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17#include <crypto/algapi.h>
18#include <linux/err.h>
19#include <linux/init.h>
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/scatterlist.h>
23#include <linux/slab.h>
24
25struct crypto_pcbc_ctx {
26 struct crypto_cipher *child;
27 void (*xor)(u8 *dst, const u8 *src, unsigned int bs);
28};
29
30static int crypto_pcbc_setkey(struct crypto_tfm *parent, const u8 *key,
31 unsigned int keylen)
32{
33 struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(parent);
34 struct crypto_cipher *child = ctx->child;
35 int err;
36
37 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
38 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
39 CRYPTO_TFM_REQ_MASK);
40 err = crypto_cipher_setkey(child, key, keylen);
41 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
42 CRYPTO_TFM_RES_MASK);
43 return err;
44}
45
46static int crypto_pcbc_encrypt_segment(struct blkcipher_desc *desc,
47 struct blkcipher_walk *walk,
48 struct crypto_cipher *tfm,
49 void (*xor)(u8 *, const u8 *,
50 unsigned int))
51{
52 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
53 crypto_cipher_alg(tfm)->cia_encrypt;
54 int bsize = crypto_cipher_blocksize(tfm);
55 unsigned int nbytes = walk->nbytes;
56 u8 *src = walk->src.virt.addr;
57 u8 *dst = walk->dst.virt.addr;
58 u8 *iv = walk->iv;
59
60 do {
61 xor(iv, src, bsize);
62 fn(crypto_cipher_tfm(tfm), dst, iv);
63 memcpy(iv, dst, bsize);
64 xor(iv, src, bsize);
65
66 src += bsize;
67 dst += bsize;
68 } while ((nbytes -= bsize) >= bsize);
69
70 return nbytes;
71}
72
73static int crypto_pcbc_encrypt_inplace(struct blkcipher_desc *desc,
74 struct blkcipher_walk *walk,
75 struct crypto_cipher *tfm,
76 void (*xor)(u8 *, const u8 *,
77 unsigned int))
78{
79 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
80 crypto_cipher_alg(tfm)->cia_encrypt;
81 int bsize = crypto_cipher_blocksize(tfm);
82 unsigned int nbytes = walk->nbytes;
83 u8 *src = walk->src.virt.addr;
84 u8 *iv = walk->iv;
85 u8 tmpbuf[bsize];
86
87 do {
88 memcpy(tmpbuf, src, bsize);
89 xor(iv, tmpbuf, bsize);
90 fn(crypto_cipher_tfm(tfm), src, iv);
91 memcpy(iv, src, bsize);
92 xor(iv, tmpbuf, bsize);
93
94 src += bsize;
95 } while ((nbytes -= bsize) >= bsize);
96
97 memcpy(walk->iv, iv, bsize);
98
99 return nbytes;
100}
101
102static int crypto_pcbc_encrypt(struct blkcipher_desc *desc,
103 struct scatterlist *dst, struct scatterlist *src,
104 unsigned int nbytes)
105{
106 struct blkcipher_walk walk;
107 struct crypto_blkcipher *tfm = desc->tfm;
108 struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
109 struct crypto_cipher *child = ctx->child;
110 void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
111 int err;
112
113 blkcipher_walk_init(&walk, dst, src, nbytes);
114 err = blkcipher_walk_virt(desc, &walk);
115
116 while ((nbytes = walk.nbytes)) {
117 if (walk.src.virt.addr == walk.dst.virt.addr)
118 nbytes = crypto_pcbc_encrypt_inplace(desc, &walk, child,
119 xor);
120 else
121 nbytes = crypto_pcbc_encrypt_segment(desc, &walk, child,
122 xor);
123 err = blkcipher_walk_done(desc, &walk, nbytes);
124 }
125
126 return err;
127}
128
129static int crypto_pcbc_decrypt_segment(struct blkcipher_desc *desc,
130 struct blkcipher_walk *walk,
131 struct crypto_cipher *tfm,
132 void (*xor)(u8 *, const u8 *,
133 unsigned int))
134{
135 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
136 crypto_cipher_alg(tfm)->cia_decrypt;
137 int bsize = crypto_cipher_blocksize(tfm);
138 unsigned int nbytes = walk->nbytes;
139 u8 *src = walk->src.virt.addr;
140 u8 *dst = walk->dst.virt.addr;
141 u8 *iv = walk->iv;
142
143 do {
144 fn(crypto_cipher_tfm(tfm), dst, src);
145 xor(dst, iv, bsize);
146 memcpy(iv, src, bsize);
147 xor(iv, dst, bsize);
148
149 src += bsize;
150 dst += bsize;
151 } while ((nbytes -= bsize) >= bsize);
152
153 memcpy(walk->iv, iv, bsize);
154
155 return nbytes;
156}
157
158static int crypto_pcbc_decrypt_inplace(struct blkcipher_desc *desc,
159 struct blkcipher_walk *walk,
160 struct crypto_cipher *tfm,
161 void (*xor)(u8 *, const u8 *,
162 unsigned int))
163{
164 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
165 crypto_cipher_alg(tfm)->cia_decrypt;
166 int bsize = crypto_cipher_blocksize(tfm);
167 unsigned int nbytes = walk->nbytes;
168 u8 *src = walk->src.virt.addr;
169 u8 *iv = walk->iv;
170 u8 tmpbuf[bsize];
171
172 do {
173 memcpy(tmpbuf, src, bsize);
174 fn(crypto_cipher_tfm(tfm), src, src);
175 xor(src, iv, bsize);
176 memcpy(iv, tmpbuf, bsize);
177 xor(iv, src, bsize);
178
179 src += bsize;
180 } while ((nbytes -= bsize) >= bsize);
181
182 memcpy(walk->iv, iv, bsize);
183
184 return nbytes;
185}
186
187static int crypto_pcbc_decrypt(struct blkcipher_desc *desc,
188 struct scatterlist *dst, struct scatterlist *src,
189 unsigned int nbytes)
190{
191 struct blkcipher_walk walk;
192 struct crypto_blkcipher *tfm = desc->tfm;
193 struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
194 struct crypto_cipher *child = ctx->child;
195 void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
196 int err;
197
198 blkcipher_walk_init(&walk, dst, src, nbytes);
199 err = blkcipher_walk_virt(desc, &walk);
200
201 while ((nbytes = walk.nbytes)) {
202 if (walk.src.virt.addr == walk.dst.virt.addr)
203 nbytes = crypto_pcbc_decrypt_inplace(desc, &walk, child,
204 xor);
205 else
206 nbytes = crypto_pcbc_decrypt_segment(desc, &walk, child,
207 xor);
208 err = blkcipher_walk_done(desc, &walk, nbytes);
209 }
210
211 return err;
212}
213
214static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
215{
216 do {
217 *a++ ^= *b++;
218 } while (--bs);
219}
220
221static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
222{
223 u32 *a = (u32 *)dst;
224 u32 *b = (u32 *)src;
225
226 do {
227 *a++ ^= *b++;
228 } while ((bs -= 4));
229}
230
231static void xor_64(u8 *a, const u8 *b, unsigned int bs)
232{
233 ((u32 *)a)[0] ^= ((u32 *)b)[0];
234 ((u32 *)a)[1] ^= ((u32 *)b)[1];
235}
236
237static void xor_128(u8 *a, const u8 *b, unsigned int bs)
238{
239 ((u32 *)a)[0] ^= ((u32 *)b)[0];
240 ((u32 *)a)[1] ^= ((u32 *)b)[1];
241 ((u32 *)a)[2] ^= ((u32 *)b)[2];
242 ((u32 *)a)[3] ^= ((u32 *)b)[3];
243}
244
245static int crypto_pcbc_init_tfm(struct crypto_tfm *tfm)
246{
247 struct crypto_instance *inst = (void *)tfm->__crt_alg;
248 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
249 struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
250 struct crypto_cipher *cipher;
251
252 switch (crypto_tfm_alg_blocksize(tfm)) {
253 case 8:
254 ctx->xor = xor_64;
255 break;
256
257 case 16:
258 ctx->xor = xor_128;
259 break;
260
261 default:
262 if (crypto_tfm_alg_blocksize(tfm) % 4)
263 ctx->xor = xor_byte;
264 else
265 ctx->xor = xor_quad;
266 }
267
268 cipher = crypto_spawn_cipher(spawn);
269 if (IS_ERR(cipher))
270 return PTR_ERR(cipher);
271
272 ctx->child = cipher;
273 return 0;
274}
275
276static void crypto_pcbc_exit_tfm(struct crypto_tfm *tfm)
277{
278 struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
279 crypto_free_cipher(ctx->child);
280}
281
282static struct crypto_instance *crypto_pcbc_alloc(struct rtattr **tb)
283{
284 struct crypto_instance *inst;
285 struct crypto_alg *alg;
286 int err;
287
288 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
289 if (err)
290 return ERR_PTR(err);
291
292 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
293 CRYPTO_ALG_TYPE_MASK);
294 if (IS_ERR(alg))
295 return ERR_PTR(PTR_ERR(alg));
296
297 inst = crypto_alloc_instance("pcbc", alg);
298 if (IS_ERR(inst))
299 goto out_put_alg;
300
301 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
302 inst->alg.cra_priority = alg->cra_priority;
303 inst->alg.cra_blocksize = alg->cra_blocksize;
304 inst->alg.cra_alignmask = alg->cra_alignmask;
305 inst->alg.cra_type = &crypto_blkcipher_type;
306
307 if (!(alg->cra_blocksize % 4))
308 inst->alg.cra_alignmask |= 3;
309 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
310 inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
311 inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
312
313 inst->alg.cra_ctxsize = sizeof(struct crypto_pcbc_ctx);
314
315 inst->alg.cra_init = crypto_pcbc_init_tfm;
316 inst->alg.cra_exit = crypto_pcbc_exit_tfm;
317
318 inst->alg.cra_blkcipher.setkey = crypto_pcbc_setkey;
319 inst->alg.cra_blkcipher.encrypt = crypto_pcbc_encrypt;
320 inst->alg.cra_blkcipher.decrypt = crypto_pcbc_decrypt;
321
322out_put_alg:
323 crypto_mod_put(alg);
324 return inst;
325}
326
327static void crypto_pcbc_free(struct crypto_instance *inst)
328{
329 crypto_drop_spawn(crypto_instance_ctx(inst));
330 kfree(inst);
331}
332
333static struct crypto_template crypto_pcbc_tmpl = {
334 .name = "pcbc",
335 .alloc = crypto_pcbc_alloc,
336 .free = crypto_pcbc_free,
337 .module = THIS_MODULE,
338};
339
340static int __init crypto_pcbc_module_init(void)
341{
342 return crypto_register_template(&crypto_pcbc_tmpl);
343}
344
345static void __exit crypto_pcbc_module_exit(void)
346{
347 crypto_unregister_template(&crypto_pcbc_tmpl);
348}
349
350module_init(crypto_pcbc_module_init);
351module_exit(crypto_pcbc_module_exit);
352
353MODULE_LICENSE("GPL");
354MODULE_DESCRIPTION("PCBC block cipher algorithm");
355
