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// Copyright 2020 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 vfs2
import (
"bytes"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/gohacks"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/hostarch"
)
// ListXattr implements Linux syscall listxattr(2).
func ListXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return listxattr(t, args, followFinalSymlink)
}
// Llistxattr implements Linux syscall llistxattr(2).
func Llistxattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return listxattr(t, args, nofollowFinalSymlink)
}
func listxattr(t *kernel.Task, args arch.SyscallArguments, shouldFollowFinalSymlink shouldFollowFinalSymlink) (uintptr, *kernel.SyscallControl, error) {
pathAddr := args[0].Pointer()
listAddr := args[1].Pointer()
size := args[2].SizeT()
path, err := copyInPath(t, pathAddr)
if err != nil {
return 0, nil, err
}
tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, shouldFollowFinalSymlink)
if err != nil {
return 0, nil, err
}
defer tpop.Release(t)
names, err := t.Kernel().VFS().ListXattrAt(t, t.Credentials(), &tpop.pop, uint64(size))
if err != nil {
return 0, nil, err
}
n, err := copyOutXattrNameList(t, listAddr, size, names)
if err != nil {
return 0, nil, err
}
return uintptr(n), nil, nil
}
// Flistxattr implements Linux syscall flistxattr(2).
func Flistxattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
listAddr := args[1].Pointer()
size := args[2].SizeT()
file := t.GetFileVFS2(fd)
if file == nil {
return 0, nil, linuxerr.EBADF
}
defer file.DecRef(t)
names, err := file.ListXattr(t, uint64(size))
if err != nil {
return 0, nil, err
}
n, err := copyOutXattrNameList(t, listAddr, size, names)
if err != nil {
return 0, nil, err
}
return uintptr(n), nil, nil
}
// GetXattr implements Linux syscall getxattr(2).
func GetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return getxattr(t, args, followFinalSymlink)
}
// Lgetxattr implements Linux syscall lgetxattr(2).
func Lgetxattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return getxattr(t, args, nofollowFinalSymlink)
}
func getxattr(t *kernel.Task, args arch.SyscallArguments, shouldFollowFinalSymlink shouldFollowFinalSymlink) (uintptr, *kernel.SyscallControl, error) {
pathAddr := args[0].Pointer()
nameAddr := args[1].Pointer()
valueAddr := args[2].Pointer()
size := args[3].SizeT()
path, err := copyInPath(t, pathAddr)
if err != nil {
return 0, nil, err
}
tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, shouldFollowFinalSymlink)
if err != nil {
return 0, nil, err
}
defer tpop.Release(t)
name, err := copyInXattrName(t, nameAddr)
if err != nil {
return 0, nil, err
}
value, err := t.Kernel().VFS().GetXattrAt(t, t.Credentials(), &tpop.pop, &vfs.GetXattrOptions{
Name: name,
Size: uint64(size),
})
if err != nil {
return 0, nil, err
}
n, err := copyOutXattrValue(t, valueAddr, size, value)
if err != nil {
return 0, nil, err
}
return uintptr(n), nil, nil
}
// Fgetxattr implements Linux syscall fgetxattr(2).
func Fgetxattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
nameAddr := args[1].Pointer()
valueAddr := args[2].Pointer()
size := args[3].SizeT()
file := t.GetFileVFS2(fd)
if file == nil {
return 0, nil, linuxerr.EBADF
}
defer file.DecRef(t)
name, err := copyInXattrName(t, nameAddr)
if err != nil {
return 0, nil, err
}
value, err := file.GetXattr(t, &vfs.GetXattrOptions{Name: name, Size: uint64(size)})
if err != nil {
return 0, nil, err
}
n, err := copyOutXattrValue(t, valueAddr, size, value)
if err != nil {
return 0, nil, err
}
return uintptr(n), nil, nil
}
// SetXattr implements Linux syscall setxattr(2).
func SetXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return 0, nil, setxattr(t, args, followFinalSymlink)
}
// Lsetxattr implements Linux syscall lsetxattr(2).
func Lsetxattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return 0, nil, setxattr(t, args, nofollowFinalSymlink)
}
func setxattr(t *kernel.Task, args arch.SyscallArguments, shouldFollowFinalSymlink shouldFollowFinalSymlink) error {
pathAddr := args[0].Pointer()
nameAddr := args[1].Pointer()
valueAddr := args[2].Pointer()
size := args[3].SizeT()
flags := args[4].Int()
if flags&^(linux.XATTR_CREATE|linux.XATTR_REPLACE) != 0 {
return linuxerr.EINVAL
}
path, err := copyInPath(t, pathAddr)
if err != nil {
return err
}
tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, shouldFollowFinalSymlink)
if err != nil {
return err
}
defer tpop.Release(t)
name, err := copyInXattrName(t, nameAddr)
if err != nil {
return err
}
value, err := copyInXattrValue(t, valueAddr, size)
if err != nil {
return err
}
return t.Kernel().VFS().SetXattrAt(t, t.Credentials(), &tpop.pop, &vfs.SetXattrOptions{
Name: name,
Value: value,
Flags: uint32(flags),
})
}
// Fsetxattr implements Linux syscall fsetxattr(2).
func Fsetxattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
nameAddr := args[1].Pointer()
valueAddr := args[2].Pointer()
size := args[3].SizeT()
flags := args[4].Int()
if flags&^(linux.XATTR_CREATE|linux.XATTR_REPLACE) != 0 {
return 0, nil, linuxerr.EINVAL
}
file := t.GetFileVFS2(fd)
if file == nil {
return 0, nil, linuxerr.EBADF
}
defer file.DecRef(t)
name, err := copyInXattrName(t, nameAddr)
if err != nil {
return 0, nil, err
}
value, err := copyInXattrValue(t, valueAddr, size)
if err != nil {
return 0, nil, err
}
return 0, nil, file.SetXattr(t, &vfs.SetXattrOptions{
Name: name,
Value: value,
Flags: uint32(flags),
})
}
// RemoveXattr implements Linux syscall removexattr(2).
func RemoveXattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return 0, nil, removexattr(t, args, followFinalSymlink)
}
// Lremovexattr implements Linux syscall lremovexattr(2).
func Lremovexattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return 0, nil, removexattr(t, args, nofollowFinalSymlink)
}
func removexattr(t *kernel.Task, args arch.SyscallArguments, shouldFollowFinalSymlink shouldFollowFinalSymlink) error {
pathAddr := args[0].Pointer()
nameAddr := args[1].Pointer()
path, err := copyInPath(t, pathAddr)
if err != nil {
return err
}
tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, shouldFollowFinalSymlink)
if err != nil {
return err
}
defer tpop.Release(t)
name, err := copyInXattrName(t, nameAddr)
if err != nil {
return err
}
return t.Kernel().VFS().RemoveXattrAt(t, t.Credentials(), &tpop.pop, name)
}
// Fremovexattr implements Linux syscall fremovexattr(2).
func Fremovexattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
nameAddr := args[1].Pointer()
file := t.GetFileVFS2(fd)
if file == nil {
return 0, nil, linuxerr.EBADF
}
defer file.DecRef(t)
name, err := copyInXattrName(t, nameAddr)
if err != nil {
return 0, nil, err
}
return 0, nil, file.RemoveXattr(t, name)
}
func copyInXattrName(t *kernel.Task, nameAddr hostarch.Addr) (string, error) {
name, err := t.CopyInString(nameAddr, linux.XATTR_NAME_MAX+1)
if err != nil {
if linuxerr.Equals(linuxerr.ENAMETOOLONG, err) {
return "", syserror.ERANGE
}
return "", err
}
if len(name) == 0 {
return "", syserror.ERANGE
}
return name, nil
}
func copyOutXattrNameList(t *kernel.Task, listAddr hostarch.Addr, size uint, names []string) (int, error) {
if size > linux.XATTR_LIST_MAX {
size = linux.XATTR_LIST_MAX
}
var buf bytes.Buffer
for _, name := range names {
buf.WriteString(name)
buf.WriteByte(0)
}
if size == 0 {
// Return the size that would be required to accomodate the list.
return buf.Len(), nil
}
if buf.Len() > int(size) {
if size >= linux.XATTR_LIST_MAX {
return 0, linuxerr.E2BIG
}
return 0, syserror.ERANGE
}
return t.CopyOutBytes(listAddr, buf.Bytes())
}
func copyInXattrValue(t *kernel.Task, valueAddr hostarch.Addr, size uint) (string, error) {
if size > linux.XATTR_SIZE_MAX {
return "", linuxerr.E2BIG
}
buf := make([]byte, size)
if _, err := t.CopyInBytes(valueAddr, buf); err != nil {
return "", err
}
return gohacks.StringFromImmutableBytes(buf), nil
}
func copyOutXattrValue(t *kernel.Task, valueAddr hostarch.Addr, size uint, value string) (int, error) {
if size > linux.XATTR_SIZE_MAX {
size = linux.XATTR_SIZE_MAX
}
if size == 0 {
// Return the size that would be required to accomodate the value.
return len(value), nil
}
if len(value) > int(size) {
if size >= linux.XATTR_SIZE_MAX {
return 0, linuxerr.E2BIG
}
return 0, syserror.ERANGE
}
return t.CopyOutBytes(valueAddr, gohacks.ImmutableBytesFromString(value))
}
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