diff --git a/core/envsetup.mk b/core/envsetup.mk
index 7ddbf32..cfb8a66 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -371,6 +371,8 @@
 TARGET_BUILD_TYPE := release
 endif
 
+include $(BUILD_SYSTEM)/product_validation_checks.mk
+
 # ---------------------------------------------------------------
 # figure out the output directories
 
diff --git a/core/product.mk b/core/product.mk
index 39c9eb7..07719e1 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -449,6 +449,8 @@
 
 _product_list_vars += PRODUCT_RELEASE_CONFIG_MAPS
 
+_product_list_vars += PRODUCT_VALIDATION_CHECKS
+
 .KATI_READONLY := _product_single_value_vars _product_list_vars
 _product_var_list :=$= $(_product_single_value_vars) $(_product_list_vars)
 
diff --git a/core/product_config.mk b/core/product_config.mk
index b475d75..3ee9654 100644
--- a/core/product_config.mk
+++ b/core/product_config.mk
@@ -420,6 +420,8 @@
 PRODUCT_EXTRA_OTA_KEYS := $(sort $(PRODUCT_EXTRA_OTA_KEYS))
 PRODUCT_EXTRA_RECOVERY_KEYS := $(sort $(PRODUCT_EXTRA_RECOVERY_KEYS))
 
+PRODUCT_VALIDATION_CHECKS := $(sort $(PRODUCT_VALIDATION_CHECKS))
+
 # Resolve and setup per-module dex-preopt configs.
 DEXPREOPT_DISABLED_MODULES :=
 # If a module has multiple setups, the first takes precedence.
diff --git a/core/product_validation_checks.mk b/core/product_validation_checks.mk
new file mode 100644
index 0000000..5939a0c
--- /dev/null
+++ b/core/product_validation_checks.mk
@@ -0,0 +1,71 @@
+# PRODUCT_VALIDATION_CHECKS allows you to enforce that your product config variables follow some
+# rules. To use it, add the paths to starlark configuration language (scl) files in
+# PRODUCT_VALIDATION_CHECKS. A validate_product_variables function in those files will be called
+# with a single "context" object.
+#
+# The context object currently 2 attributes:
+#   - product_variables: This has all the product variables. All the variables are either of type
+#                        string or list, more accurate typing (like bool) isn't known.
+#   - board_variables: This only has a small subset of the board variables, because there isn't a
+#                      known list of board variables. Feel free to expand the subset if you need a
+#                      new variable.
+#
+# You can then inspect (but not modify) these variables and fail() if they don't meet your
+# requirements. Example:
+#
+# In a product config file: PRODUCT_VALIDATION_CHECKS += //path/to/my_validations.scl
+# In my_validations.scl:
+# def validate_product_variables(ctx):
+#     for dir in ctx.board_variables.BOARD_SEPOLICY_DIRS:
+#         if not dir.startswith('system/sepolicy/'):
+#             fail('Only sepolicies in system/seplicy are allowed, found: ' + dir)
+
+ifdef PRODUCT_VALIDATION_CHECKS
+
+$(if $(filter-out //%.scl,$(PRODUCT_VALIDATION_CHECKS)), \
+	$(error All PRODUCT_VALIDATION_CHECKS files must start with // and end with .scl, exceptions: $(filter-out //%.scl,$(PRODUCT_VALIDATION_CHECKS))))
+
+known_board_variables := \
+  BOARD_VENDOR_SEPOLICY_DIRS BOARD_SEPOLICY_DIRS \
+  SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS \
+  SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS \
+
+known_board_list_variables := \
+  BOARD_VENDOR_SEPOLICY_DIRS BOARD_SEPOLICY_DIRS \
+  SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS \
+  SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS \
+
+escape_starlark_string=$(subst ",\",$(subst \,\\,$(1)))
+product_variable_starlark_value=$(if $(filter $(1),$(_product_list_vars) $(known_board_list_variables)),[$(foreach w,$($(1)),"$(call escape_starlark_string,$(w))", )],"$(call escape_starlark_string,$(1))")
+filename_to_starlark=$(subst -,_,$(subst /,_,$(subst .,_,$(1))))
+_c:=load("//build/make/core/release_config.bzl", "release_config")
+_c+=$(foreach f,$(PRODUCT_VALIDATION_CHECKS),$(newline)load("$(f)", validate_product_variables_$(call filename_to_starlark,$(f)) = "validate_product_variables"))
+# TODO: we should freeze the context because it contains mutable lists, so that validation checks can't affect each other
+_c+=$(newline)_ctx = struct(
+_c+=$(newline)product_variables = struct(
+_c+=$(foreach v,$(_product_var_list),$(newline)  $(v) = $(call product_variable_starlark_value,$(v)),)
+_c+=$(newline)),
+_c+=$(newline)board_variables = struct(
+_c+=$(foreach v,$(known_board_variables),$(newline)  $(v) = $(call product_variable_starlark_value,$(v)),)
+_c+=$(newline))
+_c+=$(newline))
+# It's important that we call the function using keyword arguments, so that if we want to add
+# more arguments in the future it's easier.
+_c+=$(foreach f,$(PRODUCT_VALIDATION_CHECKS),$(newline)validate_product_variables_$(call filename_to_starlark,$(f))(_ctx))
+_c+=$(newline)variables_to_export_to_make = {}
+$(KATI_file_no_rerun >$(OUT_DIR)/product_validation_checks_entrypoint.scl,$(_c))
+filename_to_starlark:=
+escape_starlark_string:=
+product_variable_starlark_value:=
+known_board_variables :=
+known_board_list_variables :=
+
+# Exclude the entrypoint file as a dependency (by passing it as the 2nd argument) so that we don't
+# rerun kati every build. Even though we're using KATI_file_no_rerun, product config is run every
+# build, so the file will still be rewritten.
+#
+# We also need to pass --allow_external_entrypoint to rbcrun in case the OUT_DIR is set to something
+# outside of the source tree.
+$(call run-starlark,$(OUT_DIR)/product_validation_checks_entrypoint.scl,$(OUT_DIR)/product_validation_checks_entrypoint.scl,--allow_external_entrypoint)
+
+endif # ifdef PRODUCT_VALIDATION_CHECKS