1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Module version support
  4 *
  5 * Copyright (C) 2008 Rusty Russell
  6 */
  7
  8#include <linux/module.h>
  9#include <linux/string.h>
 10#include <linux/printk.h>
 11#include "internal.h"
 12
 13int check_version(const struct load_info *info,
 14		  const char *symname,
 15			 struct module *mod,
 16			 const s32 *crc)
 17{
 18	Elf_Shdr *sechdrs = info->sechdrs;
 19	unsigned int versindex = info->index.vers;
 20	unsigned int i, num_versions;
 21	struct modversion_info *versions;
 22
 23	/* Exporting module didn't supply crcs?  OK, we're already tainted. */
 24	if (!crc)
 25		return 1;
 26
 27	/* No versions at all?  modprobe --force does this. */
 28	if (versindex == 0)
 29		return try_to_force_load(mod, symname) == 0;
 30
 31	versions = (void *)sechdrs[versindex].sh_addr;
 32	num_versions = sechdrs[versindex].sh_size
 33		/ sizeof(struct modversion_info);
 34
 35	for (i = 0; i < num_versions; i++) {
 36		u32 crcval;
 37
 38		if (strcmp(versions[i].name, symname) != 0)
 39			continue;
 40
 41		crcval = *crc;
 42		if (versions[i].crc == crcval)
 43			return 1;
 44		pr_debug("Found checksum %X vs module %lX\n",
 45			 crcval, versions[i].crc);
 46		goto bad_version;
 47	}
 48
 49	/* Broken toolchain. Warn once, then let it go.. */
 50	pr_warn_once("%s: no symbol version for %s\n", info->name, symname);
 51	return 1;
 52
 53bad_version:
 54	pr_warn("%s: disagrees about version of symbol %s\n", info->name, symname);
 55	return 0;
 56}
 57
 58int check_modstruct_version(const struct load_info *info,
 59			    struct module *mod)
 60{
 61	struct find_symbol_arg fsa = {
 62		.name	= "module_layout",
 63		.gplok	= true,
 64	};
 65
 66	/*
 67	 * Since this should be found in kernel (which can't be removed), no
 68	 * locking is necessary -- use preempt_disable() to placate lockdep.
 69	 */
 70	preempt_disable();
 71	if (!find_symbol(&fsa)) {
 72		preempt_enable();
 73		BUG();
 74	}
 75	preempt_enable();
 76	return check_version(info, "module_layout", mod, fsa.crc);
 77}
 78
 79/* First part is kernel version, which we ignore if module has crcs. */
 80int same_magic(const char *amagic, const char *bmagic,
 81	       bool has_crcs)
 82{
 83	if (has_crcs) {
 84		amagic += strcspn(amagic, " ");
 85		bmagic += strcspn(bmagic, " ");
 86	}
 87	return strcmp(amagic, bmagic) == 0;
 88}
 89
 90/*
 91 * Generate the signature for all relevant module structures here.
 92 * If these change, we don't want to try to parse the module.
 93 */
 94void module_layout(struct module *mod,
 95		   struct modversion_info *ver,
 96		   struct kernel_param *kp,
 97		   struct kernel_symbol *ks,
 98		   struct tracepoint * const *tp)
 99{
100}
101EXPORT_SYMBOL(module_layout);