/* * 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 <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/scatterwalk.h> #include <linux/err.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/scatterlist.h> #include <linux/spinlock.h> #include <linux/string.h> 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 + ivsize, 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; if (giv != req->giv) 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); int err = 0; spin_lock_bh(&ctx->lock); if (crypto_ablkcipher_crt(geniv)->givencrypt != eseqiv_givencrypt_first) goto unlock; crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt; err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt, crypto_ablkcipher_ivsize(geniv)); unlock: spin_unlock_bh(&ctx->lock); if (err) return err; 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; err = crypto_get_default_rng(); if (err) return ERR_PTR(err); inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0); if (IS_ERR(inst)) goto put_rng; 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); put_rng: crypto_put_default_rng(); goto out; } static void eseqiv_free(struct crypto_instance *inst) { skcipher_geniv_free(inst); crypto_put_default_rng(); } static struct crypto_template eseqiv_tmpl = { .name = "eseqiv", .alloc = eseqiv_alloc, .free = eseqiv_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");