From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Sun, 6 Jan 2008 16:09:33 +1100
Subject: [crypto] aead: add authenc
Message-id: E1JBNlN-0001Bs-00@gondolin.me.apana.org.au
O-Subject: [PATCH 18/32] [CRYPTO] aead: Add authenc
Bugzilla: 253051

[CRYPTO] aead: Add authenc

This patch adds the authenc algorithm which constructs an AEAD algorithm
from an asynchronous block cipher and a hash.  The construction is done
by concatenating the encrypted result from the cipher with the output
from the hash, as is used by the IPsec ESP protocol.

The authenc algorithm exists as a template with two parameters:

authenc(auth, enc)

The authentication algorithm, and the encryption algorithm.  For example,
AES-CBC with SHA1-HMAC would be represented by

authenc(hmac(sha1), cbc(aes))

The key for the authenc algorithm is the concatenation of the keys
for the authentication algorithm with the encryption algorithm with
a preamble that specifies how long is each.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Acked-by: "David S. Miller" <davem@redhat.com>

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 5fa1fb5..9169915 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -445,6 +445,15 @@ config CRYPTO_TEST
 	help
 	  Quick & dirty crypto test module.
 
+config CRYPTO_AUTHENC
+	tristate "Authenc support"
+	select CRYPTO_AEAD
+	select CRYPTO_MANAGER
+	select CRYPTO_HASH
+	help
+	  Authenc: Combined mode wrapper for IPsec.
+	  This is required for IPSec.
+
 config CRYPTO_SIGNATURE
 	bool "In-kernel signature checker (EXPERIMENTAL)"
 	depends on CRYPTO
diff --git a/crypto/Makefile b/crypto/Makefile
index 8e81b7d..5b9f139 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -53,6 +53,7 @@ obj-$(CONFIG_CRYPTO_ANUBIS) += anubis.o
 obj-$(CONFIG_CRYPTO_DEFLATE) += deflate.o
 obj-$(CONFIG_CRYPTO_MICHAEL_MIC) += michael_mic.o
 obj-$(CONFIG_CRYPTO_CRC32C) += crc32c.o
+obj-$(CONFIG_CRYPTO_AUTHENC) += authenc.o
 
 obj-$(CONFIG_CRYPTO_TEST) += tcrypt.o
 
diff --git a/crypto/authenc.c b/crypto/authenc.c
new file mode 100644
index 0000000..612d65a
--- /dev/null
+++ b/crypto/authenc.c
@@ -0,0 +1,486 @@
+/*
+ * Authenc: Simple AEAD wrapper for IPsec
+ *
+ * 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/aead.h>
+#include <crypto/internal/skcipher.h>
+#include <crypto/authenc.h>
+#include <crypto/nscatterwalk.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rtnetlink.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+struct authenc_instance_ctx {
+	struct crypto_spawn auth;
+	struct crypto_skcipher_spawn enc;
+};
+
+struct crypto_authenc_ctx {
+	spinlock_t auth_lock;
+	struct crypto_hash *auth;
+	struct crypto_ablkcipher *enc;
+};
+
+static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
+				 unsigned int keylen)
+{
+	unsigned int authkeylen;
+	unsigned int enckeylen;
+	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
+	struct crypto_hash *auth = ctx->auth;
+	struct crypto_ablkcipher *enc = ctx->enc;
+	struct rtattr *rta = (void *)key;
+	struct crypto_authenc_key_param *param;
+	int err = -EINVAL;
+
+	if (!RTA_OK(rta, keylen))
+		goto badkey;
+	if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
+		goto badkey;
+	if (RTA_PAYLOAD(rta) < sizeof(*param))
+		goto badkey;
+
+	param = RTA_DATA(rta);
+	enckeylen = be32_to_cpu(param->enckeylen);
+
+	key += RTA_ALIGN(rta->rta_len);
+	keylen -= RTA_ALIGN(rta->rta_len);
+
+	if (keylen < enckeylen)
+		goto badkey;
+
+	authkeylen = keylen - enckeylen;
+
+	crypto_hash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
+	crypto_hash_set_flags(auth, crypto_aead_get_flags(authenc) &
+				    CRYPTO_TFM_REQ_MASK);
+	err = crypto_hash_setkey(auth, key, authkeylen);
+	crypto_aead_set_flags(authenc, crypto_hash_get_flags(auth) &
+				       CRYPTO_TFM_RES_MASK);
+
+	if (err)
+		goto out;
+
+	crypto_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
+	crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
+					 CRYPTO_TFM_REQ_MASK);
+	err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
+	crypto_aead_set_flags(authenc, crypto_ablkcipher_get_flags(enc) &
+				       CRYPTO_TFM_RES_MASK);
+
+out:
+	return err;
+
+badkey:
+	crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
+	goto out;
+}
+
+static void authenc_chain(struct scatterlist *head, struct scatterlist *sg,
+			  int chain)
+{
+	if (chain) {
+		head->length += sg->length;
+		sg = scatterwalk_sg_next(sg);
+	}
+
+	if (sg)
+		scatterwalk_sg_chain(head, 2, sg);
+	else
+		sg_mark_end(head);
+}
+
+static u8 *crypto_authenc_hash(struct aead_request *req, unsigned int flags,
+			       struct scatterlist *cipher,
+			       unsigned int cryptlen)
+{
+	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
+	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
+	struct crypto_hash *auth = ctx->auth;
+	struct hash_desc desc = {
+		.tfm = auth,
+		.flags = aead_request_flags(req) & flags,
+	};
+	u8 *hash = aead_request_ctx(req);
+	int err;
+
+	hash = (u8 *)ALIGN((unsigned long)hash + crypto_hash_alignmask(auth), 
+			   crypto_hash_alignmask(auth) + 1);
+
+	spin_lock_bh(&ctx->auth_lock);
+	err = crypto_hash_init(&desc);
+	if (err)
+		goto auth_unlock;
+
+	err = crypto_hash_update(&desc, req->assoc, req->assoclen);
+	if (err)
+		goto auth_unlock;
+
+	err = crypto_hash_update(&desc, cipher, cryptlen);
+	if (err)
+		goto auth_unlock;
+
+	err = crypto_hash_final(&desc, hash);
+auth_unlock:
+	spin_unlock_bh(&ctx->auth_lock);
+
+	if (err)
+		return ERR_PTR(err);
+
+	return hash;
+}
+
+static int crypto_authenc_genicv(struct aead_request *req, u8 *iv,
+				 unsigned int flags)
+{
+	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
+	struct scatterlist *dst = req->dst;
+	struct scatterlist cipher[2];
+	struct page *dstp;
+	unsigned int ivsize = crypto_aead_ivsize(authenc);
+	unsigned int cryptlen;
+	u8 *vdst;
+	u8 *hash;
+
+	dstp = sg_page(dst);
+	vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;
+
+	sg_init_table(cipher, 2);
+	sg_set_buf(cipher, iv, ivsize);
+	authenc_chain(cipher, dst, vdst == iv + ivsize);
+
+	cryptlen = req->cryptlen + ivsize;
+	hash = crypto_authenc_hash(req, flags, cipher, cryptlen);
+	if (IS_ERR(hash))
+		return PTR_ERR(hash);
+
+	nscatterwalk_map_and_copy(hash, cipher, cryptlen,
+				  crypto_aead_authsize(authenc), 1);
+	return 0;
+}
+
+static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
+					int err)
+{
+	if (!err) {
+		struct aead_request *areq = req->data;
+		struct crypto_aead *authenc = crypto_aead_reqtfm(areq);
+		struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
+		struct ablkcipher_request *abreq = aead_request_ctx(areq);
+		u8 *iv = (u8 *)(abreq + 1) +
+			 crypto_ablkcipher_reqsize(ctx->enc);
+
+		err = crypto_authenc_genicv(areq, iv, 0);
+	}
+
+	aead_request_complete(req->data, err);
+}
+
+static int crypto_authenc_encrypt(struct aead_request *req)
+{
+	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
+	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
+	struct ablkcipher_request *abreq = aead_request_ctx(req);
+	struct crypto_ablkcipher *enc = ctx->enc;
+	struct scatterlist *dst = req->dst;
+	unsigned int cryptlen = req->cryptlen;
+	u8 *iv = (u8 *)(abreq + 1) + crypto_ablkcipher_reqsize(enc);
+	int err;
+
+	ablkcipher_request_set_tfm(abreq, enc);
+	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
+					crypto_authenc_encrypt_done, req);
+	ablkcipher_request_set_crypt(abreq, req->src, dst, cryptlen, req->iv);
+
+	memcpy(iv, req->iv, crypto_aead_ivsize(authenc));
+
+	err = crypto_ablkcipher_encrypt(abreq);
+	if (err)
+		return err;
+
+	return crypto_authenc_genicv(req, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
+}
+
+static void crypto_authenc_givencrypt_done(struct crypto_async_request *req,
+					   int err)
+{
+	if (!err) {
+		struct aead_givcrypt_request *greq = req->data;
+
+		err = crypto_authenc_genicv(&greq->areq, greq->giv, 0);
+	}
+
+	aead_request_complete(req->data, err);
+}
+
+static int crypto_authenc_givencrypt(struct aead_givcrypt_request *req)
+{
+	struct crypto_aead *authenc = aead_givcrypt_reqtfm(req);
+	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
+	struct aead_request *areq = &req->areq;
+	struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
+	u8 *iv = req->giv;
+	int err;
+
+	skcipher_givcrypt_set_tfm(greq, ctx->enc);
+	skcipher_givcrypt_set_callback(greq, aead_request_flags(areq),
+				       crypto_authenc_givencrypt_done, areq);
+	skcipher_givcrypt_set_crypt(greq, areq->src, areq->dst, areq->cryptlen,
+				    areq->iv);
+	skcipher_givcrypt_set_giv(greq, iv, req->seq);
+
+	err = crypto_skcipher_givencrypt(greq);
+	if (err)
+		return err;
+
+	return crypto_authenc_genicv(areq, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
+}
+
+static int crypto_authenc_verify(struct aead_request *req,
+				 struct scatterlist *cipher,
+				 unsigned int cryptlen)
+{
+	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
+	u8 *ohash;
+	u8 *ihash;
+	unsigned int authsize;
+
+	ohash = crypto_authenc_hash(req, CRYPTO_TFM_REQ_MAY_SLEEP, cipher,
+				    cryptlen);
+	if (IS_ERR(ohash))
+		return PTR_ERR(ohash);
+
+	authsize = crypto_aead_authsize(authenc);
+	ihash = ohash + authsize;
+	nscatterwalk_map_and_copy(ihash, cipher, cryptlen, authsize, 0);
+	return memcmp(ihash, ohash, authsize) ? -EBADMSG: 0;
+}
+
+static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
+				  unsigned int cryptlen)
+{
+	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
+	struct scatterlist *src = req->src;
+	struct scatterlist cipher[2];
+	struct page *srcp;
+	unsigned int ivsize = crypto_aead_ivsize(authenc);
+	u8 *vsrc;
+
+	srcp = sg_page(src);
+	vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;
+
+	sg_init_table(cipher, 2);
+	sg_set_buf(cipher, iv, ivsize);
+	authenc_chain(cipher, src, vsrc == iv + ivsize);
+
+	return crypto_authenc_verify(req, cipher, cryptlen + ivsize);
+}
+
+static int crypto_authenc_decrypt(struct aead_request *req)
+{
+	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
+	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
+	struct ablkcipher_request *abreq = aead_request_ctx(req);
+	unsigned int cryptlen = req->cryptlen;
+	unsigned int authsize = crypto_aead_authsize(authenc);
+	u8 *iv = req->iv;
+	int err;
+
+	if (cryptlen < authsize)
+		return -EINVAL;
+	cryptlen -= authsize;
+
+	err = crypto_authenc_iverify(req, iv, cryptlen);
+	if (err)
+		return err;
+
+	ablkcipher_request_set_tfm(abreq, ctx->enc);
+	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
+					req->base.complete, req->base.data);
+	ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen, iv);
+
+	return crypto_ablkcipher_decrypt(abreq);
+}
+
+static int crypto_authenc_init_tfm(struct ncrypto_tfm *tfm)
+{
+	struct crypto_instance *inst = (void *)tfm->__crt_alg;
+	struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
+	struct crypto_authenc_ctx *ctx = ncrypto_tfm_ctx(tfm);
+	struct crypto_hash *auth;
+	struct crypto_ablkcipher *enc;
+	int err;
+
+	auth = crypto_spawn_hash(&ictx->auth);
+	if (IS_ERR(auth))
+		return PTR_ERR(auth);
+
+	enc = crypto_spawn_skcipher(&ictx->enc);
+	err = PTR_ERR(enc);
+	if (IS_ERR(enc))
+		goto err_free_hash;
+
+	ctx->auth = auth;
+	ctx->enc = enc;
+	tfm->crt_aead.reqsize = max_t(unsigned int,
+				      (crypto_hash_alignmask(auth) &
+				       ~(ncrypto_tfm_ctx_alignment() - 1)) +
+				      crypto_hash_digestsize(auth) * 2,
+				      sizeof(struct skcipher_givcrypt_request) +
+				      crypto_ablkcipher_reqsize(enc) +
+				      crypto_ablkcipher_ivsize(enc));
+
+	spin_lock_init(&ctx->auth_lock);
+
+	return 0;
+
+err_free_hash:
+	crypto_free_hash(auth);
+	return err;
+}
+
+static void crypto_authenc_exit_tfm(struct ncrypto_tfm *tfm)
+{
+	struct crypto_authenc_ctx *ctx = ncrypto_tfm_ctx(tfm);
+
+	crypto_free_hash(ctx->auth);
+	crypto_free_ablkcipher(ctx->enc);
+}
+
+static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
+{
+	struct crypto_attr_type *algt;
+	struct crypto_instance *inst;
+	struct ncrypto_alg *auth;
+	struct ncrypto_alg *enc;
+	struct authenc_instance_ctx *ctx;
+	const char *enc_name;
+	int err;
+
+	algt = crypto_get_attr_type(tb);
+	err = PTR_ERR(algt);
+	if (IS_ERR(algt))
+		return ERR_PTR(err);
+
+	if ((algt->type ^ NCRYPTO_ALG_TYPE_AEAD) & algt->mask)
+		return ERR_PTR(-EINVAL);
+
+	auth = crypto_attr_alg(tb[1], NCRYPTO_ALG_TYPE_HASH,
+			       NCRYPTO_ALG_TYPE_HASH_MASK);
+	if (IS_ERR(auth))
+		return ERR_PTR(PTR_ERR(auth));
+
+	enc_name = crypto_attr_alg_name(tb[2]);
+	err = PTR_ERR(enc_name);
+	if (IS_ERR(enc_name))
+		goto out_put_auth;
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
+	err = -ENOMEM;
+	if (!inst)
+		goto out_put_auth;
+
+	ctx = crypto_instance_ctx(inst);
+
+	err = crypto_init_spawn(&ctx->auth, auth, inst, NCRYPTO_ALG_TYPE_MASK);
+	if (err)
+		goto err_free_inst;
+
+	crypto_set_skcipher_spawn(&ctx->enc, inst);
+	err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
+				   crypto_requires_sync(algt->type,
+							algt->mask));
+	if (err)
+		goto err_drop_auth;
+
+	enc = crypto_skcipher_spawn_alg(&ctx->enc);
+
+	err = -ENAMETOOLONG;
+	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
+		     "authenc(%s,%s)", auth->cra_name, enc->cra_name) >=
+	    CRYPTO_MAX_ALG_NAME)
+		goto err_drop_enc;
+
+	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "authenc(%s,%s)", auth->cra_driver_name,
+		     enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
+		goto err_drop_enc;
+
+	inst->alg.cra_flags = NCRYPTO_ALG_TYPE_AEAD;
+	inst->alg.cra_flags |= enc->cra_flags & NCRYPTO_ALG_ASYNC;
+	inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
+	inst->alg.cra_blocksize = enc->cra_blocksize;
+	inst->alg.cra_alignmask = auth->cra_alignmask | enc->cra_alignmask;
+	inst->alg.cra_type = &crypto_aead_type;
+
+	inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;
+	inst->alg.cra_aead.maxauthsize = auth->cra_hash.digestsize;
+
+	inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
+
+	inst->alg.cra_init = crypto_authenc_init_tfm;
+	inst->alg.cra_exit = crypto_authenc_exit_tfm;
+
+	inst->alg.cra_aead.setkey = crypto_authenc_setkey;
+	inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
+	inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;
+	inst->alg.cra_aead.givencrypt = crypto_authenc_givencrypt;
+
+out:
+	crypto_mod_put(auth);
+	return inst;
+
+err_drop_enc:
+	crypto_drop_skcipher(&ctx->enc);
+err_drop_auth:
+	crypto_drop_spawn(&ctx->auth);
+err_free_inst:
+	kfree(inst);
+out_put_auth:
+	inst = ERR_PTR(err);
+	goto out;
+}
+
+static void crypto_authenc_free(struct crypto_instance *inst)
+{
+	struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);
+
+	crypto_drop_skcipher(&ctx->enc);
+	crypto_drop_spawn(&ctx->auth);
+	kfree(inst);
+}
+
+static struct crypto_template crypto_authenc_tmpl = {
+	.name = "authenc",
+	.alloc = crypto_authenc_alloc,
+	.free = crypto_authenc_free,
+	.module = THIS_MODULE,
+};
+
+static int __init crypto_authenc_module_init(void)
+{
+	return crypto_register_template(&crypto_authenc_tmpl);
+}
+
+static void __exit crypto_authenc_module_exit(void)
+{
+	crypto_unregister_template(&crypto_authenc_tmpl);
+}
+
+module_init(crypto_authenc_module_init);
+module_exit(crypto_authenc_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
diff --git a/include/crypto/authenc.h b/include/crypto/authenc.h
new file mode 100644
index 0000000..e47b044
--- /dev/null
+++ b/include/crypto/authenc.h
@@ -0,0 +1,27 @@
+/*
+ * Authenc: Simple AEAD wrapper for IPsec
+ *
+ * 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.
+ *
+ */
+#ifndef _CRYPTO_AUTHENC_H
+#define _CRYPTO_AUTHENC_H
+
+#include <linux/types.h>
+
+enum {
+	CRYPTO_AUTHENC_KEYA_UNSPEC,
+	CRYPTO_AUTHENC_KEYA_PARAM,
+};
+
+struct crypto_authenc_key_param {
+	__be32 enckeylen;
+};
+
+#endif	/* _CRYPTO_AUTHENC_H */
+