xref: /openbmc/linux/drivers/crypto/padlock-aes.c (revision 171f1bc7) 
1 /*
2  * Cryptographic API.
3  *
4  * Support for VIA PadLock hardware crypto engine.
5  *
6  * Copyright (c) 2004  Michal Ludvig <michal@logix.cz>
7  *
8  */
9 
10 #include <crypto/algapi.h>
11 #include <crypto/aes.h>
12 #include <crypto/padlock.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/types.h>
16 #include <linux/errno.h>
17 #include <linux/interrupt.h>
18 #include <linux/kernel.h>
19 #include <linux/percpu.h>
20 #include <linux/smp.h>
21 #include <linux/slab.h>
22 #include <asm/byteorder.h>
23 #include <asm/processor.h>
24 #include <asm/i387.h>
25 
26 /*
27  * Number of data blocks actually fetched for each xcrypt insn.
28  * Processors with prefetch errata will fetch extra blocks.
29  */
30 static unsigned int ecb_fetch_blocks = 2;
31 #define MAX_ECB_FETCH_BLOCKS (8)
32 #define ecb_fetch_bytes (ecb_fetch_blocks * AES_BLOCK_SIZE)
33 
34 static unsigned int cbc_fetch_blocks = 1;
35 #define MAX_CBC_FETCH_BLOCKS (4)
36 #define cbc_fetch_bytes (cbc_fetch_blocks * AES_BLOCK_SIZE)
37 
38 /* Control word. */
39 struct cword {
40 	unsigned int __attribute__ ((__packed__))
41 		rounds:4,
42 		algo:3,
43 		keygen:1,
44 		interm:1,
45 		encdec:1,
46 		ksize:2;
47 } __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
48 
49 /* Whenever making any changes to the following
50  * structure *make sure* you keep E, d_data
51  * and cword aligned on 16 Bytes boundaries and
52  * the Hardware can access 16 * 16 bytes of E and d_data
53  * (only the first 15 * 16 bytes matter but the HW reads
54  * more).
55  */
56 struct aes_ctx {
57 	u32 E[AES_MAX_KEYLENGTH_U32]
58 		__attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
59 	u32 d_data[AES_MAX_KEYLENGTH_U32]
60 		__attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
61 	struct {
62 		struct cword encrypt;
63 		struct cword decrypt;
64 	} cword;
65 	u32 *D;
66 };
67 
68 static DEFINE_PER_CPU(struct cword *, paes_last_cword);
69 
70 /* Tells whether the ACE is capable to generate
71    the extended key for a given key_len. */
72 static inline int
73 aes_hw_extkey_available(uint8_t key_len)
74 {
75 	/* TODO: We should check the actual CPU model/stepping
76 	         as it's possible that the capability will be
77 	         added in the next CPU revisions. */
78 	if (key_len == 16)
79 		return 1;
80 	return 0;
81 }
82 
83 static inline struct aes_ctx *aes_ctx_common(void *ctx)
84 {
85 	unsigned long addr = (unsigned long)ctx;
86 	unsigned long align = PADLOCK_ALIGNMENT;
87 
88 	if (align <= crypto_tfm_ctx_alignment())
89 		align = 1;
90 	return (struct aes_ctx *)ALIGN(addr, align);
91 }
92 
93 static inline struct aes_ctx *aes_ctx(struct crypto_tfm *tfm)
94 {
95 	return aes_ctx_common(crypto_tfm_ctx(tfm));
96 }
97 
98 static inline struct aes_ctx *blk_aes_ctx(struct crypto_blkcipher *tfm)
99 {
100 	return aes_ctx_common(crypto_blkcipher_ctx(tfm));
101 }
102 
103 static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
104 		       unsigned int key_len)
105 {
106 	struct aes_ctx *ctx = aes_ctx(tfm);
107 	const __le32 *key = (const __le32 *)in_key;
108 	u32 *flags = &tfm->crt_flags;
109 	struct crypto_aes_ctx gen_aes;
110 	int cpu;
111 
112 	if (key_len % 8) {
113 		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
114 		return -EINVAL;
115 	}
116 
117 	/*
118 	 * If the hardware is capable of generating the extended key
119 	 * itself we must supply the plain key for both encryption
120 	 * and decryption.
121 	 */
122 	ctx->D = ctx->E;
123 
124 	ctx->E[0] = le32_to_cpu(key[0]);
125 	ctx->E[1] = le32_to_cpu(key[1]);
126 	ctx->E[2] = le32_to_cpu(key[2]);
127 	ctx->E[3] = le32_to_cpu(key[3]);
128 
129 	/* Prepare control words. */
130 	memset(&ctx->cword, 0, sizeof(ctx->cword));
131 
132 	ctx->cword.decrypt.encdec = 1;
133 	ctx->cword.encrypt.rounds = 10 + (key_len - 16) / 4;
134 	ctx->cword.decrypt.rounds = ctx->cword.encrypt.rounds;
135 	ctx->cword.encrypt.ksize = (key_len - 16) / 8;
136 	ctx->cword.decrypt.ksize = ctx->cword.encrypt.ksize;
137 
138 	/* Don't generate extended keys if the hardware can do it. */
139 	if (aes_hw_extkey_available(key_len))
140 		goto ok;
141 
142 	ctx->D = ctx->d_data;
143 	ctx->cword.encrypt.keygen = 1;
144 	ctx->cword.decrypt.keygen = 1;
145 
146 	if (crypto_aes_expand_key(&gen_aes, in_key, key_len)) {
147 		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
148 		return -EINVAL;
149 	}
150 
151 	memcpy(ctx->E, gen_aes.key_enc, AES_MAX_KEYLENGTH);
152 	memcpy(ctx->D, gen_aes.key_dec, AES_MAX_KEYLENGTH);
153 
154 ok:
155 	for_each_online_cpu(cpu)
156 		if (&ctx->cword.encrypt == per_cpu(paes_last_cword, cpu) ||
157 		    &ctx->cword.decrypt == per_cpu(paes_last_cword, cpu))
158 			per_cpu(paes_last_cword, cpu) = NULL;
159 
160 	return 0;
161 }
162 
163 /* ====== Encryption/decryption routines ====== */
164 
165 /* These are the real call to PadLock. */
166 static inline void padlock_reset_key(struct cword *cword)
167 {
168 	int cpu = raw_smp_processor_id();
169 
170 	if (cword != per_cpu(paes_last_cword, cpu))
171 #ifndef CONFIG_X86_64
172 		asm volatile ("pushfl; popfl");
173 #else
174 		asm volatile ("pushfq; popfq");
175 #endif
176 }
177 
178 static inline void padlock_store_cword(struct cword *cword)
179 {
180 	per_cpu(paes_last_cword, raw_smp_processor_id()) = cword;
181 }
182 
183 /*
184  * While the padlock instructions don't use FP/SSE registers, they
185  * generate a spurious DNA fault when cr0.ts is '1'. These instructions
186  * should be used only inside the irq_ts_save/restore() context
187  */
188 
189 static inline void rep_xcrypt_ecb(const u8 *input, u8 *output, void *key,
190 				  struct cword *control_word, int count)
191 {
192 	asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"	/* rep xcryptecb */
193 		      : "+S"(input), "+D"(output)
194 		      : "d"(control_word), "b"(key), "c"(count));
195 }
196 
197 static inline u8 *rep_xcrypt_cbc(const u8 *input, u8 *output, void *key,
198 				 u8 *iv, struct cword *control_word, int count)
199 {
200 	asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"	/* rep xcryptcbc */
201 		      : "+S" (input), "+D" (output), "+a" (iv)
202 		      : "d" (control_word), "b" (key), "c" (count));
203 	return iv;
204 }
205 
206 static void ecb_crypt_copy(const u8 *in, u8 *out, u32 *key,
207 			   struct cword *cword, int count)
208 {
209 	/*
210 	 * Padlock prefetches extra data so we must provide mapped input buffers.
211 	 * Assume there are at least 16 bytes of stack already in use.
212 	 */
213 	u8 buf[AES_BLOCK_SIZE * (MAX_ECB_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
214 	u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
215 
216 	memcpy(tmp, in, count * AES_BLOCK_SIZE);
217 	rep_xcrypt_ecb(tmp, out, key, cword, count);
218 }
219 
220 static u8 *cbc_crypt_copy(const u8 *in, u8 *out, u32 *key,
221 			   u8 *iv, struct cword *cword, int count)
222 {
223 	/*
224 	 * Padlock prefetches extra data so we must provide mapped input buffers.
225 	 * Assume there are at least 16 bytes of stack already in use.
226 	 */
227 	u8 buf[AES_BLOCK_SIZE * (MAX_CBC_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
228 	u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
229 
230 	memcpy(tmp, in, count * AES_BLOCK_SIZE);
231 	return rep_xcrypt_cbc(tmp, out, key, iv, cword, count);
232 }
233 
234 static inline void ecb_crypt(const u8 *in, u8 *out, u32 *key,
235 			     struct cword *cword, int count)
236 {
237 	/* Padlock in ECB mode fetches at least ecb_fetch_bytes of data.
238 	 * We could avoid some copying here but it's probably not worth it.
239 	 */
240 	if (unlikely(((unsigned long)in & ~PAGE_MASK) + ecb_fetch_bytes > PAGE_SIZE)) {
241 		ecb_crypt_copy(in, out, key, cword, count);
242 		return;
243 	}
244 
245 	rep_xcrypt_ecb(in, out, key, cword, count);
246 }
247 
248 static inline u8 *cbc_crypt(const u8 *in, u8 *out, u32 *key,
249 			    u8 *iv, struct cword *cword, int count)
250 {
251 	/* Padlock in CBC mode fetches at least cbc_fetch_bytes of data. */
252 	if (unlikely(((unsigned long)in & ~PAGE_MASK) + cbc_fetch_bytes > PAGE_SIZE))
253 		return cbc_crypt_copy(in, out, key, iv, cword, count);
254 
255 	return rep_xcrypt_cbc(in, out, key, iv, cword, count);
256 }
257 
258 static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
259 				      void *control_word, u32 count)
260 {
261 	u32 initial = count & (ecb_fetch_blocks - 1);
262 
263 	if (count < ecb_fetch_blocks) {
264 		ecb_crypt(input, output, key, control_word, count);
265 		return;
266 	}
267 
268 	if (initial)
269 		asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"	/* rep xcryptecb */
270 			      : "+S"(input), "+D"(output)
271 			      : "d"(control_word), "b"(key), "c"(initial));
272 
273 	asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"	/* rep xcryptecb */
274 		      : "+S"(input), "+D"(output)
275 		      : "d"(control_word), "b"(key), "c"(count - initial));
276 }
277 
278 static inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
279 				     u8 *iv, void *control_word, u32 count)
280 {
281 	u32 initial = count & (cbc_fetch_blocks - 1);
282 
283 	if (count < cbc_fetch_blocks)
284 		return cbc_crypt(input, output, key, iv, control_word, count);
285 
286 	if (initial)
287 		asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"	/* rep xcryptcbc */
288 			      : "+S" (input), "+D" (output), "+a" (iv)
289 			      : "d" (control_word), "b" (key), "c" (initial));
290 
291 	asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"	/* rep xcryptcbc */
292 		      : "+S" (input), "+D" (output), "+a" (iv)
293 		      : "d" (control_word), "b" (key), "c" (count-initial));
294 	return iv;
295 }
296 
297 static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
298 {
299 	struct aes_ctx *ctx = aes_ctx(tfm);
300 	int ts_state;
301 
302 	padlock_reset_key(&ctx->cword.encrypt);
303 	ts_state = irq_ts_save();
304 	ecb_crypt(in, out, ctx->E, &ctx->cword.encrypt, 1);
305 	irq_ts_restore(ts_state);
306 	padlock_store_cword(&ctx->cword.encrypt);
307 }
308 
309 static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
310 {
311 	struct aes_ctx *ctx = aes_ctx(tfm);
312 	int ts_state;
313 
314 	padlock_reset_key(&ctx->cword.encrypt);
315 	ts_state = irq_ts_save();
316 	ecb_crypt(in, out, ctx->D, &ctx->cword.decrypt, 1);
317 	irq_ts_restore(ts_state);
318 	padlock_store_cword(&ctx->cword.encrypt);
319 }
320 
321 static struct crypto_alg aes_alg = {
322 	.cra_name		=	"aes",
323 	.cra_driver_name	=	"aes-padlock",
324 	.cra_priority		=	PADLOCK_CRA_PRIORITY,
325 	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
326 	.cra_blocksize		=	AES_BLOCK_SIZE,
327 	.cra_ctxsize		=	sizeof(struct aes_ctx),
328 	.cra_alignmask		=	PADLOCK_ALIGNMENT - 1,
329 	.cra_module		=	THIS_MODULE,
330 	.cra_list		=	LIST_HEAD_INIT(aes_alg.cra_list),
331 	.cra_u			=	{
332 		.cipher = {
333 			.cia_min_keysize	=	AES_MIN_KEY_SIZE,
334 			.cia_max_keysize	=	AES_MAX_KEY_SIZE,
335 			.cia_setkey	   	= 	aes_set_key,
336 			.cia_encrypt	 	=	aes_encrypt,
337 			.cia_decrypt	  	=	aes_decrypt,
338 		}
339 	}
340 };
341 
342 static int ecb_aes_encrypt(struct blkcipher_desc *desc,
343 			   struct scatterlist *dst, struct scatterlist *src,
344 			   unsigned int nbytes)
345 {
346 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
347 	struct blkcipher_walk walk;
348 	int err;
349 	int ts_state;
350 
351 	padlock_reset_key(&ctx->cword.encrypt);
352 
353 	blkcipher_walk_init(&walk, dst, src, nbytes);
354 	err = blkcipher_walk_virt(desc, &walk);
355 
356 	ts_state = irq_ts_save();
357 	while ((nbytes = walk.nbytes)) {
358 		padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
359 				   ctx->E, &ctx->cword.encrypt,
360 				   nbytes / AES_BLOCK_SIZE);
361 		nbytes &= AES_BLOCK_SIZE - 1;
362 		err = blkcipher_walk_done(desc, &walk, nbytes);
363 	}
364 	irq_ts_restore(ts_state);
365 
366 	padlock_store_cword(&ctx->cword.encrypt);
367 
368 	return err;
369 }
370 
371 static int ecb_aes_decrypt(struct blkcipher_desc *desc,
372 			   struct scatterlist *dst, struct scatterlist *src,
373 			   unsigned int nbytes)
374 {
375 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
376 	struct blkcipher_walk walk;
377 	int err;
378 	int ts_state;
379 
380 	padlock_reset_key(&ctx->cword.decrypt);
381 
382 	blkcipher_walk_init(&walk, dst, src, nbytes);
383 	err = blkcipher_walk_virt(desc, &walk);
384 
385 	ts_state = irq_ts_save();
386 	while ((nbytes = walk.nbytes)) {
387 		padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
388 				   ctx->D, &ctx->cword.decrypt,
389 				   nbytes / AES_BLOCK_SIZE);
390 		nbytes &= AES_BLOCK_SIZE - 1;
391 		err = blkcipher_walk_done(desc, &walk, nbytes);
392 	}
393 	irq_ts_restore(ts_state);
394 
395 	padlock_store_cword(&ctx->cword.encrypt);
396 
397 	return err;
398 }
399 
400 static struct crypto_alg ecb_aes_alg = {
401 	.cra_name		=	"ecb(aes)",
402 	.cra_driver_name	=	"ecb-aes-padlock",
403 	.cra_priority		=	PADLOCK_COMPOSITE_PRIORITY,
404 	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
405 	.cra_blocksize		=	AES_BLOCK_SIZE,
406 	.cra_ctxsize		=	sizeof(struct aes_ctx),
407 	.cra_alignmask		=	PADLOCK_ALIGNMENT - 1,
408 	.cra_type		=	&crypto_blkcipher_type,
409 	.cra_module		=	THIS_MODULE,
410 	.cra_list		=	LIST_HEAD_INIT(ecb_aes_alg.cra_list),
411 	.cra_u			=	{
412 		.blkcipher = {
413 			.min_keysize		=	AES_MIN_KEY_SIZE,
414 			.max_keysize		=	AES_MAX_KEY_SIZE,
415 			.setkey	   		= 	aes_set_key,
416 			.encrypt		=	ecb_aes_encrypt,
417 			.decrypt		=	ecb_aes_decrypt,
418 		}
419 	}
420 };
421 
422 static int cbc_aes_encrypt(struct blkcipher_desc *desc,
423 			   struct scatterlist *dst, struct scatterlist *src,
424 			   unsigned int nbytes)
425 {
426 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
427 	struct blkcipher_walk walk;
428 	int err;
429 	int ts_state;
430 
431 	padlock_reset_key(&ctx->cword.encrypt);
432 
433 	blkcipher_walk_init(&walk, dst, src, nbytes);
434 	err = blkcipher_walk_virt(desc, &walk);
435 
436 	ts_state = irq_ts_save();
437 	while ((nbytes = walk.nbytes)) {
438 		u8 *iv = padlock_xcrypt_cbc(walk.src.virt.addr,
439 					    walk.dst.virt.addr, ctx->E,
440 					    walk.iv, &ctx->cword.encrypt,
441 					    nbytes / AES_BLOCK_SIZE);
442 		memcpy(walk.iv, iv, AES_BLOCK_SIZE);
443 		nbytes &= AES_BLOCK_SIZE - 1;
444 		err = blkcipher_walk_done(desc, &walk, nbytes);
445 	}
446 	irq_ts_restore(ts_state);
447 
448 	padlock_store_cword(&ctx->cword.decrypt);
449 
450 	return err;
451 }
452 
453 static int cbc_aes_decrypt(struct blkcipher_desc *desc,
454 			   struct scatterlist *dst, struct scatterlist *src,
455 			   unsigned int nbytes)
456 {
457 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
458 	struct blkcipher_walk walk;
459 	int err;
460 	int ts_state;
461 
462 	padlock_reset_key(&ctx->cword.encrypt);
463 
464 	blkcipher_walk_init(&walk, dst, src, nbytes);
465 	err = blkcipher_walk_virt(desc, &walk);
466 
467 	ts_state = irq_ts_save();
468 	while ((nbytes = walk.nbytes)) {
469 		padlock_xcrypt_cbc(walk.src.virt.addr, walk.dst.virt.addr,
470 				   ctx->D, walk.iv, &ctx->cword.decrypt,
471 				   nbytes / AES_BLOCK_SIZE);
472 		nbytes &= AES_BLOCK_SIZE - 1;
473 		err = blkcipher_walk_done(desc, &walk, nbytes);
474 	}
475 
476 	irq_ts_restore(ts_state);
477 
478 	padlock_store_cword(&ctx->cword.encrypt);
479 
480 	return err;
481 }
482 
483 static struct crypto_alg cbc_aes_alg = {
484 	.cra_name		=	"cbc(aes)",
485 	.cra_driver_name	=	"cbc-aes-padlock",
486 	.cra_priority		=	PADLOCK_COMPOSITE_PRIORITY,
487 	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
488 	.cra_blocksize		=	AES_BLOCK_SIZE,
489 	.cra_ctxsize		=	sizeof(struct aes_ctx),
490 	.cra_alignmask		=	PADLOCK_ALIGNMENT - 1,
491 	.cra_type		=	&crypto_blkcipher_type,
492 	.cra_module		=	THIS_MODULE,
493 	.cra_list		=	LIST_HEAD_INIT(cbc_aes_alg.cra_list),
494 	.cra_u			=	{
495 		.blkcipher = {
496 			.min_keysize		=	AES_MIN_KEY_SIZE,
497 			.max_keysize		=	AES_MAX_KEY_SIZE,
498 			.ivsize			=	AES_BLOCK_SIZE,
499 			.setkey	   		= 	aes_set_key,
500 			.encrypt		=	cbc_aes_encrypt,
501 			.decrypt		=	cbc_aes_decrypt,
502 		}
503 	}
504 };
505 
506 static int __init padlock_init(void)
507 {
508 	int ret;
509 	struct cpuinfo_x86 *c = &cpu_data(0);
510 
511 	if (!cpu_has_xcrypt)
512 		return -ENODEV;
513 
514 	if (!cpu_has_xcrypt_enabled) {
515 		printk(KERN_NOTICE PFX "VIA PadLock detected, but not enabled. Hmm, strange...\n");
516 		return -ENODEV;
517 	}
518 
519 	if ((ret = crypto_register_alg(&aes_alg)))
520 		goto aes_err;
521 
522 	if ((ret = crypto_register_alg(&ecb_aes_alg)))
523 		goto ecb_aes_err;
524 
525 	if ((ret = crypto_register_alg(&cbc_aes_alg)))
526 		goto cbc_aes_err;
527 
528 	printk(KERN_NOTICE PFX "Using VIA PadLock ACE for AES algorithm.\n");
529 
530 	if (c->x86 == 6 && c->x86_model == 15 && c->x86_mask == 2) {
531 		ecb_fetch_blocks = MAX_ECB_FETCH_BLOCKS;
532 		cbc_fetch_blocks = MAX_CBC_FETCH_BLOCKS;
533 		printk(KERN_NOTICE PFX "VIA Nano stepping 2 detected: enabling workaround.\n");
534 	}
535 
536 out:
537 	return ret;
538 
539 cbc_aes_err:
540 	crypto_unregister_alg(&ecb_aes_alg);
541 ecb_aes_err:
542 	crypto_unregister_alg(&aes_alg);
543 aes_err:
544 	printk(KERN_ERR PFX "VIA PadLock AES initialization failed.\n");
545 	goto out;
546 }
547 
548 static void __exit padlock_fini(void)
549 {
550 	crypto_unregister_alg(&cbc_aes_alg);
551 	crypto_unregister_alg(&ecb_aes_alg);
552 	crypto_unregister_alg(&aes_alg);
553 }
554 
555 module_init(padlock_init);
556 module_exit(padlock_fini);
557 
558 MODULE_DESCRIPTION("VIA PadLock AES algorithm support");
559 MODULE_LICENSE("GPL");
560 MODULE_AUTHOR("Michal Ludvig");
561 
562 MODULE_ALIAS("aes");
563