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
Signed-off-by: Cristian Stoica <cristian.stoica@xxxxxxxxxxxxx>
---
crypto/Kconfig | 20 ++
crypto/Makefile | 1 +
crypto/authenc.c | 5 +-
crypto/tls.c | 528 +++++++++++++++++++++++++++++++++++++++++++++++
include/crypto/authenc.h | 3 +
5 files changed, 555 insertions(+), 2 deletions(-)
create mode 100644 crypto/tls.c
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 6345c47..54cc843 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -212,6 +212,26 @@ config CRYPTO_SEQIV
This IV generator generates an IV based on a sequence number by
xoring it with a salt. This algorithm is mainly useful for CTR
+config CRYPTO_TLS
+ tristate "TLS support"
+ select CRYPTO_AUTHENC
+ select CRYPTO_AEAD
+ select CRYPTO_BLKCIPHER
+ select CRYPTO_MANAGER
+ select CRYPTO_HASH
+ help
+ Support for TLS record encryption and decryption
+
+ This module adds support for encryption/decryption of TLS frames
+ using blockcipher algorithms. The resulting algorithm is called
+ "tls10(hmac(<digest>),cbc(<cipher>))".
+
+ By default, the generic base algorithms are used (e.g. aes-generic,
+ sha1-generic), but hardware accelerated versions will be used
+ automatically if available.
+ User-space applications (OpenSSL, GnuTLS) can offload TLS operations
+ through AF_ALG or cryptodev interfaces
+
comment "Block modes"
config CRYPTO_CBC
diff --git a/crypto/Makefile b/crypto/Makefile
index cfa57b3..16088d1 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -85,6 +85,7 @@ obj-$(CONFIG_CRYPTO_CRC32C) += crc32c_generic.o
obj-$(CONFIG_CRYPTO_CRC32) += crc32.o
obj-$(CONFIG_CRYPTO_CRCT10DIF) += crct10dif_common.o crct10dif_generic.o
obj-$(CONFIG_CRYPTO_AUTHENC) += authenc.o authencesn.o
+obj-$(CONFIG_CRYPTO_TLS) += tls.o
obj-$(CONFIG_CRYPTO_LZO) += lzo.o
obj-$(CONFIG_CRYPTO_LZ4) += lz4.o
obj-$(CONFIG_CRYPTO_LZ4HC) += lz4hc.o
diff --git a/crypto/authenc.c b/crypto/authenc.c
index e122355..7f6c65d 100644
--- a/crypto/authenc.c
+++ b/crypto/authenc.c
@@ -82,8 +82,8 @@ int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
}
EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
-static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
- unsigned int keylen)
+int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
+ unsigned int keylen)
{
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct crypto_ahash *auth = ctx->auth;
@@ -118,6 +118,7 @@ badkey:
crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
goto out;
}
+EXPORT_SYMBOL_GPL(crypto_authenc_setkey);
static void authenc_geniv_ahash_update_done(struct crypto_async_request *areq,
int err)
diff --git a/crypto/tls.c b/crypto/tls.c
new file mode 100644
index 0000000..b6aedcd
--- /dev/null
+++ b/crypto/tls.c
@@ -0,0 +1,528 @@
+/*
+ * Copyright 2014 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>
+
+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);
+}
+
+/**
+ * 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_sg_chain(icv, 2, src);
+ } 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
+ * @req: (input) aead request
+ **/
+static int crypto_tls_gen_padicv(u8 *hash, unsigned int *phashlen,
+ 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);
+
+ *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 *sg, *src_last = NULL;
+ 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 together with necessary padding
+ */
+ err = crypto_tls_gen_padicv(hash, &phashlen, req);
+ if (err)
+ return err;
+
+ /*
+ * STEP 2: Hash and padding are combined with the payload
+ * depending on the form it arrives. Scatter tables must have at least
+ * one page of data before chaining with another table and can't have
+ * an empty data page. The following code addresses these requirements.
+ *
+ * For same-destination, hash is copied directly after the
+ * payload since the buffers must have enough space for encryption.
+ * For different destination there are several casess to check.
+ * If the payload is empty, only the hash is encrypted, otherwise the
+ * payload scatterlist is merged with the hash. A special merging case
+ * is when the payload has only one page of data. In that case the
+ * payload page is moved to another scatterlist and prepared there for
+ * encryption.
+ */
+
+ if (req->src == req->dst) {
+ scatterwalk_map_and_copy(hash, req->src, req->cryptlen,
+ phashlen, 1);
+ } else {
+ if (req->cryptlen) {
+ sg_init_table(cipher, 2);
+ sg_set_buf(cipher + 1, hash, phashlen);
+ if (sg_is_last(req->src)) {
+ sg_set_page(cipher, sg_page(req->src),
+ req->src->length, req->src->offset);
+ req->src = cipher;
+ } else {
+ for (sg = req->src; sg; sg = sg_next(sg))
+ src_last = sg;
+ sg_set_page(cipher, sg_page(src_last),
+ src_last->length, src_last->offset);
+ scatterwalk_sg_chain(src_last, 1, cipher);
+ }
+ } else {
+ sg_init_one(req->src, hash, phashlen);
+ }
+ }
+
+ /*
+ * STEP 3: encrypt the frame and return the result
+ */
+ cryptlen = req->cryptlen + phashlen;
+ ablkcipher_request_set_tfm(abreq, ctx->enc);
+ ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen,
+ req->iv);
+ /* set the callback for encryption request termination */
+ ablkcipher_request_set_callback(abreq, aead_request_flags(req),
+ req->base.complete, req->base.data);
+ /*
+ * Apply the cipher transform. The result will be in req->dst when the
+ * asynchronuous call terminates
+ */
+ 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 to defend against timing attacks is to continue
+ * with hash calculation even if the padding is incorrect */
+ 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 = crypto_memneq(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_authenc_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_tls10_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_tls10_tmpl);
+}
+
+static void __exit crypto_tls_module_exit(void)
+{
+ crypto_unregister_template(&crypto_tls10_tmpl);
+}
+
+module_init(crypto_tls_module_init);
+module_exit(crypto_tls_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TLS record encryption");
diff --git a/include/crypto/authenc.h b/include/crypto/authenc.h
index 6775059..ef90468 100644
--- a/include/crypto/authenc.h
+++ b/include/crypto/authenc.h
@@ -34,4 +34,7 @@ struct crypto_authenc_keys {
int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
unsigned int keylen);
+int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
+ unsigned int keylen);
+
#endif /* _CRYPTO_AUTHENC_H */
--
1.8.3.1
--
To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
