diff options
Diffstat (limited to 'crypto/eseqiv.c')
| -rw-r--r-- | crypto/eseqiv.c | 264 |
1 files changed, 264 insertions, 0 deletions
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 <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/scatterwalk.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/random.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, 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"); |