crypto: add support for TLS 1.0 record encryption

This patch adds kernel support for encryption/decryption of TLS 1.0
records using block ciphers. Implementation is similar to authenc in the
sense that the base algorithms (AES, SHA1) are combined in a template to
produce TLS encapsulation frames. The composite algorithm will be called
"tls10(hmac(<digest>),cbc(<cipher>))". The cipher and hmac keys are
wrapped in the same format used by authenc.c

Change-Id: If2211062f1e8805ee1fe9e6684e7c0902bf44467
Signed-off-by: Cristian Stoica <cristian.stoica@freescale.com>
Reviewed-on: http://git.am.freescale.net:8181/6211
Reviewed-by: Mircea Pop <mircea.pop@freescale.com>
Reviewed-by: Thomas Trefny <Tom.Trefny@freescale.com>
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Jose Rivera <German.Rivera@freescale.com>
(cherry picked from commit e2fe61d3fe94949f9fc5766f7b27a1d19c9d4d6e)

Conflicts:
	crypto/tcrypt.c

Signed-off-by: Horia Geanta <horia.geanta@freescale.com>
Change-Id: I6ecb63c7cb8c64aef984e71e439dab6000666b29
Reviewed-on: http://git.am.freescale.net:8181/10373
Reviewed-by: Cristian Stoica <cristian.stoica@freescale.com>
Reviewed-by: Mircea Pop <mircea.pop@freescale.com>
Reviewed-by: Alexandru Porosanu <alexandru.porosanu@freescale.com>
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Jose Rivera <German.Rivera@freescale.com>

1 files changed, 567 insertions, 0 deletions

diff --git a/crypto/tls.c b/crypto/tls.c
new file mode 100644
index 0000000..18cc536
--- /dev/null
+++ b/crypto/tls.c
@@ -0,0 +1,567 @@
+/*
+ * Copyright 2013 Freescale Semiconductor, Inc.
+ *
+ * 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/hash.h>
+#include <crypto/internal/skcipher.h>
+#include <crypto/authenc.h>
+#include <crypto/scatterwalk.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/rtnetlink.h>
+
+struct tls_instance_ctx {
+	struct crypto_ahash_spawn auth;
+	struct crypto_skcipher_spawn enc;
+};
+
+struct crypto_tls_ctx {
+	unsigned int reqoff;
+	struct crypto_ahash *auth;
+	struct crypto_ablkcipher *enc;
+};
+
+struct tls_request_ctx {
+	/*
+	 * cryptlen holds the payload length in the case of encryption or
+	 * payload_len + icv_len + padding_len in case of decryption
+	 */
+	unsigned int cryptlen;
+	/* working space for partial results */
+	struct scatterlist icv[2];
+	struct scatterlist cipher[2];
+	char tail[];
+};
+
+struct async_op {
+	struct completion completion;
+	int err;
+};
+
+static void tls_async_op_done(struct crypto_async_request *req, int err)
+{
+	struct async_op *areq = req->data;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	areq->err = err;
+	complete(&areq->completion);
+}
+
+static void tls_request_done(struct crypto_async_request *req, int err)
+{
+	/* Mark the completion of the TLS request */
+	struct aead_request *areq = req->data;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	aead_request_complete(areq, err);
+}
+
+static int crypto_tls_setkey(struct crypto_aead *tls, const u8 *key,
+				 unsigned int keylen)
+{
+	unsigned int authkeylen;
+	unsigned int enckeylen;
+	struct crypto_tls_ctx *ctx = crypto_aead_ctx(tls);
+	struct crypto_ahash *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_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
+	crypto_ahash_set_flags(auth, crypto_aead_get_flags(tls) &
+				    CRYPTO_TFM_REQ_MASK);
+	err = crypto_ahash_setkey(auth, key, authkeylen);
+	crypto_aead_set_flags(tls, crypto_ahash_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(tls) &
+					 CRYPTO_TFM_REQ_MASK);
+	err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
+	crypto_aead_set_flags(tls, crypto_ablkcipher_get_flags(enc) &
+				       CRYPTO_TFM_RES_MASK);
+out:
+	return err;
+
+badkey:
+	crypto_aead_set_flags(tls, CRYPTO_TFM_RES_BAD_KEY_LEN);
+	goto out;
+}
+
+/**
+ * crypto_tls_genicv - Calculate hmac digest for a TLS record
+ * @hash:	(output) buffer to save the digest into
+ * @src:	(input) scatterlist with the payload data
+ * @srclen:	(input) size of the payload data
+ * @req:	(input) aead request (with pointers to associated data)
+ **/
+static int crypto_tls_genicv(u8 *hash, struct scatterlist *src,
+			     unsigned int srclen, struct aead_request *req)
+{
+	struct crypto_aead *tls = crypto_aead_reqtfm(req);
+	struct crypto_tls_ctx *ctx = crypto_aead_ctx(tls);
+	struct tls_request_ctx *treq_ctx = aead_request_ctx(req);
+	struct scatterlist *assoc = req->assoc;
+	struct scatterlist *icv = treq_ctx->icv;
+	struct async_op ahash_op;
+	struct ahash_request *ahreq = (void *)(treq_ctx->tail + ctx->reqoff);
+	unsigned int flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+	int err = -EBADMSG;
+
+	/*
+	 * Bail out as we have only two maneuvering scatterlists in icv. Check
+	 * also if the request assoc len matches the scatterlist len
+	 */
+	if (!req->assoclen || !sg_is_last(assoc) ||
+	    req->assoclen != assoc->length)
+		return err;
+
+	/*
+	 * Prepend associated data to the source scatterlist. If the source is
+	 * empty, use directly the associated data scatterlist
+	 */
+	if (srclen) {
+		sg_init_table(icv, 2);
+		sg_set_page(icv, sg_page(assoc), assoc->length, assoc->offset);
+		scatterwalk_crypto_chain(icv, src, 0, 2);
+	} else {
+		icv = assoc;
+	}
+	srclen += assoc->length;
+
+	init_completion(&ahash_op.completion);
+
+	/* the hash transform to be executed comes from the original request */
+	ahash_request_set_tfm(ahreq, ctx->auth);
+	/* prepare the hash request with input data and result pointer */
+	ahash_request_set_crypt(ahreq, icv, hash, srclen);
+	/* set the notifier for when the async hash function returns */
+	ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
+				   tls_async_op_done, &ahash_op);
+
+	/* Calculate the digest on the given data. The result is put in hash */
+	err = crypto_ahash_digest(ahreq);
+	if (err == -EINPROGRESS) {
+		err = wait_for_completion_interruptible(&ahash_op.completion);
+		if (!err)
+			err = ahash_op.err;
+	}
+
+	return err;
+}
+
+/**
+ * crypto_tls_gen_padicv - Calculate and pad hmac digest for a TLS record
+ * @hash:	(output) buffer to save the digest and padding into
+ * @phashlen:	(output) the size of digest + padding
+ * @cryptlen:	(output) the size of the total frame to be encrypted
+ * @req:	(input) aead request
+ **/
+static int crypto_tls_gen_padicv(u8 *hash, unsigned int *phashlen,
+			     unsigned int *cryptlen, struct aead_request *req)
+{
+	struct crypto_aead *tls = crypto_aead_reqtfm(req);
+	unsigned int hash_size = crypto_aead_authsize(tls);
+	unsigned int block_size = crypto_aead_blocksize(tls);
+	unsigned int srclen = req->cryptlen + hash_size;
+	unsigned int padlen;
+	int err;
+
+	err = crypto_tls_genicv(hash, req->src, req->cryptlen, req);
+	if (err)
+		goto out;
+
+	/* add padding after digest */
+	padlen = block_size - (srclen % block_size);
+	memset(hash + hash_size, padlen - 1, padlen);
+
+	/* save the frame length to be encrypted */
+	*cryptlen = srclen + padlen;
+	*phashlen = hash_size + padlen;
+out:
+	return err;
+}
+
+static int crypto_tls_encrypt(struct aead_request *req)
+{
+	struct crypto_aead *tls = crypto_aead_reqtfm(req);
+	struct crypto_tls_ctx *ctx = crypto_aead_ctx(tls);
+	struct tls_request_ctx *treq_ctx = aead_request_ctx(req);
+
+	unsigned int cryptlen, phashlen;
+	struct scatterlist *cipher = treq_ctx->cipher;
+	struct scatterlist *icv = treq_ctx->icv;
+	int err;
+	/*
+	 * The hash and the cipher are applied at different times and their
+	 * requests can use the same memory space without interference
+	 */
+	struct ablkcipher_request *abreq = (void *)(treq_ctx->tail +
+						    ctx->reqoff);
+	/*
+	 * The hash result is saved at the beginning of the tls request and is
+	 * aligned as required by the hash transform. Enough space was
+	 * allocated in crypto_tls_init_tfm to accomodate the difference. The
+	 * requests themselves start later at treq_ctx->tail + ctx->reqoff so
+	 * the result is not overwritten by the second (cipher) request
+	 */
+	u8 *hash = treq_ctx->tail;
+	hash = (u8 *)ALIGN((unsigned long)hash +
+			   crypto_ahash_alignmask(ctx->auth),
+			   crypto_ahash_alignmask(ctx->auth) + 1);
+
+	/*
+	 * STEP 1: create ICV and add necessary padding
+	 */
+	err = crypto_tls_gen_padicv(hash, &phashlen, &cryptlen, req);
+	if (err)
+		return err;
+
+	/* we can reuse treq_cfr->icv because crypto_tls_gen_padicv finished */
+	sg_init_one(icv, hash, phashlen);
+
+	/*
+	 * STEP 2: encrypt the frame and return the result
+	 * Chain the payload with the hash. If the payload is empty, use
+	 * directly the hash scatterlist
+	 */
+	if (req->cryptlen) {
+		sg_init_table(cipher, 2);
+		sg_set_page(cipher, sg_page(req->src), req->cryptlen,
+			    req->src->offset);
+		scatterwalk_crypto_chain(cipher, icv, 0, 2);
+	} else {
+		cipher = icv;
+	}
+	/* prepare the cipher request */
+	ablkcipher_request_set_tfm(abreq, ctx->enc);
+	ablkcipher_request_set_crypt(abreq, cipher, req->dst, cryptlen,
+				     req->iv);
+	/* mark the completion of the whole encryption request */
+	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
+					tls_request_done, req);
+	/* Apply the cipher transform. The result will be in req->dst */
+	err = crypto_ablkcipher_encrypt(abreq);
+
+	return err;
+}
+
+static int crypto_tls_decrypt(struct aead_request *req)
+{
+	struct crypto_aead *tls = crypto_aead_reqtfm(req);
+	struct crypto_tls_ctx *ctx = crypto_aead_ctx(tls);
+	struct tls_request_ctx *treq_ctx = aead_request_ctx(req);
+	struct scatterlist *assoc = req->assoc;
+	unsigned int cryptlen = req->cryptlen;
+	unsigned int hash_size = crypto_aead_authsize(tls);
+	unsigned int block_size = crypto_aead_blocksize(tls);
+	struct ablkcipher_request *abreq = (void *)(treq_ctx->tail +
+						    ctx->reqoff);
+	u8 padding[255]; /* padding can be 0-255 bytes */
+	u8 pad_size;
+	u16 *len_field;
+	u8 *ihash, *hash = treq_ctx->tail;
+
+	int paderr = 0;
+	int err = -EINVAL;
+	int i;
+	struct async_op ciph_op;
+
+	/*
+	 * Rule out bad packets. The input packet length must be at least one
+	 * byte more than the hash_size
+	 */
+	if (cryptlen <= hash_size || cryptlen % block_size)
+		goto out;
+
+	/*
+	 * Step 1 - Decrypt the source
+	 */
+	init_completion(&ciph_op.completion);
+
+	ablkcipher_request_set_tfm(abreq, ctx->enc);
+	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
+					tls_async_op_done, &ciph_op);
+	ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen,
+				     req->iv);
+	err = crypto_ablkcipher_decrypt(abreq);
+	if (err == -EINPROGRESS) {
+		err = wait_for_completion_interruptible(&ciph_op.completion);
+		if (!err)
+			err = ciph_op.err;
+	}
+	if (err)
+		goto out;
+
+	/*
+	 * Step 2 - Verify padding
+	 * Retrieve the last byte of the payload; this is the padding size
+	 */
+	cryptlen -= 1;
+	scatterwalk_map_and_copy(&pad_size, req->dst, cryptlen, 1, 0);
+
+	/* RFC recommendation for invalid padding size */
+	if (cryptlen < pad_size + hash_size) {
+		pad_size = 0;
+		paderr = -EBADMSG;
+	}
+	cryptlen -= pad_size;
+	scatterwalk_map_and_copy(padding, req->dst, cryptlen, pad_size, 0);
+
+	/* Padding content must be equal with pad_size. We verify it all */
+	for (i = 0; i < pad_size; i++)
+		if (padding[i] != pad_size)
+			paderr = -EBADMSG;
+
+	/*
+	 * Step 3 - Verify hash
+	 * Align the digest result as required by the hash transform. Enough
+	 * space was allocated in crypto_tls_init_tfm
+	 */
+	hash = (u8 *)ALIGN((unsigned long)hash +
+			   crypto_ahash_alignmask(ctx->auth),
+			   crypto_ahash_alignmask(ctx->auth) + 1);
+	/*
+	 * Two bytes at the end of the associated data make the length field.
+	 * It must be updated with the length of the cleartext message before
+	 * the hash is calculated.
+	 */
+	len_field = sg_virt(assoc) + assoc->length - 2;
+	cryptlen -= hash_size;
+	*len_field = htons(cryptlen);
+
+	/* This is the hash from the decrypted packet. Save it for later */
+	ihash = hash + hash_size;
+	scatterwalk_map_and_copy(ihash, req->dst, cryptlen, hash_size, 0);
+
+	/* Now compute and compare our ICV with the one from the packet */
+	err = crypto_tls_genicv(hash, req->dst, cryptlen, req);
+	if (!err)
+		err = memcmp(hash, ihash, hash_size) ? -EBADMSG : 0;
+
+	/* return the first found error */
+	if (paderr)
+		err = paderr;
+
+out:
+	aead_request_complete(req, err);
+	return err;
+}
+
+static int crypto_tls_init_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_instance *inst = crypto_tfm_alg_instance(tfm);
+	struct tls_instance_ctx *ictx = crypto_instance_ctx(inst);
+	struct crypto_tls_ctx *ctx = crypto_tfm_ctx(tfm);
+	struct crypto_ahash *auth;
+	struct crypto_ablkcipher *enc;
+	int err;
+
+	auth = crypto_spawn_ahash(&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_ahash;
+
+	ctx->auth = auth;
+	ctx->enc = enc;
+	/*
+	 * Allow enough space for two digests. The two digests will be compared
+	 * during the decryption phase. One will come from the decrypted packet
+	 * and the other will be calculated. For encryption, one digest is
+	 * padded (up to a cipher blocksize) and chained with the payload
+	 */
+	ctx->reqoff = ALIGN(crypto_ahash_digestsize(auth) +
+			    crypto_ahash_alignmask(auth),
+			    crypto_ahash_alignmask(auth) + 1) +
+		      max(crypto_ahash_digestsize(auth),
+			  crypto_ablkcipher_blocksize(enc));
+
+	tfm->crt_aead.reqsize = sizeof(struct tls_request_ctx) + ctx->reqoff +
+		max_t(unsigned int,
+		      crypto_ahash_reqsize(auth) +
+		      sizeof(struct ahash_request),
+		      crypto_ablkcipher_reqsize(enc) +
+		      sizeof(struct ablkcipher_request));
+
+	return 0;
+
+err_free_ahash:
+	crypto_free_ahash(auth);
+	return err;
+}
+
+static void crypto_tls_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_tls_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_ahash(ctx->auth);
+	crypto_free_ablkcipher(ctx->enc);
+}
+
+static struct crypto_instance *crypto_tls_alloc(struct rtattr **tb)
+{
+	struct crypto_attr_type *algt;
+	struct crypto_instance *inst;
+	struct hash_alg_common *auth;
+	struct crypto_alg *auth_base;
+	struct crypto_alg *enc;
+	struct tls_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 ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
+		return ERR_PTR(-EINVAL);
+
+	auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
+			       CRYPTO_ALG_TYPE_AHASH_MASK);
+	if (IS_ERR(auth))
+		return ERR_CAST(auth);
+
+	auth_base = &auth->base;
+
+	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_ahash_spawn(&ctx->auth, auth, inst);
+	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,
+		     "tls10(%s,%s)", auth_base->cra_name, enc->cra_name) >=
+	    CRYPTO_MAX_ALG_NAME)
+		goto err_drop_enc;
+
+	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "tls10(%s,%s)", auth_base->cra_driver_name,
+		     enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
+		goto err_drop_enc;
+
+	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
+	inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;
+	/* priority calculation is taken from authenc.c */
+	inst->alg.cra_priority = enc->cra_priority * 10 +
+				 auth_base->cra_priority;
+	inst->alg.cra_blocksize = enc->cra_blocksize;
+	inst->alg.cra_alignmask = auth_base->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->digestsize;
+
+	inst->alg.cra_ctxsize = sizeof(struct crypto_tls_ctx);
+
+	inst->alg.cra_init = crypto_tls_init_tfm;
+	inst->alg.cra_exit = crypto_tls_exit_tfm;
+
+	inst->alg.cra_aead.setkey = crypto_tls_setkey;
+	inst->alg.cra_aead.encrypt = crypto_tls_encrypt;
+	inst->alg.cra_aead.decrypt = crypto_tls_decrypt;
+
+out:
+	crypto_mod_put(auth_base);
+	return inst;
+
+err_drop_enc:
+	crypto_drop_skcipher(&ctx->enc);
+err_drop_auth:
+	crypto_drop_ahash(&ctx->auth);
+err_free_inst:
+	kfree(inst);
+out_put_auth:
+	inst = ERR_PTR(err);
+	goto out;
+}
+
+static void crypto_tls_free(struct crypto_instance *inst)
+{
+	struct tls_instance_ctx *ctx = crypto_instance_ctx(inst);
+
+	crypto_drop_skcipher(&ctx->enc);
+	crypto_drop_ahash(&ctx->auth);
+	kfree(inst);
+}
+
+static struct crypto_template crypto_tls_tmpl = {
+	.name = "tls10",
+	.alloc = crypto_tls_alloc,
+	.free = crypto_tls_free,
+	.module = THIS_MODULE,
+};
+
+static int __init crypto_tls_module_init(void)
+{
+	return crypto_register_template(&crypto_tls_tmpl);
+}
+
+static void __exit crypto_tls_module_exit(void)
+{
+	crypto_unregister_template(&crypto_tls_tmpl);
+}
+
+module_init(crypto_tls_module_init);
+module_exit(crypto_tls_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TLS 1.0 record encryption");