drm/cirrus: Don't grab dev->struct_mutex for in mmap offset ioctl
[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/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
36 struct echainiv_ctx {
37         /* aead_geniv_ctx must be first the element */
38         struct aead_geniv_ctx geniv;
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
45 /* We don't care if we get preempted and read/write IVs from the next CPU. */
46 static void echainiv_read_iv(u8 *dst, unsigned size)
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
57 static void echainiv_write_iv(const u8 *src, unsigned size)
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
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
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;
111         unsigned int ivsize = crypto_aead_ivsize(geniv);
112         int err;
113
114         if (req->cryptlen < ivsize)
115                 return -EINVAL;
116
117         aead_request_set_tfm(subreq, ctx->geniv.child);
118
119         compl = echainiv_encrypt_complete;
120         data = req;
121         info = req->iv;
122
123         if (req->src != req->dst) {
124                 struct blkcipher_desc desc = {
125                         .tfm = ctx->null,
126                 };
127
128                 err = crypto_blkcipher_encrypt(
129                         &desc, req->dst, req->src,
130                         req->assoclen + req->cryptlen);
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);
149         aead_request_set_ad(subreq, req->assoclen + ivsize);
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
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;
167         unsigned int ivsize = crypto_aead_ivsize(geniv);
168
169         if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
170                 return -EINVAL;
171
172         aead_request_set_tfm(subreq, ctx->geniv.child);
173
174         compl = req->base.complete;
175         data = req->base.data;
176
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);
180         aead_request_set_ad(subreq, req->assoclen + ivsize);
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
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
196         spin_lock_init(&ctx->geniv.lock);
197
198         crypto_aead_set_reqsize(geniv, sizeof(struct aead_request));
199
200         err = crypto_get_default_rng();
201         if (err)
202                 goto out;
203
204         err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
205                                    crypto_aead_ivsize(geniv));
206         crypto_put_default_rng();
207         if (err)
208                 goto out;
209
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
219         ctx->geniv.child = geniv->child;
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
230 static void echainiv_exit(struct crypto_tfm *tfm)
231 {
232         struct echainiv_ctx *ctx = crypto_tfm_ctx(tfm);
233
234         crypto_free_aead(ctx->geniv.child);
235         crypto_put_default_null_skcipher();
236 }
237
238 static int echainiv_aead_create(struct crypto_template *tmpl,
239                                 struct rtattr **tb)
240 {
241         struct aead_instance *inst;
242         struct crypto_aead_spawn *spawn;
243         struct aead_alg *alg;
244         int err;
245
246         inst = aead_geniv_alloc(tmpl, tb, 0, 0);
247
248         if (IS_ERR(inst))
249                 return PTR_ERR(inst);
250
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
257         err = -EINVAL;
258         if (inst->alg.ivsize & (sizeof(u32) - 1) ||
259             inst->alg.ivsize > MAX_IV_SIZE)
260                 goto free_inst;
261
262         inst->alg.encrypt = echainiv_encrypt;
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);
270         inst->alg.base.cra_ctxsize += inst->alg.ivsize;
271
272 done:
273         err = aead_register_instance(tmpl, inst);
274         if (err)
275                 goto free_inst;
276
277 out:
278         return err;
279
280 free_inst:
281         aead_geniv_free(inst);
282         goto out;
283 }
284
285 static void echainiv_free(struct crypto_instance *inst)
286 {
287         aead_geniv_free(aead_instance(inst));
288 }
289
290 static struct crypto_template echainiv_tmpl = {
291         .name = "echainiv",
292         .create = echainiv_aead_create,
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");