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![Herbert Xu](/assets/img/avatar_default.png)
The RNG may not be available during early boot, e.g., the relevant modules may not be included in the initramfs. As the RNG Is only needed for IPsec, we should not let this prevent use of ciphers without IV generators, e.g., for disk encryption. This patch postpones the RNG allocation to the init function so that one failure during early boot does not make the RNG unavailable for all subsequent users of the same cipher. More importantly, it lets the cipher live even if RNG allocation fails. Of course we no longer offer IV generation and which will fail with an error if invoked. But all other cipher capabilities will function as usual. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
317 lines
7.6 KiB
C
317 lines
7.6 KiB
C
/*
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* chainiv: Chain IV Generator
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*
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* Generate IVs simply be using the last block of the previous encryption.
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* This is mainly useful for CBC with a synchronous algorithm.
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*
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* Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <crypto/internal/skcipher.h>
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#include <crypto/rng.h>
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#include <crypto/crypto_wq.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/workqueue.h>
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enum {
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CHAINIV_STATE_INUSE = 0,
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};
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struct chainiv_ctx {
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spinlock_t lock;
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char iv[];
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};
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struct async_chainiv_ctx {
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unsigned long state;
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spinlock_t lock;
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int err;
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struct crypto_queue queue;
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struct work_struct postponed;
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char iv[];
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};
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static int chainiv_givencrypt(struct skcipher_givcrypt_request *req)
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{
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struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
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struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
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struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
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unsigned int ivsize;
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int err;
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ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
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ablkcipher_request_set_callback(subreq, req->creq.base.flags &
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~CRYPTO_TFM_REQ_MAY_SLEEP,
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req->creq.base.complete,
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req->creq.base.data);
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ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
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req->creq.nbytes, req->creq.info);
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spin_lock_bh(&ctx->lock);
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ivsize = crypto_ablkcipher_ivsize(geniv);
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memcpy(req->giv, ctx->iv, ivsize);
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memcpy(subreq->info, ctx->iv, ivsize);
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err = crypto_ablkcipher_encrypt(subreq);
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if (err)
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goto unlock;
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memcpy(ctx->iv, subreq->info, ivsize);
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unlock:
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spin_unlock_bh(&ctx->lock);
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return err;
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}
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static int chainiv_init_common(struct crypto_tfm *tfm, char iv[])
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{
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struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
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int err = 0;
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tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
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if (iv) {
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err = crypto_rng_get_bytes(crypto_default_rng, iv,
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crypto_ablkcipher_ivsize(geniv));
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crypto_put_default_rng();
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}
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return err ?: skcipher_geniv_init(tfm);
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}
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static int chainiv_init(struct crypto_tfm *tfm)
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{
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struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
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struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
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char *iv;
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spin_lock_init(&ctx->lock);
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iv = NULL;
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if (!crypto_get_default_rng()) {
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crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt;
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iv = ctx->iv;
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}
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return chainiv_init_common(tfm, iv);
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}
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static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
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{
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int queued;
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int err = ctx->err;
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if (!ctx->queue.qlen) {
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smp_mb__before_atomic();
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clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
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if (!ctx->queue.qlen ||
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test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
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goto out;
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}
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queued = queue_work(kcrypto_wq, &ctx->postponed);
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BUG_ON(!queued);
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out:
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return err;
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}
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static int async_chainiv_postpone_request(struct skcipher_givcrypt_request *req)
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{
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struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
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struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
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int err;
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spin_lock_bh(&ctx->lock);
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err = skcipher_enqueue_givcrypt(&ctx->queue, req);
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spin_unlock_bh(&ctx->lock);
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if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
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return err;
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ctx->err = err;
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return async_chainiv_schedule_work(ctx);
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}
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static int async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request *req)
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{
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struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
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struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
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struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
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unsigned int ivsize = crypto_ablkcipher_ivsize(geniv);
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memcpy(req->giv, ctx->iv, ivsize);
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memcpy(subreq->info, ctx->iv, ivsize);
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ctx->err = crypto_ablkcipher_encrypt(subreq);
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if (ctx->err)
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goto out;
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memcpy(ctx->iv, subreq->info, ivsize);
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out:
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return async_chainiv_schedule_work(ctx);
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}
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static int async_chainiv_givencrypt(struct skcipher_givcrypt_request *req)
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{
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struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
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struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
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struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
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ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
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ablkcipher_request_set_callback(subreq, req->creq.base.flags,
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req->creq.base.complete,
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req->creq.base.data);
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ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
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req->creq.nbytes, req->creq.info);
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if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
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goto postpone;
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if (ctx->queue.qlen) {
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clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
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goto postpone;
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}
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return async_chainiv_givencrypt_tail(req);
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postpone:
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return async_chainiv_postpone_request(req);
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}
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static void async_chainiv_do_postponed(struct work_struct *work)
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{
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struct async_chainiv_ctx *ctx = container_of(work,
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struct async_chainiv_ctx,
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postponed);
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struct skcipher_givcrypt_request *req;
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struct ablkcipher_request *subreq;
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int err;
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/* Only handle one request at a time to avoid hogging keventd. */
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spin_lock_bh(&ctx->lock);
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req = skcipher_dequeue_givcrypt(&ctx->queue);
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spin_unlock_bh(&ctx->lock);
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if (!req) {
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async_chainiv_schedule_work(ctx);
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return;
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}
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subreq = skcipher_givcrypt_reqctx(req);
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subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
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err = async_chainiv_givencrypt_tail(req);
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local_bh_disable();
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skcipher_givcrypt_complete(req, err);
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local_bh_enable();
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}
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static int async_chainiv_init(struct crypto_tfm *tfm)
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{
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struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
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struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
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char *iv;
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spin_lock_init(&ctx->lock);
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crypto_init_queue(&ctx->queue, 100);
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INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);
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iv = NULL;
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if (!crypto_get_default_rng()) {
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crypto_ablkcipher_crt(geniv)->givencrypt =
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async_chainiv_givencrypt;
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iv = ctx->iv;
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}
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return chainiv_init_common(tfm, iv);
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}
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static void async_chainiv_exit(struct crypto_tfm *tfm)
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{
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struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
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BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);
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skcipher_geniv_exit(tfm);
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}
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static struct crypto_template chainiv_tmpl;
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static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
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{
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struct crypto_attr_type *algt;
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struct crypto_instance *inst;
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algt = crypto_get_attr_type(tb);
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if (IS_ERR(algt))
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return ERR_CAST(algt);
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inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0);
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if (IS_ERR(inst))
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goto out;
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inst->alg.cra_init = chainiv_init;
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inst->alg.cra_exit = skcipher_geniv_exit;
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inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx);
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if (!crypto_requires_sync(algt->type, algt->mask)) {
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inst->alg.cra_flags |= CRYPTO_ALG_ASYNC;
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inst->alg.cra_init = async_chainiv_init;
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inst->alg.cra_exit = async_chainiv_exit;
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inst->alg.cra_ctxsize = sizeof(struct async_chainiv_ctx);
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}
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inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
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out:
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return inst;
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}
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static struct crypto_template chainiv_tmpl = {
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.name = "chainiv",
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.alloc = chainiv_alloc,
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.free = skcipher_geniv_free,
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.module = THIS_MODULE,
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};
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static int __init chainiv_module_init(void)
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{
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return crypto_register_template(&chainiv_tmpl);
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}
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static void chainiv_module_exit(void)
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{
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crypto_unregister_template(&chainiv_tmpl);
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}
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module_init(chainiv_module_init);
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module_exit(chainiv_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Chain IV Generator");
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MODULE_ALIAS_CRYPTO("chainiv");
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