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 | 22 | #include <crypto/scatterwalk.h> |
0e8bff47 | 23 | #include <crypto/skcipher.h> |
a10f554f HX |
24 | #include <linux/err.h> |
25 | #include <linux/init.h> | |
26 | #include <linux/kernel.h> | |
27 | #include <linux/mm.h> | |
28 | #include <linux/module.h> | |
29 | #include <linux/percpu.h> | |
30 | #include <linux/spinlock.h> | |
31 | #include <linux/string.h> | |
32 | ||
33 | #define MAX_IV_SIZE 16 | |
34 | ||
a10f554f HX |
35 | static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv); |
36 | ||
a10f554f | 37 | /* We don't care if we get preempted and read/write IVs from the next CPU. */ |
622ff875 | 38 | static void echainiv_read_iv(u8 *dst, unsigned size) |
a10f554f HX |
39 | { |
40 | u32 *a = (u32 *)dst; | |
41 | u32 __percpu *b = echainiv_iv; | |
42 | ||
43 | for (; size >= 4; size -= 4) { | |
44 | *a++ = this_cpu_read(*b); | |
45 | b++; | |
46 | } | |
47 | } | |
48 | ||
622ff875 | 49 | static void echainiv_write_iv(const u8 *src, unsigned size) |
a10f554f HX |
50 | { |
51 | const u32 *a = (const u32 *)src; | |
52 | u32 __percpu *b = echainiv_iv; | |
53 | ||
54 | for (; size >= 4; size -= 4) { | |
55 | this_cpu_write(*b, *a); | |
56 | a++; | |
57 | b++; | |
58 | } | |
59 | } | |
60 | ||
a10f554f HX |
61 | static void echainiv_encrypt_complete2(struct aead_request *req, int err) |
62 | { | |
63 | struct aead_request *subreq = aead_request_ctx(req); | |
64 | struct crypto_aead *geniv; | |
65 | unsigned int ivsize; | |
66 | ||
67 | if (err == -EINPROGRESS) | |
68 | return; | |
69 | ||
70 | if (err) | |
71 | goto out; | |
72 | ||
73 | geniv = crypto_aead_reqtfm(req); | |
74 | ivsize = crypto_aead_ivsize(geniv); | |
75 | ||
76 | echainiv_write_iv(subreq->iv, ivsize); | |
77 | ||
78 | if (req->iv != subreq->iv) | |
79 | memcpy(req->iv, subreq->iv, ivsize); | |
80 | ||
81 | out: | |
82 | if (req->iv != subreq->iv) | |
83 | kzfree(subreq->iv); | |
84 | } | |
85 | ||
86 | static void echainiv_encrypt_complete(struct crypto_async_request *base, | |
87 | int err) | |
88 | { | |
89 | struct aead_request *req = base->data; | |
90 | ||
91 | echainiv_encrypt_complete2(req, err); | |
92 | aead_request_complete(req, err); | |
93 | } | |
94 | ||
a10f554f HX |
95 | static int echainiv_encrypt(struct aead_request *req) |
96 | { | |
97 | struct crypto_aead *geniv = crypto_aead_reqtfm(req); | |
376e0d69 | 98 | struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); |
a10f554f HX |
99 | struct aead_request *subreq = aead_request_ctx(req); |
100 | crypto_completion_t compl; | |
101 | void *data; | |
102 | u8 *info; | |
823655c9 | 103 | unsigned int ivsize = crypto_aead_ivsize(geniv); |
a10f554f HX |
104 | int err; |
105 | ||
823655c9 HX |
106 | if (req->cryptlen < ivsize) |
107 | return -EINVAL; | |
108 | ||
376e0d69 | 109 | aead_request_set_tfm(subreq, ctx->child); |
a10f554f HX |
110 | |
111 | compl = echainiv_encrypt_complete; | |
112 | data = req; | |
113 | info = req->iv; | |
114 | ||
a10f554f | 115 | if (req->src != req->dst) { |
0e8bff47 | 116 | SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull); |
a10f554f | 117 | |
0e8bff47 HX |
118 | skcipher_request_set_tfm(nreq, ctx->sknull); |
119 | skcipher_request_set_callback(nreq, req->base.flags, | |
120 | NULL, NULL); | |
121 | skcipher_request_set_crypt(nreq, req->src, req->dst, | |
122 | req->assoclen + req->cryptlen, | |
123 | NULL); | |
124 | ||
125 | err = crypto_skcipher_encrypt(nreq); | |
a10f554f HX |
126 | if (err) |
127 | return err; | |
128 | } | |
129 | ||
130 | if (unlikely(!IS_ALIGNED((unsigned long)info, | |
131 | crypto_aead_alignmask(geniv) + 1))) { | |
132 | info = kmalloc(ivsize, req->base.flags & | |
133 | CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: | |
134 | GFP_ATOMIC); | |
135 | if (!info) | |
136 | return -ENOMEM; | |
137 | ||
138 | memcpy(info, req->iv, ivsize); | |
139 | } | |
140 | ||
141 | aead_request_set_callback(subreq, req->base.flags, compl, data); | |
142 | aead_request_set_crypt(subreq, req->dst, req->dst, | |
5499b1a7 HX |
143 | req->cryptlen, info); |
144 | aead_request_set_ad(subreq, req->assoclen); | |
a10f554f HX |
145 | |
146 | crypto_xor(info, ctx->salt, ivsize); | |
147 | scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1); | |
148 | echainiv_read_iv(info, ivsize); | |
149 | ||
150 | err = crypto_aead_encrypt(subreq); | |
151 | echainiv_encrypt_complete2(req, err); | |
152 | return err; | |
153 | } | |
154 | ||
a10f554f HX |
155 | static int echainiv_decrypt(struct aead_request *req) |
156 | { | |
157 | struct crypto_aead *geniv = crypto_aead_reqtfm(req); | |
376e0d69 | 158 | struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); |
a10f554f HX |
159 | struct aead_request *subreq = aead_request_ctx(req); |
160 | crypto_completion_t compl; | |
161 | void *data; | |
823655c9 HX |
162 | unsigned int ivsize = crypto_aead_ivsize(geniv); |
163 | ||
5499b1a7 | 164 | if (req->cryptlen < ivsize) |
823655c9 | 165 | return -EINVAL; |
a10f554f | 166 | |
376e0d69 | 167 | aead_request_set_tfm(subreq, ctx->child); |
a10f554f HX |
168 | |
169 | compl = req->base.complete; | |
170 | data = req->base.data; | |
171 | ||
a10f554f HX |
172 | aead_request_set_callback(subreq, req->base.flags, compl, data); |
173 | aead_request_set_crypt(subreq, req->src, req->dst, | |
174 | req->cryptlen - ivsize, req->iv); | |
374d4ad1 | 175 | aead_request_set_ad(subreq, req->assoclen + ivsize); |
a10f554f HX |
176 | |
177 | scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0); | |
a10f554f HX |
178 | |
179 | return crypto_aead_decrypt(subreq); | |
180 | } | |
181 | ||
1e419c79 HX |
182 | static int echainiv_aead_create(struct crypto_template *tmpl, |
183 | struct rtattr **tb) | |
a10f554f HX |
184 | { |
185 | struct aead_instance *inst; | |
186 | struct crypto_aead_spawn *spawn; | |
187 | struct aead_alg *alg; | |
1e419c79 | 188 | int err; |
a10f554f | 189 | |
1e419c79 | 190 | inst = aead_geniv_alloc(tmpl, tb, 0, 0); |
a10f554f HX |
191 | |
192 | if (IS_ERR(inst)) | |
1e419c79 | 193 | return PTR_ERR(inst); |
a10f554f | 194 | |
d97de47c HX |
195 | spawn = aead_instance_ctx(inst); |
196 | alg = crypto_spawn_aead_alg(spawn); | |
197 | ||
1e419c79 | 198 | err = -EINVAL; |
d97de47c | 199 | if (inst->alg.ivsize & (sizeof(u32) - 1) || |
1e419c79 HX |
200 | inst->alg.ivsize > MAX_IV_SIZE) |
201 | goto free_inst; | |
a10f554f | 202 | |
f261c5fb | 203 | inst->alg.encrypt = echainiv_encrypt; |
a10f554f HX |
204 | inst->alg.decrypt = echainiv_decrypt; |
205 | ||
376e0d69 HX |
206 | inst->alg.init = aead_init_geniv; |
207 | inst->alg.exit = aead_exit_geniv; | |
a10f554f HX |
208 | |
209 | inst->alg.base.cra_alignmask |= __alignof__(u32) - 1; | |
376e0d69 | 210 | inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx); |
9d03aee1 | 211 | inst->alg.base.cra_ctxsize += inst->alg.ivsize; |
a10f554f | 212 | |
5499b1a7 HX |
213 | inst->free = aead_geniv_free; |
214 | ||
1e419c79 HX |
215 | err = aead_register_instance(tmpl, inst); |
216 | if (err) | |
217 | goto free_inst; | |
218 | ||
a10f554f | 219 | out: |
1e419c79 HX |
220 | return err; |
221 | ||
222 | free_inst: | |
223 | aead_geniv_free(inst); | |
224 | goto out; | |
a10f554f HX |
225 | } |
226 | ||
a10f554f HX |
227 | static void echainiv_free(struct crypto_instance *inst) |
228 | { | |
229 | aead_geniv_free(aead_instance(inst)); | |
a10f554f HX |
230 | } |
231 | ||
232 | static struct crypto_template echainiv_tmpl = { | |
233 | .name = "echainiv", | |
9fcc704d | 234 | .create = echainiv_aead_create, |
a10f554f HX |
235 | .free = echainiv_free, |
236 | .module = THIS_MODULE, | |
237 | }; | |
238 | ||
239 | static int __init echainiv_module_init(void) | |
240 | { | |
241 | return crypto_register_template(&echainiv_tmpl); | |
242 | } | |
243 | ||
244 | static void __exit echainiv_module_exit(void) | |
245 | { | |
246 | crypto_unregister_template(&echainiv_tmpl); | |
247 | } | |
248 | ||
249 | module_init(echainiv_module_init); | |
250 | module_exit(echainiv_module_exit); | |
251 | ||
252 | MODULE_LICENSE("GPL"); | |
253 | MODULE_DESCRIPTION("Encrypted Chain IV Generator"); | |
254 | MODULE_ALIAS_CRYPTO("echainiv"); |