1 files changed, 107 insertions, 0 deletions
diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
new file mode 100644
index 000000000000..74834ba15615
--- /dev/null
+++ b/kernel/module/strict_rwx.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Module strict rwx
+ *
+ * Copyright (C) 2015 Rusty Russell
+ */
+
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/set_memory.h>
+#include "internal.h"
+
+static int module_set_memory(const struct module *mod, enum mod_mem_type type,
+			     int (*set_memory)(unsigned long start, int num_pages))
+{
+	const struct module_memory *mod_mem = &mod->mem[type];
+
+	if (!mod_mem->base)
+		return 0;
+
+	set_vm_flush_reset_perms(mod_mem->base);
+	return set_memory((unsigned long)mod_mem->base, mod_mem->size >> PAGE_SHIFT);
+}
+
+/*
+ * Since some arches are moving towards PAGE_KERNEL module allocations instead
+ * of PAGE_KERNEL_EXEC, keep module_enable_x() independent of
+ * CONFIG_STRICT_MODULE_RWX because they are needed regardless of whether we
+ * are strict.
+ */
+int module_enable_text_rox(const struct module *mod)
+{
+	for_class_mod_mem_type(type, text) {
+		int ret;
+
+		if (mod->mem[type].is_rox)
+			continue;
+
+		if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+			ret = module_set_memory(mod, type, set_memory_rox);
+		else
+			ret = module_set_memory(mod, type, set_memory_x);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+int module_enable_rodata_ro(const struct module *mod)
+{
+	int ret;
+
+	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX) || !rodata_enabled)
+		return 0;
+
+	ret = module_set_memory(mod, MOD_RODATA, set_memory_ro);
+	if (ret)
+		return ret;
+	ret = module_set_memory(mod, MOD_INIT_RODATA, set_memory_ro);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+int module_enable_rodata_ro_after_init(const struct module *mod)
+{
+	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX) || !rodata_enabled)
+		return 0;
+
+	return module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
+}
+
+int module_enable_data_nx(const struct module *mod)
+{
+	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+		return 0;
+
+	for_class_mod_mem_type(type, data) {
+		int ret = module_set_memory(mod, type, set_memory_nx);
+
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
+				char *secstrings, struct module *mod)
+{
+	const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR;
+	int i;
+
+	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+		return 0;
+
+	for (i = 0; i < hdr->e_shnum; i++) {
+		if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) {
+			pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n",
+			       mod->name, secstrings + sechdrs[i].sh_name, i);
+			return -ENOEXEC;
+		}
+	}
+
+	return 0;
+}