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cryptd.c

/*
 * Software async crypto daemon.
 *
 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * 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/algapi.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/scatterlist.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#define CRYPTD_MAX_QLEN 100

struct cryptd_state {
      spinlock_t lock;
      struct mutex mutex;
      struct crypto_queue queue;
      struct task_struct *task;
};

struct cryptd_instance_ctx {
      struct crypto_spawn spawn;
      struct cryptd_state *state;
};

struct cryptd_blkcipher_ctx {
      struct crypto_blkcipher *child;
};

struct cryptd_blkcipher_request_ctx {
      crypto_completion_t complete;
};


static inline struct cryptd_state *cryptd_get_state(struct crypto_tfm *tfm)
{
      struct crypto_instance *inst = crypto_tfm_alg_instance(tfm);
      struct cryptd_instance_ctx *ictx = crypto_instance_ctx(inst);
      return ictx->state;
}

static int cryptd_blkcipher_setkey(struct crypto_ablkcipher *parent,
                           const u8 *key, unsigned int keylen)
{
      struct cryptd_blkcipher_ctx *ctx = crypto_ablkcipher_ctx(parent);
      struct crypto_blkcipher *child = ctx->child;
      int err;

      crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
      crypto_blkcipher_set_flags(child, crypto_ablkcipher_get_flags(parent) &
                                CRYPTO_TFM_REQ_MASK);
      err = crypto_blkcipher_setkey(child, key, keylen);
      crypto_ablkcipher_set_flags(parent, crypto_blkcipher_get_flags(child) &
                                  CRYPTO_TFM_RES_MASK);
      return err;
}

static void cryptd_blkcipher_crypt(struct ablkcipher_request *req,
                           struct crypto_blkcipher *child,
                           int err,
                           int (*crypt)(struct blkcipher_desc *desc,
                                    struct scatterlist *dst,
                                    struct scatterlist *src,
                                    unsigned int len))
{
      struct cryptd_blkcipher_request_ctx *rctx;
      struct blkcipher_desc desc;

      rctx = ablkcipher_request_ctx(req);

      if (unlikely(err == -EINPROGRESS)) {
            rctx->complete(&req->base, err);
            return;
      }

      desc.tfm = child;
      desc.info = req->info;
      desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;

      err = crypt(&desc, req->dst, req->src, req->nbytes);

      req->base.complete = rctx->complete;

      local_bh_disable();
      req->base.complete(&req->base, err);
      local_bh_enable();
}

static void cryptd_blkcipher_encrypt(struct crypto_async_request *req, int err)
{
      struct cryptd_blkcipher_ctx *ctx = crypto_tfm_ctx(req->tfm);
      struct crypto_blkcipher *child = ctx->child;

      cryptd_blkcipher_crypt(ablkcipher_request_cast(req), child, err,
                         crypto_blkcipher_crt(child)->encrypt);
}

static void cryptd_blkcipher_decrypt(struct crypto_async_request *req, int err)
{
      struct cryptd_blkcipher_ctx *ctx = crypto_tfm_ctx(req->tfm);
      struct crypto_blkcipher *child = ctx->child;

      cryptd_blkcipher_crypt(ablkcipher_request_cast(req), child, err,
                         crypto_blkcipher_crt(child)->decrypt);
}

static int cryptd_blkcipher_enqueue(struct ablkcipher_request *req,
                            crypto_completion_t complete)
{
      struct cryptd_blkcipher_request_ctx *rctx = ablkcipher_request_ctx(req);
      struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
      struct cryptd_state *state =
            cryptd_get_state(crypto_ablkcipher_tfm(tfm));
      int err;

      rctx->complete = req->base.complete;
      req->base.complete = complete;

      spin_lock_bh(&state->lock);
      err = ablkcipher_enqueue_request(&state->queue, req);
      spin_unlock_bh(&state->lock);

      wake_up_process(state->task);
      return err;
}

static int cryptd_blkcipher_encrypt_enqueue(struct ablkcipher_request *req)
{
      return cryptd_blkcipher_enqueue(req, cryptd_blkcipher_encrypt);
}

static int cryptd_blkcipher_decrypt_enqueue(struct ablkcipher_request *req)
{
      return cryptd_blkcipher_enqueue(req, cryptd_blkcipher_decrypt);
}

static int cryptd_blkcipher_init_tfm(struct crypto_tfm *tfm)
{
      struct crypto_instance *inst = crypto_tfm_alg_instance(tfm);
      struct cryptd_instance_ctx *ictx = crypto_instance_ctx(inst);
      struct crypto_spawn *spawn = &ictx->spawn;
      struct cryptd_blkcipher_ctx *ctx = crypto_tfm_ctx(tfm);
      struct crypto_blkcipher *cipher;

      cipher = crypto_spawn_blkcipher(spawn);
      if (IS_ERR(cipher))
            return PTR_ERR(cipher);

      ctx->child = cipher;
      tfm->crt_ablkcipher.reqsize =
            sizeof(struct cryptd_blkcipher_request_ctx);
      return 0;
}

static void cryptd_blkcipher_exit_tfm(struct crypto_tfm *tfm)
{
      struct cryptd_blkcipher_ctx *ctx = crypto_tfm_ctx(tfm);
      struct cryptd_state *state = cryptd_get_state(tfm);
      int active;

      mutex_lock(&state->mutex);
      active = ablkcipher_tfm_in_queue(&state->queue,
                               __crypto_ablkcipher_cast(tfm));
      mutex_unlock(&state->mutex);

      BUG_ON(active);

      crypto_free_blkcipher(ctx->child);
}

static struct crypto_instance *cryptd_alloc_instance(struct crypto_alg *alg,
                                         struct cryptd_state *state)
{
      struct crypto_instance *inst;
      struct cryptd_instance_ctx *ctx;
      int err;

      inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
      if (IS_ERR(inst))
            goto out;

      err = -ENAMETOOLONG;
      if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
                 "cryptd(%s)", alg->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
            goto out_free_inst;

      ctx = crypto_instance_ctx(inst);
      err = crypto_init_spawn(&ctx->spawn, alg, inst,
                        CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
      if (err)
            goto out_free_inst;

      ctx->state = state;

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

      inst->alg.cra_priority = alg->cra_priority + 50;
      inst->alg.cra_blocksize = alg->cra_blocksize;
      inst->alg.cra_alignmask = alg->cra_alignmask;

out:
      return inst;

out_free_inst:
      kfree(inst);
      inst = ERR_PTR(err);
      goto out;
}

static struct crypto_instance *cryptd_alloc_blkcipher(
      struct rtattr **tb, struct cryptd_state *state)
{
      struct crypto_instance *inst;
      struct crypto_alg *alg;

      alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_BLKCIPHER,
                          CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
      if (IS_ERR(alg))
            return ERR_PTR(PTR_ERR(alg));

      inst = cryptd_alloc_instance(alg, state);
      if (IS_ERR(inst))
            goto out_put_alg;

      inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_ASYNC;
      inst->alg.cra_type = &crypto_ablkcipher_type;

      inst->alg.cra_ablkcipher.ivsize = alg->cra_blkcipher.ivsize;
      inst->alg.cra_ablkcipher.min_keysize = alg->cra_blkcipher.min_keysize;
      inst->alg.cra_ablkcipher.max_keysize = alg->cra_blkcipher.max_keysize;

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

      inst->alg.cra_init = cryptd_blkcipher_init_tfm;
      inst->alg.cra_exit = cryptd_blkcipher_exit_tfm;

      inst->alg.cra_ablkcipher.setkey = cryptd_blkcipher_setkey;
      inst->alg.cra_ablkcipher.encrypt = cryptd_blkcipher_encrypt_enqueue;
      inst->alg.cra_ablkcipher.decrypt = cryptd_blkcipher_decrypt_enqueue;

out_put_alg:
      crypto_mod_put(alg);
      return inst;
}

static struct cryptd_state state;

static struct crypto_instance *cryptd_alloc(struct rtattr **tb)
{
      struct crypto_attr_type *algt;

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

      switch (algt->type & algt->mask & CRYPTO_ALG_TYPE_MASK) {
      case CRYPTO_ALG_TYPE_BLKCIPHER:
            return cryptd_alloc_blkcipher(tb, &state);
      }

      return ERR_PTR(-EINVAL);
}

static void cryptd_free(struct crypto_instance *inst)
{
      struct cryptd_instance_ctx *ctx = crypto_instance_ctx(inst);

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

static struct crypto_template cryptd_tmpl = {
      .name = "cryptd",
      .alloc = cryptd_alloc,
      .free = cryptd_free,
      .module = THIS_MODULE,
};

static inline int cryptd_create_thread(struct cryptd_state *state,
                               int (*fn)(void *data), const char *name)
{
      spin_lock_init(&state->lock);
      mutex_init(&state->mutex);
      crypto_init_queue(&state->queue, CRYPTD_MAX_QLEN);

      state->task = kthread_run(fn, state, name);
      if (IS_ERR(state->task))
            return PTR_ERR(state->task);

      return 0;
}

static inline void cryptd_stop_thread(struct cryptd_state *state)
{
      BUG_ON(state->queue.qlen);
      kthread_stop(state->task);
}

static int cryptd_thread(void *data)
{
      struct cryptd_state *state = data;
      int stop;

      current->flags |= PF_NOFREEZE;

      do {
            struct crypto_async_request *req, *backlog;

            mutex_lock(&state->mutex);
            __set_current_state(TASK_INTERRUPTIBLE);

            spin_lock_bh(&state->lock);
            backlog = crypto_get_backlog(&state->queue);
            req = crypto_dequeue_request(&state->queue);
            spin_unlock_bh(&state->lock);

            stop = kthread_should_stop();

            if (stop || req) {
                  __set_current_state(TASK_RUNNING);
                  if (req) {
                        if (backlog)
                              backlog->complete(backlog,
                                            -EINPROGRESS);
                        req->complete(req, 0);
                  }
            }

            mutex_unlock(&state->mutex);

            schedule();
      } while (!stop);

      return 0;
}

static int __init cryptd_init(void)
{
      int err;

      err = cryptd_create_thread(&state, cryptd_thread, "cryptd");
      if (err)
            return err;

      err = crypto_register_template(&cryptd_tmpl);
      if (err)
            kthread_stop(state.task);

      return err;
}

static void __exit cryptd_exit(void)
{
      cryptd_stop_thread(&state);
      crypto_unregister_template(&cryptd_tmpl);
}

module_init(cryptd_init);
module_exit(cryptd_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Software async crypto daemon");

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