Commit 47889798 authored by Aaron Tomlin's avatar Aaron Tomlin Committed by Luis Chamberlain
Browse files

module: Move version support into a separate file 



No functional change.

This patch migrates module version support out of core code into
kernel/module/version.c. In addition simple code refactoring to
make this possible.

Reviewed-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarAaron Tomlin <atomlin@redhat.com>
Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
parent f64205a4

kernel/module/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -18,3 +18,4 @@ obj-$(CONFIG_KALLSYMS) += kallsyms.o 
obj-$(CONFIG_PROC_FS) += procfs.o

obj-$(CONFIG_SYSFS) += sysfs.o

obj-$(CONFIG_KGDB_KDB) += kdb.o

obj-$(CONFIG_MODVERSIONS) += version.o

kernel/module/internal.h

+48 −0
Original line number Diff line number Diff line
@@ -70,7 +70,27 @@ struct load_info { 
	} index;

};



enum mod_license {

	NOT_GPL_ONLY,

	GPL_ONLY,

};



struct find_symbol_arg {

	/* Input */

	const char *name;

	bool gplok;

	bool warn;



	/* Output */

	struct module *owner;

	const s32 *crc;

	const struct kernel_symbol *sym;

	enum mod_license license;

};



int mod_verify_sig(const void *mod, struct load_info *info);

int try_to_force_load(struct module *mod, const char *reason);

bool find_symbol(struct find_symbol_arg *fsa);

struct module *find_module_all(const char *name, size_t len, bool even_unformed);

int cmp_name(const void *name, const void *sym);

long module_get_offset(struct module *mod, unsigned int *size, Elf_Shdr *sechdr,
@@ -225,3 +245,31 @@ static inline int mod_sysfs_setup(struct module *mod, 
static inline void mod_sysfs_teardown(struct module *mod) { }

static inline void init_param_lock(struct module *mod) { }

#endif /* CONFIG_SYSFS */



#ifdef CONFIG_MODVERSIONS

int check_version(const struct load_info *info,

		  const char *symname, struct module *mod, const s32 *crc);

void module_layout(struct module *mod, struct modversion_info *ver, struct kernel_param *kp,

		   struct kernel_symbol *ks, struct tracepoint * const *tp);

int check_modstruct_version(const struct load_info *info, struct module *mod);

int same_magic(const char *amagic, const char *bmagic, bool has_crcs);

#else /* !CONFIG_MODVERSIONS */

static inline int check_version(const struct load_info *info,

				const char *symname,

				struct module *mod,

				const s32 *crc)

{

	return 1;

}



static inline int check_modstruct_version(const struct load_info *info,

					  struct module *mod)

{

	return 1;

}



static inline int same_magic(const char *amagic, const char *bmagic, bool has_crcs)

{

	return strcmp(amagic, bmagic) == 0;

}

#endif /* CONFIG_MODVERSIONS */

kernel/module/main.c

+8 −148
Original line number Diff line number Diff line
@@ -86,6 +86,12 @@ struct mod_tree_root mod_tree __cacheline_aligned = { 
static unsigned long module_addr_min = -1UL, module_addr_max;

#endif /* CONFIG_MODULES_TREE_LOOKUP */



struct symsearch {

	const struct kernel_symbol *start, *stop;

	const s32 *crcs;

	enum mod_license license;

};



/*

 * Bounds of module text, for speeding up __module_address.

 * Protected by module_mutex.
@@ -244,28 +250,6 @@ static __maybe_unused void *any_section_objs(const struct load_info *info, 
#define symversion(base, idx) ((base != NULL) ? ((base) + (idx)) : NULL)

#endif



struct symsearch {

	const struct kernel_symbol *start, *stop;

	const s32 *crcs;

	enum mod_license {

		NOT_GPL_ONLY,

		GPL_ONLY,

	} license;

};



struct find_symbol_arg {

	/* Input */

	const char *name;

	bool gplok;

	bool warn;



	/* Output */

	struct module *owner;

	const s32 *crc;

	const struct kernel_symbol *sym;

	enum mod_license license;

};



static bool check_exported_symbol(const struct symsearch *syms,

				  struct module *owner,

				  unsigned int symnum, void *data)
@@ -327,7 +311,7 @@ static bool find_exported_symbol_in_section(const struct symsearch *syms, 
 * Find an exported symbol and return it, along with, (optional) crc and

 * (optional) module which owns it.  Needs preempt disabled or module_mutex.

 */

static bool find_symbol(struct find_symbol_arg *fsa)

bool find_symbol(struct find_symbol_arg *fsa)

{

	static const struct symsearch arr[] = {

		{ __start___ksymtab, __stop___ksymtab, __start___kcrctab,
@@ -1001,7 +985,7 @@ size_t modinfo_attrs_count = ARRAY_SIZE(modinfo_attrs); 


static const char vermagic[] = VERMAGIC_STRING;



static int try_to_force_load(struct module *mod, const char *reason)

int try_to_force_load(struct module *mod, const char *reason)

{

#ifdef CONFIG_MODULE_FORCE_LOAD

	if (!test_taint(TAINT_FORCED_MODULE))
@@ -1013,115 +997,6 @@ static int try_to_force_load(struct module *mod, const char *reason) 
#endif

}



#ifdef CONFIG_MODVERSIONS



static u32 resolve_rel_crc(const s32 *crc)

{

	return *(u32 *)((void *)crc + *crc);

}



static int check_version(const struct load_info *info,

			 const char *symname,

			 struct module *mod,

			 const s32 *crc)

{

	Elf_Shdr *sechdrs = info->sechdrs;

	unsigned int versindex = info->index.vers;

	unsigned int i, num_versions;

	struct modversion_info *versions;



	/* Exporting module didn't supply crcs?  OK, we're already tainted. */

	if (!crc)

		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;



		if (IS_ENABLED(CONFIG_MODULE_REL_CRCS))

			crcval = resolve_rel_crc(crc);

		else

			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;

	}



	/* Broken toolchain. Warn once, then let it go.. */

	pr_warn_once("%s: no symbol version for %s\n", info->name, symname);

	return 1;



bad_version:

	pr_warn("%s: disagrees about version of symbol %s\n",

	       info->name, symname);

	return 0;

}



static inline int check_modstruct_version(const struct load_info *info,

					  struct module *mod)

{

	struct find_symbol_arg fsa = {

		.name	= "module_layout",

		.gplok	= true,

	};



	/*

	 * Since this should be found in kernel (which can't be removed), no

	 * locking is necessary -- use preempt_disable() to placate lockdep.

	 */

	preempt_disable();

	if (!find_symbol(&fsa)) {

		preempt_enable();

		BUG();

	}

	preempt_enable();

	return check_version(info, "module_layout", mod, fsa.crc);

}



/* First part is kernel version, which we ignore if module has crcs. */

static inline 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;

}

#else

static inline int check_version(const struct load_info *info,

				const char *symname,

				struct module *mod,

				const s32 *crc)

{

	return 1;

}



static inline int check_modstruct_version(const struct load_info *info,

					  struct module *mod)

{

	return 1;

}



static inline int same_magic(const char *amagic, const char *bmagic,

			     bool has_crcs)

{

	return strcmp(amagic, bmagic) == 0;

}

#endif /* CONFIG_MODVERSIONS */



static char *get_modinfo(const struct load_info *info, const char *tag);

static char *get_next_modinfo(const struct load_info *info, const char *tag,

			      char *prev);
@@ -3247,18 +3122,3 @@ void print_modules(void) 
		pr_cont(" [last unloaded: %s]", last_unloaded_module);

	pr_cont("\n");

}
 


#ifdef CONFIG_MODVERSIONS

/*

 * 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);

#endif

kernel/module/version.c

0 → 100644
+109 −0
Original line number Diff line number Diff line 
// 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"



static u32 resolve_rel_crc(const s32 *crc)

{

	return *(u32 *)((void *)crc + *crc);

}



int check_version(const struct load_info *info,

		  const char *symname,

			 struct module *mod,

			 const s32 *crc)

{

	Elf_Shdr *sechdrs = info->sechdrs;

	unsigned int versindex = info->index.vers;

	unsigned int i, num_versions;

	struct modversion_info *versions;



	/* Exporting module didn't supply crcs?  OK, we're already tainted. */

	if (!crc)

		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;



		if (IS_ENABLED(CONFIG_MODULE_REL_CRCS))

			crcval = resolve_rel_crc(crc);

		else

			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;

	}



	/* Broken toolchain. Warn once, then let it go.. */

	pr_warn_once("%s: no symbol version for %s\n", info->name, symname);

	return 1;



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,

	};



	/*

	 * Since this should be found in kernel (which can't be removed), no

	 * locking is necessary -- use preempt_disable() to placate lockdep.

	 */

	preempt_disable();

	if (!find_symbol(&fsa)) {

		preempt_enable();

		BUG();

	}

	preempt_enable();

	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;

}



/*

 * 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);