xref: /openbmc/linux/crypto/cipher.c (revision 87c2ce3b)
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 	unsigned long alignmask = crypto_tfm_alg_alignmask(desc->tfm);
216 
217 	u8 stack[src == dst ? bsize + alignmask : 0];
218 	u8 *buf = (u8 *)ALIGN((unsigned long)stack, alignmask + 1);
219 	u8 **dst_p = src == dst ? &buf : &dst;
220 
221 	void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
222 	u8 *iv = desc->info;
223 	unsigned int done = 0;
224 
225 	nbytes -= bsize;
226 
227 	do {
228 		u8 *tmp_dst = *dst_p;
229 
230 		fn(crypto_tfm_ctx(tfm), tmp_dst, src);
231 		xor(tmp_dst, iv);
232 		memcpy(iv, src, bsize);
233 		if (tmp_dst != dst)
234 			memcpy(dst, tmp_dst, bsize);
235 
236 		src += bsize;
237 		dst += bsize;
238 	} while ((done += bsize) <= nbytes);
239 
240 	return done;
241 }
242 
243 static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
244 				const u8 *src, unsigned int nbytes)
245 {
246 	struct crypto_tfm *tfm = desc->tfm;
247 	int bsize = crypto_tfm_alg_blocksize(tfm);
248 	void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
249 	unsigned int done = 0;
250 
251 	nbytes -= bsize;
252 
253 	do {
254 		fn(crypto_tfm_ctx(tfm), dst, src);
255 
256 		src += bsize;
257 		dst += bsize;
258 	} while ((done += bsize) <= nbytes);
259 
260 	return done;
261 }
262 
263 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
264 {
265 	struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
266 
267 	if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
268 		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
269 		return -EINVAL;
270 	} else
271 		return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen,
272 		                       &tfm->crt_flags);
273 }
274 
275 static int ecb_encrypt(struct crypto_tfm *tfm,
276 		       struct scatterlist *dst,
277                        struct scatterlist *src, unsigned int nbytes)
278 {
279 	struct cipher_desc desc;
280 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
281 
282 	desc.tfm = tfm;
283 	desc.crfn = cipher->cia_encrypt;
284 	desc.prfn = cipher->cia_encrypt_ecb ?: ecb_process;
285 
286 	return crypt(&desc, dst, src, nbytes);
287 }
288 
289 static int ecb_decrypt(struct crypto_tfm *tfm,
290                        struct scatterlist *dst,
291                        struct scatterlist *src,
292 		       unsigned int nbytes)
293 {
294 	struct cipher_desc desc;
295 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
296 
297 	desc.tfm = tfm;
298 	desc.crfn = cipher->cia_decrypt;
299 	desc.prfn = cipher->cia_decrypt_ecb ?: ecb_process;
300 
301 	return crypt(&desc, dst, src, nbytes);
302 }
303 
304 static int cbc_encrypt(struct crypto_tfm *tfm,
305                        struct scatterlist *dst,
306                        struct scatterlist *src,
307 		       unsigned int nbytes)
308 {
309 	struct cipher_desc desc;
310 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
311 
312 	desc.tfm = tfm;
313 	desc.crfn = cipher->cia_encrypt;
314 	desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
315 	desc.info = tfm->crt_cipher.cit_iv;
316 
317 	return crypt(&desc, dst, src, nbytes);
318 }
319 
320 static int cbc_encrypt_iv(struct crypto_tfm *tfm,
321                           struct scatterlist *dst,
322                           struct scatterlist *src,
323                           unsigned int nbytes, u8 *iv)
324 {
325 	struct cipher_desc desc;
326 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
327 
328 	desc.tfm = tfm;
329 	desc.crfn = cipher->cia_encrypt;
330 	desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
331 	desc.info = iv;
332 
333 	return crypt_iv_unaligned(&desc, dst, src, nbytes);
334 }
335 
336 static int cbc_decrypt(struct crypto_tfm *tfm,
337                        struct scatterlist *dst,
338                        struct scatterlist *src,
339 		       unsigned int nbytes)
340 {
341 	struct cipher_desc desc;
342 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
343 
344 	desc.tfm = tfm;
345 	desc.crfn = cipher->cia_decrypt;
346 	desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
347 	desc.info = tfm->crt_cipher.cit_iv;
348 
349 	return crypt(&desc, dst, src, nbytes);
350 }
351 
352 static int cbc_decrypt_iv(struct crypto_tfm *tfm,
353                           struct scatterlist *dst,
354                           struct scatterlist *src,
355                           unsigned int nbytes, u8 *iv)
356 {
357 	struct cipher_desc desc;
358 	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
359 
360 	desc.tfm = tfm;
361 	desc.crfn = cipher->cia_decrypt;
362 	desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
363 	desc.info = iv;
364 
365 	return crypt_iv_unaligned(&desc, dst, src, nbytes);
366 }
367 
368 static int nocrypt(struct crypto_tfm *tfm,
369                    struct scatterlist *dst,
370                    struct scatterlist *src,
371 		   unsigned int nbytes)
372 {
373 	return -ENOSYS;
374 }
375 
376 static int nocrypt_iv(struct crypto_tfm *tfm,
377                       struct scatterlist *dst,
378                       struct scatterlist *src,
379                       unsigned int nbytes, u8 *iv)
380 {
381 	return -ENOSYS;
382 }
383 
384 int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
385 {
386 	u32 mode = flags & CRYPTO_TFM_MODE_MASK;
387 	tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
388 	return 0;
389 }
390 
391 int crypto_init_cipher_ops(struct crypto_tfm *tfm)
392 {
393 	int ret = 0;
394 	struct cipher_tfm *ops = &tfm->crt_cipher;
395 
396 	ops->cit_setkey = setkey;
397 
398 	switch (tfm->crt_cipher.cit_mode) {
399 	case CRYPTO_TFM_MODE_ECB:
400 		ops->cit_encrypt = ecb_encrypt;
401 		ops->cit_decrypt = ecb_decrypt;
402 		break;
403 
404 	case CRYPTO_TFM_MODE_CBC:
405 		ops->cit_encrypt = cbc_encrypt;
406 		ops->cit_decrypt = cbc_decrypt;
407 		ops->cit_encrypt_iv = cbc_encrypt_iv;
408 		ops->cit_decrypt_iv = cbc_decrypt_iv;
409 		break;
410 
411 	case CRYPTO_TFM_MODE_CFB:
412 		ops->cit_encrypt = nocrypt;
413 		ops->cit_decrypt = nocrypt;
414 		ops->cit_encrypt_iv = nocrypt_iv;
415 		ops->cit_decrypt_iv = nocrypt_iv;
416 		break;
417 
418 	case CRYPTO_TFM_MODE_CTR:
419 		ops->cit_encrypt = nocrypt;
420 		ops->cit_decrypt = nocrypt;
421 		ops->cit_encrypt_iv = nocrypt_iv;
422 		ops->cit_decrypt_iv = nocrypt_iv;
423 		break;
424 
425 	default:
426 		BUG();
427 	}
428 
429 	if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
430 		unsigned long align;
431 		unsigned long addr;
432 
433 	    	switch (crypto_tfm_alg_blocksize(tfm)) {
434 	    	case 8:
435 	    		ops->cit_xor_block = xor_64;
436 	    		break;
437 
438 	    	case 16:
439 	    		ops->cit_xor_block = xor_128;
440 	    		break;
441 
442 	    	default:
443 	    		printk(KERN_WARNING "%s: block size %u not supported\n",
444 	    		       crypto_tfm_alg_name(tfm),
445 	    		       crypto_tfm_alg_blocksize(tfm));
446 	    		ret = -EINVAL;
447 	    		goto out;
448 	    	}
449 
450 		ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
451 		align = crypto_tfm_alg_alignmask(tfm) + 1;
452 		addr = (unsigned long)crypto_tfm_ctx(tfm);
453 		addr = ALIGN(addr, align);
454 		addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
455 		ops->cit_iv = (void *)addr;
456 	}
457 
458 out:
459 	return ret;
460 }
461 
462 void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
463 {
464 }
465