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19#include <crypto/algapi.h>
20#include <linux/err.h>
21#include <linux/init.h>
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/scatterlist.h>
25#include <linux/slab.h>
26
27#include <crypto/b128ops.h>
28#include <crypto/gf128mul.h>
29
30struct priv {
31 struct crypto_cipher *child;
32
33
34
35
36 struct gf128mul_64k *table;
37
38
39
40
41
42
43 be128 mulinc[128];
44};
45
46static inline void setbit128_bbe(void *b, int bit)
47{
48 __set_bit(bit ^ 0x78, b);
49}
50
51static int setkey(struct crypto_tfm *parent, const u8 *key,
52 unsigned int keylen)
53{
54 struct priv *ctx = crypto_tfm_ctx(parent);
55 struct crypto_cipher *child = ctx->child;
56 int err, i;
57 be128 tmp = { 0 };
58 int bsize = crypto_cipher_blocksize(child);
59
60 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
61 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
62 CRYPTO_TFM_REQ_MASK);
63 if ((err = crypto_cipher_setkey(child, key, keylen - bsize)))
64 return err;
65 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
66 CRYPTO_TFM_RES_MASK);
67
68 if (ctx->table)
69 gf128mul_free_64k(ctx->table);
70
71
72 ctx->table = gf128mul_init_64k_bbe((be128 *)(key + keylen - bsize));
73 if (!ctx->table)
74 return -ENOMEM;
75
76
77 for (i = 0; i < 128; i++) {
78 setbit128_bbe(&tmp, i);
79 ctx->mulinc[i] = tmp;
80 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
81 }
82
83 return 0;
84}
85
86struct sinfo {
87 be128 t;
88 struct crypto_tfm *tfm;
89 void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
90};
91
92static inline void inc(be128 *iv)
93{
94 be64_add_cpu(&iv->b, 1);
95 if (!iv->b)
96 be64_add_cpu(&iv->a, 1);
97}
98
99static inline void lrw_round(struct sinfo *s, void *dst, const void *src)
100{
101 be128_xor(dst, &s->t, src);
102 s->fn(s->tfm, dst, dst);
103 be128_xor(dst, dst, &s->t);
104}
105
106
107
108static inline int get_index128(be128 *block)
109{
110 int x;
111 __be32 *p = (__be32 *) block;
112
113 for (p += 3, x = 0; x < 128; p--, x += 32) {
114 u32 val = be32_to_cpup(p);
115
116 if (!~val)
117 continue;
118
119 return x + ffz(val);
120 }
121
122 return x;
123}
124
125static int crypt(struct blkcipher_desc *d,
126 struct blkcipher_walk *w, struct priv *ctx,
127 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
128{
129 int err;
130 unsigned int avail;
131 const int bs = crypto_cipher_blocksize(ctx->child);
132 struct sinfo s = {
133 .tfm = crypto_cipher_tfm(ctx->child),
134 .fn = fn
135 };
136 be128 *iv;
137 u8 *wsrc;
138 u8 *wdst;
139
140 err = blkcipher_walk_virt(d, w);
141 if (!(avail = w->nbytes))
142 return err;
143
144 wsrc = w->src.virt.addr;
145 wdst = w->dst.virt.addr;
146
147
148 iv = (be128 *)w->iv;
149 s.t = *iv;
150
151
152 gf128mul_64k_bbe(&s.t, ctx->table);
153
154 goto first;
155
156 for (;;) {
157 do {
158
159
160 be128_xor(&s.t, &s.t, &ctx->mulinc[get_index128(iv)]);
161 inc(iv);
162
163first:
164 lrw_round(&s, wdst, wsrc);
165
166 wsrc += bs;
167 wdst += bs;
168 } while ((avail -= bs) >= bs);
169
170 err = blkcipher_walk_done(d, w, avail);
171 if (!(avail = w->nbytes))
172 break;
173
174 wsrc = w->src.virt.addr;
175 wdst = w->dst.virt.addr;
176 }
177
178 return err;
179}
180
181static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
182 struct scatterlist *src, unsigned int nbytes)
183{
184 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
185 struct blkcipher_walk w;
186
187 blkcipher_walk_init(&w, dst, src, nbytes);
188 return crypt(desc, &w, ctx,
189 crypto_cipher_alg(ctx->child)->cia_encrypt);
190}
191
192static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
193 struct scatterlist *src, unsigned int nbytes)
194{
195 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
196 struct blkcipher_walk w;
197
198 blkcipher_walk_init(&w, dst, src, nbytes);
199 return crypt(desc, &w, ctx,
200 crypto_cipher_alg(ctx->child)->cia_decrypt);
201}
202
203static int init_tfm(struct crypto_tfm *tfm)
204{
205 struct crypto_cipher *cipher;
206 struct crypto_instance *inst = (void *)tfm->__crt_alg;
207 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
208 struct priv *ctx = crypto_tfm_ctx(tfm);
209 u32 *flags = &tfm->crt_flags;
210
211 cipher = crypto_spawn_cipher(spawn);
212 if (IS_ERR(cipher))
213 return PTR_ERR(cipher);
214
215 if (crypto_cipher_blocksize(cipher) != 16) {
216 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
217 return -EINVAL;
218 }
219
220 ctx->child = cipher;
221 return 0;
222}
223
224static void exit_tfm(struct crypto_tfm *tfm)
225{
226 struct priv *ctx = crypto_tfm_ctx(tfm);
227 if (ctx->table)
228 gf128mul_free_64k(ctx->table);
229 crypto_free_cipher(ctx->child);
230}
231
232static struct crypto_instance *alloc(struct rtattr **tb)
233{
234 struct crypto_instance *inst;
235 struct crypto_alg *alg;
236 int err;
237
238 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
239 if (err)
240 return ERR_PTR(err);
241
242 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
243 CRYPTO_ALG_TYPE_MASK);
244 if (IS_ERR(alg))
245 return ERR_CAST(alg);
246
247 inst = crypto_alloc_instance("lrw", alg);
248 if (IS_ERR(inst))
249 goto out_put_alg;
250
251 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
252 inst->alg.cra_priority = alg->cra_priority;
253 inst->alg.cra_blocksize = alg->cra_blocksize;
254
255 if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
256 else inst->alg.cra_alignmask = alg->cra_alignmask;
257 inst->alg.cra_type = &crypto_blkcipher_type;
258
259 if (!(alg->cra_blocksize % 4))
260 inst->alg.cra_alignmask |= 3;
261 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
262 inst->alg.cra_blkcipher.min_keysize =
263 alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
264 inst->alg.cra_blkcipher.max_keysize =
265 alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
266
267 inst->alg.cra_ctxsize = sizeof(struct priv);
268
269 inst->alg.cra_init = init_tfm;
270 inst->alg.cra_exit = exit_tfm;
271
272 inst->alg.cra_blkcipher.setkey = setkey;
273 inst->alg.cra_blkcipher.encrypt = encrypt;
274 inst->alg.cra_blkcipher.decrypt = decrypt;
275
276out_put_alg:
277 crypto_mod_put(alg);
278 return inst;
279}
280
281static void free(struct crypto_instance *inst)
282{
283 crypto_drop_spawn(crypto_instance_ctx(inst));
284 kfree(inst);
285}
286
287static struct crypto_template crypto_tmpl = {
288 .name = "lrw",
289 .alloc = alloc,
290 .free = free,
291 .module = THIS_MODULE,
292};
293
294static int __init crypto_module_init(void)
295{
296 return crypto_register_template(&crypto_tmpl);
297}
298
299static void __exit crypto_module_exit(void)
300{
301 crypto_unregister_template(&crypto_tmpl);
302}
303
304module_init(crypto_module_init);
305module_exit(crypto_module_exit);
306
307MODULE_LICENSE("GPL");
308MODULE_DESCRIPTION("LRW block cipher mode");
309