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9fcc704dfd
This patch changes the RNG allocation so that we only hold a reference to the RNG during initialisation. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
313 lines
7.3 KiB
C
313 lines
7.3 KiB
C
/*
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* echainiv: Encrypted Chain IV Generator
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*
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* This generator generates an IV based on a sequence number by xoring it
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* with a salt and then encrypting it with the same key as used to encrypt
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* the plain text. This algorithm requires that the block size be equal
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* to the IV size. It is mainly useful for CBC.
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*
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* This generator can only be used by algorithms where authentication
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* is performed after encryption (i.e., authenc).
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*
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* Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <crypto/internal/geniv.h>
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#include <crypto/null.h>
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#include <crypto/rng.h>
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#include <crypto/scatterwalk.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/percpu.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#define MAX_IV_SIZE 16
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struct echainiv_ctx {
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/* aead_geniv_ctx must be first the element */
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struct aead_geniv_ctx geniv;
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struct crypto_blkcipher *null;
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u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
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};
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static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv);
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/* We don't care if we get preempted and read/write IVs from the next CPU. */
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static void echainiv_read_iv(u8 *dst, unsigned size)
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{
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u32 *a = (u32 *)dst;
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u32 __percpu *b = echainiv_iv;
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for (; size >= 4; size -= 4) {
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*a++ = this_cpu_read(*b);
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b++;
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}
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}
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static void echainiv_write_iv(const u8 *src, unsigned size)
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{
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const u32 *a = (const u32 *)src;
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u32 __percpu *b = echainiv_iv;
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for (; size >= 4; size -= 4) {
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this_cpu_write(*b, *a);
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a++;
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b++;
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}
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}
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static void echainiv_encrypt_complete2(struct aead_request *req, int err)
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{
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struct aead_request *subreq = aead_request_ctx(req);
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struct crypto_aead *geniv;
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unsigned int ivsize;
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if (err == -EINPROGRESS)
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return;
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if (err)
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goto out;
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geniv = crypto_aead_reqtfm(req);
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ivsize = crypto_aead_ivsize(geniv);
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echainiv_write_iv(subreq->iv, ivsize);
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if (req->iv != subreq->iv)
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memcpy(req->iv, subreq->iv, ivsize);
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out:
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if (req->iv != subreq->iv)
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kzfree(subreq->iv);
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}
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static void echainiv_encrypt_complete(struct crypto_async_request *base,
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int err)
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{
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struct aead_request *req = base->data;
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echainiv_encrypt_complete2(req, err);
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aead_request_complete(req, err);
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}
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static int echainiv_encrypt(struct aead_request *req)
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{
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struct crypto_aead *geniv = crypto_aead_reqtfm(req);
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struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
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struct aead_request *subreq = aead_request_ctx(req);
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crypto_completion_t compl;
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void *data;
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u8 *info;
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unsigned int ivsize = crypto_aead_ivsize(geniv);
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int err;
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if (req->cryptlen < ivsize)
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return -EINVAL;
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aead_request_set_tfm(subreq, ctx->geniv.child);
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compl = echainiv_encrypt_complete;
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data = req;
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info = req->iv;
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if (req->src != req->dst) {
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struct blkcipher_desc desc = {
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.tfm = ctx->null,
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};
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err = crypto_blkcipher_encrypt(
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&desc, req->dst, req->src,
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req->assoclen + req->cryptlen);
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if (err)
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return err;
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}
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if (unlikely(!IS_ALIGNED((unsigned long)info,
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crypto_aead_alignmask(geniv) + 1))) {
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info = kmalloc(ivsize, req->base.flags &
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CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
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GFP_ATOMIC);
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if (!info)
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return -ENOMEM;
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memcpy(info, req->iv, ivsize);
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}
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aead_request_set_callback(subreq, req->base.flags, compl, data);
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aead_request_set_crypt(subreq, req->dst, req->dst,
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req->cryptlen - ivsize, info);
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aead_request_set_ad(subreq, req->assoclen + ivsize);
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crypto_xor(info, ctx->salt, ivsize);
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scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
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echainiv_read_iv(info, ivsize);
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err = crypto_aead_encrypt(subreq);
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echainiv_encrypt_complete2(req, err);
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return err;
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}
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static int echainiv_decrypt(struct aead_request *req)
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{
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struct crypto_aead *geniv = crypto_aead_reqtfm(req);
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struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
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struct aead_request *subreq = aead_request_ctx(req);
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crypto_completion_t compl;
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void *data;
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unsigned int ivsize = crypto_aead_ivsize(geniv);
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if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
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return -EINVAL;
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aead_request_set_tfm(subreq, ctx->geniv.child);
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compl = req->base.complete;
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data = req->base.data;
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aead_request_set_callback(subreq, req->base.flags, compl, data);
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aead_request_set_crypt(subreq, req->src, req->dst,
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req->cryptlen - ivsize, req->iv);
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aead_request_set_ad(subreq, req->assoclen + ivsize);
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scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
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if (req->src != req->dst)
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scatterwalk_map_and_copy(req->iv, req->dst,
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req->assoclen, ivsize, 1);
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return crypto_aead_decrypt(subreq);
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}
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static int echainiv_init(struct crypto_tfm *tfm)
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{
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struct crypto_aead *geniv = __crypto_aead_cast(tfm);
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struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
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int err;
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spin_lock_init(&ctx->geniv.lock);
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crypto_aead_set_reqsize(geniv, sizeof(struct aead_request));
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err = crypto_get_default_rng();
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if (err)
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goto out;
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err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
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crypto_aead_ivsize(geniv));
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crypto_put_default_rng();
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if (err)
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goto out;
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ctx->null = crypto_get_default_null_skcipher();
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err = PTR_ERR(ctx->null);
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if (IS_ERR(ctx->null))
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goto out;
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err = aead_geniv_init(tfm);
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if (err)
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goto drop_null;
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ctx->geniv.child = geniv->child;
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geniv->child = geniv;
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out:
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return err;
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drop_null:
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crypto_put_default_null_skcipher();
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goto out;
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}
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static void echainiv_exit(struct crypto_tfm *tfm)
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{
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struct echainiv_ctx *ctx = crypto_tfm_ctx(tfm);
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crypto_free_aead(ctx->geniv.child);
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crypto_put_default_null_skcipher();
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}
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static int echainiv_aead_create(struct crypto_template *tmpl,
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struct rtattr **tb)
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{
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struct aead_instance *inst;
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struct crypto_aead_spawn *spawn;
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struct aead_alg *alg;
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int err;
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inst = aead_geniv_alloc(tmpl, tb, 0, 0);
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if (IS_ERR(inst))
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return PTR_ERR(inst);
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spawn = aead_instance_ctx(inst);
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alg = crypto_spawn_aead_alg(spawn);
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if (alg->base.cra_aead.encrypt)
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goto done;
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err = -EINVAL;
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if (inst->alg.ivsize & (sizeof(u32) - 1) ||
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inst->alg.ivsize > MAX_IV_SIZE)
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goto free_inst;
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inst->alg.encrypt = echainiv_encrypt;
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inst->alg.decrypt = echainiv_decrypt;
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inst->alg.base.cra_init = echainiv_init;
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inst->alg.base.cra_exit = echainiv_exit;
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inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
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inst->alg.base.cra_ctxsize = sizeof(struct echainiv_ctx);
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inst->alg.base.cra_ctxsize += inst->alg.ivsize;
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done:
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err = aead_register_instance(tmpl, inst);
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if (err)
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goto free_inst;
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out:
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return err;
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free_inst:
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aead_geniv_free(inst);
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goto out;
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}
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static void echainiv_free(struct crypto_instance *inst)
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{
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aead_geniv_free(aead_instance(inst));
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}
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static struct crypto_template echainiv_tmpl = {
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.name = "echainiv",
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.create = echainiv_aead_create,
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.free = echainiv_free,
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.module = THIS_MODULE,
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};
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static int __init echainiv_module_init(void)
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{
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return crypto_register_template(&echainiv_tmpl);
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}
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static void __exit echainiv_module_exit(void)
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{
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crypto_unregister_template(&echainiv_tmpl);
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}
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module_init(echainiv_module_init);
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module_exit(echainiv_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Encrypted Chain IV Generator");
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MODULE_ALIAS_CRYPTO("echainiv");
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