dentry.DecRef() + return vd, "", nil +} + +// namespaceInode is a synthetic inode created to represent a namespace in +// /proc/[pid]/ns/*. +type namespaceInode struct { + kernfs.InodeAttrs + kernfs.InodeNoopRefCount + kernfs.InodeNotDirectory + kernfs.InodeNotSymlink +} + +var _ kernfs.Inode = (*namespaceInode)(nil) + +// Init initializes a namespace inode. +func (i *namespaceInode) Init(creds *auth.Credentials, ino uint64, perm linux.FileMode) { + if perm&^linux.PermissionsMask != 0 { + panic(fmt.Sprintf("Only permission mask must be set: %x", perm&linux.PermissionsMask)) + } + i.InodeAttrs.Init(creds, ino, linux.ModeRegular|perm) +} + +// Open implements Inode.Open. +func (i *namespaceInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + fd := &namespaceFD{inode: i} + i.IncRef() + if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{}); err != nil { + return nil, err + } + return &fd.vfsfd, nil +} + +// namespace FD is a synthetic file that represents a namespace in +// /proc/[pid]/ns/*. +type namespaceFD struct { + vfs.FileDescriptionDefaultImpl + + vfsfd vfs.FileDescription + inode *namespaceInode +} + +var _ vfs.FileDescriptionImpl = (*namespaceFD)(nil) + +// Stat implements FileDescriptionImpl. +func (fd *namespaceFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { + vfs := fd.vfsfd.VirtualDentry().Mount().Filesystem() + return fd.inode.Stat(vfs, opts) +} + +// SetStat implements FileDescriptionImpl. +func (fd *namespaceFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) error { + vfs := fd.vfsfd.VirtualDentry().Mount().Filesystem() + creds := auth.CredentialsFromContext(ctx) + return fd.inode.SetStat(ctx, vfs, creds, opts) +} + +// Release implements FileDescriptionImpl. +func (fd *namespaceFD) Release() { + fd.inode.DecRef() +} + +// OnClose implements FileDescriptionImpl. +func (*namespaceFD) OnClose(context.Context) error { + return nil } diff --git a/pkg/sentry/fsimpl/proc/tasks.go b/pkg/sentry/fsimpl/proc/tasks.go index 9f2ef8200..26518ed03 100644 --- a/pkg/sentry/fsimpl/proc/tasks.go +++ b/pkg/sentry/fsimpl/proc/tasks.go @@ -202,8 +202,10 @@ func (i *tasksInode) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback // 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) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + if err != nil { + return nil, err + } return fd.VFSFileDescription(), nil } diff --git a/pkg/sentry/fsimpl/proc/tasks_files.go b/pkg/sentry/fsimpl/proc/tasks_files.go index 4621e2de0..92007df81 100644 --- a/pkg/sentry/fsimpl/proc/tasks_files.go +++ b/pkg/sentry/fsimpl/proc/tasks_files.go @@ -63,7 +63,7 @@ func (s *selfSymlink) Readlink(ctx context.Context) (string, error) { return strconv.FormatUint(uint64(tgid), 10), nil } -func (s *selfSymlink) Getlink(ctx context.Context) (vfs.VirtualDentry, string, error) { +func (s *selfSymlink) Getlink(ctx context.Context, _ *vfs.Mount) (vfs.VirtualDentry, string, error) { target, err := s.Readlink(ctx) return vfs.VirtualDentry{}, target, err } @@ -106,7 +106,7 @@ func (s *threadSelfSymlink) Readlink(ctx context.Context) (string, error) { return fmt.Sprintf("%d/task/%d", tgid, tid), nil } -func (s *threadSelfSymlink) Getlink(ctx context.Context) (vfs.VirtualDentry, string, error) { +func (s *threadSelfSymlink) Getlink(ctx context.Context, _ *vfs.Mount) (vfs.VirtualDentry, string, error) { target, err := s.Readlink(ctx) return vfs.VirtualDentry{}, target, err } -- cgit v1.2.3