Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | |
| 3 | /* |
| 4 | * OFB: Output FeedBack mode |
| 5 | * |
| 6 | * Copyright (C) 2018 ARM Limited or its affiliates. |
| 7 | * All rights reserved. |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 8 | */ |
| 9 | |
| 10 | #include <crypto/algapi.h> |
Ard Biesheuvel | 0eb76ba | 2020-12-11 13:27:15 +0100 | [diff] [blame] | 11 | #include <crypto/internal/cipher.h> |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 12 | #include <crypto/internal/skcipher.h> |
| 13 | #include <linux/err.h> |
| 14 | #include <linux/init.h> |
| 15 | #include <linux/kernel.h> |
| 16 | #include <linux/module.h> |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 17 | |
Eric Biggers | b3e3e2d | 2019-01-03 20:16:12 -0800 | [diff] [blame] | 18 | static int crypto_ofb_crypt(struct skcipher_request *req) |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 19 | { |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 20 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
Eric Biggers | 21f3ca6 | 2019-01-03 20:16:20 -0800 | [diff] [blame] | 21 | struct crypto_cipher *cipher = skcipher_cipher_simple(tfm); |
Eric Biggers | b3e3e2d | 2019-01-03 20:16:12 -0800 | [diff] [blame] | 22 | const unsigned int bsize = crypto_cipher_blocksize(cipher); |
| 23 | struct skcipher_walk walk; |
| 24 | int err; |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 25 | |
Eric Biggers | b3e3e2d | 2019-01-03 20:16:12 -0800 | [diff] [blame] | 26 | err = skcipher_walk_virt(&walk, req, false); |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 27 | |
Eric Biggers | b3e3e2d | 2019-01-03 20:16:12 -0800 | [diff] [blame] | 28 | while (walk.nbytes >= bsize) { |
| 29 | const u8 *src = walk.src.virt.addr; |
| 30 | u8 *dst = walk.dst.virt.addr; |
| 31 | u8 * const iv = walk.iv; |
| 32 | unsigned int nbytes = walk.nbytes; |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 33 | |
Eric Biggers | b3e3e2d | 2019-01-03 20:16:12 -0800 | [diff] [blame] | 34 | do { |
| 35 | crypto_cipher_encrypt_one(cipher, iv, iv); |
| 36 | crypto_xor_cpy(dst, src, iv, bsize); |
| 37 | dst += bsize; |
| 38 | src += bsize; |
| 39 | } while ((nbytes -= bsize) >= bsize); |
| 40 | |
| 41 | err = skcipher_walk_done(&walk, nbytes); |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 42 | } |
| 43 | |
Eric Biggers | b3e3e2d | 2019-01-03 20:16:12 -0800 | [diff] [blame] | 44 | if (walk.nbytes) { |
| 45 | crypto_cipher_encrypt_one(cipher, walk.iv, walk.iv); |
| 46 | crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, walk.iv, |
| 47 | walk.nbytes); |
| 48 | err = skcipher_walk_done(&walk, 0); |
| 49 | } |
| 50 | return err; |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 51 | } |
| 52 | |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 53 | static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb) |
| 54 | { |
| 55 | struct skcipher_instance *inst; |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 56 | struct crypto_alg *alg; |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 57 | int err; |
| 58 | |
Herbert Xu | b3c16bf | 2019-12-20 13:29:40 +0800 | [diff] [blame] | 59 | inst = skcipher_alloc_instance_simple(tmpl, tb); |
Eric Biggers | 21f3ca6 | 2019-01-03 20:16:20 -0800 | [diff] [blame] | 60 | if (IS_ERR(inst)) |
| 61 | return PTR_ERR(inst); |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 62 | |
Herbert Xu | b3c16bf | 2019-12-20 13:29:40 +0800 | [diff] [blame] | 63 | alg = skcipher_ialg_simple(inst); |
| 64 | |
Eric Biggers | b3e3e2d | 2019-01-03 20:16:12 -0800 | [diff] [blame] | 65 | /* OFB mode is a stream cipher. */ |
| 66 | inst->alg.base.cra_blocksize = 1; |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 67 | |
Eric Biggers | b3e3e2d | 2019-01-03 20:16:12 -0800 | [diff] [blame] | 68 | /* |
| 69 | * To simplify the implementation, configure the skcipher walk to only |
| 70 | * give a partial block at the very end, never earlier. |
| 71 | */ |
| 72 | inst->alg.chunksize = alg->cra_blocksize; |
| 73 | |
Eric Biggers | b3e3e2d | 2019-01-03 20:16:12 -0800 | [diff] [blame] | 74 | inst->alg.encrypt = crypto_ofb_crypt; |
| 75 | inst->alg.decrypt = crypto_ofb_crypt; |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 76 | |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 77 | err = skcipher_register_instance(tmpl, inst); |
| 78 | if (err) |
Eric Biggers | 21f3ca6 | 2019-01-03 20:16:20 -0800 | [diff] [blame] | 79 | inst->free(inst); |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 80 | |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 81 | return err; |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 82 | } |
| 83 | |
| 84 | static struct crypto_template crypto_ofb_tmpl = { |
| 85 | .name = "ofb", |
| 86 | .create = crypto_ofb_create, |
| 87 | .module = THIS_MODULE, |
| 88 | }; |
| 89 | |
| 90 | static int __init crypto_ofb_module_init(void) |
| 91 | { |
| 92 | return crypto_register_template(&crypto_ofb_tmpl); |
| 93 | } |
| 94 | |
| 95 | static void __exit crypto_ofb_module_exit(void) |
| 96 | { |
| 97 | crypto_unregister_template(&crypto_ofb_tmpl); |
| 98 | } |
| 99 | |
Eric Biggers | c4741b2 | 2019-04-11 21:57:42 -0700 | [diff] [blame] | 100 | subsys_initcall(crypto_ofb_module_init); |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 101 | module_exit(crypto_ofb_module_exit); |
| 102 | |
| 103 | MODULE_LICENSE("GPL"); |
Eric Biggers | 21f3ca6 | 2019-01-03 20:16:20 -0800 | [diff] [blame] | 104 | MODULE_DESCRIPTION("OFB block cipher mode of operation"); |
Gilad Ben-Yossef | e497c51 | 2018-09-20 14:18:39 +0100 | [diff] [blame] | 105 | MODULE_ALIAS_CRYPTO("ofb"); |
Ard Biesheuvel | 0eb76ba | 2020-12-11 13:27:15 +0100 | [diff] [blame] | 106 | MODULE_IMPORT_NS(CRYPTO_INTERNAL); |