module: Split module_enable_rodata_ro()

module_enable_rodata_ro() is called twice, once before module init
to set rodata sections readonly and once after module init to set
rodata_after_init section readonly.

The second time, only the rodata_after_init section needs to be
set to read-only, no need to re-apply it to already set rodata.

Split module_enable_rodata_ro() in two.

Signed-off-by: Christophe Leroy <[email protected]>
Tested-by: Daniel Gomez <[email protected]>
Reviewed-by: Luis Chamberlain <[email protected]>
Link: https://lore.kernel.org/r/e3b6ff0df7eac281c58bb02cecaeb377215daff3.1733427536.git.christophe.leroy@csgroup.eu
Signed-off-by: Petr Pavlu <[email protected]>

Author: chleroy

kernel/module/internal.h

@@ -327,7 +327,8 @@ static inline struct module *mod_find(unsigned long addr, struct mod_tree_root *
 }
 #endif /* CONFIG_MODULES_TREE_LOOKUP */
 
-int module_enable_rodata_ro(const struct module *mod, bool after_init);
+int module_enable_rodata_ro(const struct module *mod);
+int module_enable_rodata_ro_after_init(const struct module *mod);
 int module_enable_data_nx(const struct module *mod);
 int module_enable_text_rox(const struct module *mod);
 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,

kernel/module/main.c

@@ -2953,7 +2953,7 @@ static noinline int do_init_module(struct module *mod)
 	/* Switch to core kallsyms now init is done: kallsyms may be walking! */
 	rcu_assign_pointer(mod->kallsyms, &mod->core_kallsyms);
 #endif
-	ret = module_enable_rodata_ro(mod, true);
+	ret = module_enable_rodata_ro_after_init(mod);
 	if (ret)
 		goto fail_mutex_unlock;
 	mod_tree_remove_init(mod);
@@ -3123,7 +3123,7 @@ static int complete_formation(struct module *mod, struct load_info *info)
 	module_bug_finalize(info->hdr, info->sechdrs, mod);
 	module_cfi_finalize(info->hdr, info->sechdrs, mod);
 
-	err = module_enable_rodata_ro(mod, false);
+	err = module_enable_rodata_ro(mod);
 	if (err)
 		goto out_strict_rwx;
 	err = module_enable_data_nx(mod);

kernel/module/strict_rwx.c

@@ -47,7 +47,7 @@ int module_enable_text_rox(const struct module *mod)
 	return 0;
 }
 
-int module_enable_rodata_ro(const struct module *mod, bool after_init)
+int module_enable_rodata_ro(const struct module *mod)
 {
 	int ret;
 
@@ -61,12 +61,17 @@ int module_enable_rodata_ro(const struct module *mod, bool after_init)
 	if (ret)
 		return ret;
 
-	if (after_init)
-		return module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
-
 	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))