autofs4: Do not potentially dereference NULL pointer returned by fget() in autofs_dev...

[mirror_ubuntu-bionic-kernel.git] / crypto / api.c

/*
 * Scatterlist Cryptographic API.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2002 David S. Miller (davem@redhat.com)
 * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * Portions derived from Cryptoapi, by Alexander Kjeldaas <astor@fast.no>
 * and Nettle, by Niels Möller.
 *
 * 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.
 *
 */

#include <linux/err.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/param.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "internal.h"

LIST_HEAD(crypto_alg_list);
EXPORT_SYMBOL_GPL(crypto_alg_list);
DECLARE_RWSEM(crypto_alg_sem);
EXPORT_SYMBOL_GPL(crypto_alg_sem);

BLOCKING_NOTIFIER_HEAD(crypto_chain);
EXPORT_SYMBOL_GPL(crypto_chain);

static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
{
        atomic_inc(&alg->cra_refcnt);
        return alg;
}

struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
{
        return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
}
EXPORT_SYMBOL_GPL(crypto_mod_get);

void crypto_mod_put(struct crypto_alg *alg)
{
        struct module *module = alg->cra_module;

        crypto_alg_put(alg);
        module_put(module);
}
EXPORT_SYMBOL_GPL(crypto_mod_put);

static inline int crypto_is_test_larval(struct crypto_larval *larval)
{
        return larval->alg.cra_driver_name[0];
}

static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
                                              u32 mask)
{
        struct crypto_alg *q, *alg = NULL;
        int best = -2;

        list_for_each_entry(q, &crypto_alg_list, cra_list) {
                int exact, fuzzy;

                if (crypto_is_moribund(q))
                        continue;

                if ((q->cra_flags ^ type) & mask)
                        continue;

                if (crypto_is_larval(q) &&
                    !crypto_is_test_larval((struct crypto_larval *)q) &&
                    ((struct crypto_larval *)q)->mask != mask)
                        continue;

                exact = !strcmp(q->cra_driver_name, name);
                fuzzy = !strcmp(q->cra_name, name);
                if (!exact && !(fuzzy && q->cra_priority > best))
                        continue;

                if (unlikely(!crypto_mod_get(q)))
                        continue;

                best = q->cra_priority;
                if (alg)
                        crypto_mod_put(alg);
                alg = q;

                if (exact)
                        break;
        }

        return alg;
}

static void crypto_larval_destroy(struct crypto_alg *alg)
{
        struct crypto_larval *larval = (void *)alg;

        BUG_ON(!crypto_is_larval(alg));
        if (larval->adult)
                crypto_mod_put(larval->adult);
        kfree(larval);
}

struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
{
        struct crypto_larval *larval;

        larval = kzalloc(sizeof(*larval), GFP_KERNEL);
        if (!larval)
                return ERR_PTR(-ENOMEM);

        larval->mask = mask;
        larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
        larval->alg.cra_priority = -1;
        larval->alg.cra_destroy = crypto_larval_destroy;

        strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
        init_completion(&larval->completion);

        return larval;
}
EXPORT_SYMBOL_GPL(crypto_larval_alloc);

static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
                                            u32 mask)
{
        struct crypto_alg *alg;
        struct crypto_larval *larval;

        larval = crypto_larval_alloc(name, type, mask);
        if (IS_ERR(larval))
                return ERR_CAST(larval);

        atomic_set(&larval->alg.cra_refcnt, 2);

        down_write(&crypto_alg_sem);
        alg = __crypto_alg_lookup(name, type, mask);
        if (!alg) {
                alg = &larval->alg;
                list_add(&alg->cra_list, &crypto_alg_list);
        }
        up_write(&crypto_alg_sem);

        if (alg != &larval->alg)
                kfree(larval);

        return alg;
}

void crypto_larval_kill(struct crypto_alg *alg)
{
        struct crypto_larval *larval = (void *)alg;

        down_write(&crypto_alg_sem);
        list_del(&alg->cra_list);
        up_write(&crypto_alg_sem);
        complete_all(&larval->completion);
        crypto_alg_put(alg);
}
EXPORT_SYMBOL_GPL(crypto_larval_kill);

static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
{
        struct crypto_larval *larval = (void *)alg;
        long timeout;

        timeout = wait_for_completion_interruptible_timeout(
                &larval->completion, 60 * HZ);

        alg = larval->adult;
        if (timeout < 0)
                alg = ERR_PTR(-EINTR);
        else if (!timeout)
                alg = ERR_PTR(-ETIMEDOUT);
        else if (!alg)
                alg = ERR_PTR(-ENOENT);
        else if (crypto_is_test_larval(larval) &&
                 !(alg->cra_flags & CRYPTO_ALG_TESTED))
                alg = ERR_PTR(-EAGAIN);
        else if (!crypto_mod_get(alg))
                alg = ERR_PTR(-EAGAIN);
        crypto_mod_put(&larval->alg);

        return alg;
}

struct crypto_alg *crypto_alg_lookup(const char *name, u32 type, u32 mask)
{
        struct crypto_alg *alg;

        down_read(&crypto_alg_sem);
        alg = __crypto_alg_lookup(name, type, mask);
        up_read(&crypto_alg_sem);

        return alg;
}
EXPORT_SYMBOL_GPL(crypto_alg_lookup);

struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
{
        struct crypto_alg *alg;

        if (!name)
                return ERR_PTR(-ENOENT);

        mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
        type &= mask;

        alg = crypto_alg_lookup(name, type, mask);
        if (!alg) {
                request_module("%s", name);

                if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
                      CRYPTO_ALG_NEED_FALLBACK))
                        request_module("%s-all", name);

                alg = crypto_alg_lookup(name, type, mask);
        }

        if (alg)
                return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;

        return crypto_larval_add(name, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_larval_lookup);

int crypto_probing_notify(unsigned long val, void *v)
{
        int ok;

        ok = blocking_notifier_call_chain(&crypto_chain, val, v);
        if (ok == NOTIFY_DONE) {
                request_module("cryptomgr");
                ok = blocking_notifier_call_chain(&crypto_chain, val, v);
        }

        return ok;
}
EXPORT_SYMBOL_GPL(crypto_probing_notify);

struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
{
        struct crypto_alg *alg;
        struct crypto_alg *larval;
        int ok;

        if (!((type | mask) & CRYPTO_ALG_TESTED)) {
                type |= CRYPTO_ALG_TESTED;
                mask |= CRYPTO_ALG_TESTED;
        }

        larval = crypto_larval_lookup(name, type, mask);
        if (IS_ERR(larval) || !crypto_is_larval(larval))
                return larval;

        ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);

        if (ok == NOTIFY_STOP)
                alg = crypto_larval_wait(larval);
        else {
                crypto_mod_put(larval);
                alg = ERR_PTR(-ENOENT);
        }
        crypto_larval_kill(larval);
        return alg;
}
EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);

static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
{
        const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;

        if (type_obj)
                return type_obj->init(tfm, type, mask);

        switch (crypto_tfm_alg_type(tfm)) {
        case CRYPTO_ALG_TYPE_CIPHER:
                return crypto_init_cipher_ops(tfm);

        case CRYPTO_ALG_TYPE_COMPRESS:
                return crypto_init_compress_ops(tfm);

        default:
                break;
        }

        BUG();
        return -EINVAL;
}

static void crypto_exit_ops(struct crypto_tfm *tfm)
{
        const struct crypto_type *type = tfm->__crt_alg->cra_type;

        if (type) {
                if (tfm->exit)
                        tfm->exit(tfm);
                return;
        }

        switch (crypto_tfm_alg_type(tfm)) {
        case CRYPTO_ALG_TYPE_CIPHER:
                crypto_exit_cipher_ops(tfm);
                break;

        case CRYPTO_ALG_TYPE_COMPRESS:
                crypto_exit_compress_ops(tfm);
                break;

        default:
                BUG();
        }
}

static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
{
        const struct crypto_type *type_obj = alg->cra_type;
        unsigned int len;

        len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
        if (type_obj)
                return len + type_obj->ctxsize(alg, type, mask);

        switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
        default:
                BUG();

        case CRYPTO_ALG_TYPE_CIPHER:
                len += crypto_cipher_ctxsize(alg);
                break;

        case CRYPTO_ALG_TYPE_COMPRESS:
                len += crypto_compress_ctxsize(alg);
                break;
        }

        return len;
}

void crypto_shoot_alg(struct crypto_alg *alg)
{
        down_write(&crypto_alg_sem);
        alg->cra_flags |= CRYPTO_ALG_DYING;
        up_write(&crypto_alg_sem);
}
EXPORT_SYMBOL_GPL(crypto_shoot_alg);

struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
                                      u32 mask)
{
        struct crypto_tfm *tfm = NULL;
        unsigned int tfm_size;
        int err = -ENOMEM;

        tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
        tfm = kzalloc(tfm_size, GFP_KERNEL);
        if (tfm == NULL)
                goto out_err;

        tfm->__crt_alg = alg;

        err = crypto_init_ops(tfm, type, mask);
        if (err)
                goto out_free_tfm;

        if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
                goto cra_init_failed;

        goto out;

cra_init_failed:
        crypto_exit_ops(tfm);
out_free_tfm:
        if (err == -EAGAIN)
                crypto_shoot_alg(alg);
        kfree(tfm);
out_err:
        tfm = ERR_PTR(err);
out:
        return tfm;
}
EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);

/*
 *      crypto_alloc_base - Locate algorithm and allocate transform
 *      @alg_name: Name of algorithm
 *      @type: Type of algorithm
 *      @mask: Mask for type comparison
 *
 *      This function should not be used by new algorithm types.
 *      Plesae use crypto_alloc_tfm instead.
 *
 *      crypto_alloc_base() will first attempt to locate an already loaded
 *      algorithm.  If that fails and the kernel supports dynamically loadable
 *      modules, it will then attempt to load a module of the same name or
 *      alias.  If that fails it will send a query to any loaded crypto manager
 *      to construct an algorithm on the fly.  A refcount is grabbed on the
 *      algorithm which is then associated with the new transform.
 *
 *      The returned transform is of a non-determinate type.  Most people
 *      should use one of the more specific allocation functions such as
 *      crypto_alloc_blkcipher.
 *
 *      In case of error the return value is an error pointer.
 */
struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
{
        struct crypto_tfm *tfm;
        int err;

        for (;;) {
                struct crypto_alg *alg;

                alg = crypto_alg_mod_lookup(alg_name, type, mask);
                if (IS_ERR(alg)) {
                        err = PTR_ERR(alg);
                        goto err;
                }

                tfm = __crypto_alloc_tfm(alg, type, mask);
                if (!IS_ERR(tfm))
                        return tfm;

                crypto_mod_put(alg);
                err = PTR_ERR(tfm);

err:
                if (err != -EAGAIN)
                        break;
                if (signal_pending(current)) {
                        err = -EINTR;
                        break;
                }
        }

        return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(crypto_alloc_base);

void *crypto_create_tfm(struct crypto_alg *alg,
                        const struct crypto_type *frontend)
{
        char *mem;
        struct crypto_tfm *tfm = NULL;
        unsigned int tfmsize;
        unsigned int total;
        int err = -ENOMEM;

        tfmsize = frontend->tfmsize;
        total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);

        mem = kzalloc(total, GFP_KERNEL);
        if (mem == NULL)
                goto out_err;

        tfm = (struct crypto_tfm *)(mem + tfmsize);
        tfm->__crt_alg = alg;

        err = frontend->init_tfm(tfm);
        if (err)
                goto out_free_tfm;

        if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
                goto cra_init_failed;

        goto out;

cra_init_failed:
        crypto_exit_ops(tfm);
out_free_tfm:
        if (err == -EAGAIN)
                crypto_shoot_alg(alg);
        kfree(mem);
out_err:
        mem = ERR_PTR(err);
out:
        return mem;
}
EXPORT_SYMBOL_GPL(crypto_create_tfm);

struct crypto_alg *crypto_find_alg(const char *alg_name,
                                   const struct crypto_type *frontend,
                                   u32 type, u32 mask)
{
        struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask) =
                crypto_alg_mod_lookup;

        if (frontend) {
                type &= frontend->maskclear;
                mask &= frontend->maskclear;
                type |= frontend->type;
                mask |= frontend->maskset;

                if (frontend->lookup)
                        lookup = frontend->lookup;
        }

        return lookup(alg_name, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_find_alg);

/*
 *      crypto_alloc_tfm - Locate algorithm and allocate transform
 *      @alg_name: Name of algorithm
 *      @frontend: Frontend algorithm type
 *      @type: Type of algorithm
 *      @mask: Mask for type comparison
 *
 *      crypto_alloc_tfm() will first attempt to locate an already loaded
 *      algorithm.  If that fails and the kernel supports dynamically loadable
 *      modules, it will then attempt to load a module of the same name or
 *      alias.  If that fails it will send a query to any loaded crypto manager
 *      to construct an algorithm on the fly.  A refcount is grabbed on the
 *      algorithm which is then associated with the new transform.
 *
 *      The returned transform is of a non-determinate type.  Most people
 *      should use one of the more specific allocation functions such as
 *      crypto_alloc_blkcipher.
 *
 *      In case of error the return value is an error pointer.
 */
void *crypto_alloc_tfm(const char *alg_name,
                       const struct crypto_type *frontend, u32 type, u32 mask)
{
        void *tfm;
        int err;

        for (;;) {
                struct crypto_alg *alg;

                alg = crypto_find_alg(alg_name, frontend, type, mask);
                if (IS_ERR(alg)) {
                        err = PTR_ERR(alg);
                        goto err;
                }

                tfm = crypto_create_tfm(alg, frontend);
                if (!IS_ERR(tfm))
                        return tfm;

                crypto_mod_put(alg);
                err = PTR_ERR(tfm);

err:
                if (err != -EAGAIN)
                        break;
                if (signal_pending(current)) {
                        err = -EINTR;
                        break;
                }
        }

        return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(crypto_alloc_tfm);

/*
 *      crypto_destroy_tfm - Free crypto transform
 *      @mem: Start of tfm slab
 *      @tfm: Transform to free
 *
 *      This function frees up the transform and any associated resources,
 *      then drops the refcount on the associated algorithm.
 */
void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
{
        struct crypto_alg *alg;

        if (unlikely(!mem))
                return;

        alg = tfm->__crt_alg;

        if (!tfm->exit && alg->cra_exit)
                alg->cra_exit(tfm);
        crypto_exit_ops(tfm);
        crypto_mod_put(alg);
        kzfree(mem);
}
EXPORT_SYMBOL_GPL(crypto_destroy_tfm);

int crypto_has_alg(const char *name, u32 type, u32 mask)
{
        int ret = 0;
        struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);

        if (!IS_ERR(alg)) {
                crypto_mod_put(alg);
                ret = 1;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(crypto_has_alg);

MODULE_DESCRIPTION("Cryptographic core API");
MODULE_LICENSE("GPL");