/* * 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 <crypto/chacha20.h> #include <crypto/poly1305.h> #include <linux/err.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include "internal.h" #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_skcipher *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 { u8 iv[CHACHA20_IV_SIZE]; struct scatterlist src[1]; struct skcipher_request req; /* must be last member */ }; struct chachapoly_req_ctx { struct scatterlist src[2]; struct scatterlist dst[2]; /* the key we generate for Poly1305 using Chacha20 */ u8 key[POLY1305_KEY_SIZE]; /* calculated Poly1305 tag */ u8 tag[POLY1305_DIGEST_SIZE]; /* length of data to en/decrypt, without ICV */ unsigned int cryptlen; /* Actual AD, excluding IV */ unsigned int assoclen; 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, req->assoclen + 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, req->assoclen + 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; struct scatterlist *src, *dst; int err; if (rctx->cryptlen == 0) goto skip; chacha_iv(creq->iv, req, 1); sg_init_table(rctx->src, 2); src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen); dst = src; if (req->src != req->dst) { sg_init_table(rctx->dst, 2); dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen); } skcipher_request_set_callback(&creq->req, aead_request_flags(req), chacha_decrypt_done, req); skcipher_request_set_tfm(&creq->req, ctx->chacha); skcipher_request_set_crypt(&creq->req, src, dst, rctx->cryptlen, creq->iv); err = crypto_skcipher_decrypt(&creq->req); if (err) return err; skip: 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 crypto_aead *tfm = crypto_aead_reqtfm(req); struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm); 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(rctx->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; sg_init_table(rctx->src, 2); crypt = scatterwalk_ffwd(rctx->src, crypt, req->assoclen); 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 - (rctx->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->src, NULL, rctx->assoclen); err = crypto_ahash_update(&preq->req); if (err) return err; return poly_adpad(req); } static void poly_setkey_done(struct crypto_async_request *areq, int err) { async_done_continue(areq->data, err, poly_ad); } static int poly_setkey(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; sg_init_table(preq->src, 1); sg_set_buf(preq->src, rctx->key, sizeof(rctx->key)); ahash_request_set_callback(&preq->req, aead_request_flags(req), poly_setkey_done, req); ahash_request_set_tfm(&preq->req, ctx->poly); ahash_request_set_crypt(&preq->req, preq->src, NULL, sizeof(rctx->key)); err = crypto_ahash_update(&preq->req); if (err) return err; return poly_ad(req); } static void poly_init_done(struct crypto_async_request *areq, int err) { async_done_continue(areq->data, err, poly_setkey); } 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_setkey(req); } static void poly_genkey_done(struct crypto_async_request *areq, int err) { async_done_continue(areq->data, err, poly_init); } static int poly_genkey(struct aead_request *req) { struct crypto_aead *tfm = crypto_aead_reqtfm(req); struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm); struct chachapoly_req_ctx *rctx = aead_request_ctx(req); struct chacha_req *creq = &rctx->u.chacha; int err; rctx->assoclen = req->assoclen; if (crypto_aead_ivsize(tfm) == 8) { if (rctx->assoclen < 8) return -EINVAL; rctx->assoclen -= 8; } sg_init_table(creq->src, 1); memset(rctx->key, 0, sizeof(rctx->key)); sg_set_buf(creq->src, rctx->key, sizeof(rctx->key)); chacha_iv(creq->iv, req, 0); skcipher_request_set_callback(&creq->req, aead_request_flags(req), poly_genkey_done, req); skcipher_request_set_tfm(&creq->req, ctx->chacha); skcipher_request_set_crypt(&creq->req, creq->src, creq->src, POLY1305_KEY_SIZE, creq->iv); err = crypto_skcipher_decrypt(&creq->req); if (err) return err; return poly_init(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; struct scatterlist *src, *dst; int err; if (req->cryptlen == 0) goto skip; chacha_iv(creq->iv, req, 1); sg_init_table(rctx->src, 2); src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen); dst = src; if (req->src != req->dst) { sg_init_table(rctx->dst, 2); dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen); } skcipher_request_set_callback(&creq->req, aead_request_flags(req), chacha_encrypt_done, req); skcipher_request_set_tfm(&creq->req, ctx->chacha); skcipher_request_set_crypt(&creq->req, src, dst, req->cryptlen, creq->iv); err = crypto_skcipher_encrypt(&creq->req); if (err) return err; skip: 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() * - poly_init/done() * - poly_setkey/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); rctx->cryptlen = req->cryptlen - POLY1305_DIGEST_SIZE; /* decrypt call chain: * - poly_genkey/done() * - poly_init/done() * - poly_setkey/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_skcipher_clear_flags(ctx->chacha, CRYPTO_TFM_REQ_MASK); crypto_skcipher_set_flags(ctx->chacha, crypto_aead_get_flags(aead) & CRYPTO_TFM_REQ_MASK); err = crypto_skcipher_setkey(ctx->chacha, key, keylen); crypto_aead_set_flags(aead, crypto_skcipher_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_aead *tfm) { struct aead_instance *inst = aead_alg_instance(tfm); struct chachapoly_instance_ctx *ictx = aead_instance_ctx(inst); struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm); struct crypto_skcipher *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_aead_alignmask(tfm); align &= ~(crypto_tfm_ctx_alignment() - 1); crypto_aead_set_reqsize( tfm, align + offsetof(struct chachapoly_req_ctx, u) + max(offsetof(struct chacha_req, req) + sizeof(struct skcipher_request) + crypto_skcipher_reqsize(chacha), offsetof(struct poly_req, req) + sizeof(struct ahash_request) + crypto_ahash_reqsize(poly))); return 0; } static void chachapoly_exit(struct crypto_aead *tfm) { struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm); crypto_free_ahash(ctx->poly); crypto_free_skcipher(ctx->chacha); } static void chachapoly_free(struct aead_instance *inst) { struct chachapoly_instance_ctx *ctx = aead_instance_ctx(inst); crypto_drop_skcipher(&ctx->chacha); crypto_drop_ahash(&ctx->poly); kfree(inst); } static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb, const char *name, unsigned int ivsize) { struct crypto_attr_type *algt; struct aead_instance *inst; struct skcipher_alg *chacha; struct crypto_alg *poly; struct hash_alg_common *poly_hash; struct chachapoly_instance_ctx *ctx; const char *chacha_name, *poly_name; int err; if (ivsize > CHACHAPOLY_IV_SIZE) return -EINVAL; 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; chacha_name = crypto_attr_alg_name(tb[1]); if (IS_ERR(chacha_name)) return PTR_ERR(chacha_name); poly_name = crypto_attr_alg_name(tb[2]); if (IS_ERR(poly_name)) return PTR_ERR(poly_name); poly = crypto_find_alg(poly_name, &crypto_ahash_type, CRYPTO_ALG_TYPE_HASH, CRYPTO_ALG_TYPE_AHASH_MASK | crypto_requires_sync(algt->type, algt->mask)); if (IS_ERR(poly)) return PTR_ERR(poly); err = -ENOMEM; inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL); if (!inst) goto out_put_poly; ctx = aead_instance_ctx(inst); ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize; poly_hash = __crypto_hash_alg_common(poly); err = crypto_init_ahash_spawn(&ctx->poly, poly_hash, aead_crypto_instance(inst)); if (err) goto err_free_inst; crypto_set_skcipher_spawn(&ctx->chacha, aead_crypto_instance(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_spawn_skcipher_alg(&ctx->chacha); err = -EINVAL; /* Need 16-byte IV size, including Initial Block Counter value */ if (crypto_skcipher_alg_ivsize(chacha) != CHACHA20_IV_SIZE) goto out_drop_chacha; /* Not a stream cipher? */ if (chacha->base.cra_blocksize != 1) goto out_drop_chacha; err = -ENAMETOOLONG; if (snprintf(inst->alg.base.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.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, "%s(%s,%s)", name, chacha->base.cra_driver_name, poly->cra_driver_name) >= CRYPTO_MAX_ALG_NAME) goto out_drop_chacha; inst->alg.base.cra_flags = (chacha->base.cra_flags | poly->cra_flags) & CRYPTO_ALG_ASYNC; inst->alg.base.cra_priority = (chacha->base.cra_priority + poly->cra_priority) / 2; inst->alg.base.cra_blocksize = 1; inst->alg.base.cra_alignmask = chacha->base.cra_alignmask | poly->cra_alignmask; inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) + ctx->saltlen; inst->alg.ivsize = ivsize; inst->alg.chunksize = crypto_skcipher_alg_chunksize(chacha); inst->alg.maxauthsize = POLY1305_DIGEST_SIZE; inst->alg.init = chachapoly_init; inst->alg.exit = chachapoly_exit; inst->alg.encrypt = chachapoly_encrypt; inst->alg.decrypt = chachapoly_decrypt; inst->alg.setkey = chachapoly_setkey; inst->alg.setauthsize = chachapoly_setauthsize; inst->free = chachapoly_free; err = aead_register_instance(tmpl, inst); if (err) goto out_drop_chacha; out_put_poly: crypto_mod_put(poly); return err; out_drop_chacha: crypto_drop_skcipher(&ctx->chacha); err_drop_poly: crypto_drop_ahash(&ctx->poly); err_free_inst: kfree(inst); goto out_put_poly; } static int rfc7539_create(struct crypto_template *tmpl, struct rtattr **tb) { return chachapoly_create(tmpl, tb, "rfc7539", 12); } static int rfc7539esp_create(struct crypto_template *tmpl, struct rtattr **tb) { return chachapoly_create(tmpl, tb, "rfc7539esp", 8); } static struct crypto_template rfc7539_tmpl = { .name = "rfc7539", .create = rfc7539_create, .module = THIS_MODULE, }; static struct crypto_template rfc7539esp_tmpl = { .name = "rfc7539esp", .create = rfc7539esp_create, .module = THIS_MODULE, }; static int __init chacha20poly1305_module_init(void) { int err; err = crypto_register_template(&rfc7539_tmpl); if (err) return err; err = crypto_register_template(&rfc7539esp_tmpl); if (err) crypto_unregister_template(&rfc7539_tmpl); return err; } static void __exit chacha20poly1305_module_exit(void) { crypto_unregister_template(&rfc7539esp_tmpl); 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("rfc7539"); MODULE_ALIAS_CRYPTO("rfc7539esp");