libgocryptfs/tests/root_test/root_test.go

// Package root_test contains tests that need root
// permissions to run
package root_test

import (
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"sync"
	"syscall"
	"testing"

	"golang.org/x/sys/unix"

	"github.com/rfjakob/gocryptfs/tests/test_helpers"
)

func asUser(uid int, gid int, supplementaryGroups []int, f func() error) error {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	err := unix.Setgroups(supplementaryGroups)
	if err != nil {
		return err
	}
	defer func() {
		err = unix.Setgroups(nil)
		if err != nil {
			panic(err)
		}
	}()
	err = unix.Setregid(-1, gid)
	if err != nil {
		return err
	}
	defer func() {
		err = unix.Setregid(-1, 0)
		if err != nil {
			panic(err)
		}
	}()
	err = unix.Setreuid(-1, uid)
	if err != nil {
		return err
	}
	defer func() {
		err = unix.Setreuid(-1, 0)
		if err != nil {
			panic(err)
		}
	}()

	ret := f()

	// Also reset the saved user id (suid) and saved group id (sgid) to prevent
	// bizarre failures in later tests.
	//
	// Yes, the kernel checks that *all of them* match:
	// https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/fuse/dir.c?h=v5.12-rc2#n1193
	//
	// How to check:
	// ps -o tid,pid,euid,ruid,suid,egid,rgid,sgid,cmd -eL
	err = unix.Setresuid(0, 0, 0)
	if err != nil {
		panic(err)
	}
	err = unix.Setresgid(0, 0, 0)
	if err != nil {
		panic(err)
	}

	return ret
}

func TestSupplementaryGroups(t *testing.T) {
	if os.Getuid() != 0 {
		t.Skip("must run as root")
	}
	cDir := test_helpers.InitFS(t)
	os.Chmod(cDir, 0755)
	pDir := cDir + ".mnt"
	test_helpers.MountOrFatal(t, cDir, pDir, "-allow_other", "-extpass=echo test")
	defer test_helpers.UnmountPanic(pDir)

	// We need an unrestricted umask
	syscall.Umask(0000)

	dir1 := pDir + "/dir1"
	err := os.Mkdir(dir1, 0770)
	if err != nil {
		t.Fatal(err)
	}
	err = os.Chown(dir1, 0, 1234)
	if err != nil {
		t.Fatal(err)
	}

	err = asUser(1235, 1235, []int{1234}, func() error { return os.Mkdir(dir1+"/dir2", 0700) })
	if err != nil {
		t.Error(err)
	}

	err = asUser(1235, 1235, []int{1234}, func() error {
		f, err := os.Create(dir1 + "/file1")
		if err == nil {
			f.Close()
		}
		return err
	})
	if err != nil {
		t.Error(err)
	}
}

func writeTillFull(t *testing.T, path string) (int, syscall.Errno) {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	fd, err := syscall.Creat(path, 0600)
	if err != nil {
		return 0, err.(syscall.Errno)
	}
	defer syscall.Close(fd)
	// Write in 100.000 byte-blocks, which is not aligend to the
	// underlying block size
	buf := make([]byte, 100000)
	var sz int
	for {
		n, err := syscall.Write(fd, buf)
		if err != nil {
			return sz, err.(syscall.Errno)
		}
		sz += n
	}
	return sz, 0
}

func TestDiskFull(t *testing.T) {
	if os.Getuid() != 0 {
		t.Skip("must run as root")
	}

	// Create 10 MB file full of zeros
	ext4img := filepath.Join(test_helpers.TmpDir, t.Name()+".ext4")
	f, err := os.Create(ext4img)
	if err != nil {
		t.Fatal(err)
	}
	defer f.Close()
	err = f.Truncate(10 * 1024 * 1024)
	if err != nil {
		t.Fatal(err)
	}

	// Format as ext4
	cmd := exec.Command("mkfs.ext4", ext4img)
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Log(string(out))
		t.Fatal(err)
	}

	// Mount ext4
	ext4mnt := ext4img + ".mnt"
	err = os.Mkdir(ext4mnt, 0600)
	if err != nil {
		t.Fatal(err)
	}
	cmd = exec.Command("mount", ext4img, ext4mnt)
	out, err = cmd.CombinedOutput()
	if err != nil {
		t.Log(string(out))
		t.Fatal(err)
	}
	defer syscall.Unlink(ext4img)
	defer syscall.Unmount(ext4mnt, 0)

	// gocryptfs -init
	cipherdir := ext4mnt + "/a"
	if err = os.Mkdir(cipherdir, 0600); err != nil {
		t.Fatal(err)
	}
	cmd = exec.Command(test_helpers.GocryptfsBinary, "-q", "-init", "-extpass", "echo test", "-scryptn=10", cipherdir)
	out, err = cmd.CombinedOutput()
	if err != nil {
		t.Log(string(out))
		t.Fatal(err)
	}

	// Mount gocryptfs
	mnt := ext4mnt + "/b"
	test_helpers.MountOrFatal(t, cipherdir, mnt, "-extpass", "echo test")
	defer test_helpers.UnmountPanic(mnt)

	// Write till we get ENOSPC
	var err1, err2 error
	var sz1, sz2 int
	var wg sync.WaitGroup
	wg.Add(2)
	go func() {
		sz1, err1 = writeTillFull(t, mnt+"/foo1")
		wg.Done()
	}()
	go func() {
		sz2, err2 = writeTillFull(t, mnt+"/foo2")
		wg.Done()
	}()
	wg.Wait()
	if err1 != syscall.ENOSPC || err2 != syscall.ENOSPC {
		t.Fatalf("err1=%v, err2=%v", err1, err2)
	}
	t.Logf("sz1=%d, sz2=%d", sz1, sz2)

	foo1, err := ioutil.ReadFile(mnt + "/foo1")
	if err != nil {
		t.Fatal(err)
	}
	if len(foo1) != sz1 {
		t.Fail()
	}

	foo2, err := ioutil.ReadFile(mnt + "/foo2")
	if err != nil {
		t.Fatal(err)
	}
	if len(foo2) != sz2 {
		t.Fail()
	}
}