1 files changed, 131 insertions, 0 deletions
diff --git a/pkg/sentry/syscalls/linux/vfs2/fscontext.go b/pkg/sentry/syscalls/linux/vfs2/fscontext.go
new file mode 100644
index 000000000..317409a18
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/fscontext.go
@@ -0,0 +1,131 @@
+// 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/fspath"
+	"gvisor.dev/gvisor/pkg/sentry/arch"
+	"gvisor.dev/gvisor/pkg/sentry/kernel"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/syserror"
+)
+
+// Getcwd implements Linux syscall getcwd(2).
+func Getcwd(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	size := args[1].SizeT()
+
+	root := t.FSContext().RootDirectoryVFS2()
+	wd := t.FSContext().WorkingDirectoryVFS2()
+	s, err := t.Kernel().VFS().PathnameForGetcwd(t, root, wd)
+	root.DecRef()
+	wd.DecRef()
+	if err != nil {
+		return 0, nil, err
+	}
+
+	// Note this is >= because we need a terminator.
+	if uint(len(s)) >= size {
+		return 0, nil, syserror.ERANGE
+	}
+
+	// Construct a byte slice containing a NUL terminator.
+	buf := t.CopyScratchBuffer(len(s) + 1)
+	copy(buf, s)
+	buf[len(buf)-1] = 0
+
+	// Write the pathname slice.
+	n, err := t.CopyOutBytes(addr, buf)
+	if err != nil {
+		return 0, nil, err
+	}
+	return uintptr(n), nil, nil
+}
+
+// Chdir implements Linux syscall chdir(2).
+func Chdir(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+
+	path, err := copyInPath(t, addr)
+	if err != nil {
+		return 0, nil, err
+	}
+	tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, followFinalSymlink)
+	if err != nil {
+		return 0, nil, err
+	}
+	defer tpop.Release()
+
+	vd, err := t.Kernel().VFS().GetDentryAt(t, t.Credentials(), &tpop.pop, &vfs.GetDentryOptions{
+		CheckSearchable: true,
+	})
+	if err != nil {
+		return 0, nil, err
+	}
+	t.FSContext().SetWorkingDirectoryVFS2(vd)
+	vd.DecRef()
+	return 0, nil, nil
+}
+
+// Fchdir implements Linux syscall fchdir(2).
+func Fchdir(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	fd := args[0].Int()
+
+	tpop, err := getTaskPathOperation(t, fd, fspath.Path{}, allowEmptyPath, nofollowFinalSymlink)
+	if err != nil {
+		return 0, nil, err
+	}
+	defer tpop.Release()
+
+	vd, err := t.Kernel().VFS().GetDentryAt(t, t.Credentials(), &tpop.pop, &vfs.GetDentryOptions{
+		CheckSearchable: true,
+	})
+	if err != nil {
+		return 0, nil, err
+	}
+	t.FSContext().SetWorkingDirectoryVFS2(vd)
+	vd.DecRef()
+	return 0, nil, nil
+}
+
+// Chroot implements Linux syscall chroot(2).
+func Chroot(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+
+	if !t.HasCapability(linux.CAP_SYS_CHROOT) {
+		return 0, nil, syserror.EPERM
+	}
+
+	path, err := copyInPath(t, addr)
+	if err != nil {
+		return 0, nil, err
+	}
+	tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, followFinalSymlink)
+	if err != nil {
+		return 0, nil, err
+	}
+	defer tpop.Release()
+
+	vd, err := t.Kernel().VFS().GetDentryAt(t, t.Credentials(), &tpop.pop, &vfs.GetDentryOptions{
+		CheckSearchable: true,
+	})
+	if err != nil {
+		return 0, nil, err
+	}
+	t.FSContext().SetRootDirectoryVFS2(vd)
+	vd.DecRef()
+	return 0, nil, nil
+}