1 files changed, 531 insertions, 0 deletions
diff --git a/crypto/echainiv.c b/crypto/echainiv.c
new file mode 100644
index 000000000000..e5a9878e6532
--- /dev/null
+++ b/crypto/echainiv.c
@@ -0,0 +1,531 @@
+/*
+ * 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/aead.h>
+#include <crypto/null.h>
+#include <crypto/rng.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
+
+struct echainiv_request_ctx {
+	struct scatterlist src[2];
+	struct scatterlist dst[2];
+	struct scatterlist ivbuf[2];
+	struct scatterlist *ivsg;
+	struct aead_givcrypt_request subreq;
+};
+
+struct echainiv_ctx {
+	struct crypto_aead *child;
+	spinlock_t lock;
+	struct crypto_blkcipher *null;
+	u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
+};
+
+static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv);
+
+static int echainiv_setkey(struct crypto_aead *tfm,
+			      const u8 *key, unsigned int keylen)
+{
+	struct echainiv_ctx *ctx = crypto_aead_ctx(tfm);
+
+	return crypto_aead_setkey(ctx->child, key, keylen);
+}
+
+static int echainiv_setauthsize(struct crypto_aead *tfm,
+				  unsigned int authsize)
+{
+	struct echainiv_ctx *ctx = crypto_aead_ctx(tfm);
+
+	return crypto_aead_setauthsize(ctx->child, authsize);
+}
+
+/* We don't care if we get preempted and read/write IVs from the next CPU. */
+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++;
+	}
+}
+
+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_compat_complete2(struct aead_request *req,
+						 int err)
+{
+	struct echainiv_request_ctx *rctx = aead_request_ctx(req);
+	struct aead_givcrypt_request *subreq = &rctx->subreq;
+	struct crypto_aead *geniv;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	if (err)
+		goto out;
+
+	geniv = crypto_aead_reqtfm(req);
+	scatterwalk_map_and_copy(subreq->giv, rctx->ivsg, 0,
+				 crypto_aead_ivsize(geniv), 1);
+
+out:
+	kzfree(subreq->giv);
+}
+
+static void echainiv_encrypt_compat_complete(
+	struct crypto_async_request *base, int err)
+{
+	struct aead_request *req = base->data;
+
+	echainiv_encrypt_compat_complete2(req, err);
+	aead_request_complete(req, err);
+}
+
+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_compat(struct aead_request *req)
+{
+	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
+	struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
+	struct echainiv_request_ctx *rctx = aead_request_ctx(req);
+	struct aead_givcrypt_request *subreq = &rctx->subreq;
+	unsigned int ivsize = crypto_aead_ivsize(geniv);
+	crypto_completion_t compl;
+	void *data;
+	u8 *info;
+	__be64 seq;
+	int err;
+
+	compl = req->base.complete;
+	data = req->base.data;
+
+	rctx->ivsg = scatterwalk_ffwd(rctx->ivbuf, req->dst, req->assoclen);
+	info = PageHighMem(sg_page(rctx->ivsg)) ? NULL : sg_virt(rctx->ivsg);
+
+	if (!info) {
+		info = kmalloc(ivsize, req->base.flags &
+				       CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
+								  GFP_ATOMIC);
+		if (!info)
+			return -ENOMEM;
+
+		compl = echainiv_encrypt_compat_complete;
+		data = req;
+	}
+
+	memcpy(&seq, req->iv + ivsize - sizeof(seq), sizeof(seq));
+
+	aead_givcrypt_set_tfm(subreq, ctx->child);
+	aead_givcrypt_set_callback(subreq, req->base.flags,
+				   req->base.complete, req->base.data);
+	aead_givcrypt_set_crypt(subreq,
+				scatterwalk_ffwd(rctx->src, req->src,
+						 req->assoclen + ivsize),
+				scatterwalk_ffwd(rctx->dst, rctx->ivsg,
+						 ivsize),
+				req->cryptlen - ivsize, req->iv);
+	aead_givcrypt_set_assoc(subreq, req->src, req->assoclen);
+	aead_givcrypt_set_giv(subreq, info, be64_to_cpu(seq));
+
+	err = crypto_aead_givencrypt(subreq);
+	if (unlikely(PageHighMem(sg_page(rctx->ivsg))))
+		echainiv_encrypt_compat_complete2(req, err);
+	return err;
+}
+
+static int echainiv_encrypt(struct aead_request *req)
+{
+	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
+	struct echainiv_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;
+	int err;
+
+	aead_request_set_tfm(subreq, ctx->child);
+
+	compl = echainiv_encrypt_complete;
+	data = req;
+	info = req->iv;
+
+	ivsize = crypto_aead_ivsize(geniv);
+
+	if (req->src != req->dst) {
+		struct scatterlist src[2];
+		struct scatterlist dst[2];
+		struct blkcipher_desc desc = {
+			.tfm = ctx->null,
+		};
+
+		err = crypto_blkcipher_encrypt(
+			&desc,
+			scatterwalk_ffwd(dst, req->dst,
+					 req->assoclen + ivsize),
+			scatterwalk_ffwd(src, req->src,
+					 req->assoclen + ivsize),
+			req->cryptlen - ivsize);
+		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 - ivsize, info);
+	aead_request_set_ad(subreq, req->assoclen + ivsize, 0);
+
+	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_compat(struct aead_request *req)
+{
+	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
+	struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
+	struct aead_request *subreq = aead_request_ctx(req);
+	crypto_completion_t compl;
+	void *data;
+	unsigned int ivsize;
+
+	aead_request_set_tfm(subreq, ctx->child);
+
+	compl = req->base.complete;
+	data = req->base.data;
+
+	ivsize = crypto_aead_ivsize(geniv);
+
+	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_decrypt(struct aead_request *req)
+{
+	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
+	struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
+	struct aead_request *subreq = aead_request_ctx(req);
+	crypto_completion_t compl;
+	void *data;
+	unsigned int ivsize;
+
+	aead_request_set_tfm(subreq, ctx->child);
+
+	compl = req->base.complete;
+	data = req->base.data;
+
+	ivsize = crypto_aead_ivsize(geniv);
+
+	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, 0);
+
+	scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
+	if (req->src != req->dst)
+		scatterwalk_map_and_copy(req->iv, req->dst,
+					 req->assoclen, ivsize, 1);
+
+	return crypto_aead_decrypt(subreq);
+}
+
+static int echainiv_encrypt_compat_first(struct aead_request *req)
+{
+	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
+	struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
+	int err = 0;
+
+	spin_lock_bh(&ctx->lock);
+	if (geniv->encrypt != echainiv_encrypt_compat_first)
+		goto unlock;
+
+	geniv->encrypt = echainiv_encrypt_compat;
+	err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
+				   crypto_aead_ivsize(geniv));
+
+unlock:
+	spin_unlock_bh(&ctx->lock);
+
+	if (err)
+		return err;
+
+	return echainiv_encrypt_compat(req);
+}
+
+static int echainiv_encrypt_first(struct aead_request *req)
+{
+	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
+	struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
+	int err = 0;
+
+	spin_lock_bh(&ctx->lock);
+	if (geniv->encrypt != echainiv_encrypt_first)
+		goto unlock;
+
+	geniv->encrypt = echainiv_encrypt;
+	err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
+				   crypto_aead_ivsize(geniv));
+
+unlock:
+	spin_unlock_bh(&ctx->lock);
+
+	if (err)
+		return err;
+
+	return echainiv_encrypt(req);
+}
+
+static int echainiv_compat_init(struct crypto_tfm *tfm)
+{
+	struct crypto_aead *geniv = __crypto_aead_cast(tfm);
+	struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
+	int err;
+
+	spin_lock_init(&ctx->lock);
+
+	crypto_aead_set_reqsize(geniv, sizeof(struct echainiv_request_ctx));
+
+	err = aead_geniv_init(tfm);
+
+	ctx->child = geniv->child;
+	geniv->child = geniv;
+
+	return err;
+}
+
+static int echainiv_init(struct crypto_tfm *tfm)
+{
+	struct crypto_aead *geniv = __crypto_aead_cast(tfm);
+	struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
+	int err;
+
+	spin_lock_init(&ctx->lock);
+
+	crypto_aead_set_reqsize(geniv, sizeof(struct aead_request));
+
+	ctx->null = crypto_get_default_null_skcipher();
+	err = PTR_ERR(ctx->null);
+	if (IS_ERR(ctx->null))
+		goto out;
+
+	err = aead_geniv_init(tfm);
+	if (err)
+		goto drop_null;
+
+	ctx->child = geniv->child;
+	geniv->child = geniv;
+
+out:
+	return err;
+
+drop_null:
+	crypto_put_default_null_skcipher();
+	goto out;
+}
+
+static void echainiv_compat_exit(struct crypto_tfm *tfm)
+{
+	struct echainiv_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_aead(ctx->child);
+}
+
+static void echainiv_exit(struct crypto_tfm *tfm)
+{
+	struct echainiv_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_aead(ctx->child);
+	crypto_put_default_null_skcipher();
+}
+
+static struct crypto_template echainiv_tmpl;
+
+static struct crypto_instance *echainiv_aead_alloc(struct rtattr **tb)
+{
+	struct aead_instance *inst;
+	struct crypto_aead_spawn *spawn;
+	struct aead_alg *alg;
+
+	inst = aead_geniv_alloc(&echainiv_tmpl, tb, 0, 0);
+
+	if (IS_ERR(inst))
+		goto out;
+
+	if (inst->alg.ivsize < sizeof(u64) ||
+	    inst->alg.ivsize & (sizeof(u32) - 1) ||
+	    inst->alg.ivsize > MAX_IV_SIZE) {
+		aead_geniv_free(inst);
+		inst = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+	spawn = aead_instance_ctx(inst);
+	alg = crypto_spawn_aead_alg(spawn);
+
+	inst->alg.setkey = echainiv_setkey;
+	inst->alg.setauthsize = echainiv_setauthsize;
+	inst->alg.encrypt = echainiv_encrypt_first;
+	inst->alg.decrypt = echainiv_decrypt;
+
+	inst->alg.base.cra_init = echainiv_init;
+	inst->alg.base.cra_exit = echainiv_exit;
+
+	inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
+	inst->alg.base.cra_ctxsize = sizeof(struct echainiv_ctx);
+	inst->alg.base.cra_ctxsize += inst->alg.base.cra_aead.ivsize;
+
+	if (alg->base.cra_aead.encrypt) {
+		inst->alg.encrypt = echainiv_encrypt_compat_first;
+		inst->alg.decrypt = echainiv_decrypt_compat;
+
+		inst->alg.base.cra_init = echainiv_compat_init;
+		inst->alg.base.cra_exit = echainiv_compat_exit;
+	}
+
+out:
+	return aead_crypto_instance(inst);
+}
+
+static struct crypto_instance *echainiv_alloc(struct rtattr **tb)
+{
+	struct crypto_instance *inst;
+	int err;
+
+	err = crypto_get_default_rng();
+	if (err)
+		return ERR_PTR(err);
+
+	inst = echainiv_aead_alloc(tb);
+
+	if (IS_ERR(inst))
+		goto put_rng;
+
+out:
+	return inst;
+
+put_rng:
+	crypto_put_default_rng();
+	goto out;
+}
+
+static void echainiv_free(struct crypto_instance *inst)
+{
+	aead_geniv_free(aead_instance(inst));
+	crypto_put_default_rng();
+}
+
+static struct crypto_template echainiv_tmpl = {
+	.name = "echainiv",
+	.alloc = echainiv_alloc,
+	.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");