Commit | Line | Data |
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a10f554f HX |
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 | ||
d97de47c | 21 | #include <crypto/internal/geniv.h> |
a10f554f HX |
22 | #include <crypto/null.h> |
23 | #include <crypto/rng.h> | |
24 | #include <crypto/scatterwalk.h> | |
25 | #include <linux/err.h> | |
26 | #include <linux/init.h> | |
27 | #include <linux/kernel.h> | |
28 | #include <linux/mm.h> | |
29 | #include <linux/module.h> | |
30 | #include <linux/percpu.h> | |
31 | #include <linux/spinlock.h> | |
32 | #include <linux/string.h> | |
33 | ||
34 | #define MAX_IV_SIZE 16 | |
35 | ||
a10f554f | 36 | struct echainiv_ctx { |
d97de47c HX |
37 | /* aead_geniv_ctx must be first the element */ |
38 | struct aead_geniv_ctx geniv; | |
a10f554f HX |
39 | struct crypto_blkcipher *null; |
40 | u8 salt[] __attribute__ ((aligned(__alignof__(u32)))); | |
41 | }; | |
42 | ||
43 | static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv); | |
44 | ||
a10f554f | 45 | /* We don't care if we get preempted and read/write IVs from the next CPU. */ |
622ff875 | 46 | static void echainiv_read_iv(u8 *dst, unsigned size) |
a10f554f HX |
47 | { |
48 | u32 *a = (u32 *)dst; | |
49 | u32 __percpu *b = echainiv_iv; | |
50 | ||
51 | for (; size >= 4; size -= 4) { | |
52 | *a++ = this_cpu_read(*b); | |
53 | b++; | |
54 | } | |
55 | } | |
56 | ||
622ff875 | 57 | static void echainiv_write_iv(const u8 *src, unsigned size) |
a10f554f HX |
58 | { |
59 | const u32 *a = (const u32 *)src; | |
60 | u32 __percpu *b = echainiv_iv; | |
61 | ||
62 | for (; size >= 4; size -= 4) { | |
63 | this_cpu_write(*b, *a); | |
64 | a++; | |
65 | b++; | |
66 | } | |
67 | } | |
68 | ||
a10f554f HX |
69 | static void echainiv_encrypt_complete2(struct aead_request *req, int err) |
70 | { | |
71 | struct aead_request *subreq = aead_request_ctx(req); | |
72 | struct crypto_aead *geniv; | |
73 | unsigned int ivsize; | |
74 | ||
75 | if (err == -EINPROGRESS) | |
76 | return; | |
77 | ||
78 | if (err) | |
79 | goto out; | |
80 | ||
81 | geniv = crypto_aead_reqtfm(req); | |
82 | ivsize = crypto_aead_ivsize(geniv); | |
83 | ||
84 | echainiv_write_iv(subreq->iv, ivsize); | |
85 | ||
86 | if (req->iv != subreq->iv) | |
87 | memcpy(req->iv, subreq->iv, ivsize); | |
88 | ||
89 | out: | |
90 | if (req->iv != subreq->iv) | |
91 | kzfree(subreq->iv); | |
92 | } | |
93 | ||
94 | static void echainiv_encrypt_complete(struct crypto_async_request *base, | |
95 | int err) | |
96 | { | |
97 | struct aead_request *req = base->data; | |
98 | ||
99 | echainiv_encrypt_complete2(req, err); | |
100 | aead_request_complete(req, err); | |
101 | } | |
102 | ||
a10f554f HX |
103 | static int echainiv_encrypt(struct aead_request *req) |
104 | { | |
105 | struct crypto_aead *geniv = crypto_aead_reqtfm(req); | |
106 | struct echainiv_ctx *ctx = crypto_aead_ctx(geniv); | |
107 | struct aead_request *subreq = aead_request_ctx(req); | |
108 | crypto_completion_t compl; | |
109 | void *data; | |
110 | u8 *info; | |
823655c9 | 111 | unsigned int ivsize = crypto_aead_ivsize(geniv); |
a10f554f HX |
112 | int err; |
113 | ||
823655c9 HX |
114 | if (req->cryptlen < ivsize) |
115 | return -EINVAL; | |
116 | ||
d97de47c | 117 | aead_request_set_tfm(subreq, ctx->geniv.child); |
a10f554f HX |
118 | |
119 | compl = echainiv_encrypt_complete; | |
120 | data = req; | |
121 | info = req->iv; | |
122 | ||
a10f554f | 123 | if (req->src != req->dst) { |
a10f554f HX |
124 | struct blkcipher_desc desc = { |
125 | .tfm = ctx->null, | |
126 | }; | |
127 | ||
128 | err = crypto_blkcipher_encrypt( | |
838c9d56 HX |
129 | &desc, req->dst, req->src, |
130 | req->assoclen + req->cryptlen); | |
a10f554f HX |
131 | if (err) |
132 | return err; | |
133 | } | |
134 | ||
135 | if (unlikely(!IS_ALIGNED((unsigned long)info, | |
136 | crypto_aead_alignmask(geniv) + 1))) { | |
137 | info = kmalloc(ivsize, req->base.flags & | |
138 | CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: | |
139 | GFP_ATOMIC); | |
140 | if (!info) | |
141 | return -ENOMEM; | |
142 | ||
143 | memcpy(info, req->iv, ivsize); | |
144 | } | |
145 | ||
146 | aead_request_set_callback(subreq, req->base.flags, compl, data); | |
147 | aead_request_set_crypt(subreq, req->dst, req->dst, | |
148 | req->cryptlen - ivsize, info); | |
374d4ad1 | 149 | aead_request_set_ad(subreq, req->assoclen + ivsize); |
a10f554f HX |
150 | |
151 | crypto_xor(info, ctx->salt, ivsize); | |
152 | scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1); | |
153 | echainiv_read_iv(info, ivsize); | |
154 | ||
155 | err = crypto_aead_encrypt(subreq); | |
156 | echainiv_encrypt_complete2(req, err); | |
157 | return err; | |
158 | } | |
159 | ||
a10f554f HX |
160 | static int echainiv_decrypt(struct aead_request *req) |
161 | { | |
162 | struct crypto_aead *geniv = crypto_aead_reqtfm(req); | |
163 | struct echainiv_ctx *ctx = crypto_aead_ctx(geniv); | |
164 | struct aead_request *subreq = aead_request_ctx(req); | |
165 | crypto_completion_t compl; | |
166 | void *data; | |
823655c9 HX |
167 | unsigned int ivsize = crypto_aead_ivsize(geniv); |
168 | ||
169 | if (req->cryptlen < ivsize + crypto_aead_authsize(geniv)) | |
170 | return -EINVAL; | |
a10f554f | 171 | |
d97de47c | 172 | aead_request_set_tfm(subreq, ctx->geniv.child); |
a10f554f HX |
173 | |
174 | compl = req->base.complete; | |
175 | data = req->base.data; | |
176 | ||
a10f554f HX |
177 | aead_request_set_callback(subreq, req->base.flags, compl, data); |
178 | aead_request_set_crypt(subreq, req->src, req->dst, | |
179 | req->cryptlen - ivsize, req->iv); | |
374d4ad1 | 180 | aead_request_set_ad(subreq, req->assoclen + ivsize); |
a10f554f HX |
181 | |
182 | scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0); | |
183 | if (req->src != req->dst) | |
184 | scatterwalk_map_and_copy(req->iv, req->dst, | |
185 | req->assoclen, ivsize, 1); | |
186 | ||
187 | return crypto_aead_decrypt(subreq); | |
188 | } | |
189 | ||
a10f554f HX |
190 | static int echainiv_init(struct crypto_tfm *tfm) |
191 | { | |
192 | struct crypto_aead *geniv = __crypto_aead_cast(tfm); | |
193 | struct echainiv_ctx *ctx = crypto_aead_ctx(geniv); | |
194 | int err; | |
195 | ||
d97de47c | 196 | spin_lock_init(&ctx->geniv.lock); |
a10f554f HX |
197 | |
198 | crypto_aead_set_reqsize(geniv, sizeof(struct aead_request)); | |
199 | ||
9fcc704d HX |
200 | err = crypto_get_default_rng(); |
201 | if (err) | |
202 | goto out; | |
203 | ||
f261c5fb HX |
204 | err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt, |
205 | crypto_aead_ivsize(geniv)); | |
9fcc704d | 206 | crypto_put_default_rng(); |
f261c5fb HX |
207 | if (err) |
208 | goto out; | |
209 | ||
a10f554f HX |
210 | ctx->null = crypto_get_default_null_skcipher(); |
211 | err = PTR_ERR(ctx->null); | |
212 | if (IS_ERR(ctx->null)) | |
213 | goto out; | |
214 | ||
215 | err = aead_geniv_init(tfm); | |
216 | if (err) | |
217 | goto drop_null; | |
218 | ||
d97de47c | 219 | ctx->geniv.child = geniv->child; |
a10f554f HX |
220 | geniv->child = geniv; |
221 | ||
222 | out: | |
223 | return err; | |
224 | ||
225 | drop_null: | |
226 | crypto_put_default_null_skcipher(); | |
227 | goto out; | |
228 | } | |
229 | ||
a10f554f HX |
230 | static void echainiv_exit(struct crypto_tfm *tfm) |
231 | { | |
232 | struct echainiv_ctx *ctx = crypto_tfm_ctx(tfm); | |
233 | ||
d97de47c | 234 | crypto_free_aead(ctx->geniv.child); |
a10f554f HX |
235 | crypto_put_default_null_skcipher(); |
236 | } | |
237 | ||
1e419c79 HX |
238 | static int echainiv_aead_create(struct crypto_template *tmpl, |
239 | struct rtattr **tb) | |
a10f554f HX |
240 | { |
241 | struct aead_instance *inst; | |
242 | struct crypto_aead_spawn *spawn; | |
243 | struct aead_alg *alg; | |
1e419c79 | 244 | int err; |
a10f554f | 245 | |
1e419c79 | 246 | inst = aead_geniv_alloc(tmpl, tb, 0, 0); |
a10f554f HX |
247 | |
248 | if (IS_ERR(inst)) | |
1e419c79 | 249 | return PTR_ERR(inst); |
a10f554f | 250 | |
d97de47c HX |
251 | spawn = aead_instance_ctx(inst); |
252 | alg = crypto_spawn_aead_alg(spawn); | |
253 | ||
254 | if (alg->base.cra_aead.encrypt) | |
255 | goto done; | |
256 | ||
1e419c79 | 257 | err = -EINVAL; |
d97de47c | 258 | if (inst->alg.ivsize & (sizeof(u32) - 1) || |
1e419c79 HX |
259 | inst->alg.ivsize > MAX_IV_SIZE) |
260 | goto free_inst; | |
a10f554f | 261 | |
f261c5fb | 262 | inst->alg.encrypt = echainiv_encrypt; |
a10f554f HX |
263 | inst->alg.decrypt = echainiv_decrypt; |
264 | ||
265 | inst->alg.base.cra_init = echainiv_init; | |
266 | inst->alg.base.cra_exit = echainiv_exit; | |
267 | ||
268 | inst->alg.base.cra_alignmask |= __alignof__(u32) - 1; | |
269 | inst->alg.base.cra_ctxsize = sizeof(struct echainiv_ctx); | |
9d03aee1 | 270 | inst->alg.base.cra_ctxsize += inst->alg.ivsize; |
a10f554f | 271 | |
d97de47c | 272 | done: |
1e419c79 HX |
273 | err = aead_register_instance(tmpl, inst); |
274 | if (err) | |
275 | goto free_inst; | |
276 | ||
a10f554f | 277 | out: |
1e419c79 HX |
278 | return err; |
279 | ||
280 | free_inst: | |
281 | aead_geniv_free(inst); | |
282 | goto out; | |
a10f554f HX |
283 | } |
284 | ||
a10f554f HX |
285 | static void echainiv_free(struct crypto_instance *inst) |
286 | { | |
287 | aead_geniv_free(aead_instance(inst)); | |
a10f554f HX |
288 | } |
289 | ||
290 | static struct crypto_template echainiv_tmpl = { | |
291 | .name = "echainiv", | |
9fcc704d | 292 | .create = echainiv_aead_create, |
a10f554f HX |
293 | .free = echainiv_free, |
294 | .module = THIS_MODULE, | |
295 | }; | |
296 | ||
297 | static int __init echainiv_module_init(void) | |
298 | { | |
299 | return crypto_register_template(&echainiv_tmpl); | |
300 | } | |
301 | ||
302 | static void __exit echainiv_module_exit(void) | |
303 | { | |
304 | crypto_unregister_template(&echainiv_tmpl); | |
305 | } | |
306 | ||
307 | module_init(echainiv_module_init); | |
308 | module_exit(echainiv_module_exit); | |
309 | ||
310 | MODULE_LICENSE("GPL"); | |
311 | MODULE_DESCRIPTION("Encrypted Chain IV Generator"); | |
312 | MODULE_ALIAS_CRYPTO("echainiv"); |