Merge remote-tracking branch 'mailbox/mailbox-for-next'
[deliverable/linux.git] / crypto / echainiv.c
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 <crypto/skcipher.h>
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
35 static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv);
36
37 /* We don't care if we get preempted and read/write IVs from the next CPU. */
38 static void echainiv_read_iv(u8 *dst, unsigned size)
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
49 static void echainiv_write_iv(const u8 *src, unsigned size)
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
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
95 static int echainiv_encrypt(struct aead_request *req)
96 {
97 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
98 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
99 struct aead_request *subreq = aead_request_ctx(req);
100 crypto_completion_t compl;
101 void *data;
102 u8 *info;
103 unsigned int ivsize = crypto_aead_ivsize(geniv);
104 int err;
105
106 if (req->cryptlen < ivsize)
107 return -EINVAL;
108
109 aead_request_set_tfm(subreq, ctx->child);
110
111 compl = echainiv_encrypt_complete;
112 data = req;
113 info = req->iv;
114
115 if (req->src != req->dst) {
116 SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
117
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);
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,
143 req->cryptlen, info);
144 aead_request_set_ad(subreq, req->assoclen);
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
155 static int echainiv_decrypt(struct aead_request *req)
156 {
157 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
158 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
159 struct aead_request *subreq = aead_request_ctx(req);
160 crypto_completion_t compl;
161 void *data;
162 unsigned int ivsize = crypto_aead_ivsize(geniv);
163
164 if (req->cryptlen < ivsize)
165 return -EINVAL;
166
167 aead_request_set_tfm(subreq, ctx->child);
168
169 compl = req->base.complete;
170 data = req->base.data;
171
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);
175 aead_request_set_ad(subreq, req->assoclen + ivsize);
176
177 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
178
179 return crypto_aead_decrypt(subreq);
180 }
181
182 static int echainiv_aead_create(struct crypto_template *tmpl,
183 struct rtattr **tb)
184 {
185 struct aead_instance *inst;
186 struct crypto_aead_spawn *spawn;
187 struct aead_alg *alg;
188 int err;
189
190 inst = aead_geniv_alloc(tmpl, tb, 0, 0);
191
192 if (IS_ERR(inst))
193 return PTR_ERR(inst);
194
195 spawn = aead_instance_ctx(inst);
196 alg = crypto_spawn_aead_alg(spawn);
197
198 err = -EINVAL;
199 if (inst->alg.ivsize & (sizeof(u32) - 1) ||
200 inst->alg.ivsize > MAX_IV_SIZE)
201 goto free_inst;
202
203 inst->alg.encrypt = echainiv_encrypt;
204 inst->alg.decrypt = echainiv_decrypt;
205
206 inst->alg.init = aead_init_geniv;
207 inst->alg.exit = aead_exit_geniv;
208
209 inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
210 inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
211 inst->alg.base.cra_ctxsize += inst->alg.ivsize;
212
213 inst->free = aead_geniv_free;
214
215 err = aead_register_instance(tmpl, inst);
216 if (err)
217 goto free_inst;
218
219 out:
220 return err;
221
222 free_inst:
223 aead_geniv_free(inst);
224 goto out;
225 }
226
227 static void echainiv_free(struct crypto_instance *inst)
228 {
229 aead_geniv_free(aead_instance(inst));
230 }
231
232 static struct crypto_template echainiv_tmpl = {
233 .name = "echainiv",
234 .create = echainiv_aead_create,
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");
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