diff options
Diffstat (limited to 'crypto/chainiv.c')
-rw-r--r-- | crypto/chainiv.c | 362 |
1 files changed, 362 insertions, 0 deletions
diff --git a/crypto/chainiv.c b/crypto/chainiv.c new file mode 100644 index 00000000..ba200b07 --- /dev/null +++ b/crypto/chainiv.c @@ -0,0 +1,362 @@ +/* + * 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 <crypto/crypto_wq.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 = queue_work(kcrypto_wq, &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"); |