/*
 * pcrypt - Parallel crypto wrapper.
 *
 * Copyright (C) 2009 secunet Security Networks AG
 * Copyright (C) 2009 Steffen Klassert <steffen.klassert@secunet.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <crypto/algapi.h>
#include <crypto/internal/aead.h>
#include <linux/atomic.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/kobject.h>
#include <linux/cpu.h>
#include <crypto/pcrypt.h>

struct padata_pcrypt {
        struct padata_instance *pinst;
        struct workqueue_struct *wq;

        /*
         * Cpumask for callback CPUs. It should be
         * equal to serial cpumask of corresponding padata instance,
         * so it is updated when padata notifies us about serial
         * cpumask change.
         *
         * cb_cpumask is protected by RCU. This fact prevents us from
         * using cpumask_var_t directly because the actual type of
         * cpumsak_var_t depends on kernel configuration(particularly on
         * CONFIG_CPUMASK_OFFSTACK macro). Depending on the configuration
         * cpumask_var_t may be either a pointer to the struct cpumask
         * or a variable allocated on the stack. Thus we can not safely use
         * cpumask_var_t with RCU operations such as rcu_assign_pointer or
         * rcu_dereference. So cpumask_var_t is wrapped with struct
         * pcrypt_cpumask which makes possible to use it with RCU.
         */
        struct pcrypt_cpumask {
                cpumask_var_t mask;
        } *cb_cpumask;
        struct notifier_block nblock;
};

static struct padata_pcrypt pencrypt;
static struct padata_pcrypt pdecrypt;
static struct kset           *pcrypt_kset;

struct pcrypt_instance_ctx {
        struct crypto_aead_spawn spawn;
        atomic_t tfm_count;
};

struct pcrypt_aead_ctx {
        struct crypto_aead *child;
        unsigned int cb_cpu;
};

static int pcrypt_do_parallel(struct padata_priv *padata, unsigned int *cb_cpu,
                              struct padata_pcrypt *pcrypt)
{
        unsigned int cpu_index, cpu, i;
        struct pcrypt_cpumask *cpumask;

        cpu = *cb_cpu;

        rcu_read_lock_bh();
        cpumask = rcu_dereference_bh(pcrypt->cb_cpumask);
        if (cpumask_test_cpu(cpu, cpumask->mask))
                        goto out;

        if (!cpumask_weight(cpumask->mask))
                        goto out;

        cpu_index = cpu % cpumask_weight(cpumask->mask);

        cpu = cpumask_first(cpumask->mask);
        for (i = 0; i < cpu_index; i++)
                cpu = cpumask_next(cpu, cpumask->mask);

        *cb_cpu = cpu;

out:
        rcu_read_unlock_bh();
        return padata_do_parallel(pcrypt->pinst, padata, cpu);
}

static int pcrypt_aead_setkey(struct crypto_aead *parent,
                              const u8 *key, unsigned int keylen)
{
        struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(parent);

        return crypto_aead_setkey(ctx->child, key, keylen);
}

static int pcrypt_aead_setauthsize(struct crypto_aead *parent,
                                   unsigned int authsize)
{
        struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(parent);

        return crypto_aead_setauthsize(ctx->child, authsize);
}

static void pcrypt_aead_serial(struct padata_priv *padata)
{
        struct pcrypt_request *preq = pcrypt_padata_request(padata);
        struct aead_request *req = pcrypt_request_ctx(preq);

        aead_request_complete(req->base.data, padata->info);
}

static void pcrypt_aead_done(struct crypto_async_request *areq, int err)
{
        struct aead_request *req = areq->data;
        struct pcrypt_request *preq = aead_request_ctx(req);
        struct padata_priv *padata = pcrypt_request_padata(preq);

        padata->info = err;
        req->base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;

        padata_do_serial(padata);
}

static void pcrypt_aead_enc(struct padata_priv *padata)
{
        struct pcrypt_request *preq = pcrypt_padata_request(padata);
        struct aead_request *req = pcrypt_request_ctx(preq);

        padata->info = crypto_aead_encrypt(req);

        if (padata->info == -EINPROGRESS)
                return;

        padata_do_serial(padata);
}

static int pcrypt_aead_encrypt(struct aead_request *req)
{
        int err;
        struct pcrypt_request *preq = aead_request_ctx(req);
        struct aead_request *creq = pcrypt_request_ctx(preq);
        struct padata_priv *padata = pcrypt_request_padata(preq);
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(aead);
        u32 flags = aead_request_flags(req);

        memset(padata, 0, sizeof(struct padata_priv));

        padata->parallel = pcrypt_aead_enc;
        padata->serial = pcrypt_aead_serial;

        aead_request_set_tfm(creq, ctx->child);
        aead_request_set_callback(creq, flags & ~CRYPTO_TFM_REQ_MAY_SLEEP,
                                  pcrypt_aead_done, req);
        aead_request_set_crypt(creq, req->src, req->dst,
                               req->cryptlen, req->iv);
        aead_request_set_ad(creq, req->assoclen);

        err = pcrypt_do_parallel(padata, &ctx->cb_cpu, &pencrypt);
        if (!err)
                return -EINPROGRESS;

        return err;
}

static void pcrypt_aead_dec(struct padata_priv *padata)
{
        struct pcrypt_request *preq = pcrypt_padata_request(padata);
        struct aead_request *req = pcrypt_request_ctx(preq);

        padata->info = crypto_aead_decrypt(req);

        if (padata->info == -EINPROGRESS)
                return;

        padata_do_serial(padata);
}

static int pcrypt_aead_decrypt(struct aead_request *req)
{
        int err;
        struct pcrypt_request *preq = aead_request_ctx(req);
        struct aead_request *creq = pcrypt_request_ctx(preq);
        struct padata_priv *padata = pcrypt_request_padata(preq);
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(aead);
        u32 flags = aead_request_flags(req);

        memset(padata, 0, sizeof(struct padata_priv));

        padata->parallel = pcrypt_aead_dec;
        padata->serial = pcrypt_aead_serial;

        aead_request_set_tfm(creq, ctx->child);
        aead_request_set_callback(creq, flags & ~CRYPTO_TFM_REQ_MAY_SLEEP,
                                  pcrypt_aead_done, req);
        aead_request_set_crypt(creq, req->src, req->dst,
                               req->cryptlen, req->iv);
        aead_request_set_ad(creq, req->assoclen);

        err = pcrypt_do_parallel(padata, &ctx->cb_cpu, &pdecrypt);
        if (!err)
                return -EINPROGRESS;

        return err;
}

static int pcrypt_aead_init_tfm(struct crypto_aead *tfm)
{
        int cpu, cpu_index;
        struct aead_instance *inst = aead_alg_instance(tfm);
        struct pcrypt_instance_ctx *ictx = aead_instance_ctx(inst);
        struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(tfm);
        struct crypto_aead *cipher;

        cpu_index = (unsigned int)atomic_inc_return(&ictx->tfm_count) %
                    cpumask_weight(cpu_online_mask);

        ctx->cb_cpu = cpumask_first(cpu_online_mask);
        for (cpu = 0; cpu < cpu_index; cpu++)
                ctx->cb_cpu = cpumask_next(ctx->cb_cpu, cpu_online_mask);

        cipher = crypto_spawn_aead(&ictx->spawn);

        if (IS_ERR(cipher))
                return PTR_ERR(cipher);

        ctx->child = cipher;
        crypto_aead_set_reqsize(tfm, sizeof(struct pcrypt_request) +
                                     sizeof(struct aead_request) +
                                     crypto_aead_reqsize(cipher));

        return 0;
}

static void pcrypt_aead_exit_tfm(struct crypto_aead *tfm)
{
        struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(tfm);

        crypto_free_aead(ctx->child);
}

static void pcrypt_free(struct aead_instance *inst)
{
        struct pcrypt_instance_ctx *ctx = aead_instance_ctx(inst);

        crypto_drop_aead(&ctx->spawn);
        kfree(inst);
}

static int pcrypt_init_instance(struct crypto_instance *inst,
                                struct crypto_alg *alg)
{
        if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
                     "pcrypt(%s)", alg->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
                return -ENAMETOOLONG;

        memcpy(inst->alg.cra_name, alg->cra_name, CRYPTO_MAX_ALG_NAME);

        inst->alg.cra_priority = alg->cra_priority + 100;
        inst->alg.cra_blocksize = alg->cra_blocksize;
        inst->alg.cra_alignmask = alg->cra_alignmask;

        return 0;
}

static int pcrypt_create_aead(struct crypto_template *tmpl, struct rtattr **tb,
                              u32 type, u32 mask)
{
        struct pcrypt_instance_ctx *ctx;
        struct crypto_attr_type *algt;
        struct aead_instance *inst;
        struct aead_alg *alg;
        const char *name;
        int err;

        algt = crypto_get_attr_type(tb);
        if (IS_ERR(algt))
                return PTR_ERR(algt);

        name = crypto_attr_alg_name(tb[1]);
        if (IS_ERR(name))
                return PTR_ERR(name);

        inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
        if (!inst)
                return -ENOMEM;

        ctx = aead_instance_ctx(inst);
        crypto_set_aead_spawn(&ctx->spawn, aead_crypto_instance(inst));

        err = crypto_grab_aead(&ctx->spawn, name, 0, 0);
        if (err)
                goto out_free_inst;

        alg = crypto_spawn_aead_alg(&ctx->spawn);
        err = pcrypt_init_instance(aead_crypto_instance(inst), &alg->base);
        if (err)
                goto out_drop_aead;

        inst->alg.base.cra_flags = CRYPTO_ALG_ASYNC;

        inst->alg.ivsize = crypto_aead_alg_ivsize(alg);
        inst->alg.maxauthsize = crypto_aead_alg_maxauthsize(alg);

        inst->alg.base.cra_ctxsize = sizeof(struct pcrypt_aead_ctx);

        inst->alg.init = pcrypt_aead_init_tfm;
        inst->alg.exit = pcrypt_aead_exit_tfm;

        inst->alg.setkey = pcrypt_aead_setkey;
        inst->alg.setauthsize = pcrypt_aead_setauthsize;
        inst->alg.encrypt = pcrypt_aead_encrypt;
        inst->alg.decrypt = pcrypt_aead_decrypt;

        inst->free = pcrypt_free;

        err = aead_register_instance(tmpl, inst);
        if (err)
                goto out_drop_aead;

out:
        return err;

out_drop_aead:
        crypto_drop_aead(&ctx->spawn);
out_free_inst:
        kfree(inst);
        goto out;
}

static int pcrypt_create(struct crypto_template *tmpl, struct rtattr **tb)
{
        struct crypto_attr_type *algt;

        algt = crypto_get_attr_type(tb);
        if (IS_ERR(algt))
                return PTR_ERR(algt);

        switch (algt->type & algt->mask & CRYPTO_ALG_TYPE_MASK) {
        case CRYPTO_ALG_TYPE_AEAD:
                return pcrypt_create_aead(tmpl, tb, algt->type, algt->mask);
        }

        return -EINVAL;
}

static int pcrypt_cpumask_change_notify(struct notifier_block *self,
                                        unsigned long val, void *data)
{
        struct padata_pcrypt *pcrypt;
        struct pcrypt_cpumask *new_mask, *old_mask;
        struct padata_cpumask *cpumask = (struct padata_cpumask *)data;

        if (!(val & PADATA_CPU_SERIAL))
                return 0;

        pcrypt = container_of(self, struct padata_pcrypt, nblock);
        new_mask = kmalloc(sizeof(*new_mask), GFP_KERNEL);
        if (!new_mask)
                return -ENOMEM;
        if (!alloc_cpumask_var(&new_mask->mask, GFP_KERNEL)) {
                kfree(new_mask);
                return -ENOMEM;
        }

        old_mask = pcrypt->cb_cpumask;

        cpumask_copy(new_mask->mask, cpumask->cbcpu);
        rcu_assign_pointer(pcrypt->cb_cpumask, new_mask);
        synchronize_rcu_bh();

        free_cpumask_var(old_mask->mask);
        kfree(old_mask);
        return 0;
}

static int pcrypt_sysfs_add(struct padata_instance *pinst, const char *name)
{
        int ret;

        pinst->kobj.kset = pcrypt_kset;
        ret = kobject_add(&pinst->kobj, NULL, name);
        if (!ret)
                kobject_uevent(&pinst->kobj, KOBJ_ADD);

        return ret;
}

static int pcrypt_init_padata(struct padata_pcrypt *pcrypt,
                              const char *name)
{
        int ret = -ENOMEM;
        struct pcrypt_cpumask *mask;

        get_online_cpus();

        pcrypt->wq = alloc_workqueue("%s", WQ_MEM_RECLAIM | WQ_CPU_INTENSIVE,
                                     1, name);
        if (!pcrypt->wq)
                goto err;

        pcrypt->pinst = padata_alloc_possible(pcrypt->wq);
        if (!pcrypt->pinst)
                goto err_destroy_workqueue;

        mask = kmalloc(sizeof(*mask), GFP_KERNEL);
        if (!mask)
                goto err_free_padata;
        if (!alloc_cpumask_var(&mask->mask, GFP_KERNEL)) {
                kfree(mask);
                goto err_free_padata;
        }

        cpumask_and(mask->mask, cpu_possible_mask, cpu_online_mask);
        rcu_assign_pointer(pcrypt->cb_cpumask, mask);

        pcrypt->nblock.notifier_call = pcrypt_cpumask_change_notify;
        ret = padata_register_cpumask_notifier(pcrypt->pinst, &pcrypt->nblock);
        if (ret)
                goto err_free_cpumask;

        ret = pcrypt_sysfs_add(pcrypt->pinst, name);
        if (ret)
                goto err_unregister_notifier;

        put_online_cpus();

        return ret;

err_unregister_notifier:
        padata_unregister_cpumask_notifier(pcrypt->pinst, &pcrypt->nblock);
err_free_cpumask:
        free_cpumask_var(mask->mask);
        kfree(mask);
err_free_padata:
        padata_free(pcrypt->pinst);
err_destroy_workqueue:
        destroy_workqueue(pcrypt->wq);
err:
        put_online_cpus();

        return ret;
}

static void pcrypt_fini_padata(struct padata_pcrypt *pcrypt)
{
        free_cpumask_var(pcrypt->cb_cpumask->mask);
        kfree(pcrypt->cb_cpumask);

        padata_stop(pcrypt->pinst);
        padata_unregister_cpumask_notifier(pcrypt->pinst, &pcrypt->nblock);
        destroy_workqueue(pcrypt->wq);
        padata_free(pcrypt->pinst);
}

static struct crypto_template pcrypt_tmpl = {
        .name = "pcrypt",
        .create = pcrypt_create,
        .module = THIS_MODULE,
};

static int __init pcrypt_init(void)
{
        int err = -ENOMEM;

        pcrypt_kset = kset_create_and_add("pcrypt", NULL, kernel_kobj);
        if (!pcrypt_kset)
                goto err;

        err = pcrypt_init_padata(&pencrypt, "pencrypt");
        if (err)
                goto err_unreg_kset;

        err = pcrypt_init_padata(&pdecrypt, "pdecrypt");
        if (err)
                goto err_deinit_pencrypt;

        padata_start(pencrypt.pinst);
        padata_start(pdecrypt.pinst);

        return crypto_register_template(&pcrypt_tmpl);

err_deinit_pencrypt:
        pcrypt_fini_padata(&pencrypt);
err_unreg_kset:
        kset_unregister(pcrypt_kset);
err:
        return err;
}

static void __exit pcrypt_exit(void)
{
        pcrypt_fini_padata(&pencrypt);
        pcrypt_fini_padata(&pdecrypt);

        kset_unregister(pcrypt_kset);
        crypto_unregister_template(&pcrypt_tmpl);
}

module_init(pcrypt_init);
module_exit(pcrypt_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
MODULE_DESCRIPTION("Parallel crypto wrapper");
MODULE_ALIAS_CRYPTO("pcrypt");