Merge branch 'master' into ip-forwarding

- Merges aleksej-paschenko's with HEAD
- Adds vfs2 support for ip_forward

1 files changed, 334 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..01e0f9010
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/filesystem.go
@@ -0,0 +1,334 @@
+// 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(t)
+
+	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(t)
+
+	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(t)
+	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, linux.FileMode(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, linux.FileMode(mode), dev)
+}
+
+func mknodat(t *kernel.Task, dirfd int32, addr usermem.Addr, mode linux.FileMode, 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(t)
+
+	// "Zero file type is equivalent to type S_IFREG." - mknod(2)
+	if mode.FileType() == 0 {
+		mode |= linux.ModeRegular
+	}
+	major, minor := linux.DecodeDeviceID(dev)
+	return t.Kernel().VFS().MknodAt(t, t.Credentials(), &tpop.pop, &vfs.MknodOptions{
+		Mode:     mode &^ linux.FileMode(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(t)
+
+	file, err := t.Kernel().VFS().OpenAt(t, t.Credentials(), &tpop.pop, &vfs.OpenOptions{
+		Flags: flags | linux.O_LARGEFILE,
+		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(t)
+
+	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(t)
+
+	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(t)
+
+	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, nofollowFinalSymlink)
+	if err != nil {
+		return err
+	}
+	defer tpop.Release(t)
+	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(t)
+	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
+	}
+	if len(target) == 0 {
+		return syserror.ENOENT
+	}
+	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(t)
+	return t.Kernel().VFS().SymlinkAt(t, t.Credentials(), &tpop.pop, target)
+}