1 files changed, 353 insertions, 0 deletions
diff --git a/pkg/sentry/syscalls/linux/vfs2/xattr.go b/pkg/sentry/syscalls/linux/vfs2/xattr.go
new file mode 100644
index 000000000..89e9ff4d7
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/xattr.go
@@ -0,0 +1,353 @@
+// 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/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/usermem"
+)
+
+// 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()
+
+	names, err := t.Kernel().VFS().ListxattrAt(t, t.Credentials(), &tpop.pop)
+	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, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	names, err := file.Listxattr(t)
+	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()
+
+	name, err := copyInXattrName(t, nameAddr)
+	if err != nil {
+		return 0, nil, err
+	}
+
+	value, err := t.Kernel().VFS().GetxattrAt(t, t.Credentials(), &tpop.pop, name)
+	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, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	name, err := copyInXattrName(t, nameAddr)
+	if err != nil {
+		return 0, nil, err
+	}
+
+	value, err := file.Getxattr(t, name)
+	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 syserror.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()
+
+	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, syserror.EINVAL
+	}
+
+	file := t.GetFileVFS2(fd)
+	if file == nil {
+		return 0, nil, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	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()
+
+	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, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	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 usermem.Addr) (string, error) {
+	name, err := t.CopyInString(nameAddr, linux.XATTR_NAME_MAX+1)
+	if err != nil {
+		if err == syserror.ENAMETOOLONG {
+			return "", syserror.ERANGE
+		}
+		return "", err
+	}
+	if len(name) == 0 {
+		return "", syserror.ERANGE
+	}
+	return name, nil
+}
+
+func copyOutXattrNameList(t *kernel.Task, listAddr usermem.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, syserror.E2BIG
+		}
+		return 0, syserror.ERANGE
+	}
+	return t.CopyOutBytes(listAddr, buf.Bytes())
+}
+
+func copyInXattrValue(t *kernel.Task, valueAddr usermem.Addr, size uint) (string, error) {
+	if size > linux.XATTR_SIZE_MAX {
+		return "", syserror.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 usermem.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, syserror.E2BIG
+		}
+		return 0, syserror.ERANGE
+	}
+	return t.CopyOutBytes(valueAddr, gohacks.ImmutableBytesFromString(value))
+}