From: Herbert Xu Subject: [PATCH 12/19] [CRYPTO] eseqiv: Add Encrypted Sequence Number IV Generator Date: Tue, 11 Dec 2007 12:05:40 +0800 Message-ID: References: <20071211040215.GA10360@gondor.apana.org.au> To: Linux Crypto Mailing List Return-path: Received: from rhun.apana.org.au ([64.62.148.172]:1961 "EHLO arnor.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751357AbXLKEFo (ORCPT ); Mon, 10 Dec 2007 23:05:44 -0500 Received: from gondolin.me.apana.org.au ([192.168.0.6] ident=mail) by arnor.apana.org.au with esmtp (Exim 4.50 #1 (Debian)) id 1J1wNJ-00067t-Jy for ; Tue, 11 Dec 2007 15:05:41 +1100 Sender: linux-crypto-owner@vger.kernel.org List-ID: [CRYPTO] eseqiv: Add Encrypted Sequence Number IV Generator This generator generates an IV based on a sequence number by xoring it with a salt and then encrypting it with the same key as used to encrypt the plain text. This algorithm requires that the block size be equal to the IV size. It is mainly useful for CBC. It has one noteworthy property that for IPsec the IV happens to lie just before the plain text so the IV generation simply increases the number of encrypted blocks by one. Therefore the cost of this generator is entirely dependent on the speed of the underlying cipher. Signed-off-by: Herbert Xu --- crypto/Makefile | 1 crypto/eseqiv.c | 264 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 265 insertions(+) diff --git a/crypto/Makefile b/crypto/Makefile index 4b2e0c3..968b796 100644 --- a/crypto/Makefile +++ b/crypto/Makefile @@ -14,6 +14,7 @@ crypto_blkcipher-objs := ablkcipher.o crypto_blkcipher-objs += blkcipher.o obj-$(CONFIG_CRYPTO_BLKCIPHER) += crypto_blkcipher.o obj-$(CONFIG_CRYPTO_BLKCIPHER) += chainiv.o +obj-$(CONFIG_CRYPTO_BLKCIPHER) += eseqiv.o crypto_hash-objs := hash.o obj-$(CONFIG_CRYPTO_HASH) += crypto_hash.o diff --git a/crypto/eseqiv.c b/crypto/eseqiv.c new file mode 100644 index 0000000..eb90d27 --- /dev/null +++ b/crypto/eseqiv.c @@ -0,0 +1,264 @@ +/* + * eseqiv: Encrypted Sequence Number IV Generator + * + * This generator generates an IV based on a sequence number by xoring it + * with a salt and then encrypting it with the same key as used to encrypt + * the plain text. This algorithm requires that the block size be equal + * to the IV size. It is mainly useful for CBC. + * + * Copyright (c) 2007 Herbert Xu + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +struct eseqiv_request_ctx { + struct scatterlist src[2]; + struct scatterlist dst[2]; + char tail[]; +}; + +struct eseqiv_ctx { + spinlock_t lock; + unsigned int reqoff; + char salt[]; +}; + +static void eseqiv_complete2(struct skcipher_givcrypt_request *req) +{ + struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); + struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req); + + memcpy(req->giv, PTR_ALIGN((u8 *)reqctx->tail, + crypto_ablkcipher_alignmask(geniv) + 1), + crypto_ablkcipher_ivsize(geniv)); +} + +static void eseqiv_complete(struct crypto_async_request *base, int err) +{ + struct skcipher_givcrypt_request *req = base->data; + + if (err) + goto out; + + eseqiv_complete2(req); + +out: + skcipher_givcrypt_complete(req, err); +} + +static void eseqiv_chain(struct scatterlist *head, struct scatterlist *sg, + int chain) +{ + if (chain) { + head->length += sg->length; + sg = scatterwalk_sg_next(sg); + } + + if (sg) + scatterwalk_sg_chain(head, 2, sg); + else + sg_mark_end(head); +} + +static int eseqiv_givencrypt(struct skcipher_givcrypt_request *req) +{ + struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); + struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); + struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req); + struct ablkcipher_request *subreq; + crypto_completion_t complete; + void *data; + struct scatterlist *osrc, *odst; + struct scatterlist *dst; + struct page *srcp; + struct page *dstp; + u8 *giv; + u8 *vsrc; + u8 *vdst; + __be64 seq; + unsigned int ivsize; + unsigned int len; + int err; + + subreq = (void *)(reqctx->tail + ctx->reqoff); + ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv)); + + giv = req->giv; + complete = req->creq.base.complete; + data = req->creq.base.data; + + osrc = req->creq.src; + odst = req->creq.dst; + srcp = sg_page(osrc); + dstp = sg_page(odst); + vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + osrc->offset; + vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + odst->offset; + + ivsize = crypto_ablkcipher_ivsize(geniv); + + if (vsrc != giv + ivsize && vdst != giv + ivsize) { + giv = PTR_ALIGN((u8 *)reqctx->tail, + crypto_ablkcipher_alignmask(geniv) + 1); + complete = eseqiv_complete; + data = req; + } + + ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete, + data); + + sg_init_table(reqctx->src, 2); + sg_set_buf(reqctx->src, giv, ivsize); + eseqiv_chain(reqctx->src, osrc, vsrc == giv + ivsize); + + dst = reqctx->src; + if (osrc != odst) { + sg_init_table(reqctx->dst, 2); + sg_set_buf(reqctx->dst, giv, ivsize); + eseqiv_chain(reqctx->dst, odst, vdst == giv + ivsize); + + dst = reqctx->dst; + } + + ablkcipher_request_set_crypt(subreq, reqctx->src, dst, + req->creq.nbytes, req->creq.info); + + memcpy(req->creq.info, ctx->salt, ivsize); + + len = ivsize; + if (ivsize > sizeof(u64)) { + memset(req->giv, 0, ivsize - sizeof(u64)); + len = sizeof(u64); + } + seq = cpu_to_be64(req->seq); + memcpy(req->giv + ivsize - len, &seq, len); + + err = crypto_ablkcipher_encrypt(subreq); + if (err) + goto out; + + eseqiv_complete2(req); + +out: + return err; +} + +static int eseqiv_givencrypt_first(struct skcipher_givcrypt_request *req) +{ + struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); + struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); + + spin_lock_bh(&ctx->lock); + if (crypto_ablkcipher_crt(geniv)->givencrypt != eseqiv_givencrypt_first) + goto unlock; + + crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt; + get_random_bytes(ctx->salt, crypto_ablkcipher_ivsize(geniv)); + +unlock: + spin_unlock_bh(&ctx->lock); + + return eseqiv_givencrypt(req); +} + +static int eseqiv_init(struct crypto_tfm *tfm) +{ + struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); + struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); + unsigned long alignmask; + unsigned int reqsize; + + spin_lock_init(&ctx->lock); + + alignmask = crypto_tfm_ctx_alignment() - 1; + reqsize = sizeof(struct eseqiv_request_ctx); + + if (alignmask & reqsize) { + alignmask &= reqsize; + alignmask--; + } + + alignmask = ~alignmask; + alignmask &= crypto_ablkcipher_alignmask(geniv); + + reqsize += alignmask; + reqsize += crypto_ablkcipher_ivsize(geniv); + reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment()); + + ctx->reqoff = reqsize - sizeof(struct eseqiv_request_ctx); + + tfm->crt_ablkcipher.reqsize = reqsize + + sizeof(struct ablkcipher_request); + + return skcipher_geniv_init(tfm); +} + +static struct crypto_template eseqiv_tmpl; + +static struct crypto_instance *eseqiv_alloc(struct rtattr **tb) +{ + struct crypto_instance *inst; + int err; + + inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0); + if (IS_ERR(inst)) + goto out; + + err = -EINVAL; + if (inst->alg.cra_ablkcipher.ivsize != inst->alg.cra_blocksize) + goto free_inst; + + inst->alg.cra_ablkcipher.givencrypt = eseqiv_givencrypt_first; + + inst->alg.cra_init = eseqiv_init; + inst->alg.cra_exit = skcipher_geniv_exit; + + inst->alg.cra_ctxsize = sizeof(struct eseqiv_ctx); + inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; + +out: + return inst; + +free_inst: + skcipher_geniv_free(inst); + inst = ERR_PTR(err); + goto out; +} + +static struct crypto_template eseqiv_tmpl = { + .name = "eseqiv", + .alloc = eseqiv_alloc, + .free = skcipher_geniv_free, + .module = THIS_MODULE, +}; + +static int __init eseqiv_module_init(void) +{ + return crypto_register_template(&eseqiv_tmpl); +} + +static void __exit eseqiv_module_exit(void) +{ + crypto_unregister_template(&eseqiv_tmpl); +} + +module_init(eseqiv_module_init); +module_exit(eseqiv_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Encrypted Sequence Number IV Generator");