1 /* 2 * Cryptographic API. 3 * 4 * Cipher operations. 5 * 6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> 7 * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au> 8 * 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms of the GNU General Public License as published by the Free 11 * Software Foundation; either version 2 of the License, or (at your option) 12 * any later version. 13 * 14 */ 15 #include <linux/compiler.h> 16 #include <linux/kernel.h> 17 #include <linux/crypto.h> 18 #include <linux/errno.h> 19 #include <linux/mm.h> 20 #include <linux/slab.h> 21 #include <linux/string.h> 22 #include <asm/scatterlist.h> 23 #include "internal.h" 24 #include "scatterwalk.h" 25 26 static inline void xor_64(u8 *a, const u8 *b) 27 { 28 ((u32 *)a)[0] ^= ((u32 *)b)[0]; 29 ((u32 *)a)[1] ^= ((u32 *)b)[1]; 30 } 31 32 static inline void xor_128(u8 *a, const u8 *b) 33 { 34 ((u32 *)a)[0] ^= ((u32 *)b)[0]; 35 ((u32 *)a)[1] ^= ((u32 *)b)[1]; 36 ((u32 *)a)[2] ^= ((u32 *)b)[2]; 37 ((u32 *)a)[3] ^= ((u32 *)b)[3]; 38 } 39 40 static unsigned int crypt_slow(const struct cipher_desc *desc, 41 struct scatter_walk *in, 42 struct scatter_walk *out, unsigned int bsize) 43 { 44 unsigned long alignmask = crypto_tfm_alg_alignmask(desc->tfm); 45 u8 buffer[bsize * 2 + alignmask]; 46 u8 *src = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1); 47 u8 *dst = src + bsize; 48 unsigned int n; 49 50 n = scatterwalk_copychunks(src, in, bsize, 0); 51 scatterwalk_advance(in, n); 52 53 desc->prfn(desc, dst, src, bsize); 54 55 n = scatterwalk_copychunks(dst, out, bsize, 1); 56 scatterwalk_advance(out, n); 57 58 return bsize; 59 } 60 61 static inline unsigned int crypt_fast(const struct cipher_desc *desc, 62 struct scatter_walk *in, 63 struct scatter_walk *out, 64 unsigned int nbytes, u8 *tmp) 65 { 66 u8 *src, *dst; 67 68 src = in->data; 69 dst = scatterwalk_samebuf(in, out) ? src : out->data; 70 71 if (tmp) { 72 memcpy(tmp, in->data, nbytes); 73 src = tmp; 74 dst = tmp; 75 } 76 77 nbytes = desc->prfn(desc, dst, src, nbytes); 78 79 if (tmp) 80 memcpy(out->data, tmp, nbytes); 81 82 scatterwalk_advance(in, nbytes); 83 scatterwalk_advance(out, nbytes); 84 85 return nbytes; 86 } 87 88 /* 89 * Generic encrypt/decrypt wrapper for ciphers, handles operations across 90 * multiple page boundaries by using temporary blocks. In user context, 91 * the kernel is given a chance to schedule us once per page. 92 */ 93 static int crypt(const struct cipher_desc *desc, 94 struct scatterlist *dst, 95 struct scatterlist *src, 96 unsigned int nbytes) 97 { 98 struct scatter_walk walk_in, walk_out; 99 struct crypto_tfm *tfm = desc->tfm; 100 const unsigned int bsize = crypto_tfm_alg_blocksize(tfm); 101 unsigned int alignmask = crypto_tfm_alg_alignmask(tfm); 102 unsigned long buffer = 0; 103 104 if (!nbytes) 105 return 0; 106 107 if (nbytes % bsize) { 108 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN; 109 return -EINVAL; 110 } 111 112 scatterwalk_start(&walk_in, src); 113 scatterwalk_start(&walk_out, dst); 114 115 for(;;) { 116 unsigned int n = nbytes; 117 u8 *tmp = NULL; 118 119 if (!scatterwalk_aligned(&walk_in, alignmask) || 120 !scatterwalk_aligned(&walk_out, alignmask)) { 121 if (!buffer) { 122 buffer = __get_free_page(GFP_ATOMIC); 123 if (!buffer) 124 n = 0; 125 } 126 tmp = (u8 *)buffer; 127 } 128 129 scatterwalk_map(&walk_in, 0); 130 scatterwalk_map(&walk_out, 1); 131 132 n = scatterwalk_clamp(&walk_in, n); 133 n = scatterwalk_clamp(&walk_out, n); 134 135 if (likely(n >= bsize)) 136 n = crypt_fast(desc, &walk_in, &walk_out, n, tmp); 137 else 138 n = crypt_slow(desc, &walk_in, &walk_out, bsize); 139 140 nbytes -= n; 141 142 scatterwalk_done(&walk_in, 0, nbytes); 143 scatterwalk_done(&walk_out, 1, nbytes); 144 145 if (!nbytes) 146 break; 147 148 crypto_yield(tfm); 149 } 150 151 if (buffer) 152 free_page(buffer); 153 154 return 0; 155 } 156 157 static int crypt_iv_unaligned(struct cipher_desc *desc, 158 struct scatterlist *dst, 159 struct scatterlist *src, 160 unsigned int nbytes) 161 { 162 struct crypto_tfm *tfm = desc->tfm; 163 unsigned long alignmask = crypto_tfm_alg_alignmask(tfm); 164 u8 *iv = desc->info; 165 166 if (unlikely(((unsigned long)iv & alignmask))) { 167 unsigned int ivsize = tfm->crt_cipher.cit_ivsize; 168 u8 buffer[ivsize + alignmask]; 169 u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1); 170 int err; 171 172 desc->info = memcpy(tmp, iv, ivsize); 173 err = crypt(desc, dst, src, nbytes); 174 memcpy(iv, tmp, ivsize); 175 176 return err; 177 } 178 179 return crypt(desc, dst, src, nbytes); 180 } 181 182 static unsigned int cbc_process_encrypt(const struct cipher_desc *desc, 183 u8 *dst, const u8 *src, 184 unsigned int nbytes) 185 { 186 struct crypto_tfm *tfm = desc->tfm; 187 void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block; 188 int bsize = crypto_tfm_alg_blocksize(tfm); 189 190 void (*fn)(void *, u8 *, const u8 *) = desc->crfn; 191 u8 *iv = desc->info; 192 unsigned int done = 0; 193 194 do { 195 xor(iv, src); 196 fn(crypto_tfm_ctx(tfm), dst, iv); 197 memcpy(iv, dst, bsize); 198 199 src += bsize; 200 dst += bsize; 201 } while ((done += bsize) < nbytes); 202 203 return done; 204 } 205 206 static unsigned int cbc_process_decrypt(const struct cipher_desc *desc, 207 u8 *dst, const u8 *src, 208 unsigned int nbytes) 209 { 210 struct crypto_tfm *tfm = desc->tfm; 211 void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block; 212 int bsize = crypto_tfm_alg_blocksize(tfm); 213 214 u8 stack[src == dst ? bsize : 0]; 215 u8 *buf = stack; 216 u8 **dst_p = src == dst ? &buf : &dst; 217 218 void (*fn)(void *, u8 *, const u8 *) = desc->crfn; 219 u8 *iv = desc->info; 220 unsigned int done = 0; 221 222 do { 223 u8 *tmp_dst = *dst_p; 224 225 fn(crypto_tfm_ctx(tfm), tmp_dst, src); 226 xor(tmp_dst, iv); 227 memcpy(iv, src, bsize); 228 if (tmp_dst != dst) 229 memcpy(dst, tmp_dst, bsize); 230 231 src += bsize; 232 dst += bsize; 233 } while ((done += bsize) < nbytes); 234 235 return done; 236 } 237 238 static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst, 239 const u8 *src, unsigned int nbytes) 240 { 241 struct crypto_tfm *tfm = desc->tfm; 242 int bsize = crypto_tfm_alg_blocksize(tfm); 243 void (*fn)(void *, u8 *, const u8 *) = desc->crfn; 244 unsigned int done = 0; 245 246 do { 247 fn(crypto_tfm_ctx(tfm), dst, src); 248 249 src += bsize; 250 dst += bsize; 251 } while ((done += bsize) < nbytes); 252 253 return done; 254 } 255 256 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen) 257 { 258 struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher; 259 260 if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) { 261 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; 262 return -EINVAL; 263 } else 264 return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen, 265 &tfm->crt_flags); 266 } 267 268 static int ecb_encrypt(struct crypto_tfm *tfm, 269 struct scatterlist *dst, 270 struct scatterlist *src, unsigned int nbytes) 271 { 272 struct cipher_desc desc; 273 struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher; 274 275 desc.tfm = tfm; 276 desc.crfn = cipher->cia_encrypt; 277 desc.prfn = cipher->cia_encrypt_ecb ?: ecb_process; 278 279 return crypt(&desc, dst, src, nbytes); 280 } 281 282 static int ecb_decrypt(struct crypto_tfm *tfm, 283 struct scatterlist *dst, 284 struct scatterlist *src, 285 unsigned int nbytes) 286 { 287 struct cipher_desc desc; 288 struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher; 289 290 desc.tfm = tfm; 291 desc.crfn = cipher->cia_decrypt; 292 desc.prfn = cipher->cia_decrypt_ecb ?: ecb_process; 293 294 return crypt(&desc, dst, src, nbytes); 295 } 296 297 static int cbc_encrypt(struct crypto_tfm *tfm, 298 struct scatterlist *dst, 299 struct scatterlist *src, 300 unsigned int nbytes) 301 { 302 struct cipher_desc desc; 303 struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher; 304 305 desc.tfm = tfm; 306 desc.crfn = cipher->cia_encrypt; 307 desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt; 308 desc.info = tfm->crt_cipher.cit_iv; 309 310 return crypt(&desc, dst, src, nbytes); 311 } 312 313 static int cbc_encrypt_iv(struct crypto_tfm *tfm, 314 struct scatterlist *dst, 315 struct scatterlist *src, 316 unsigned int nbytes, u8 *iv) 317 { 318 struct cipher_desc desc; 319 struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher; 320 321 desc.tfm = tfm; 322 desc.crfn = cipher->cia_encrypt; 323 desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt; 324 desc.info = iv; 325 326 return crypt_iv_unaligned(&desc, dst, src, nbytes); 327 } 328 329 static int cbc_decrypt(struct crypto_tfm *tfm, 330 struct scatterlist *dst, 331 struct scatterlist *src, 332 unsigned int nbytes) 333 { 334 struct cipher_desc desc; 335 struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher; 336 337 desc.tfm = tfm; 338 desc.crfn = cipher->cia_decrypt; 339 desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt; 340 desc.info = tfm->crt_cipher.cit_iv; 341 342 return crypt(&desc, dst, src, nbytes); 343 } 344 345 static int cbc_decrypt_iv(struct crypto_tfm *tfm, 346 struct scatterlist *dst, 347 struct scatterlist *src, 348 unsigned int nbytes, u8 *iv) 349 { 350 struct cipher_desc desc; 351 struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher; 352 353 desc.tfm = tfm; 354 desc.crfn = cipher->cia_decrypt; 355 desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt; 356 desc.info = iv; 357 358 return crypt_iv_unaligned(&desc, dst, src, nbytes); 359 } 360 361 static int nocrypt(struct crypto_tfm *tfm, 362 struct scatterlist *dst, 363 struct scatterlist *src, 364 unsigned int nbytes) 365 { 366 return -ENOSYS; 367 } 368 369 static int nocrypt_iv(struct crypto_tfm *tfm, 370 struct scatterlist *dst, 371 struct scatterlist *src, 372 unsigned int nbytes, u8 *iv) 373 { 374 return -ENOSYS; 375 } 376 377 int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags) 378 { 379 u32 mode = flags & CRYPTO_TFM_MODE_MASK; 380 381 tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB; 382 if (flags & CRYPTO_TFM_REQ_WEAK_KEY) 383 tfm->crt_flags = CRYPTO_TFM_REQ_WEAK_KEY; 384 385 return 0; 386 } 387 388 int crypto_init_cipher_ops(struct crypto_tfm *tfm) 389 { 390 int ret = 0; 391 struct cipher_tfm *ops = &tfm->crt_cipher; 392 393 ops->cit_setkey = setkey; 394 395 switch (tfm->crt_cipher.cit_mode) { 396 case CRYPTO_TFM_MODE_ECB: 397 ops->cit_encrypt = ecb_encrypt; 398 ops->cit_decrypt = ecb_decrypt; 399 break; 400 401 case CRYPTO_TFM_MODE_CBC: 402 ops->cit_encrypt = cbc_encrypt; 403 ops->cit_decrypt = cbc_decrypt; 404 ops->cit_encrypt_iv = cbc_encrypt_iv; 405 ops->cit_decrypt_iv = cbc_decrypt_iv; 406 break; 407 408 case CRYPTO_TFM_MODE_CFB: 409 ops->cit_encrypt = nocrypt; 410 ops->cit_decrypt = nocrypt; 411 ops->cit_encrypt_iv = nocrypt_iv; 412 ops->cit_decrypt_iv = nocrypt_iv; 413 break; 414 415 case CRYPTO_TFM_MODE_CTR: 416 ops->cit_encrypt = nocrypt; 417 ops->cit_decrypt = nocrypt; 418 ops->cit_encrypt_iv = nocrypt_iv; 419 ops->cit_decrypt_iv = nocrypt_iv; 420 break; 421 422 default: 423 BUG(); 424 } 425 426 if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) { 427 unsigned long align; 428 unsigned long addr; 429 430 switch (crypto_tfm_alg_blocksize(tfm)) { 431 case 8: 432 ops->cit_xor_block = xor_64; 433 break; 434 435 case 16: 436 ops->cit_xor_block = xor_128; 437 break; 438 439 default: 440 printk(KERN_WARNING "%s: block size %u not supported\n", 441 crypto_tfm_alg_name(tfm), 442 crypto_tfm_alg_blocksize(tfm)); 443 ret = -EINVAL; 444 goto out; 445 } 446 447 ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm); 448 align = crypto_tfm_alg_alignmask(tfm) + 1; 449 addr = (unsigned long)crypto_tfm_ctx(tfm); 450 addr = ALIGN(addr, align); 451 addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align); 452 ops->cit_iv = (void *)addr; 453 } 454 455 out: 456 return ret; 457 } 458 459 void crypto_exit_cipher_ops(struct crypto_tfm *tfm) 460 { 461 } 462