userns: prevent speculative execution

[mirror_ubuntu-artful-kernel.git] / kernel / module.c

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

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include <linux/export.h>
#include <linux/extable.h>
#include <linux/moduleloader.h>
#include <linux/trace_events.h>
#include <linux/init.h>
#include <linux/kallsyms.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/elf.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/fcntl.h>
#include <linux/rcupdate.h>
#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/moduleparam.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/vermagic.h>
#include <linux/notifier.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/string.h>
#include <linux/mutex.h>
#include <linux/rculist.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <linux/set_memory.h>
#include <asm/mmu_context.h>
#include <linux/license.h>
#include <asm/sections.h>
#include <linux/tracepoint.h>
#include <linux/ftrace.h>
#include <linux/livepatch.h>
#include <linux/async.h>
#include <linux/percpu.h>
#include <linux/kmemleak.h>
#include <linux/jump_label.h>
#include <linux/pfn.h>
#include <linux/bsearch.h>
#include <linux/dynamic_debug.h>
#include <linux/audit.h>
#include <uapi/linux/module.h>
#include "module-internal.h"

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

#ifndef ARCH_SHF_SMALL
#define ARCH_SHF_SMALL 0
#endif

/*
 * Modules' sections will be aligned on page boundaries
 * to ensure complete separation of code and data, but
 * only when CONFIG_STRICT_MODULE_RWX=y
 */
#ifdef CONFIG_STRICT_MODULE_RWX
# define debug_align(X) ALIGN(X, PAGE_SIZE)
#else
# define debug_align(X) (X)
#endif

/* If this is set, the section belongs in the init part of the module */
#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))

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

#ifdef CONFIG_MODULES_TREE_LOOKUP

/*
 * Use a latched RB-tree for __module_address(); this allows us to use
 * RCU-sched lookups of the address from any context.
 *
 * This is conditional on PERF_EVENTS || TRACING because those can really hit
 * __module_address() hard by doing a lot of stack unwinding; potentially from
 * NMI context.
 */

static __always_inline unsigned long __mod_tree_val(struct latch_tree_node *n)
{
        struct module_layout *layout = container_of(n, struct module_layout, mtn.node);

        return (unsigned long)layout->base;
}

static __always_inline unsigned long __mod_tree_size(struct latch_tree_node *n)
{
        struct module_layout *layout = container_of(n, struct module_layout, mtn.node);

        return (unsigned long)layout->size;
}

static __always_inline bool
mod_tree_less(struct latch_tree_node *a, struct latch_tree_node *b)
{
        return __mod_tree_val(a) < __mod_tree_val(b);
}

static __always_inline int
mod_tree_comp(void *key, struct latch_tree_node *n)
{
        unsigned long val = (unsigned long)key;
        unsigned long start, end;

        start = __mod_tree_val(n);
        if (val < start)
                return -1;

        end = start + __mod_tree_size(n);
        if (val >= end)
                return 1;

        return 0;
}

static const struct latch_tree_ops mod_tree_ops = {
        .less = mod_tree_less,
        .comp = mod_tree_comp,
};

static struct mod_tree_root {
        struct latch_tree_root root;
        unsigned long addr_min;
        unsigned long addr_max;
} mod_tree __cacheline_aligned = {
        .addr_min = -1UL,
};

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

static noinline void __mod_tree_insert(struct mod_tree_node *node)
{
        latch_tree_insert(&node->node, &mod_tree.root, &mod_tree_ops);
}

static void __mod_tree_remove(struct mod_tree_node *node)
{
        latch_tree_erase(&node->node, &mod_tree.root, &mod_tree_ops);
}

/*
 * These modifications: insert, remove_init and remove; are serialized by the
 * module_mutex.
 */
static void mod_tree_insert(struct module *mod)
{
        mod->core_layout.mtn.mod = mod;
        mod->init_layout.mtn.mod = mod;

        __mod_tree_insert(&mod->core_layout.mtn);
        if (mod->init_layout.size)
                __mod_tree_insert(&mod->init_layout.mtn);
}

static void mod_tree_remove_init(struct module *mod)
{
        if (mod->init_layout.size)
                __mod_tree_remove(&mod->init_layout.mtn);
}

static void mod_tree_remove(struct module *mod)
{
        __mod_tree_remove(&mod->core_layout.mtn);
        mod_tree_remove_init(mod);
}

static struct module *mod_find(unsigned long addr)
{
        struct latch_tree_node *ltn;

        ltn = latch_tree_find((void *)addr, &mod_tree.root, &mod_tree_ops);
        if (!ltn)
                return NULL;

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

#else /* MODULES_TREE_LOOKUP */

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

static void mod_tree_insert(struct module *mod) { }
static void mod_tree_remove_init(struct module *mod) { }
static void mod_tree_remove(struct module *mod) { }

static struct module *mod_find(unsigned long addr)
{
        struct module *mod;

        list_for_each_entry_rcu(mod, &modules, list) {
                if (within_module(addr, mod))
                        return mod;
        }

        return NULL;
}

#endif /* MODULES_TREE_LOOKUP */

/*
 * Bounds of module text, for speeding up __module_address.
 * Protected by module_mutex.
 */
static void __mod_update_bounds(void *base, unsigned int size)
{
        unsigned long min = (unsigned long)base;
        unsigned long max = min + size;

        if (min < module_addr_min)
                module_addr_min = min;
        if (max > module_addr_max)
                module_addr_max = max;
}

static void mod_update_bounds(struct module *mod)
{
        __mod_update_bounds(mod->core_layout.base, mod->core_layout.size);
        if (mod->init_layout.size)
                __mod_update_bounds(mod->init_layout.base, mod->init_layout.size);
}

#ifdef CONFIG_KGDB_KDB
struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */
#endif /* CONFIG_KGDB_KDB */

static void module_assert_mutex(void)
{
        lockdep_assert_held(&module_mutex);
}

static void module_assert_mutex_or_preempt(void)
{
#ifdef CONFIG_LOCKDEP
        if (unlikely(!debug_locks))
                return;

        WARN_ON_ONCE(!rcu_read_lock_sched_held() &&
                !lockdep_is_held(&module_mutex));
#endif
}

static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
#ifndef CONFIG_MODULE_SIG_FORCE
module_param(sig_enforce, bool_enable_only, 0644);
#endif /* !CONFIG_MODULE_SIG_FORCE */

/* Block module loading/unloading? */
int modules_disabled = 0;
core_param(nomodule, modules_disabled, bint, 0);

/* Waiting for a module to finish initializing? */
static DECLARE_WAIT_QUEUE_HEAD(module_wq);

static BLOCKING_NOTIFIER_HEAD(module_notify_list);

int register_module_notifier(struct notifier_block *nb)
{
        return blocking_notifier_chain_register(&module_notify_list, nb);
}
EXPORT_SYMBOL(register_module_notifier);

int unregister_module_notifier(struct notifier_block *nb)
{
        return blocking_notifier_chain_unregister(&module_notify_list, nb);
}
EXPORT_SYMBOL(unregister_module_notifier);

struct load_info {
        const char *name;
        Elf_Ehdr *hdr;
        unsigned long len;
        Elf_Shdr *sechdrs;
        char *secstrings, *strtab;
        unsigned long symoffs, stroffs;
        struct _ddebug *debug;
        unsigned int num_debug;
        bool sig_ok;
#ifdef CONFIG_KALLSYMS
        unsigned long mod_kallsyms_init_off;
#endif
        struct {
                unsigned int sym, str, mod, vers, info, pcpu;
        } index;
};

/*
 * We require a truly strong try_module_get(): 0 means success.
 * Otherwise an error is returned due to ongoing or failed
 * initialization etc.
 */
static inline int strong_try_module_get(struct module *mod)
{
        BUG_ON(mod && mod->state == MODULE_STATE_UNFORMED);
        if (mod && mod->state == MODULE_STATE_COMING)
                return -EBUSY;
        if (try_module_get(mod))
                return 0;
        else
                return -ENOENT;
}

static inline void add_taint_module(struct module *mod, unsigned flag,
                                    enum lockdep_ok lockdep_ok)
{
        add_taint(flag, lockdep_ok);
        set_bit(flag, &mod->taints);
}

/*
 * A thread that wants to hold a reference to a module only while it
 * is running can call this to safely exit.  nfsd and lockd use this.
 */
void __noreturn __module_put_and_exit(struct module *mod, long code)
{
        module_put(mod);
        do_exit(code);
}
EXPORT_SYMBOL(__module_put_and_exit);

/* Find a module section: 0 means not found. */
static unsigned int find_sec(const struct load_info *info, const char *name)
{
        unsigned int i;

        for (i = 1; i < info->hdr->e_shnum; i++) {
                Elf_Shdr *shdr = &info->sechdrs[i];
                /* Alloc bit cleared means "ignore it." */
                if ((shdr->sh_flags & SHF_ALLOC)
                    && strcmp(info->secstrings + shdr->sh_name, name) == 0)
                        return i;
        }
        return 0;
}

/* Find a module section, or NULL. */
static void *section_addr(const struct load_info *info, const char *name)
{
        /* Section 0 has sh_addr 0. */
        return (void *)info->sechdrs[find_sec(info, name)].sh_addr;
}

/* Find a module section, or NULL.  Fill in number of "objects" in section. */
static void *section_objs(const struct load_info *info,
                          const char *name,
                          size_t object_size,
                          unsigned int *num)
{
        unsigned int sec = find_sec(info, name);

        /* Section 0 has sh_addr 0 and sh_size 0. */
        *num = info->sechdrs[sec].sh_size / object_size;
        return (void *)info->sechdrs[sec].sh_addr;
}

/* Provided by the linker */
extern const struct kernel_symbol __start___ksymtab[];
extern const struct kernel_symbol __stop___ksymtab[];
extern const struct kernel_symbol __start___ksymtab_gpl[];
extern const struct kernel_symbol __stop___ksymtab_gpl[];
extern const struct kernel_symbol __start___ksymtab_gpl_future[];
extern const struct kernel_symbol __stop___ksymtab_gpl_future[];
extern const s32 __start___kcrctab[];
extern const s32 __start___kcrctab_gpl[];
extern const s32 __start___kcrctab_gpl_future[];
#ifdef CONFIG_UNUSED_SYMBOLS
extern const struct kernel_symbol __start___ksymtab_unused[];
extern const struct kernel_symbol __stop___ksymtab_unused[];
extern const struct kernel_symbol __start___ksymtab_unused_gpl[];
extern const struct kernel_symbol __stop___ksymtab_unused_gpl[];
extern const s32 __start___kcrctab_unused[];
extern const s32 __start___kcrctab_unused_gpl[];
#endif

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

static bool each_symbol_in_section(const struct symsearch *arr,
                                   unsigned int arrsize,
                                   struct module *owner,
                                   bool (*fn)(const struct symsearch *syms,
                                              struct module *owner,
                                              void *data),
                                   void *data)
{
        unsigned int j;

        for (j = 0; j < arrsize; j++) {
                if (fn(&arr[j], owner, data))
                        return true;
        }

        return false;
}

/* Returns true as soon as fn returns true, otherwise false. */
bool each_symbol_section(bool (*fn)(const struct symsearch *arr,
                                    struct module *owner,
                                    void *data),
                         void *data)
{
        struct module *mod;
        static const struct symsearch arr[] = {
                { __start___ksymtab, __stop___ksymtab, __start___kcrctab,
                  NOT_GPL_ONLY, false },
                { __start___ksymtab_gpl, __stop___ksymtab_gpl,
                  __start___kcrctab_gpl,
                  GPL_ONLY, false },
                { __start___ksymtab_gpl_future, __stop___ksymtab_gpl_future,
                  __start___kcrctab_gpl_future,
                  WILL_BE_GPL_ONLY, false },
#ifdef CONFIG_UNUSED_SYMBOLS
                { __start___ksymtab_unused, __stop___ksymtab_unused,
                  __start___kcrctab_unused,
                  NOT_GPL_ONLY, true },
                { __start___ksymtab_unused_gpl, __stop___ksymtab_unused_gpl,
                  __start___kcrctab_unused_gpl,
                  GPL_ONLY, true },
#endif
        };

        module_assert_mutex_or_preempt();

        if (each_symbol_in_section(arr, ARRAY_SIZE(arr), NULL, fn, data))
                return true;

        list_for_each_entry_rcu(mod, &modules, list) {
                struct symsearch arr[] = {
                        { mod->syms, mod->syms + mod->num_syms, mod->crcs,
                          NOT_GPL_ONLY, false },
                        { mod->gpl_syms, mod->gpl_syms + mod->num_gpl_syms,
                          mod->gpl_crcs,
                          GPL_ONLY, false },
                        { mod->gpl_future_syms,
                          mod->gpl_future_syms + mod->num_gpl_future_syms,
                          mod->gpl_future_crcs,
                          WILL_BE_GPL_ONLY, false },
#ifdef CONFIG_UNUSED_SYMBOLS
                        { mod->unused_syms,
                          mod->unused_syms + mod->num_unused_syms,
                          mod->unused_crcs,
                          NOT_GPL_ONLY, true },
                        { mod->unused_gpl_syms,
                          mod->unused_gpl_syms + mod->num_unused_gpl_syms,
                          mod->unused_gpl_crcs,
                          GPL_ONLY, true },
#endif
                };

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

                if (each_symbol_in_section(arr, ARRAY_SIZE(arr), mod, fn, data))
                        return true;
        }
        return false;
}
EXPORT_SYMBOL_GPL(each_symbol_section);

struct find_symbol_arg {
        /* Input */
        const char *name;
        bool gplok;
        bool warn;

        /* Output */
        struct module *owner;
        const s32 *crc;
        const struct kernel_symbol *sym;
};

static bool check_symbol(const struct symsearch *syms,
                                 struct module *owner,
                                 unsigned int symnum, void *data)
{
        struct find_symbol_arg *fsa = data;

        if (!fsa->gplok) {
                if (syms->licence == GPL_ONLY)
                        return false;
                if (syms->licence == WILL_BE_GPL_ONLY && fsa->warn) {
                        pr_warn("Symbol %s is being used by a non-GPL module, "
                                "which will not be allowed in the future\n",
                                fsa->name);
                }
        }

#ifdef CONFIG_UNUSED_SYMBOLS
        if (syms->unused && fsa->warn) {
                pr_warn("Symbol %s is marked as UNUSED, however this module is "
                        "using it.\n", fsa->name);
                pr_warn("This symbol will go away in the future.\n");
                pr_warn("Please evaluate if this is the right api to use and "
                        "if it really is, submit a report to the linux kernel "
                        "mailing list together with submitting your code for "
                        "inclusion.\n");
        }
#endif

        fsa->owner = owner;
        fsa->crc = symversion(syms->crcs, symnum);
        fsa->sym = &syms->start[symnum];
        return true;
}

static int cmp_name(const void *va, const void *vb)
{
        const char *a;
        const struct kernel_symbol *b;
        a = va; b = vb;
        return strcmp(a, b->name);
}

static bool find_symbol_in_section(const struct symsearch *syms,
                                   struct module *owner,
                                   void *data)
{
        struct find_symbol_arg *fsa = data;
        struct kernel_symbol *sym;

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

        if (sym != NULL && check_symbol(syms, owner, sym - syms->start, data))
                return true;

        return false;
}

/* Find a symbol and return it, along with, (optional) crc and
 * (optional) module which owns it.  Needs preempt disabled or module_mutex. */
const struct kernel_symbol *find_symbol(const char *name,
                                        struct module **owner,
                                        const s32 **crc,
                                        bool gplok,
                                        bool warn)
{
        struct find_symbol_arg fsa;

        fsa.name = name;
        fsa.gplok = gplok;
        fsa.warn = warn;

        if (each_symbol_section(find_symbol_in_section, &fsa)) {
                if (owner)
                        *owner = fsa.owner;
                if (crc)
                        *crc = fsa.crc;
                return fsa.sym;
        }

        pr_debug("Failed to find symbol %s\n", name);
        return NULL;
}
EXPORT_SYMBOL_GPL(find_symbol);

/*
 * Search for module by name: must hold module_mutex (or preempt disabled
 * for read-only access).
 */
static struct module *find_module_all(const char *name, size_t len,
                                      bool even_unformed)
{
        struct module *mod;

        module_assert_mutex_or_preempt();

        list_for_each_entry_rcu(mod, &modules, list) {
                if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
                        continue;
                if (strlen(mod->name) == len && !memcmp(mod->name, name, len))
                        return mod;
        }
        return NULL;
}

struct module *find_module(const char *name)
{
        module_assert_mutex();
        return find_module_all(name, strlen(name), false);
}
EXPORT_SYMBOL_GPL(find_module);

#ifdef CONFIG_SMP

static inline void __percpu *mod_percpu(struct module *mod)
{
        return mod->percpu;
}

static int percpu_modalloc(struct module *mod, struct load_info *info)
{
        Elf_Shdr *pcpusec = &info->sechdrs[info->index.pcpu];
        unsigned long align = pcpusec->sh_addralign;

        if (!pcpusec->sh_size)
                return 0;

        if (align > PAGE_SIZE) {
                pr_warn("%s: per-cpu alignment %li > %li\n",
                        mod->name, align, PAGE_SIZE);
                align = PAGE_SIZE;
        }

        mod->percpu = __alloc_reserved_percpu(pcpusec->sh_size, align);
        if (!mod->percpu) {
                pr_warn("%s: Could not allocate %lu bytes percpu data\n",
                        mod->name, (unsigned long)pcpusec->sh_size);
                return -ENOMEM;
        }
        mod->percpu_size = pcpusec->sh_size;
        return 0;
}

static void percpu_modfree(struct module *mod)
{
        free_percpu(mod->percpu);
}

static unsigned int find_pcpusec(struct load_info *info)
{
        return find_sec(info, ".data..percpu");
}

static void percpu_modcopy(struct module *mod,
                           const void *from, unsigned long size)
{
        int cpu;

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

bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
{
        struct module *mod;
        unsigned int cpu;

        preempt_disable();

        list_for_each_entry_rcu(mod, &modules, list) {
                if (mod->state == MODULE_STATE_UNFORMED)
                        continue;
                if (!mod->percpu_size)
                        continue;
                for_each_possible_cpu(cpu) {
                        void *start = per_cpu_ptr(mod->percpu, cpu);
                        void *va = (void *)addr;

                        if (va >= start && va < start + mod->percpu_size) {
                                if (can_addr) {
                                        *can_addr = (unsigned long) (va - start);
                                        *can_addr += (unsigned long)
                                                per_cpu_ptr(mod->percpu,
                                                            get_boot_cpu_id());
                                }
                                preempt_enable();
                                return true;
                        }
                }
        }

        preempt_enable();
        return false;
}

/**
 * is_module_percpu_address - test whether address is from module static percpu
 * @addr: address to test
 *
 * Test whether @addr belongs to module static percpu area.
 *
 * RETURNS:
 * %true if @addr is from module static percpu area
 */
bool is_module_percpu_address(unsigned long addr)
{
        return __is_module_percpu_address(addr, NULL);
}

#else /* ... !CONFIG_SMP */

static inline void __percpu *mod_percpu(struct module *mod)
{
        return NULL;
}
static int percpu_modalloc(struct module *mod, struct load_info *info)
{
        /* UP modules shouldn't have this section: ENOMEM isn't quite right */
        if (info->sechdrs[info->index.pcpu].sh_size != 0)
                return -ENOMEM;
        return 0;
}
static inline void percpu_modfree(struct module *mod)
{
}
static unsigned int find_pcpusec(struct load_info *info)
{
        return 0;
}
static inline void percpu_modcopy(struct module *mod,
                                  const void *from, unsigned long size)
{
        /* pcpusec should be 0, and size of that section should be 0. */
        BUG_ON(size != 0);
}
bool is_module_percpu_address(unsigned long addr)
{
        return false;
}

bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
{
        return false;
}

#endif /* CONFIG_SMP */

#define MODINFO_ATTR(field)     \
static void setup_modinfo_##field(struct module *mod, const char *s)  \
{                                                                     \
        mod->field = kstrdup(s, GFP_KERNEL);                          \
}                                                                     \
static ssize_t show_modinfo_##field(struct module_attribute *mattr,   \
                        struct module_kobject *mk, char *buffer)      \
{                                                                     \
        return scnprintf(buffer, PAGE_SIZE, "%s\n", mk->mod->field);  \
}                                                                     \
static int modinfo_##field##_exists(struct module *mod)               \
{                                                                     \
        return mod->field != NULL;                                    \
}                                                                     \
static void free_modinfo_##field(struct module *mod)                  \
{                                                                     \
        kfree(mod->field);                                            \
        mod->field = NULL;                                            \
}                                                                     \
static struct module_attribute modinfo_##field = {                    \
        .attr = { .name = __stringify(field), .mode = 0444 },         \
        .show = show_modinfo_##field,                                 \
        .setup = setup_modinfo_##field,                               \
        .test = modinfo_##field##_exists,                             \
        .free = free_modinfo_##field,                                 \
};

MODINFO_ATTR(version);
MODINFO_ATTR(srcversion);

static char last_unloaded_module[MODULE_NAME_LEN+1];

#ifdef CONFIG_MODULE_UNLOAD

EXPORT_TRACEPOINT_SYMBOL(module_get);

/* MODULE_REF_BASE is the base reference count by kmodule loader. */
#define MODULE_REF_BASE 1

/* Init the unload section of the module. */
static int module_unload_init(struct module *mod)
{
        /*
         * Initialize reference counter to MODULE_REF_BASE.
         * refcnt == 0 means module is going.
         */
        atomic_set(&mod->refcnt, MODULE_REF_BASE);

        INIT_LIST_HEAD(&mod->source_list);
        INIT_LIST_HEAD(&mod->target_list);

        /* Hold reference count during initialization. */
        atomic_inc(&mod->refcnt);

        return 0;
}

/* Does a already use b? */
static int already_uses(struct module *a, struct module *b)
{
        struct module_use *use;

        list_for_each_entry(use, &b->source_list, source_list) {
                if (use->source == a) {
                        pr_debug("%s uses %s!\n", a->name, b->name);
                        return 1;
                }
        }
        pr_debug("%s does not use %s!\n", a->name, b->name);
        return 0;
}

/*
 * Module a uses b
 *  - we add 'a' as a "source", 'b' as a "target" of module use
 *  - the module_use is added to the list of 'b' sources (so
 *    'b' can walk the list to see who sourced them), and of 'a'
 *    targets (so 'a' can see what modules it targets).
 */
static int add_module_usage(struct module *a, struct module *b)
{
        struct module_use *use;

        pr_debug("Allocating new usage for %s.\n", a->name);
        use = kmalloc(sizeof(*use), GFP_ATOMIC);
        if (!use) {
                pr_warn("%s: out of memory loading\n", a->name);
                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() */
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;
}
EXPORT_SYMBOL_GPL(ref_module);

/* 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
 *
 * Returns:
 *      -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];
        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;
                }
        }

        /* Stop the machine so refcounts can't move and disable module. */
        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 of the last unloaded module for diagnostic purposes */
        strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));

        free_module(mod);
        return 0;
out:
        mutex_unlock(&module_mutex);
        return ret;
}

static inline void print_unload_info(struct seq_file *m, struct module *mod)
{
        struct module_use *use;
        int printed_something = 0;

        seq_printf(m, " %i ", module_refcount(mod));

        /*
         * Always include a trailing , so userspace can differentiate
         * between this and the old multi-field proc format.
         */
        list_for_each_entry(use, &mod->source_list, source_list) {
                printed_something = 1;
                seq_printf(m, "%s,", use->source->name);
        }

        if (mod->init != NULL && mod->exit == NULL) {
                printed_something = 1;
                seq_puts(m, "[permanent],");
        }

        if (!printed_something)
                seq_puts(m, "-");
}

void __symbol_put(const char *symbol)
{
        struct module *owner;

        preempt_disable();
        if (!find_symbol(symbol, &owner, NULL, true, false))
                BUG();
        module_put(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 print_unload_info(struct seq_file *m, struct module *mod)
{
        /* We don't know the usage count, or what modules are using. */
        seq_puts(m, " - -");
}

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

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

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

static size_t module_flags_taint(struct module *mod, char *buf)
{
        size_t l = 0;
        int i;

        for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
                if (taint_flags[i].module && test_bit(i, &mod->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)
{
        kobject_synth_uevent(&mk->kobj, buffer, count);
        return 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);

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, buffer);
        buffer[l++] = '\n';
        return l;
}

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

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

static const char vermagic[] = VERMAGIC_STRING;

static 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
}

#ifdef CONFIG_MODVERSIONS

static u32 resolve_rel_crc(const s32 *crc)
{
        return *(u32 *)((void *)crc + *crc);
}

static int check_version(const struct load_info *info,
                         const char *symname,
                         struct module *mod,
                         const s32 *crc)
{
        Elf_Shdr *sechdrs = info->sechdrs;
        unsigned int versindex = info->index.vers;
        unsigned int i, num_versions;
        struct modversion_info *versions;

        /* Exporting module didn't supply crcs?  OK, we're already tainted. */
        if (!crc)
                return 1;

        /* No versions at all?  modprobe --force does this. */
        if (versindex == 0)
                return try_to_force_load(mod, symname) == 0;

        versions = (void *) sechdrs[versindex].sh_addr;
        num_versions = sechdrs[versindex].sh_size
                / sizeof(struct modversion_info);

        for (i = 0; i < num_versions; i++) {
                u32 crcval;

                if (strcmp(versions[i].name, symname) != 0)
                        continue;

                if (IS_ENABLED(CONFIG_MODULE_REL_CRCS))
                        crcval = resolve_rel_crc(crc);
                else
                        crcval = *crc;
                if (versions[i].crc == crcval)
                        return 1;
                pr_debug("Found checksum %X vs module %lX\n",
                         crcval, versions[i].crc);
                goto bad_version;
        }

        /* Broken toolchain. Warn once, then let it go.. */
        pr_warn_once("%s: no symbol version for %s\n", info->name, symname);
        return 1;

bad_version:
        pr_warn("%s: disagrees about version of symbol %s\n",
               info->name, symname);
        return 0;
}

static inline int check_modstruct_version(const struct load_info *info,
                                          struct module *mod)
{
        const s32 *crc;

        /*
         * Since this should be found in kernel (which can't be removed), no
         * locking is necessary -- use preempt_disable() to placate lockdep.
         */
        preempt_disable();
        if (!find_symbol(VMLINUX_SYMBOL_STR(module_layout), NULL,
                         &crc, true, false)) {
                preempt_enable();
                BUG();
        }
        preempt_enable();
        return check_version(info, VMLINUX_SYMBOL_STR(module_layout),
                             mod, crc);
}

/* First part is kernel version, which we ignore if module has crcs. */
static inline int same_magic(const char *amagic, const char *bmagic,
                             bool has_crcs)
{
        if (has_crcs) {
                amagic += strcspn(amagic, " ");
                bmagic += strcspn(bmagic, " ");
        }
        return strcmp(amagic, bmagic) == 0;
}
#else
static inline int check_version(const struct load_info *info,
                                const char *symname,
                                struct module *mod,
                                const s32 *crc)
{
        return 1;
}

static inline int check_modstruct_version(const struct load_info *info,
                                          struct module *mod)
{
        return 1;
}

static inline int same_magic(const char *amagic, const char *bmagic,
                             bool has_crcs)
{
        return strcmp(amagic, bmagic) == 0;
}
#endif /* CONFIG_MODVERSIONS */

/* 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 module *owner;
        const struct kernel_symbol *sym;
        const s32 *crc;
        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);
        sym = find_symbol(name, &owner, &crc,
                          !(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)), true);
        if (!sym)
                goto unlock;

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

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

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

/*
 * /sys/module/foo/sections stuff
 * J. Corbet <corbet@lwn.net>
 */
#ifdef CONFIG_SYSFS

#ifdef CONFIG_KALLSYMS
static inline bool sect_empty(const Elf_Shdr *sect)
{
        return !(sect->sh_flags & SHF_ALLOC) || sect->sh_size == 0;
}

struct module_sect_attr {
        struct module_attribute mattr;
        char *name;
        unsigned long address;
};

struct module_sect_attrs {
        struct attribute_group grp;
        unsigned int nsections;
        struct module_sect_attr attrs[0];
};

static ssize_t module_sect_show(struct module_attribute *mattr,
                                struct module_kobject *mk, char *buf)
{
        struct module_sect_attr *sattr =
                container_of(mattr, struct module_sect_attr, mattr);
        return sprintf(buf, "0x%pK\n", (void *)sattr->address);
}

static void free_sect_attrs(struct module_sect_attrs *sect_attrs)
{
        unsigned int section;

        for (section = 0; section < sect_attrs->nsections; section++)
                kfree(sect_attrs->attrs[section].name);
        kfree(sect_attrs);
}

static void add_sect_attrs(struct module *mod, const struct load_info *info)
{
        unsigned int nloaded = 0, i, size[2];
        struct module_sect_attrs *sect_attrs;
        struct module_sect_attr *sattr;
        struct attribute **gattr;

        /* Count loaded sections and allocate structures */
        for (i = 0; i < info->hdr->e_shnum; i++)
                if (!sect_empty(&info->sechdrs[i]))
                        nloaded++;
        size[0] = ALIGN(sizeof(*sect_attrs)
                        + nloaded * sizeof(sect_attrs->attrs[0]),
                        sizeof(sect_attrs->grp.attrs[0]));
        size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.attrs[0]);
        sect_attrs = kzalloc(size[0] + size[1], GFP_KERNEL);
        if (sect_attrs == NULL)
                return;

        /* Setup section attributes. */
        sect_attrs->grp.name = "sections";
        sect_attrs->grp.attrs = (void *)sect_attrs + size[0];

        sect_attrs->nsections = 0;
        sattr = &sect_attrs->attrs[0];
        gattr = &sect_attrs->grp.attrs[0];
        for (i = 0; i < info->hdr->e_shnum; i++) {
                Elf_Shdr *sec = &info->sechdrs[i];
                if (sect_empty(sec))
                        continue;
                sattr->address = sec->sh_addr;
                sattr->name = kstrdup(info->secstrings + sec->sh_name,
                                        GFP_KERNEL);
                if (sattr->name == NULL)
                        goto out;
                sect_attrs->nsections++;
                sysfs_attr_init(&sattr->mattr.attr);
                sattr->mattr.show = module_sect_show;
                sattr->mattr.store = NULL;
                sattr->mattr.attr.name = sattr->name;
                sattr->mattr.attr.mode = S_IRUGO;
                *(gattr++) = &(sattr++)->mattr.attr;
        }
        *gattr = NULL;

        if (sysfs_create_group(&mod->mkobj.kobj, &sect_attrs->grp))
                goto out;

        mod->sect_attrs = sect_attrs;
        return;
  out:
        free_sect_attrs(sect_attrs);
}

static void remove_sect_attrs(struct module *mod)
{
        if (mod->sect_attrs) {
                sysfs_remove_group(&mod->mkobj.kobj,
                                   &mod->sect_attrs->grp);
                /* We are positive that no one is using any sect attrs
                 * at this point.  Deallocate immediately. */
                free_sect_attrs(mod->sect_attrs);
                mod->sect_attrs = NULL;
        }
}

/*
 * /sys/module/foo/notes/.section.name gives contents of SHT_NOTE sections.
 */

struct module_notes_attrs {
        struct kobject *dir;
        unsigned int notes;
        struct bin_attribute attrs[0];
};

static ssize_t module_notes_read(struct file *filp, struct kobject *kobj,
                                 struct bin_attribute *bin_attr,
                                 char *buf, loff_t pos, size_t count)
{
        /*
         * The caller checked the pos and count against our size.
         */
        memcpy(buf, bin_attr->private + pos, count);
        return count;
}

static void free_notes_attrs(struct module_notes_attrs *notes_attrs,
                             unsigned int i)
{
        if (notes_attrs->dir) {
                while (i-- > 0)
                        sysfs_remove_bin_file(notes_attrs->dir,
                                              &notes_attrs->attrs[i]);
                kobject_put(notes_attrs->dir);
        }
        kfree(notes_attrs);
}

static void add_notes_attrs(struct module *mod, const struct load_info *info)
{
        unsigned int notes, loaded, i;
        struct module_notes_attrs *notes_attrs;
        struct bin_attribute *nattr;

        /* failed to create section attributes, so can't create notes */
        if (!mod->sect_attrs)
                return;

        /* Count notes sections and allocate structures.  */
        notes = 0;
        for (i = 0; i < info->hdr->e_shnum; i++)
                if (!sect_empty(&info->sechdrs[i]) &&
                    (info->sechdrs[i].sh_type == SHT_NOTE))
                        ++notes;

        if (notes == 0)
                return;

        notes_attrs = kzalloc(sizeof(*notes_attrs)
                              + notes * sizeof(notes_attrs->attrs[0]),
                              GFP_KERNEL);
        if (notes_attrs == NULL)
                return;

        notes_attrs->notes = notes;
        nattr = &notes_attrs->attrs[0];
        for (loaded = i = 0; i < info->hdr->e_shnum; ++i) {
                if (sect_empty(&info->sechdrs[i]))
                        continue;
                if (info->sechdrs[i].sh_type == SHT_NOTE) {
                        sysfs_bin_attr_init(nattr);
                        nattr->attr.name = mod->sect_attrs->attrs[loaded].name;
                        nattr->attr.mode = S_IRUGO;
                        nattr->size = info->sechdrs[i].sh_size;
                        nattr->private = (void *) info->sechdrs[i].sh_addr;
                        nattr->read = module_notes_read;
                        ++nattr;
                }
                ++loaded;
        }

        notes_attrs->dir = kobject_create_and_add("notes", &mod->mkobj.kobj);
        if (!notes_attrs->dir)
                goto out;

        for (i = 0; i < notes; ++i)
                if (sysfs_create_bin_file(notes_attrs->dir,
                                          &notes_attrs->attrs[i]))
                        goto out;

        mod->notes_attrs = notes_attrs;
        return;

  out:
        free_notes_attrs(notes_attrs, i);
}

static void remove_notes_attrs(struct module *mod)
{
        if (mod->notes_attrs)
                free_notes_attrs(mod->notes_attrs, mod->notes_attrs->notes);
}

#else

static inline void add_sect_attrs(struct module *mod,
                                  const struct load_info *info)
{
}

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

static inline void add_notes_attrs(struct module *mod,
                                   const struct load_info *info)
{
}

static inline void remove_notes_attrs(struct module *mod)
{
}
#endif /* CONFIG_KALLSYMS */

static void del_usage_links(struct module *mod)
{
#ifdef CONFIG_MODULE_UNLOAD
        struct module_use *use;

        mutex_lock(&module_mutex);
        list_for_each_entry(use, &mod->target_list, target_list)
                sysfs_remove_link(use->target->holders_dir, mod->name);
        mutex_unlock(&module_mutex);
#endif
}

static int add_usage_links(struct module *mod)
{
        int ret = 0;
#ifdef CONFIG_MODULE_UNLOAD
        struct module_use *use;

        mutex_lock(&module_mutex);
        list_for_each_entry(use, &mod->target_list, target_list) {
                ret = sysfs_create_link(use->target->holders_dir,
                                        &mod->mkobj.kobj, mod->name);
                if (ret)
                        break;
        }
        mutex_unlock(&module_mutex);
        if (ret)
                del_usage_links(mod);
#endif
        return ret;
}

static int module_add_modinfo_attrs(struct module *mod)
{
        struct module_attribute *attr;
        struct module_attribute *temp_attr;
        int error = 0;
        int i;

        mod->modinfo_attrs = kzalloc((sizeof(struct module_attribute) *
                                        (ARRAY_SIZE(modinfo_attrs) + 1)),
                                        GFP_KERNEL);
        if (!mod->modinfo_attrs)
                return -ENOMEM;

        temp_attr = mod->modinfo_attrs;
        for (i = 0; (attr = modinfo_attrs[i]) && !error; i++) {
                if (!attr->test || attr->test(mod)) {
                        memcpy(temp_attr, attr, sizeof(*temp_attr));
                        sysfs_attr_init(&temp_attr->attr);
                        error = sysfs_create_file(&mod->mkobj.kobj,
                                        &temp_attr->attr);
                        ++temp_attr;
                }
        }
        return error;
}

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

        for (i = 0; (attr = &mod->modinfo_attrs[i]); i++) {
                /* pick a field to test for end of list */
                if (!attr->attr.name)
                        break;
                sysfs_remove_file(&mod->mkobj.kobj, &attr->attr);
                if (attr->free)
                        attr->free(mod);
        }
        kfree(mod->modinfo_attrs);
}

static void mod_kobject_put(struct module *mod)
{
        DECLARE_COMPLETION_ONSTACK(c);
        mod->mkobj.kobj_completion = &c;
        kobject_put(&mod->mkobj.kobj);
        wait_for_completion(&c);
}

static int mod_sysfs_init(struct module *mod)
{
        int err;
        struct kobject *kobj;

        if (!module_sysfs_initialized) {
                pr_err("%s: module sysfs not initialized\n", mod->name);
                err = -EINVAL;
                goto out;
        }

        kobj = kset_find_obj(module_kset, mod->name);
        if (kobj) {
                pr_err("%s: module is already loaded\n", mod->name);
                kobject_put(kobj);
                err = -EINVAL;
                goto out;
        }

        mod->mkobj.mod = mod;

        memset(&mod->mkobj.kobj, 0, sizeof(mod->mkobj.kobj));
        mod->mkobj.kobj.kset = module_kset;
        err = kobject_init_and_add(&mod->mkobj.kobj, &module_ktype, NULL,
                                   "%s", mod->name);
        if (err)
                mod_kobject_put(mod);

        /* delay uevent until full sysfs population */
out:
        return err;
}

static int mod_sysfs_setup(struct module *mod,
                           const struct load_info *info,
                           struct kernel_param *kparam,
                           unsigned int num_params)
{
        int err;

        err = mod_sysfs_init(mod);
        if (err)
                goto out;

        mod->holders_dir = kobject_create_and_add("holders", &mod->mkobj.kobj);
        if (!mod->holders_dir) {
                err = -ENOMEM;
                goto out_unreg;
        }

        err = module_param_sysfs_setup(mod, kparam, num_params);
        if (err)
                goto out_unreg_holders;

        err = module_add_modinfo_attrs(mod);
        if (err)
                goto out_unreg_param;

        err = add_usage_links(mod);
        if (err)
                goto out_unreg_modinfo_attrs;

        add_sect_attrs(mod, info);
        add_notes_attrs(mod, info);

        kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD);
        return 0;

out_unreg_modinfo_attrs:
        module_remove_modinfo_attrs(mod);
out_unreg_param:
        module_param_sysfs_remove(mod);
out_unreg_holders:
        kobject_put(mod->holders_dir);
out_unreg:
        mod_kobject_put(mod);
out:
        return err;
}

static void mod_sysfs_fini(struct module *mod)
{
        remove_notes_attrs(mod);
        remove_sect_attrs(mod);
        mod_kobject_put(mod);
}

static void init_param_lock(struct module *mod)
{
        mutex_init(&mod->param_lock);
}
#else /* !CONFIG_SYSFS */

static int mod_sysfs_setup(struct module *mod,
                           const struct load_info *info,
                           struct kernel_param *kparam,
                           unsigned int num_params)
{
        return 0;
}

static void mod_sysfs_fini(struct module *mod)
{
}

static void module_remove_modinfo_attrs(struct module *mod)
{
}

static void del_usage_links(struct module *mod)
{
}

static void init_param_lock(struct module *mod)
{
}
#endif /* CONFIG_SYSFS */

static void mod_sysfs_teardown(struct module *mod)
{
        del_usage_links(mod);
        module_remove_modinfo_attrs(mod);
        module_param_sysfs_remove(mod);
        kobject_put(mod->mkobj.drivers_dir);
        kobject_put(mod->holders_dir);
        mod_sysfs_fini(mod);
}

#ifdef CONFIG_STRICT_MODULE_RWX
/*
 * LKM RO/NX protection: protect module's text/ro-data
 * from modification and any data from execution.
 *
 * General layout of module is:
 *          [text] [read-only-data] [ro-after-init] [writable data]
 * text_size -----^                ^               ^               ^
 * ro_size ------------------------|               |               |
 * ro_after_init_size -----------------------------|               |
 * size -----------------------------------------------------------|
 *
 * These values are always page-aligned (as is base)
 */
static void frob_text(const struct module_layout *layout,
                      int (*set_memory)(unsigned long start, int num_pages))
{
        BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1));
        BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1));
        set_memory((unsigned long)layout->base,
                   layout->text_size >> PAGE_SHIFT);
}

static void frob_rodata(const struct module_layout *layout,
                        int (*set_memory)(unsigned long start, int num_pages))
{
        BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1));
        BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1));
        BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1));
        set_memory((unsigned long)layout->base + layout->text_size,
                   (layout->ro_size - layout->text_size) >> PAGE_SHIFT);
}

static void frob_ro_after_init(const struct module_layout *layout,
                                int (*set_memory)(unsigned long start, int num_pages))
{
        BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1));
        BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1));
        BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1));
        set_memory((unsigned long)layout->base + layout->ro_size,
                   (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT);
}

static void frob_writable_data(const struct module_layout *layout,
                               int (*set_memory)(unsigned long start, int num_pages))
{
        BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1));
        BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1));
        BUG_ON((unsigned long)layout->size & (PAGE_SIZE-1));
        set_memory((unsigned long)layout->base + layout->ro_after_init_size,
                   (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT);
}

/* livepatching wants to disable read-only so it can frob module. */
void module_disable_ro(const struct module *mod)
{
        if (!rodata_enabled)
                return;

        frob_text(&mod->core_layout, set_memory_rw);
        frob_rodata(&mod->core_layout, set_memory_rw);
        frob_ro_after_init(&mod->core_layout, set_memory_rw);
        frob_text(&mod->init_layout, set_memory_rw);
        frob_rodata(&mod->init_layout, set_memory_rw);
}

void module_enable_ro(const struct module *mod, bool after_init)
{
        if (!rodata_enabled)
                return;

        frob_text(&mod->core_layout, set_memory_ro);
        frob_rodata(&mod->core_layout, set_memory_ro);
        frob_text(&mod->init_layout, set_memory_ro);
        frob_rodata(&mod->init_layout, set_memory_ro);

        if (after_init)
                frob_ro_after_init(&mod->core_layout, set_memory_ro);
}

static void module_enable_nx(const struct module *mod)
{
        frob_rodata(&mod->core_layout, set_memory_nx);
        frob_ro_after_init(&mod->core_layout, set_memory_nx);
        frob_writable_data(&mod->core_layout, set_memory_nx);
        frob_rodata(&mod->init_layout, set_memory_nx);
        frob_writable_data(&mod->init_layout, set_memory_nx);
}

static void module_disable_nx(const struct module *mod)
{
        frob_rodata(&mod->core_layout, set_memory_x);
        frob_ro_after_init(&mod->core_layout, set_memory_x);
        frob_writable_data(&mod->core_layout, set_memory_x);
        frob_rodata(&mod->init_layout, set_memory_x);
        frob_writable_data(&mod->init_layout, set_memory_x);
}

/* Iterate through all modules and set each module's text as RW */
void set_all_modules_text_rw(void)
{
        struct module *mod;

        if (!rodata_enabled)
                return;

        mutex_lock(&module_mutex);
        list_for_each_entry_rcu(mod, &modules, list) {
                if (mod->state == MODULE_STATE_UNFORMED)
                        continue;

                frob_text(&mod->core_layout, set_memory_rw);
                frob_text(&mod->init_layout, set_memory_rw);
        }
        mutex_unlock(&module_mutex);
}

/* Iterate through all modules and set each module's text as RO */
void set_all_modules_text_ro(void)
{
        struct module *mod;

        if (!rodata_enabled)
                return;

        mutex_lock(&module_mutex);
        list_for_each_entry_rcu(mod, &modules, list) {
                /*
                 * Ignore going modules since it's possible that ro
                 * protection has already been disabled, otherwise we'll
                 * run into protection faults at module deallocation.
                 */
                if (mod->state == MODULE_STATE_UNFORMED ||
                        mod->state == MODULE_STATE_GOING)
                        continue;

                frob_text(&mod->core_layout, set_memory_ro);
                frob_text(&mod->init_layout, set_memory_ro);
        }
        mutex_unlock(&module_mutex);
}

static void disable_ro_nx(const struct module_layout *layout)
{
        if (rodata_enabled) {
                frob_text(layout, set_memory_rw);
                frob_rodata(layout, set_memory_rw);
                frob_ro_after_init(layout, set_memory_rw);
        }
        frob_rodata(layout, set_memory_x);
        frob_ro_after_init(layout, set_memory_x);
        frob_writable_data(layout, set_memory_x);
}

#else
static void disable_ro_nx(const struct module_layout *layout) { }
static void module_enable_nx(const struct module *mod) { }
static void module_disable_nx(const struct module *mod) { }
#endif

#ifdef CONFIG_LIVEPATCH
/*
 * Persist Elf information about a module. Copy the Elf header,
 * section header table, section string table, and symtab section
 * index from info to mod->klp_info.
 */
static int copy_module_elf(struct module *mod, struct load_info *info)
{
        unsigned int size, symndx;
        int ret;

        size = sizeof(*mod->klp_info);
        mod->klp_info = kmalloc(size, GFP_KERNEL);
        if (mod->klp_info == NULL)
                return -ENOMEM;

        /* Elf header */
        size = sizeof(mod->klp_info->hdr);
        memcpy(&mod->klp_info->hdr, info->hdr, size);

        /* Elf section header table */
        size = sizeof(*info->sechdrs) * info->hdr->e_shnum;
        mod->klp_info->sechdrs = kmalloc(size, GFP_KERNEL);
        if (mod->klp_info->sechdrs == NULL) {
                ret = -ENOMEM;
                goto free_info;
        }
        memcpy(mod->klp_info->sechdrs, info->sechdrs, size);

        /* Elf section name string table */
        size = info->sechdrs[info->hdr->e_shstrndx].sh_size;
        mod->klp_info->secstrings = kmalloc(size, GFP_KERNEL);
        if (mod->klp_info->secstrings == NULL) {
                ret = -ENOMEM;
                goto free_sechdrs;
        }
        memcpy(mod->klp_info->secstrings, info->secstrings, size);

        /* Elf symbol section index */
        symndx = info->index.sym;
        mod->klp_info->symndx = symndx;

        /*
         * For livepatch modules, core_kallsyms.symtab is a complete
         * copy of the original symbol table. Adjust sh_addr to point
         * to core_kallsyms.symtab since the copy of the symtab in module
         * init memory is freed at the end of do_init_module().
         */
        mod->klp_info->sechdrs[symndx].sh_addr = \
                (unsigned long) mod->core_kallsyms.symtab;

        return 0;

free_sechdrs:
        kfree(mod->klp_info->sechdrs);
free_info:
        kfree(mod->klp_info);
        return ret;
}

static void free_module_elf(struct module *mod)
{
        kfree(mod->klp_info->sechdrs);
        kfree(mod->klp_info->secstrings);
        kfree(mod->klp_info);
}
#else /* !CONFIG_LIVEPATCH */
static int copy_module_elf(struct module *mod, struct load_info *info)
{
        return 0;
}

static void free_module_elf(struct module *mod)
{
}
#endif /* CONFIG_LIVEPATCH */

void __weak module_memfree(void *module_region)
{
        vfree(module_region);
}

void __weak module_arch_cleanup(struct module *mod)
{
}

void __weak module_arch_freeing_init(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_sched();
        mutex_unlock(&module_mutex);

        /* This may be empty, but that's OK */
        disable_ro_nx(&mod->init_layout);
        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->core_layout.base, mod->core_layout.size);

        /* Finally, free the core (containing the module structure) */
        disable_ro_nx(&mod->core_layout);
        module_memfree(mod->core_layout.base);

#ifdef CONFIG_MPU
        update_protections(current->mm);
#endif
}

void *__symbol_get(const char *symbol)
{
        struct module *owner;
        const struct kernel_symbol *sym;

        preempt_disable();
        sym = find_symbol(symbol, &owner, NULL, true, true);
        if (sym && strong_try_module_get(owner))
                sym = NULL;
        preempt_enable();

        return sym ? (void *)sym->value : NULL;
}
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_export_symbols(struct module *mod)
{
        unsigned int i;
        struct module *owner;
        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 },
                { mod->gpl_future_syms, mod->num_gpl_future_syms },
#ifdef CONFIG_UNUSED_SYMBOLS
                { mod->unused_syms, mod->num_unused_syms },
                { mod->unused_gpl_syms, mod->num_unused_gpl_syms },
#endif
        };

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

/* 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 = ksym->value;
                                break;
                        }

                        /* Ok if weak.  */
                        if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK)
                                break;

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

                /* Livepatch relocation sections are applied by livepatch */
                if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH)
                        continue;

                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. */
static long 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;
}

/* 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;

                        if ((s->sh_flags & masks[m][0]) != masks[m][0]
                            || (s->sh_flags & masks[m][1])
                            || s->sh_entsize != ~0UL
                            || strstarts(sname, ".init"))
                                continue;
                        s->sh_entsize = get_offset(mod, &mod->core_layout.size, s, i);
                        pr_debug("\t%s\n", sname);
                }
                switch (m) {
                case 0: /* executable */
                        mod->core_layout.size = debug_align(mod->core_layout.size);
                        mod->core_layout.text_size = mod->core_layout.size;
                        break;
                case 1: /* RO: text and ro-data */
                        mod->core_layout.size = debug_align(mod->core_layout.size);
                        mod->core_layout.ro_size = mod->core_layout.size;
                        break;
                case 2: /* RO after init */
                        mod->core_layout.size = debug_align(mod->core_layout.size);
                        mod->core_layout.ro_after_init_size = mod->core_layout.size;
                        break;
                case 4: /* whole core */
                        mod->core_layout.size = debug_align(mod->core_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
                            || !strstarts(sname, ".init"))
                                continue;
                        s->sh_entsize = (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 = debug_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 = debug_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 = debug_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_modinfo(struct load_info *info, const char *tag)
{
        char *p;
        unsigned int taglen = strlen(tag);
        Elf_Shdr *infosec = &info->sechdrs[info->index.info];
        unsigned long size = infosec->sh_size;

        for (p = (char *)infosec->sh_addr; p; p = next_string(p, &size)) {
                if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
                        return p + taglen + 1;
        }
        return 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);
        }
}

#ifdef CONFIG_KALLSYMS

/* lookup symbol in given range of kernel_symbols */
static const struct kernel_symbol *lookup_symbol(const char *name,
        const struct kernel_symbol *start,
        const struct kernel_symbol *stop)
{
        return bsearch(name, start, stop - start,
                        sizeof(struct kernel_symbol), cmp_name);
}

static int is_exported(const char *name, unsigned long value,
                       const struct module *mod)
{
        const struct kernel_symbol *ks;
        if (!mod)
                ks = lookup_symbol(name, __start___ksymtab, __stop___ksymtab);
        else
                ks = lookup_symbol(name, mod->syms, mod->syms + mod->num_syms);
        return ks != NULL && ks->value == value;
}

/* As per nm */
static char elf_type(const Elf_Sym *sym, const struct load_info *info)
{
        const Elf_Shdr *sechdrs = info->sechdrs;

        if (ELF_ST_BIND(sym->st_info) == STB_WEAK) {
                if (ELF_ST_TYPE(sym->st_info) == STT_OBJECT)
                        return 'v';
                else
                        return 'w';
        }
        if (sym->st_shndx == SHN_UNDEF)
                return 'U';
        if (sym->st_shndx == SHN_ABS || sym->st_shndx == info->index.pcpu)
                return 'a';
        if (sym->st_shndx >= SHN_LORESERVE)
                return '?';
        if (sechdrs[sym->st_shndx].sh_flags & SHF_EXECINSTR)
                return 't';
        if (sechdrs[sym->st_shndx].sh_flags & SHF_ALLOC
            && sechdrs[sym->st_shndx].sh_type != SHT_NOBITS) {
                if (!(sechdrs[sym->st_shndx].sh_flags & SHF_WRITE))
                        return 'r';
                else if (sechdrs[sym->st_shndx].sh_flags & ARCH_SHF_SMALL)
                        return 'g';
                else
                        return 'd';
        }
        if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
                if (sechdrs[sym->st_shndx].sh_flags & ARCH_SHF_SMALL)
                        return 's';
                else
                        return 'b';
        }
        if (strstarts(info->secstrings + sechdrs[sym->st_shndx].sh_name,
                      ".debug")) {
                return 'n';
        }
        return '?';
}

static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs,
                        unsigned int shnum, unsigned int pcpundx)
{
        const Elf_Shdr *sec;

        if (src->st_shndx == SHN_UNDEF
            || src->st_shndx >= shnum
            || !src->st_name)
                return false;

#ifdef CONFIG_KALLSYMS_ALL
        if (src->st_shndx == pcpundx)
                return true;
#endif

        sec = sechdrs + src->st_shndx;
        if (!(sec->sh_flags & SHF_ALLOC)
#ifndef CONFIG_KALLSYMS_ALL
            || !(sec->sh_flags & SHF_EXECINSTR)
#endif
            || (sec->sh_entsize & INIT_OFFSET_MASK))
                return false;

        return true;
}

/*
 * We only allocate and copy the strings needed by the parts of symtab
 * we keep.  This is simple, but has the effect of making multiple
 * copies of duplicates.  We could be more sophisticated, see
 * linux-kernel thread starting with
 * <73defb5e4bca04a6431392cc341112b1@localhost>.
 */
static void layout_symtab(struct module *mod, struct load_info *info)
{
        Elf_Shdr *symsect = info->sechdrs + info->index.sym;
        Elf_Shdr *strsect = info->sechdrs + info->index.str;
        const Elf_Sym *src;
        unsigned int i, nsrc, ndst, strtab_size = 0;

        /* Put symbol section at end of init part of module. */
        symsect->sh_flags |= SHF_ALLOC;
        symsect->sh_entsize = get_offset(mod, &mod->init_layout.size, symsect,
                                         info->index.sym) | INIT_OFFSET_MASK;
        pr_debug("\t%s\n", info->secstrings + symsect->sh_name);

        src = (void *)info->hdr + symsect->sh_offset;
        nsrc = symsect->sh_size / sizeof(*src);

        /* Compute total space required for the core symbols' strtab. */
        for (ndst = i = 0; i < nsrc; i++) {
                if (i == 0 || is_livepatch_module(mod) ||
                    is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum,
                                   info->index.pcpu)) {
                        strtab_size += strlen(&info->strtab[src[i].st_name])+1;
                        ndst++;
                }
        }

        /* Append room for core symbols at end of core part. */
        info->symoffs = ALIGN(mod->core_layout.size, symsect->sh_addralign ?: 1);
        info->stroffs = mod->core_layout.size = info->symoffs + ndst * sizeof(Elf_Sym);
        mod->core_layout.size += strtab_size;
        mod->core_layout.size = debug_align(mod->core_layout.size);

        /* Put string table section at end of init part of module. */
        strsect->sh_flags |= SHF_ALLOC;
        strsect->sh_entsize = get_offset(mod, &mod->init_layout.size, strsect,
                                         info->index.str) | INIT_OFFSET_MASK;
        pr_debug("\t%s\n", info->secstrings + strsect->sh_name);

        /* We'll tack temporary mod_kallsyms on the end. */
        mod->init_layout.size = ALIGN(mod->init_layout.size,
                                      __alignof__(struct mod_kallsyms));
        info->mod_kallsyms_init_off = mod->init_layout.size;
        mod->init_layout.size += sizeof(struct mod_kallsyms);
        mod->init_layout.size = debug_align(mod->init_layout.size);
}

/*
 * We use the full symtab and strtab which layout_symtab arranged to
 * be appended to the init section.  Later we switch to the cut-down
 * core-only ones.
 */
static void add_kallsyms(struct module *mod, const struct load_info *info)
{
        unsigned int i, ndst;
        const Elf_Sym *src;
        Elf_Sym *dst;
        char *s;
        Elf_Shdr *symsec = &info->sechdrs[info->index.sym];

        /* Set up to point into init section. */
        mod->kallsyms = mod->init_layout.base + info->mod_kallsyms_init_off;

        mod->kallsyms->symtab = (void *)symsec->sh_addr;
        mod->kallsyms->num_symtab = symsec->sh_size / sizeof(Elf_Sym);
        /* Make sure we get permanent strtab: don't use info->strtab. */
        mod->kallsyms->strtab = (void *)info->sechdrs[info->index.str].sh_addr;

        /* Set types up while we still have access to sections. */
        for (i = 0; i < mod->kallsyms->num_symtab; i++)
                mod->kallsyms->symtab[i].st_info
                        = elf_type(&mod->kallsyms->symtab[i], info);

        /* Now populate the cut down core kallsyms for after init. */
        mod->core_kallsyms.symtab = dst = mod->core_layout.base + info->symoffs;
        mod->core_kallsyms.strtab = s = mod->core_layout.base + info->stroffs;
        src = mod->kallsyms->symtab;
        for (ndst = i = 0; i < mod->kallsyms->num_symtab; i++) {
                if (i == 0 || is_livepatch_module(mod) ||
                    is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum,
                                   info->index.pcpu)) {
                        dst[ndst] = src[i];
                        dst[ndst++].st_name = s - mod->core_kallsyms.strtab;
                        s += strlcpy(s, &mod->kallsyms->strtab[src[i].st_name],
                                     KSYM_NAME_LEN) + 1;
                }
        }
        mod->core_kallsyms.num_symtab = ndst;
}
#else
static inline void layout_symtab(struct module *mod, struct load_info *info)
{
}

static void add_kallsyms(struct module *mod, const struct load_info *info)
{
}
#endif /* CONFIG_KALLSYMS */

static void dynamic_debug_setup(struct _ddebug *debug, unsigned int num)
{
        if (!debug)
                return;
#ifdef CONFIG_DYNAMIC_DEBUG
        if (ddebug_add_module(debug, num, debug->modname))
                pr_err("dynamic debug error adding module: %s\n",
                        debug->modname);
#endif
}

static void dynamic_debug_remove(struct _ddebug *debug)
{
        if (debug)
                ddebug_remove_module(debug->modname);
}

void * __weak module_alloc(unsigned long size)
{
        return vmalloc_exec(size);
}

#ifdef CONFIG_DEBUG_KMEMLEAK
static void kmemleak_load_module(const struct module *mod,
                                 const struct load_info *info)
{
        unsigned int i;

        /* only scan the sections containing data */
        kmemleak_scan_area(mod, sizeof(struct module), GFP_KERNEL);

        for (i = 1; i < info->hdr->e_shnum; i++) {
                /* Scan all writable sections that's not executable */
                if (!(info->sechdrs[i].sh_flags & SHF_ALLOC) ||
                    !(info->sechdrs[i].sh_flags & SHF_WRITE) ||
                    (info->sechdrs[i].sh_flags & SHF_EXECINSTR))
                        continue;

                kmemleak_scan_area((void *)info->sechdrs[i].sh_addr,
                                   info->sechdrs[i].sh_size, GFP_KERNEL);
        }
}
#else
static inline void kmemleak_load_module(const struct module *mod,
                                        const struct load_info *info)
{
}
#endif

#ifdef CONFIG_MODULE_SIG
static int module_sig_check(struct load_info *info, int flags)
{
        int err = -ENOKEY;
        const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
        const void *mod = info->hdr;

        /*
         * Require flags == 0, as a module with version information
         * removed is no longer the module that was signed
         */
        if (flags == 0 &&
            info->len > markerlen &&
            memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) {
                /* We truncate the module to discard the signature */
                info->len -= markerlen;
                err = mod_verify_sig(mod, &info->len);
        }

        if (!err) {
                info->sig_ok = true;
                return 0;
        }

        /* Not having a signature is only an error if we're strict. */
        if (err == -ENOKEY && !sig_enforce && !kernel_is_locked_down())
                err = 0;

        return err;
}
#else /* !CONFIG_MODULE_SIG */
static int module_sig_check(struct load_info *info, int flags)
{
        return 0;
}
#endif /* !CONFIG_MODULE_SIG */

/* Sanity checks against invalid binaries, wrong arch, weird elf version. */
static int elf_header_check(struct load_info *info)
{
        if (info->len < sizeof(*(info->hdr)))
                return -ENOEXEC;

        if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0
            || info->hdr->e_type != ET_REL
            || !elf_check_arch(info->hdr)
            || info->hdr->e_shentsize != sizeof(Elf_Shdr))
                return -ENOEXEC;

        if (info->hdr->e_shoff >= info->len
            || (info->hdr->e_shnum * sizeof(Elf_Shdr) >
                info->len - info->hdr->e_shoff))
                return -ENOEXEC;

        return 0;
}

#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;
}

#ifdef CONFIG_LIVEPATCH
static int check_modinfo_livepatch(struct module *mod, struct load_info *info)
{
        if (get_modinfo(info, "livepatch")) {
                mod->klp = true;
                add_taint_module(mod, TAINT_LIVEPATCH, LOCKDEP_STILL_OK);
                pr_notice_once("%s: tainting kernel with TAINT_LIVEPATCH\n",
                               mod->name);
        }

        return 0;
}
#else /* !CONFIG_LIVEPATCH */
static int check_modinfo_livepatch(struct module *mod, struct load_info *info)
{
        if (get_modinfo(info, "livepatch")) {
                pr_err("%s: module is marked as livepatch module, but livepatch support is disabled",
                       mod->name);
                return -ENOEXEC;
        }

        return 0;
}
#endif /* CONFIG_LIVEPATCH */

/* 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_read_file(NULL, READING_MODULE);
        if (err)
                return err;

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

        if (copy_chunked_from_user(info->hdr, umod, info->len) != 0) {
                vfree(info->hdr);
                return -EFAULT;
        }

        return 0;
}

static void free_copy(struct load_info *info)
{
        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];
                if (shdr->sh_type != SHT_NOBITS
                    && info->len < shdr->sh_offset + shdr->sh_size) {
                        pr_err("Module len %lu truncated\n", info->len);
                        return -ENOEXEC;
                }

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

#ifndef CONFIG_MODULE_UNLOAD
                /* Don't load .exit sections */
                if (strstarts(info->secstrings+shdr->sh_name, ".exit"))
                        shdr->sh_flags &= ~(unsigned long)SHF_ALLOC;
#endif
        }

        /* Track but don't keep modinfo and version sections. */
        if (flags & MODULE_INIT_IGNORE_MODVERSIONS)
                info->index.vers = 0; /* Pretend no __versions section! */
        else
                info->index.vers = find_sec(info, "__versions");
        info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;

        info->index.info = find_sec(info, ".modinfo");
        if (!info->index.info)
                info->name = "(missing .modinfo section)";
        else
                info->name = get_modinfo(info, "name");
        info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;

        return 0;
}

/*
 * Set up our basic convenience variables (pointers to section headers,
 * search for module section index etc), and do some basic section
 * verification.
 *
 * Return the temporary module pointer (we'll replace it with the final
 * one when we move the module sections around).
 */
static struct module *setup_load_info(struct load_info *info, int flags)
{
        unsigned int i;
        int err;
        struct module *mod;

        /* Set up the convenience variables */
        info->sechdrs = (void *)info->hdr + info->hdr->e_shoff;
        info->secstrings = (void *)info->hdr
                + info->sechdrs[info->hdr->e_shstrndx].sh_offset;

        err = rewrite_section_headers(info, flags);
        if (err)
                return ERR_PTR(err);

        /* 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;
                }
        }

        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 name field)");
                return ERR_PTR(-ENOEXEC);
        }
        /* This is temporary: point mod into copy of data. */
        mod = (void *)info->sechdrs[info->index.mod].sh_addr;

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

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

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

        /* Check module struct version now, before we try to use module. */
        if (!check_modstruct_version(info, mod))
                return ERR_PTR(-ENOEXEC);

        return mod;
}

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);
        }

        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"));

        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");
        mod->gpl_future_syms = section_objs(info,
                                            "__ksymtab_gpl_future",
                                            sizeof(*mod->gpl_future_syms),
                                            &mod->num_gpl_future_syms);
        mod->gpl_future_crcs = section_addr(info, "__kcrctab_gpl_future");

#ifdef CONFIG_UNUSED_SYMBOLS
        mod->unused_syms = section_objs(info, "__ksymtab_unused",
                                        sizeof(*mod->unused_syms),
                                        &mod->num_unused_syms);
        mod->unused_crcs = section_addr(info, "__kcrctab_unused");
        mod->unused_gpl_syms = section_objs(info, "__ksymtab_unused_gpl",
                                            sizeof(*mod->unused_gpl_syms),
                                            &mod->num_unused_gpl_syms);
        mod->unused_gpl_crcs = section_addr(info, "__kcrctab_unused_gpl");
#endif
#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

#ifdef CONFIG_TRACEPOINTS
        mod->tracepoints_ptrs = section_objs(info, "__tracepoints_ptrs",
                                             sizeof(*mod->tracepoints_ptrs),
                                             &mod->num_tracepoints);
#endif
#ifdef HAVE_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, "__mcount_loc",
                                             sizeof(*mod->ftrace_callsites),
                                             &mod->num_ftrace_callsites);
#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, "__verbose",
                                   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;

        /* 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
                        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)
            || (mod->num_gpl_future_syms && !mod->gpl_future_crcs)
#ifdef CONFIG_UNUSED_SYMBOLS
            || (mod->num_unused_syms && !mod->unused_crcs)
            || (mod->num_unused_gpl_syms && !mod->unused_gpl_crcs)
#endif
                ) {
                return try_to_force_load(mod,
                                         "no versions for exported symbols");
        }
#endif
        return 0;
}

static void flush_module_icache(const struct module *mod)
{
        mm_segment_t old_fs;

        /* flush the icache in correct context */
        old_fs = get_fs();
        set_fs(KERNEL_DS);

        /*
         * 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);

        set_fs(old_fs);
}

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)
{
        /* Module within temporary copy. */
        struct module *mod;
        unsigned int ndx;
        int err;

        mod = setup_load_info(info, flags);
        if (IS_ERR(mod))
                return mod;

        if (blacklisted(info->name))
                return ERR_PTR(-EPERM);

        err = check_modinfo(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, 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;

        /* 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(mod, info);
        layout_symtab(mod, info);

        /* Allocate and move to the final place */
        err = move_module(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);
}

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
                || mod->state == MODULE_STATE_GOING;
        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 rcu_head rcu;
        void *module_init;
};

static void do_free_init(struct rcu_head *head)
{
        struct mod_initfree *m = container_of(head, struct mod_initfree, rcu);
        module_memfree(m->module_init);
        kfree(m);
}

/*
 * 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;

        /*
         * We want to find out whether @mod uses async during init.  Clear
         * PF_USED_ASYNC.  async_schedule*() will set it.
         */
        current->flags &= ~PF_USED_ASYNC;

        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);

        /*
         * We need to finish all async code before the module init sequence
         * is done.  This has potential to deadlock.  For example, a newly
         * detected block device can trigger request_module() of the
         * default iosched from async probing task.  Once userland helper
         * reaches here, async_synchronize_full() will wait on the async
         * task waiting on request_module() and deadlock.
         *
         * This deadlock is avoided by perfomring async_synchronize_full()
         * iff module init queued any async jobs.  This isn't a full
         * solution as it will deadlock the same if module loading from
         * async jobs nests more than once; however, due to the various
         * constraints, this hack seems to be the best option for now.
         * Please refer to the following thread for details.
         *
         * http://thread.gmane.org/gmane.linux.kernel/1420814
         */
        if (!mod->async_probe_requested && (current->flags & PF_USED_ASYNC))
                async_synchronize_full();

        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);
        disable_ro_nx(&mod->init_layout);
        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;
        /*
         * 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_sched(), but we don't want to slow down the success
         * path, so use actual RCU here.
         */
        call_rcu_sched(&freeinit->rcu, do_free_init);
        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_sched();
        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_COMING
                    || old->state == MODULE_STATE_UNFORMED) {
                        /* 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_export_symbols(mod);
        if (err < 0)
                goto out;

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

        module_enable_ro(mod, false);
        module_enable_nx(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:
        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;

        blocking_notifier_call_chain(&module_notify_list,
                                     MODULE_STATE_COMING, mod);
        return 0;
}

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) {
                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;
}

/* 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;
        char *after_dashes;

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

        err = elf_header_check(info);
        if (err)
                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);

        /* 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;
        }

        dynamic_debug_setup(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;

        /* 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);

        /* 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:
        /* module_bug_cleanup needs module_mutex protection */
        mutex_lock(&module_mutex);
        module_bug_cleanup(mod);
        mutex_unlock(&module_mutex);

        /* we can't deallocate the module until we clear memory protection */
        module_disable_ro(mod);
        module_disable_nx(mod);

 ddebug_cleanup:
        dynamic_debug_remove(info->debug);
        synchronize_sched();
        kfree(mod->args);
 free_arch_cleanup:
        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_sched();
        mutex_unlock(&module_mutex);
 free_module:
        /*
         * Ftrace needs to clean up what it initialized.
         * This does nothing if ftrace_module_init() wasn't called,
         * but it must be called outside of module_mutex.
         */
        ftrace_release_mod(mod);
        /* Free lock-classes; relies on the preceding sync_rcu() */
        lockdep_free_key_range(mod->core_layout.base, mod->core_layout.size);

        module_deallocate(mod, info);
 free_copy:
        free_copy(info);
        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 = { };
        loff_t size;
        void *hdr;
        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))
                return -EINVAL;

        err = kernel_read_file_from_fd(fd, &hdr, &size, INT_MAX,
                                       READING_MODULE);
        if (err)
                return err;
        info.hdr = hdr;
        info.len = size;

        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);
}

#ifdef CONFIG_KALLSYMS
/*
 * This ignores the intensely annoying "mapping symbols" found
 * in ARM ELF files: $a, $t and $d.
 */
static inline int is_arm_mapping_symbol(const char *str)
{
        if (str[0] == '.' && str[1] == 'L')
                return true;
        return str[0] == '$' && strchr("axtd", str[1])
               && (str[2] == '\0' || str[2] == '.');
}

static const char *symname(struct mod_kallsyms *kallsyms, unsigned int symnum)
{
        return kallsyms->strtab + kallsyms->symtab[symnum].st_name;
}

static const char *get_ksymbol(struct module *mod,
                               unsigned long addr,
                               unsigned long *size,
                               unsigned long *offset)
{
        unsigned int i, best = 0;
        unsigned long nextval;
        struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);

        /* At worse, next value is at end of module */
        if (within_module_init(addr, mod))
                nextval = (unsigned long)mod->init_layout.base+mod->init_layout.text_size;
        else
                nextval = (unsigned long)mod->core_layout.base+mod->core_layout.text_size;

        /* Scan for closest preceding symbol, and next symbol. (ELF
           starts real symbols at 1). */
        for (i = 1; i < kallsyms->num_symtab; i++) {
                if (kallsyms->symtab[i].st_shndx == SHN_UNDEF)
                        continue;

                /* We ignore unnamed symbols: they're uninformative
                 * and inserted at a whim. */
                if (*symname(kallsyms, i) == '\0'
                    || is_arm_mapping_symbol(symname(kallsyms, i)))
                        continue;

                if (kallsyms->symtab[i].st_value <= addr
                    && kallsyms->symtab[i].st_value > kallsyms->symtab[best].st_value)
                        best = i;
                if (kallsyms->symtab[i].st_value > addr
                    && kallsyms->symtab[i].st_value < nextval)
                        nextval = kallsyms->symtab[i].st_value;
        }

        if (!best)
                return NULL;

        if (size)
                *size = nextval - kallsyms->symtab[best].st_value;
        if (offset)
                *offset = addr - kallsyms->symtab[best].st_value;
        return symname(kallsyms, best);
}

/* For kallsyms to ask for address resolution.  NULL means not found.  Careful
 * not to lock to avoid deadlock on oopses, simply disable preemption. */
const char *module_address_lookup(unsigned long addr,
                            unsigned long *size,
                            unsigned long *offset,
                            char **modname,
                            char *namebuf)
{
        const char *ret = NULL;
        struct module *mod;

        preempt_disable();
        mod = __module_address(addr);
        if (mod) {
                if (modname)
                        *modname = mod->name;
                ret = get_ksymbol(mod, addr, size, offset);
        }
        /* Make a copy in here where it's safe */
        if (ret) {
                strncpy(namebuf, ret, KSYM_NAME_LEN - 1);
                ret = namebuf;
        }
        preempt_enable();

        return ret;
}

int lookup_module_symbol_name(unsigned long addr, char *symname)
{
        struct module *mod;

        preempt_disable();
        list_for_each_entry_rcu(mod, &modules, list) {
                if (mod->state == MODULE_STATE_UNFORMED)
                        continue;
                if (within_module(addr, mod)) {
                        const char *sym;

                        sym = get_ksymbol(mod, addr, NULL, NULL);
                        if (!sym)
                                goto out;
                        strlcpy(symname, sym, KSYM_NAME_LEN);
                        preempt_enable();
                        return 0;
                }
        }
out:
        preempt_enable();
        return -ERANGE;
}

int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size,
                        unsigned long *offset, char *modname, char *name)
{
        struct module *mod;

        preempt_disable();
        list_for_each_entry_rcu(mod, &modules, list) {
                if (mod->state == MODULE_STATE_UNFORMED)
                        continue;
                if (within_module(addr, mod)) {
                        const char *sym;

                        sym = get_ksymbol(mod, addr, size, offset);
                        if (!sym)
                                goto out;
                        if (modname)
                                strlcpy(modname, mod->name, MODULE_NAME_LEN);
                        if (name)
                                strlcpy(name, sym, KSYM_NAME_LEN);
                        preempt_enable();
                        return 0;
                }
        }
out:
        preempt_enable();
        return -ERANGE;
}

int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
                        char *name, char *module_name, int *exported)
{
        struct module *mod;

        preempt_disable();
        list_for_each_entry_rcu(mod, &modules, list) {
                struct mod_kallsyms *kallsyms;

                if (mod->state == MODULE_STATE_UNFORMED)
                        continue;
                kallsyms = rcu_dereference_sched(mod->kallsyms);
                if (symnum < kallsyms->num_symtab) {
                        *value = kallsyms->symtab[symnum].st_value;
                        *type = kallsyms->symtab[symnum].st_info;
                        strlcpy(name, symname(kallsyms, symnum), KSYM_NAME_LEN);
                        strlcpy(module_name, mod->name, MODULE_NAME_LEN);
                        *exported = is_exported(name, *value, mod);
                        preempt_enable();
                        return 0;
                }
                symnum -= kallsyms->num_symtab;
        }
        preempt_enable();
        return -ERANGE;
}

static unsigned long mod_find_symname(struct module *mod, const char *name)
{
        unsigned int i;
        struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);

        for (i = 0; i < kallsyms->num_symtab; i++)
                if (strcmp(name, symname(kallsyms, i)) == 0 &&
                    kallsyms->symtab[i].st_info != 'U')
                        return kallsyms->symtab[i].st_value;
        return 0;
}

/* Look for this name: can be of form module:name. */
unsigned long module_kallsyms_lookup_name(const char *name)
{
        struct module *mod;
        char *colon;
        unsigned long ret = 0;

        /* Don't lock: we're in enough trouble already. */
        preempt_disable();
        if ((colon = strnchr(name, MODULE_NAME_LEN, ':')) != NULL) {
                if ((mod = find_module_all(name, colon - name, false)) != NULL)
                        ret = mod_find_symname(mod, colon+1);
        } else {
                list_for_each_entry_rcu(mod, &modules, list) {
                        if (mod->state == MODULE_STATE_UNFORMED)
                                continue;
                        if ((ret = mod_find_symname(mod, name)) != 0)
                                break;
                }
        }
        preempt_enable();
        return ret;
}

int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
                                             struct module *, unsigned long),
                                   void *data)
{
        struct module *mod;
        unsigned int i;
        int ret;

        module_assert_mutex();

        list_for_each_entry(mod, &modules, list) {
                /* We hold module_mutex: no need for rcu_dereference_sched */
                struct mod_kallsyms *kallsyms = mod->kallsyms;

                if (mod->state == MODULE_STATE_UNFORMED)
                        continue;
                for (i = 0; i < kallsyms->num_symtab; i++) {
                        ret = fn(data, symname(kallsyms, i),
                                 mod, kallsyms->symtab[i].st_value);
                        if (ret != 0)
                                return ret;
                }
        }
        return 0;
}
#endif /* CONFIG_KALLSYMS */

/* Maximum number of characters written by module_flags() */
#define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)

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

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

        return buf;
}

#ifdef CONFIG_PROC_FS
/* Called by the /proc file system to return a list of modules. */
static void *m_start(struct seq_file *m, loff_t *pos)
{
        mutex_lock(&module_mutex);
        return seq_list_start(&modules, *pos);
}

static void *m_next(struct seq_file *m, void *p, loff_t *pos)
{
        return seq_list_next(p, &modules, pos);
}

static void m_stop(struct seq_file *m, void *p)
{
        mutex_unlock(&module_mutex);
}

static int m_show(struct seq_file *m, void *p)
{
        struct module *mod = list_entry(p, struct module, list);
        char buf[MODULE_FLAGS_BUF_SIZE];

        /* We always ignore unformed modules. */
        if (mod->state == MODULE_STATE_UNFORMED)
                return 0;

        seq_printf(m, "%s %u",
                   mod->name, mod->init_layout.size + mod->core_layout.size);
        print_unload_info(m, mod);

        /* Informative for users. */
        seq_printf(m, " %s",
                   mod->state == MODULE_STATE_GOING ? "Unloading" :
                   mod->state == MODULE_STATE_COMING ? "Loading" :
                   "Live");
        /* Used by oprofile and other similar tools. */
        seq_printf(m, " 0x%pK", mod->core_layout.base);

        /* Taints info */
        if (mod->taints)
                seq_printf(m, " %s", module_flags(mod, buf));

        seq_puts(m, "\n");
        return 0;
}

/* Format: modulename size refcount deps address

   Where refcount is a number or -, and deps is a comma-separated list
   of depends or -.
*/
static const struct seq_operations modules_op = {
        .start  = m_start,
        .next   = m_next,
        .stop   = m_stop,
        .show   = m_show
};

static int modules_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &modules_op);
}

static const struct file_operations proc_modules_operations = {
        .open           = modules_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

static int __init proc_modules_init(void)
{
        proc_create("modules", 0, NULL, &proc_modules_operations);
        return 0;
}
module_init(proc_modules_init);
#endif

/* 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;

        if (addr < module_addr_min || addr > module_addr_max)
                return NULL;

        module_assert_mutex_or_preempt();

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

/*
 * 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;
}
EXPORT_SYMBOL_GPL(__module_text_address);

/* 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));
        }
        preempt_enable();
        if (last_unloaded_module[0])
                pr_cont(" [last unloaded: %s]", last_unloaded_module);
        pr_cont("\n");
}

#ifdef CONFIG_MODVERSIONS
/* Generate the signature for all relevant module structures here.
 * If these change, we don't want to try to parse the module. */
void module_layout(struct module *mod,
                   struct modversion_info *ver,
                   struct kernel_param *kp,
                   struct kernel_symbol *ks,
                   struct tracepoint * const *tp)
{
}
EXPORT_SYMBOL(module_layout);
#endif