Port most syscalls to VFS2.

pipe and pipe2 aren't ported, pending a slight rework of pipe FDs for VFS2.
mount and umount2 aren't ported out of temporary laziness. access and faccessat
need additional FSImpl methods to implement properly, but are stubbed to
prevent googletest from CHECK-failing. Other syscalls require additional
plumbing.

Updates #1623

PiperOrigin-RevId: 297188448

1 files changed, 326 insertions, 0 deletions

diff --git a/pkg/sentry/syscalls/linux/vfs2/filesystem.go b/pkg/sentry/syscalls/linux/vfs2/filesystem.go
new file mode 100644
index 000000000..fc5ceea4c
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/filesystem.go
@@ -0,0 +1,326 @@
+// 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 (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"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"
+)
+
+// Link implements Linux syscall link(2).
+func Link(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	oldpathAddr := args[0].Pointer()
+	newpathAddr := args[1].Pointer()
+	return 0, nil, linkat(t, linux.AT_FDCWD, oldpathAddr, linux.AT_FDCWD, newpathAddr, 0 /* flags */)
+}
+
+// Linkat implements Linux syscall linkat(2).
+func Linkat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	olddirfd := args[0].Int()
+	oldpathAddr := args[1].Pointer()
+	newdirfd := args[2].Int()
+	newpathAddr := args[3].Pointer()
+	flags := args[4].Int()
+	return 0, nil, linkat(t, olddirfd, oldpathAddr, newdirfd, newpathAddr, flags)
+}
+
+func linkat(t *kernel.Task, olddirfd int32, oldpathAddr usermem.Addr, newdirfd int32, newpathAddr usermem.Addr, flags int32) error {
+	if flags&^(linux.AT_EMPTY_PATH|linux.AT_SYMLINK_FOLLOW) != 0 {
+		return syserror.EINVAL
+	}
+	if flags&linux.AT_EMPTY_PATH != 0 && !t.HasCapability(linux.CAP_DAC_READ_SEARCH) {
+		return syserror.ENOENT
+	}
+
+	oldpath, err := copyInPath(t, oldpathAddr)
+	if err != nil {
+		return err
+	}
+	oldtpop, err := getTaskPathOperation(t, olddirfd, oldpath, shouldAllowEmptyPath(flags&linux.AT_EMPTY_PATH != 0), shouldFollowFinalSymlink(flags&linux.AT_SYMLINK_FOLLOW != 0))
+	if err != nil {
+		return err
+	}
+	defer oldtpop.Release()
+
+	newpath, err := copyInPath(t, newpathAddr)
+	if err != nil {
+		return err
+	}
+	newtpop, err := getTaskPathOperation(t, newdirfd, newpath, disallowEmptyPath, nofollowFinalSymlink)
+	if err != nil {
+		return err
+	}
+	defer newtpop.Release()
+
+	return t.Kernel().VFS().LinkAt(t, t.Credentials(), &oldtpop.pop, &newtpop.pop)
+}
+
+// Mkdir implements Linux syscall mkdir(2).
+func Mkdir(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	mode := args[1].ModeT()
+	return 0, nil, mkdirat(t, linux.AT_FDCWD, addr, mode)
+}
+
+// Mkdirat implements Linux syscall mkdirat(2).
+func Mkdirat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	dirfd := args[0].Int()
+	addr := args[1].Pointer()
+	mode := args[2].ModeT()
+	return 0, nil, mkdirat(t, dirfd, addr, mode)
+}
+
+func mkdirat(t *kernel.Task, dirfd int32, addr usermem.Addr, mode uint) error {
+	path, err := copyInPath(t, addr)
+	if err != nil {
+		return err
+	}
+	tpop, err := getTaskPathOperation(t, dirfd, path, disallowEmptyPath, nofollowFinalSymlink)
+	if err != nil {
+		return err
+	}
+	defer tpop.Release()
+	return t.Kernel().VFS().MkdirAt(t, t.Credentials(), &tpop.pop, &vfs.MkdirOptions{
+		Mode: linux.FileMode(mode & (0777 | linux.S_ISVTX) &^ t.FSContext().Umask()),
+	})
+}
+
+// Mknod implements Linux syscall mknod(2).
+func Mknod(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	mode := args[1].ModeT()
+	dev := args[2].Uint()
+	return 0, nil, mknodat(t, linux.AT_FDCWD, addr, mode, dev)
+}
+
+// Mknodat implements Linux syscall mknodat(2).
+func Mknodat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	dirfd := args[0].Int()
+	addr := args[1].Pointer()
+	mode := args[2].ModeT()
+	dev := args[3].Uint()
+	return 0, nil, mknodat(t, dirfd, addr, mode, dev)
+}
+
+func mknodat(t *kernel.Task, dirfd int32, addr usermem.Addr, mode uint, dev uint32) error {
+	path, err := copyInPath(t, addr)
+	if err != nil {
+		return err
+	}
+	tpop, err := getTaskPathOperation(t, dirfd, path, disallowEmptyPath, nofollowFinalSymlink)
+	if err != nil {
+		return err
+	}
+	defer tpop.Release()
+	major, minor := linux.DecodeDeviceID(dev)
+	return t.Kernel().VFS().MknodAt(t, t.Credentials(), &tpop.pop, &vfs.MknodOptions{
+		Mode:     linux.FileMode(mode &^ t.FSContext().Umask()),
+		DevMajor: uint32(major),
+		DevMinor: minor,
+	})
+}
+
+// Open implements Linux syscall open(2).
+func Open(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	flags := args[1].Uint()
+	mode := args[2].ModeT()
+	return openat(t, linux.AT_FDCWD, addr, flags, mode)
+}
+
+// Openat implements Linux syscall openat(2).
+func Openat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	dirfd := args[0].Int()
+	addr := args[1].Pointer()
+	flags := args[2].Uint()
+	mode := args[3].ModeT()
+	return openat(t, dirfd, addr, flags, mode)
+}
+
+// Creat implements Linux syscall creat(2).
+func Creat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	mode := args[1].ModeT()
+	return openat(t, linux.AT_FDCWD, addr, linux.O_WRONLY|linux.O_CREAT|linux.O_TRUNC, mode)
+}
+
+func openat(t *kernel.Task, dirfd int32, pathAddr usermem.Addr, flags uint32, mode uint) (uintptr, *kernel.SyscallControl, error) {
+	path, err := copyInPath(t, pathAddr)
+	if err != nil {
+		return 0, nil, err
+	}
+	tpop, err := getTaskPathOperation(t, dirfd, path, disallowEmptyPath, shouldFollowFinalSymlink(flags&linux.O_NOFOLLOW == 0))
+	if err != nil {
+		return 0, nil, err
+	}
+	defer tpop.Release()
+
+	file, err := t.Kernel().VFS().OpenAt(t, t.Credentials(), &tpop.pop, &vfs.OpenOptions{
+		Flags: flags,
+		Mode:  linux.FileMode(mode & (0777 | linux.S_ISUID | linux.S_ISGID | linux.S_ISVTX) &^ t.FSContext().Umask()),
+	})
+	if err != nil {
+		return 0, nil, err
+	}
+	defer file.DecRef()
+
+	fd, err := t.NewFDFromVFS2(0, file, kernel.FDFlags{
+		CloseOnExec: flags&linux.O_CLOEXEC != 0,
+	})
+	return uintptr(fd), nil, err
+}
+
+// Rename implements Linux syscall rename(2).
+func Rename(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	oldpathAddr := args[0].Pointer()
+	newpathAddr := args[1].Pointer()
+	return 0, nil, renameat(t, linux.AT_FDCWD, oldpathAddr, linux.AT_FDCWD, newpathAddr, 0 /* flags */)
+}
+
+// Renameat implements Linux syscall renameat(2).
+func Renameat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	olddirfd := args[0].Int()
+	oldpathAddr := args[1].Pointer()
+	newdirfd := args[2].Int()
+	newpathAddr := args[3].Pointer()
+	return 0, nil, renameat(t, olddirfd, oldpathAddr, newdirfd, newpathAddr, 0 /* flags */)
+}
+
+// Renameat2 implements Linux syscall renameat2(2).
+func Renameat2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	olddirfd := args[0].Int()
+	oldpathAddr := args[1].Pointer()
+	newdirfd := args[2].Int()
+	newpathAddr := args[3].Pointer()
+	flags := args[4].Uint()
+	return 0, nil, renameat(t, olddirfd, oldpathAddr, newdirfd, newpathAddr, flags)
+}
+
+func renameat(t *kernel.Task, olddirfd int32, oldpathAddr usermem.Addr, newdirfd int32, newpathAddr usermem.Addr, flags uint32) error {
+	oldpath, err := copyInPath(t, oldpathAddr)
+	if err != nil {
+		return err
+	}
+	// "If oldpath refers to a symbolic link, the link is renamed" - rename(2)
+	oldtpop, err := getTaskPathOperation(t, olddirfd, oldpath, disallowEmptyPath, nofollowFinalSymlink)
+	if err != nil {
+		return err
+	}
+	defer oldtpop.Release()
+
+	newpath, err := copyInPath(t, newpathAddr)
+	if err != nil {
+		return err
+	}
+	newtpop, err := getTaskPathOperation(t, newdirfd, newpath, disallowEmptyPath, nofollowFinalSymlink)
+	if err != nil {
+		return err
+	}
+	defer newtpop.Release()
+
+	return t.Kernel().VFS().RenameAt(t, t.Credentials(), &oldtpop.pop, &newtpop.pop, &vfs.RenameOptions{
+		Flags: flags,
+	})
+}
+
+// Rmdir implements Linux syscall rmdir(2).
+func Rmdir(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	pathAddr := args[0].Pointer()
+	return 0, nil, rmdirat(t, linux.AT_FDCWD, pathAddr)
+}
+
+func rmdirat(t *kernel.Task, dirfd int32, pathAddr usermem.Addr) error {
+	path, err := copyInPath(t, pathAddr)
+	if err != nil {
+		return err
+	}
+	tpop, err := getTaskPathOperation(t, dirfd, path, disallowEmptyPath, followFinalSymlink)
+	if err != nil {
+		return err
+	}
+	defer tpop.Release()
+	return t.Kernel().VFS().RmdirAt(t, t.Credentials(), &tpop.pop)
+}
+
+// Unlink implements Linux syscall unlink(2).
+func Unlink(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	pathAddr := args[0].Pointer()
+	return 0, nil, unlinkat(t, linux.AT_FDCWD, pathAddr)
+}
+
+func unlinkat(t *kernel.Task, dirfd int32, pathAddr usermem.Addr) error {
+	path, err := copyInPath(t, pathAddr)
+	if err != nil {
+		return err
+	}
+	tpop, err := getTaskPathOperation(t, dirfd, path, disallowEmptyPath, nofollowFinalSymlink)
+	if err != nil {
+		return err
+	}
+	defer tpop.Release()
+	return t.Kernel().VFS().UnlinkAt(t, t.Credentials(), &tpop.pop)
+}
+
+// Unlinkat implements Linux syscall unlinkat(2).
+func Unlinkat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	dirfd := args[0].Int()
+	pathAddr := args[1].Pointer()
+	flags := args[2].Int()
+
+	if flags&^linux.AT_REMOVEDIR != 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	if flags&linux.AT_REMOVEDIR != 0 {
+		return 0, nil, rmdirat(t, dirfd, pathAddr)
+	}
+	return 0, nil, unlinkat(t, dirfd, pathAddr)
+}
+
+// Symlink implements Linux syscall symlink(2).
+func Symlink(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	targetAddr := args[0].Pointer()
+	linkpathAddr := args[1].Pointer()
+	return 0, nil, symlinkat(t, targetAddr, linux.AT_FDCWD, linkpathAddr)
+}
+
+// Symlinkat implements Linux syscall symlinkat(2).
+func Symlinkat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	targetAddr := args[0].Pointer()
+	newdirfd := args[1].Int()
+	linkpathAddr := args[2].Pointer()
+	return 0, nil, symlinkat(t, targetAddr, newdirfd, linkpathAddr)
+}
+
+func symlinkat(t *kernel.Task, targetAddr usermem.Addr, newdirfd int32, linkpathAddr usermem.Addr) error {
+	target, err := t.CopyInString(targetAddr, linux.PATH_MAX)
+	if err != nil {
+		return err
+	}
+	linkpath, err := copyInPath(t, linkpathAddr)
+	if err != nil {
+		return err
+	}
+	tpop, err := getTaskPathOperation(t, newdirfd, linkpath, disallowEmptyPath, nofollowFinalSymlink)
+	if err != nil {
+		return err
+	}
+	defer tpop.Release()
+	return t.Kernel().VFS().SymlinkAt(t, t.Credentials(), &tpop.pop, target)
+}