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1/*
2 * echainiv: Encrypted Chain IV Generator
3 *
4 * This generator generates an IV based on a sequence number by xoring it
5 * with a salt and then encrypting it with the same key as used to encrypt
6 * the plain text. This algorithm requires that the block size be equal
7 * to the IV size. It is mainly useful for CBC.
8 *
9 * This generator can only be used by algorithms where authentication
10 * is performed after encryption (i.e., authenc).
11 *
12 * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
13 *
14 * This program is free software; you can redistribute it and/or modify it
15 * under the terms of the GNU General Public License as published by the Free
16 * Software Foundation; either version 2 of the License, or (at your option)
17 * any later version.
18 *
19 */
20
21#include <crypto/internal/geniv.h>
22#include <crypto/scatterwalk.h>
23#include <linux/err.h>
24#include <linux/init.h>
25#include <linux/kernel.h>
26#include <linux/mm.h>
27#include <linux/module.h>
28#include <linux/percpu.h>
29#include <linux/spinlock.h>
30#include <linux/string.h>
31
32#define MAX_IV_SIZE 16
33
34static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv);
35
36/* We don't care if we get preempted and read/write IVs from the next CPU. */
37static void echainiv_read_iv(u8 *dst, unsigned size)
38{
39 u32 *a = (u32 *)dst;
40 u32 __percpu *b = echainiv_iv;
41
42 for (; size >= 4; size -= 4) {
43 *a++ = this_cpu_read(*b);
44 b++;
45 }
46}
47
48static void echainiv_write_iv(const u8 *src, unsigned size)
49{
50 const u32 *a = (const u32 *)src;
51 u32 __percpu *b = echainiv_iv;
52
53 for (; size >= 4; size -= 4) {
54 this_cpu_write(*b, *a);
55 a++;
56 b++;
57 }
58}
59
60static void echainiv_encrypt_complete2(struct aead_request *req, int err)
61{
62 struct aead_request *subreq = aead_request_ctx(req);
63 struct crypto_aead *geniv;
64 unsigned int ivsize;
65
66 if (err == -EINPROGRESS)
67 return;
68
69 if (err)
70 goto out;
71
72 geniv = crypto_aead_reqtfm(req);
73 ivsize = crypto_aead_ivsize(geniv);
74
75 echainiv_write_iv(subreq->iv, ivsize);
76
77 if (req->iv != subreq->iv)
78 memcpy(req->iv, subreq->iv, ivsize);
79
80out:
81 if (req->iv != subreq->iv)
82 kzfree(subreq->iv);
83}
84
85static void echainiv_encrypt_complete(struct crypto_async_request *base,
86 int err)
87{
88 struct aead_request *req = base->data;
89
90 echainiv_encrypt_complete2(req, err);
91 aead_request_complete(req, err);
92}
93
94static int echainiv_encrypt(struct aead_request *req)
95{
96 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
97 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
98 struct aead_request *subreq = aead_request_ctx(req);
99 crypto_completion_t compl;
100 void *data;
101 u8 *info;
102 unsigned int ivsize = crypto_aead_ivsize(geniv);
103 int err;
104
105 if (req->cryptlen < ivsize)
106 return -EINVAL;
107
108 aead_request_set_tfm(subreq, ctx->child);
109
110 compl = echainiv_encrypt_complete;
111 data = req;
112 info = req->iv;
113
114 if (req->src != req->dst) {
115 struct blkcipher_desc desc = {
116 .tfm = ctx->null,
117 };
118
119 err = crypto_blkcipher_encrypt(
120 &desc, req->dst, req->src,
121 req->assoclen + req->cryptlen);
122 if (err)
123 return err;
124 }
125
126 if (unlikely(!IS_ALIGNED((unsigned long)info,
127 crypto_aead_alignmask(geniv) + 1))) {
128 info = kmalloc(ivsize, req->base.flags &
129 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
130 GFP_ATOMIC);
131 if (!info)
132 return -ENOMEM;
133
134 memcpy(info, req->iv, ivsize);
135 }
136
137 aead_request_set_callback(subreq, req->base.flags, compl, data);
138 aead_request_set_crypt(subreq, req->dst, req->dst,
139 req->cryptlen, info);
140 aead_request_set_ad(subreq, req->assoclen);
141
142 crypto_xor(info, ctx->salt, ivsize);
143 scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
144 echainiv_read_iv(info, ivsize);
145
146 err = crypto_aead_encrypt(subreq);
147 echainiv_encrypt_complete2(req, err);
148 return err;
149}
150
151static int echainiv_decrypt(struct aead_request *req)
152{
153 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
154 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
155 struct aead_request *subreq = aead_request_ctx(req);
156 crypto_completion_t compl;
157 void *data;
158 unsigned int ivsize = crypto_aead_ivsize(geniv);
159
160 if (req->cryptlen < ivsize)
161 return -EINVAL;
162
163 aead_request_set_tfm(subreq, ctx->child);
164
165 compl = req->base.complete;
166 data = req->base.data;
167
168 aead_request_set_callback(subreq, req->base.flags, compl, data);
169 aead_request_set_crypt(subreq, req->src, req->dst,
170 req->cryptlen - ivsize, req->iv);
171 aead_request_set_ad(subreq, req->assoclen + ivsize);
172
173 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
174
175 return crypto_aead_decrypt(subreq);
176}
177
178static int echainiv_aead_create(struct crypto_template *tmpl,
179 struct rtattr **tb)
180{
181 struct aead_instance *inst;
182 struct crypto_aead_spawn *spawn;
183 struct aead_alg *alg;
184 int err;
185
186 inst = aead_geniv_alloc(tmpl, tb, 0, 0);
187
188 if (IS_ERR(inst))
189 return PTR_ERR(inst);
190
191 spawn = aead_instance_ctx(inst);
192 alg = crypto_spawn_aead_alg(spawn);
193
194 err = -EINVAL;
195 if (inst->alg.ivsize & (sizeof(u32) - 1) ||
196 inst->alg.ivsize > MAX_IV_SIZE)
197 goto free_inst;
198
199 inst->alg.encrypt = echainiv_encrypt;
200 inst->alg.decrypt = echainiv_decrypt;
201
202 inst->alg.init = aead_init_geniv;
203 inst->alg.exit = aead_exit_geniv;
204
205 inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
206 inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
207 inst->alg.base.cra_ctxsize += inst->alg.ivsize;
208
209 inst->free = aead_geniv_free;
210
211 err = aead_register_instance(tmpl, inst);
212 if (err)
213 goto free_inst;
214
215out:
216 return err;
217
218free_inst:
219 aead_geniv_free(inst);
220 goto out;
221}
222
223static void echainiv_free(struct crypto_instance *inst)
224{
225 aead_geniv_free(aead_instance(inst));
226}
227
228static struct crypto_template echainiv_tmpl = {
229 .name = "echainiv",
230 .create = echainiv_aead_create,
231 .free = echainiv_free,
232 .module = THIS_MODULE,
233};
234
235static int __init echainiv_module_init(void)
236{
237 return crypto_register_template(&echainiv_tmpl);
238}
239
240static void __exit echainiv_module_exit(void)
241{
242 crypto_unregister_template(&echainiv_tmpl);
243}
244
245module_init(echainiv_module_init);
246module_exit(echainiv_module_exit);
247
248MODULE_LICENSE("GPL");
249MODULE_DESCRIPTION("Encrypted Chain IV Generator");
250MODULE_ALIAS_CRYPTO("echainiv");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * echainiv: Encrypted Chain IV Generator
4 *
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
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>
14 */
15
16#include <crypto/internal/geniv.h>
17#include <crypto/scatterwalk.h>
18#include <crypto/skcipher.h>
19#include <linux/err.h>
20#include <linux/init.h>
21#include <linux/kernel.h>
22#include <linux/module.h>
23#include <linux/slab.h>
24#include <linux/string.h>
25
26static int echainiv_encrypt(struct aead_request *req)
27{
28 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
29 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
30 struct aead_request *subreq = aead_request_ctx(req);
31 __be64 nseqno;
32 u64 seqno;
33 u8 *info;
34 unsigned int ivsize = crypto_aead_ivsize(geniv);
35 int err;
36
37 if (req->cryptlen < ivsize)
38 return -EINVAL;
39
40 aead_request_set_tfm(subreq, ctx->child);
41
42 info = req->iv;
43
44 if (req->src != req->dst) {
45 SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
46
47 skcipher_request_set_sync_tfm(nreq, ctx->sknull);
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);
55 if (err)
56 return err;
57 }
58
59 aead_request_set_callback(subreq, req->base.flags,
60 req->base.complete, req->base.data);
61 aead_request_set_crypt(subreq, req->dst, req->dst,
62 req->cryptlen, info);
63 aead_request_set_ad(subreq, req->assoclen);
64
65 memcpy(&nseqno, info + ivsize - 8, 8);
66 seqno = be64_to_cpu(nseqno);
67 memset(info, 0, ivsize);
68
69 scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
70
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);
83}
84
85static int echainiv_decrypt(struct aead_request *req)
86{
87 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
88 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
89 struct aead_request *subreq = aead_request_ctx(req);
90 crypto_completion_t compl;
91 void *data;
92 unsigned int ivsize = crypto_aead_ivsize(geniv);
93
94 if (req->cryptlen < ivsize)
95 return -EINVAL;
96
97 aead_request_set_tfm(subreq, ctx->child);
98
99 compl = req->base.complete;
100 data = req->base.data;
101
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);
105 aead_request_set_ad(subreq, req->assoclen + ivsize);
106
107 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
108
109 return crypto_aead_decrypt(subreq);
110}
111
112static int echainiv_aead_create(struct crypto_template *tmpl,
113 struct rtattr **tb)
114{
115 struct aead_instance *inst;
116 int err;
117
118 inst = aead_geniv_alloc(tmpl, tb);
119
120 if (IS_ERR(inst))
121 return PTR_ERR(inst);
122
123 err = -EINVAL;
124 if (inst->alg.ivsize & (sizeof(u64) - 1) || !inst->alg.ivsize)
125 goto free_inst;
126
127 inst->alg.encrypt = echainiv_encrypt;
128 inst->alg.decrypt = echainiv_decrypt;
129
130 inst->alg.init = aead_init_geniv;
131 inst->alg.exit = aead_exit_geniv;
132
133 inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
134 inst->alg.base.cra_ctxsize += inst->alg.ivsize;
135
136 err = aead_register_instance(tmpl, inst);
137 if (err) {
138free_inst:
139 inst->free(inst);
140 }
141 return err;
142}
143
144static struct crypto_template echainiv_tmpl = {
145 .name = "echainiv",
146 .create = echainiv_aead_create,
147 .module = THIS_MODULE,
148};
149
150static int __init echainiv_module_init(void)
151{
152 return crypto_register_template(&echainiv_tmpl);
153}
154
155static void __exit echainiv_module_exit(void)
156{
157 crypto_unregister_template(&echainiv_tmpl);
158}
159
160subsys_initcall(echainiv_module_init);
161module_exit(echainiv_module_exit);
162
163MODULE_LICENSE("GPL");
164MODULE_DESCRIPTION("Encrypted Chain IV Generator");
165MODULE_ALIAS_CRYPTO("echainiv");