root/crypto/chainiv.c

DEFINITIONS

1. chainiv_givencrypt
2. chainiv_givencrypt_first
3. chainiv_init_common
4. chainiv_init
5. async_chainiv_schedule_work
6. async_chainiv_postpone_request
7. async_chainiv_givencrypt_tail
8. async_chainiv_givencrypt
9. async_chainiv_givencrypt_first
10. async_chainiv_do_postponed
11. async_chainiv_init
12. async_chainiv_exit
13. chainiv_alloc
14. chainiv_free
15. chainiv_module_init
16. chainiv_module_exit

/*
 * chainiv: Chain IV Generator
 *
 * Generate IVs simply be using the last block of the previous encryption.
 * This is mainly useful for CBC with a synchronous algorithm.
 *
 * Copyright (c) 2007 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/internal/skcipher.h>
#include <crypto/rng.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/workqueue.h>

enum {
        CHAINIV_STATE_INUSE = 0,
};

struct chainiv_ctx {
        spinlock_t lock;
        char iv[];
};

struct async_chainiv_ctx {
        unsigned long state;

        spinlock_t lock;
        int err;

        struct crypto_queue queue;
        struct work_struct postponed;

        char iv[];
};

static int chainiv_givencrypt(struct skcipher_givcrypt_request *req)
{
        struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
        struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
        struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
        unsigned int ivsize;
        int err;

        ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
        ablkcipher_request_set_callback(subreq, req->creq.base.flags &
                                                ~CRYPTO_TFM_REQ_MAY_SLEEP,
                                        req->creq.base.complete,
                                        req->creq.base.data);
        ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
                                     req->creq.nbytes, req->creq.info);

        spin_lock_bh(&ctx->lock);

        ivsize = crypto_ablkcipher_ivsize(geniv);

        memcpy(req->giv, ctx->iv, ivsize);
        memcpy(subreq->info, ctx->iv, ivsize);

        err = crypto_ablkcipher_encrypt(subreq);
        if (err)
                goto unlock;

        memcpy(ctx->iv, subreq->info, ivsize);

unlock:
        spin_unlock_bh(&ctx->lock);

        return err;
}

static int chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
{
        struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
        struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
        int err = 0;

        spin_lock_bh(&ctx->lock);
        if (crypto_ablkcipher_crt(geniv)->givencrypt !=
            chainiv_givencrypt_first)
                goto unlock;

        crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt;
        err = crypto_rng_get_bytes(crypto_default_rng, ctx->iv,
                                   crypto_ablkcipher_ivsize(geniv));

unlock:
        spin_unlock_bh(&ctx->lock);

        if (err)
                return err;

        return chainiv_givencrypt(req);
}

static int chainiv_init_common(struct crypto_tfm *tfm)
{
        tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);

        return skcipher_geniv_init(tfm);
}

static int chainiv_init(struct crypto_tfm *tfm)
{
        struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);

        spin_lock_init(&ctx->lock);

        return chainiv_init_common(tfm);
}

static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
{
        int queued;
        int err = ctx->err;

        if (!ctx->queue.qlen) {
                smp_mb__before_clear_bit();
                clear_bit(CHAINIV_STATE_INUSE, &ctx->state);

                if (!ctx->queue.qlen ||
                    test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
                        goto out;
        }

        queued = schedule_work(&ctx->postponed);
        BUG_ON(!queued);

out:
        return err;
}

static int async_chainiv_postpone_request(struct skcipher_givcrypt_request *req)
{
        struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
        struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
        int err;

        spin_lock_bh(&ctx->lock);
        err = skcipher_enqueue_givcrypt(&ctx->queue, req);
        spin_unlock_bh(&ctx->lock);

        if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
                return err;

        ctx->err = err;
        return async_chainiv_schedule_work(ctx);
}

static int async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request *req)
{
        struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
        struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
        struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
        unsigned int ivsize = crypto_ablkcipher_ivsize(geniv);

        memcpy(req->giv, ctx->iv, ivsize);
        memcpy(subreq->info, ctx->iv, ivsize);

        ctx->err = crypto_ablkcipher_encrypt(subreq);
        if (ctx->err)
                goto out;

        memcpy(ctx->iv, subreq->info, ivsize);

out:
        return async_chainiv_schedule_work(ctx);
}

static int async_chainiv_givencrypt(struct skcipher_givcrypt_request *req)
{
        struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
        struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
        struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);

        ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
        ablkcipher_request_set_callback(subreq, req->creq.base.flags,
                                        req->creq.base.complete,
                                        req->creq.base.data);
        ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
                                     req->creq.nbytes, req->creq.info);

        if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
                goto postpone;

        if (ctx->queue.qlen) {
                clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
                goto postpone;
        }

        return async_chainiv_givencrypt_tail(req);

postpone:
        return async_chainiv_postpone_request(req);
}

static int async_chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
{
        struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
        struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
        int err = 0;

        if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
                goto out;

        if (crypto_ablkcipher_crt(geniv)->givencrypt !=
            async_chainiv_givencrypt_first)
                goto unlock;

        crypto_ablkcipher_crt(geniv)->givencrypt = async_chainiv_givencrypt;
        err = crypto_rng_get_bytes(crypto_default_rng, ctx->iv,
                                   crypto_ablkcipher_ivsize(geniv));

unlock:
        clear_bit(CHAINIV_STATE_INUSE, &ctx->state);

        if (err)
                return err;

out:
        return async_chainiv_givencrypt(req);
}

static void async_chainiv_do_postponed(struct work_struct *work)
{
        struct async_chainiv_ctx *ctx = container_of(work,
                                                     struct async_chainiv_ctx,
                                                     postponed);
        struct skcipher_givcrypt_request *req;
        struct ablkcipher_request *subreq;
        int err;

        /* Only handle one request at a time to avoid hogging keventd. */
        spin_lock_bh(&ctx->lock);
        req = skcipher_dequeue_givcrypt(&ctx->queue);
        spin_unlock_bh(&ctx->lock);

        if (!req) {
                async_chainiv_schedule_work(ctx);
                return;
        }

        subreq = skcipher_givcrypt_reqctx(req);
        subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;

        err = async_chainiv_givencrypt_tail(req);

        local_bh_disable();
        skcipher_givcrypt_complete(req, err);
        local_bh_enable();
}

static int async_chainiv_init(struct crypto_tfm *tfm)
{
        struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);

        spin_lock_init(&ctx->lock);

        crypto_init_queue(&ctx->queue, 100);
        INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);

        return chainiv_init_common(tfm);
}

static void async_chainiv_exit(struct crypto_tfm *tfm)
{
        struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);

        BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);

        skcipher_geniv_exit(tfm);
}

static struct crypto_template chainiv_tmpl;

static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
{
        struct crypto_attr_type *algt;
        struct crypto_instance *inst;
        int err;

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

        err = crypto_get_default_rng();
        if (err)
                return ERR_PTR(err);

        inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0);
        if (IS_ERR(inst))
                goto put_rng;

        inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt_first;

        inst->alg.cra_init = chainiv_init;
        inst->alg.cra_exit = skcipher_geniv_exit;

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

        if (!crypto_requires_sync(algt->type, algt->mask)) {
                inst->alg.cra_flags |= CRYPTO_ALG_ASYNC;

                inst->alg.cra_ablkcipher.givencrypt =
                        async_chainiv_givencrypt_first;

                inst->alg.cra_init = async_chainiv_init;
                inst->alg.cra_exit = async_chainiv_exit;

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

        inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;

out:
        return inst;

put_rng:
        crypto_put_default_rng();
        goto out;
}

static void chainiv_free(struct crypto_instance *inst)
{
        skcipher_geniv_free(inst);
        crypto_put_default_rng();
}

static struct crypto_template chainiv_tmpl = {
        .name = "chainiv",
        .alloc = chainiv_alloc,
        .free = chainiv_free,
        .module = THIS_MODULE,
};

static int __init chainiv_module_init(void)
{
        return crypto_register_template(&chainiv_tmpl);
}

static void chainiv_module_exit(void)
{
        crypto_unregister_template(&chainiv_tmpl);
}

module_init(chainiv_module_init);
module_exit(chainiv_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Chain IV Generator");