[PATCH 8/8] [CRYPTO] aead: Add authenc

[Herbert Xu <herbert@gondor.apana.org.au>]

[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 four parameters:

	authenc(auth, authsize, enc, enckeylen).

The authentication algorithm, the authentication size (i.e., truncating
the output of the authentication algorithm), the encryption algorithm,
and the encryption key length.  Both the size field and the key length
field are in bytes.  For example, AES-128 with SHA1-HMAC would be
represented by

	authenc(hmac(sha1), 12, cbc(aes), 16)

The key for the authenc algorithm is the concatenation of the keys for
the authentication algorithm with the encryption algorithm.  For the
above example, if a key of length 36 bytes is given, then hmac(sha1)
would receive the first 20 bytes while the last 16 would be given to
cbc(aes).

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

 crypto/Kconfig          |    8 
 crypto/Makefile         |    1 
 crypto/algapi.c         |   23 ++
 crypto/authenc.c        |  400 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/crypto/algapi.h |   44 +++++
 5 files changed, 472 insertions(+), 4 deletions(-)

diff --git a/crypto/Kconfig b/crypto/Kconfig
index a83d349..71bfa51 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -469,6 +469,14 @@ config CRYPTO_TEST
 	help
 	  Quick & dirty crypto test module.
 
+config CRYPTO_AUTHENC
+	tristate "Authenc support"
+	select CRYPTO_AEAD
+	select CRYPTO_MANAGER
+	help
+	  Authenc: Combined mode wrapper for IPsec.
+	  This is required for IPSec.
+
 source "drivers/crypto/Kconfig"
 
 endif	# if CRYPTO
diff --git a/crypto/Makefile b/crypto/Makefile
index 5c015cc..ba8841e 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -49,6 +49,7 @@ 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/algapi.c b/crypto/algapi.c
index d955960..d891f56 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -470,9 +470,8 @@ int crypto_check_attr_type(struct rtattr **tb, u32 type)
 }
 EXPORT_SYMBOL_GPL(crypto_check_attr_type);
 
-struct crypto_alg *crypto_get_attr_alg(struct rtattr **tb, u32 type, u32 mask)
+struct crypto_alg *crypto_attr_alg(struct rtattr *rta, u32 type, u32 mask)
 {
-	struct rtattr *rta = tb[1];
 	struct crypto_attr_alg *alga;
 
 	if (!rta)
@@ -487,7 +486,25 @@ struct crypto_alg *crypto_get_attr_alg(struct rtattr **tb, u32 type, u32 mask)
 
 	return crypto_alg_mod_lookup(alga->name, type, mask);
 }
-EXPORT_SYMBOL_GPL(crypto_get_attr_alg);
+EXPORT_SYMBOL_GPL(crypto_attr_alg);
+
+int crypto_attr_u32(struct rtattr *rta, u32 *num)
+{
+	struct crypto_attr_u32 *nu32;
+
+	if (!rta)
+		return -ENOENT;
+	if (RTA_PAYLOAD(rta) < sizeof(*nu32))
+		return -EINVAL;
+	if (rta->rta_type != CRYPTOA_U32)
+		return -EINVAL;
+
+	nu32 = RTA_DATA(rta);
+	*num = nu32->num;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_attr_u32);
 
 struct crypto_instance *crypto_alloc_instance(const char *name,
 					      struct crypto_alg *alg)
diff --git a/crypto/authenc.c b/crypto/authenc.c
new file mode 100644
index 0000000..86b3ac8
--- /dev/null
+++ b/crypto/authenc.c
@@ -0,0 +1,400 @@
+/*
+ * 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/algapi.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "scatterwalk.h"
+
+struct authenc_instance_ctx {
+	struct crypto_spawn auth;
+	struct crypto_spawn enc;
+
+	unsigned int authsize;
+	unsigned int enckeylen;
+};
+
+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)
+{
+	struct authenc_instance_ctx *ictx =
+		crypto_instance_ctx(crypto_aead_alg_instance(authenc));
+	unsigned int enckeylen = ictx->enckeylen;
+	unsigned int authkeylen;
+	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
+	struct crypto_hash *auth = ctx->auth;
+	struct crypto_ablkcipher *enc = ctx->enc;
+	int err = -EINVAL;
+
+	if (keylen < enckeylen) {
+		crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
+		goto out;
+	}
+	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;
+}
+
+static int crypto_authenc_hash(struct aead_request *req)
+{
+	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
+	struct authenc_instance_ctx *ictx =
+		crypto_instance_ctx(crypto_aead_alg_instance(authenc));
+	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
+	struct crypto_hash *auth = ctx->auth;
+	struct hash_desc desc = {
+		.tfm = auth,
+	};
+	u8 *hash = aead_request_ctx(req);
+	struct scatterlist *dst;
+	unsigned int cryptlen;
+	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;
+
+	cryptlen = req->cryptlen;
+	dst = req->dst;
+	err = crypto_hash_update(&desc, dst, cryptlen);
+	if (err)
+		goto auth_unlock;
+
+	err = crypto_hash_final(&desc, hash);
+auth_unlock:
+	spin_unlock_bh(&ctx->auth_lock);
+
+	if (err)
+		return err;
+
+	scatterwalk_map_and_copy(hash, dst, cryptlen, ictx->authsize, 1);
+	return 0;
+}
+
+static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
+					int err)
+{
+	if (!err)
+		err = crypto_authenc_hash(req->data);
+
+	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);
+	int err;
+
+	ablkcipher_request_set_tfm(abreq, ctx->enc);
+	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
+					crypto_authenc_encrypt_done, req);
+	ablkcipher_request_set_crypt(abreq, req->src, req->dst, req->cryptlen,
+				     req->iv);
+
+	err = crypto_ablkcipher_encrypt(abreq);
+	if (err)
+		return err;
+
+	return crypto_authenc_hash(req);
+}
+
+static int crypto_authenc_verify(struct aead_request *req)
+{
+	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
+	struct authenc_instance_ctx *ictx =
+		crypto_instance_ctx(crypto_aead_alg_instance(authenc));
+	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),
+	};
+	u8 *ohash = aead_request_ctx(req);
+	u8 *ihash;
+	struct scatterlist *src;
+	unsigned int cryptlen;
+	unsigned int authsize;
+	int err;
+
+	ohash = (u8 *)ALIGN((unsigned long)ohash + crypto_hash_alignmask(auth), 
+			    crypto_hash_alignmask(auth) + 1);
+	ihash = ohash + crypto_hash_digestsize(auth);
+
+	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;
+
+	cryptlen = req->cryptlen;
+	src = req->src;
+	err = crypto_hash_update(&desc, src, cryptlen);
+	if (err)
+		goto auth_unlock;
+
+	err = crypto_hash_final(&desc, ohash);
+auth_unlock:
+	spin_unlock_bh(&ctx->auth_lock);
+
+	if (err)
+		return err;
+
+	authsize = ictx->authsize;
+	scatterwalk_map_and_copy(ihash, src, cryptlen, authsize, 0);
+	return memcmp(ihash, ohash, authsize) ? -EINVAL : 0;
+}
+
+static void crypto_authenc_decrypt_done(struct crypto_async_request *req,
+					int err)
+{
+	aead_request_complete(req->data, err);
+}
+
+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);
+	int err;
+
+	err = crypto_authenc_verify(req);
+	if (err)
+		return err;
+
+	ablkcipher_request_set_tfm(abreq, ctx->enc);
+	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
+					crypto_authenc_decrypt_done, req);
+	ablkcipher_request_set_crypt(abreq, req->src, req->dst, req->cryptlen,
+				     req->iv);
+
+	return crypto_ablkcipher_decrypt(abreq);
+}
+
+static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_instance *inst = (void *)tfm->__crt_alg;
+	struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
+	struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
+	struct crypto_hash *auth;
+	struct crypto_ablkcipher *enc;
+	unsigned int digestsize;
+	int err;
+
+	auth = crypto_spawn_hash(&ictx->auth);
+	if (IS_ERR(auth))
+		return PTR_ERR(auth);
+
+	err = -EINVAL;
+	digestsize = crypto_hash_digestsize(auth);
+	if (ictx->authsize > digestsize)
+		goto err_free_hash;
+
+	enc = crypto_spawn_ablkcipher(&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) &
+				       ~(crypto_tfm_ctx_alignment() - 1)) +
+				      digestsize * 2,
+				      sizeof(struct ablkcipher_request) +
+				      crypto_ablkcipher_reqsize(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 crypto_tfm *tfm)
+{
+	struct crypto_authenc_ctx *ctx = crypto_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_instance *inst;
+	struct crypto_alg *auth;
+	struct crypto_alg *enc;
+	struct authenc_instance_ctx *ctx;
+	unsigned int authsize;
+	unsigned int enckeylen;
+	int err;
+
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD);
+	if (err)
+		return ERR_PTR(err);
+
+	auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
+			       CRYPTO_ALG_TYPE_HASH_MASK);
+	if (IS_ERR(auth))
+		return ERR_PTR(PTR_ERR(auth));
+
+	err = crypto_attr_u32(tb[2], &authsize);
+	inst = ERR_PTR(err);
+	if (err)
+		goto out_put_auth;
+
+	enc = crypto_attr_alg(tb[3], CRYPTO_ALG_TYPE_BLKCIPHER,
+			      CRYPTO_ALG_TYPE_MASK);
+	inst = ERR_PTR(PTR_ERR(enc));
+	if (IS_ERR(enc))
+		goto out_put_auth;
+
+	err = crypto_attr_u32(tb[4], &enckeylen);
+	if (err)
+		goto out_put_enc;
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
+	err = -ENOMEM;
+	if (!inst)
+		goto out_put_enc;
+
+	err = -ENAMETOOLONG;
+	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
+		     "authenc(%s, %u, %s, %u)", auth->cra_name, authsize,
+		     enc->cra_name, enckeylen) >= CRYPTO_MAX_ALG_NAME)
+		goto err_free_inst;
+
+	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "authenc(%s, %u, %s, %u)", auth->cra_driver_name,
+		     authsize, enc->cra_driver_name, enckeylen) >=
+	    CRYPTO_MAX_ALG_NAME)
+		goto err_free_inst;
+
+	ctx = crypto_instance_ctx(inst);
+	ctx->authsize = authsize;
+	ctx->enckeylen = enckeylen;
+
+	err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
+	if (err)
+		goto err_free_inst;
+
+	err = crypto_init_spawn(&ctx->enc, enc, inst, CRYPTO_ALG_TYPE_MASK);
+	if (err)
+		goto err_drop_auth;
+
+	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC;
+	inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
+	inst->alg.cra_blocksize = enc->cra_blocksize;
+	inst->alg.cra_alignmask = max(auth->cra_alignmask, enc->cra_alignmask);
+	inst->alg.cra_type = &crypto_aead_type;
+
+	inst->alg.cra_aead.ivsize = enc->cra_blkcipher.ivsize;
+	inst->alg.cra_aead.authsize = authsize;
+
+	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;
+
+out:
+	crypto_mod_put(enc);
+out_put_auth:
+	crypto_mod_put(auth);
+	return inst;
+
+err_drop_auth:
+	crypto_drop_spawn(&ctx->auth);
+err_free_inst:
+	kfree(inst);
+out_put_enc:
+	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_spawn(&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/algapi.h b/include/crypto/algapi.h
index cd721a7..4af72dc 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -112,7 +112,8 @@ struct crypto_tfm *crypto_spawn_tfm(struct crypto_spawn *spawn, u32 type,
 
 struct crypto_attr_type *crypto_get_attr_type(struct rtattr **tb);
 int crypto_check_attr_type(struct rtattr **tb, u32 type);
-struct crypto_alg *crypto_get_attr_alg(struct rtattr **tb, u32 type, u32 mask);
+struct crypto_alg *crypto_attr_alg(struct rtattr *rta, u32 type, u32 mask);
+int crypto_attr_u32(struct rtattr *rta, u32 *num);
 struct crypto_instance *crypto_alloc_instance(const char *name,
 					      struct crypto_alg *alg);
 
@@ -171,6 +172,26 @@ static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
 	return &crypto_aead_tfm(tfm)->__crt_alg->cra_aead;
 }
 
+static inline void *crypto_aead_ctx(struct crypto_aead *tfm)
+{
+	return crypto_tfm_ctx(&tfm->base);
+}
+
+static inline struct crypto_instance *crypto_aead_alg_instance(
+	struct crypto_aead *aead)
+{
+	return crypto_tfm_alg_instance(&aead->base);
+}
+
+static inline struct crypto_ablkcipher *crypto_spawn_ablkcipher(
+	struct crypto_spawn *spawn)
+{
+	u32 type = CRYPTO_ALG_TYPE_BLKCIPHER;
+	u32 mask = CRYPTO_ALG_TYPE_MASK;
+
+	return __crypto_ablkcipher_cast(crypto_spawn_tfm(spawn, type, mask));
+}
+
 static inline struct crypto_blkcipher *crypto_spawn_blkcipher(
 	struct crypto_spawn *spawn)
 {
@@ -257,5 +278,26 @@ static inline int ablkcipher_tfm_in_queue(struct crypto_queue *queue,
 	return crypto_tfm_in_queue(queue, crypto_ablkcipher_tfm(tfm));
 }
 
+static inline void *aead_request_ctx(struct aead_request *req)
+{
+	return req->__ctx;
+}
+
+static inline void aead_request_complete(struct aead_request *req, int err)
+{
+	req->base.complete(&req->base, err);
+}
+
+static inline u32 aead_request_flags(struct aead_request *req)
+{
+	return req->base.flags;
+}
+
+static inline struct crypto_alg *crypto_get_attr_alg(struct rtattr **tb,
+						     u32 type, u32 mask)
+{
+	return crypto_attr_alg(tb[1], type, mask);
+}
+
 #endif	/* _CRYPTO_ALGAPI_H */