diff options
Diffstat (limited to 'crypto/seqiv.c')
| -rw-r--r-- | crypto/seqiv.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/crypto/seqiv.c b/crypto/seqiv.c new file mode 100644 index 0000000..9c2d80d --- /dev/null +++ b/crypto/seqiv.c @@ -0,0 +1,186 @@ +/* + * seqiv: Sequence Number IV Generator + * + * This generator generates an IV based on a sequence number by xoring it + * with a salt. This algorithm is mainly useful for CTR and similar modes. + * + * 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 <linux/err.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/random.h> +#include <linux/spinlock.h> +#include <linux/string.h> + +struct seqiv_ctx { + spinlock_t lock; + u8 salt[] __attribute__ ((aligned(__alignof__(u32)))); +}; + +static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err) +{ + struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); + struct crypto_ablkcipher *geniv; + + if (err == -EINPROGRESS) + return; + + if (err) + goto out; + + geniv = skcipher_givcrypt_reqtfm(req); + memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv)); + +out: + kfree(subreq->info); +} + +static void seqiv_complete(struct crypto_async_request *base, int err) +{ + struct skcipher_givcrypt_request *req = base->data; + + seqiv_complete2(req, err); + skcipher_givcrypt_complete(req, err); +} + +static int seqiv_givencrypt(struct skcipher_givcrypt_request *req) +{ + struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); + struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); + struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); + crypto_completion_t complete; + void *data; + u8 *info; + __be64 seq; + unsigned int ivsize; + unsigned int len; + int err; + + ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv)); + + complete = req->creq.base.complete; + data = req->creq.base.data; + info = req->creq.info; + + ivsize = crypto_ablkcipher_ivsize(geniv); + + if (unlikely(!IS_ALIGNED((unsigned long)info, + crypto_ablkcipher_alignmask(geniv) + 1))) { + info = kmalloc(ivsize, req->creq.base.flags & + CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: + GFP_ATOMIC); + if (!info) + return -ENOMEM; + + complete = seqiv_complete; + data = req; + } + + ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete, + data); + ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst, + req->creq.nbytes, info); + + len = ivsize; + if (ivsize > sizeof(u64)) { + memset(info, 0, ivsize - sizeof(u64)); + len = sizeof(u64); + } + seq = cpu_to_be64(req->seq); + memcpy(info + ivsize - len, &seq, len); + crypto_xor(info, ctx->salt, ivsize); + + memcpy(req->giv, info, ivsize); + + err = crypto_ablkcipher_encrypt(subreq); + if (unlikely(info != req->creq.info)) + seqiv_complete2(req, err); + return err; +} + +static int seqiv_givencrypt_first(struct skcipher_givcrypt_request *req) +{ + struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); + struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); + + spin_lock_bh(&ctx->lock); + if (crypto_ablkcipher_crt(geniv)->givencrypt != seqiv_givencrypt_first) + goto unlock; + + crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt; + get_random_bytes(ctx->salt, crypto_ablkcipher_ivsize(geniv)); + +unlock: + spin_unlock_bh(&ctx->lock); + + return seqiv_givencrypt(req); +} + +static int seqiv_init(struct crypto_tfm *tfm) +{ + struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); + struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); + + spin_lock_init(&ctx->lock); + + tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request); + + return skcipher_geniv_init(tfm); +} + +static struct crypto_template seqiv_tmpl; + +static struct crypto_instance *seqiv_alloc(struct rtattr **tb) +{ + struct crypto_instance *inst; + + inst = skcipher_geniv_alloc(&seqiv_tmpl, tb, 0, 0); + if (IS_ERR(inst)) + goto out; + + inst->alg.cra_ablkcipher.givencrypt = seqiv_givencrypt_first; + + inst->alg.cra_init = seqiv_init; + inst->alg.cra_exit = skcipher_geniv_exit; + + inst->alg.cra_alignmask |= __alignof__(u32) - 1; + + inst->alg.cra_ctxsize = sizeof(struct seqiv_ctx); + inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; + +out: + return inst; +} + +static struct crypto_template seqiv_tmpl = { + .name = "seqiv", + .alloc = seqiv_alloc, + .free = skcipher_geniv_free, + .module = THIS_MODULE, +}; + +static int __init seqiv_module_init(void) +{ + return crypto_register_template(&seqiv_tmpl); +} + +static void __exit seqiv_module_exit(void) +{ + crypto_unregister_template(&seqiv_tmpl); +} + +module_init(seqiv_module_init); +module_exit(seqiv_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Sequence Number IV Generator"); |