291 lines
8.9 KiB
Go
291 lines
8.9 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 linux
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import (
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"gvisor.dev/gvisor/pkg/abi/linux"
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"gvisor.dev/gvisor/pkg/errors/linuxerr"
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"gvisor.dev/gvisor/pkg/hostarch"
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"gvisor.dev/gvisor/pkg/sentry/arch"
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"gvisor.dev/gvisor/pkg/sentry/fs"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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)
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// LINT.IfChange
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// Stat implements linux syscall stat(2).
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func Stat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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addr := args[0].Pointer()
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statAddr := args[1].Pointer()
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path, dirPath, err := copyInPath(t, addr, false /* allowEmpty */)
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if err != nil {
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return 0, nil, err
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}
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return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
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return stat(t, d, dirPath, statAddr)
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})
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}
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// Fstatat implements linux syscall newfstatat, i.e. fstatat(2).
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func Fstatat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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addr := args[1].Pointer()
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statAddr := args[2].Pointer()
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flags := args[3].Int()
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path, dirPath, err := copyInPath(t, addr, flags&linux.AT_EMPTY_PATH != 0)
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if err != nil {
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return 0, nil, err
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}
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if path == "" {
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// Annoying. What's wrong with fstat?
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, linuxerr.EBADF
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}
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defer file.DecRef(t)
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return 0, nil, fstat(t, file, statAddr)
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}
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// If the path ends in a slash (i.e. dirPath is true) or if AT_SYMLINK_NOFOLLOW is unset,
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// then we must resolve the final component.
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resolve := dirPath || flags&linux.AT_SYMLINK_NOFOLLOW == 0
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return 0, nil, fileOpOn(t, fd, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
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return stat(t, d, dirPath, statAddr)
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})
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}
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// Lstat implements linux syscall lstat(2).
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func Lstat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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addr := args[0].Pointer()
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statAddr := args[1].Pointer()
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path, dirPath, err := copyInPath(t, addr, false /* allowEmpty */)
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if err != nil {
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return 0, nil, err
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}
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// If the path ends in a slash (i.e. dirPath is true), then we *do*
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// want to resolve the final component.
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resolve := dirPath
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return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
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return stat(t, d, dirPath, statAddr)
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})
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}
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// Fstat implements linux syscall fstat(2).
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func Fstat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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statAddr := args[1].Pointer()
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, linuxerr.EBADF
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}
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defer file.DecRef(t)
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return 0, nil, fstat(t, file, statAddr)
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}
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// stat implements stat from the given *fs.Dirent.
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func stat(t *kernel.Task, d *fs.Dirent, dirPath bool, statAddr hostarch.Addr) error {
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if dirPath && !fs.IsDir(d.Inode.StableAttr) {
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return linuxerr.ENOTDIR
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}
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uattr, err := d.Inode.UnstableAttr(t)
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if err != nil {
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return err
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}
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s := statFromAttrs(t, d.Inode.StableAttr, uattr)
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_, err = s.CopyOut(t, statAddr)
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return err
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}
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// fstat implements fstat for the given *fs.File.
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func fstat(t *kernel.Task, f *fs.File, statAddr hostarch.Addr) error {
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uattr, err := f.UnstableAttr(t)
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if err != nil {
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return err
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}
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s := statFromAttrs(t, f.Dirent.Inode.StableAttr, uattr)
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_, err = s.CopyOut(t, statAddr)
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return err
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}
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// Statx implements linux syscall statx(2).
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func Statx(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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pathAddr := args[1].Pointer()
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flags := args[2].Int()
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mask := args[3].Uint()
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statxAddr := args[4].Pointer()
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if mask&linux.STATX__RESERVED != 0 {
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return 0, nil, linuxerr.EINVAL
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}
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if flags&^(linux.AT_SYMLINK_NOFOLLOW|linux.AT_EMPTY_PATH|linux.AT_STATX_SYNC_TYPE) != 0 {
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return 0, nil, linuxerr.EINVAL
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}
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if flags&linux.AT_STATX_SYNC_TYPE == linux.AT_STATX_SYNC_TYPE {
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return 0, nil, linuxerr.EINVAL
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}
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path, dirPath, err := copyInPath(t, pathAddr, flags&linux.AT_EMPTY_PATH != 0)
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if err != nil {
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return 0, nil, err
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}
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if path == "" {
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, linuxerr.EBADF
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}
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defer file.DecRef(t)
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uattr, err := file.UnstableAttr(t)
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if err != nil {
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return 0, nil, err
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}
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return 0, nil, statx(t, file.Dirent.Inode.StableAttr, uattr, statxAddr)
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}
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resolve := dirPath || flags&linux.AT_SYMLINK_NOFOLLOW == 0
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return 0, nil, fileOpOn(t, fd, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
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if dirPath && !fs.IsDir(d.Inode.StableAttr) {
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return linuxerr.ENOTDIR
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}
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uattr, err := d.Inode.UnstableAttr(t)
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if err != nil {
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return err
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}
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return statx(t, d.Inode.StableAttr, uattr, statxAddr)
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})
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}
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func statx(t *kernel.Task, sattr fs.StableAttr, uattr fs.UnstableAttr, statxAddr hostarch.Addr) error {
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// "[T]he kernel may return fields that weren't requested and may fail to
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// return fields that were requested, depending on what the backing
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// filesystem supports.
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// [...]
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// A filesystem may also fill in fields that the caller didn't ask for
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// if it has values for them available and the information is available
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// at no extra cost. If this happens, the corresponding bits will be
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// set in stx_mask." -- statx(2)
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//
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// We fill in all the values we have (which currently does not include
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// btime, see b/135608823), regardless of what the user asked for. The
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// STATX_BASIC_STATS mask indicates that all fields are present except
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// for btime.
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devMajor, devMinor := linux.DecodeDeviceID(uint32(sattr.DeviceID))
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s := linux.Statx{
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// TODO(b/135608823): Support btime, and then change this to
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// STATX_ALL to indicate presence of btime.
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Mask: linux.STATX_BASIC_STATS,
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// No attributes, and none supported.
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Attributes: 0,
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AttributesMask: 0,
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Blksize: uint32(sattr.BlockSize),
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Nlink: uint32(uattr.Links),
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UID: uint32(uattr.Owner.UID.In(t.UserNamespace()).OrOverflow()),
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GID: uint32(uattr.Owner.GID.In(t.UserNamespace()).OrOverflow()),
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Mode: uint16(sattr.Type.LinuxType()) | uint16(uattr.Perms.LinuxMode()),
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Ino: sattr.InodeID,
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Size: uint64(uattr.Size),
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Blocks: uint64(uattr.Usage) / 512,
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Atime: uattr.AccessTime.StatxTimestamp(),
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Ctime: uattr.StatusChangeTime.StatxTimestamp(),
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Mtime: uattr.ModificationTime.StatxTimestamp(),
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RdevMajor: uint32(sattr.DeviceFileMajor),
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RdevMinor: sattr.DeviceFileMinor,
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DevMajor: uint32(devMajor),
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DevMinor: devMinor,
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}
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_, err := s.CopyOut(t, statxAddr)
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return err
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}
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// Statfs implements linux syscall statfs(2).
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func Statfs(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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addr := args[0].Pointer()
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statfsAddr := args[1].Pointer()
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path, _, err := copyInPath(t, addr, false /* allowEmpty */)
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if err != nil {
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return 0, nil, err
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}
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return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
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return statfsImpl(t, d, statfsAddr)
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})
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}
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// Fstatfs implements linux syscall fstatfs(2).
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func Fstatfs(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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statfsAddr := args[1].Pointer()
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, linuxerr.EBADF
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}
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defer file.DecRef(t)
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return 0, nil, statfsImpl(t, file.Dirent, statfsAddr)
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}
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// statfsImpl implements the linux syscall statfs and fstatfs based on a Dirent,
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// copying the statfs structure out to addr on success, otherwise an error is
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// returned.
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func statfsImpl(t *kernel.Task, d *fs.Dirent, addr hostarch.Addr) error {
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info, err := d.Inode.StatFS(t)
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if err != nil {
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return err
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}
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// Construct the statfs structure and copy it out.
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statfs := linux.Statfs{
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Type: info.Type,
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// Treat block size and fragment size as the same, as
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// most consumers of this structure will expect one
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// or the other to be filled in.
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BlockSize: d.Inode.StableAttr.BlockSize,
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Blocks: info.TotalBlocks,
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// We don't have the concept of reserved blocks, so
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// report blocks free the same as available blocks.
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// This is a normal thing for filesystems, to do, see
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// udf, hugetlbfs, tmpfs, among others.
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BlocksFree: info.FreeBlocks,
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BlocksAvailable: info.FreeBlocks,
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Files: info.TotalFiles,
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FilesFree: info.FreeFiles,
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// Same as Linux for simple_statfs, see fs/libfs.c.
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NameLength: linux.NAME_MAX,
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FragmentSize: d.Inode.StableAttr.BlockSize,
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// Leave other fields 0 like simple_statfs does.
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}
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_, err = statfs.CopyOut(t, addr)
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return err
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}
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// LINT.ThenChange(vfs2/stat.go)
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