// SPDX-License-Identifier: GPL-2.0-or-later

/*

* Copyright (C) 2002 Richard Henderson

* Copyright (C) 2001 Rusty Russell, 2002, 2010 Rusty Russell IBM.

*/

#define INCLUDE_VERMAGIC

#include <linux/export.h>

#include <linux/extable.h>

#include <linux/moduleloader.h>

#include <linux/module_signature.h>

#include <linux/trace_events.h>

#include <linux/init.h>

#include <linux/kallsyms.h>

#include <linux/file.h>

#include <linux/fs.h>

#include <linux/sysfs.h>

#include <linux/kernel.h>

#include <linux/kernel_read_file.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>

#include <linux/elf.h>

#include <linux/proc_fs.h>

#include <linux/security.h>

#include <linux/seq_file.h>

#include <linux/syscalls.h>

#include <linux/fcntl.h>

#include <linux/rcupdate.h>

#include <linux/capability.h>

#include <linux/cpu.h>

#include <linux/moduleparam.h>

#include <linux/errno.h>

#include <linux/err.h>

#include <linux/vermagic.h>

#include <linux/notifier.h>

#include <linux/sched.h>

#include <linux/device.h>

#include <linux/string.h>

#include <linux/mutex.h>

#include <linux/rculist.h>

#include <linux/uaccess.h>

#include <asm/cacheflush.h>

#include <linux/set_memory.h>

#include <asm/mmu_context.h>

#include <linux/license.h>

#include <asm/sections.h>

#include <linux/tracepoint.h>

#include <linux/ftrace.h>

#include <linux/livepatch.h>

#include <linux/async.h>

#include <linux/percpu.h>

#include <linux/kmemleak.h>

#include <linux/jump_label.h>

#include <linux/pfn.h>

#include <linux/bsearch.h>

#include <linux/dynamic_debug.h>

#include <linux/audit.h>

#include <uapi/linux/module.h>

#include "module-internal.h"

#define CREATE_TRACE_POINTS

#include <trace/events/module.h>

#ifndef ARCH_SHF_SMALL

#define ARCH_SHF_SMALL 0

#endif

/*

* Modules' sections will be aligned on page boundaries

* to ensure complete separation of code and data, but

* only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y

*/

#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX

# define debug_align(X) ALIGN(X, PAGE_SIZE)

#else

# define debug_align(X) (X)

#endif

/* If this is set, the section belongs in the init part of the module */

#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))

/*

* Mutex protects:

* 1) List of modules (also safely readable with preempt_disable),

* 2) module_use links,

* 3) module_addr_min/module_addr_max.

* (delete and add uses RCU list operations).

*/

DEFINE_MUTEX(module_mutex);

EXPORT_SYMBOL_GPL(module_mutex);

static LIST_HEAD(modules);

/* Work queue for freeing init sections in success case */

static void do_free_init(struct work_struct *w);

static DECLARE_WORK(init_free_wq, do_free_init);

static LLIST_HEAD(init_free_list);

#ifdef CONFIG_MODULES_TREE_LOOKUP

/*

* Use a latched RB-tree for __module_address(); this allows us to use

* RCU-sched lookups of the address from any context.

*

* This is conditional on PERF_EVENTS || TRACING because those can really hit

* __module_address() hard by doing a lot of stack unwinding; potentially from

* NMI context.

*/

static __always_inline unsigned long __mod_tree_val(struct latch_tree_node *n)

{

struct module_layout *layout = container_of(n, struct module_layout, mtn.node);

return (unsigned long)layout->base;

}

static __always_inline unsigned long __mod_tree_size(struct latch_tree_node *n)

{

struct module_layout *layout = container_of(n, struct module_layout, mtn.node);

return (unsigned long)layout->size;

}

static __always_inline bool

mod_tree_less(struct latch_tree_node *a, struct latch_tree_node *b)

{

return __mod_tree_val(a) < __mod_tree_val(b);

}

static __always_inline int

mod_tree_comp(void *key, struct latch_tree_node *n)

{

unsigned long val = (unsigned long)key;

unsigned long start, end;

start = __mod_tree_val(n);

if (val < start)

return -1;

end = start + __mod_tree_size(n);

if (val >= end)

return 1;

return 0;

}

static const struct latch_tree_ops mod_tree_ops = {

.less = mod_tree_less,

.comp = mod_tree_comp,

};

static struct mod_tree_root {

struct latch_tree_root root;

unsigned long addr_min;

unsigned long addr_max;

} mod_tree __cacheline_aligned = {

.addr_min = -1UL,

};

#define module_addr_min mod_tree.addr_min

#define module_addr_max mod_tree.addr_max

static noinline void __mod_tree_insert(struct mod_tree_node *node)

{

latch_tree_insert(&node->node, &mod_tree.root, &mod_tree_ops);

}

static void __mod_tree_remove(struct mod_tree_node *node)

{

latch_tree_erase(&node->node, &mod_tree.root, &mod_tree_ops);

}

/*

* These modifications: insert, remove_init and remove; are serialized by the

* module_mutex.

*/

static void mod_tree_insert(struct module *mod)

{

mod->core_layout.mtn.mod = mod;

mod->init_layout.mtn.mod = mod;

__mod_tree_insert(&mod->core_layout.mtn);

if (mod->init_layout.size)

__mod_tree_insert(&mod->init_layout.mtn);

}

static void mod_tree_remove_init(struct module *mod)

{

if (mod->init_layout.size)

__mod_tree_remove(&mod->init_layout.mtn);

}

static void mod_tree_remove(struct module *mod)

{

__mod_tree_remove(&mod->core_layout.mtn);

mod_tree_remove_init(mod);

}

static struct module *mod_find(unsigned long addr)

{

struct latch_tree_node *ltn;

ltn = latch_tree_find((void *)addr, &mod_tree.root, &mod_tree_ops);

if (!ltn)

return NULL;

return container_of(ltn, struct mod_tree_node, node)->mod;

}

#else /* MODULES_TREE_LOOKUP */

static unsigned long module_addr_min = -1UL, module_addr_max = 0;

static void mod_tree_insert(struct module *mod) { }

static void mod_tree_remove_init(struct module *mod) { }

static void mod_tree_remove(struct module *mod) { }

static struct module *mod_find(unsigned long addr)

{

struct module *mod;

list_for_each_entry_rcu(mod, &modules, list,

lockdep_is_held(&module_mutex)) {

if (within_module(addr, mod))

return mod;

}

return NULL;

}

#endif /* MODULES_TREE_LOOKUP */

/*

* Bounds of module text, for speeding up __module_address.

* Protected by module_mutex.

*/

static void __mod_update_bounds(void *base, unsigned int size)

{

unsigned long min = (unsigned long)base;

unsigned long max = min + size;

if (min < module_addr_min)

module_addr_min = min;

if (max > module_addr_max)

module_addr_max = max;

}

static void mod_update_bounds(struct module *mod)

{

__mod_update_bounds(mod->core_layout.base, mod->core_layout.size);

if (mod->init_layout.size)

__mod_update_bounds(mod->init_layout.base, mod->init_layout.size);

}

#ifdef CONFIG_KGDB_KDB

struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */

#endif /* CONFIG_KGDB_KDB */

static void module_assert_mutex(void)

{

lockdep_assert_held(&module_mutex);

}

static void module_assert_mutex_or_preempt(void)

{

#ifdef CONFIG_LOCKDEP

if (unlikely(!debug_locks))

return;

WARN_ON_ONCE(!rcu_read_lock_sched_held() &&

!lockdep_is_held(&module_mutex));

#endif

}

static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);

module_param(sig_enforce, bool_enable_only, 0644);

/*

* Export sig_enforce kernel cmdline parameter to allow other subsystems rely

* on that instead of directly to CONFIG_MODULE_SIG_FORCE config.

*/

bool is_module_sig_enforced(void)

{

return sig_enforce;

}

EXPORT_SYMBOL(is_module_sig_enforced);

void set_module_sig_enforced(void)

{

sig_enforce = true;

}

/* Block module loading/unloading? */

int modules_disabled = 0;

core_param(nomodule, modules_disabled, bint, 0);

/* Waiting for a module to finish initializing? */

static DECLARE_WAIT_QUEUE_HEAD(module_wq);

static BLOCKING_NOTIFIER_HEAD(module_notify_list);

int register_module_notifier(struct notifier_block *nb)

{

return blocking_notifier_chain_register(&module_notify_list, nb);

}

EXPORT_SYMBOL(register_module_notifier);

int unregister_module_notifier(struct notifier_block *nb)

{

return blocking_notifier_chain_unregister(&module_notify_list, nb);

}

EXPORT_SYMBOL(unregister_module_notifier);

/*

* We require a truly strong try_module_get(): 0 means success.

* Otherwise an error is returned due to ongoing or failed

* initialization etc.

*/

static inline int strong_try_module_get(struct module *mod)

{

BUG_ON(mod && mod->state == MODULE_STATE_UNFORMED);

if (mod && mod->state == MODULE_STATE_COMING)

return -EBUSY;

if (try_module_get(mod))

return 0;

else

return -ENOENT;

}

static inline void add_taint_module(struct module *mod, unsigned flag,

enum lockdep_ok lockdep_ok)

{

add_taint(flag, lockdep_ok);

set_bit(flag, &mod->taints);

}

/*

* A thread that wants to hold a reference to a module only while it

* is running can call this to safely exit. nfsd and lockd use this.

*/

void __noreturn __module_put_and_exit(struct module *mod, long code)

{

module_put(mod);

do_exit(code);

}

EXPORT_SYMBOL(__module_put_and_exit);

/* Find a module section: 0 means not found. */

static unsigned int find_sec(const struct load_info *info, const char *name)

{

unsigned int i;

for (i = 1; i < info->hdr->e_shnum; i++) {

Elf_Shdr *shdr = &info->sechdrs[i];

/* Alloc bit cleared means "ignore it." */

if ((shdr->sh_flags & SHF_ALLOC)

&& strcmp(info->secstrings + shdr->sh_name, name) == 0)

return i;

}

return 0;

}

/* Find a module section, or NULL. */

static void *section_addr(const struct load_info *info, const char *name)

{

/* Section 0 has sh_addr 0. */

return (void *)info->sechdrs[find_sec(info, name)].sh_addr;

}

/* Find a module section, or NULL. Fill in number of "objects" in section. */

static void *section_objs(const struct load_info *info,

const char *name,

size_t object_size,

unsigned int *num)

{

unsigned int sec = find_sec(info, name);

/* Section 0 has sh_addr 0 and sh_size 0. */

*num = info->sechdrs[sec].sh_size / object_size;

return (void *)info->sechdrs[sec].sh_addr;

}

/* Find a module section: 0 means not found. Ignores SHF_ALLOC flag. */

static unsigned int find_any_sec(const struct load_info *info, const char *name)

{

unsigned int i;

for (i = 1; i < info->hdr->e_shnum; i++) {

Elf_Shdr *shdr = &info->sechdrs[i];

if (strcmp(info->secstrings + shdr->sh_name, name) == 0)

return i;

}

return 0;

}

/*

* Find a module section, or NULL. Fill in number of "objects" in section.

* Ignores SHF_ALLOC flag.

*/

static __maybe_unused void *any_section_objs(const struct load_info *info,

const char *name,

size_t object_size,

unsigned int *num)

{

unsigned int sec = find_any_sec(info, name);

/* Section 0 has sh_addr 0 and sh_size 0. */

*num = info->sechdrs[sec].sh_size / object_size;

return (void *)info->sechdrs[sec].sh_addr;

}

/* Provided by the linker */

extern const struct kernel_symbol __start___ksymtab[];

extern const struct kernel_symbol __stop___ksymtab[];

extern const struct kernel_symbol __start___ksymtab_gpl[];

extern const struct kernel_symbol __stop___ksymtab_gpl[];

extern const struct kernel_symbol __start___ksymtab_gpl_future[];

extern const struct kernel_symbol __stop___ksymtab_gpl_future[];

extern const s32 __start___kcrctab[];

extern const s32 __start___kcrctab_gpl[];

extern const s32 __start___kcrctab_gpl_future[];

#ifdef CONFIG_UNUSED_SYMBOLS

extern const struct kernel_symbol __start___ksymtab_unused[];

extern const struct kernel_symbol __stop___ksymtab_unused[];

extern const struct kernel_symbol __start___ksymtab_unused_gpl[];

extern const struct kernel_symbol __stop___ksymtab_unused_gpl[];

extern const s32 __start___kcrctab_unused[];

extern const s32 __start___kcrctab_unused_gpl[];

#endif

#ifndef CONFIG_MODVERSIONS

#define symversion(base, idx) NULL

#else

#define symversion(base, idx) ((base != NULL) ? ((base) + (idx)) : NULL)

#endif

static bool each_symbol_in_section(const struct symsearch *arr,

unsigned int arrsize,

struct module *owner,

bool (*fn)(const struct symsearch *syms,

struct module *owner,

void *data),

void *data)

{

unsigned int j;

for (j = 0; j < arrsize; j++) {

if (fn(&arr[j], owner, data))

return true;

}

return false;

}

/* Returns true as soon as fn returns true, otherwise false. */

static bool each_symbol_section(bool (*fn)(const struct symsearch *arr,

struct module *owner,

void *data),

void *data)

{

struct module *mod;

static const struct symsearch arr[] = {

{ __start___ksymtab, __stop___ksymtab, __start___kcrctab,

NOT_GPL_ONLY, false },

{ __start___ksymtab_gpl, __stop___ksymtab_gpl,

__start___kcrctab_gpl,

GPL_ONLY, false },

{ __start___ksymtab_gpl_future, __stop___ksymtab_gpl_future,

__start___kcrctab_gpl_future,

WILL_BE_GPL_ONLY, false },

#ifdef CONFIG_UNUSED_SYMBOLS

{ __start___ksymtab_unused, __stop___ksymtab_unused,

__start___kcrctab_unused,

NOT_GPL_ONLY, true },

{ __start___ksymtab_unused_gpl, __stop___ksymtab_unused_gpl,

__start___kcrctab_unused_gpl,

GPL_ONLY, true },

#endif

};

module_assert_mutex_or_preempt();

if (each_symbol_in_section(arr, ARRAY_SIZE(arr), NULL, fn, data))

return true;

list_for_each_entry_rcu(mod, &modules, list,

lockdep_is_held(&module_mutex)) {

struct symsearch arr[] = {

{ mod->syms, mod->syms + mod->num_syms, mod->crcs,

NOT_GPL_ONLY, false },

{ mod->gpl_syms, mod->gpl_syms + mod->num_gpl_syms,

mod->gpl_crcs,

GPL_ONLY, false },

{ mod->gpl_future_syms,

mod->gpl_future_syms + mod->num_gpl_future_syms,

mod->gpl_future_crcs,

WILL_BE_GPL_ONLY, false },

#ifdef CONFIG_UNUSED_SYMBOLS

{ mod->unused_syms,

mod->unused_syms + mod->num_unused_syms,

mod->unused_crcs,

NOT_GPL_ONLY, true },

{ mod->unused_gpl_syms,

mod->unused_gpl_syms + mod->num_unused_gpl_syms,

mod->unused_gpl_crcs,

GPL_ONLY, true },

#endif

};

if (mod->state == MODULE_STATE_UNFORMED)

continue;

if (each_symbol_in_section(arr, ARRAY_SIZE(arr), mod, fn, data))

return true;

}

return false;

}

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)

{

struct find_symbol_arg *fsa = data;

if (!fsa->gplok) {

if (syms->license == GPL_ONLY)

return false;

if (syms->license == WILL_BE_GPL_ONLY && fsa->warn) {

pr_warn("Symbol %s is being used by a non-GPL module, "

"which will not be allowed in the future\n",

fsa->name);

}

}

#ifdef CONFIG_UNUSED_SYMBOLS

if (syms->unused && fsa->warn) {

pr_warn("Symbol %s is marked as UNUSED, however this module is "

"using it.\n", fsa->name);

pr_warn("This symbol will go away in the future.\n");

pr_warn("Please evaluate if this is the right api to use and "

"if it really is, submit a report to the linux kernel "

"mailing list together with submitting your code for "

"inclusion.\n");

}

#endif

fsa->owner = owner;

fsa->crc = symversion(syms->crcs, symnum);

fsa->sym = &syms->start[symnum];

fsa->license = syms->license;

return true;

}

static unsigned long kernel_symbol_value(const struct kernel_symbol *sym)

{

#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS

return (unsigned long)offset_to_ptr(&sym->value_offset);

#else

return sym->value;

#endif

}

static const char *kernel_symbol_name(const struct kernel_symbol *sym)

{

#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS

return offset_to_ptr(&sym->name_offset);

#else

return sym->name;

#endif

}

static const char *kernel_symbol_namespace(const struct kernel_symbol *sym)

{

#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS

if (!sym->namespace_offset)

return NULL;

return offset_to_ptr(&sym->namespace_offset);

#else

return sym->namespace;

#endif

}

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

{

return strcmp(name, kernel_symbol_name(sym));

}

static bool find_exported_symbol_in_section(const struct symsearch *syms,

struct module *owner,

void *data)

{

struct find_symbol_arg *fsa = data;

struct kernel_symbol *sym;

sym = bsearch(fsa->name, syms->start, syms->stop - syms->start,

sizeof(struct kernel_symbol), cmp_name);

if (sym != NULL && check_exported_symbol(syms, owner,

sym - syms->start, data))

return true;

return false;

}

/*

* Find an exported symbol and return it, along with, (optional) crc and

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

*/

static const struct kernel_symbol *find_symbol(const char *name,

struct module **owner,

const s32 **crc,

enum mod_license *license,

bool gplok,

bool warn)

{

struct find_symbol_arg fsa;

fsa.name = name;

fsa.gplok = gplok;

fsa.warn = warn;

if (each_symbol_section(find_exported_symbol_in_section, &fsa)) {

if (owner)

*owner = fsa.owner;

if (crc)

*crc = fsa.crc;

if (license)

*license = fsa.license;

return fsa.sym;

}

pr_debug("Failed to find symbol %s\n", name);

return NULL;

}

/*

* Search for module by name: must hold module_mutex (or preempt disabled

* for read-only access).

*/

static struct module *find_module_all(const char *name, size_t len,

bool even_unformed)

{

struct module *mod;

module_assert_mutex_or_preempt();

list_for_each_entry_rcu(mod, &modules, list,

lockdep_is_held(&module_mutex)) {

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

continue;

if (strlen(mod->name) == len && !memcmp(mod->name, name, len))

return mod;

}

return NULL;

}

struct module *find_module(const char *name)

{

module_assert_mutex();

return find_module_all(name, strlen(name), false);

}

EXPORT_SYMBOL_GPL(find_module);

#ifdef CONFIG_SMP

static inline void __percpu *mod_percpu(struct module *mod)

{

return mod->percpu;

}

static int percpu_modalloc(struct module *mod, struct load_info *info)

{

Elf_Shdr *pcpusec = &info->sechdrs[info->index.pcpu];

unsigned long align = pcpusec->sh_addralign;

if (!pcpusec->sh_size)

return 0;

if (align > PAGE_SIZE) {

pr_warn("%s: per-cpu alignment %li > %li\n",

mod->name, align, PAGE_SIZE);

align = PAGE_SIZE;

}

mod->percpu = __alloc_reserved_percpu(pcpusec->sh_size, align);

if (!mod->percpu) {

pr_warn("%s: Could not allocate %lu bytes percpu data\n",

mod->name, (unsigned long)pcpusec->sh_size);

return -ENOMEM;

}

mod->percpu_size = pcpusec->sh_size;

return 0;

}

static void percpu_modfree(struct module *mod)

{

free_percpu(mod->percpu);

}

static unsigned int find_pcpusec(struct load_info *info)

{

return find_sec(info, ".data..percpu");

}

static void percpu_modcopy(struct module *mod,

const void *from, unsigned long size)

{

int cpu;

for_each_possible_cpu(cpu)

memcpy(per_cpu_ptr(mod->percpu, cpu), from, size);

}

bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)

{

struct module *mod;

unsigned int cpu;

preempt_disable();

list_for_each_entry_rcu(mod, &modules, list) {

if (mod->state == MODULE_STATE_UNFORMED)

continue;

if (!mod->percpu_size)

continue;

for_each_possible_cpu(cpu) {

void *start = per_cpu_ptr(mod->percpu, cpu);

void *va = (void *)addr;

if (va >= start && va < start + mod->percpu_size) {

if (can_addr) {

*can_addr = (unsigned long) (va - start);

*can_addr += (unsigned long)

per_cpu_ptr(mod->percpu,

get_boot_cpu_id());

}

preempt_enable();

return true;

}

}

}

preempt_enable();

return false;

}

/**

* is_module_percpu_address() - test whether address is from module static percpu

* @addr: address to test

*

* Test whether @addr belongs to module static percpu area.

*

* Return: %true if @addr is from module static percpu area

*/

bool is_module_percpu_address(unsigned long addr)

{

return __is_module_percpu_address(addr, NULL);

}

#else /* ... !CONFIG_SMP */

static inline void __percpu *mod_percpu(struct module *mod)

{

return NULL;

}

static int percpu_modalloc(struct module *mod, struct load_info *info)

{

/* UP modules shouldn't have this section: ENOMEM isn't quite right */

if (info->sechdrs[info->index.pcpu].sh_size != 0)

return -ENOMEM;

return 0;

}

static inline void percpu_modfree(struct module *mod)

{

}

static unsigned int find_pcpusec(struct load_info *info)

{

return 0;

}

static inline void percpu_modcopy(struct module *mod,

const void *from, unsigned long size)

{

/* pcpusec should be 0, and size of that section should be 0. */

BUG_ON(size != 0);

}

bool is_module_percpu_address(unsigned long addr)

{

return false;

}

bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)

{

return false;

}

#endif /* CONFIG_SMP */

#define MODINFO_ATTR(field) \

static void setup_modinfo_##field(struct module *mod, const char *s) \

{ \

mod->field = kstrdup(s, GFP_KERNEL); \

} \

static ssize_t show_modinfo_##field(struct module_attribute *mattr, \

struct module_kobject *mk, char *buffer) \

{ \

return scnprintf(buffer, PAGE_SIZE, "%s\n", mk->mod->field); \

} \

static int modinfo_##field##_exists(struct module *mod) \

{ \

return mod->field != NULL; \

} \

static void free_modinfo_##field(struct module *mod) \

{ \

kfree(mod->field); \

mod->field = NULL; \

} \

static struct module_attribute modinfo_##field = { \

.attr = { .name = __stringify(field), .mode = 0444 }, \

.show = show_modinfo_##field, \

.setup = setup_modinfo_##field, \

.test = modinfo_##field##_exists, \

.free = free_modinfo_##field, \

};

MODINFO_ATTR(version);

MODINFO_ATTR(srcversion);

static char last_unloaded_module[MODULE_NAME_LEN+1];

#ifdef CONFIG_MODULE_UNLOAD

EXPORT_TRACEPOINT_SYMBOL(module_get);

/* MODULE_REF_BASE is the base reference count by kmodule loader. */

#define MODULE_REF_BASE 1

/* Init the unload section of the module. */

static int module_unload_init(struct module *mod)

{

/*

* Initialize reference counter to MODULE_REF_BASE.

* refcnt == 0 means module is going.

*/

atomic_set(&mod->refcnt, MODULE_REF_BASE);

INIT_LIST_HEAD(&mod->source_list);

INIT_LIST_HEAD(&mod->target_list);

/* Hold reference count during initialization. */

atomic_inc(&mod->refcnt);

return 0;

}

/* Does a already use b? */

static int already_uses(struct module *a, struct module *b)

{

struct module_use *use;

list_for_each_entry(use, &b->source_list, source_list) {

if (use->source == a) {

pr_debug("%s uses %s!\n", a->name, b->name);

return 1;

}

}

pr_debug("%s does not use %s!\n", a->name, b->name);

return 0;

}

/*

* Module a uses b

* - we add 'a' as a "source", 'b' as a "target" of module use

* - the module_use is added to the list of 'b' sources (so

* 'b' can walk the list to see who sourced them), and of 'a'

* targets (so 'a' can see what modules it targets).

*/

static int add_module_usage(struct module *a, struct module *b)

{

struct module_use *use;

pr_debug("Allocating new usage for %s.\n", a->name);

use = kmalloc(sizeof(*use), GFP_ATOMIC);

if (!use)

return -ENOMEM;

use->source = a;

use->target = b;

list_add(&use->source_list, &b->source_list);

list_add(&use->target_list, &a->target_list);

return 0;

}

/* Module a uses b: caller needs module_mutex() */

static int ref_module(struct module *a, struct module *b)

{

int err;

if (b == NULL || already_uses(a, b))

return 0;

/* If module isn't available, we fail. */

err = strong_try_module_get(b);

if (err)

return err;

err = add_module_usage(a, b);

if (err) {

module_put(b);

return err;

}

return 0;

}

/* Clear the unload stuff of the module. */

static void module_unload_free(struct module *mod)

{

struct module_use *use, *tmp;

mutex_lock(&module_mutex);

list_for_each_entry_safe(use, tmp, &mod->target_list, target_list) {

struct module *i = use->target;

pr_debug("%s unusing %s\n", mod->name, i->name);

module_put(i);

list_del(&use->source_list);

list_del(&use->target_list);

kfree(use);

}

mutex_unlock(&module_mutex);

}

#ifdef CONFIG_MODULE_FORCE_UNLOAD

static inline int try_force_unload(unsigned int flags)

{

int ret = (flags & O_TRUNC);

if (ret)

add_taint(TAINT_FORCED_RMMOD, LOCKDEP_NOW_UNRELIABLE);

return ret;

}

#else

static inline int try_force_unload(unsigned int flags)

{

return 0;

}

#endif /* CONFIG_MODULE_FORCE_UNLOAD */

/* Try to release refcount of module, 0 means success. */

static int try_release_module_ref(struct module *mod)

{

int ret;

/* Try to decrement refcnt which we set at loading */

ret = atomic_sub_return(MODULE_REF_BASE, &mod->refcnt);

BUG_ON(ret < 0);

if (ret)

/* Someone can put this right now, recover with checking */

ret = atomic_add_unless(&mod->refcnt, MODULE_REF_BASE, 0);

return ret;

}

static int try_stop_module(struct module *mod, int flags, int *forced)

{

/* If it's not unused, quit unless we're forcing. */

if (try_release_module_ref(mod) != 0) {

*forced = try_force_unload(flags);

if (!(*forced))

return -EWOULDBLOCK;

}

/* Mark it as dying. */

mod->state = MODULE_STATE_GOING;

return 0;

}

/**

* module_refcount() - return the refcount or -1 if unloading

* @mod: the module we're checking

*

* Return:

* -1 if the module is in the process of unloading

* otherwise the number of references in the kernel to the module

*/

int module_refcount(struct module *mod)

{

return atomic_read(&mod->refcnt) - MODULE_REF_BASE;

}