Commit | Line | Data |
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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
a10f554f HX |
2 | /* |
3 | * echainiv: Encrypted Chain IV Generator | |
4 | * | |
53a5d5dd HX |
5 | * This generator generates an IV based on a sequence number by multiplying |
6 | * it with a salt and then encrypting it with the same key as used to encrypt | |
a10f554f HX |
7 | * the plain text. This algorithm requires that the block size be equal |
8 | * to the IV size. It is mainly useful for CBC. | |
9 | * | |
10 | * This generator can only be used by algorithms where authentication | |
11 | * is performed after encryption (i.e., authenc). | |
12 | * | |
13 | * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> | |
a10f554f HX |
14 | */ |
15 | ||
d97de47c | 16 | #include <crypto/internal/geniv.h> |
a10f554f | 17 | #include <crypto/scatterwalk.h> |
0e8bff47 | 18 | #include <crypto/skcipher.h> |
a10f554f HX |
19 | #include <linux/err.h> |
20 | #include <linux/init.h> | |
21 | #include <linux/kernel.h> | |
a10f554f | 22 | #include <linux/module.h> |
53a5d5dd | 23 | #include <linux/slab.h> |
a10f554f HX |
24 | #include <linux/string.h> |
25 | ||
a10f554f HX |
26 | static int echainiv_encrypt(struct aead_request *req) |
27 | { | |
28 | struct crypto_aead *geniv = crypto_aead_reqtfm(req); | |
376e0d69 | 29 | struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); |
a10f554f | 30 | struct aead_request *subreq = aead_request_ctx(req); |
53a5d5dd HX |
31 | __be64 nseqno; |
32 | u64 seqno; | |
a10f554f | 33 | u8 *info; |
823655c9 | 34 | unsigned int ivsize = crypto_aead_ivsize(geniv); |
a10f554f HX |
35 | int err; |
36 | ||
823655c9 HX |
37 | if (req->cryptlen < ivsize) |
38 | return -EINVAL; | |
39 | ||
376e0d69 | 40 | aead_request_set_tfm(subreq, ctx->child); |
a10f554f | 41 | |
a10f554f HX |
42 | info = req->iv; |
43 | ||
a10f554f | 44 | if (req->src != req->dst) { |
8d605398 | 45 | SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull); |
a10f554f | 46 | |
8d605398 | 47 | skcipher_request_set_sync_tfm(nreq, ctx->sknull); |
0e8bff47 HX |
48 | skcipher_request_set_callback(nreq, req->base.flags, |
49 | NULL, NULL); | |
50 | skcipher_request_set_crypt(nreq, req->src, req->dst, | |
51 | req->assoclen + req->cryptlen, | |
52 | NULL); | |
53 | ||
54 | err = crypto_skcipher_encrypt(nreq); | |
a10f554f HX |
55 | if (err) |
56 | return err; | |
57 | } | |
58 | ||
53a5d5dd HX |
59 | aead_request_set_callback(subreq, req->base.flags, |
60 | req->base.complete, req->base.data); | |
a10f554f | 61 | aead_request_set_crypt(subreq, req->dst, req->dst, |
5499b1a7 HX |
62 | req->cryptlen, info); |
63 | aead_request_set_ad(subreq, req->assoclen); | |
a10f554f | 64 | |
53a5d5dd HX |
65 | memcpy(&nseqno, info + ivsize - 8, 8); |
66 | seqno = be64_to_cpu(nseqno); | |
67 | memset(info, 0, ivsize); | |
68 | ||
a10f554f | 69 | scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1); |
a10f554f | 70 | |
53a5d5dd HX |
71 | do { |
72 | u64 a; | |
73 | ||
74 | memcpy(&a, ctx->salt + ivsize - 8, 8); | |
75 | ||
76 | a |= 1; | |
77 | a *= seqno; | |
78 | ||
79 | memcpy(info + ivsize - 8, &a, 8); | |
80 | } while ((ivsize -= 8)); | |
81 | ||
82 | return crypto_aead_encrypt(subreq); | |
a10f554f HX |
83 | } |
84 | ||
a10f554f HX |
85 | static int echainiv_decrypt(struct aead_request *req) |
86 | { | |
87 | struct crypto_aead *geniv = crypto_aead_reqtfm(req); | |
376e0d69 | 88 | struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); |
a10f554f HX |
89 | struct aead_request *subreq = aead_request_ctx(req); |
90 | crypto_completion_t compl; | |
91 | void *data; | |
823655c9 HX |
92 | unsigned int ivsize = crypto_aead_ivsize(geniv); |
93 | ||
5499b1a7 | 94 | if (req->cryptlen < ivsize) |
823655c9 | 95 | return -EINVAL; |
a10f554f | 96 | |
376e0d69 | 97 | aead_request_set_tfm(subreq, ctx->child); |
a10f554f HX |
98 | |
99 | compl = req->base.complete; | |
100 | data = req->base.data; | |
101 | ||
a10f554f HX |
102 | aead_request_set_callback(subreq, req->base.flags, compl, data); |
103 | aead_request_set_crypt(subreq, req->src, req->dst, | |
104 | req->cryptlen - ivsize, req->iv); | |
374d4ad1 | 105 | aead_request_set_ad(subreq, req->assoclen + ivsize); |
a10f554f HX |
106 | |
107 | scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0); | |
a10f554f HX |
108 | |
109 | return crypto_aead_decrypt(subreq); | |
110 | } | |
111 | ||
1e419c79 HX |
112 | static int echainiv_aead_create(struct crypto_template *tmpl, |
113 | struct rtattr **tb) | |
a10f554f HX |
114 | { |
115 | struct aead_instance *inst; | |
1e419c79 | 116 | int err; |
a10f554f | 117 | |
e72b48c5 | 118 | inst = aead_geniv_alloc(tmpl, tb); |
a10f554f HX |
119 | |
120 | if (IS_ERR(inst)) | |
1e419c79 | 121 | return PTR_ERR(inst); |
a10f554f | 122 | |
1e419c79 | 123 | err = -EINVAL; |
53a5d5dd | 124 | if (inst->alg.ivsize & (sizeof(u64) - 1) || !inst->alg.ivsize) |
1e419c79 | 125 | goto free_inst; |
a10f554f | 126 | |
f261c5fb | 127 | inst->alg.encrypt = echainiv_encrypt; |
a10f554f HX |
128 | inst->alg.decrypt = echainiv_decrypt; |
129 | ||
376e0d69 HX |
130 | inst->alg.init = aead_init_geniv; |
131 | inst->alg.exit = aead_exit_geniv; | |
a10f554f | 132 | |
376e0d69 | 133 | inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx); |
9d03aee1 | 134 | inst->alg.base.cra_ctxsize += inst->alg.ivsize; |
a10f554f | 135 | |
1e419c79 | 136 | err = aead_register_instance(tmpl, inst); |
0f8f6d86 | 137 | if (err) { |
1e419c79 | 138 | free_inst: |
0f8f6d86 EB |
139 | inst->free(inst); |
140 | } | |
141 | return err; | |
a10f554f HX |
142 | } |
143 | ||
144 | static struct crypto_template echainiv_tmpl = { | |
145 | .name = "echainiv", | |
9fcc704d | 146 | .create = echainiv_aead_create, |
a10f554f HX |
147 | .module = THIS_MODULE, |
148 | }; | |
149 | ||
150 | static int __init echainiv_module_init(void) | |
151 | { | |
152 | return crypto_register_template(&echainiv_tmpl); | |
153 | } | |
154 | ||
155 | static void __exit echainiv_module_exit(void) | |
156 | { | |
157 | crypto_unregister_template(&echainiv_tmpl); | |
158 | } | |
159 | ||
c4741b23 | 160 | subsys_initcall(echainiv_module_init); |
a10f554f HX |
161 | module_exit(echainiv_module_exit); |
162 | ||
163 | MODULE_LICENSE("GPL"); | |
164 | MODULE_DESCRIPTION("Encrypted Chain IV Generator"); | |
165 | MODULE_ALIAS_CRYPTO("echainiv"); |