// SPDX-License-Identifier: GPL-2.0-or-later /* * ChaCha20-Poly1305 AEAD, RFC7539 * * Copyright (C) 2015 Martin Willi */ #include <crypto/internal/aead.h> #include <crypto/internal/hash.h> #include <crypto/internal/skcipher.h> #include <crypto/scatterwalk.h> #include <crypto/chacha.h> #include <crypto/poly1305.h> #include <linux/err.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> 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[CHACHA_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; /* request flags, with MAY_SLEEP cleared if needed */ u32 flags; 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) { struct chachapoly_req_ctx *rctx = aead_request_ctx(req); rctx->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP; 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, CHACHA_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); src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen); dst = src; if (req->src != req->dst) dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen); skcipher_request_set_callback(&creq->req, rctx->flags, 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; int err; preq->tail.assoclen = cpu_to_le64(rctx->assoclen); preq->tail.cryptlen = cpu_to_le64(rctx->cryptlen); sg_init_one(preq->src, &preq->tail, sizeof(preq->tail)); ahash_request_set_callback(&preq->req, rctx->flags, 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; int err; padlen = -rctx->cryptlen % POLY1305_BLOCK_SIZE; memset(preq->pad, 0, sizeof(preq->pad)); sg_init_one(preq->src, preq->pad, padlen); ahash_request_set_callback(&preq->req, rctx->flags, 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; crypt = scatterwalk_ffwd(rctx->src, crypt, req->assoclen); ahash_request_set_callback(&preq->req, rctx->flags, 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; int err; padlen = -rctx->assoclen % POLY1305_BLOCK_SIZE; memset(preq->pad, 0, sizeof(preq->pad)); sg_init_one(preq->src, preq->pad, padlen); ahash_request_set_callback(&preq->req, rctx->flags, 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, rctx->flags, 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_one(preq->src, rctx->key, sizeof(rctx->key)); ahash_request_set_callback(&preq->req, rctx->flags, 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, rctx->flags, 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; } memset(rctx->key, 0, sizeof(rctx->key)); sg_init_one(creq->src, rctx->key, sizeof(rctx->key)); chacha_iv(creq->iv, req, 0); skcipher_request_set_callback(&creq->req, rctx->flags, 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); src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen); dst = src; if (req->src != req->dst) dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen); skcipher_request_set_callback(&creq->req, rctx->flags, 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; rctx->flags = aead_request_flags(req); /* 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; rctx->flags = aead_request_flags(req); /* 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); if (keylen != ctx->saltlen + CHACHA_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); return crypto_skcipher_setkey(ctx->chacha, key, keylen); } 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) { u32 mask; struct aead_instance *inst; struct chachapoly_instance_ctx *ctx; struct skcipher_alg *chacha; struct hash_alg_common *poly; int err; if (ivsize > CHACHAPOLY_IV_SIZE) return -EINVAL; err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask); if (err) return err; inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL); if (!inst) return -ENOMEM; ctx = aead_instance_ctx(inst); ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize; err = crypto_grab_skcipher(&ctx->chacha, aead_crypto_instance(inst), crypto_attr_alg_name(tb[1]), 0, mask); if (err) goto err_free_inst; chacha = crypto_spawn_skcipher_alg(&ctx->chacha); err = crypto_grab_ahash(&ctx->poly, aead_crypto_instance(inst), crypto_attr_alg_name(tb[2]), 0, mask); if (err) goto err_free_inst; poly = crypto_spawn_ahash_alg(&ctx->poly); err = -EINVAL; if (poly->digestsize != POLY1305_DIGEST_SIZE) goto err_free_inst; /* Need 16-byte IV size, including Initial Block Counter value */ if (crypto_skcipher_alg_ivsize(chacha) != CHACHA_IV_SIZE) goto err_free_inst; /* Not a stream cipher? */ if (chacha->base.cra_blocksize != 1) goto err_free_inst; err = -ENAMETOOLONG; if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, "%s(%s,%s)", name, chacha->base.cra_name, poly->base.cra_name) >= CRYPTO_MAX_ALG_NAME) goto err_free_inst; if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, "%s(%s,%s)", name, chacha->base.cra_driver_name, poly->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME) goto err_free_inst; inst->alg.base.cra_priority = (chacha->base.cra_priority + poly->base.cra_priority) / 2; inst->alg.base.cra_blocksize = 1; inst->alg.base.cra_alignmask = chacha->base.cra_alignmask | poly->base.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) { err_free_inst: chachapoly_free(inst); } return err; } 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_tmpls[] = { { .name = "rfc7539", .create = rfc7539_create, .module = THIS_MODULE, }, { .name = "rfc7539esp", .create = rfc7539esp_create, .module = THIS_MODULE, }, }; static int __init chacha20poly1305_module_init(void) { return crypto_register_templates(rfc7539_tmpls, ARRAY_SIZE(rfc7539_tmpls)); } static void __exit chacha20poly1305_module_exit(void) { crypto_unregister_templates(rfc7539_tmpls, ARRAY_SIZE(rfc7539_tmpls)); } subsys_initcall(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");