container/bits: move bind bits

This allows referring to the bits without importing container.

Signed-off-by: Ophestra <cat@gensokyo.uk>

5 files changed, 80 insertions, 75 deletions

diff --git a/container/autoroot_test.go b/container/autoroot_test.go
index fed1ab11..8c72b789 100644
--- a/container/autoroot_test.go
+++ b/container/autoroot_test.go
@@ -5,6 +5,7 @@ import (
 	"os"
 	"testing"
 
+	"hakurei.app/container/bits"
 	"hakurei.app/container/check"
 	"hakurei.app/container/stub"
 )
@@ -20,14 +21,14 @@ func TestAutoRootOp(t *testing.T) {
 	checkOpBehaviour(t, []opBehaviourTestCase{
 		{"readdir", &Params{ParentPerm: 0750}, &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, []stub.Call{
 			call("readdir", stub.ExpectArgs{"/"}, stubDir(), stub.UniqueError(2)),
 		}, stub.UniqueError(2), nil, nil},
 
 		{"early", &Params{ParentPerm: 0750}, &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, []stub.Call{
 			call("readdir", stub.ExpectArgs{"/"}, stubDir("bin", "dev", "etc", "home", "lib64",
 				"lost+found", "mnt", "nix", "proc", "root", "run", "srv", "sys", "tmp", "usr", "var"), nil),
@@ -36,7 +37,7 @@ func TestAutoRootOp(t *testing.T) {
 
 		{"apply", &Params{ParentPerm: 0750}, &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, []stub.Call{
 			call("readdir", stub.ExpectArgs{"/"}, stubDir("bin", "dev", "etc", "home", "lib64",
 				"lost+found", "mnt", "nix", "proc", "root", "run", "srv", "sys", "tmp", "usr", "var"), nil),
@@ -57,7 +58,7 @@ func TestAutoRootOp(t *testing.T) {
 
 		{"success pd", &Params{ParentPerm: 0750}, &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, []stub.Call{
 			call("readdir", stub.ExpectArgs{"/"}, stubDir("bin", "dev", "etc", "home", "lib64",
 				"lost+found", "mnt", "nix", "proc", "root", "run", "srv", "sys", "tmp", "usr", "var"), nil),
@@ -124,10 +125,10 @@ func TestAutoRootOp(t *testing.T) {
 	})
 
 	checkOpsBuilder(t, []opsBuilderTestCase{
-		{"pd", new(Ops).Root(check.MustAbs("/"), BindWritable), Ops{
+		{"pd", new(Ops).Root(check.MustAbs("/"), bits.BindWritable), Ops{
 			&AutoRootOp{
 				Host:  check.MustAbs("/"),
-				Flags: BindWritable,
+				Flags: bits.BindWritable,
 			},
 		}},
 	})
@@ -137,42 +138,42 @@ func TestAutoRootOp(t *testing.T) {
 
 		{"internal ne", &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, &AutoRootOp{
 			Host:     check.MustAbs("/"),
-			Flags:    BindWritable,
+			Flags:    bits.BindWritable,
 			resolved: []*BindMountOp{new(BindMountOp)},
 		}, true},
 
 		{"flags differs", &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable | BindDevice,
+			Flags: bits.BindWritable | bits.BindDevice,
 		}, &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, false},
 
 		{"host differs", &AutoRootOp{
 			Host:  check.MustAbs("/tmp/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, false},
 
 		{"equals", &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, true},
 	})
 
 	checkOpMeta(t, []opMetaTestCase{
 		{"root", &AutoRootOp{
 			Host:  check.MustAbs("/"),
-			Flags: BindWritable,
+			Flags: bits.BindWritable,
 		}, "setting up", `auto root "/" flags 0x2`},
 	})
 }
diff --git a/container/bits/bits.go b/container/bits/bits.go
new file mode 100644
index 00000000..7aa2e448
--- /dev/null
+++ b/container/bits/bits.go
@@ -0,0 +1,13 @@
+// Package bits contains constants for configuring the container.
+package bits
+
+const (
+	// BindOptional skips nonexistent host paths.
+	BindOptional = 1 << iota
+	// BindWritable mounts filesystem read-write.
+	BindWritable
+	// BindDevice allows access to devices (special files) on this filesystem.
+	BindDevice
+	// BindEnsure attempts to create the host path if it does not exist.
+	BindEnsure
+)
diff --git a/container/init_test.go b/container/init_test.go
index de700db9..1db81741 100644
--- a/container/init_test.go
+++ b/container/init_test.go
@@ -350,7 +350,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(nil, nil, BindDevice),
+					Ops:            new(Ops).Bind(nil, nil, bits.BindDevice),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -388,7 +388,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -427,7 +427,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -466,7 +466,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -506,7 +506,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -547,7 +547,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -589,7 +589,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -632,7 +632,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -676,7 +676,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -721,7 +721,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -767,7 +767,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -822,7 +822,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -877,7 +877,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -933,7 +933,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -990,7 +990,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1049,7 +1049,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1109,7 +1109,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1170,7 +1170,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1232,7 +1232,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1295,7 +1295,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1359,7 +1359,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1424,7 +1424,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1490,7 +1490,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1564,7 +1564,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1671,7 +1671,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1779,7 +1779,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
@@ -1889,7 +1889,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 24,
 					Gid:            1 << 47,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompDisable: true,
 					ParentPerm:     0750,
@@ -2003,7 +2003,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 24,
 					Gid:            1 << 47,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompDisable: true,
 					ParentPerm:     0750,
@@ -2103,7 +2103,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 24,
 					Gid:            1 << 47,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompDisable: true,
 					ParentPerm:     0750,
@@ -2194,7 +2194,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 24,
 					Gid:            1 << 47,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompDisable: true,
 					ParentPerm:     0750,
@@ -2287,7 +2287,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 24,
 					Gid:            1 << 47,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompDisable: true,
 					ParentPerm:     0750,
@@ -2387,7 +2387,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 24,
 					Gid:            1 << 47,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompDisable: true,
 					ParentPerm:     0750,
@@ -2523,7 +2523,7 @@ func TestInitEntrypoint(t *testing.T) {
 					Uid:            1 << 32,
 					Gid:            1 << 31,
 					Hostname:       "hakurei-check",
-					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), BindDevice).Proc(check.MustAbs("/proc/")),
+					Ops:            new(Ops).Bind(check.MustAbs("/"), check.MustAbs("/"), bits.BindDevice).Proc(check.MustAbs("/proc/")),
 					SeccompRules:   make([]seccomp.NativeRule, 0),
 					SeccompPresets: bits.PresetStrict,
 					RetainSession:  true,
diff --git a/container/initbind.go b/container/initbind.go
index 0cb2e2f8..54f00120 100644
--- a/container/initbind.go
+++ b/container/initbind.go
@@ -6,6 +6,7 @@ import (
 	"os"
 	"syscall"
 
+	"hakurei.app/container/bits"
 	"hakurei.app/container/check"
 )
 
@@ -25,32 +26,21 @@ type BindMountOp struct {
 	Flags int
 }
 
-const (
-	// BindOptional skips nonexistent host paths.
-	BindOptional = 1 << iota
-	// BindWritable mounts filesystem read-write.
-	BindWritable
-	// BindDevice allows access to devices (special files) on this filesystem.
-	BindDevice
-	// BindEnsure attempts to create the host path if it does not exist.
-	BindEnsure
-)
-
 func (b *BindMountOp) Valid() bool {
 	return b != nil &&
 		b.Source != nil && b.Target != nil &&
-		b.Flags&(BindOptional|BindEnsure) != (BindOptional|BindEnsure)
+		b.Flags&(bits.BindOptional|bits.BindEnsure) != (bits.BindOptional|bits.BindEnsure)
 }
 
 func (b *BindMountOp) early(_ *setupState, k syscallDispatcher) error {
-	if b.Flags&BindEnsure != 0 {
+	if b.Flags&bits.BindEnsure != 0 {
 		if err := k.mkdirAll(b.Source.String(), 0700); err != nil {
 			return err
 		}
 	}
 
 	if pathname, err := k.evalSymlinks(b.Source.String()); err != nil {
-		if os.IsNotExist(err) && b.Flags&BindOptional != 0 {
+		if os.IsNotExist(err) && b.Flags&bits.BindOptional != 0 {
 			// leave sourceFinal as nil
 			return nil
 		}
@@ -63,7 +53,7 @@ func (b *BindMountOp) early(_ *setupState, k syscallDispatcher) error {
 
 func (b *BindMountOp) apply(state *setupState, k syscallDispatcher) error {
 	if b.sourceFinal == nil {
-		if b.Flags&BindOptional == 0 {
+		if b.Flags&bits.BindOptional == 0 {
 			// unreachable
 			return OpStateError("bind")
 		}
@@ -86,10 +76,10 @@ func (b *BindMountOp) apply(state *setupState, k syscallDispatcher) error {
 	}
 
 	var flags uintptr = syscall.MS_REC
-	if b.Flags&BindWritable == 0 {
+	if b.Flags&bits.BindWritable == 0 {
 		flags |= syscall.MS_RDONLY
 	}
-	if b.Flags&BindDevice == 0 {
+	if b.Flags&bits.BindDevice == 0 {
 		flags |= syscall.MS_NODEV
 	}
 
diff --git a/container/initbind_test.go b/container/initbind_test.go
index 5e0c37e7..41a1d972 100644
--- a/container/initbind_test.go
+++ b/container/initbind_test.go
@@ -6,6 +6,7 @@ import (
 	"syscall"
 	"testing"
 
+	"hakurei.app/container/bits"
 	"hakurei.app/container/check"
 	"hakurei.app/container/stub"
 )
@@ -22,7 +23,7 @@ func TestBindMountOp(t *testing.T) {
 		{"skip optional", new(Params), &BindMountOp{
 			Source: check.MustAbs("/bin/"),
 			Target: check.MustAbs("/bin/"),
-			Flags:  BindOptional,
+			Flags:  bits.BindOptional,
 		}, []stub.Call{
 			call("evalSymlinks", stub.ExpectArgs{"/bin/"}, "", syscall.ENOENT),
 		}, nil, nil, nil},
@@ -30,7 +31,7 @@ func TestBindMountOp(t *testing.T) {
 		{"success optional", new(Params), &BindMountOp{
 			Source: check.MustAbs("/bin/"),
 			Target: check.MustAbs("/bin/"),
-			Flags:  BindOptional,
+			Flags:  bits.BindOptional,
 		}, []stub.Call{
 			call("evalSymlinks", stub.ExpectArgs{"/bin/"}, "/usr/bin", nil),
 		}, nil, []stub.Call{
@@ -43,7 +44,7 @@ func TestBindMountOp(t *testing.T) {
 		{"ensureFile device", new(Params), &BindMountOp{
 			Source: check.MustAbs("/dev/null"),
 			Target: check.MustAbs("/dev/null"),
-			Flags:  BindWritable | BindDevice,
+			Flags:  bits.BindWritable | bits.BindDevice,
 		}, []stub.Call{
 			call("evalSymlinks", stub.ExpectArgs{"/dev/null"}, "/dev/null", nil),
 		}, nil, []stub.Call{
@@ -54,7 +55,7 @@ func TestBindMountOp(t *testing.T) {
 		{"mkdirAll ensure", new(Params), &BindMountOp{
 			Source: check.MustAbs("/bin/"),
 			Target: check.MustAbs("/bin/"),
-			Flags:  BindEnsure,
+			Flags:  bits.BindEnsure,
 		}, []stub.Call{
 			call("mkdirAll", stub.ExpectArgs{"/bin/", os.FileMode(0700)}, nil, stub.UniqueError(4)),
 		}, stub.UniqueError(4), nil, nil},
@@ -62,7 +63,7 @@ func TestBindMountOp(t *testing.T) {
 		{"success ensure", new(Params), &BindMountOp{
 			Source: check.MustAbs("/bin/"),
 			Target: check.MustAbs("/usr/bin/"),
-			Flags:  BindEnsure,
+			Flags:  bits.BindEnsure,
 		}, []stub.Call{
 			call("mkdirAll", stub.ExpectArgs{"/bin/", os.FileMode(0700)}, nil, nil),
 			call("evalSymlinks", stub.ExpectArgs{"/bin/"}, "/usr/bin", nil),
@@ -76,7 +77,7 @@ func TestBindMountOp(t *testing.T) {
 		{"success device ro", new(Params), &BindMountOp{
 			Source: check.MustAbs("/dev/null"),
 			Target: check.MustAbs("/dev/null"),
-			Flags:  BindDevice,
+			Flags:  bits.BindDevice,
 		}, []stub.Call{
 			call("evalSymlinks", stub.ExpectArgs{"/dev/null"}, "/dev/null", nil),
 		}, nil, []stub.Call{
@@ -89,7 +90,7 @@ func TestBindMountOp(t *testing.T) {
 		{"success device", new(Params), &BindMountOp{
 			Source: check.MustAbs("/dev/null"),
 			Target: check.MustAbs("/dev/null"),
-			Flags:  BindWritable | BindDevice,
+			Flags:  bits.BindWritable | bits.BindDevice,
 		}, []stub.Call{
 			call("evalSymlinks", stub.ExpectArgs{"/dev/null"}, "/dev/null", nil),
 		}, nil, []stub.Call{
@@ -176,7 +177,7 @@ func TestBindMountOp(t *testing.T) {
 		{"zero", new(BindMountOp), false},
 		{"nil source", &BindMountOp{Target: check.MustAbs("/")}, false},
 		{"nil target", &BindMountOp{Source: check.MustAbs("/")}, false},
-		{"flag optional ensure", &BindMountOp{Source: check.MustAbs("/"), Target: check.MustAbs("/"), Flags: BindOptional | BindEnsure}, false},
+		{"flag optional ensure", &BindMountOp{Source: check.MustAbs("/"), Target: check.MustAbs("/"), Flags: bits.BindOptional | bits.BindEnsure}, false},
 		{"valid", &BindMountOp{Source: check.MustAbs("/"), Target: check.MustAbs("/")}, true},
 	})
 
@@ -211,7 +212,7 @@ func TestBindMountOp(t *testing.T) {
 		}, &BindMountOp{
 			Source: check.MustAbs("/etc/"),
 			Target: check.MustAbs("/etc/.host/048090b6ed8f9ebb10e275ff5d8c0659"),
-			Flags:  BindOptional,
+			Flags:  bits.BindOptional,
 		}, false},
 
 		{"source differs", &BindMountOp{
@@ -250,7 +251,7 @@ func TestBindMountOp(t *testing.T) {
 		{"hostdev", &BindMountOp{
 			Source: check.MustAbs("/dev/"),
 			Target: check.MustAbs("/dev/"),
-			Flags:  BindWritable | BindDevice,
+			Flags:  bits.BindWritable | bits.BindDevice,
 		}, "mounting", `"/dev/" flags 0x6`},
 	})
 }