ablkcipher.c

Go to the documentation of this file.

/*
 * Asynchronous block chaining cipher operations.
 *
 * This is the asynchronous version of blkcipher.c indicating completion
 * via a callback.
 *
 * Copyright (c) 2006 Herbert Xu <[email protected]>
 *
 * 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 <crypto/internal/skcipher.h>
#include <linux/cpumask.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rtnetlink.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/cryptouser.h>
#include <net/netlink.h>

#include <crypto/scatterwalk.h>

#include "internal.h"

static const char *skcipher_default_geniv __read_mostly;

struct ablkcipher_buffer {
    struct list_head    entry;
    struct scatter_walk dst;
    unsigned int        len;
    void            *data;
};

enum {
    ABLKCIPHER_WALK_SLOW = 1 << 0,
};

static inline void ablkcipher_buffer_write(struct ablkcipher_buffer *p)
{
    scatterwalk_copychunks(p->data, &p->dst, p->len, 1);
}

void __ablkcipher_walk_complete(struct ablkcipher_walk *walk)
{
    struct ablkcipher_buffer *p, *tmp;

    list_for_each_entry_safe(p, tmp, &walk->buffers, entry) {
        ablkcipher_buffer_write(p);
        list_del(&p->entry);
        kfree(p);
    }
}
EXPORT_SYMBOL_GPL(__ablkcipher_walk_complete);

static inline void ablkcipher_queue_write(struct ablkcipher_walk *walk,
                      struct ablkcipher_buffer *p)
{
    p->dst = walk->out;
    list_add_tail(&p->entry, &walk->buffers);
}

/* Get a spot of the specified length that does not straddle a page.
 * The caller needs to ensure that there is enough space for this operation.
 */
static inline u8 *ablkcipher_get_spot(u8 *start, unsigned int len)
{
    u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK);
    return max(start, end_page);
}

static inline unsigned int ablkcipher_done_slow(struct ablkcipher_walk *walk,
                        unsigned int bsize)
{
    unsigned int n = bsize;

    for (;;) {
        unsigned int len_this_page = scatterwalk_pagelen(&walk->out);

        if (len_this_page > n)
            len_this_page = n;
        scatterwalk_advance(&walk->out, n);
        if (n == len_this_page)
            break;
        n -= len_this_page;
        scatterwalk_start(&walk->out, scatterwalk_sg_next(walk->out.sg));
    }

    return bsize;
}

static inline unsigned int ablkcipher_done_fast(struct ablkcipher_walk *walk,
                        unsigned int n)
{
    scatterwalk_advance(&walk->in, n);
    scatterwalk_advance(&walk->out, n);

    return n;
}

static int ablkcipher_walk_next(struct ablkcipher_request *req,
                struct ablkcipher_walk *walk);

int ablkcipher_walk_done(struct ablkcipher_request *req,
             struct ablkcipher_walk *walk, int err)
{
    struct crypto_tfm *tfm = req->base.tfm;
    unsigned int nbytes = 0;

    if (likely(err >= 0)) {
        unsigned int n = walk->nbytes - err;

        if (likely(!(walk->flags & ABLKCIPHER_WALK_SLOW)))
            n = ablkcipher_done_fast(walk, n);
        else if (WARN_ON(err)) {
            err = -EINVAL;
            goto err;
        } else
            n = ablkcipher_done_slow(walk, n);

        nbytes = walk->total - n;
        err = 0;
    }

    scatterwalk_done(&walk->in, 0, nbytes);
    scatterwalk_done(&walk->out, 1, nbytes);

err:
    walk->total = nbytes;
    walk->nbytes = nbytes;

    if (nbytes) {
        crypto_yield(req->base.flags);
        return ablkcipher_walk_next(req, walk);
    }

    if (walk->iv != req->info)
        memcpy(req->info, walk->iv, tfm->crt_ablkcipher.ivsize);
    kfree(walk->iv_buffer);

    return err;
}
EXPORT_SYMBOL_GPL(ablkcipher_walk_done);

static inline int ablkcipher_next_slow(struct ablkcipher_request *req,
                       struct ablkcipher_walk *walk,
                       unsigned int bsize,
                       unsigned int alignmask,
                       void **src_p, void **dst_p)
{
    unsigned aligned_bsize = ALIGN(bsize, alignmask + 1);
    struct ablkcipher_buffer *p;
    void *src, *dst, *base;
    unsigned int n;

    n = ALIGN(sizeof(struct ablkcipher_buffer), alignmask + 1);
    n += (aligned_bsize * 3 - (alignmask + 1) +
          (alignmask & ~(crypto_tfm_ctx_alignment() - 1)));

    p = kmalloc(n, GFP_ATOMIC);
    if (!p)
        return ablkcipher_walk_done(req, walk, -ENOMEM);

    base = p + 1;

    dst = (u8 *)ALIGN((unsigned long)base, alignmask + 1);
    src = dst = ablkcipher_get_spot(dst, bsize);

    p->len = bsize;
    p->data = dst;

    scatterwalk_copychunks(src, &walk->in, bsize, 0);

    ablkcipher_queue_write(walk, p);

    walk->nbytes = bsize;
    walk->flags |= ABLKCIPHER_WALK_SLOW;

    *src_p = src;
    *dst_p = dst;

    return 0;
}

static inline int ablkcipher_copy_iv(struct ablkcipher_walk *walk,
                     struct crypto_tfm *tfm,
                     unsigned int alignmask)
{
    unsigned bs = walk->blocksize;
    unsigned int ivsize = tfm->crt_ablkcipher.ivsize;
    unsigned aligned_bs = ALIGN(bs, alignmask + 1);
    unsigned int size = aligned_bs * 2 + ivsize + max(aligned_bs, ivsize) -
                (alignmask + 1);
    u8 *iv;

    size += alignmask & ~(crypto_tfm_ctx_alignment() - 1);
    walk->iv_buffer = kmalloc(size, GFP_ATOMIC);
    if (!walk->iv_buffer)
        return -ENOMEM;

    iv = (u8 *)ALIGN((unsigned long)walk->iv_buffer, alignmask + 1);
    iv = ablkcipher_get_spot(iv, bs) + aligned_bs;
    iv = ablkcipher_get_spot(iv, bs) + aligned_bs;
    iv = ablkcipher_get_spot(iv, ivsize);

    walk->iv = memcpy(iv, walk->iv, ivsize);
    return 0;
}

static inline int ablkcipher_next_fast(struct ablkcipher_request *req,
                       struct ablkcipher_walk *walk)
{
    walk->src.page = scatterwalk_page(&walk->in);
    walk->src.offset = offset_in_page(walk->in.offset);
    walk->dst.page = scatterwalk_page(&walk->out);
    walk->dst.offset = offset_in_page(walk->out.offset);

    return 0;
}

static int ablkcipher_walk_next(struct ablkcipher_request *req,
                struct ablkcipher_walk *walk)
{
    struct crypto_tfm *tfm = req->base.tfm;
    unsigned int alignmask, bsize, n;
    void *src, *dst;
    int err;

    alignmask = crypto_tfm_alg_alignmask(tfm);
    n = walk->total;
    if (unlikely(n < crypto_tfm_alg_blocksize(tfm))) {
        req->base.flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
        return ablkcipher_walk_done(req, walk, -EINVAL);
    }

    walk->flags &= ~ABLKCIPHER_WALK_SLOW;
    src = dst = NULL;

    bsize = min(walk->blocksize, n);
    n = scatterwalk_clamp(&walk->in, n);
    n = scatterwalk_clamp(&walk->out, n);

    if (n < bsize ||
        !scatterwalk_aligned(&walk->in, alignmask) ||
        !scatterwalk_aligned(&walk->out, alignmask)) {
        err = ablkcipher_next_slow(req, walk, bsize, alignmask,
                       &src, &dst);
        goto set_phys_lowmem;
    }

    walk->nbytes = n;

    return ablkcipher_next_fast(req, walk);

set_phys_lowmem:
    if (err >= 0) {
        walk->src.page = virt_to_page(src);
        walk->dst.page = virt_to_page(dst);
        walk->src.offset = ((unsigned long)src & (PAGE_SIZE - 1));
        walk->dst.offset = ((unsigned long)dst & (PAGE_SIZE - 1));
    }

    return err;
}

static int ablkcipher_walk_first(struct ablkcipher_request *req,
                 struct ablkcipher_walk *walk)
{
    struct crypto_tfm *tfm = req->base.tfm;
    unsigned int alignmask;

    alignmask = crypto_tfm_alg_alignmask(tfm);
    if (WARN_ON_ONCE(in_irq()))
        return -EDEADLK;

    walk->nbytes = walk->total;
    if (unlikely(!walk->total))
        return 0;

    walk->iv_buffer = NULL;
    walk->iv = req->info;
    if (unlikely(((unsigned long)walk->iv & alignmask))) {
        int err = ablkcipher_copy_iv(walk, tfm, alignmask);
        if (err)
            return err;
    }

    scatterwalk_start(&walk->in, walk->in.sg);
    scatterwalk_start(&walk->out, walk->out.sg);

    return ablkcipher_walk_next(req, walk);
}

int ablkcipher_walk_phys(struct ablkcipher_request *req,
             struct ablkcipher_walk *walk)
{
    walk->blocksize = crypto_tfm_alg_blocksize(req->base.tfm);
    return ablkcipher_walk_first(req, walk);
}
EXPORT_SYMBOL_GPL(ablkcipher_walk_phys);

static int setkey_unaligned(struct crypto_ablkcipher *tfm, const u8 *key,
                unsigned int keylen)
{
    struct ablkcipher_alg *cipher = crypto_ablkcipher_alg(tfm);
    unsigned long alignmask = crypto_ablkcipher_alignmask(tfm);
    int ret;
    u8 *buffer, *alignbuffer;
    unsigned long absize;

    absize = keylen + alignmask;
    buffer = kmalloc(absize, GFP_ATOMIC);
    if (!buffer)
        return -ENOMEM;

    alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
    memcpy(alignbuffer, key, keylen);
    ret = cipher->setkey(tfm, alignbuffer, keylen);
    memset(alignbuffer, 0, keylen);
    kfree(buffer);
    return ret;
}

static int setkey(struct crypto_ablkcipher *tfm, const u8 *key,
          unsigned int keylen)
{
    struct ablkcipher_alg *cipher = crypto_ablkcipher_alg(tfm);
    unsigned long alignmask = crypto_ablkcipher_alignmask(tfm);

    if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
        crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
        return -EINVAL;
    }

    if ((unsigned long)key & alignmask)
        return setkey_unaligned(tfm, key, keylen);

    return cipher->setkey(tfm, key, keylen);
}

static unsigned int crypto_ablkcipher_ctxsize(struct crypto_alg *alg, u32 type,
                          u32 mask)
{
    return alg->cra_ctxsize;
}

int skcipher_null_givencrypt(struct skcipher_givcrypt_request *req)
{
    return crypto_ablkcipher_encrypt(&req->creq);
}

int skcipher_null_givdecrypt(struct skcipher_givcrypt_request *req)
{
    return crypto_ablkcipher_decrypt(&req->creq);
}

static int crypto_init_ablkcipher_ops(struct crypto_tfm *tfm, u32 type,
                      u32 mask)
{
    struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
    struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;

    if (alg->ivsize > PAGE_SIZE / 8)
        return -EINVAL;

    crt->setkey = setkey;
    crt->encrypt = alg->encrypt;
    crt->decrypt = alg->decrypt;
    if (!alg->ivsize) {
        crt->givencrypt = skcipher_null_givencrypt;
        crt->givdecrypt = skcipher_null_givdecrypt;
    }
    crt->base = __crypto_ablkcipher_cast(tfm);
    crt->ivsize = alg->ivsize;

    return 0;
}

#ifdef CONFIG_NET
static int crypto_ablkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
    struct crypto_report_blkcipher rblkcipher;

    snprintf(rblkcipher.type, CRYPTO_MAX_ALG_NAME, "%s", "ablkcipher");
    snprintf(rblkcipher.geniv, CRYPTO_MAX_ALG_NAME, "%s",
         alg->cra_ablkcipher.geniv ?: "<default>");

    rblkcipher.blocksize = alg->cra_blocksize;
    rblkcipher.min_keysize = alg->cra_ablkcipher.min_keysize;
    rblkcipher.max_keysize = alg->cra_ablkcipher.max_keysize;
    rblkcipher.ivsize = alg->cra_ablkcipher.ivsize;

    if (nla_put(skb, CRYPTOCFGA_REPORT_BLKCIPHER,
            sizeof(struct crypto_report_blkcipher), &rblkcipher))
        goto nla_put_failure;
    return 0;

nla_put_failure:
    return -EMSGSIZE;
}
#else
static int crypto_ablkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
    return -ENOSYS;
}
#endif

static void crypto_ablkcipher_show(struct seq_file *m, struct crypto_alg *alg)
    __attribute__ ((unused));
static void crypto_ablkcipher_show(struct seq_file *m, struct crypto_alg *alg)
{
    struct ablkcipher_alg *ablkcipher = &alg->cra_ablkcipher;

    seq_printf(m, "type         : ablkcipher\n");
    seq_printf(m, "async        : %s\n", alg->cra_flags & CRYPTO_ALG_ASYNC ?
                         "yes" : "no");
    seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
    seq_printf(m, "min keysize  : %u\n", ablkcipher->min_keysize);
    seq_printf(m, "max keysize  : %u\n", ablkcipher->max_keysize);
    seq_printf(m, "ivsize       : %u\n", ablkcipher->ivsize);
    seq_printf(m, "geniv        : %s\n", ablkcipher->geniv ?: "<default>");
}

const struct crypto_type crypto_ablkcipher_type = {
    .ctxsize = crypto_ablkcipher_ctxsize,
    .init = crypto_init_ablkcipher_ops,
#ifdef CONFIG_PROC_FS
    .show = crypto_ablkcipher_show,
#endif
    .report = crypto_ablkcipher_report,
};
EXPORT_SYMBOL_GPL(crypto_ablkcipher_type);

static int no_givdecrypt(struct skcipher_givcrypt_request *req)
{
    return -ENOSYS;
}

static int crypto_init_givcipher_ops(struct crypto_tfm *tfm, u32 type,
                      u32 mask)
{
    struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
    struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;

    if (alg->ivsize > PAGE_SIZE / 8)
        return -EINVAL;

    crt->setkey = tfm->__crt_alg->cra_flags & CRYPTO_ALG_GENIV ?
              alg->setkey : setkey;
    crt->encrypt = alg->encrypt;
    crt->decrypt = alg->decrypt;
    crt->givencrypt = alg->givencrypt;
    crt->givdecrypt = alg->givdecrypt ?: no_givdecrypt;
    crt->base = __crypto_ablkcipher_cast(tfm);
    crt->ivsize = alg->ivsize;

    return 0;
}

#ifdef CONFIG_NET
static int crypto_givcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
    struct crypto_report_blkcipher rblkcipher;

    snprintf(rblkcipher.type, CRYPTO_MAX_ALG_NAME, "%s", "givcipher");
    snprintf(rblkcipher.geniv, CRYPTO_MAX_ALG_NAME, "%s",
         alg->cra_ablkcipher.geniv ?: "<built-in>");

    rblkcipher.blocksize = alg->cra_blocksize;
    rblkcipher.min_keysize = alg->cra_ablkcipher.min_keysize;
    rblkcipher.max_keysize = alg->cra_ablkcipher.max_keysize;
    rblkcipher.ivsize = alg->cra_ablkcipher.ivsize;

    if (nla_put(skb, CRYPTOCFGA_REPORT_BLKCIPHER,
            sizeof(struct crypto_report_blkcipher), &rblkcipher))
        goto nla_put_failure;
    return 0;

nla_put_failure:
    return -EMSGSIZE;
}
#else
static int crypto_givcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
    return -ENOSYS;
}
#endif

static void crypto_givcipher_show(struct seq_file *m, struct crypto_alg *alg)
    __attribute__ ((unused));
static void crypto_givcipher_show(struct seq_file *m, struct crypto_alg *alg)
{
    struct ablkcipher_alg *ablkcipher = &alg->cra_ablkcipher;

    seq_printf(m, "type         : givcipher\n");
    seq_printf(m, "async        : %s\n", alg->cra_flags & CRYPTO_ALG_ASYNC ?
                         "yes" : "no");
    seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
    seq_printf(m, "min keysize  : %u\n", ablkcipher->min_keysize);
    seq_printf(m, "max keysize  : %u\n", ablkcipher->max_keysize);
    seq_printf(m, "ivsize       : %u\n", ablkcipher->ivsize);
    seq_printf(m, "geniv        : %s\n", ablkcipher->geniv ?: "<built-in>");
}

const struct crypto_type crypto_givcipher_type = {
    .ctxsize = crypto_ablkcipher_ctxsize,
    .init = crypto_init_givcipher_ops,
#ifdef CONFIG_PROC_FS
    .show = crypto_givcipher_show,
#endif
    .report = crypto_givcipher_report,
};
EXPORT_SYMBOL_GPL(crypto_givcipher_type);

const char *crypto_default_geniv(const struct crypto_alg *alg)
{
    if (((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
         CRYPTO_ALG_TYPE_BLKCIPHER ? alg->cra_blkcipher.ivsize :
                     alg->cra_ablkcipher.ivsize) !=
        alg->cra_blocksize)
        return "chainiv";

    return alg->cra_flags & CRYPTO_ALG_ASYNC ?
           "eseqiv" : skcipher_default_geniv;
}

static int crypto_givcipher_default(struct crypto_alg *alg, u32 type, u32 mask)
{
    struct rtattr *tb[3];
    struct {
        struct rtattr attr;
        struct crypto_attr_type data;
    } ptype;
    struct {
        struct rtattr attr;
        struct crypto_attr_alg data;
    } palg;
    struct crypto_template *tmpl;
    struct crypto_instance *inst;
    struct crypto_alg *larval;
    const char *geniv;
    int err;

    larval = crypto_larval_lookup(alg->cra_driver_name,
                      (type & ~CRYPTO_ALG_TYPE_MASK) |
                      CRYPTO_ALG_TYPE_GIVCIPHER,
                      mask | CRYPTO_ALG_TYPE_MASK);
    err = PTR_ERR(larval);
    if (IS_ERR(larval))
        goto out;

    err = -EAGAIN;
    if (!crypto_is_larval(larval))
        goto drop_larval;

    ptype.attr.rta_len = sizeof(ptype);
    ptype.attr.rta_type = CRYPTOA_TYPE;
    ptype.data.type = type | CRYPTO_ALG_GENIV;
    /* GENIV tells the template that we're making a default geniv. */
    ptype.data.mask = mask | CRYPTO_ALG_GENIV;
    tb[0] = &ptype.attr;

    palg.attr.rta_len = sizeof(palg);
    palg.attr.rta_type = CRYPTOA_ALG;
    /* Must use the exact name to locate ourselves. */
    memcpy(palg.data.name, alg->cra_driver_name, CRYPTO_MAX_ALG_NAME);
    tb[1] = &palg.attr;

    tb[2] = NULL;

    if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
        CRYPTO_ALG_TYPE_BLKCIPHER)
        geniv = alg->cra_blkcipher.geniv;
    else
        geniv = alg->cra_ablkcipher.geniv;

    if (!geniv)
        geniv = crypto_default_geniv(alg);

    tmpl = crypto_lookup_template(geniv);
    err = -ENOENT;
    if (!tmpl)
        goto kill_larval;

    inst = tmpl->alloc(tb);
    err = PTR_ERR(inst);
    if (IS_ERR(inst))
        goto put_tmpl;

    if ((err = crypto_register_instance(tmpl, inst))) {
        tmpl->free(inst);
        goto put_tmpl;
    }

    /* Redo the lookup to use the instance we just registered. */
    err = -EAGAIN;

put_tmpl:
    crypto_tmpl_put(tmpl);
kill_larval:
    crypto_larval_kill(larval);
drop_larval:
    crypto_mod_put(larval);
out:
    crypto_mod_put(alg);
    return err;
}

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

    alg = crypto_alg_mod_lookup(name, type, mask);
    if (IS_ERR(alg))
        return alg;

    if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
        CRYPTO_ALG_TYPE_GIVCIPHER)
        return alg;

    if (!((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
          CRYPTO_ALG_TYPE_BLKCIPHER ? alg->cra_blkcipher.ivsize :
                      alg->cra_ablkcipher.ivsize))
        return alg;

    crypto_mod_put(alg);
    alg = crypto_alg_mod_lookup(name, type | CRYPTO_ALG_TESTED,
                    mask & ~CRYPTO_ALG_TESTED);
    if (IS_ERR(alg))
        return alg;

    if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
        CRYPTO_ALG_TYPE_GIVCIPHER) {
        if ((alg->cra_flags ^ type ^ ~mask) & CRYPTO_ALG_TESTED) {
            crypto_mod_put(alg);
            alg = ERR_PTR(-ENOENT);
        }
        return alg;
    }

    BUG_ON(!((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
         CRYPTO_ALG_TYPE_BLKCIPHER ? alg->cra_blkcipher.ivsize :
                         alg->cra_ablkcipher.ivsize));

    return ERR_PTR(crypto_givcipher_default(alg, type, mask));
}
EXPORT_SYMBOL_GPL(crypto_lookup_skcipher);

int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn, const char *name,
             u32 type, u32 mask)
{
    struct crypto_alg *alg;
    int err;

    type = crypto_skcipher_type(type);
    mask = crypto_skcipher_mask(mask);

    alg = crypto_lookup_skcipher(name, type, mask);
    if (IS_ERR(alg))
        return PTR_ERR(alg);

    err = crypto_init_spawn(&spawn->base, alg, spawn->base.inst, mask);
    crypto_mod_put(alg);
    return err;
}
EXPORT_SYMBOL_GPL(crypto_grab_skcipher);

struct crypto_ablkcipher *crypto_alloc_ablkcipher(const char *alg_name,
                          u32 type, u32 mask)
{
    struct crypto_tfm *tfm;
    int err;

    type = crypto_skcipher_type(type);
    mask = crypto_skcipher_mask(mask);

    for (;;) {
        struct crypto_alg *alg;

        alg = crypto_lookup_skcipher(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 __crypto_ablkcipher_cast(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_ablkcipher);

static int __init skcipher_module_init(void)
{
    skcipher_default_geniv = num_possible_cpus() > 1 ?
                 "eseqiv" : "chainiv";
    return 0;
}

static void skcipher_module_exit(void)
{
}

module_init(skcipher_module_init);
module_exit(skcipher_module_exit);