aboutsummaryrefslogtreecommitdiffstats
path: root/crypto/xts.c
diff options
context:
space:
mode:
Diffstat (limited to 'crypto/xts.c')
-rw-r--r--crypto/xts.c292
1 files changed, 292 insertions, 0 deletions
diff --git a/crypto/xts.c b/crypto/xts.c
new file mode 100644
index 000000000000..8eb08bfaf7c0
--- /dev/null
+++ b/crypto/xts.c
@@ -0,0 +1,292 @@
1/* XTS: as defined in IEEE1619/D16
2 * http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
3 * (sector sizes which are not a multiple of 16 bytes are,
4 * however currently unsupported)
5 *
6 * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
7 *
8 * Based om ecb.c
9 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
10 *
11 * This program is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the Free
13 * Software Foundation; either version 2 of the License, or (at your option)
14 * any later version.
15 */
16#include <crypto/algapi.h>
17#include <linux/err.h>
18#include <linux/init.h>
19#include <linux/kernel.h>
20#include <linux/module.h>
21#include <linux/scatterlist.h>
22#include <linux/slab.h>
23
24#include <crypto/b128ops.h>
25#include <crypto/gf128mul.h>
26
27struct priv {
28 struct crypto_cipher *child;
29 struct crypto_cipher *tweak;
30};
31
32static int setkey(struct crypto_tfm *parent, const u8 *key,
33 unsigned int keylen)
34{
35 struct priv *ctx = crypto_tfm_ctx(parent);
36 struct crypto_cipher *child = ctx->tweak;
37 u32 *flags = &parent->crt_flags;
38 int err;
39
40 /* key consists of keys of equal size concatenated, therefore
41 * the length must be even */
42 if (keylen % 2) {
43 /* tell the user why there was an error */
44 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
45 return -EINVAL;
46 }
47
48 /* we need two cipher instances: one to compute the inital 'tweak'
49 * by encrypting the IV (usually the 'plain' iv) and the other
50 * one to encrypt and decrypt the data */
51
52 /* tweak cipher, uses Key2 i.e. the second half of *key */
53 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
54 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
55 CRYPTO_TFM_REQ_MASK);
56 err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
57 if (err)
58 return err;
59
60 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
61 CRYPTO_TFM_RES_MASK);
62
63 child = ctx->child;
64
65 /* data cipher, uses Key1 i.e. the first half of *key */
66 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
67 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
68 CRYPTO_TFM_REQ_MASK);
69 err = crypto_cipher_setkey(child, key, keylen/2);
70 if (err)
71 return err;
72
73 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
74 CRYPTO_TFM_RES_MASK);
75
76 return 0;
77}
78
79struct sinfo {
80 be128 t;
81 struct crypto_tfm *tfm;
82 void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
83};
84
85static inline void xts_round(struct sinfo *s, void *dst, const void *src)
86{
87 be128_xor(dst, &s->t, src); /* PP <- T xor P */
88 s->fn(s->tfm, dst, dst); /* CC <- E(Key1,PP) */
89 be128_xor(dst, dst, &s->t); /* C <- T xor CC */
90}
91
92static int crypt(struct blkcipher_desc *d,
93 struct blkcipher_walk *w, struct priv *ctx,
94 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
95 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
96{
97 int err;
98 unsigned int avail;
99 const int bs = crypto_cipher_blocksize(ctx->child);
100 struct sinfo s = {
101 .tfm = crypto_cipher_tfm(ctx->child),
102 .fn = fn
103 };
104 be128 *iv;
105 u8 *wsrc;
106 u8 *wdst;
107
108 err = blkcipher_walk_virt(d, w);
109 if (!w->nbytes)
110 return err;
111
112 avail = w->nbytes;
113
114 wsrc = w->src.virt.addr;
115 wdst = w->dst.virt.addr;
116
117 /* calculate first value of T */
118 iv = (be128 *)w->iv;
119 tw(crypto_cipher_tfm(ctx->tweak), (void *)&s.t, w->iv);
120
121 goto first;
122
123 for (;;) {
124 do {
125 gf128mul_x_ble(&s.t, &s.t);
126
127first:
128 xts_round(&s, wdst, wsrc);
129
130 wsrc += bs;
131 wdst += bs;
132 } while ((avail -= bs) >= bs);
133
134 err = blkcipher_walk_done(d, w, avail);
135 if (!w->nbytes)
136 break;
137
138 avail = w->nbytes;
139
140 wsrc = w->src.virt.addr;
141 wdst = w->dst.virt.addr;
142 }
143
144 return err;
145}
146
147static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
148 struct scatterlist *src, unsigned int nbytes)
149{
150 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
151 struct blkcipher_walk w;
152
153 blkcipher_walk_init(&w, dst, src, nbytes);
154 return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
155 crypto_cipher_alg(ctx->child)->cia_encrypt);
156}
157
158static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
159 struct scatterlist *src, unsigned int nbytes)
160{
161 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
162 struct blkcipher_walk w;
163
164 blkcipher_walk_init(&w, dst, src, nbytes);
165 return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
166 crypto_cipher_alg(ctx->child)->cia_decrypt);
167}
168
169static int init_tfm(struct crypto_tfm *tfm)
170{
171 struct crypto_cipher *cipher;
172 struct crypto_instance *inst = (void *)tfm->__crt_alg;
173 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
174 struct priv *ctx = crypto_tfm_ctx(tfm);
175 u32 *flags = &tfm->crt_flags;
176
177 cipher = crypto_spawn_cipher(spawn);
178 if (IS_ERR(cipher))
179 return PTR_ERR(cipher);
180
181 if (crypto_cipher_blocksize(cipher) != 16) {
182 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
183 crypto_free_cipher(cipher);
184 return -EINVAL;
185 }
186
187 ctx->child = cipher;
188
189 cipher = crypto_spawn_cipher(spawn);
190 if (IS_ERR(cipher)) {
191 crypto_free_cipher(ctx->child);
192 return PTR_ERR(cipher);
193 }
194
195 /* this check isn't really needed, leave it here just in case */
196 if (crypto_cipher_blocksize(cipher) != 16) {
197 crypto_free_cipher(cipher);
198 crypto_free_cipher(ctx->child);
199 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
200 return -EINVAL;
201 }
202
203 ctx->tweak = cipher;
204
205 return 0;
206}
207
208static void exit_tfm(struct crypto_tfm *tfm)
209{
210 struct priv *ctx = crypto_tfm_ctx(tfm);
211 crypto_free_cipher(ctx->child);
212 crypto_free_cipher(ctx->tweak);
213}
214
215static struct crypto_instance *alloc(struct rtattr **tb)
216{
217 struct crypto_instance *inst;
218 struct crypto_alg *alg;
219 int err;
220
221 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
222 if (err)
223 return ERR_PTR(err);
224
225 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
226 CRYPTO_ALG_TYPE_MASK);
227 if (IS_ERR(alg))
228 return ERR_PTR(PTR_ERR(alg));
229
230 inst = crypto_alloc_instance("xts", alg);
231 if (IS_ERR(inst))
232 goto out_put_alg;
233
234 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
235 inst->alg.cra_priority = alg->cra_priority;
236 inst->alg.cra_blocksize = alg->cra_blocksize;
237
238 if (alg->cra_alignmask < 7)
239 inst->alg.cra_alignmask = 7;
240 else
241 inst->alg.cra_alignmask = alg->cra_alignmask;
242
243 inst->alg.cra_type = &crypto_blkcipher_type;
244
245 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
246 inst->alg.cra_blkcipher.min_keysize =
247 2 * alg->cra_cipher.cia_min_keysize;
248 inst->alg.cra_blkcipher.max_keysize =
249 2 * alg->cra_cipher.cia_max_keysize;
250
251 inst->alg.cra_ctxsize = sizeof(struct priv);
252
253 inst->alg.cra_init = init_tfm;
254 inst->alg.cra_exit = exit_tfm;
255
256 inst->alg.cra_blkcipher.setkey = setkey;
257 inst->alg.cra_blkcipher.encrypt = encrypt;
258 inst->alg.cra_blkcipher.decrypt = decrypt;
259
260out_put_alg:
261 crypto_mod_put(alg);
262 return inst;
263}
264
265static void free(struct crypto_instance *inst)
266{
267 crypto_drop_spawn(crypto_instance_ctx(inst));
268 kfree(inst);
269}
270
271static struct crypto_template crypto_tmpl = {
272 .name = "xts",
273 .alloc = alloc,
274 .free = free,
275 .module = THIS_MODULE,
276};
277
278static int __init crypto_module_init(void)
279{
280 return crypto_register_template(&crypto_tmpl);
281}
282
283static void __exit crypto_module_exit(void)
284{
285 crypto_unregister_template(&crypto_tmpl);
286}
287
288module_init(crypto_module_init);
289module_exit(crypto_module_exit);
290
291MODULE_LICENSE("GPL");
292MODULE_DESCRIPTION("XTS block cipher mode");
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-22 10:48:26 -0500