Commit 3a75ad14 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'modules-for-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux 

Pull modules updates from Jessica Yu:
 "Summary of modules changes for the 4.13 merge window:

   - Minor code cleanups

   - Avoid accessing mod struct prior to checking module struct version,
     from Kees

   - Fix racy atomic inc/dec logic of kmod_concurrent_max in kmod, from
     Luis"

* tag 'modules-for-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
  module: make the modinfo name const
  kmod: reduce atomic operations on kmod_concurrent and simplify
  module: use list_for_each_entry_rcu() on find_module_all()
  kernel/module.c: suppress warning about unused nowarn variable
  module: Add module name to modinfo
  module: Pass struct load_info into symbol checks
parents 235b84fc 96b5b194

kernel/kmod.c

+18 −22
Original line number Diff line number Diff line
@@ -45,8 +45,6 @@ 


#include <trace/events/module.h>



extern int max_threads;



#define CAP_BSET	(void *)1

#define CAP_PI		(void *)2
@@ -56,6 +54,20 @@ static DEFINE_SPINLOCK(umh_sysctl_lock); 
static DECLARE_RWSEM(umhelper_sem);



#ifdef CONFIG_MODULES

/*

 * Assuming:

 *

 * threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE,

 *		       (u64) THREAD_SIZE * 8UL);

 *

 * If you need less than 50 threads would mean we're dealing with systems

 * smaller than 3200 pages. This assuems you are capable of having ~13M memory,

 * and this would only be an be an upper limit, after which the OOM killer

 * would take effect. Systems like these are very unlikely if modules are

 * enabled.

 */

#define MAX_KMOD_CONCURRENT 50

static atomic_t kmod_concurrent_max = ATOMIC_INIT(MAX_KMOD_CONCURRENT);



/*

	modprobe_path is set via /proc/sys.
@@ -127,10 +139,7 @@ int __request_module(bool wait, const char *fmt, ...) 
{

	va_list args;

	char module_name[MODULE_NAME_LEN];

	unsigned int max_modprobes;

	int ret;

	static atomic_t kmod_concurrent = ATOMIC_INIT(0);

#define MAX_KMOD_CONCURRENT 50	/* Completely arbitrary value - KAO */

	static int kmod_loop_msg;



	/*
@@ -154,21 +163,7 @@ int __request_module(bool wait, const char *fmt, ...) 
	if (ret)

		return ret;



	/* If modprobe needs a service that is in a module, we get a recursive

	 * loop.  Limit the number of running kmod threads to max_threads/2 or

	 * MAX_KMOD_CONCURRENT, whichever is the smaller.  A cleaner method

	 * would be to run the parents of this process, counting how many times

	 * kmod was invoked.  That would mean accessing the internals of the

	 * process tables to get the command line, proc_pid_cmdline is static

	 * and it is not worth changing the proc code just to handle this case. 

	 * KAO.

	 *

	 * "trace the ppid" is simple, but will fail if someone's

	 * parent exits.  I think this is as good as it gets. --RR

	 */

	max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);

	atomic_inc(&kmod_concurrent);

	if (atomic_read(&kmod_concurrent) > max_modprobes) {

	if (atomic_dec_if_positive(&kmod_concurrent_max) < 0) {

		/* We may be blaming an innocent here, but unlikely */

		if (kmod_loop_msg < 5) {

			printk(KERN_ERR
@@ -176,7 +171,6 @@ int __request_module(bool wait, const char *fmt, ...) 
			       module_name);

			kmod_loop_msg++;

		}

		atomic_dec(&kmod_concurrent);

		return -ENOMEM;

	}
@@ -184,10 +178,12 @@ int __request_module(bool wait, const char *fmt, ...) 


	ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);



	atomic_dec(&kmod_concurrent);

	atomic_inc(&kmod_concurrent_max);



	return ret;

}

EXPORT_SYMBOL(__request_module);



#endif /* CONFIG_MODULES */



static void call_usermodehelper_freeinfo(struct subprocess_info *info)

kernel/module.c

+54 −31
Original line number Diff line number Diff line
@@ -300,6 +300,7 @@ int unregister_module_notifier(struct notifier_block *nb) 
EXPORT_SYMBOL(unregister_module_notifier);



struct load_info {

	const char *name;

	Elf_Ehdr *hdr;

	unsigned long len;

	Elf_Shdr *sechdrs;
@@ -600,7 +601,7 @@ static struct module *find_module_all(const char *name, size_t len, 


	module_assert_mutex_or_preempt();



	list_for_each_entry(mod, &modules, list) {

	list_for_each_entry_rcu(mod, &modules, list) {

		if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)

			continue;

		if (strlen(mod->name) == len && !memcmp(mod->name, name, len))
@@ -1273,12 +1274,13 @@ static u32 resolve_rel_crc(const s32 *crc) 
	return *(u32 *)((void *)crc + *crc);

}



static int check_version(Elf_Shdr *sechdrs,

			 unsigned int versindex,

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;
@@ -1312,17 +1314,16 @@ static int check_version(Elf_Shdr *sechdrs, 
	}



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

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

	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",

	       mod->name, symname);

	       info->name, symname);

	return 0;

}



static inline int check_modstruct_version(Elf_Shdr *sechdrs,

					  unsigned int versindex,

static inline int check_modstruct_version(const struct load_info *info,

					  struct module *mod)

{

	const s32 *crc;
@@ -1338,8 +1339,8 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs, 
		BUG();

	}

	preempt_enable();

	return check_version(sechdrs, versindex,

			     VMLINUX_SYMBOL_STR(module_layout), mod, crc);

	return check_version(info, VMLINUX_SYMBOL_STR(module_layout),

			     mod, crc);

}



/* First part is kernel version, which we ignore if module has crcs. */
@@ -1353,8 +1354,7 @@ static inline int same_magic(const char *amagic, const char *bmagic, 
	return strcmp(amagic, bmagic) == 0;

}

#else

static inline int check_version(Elf_Shdr *sechdrs,

				unsigned int versindex,

static inline int check_version(const struct load_info *info,

				const char *symname,

				struct module *mod,

				const s32 *crc)
@@ -1362,8 +1362,7 @@ static inline int check_version(Elf_Shdr *sechdrs, 
	return 1;

}



static inline int check_modstruct_version(Elf_Shdr *sechdrs,

					  unsigned int versindex,

static inline int check_modstruct_version(const struct load_info *info,

					  struct module *mod)

{

	return 1;
@@ -1399,7 +1398,7 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod, 
	if (!sym)

		goto unlock;



	if (!check_version(info->sechdrs, info->index.vers, name, mod, crc)) {

	if (!check_version(info, name, mod, crc)) {

		sym = ERR_PTR(-EINVAL);

		goto getname;

	}
@@ -1662,31 +1661,36 @@ static inline void remove_notes_attrs(struct module *mod) 
}

#endif /* CONFIG_KALLSYMS */



static void add_usage_links(struct module *mod)

static void del_usage_links(struct module *mod)

{

#ifdef CONFIG_MODULE_UNLOAD

	struct module_use *use;

	int nowarn;



	mutex_lock(&module_mutex);

	list_for_each_entry(use, &mod->target_list, target_list) {

		nowarn = sysfs_create_link(use->target->holders_dir,

					   &mod->mkobj.kobj, mod->name);

	}

	list_for_each_entry(use, &mod->target_list, target_list)

		sysfs_remove_link(use->target->holders_dir, mod->name);

	mutex_unlock(&module_mutex);

#endif

}



static void del_usage_links(struct module *mod)

static int add_usage_links(struct module *mod)

{

	int ret = 0;

#ifdef CONFIG_MODULE_UNLOAD

	struct module_use *use;



	mutex_lock(&module_mutex);

	list_for_each_entry(use, &mod->target_list, target_list)

		sysfs_remove_link(use->target->holders_dir, mod->name);

	list_for_each_entry(use, &mod->target_list, target_list) {

		ret = sysfs_create_link(use->target->holders_dir,

					&mod->mkobj.kobj, mod->name);

		if (ret)

			break;

	}

	mutex_unlock(&module_mutex);

	if (ret)

		del_usage_links(mod);

#endif

	return ret;

}



static int module_add_modinfo_attrs(struct module *mod)
@@ -1797,13 +1801,18 @@ static int mod_sysfs_setup(struct module *mod, 
	if (err)

		goto out_unreg_param;



	add_usage_links(mod);

	err = add_usage_links(mod);

	if (err)

		goto out_unreg_modinfo_attrs;



	add_sect_attrs(mod, info);

	add_notes_attrs(mod, info);



	kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD);

	return 0;



out_unreg_modinfo_attrs:

	module_remove_modinfo_attrs(mod);

out_unreg_param:

	module_param_sysfs_remove(mod);

out_unreg_holders:
@@ -2910,9 +2919,15 @@ static int rewrite_section_headers(struct load_info *info, int flags) 
		info->index.vers = 0; /* Pretend no __versions section! */

	else

		info->index.vers = find_sec(info, "__versions");

	info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;



	info->index.info = find_sec(info, ".modinfo");

	if (!info->index.info)

		info->name = "(missing .modinfo section)";

	else

		info->name = get_modinfo(info, "name");

	info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;

	info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;



	return 0;

}
@@ -2952,21 +2967,29 @@ static struct module *setup_load_info(struct load_info *info, int flags) 


	info->index.mod = find_sec(info, ".gnu.linkonce.this_module");

	if (!info->index.mod) {

		pr_warn("No module found in object\n");

		pr_warn("%s: No module found in object\n",

			info->name ?: "(missing .modinfo name field)");

		return ERR_PTR(-ENOEXEC);

	}

	/* This is temporary: point mod into copy of data. */

	mod = (void *)info->sechdrs[info->index.mod].sh_addr;



	/*

	 * If we didn't load the .modinfo 'name' field, fall back to

	 * on-disk struct mod 'name' field.

	 */

	if (!info->name)

		info->name = mod->name;



	if (info->index.sym == 0) {

		pr_warn("%s: module has no symbols (stripped?)\n", mod->name);

		pr_warn("%s: module has no symbols (stripped?)\n", info->name);

		return ERR_PTR(-ENOEXEC);

	}



	info->index.pcpu = find_pcpusec(info);



	/* Check module struct version now, before we try to use module. */

	if (!check_modstruct_version(info->sechdrs, info->index.vers, mod))

	if (!check_modstruct_version(info, mod))

		return ERR_PTR(-ENOEXEC);



	return mod;
@@ -2987,7 +3010,7 @@ static int check_modinfo(struct module *mod, struct load_info *info, int flags) 
			return err;

	} else if (!same_magic(modmagic, vermagic, info->index.vers)) {

		pr_err("%s: version magic '%s' should be '%s'\n",

		       mod->name, modmagic, vermagic);

		       info->name, modmagic, vermagic);

		return -ENOEXEC;

	}
@@ -3237,7 +3260,7 @@ int __weak module_frob_arch_sections(Elf_Ehdr *hdr, 


/* module_blacklist is a comma-separated list of module names */

static char *module_blacklist;

static bool blacklisted(char *module_name)

static bool blacklisted(const char *module_name)

{

	const char *p;

	size_t len;
@@ -3267,7 +3290,7 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) 
	if (IS_ERR(mod))

		return mod;



	if (blacklisted(mod->name))

	if (blacklisted(info->name))

		return ERR_PTR(-EPERM);



	err = check_modinfo(mod, info, flags);

scripts/mod/modpost.c

+1 −0
Original line number Diff line number Diff line
@@ -2126,6 +2126,7 @@ static void add_header(struct buffer *b, struct module *mod) 
	buf_printf(b, "#include <linux/compiler.h>\n");

	buf_printf(b, "\n");

	buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n");

	buf_printf(b, "MODULE_INFO(name, KBUILD_MODNAME);\n");

	buf_printf(b, "\n");

	buf_printf(b, "__visible struct module __this_module\n");

	buf_printf(b, "__attribute__((section(\".gnu.linkonce.this_module\"))) = {\n");

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