Merge tag 'media/v4.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab...
[firefly-linux-kernel-4.4.55.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 <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
34 static 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. */
37 static 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
48 static 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
60 static 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
80 out:
81         if (req->iv != subreq->iv)
82                 kzfree(subreq->iv);
83 }
84
85 static 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
94 static 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
151 static 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
178 static 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
215 out:
216         return err;
217
218 free_inst:
219         aead_geniv_free(inst);
220         goto out;
221 }
222
223 static void echainiv_free(struct crypto_instance *inst)
224 {
225         aead_geniv_free(aead_instance(inst));
226 }
227
228 static struct crypto_template echainiv_tmpl = {
229         .name = "echainiv",
230         .create = echainiv_aead_create,
231         .free = echainiv_free,
232         .module = THIS_MODULE,
233 };
234
235 static int __init echainiv_module_init(void)
236 {
237         return crypto_register_template(&echainiv_tmpl);
238 }
239
240 static void __exit echainiv_module_exit(void)
241 {
242         crypto_unregister_template(&echainiv_tmpl);
243 }
244
245 module_init(echainiv_module_init);
246 module_exit(echainiv_module_exit);
247
248 MODULE_LICENSE("GPL");
249 MODULE_DESCRIPTION("Encrypted Chain IV Generator");
250 MODULE_ALIAS_CRYPTO("echainiv");