hst: optionally cover /run/ early

This works around awkward root permissions.

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

cmd/app/app.go

@@ -83,6 +83,8 @@ func parse(id string, base *check.Absolute, r io.Reader) (*hst.Config, error) {
 			Home:     home,
 			Path:     shell,
 			Args:     []string{"zsh", "-c"},
+
+			Flags: hst.FCoverRun,
 		},
 	}
 

cmd/app/app_test.go

@@ -122,7 +122,7 @@ talk com.canonical.Unity
 					"exec Discord --ozone-platform-hint=wayland",
 				},
 
-				Flags: hst.FUserns | hst.FHostNet | hst.FMapRealUID |
+				Flags: hst.FCoverRun | hst.FUserns | hst.FHostNet | hst.FMapRealUID |
 					hst.FShareRuntime | hst.FShareTmpdir,
 			},
 		}, nil},

cmd/hakurei/print_test.go

@@ -64,7 +64,7 @@ func TestPrintShowInstance(t *testing.T) {
  Identity:       9 (org.chromium.Chromium)
  Enablements:    wayland, dbus, pipewire
  Groups:         video, dialout, plugdev
- Flags:          multiarch, compat, devel, userns, net, abstract, tty, mapuid, device, runtime, tmpdir
+ Flags:          multiarch, compat, devel, userns, net, abstract, tty, mapuid, device, cover_run, runtime, tmpdir
  Home:           /data/data/org.chromium.Chromium
  Hostname:       localhost
  Path:           /run/current-system/sw/bin/chromium
@@ -161,7 +161,7 @@ App
  Identity:       9 (org.chromium.Chromium)
  Enablements:    wayland, dbus, pipewire
  Groups:         video, dialout, plugdev
- Flags:          multiarch, compat, devel, userns, net, abstract, tty, mapuid, device, runtime, tmpdir
+ Flags:          multiarch, compat, devel, userns, net, abstract, tty, mapuid, device, cover_run, runtime, tmpdir
  Home:           /data/data/org.chromium.Chromium
  Hostname:       localhost
  Path:           /run/current-system/sw/bin/chromium
@@ -355,6 +355,7 @@ App
     "multiarch": true,
     "map_real_uid": true,
     "device": true,
+    "cover_run": true,
     "share_runtime": true,
     "share_tmpdir": true
   },
@@ -506,6 +507,7 @@ App
     "multiarch": true,
     "map_real_uid": true,
     "device": true,
+    "cover_run": true,
     "share_runtime": true,
     "share_tmpdir": true
   }
@@ -704,6 +706,7 @@ func TestPrintPs(t *testing.T) {
       "multiarch": true,
       "map_real_uid": true,
       "device": true,
+      "cover_run": true,
       "share_runtime": true,
       "share_tmpdir": true
     },

hst/container.go

@@ -69,6 +69,8 @@ const (
 	// FDevice mount /dev/ from the init mount namespace as is in the container
 	// mount namespace.
 	FDevice
+	// FCoverRun covers /run/ in the container mount namespace early.
+	FCoverRun
 
 	// FShareRuntime shares XDG_RUNTIME_DIR between containers under the same identity.
 	FShareRuntime
@@ -101,6 +103,8 @@ func (flags Flags) String() string {
 		return "mapuid"
 	case FDevice:
 		return "device"
+	case FCoverRun:
+		return "cover_run"
 	case FShareRuntime:
 		return "runtime"
 	case FShareTmpdir:
@@ -196,6 +200,8 @@ type containerConfigJSON = struct {
 
 	// Corresponds to [FDevice].
 	Device bool `json:"device,omitempty"`
+	// Corresponds to [FCoverRun].
+	CoverRun bool `json:"cover_run,omitempty"`
 
 	// Corresponds to [FShareRuntime].
 	ShareRuntime bool `json:"share_runtime,omitempty"`
@@ -219,6 +225,7 @@ func (c *ContainerConfig) MarshalJSON() ([]byte, error) {
 		Multiarch:     c.Flags&FMultiarch != 0,
 		MapRealUID:    c.Flags&FMapRealUID != 0,
 		Device:        c.Flags&FDevice != 0,
+		CoverRun:      c.Flags&FCoverRun != 0,
 		ShareRuntime:  c.Flags&FShareRuntime != 0,
 		ShareTmpdir:   c.Flags&FShareTmpdir != 0,
 	})
@@ -262,6 +269,9 @@ func (c *ContainerConfig) UnmarshalJSON(data []byte) error {
 	if v.Device {
 		c.Flags |= FDevice
 	}
+	if v.CoverRun {
+		c.Flags |= FCoverRun
+	}
 	if v.ShareRuntime {
 		c.Flags |= FShareRuntime
 	}

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, runtime, tmpdir"},
+		{"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, runtime, tmpdir"},
+		{"all high", math.MaxUint, "multiarch, compat, devel, userns, net, abstract, tty, mapuid, 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,"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,"device":true,"cover_run":true,"share_runtime":true,"share_tmpdir":true}`},
 	}
 
 	for _, tc := range testCases {

hst/hst_test.go

@@ -245,6 +245,7 @@ func TestTemplate(t *testing.T) {
 		"multiarch": true,
 		"map_real_uid": true,
 		"device": true,
+		"cover_run": true,
 		"share_runtime": true,
 		"share_tmpdir": true
 	}

internal/outcome/run_test.go

@@ -136,6 +136,7 @@ func TestOutcomeRun(t *testing.T) {
 				Tmpfs(fhs.AbsDevShm, 0, 01777).
 
 				// spRuntimeOp
+				Tmpfs(fhs.AbsRun, xdgRuntimeDirSize, 0755).
 				Tmpfs(fhs.AbsRunUser, xdgRuntimeDirSize, 0755).
 				Bind(m("/tmp/hakurei.0/runtime/9"), m("/run/user/1971"), std.BindWritable).
 

internal/outcome/shim_test.go

@@ -71,6 +71,7 @@ func TestShimEntrypoint(t *testing.T) {
 			Tmpfs(fhs.AbsDevShm, 0, 01777).
 
 			// spRuntimeOp
+			Tmpfs(fhs.AbsRun, xdgRuntimeDirSize, 0755).
 			Tmpfs(fhs.AbsRunUser, xdgRuntimeDirSize, 0755).
 			Bind(m("/tmp/hakurei.10/runtime/9999"), m("/run/user/1000"), std.BindWritable).
 

internal/outcome/spruntime.go

@@ -113,6 +113,9 @@ func (s *spRuntimeOp) toContainer(state *outcomeStateParams) error {
 
 	}
 
+	if state.Container.Flags&hst.FCoverRun != 0 {
+		state.params.Tmpfs(fhs.AbsRun, xdgRuntimeDirSize, 0755)
+	}
 	state.params.Tmpfs(fhs.AbsRunUser, xdgRuntimeDirSize, 0755)
 	if state.Container.Flags&hst.FShareRuntime != 0 {
 		_, runtimeDirInst := s.commonPaths(state.outcomeState)

internal/outcome/spruntime_test.go

@@ -40,6 +40,7 @@ func TestSpRuntimeOp(t *testing.T) {
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Ops: new(container.Ops).
+				Tmpfs(fhs.AbsRun, xdgRuntimeDirSize, 0755).
 				Tmpfs(fhs.AbsRunUser, xdgRuntimeDirSize, 0755).
 				Bind(m("/proc/nonexistent/tmp/hakurei.0/runtime/9"), m("/run/user/1000"), std.BindWritable),
 		}, paramsWantEnv(config, map[string]string{
@@ -67,6 +68,7 @@ func TestSpRuntimeOp(t *testing.T) {
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Ops: new(container.Ops).
+				Tmpfs(fhs.AbsRun, xdgRuntimeDirSize, 0755).
 				Tmpfs(fhs.AbsRunUser, xdgRuntimeDirSize, 0755).
 				Bind(m("/proc/nonexistent/tmp/hakurei.0/runtime/9"), m("/run/user/1000"), std.BindWritable),
 		}, paramsWantEnv(config, map[string]string{
@@ -94,6 +96,7 @@ func TestSpRuntimeOp(t *testing.T) {
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Ops: new(container.Ops).
+				Tmpfs(fhs.AbsRun, xdgRuntimeDirSize, 0755).
 				Tmpfs(fhs.AbsRunUser, xdgRuntimeDirSize, 0755).
 				Bind(m("/proc/nonexistent/tmp/hakurei.0/runtime/9"), m("/run/user/1000"), std.BindWritable),
 		}, paramsWantEnv(config, map[string]string{
@@ -117,6 +120,7 @@ func TestSpRuntimeOp(t *testing.T) {
 			// this op configures the container state and does not make calls during toContainer
 		}, &container.Params{
 			Ops: new(container.Ops).
+				Tmpfs(fhs.AbsRun, xdgRuntimeDirSize, 0755).
 				Tmpfs(fhs.AbsRunUser, xdgRuntimeDirSize, 0755).
 				Bind(m("/proc/nonexistent/tmp/hakurei.0/runtime/9"), m("/run/user/1000"), std.BindWritable),
 		}, paramsWantEnv(config, map[string]string{