/* * 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_init_common(struct crypto_tfm *tfm, char iv[]) { struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); int err = 0; tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request); if (iv) { err = crypto_rng_get_bytes(crypto_default_rng, iv, crypto_ablkcipher_ivsize(geniv)); crypto_put_default_rng(); } return err ?: skcipher_geniv_init(tfm); } static int chainiv_init(struct crypto_tfm *tfm) { struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm); char *iv; spin_lock_init(&ctx->lock); iv = NULL; if (!crypto_get_default_rng()) { crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt; iv = ctx->iv; } return chainiv_init_common(tfm, iv); } static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx) { int queued; int err = ctx->err; if (!ctx->queue.qlen) { smp_mb__before_atomic(); 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 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 crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm); char *iv; spin_lock_init(&ctx->lock); crypto_init_queue(&ctx->queue, 100); INIT_WORK(&ctx->postponed, async_chainiv_do_postponed); iv = NULL; if (!crypto_get_default_rng()) { crypto_ablkcipher_crt(geniv)->givencrypt = async_chainiv_givencrypt; iv = ctx->iv; } return chainiv_init_common(tfm, iv); } 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; algt = crypto_get_attr_type(tb); if (IS_ERR(algt)) return ERR_CAST(algt); inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0); if (IS_ERR(inst)) goto out; 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_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; } static struct crypto_template chainiv_tmpl = { .name = "chainiv", .alloc = chainiv_alloc, .free = skcipher_geniv_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"); MODULE_ALIAS_CRYPTO("chainiv");