diff options
Diffstat (limited to 'kernel/crypto/echainiv.c')
| -rw-r--r-- | kernel/crypto/echainiv.c | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/kernel/crypto/echainiv.c b/kernel/crypto/echainiv.c new file mode 100644 index 000000000..b96a84560 --- /dev/null +++ b/kernel/crypto/echainiv.c @@ -0,0 +1,250 @@ +/* + * echainiv: Encrypted Chain 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. + * + * This generator can only be used by algorithms where authentication + * is performed after encryption (i.e., authenc). + * + * Copyright (c) 2015 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/geniv.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/percpu.h> +#include <linux/spinlock.h> +#include <linux/string.h> + +#define MAX_IV_SIZE 16 + +static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv); + +/* We don't care if we get preempted and read/write IVs from the next CPU. */ +static void echainiv_read_iv(u8 *dst, unsigned size) +{ + u32 *a = (u32 *)dst; + u32 __percpu *b = echainiv_iv; + + for (; size >= 4; size -= 4) { + *a++ = this_cpu_read(*b); + b++; + } +} + +static void echainiv_write_iv(const u8 *src, unsigned size) +{ + const u32 *a = (const u32 *)src; + u32 __percpu *b = echainiv_iv; + + for (; size >= 4; size -= 4) { + this_cpu_write(*b, *a); + a++; + b++; + } +} + +static void echainiv_encrypt_complete2(struct aead_request *req, int err) +{ + struct aead_request *subreq = aead_request_ctx(req); + struct crypto_aead *geniv; + unsigned int ivsize; + + if (err == -EINPROGRESS) + return; + + if (err) + goto out; + + geniv = crypto_aead_reqtfm(req); + ivsize = crypto_aead_ivsize(geniv); + + echainiv_write_iv(subreq->iv, ivsize); + + if (req->iv != subreq->iv) + memcpy(req->iv, subreq->iv, ivsize); + +out: + if (req->iv != subreq->iv) + kzfree(subreq->iv); +} + +static void echainiv_encrypt_complete(struct crypto_async_request *base, + int err) +{ + struct aead_request *req = base->data; + + echainiv_encrypt_complete2(req, err); + aead_request_complete(req, err); +} + +static int echainiv_encrypt(struct aead_request *req) +{ + struct crypto_aead *geniv = crypto_aead_reqtfm(req); + struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); + struct aead_request *subreq = aead_request_ctx(req); + crypto_completion_t compl; + void *data; + u8 *info; + unsigned int ivsize = crypto_aead_ivsize(geniv); + int err; + + if (req->cryptlen < ivsize) + return -EINVAL; + + aead_request_set_tfm(subreq, ctx->child); + + compl = echainiv_encrypt_complete; + data = req; + info = req->iv; + + if (req->src != req->dst) { + struct blkcipher_desc desc = { + .tfm = ctx->null, + }; + + err = crypto_blkcipher_encrypt( + &desc, req->dst, req->src, + req->assoclen + req->cryptlen); + if (err) + return err; + } + + if (unlikely(!IS_ALIGNED((unsigned long)info, + crypto_aead_alignmask(geniv) + 1))) { + info = kmalloc(ivsize, req->base.flags & + CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: + GFP_ATOMIC); + if (!info) + return -ENOMEM; + + memcpy(info, req->iv, ivsize); + } + + aead_request_set_callback(subreq, req->base.flags, compl, data); + aead_request_set_crypt(subreq, req->dst, req->dst, + req->cryptlen, info); + aead_request_set_ad(subreq, req->assoclen); + + crypto_xor(info, ctx->salt, ivsize); + scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1); + echainiv_read_iv(info, ivsize); + + err = crypto_aead_encrypt(subreq); + echainiv_encrypt_complete2(req, err); + return err; +} + +static int echainiv_decrypt(struct aead_request *req) +{ + struct crypto_aead *geniv = crypto_aead_reqtfm(req); + struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); + struct aead_request *subreq = aead_request_ctx(req); + crypto_completion_t compl; + void *data; + unsigned int ivsize = crypto_aead_ivsize(geniv); + + if (req->cryptlen < ivsize) + return -EINVAL; + + aead_request_set_tfm(subreq, ctx->child); + + compl = req->base.complete; + data = req->base.data; + + aead_request_set_callback(subreq, req->base.flags, compl, data); + aead_request_set_crypt(subreq, req->src, req->dst, + req->cryptlen - ivsize, req->iv); + aead_request_set_ad(subreq, req->assoclen + ivsize); + + scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0); + + return crypto_aead_decrypt(subreq); +} + +static int echainiv_aead_create(struct crypto_template *tmpl, + struct rtattr **tb) +{ + struct aead_instance *inst; + struct crypto_aead_spawn *spawn; + struct aead_alg *alg; + int err; + + inst = aead_geniv_alloc(tmpl, tb, 0, 0); + + if (IS_ERR(inst)) + return PTR_ERR(inst); + + spawn = aead_instance_ctx(inst); + alg = crypto_spawn_aead_alg(spawn); + + err = -EINVAL; + if (inst->alg.ivsize & (sizeof(u32) - 1) || + inst->alg.ivsize > MAX_IV_SIZE) + goto free_inst; + + inst->alg.encrypt = echainiv_encrypt; + inst->alg.decrypt = echainiv_decrypt; + + inst->alg.init = aead_init_geniv; + inst->alg.exit = aead_exit_geniv; + + inst->alg.base.cra_alignmask |= __alignof__(u32) - 1; + inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx); + inst->alg.base.cra_ctxsize += inst->alg.ivsize; + + inst->free = aead_geniv_free; + + err = aead_register_instance(tmpl, inst); + if (err) + goto free_inst; + +out: + return err; + +free_inst: + aead_geniv_free(inst); + goto out; +} + +static void echainiv_free(struct crypto_instance *inst) +{ + aead_geniv_free(aead_instance(inst)); +} + +static struct crypto_template echainiv_tmpl = { + .name = "echainiv", + .create = echainiv_aead_create, + .free = echainiv_free, + .module = THIS_MODULE, +}; + +static int __init echainiv_module_init(void) +{ + return crypto_register_template(&echainiv_tmpl); +} + +static void __exit echainiv_module_exit(void) +{ + crypto_unregister_template(&echainiv_tmpl); +} + +module_init(echainiv_module_init); +module_exit(echainiv_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Encrypted Chain IV Generator"); +MODULE_ALIAS_CRYPTO("echainiv"); |