diff options
Diffstat (limited to 'crypto/tls.c')
| -rw-r--r-- | crypto/tls.c | 607 |
1 files changed, 607 insertions, 0 deletions
diff --git a/crypto/tls.c b/crypto/tls.c new file mode 100644 index 0000000..1700fb9 --- /dev/null +++ b/crypto/tls.c @@ -0,0 +1,607 @@ +/* + * Copyright 2013 Freescale Semiconductor, Inc. + * Copyright 2017 NXP + * + * 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/internal/hash.h> +#include <crypto/internal/skcipher.h> +#include <crypto/authenc.h> +#include <crypto/null.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_skcipher *enc; + struct crypto_skcipher *null; +}; + +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 tmp[2]; + struct scatterlist cipher[2]; + struct scatterlist dst[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 int crypto_tls_setkey(struct crypto_aead *tls, const u8 *key, + unsigned int keylen) +{ + struct crypto_tls_ctx *ctx = crypto_aead_ctx(tls); + struct crypto_ahash *auth = ctx->auth; + struct crypto_skcipher *enc = ctx->enc; + struct crypto_authenc_keys keys; + int err = -EINVAL; + + if (crypto_authenc_extractkeys(&keys, key, keylen) != 0) + goto badkey; + + 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, keys.authkey, keys.authkeylen); + crypto_aead_set_flags(tls, crypto_ahash_get_flags(auth) & + CRYPTO_TFM_RES_MASK); + + if (err) + goto out; + + crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK); + crypto_skcipher_set_flags(enc, crypto_aead_get_flags(tls) & + CRYPTO_TFM_REQ_MASK); + err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen); + crypto_aead_set_flags(tls, crypto_skcipher_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 assoc and payload data + * @srclen: (input) size of the source buffer (assoclen + cryptlen) + * @req: (input) aead request + **/ +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 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 if the request assoc len is 0 */ + if (!req->assoclen) + return err; + + 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, src, 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 icvlen = req->cryptlen + req->assoclen; + unsigned int padlen; + int err; + + err = crypto_tls_genicv(hash, req->src, icvlen, 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_copy_data(struct aead_request *req, + struct scatterlist *src, + struct scatterlist *dst, + unsigned int len) +{ + struct crypto_aead *tls = crypto_aead_reqtfm(req); + struct crypto_tls_ctx *ctx = crypto_aead_ctx(tls); + SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null); + + skcipher_request_set_tfm(skreq, ctx->null); + skcipher_request_set_callback(skreq, aead_request_flags(req), + NULL, NULL); + skcipher_request_set_crypt(skreq, src, dst, len, NULL); + + return crypto_skcipher_encrypt(skreq); +} + +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); + struct skcipher_request *skreq; + struct scatterlist *cipher = treq_ctx->cipher; + struct scatterlist *tmp = treq_ctx->tmp; + struct scatterlist *sg, *src, *dst; + unsigned int cryptlen, phashlen; + u8 *hash = treq_ctx->tail; + int err; + + /* + * The hash result is saved at the beginning of the tls request ctx + * and is aligned as required by the hash transform. Enough space was + * allocated in crypto_tls_init_tfm to accommodate the difference. The + * requests themselves start later at treq_ctx->tail + ctx->reqoff so + * the result is not overwritten by the second (cipher) request. + */ + 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. + * + * 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->cryptlen) { + src = scatterwalk_ffwd(tmp, req->src, req->assoclen); + + sg_init_table(cipher, 2); + sg_set_buf(cipher + 1, hash, phashlen); + + if (sg_is_last(src)) { + sg_set_page(cipher, sg_page(src), req->cryptlen, + src->offset); + src = cipher; + } else { + unsigned int rem_len = req->cryptlen; + + for (sg = src; rem_len > sg->length; sg = sg_next(sg)) + rem_len -= min(rem_len, sg->length); + + sg_set_page(cipher, sg_page(sg), rem_len, sg->offset); + sg_chain(sg, 1, cipher); + } + } else { + sg_init_one(cipher, hash, phashlen); + src = cipher; + } + + /** + * If src != dst copy the associated data from source to destination. + * In both cases fast-forward passed the associated data in the dest. + */ + if (req->src != req->dst) { + err = crypto_tls_copy_data(req, req->src, req->dst, + req->assoclen); + if (err) + return err; + } + dst = scatterwalk_ffwd(treq_ctx->dst, req->dst, req->assoclen); + + /* + * STEP 3: encrypt the frame and return the result + */ + cryptlen = req->cryptlen + phashlen; + + /* + * The hash and the cipher are applied at different times and their + * requests can use the same memory space without interference + */ + skreq = (void *)(treq_ctx->tail + ctx->reqoff); + skcipher_request_set_tfm(skreq, ctx->enc); + skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv); + skcipher_request_set_callback(skreq, 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_skcipher_encrypt(skreq); + + 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); + unsigned int cryptlen = req->cryptlen; + unsigned int hash_size = crypto_aead_authsize(tls); + unsigned int block_size = crypto_aead_blocksize(tls); + struct skcipher_request *skreq = (void *)(treq_ctx->tail + ctx->reqoff); + struct scatterlist *tmp = treq_ctx->tmp; + struct scatterlist *src, *dst; + + 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. Fast-forward past the associated data + * to the encrypted data. The result will be overwritten in place so + * that the decrypted data will be adjacent to the associated data. The + * last step (computing the hash) will have it's input data already + * prepared and ready to be accessed at req->src. + */ + src = scatterwalk_ffwd(tmp, req->src, req->assoclen); + dst = src; + + init_completion(&ciph_op.completion); + skcipher_request_set_tfm(skreq, ctx->enc); + skcipher_request_set_callback(skreq, aead_request_flags(req), + tls_async_op_done, &ciph_op); + skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv); + err = crypto_skcipher_decrypt(skreq); + 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, 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, 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(req->src) + req->assoclen - 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, dst, cryptlen, hash_size, 0); + + /* Now compute and compare our ICV with the one from the packet */ + err = crypto_tls_genicv(hash, req->src, cryptlen + req->assoclen, req); + if (!err) + err = memcmp(hash, ihash, hash_size) ? -EBADMSG : 0; + + if (req->src != req->dst) { + err = crypto_tls_copy_data(req, req->src, req->dst, cryptlen + + req->assoclen); + if (err) + goto out; + } + + /* 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_aead *tfm) +{ + struct aead_instance *inst = aead_alg_instance(tfm); + struct tls_instance_ctx *ictx = aead_instance_ctx(inst); + struct crypto_tls_ctx *ctx = crypto_aead_ctx(tfm); + struct crypto_ahash *auth; + struct crypto_skcipher *enc; + struct crypto_skcipher *null; + 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; + + null = crypto_get_default_null_skcipher2(); + err = PTR_ERR(null); + if (IS_ERR(null)) + goto err_free_skcipher; + + ctx->auth = auth; + ctx->enc = enc; + ctx->null = null; + + /* + * 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_skcipher_blocksize(enc)); + + crypto_aead_set_reqsize(tfm, + sizeof(struct tls_request_ctx) + + ctx->reqoff + + max_t(unsigned int, + crypto_ahash_reqsize(auth) + + sizeof(struct ahash_request), + crypto_skcipher_reqsize(enc) + + sizeof(struct skcipher_request))); + + return 0; + +err_free_skcipher: + crypto_free_skcipher(enc); +err_free_ahash: + crypto_free_ahash(auth); + return err; +} + +static void crypto_tls_exit_tfm(struct crypto_aead *tfm) +{ + struct crypto_tls_ctx *ctx = crypto_aead_ctx(tfm); + + crypto_free_ahash(ctx->auth); + crypto_free_skcipher(ctx->enc); + crypto_put_default_null_skcipher2(); +} + +static void crypto_tls_free(struct aead_instance *inst) +{ + struct tls_instance_ctx *ctx = aead_instance_ctx(inst); + + crypto_drop_skcipher(&ctx->enc); + crypto_drop_ahash(&ctx->auth); + kfree(inst); +} + +static int crypto_tls_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + struct crypto_attr_type *algt; + struct aead_instance *inst; + struct hash_alg_common *auth; + struct crypto_alg *auth_base; + struct skcipher_alg *enc; + struct tls_instance_ctx *ctx; + const char *enc_name; + int err; + + algt = crypto_get_attr_type(tb); + if (IS_ERR(algt)) + return PTR_ERR(algt); + + if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask) + return -EINVAL; + + auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH, + CRYPTO_ALG_TYPE_AHASH_MASK | + crypto_requires_sync(algt->type, algt->mask)); + if (IS_ERR(auth)) + return PTR_ERR(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 = aead_instance_ctx(inst); + + err = crypto_init_ahash_spawn(&ctx->auth, auth, + aead_crypto_instance(inst)); + if (err) + goto err_free_inst; + + crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(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_spawn_skcipher_alg(&ctx->enc); + + err = -ENAMETOOLONG; + if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, + "tls10(%s,%s)", auth_base->cra_name, + enc->base.cra_name) >= CRYPTO_MAX_ALG_NAME) + goto err_drop_enc; + + if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, + "tls10(%s,%s)", auth_base->cra_driver_name, + enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME) + goto err_drop_enc; + + inst->alg.base.cra_flags = (auth_base->cra_flags | + enc->base.cra_flags) & CRYPTO_ALG_ASYNC; + inst->alg.base.cra_priority = enc->base.cra_priority * 10 + + auth_base->cra_priority; + inst->alg.base.cra_blocksize = enc->base.cra_blocksize; + inst->alg.base.cra_alignmask = auth_base->cra_alignmask | + enc->base.cra_alignmask; + inst->alg.base.cra_ctxsize = sizeof(struct crypto_tls_ctx); + + inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc); + inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc); + inst->alg.maxauthsize = auth->digestsize; + + inst->alg.init = crypto_tls_init_tfm; + inst->alg.exit = crypto_tls_exit_tfm; + + inst->alg.setkey = crypto_tls_setkey; + inst->alg.encrypt = crypto_tls_encrypt; + inst->alg.decrypt = crypto_tls_decrypt; + + inst->free = crypto_tls_free; + + err = aead_register_instance(tmpl, inst); + if (err) + goto err_drop_enc; + +out: + crypto_mod_put(auth_base); + return err; + +err_drop_enc: + crypto_drop_skcipher(&ctx->enc); +err_drop_auth: + crypto_drop_ahash(&ctx->auth); +err_free_inst: + kfree(inst); +out_put_auth: + goto out; +} + +static struct crypto_template crypto_tls_tmpl = { + .name = "tls10", + .create = crypto_tls_create, + .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"); |