Revert "Revert "Add a neverallow for debugfs mounting""

This reverts commit f9dbb72654.
Issues with GSI testing fixed with
https://android-review.googlesource.com/c/platform/build/+/1686425/

Bug: 184381659
Test: manual
Change-Id: Icd07430c606e294dfaad2fc9b37d34e3dae8cbfc

Android.mk

@@ -301,6 +301,11 @@ ifeq ($(BUILD_BROKEN_ENFORCE_SYSPROP_OWNER),true)
   enforce_sysprop_owner := false
 endif
 
+enforce_debugfs_restriction := false
+ifeq ($(PRODUCT_SET_DEBUGFS_RESTRICTIONS),true)
+  enforce_debugfs_restriction := true
+endif
+
 ifeq ($(PRODUCT_SHIPPING_API_LEVEL),)
   #$(warning no product shipping level defined)
 else ifneq ($(call math_lt,30,$(PRODUCT_SHIPPING_API_LEVEL)),)
@@ -631,6 +636,7 @@ $(sepolicy_policy.conf): PRIVATE_TGT_WITH_ASAN := $(with_asan)
 $(sepolicy_policy.conf): PRIVATE_TGT_WITH_NATIVE_COVERAGE := $(with_native_coverage)
 $(sepolicy_policy.conf): PRIVATE_ADDITIONAL_M4DEFS := $(LOCAL_ADDITIONAL_M4DEFS)
 $(sepolicy_policy.conf): PRIVATE_SEPOLICY_SPLIT := $(PRODUCT_SEPOLICY_SPLIT)
+$(sepolicy_policy.conf): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $(enforce_debugfs_restriction)
 $(sepolicy_policy.conf): PRIVATE_POLICY_FILES := $(policy_files)
 $(sepolicy_policy.conf): $(policy_files) $(M4)
 	$(transform-policy-to-conf)
@@ -648,6 +654,7 @@ $(sepolicy_policy_2.conf): PRIVATE_TGT_WITH_ASAN := $(with_asan)
 $(sepolicy_policy_2.conf): PRIVATE_TGT_WITH_NATIVE_COVERAGE := $(with_native_coverage)
 $(sepolicy_policy_2.conf): PRIVATE_ADDITIONAL_M4DEFS := $(LOCAL_ADDITIONAL_M4DEFS)
 $(sepolicy_policy_2.conf): PRIVATE_SEPOLICY_SPLIT := $(PRODUCT_SEPOLICY_SPLIT)
+$(sepolicy_policy_2.conf): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $(enforce_debugfs_restriction)
 $(sepolicy_policy_2.conf): PRIVATE_POLICY_FILES := $(policy_files)
 $(sepolicy_policy_2.conf): $(policy_files) $(M4)
 	$(transform-policy-to-conf)
@@ -706,6 +713,7 @@ $(sepolicy_policy.conf): PRIVATE_TGT_WITH_ASAN := $(with_asan)
 $(sepolicy_policy.conf): PRIVATE_TGT_WITH_NATIVE_COVERAGE := $(with_native_coverage)
 $(sepolicy_policy.conf): PRIVATE_ADDITIONAL_M4DEFS := $(LOCAL_ADDITIONAL_M4DEFS)
 $(sepolicy_policy.conf): PRIVATE_SEPOLICY_SPLIT := $(PRODUCT_SEPOLICY_SPLIT)
+$(sepolicy_policy.conf): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $(enforce_debugfs_restriction)
 $(sepolicy_policy.conf): PRIVATE_POLICY_FILES := $(policy_files)
 $(sepolicy_policy.conf): $(policy_files) $(M4)
 	$(transform-policy-to-conf)
@@ -723,6 +731,7 @@ $(sepolicy_policy_2.conf): PRIVATE_TGT_WITH_ASAN := $(with_asan)
 $(sepolicy_policy_2.conf): PRIVATE_TGT_WITH_NATIVE_COVERAGE := $(with_native_coverage)
 $(sepolicy_policy_2.conf): PRIVATE_ADDITIONAL_M4DEFS := $(LOCAL_ADDITIONAL_M4DEFS)
 $(sepolicy_policy_2.conf): PRIVATE_SEPOLICY_SPLIT := $(PRODUCT_SEPOLICY_SPLIT)
+$(sepolicy_policy_2.conf): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $(enforce_debugfs_restriction)
 $(sepolicy_policy_2.conf): PRIVATE_POLICY_FILES := $(policy_files)
 $(sepolicy_policy_2.conf): $(policy_files) $(M4)
 	$(transform-policy-to-conf)
@@ -826,6 +835,7 @@ $(vendor_policy.conf): PRIVATE_SEPOLICY_SPLIT := $(PRODUCT_SEPOLICY_SPLIT)
 $(vendor_policy.conf): PRIVATE_COMPATIBLE_PROPERTY := $(PRODUCT_COMPATIBLE_PROPERTY)
 $(vendor_policy.conf): PRIVATE_TREBLE_SYSPROP_NEVERALLOW := $(treble_sysprop_neverallow)
 $(vendor_policy.conf): PRIVATE_ENFORCE_SYSPROP_OWNER := $(enforce_sysprop_owner)
+$(vendor_policy.conf): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $(enforce_debugfs_restriction)
 $(vendor_policy.conf): PRIVATE_POLICY_FILES := $(policy_files)
 $(vendor_policy.conf): $(policy_files) $(M4)
 	$(transform-policy-to-conf)
@@ -889,6 +899,7 @@ $(odm_policy.conf): PRIVATE_ADDITIONAL_M4DEFS := $(LOCAL_ADDITIONAL_M4DEFS)
 $(odm_policy.conf): PRIVATE_SEPOLICY_SPLIT := $(PRODUCT_SEPOLICY_SPLIT)
 $(odm_policy.conf): PRIVATE_COMPATIBLE_PROPERTY := $(PRODUCT_COMPATIBLE_PROPERTY)
 $(odm_policy.conf): PRIVATE_TREBLE_SYSPROP_NEVERALLOW := $(treble_sysprop_neverallow)
+$(odm_policy.conf): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $(enforce_debugfs_restriction)
 $(odm_policy.conf): PRIVATE_ENFORCE_SYSPROP_OWNER := $(enforce_sysprop_owner)
 $(odm_policy.conf): PRIVATE_POLICY_FILES := $(policy_files)
 $(odm_policy.conf): $(policy_files) $(M4)
@@ -1155,6 +1166,7 @@ $(sepolicy.recovery.conf): PRIVATE_TGT_WITH_ASAN := $(with_asan)
 $(sepolicy.recovery.conf): PRIVATE_TGT_WITH_NATIVE_COVERAGE := $(with_native_coverage)
 $(sepolicy.recovery.conf): PRIVATE_ADDITIONAL_M4DEFS := $(LOCAL_ADDITIONAL_M4DEFS)
 $(sepolicy.recovery.conf): PRIVATE_TGT_RECOVERY := -D target_recovery=true
+$(sepolicy.recovery.conf): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $(enforce_debugfs_restriction)
 $(sepolicy.recovery.conf): PRIVATE_POLICY_FILES := $(policy_files)
 $(sepolicy.recovery.conf): $(policy_files) $(M4)
 	$(transform-policy-to-conf)
@@ -1392,6 +1404,7 @@ $(base_plat_policy.conf): PRIVATE_SEPOLICY_SPLIT := true
 $(base_plat_policy.conf): PRIVATE_COMPATIBLE_PROPERTY := $(PRODUCT_COMPATIBLE_PROPERTY)
 $(base_plat_policy.conf): PRIVATE_TREBLE_SYSPROP_NEVERALLOW := $(treble_sysprop_neverallow)
 $(base_plat_policy.conf): PRIVATE_ENFORCE_SYSPROP_OWNER := $(enforce_sysprop_owner)
+$(base_plat_policy.conf): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $(enforce_debugfs_restriction)
 $(base_plat_policy.conf): PRIVATE_POLICY_FILES := $(policy_files)
 $(base_plat_policy.conf): $(policy_files) $(M4)
 	$(transform-policy-to-conf)
@@ -1424,6 +1437,7 @@ $(base_plat_pub_policy.conf): PRIVATE_SEPOLICY_SPLIT := true
 $(base_plat_pub_policy.conf): PRIVATE_COMPATIBLE_PROPERTY := $(PRODUCT_COMPATIBLE_PROPERTY)
 $(base_plat_pub_policy.conf): PRIVATE_TREBLE_SYSPROP_NEVERALLOW := $(treble_sysprop_neverallow)
 $(base_plat_pub_policy.conf): PRIVATE_ENFORCE_SYSPROP_OWNER := $(enforce_sysprop_owner)
+$(base_plat_pub_policy.conf): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $(enforce_debugfs_restriction)
 $(base_plat_pub_policy.conf): PRIVATE_POLICY_FILES := $(policy_files)
 $(base_plat_pub_policy.conf): $(policy_files) $(M4)
 	$(transform-policy-to-conf)
@@ -1542,6 +1556,7 @@ built_vendor_svc :=
 built_plat_sepolicy :=
 treble_sysprop_neverallow :=
 enforce_sysprop_owner :=
+enforce_debugfs_restriction :=
 mapping_policy :=
 my_target_arch :=
 pub_policy.cil :=

build/soong/policy.go

@@ -135,6 +135,13 @@ func (c *policyConf) enforceSyspropOwner(ctx android.ModuleContext) string {
 	return strconv.FormatBool(!ctx.DeviceConfig().BuildBrokenEnforceSyspropOwner())
 }
 
+func (c *policyConf) enforceDebugfsRestrictions(ctx android.ModuleContext) string {
+	if c.cts() {
+		return "cts"
+	}
+	return strconv.FormatBool(ctx.DeviceConfig().BuildDebugfsRestrictionsEnabled())
+}
+
 func (c *policyConf) transformPolicyToConf(ctx android.ModuleContext) android.OutputPath {
 	conf := android.PathForModuleOut(ctx, "conf").OutputPath
 	rule := android.NewRuleBuilder(pctx, ctx)
@@ -154,6 +161,7 @@ func (c *policyConf) transformPolicyToConf(ctx android.ModuleContext) android.Ou
 		FlagWithArg("-D target_enforce_sysprop_owner=", c.enforceSyspropOwner(ctx)).
 		FlagWithArg("-D target_exclude_build_test=", strconv.FormatBool(proptools.Bool(c.properties.Exclude_build_test))).
 		FlagWithArg("-D target_requires_insecure_execmem_for_swiftshader=", strconv.FormatBool(ctx.DeviceConfig().RequiresInsecureExecmemForSwiftshader())).
+		FlagWithArg("-D target_enforce_debugfs_restriction=", c.enforceDebugfsRestrictions(ctx)).
 		Flag("-s").
 		Inputs(android.PathsForModuleSrc(ctx, c.properties.Srcs)).
 		Text("> ").Output(conf)

definitions.mk

@@ -15,6 +15,7 @@ $(hide) $(M4) --fatal-warnings $(PRIVATE_ADDITIONAL_M4DEFS) \
 	-D target_enforce_sysprop_owner=$(PRIVATE_ENFORCE_SYSPROP_OWNER) \
 	-D target_exclude_build_test=$(PRIVATE_EXCLUDE_BUILD_TEST) \
 	-D target_requires_insecure_execmem_for_swiftshader=$(PRODUCT_REQUIRES_INSECURE_EXECMEM_FOR_SWIFTSHADER) \
+	-D target_enforce_debugfs_restriction=$(PRIVATE_ENFORCE_DEBUGFS_RESTRICTION) \
 	$(PRIVATE_TGT_RECOVERY) \
 	-s $(PRIVATE_POLICY_FILES) > $@
 endef

prebuilt_policy.mk

@@ -61,6 +61,7 @@ $(1): PRIVATE_SEPOLICY_SPLIT := $$(PRODUCT_SEPOLICY_SPLIT)
 $(1): PRIVATE_COMPATIBLE_PROPERTY := $$(PRODUCT_COMPATIBLE_PROPERTY)
 $(1): PRIVATE_TREBLE_SYSPROP_NEVERALLOW := $$(treble_sysprop_neverallow)
 $(1): PRIVATE_ENFORCE_SYSPROP_OWNER := $$(enforce_sysprop_owner)
+$(1): PRIVATE_ENFORCE_DEBUGFS_RESTRICTION := $$(enforce_debugfs_restriction)
 $(1): PRIVATE_POLICY_FILES := $$(policy_files)
 $(1): $$(policy_files) $$(M4)
 	$$(transform-policy-to-conf)

private/domain.te

@@ -367,7 +367,15 @@ neverallow {
     -update_engine
     -vold
     -zygote
-} { fs_type -sdcard_type }:filesystem { mount remount relabelfrom relabelto };
+} { fs_type
+    -sdcard_type
+}:filesystem { mount remount relabelfrom relabelto };
+
+enforce_debugfs_restriction(`
+  neverallow {
+    domain userdebug_or_eng(`-init')
+  } { debugfs_type -debugfs_tracing_debug }:filesystem { mount remount relabelfrom relabelto };
+')
 
 # Limit raw I/O to these allowlisted domains. Do not apply to debug builds.
 neverallow {

public/init.te

@@ -162,7 +162,19 @@ allowxperm init dev_type:blk_file ioctl BLKROSET;
 # which should all be assigned the contextmount_type attribute.
 # This can be done in device-specific policy via type or typeattribute
 # declarations.
-allow init fs_type:filesystem ~relabelto;
+allow init {
+  fs_type
+  enforce_debugfs_restriction(`-debugfs_type')
+}:filesystem ~relabelto;
+
+# Allow init to mount/unmount debugfs in non-user builds.
+enforce_debugfs_restriction(`
+  userdebug_or_eng(`allow init debugfs_type:filesystem { mount unmount };')
+')
+
+# Allow init to mount tracefs in /sys/kernel/tracing
+allow init debugfs_tracing_debug:filesystem mount;
+
 allow init unlabeled:filesystem ~relabelto;
 allow init contextmount_type:filesystem relabelto;
 

public/recovery.te

@@ -32,7 +32,7 @@ recovery_only(`
   # Mount filesystems.
   allow recovery rootfs:dir mounton;
   allow recovery tmpfs:dir mounton;
-  allow recovery fs_type:filesystem ~relabelto;
+  allow recovery { fs_type enforce_debugfs_restriction(`-debugfs_type') }:filesystem ~relabelto;
   allow recovery unlabeled:filesystem ~relabelto;
   allow recovery contextmount_type:filesystem relabelto;
 

public/te_macros

@@ -505,6 +505,23 @@ $1
 #
 define(`not_full_treble', ifelse(target_full_treble, `true', , $1))
 
+#####################################
+# enforce_debugfs_restriction
+# SELinux rules which apply to devices that enable debugfs restrictions.
+# The keyword "cts" is used to insert markers to only CTS test the neverallows
+# added by the macro for S-launch devices and newer.
+define(`enforce_debugfs_restriction', ifelse(target_enforce_debugfs_restriction, `true', $1,
+ifelse(target_enforce_debugfs_restriction, `cts',
+# BEGIN_LAUNCHING_WITH_S_ONLY -- this marker is used by CTS -- do not modify
+$1
+# END_LAUNCHING_WITH_S_ONLY -- this marker is used by CTS -- do not modify
+, )))
+
+#####################################
+# no_debugfs_restriction
+# SELinux rules which apply to devices that do not have debugfs restrictions in non-user builds.
+define(`no_debugfs_restriction', ifelse(target_enforce_debugfs_restriction, `true', , $1))
+
 #####################################
 # Compatible property only
 # SELinux rules which apply only to devices with compatible property