1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Module strict rwx
  4 *
  5 * Copyright (C) 2015 Rusty Russell
  6 */
  7
  8#include <linux/module.h>
  9#include <linux/mm.h>
 10#include <linux/vmalloc.h>
 11#include <linux/set_memory.h>
 12#include "internal.h"
 13
 14static int module_set_memory(const struct module *mod, enum mod_mem_type type,
 15			     int (*set_memory)(unsigned long start, int num_pages))
 16{
 17	const struct module_memory *mod_mem = &mod->mem[type];
 18
 19	if (!mod_mem->base)
 20		return 0;
 21
 22	set_vm_flush_reset_perms(mod_mem->base);
 23	return set_memory((unsigned long)mod_mem->base, mod_mem->size >> PAGE_SHIFT);
 24}
 25
 26/*
 27 * Since some arches are moving towards PAGE_KERNEL module allocations instead
 28 * of PAGE_KERNEL_EXEC, keep module_enable_x() independent of
 29 * CONFIG_STRICT_MODULE_RWX because they are needed regardless of whether we
 30 * are strict.
 31 */
 32int module_enable_text_rox(const struct module *mod)
 33{
 34	for_class_mod_mem_type(type, text) {
 35		int ret;
 36
 37		if (mod->mem[type].is_rox)
 38			continue;
 39
 40		if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
 41			ret = module_set_memory(mod, type, set_memory_rox);
 42		else
 43			ret = module_set_memory(mod, type, set_memory_x);
 44		if (ret)
 45			return ret;
 46	}
 47	return 0;
 48}
 49
 50int module_enable_rodata_ro(const struct module *mod, bool after_init)
 51{
 52	int ret;
 53
 54	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX) || !rodata_enabled)
 55		return 0;
 56
 57	ret = module_set_memory(mod, MOD_RODATA, set_memory_ro);
 58	if (ret)
 59		return ret;
 60	ret = module_set_memory(mod, MOD_INIT_RODATA, set_memory_ro);
 61	if (ret)
 62		return ret;
 63
 64	if (after_init)
 65		return module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
 66
 67	return 0;
 68}
 69
 70int module_enable_data_nx(const struct module *mod)
 71{
 72	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
 73		return 0;
 74
 75	for_class_mod_mem_type(type, data) {
 76		int ret = module_set_memory(mod, type, set_memory_nx);
 77
 78		if (ret)
 79			return ret;
 80	}
 81	return 0;
 82}
 83
 84int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 85				char *secstrings, struct module *mod)
 86{
 87	const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR;
 88	int i;
 89
 90	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
 91		return 0;
 92
 93	for (i = 0; i < hdr->e_shnum; i++) {
 94		if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) {
 95			pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n",
 96			       mod->name, secstrings + sechdrs[i].sh_name, i);
 97			return -ENOEXEC;
 98		}
 99	}
100
101	return 0;
102}