--- /dev/null
+/*
+ * 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");
Code Review / kvmfornfv.git / blobdiff