xref: /openbmc/linux/drivers/crypto/padlock-aes.c (revision e2c75e76) 
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/cpu_device_id.h>
23 #include <asm/byteorder.h>
24 #include <asm/processor.h>
25 #include <asm/fpu/api.h>
26 
27 /*
28  * Number of data blocks actually fetched for each xcrypt insn.
29  * Processors with prefetch errata will fetch extra blocks.
30  */
31 static unsigned int ecb_fetch_blocks = 2;
32 #define MAX_ECB_FETCH_BLOCKS (8)
33 #define ecb_fetch_bytes (ecb_fetch_blocks * AES_BLOCK_SIZE)
34 
35 static unsigned int cbc_fetch_blocks = 1;
36 #define MAX_CBC_FETCH_BLOCKS (4)
37 #define cbc_fetch_bytes (cbc_fetch_blocks * AES_BLOCK_SIZE)
38 
39 /* Control word. */
40 struct cword {
41 	unsigned int __attribute__ ((__packed__))
42 		rounds:4,
43 		algo:3,
44 		keygen:1,
45 		interm:1,
46 		encdec:1,
47 		ksize:2;
48 } __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
49 
50 /* Whenever making any changes to the following
51  * structure *make sure* you keep E, d_data
52  * and cword aligned on 16 Bytes boundaries and
53  * the Hardware can access 16 * 16 bytes of E and d_data
54  * (only the first 15 * 16 bytes matter but the HW reads
55  * more).
56  */
57 struct aes_ctx {
58 	u32 E[AES_MAX_KEYLENGTH_U32]
59 		__attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
60 	u32 d_data[AES_MAX_KEYLENGTH_U32]
61 		__attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
62 	struct {
63 		struct cword encrypt;
64 		struct cword decrypt;
65 	} cword;
66 	u32 *D;
67 };
68 
69 static DEFINE_PER_CPU(struct cword *, paes_last_cword);
70 
71 /* Tells whether the ACE is capable to generate
72    the extended key for a given key_len. */
73 static inline int
74 aes_hw_extkey_available(uint8_t key_len)
75 {
76 	/* TODO: We should check the actual CPU model/stepping
77 	         as it's possible that the capability will be
78 	         added in the next CPU revisions. */
79 	if (key_len == 16)
80 		return 1;
81 	return 0;
82 }
83 
84 static inline struct aes_ctx *aes_ctx_common(void *ctx)
85 {
86 	unsigned long addr = (unsigned long)ctx;
87 	unsigned long align = PADLOCK_ALIGNMENT;
88 
89 	if (align <= crypto_tfm_ctx_alignment())
90 		align = 1;
91 	return (struct aes_ctx *)ALIGN(addr, align);
92 }
93 
94 static inline struct aes_ctx *aes_ctx(struct crypto_tfm *tfm)
95 {
96 	return aes_ctx_common(crypto_tfm_ctx(tfm));
97 }
98 
99 static inline struct aes_ctx *blk_aes_ctx(struct crypto_blkcipher *tfm)
100 {
101 	return aes_ctx_common(crypto_blkcipher_ctx(tfm));
102 }
103 
104 static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
105 		       unsigned int key_len)
106 {
107 	struct aes_ctx *ctx = aes_ctx(tfm);
108 	const __le32 *key = (const __le32 *)in_key;
109 	u32 *flags = &tfm->crt_flags;
110 	struct crypto_aes_ctx gen_aes;
111 	int cpu;
112 
113 	if (key_len % 8) {
114 		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
115 		return -EINVAL;
116 	}
117 
118 	/*
119 	 * If the hardware is capable of generating the extended key
120 	 * itself we must supply the plain key for both encryption
121 	 * and decryption.
122 	 */
123 	ctx->D = ctx->E;
124 
125 	ctx->E[0] = le32_to_cpu(key[0]);
126 	ctx->E[1] = le32_to_cpu(key[1]);
127 	ctx->E[2] = le32_to_cpu(key[2]);
128 	ctx->E[3] = le32_to_cpu(key[3]);
129 
130 	/* Prepare control words. */
131 	memset(&ctx->cword, 0, sizeof(ctx->cword));
132 
133 	ctx->cword.decrypt.encdec = 1;
134 	ctx->cword.encrypt.rounds = 10 + (key_len - 16) / 4;
135 	ctx->cword.decrypt.rounds = ctx->cword.encrypt.rounds;
136 	ctx->cword.encrypt.ksize = (key_len - 16) / 8;
137 	ctx->cword.decrypt.ksize = ctx->cword.encrypt.ksize;
138 
139 	/* Don't generate extended keys if the hardware can do it. */
140 	if (aes_hw_extkey_available(key_len))
141 		goto ok;
142 
143 	ctx->D = ctx->d_data;
144 	ctx->cword.encrypt.keygen = 1;
145 	ctx->cword.decrypt.keygen = 1;
146 
147 	if (crypto_aes_expand_key(&gen_aes, in_key, key_len)) {
148 		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
149 		return -EINVAL;
150 	}
151 
152 	memcpy(ctx->E, gen_aes.key_enc, AES_MAX_KEYLENGTH);
153 	memcpy(ctx->D, gen_aes.key_dec, AES_MAX_KEYLENGTH);
154 
155 ok:
156 	for_each_online_cpu(cpu)
157 		if (&ctx->cword.encrypt == per_cpu(paes_last_cword, cpu) ||
158 		    &ctx->cword.decrypt == per_cpu(paes_last_cword, cpu))
159 			per_cpu(paes_last_cword, cpu) = NULL;
160 
161 	return 0;
162 }
163 
164 /* ====== Encryption/decryption routines ====== */
165 
166 /* These are the real call to PadLock. */
167 static inline void padlock_reset_key(struct cword *cword)
168 {
169 	int cpu = raw_smp_processor_id();
170 
171 	if (cword != per_cpu(paes_last_cword, cpu))
172 #ifndef CONFIG_X86_64
173 		asm volatile ("pushfl; popfl");
174 #else
175 		asm volatile ("pushfq; popfq");
176 #endif
177 }
178 
179 static inline void padlock_store_cword(struct cword *cword)
180 {
181 	per_cpu(paes_last_cword, raw_smp_processor_id()) = cword;
182 }
183 
184 /*
185  * While the padlock instructions don't use FP/SSE registers, they
186  * generate a spurious DNA fault when CR0.TS is '1'.  Fortunately,
187  * the kernel doesn't use CR0.TS.
188  */
189 
190 static inline void rep_xcrypt_ecb(const u8 *input, u8 *output, void *key,
191 				  struct cword *control_word, int count)
192 {
193 	asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"	/* rep xcryptecb */
194 		      : "+S"(input), "+D"(output)
195 		      : "d"(control_word), "b"(key), "c"(count));
196 }
197 
198 static inline u8 *rep_xcrypt_cbc(const u8 *input, u8 *output, void *key,
199 				 u8 *iv, struct cword *control_word, int count)
200 {
201 	asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"	/* rep xcryptcbc */
202 		      : "+S" (input), "+D" (output), "+a" (iv)
203 		      : "d" (control_word), "b" (key), "c" (count));
204 	return iv;
205 }
206 
207 static void ecb_crypt_copy(const u8 *in, u8 *out, u32 *key,
208 			   struct cword *cword, int count)
209 {
210 	/*
211 	 * Padlock prefetches extra data so we must provide mapped input buffers.
212 	 * Assume there are at least 16 bytes of stack already in use.
213 	 */
214 	u8 buf[AES_BLOCK_SIZE * (MAX_ECB_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
215 	u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
216 
217 	memcpy(tmp, in, count * AES_BLOCK_SIZE);
218 	rep_xcrypt_ecb(tmp, out, key, cword, count);
219 }
220 
221 static u8 *cbc_crypt_copy(const u8 *in, u8 *out, u32 *key,
222 			   u8 *iv, struct cword *cword, int count)
223 {
224 	/*
225 	 * Padlock prefetches extra data so we must provide mapped input buffers.
226 	 * Assume there are at least 16 bytes of stack already in use.
227 	 */
228 	u8 buf[AES_BLOCK_SIZE * (MAX_CBC_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
229 	u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
230 
231 	memcpy(tmp, in, count * AES_BLOCK_SIZE);
232 	return rep_xcrypt_cbc(tmp, out, key, iv, cword, count);
233 }
234 
235 static inline void ecb_crypt(const u8 *in, u8 *out, u32 *key,
236 			     struct cword *cword, int count)
237 {
238 	/* Padlock in ECB mode fetches at least ecb_fetch_bytes of data.
239 	 * We could avoid some copying here but it's probably not worth it.
240 	 */
241 	if (unlikely(offset_in_page(in) + ecb_fetch_bytes > PAGE_SIZE)) {
242 		ecb_crypt_copy(in, out, key, cword, count);
243 		return;
244 	}
245 
246 	rep_xcrypt_ecb(in, out, key, cword, count);
247 }
248 
249 static inline u8 *cbc_crypt(const u8 *in, u8 *out, u32 *key,
250 			    u8 *iv, struct cword *cword, int count)
251 {
252 	/* Padlock in CBC mode fetches at least cbc_fetch_bytes of data. */
253 	if (unlikely(offset_in_page(in) + cbc_fetch_bytes > PAGE_SIZE))
254 		return cbc_crypt_copy(in, out, key, iv, cword, count);
255 
256 	return rep_xcrypt_cbc(in, out, key, iv, cword, count);
257 }
258 
259 static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
260 				      void *control_word, u32 count)
261 {
262 	u32 initial = count & (ecb_fetch_blocks - 1);
263 
264 	if (count < ecb_fetch_blocks) {
265 		ecb_crypt(input, output, key, control_word, count);
266 		return;
267 	}
268 
269 	if (initial)
270 		asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"	/* rep xcryptecb */
271 			      : "+S"(input), "+D"(output)
272 			      : "d"(control_word), "b"(key), "c"(initial));
273 
274 	asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"	/* rep xcryptecb */
275 		      : "+S"(input), "+D"(output)
276 		      : "d"(control_word), "b"(key), "c"(count - initial));
277 }
278 
279 static inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
280 				     u8 *iv, void *control_word, u32 count)
281 {
282 	u32 initial = count & (cbc_fetch_blocks - 1);
283 
284 	if (count < cbc_fetch_blocks)
285 		return cbc_crypt(input, output, key, iv, control_word, count);
286 
287 	if (initial)
288 		asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"	/* rep xcryptcbc */
289 			      : "+S" (input), "+D" (output), "+a" (iv)
290 			      : "d" (control_word), "b" (key), "c" (initial));
291 
292 	asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"	/* rep xcryptcbc */
293 		      : "+S" (input), "+D" (output), "+a" (iv)
294 		      : "d" (control_word), "b" (key), "c" (count-initial));
295 	return iv;
296 }
297 
298 static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
299 {
300 	struct aes_ctx *ctx = aes_ctx(tfm);
301 
302 	padlock_reset_key(&ctx->cword.encrypt);
303 	ecb_crypt(in, out, ctx->E, &ctx->cword.encrypt, 1);
304 	padlock_store_cword(&ctx->cword.encrypt);
305 }
306 
307 static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
308 {
309 	struct aes_ctx *ctx = aes_ctx(tfm);
310 
311 	padlock_reset_key(&ctx->cword.encrypt);
312 	ecb_crypt(in, out, ctx->D, &ctx->cword.decrypt, 1);
313 	padlock_store_cword(&ctx->cword.encrypt);
314 }
315 
316 static struct crypto_alg aes_alg = {
317 	.cra_name		=	"aes",
318 	.cra_driver_name	=	"aes-padlock",
319 	.cra_priority		=	PADLOCK_CRA_PRIORITY,
320 	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
321 	.cra_blocksize		=	AES_BLOCK_SIZE,
322 	.cra_ctxsize		=	sizeof(struct aes_ctx),
323 	.cra_alignmask		=	PADLOCK_ALIGNMENT - 1,
324 	.cra_module		=	THIS_MODULE,
325 	.cra_u			=	{
326 		.cipher = {
327 			.cia_min_keysize	=	AES_MIN_KEY_SIZE,
328 			.cia_max_keysize	=	AES_MAX_KEY_SIZE,
329 			.cia_setkey	   	= 	aes_set_key,
330 			.cia_encrypt	 	=	aes_encrypt,
331 			.cia_decrypt	  	=	aes_decrypt,
332 		}
333 	}
334 };
335 
336 static int ecb_aes_encrypt(struct blkcipher_desc *desc,
337 			   struct scatterlist *dst, struct scatterlist *src,
338 			   unsigned int nbytes)
339 {
340 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
341 	struct blkcipher_walk walk;
342 	int err;
343 
344 	padlock_reset_key(&ctx->cword.encrypt);
345 
346 	blkcipher_walk_init(&walk, dst, src, nbytes);
347 	err = blkcipher_walk_virt(desc, &walk);
348 
349 	while ((nbytes = walk.nbytes)) {
350 		padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
351 				   ctx->E, &ctx->cword.encrypt,
352 				   nbytes / AES_BLOCK_SIZE);
353 		nbytes &= AES_BLOCK_SIZE - 1;
354 		err = blkcipher_walk_done(desc, &walk, nbytes);
355 	}
356 
357 	padlock_store_cword(&ctx->cword.encrypt);
358 
359 	return err;
360 }
361 
362 static int ecb_aes_decrypt(struct blkcipher_desc *desc,
363 			   struct scatterlist *dst, struct scatterlist *src,
364 			   unsigned int nbytes)
365 {
366 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
367 	struct blkcipher_walk walk;
368 	int err;
369 
370 	padlock_reset_key(&ctx->cword.decrypt);
371 
372 	blkcipher_walk_init(&walk, dst, src, nbytes);
373 	err = blkcipher_walk_virt(desc, &walk);
374 
375 	while ((nbytes = walk.nbytes)) {
376 		padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
377 				   ctx->D, &ctx->cword.decrypt,
378 				   nbytes / AES_BLOCK_SIZE);
379 		nbytes &= AES_BLOCK_SIZE - 1;
380 		err = blkcipher_walk_done(desc, &walk, nbytes);
381 	}
382 
383 	padlock_store_cword(&ctx->cword.encrypt);
384 
385 	return err;
386 }
387 
388 static struct crypto_alg ecb_aes_alg = {
389 	.cra_name		=	"ecb(aes)",
390 	.cra_driver_name	=	"ecb-aes-padlock",
391 	.cra_priority		=	PADLOCK_COMPOSITE_PRIORITY,
392 	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
393 	.cra_blocksize		=	AES_BLOCK_SIZE,
394 	.cra_ctxsize		=	sizeof(struct aes_ctx),
395 	.cra_alignmask		=	PADLOCK_ALIGNMENT - 1,
396 	.cra_type		=	&crypto_blkcipher_type,
397 	.cra_module		=	THIS_MODULE,
398 	.cra_u			=	{
399 		.blkcipher = {
400 			.min_keysize		=	AES_MIN_KEY_SIZE,
401 			.max_keysize		=	AES_MAX_KEY_SIZE,
402 			.setkey	   		= 	aes_set_key,
403 			.encrypt		=	ecb_aes_encrypt,
404 			.decrypt		=	ecb_aes_decrypt,
405 		}
406 	}
407 };
408 
409 static int cbc_aes_encrypt(struct blkcipher_desc *desc,
410 			   struct scatterlist *dst, struct scatterlist *src,
411 			   unsigned int nbytes)
412 {
413 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
414 	struct blkcipher_walk walk;
415 	int err;
416 
417 	padlock_reset_key(&ctx->cword.encrypt);
418 
419 	blkcipher_walk_init(&walk, dst, src, nbytes);
420 	err = blkcipher_walk_virt(desc, &walk);
421 
422 	while ((nbytes = walk.nbytes)) {
423 		u8 *iv = padlock_xcrypt_cbc(walk.src.virt.addr,
424 					    walk.dst.virt.addr, ctx->E,
425 					    walk.iv, &ctx->cword.encrypt,
426 					    nbytes / AES_BLOCK_SIZE);
427 		memcpy(walk.iv, iv, AES_BLOCK_SIZE);
428 		nbytes &= AES_BLOCK_SIZE - 1;
429 		err = blkcipher_walk_done(desc, &walk, nbytes);
430 	}
431 
432 	padlock_store_cword(&ctx->cword.decrypt);
433 
434 	return err;
435 }
436 
437 static int cbc_aes_decrypt(struct blkcipher_desc *desc,
438 			   struct scatterlist *dst, struct scatterlist *src,
439 			   unsigned int nbytes)
440 {
441 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
442 	struct blkcipher_walk walk;
443 	int err;
444 
445 	padlock_reset_key(&ctx->cword.encrypt);
446 
447 	blkcipher_walk_init(&walk, dst, src, nbytes);
448 	err = blkcipher_walk_virt(desc, &walk);
449 
450 	while ((nbytes = walk.nbytes)) {
451 		padlock_xcrypt_cbc(walk.src.virt.addr, walk.dst.virt.addr,
452 				   ctx->D, walk.iv, &ctx->cword.decrypt,
453 				   nbytes / AES_BLOCK_SIZE);
454 		nbytes &= AES_BLOCK_SIZE - 1;
455 		err = blkcipher_walk_done(desc, &walk, nbytes);
456 	}
457 
458 	padlock_store_cword(&ctx->cword.encrypt);
459 
460 	return err;
461 }
462 
463 static struct crypto_alg cbc_aes_alg = {
464 	.cra_name		=	"cbc(aes)",
465 	.cra_driver_name	=	"cbc-aes-padlock",
466 	.cra_priority		=	PADLOCK_COMPOSITE_PRIORITY,
467 	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
468 	.cra_blocksize		=	AES_BLOCK_SIZE,
469 	.cra_ctxsize		=	sizeof(struct aes_ctx),
470 	.cra_alignmask		=	PADLOCK_ALIGNMENT - 1,
471 	.cra_type		=	&crypto_blkcipher_type,
472 	.cra_module		=	THIS_MODULE,
473 	.cra_u			=	{
474 		.blkcipher = {
475 			.min_keysize		=	AES_MIN_KEY_SIZE,
476 			.max_keysize		=	AES_MAX_KEY_SIZE,
477 			.ivsize			=	AES_BLOCK_SIZE,
478 			.setkey	   		= 	aes_set_key,
479 			.encrypt		=	cbc_aes_encrypt,
480 			.decrypt		=	cbc_aes_decrypt,
481 		}
482 	}
483 };
484 
485 static const struct x86_cpu_id padlock_cpu_id[] = {
486 	X86_FEATURE_MATCH(X86_FEATURE_XCRYPT),
487 	{}
488 };
489 MODULE_DEVICE_TABLE(x86cpu, padlock_cpu_id);
490 
491 static int __init padlock_init(void)
492 {
493 	int ret;
494 	struct cpuinfo_x86 *c = &cpu_data(0);
495 
496 	if (!x86_match_cpu(padlock_cpu_id))
497 		return -ENODEV;
498 
499 	if (!boot_cpu_has(X86_FEATURE_XCRYPT_EN)) {
500 		printk(KERN_NOTICE PFX "VIA PadLock detected, but not enabled. Hmm, strange...\n");
501 		return -ENODEV;
502 	}
503 
504 	if ((ret = crypto_register_alg(&aes_alg)))
505 		goto aes_err;
506 
507 	if ((ret = crypto_register_alg(&ecb_aes_alg)))
508 		goto ecb_aes_err;
509 
510 	if ((ret = crypto_register_alg(&cbc_aes_alg)))
511 		goto cbc_aes_err;
512 
513 	printk(KERN_NOTICE PFX "Using VIA PadLock ACE for AES algorithm.\n");
514 
515 	if (c->x86 == 6 && c->x86_model == 15 && c->x86_stepping == 2) {
516 		ecb_fetch_blocks = MAX_ECB_FETCH_BLOCKS;
517 		cbc_fetch_blocks = MAX_CBC_FETCH_BLOCKS;
518 		printk(KERN_NOTICE PFX "VIA Nano stepping 2 detected: enabling workaround.\n");
519 	}
520 
521 out:
522 	return ret;
523 
524 cbc_aes_err:
525 	crypto_unregister_alg(&ecb_aes_alg);
526 ecb_aes_err:
527 	crypto_unregister_alg(&aes_alg);
528 aes_err:
529 	printk(KERN_ERR PFX "VIA PadLock AES initialization failed.\n");
530 	goto out;
531 }
532 
533 static void __exit padlock_fini(void)
534 {
535 	crypto_unregister_alg(&cbc_aes_alg);
536 	crypto_unregister_alg(&ecb_aes_alg);
537 	crypto_unregister_alg(&aes_alg);
538 }
539 
540 module_init(padlock_init);
541 module_exit(padlock_fini);
542 
543 MODULE_DESCRIPTION("VIA PadLock AES algorithm support");
544 MODULE_LICENSE("GPL");
545 MODULE_AUTHOR("Michal Ludvig");
546 
547 MODULE_ALIAS_CRYPTO("aes");
548