xref: /openbmc/linux/crypto/cipher.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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 	nbytes -= bsize;
195 
196 	do {
197 		xor(iv, src);
198 		fn(crypto_tfm_ctx(tfm), dst, iv);
199 		memcpy(iv, dst, bsize);
200 
201 		src += bsize;
202 		dst += bsize;
203 	} while ((done += bsize) <= nbytes);
204 
205 	return done;
206 }
207 
208 static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
209 					u8 *dst, const u8 *src,
210 					unsigned int nbytes)
211 {
212 	struct crypto_tfm *tfm = desc->tfm;
213 	void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
214 	int bsize = crypto_tfm_alg_blocksize(tfm);
215 
216 	u8 stack[src == dst ? bsize : 0];
217 	u8 *buf = stack;
218 	u8 **dst_p = src == dst ? &buf : &dst;
219 
220 	void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
221 	u8 *iv = desc->info;
222 	unsigned int done = 0;
223 
224 	nbytes -= bsize;
225 
226 	do {
227 		u8 *tmp_dst = *dst_p;
228 
229 		fn(crypto_tfm_ctx(tfm), tmp_dst, src);
230 		xor(tmp_dst, iv);
231 		memcpy(iv, src, bsize);
232 		if (tmp_dst != dst)
233 			memcpy(dst, tmp_dst, bsize);
234 
235 		src += bsize;
236 		dst += bsize;
237 	} while ((done += bsize) <= nbytes);
238 
239 	return done;
240 }
241 
242 static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
243 				const u8 *src, unsigned int nbytes)
244 {
245 	struct crypto_tfm *tfm = desc->tfm;
246 	int bsize = crypto_tfm_alg_blocksize(tfm);
247 	void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
248 	unsigned int done = 0;
249 
250 	nbytes -= bsize;
251 
252 	do {
253 		fn(crypto_tfm_ctx(tfm), dst, src);
254 
255 		src += bsize;
256 		dst += bsize;
257 	} while ((done += bsize) <= nbytes);
258 
259 	return done;
260 }
261 
262 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
263 {
264 	struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
265 
266 	if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
267 		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
268 		return -EINVAL;
269 	} else
270 		return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen,
271 		                       &tfm->crt_flags);
272 }
273 
274 static int ecb_encrypt(struct crypto_tfm *tfm,
275 		       struct scatterlist *dst,
276                        struct scatterlist *src, unsigned int nbytes)
277 {
278 	struct cipher_desc desc;
279 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
280 
281 	desc.tfm = tfm;
282 	desc.crfn = cipher->cia_encrypt;
283 	desc.prfn = cipher->cia_encrypt_ecb ?: ecb_process;
284 
285 	return crypt(&desc, dst, src, nbytes);
286 }
287 
288 static int ecb_decrypt(struct crypto_tfm *tfm,
289                        struct scatterlist *dst,
290                        struct scatterlist *src,
291 		       unsigned int nbytes)
292 {
293 	struct cipher_desc desc;
294 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
295 
296 	desc.tfm = tfm;
297 	desc.crfn = cipher->cia_decrypt;
298 	desc.prfn = cipher->cia_decrypt_ecb ?: ecb_process;
299 
300 	return crypt(&desc, dst, src, nbytes);
301 }
302 
303 static int cbc_encrypt(struct crypto_tfm *tfm,
304                        struct scatterlist *dst,
305                        struct scatterlist *src,
306 		       unsigned int nbytes)
307 {
308 	struct cipher_desc desc;
309 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
310 
311 	desc.tfm = tfm;
312 	desc.crfn = cipher->cia_encrypt;
313 	desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
314 	desc.info = tfm->crt_cipher.cit_iv;
315 
316 	return crypt(&desc, dst, src, nbytes);
317 }
318 
319 static int cbc_encrypt_iv(struct crypto_tfm *tfm,
320                           struct scatterlist *dst,
321                           struct scatterlist *src,
322                           unsigned int nbytes, u8 *iv)
323 {
324 	struct cipher_desc desc;
325 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
326 
327 	desc.tfm = tfm;
328 	desc.crfn = cipher->cia_encrypt;
329 	desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
330 	desc.info = iv;
331 
332 	return crypt_iv_unaligned(&desc, dst, src, nbytes);
333 }
334 
335 static int cbc_decrypt(struct crypto_tfm *tfm,
336                        struct scatterlist *dst,
337                        struct scatterlist *src,
338 		       unsigned int nbytes)
339 {
340 	struct cipher_desc desc;
341 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
342 
343 	desc.tfm = tfm;
344 	desc.crfn = cipher->cia_decrypt;
345 	desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
346 	desc.info = tfm->crt_cipher.cit_iv;
347 
348 	return crypt(&desc, dst, src, nbytes);
349 }
350 
351 static int cbc_decrypt_iv(struct crypto_tfm *tfm,
352                           struct scatterlist *dst,
353                           struct scatterlist *src,
354                           unsigned int nbytes, u8 *iv)
355 {
356 	struct cipher_desc desc;
357 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
358 
359 	desc.tfm = tfm;
360 	desc.crfn = cipher->cia_decrypt;
361 	desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
362 	desc.info = iv;
363 
364 	return crypt_iv_unaligned(&desc, dst, src, nbytes);
365 }
366 
367 static int nocrypt(struct crypto_tfm *tfm,
368                    struct scatterlist *dst,
369                    struct scatterlist *src,
370 		   unsigned int nbytes)
371 {
372 	return -ENOSYS;
373 }
374 
375 static int nocrypt_iv(struct crypto_tfm *tfm,
376                       struct scatterlist *dst,
377                       struct scatterlist *src,
378                       unsigned int nbytes, u8 *iv)
379 {
380 	return -ENOSYS;
381 }
382 
383 int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
384 {
385 	u32 mode = flags & CRYPTO_TFM_MODE_MASK;
386 	tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
387 	return 0;
388 }
389 
390 int crypto_init_cipher_ops(struct crypto_tfm *tfm)
391 {
392 	int ret = 0;
393 	struct cipher_tfm *ops = &tfm->crt_cipher;
394 
395 	ops->cit_setkey = setkey;
396 
397 	switch (tfm->crt_cipher.cit_mode) {
398 	case CRYPTO_TFM_MODE_ECB:
399 		ops->cit_encrypt = ecb_encrypt;
400 		ops->cit_decrypt = ecb_decrypt;
401 		break;
402 
403 	case CRYPTO_TFM_MODE_CBC:
404 		ops->cit_encrypt = cbc_encrypt;
405 		ops->cit_decrypt = cbc_decrypt;
406 		ops->cit_encrypt_iv = cbc_encrypt_iv;
407 		ops->cit_decrypt_iv = cbc_decrypt_iv;
408 		break;
409 
410 	case CRYPTO_TFM_MODE_CFB:
411 		ops->cit_encrypt = nocrypt;
412 		ops->cit_decrypt = nocrypt;
413 		ops->cit_encrypt_iv = nocrypt_iv;
414 		ops->cit_decrypt_iv = nocrypt_iv;
415 		break;
416 
417 	case CRYPTO_TFM_MODE_CTR:
418 		ops->cit_encrypt = nocrypt;
419 		ops->cit_decrypt = nocrypt;
420 		ops->cit_encrypt_iv = nocrypt_iv;
421 		ops->cit_decrypt_iv = nocrypt_iv;
422 		break;
423 
424 	default:
425 		BUG();
426 	}
427 
428 	if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
429 		unsigned long align;
430 		unsigned long addr;
431 
432 	    	switch (crypto_tfm_alg_blocksize(tfm)) {
433 	    	case 8:
434 	    		ops->cit_xor_block = xor_64;
435 	    		break;
436 
437 	    	case 16:
438 	    		ops->cit_xor_block = xor_128;
439 	    		break;
440 
441 	    	default:
442 	    		printk(KERN_WARNING "%s: block size %u not supported\n",
443 	    		       crypto_tfm_alg_name(tfm),
444 	    		       crypto_tfm_alg_blocksize(tfm));
445 	    		ret = -EINVAL;
446 	    		goto out;
447 	    	}
448 
449 		ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
450 		align = crypto_tfm_alg_alignmask(tfm) + 1;
451 		addr = (unsigned long)crypto_tfm_ctx(tfm);
452 		addr = ALIGN(addr, align);
453 		addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
454 		ops->cit_iv = (void *)addr;
455 	}
456 
457 out:
458 	return ret;
459 }
460 
461 void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
462 {
463 }
464