Merge tag 'modules-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof...

[linux.git] / kernel / module / main.c

// 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/buildid.h>
#include <linux/fs.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/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 "internal.h"

#define CREATE_TRACE_POINTS
#include <trace/events/module.h>

/*
 * Mutex protects:
 * 1) List of modules (also safely readable with preempt_disable),
 * 2) module_use links,
 * 3) mod_tree.addr_min/mod_tree.addr_max.
 * (delete and add uses RCU list operations).
 */
DEFINE_MUTEX(module_mutex);
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);

struct mod_tree_root mod_tree __cacheline_aligned = {
        .addr_min = -1UL,
};

#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
struct mod_tree_root mod_data_tree __cacheline_aligned = {
        .addr_min = -1UL,
};
#endif

#define module_addr_min mod_tree.addr_min
#define module_addr_max mod_tree.addr_max

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.
 */
static void __mod_update_bounds(void *base, unsigned int size, struct mod_tree_root *tree)
{
        unsigned long min = (unsigned long)base;
        unsigned long max = min + size;

        if (min < tree->addr_min)
                tree->addr_min = min;
        if (max > tree->addr_max)
                tree->addr_max = max;
}

static void mod_update_bounds(struct module *mod)
{
        __mod_update_bounds(mod->core_layout.base, mod->core_layout.size, &mod_tree);
        if (mod->init_layout.size)
                __mod_update_bounds(mod->init_layout.base, mod->init_layout.size, &mod_tree);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
        __mod_update_bounds(mod->data_layout.base, mod->data_layout.size, &mod_data_tree);
#endif
}

/* Block module loading/unloading? */
int modules_disabled;
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.
 */
void __noreturn __module_put_and_kthread_exit(struct module *mod, long code)
{
        module_put(mod);
        kthread_exit(code);
}
EXPORT_SYMBOL(__module_put_and_kthread_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;
}

#ifndef CONFIG_MODVERSIONS
#define symversion(base, idx) NULL
#else
#define symversion(base, idx) ((base != NULL) ? ((base) + (idx)) : NULL)
#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
}

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,
                                            struct find_symbol_arg *fsa)
{
        struct kernel_symbol *sym;

        if (!fsa->gplok && syms->license == GPL_ONLY)
                return false;

        sym = bsearch(fsa->name, syms->start, syms->stop - syms->start,
                        sizeof(struct kernel_symbol), cmp_name);
        if (!sym)
                return false;

        fsa->owner = owner;
        fsa->crc = symversion(syms->crcs, sym - syms->start);
        fsa->sym = sym;
        fsa->license = syms->license;

        return true;
}

/*
 * Find an exported symbol and return it, along with, (optional) crc and
 * (optional) module which owns it.  Needs preempt disabled or module_mutex.
 */
bool find_symbol(struct find_symbol_arg *fsa)
{
        static const struct symsearch arr[] = {
                { __start___ksymtab, __stop___ksymtab, __start___kcrctab,
                  NOT_GPL_ONLY },
                { __start___ksymtab_gpl, __stop___ksymtab_gpl,
                  __start___kcrctab_gpl,
                  GPL_ONLY },
        };
        struct module *mod;
        unsigned int i;

        module_assert_mutex_or_preempt();

        for (i = 0; i < ARRAY_SIZE(arr); i++)
                if (find_exported_symbol_in_section(&arr[i], NULL, fsa))
                        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 },
                        { mod->gpl_syms, mod->gpl_syms + mod->num_gpl_syms,
                          mod->gpl_crcs,
                          GPL_ONLY },
                };

                if (mod->state == MODULE_STATE_UNFORMED)
                        continue;

                for (i = 0; i < ARRAY_SIZE(arr); i++)
                        if (find_exported_symbol_in_section(&arr[i], mod, fsa))
                                return true;
        }

        pr_debug("Failed to find symbol %s\n", fsa->name);
        return false;
}

/*
 * Search for module by name: must hold module_mutex (or preempt disabled
 * for read-only access).
 */
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)
{
        return find_module_all(name, strlen(name), false);
}

#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 struct {
        char name[MODULE_NAME_LEN + 1];
        char taints[MODULE_FLAGS_BUF_SIZE];
} last_unloaded_module;

#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;
}
EXPORT_SYMBOL(module_refcount);

/* This exists whether we can unload or not */
static void free_module(struct module *mod);

SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
                unsigned int, flags)
{
        struct module *mod;
        char name[MODULE_NAME_LEN];
        char buf[MODULE_FLAGS_BUF_SIZE];
        int ret, forced = 0;

        if (!capable(CAP_SYS_MODULE) || modules_disabled)
                return -EPERM;

        if (strncpy_from_user(name, name_user, MODULE_NAME_LEN-1) < 0)
                return -EFAULT;
        name[MODULE_NAME_LEN-1] = '\0';

        audit_log_kern_module(name);

        if (mutex_lock_interruptible(&module_mutex) != 0)
                return -EINTR;

        mod = find_module(name);
        if (!mod) {
                ret = -ENOENT;
                goto out;
        }

        if (!list_empty(&mod->source_list)) {
                /* Other modules depend on us: get rid of them first. */
                ret = -EWOULDBLOCK;
                goto out;
        }

        /* Doing init or already dying? */
        if (mod->state != MODULE_STATE_LIVE) {
                /* FIXME: if (force), slam module count damn the torpedoes */
                pr_debug("%s already dying\n", mod->name);
                ret = -EBUSY;
                goto out;
        }

        /* If it has an init func, it must have an exit func to unload */
        if (mod->init && !mod->exit) {
                forced = try_force_unload(flags);
                if (!forced) {
                        /* This module can't be removed */
                        ret = -EBUSY;
                        goto out;
                }
        }

        ret = try_stop_module(mod, flags, &forced);
        if (ret != 0)
                goto out;

        mutex_unlock(&module_mutex);
        /* Final destruction now no one is using it. */
        if (mod->exit != NULL)
                mod->exit();
        blocking_notifier_call_chain(&module_notify_list,
                                     MODULE_STATE_GOING, mod);
        klp_module_going(mod);
        ftrace_release_mod(mod);

        async_synchronize_full();

        /* Store the name and taints of the last unloaded module for diagnostic purposes */
        strscpy(last_unloaded_module.name, mod->name, sizeof(last_unloaded_module.name));
        strscpy(last_unloaded_module.taints, module_flags(mod, buf, false), sizeof(last_unloaded_module.taints));

        free_module(mod);
        /* someone could wait for the module in add_unformed_module() */
        wake_up_all(&module_wq);
        return 0;
out:
        mutex_unlock(&module_mutex);
        return ret;
}

void __symbol_put(const char *symbol)
{
        struct find_symbol_arg fsa = {
                .name   = symbol,
                .gplok  = true,
        };

        preempt_disable();
        BUG_ON(!find_symbol(&fsa));
        module_put(fsa.owner);
        preempt_enable();
}
EXPORT_SYMBOL(__symbol_put);

/* Note this assumes addr is a function, which it currently always is. */
void symbol_put_addr(void *addr)
{
        struct module *modaddr;
        unsigned long a = (unsigned long)dereference_function_descriptor(addr);

        if (core_kernel_text(a))
                return;

        /*
         * Even though we hold a reference on the module; we still need to
         * disable preemption in order to safely traverse the data structure.
         */
        preempt_disable();
        modaddr = __module_text_address(a);
        BUG_ON(!modaddr);
        module_put(modaddr);
        preempt_enable();
}
EXPORT_SYMBOL_GPL(symbol_put_addr);

static ssize_t show_refcnt(struct module_attribute *mattr,
                           struct module_kobject *mk, char *buffer)
{
        return sprintf(buffer, "%i\n", module_refcount(mk->mod));
}

static struct module_attribute modinfo_refcnt =
        __ATTR(refcnt, 0444, show_refcnt, NULL);

void __module_get(struct module *module)
{
        if (module) {
                preempt_disable();
                atomic_inc(&module->refcnt);
                trace_module_get(module, _RET_IP_);
                preempt_enable();
        }
}
EXPORT_SYMBOL(__module_get);

bool try_module_get(struct module *module)
{
        bool ret = true;

        if (module) {
                preempt_disable();
                /* Note: here, we can fail to get a reference */
                if (likely(module_is_live(module) &&
                           atomic_inc_not_zero(&module->refcnt) != 0))
                        trace_module_get(module, _RET_IP_);
                else
                        ret = false;

                preempt_enable();
        }
        return ret;
}
EXPORT_SYMBOL(try_module_get);

void module_put(struct module *module)
{
        int ret;

        if (module) {
                preempt_disable();
                ret = atomic_dec_if_positive(&module->refcnt);
                WARN_ON(ret < 0);       /* Failed to put refcount */
                trace_module_put(module, _RET_IP_);
                preempt_enable();
        }
}
EXPORT_SYMBOL(module_put);

#else /* !CONFIG_MODULE_UNLOAD */
static inline void module_unload_free(struct module *mod)
{
}

static int ref_module(struct module *a, struct module *b)
{
        return strong_try_module_get(b);
}

static inline int module_unload_init(struct module *mod)
{
        return 0;
}
#endif /* CONFIG_MODULE_UNLOAD */

size_t module_flags_taint(unsigned long taints, char *buf)
{
        size_t l = 0;
        int i;

        for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
                if (taint_flags[i].module && test_bit(i, &taints))
                        buf[l++] = taint_flags[i].c_true;
        }

        return l;
}

static ssize_t show_initstate(struct module_attribute *mattr,
                              struct module_kobject *mk, char *buffer)
{
        const char *state = "unknown";

        switch (mk->mod->state) {
        case MODULE_STATE_LIVE:
                state = "live";
                break;
        case MODULE_STATE_COMING:
                state = "coming";
                break;
        case MODULE_STATE_GOING:
                state = "going";
                break;
        default:
                BUG();
        }
        return sprintf(buffer, "%s\n", state);
}

static struct module_attribute modinfo_initstate =
        __ATTR(initstate, 0444, show_initstate, NULL);

static ssize_t store_uevent(struct module_attribute *mattr,
                            struct module_kobject *mk,
                            const char *buffer, size_t count)
{
        int rc;

        rc = kobject_synth_uevent(&mk->kobj, buffer, count);
        return rc ? rc : count;
}

struct module_attribute module_uevent =
        __ATTR(uevent, 0200, NULL, store_uevent);

static ssize_t show_coresize(struct module_attribute *mattr,
                             struct module_kobject *mk, char *buffer)
{
        return sprintf(buffer, "%u\n", mk->mod->core_layout.size);
}

static struct module_attribute modinfo_coresize =
        __ATTR(coresize, 0444, show_coresize, NULL);

#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
static ssize_t show_datasize(struct module_attribute *mattr,
                             struct module_kobject *mk, char *buffer)
{
        return sprintf(buffer, "%u\n", mk->mod->data_layout.size);
}

static struct module_attribute modinfo_datasize =
        __ATTR(datasize, 0444, show_datasize, NULL);
#endif

static ssize_t show_initsize(struct module_attribute *mattr,
                             struct module_kobject *mk, char *buffer)
{
        return sprintf(buffer, "%u\n", mk->mod->init_layout.size);
}

static struct module_attribute modinfo_initsize =
        __ATTR(initsize, 0444, show_initsize, NULL);

static ssize_t show_taint(struct module_attribute *mattr,
                          struct module_kobject *mk, char *buffer)
{
        size_t l;

        l = module_flags_taint(mk->mod->taints, buffer);
        buffer[l++] = '\n';
        return l;
}

static struct module_attribute modinfo_taint =
        __ATTR(taint, 0444, show_taint, NULL);

struct module_attribute *modinfo_attrs[] = {
        &module_uevent,
        &modinfo_version,
        &modinfo_srcversion,
        &modinfo_initstate,
        &modinfo_coresize,
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
        &modinfo_datasize,
#endif
        &modinfo_initsize,
        &modinfo_taint,
#ifdef CONFIG_MODULE_UNLOAD
        &modinfo_refcnt,
#endif
        NULL,
};

size_t modinfo_attrs_count = ARRAY_SIZE(modinfo_attrs);

static const char vermagic[] = VERMAGIC_STRING;

int try_to_force_load(struct module *mod, const char *reason)
{
#ifdef CONFIG_MODULE_FORCE_LOAD
        if (!test_taint(TAINT_FORCED_MODULE))
                pr_warn("%s: %s: kernel tainted.\n", mod->name, reason);
        add_taint_module(mod, TAINT_FORCED_MODULE, LOCKDEP_NOW_UNRELIABLE);
        return 0;
#else
        return -ENOEXEC;
#endif
}

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);

static int verify_namespace_is_imported(const struct load_info *info,
                                        const struct kernel_symbol *sym,
                                        struct module *mod)
{
        const char *namespace;
        char *imported_namespace;

        namespace = kernel_symbol_namespace(sym);
        if (namespace && namespace[0]) {
                imported_namespace = get_modinfo(info, "import_ns");
                while (imported_namespace) {
                        if (strcmp(namespace, imported_namespace) == 0)
                                return 0;
                        imported_namespace = get_next_modinfo(
                                info, "import_ns", imported_namespace);
                }
#ifdef CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
                pr_warn(
#else
                pr_err(
#endif
                        "%s: module uses symbol (%s) from namespace %s, but does not import it.\n",
                        mod->name, kernel_symbol_name(sym), namespace);
#ifndef CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
                return -EINVAL;
#endif
        }
        return 0;
}

static bool inherit_taint(struct module *mod, struct module *owner, const char *name)
{
        if (!owner || !test_bit(TAINT_PROPRIETARY_MODULE, &owner->taints))
                return true;

        if (mod->using_gplonly_symbols) {
                pr_err("%s: module using GPL-only symbols uses symbols %s from proprietary module %s.\n",
                        mod->name, name, owner->name);
                return false;
        }

        if (!test_bit(TAINT_PROPRIETARY_MODULE, &mod->taints)) {
                pr_warn("%s: module uses symbols %s from proprietary module %s, inheriting taint.\n",
                        mod->name, name, owner->name);
                set_bit(TAINT_PROPRIETARY_MODULE, &mod->taints);
        }
        return true;
}

/* Resolve a symbol for this module.  I.e. if we find one, record usage. */
static const struct kernel_symbol *resolve_symbol(struct module *mod,
                                                  const struct load_info *info,
                                                  const char *name,
                                                  char ownername[])
{
        struct find_symbol_arg fsa = {
                .name   = name,
                .gplok  = !(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)),
                .warn   = true,
        };
        int err;

        /*
         * The module_mutex should not be a heavily contended lock;
         * if we get the occasional sleep here, we'll go an extra iteration
         * in the wait_event_interruptible(), which is harmless.
         */
        sched_annotate_sleep();
        mutex_lock(&module_mutex);
        if (!find_symbol(&fsa))
                goto unlock;

        if (fsa.license == GPL_ONLY)
                mod->using_gplonly_symbols = true;

        if (!inherit_taint(mod, fsa.owner, name)) {
                fsa.sym = NULL;
                goto getname;
        }

        if (!check_version(info, name, mod, fsa.crc)) {
                fsa.sym = ERR_PTR(-EINVAL);
                goto getname;
        }

        err = verify_namespace_is_imported(info, fsa.sym, mod);
        if (err) {
                fsa.sym = ERR_PTR(err);
                goto getname;
        }

        err = ref_module(mod, fsa.owner);
        if (err) {
                fsa.sym = ERR_PTR(err);
                goto getname;
        }

getname:
        /* We must make copy under the lock if we failed to get ref. */
        strncpy(ownername, module_name(fsa.owner), MODULE_NAME_LEN);
unlock:
        mutex_unlock(&module_mutex);
        return fsa.sym;
}

static const struct kernel_symbol *
resolve_symbol_wait(struct module *mod,
                    const struct load_info *info,
                    const char *name)
{
        const struct kernel_symbol *ksym;
        char owner[MODULE_NAME_LEN];

        if (wait_event_interruptible_timeout(module_wq,
                        !IS_ERR(ksym = resolve_symbol(mod, info, name, owner))
                        || PTR_ERR(ksym) != -EBUSY,
                                             30 * HZ) <= 0) {
                pr_warn("%s: gave up waiting for init of module %s.\n",
                        mod->name, owner);
        }
        return ksym;
}

void __weak module_memfree(void *module_region)
{
        /*
         * This memory may be RO, and freeing RO memory in an interrupt is not
         * supported by vmalloc.
         */
        WARN_ON(in_interrupt());
        vfree(module_region);
}

void __weak module_arch_cleanup(struct module *mod)
{
}

void __weak module_arch_freeing_init(struct module *mod)
{
}

static void cfi_cleanup(struct module *mod);

/* Free a module, remove from lists, etc. */
static void free_module(struct module *mod)
{
        trace_module_free(mod);

        mod_sysfs_teardown(mod);

        /*
         * We leave it in list to prevent duplicate loads, but make sure
         * that noone uses it while it's being deconstructed.
         */
        mutex_lock(&module_mutex);
        mod->state = MODULE_STATE_UNFORMED;
        mutex_unlock(&module_mutex);

        /* Remove dynamic debug info */
        ddebug_remove_module(mod->name);

        /* Arch-specific cleanup. */
        module_arch_cleanup(mod);

        /* Module unload stuff */
        module_unload_free(mod);

        /* Free any allocated parameters. */
        destroy_params(mod->kp, mod->num_kp);

        if (is_livepatch_module(mod))
                free_module_elf(mod);

        /* Now we can delete it from the lists */
        mutex_lock(&module_mutex);
        /* Unlink carefully: kallsyms could be walking list. */
        list_del_rcu(&mod->list);
        mod_tree_remove(mod);
        /* Remove this module from bug list, this uses list_del_rcu */
        module_bug_cleanup(mod);
        /* Wait for RCU-sched synchronizing before releasing mod->list and buglist. */
        synchronize_rcu();
        if (try_add_tainted_module(mod))
                pr_err("%s: adding tainted module to the unloaded tainted modules list failed.\n",
                       mod->name);
        mutex_unlock(&module_mutex);

        /* Clean up CFI for the module. */
        cfi_cleanup(mod);

        /* This may be empty, but that's OK */
        module_arch_freeing_init(mod);
        module_memfree(mod->init_layout.base);
        kfree(mod->args);
        percpu_modfree(mod);

        /* Free lock-classes; relies on the preceding sync_rcu(). */
        lockdep_free_key_range(mod->data_layout.base, mod->data_layout.size);

        /* Finally, free the core (containing the module structure) */
        module_memfree(mod->core_layout.base);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
        vfree(mod->data_layout.base);
#endif
}

void *__symbol_get(const char *symbol)
{
        struct find_symbol_arg fsa = {
                .name   = symbol,
                .gplok  = true,
                .warn   = true,
        };

        preempt_disable();
        if (!find_symbol(&fsa) || strong_try_module_get(fsa.owner)) {
                preempt_enable();
                return NULL;
        }
        preempt_enable();
        return (void *)kernel_symbol_value(fsa.sym);
}
EXPORT_SYMBOL_GPL(__symbol_get);

/*
 * Ensure that an exported symbol [global namespace] does not already exist
 * in the kernel or in some other module's exported symbol table.
 *
 * You must hold the module_mutex.
 */
static int verify_exported_symbols(struct module *mod)
{
        unsigned int i;
        const struct kernel_symbol *s;
        struct {
                const struct kernel_symbol *sym;
                unsigned int num;
        } arr[] = {
                { mod->syms, mod->num_syms },
                { mod->gpl_syms, mod->num_gpl_syms },
        };

        for (i = 0; i < ARRAY_SIZE(arr); i++) {
                for (s = arr[i].sym; s < arr[i].sym + arr[i].num; s++) {
                        struct find_symbol_arg fsa = {
                                .name   = kernel_symbol_name(s),
                                .gplok  = true,
                        };
                        if (find_symbol(&fsa)) {
                                pr_err("%s: exports duplicate symbol %s"
                                       " (owned by %s)\n",
                                       mod->name, kernel_symbol_name(s),
                                       module_name(fsa.owner));
                                return -ENOEXEC;
                        }
                }
        }
        return 0;
}

static bool ignore_undef_symbol(Elf_Half emachine, const char *name)
{
        /*
         * On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as
         * before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ on x86-64.
         * i386 has a similar problem but may not deserve a fix.
         *
         * If we ever have to ignore many symbols, consider refactoring the code to
         * only warn if referenced by a relocation.
         */
        if (emachine == EM_386 || emachine == EM_X86_64)
                return !strcmp(name, "_GLOBAL_OFFSET_TABLE_");
        return false;
}

/* Change all symbols so that st_value encodes the pointer directly. */
static int simplify_symbols(struct module *mod, const struct load_info *info)
{
        Elf_Shdr *symsec = &info->sechdrs[info->index.sym];
        Elf_Sym *sym = (void *)symsec->sh_addr;
        unsigned long secbase;
        unsigned int i;
        int ret = 0;
        const struct kernel_symbol *ksym;

        for (i = 1; i < symsec->sh_size / sizeof(Elf_Sym); i++) {
                const char *name = info->strtab + sym[i].st_name;

                switch (sym[i].st_shndx) {
                case SHN_COMMON:
                        /* Ignore common symbols */
                        if (!strncmp(name, "__gnu_lto", 9))
                                break;

                        /*
                         * We compiled with -fno-common.  These are not
                         * supposed to happen.
                         */
                        pr_debug("Common symbol: %s\n", name);
                        pr_warn("%s: please compile with -fno-common\n",
                               mod->name);
                        ret = -ENOEXEC;
                        break;

                case SHN_ABS:
                        /* Don't need to do anything */
                        pr_debug("Absolute symbol: 0x%08lx\n",
                               (long)sym[i].st_value);
                        break;

                case SHN_LIVEPATCH:
                        /* Livepatch symbols are resolved by livepatch */
                        break;

                case SHN_UNDEF:
                        ksym = resolve_symbol_wait(mod, info, name);
                        /* Ok if resolved.  */
                        if (ksym && !IS_ERR(ksym)) {
                                sym[i].st_value = kernel_symbol_value(ksym);
                                break;
                        }

                        /* Ok if weak or ignored.  */
                        if (!ksym &&
                            (ELF_ST_BIND(sym[i].st_info) == STB_WEAK ||
                             ignore_undef_symbol(info->hdr->e_machine, name)))
                                break;

                        ret = PTR_ERR(ksym) ?: -ENOENT;
                        pr_warn("%s: Unknown symbol %s (err %d)\n",
                                mod->name, name, ret);
                        break;

                default:
                        /* Divert to percpu allocation if a percpu var. */
                        if (sym[i].st_shndx == info->index.pcpu)
                                secbase = (unsigned long)mod_percpu(mod);
                        else
                                secbase = info->sechdrs[sym[i].st_shndx].sh_addr;
                        sym[i].st_value += secbase;
                        break;
                }
        }

        return ret;
}

static int apply_relocations(struct module *mod, const struct load_info *info)
{
        unsigned int i;
        int err = 0;

        /* Now do relocations. */
        for (i = 1; i < info->hdr->e_shnum; i++) {
                unsigned int infosec = info->sechdrs[i].sh_info;

                /* Not a valid relocation section? */
                if (infosec >= info->hdr->e_shnum)
                        continue;

                /* Don't bother with non-allocated sections */
                if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC))
                        continue;

                if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH)
                        err = klp_apply_section_relocs(mod, info->sechdrs,
                                                       info->secstrings,
                                                       info->strtab,
                                                       info->index.sym, i,
                                                       NULL);
                else if (info->sechdrs[i].sh_type == SHT_REL)
                        err = apply_relocate(info->sechdrs, info->strtab,
                                             info->index.sym, i, mod);
                else if (info->sechdrs[i].sh_type == SHT_RELA)
                        err = apply_relocate_add(info->sechdrs, info->strtab,
                                                 info->index.sym, i, mod);
                if (err < 0)
                        break;
        }
        return err;
}

/* Additional bytes needed by arch in front of individual sections */
unsigned int __weak arch_mod_section_prepend(struct module *mod,
                                             unsigned int section)
{
        /* default implementation just returns zero */
        return 0;
}

/* Update size with this section: return offset. */
long module_get_offset(struct module *mod, unsigned int *size,
                       Elf_Shdr *sechdr, unsigned int section)
{
        long ret;

        *size += arch_mod_section_prepend(mod, section);
        ret = ALIGN(*size, sechdr->sh_addralign ?: 1);
        *size = ret + sechdr->sh_size;
        return ret;
}

static bool module_init_layout_section(const char *sname)
{
#ifndef CONFIG_MODULE_UNLOAD
        if (module_exit_section(sname))
                return true;
#endif
        return module_init_section(sname);
}

/*
 * Lay out the SHF_ALLOC sections in a way not dissimilar to how ld
 * might -- code, read-only data, read-write data, small data.  Tally
 * sizes, and place the offsets into sh_entsize fields: high bit means it
 * belongs in init.
 */
static void layout_sections(struct module *mod, struct load_info *info)
{
        static unsigned long const masks[][2] = {
                /*
                 * NOTE: all executable code must be the first section
                 * in this array; otherwise modify the text_size
                 * finder in the two loops below
                 */
                { SHF_EXECINSTR | SHF_ALLOC, ARCH_SHF_SMALL },
                { SHF_ALLOC, SHF_WRITE | ARCH_SHF_SMALL },
                { SHF_RO_AFTER_INIT | SHF_ALLOC, ARCH_SHF_SMALL },
                { SHF_WRITE | SHF_ALLOC, ARCH_SHF_SMALL },
                { ARCH_SHF_SMALL | SHF_ALLOC, 0 }
        };
        unsigned int m, i;

        for (i = 0; i < info->hdr->e_shnum; i++)
                info->sechdrs[i].sh_entsize = ~0UL;

        pr_debug("Core section allocation order:\n");
        for (m = 0; m < ARRAY_SIZE(masks); ++m) {
                for (i = 0; i < info->hdr->e_shnum; ++i) {
                        Elf_Shdr *s = &info->sechdrs[i];
                        const char *sname = info->secstrings + s->sh_name;
                        unsigned int *sizep;

                        if ((s->sh_flags & masks[m][0]) != masks[m][0]
                            || (s->sh_flags & masks[m][1])
                            || s->sh_entsize != ~0UL
                            || module_init_layout_section(sname))
                                continue;
                        sizep = m ? &mod->data_layout.size : &mod->core_layout.size;
                        s->sh_entsize = module_get_offset(mod, sizep, s, i);
                        pr_debug("\t%s\n", sname);
                }
                switch (m) {
                case 0: /* executable */
                        mod->core_layout.size = strict_align(mod->core_layout.size);
                        mod->core_layout.text_size = mod->core_layout.size;
                        break;
                case 1: /* RO: text and ro-data */
                        mod->data_layout.size = strict_align(mod->data_layout.size);
                        mod->data_layout.ro_size = mod->data_layout.size;
                        break;
                case 2: /* RO after init */
                        mod->data_layout.size = strict_align(mod->data_layout.size);
                        mod->data_layout.ro_after_init_size = mod->data_layout.size;
                        break;
                case 4: /* whole core */
                        mod->data_layout.size = strict_align(mod->data_layout.size);
                        break;
                }
        }

        pr_debug("Init section allocation order:\n");
        for (m = 0; m < ARRAY_SIZE(masks); ++m) {
                for (i = 0; i < info->hdr->e_shnum; ++i) {
                        Elf_Shdr *s = &info->sechdrs[i];
                        const char *sname = info->secstrings + s->sh_name;

                        if ((s->sh_flags & masks[m][0]) != masks[m][0]
                            || (s->sh_flags & masks[m][1])
                            || s->sh_entsize != ~0UL
                            || !module_init_layout_section(sname))
                                continue;
                        s->sh_entsize = (module_get_offset(mod, &mod->init_layout.size, s, i)
                                         | INIT_OFFSET_MASK);
                        pr_debug("\t%s\n", sname);
                }
                switch (m) {
                case 0: /* executable */
                        mod->init_layout.size = strict_align(mod->init_layout.size);
                        mod->init_layout.text_size = mod->init_layout.size;
                        break;
                case 1: /* RO: text and ro-data */
                        mod->init_layout.size = strict_align(mod->init_layout.size);
                        mod->init_layout.ro_size = mod->init_layout.size;
                        break;
                case 2:
                        /*
                         * RO after init doesn't apply to init_layout (only
                         * core_layout), so it just takes the value of ro_size.
                         */
                        mod->init_layout.ro_after_init_size = mod->init_layout.ro_size;
                        break;
                case 4: /* whole init */
                        mod->init_layout.size = strict_align(mod->init_layout.size);
                        break;
                }
        }
}

static void set_license(struct module *mod, const char *license)
{
        if (!license)
                license = "unspecified";

        if (!license_is_gpl_compatible(license)) {
                if (!test_taint(TAINT_PROPRIETARY_MODULE))
                        pr_warn("%s: module license '%s' taints kernel.\n",
                                mod->name, license);
                add_taint_module(mod, TAINT_PROPRIETARY_MODULE,
                                 LOCKDEP_NOW_UNRELIABLE);
        }
}

/* Parse tag=value strings from .modinfo section */
static char *next_string(char *string, unsigned long *secsize)
{
        /* Skip non-zero chars */
        while (string[0]) {
                string++;
                if ((*secsize)-- <= 1)
                        return NULL;
        }

        /* Skip any zero padding. */
        while (!string[0]) {
                string++;
                if ((*secsize)-- <= 1)
                        return NULL;
        }
        return string;
}

static char *get_next_modinfo(const struct load_info *info, const char *tag,
                              char *prev)
{
        char *p;
        unsigned int taglen = strlen(tag);
        Elf_Shdr *infosec = &info->sechdrs[info->index.info];
        unsigned long size = infosec->sh_size;

        /*
         * get_modinfo() calls made before rewrite_section_headers()
         * must use sh_offset, as sh_addr isn't set!
         */
        char *modinfo = (char *)info->hdr + infosec->sh_offset;

        if (prev) {
                size -= prev - modinfo;
                modinfo = next_string(prev, &size);
        }

        for (p = modinfo; p; p = next_string(p, &size)) {
                if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
                        return p + taglen + 1;
        }
        return NULL;
}

static char *get_modinfo(const struct load_info *info, const char *tag)
{
        return get_next_modinfo(info, tag, NULL);
}

static void setup_modinfo(struct module *mod, struct load_info *info)
{
        struct module_attribute *attr;
        int i;

        for (i = 0; (attr = modinfo_attrs[i]); i++) {
                if (attr->setup)
                        attr->setup(mod, get_modinfo(info, attr->attr.name));
        }
}

static void free_modinfo(struct module *mod)
{
        struct module_attribute *attr;
        int i;

        for (i = 0; (attr = modinfo_attrs[i]); i++) {
                if (attr->free)
                        attr->free(mod);
        }
}

static void dynamic_debug_setup(struct module *mod, struct _ddebug *debug, unsigned int num)
{
        if (!debug)
                return;
        ddebug_add_module(debug, num, mod->name);
}

static void dynamic_debug_remove(struct module *mod, struct _ddebug *debug)
{
        if (debug)
                ddebug_remove_module(mod->name);
}

void * __weak module_alloc(unsigned long size)
{
        return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
                        GFP_KERNEL, PAGE_KERNEL_EXEC, VM_FLUSH_RESET_PERMS,
                        NUMA_NO_NODE, __builtin_return_address(0));
}

bool __weak module_init_section(const char *name)
{
        return strstarts(name, ".init");
}

bool __weak module_exit_section(const char *name)
{
        return strstarts(name, ".exit");
}

static int validate_section_offset(struct load_info *info, Elf_Shdr *shdr)
{
#if defined(CONFIG_64BIT)
        unsigned long long secend;
#else
        unsigned long secend;
#endif

        /*
         * Check for both overflow and offset/size being
         * too large.
         */
        secend = shdr->sh_offset + shdr->sh_size;
        if (secend < shdr->sh_offset || secend > info->len)
                return -ENOEXEC;

        return 0;
}

/*
 * Sanity checks against invalid binaries, wrong arch, weird elf version.
 *
 * Also do basic validity checks against section offsets and sizes, the
 * section name string table, and the indices used for it (sh_name).
 */
static int elf_validity_check(struct load_info *info)
{
        unsigned int i;
        Elf_Shdr *shdr, *strhdr;
        int err;

        if (info->len < sizeof(*(info->hdr))) {
                pr_err("Invalid ELF header len %lu\n", info->len);
                goto no_exec;
        }

        if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0) {
                pr_err("Invalid ELF header magic: != %s\n", ELFMAG);
                goto no_exec;
        }
        if (info->hdr->e_type != ET_REL) {
                pr_err("Invalid ELF header type: %u != %u\n",
                       info->hdr->e_type, ET_REL);
                goto no_exec;
        }
        if (!elf_check_arch(info->hdr)) {
                pr_err("Invalid architecture in ELF header: %u\n",
                       info->hdr->e_machine);
                goto no_exec;
        }
        if (info->hdr->e_shentsize != sizeof(Elf_Shdr)) {
                pr_err("Invalid ELF section header size\n");
                goto no_exec;
        }

        /*
         * e_shnum is 16 bits, and sizeof(Elf_Shdr) is
         * known and small. So e_shnum * sizeof(Elf_Shdr)
         * will not overflow unsigned long on any platform.
         */
        if (info->hdr->e_shoff >= info->len
            || (info->hdr->e_shnum * sizeof(Elf_Shdr) >
                info->len - info->hdr->e_shoff)) {
                pr_err("Invalid ELF section header overflow\n");
                goto no_exec;
        }

        info->sechdrs = (void *)info->hdr + info->hdr->e_shoff;

        /*
         * Verify if the section name table index is valid.
         */
        if (info->hdr->e_shstrndx == SHN_UNDEF
            || info->hdr->e_shstrndx >= info->hdr->e_shnum) {
                pr_err("Invalid ELF section name index: %d || e_shstrndx (%d) >= e_shnum (%d)\n",
                       info->hdr->e_shstrndx, info->hdr->e_shstrndx,
                       info->hdr->e_shnum);
                goto no_exec;
        }

        strhdr = &info->sechdrs[info->hdr->e_shstrndx];
        err = validate_section_offset(info, strhdr);
        if (err < 0) {
                pr_err("Invalid ELF section hdr(type %u)\n", strhdr->sh_type);
                return err;
        }

        /*
         * The section name table must be NUL-terminated, as required
         * by the spec. This makes strcmp and pr_* calls that access
         * strings in the section safe.
         */
        info->secstrings = (void *)info->hdr + strhdr->sh_offset;
        if (strhdr->sh_size == 0) {
                pr_err("empty section name table\n");
                goto no_exec;
        }
        if (info->secstrings[strhdr->sh_size - 1] != '\0') {
                pr_err("ELF Spec violation: section name table isn't null terminated\n");
                goto no_exec;
        }

        /*
         * The code assumes that section 0 has a length of zero and
         * an addr of zero, so check for it.
         */
        if (info->sechdrs[0].sh_type != SHT_NULL
            || info->sechdrs[0].sh_size != 0
            || info->sechdrs[0].sh_addr != 0) {
                pr_err("ELF Spec violation: section 0 type(%d)!=SH_NULL or non-zero len or addr\n",
                       info->sechdrs[0].sh_type);
                goto no_exec;
        }

        for (i = 1; i < info->hdr->e_shnum; i++) {
                shdr = &info->sechdrs[i];
                switch (shdr->sh_type) {
                case SHT_NULL:
                case SHT_NOBITS:
                        continue;
                case SHT_SYMTAB:
                        if (shdr->sh_link == SHN_UNDEF
                            || shdr->sh_link >= info->hdr->e_shnum) {
                                pr_err("Invalid ELF sh_link!=SHN_UNDEF(%d) or (sh_link(%d) >= hdr->e_shnum(%d)\n",
                                       shdr->sh_link, shdr->sh_link,
                                       info->hdr->e_shnum);
                                goto no_exec;
                        }
                        fallthrough;
                default:
                        err = validate_section_offset(info, shdr);
                        if (err < 0) {
                                pr_err("Invalid ELF section in module (section %u type %u)\n",
                                        i, shdr->sh_type);
                                return err;
                        }

                        if (shdr->sh_flags & SHF_ALLOC) {
                                if (shdr->sh_name >= strhdr->sh_size) {
                                        pr_err("Invalid ELF section name in module (section %u type %u)\n",
                                               i, shdr->sh_type);
                                        return -ENOEXEC;
                                }
                        }
                        break;
                }
        }

        return 0;

no_exec:
        return -ENOEXEC;
}

#define COPY_CHUNK_SIZE (16*PAGE_SIZE)

static int copy_chunked_from_user(void *dst, const void __user *usrc, unsigned long len)
{
        do {
                unsigned long n = min(len, COPY_CHUNK_SIZE);

                if (copy_from_user(dst, usrc, n) != 0)
                        return -EFAULT;
                cond_resched();
                dst += n;
                usrc += n;
                len -= n;
        } while (len);
        return 0;
}

static int check_modinfo_livepatch(struct module *mod, struct load_info *info)
{
        if (!get_modinfo(info, "livepatch"))
                /* Nothing more to do */
                return 0;

        if (set_livepatch_module(mod)) {
                add_taint_module(mod, TAINT_LIVEPATCH, LOCKDEP_STILL_OK);
                pr_notice_once("%s: tainting kernel with TAINT_LIVEPATCH\n",
                                mod->name);
                return 0;
        }

        pr_err("%s: module is marked as livepatch module, but livepatch support is disabled",
               mod->name);
        return -ENOEXEC;
}

static void check_modinfo_retpoline(struct module *mod, struct load_info *info)
{
        if (retpoline_module_ok(get_modinfo(info, "retpoline")))
                return;

        pr_warn("%s: loading module not compiled with retpoline compiler.\n",
                mod->name);
}

/* Sets info->hdr and info->len. */
static int copy_module_from_user(const void __user *umod, unsigned long len,
                                  struct load_info *info)
{
        int err;

        info->len = len;
        if (info->len < sizeof(*(info->hdr)))
                return -ENOEXEC;

        err = security_kernel_load_data(LOADING_MODULE, true);
        if (err)
                return err;

        /* Suck in entire file: we'll want most of it. */
        info->hdr = __vmalloc(info->len, GFP_KERNEL | __GFP_NOWARN);
        if (!info->hdr)
                return -ENOMEM;

        if (copy_chunked_from_user(info->hdr, umod, info->len) != 0) {
                err = -EFAULT;
                goto out;
        }

        err = security_kernel_post_load_data((char *)info->hdr, info->len,
                                             LOADING_MODULE, "init_module");
out:
        if (err)
                vfree(info->hdr);

        return err;
}

static void free_copy(struct load_info *info, int flags)
{
        if (flags & MODULE_INIT_COMPRESSED_FILE)
                module_decompress_cleanup(info);
        else
                vfree(info->hdr);
}

static int rewrite_section_headers(struct load_info *info, int flags)
{
        unsigned int i;

        /* This should always be true, but let's be sure. */
        info->sechdrs[0].sh_addr = 0;

        for (i = 1; i < info->hdr->e_shnum; i++) {
                Elf_Shdr *shdr = &info->sechdrs[i];

                /*
                 * Mark all sections sh_addr with their address in the
                 * temporary image.
                 */
                shdr->sh_addr = (size_t)info->hdr + shdr->sh_offset;

        }

        /* Track but don't keep modinfo and version sections. */
        info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;
        info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;

        return 0;
}

/*
 * Set up our basic convenience variables (pointers to section headers,
 * search for module section index etc), and do some basic section
 * verification.
 *
 * Set info->mod to the temporary copy of the module in info->hdr. The final one
 * will be allocated in move_module().
 */
static int setup_load_info(struct load_info *info, int flags)
{
        unsigned int i;

        /* Try to find a name early so we can log errors with a module name */
        info->index.info = find_sec(info, ".modinfo");
        if (info->index.info)
                info->name = get_modinfo(info, "name");

        /* Find internal symbols and strings. */
        for (i = 1; i < info->hdr->e_shnum; i++) {
                if (info->sechdrs[i].sh_type == SHT_SYMTAB) {
                        info->index.sym = i;
                        info->index.str = info->sechdrs[i].sh_link;
                        info->strtab = (char *)info->hdr
                                + info->sechdrs[info->index.str].sh_offset;
                        break;
                }
        }

        if (info->index.sym == 0) {
                pr_warn("%s: module has no symbols (stripped?)\n",
                        info->name ?: "(missing .modinfo section or name field)");
                return -ENOEXEC;
        }

        info->index.mod = find_sec(info, ".gnu.linkonce.this_module");
        if (!info->index.mod) {
                pr_warn("%s: No module found in object\n",
                        info->name ?: "(missing .modinfo section or name field)");
                return -ENOEXEC;
        }
        /* This is temporary: point mod into copy of data. */
        info->mod = (void *)info->hdr + info->sechdrs[info->index.mod].sh_offset;

        /*
         * If we didn't load the .modinfo 'name' field earlier, fall back to
         * on-disk struct mod 'name' field.
         */
        if (!info->name)
                info->name = info->mod->name;

        if (flags & MODULE_INIT_IGNORE_MODVERSIONS)
                info->index.vers = 0; /* Pretend no __versions section! */
        else
                info->index.vers = find_sec(info, "__versions");

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

        return 0;
}

static int check_modinfo(struct module *mod, struct load_info *info, int flags)
{
        const char *modmagic = get_modinfo(info, "vermagic");
        int err;

        if (flags & MODULE_INIT_IGNORE_VERMAGIC)
                modmagic = NULL;

        /* This is allowed: modprobe --force will invalidate it. */
        if (!modmagic) {
                err = try_to_force_load(mod, "bad vermagic");
                if (err)
                        return err;
        } else if (!same_magic(modmagic, vermagic, info->index.vers)) {
                pr_err("%s: version magic '%s' should be '%s'\n",
                       info->name, modmagic, vermagic);
                return -ENOEXEC;
        }

        if (!get_modinfo(info, "intree")) {
                if (!test_taint(TAINT_OOT_MODULE))
                        pr_warn("%s: loading out-of-tree module taints kernel.\n",
                                mod->name);
                add_taint_module(mod, TAINT_OOT_MODULE, LOCKDEP_STILL_OK);
        }

        check_modinfo_retpoline(mod, info);

        if (get_modinfo(info, "staging")) {
                add_taint_module(mod, TAINT_CRAP, LOCKDEP_STILL_OK);
                pr_warn("%s: module is from the staging directory, the quality "
                        "is unknown, you have been warned.\n", mod->name);
        }

        err = check_modinfo_livepatch(mod, info);
        if (err)
                return err;

        /* Set up license info based on the info section */
        set_license(mod, get_modinfo(info, "license"));

        if (get_modinfo(info, "test")) {
                if (!test_taint(TAINT_TEST))
                        pr_warn("%s: loading test module taints kernel.\n",
                                mod->name);
                add_taint_module(mod, TAINT_TEST, LOCKDEP_STILL_OK);
        }

        return 0;
}

static int find_module_sections(struct module *mod, struct load_info *info)
{
        mod->kp = section_objs(info, "__param",
                               sizeof(*mod->kp), &mod->num_kp);
        mod->syms = section_objs(info, "__ksymtab",
                                 sizeof(*mod->syms), &mod->num_syms);
        mod->crcs = section_addr(info, "__kcrctab");
        mod->gpl_syms = section_objs(info, "__ksymtab_gpl",
                                     sizeof(*mod->gpl_syms),
                                     &mod->num_gpl_syms);
        mod->gpl_crcs = section_addr(info, "__kcrctab_gpl");

#ifdef CONFIG_CONSTRUCTORS
        mod->ctors = section_objs(info, ".ctors",
                                  sizeof(*mod->ctors), &mod->num_ctors);
        if (!mod->ctors)
                mod->ctors = section_objs(info, ".init_array",
                                sizeof(*mod->ctors), &mod->num_ctors);
        else if (find_sec(info, ".init_array")) {
                /*
                 * This shouldn't happen with same compiler and binutils
                 * building all parts of the module.
                 */
                pr_warn("%s: has both .ctors and .init_array.\n",
                       mod->name);
                return -EINVAL;
        }
#endif

        mod->noinstr_text_start = section_objs(info, ".noinstr.text", 1,
                                                &mod->noinstr_text_size);

#ifdef CONFIG_TRACEPOINTS
        mod->tracepoints_ptrs = section_objs(info, "__tracepoints_ptrs",
                                             sizeof(*mod->tracepoints_ptrs),
                                             &mod->num_tracepoints);
#endif
#ifdef CONFIG_TREE_SRCU
        mod->srcu_struct_ptrs = section_objs(info, "___srcu_struct_ptrs",
                                             sizeof(*mod->srcu_struct_ptrs),
                                             &mod->num_srcu_structs);
#endif
#ifdef CONFIG_BPF_EVENTS
        mod->bpf_raw_events = section_objs(info, "__bpf_raw_tp_map",
                                           sizeof(*mod->bpf_raw_events),
                                           &mod->num_bpf_raw_events);
#endif
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
        mod->btf_data = any_section_objs(info, ".BTF", 1, &mod->btf_data_size);
#endif
#ifdef CONFIG_JUMP_LABEL
        mod->jump_entries = section_objs(info, "__jump_table",
                                        sizeof(*mod->jump_entries),
                                        &mod->num_jump_entries);
#endif
#ifdef CONFIG_EVENT_TRACING
        mod->trace_events = section_objs(info, "_ftrace_events",
                                         sizeof(*mod->trace_events),
                                         &mod->num_trace_events);
        mod->trace_evals = section_objs(info, "_ftrace_eval_map",
                                        sizeof(*mod->trace_evals),
                                        &mod->num_trace_evals);
#endif
#ifdef CONFIG_TRACING
        mod->trace_bprintk_fmt_start = section_objs(info, "__trace_printk_fmt",
                                         sizeof(*mod->trace_bprintk_fmt_start),
                                         &mod->num_trace_bprintk_fmt);
#endif
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
        /* sechdrs[0].sh_size is always zero */
        mod->ftrace_callsites = section_objs(info, FTRACE_CALLSITE_SECTION,
                                             sizeof(*mod->ftrace_callsites),
                                             &mod->num_ftrace_callsites);
#endif
#ifdef CONFIG_FUNCTION_ERROR_INJECTION
        mod->ei_funcs = section_objs(info, "_error_injection_whitelist",
                                            sizeof(*mod->ei_funcs),
                                            &mod->num_ei_funcs);
#endif
#ifdef CONFIG_KPROBES
        mod->kprobes_text_start = section_objs(info, ".kprobes.text", 1,
                                                &mod->kprobes_text_size);
        mod->kprobe_blacklist = section_objs(info, "_kprobe_blacklist",
                                                sizeof(unsigned long),
                                                &mod->num_kprobe_blacklist);
#endif
#ifdef CONFIG_PRINTK_INDEX
        mod->printk_index_start = section_objs(info, ".printk_index",
                                               sizeof(*mod->printk_index_start),
                                               &mod->printk_index_size);
#endif
#ifdef CONFIG_HAVE_STATIC_CALL_INLINE
        mod->static_call_sites = section_objs(info, ".static_call_sites",
                                              sizeof(*mod->static_call_sites),
                                              &mod->num_static_call_sites);
#endif
#ifdef CONFIG_KUNIT
        mod->kunit_suites = section_objs(info, ".kunit_test_suites",
                                              sizeof(*mod->kunit_suites),
                                              &mod->num_kunit_suites);
#endif

        mod->extable = section_objs(info, "__ex_table",
                                    sizeof(*mod->extable), &mod->num_exentries);

        if (section_addr(info, "__obsparm"))
                pr_warn("%s: Ignoring obsolete parameters\n", mod->name);

        info->debug = section_objs(info, "__dyndbg",
                                   sizeof(*info->debug), &info->num_debug);

        return 0;
}

static int move_module(struct module *mod, struct load_info *info)
{
        int i;
        void *ptr;

        /* Do the allocs. */
        ptr = module_alloc(mod->core_layout.size);
        /*
         * The pointer to this block is stored in the module structure
         * which is inside the block. Just mark it as not being a
         * leak.
         */
        kmemleak_not_leak(ptr);
        if (!ptr)
                return -ENOMEM;

        memset(ptr, 0, mod->core_layout.size);
        mod->core_layout.base = ptr;

        if (mod->init_layout.size) {
                ptr = module_alloc(mod->init_layout.size);
                /*
                 * The pointer to this block is stored in the module structure
                 * which is inside the block. This block doesn't need to be
                 * scanned as it contains data and code that will be freed
                 * after the module is initialized.
                 */
                kmemleak_ignore(ptr);
                if (!ptr) {
                        module_memfree(mod->core_layout.base);
                        return -ENOMEM;
                }
                memset(ptr, 0, mod->init_layout.size);
                mod->init_layout.base = ptr;
        } else
                mod->init_layout.base = NULL;

#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
        /* Do the allocs. */
        ptr = vzalloc(mod->data_layout.size);
        /*
         * The pointer to this block is stored in the module structure
         * which is inside the block. Just mark it as not being a
         * leak.
         */
        kmemleak_not_leak(ptr);
        if (!ptr) {
                module_memfree(mod->core_layout.base);
                module_memfree(mod->init_layout.base);
                return -ENOMEM;
        }

        mod->data_layout.base = ptr;
#endif
        /* Transfer each section which specifies SHF_ALLOC */
        pr_debug("final section addresses:\n");
        for (i = 0; i < info->hdr->e_shnum; i++) {
                void *dest;
                Elf_Shdr *shdr = &info->sechdrs[i];

                if (!(shdr->sh_flags & SHF_ALLOC))
                        continue;

                if (shdr->sh_entsize & INIT_OFFSET_MASK)
                        dest = mod->init_layout.base
                                + (shdr->sh_entsize & ~INIT_OFFSET_MASK);
                else if (!(shdr->sh_flags & SHF_EXECINSTR))
                        dest = mod->data_layout.base + shdr->sh_entsize;
                else
                        dest = mod->core_layout.base + shdr->sh_entsize;

                if (shdr->sh_type != SHT_NOBITS)
                        memcpy(dest, (void *)shdr->sh_addr, shdr->sh_size);
                /* Update sh_addr to point to copy in image. */
                shdr->sh_addr = (unsigned long)dest;
                pr_debug("\t0x%lx %s\n",
                         (long)shdr->sh_addr, info->secstrings + shdr->sh_name);
        }

        return 0;
}

static int check_module_license_and_versions(struct module *mod)
{
        int prev_taint = test_taint(TAINT_PROPRIETARY_MODULE);

        /*
         * ndiswrapper is under GPL by itself, but loads proprietary modules.
         * Don't use add_taint_module(), as it would prevent ndiswrapper from
         * using GPL-only symbols it needs.
         */
        if (strcmp(mod->name, "ndiswrapper") == 0)
                add_taint(TAINT_PROPRIETARY_MODULE, LOCKDEP_NOW_UNRELIABLE);

        /* driverloader was caught wrongly pretending to be under GPL */
        if (strcmp(mod->name, "driverloader") == 0)
                add_taint_module(mod, TAINT_PROPRIETARY_MODULE,
                                 LOCKDEP_NOW_UNRELIABLE);

        /* lve claims to be GPL but upstream won't provide source */
        if (strcmp(mod->name, "lve") == 0)
                add_taint_module(mod, TAINT_PROPRIETARY_MODULE,
                                 LOCKDEP_NOW_UNRELIABLE);

        if (!prev_taint && test_taint(TAINT_PROPRIETARY_MODULE))
                pr_warn("%s: module license taints kernel.\n", mod->name);

#ifdef CONFIG_MODVERSIONS
        if ((mod->num_syms && !mod->crcs) ||
            (mod->num_gpl_syms && !mod->gpl_crcs)) {
                return try_to_force_load(mod,
                                         "no versions for exported symbols");
        }
#endif
        return 0;
}

static void flush_module_icache(const struct module *mod)
{
        /*
         * Flush the instruction cache, since we've played with text.
         * Do it before processing of module parameters, so the module
         * can provide parameter accessor functions of its own.
         */
        if (mod->init_layout.base)
                flush_icache_range((unsigned long)mod->init_layout.base,
                                   (unsigned long)mod->init_layout.base
                                   + mod->init_layout.size);
        flush_icache_range((unsigned long)mod->core_layout.base,
                           (unsigned long)mod->core_layout.base + mod->core_layout.size);
}

int __weak module_frob_arch_sections(Elf_Ehdr *hdr,
                                     Elf_Shdr *sechdrs,
                                     char *secstrings,
                                     struct module *mod)
{
        return 0;
}

/* module_blacklist is a comma-separated list of module names */
static char *module_blacklist;
static bool blacklisted(const char *module_name)
{
        const char *p;
        size_t len;

        if (!module_blacklist)
                return false;

        for (p = module_blacklist; *p; p += len) {
                len = strcspn(p, ",");
                if (strlen(module_name) == len && !memcmp(module_name, p, len))
                        return true;
                if (p[len] == ',')
                        len++;
        }
        return false;
}
core_param(module_blacklist, module_blacklist, charp, 0400);

static struct module *layout_and_allocate(struct load_info *info, int flags)
{
        struct module *mod;
        unsigned int ndx;
        int err;

        err = check_modinfo(info->mod, info, flags);
        if (err)
                return ERR_PTR(err);

        /* Allow arches to frob section contents and sizes.  */
        err = module_frob_arch_sections(info->hdr, info->sechdrs,
                                        info->secstrings, info->mod);
        if (err < 0)
                return ERR_PTR(err);

        err = module_enforce_rwx_sections(info->hdr, info->sechdrs,
                                          info->secstrings, info->mod);
        if (err < 0)
                return ERR_PTR(err);

        /* We will do a special allocation for per-cpu sections later. */
        info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;

        /*
         * Mark ro_after_init section with SHF_RO_AFTER_INIT so that
         * layout_sections() can put it in the right place.
         * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set.
         */
        ndx = find_sec(info, ".data..ro_after_init");
        if (ndx)
                info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT;
        /*
         * Mark the __jump_table section as ro_after_init as well: these data
         * structures are never modified, with the exception of entries that
         * refer to code in the __init section, which are annotated as such
         * at module load time.
         */
        ndx = find_sec(info, "__jump_table");
        if (ndx)
                info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT;

        /*
         * Determine total sizes, and put offsets in sh_entsize.  For now
         * this is done generically; there doesn't appear to be any
         * special cases for the architectures.
         */
        layout_sections(info->mod, info);
        layout_symtab(info->mod, info);

        /* Allocate and move to the final place */
        err = move_module(info->mod, info);
        if (err)
                return ERR_PTR(err);

        /* Module has been copied to its final place now: return it. */
        mod = (void *)info->sechdrs[info->index.mod].sh_addr;
        kmemleak_load_module(mod, info);
        return mod;
}

/* mod is no longer valid after this! */
static void module_deallocate(struct module *mod, struct load_info *info)
{
        percpu_modfree(mod);
        module_arch_freeing_init(mod);
        module_memfree(mod->init_layout.base);
        module_memfree(mod->core_layout.base);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
        vfree(mod->data_layout.base);
#endif
}

int __weak module_finalize(const Elf_Ehdr *hdr,
                           const Elf_Shdr *sechdrs,
                           struct module *me)
{
        return 0;
}

static int post_relocation(struct module *mod, const struct load_info *info)
{
        /* Sort exception table now relocations are done. */
        sort_extable(mod->extable, mod->extable + mod->num_exentries);

        /* Copy relocated percpu area over. */
        percpu_modcopy(mod, (void *)info->sechdrs[info->index.pcpu].sh_addr,
                       info->sechdrs[info->index.pcpu].sh_size);

        /* Setup kallsyms-specific fields. */
        add_kallsyms(mod, info);

        /* Arch-specific module finalizing. */
        return module_finalize(info->hdr, info->sechdrs, mod);
}

/* Is this module of this name done loading?  No locks held. */
static bool finished_loading(const char *name)
{
        struct module *mod;
        bool ret;

        /*
         * The module_mutex should not be a heavily contended lock;
         * if we get the occasional sleep here, we'll go an extra iteration
         * in the wait_event_interruptible(), which is harmless.
         */
        sched_annotate_sleep();
        mutex_lock(&module_mutex);
        mod = find_module_all(name, strlen(name), true);
        ret = !mod || mod->state == MODULE_STATE_LIVE;
        mutex_unlock(&module_mutex);

        return ret;
}

/* Call module constructors. */
static void do_mod_ctors(struct module *mod)
{
#ifdef CONFIG_CONSTRUCTORS
        unsigned long i;

        for (i = 0; i < mod->num_ctors; i++)
                mod->ctors[i]();
#endif
}

/* For freeing module_init on success, in case kallsyms traversing */
struct mod_initfree {
        struct llist_node node;
        void *module_init;
};

static void do_free_init(struct work_struct *w)
{
        struct llist_node *pos, *n, *list;
        struct mod_initfree *initfree;

        list = llist_del_all(&init_free_list);

        synchronize_rcu();

        llist_for_each_safe(pos, n, list) {
                initfree = container_of(pos, struct mod_initfree, node);
                module_memfree(initfree->module_init);
                kfree(initfree);
        }
}

#undef MODULE_PARAM_PREFIX
#define MODULE_PARAM_PREFIX "module."
/* Default value for module->async_probe_requested */
static bool async_probe;
module_param(async_probe, bool, 0644);

/*
 * This is where the real work happens.
 *
 * Keep it uninlined to provide a reliable breakpoint target, e.g. for the gdb
 * helper command 'lx-symbols'.
 */
static noinline int do_init_module(struct module *mod)
{
        int ret = 0;
        struct mod_initfree *freeinit;

        freeinit = kmalloc(sizeof(*freeinit), GFP_KERNEL);
        if (!freeinit) {
                ret = -ENOMEM;
                goto fail;
        }
        freeinit->module_init = mod->init_layout.base;

        do_mod_ctors(mod);
        /* Start the module */
        if (mod->init != NULL)
                ret = do_one_initcall(mod->init);
        if (ret < 0) {
                goto fail_free_freeinit;
        }
        if (ret > 0) {
                pr_warn("%s: '%s'->init suspiciously returned %d, it should "
                        "follow 0/-E convention\n"
                        "%s: loading module anyway...\n",
                        __func__, mod->name, ret, __func__);
                dump_stack();
        }

        /* Now it's a first class citizen! */
        mod->state = MODULE_STATE_LIVE;
        blocking_notifier_call_chain(&module_notify_list,
                                     MODULE_STATE_LIVE, mod);

        /* Delay uevent until module has finished its init routine */
        kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD);

        /*
         * We need to finish all async code before the module init sequence
         * is done. This has potential to deadlock if synchronous module
         * loading is requested from async (which is not allowed!).
         *
         * See commit 0fdff3ec6d87 ("async, kmod: warn on synchronous
         * request_module() from async workers") for more details.
         */
        if (!mod->async_probe_requested)
                async_synchronize_full();

        ftrace_free_mem(mod, mod->init_layout.base, mod->init_layout.base +
                        mod->init_layout.size);
        mutex_lock(&module_mutex);
        /* Drop initial reference. */
        module_put(mod);
        trim_init_extable(mod);
#ifdef CONFIG_KALLSYMS
        /* Switch to core kallsyms now init is done: kallsyms may be walking! */
        rcu_assign_pointer(mod->kallsyms, &mod->core_kallsyms);
#endif
        module_enable_ro(mod, true);
        mod_tree_remove_init(mod);
        module_arch_freeing_init(mod);
        mod->init_layout.base = NULL;
        mod->init_layout.size = 0;
        mod->init_layout.ro_size = 0;
        mod->init_layout.ro_after_init_size = 0;
        mod->init_layout.text_size = 0;
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
        /* .BTF is not SHF_ALLOC and will get removed, so sanitize pointer */
        mod->btf_data = NULL;
#endif
        /*
         * We want to free module_init, but be aware that kallsyms may be
         * walking this with preempt disabled.  In all the failure paths, we
         * call synchronize_rcu(), but we don't want to slow down the success
         * path. module_memfree() cannot be called in an interrupt, so do the
         * work and call synchronize_rcu() in a work queue.
         *
         * Note that module_alloc() on most architectures creates W+X page
         * mappings which won't be cleaned up until do_free_init() runs.  Any
         * code such as mark_rodata_ro() which depends on those mappings to
         * be cleaned up needs to sync with the queued work - ie
         * rcu_barrier()
         */
        if (llist_add(&freeinit->node, &init_free_list))
                schedule_work(&init_free_wq);

        mutex_unlock(&module_mutex);
        wake_up_all(&module_wq);

        return 0;

fail_free_freeinit:
        kfree(freeinit);
fail:
        /* Try to protect us from buggy refcounters. */
        mod->state = MODULE_STATE_GOING;
        synchronize_rcu();
        module_put(mod);
        blocking_notifier_call_chain(&module_notify_list,
                                     MODULE_STATE_GOING, mod);
        klp_module_going(mod);
        ftrace_release_mod(mod);
        free_module(mod);
        wake_up_all(&module_wq);
        return ret;
}

static int may_init_module(void)
{
        if (!capable(CAP_SYS_MODULE) || modules_disabled)
                return -EPERM;

        return 0;
}

/*
 * We try to place it in the list now to make sure it's unique before
 * we dedicate too many resources.  In particular, temporary percpu
 * memory exhaustion.
 */
static int add_unformed_module(struct module *mod)
{
        int err;
        struct module *old;

        mod->state = MODULE_STATE_UNFORMED;

again:
        mutex_lock(&module_mutex);
        old = find_module_all(mod->name, strlen(mod->name), true);
        if (old != NULL) {
                if (old->state != MODULE_STATE_LIVE) {
                        /* Wait in case it fails to load. */
                        mutex_unlock(&module_mutex);
                        err = wait_event_interruptible(module_wq,
                                               finished_loading(mod->name));
                        if (err)
                                goto out_unlocked;
                        goto again;
                }
                err = -EEXIST;
                goto out;
        }
        mod_update_bounds(mod);
        list_add_rcu(&mod->list, &modules);
        mod_tree_insert(mod);
        err = 0;

out:
        mutex_unlock(&module_mutex);
out_unlocked:
        return err;
}

static int complete_formation(struct module *mod, struct load_info *info)
{
        int err;

        mutex_lock(&module_mutex);

        /* Find duplicate symbols (must be called under lock). */
        err = verify_exported_symbols(mod);
        if (err < 0)
                goto out;

        /* This relies on module_mutex for list integrity. */
        module_bug_finalize(info->hdr, info->sechdrs, mod);

        if (module_check_misalignment(mod))
                goto out_misaligned;

        module_enable_ro(mod, false);
        module_enable_nx(mod);
        module_enable_x(mod);

        /*
         * Mark state as coming so strong_try_module_get() ignores us,
         * but kallsyms etc. can see us.
         */
        mod->state = MODULE_STATE_COMING;
        mutex_unlock(&module_mutex);

        return 0;

out_misaligned:
        err = -EINVAL;
out:
        mutex_unlock(&module_mutex);
        return err;
}

static int prepare_coming_module(struct module *mod)
{
        int err;

        ftrace_module_enable(mod);
        err = klp_module_coming(mod);
        if (err)
                return err;

        err = blocking_notifier_call_chain_robust(&module_notify_list,
                        MODULE_STATE_COMING, MODULE_STATE_GOING, mod);
        err = notifier_to_errno(err);
        if (err)
                klp_module_going(mod);

        return err;
}

static int unknown_module_param_cb(char *param, char *val, const char *modname,
                                   void *arg)
{
        struct module *mod = arg;
        int ret;

        if (strcmp(param, "async_probe") == 0) {
                if (strtobool(val, &mod->async_probe_requested))
                        mod->async_probe_requested = true;
                return 0;
        }

        /* Check for magic 'dyndbg' arg */
        ret = ddebug_dyndbg_module_param_cb(param, val, modname);
        if (ret != 0)
                pr_warn("%s: unknown parameter '%s' ignored\n", modname, param);
        return 0;
}

static void cfi_init(struct module *mod);

/*
 * Allocate and load the module: note that size of section 0 is always
 * zero, and we rely on this for optional sections.
 */
static int load_module(struct load_info *info, const char __user *uargs,
                       int flags)
{
        struct module *mod;
        long err = 0;
        char *after_dashes;

        /*
         * Do the signature check (if any) first. All that
         * the signature check needs is info->len, it does
         * not need any of the section info. That can be
         * set up later. This will minimize the chances
         * of a corrupt module causing problems before
         * we even get to the signature check.
         *
         * The check will also adjust info->len by stripping
         * off the sig length at the end of the module, making
         * checks against info->len more correct.
         */
        err = module_sig_check(info, flags);
        if (err)
                goto free_copy;

        /*
         * Do basic sanity checks against the ELF header and
         * sections.
         */
        err = elf_validity_check(info);
        if (err)
                goto free_copy;

        /*
         * Everything checks out, so set up the section info
         * in the info structure.
         */
        err = setup_load_info(info, flags);
        if (err)
                goto free_copy;

        /*
         * Now that we know we have the correct module name, check
         * if it's blacklisted.
         */
        if (blacklisted(info->name)) {
                err = -EPERM;
                pr_err("Module %s is blacklisted\n", info->name);
                goto free_copy;
        }

        err = rewrite_section_headers(info, flags);
        if (err)
                goto free_copy;

        /* Check module struct version now, before we try to use module. */
        if (!check_modstruct_version(info, info->mod)) {
                err = -ENOEXEC;
                goto free_copy;
        }

        /* Figure out module layout, and allocate all the memory. */
        mod = layout_and_allocate(info, flags);
        if (IS_ERR(mod)) {
                err = PTR_ERR(mod);
                goto free_copy;
        }

        audit_log_kern_module(mod->name);

        /* Reserve our place in the list. */
        err = add_unformed_module(mod);
        if (err)
                goto free_module;

#ifdef CONFIG_MODULE_SIG
        mod->sig_ok = info->sig_ok;
        if (!mod->sig_ok) {
                pr_notice_once("%s: module verification failed: signature "
                               "and/or required key missing - tainting "
                               "kernel\n", mod->name);
                add_taint_module(mod, TAINT_UNSIGNED_MODULE, LOCKDEP_STILL_OK);
        }
#endif

        /* To avoid stressing percpu allocator, do this once we're unique. */
        err = percpu_modalloc(mod, info);
        if (err)
                goto unlink_mod;

        /* Now module is in final location, initialize linked lists, etc. */
        err = module_unload_init(mod);
        if (err)
                goto unlink_mod;

        init_param_lock(mod);

        /*
         * Now we've got everything in the final locations, we can
         * find optional sections.
         */
        err = find_module_sections(mod, info);
        if (err)
                goto free_unload;

        err = check_module_license_and_versions(mod);
        if (err)
                goto free_unload;

        /* Set up MODINFO_ATTR fields */
        setup_modinfo(mod, info);

        /* Fix up syms, so that st_value is a pointer to location. */
        err = simplify_symbols(mod, info);
        if (err < 0)
                goto free_modinfo;

        err = apply_relocations(mod, info);
        if (err < 0)
                goto free_modinfo;

        err = post_relocation(mod, info);
        if (err < 0)
                goto free_modinfo;

        flush_module_icache(mod);

        /* Setup CFI for the module. */
        cfi_init(mod);

        /* Now copy in args */
        mod->args = strndup_user(uargs, ~0UL >> 1);
        if (IS_ERR(mod->args)) {
                err = PTR_ERR(mod->args);
                goto free_arch_cleanup;
        }

        init_build_id(mod, info);
        dynamic_debug_setup(mod, info->debug, info->num_debug);

        /* Ftrace init must be called in the MODULE_STATE_UNFORMED state */
        ftrace_module_init(mod);

        /* Finally it's fully formed, ready to start executing. */
        err = complete_formation(mod, info);
        if (err)
                goto ddebug_cleanup;

        err = prepare_coming_module(mod);
        if (err)
                goto bug_cleanup;

        mod->async_probe_requested = async_probe;

        /* Module is ready to execute: parsing args may do that. */
        after_dashes = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
                                  -32768, 32767, mod,
                                  unknown_module_param_cb);
        if (IS_ERR(after_dashes)) {
                err = PTR_ERR(after_dashes);
                goto coming_cleanup;
        } else if (after_dashes) {
                pr_warn("%s: parameters '%s' after `--' ignored\n",
                       mod->name, after_dashes);
        }

        /* Link in to sysfs. */
        err = mod_sysfs_setup(mod, info, mod->kp, mod->num_kp);
        if (err < 0)
                goto coming_cleanup;

        if (is_livepatch_module(mod)) {
                err = copy_module_elf(mod, info);
                if (err < 0)
                        goto sysfs_cleanup;
        }

        /* Get rid of temporary copy. */
        free_copy(info, flags);

        /* Done! */
        trace_module_load(mod);

        return do_init_module(mod);

 sysfs_cleanup:
        mod_sysfs_teardown(mod);
 coming_cleanup:
        mod->state = MODULE_STATE_GOING;
        destroy_params(mod->kp, mod->num_kp);
        blocking_notifier_call_chain(&module_notify_list,
                                     MODULE_STATE_GOING, mod);
        klp_module_going(mod);
 bug_cleanup:
        mod->state = MODULE_STATE_GOING;
        /* module_bug_cleanup needs module_mutex protection */
        mutex_lock(&module_mutex);
        module_bug_cleanup(mod);
        mutex_unlock(&module_mutex);

 ddebug_cleanup:
        ftrace_release_mod(mod);
        dynamic_debug_remove(mod, info->debug);
        synchronize_rcu();
        kfree(mod->args);
 free_arch_cleanup:
        cfi_cleanup(mod);
        module_arch_cleanup(mod);
 free_modinfo:
        free_modinfo(mod);
 free_unload:
        module_unload_free(mod);
 unlink_mod:
        mutex_lock(&module_mutex);
        /* Unlink carefully: kallsyms could be walking list. */
        list_del_rcu(&mod->list);
        mod_tree_remove(mod);
        wake_up_all(&module_wq);
        /* Wait for RCU-sched synchronizing before releasing mod->list. */
        synchronize_rcu();
        mutex_unlock(&module_mutex);
 free_module:
        /* Free lock-classes; relies on the preceding sync_rcu() */
        lockdep_free_key_range(mod->data_layout.base, mod->data_layout.size);

        module_deallocate(mod, info);
 free_copy:
        free_copy(info, flags);
        return err;
}

SYSCALL_DEFINE3(init_module, void __user *, umod,
                unsigned long, len, const char __user *, uargs)
{
        int err;
        struct load_info info = { };

        err = may_init_module();
        if (err)
                return err;

        pr_debug("init_module: umod=%p, len=%lu, uargs=%p\n",
               umod, len, uargs);

        err = copy_module_from_user(umod, len, &info);
        if (err)
                return err;

        return load_module(&info, uargs, 0);
}

SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
{
        struct load_info info = { };
        void *buf = NULL;
        int len;
        int err;

        err = may_init_module();
        if (err)
                return err;

        pr_debug("finit_module: fd=%d, uargs=%p, flags=%i\n", fd, uargs, flags);

        if (flags & ~(MODULE_INIT_IGNORE_MODVERSIONS
                      |MODULE_INIT_IGNORE_VERMAGIC
                      |MODULE_INIT_COMPRESSED_FILE))
                return -EINVAL;

        len = kernel_read_file_from_fd(fd, 0, &buf, INT_MAX, NULL,
                                       READING_MODULE);
        if (len < 0)
                return len;

        if (flags & MODULE_INIT_COMPRESSED_FILE) {
                err = module_decompress(&info, buf, len);
                vfree(buf); /* compressed data is no longer needed */
                if (err)
                        return err;
        } else {
                info.hdr = buf;
                info.len = len;
        }

        return load_module(&info, uargs, flags);
}

static inline int within(unsigned long addr, void *start, unsigned long size)
{
        return ((void *)addr >= start && (void *)addr < start + size);
}

static void cfi_init(struct module *mod)
{
#ifdef CONFIG_CFI_CLANG
        initcall_t *init;
#ifdef CONFIG_MODULE_UNLOAD
        exitcall_t *exit;
#endif

        rcu_read_lock_sched();
        mod->cfi_check = (cfi_check_fn)
                find_kallsyms_symbol_value(mod, "__cfi_check");
        init = (initcall_t *)
                find_kallsyms_symbol_value(mod, "__cfi_jt_init_module");
        /* Fix init/exit functions to point to the CFI jump table */
        if (init)
                mod->init = *init;
#ifdef CONFIG_MODULE_UNLOAD
        exit = (exitcall_t *)
                find_kallsyms_symbol_value(mod, "__cfi_jt_cleanup_module");
        if (exit)
                mod->exit = *exit;
#endif
        rcu_read_unlock_sched();

        cfi_module_add(mod, mod_tree.addr_min);
#endif
}

static void cfi_cleanup(struct module *mod)
{
#ifdef CONFIG_CFI_CLANG
        cfi_module_remove(mod, mod_tree.addr_min);
#endif
}

/* Keep in sync with MODULE_FLAGS_BUF_SIZE !!! */
char *module_flags(struct module *mod, char *buf, bool show_state)
{
        int bx = 0;

        BUG_ON(mod->state == MODULE_STATE_UNFORMED);
        if (!mod->taints && !show_state)
                goto out;
        if (mod->taints ||
            mod->state == MODULE_STATE_GOING ||
            mod->state == MODULE_STATE_COMING) {
                buf[bx++] = '(';
                bx += module_flags_taint(mod->taints, buf + bx);
                /* Show a - for module-is-being-unloaded */
                if (mod->state == MODULE_STATE_GOING && show_state)
                        buf[bx++] = '-';
                /* Show a + for module-is-being-loaded */
                if (mod->state == MODULE_STATE_COMING && show_state)
                        buf[bx++] = '+';
                buf[bx++] = ')';
        }
out:
        buf[bx] = '\0';

        return buf;
}

/* Given an address, look for it in the module exception tables. */
const struct exception_table_entry *search_module_extables(unsigned long addr)
{
        const struct exception_table_entry *e = NULL;
        struct module *mod;

        preempt_disable();
        mod = __module_address(addr);
        if (!mod)
                goto out;

        if (!mod->num_exentries)
                goto out;

        e = search_extable(mod->extable,
                           mod->num_exentries,
                           addr);
out:
        preempt_enable();

        /*
         * Now, if we found one, we are running inside it now, hence
         * we cannot unload the module, hence no refcnt needed.
         */
        return e;
}

/**
 * is_module_address() - is this address inside a module?
 * @addr: the address to check.
 *
 * See is_module_text_address() if you simply want to see if the address
 * is code (not data).
 */
bool is_module_address(unsigned long addr)
{
        bool ret;

        preempt_disable();
        ret = __module_address(addr) != NULL;
        preempt_enable();

        return ret;
}

/**
 * __module_address() - get the module which contains an address.
 * @addr: the address.
 *
 * Must be called with preempt disabled or module mutex held so that
 * module doesn't get freed during this.
 */
struct module *__module_address(unsigned long addr)
{
        struct module *mod;
        struct mod_tree_root *tree;

        if (addr >= mod_tree.addr_min && addr <= mod_tree.addr_max)
                tree = &mod_tree;
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
        else if (addr >= mod_data_tree.addr_min && addr <= mod_data_tree.addr_max)
                tree = &mod_data_tree;
#endif
        else
                return NULL;

        module_assert_mutex_or_preempt();

        mod = mod_find(addr, tree);
        if (mod) {
                BUG_ON(!within_module(addr, mod));
                if (mod->state == MODULE_STATE_UNFORMED)
                        mod = NULL;
        }
        return mod;
}

/**
 * is_module_text_address() - is this address inside module code?
 * @addr: the address to check.
 *
 * See is_module_address() if you simply want to see if the address is
 * anywhere in a module.  See kernel_text_address() for testing if an
 * address corresponds to kernel or module code.
 */
bool is_module_text_address(unsigned long addr)
{
        bool ret;

        preempt_disable();
        ret = __module_text_address(addr) != NULL;
        preempt_enable();

        return ret;
}

/**
 * __module_text_address() - get the module whose code contains an address.
 * @addr: the address.
 *
 * Must be called with preempt disabled or module mutex held so that
 * module doesn't get freed during this.
 */
struct module *__module_text_address(unsigned long addr)
{
        struct module *mod = __module_address(addr);
        if (mod) {
                /* Make sure it's within the text section. */
                if (!within(addr, mod->init_layout.base, mod->init_layout.text_size)
                    && !within(addr, mod->core_layout.base, mod->core_layout.text_size))
                        mod = NULL;
        }
        return mod;
}

/* Don't grab lock, we're oopsing. */
void print_modules(void)
{
        struct module *mod;
        char buf[MODULE_FLAGS_BUF_SIZE];

        printk(KERN_DEFAULT "Modules linked in:");
        /* Most callers should already have preempt disabled, but make sure */
        preempt_disable();
        list_for_each_entry_rcu(mod, &modules, list) {
                if (mod->state == MODULE_STATE_UNFORMED)
                        continue;
                pr_cont(" %s%s", mod->name, module_flags(mod, buf, true));
        }

        print_unloaded_tainted_modules();
        preempt_enable();
        if (last_unloaded_module.name[0])
                pr_cont(" [last unloaded: %s%s]", last_unloaded_module.name,
                        last_unloaded_module.taints);
        pr_cont("\n");
}