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1cd9502ee9
Commit 71810db27c1c ("modversions: treat symbol CRCs as 32 bit
quantities") changed the CRC fields to s32 because the __kcrctab and
__kcrctab_gpl sections contained relative references to the actual
CRC values stored in the .rodata section when CONFIG_MODULE_REL_CRCS=y.
Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing
CONFIG_MODULE_REL_CRCS") removed this complexity. Now, the __kcrctab
and __kcrctab_gpl sections directly contain the CRC values in all cases.
The genksyms tool outputs unsigned 32-bit CRC values, so u32 is preferred
over s32.
No functional changes are intended.
Regardless of this change, the CRC value is assigned to the u32 variable
'crcval' before the comparison, as seen in kernel/module/version.c:
crcval = *crc;
It was previously mandatory (but now optional) in order to avoid sign
extension because the following line previously compared 'unsigned long'
and 's32':
if (versions[i].crc == crcval)
return 1;
versions[i].crc is still 'unsigned long' for backward compatibility.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
102 lines
2.4 KiB
C
102 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Module version support
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*
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* Copyright (C) 2008 Rusty Russell
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*/
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/printk.h>
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#include "internal.h"
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int check_version(const struct load_info *info,
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const char *symname,
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struct module *mod,
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const u32 *crc)
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{
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Elf_Shdr *sechdrs = info->sechdrs;
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unsigned int versindex = info->index.vers;
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unsigned int i, num_versions;
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struct modversion_info *versions;
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/* Exporting module didn't supply crcs? OK, we're already tainted. */
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if (!crc)
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return 1;
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/* No versions at all? modprobe --force does this. */
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if (versindex == 0)
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return try_to_force_load(mod, symname) == 0;
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versions = (void *)sechdrs[versindex].sh_addr;
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num_versions = sechdrs[versindex].sh_size
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/ sizeof(struct modversion_info);
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for (i = 0; i < num_versions; i++) {
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u32 crcval;
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if (strcmp(versions[i].name, symname) != 0)
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continue;
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crcval = *crc;
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if (versions[i].crc == crcval)
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return 1;
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pr_debug("Found checksum %X vs module %lX\n",
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crcval, versions[i].crc);
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goto bad_version;
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}
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/* Broken toolchain. Warn once, then let it go.. */
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pr_warn_once("%s: no symbol version for %s\n", info->name, symname);
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return 1;
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bad_version:
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pr_warn("%s: disagrees about version of symbol %s\n", info->name, symname);
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return 0;
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}
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int check_modstruct_version(const struct load_info *info,
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struct module *mod)
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{
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struct find_symbol_arg fsa = {
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.name = "module_layout",
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.gplok = true,
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};
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/*
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* Since this should be found in kernel (which can't be removed), no
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* locking is necessary -- use preempt_disable() to placate lockdep.
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*/
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preempt_disable();
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if (!find_symbol(&fsa)) {
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preempt_enable();
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BUG();
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}
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preempt_enable();
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return check_version(info, "module_layout", mod, fsa.crc);
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}
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/* First part is kernel version, which we ignore if module has crcs. */
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int same_magic(const char *amagic, const char *bmagic,
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bool has_crcs)
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{
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if (has_crcs) {
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amagic += strcspn(amagic, " ");
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bmagic += strcspn(bmagic, " ");
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}
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return strcmp(amagic, bmagic) == 0;
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}
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/*
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* Generate the signature for all relevant module structures here.
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* If these change, we don't want to try to parse the module.
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*/
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void module_layout(struct module *mod,
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struct modversion_info *ver,
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struct kernel_param *kp,
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struct kernel_symbol *ks,
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struct tracepoint * const *tp)
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{
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}
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EXPORT_SYMBOL(module_layout);
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