5311f248b7
As discussed previously, this patch moves the basic CTR functionality into a chainable algorithm called ctr. The IPsec-specific variant of it is now placed on top with the name rfc3686. So ctr(aes) gives a chainable cipher with IV size 16 while the IPsec variant will be called rfc3686(ctr(aes)). This patch also adjusts gcm accordingly. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
420 lines
11 KiB
C
420 lines
11 KiB
C
/*
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* CTR: Counter mode
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*
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* (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
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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/algapi.h>
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#include <crypto/ctr.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/random.h>
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#include <linux/scatterlist.h>
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#include <linux/slab.h>
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struct crypto_ctr_ctx {
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struct crypto_cipher *child;
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};
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struct crypto_rfc3686_ctx {
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struct crypto_blkcipher *child;
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u8 nonce[CTR_RFC3686_NONCE_SIZE];
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};
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static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
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unsigned int keylen)
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{
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struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
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struct crypto_cipher *child = ctx->child;
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int err;
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crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
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crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
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CRYPTO_TFM_REQ_MASK);
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err = crypto_cipher_setkey(child, key, keylen);
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crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
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CRYPTO_TFM_RES_MASK);
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return err;
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}
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static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
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struct crypto_cipher *tfm)
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{
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unsigned int bsize = crypto_cipher_blocksize(tfm);
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unsigned long alignmask = crypto_cipher_alignmask(tfm);
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u8 *ctrblk = walk->iv;
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u8 tmp[bsize + alignmask];
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u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
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u8 *src = walk->src.virt.addr;
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u8 *dst = walk->dst.virt.addr;
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unsigned int nbytes = walk->nbytes;
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crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
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crypto_xor(keystream, src, nbytes);
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memcpy(dst, keystream, nbytes);
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crypto_inc(ctrblk, bsize);
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}
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static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
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struct crypto_cipher *tfm)
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{
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
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crypto_cipher_alg(tfm)->cia_encrypt;
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unsigned int bsize = crypto_cipher_blocksize(tfm);
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u8 *ctrblk = walk->iv;
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u8 *src = walk->src.virt.addr;
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u8 *dst = walk->dst.virt.addr;
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unsigned int nbytes = walk->nbytes;
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do {
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/* create keystream */
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fn(crypto_cipher_tfm(tfm), dst, ctrblk);
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crypto_xor(dst, src, bsize);
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/* increment counter in counterblock */
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crypto_inc(ctrblk, bsize);
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src += bsize;
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dst += bsize;
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} while ((nbytes -= bsize) >= bsize);
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return nbytes;
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}
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static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
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struct crypto_cipher *tfm)
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{
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
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crypto_cipher_alg(tfm)->cia_encrypt;
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unsigned int bsize = crypto_cipher_blocksize(tfm);
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unsigned long alignmask = crypto_cipher_alignmask(tfm);
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unsigned int nbytes = walk->nbytes;
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u8 *ctrblk = walk->iv;
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u8 *src = walk->src.virt.addr;
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u8 tmp[bsize + alignmask];
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u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
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do {
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/* create keystream */
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fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
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crypto_xor(src, keystream, bsize);
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/* increment counter in counterblock */
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crypto_inc(ctrblk, bsize);
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src += bsize;
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} while ((nbytes -= bsize) >= bsize);
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return nbytes;
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}
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static int crypto_ctr_crypt(struct blkcipher_desc *desc,
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struct scatterlist *dst, struct scatterlist *src,
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unsigned int nbytes)
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{
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struct blkcipher_walk walk;
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struct crypto_blkcipher *tfm = desc->tfm;
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struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
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struct crypto_cipher *child = ctx->child;
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unsigned int bsize = crypto_cipher_blocksize(child);
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int err;
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blkcipher_walk_init(&walk, dst, src, nbytes);
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err = blkcipher_walk_virt_block(desc, &walk, bsize);
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while (walk.nbytes >= bsize) {
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if (walk.src.virt.addr == walk.dst.virt.addr)
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nbytes = crypto_ctr_crypt_inplace(&walk, child);
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else
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nbytes = crypto_ctr_crypt_segment(&walk, child);
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err = blkcipher_walk_done(desc, &walk, nbytes);
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}
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if (walk.nbytes) {
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crypto_ctr_crypt_final(&walk, child);
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err = blkcipher_walk_done(desc, &walk, 0);
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}
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return err;
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}
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static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
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{
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struct crypto_instance *inst = (void *)tfm->__crt_alg;
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struct crypto_spawn *spawn = crypto_instance_ctx(inst);
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struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
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struct crypto_cipher *cipher;
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cipher = crypto_spawn_cipher(spawn);
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if (IS_ERR(cipher))
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return PTR_ERR(cipher);
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ctx->child = cipher;
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return 0;
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}
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static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
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{
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struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
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crypto_free_cipher(ctx->child);
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}
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static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
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{
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struct crypto_instance *inst;
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struct crypto_alg *alg;
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int err;
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err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
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if (err)
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return ERR_PTR(err);
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alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
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CRYPTO_ALG_TYPE_MASK);
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if (IS_ERR(alg))
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return ERR_PTR(PTR_ERR(alg));
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/* Block size must be >= 4 bytes. */
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err = -EINVAL;
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if (alg->cra_blocksize < 4)
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goto out_put_alg;
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/* If this is false we'd fail the alignment of crypto_inc. */
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if (alg->cra_blocksize % 4)
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goto out_put_alg;
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inst = crypto_alloc_instance("ctr", alg);
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if (IS_ERR(inst))
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goto out;
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inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
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inst->alg.cra_priority = alg->cra_priority;
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inst->alg.cra_blocksize = 1;
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inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1);
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inst->alg.cra_type = &crypto_blkcipher_type;
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inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
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inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
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inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
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inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);
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inst->alg.cra_init = crypto_ctr_init_tfm;
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inst->alg.cra_exit = crypto_ctr_exit_tfm;
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inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
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inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
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inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
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out:
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crypto_mod_put(alg);
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return inst;
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out_put_alg:
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inst = ERR_PTR(err);
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goto out;
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}
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static void crypto_ctr_free(struct crypto_instance *inst)
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{
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crypto_drop_spawn(crypto_instance_ctx(inst));
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kfree(inst);
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}
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static struct crypto_template crypto_ctr_tmpl = {
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.name = "ctr",
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.alloc = crypto_ctr_alloc,
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.free = crypto_ctr_free,
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.module = THIS_MODULE,
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};
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static int crypto_rfc3686_setkey(struct crypto_tfm *parent, const u8 *key,
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unsigned int keylen)
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{
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struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(parent);
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struct crypto_blkcipher *child = ctx->child;
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int err;
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/* the nonce is stored in bytes at end of key */
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if (keylen < CTR_RFC3686_NONCE_SIZE)
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return -EINVAL;
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memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
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CTR_RFC3686_NONCE_SIZE);
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keylen -= CTR_RFC3686_NONCE_SIZE;
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crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
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crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) &
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CRYPTO_TFM_REQ_MASK);
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err = crypto_blkcipher_setkey(child, key, keylen);
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crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) &
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CRYPTO_TFM_RES_MASK);
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return err;
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}
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static int crypto_rfc3686_crypt(struct blkcipher_desc *desc,
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struct scatterlist *dst,
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struct scatterlist *src, unsigned int nbytes)
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{
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struct crypto_blkcipher *tfm = desc->tfm;
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struct crypto_rfc3686_ctx *ctx = crypto_blkcipher_ctx(tfm);
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struct crypto_blkcipher *child = ctx->child;
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unsigned long alignmask = crypto_blkcipher_alignmask(tfm);
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u8 ivblk[CTR_RFC3686_BLOCK_SIZE + alignmask];
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u8 *iv = PTR_ALIGN(ivblk + 0, alignmask + 1);
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u8 *info = desc->info;
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int err;
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/* set up counter block */
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memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
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memcpy(iv + CTR_RFC3686_NONCE_SIZE, info, CTR_RFC3686_IV_SIZE);
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/* initialize counter portion of counter block */
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*(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
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cpu_to_be32(1);
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desc->tfm = child;
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desc->info = iv;
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err = crypto_blkcipher_encrypt_iv(desc, dst, src, nbytes);
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desc->tfm = tfm;
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desc->info = info;
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return err;
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}
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static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm)
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{
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struct crypto_instance *inst = (void *)tfm->__crt_alg;
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struct crypto_spawn *spawn = crypto_instance_ctx(inst);
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struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
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struct crypto_blkcipher *cipher;
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cipher = crypto_spawn_blkcipher(spawn);
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if (IS_ERR(cipher))
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return PTR_ERR(cipher);
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ctx->child = cipher;
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return 0;
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}
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static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm)
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{
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struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
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crypto_free_blkcipher(ctx->child);
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}
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static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb)
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{
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struct crypto_instance *inst;
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struct crypto_alg *alg;
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int err;
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err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
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if (err)
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return ERR_PTR(err);
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alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_BLKCIPHER,
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CRYPTO_ALG_TYPE_MASK);
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err = PTR_ERR(alg);
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if (IS_ERR(alg))
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return ERR_PTR(err);
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/* We only support 16-byte blocks. */
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err = -EINVAL;
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if (alg->cra_blkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE)
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goto out_put_alg;
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/* Not a stream cipher? */
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if (alg->cra_blocksize != 1)
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goto out_put_alg;
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inst = crypto_alloc_instance("rfc3686", alg);
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if (IS_ERR(inst))
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goto out;
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inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
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inst->alg.cra_priority = alg->cra_priority;
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inst->alg.cra_blocksize = 1;
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inst->alg.cra_alignmask = alg->cra_alignmask;
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inst->alg.cra_type = &crypto_blkcipher_type;
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inst->alg.cra_blkcipher.ivsize = CTR_RFC3686_IV_SIZE;
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inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize
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+ CTR_RFC3686_NONCE_SIZE;
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inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize
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+ CTR_RFC3686_NONCE_SIZE;
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inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
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inst->alg.cra_init = crypto_rfc3686_init_tfm;
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inst->alg.cra_exit = crypto_rfc3686_exit_tfm;
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inst->alg.cra_blkcipher.setkey = crypto_rfc3686_setkey;
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inst->alg.cra_blkcipher.encrypt = crypto_rfc3686_crypt;
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inst->alg.cra_blkcipher.decrypt = crypto_rfc3686_crypt;
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out:
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crypto_mod_put(alg);
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return inst;
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out_put_alg:
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inst = ERR_PTR(err);
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goto out;
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}
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static struct crypto_template crypto_rfc3686_tmpl = {
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.name = "rfc3686",
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.alloc = crypto_rfc3686_alloc,
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.free = crypto_ctr_free,
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.module = THIS_MODULE,
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};
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static int __init crypto_ctr_module_init(void)
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{
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int err;
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err = crypto_register_template(&crypto_ctr_tmpl);
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if (err)
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goto out;
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err = crypto_register_template(&crypto_rfc3686_tmpl);
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if (err)
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goto out_drop_ctr;
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out:
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return err;
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out_drop_ctr:
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crypto_unregister_template(&crypto_ctr_tmpl);
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goto out;
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}
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static void __exit crypto_ctr_module_exit(void)
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{
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crypto_unregister_template(&crypto_rfc3686_tmpl);
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crypto_unregister_template(&crypto_ctr_tmpl);
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}
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module_init(crypto_ctr_module_init);
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module_exit(crypto_ctr_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("CTR Counter block mode");
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MODULE_ALIAS("rfc3686");
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