diff options
Diffstat (limited to 'crypto/chacha20poly1305.c')
| -rw-r--r-- | crypto/chacha20poly1305.c | 663 |
1 files changed, 663 insertions, 0 deletions
diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c new file mode 100644 index 0000000..6171cf1 --- /dev/null +++ b/crypto/chacha20poly1305.c @@ -0,0 +1,663 @@ +/* + * ChaCha20-Poly1305 AEAD, RFC7539 + * + * Copyright (C) 2015 Martin Willi + * + * 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/scatterwalk.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> + +#include "internal.h" + +#define POLY1305_BLOCK_SIZE 16 +#define POLY1305_DIGEST_SIZE 16 +#define POLY1305_KEY_SIZE 32 +#define CHACHA20_KEY_SIZE 32 +#define CHACHA20_IV_SIZE 16 +#define CHACHAPOLY_IV_SIZE 12 + +struct chachapoly_instance_ctx { + struct crypto_skcipher_spawn chacha; + struct crypto_ahash_spawn poly; + unsigned int saltlen; +}; + +struct chachapoly_ctx { + struct crypto_ablkcipher *chacha; + struct crypto_ahash *poly; + /* key bytes we use for the ChaCha20 IV */ + unsigned int saltlen; + u8 salt[]; +}; + +struct poly_req { + /* zero byte padding for AD/ciphertext, as needed */ + u8 pad[POLY1305_BLOCK_SIZE]; + /* tail data with AD/ciphertext lengths */ + struct { + __le64 assoclen; + __le64 cryptlen; + } tail; + struct scatterlist src[1]; + struct ahash_request req; /* must be last member */ +}; + +struct chacha_req { + /* the key we generate for Poly1305 using Chacha20 */ + u8 key[POLY1305_KEY_SIZE]; + u8 iv[CHACHA20_IV_SIZE]; + struct scatterlist src[1]; + struct ablkcipher_request req; /* must be last member */ +}; + +struct chachapoly_req_ctx { + /* calculated Poly1305 tag */ + u8 tag[POLY1305_DIGEST_SIZE]; + /* length of data to en/decrypt, without ICV */ + unsigned int cryptlen; + union { + struct poly_req poly; + struct chacha_req chacha; + } u; +}; + +static inline void async_done_continue(struct aead_request *req, int err, + int (*cont)(struct aead_request *)) +{ + if (!err) + err = cont(req); + + if (err != -EINPROGRESS && err != -EBUSY) + aead_request_complete(req, err); +} + +static void chacha_iv(u8 *iv, struct aead_request *req, u32 icb) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + __le32 leicb = cpu_to_le32(icb); + + memcpy(iv, &leicb, sizeof(leicb)); + memcpy(iv + sizeof(leicb), ctx->salt, ctx->saltlen); + memcpy(iv + sizeof(leicb) + ctx->saltlen, req->iv, + CHACHA20_IV_SIZE - sizeof(leicb) - ctx->saltlen); +} + +static int poly_verify_tag(struct aead_request *req) +{ + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + u8 tag[sizeof(rctx->tag)]; + + scatterwalk_map_and_copy(tag, req->src, rctx->cryptlen, sizeof(tag), 0); + if (crypto_memneq(tag, rctx->tag, sizeof(tag))) + return -EBADMSG; + return 0; +} + +static int poly_copy_tag(struct aead_request *req) +{ + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + + scatterwalk_map_and_copy(rctx->tag, req->dst, rctx->cryptlen, + sizeof(rctx->tag), 1); + return 0; +} + +static void chacha_decrypt_done(struct crypto_async_request *areq, int err) +{ + async_done_continue(areq->data, err, poly_verify_tag); +} + +static int chacha_decrypt(struct aead_request *req) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct chacha_req *creq = &rctx->u.chacha; + int err; + + chacha_iv(creq->iv, req, 1); + + ablkcipher_request_set_callback(&creq->req, aead_request_flags(req), + chacha_decrypt_done, req); + ablkcipher_request_set_tfm(&creq->req, ctx->chacha); + ablkcipher_request_set_crypt(&creq->req, req->src, req->dst, + rctx->cryptlen, creq->iv); + err = crypto_ablkcipher_decrypt(&creq->req); + if (err) + return err; + + return poly_verify_tag(req); +} + +static int poly_tail_continue(struct aead_request *req) +{ + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + + if (rctx->cryptlen == req->cryptlen) /* encrypting */ + return poly_copy_tag(req); + + return chacha_decrypt(req); +} + +static void poly_tail_done(struct crypto_async_request *areq, int err) +{ + async_done_continue(areq->data, err, poly_tail_continue); +} + +static int poly_tail(struct aead_request *req) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct poly_req *preq = &rctx->u.poly; + __le64 len; + int err; + + sg_init_table(preq->src, 1); + len = cpu_to_le64(req->assoclen); + memcpy(&preq->tail.assoclen, &len, sizeof(len)); + len = cpu_to_le64(rctx->cryptlen); + memcpy(&preq->tail.cryptlen, &len, sizeof(len)); + sg_set_buf(preq->src, &preq->tail, sizeof(preq->tail)); + + ahash_request_set_callback(&preq->req, aead_request_flags(req), + poly_tail_done, req); + ahash_request_set_tfm(&preq->req, ctx->poly); + ahash_request_set_crypt(&preq->req, preq->src, + rctx->tag, sizeof(preq->tail)); + + err = crypto_ahash_finup(&preq->req); + if (err) + return err; + + return poly_tail_continue(req); +} + +static void poly_cipherpad_done(struct crypto_async_request *areq, int err) +{ + async_done_continue(areq->data, err, poly_tail); +} + +static int poly_cipherpad(struct aead_request *req) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct poly_req *preq = &rctx->u.poly; + unsigned int padlen, bs = POLY1305_BLOCK_SIZE; + int err; + + padlen = (bs - (rctx->cryptlen % bs)) % bs; + memset(preq->pad, 0, sizeof(preq->pad)); + sg_init_table(preq->src, 1); + sg_set_buf(preq->src, &preq->pad, padlen); + + ahash_request_set_callback(&preq->req, aead_request_flags(req), + poly_cipherpad_done, req); + ahash_request_set_tfm(&preq->req, ctx->poly); + ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen); + + err = crypto_ahash_update(&preq->req); + if (err) + return err; + + return poly_tail(req); +} + +static void poly_cipher_done(struct crypto_async_request *areq, int err) +{ + async_done_continue(areq->data, err, poly_cipherpad); +} + +static int poly_cipher(struct aead_request *req) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct poly_req *preq = &rctx->u.poly; + struct scatterlist *crypt = req->src; + int err; + + if (rctx->cryptlen == req->cryptlen) /* encrypting */ + crypt = req->dst; + + ahash_request_set_callback(&preq->req, aead_request_flags(req), + poly_cipher_done, req); + ahash_request_set_tfm(&preq->req, ctx->poly); + ahash_request_set_crypt(&preq->req, crypt, NULL, rctx->cryptlen); + + err = crypto_ahash_update(&preq->req); + if (err) + return err; + + return poly_cipherpad(req); +} + +static void poly_adpad_done(struct crypto_async_request *areq, int err) +{ + async_done_continue(areq->data, err, poly_cipher); +} + +static int poly_adpad(struct aead_request *req) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct poly_req *preq = &rctx->u.poly; + unsigned int padlen, bs = POLY1305_BLOCK_SIZE; + int err; + + padlen = (bs - (req->assoclen % bs)) % bs; + memset(preq->pad, 0, sizeof(preq->pad)); + sg_init_table(preq->src, 1); + sg_set_buf(preq->src, preq->pad, padlen); + + ahash_request_set_callback(&preq->req, aead_request_flags(req), + poly_adpad_done, req); + ahash_request_set_tfm(&preq->req, ctx->poly); + ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen); + + err = crypto_ahash_update(&preq->req); + if (err) + return err; + + return poly_cipher(req); +} + +static void poly_ad_done(struct crypto_async_request *areq, int err) +{ + async_done_continue(areq->data, err, poly_adpad); +} + +static int poly_ad(struct aead_request *req) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct poly_req *preq = &rctx->u.poly; + int err; + + ahash_request_set_callback(&preq->req, aead_request_flags(req), + poly_ad_done, req); + ahash_request_set_tfm(&preq->req, ctx->poly); + ahash_request_set_crypt(&preq->req, req->assoc, NULL, req->assoclen); + + err = crypto_ahash_update(&preq->req); + if (err) + return err; + + return poly_adpad(req); +} + +static void poly_init_done(struct crypto_async_request *areq, int err) +{ + async_done_continue(areq->data, err, poly_ad); +} + +static int poly_init(struct aead_request *req) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct poly_req *preq = &rctx->u.poly; + int err; + + ahash_request_set_callback(&preq->req, aead_request_flags(req), + poly_init_done, req); + ahash_request_set_tfm(&preq->req, ctx->poly); + + err = crypto_ahash_init(&preq->req); + if (err) + return err; + + return poly_ad(req); +} + +static int poly_genkey_continue(struct aead_request *req) +{ + struct crypto_aead *aead = crypto_aead_reqtfm(req); + struct chachapoly_ctx *ctx = crypto_aead_ctx(aead); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct chacha_req *creq = &rctx->u.chacha; + int err; + + crypto_ahash_clear_flags(ctx->poly, CRYPTO_TFM_REQ_MASK); + crypto_ahash_set_flags(ctx->poly, crypto_aead_get_flags(aead) & + CRYPTO_TFM_REQ_MASK); + + err = crypto_ahash_setkey(ctx->poly, creq->key, sizeof(creq->key)); + crypto_aead_set_flags(aead, crypto_ahash_get_flags(ctx->poly) & + CRYPTO_TFM_RES_MASK); + if (err) + return err; + + return poly_init(req); +} + +static void poly_genkey_done(struct crypto_async_request *areq, int err) +{ + async_done_continue(areq->data, err, poly_genkey_continue); +} + +static int poly_genkey(struct aead_request *req) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct chacha_req *creq = &rctx->u.chacha; + int err; + + sg_init_table(creq->src, 1); + memset(creq->key, 0, sizeof(creq->key)); + sg_set_buf(creq->src, creq->key, sizeof(creq->key)); + + chacha_iv(creq->iv, req, 0); + + ablkcipher_request_set_callback(&creq->req, aead_request_flags(req), + poly_genkey_done, req); + ablkcipher_request_set_tfm(&creq->req, ctx->chacha); + ablkcipher_request_set_crypt(&creq->req, creq->src, creq->src, + POLY1305_KEY_SIZE, creq->iv); + + err = crypto_ablkcipher_decrypt(&creq->req); + if (err) + return err; + + return poly_genkey_continue(req); +} + +static void chacha_encrypt_done(struct crypto_async_request *areq, int err) +{ + async_done_continue(areq->data, err, poly_genkey); +} + +static int chacha_encrypt(struct aead_request *req) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req)); + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + struct chacha_req *creq = &rctx->u.chacha; + int err; + + chacha_iv(creq->iv, req, 1); + + ablkcipher_request_set_callback(&creq->req, aead_request_flags(req), + chacha_encrypt_done, req); + ablkcipher_request_set_tfm(&creq->req, ctx->chacha); + ablkcipher_request_set_crypt(&creq->req, req->src, req->dst, + req->cryptlen, creq->iv); + err = crypto_ablkcipher_encrypt(&creq->req); + if (err) + return err; + + return poly_genkey(req); +} + +static int chachapoly_encrypt(struct aead_request *req) +{ + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + + rctx->cryptlen = req->cryptlen; + + /* encrypt call chain: + * - chacha_encrypt/done() + * - poly_genkey/done/continue() + * - poly_init/done() + * - poly_ad/done() + * - poly_adpad/done() + * - poly_cipher/done() + * - poly_cipherpad/done() + * - poly_tail/done/continue() + * - poly_copy_tag() + */ + return chacha_encrypt(req); +} + +static int chachapoly_decrypt(struct aead_request *req) +{ + struct chachapoly_req_ctx *rctx = aead_request_ctx(req); + + if (req->cryptlen < POLY1305_DIGEST_SIZE) + return -EINVAL; + rctx->cryptlen = req->cryptlen - POLY1305_DIGEST_SIZE; + + /* decrypt call chain: + * - poly_genkey/done/continue() + * - poly_init/done() + * - poly_ad/done() + * - poly_adpad/done() + * - poly_cipher/done() + * - poly_cipherpad/done() + * - poly_tail/done/continue() + * - chacha_decrypt/done() + * - poly_verify_tag() + */ + return poly_genkey(req); +} + +static int chachapoly_setkey(struct crypto_aead *aead, const u8 *key, + unsigned int keylen) +{ + struct chachapoly_ctx *ctx = crypto_aead_ctx(aead); + int err; + + if (keylen != ctx->saltlen + CHACHA20_KEY_SIZE) + return -EINVAL; + + keylen -= ctx->saltlen; + memcpy(ctx->salt, key + keylen, ctx->saltlen); + + crypto_ablkcipher_clear_flags(ctx->chacha, CRYPTO_TFM_REQ_MASK); + crypto_ablkcipher_set_flags(ctx->chacha, crypto_aead_get_flags(aead) & + CRYPTO_TFM_REQ_MASK); + + err = crypto_ablkcipher_setkey(ctx->chacha, key, keylen); + crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctx->chacha) & + CRYPTO_TFM_RES_MASK); + return err; +} + +static int chachapoly_setauthsize(struct crypto_aead *tfm, + unsigned int authsize) +{ + if (authsize != POLY1305_DIGEST_SIZE) + return -EINVAL; + + return 0; +} + +static int chachapoly_init(struct crypto_tfm *tfm) +{ + struct crypto_instance *inst = (void *)tfm->__crt_alg; + struct chachapoly_instance_ctx *ictx = crypto_instance_ctx(inst); + struct chachapoly_ctx *ctx = crypto_tfm_ctx(tfm); + struct crypto_ablkcipher *chacha; + struct crypto_ahash *poly; + unsigned long align; + + poly = crypto_spawn_ahash(&ictx->poly); + if (IS_ERR(poly)) + return PTR_ERR(poly); + + chacha = crypto_spawn_skcipher(&ictx->chacha); + if (IS_ERR(chacha)) { + crypto_free_ahash(poly); + return PTR_ERR(chacha); + } + + ctx->chacha = chacha; + ctx->poly = poly; + ctx->saltlen = ictx->saltlen; + + align = crypto_tfm_alg_alignmask(tfm); + align &= ~(crypto_tfm_ctx_alignment() - 1); + crypto_aead_set_reqsize(__crypto_aead_cast(tfm), + align + offsetof(struct chachapoly_req_ctx, u) + + max(offsetof(struct chacha_req, req) + + sizeof(struct ablkcipher_request) + + crypto_ablkcipher_reqsize(chacha), + offsetof(struct poly_req, req) + + sizeof(struct ahash_request) + + crypto_ahash_reqsize(poly))); + + return 0; +} + +static void chachapoly_exit(struct crypto_tfm *tfm) +{ + struct chachapoly_ctx *ctx = crypto_tfm_ctx(tfm); + + crypto_free_ahash(ctx->poly); + crypto_free_ablkcipher(ctx->chacha); +} + +static struct crypto_instance *chachapoly_alloc(struct rtattr **tb, + const char *name, + unsigned int ivsize) +{ + struct crypto_attr_type *algt; + struct crypto_instance *inst; + struct crypto_alg *chacha; + struct crypto_alg *poly; + struct ahash_alg *poly_ahash; + struct chachapoly_instance_ctx *ctx; + const char *chacha_name, *poly_name; + int err; + + if (ivsize > CHACHAPOLY_IV_SIZE) + return ERR_PTR(-EINVAL); + + algt = crypto_get_attr_type(tb); + if (IS_ERR(algt)) + return ERR_CAST(algt); + + if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask) + return ERR_PTR(-EINVAL); + + chacha_name = crypto_attr_alg_name(tb[1]); + if (IS_ERR(chacha_name)) + return ERR_CAST(chacha_name); + poly_name = crypto_attr_alg_name(tb[2]); + if (IS_ERR(poly_name)) + return ERR_CAST(poly_name); + + poly = crypto_find_alg(poly_name, &crypto_ahash_type, + CRYPTO_ALG_TYPE_HASH, + CRYPTO_ALG_TYPE_AHASH_MASK); + if (IS_ERR(poly)) + return ERR_CAST(poly); + + err = -ENOMEM; + inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL); + if (!inst) + goto out_put_poly; + + ctx = crypto_instance_ctx(inst); + ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize; + poly_ahash = container_of(poly, struct ahash_alg, halg.base); + err = crypto_init_ahash_spawn(&ctx->poly, &poly_ahash->halg, inst); + if (err) + goto err_free_inst; + + crypto_set_skcipher_spawn(&ctx->chacha, inst); + err = crypto_grab_skcipher(&ctx->chacha, chacha_name, 0, + crypto_requires_sync(algt->type, + algt->mask)); + if (err) + goto err_drop_poly; + + chacha = crypto_skcipher_spawn_alg(&ctx->chacha); + + err = -EINVAL; + /* Need 16-byte IV size, including Initial Block Counter value */ + if (chacha->cra_ablkcipher.ivsize != CHACHA20_IV_SIZE) + goto out_drop_chacha; + /* Not a stream cipher? */ + if (chacha->cra_blocksize != 1) + goto out_drop_chacha; + + err = -ENAMETOOLONG; + if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME, + "%s(%s,%s)", name, chacha_name, + poly_name) >= CRYPTO_MAX_ALG_NAME) + goto out_drop_chacha; + if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME, + "%s(%s,%s)", name, chacha->cra_driver_name, + poly->cra_driver_name) >= CRYPTO_MAX_ALG_NAME) + goto out_drop_chacha; + + inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD; + inst->alg.cra_flags |= (chacha->cra_flags | + poly->cra_flags) & CRYPTO_ALG_ASYNC; + inst->alg.cra_priority = (chacha->cra_priority + + poly->cra_priority) / 2; + inst->alg.cra_blocksize = 1; + inst->alg.cra_alignmask = chacha->cra_alignmask | poly->cra_alignmask; + inst->alg.cra_type = &crypto_nivaead_type; + inst->alg.cra_aead.ivsize = ivsize; + inst->alg.cra_aead.maxauthsize = POLY1305_DIGEST_SIZE; + inst->alg.cra_ctxsize = sizeof(struct chachapoly_ctx) + ctx->saltlen; + inst->alg.cra_init = chachapoly_init; + inst->alg.cra_exit = chachapoly_exit; + inst->alg.cra_aead.encrypt = chachapoly_encrypt; + inst->alg.cra_aead.decrypt = chachapoly_decrypt; + inst->alg.cra_aead.setkey = chachapoly_setkey; + inst->alg.cra_aead.setauthsize = chachapoly_setauthsize; + inst->alg.cra_aead.geniv = "seqiv"; + +out: + crypto_mod_put(poly); + return inst; + +out_drop_chacha: + crypto_drop_skcipher(&ctx->chacha); +err_drop_poly: + crypto_drop_ahash(&ctx->poly); +err_free_inst: + kfree(inst); +out_put_poly: + inst = ERR_PTR(err); + goto out; +} + +static struct crypto_instance *rfc7539_alloc(struct rtattr **tb) +{ + return chachapoly_alloc(tb, "rfc7539", 12); +} + +static void chachapoly_free(struct crypto_instance *inst) +{ + struct chachapoly_instance_ctx *ctx = crypto_instance_ctx(inst); + + crypto_drop_skcipher(&ctx->chacha); + crypto_drop_ahash(&ctx->poly); + kfree(inst); +} + +static struct crypto_template rfc7539_tmpl = { + .name = "rfc7539", + .alloc = rfc7539_alloc, + .free = chachapoly_free, + .module = THIS_MODULE, +}; + +static int __init chacha20poly1305_module_init(void) +{ + return crypto_register_template(&rfc7539_tmpl); +} + +static void __exit chacha20poly1305_module_exit(void) +{ + crypto_unregister_template(&rfc7539_tmpl); +} + +module_init(chacha20poly1305_module_init); +module_exit(chacha20poly1305_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); +MODULE_DESCRIPTION("ChaCha20-Poly1305 AEAD"); +MODULE_ALIAS_CRYPTO("chacha20poly1305"); +MODULE_ALIAS_CRYPTO("rfc7539"); |
