hst: optionally disable file placement

This works around stubborn package managers.

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

hst/container.go

@@ -65,6 +65,8 @@ const (
 	// Some programs fail to connect to dbus session running as a different uid,
 	// this option works around it by mapping priv-side caller uid in container.
 	FMapRealUID
+	// FNoPlace disables placement of /etc/passwd and /etc/group.
+	FNoPlace
 
 	// FDevice mount /dev/ from the init mount namespace as is in the container
 	// mount namespace.
@@ -101,6 +103,8 @@ func (flags Flags) String() string {
 		return "tty"
 	case FMapRealUID:
 		return "mapuid"
+	case FNoPlace:
+		return "noplace"
 	case FDevice:
 		return "device"
 	case FCoverRun:
@@ -197,6 +201,8 @@ type containerConfigJSON = struct {
 
 	// Corresponds to [FMapRealUID].
 	MapRealUID bool `json:"map_real_uid"`
+	// Corresponds to [FNoPlace].
+	NoPlace bool `json:"noplace,omitempty"`
 
 	// Corresponds to [FDevice].
 	Device bool `json:"device,omitempty"`
@@ -224,6 +230,7 @@ func (c *ContainerConfig) MarshalJSON() ([]byte, error) {
 		Tty:           c.Flags&FTty != 0,
 		Multiarch:     c.Flags&FMultiarch != 0,
 		MapRealUID:    c.Flags&FMapRealUID != 0,
+		NoPlace:       c.Flags&FNoPlace != 0,
 		Device:        c.Flags&FDevice != 0,
 		CoverRun:      c.Flags&FCoverRun != 0,
 		ShareRuntime:  c.Flags&FShareRuntime != 0,
@@ -266,6 +273,9 @@ func (c *ContainerConfig) UnmarshalJSON(data []byte) error {
 	if v.MapRealUID {
 		c.Flags |= FMapRealUID
 	}
+	if v.NoPlace {
+		c.Flags |= FNoPlace
+	}
 	if v.Device {
 		c.Flags |= FDevice
 	}

hst/container_test.go

@@ -21,8 +21,8 @@ func TestFlagsString(t *testing.T) {
 	}{
 		{"none", 0, "none"},
 		{"none high", hst.FAll + 1, "none"},
-		{"all", hst.FAll, "multiarch, compat, devel, userns, net, abstract, tty, mapuid, device, cover_run, runtime, tmpdir"},
-		{"all high", math.MaxUint, "multiarch, compat, devel, userns, net, abstract, tty, mapuid, device, cover_run, runtime, tmpdir"},
+		{"all", hst.FAll, "multiarch, compat, devel, userns, net, abstract, tty, mapuid, noplace, device, cover_run, runtime, tmpdir"},
+		{"all high", math.MaxUint, "multiarch, compat, devel, userns, net, abstract, tty, mapuid, noplace, device, cover_run, runtime, tmpdir"},
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
@@ -53,7 +53,7 @@ func TestContainerConfig(t *testing.T) {
 		{"hostnet hostabstract mapuid", &hst.ContainerConfig{Flags: hst.FHostNet | hst.FHostAbstract | hst.FMapRealUID},
 			`{"env":null,"filesystem":null,"shell":null,"home":null,"args":null,"host_net":true,"host_abstract":true,"map_real_uid":true}`},
 		{"all", &hst.ContainerConfig{Flags: hst.FAll},
-			`{"env":null,"filesystem":null,"shell":null,"home":null,"args":null,"seccomp_compat":true,"devel":true,"userns":true,"host_net":true,"host_abstract":true,"tty":true,"multiarch":true,"map_real_uid":true,"device":true,"cover_run":true,"share_runtime":true,"share_tmpdir":true}`},
+			`{"env":null,"filesystem":null,"shell":null,"home":null,"args":null,"seccomp_compat":true,"devel":true,"userns":true,"host_net":true,"host_abstract":true,"tty":true,"multiarch":true,"map_real_uid":true,"noplace":true,"device":true,"cover_run":true,"share_runtime":true,"share_tmpdir":true}`},
 	}
 
 	for _, tc := range testCases {

hst/hst_test.go

@@ -244,6 +244,7 @@ func TestTemplate(t *testing.T) {
 		"tty": true,
 		"multiarch": true,
 		"map_real_uid": true,
+		"noplace": true,
 		"device": true,
 		"cover_run": true,
 		"share_runtime": true,