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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Module version support
*
* Copyright (C) 2008 Rusty Russell
*/
#include <linux/module.h>
#include <linux/string.h>
#include <linux/printk.h>
#include "internal.h"
int check_version(const struct load_info *info,
const char *symname,
struct module *mod,
const u32 *crc)
{
Elf_Shdr *sechdrs = info->sechdrs;
unsigned int versindex = info->index.vers;
unsigned int i, num_versions;
struct modversion_info *versions;
struct modversion_info_ext version_ext;
/* Exporting module didn't supply crcs? OK, we're already tainted. */
if (!crc)
return 1;
/* If we have extended version info, rely on it */
if (info->index.vers_ext_crc) {
for_each_modversion_info_ext(version_ext, info) {
if (strcmp(version_ext.name, symname) != 0)
continue;
if (*version_ext.crc == *crc)
return 1;
pr_debug("Found checksum %X vs module %X\n",
*crc, *version_ext.crc);
goto bad_version;
}
pr_warn_once("%s: no extended symbol version for %s\n",
info->name, symname);
return 1;
}
/* No versions at all? modprobe --force does this. */
if (versindex == 0)
return try_to_force_load(mod, symname) == 0;
versions = (void *)sechdrs[versindex].sh_addr;
num_versions = sechdrs[versindex].sh_size
/ sizeof(struct modversion_info);
for (i = 0; i < num_versions; i++) {
u32 crcval;
if (strcmp(versions[i].name, symname) != 0)
continue;
crcval = *crc;
if (versions[i].crc == crcval)
return 1;
pr_debug("Found checksum %X vs module %lX\n",
crcval, versions[i].crc);
goto bad_version;
}
pr_warn("%s: no symbol version for %s\n", info->name, symname);
return 0;
bad_version:
pr_warn("%s: disagrees about version of symbol %s\n", info->name, symname);
return 0;
}
int check_modstruct_version(const struct load_info *info,
struct module *mod)
{
struct find_symbol_arg fsa = {
.name = "module_layout",
.gplok = true,
};
bool have_symbol;
/*
* Since this should be found in kernel (which can't be removed), no
* locking is necessary. Regardless use a RCU read section to keep
* lockdep happy.
*/
scoped_guard(rcu)
have_symbol = find_symbol(&fsa);
BUG_ON(!have_symbol);
return check_version(info, "module_layout", mod, fsa.crc);
}
/* First part is kernel version, which we ignore if module has crcs. */
int same_magic(const char *amagic, const char *bmagic,
bool has_crcs)
{
if (has_crcs) {
amagic += strcspn(amagic, " ");
bmagic += strcspn(bmagic, " ");
}
return strcmp(amagic, bmagic) == 0;
}
void modversion_ext_start(const struct load_info *info,
struct modversion_info_ext *start)
{
unsigned int crc_idx = info->index.vers_ext_crc;
unsigned int name_idx = info->index.vers_ext_name;
Elf_Shdr *sechdrs = info->sechdrs;
/*
* Both of these fields are needed for this to be useful
* Any future fields should be initialized to NULL if absent.
*/
if (crc_idx == 0 || name_idx == 0) {
start->remaining = 0;
return;
}
start->crc = (const u32 *)sechdrs[crc_idx].sh_addr;
start->name = (const char *)sechdrs[name_idx].sh_addr;
start->remaining = sechdrs[crc_idx].sh_size / sizeof(*start->crc);
}
void modversion_ext_advance(struct modversion_info_ext *vers)
{
vers->remaining--;
vers->crc++;
vers->name += strlen(vers->name) + 1;
}
/*
* Generate the signature for all relevant module structures here.
* If these change, we don't want to try to parse the module.
*/
void module_layout(struct module *mod,
struct modversion_info *ver,
struct kernel_param *kp,
struct kernel_symbol *ks,
struct tracepoint * const *tp)
{
}
EXPORT_SYMBOL(module_layout);
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