1 /*
2  *  linux/net/sunrpc/gss_krb5_crypto.c
3  *
4  *  Copyright (c) 2000-2008 The Regents of the University of Michigan.
5  *  All rights reserved.
6  *
7  *  Andy Adamson   <andros@umich.edu>
8  *  Bruce Fields   <bfields@umich.edu>
9  */
10 
11 /*
12  * Copyright (C) 1998 by the FundsXpress, INC.
13  *
14  * All rights reserved.
15  *
16  * Export of this software from the United States of America may require
17  * a specific license from the United States Government.  It is the
18  * responsibility of any person or organization contemplating export to
19  * obtain such a license before exporting.
20  *
21  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
22  * distribute this software and its documentation for any purpose and
23  * without fee is hereby granted, provided that the above copyright
24  * notice appear in all copies and that both that copyright notice and
25  * this permission notice appear in supporting documentation, and that
26  * the name of FundsXpress. not be used in advertising or publicity pertaining
27  * to distribution of the software without specific, written prior
28  * permission.  FundsXpress makes no representations about the suitability of
29  * this software for any purpose.  It is provided "as is" without express
30  * or implied warranty.
31  *
32  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
33  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
34  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
35  */
36 
37 #include <crypto/hash.h>
38 #include <crypto/skcipher.h>
39 #include <linux/err.h>
40 #include <linux/types.h>
41 #include <linux/mm.h>
42 #include <linux/scatterlist.h>
43 #include <linux/highmem.h>
44 #include <linux/pagemap.h>
45 #include <linux/random.h>
46 #include <linux/sunrpc/gss_krb5.h>
47 #include <linux/sunrpc/xdr.h>
48 
49 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
50 # define RPCDBG_FACILITY        RPCDBG_AUTH
51 #endif
52 
53 u32
54 krb5_encrypt(
55 	struct crypto_skcipher *tfm,
56 	void * iv,
57 	void * in,
58 	void * out,
59 	int length)
60 {
61 	u32 ret = -EINVAL;
62 	struct scatterlist sg[1];
63 	u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
64 	SKCIPHER_REQUEST_ON_STACK(req, tfm);
65 
66 	if (length % crypto_skcipher_blocksize(tfm) != 0)
67 		goto out;
68 
69 	if (crypto_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
70 		dprintk("RPC:       gss_k5encrypt: tfm iv size too large %d\n",
71 			crypto_skcipher_ivsize(tfm));
72 		goto out;
73 	}
74 
75 	if (iv)
76 		memcpy(local_iv, iv, crypto_skcipher_ivsize(tfm));
77 
78 	memcpy(out, in, length);
79 	sg_init_one(sg, out, length);
80 
81 	skcipher_request_set_tfm(req, tfm);
82 	skcipher_request_set_callback(req, 0, NULL, NULL);
83 	skcipher_request_set_crypt(req, sg, sg, length, local_iv);
84 
85 	ret = crypto_skcipher_encrypt(req);
86 	skcipher_request_zero(req);
87 out:
88 	dprintk("RPC:       krb5_encrypt returns %d\n", ret);
89 	return ret;
90 }
91 
92 u32
93 krb5_decrypt(
94      struct crypto_skcipher *tfm,
95      void * iv,
96      void * in,
97      void * out,
98      int length)
99 {
100 	u32 ret = -EINVAL;
101 	struct scatterlist sg[1];
102 	u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
103 	SKCIPHER_REQUEST_ON_STACK(req, tfm);
104 
105 	if (length % crypto_skcipher_blocksize(tfm) != 0)
106 		goto out;
107 
108 	if (crypto_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
109 		dprintk("RPC:       gss_k5decrypt: tfm iv size too large %d\n",
110 			crypto_skcipher_ivsize(tfm));
111 		goto out;
112 	}
113 	if (iv)
114 		memcpy(local_iv,iv, crypto_skcipher_ivsize(tfm));
115 
116 	memcpy(out, in, length);
117 	sg_init_one(sg, out, length);
118 
119 	skcipher_request_set_tfm(req, tfm);
120 	skcipher_request_set_callback(req, 0, NULL, NULL);
121 	skcipher_request_set_crypt(req, sg, sg, length, local_iv);
122 
123 	ret = crypto_skcipher_decrypt(req);
124 	skcipher_request_zero(req);
125 out:
126 	dprintk("RPC:       gss_k5decrypt returns %d\n",ret);
127 	return ret;
128 }
129 
130 static int
131 checksummer(struct scatterlist *sg, void *data)
132 {
133 	struct ahash_request *req = data;
134 
135 	ahash_request_set_crypt(req, sg, NULL, sg->length);
136 
137 	return crypto_ahash_update(req);
138 }
139 
140 static int
141 arcfour_hmac_md5_usage_to_salt(unsigned int usage, u8 salt[4])
142 {
143 	unsigned int ms_usage;
144 
145 	switch (usage) {
146 	case KG_USAGE_SIGN:
147 		ms_usage = 15;
148 		break;
149 	case KG_USAGE_SEAL:
150 		ms_usage = 13;
151 		break;
152 	default:
153 		return -EINVAL;
154 	}
155 	salt[0] = (ms_usage >> 0) & 0xff;
156 	salt[1] = (ms_usage >> 8) & 0xff;
157 	salt[2] = (ms_usage >> 16) & 0xff;
158 	salt[3] = (ms_usage >> 24) & 0xff;
159 
160 	return 0;
161 }
162 
163 static u32
164 make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
165 		       struct xdr_buf *body, int body_offset, u8 *cksumkey,
166 		       unsigned int usage, struct xdr_netobj *cksumout)
167 {
168 	struct scatterlist              sg[1];
169 	int err;
170 	u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
171 	u8 rc4salt[4];
172 	struct crypto_ahash *md5;
173 	struct crypto_ahash *hmac_md5;
174 	struct ahash_request *req;
175 
176 	if (cksumkey == NULL)
177 		return GSS_S_FAILURE;
178 
179 	if (cksumout->len < kctx->gk5e->cksumlength) {
180 		dprintk("%s: checksum buffer length, %u, too small for %s\n",
181 			__func__, cksumout->len, kctx->gk5e->name);
182 		return GSS_S_FAILURE;
183 	}
184 
185 	if (arcfour_hmac_md5_usage_to_salt(usage, rc4salt)) {
186 		dprintk("%s: invalid usage value %u\n", __func__, usage);
187 		return GSS_S_FAILURE;
188 	}
189 
190 	md5 = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
191 	if (IS_ERR(md5))
192 		return GSS_S_FAILURE;
193 
194 	hmac_md5 = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0,
195 				      CRYPTO_ALG_ASYNC);
196 	if (IS_ERR(hmac_md5)) {
197 		crypto_free_ahash(md5);
198 		return GSS_S_FAILURE;
199 	}
200 
201 	req = ahash_request_alloc(md5, GFP_KERNEL);
202 	if (!req) {
203 		crypto_free_ahash(hmac_md5);
204 		crypto_free_ahash(md5);
205 		return GSS_S_FAILURE;
206 	}
207 
208 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
209 
210 	err = crypto_ahash_init(req);
211 	if (err)
212 		goto out;
213 	sg_init_one(sg, rc4salt, 4);
214 	ahash_request_set_crypt(req, sg, NULL, 4);
215 	err = crypto_ahash_update(req);
216 	if (err)
217 		goto out;
218 
219 	sg_init_one(sg, header, hdrlen);
220 	ahash_request_set_crypt(req, sg, NULL, hdrlen);
221 	err = crypto_ahash_update(req);
222 	if (err)
223 		goto out;
224 	err = xdr_process_buf(body, body_offset, body->len - body_offset,
225 			      checksummer, req);
226 	if (err)
227 		goto out;
228 	ahash_request_set_crypt(req, NULL, checksumdata, 0);
229 	err = crypto_ahash_final(req);
230 	if (err)
231 		goto out;
232 
233 	ahash_request_free(req);
234 	req = ahash_request_alloc(hmac_md5, GFP_KERNEL);
235 	if (!req) {
236 		crypto_free_ahash(hmac_md5);
237 		crypto_free_ahash(md5);
238 		return GSS_S_FAILURE;
239 	}
240 
241 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
242 
243 	err = crypto_ahash_init(req);
244 	if (err)
245 		goto out;
246 	err = crypto_ahash_setkey(hmac_md5, cksumkey, kctx->gk5e->keylength);
247 	if (err)
248 		goto out;
249 
250 	sg_init_one(sg, checksumdata, crypto_ahash_digestsize(md5));
251 	ahash_request_set_crypt(req, sg, checksumdata,
252 				crypto_ahash_digestsize(md5));
253 	err = crypto_ahash_digest(req);
254 	if (err)
255 		goto out;
256 
257 	memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
258 	cksumout->len = kctx->gk5e->cksumlength;
259 out:
260 	ahash_request_free(req);
261 	crypto_free_ahash(md5);
262 	crypto_free_ahash(hmac_md5);
263 	return err ? GSS_S_FAILURE : 0;
264 }
265 
266 /*
267  * checksum the plaintext data and hdrlen bytes of the token header
268  * The checksum is performed over the first 8 bytes of the
269  * gss token header and then over the data body
270  */
271 u32
272 make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
273 	      struct xdr_buf *body, int body_offset, u8 *cksumkey,
274 	      unsigned int usage, struct xdr_netobj *cksumout)
275 {
276 	struct crypto_ahash *tfm;
277 	struct ahash_request *req;
278 	struct scatterlist              sg[1];
279 	int err;
280 	u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
281 	unsigned int checksumlen;
282 
283 	if (kctx->gk5e->ctype == CKSUMTYPE_HMAC_MD5_ARCFOUR)
284 		return make_checksum_hmac_md5(kctx, header, hdrlen,
285 					      body, body_offset,
286 					      cksumkey, usage, cksumout);
287 
288 	if (cksumout->len < kctx->gk5e->cksumlength) {
289 		dprintk("%s: checksum buffer length, %u, too small for %s\n",
290 			__func__, cksumout->len, kctx->gk5e->name);
291 		return GSS_S_FAILURE;
292 	}
293 
294 	tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
295 	if (IS_ERR(tfm))
296 		return GSS_S_FAILURE;
297 
298 	req = ahash_request_alloc(tfm, GFP_KERNEL);
299 	if (!req) {
300 		crypto_free_ahash(tfm);
301 		return GSS_S_FAILURE;
302 	}
303 
304 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
305 
306 	checksumlen = crypto_ahash_digestsize(tfm);
307 
308 	if (cksumkey != NULL) {
309 		err = crypto_ahash_setkey(tfm, cksumkey,
310 					  kctx->gk5e->keylength);
311 		if (err)
312 			goto out;
313 	}
314 
315 	err = crypto_ahash_init(req);
316 	if (err)
317 		goto out;
318 	sg_init_one(sg, header, hdrlen);
319 	ahash_request_set_crypt(req, sg, NULL, hdrlen);
320 	err = crypto_ahash_update(req);
321 	if (err)
322 		goto out;
323 	err = xdr_process_buf(body, body_offset, body->len - body_offset,
324 			      checksummer, req);
325 	if (err)
326 		goto out;
327 	ahash_request_set_crypt(req, NULL, checksumdata, 0);
328 	err = crypto_ahash_final(req);
329 	if (err)
330 		goto out;
331 
332 	switch (kctx->gk5e->ctype) {
333 	case CKSUMTYPE_RSA_MD5:
334 		err = kctx->gk5e->encrypt(kctx->seq, NULL, checksumdata,
335 					  checksumdata, checksumlen);
336 		if (err)
337 			goto out;
338 		memcpy(cksumout->data,
339 		       checksumdata + checksumlen - kctx->gk5e->cksumlength,
340 		       kctx->gk5e->cksumlength);
341 		break;
342 	case CKSUMTYPE_HMAC_SHA1_DES3:
343 		memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
344 		break;
345 	default:
346 		BUG();
347 		break;
348 	}
349 	cksumout->len = kctx->gk5e->cksumlength;
350 out:
351 	ahash_request_free(req);
352 	crypto_free_ahash(tfm);
353 	return err ? GSS_S_FAILURE : 0;
354 }
355 
356 /*
357  * checksum the plaintext data and hdrlen bytes of the token header
358  * Per rfc4121, sec. 4.2.4, the checksum is performed over the data
359  * body then over the first 16 octets of the MIC token
360  * Inclusion of the header data in the calculation of the
361  * checksum is optional.
362  */
363 u32
364 make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen,
365 		 struct xdr_buf *body, int body_offset, u8 *cksumkey,
366 		 unsigned int usage, struct xdr_netobj *cksumout)
367 {
368 	struct crypto_ahash *tfm;
369 	struct ahash_request *req;
370 	struct scatterlist sg[1];
371 	int err;
372 	u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
373 	unsigned int checksumlen;
374 
375 	if (kctx->gk5e->keyed_cksum == 0) {
376 		dprintk("%s: expected keyed hash for %s\n",
377 			__func__, kctx->gk5e->name);
378 		return GSS_S_FAILURE;
379 	}
380 	if (cksumkey == NULL) {
381 		dprintk("%s: no key supplied for %s\n",
382 			__func__, kctx->gk5e->name);
383 		return GSS_S_FAILURE;
384 	}
385 
386 	tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
387 	if (IS_ERR(tfm))
388 		return GSS_S_FAILURE;
389 	checksumlen = crypto_ahash_digestsize(tfm);
390 
391 	req = ahash_request_alloc(tfm, GFP_KERNEL);
392 	if (!req) {
393 		crypto_free_ahash(tfm);
394 		return GSS_S_FAILURE;
395 	}
396 
397 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
398 
399 	err = crypto_ahash_setkey(tfm, cksumkey, kctx->gk5e->keylength);
400 	if (err)
401 		goto out;
402 
403 	err = crypto_ahash_init(req);
404 	if (err)
405 		goto out;
406 	err = xdr_process_buf(body, body_offset, body->len - body_offset,
407 			      checksummer, req);
408 	if (err)
409 		goto out;
410 	if (header != NULL) {
411 		sg_init_one(sg, header, hdrlen);
412 		ahash_request_set_crypt(req, sg, NULL, hdrlen);
413 		err = crypto_ahash_update(req);
414 		if (err)
415 			goto out;
416 	}
417 	ahash_request_set_crypt(req, NULL, checksumdata, 0);
418 	err = crypto_ahash_final(req);
419 	if (err)
420 		goto out;
421 
422 	cksumout->len = kctx->gk5e->cksumlength;
423 
424 	switch (kctx->gk5e->ctype) {
425 	case CKSUMTYPE_HMAC_SHA1_96_AES128:
426 	case CKSUMTYPE_HMAC_SHA1_96_AES256:
427 		/* note that this truncates the hash */
428 		memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
429 		break;
430 	default:
431 		BUG();
432 		break;
433 	}
434 out:
435 	ahash_request_free(req);
436 	crypto_free_ahash(tfm);
437 	return err ? GSS_S_FAILURE : 0;
438 }
439 
440 struct encryptor_desc {
441 	u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
442 	struct skcipher_request *req;
443 	int pos;
444 	struct xdr_buf *outbuf;
445 	struct page **pages;
446 	struct scatterlist infrags[4];
447 	struct scatterlist outfrags[4];
448 	int fragno;
449 	int fraglen;
450 };
451 
452 static int
453 encryptor(struct scatterlist *sg, void *data)
454 {
455 	struct encryptor_desc *desc = data;
456 	struct xdr_buf *outbuf = desc->outbuf;
457 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(desc->req);
458 	struct page *in_page;
459 	int thislen = desc->fraglen + sg->length;
460 	int fraglen, ret;
461 	int page_pos;
462 
463 	/* Worst case is 4 fragments: head, end of page 1, start
464 	 * of page 2, tail.  Anything more is a bug. */
465 	BUG_ON(desc->fragno > 3);
466 
467 	page_pos = desc->pos - outbuf->head[0].iov_len;
468 	if (page_pos >= 0 && page_pos < outbuf->page_len) {
469 		/* pages are not in place: */
470 		int i = (page_pos + outbuf->page_base) >> PAGE_SHIFT;
471 		in_page = desc->pages[i];
472 	} else {
473 		in_page = sg_page(sg);
474 	}
475 	sg_set_page(&desc->infrags[desc->fragno], in_page, sg->length,
476 		    sg->offset);
477 	sg_set_page(&desc->outfrags[desc->fragno], sg_page(sg), sg->length,
478 		    sg->offset);
479 	desc->fragno++;
480 	desc->fraglen += sg->length;
481 	desc->pos += sg->length;
482 
483 	fraglen = thislen & (crypto_skcipher_blocksize(tfm) - 1);
484 	thislen -= fraglen;
485 
486 	if (thislen == 0)
487 		return 0;
488 
489 	sg_mark_end(&desc->infrags[desc->fragno - 1]);
490 	sg_mark_end(&desc->outfrags[desc->fragno - 1]);
491 
492 	skcipher_request_set_crypt(desc->req, desc->infrags, desc->outfrags,
493 				   thislen, desc->iv);
494 
495 	ret = crypto_skcipher_encrypt(desc->req);
496 	if (ret)
497 		return ret;
498 
499 	sg_init_table(desc->infrags, 4);
500 	sg_init_table(desc->outfrags, 4);
501 
502 	if (fraglen) {
503 		sg_set_page(&desc->outfrags[0], sg_page(sg), fraglen,
504 				sg->offset + sg->length - fraglen);
505 		desc->infrags[0] = desc->outfrags[0];
506 		sg_assign_page(&desc->infrags[0], in_page);
507 		desc->fragno = 1;
508 		desc->fraglen = fraglen;
509 	} else {
510 		desc->fragno = 0;
511 		desc->fraglen = 0;
512 	}
513 	return 0;
514 }
515 
516 int
517 gss_encrypt_xdr_buf(struct crypto_skcipher *tfm, struct xdr_buf *buf,
518 		    int offset, struct page **pages)
519 {
520 	int ret;
521 	struct encryptor_desc desc;
522 	SKCIPHER_REQUEST_ON_STACK(req, tfm);
523 
524 	BUG_ON((buf->len - offset) % crypto_skcipher_blocksize(tfm) != 0);
525 
526 	skcipher_request_set_tfm(req, tfm);
527 	skcipher_request_set_callback(req, 0, NULL, NULL);
528 
529 	memset(desc.iv, 0, sizeof(desc.iv));
530 	desc.req = req;
531 	desc.pos = offset;
532 	desc.outbuf = buf;
533 	desc.pages = pages;
534 	desc.fragno = 0;
535 	desc.fraglen = 0;
536 
537 	sg_init_table(desc.infrags, 4);
538 	sg_init_table(desc.outfrags, 4);
539 
540 	ret = xdr_process_buf(buf, offset, buf->len - offset, encryptor, &desc);
541 	skcipher_request_zero(req);
542 	return ret;
543 }
544 
545 struct decryptor_desc {
546 	u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
547 	struct skcipher_request *req;
548 	struct scatterlist frags[4];
549 	int fragno;
550 	int fraglen;
551 };
552 
553 static int
554 decryptor(struct scatterlist *sg, void *data)
555 {
556 	struct decryptor_desc *desc = data;
557 	int thislen = desc->fraglen + sg->length;
558 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(desc->req);
559 	int fraglen, ret;
560 
561 	/* Worst case is 4 fragments: head, end of page 1, start
562 	 * of page 2, tail.  Anything more is a bug. */
563 	BUG_ON(desc->fragno > 3);
564 	sg_set_page(&desc->frags[desc->fragno], sg_page(sg), sg->length,
565 		    sg->offset);
566 	desc->fragno++;
567 	desc->fraglen += sg->length;
568 
569 	fraglen = thislen & (crypto_skcipher_blocksize(tfm) - 1);
570 	thislen -= fraglen;
571 
572 	if (thislen == 0)
573 		return 0;
574 
575 	sg_mark_end(&desc->frags[desc->fragno - 1]);
576 
577 	skcipher_request_set_crypt(desc->req, desc->frags, desc->frags,
578 				   thislen, desc->iv);
579 
580 	ret = crypto_skcipher_decrypt(desc->req);
581 	if (ret)
582 		return ret;
583 
584 	sg_init_table(desc->frags, 4);
585 
586 	if (fraglen) {
587 		sg_set_page(&desc->frags[0], sg_page(sg), fraglen,
588 				sg->offset + sg->length - fraglen);
589 		desc->fragno = 1;
590 		desc->fraglen = fraglen;
591 	} else {
592 		desc->fragno = 0;
593 		desc->fraglen = 0;
594 	}
595 	return 0;
596 }
597 
598 int
599 gss_decrypt_xdr_buf(struct crypto_skcipher *tfm, struct xdr_buf *buf,
600 		    int offset)
601 {
602 	int ret;
603 	struct decryptor_desc desc;
604 	SKCIPHER_REQUEST_ON_STACK(req, tfm);
605 
606 	/* XXXJBF: */
607 	BUG_ON((buf->len - offset) % crypto_skcipher_blocksize(tfm) != 0);
608 
609 	skcipher_request_set_tfm(req, tfm);
610 	skcipher_request_set_callback(req, 0, NULL, NULL);
611 
612 	memset(desc.iv, 0, sizeof(desc.iv));
613 	desc.req = req;
614 	desc.fragno = 0;
615 	desc.fraglen = 0;
616 
617 	sg_init_table(desc.frags, 4);
618 
619 	ret = xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
620 	skcipher_request_zero(req);
621 	return ret;
622 }
623 
624 /*
625  * This function makes the assumption that it was ultimately called
626  * from gss_wrap().
627  *
628  * The client auth_gss code moves any existing tail data into a
629  * separate page before calling gss_wrap.
630  * The server svcauth_gss code ensures that both the head and the
631  * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
632  *
633  * Even with that guarantee, this function may be called more than
634  * once in the processing of gss_wrap().  The best we can do is
635  * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
636  * largest expected shift will fit within RPC_MAX_AUTH_SIZE.
637  * At run-time we can verify that a single invocation of this
638  * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
639  */
640 
641 int
642 xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
643 {
644 	u8 *p;
645 
646 	if (shiftlen == 0)
647 		return 0;
648 
649 	BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE);
650 	BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
651 
652 	p = buf->head[0].iov_base + base;
653 
654 	memmove(p + shiftlen, p, buf->head[0].iov_len - base);
655 
656 	buf->head[0].iov_len += shiftlen;
657 	buf->len += shiftlen;
658 
659 	return 0;
660 }
661 
662 static u32
663 gss_krb5_cts_crypt(struct crypto_skcipher *cipher, struct xdr_buf *buf,
664 		   u32 offset, u8 *iv, struct page **pages, int encrypt)
665 {
666 	u32 ret;
667 	struct scatterlist sg[1];
668 	SKCIPHER_REQUEST_ON_STACK(req, cipher);
669 	u8 data[GSS_KRB5_MAX_BLOCKSIZE * 2];
670 	struct page **save_pages;
671 	u32 len = buf->len - offset;
672 
673 	if (len > ARRAY_SIZE(data)) {
674 		WARN_ON(0);
675 		return -ENOMEM;
676 	}
677 
678 	/*
679 	 * For encryption, we want to read from the cleartext
680 	 * page cache pages, and write the encrypted data to
681 	 * the supplied xdr_buf pages.
682 	 */
683 	save_pages = buf->pages;
684 	if (encrypt)
685 		buf->pages = pages;
686 
687 	ret = read_bytes_from_xdr_buf(buf, offset, data, len);
688 	buf->pages = save_pages;
689 	if (ret)
690 		goto out;
691 
692 	sg_init_one(sg, data, len);
693 
694 	skcipher_request_set_tfm(req, cipher);
695 	skcipher_request_set_callback(req, 0, NULL, NULL);
696 	skcipher_request_set_crypt(req, sg, sg, len, iv);
697 
698 	if (encrypt)
699 		ret = crypto_skcipher_encrypt(req);
700 	else
701 		ret = crypto_skcipher_decrypt(req);
702 
703 	skcipher_request_zero(req);
704 
705 	if (ret)
706 		goto out;
707 
708 	ret = write_bytes_to_xdr_buf(buf, offset, data, len);
709 
710 out:
711 	return ret;
712 }
713 
714 u32
715 gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
716 		     struct xdr_buf *buf, struct page **pages)
717 {
718 	u32 err;
719 	struct xdr_netobj hmac;
720 	u8 *cksumkey;
721 	u8 *ecptr;
722 	struct crypto_skcipher *cipher, *aux_cipher;
723 	int blocksize;
724 	struct page **save_pages;
725 	int nblocks, nbytes;
726 	struct encryptor_desc desc;
727 	u32 cbcbytes;
728 	unsigned int usage;
729 
730 	if (kctx->initiate) {
731 		cipher = kctx->initiator_enc;
732 		aux_cipher = kctx->initiator_enc_aux;
733 		cksumkey = kctx->initiator_integ;
734 		usage = KG_USAGE_INITIATOR_SEAL;
735 	} else {
736 		cipher = kctx->acceptor_enc;
737 		aux_cipher = kctx->acceptor_enc_aux;
738 		cksumkey = kctx->acceptor_integ;
739 		usage = KG_USAGE_ACCEPTOR_SEAL;
740 	}
741 	blocksize = crypto_skcipher_blocksize(cipher);
742 
743 	/* hide the gss token header and insert the confounder */
744 	offset += GSS_KRB5_TOK_HDR_LEN;
745 	if (xdr_extend_head(buf, offset, kctx->gk5e->conflen))
746 		return GSS_S_FAILURE;
747 	gss_krb5_make_confounder(buf->head[0].iov_base + offset, kctx->gk5e->conflen);
748 	offset -= GSS_KRB5_TOK_HDR_LEN;
749 
750 	if (buf->tail[0].iov_base != NULL) {
751 		ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
752 	} else {
753 		buf->tail[0].iov_base = buf->head[0].iov_base
754 							+ buf->head[0].iov_len;
755 		buf->tail[0].iov_len = 0;
756 		ecptr = buf->tail[0].iov_base;
757 	}
758 
759 	/* copy plaintext gss token header after filler (if any) */
760 	memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
761 	buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
762 	buf->len += GSS_KRB5_TOK_HDR_LEN;
763 
764 	/* Do the HMAC */
765 	hmac.len = GSS_KRB5_MAX_CKSUM_LEN;
766 	hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
767 
768 	/*
769 	 * When we are called, pages points to the real page cache
770 	 * data -- which we can't go and encrypt!  buf->pages points
771 	 * to scratch pages which we are going to send off to the
772 	 * client/server.  Swap in the plaintext pages to calculate
773 	 * the hmac.
774 	 */
775 	save_pages = buf->pages;
776 	buf->pages = pages;
777 
778 	err = make_checksum_v2(kctx, NULL, 0, buf,
779 			       offset + GSS_KRB5_TOK_HDR_LEN,
780 			       cksumkey, usage, &hmac);
781 	buf->pages = save_pages;
782 	if (err)
783 		return GSS_S_FAILURE;
784 
785 	nbytes = buf->len - offset - GSS_KRB5_TOK_HDR_LEN;
786 	nblocks = (nbytes + blocksize - 1) / blocksize;
787 	cbcbytes = 0;
788 	if (nblocks > 2)
789 		cbcbytes = (nblocks - 2) * blocksize;
790 
791 	memset(desc.iv, 0, sizeof(desc.iv));
792 
793 	if (cbcbytes) {
794 		SKCIPHER_REQUEST_ON_STACK(req, aux_cipher);
795 
796 		desc.pos = offset + GSS_KRB5_TOK_HDR_LEN;
797 		desc.fragno = 0;
798 		desc.fraglen = 0;
799 		desc.pages = pages;
800 		desc.outbuf = buf;
801 		desc.req = req;
802 
803 		skcipher_request_set_tfm(req, aux_cipher);
804 		skcipher_request_set_callback(req, 0, NULL, NULL);
805 
806 		sg_init_table(desc.infrags, 4);
807 		sg_init_table(desc.outfrags, 4);
808 
809 		err = xdr_process_buf(buf, offset + GSS_KRB5_TOK_HDR_LEN,
810 				      cbcbytes, encryptor, &desc);
811 		skcipher_request_zero(req);
812 		if (err)
813 			goto out_err;
814 	}
815 
816 	/* Make sure IV carries forward from any CBC results. */
817 	err = gss_krb5_cts_crypt(cipher, buf,
818 				 offset + GSS_KRB5_TOK_HDR_LEN + cbcbytes,
819 				 desc.iv, pages, 1);
820 	if (err) {
821 		err = GSS_S_FAILURE;
822 		goto out_err;
823 	}
824 
825 	/* Now update buf to account for HMAC */
826 	buf->tail[0].iov_len += kctx->gk5e->cksumlength;
827 	buf->len += kctx->gk5e->cksumlength;
828 
829 out_err:
830 	if (err)
831 		err = GSS_S_FAILURE;
832 	return err;
833 }
834 
835 u32
836 gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
837 		     u32 *headskip, u32 *tailskip)
838 {
839 	struct xdr_buf subbuf;
840 	u32 ret = 0;
841 	u8 *cksum_key;
842 	struct crypto_skcipher *cipher, *aux_cipher;
843 	struct xdr_netobj our_hmac_obj;
844 	u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
845 	u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
846 	int nblocks, blocksize, cbcbytes;
847 	struct decryptor_desc desc;
848 	unsigned int usage;
849 
850 	if (kctx->initiate) {
851 		cipher = kctx->acceptor_enc;
852 		aux_cipher = kctx->acceptor_enc_aux;
853 		cksum_key = kctx->acceptor_integ;
854 		usage = KG_USAGE_ACCEPTOR_SEAL;
855 	} else {
856 		cipher = kctx->initiator_enc;
857 		aux_cipher = kctx->initiator_enc_aux;
858 		cksum_key = kctx->initiator_integ;
859 		usage = KG_USAGE_INITIATOR_SEAL;
860 	}
861 	blocksize = crypto_skcipher_blocksize(cipher);
862 
863 
864 	/* create a segment skipping the header and leaving out the checksum */
865 	xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
866 				    (buf->len - offset - GSS_KRB5_TOK_HDR_LEN -
867 				     kctx->gk5e->cksumlength));
868 
869 	nblocks = (subbuf.len + blocksize - 1) / blocksize;
870 
871 	cbcbytes = 0;
872 	if (nblocks > 2)
873 		cbcbytes = (nblocks - 2) * blocksize;
874 
875 	memset(desc.iv, 0, sizeof(desc.iv));
876 
877 	if (cbcbytes) {
878 		SKCIPHER_REQUEST_ON_STACK(req, aux_cipher);
879 
880 		desc.fragno = 0;
881 		desc.fraglen = 0;
882 		desc.req = req;
883 
884 		skcipher_request_set_tfm(req, aux_cipher);
885 		skcipher_request_set_callback(req, 0, NULL, NULL);
886 
887 		sg_init_table(desc.frags, 4);
888 
889 		ret = xdr_process_buf(&subbuf, 0, cbcbytes, decryptor, &desc);
890 		skcipher_request_zero(req);
891 		if (ret)
892 			goto out_err;
893 	}
894 
895 	/* Make sure IV carries forward from any CBC results. */
896 	ret = gss_krb5_cts_crypt(cipher, &subbuf, cbcbytes, desc.iv, NULL, 0);
897 	if (ret)
898 		goto out_err;
899 
900 
901 	/* Calculate our hmac over the plaintext data */
902 	our_hmac_obj.len = sizeof(our_hmac);
903 	our_hmac_obj.data = our_hmac;
904 
905 	ret = make_checksum_v2(kctx, NULL, 0, &subbuf, 0,
906 			       cksum_key, usage, &our_hmac_obj);
907 	if (ret)
908 		goto out_err;
909 
910 	/* Get the packet's hmac value */
911 	ret = read_bytes_from_xdr_buf(buf, buf->len - kctx->gk5e->cksumlength,
912 				      pkt_hmac, kctx->gk5e->cksumlength);
913 	if (ret)
914 		goto out_err;
915 
916 	if (memcmp(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
917 		ret = GSS_S_BAD_SIG;
918 		goto out_err;
919 	}
920 	*headskip = kctx->gk5e->conflen;
921 	*tailskip = kctx->gk5e->cksumlength;
922 out_err:
923 	if (ret && ret != GSS_S_BAD_SIG)
924 		ret = GSS_S_FAILURE;
925 	return ret;
926 }
927 
928 /*
929  * Compute Kseq given the initial session key and the checksum.
930  * Set the key of the given cipher.
931  */
932 int
933 krb5_rc4_setup_seq_key(struct krb5_ctx *kctx, struct crypto_skcipher *cipher,
934 		       unsigned char *cksum)
935 {
936 	struct crypto_shash *hmac;
937 	struct shash_desc *desc;
938 	u8 Kseq[GSS_KRB5_MAX_KEYLEN];
939 	u32 zeroconstant = 0;
940 	int err;
941 
942 	dprintk("%s: entered\n", __func__);
943 
944 	hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
945 	if (IS_ERR(hmac)) {
946 		dprintk("%s: error %ld, allocating hash '%s'\n",
947 			__func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
948 		return PTR_ERR(hmac);
949 	}
950 
951 	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
952 		       GFP_KERNEL);
953 	if (!desc) {
954 		dprintk("%s: failed to allocate shash descriptor for '%s'\n",
955 			__func__, kctx->gk5e->cksum_name);
956 		crypto_free_shash(hmac);
957 		return -ENOMEM;
958 	}
959 
960 	desc->tfm = hmac;
961 	desc->flags = 0;
962 
963 	/* Compute intermediate Kseq from session key */
964 	err = crypto_shash_setkey(hmac, kctx->Ksess, kctx->gk5e->keylength);
965 	if (err)
966 		goto out_err;
967 
968 	err = crypto_shash_digest(desc, (u8 *)&zeroconstant, 4, Kseq);
969 	if (err)
970 		goto out_err;
971 
972 	/* Compute final Kseq from the checksum and intermediate Kseq */
973 	err = crypto_shash_setkey(hmac, Kseq, kctx->gk5e->keylength);
974 	if (err)
975 		goto out_err;
976 
977 	err = crypto_shash_digest(desc, cksum, 8, Kseq);
978 	if (err)
979 		goto out_err;
980 
981 	err = crypto_skcipher_setkey(cipher, Kseq, kctx->gk5e->keylength);
982 	if (err)
983 		goto out_err;
984 
985 	err = 0;
986 
987 out_err:
988 	kzfree(desc);
989 	crypto_free_shash(hmac);
990 	dprintk("%s: returning %d\n", __func__, err);
991 	return err;
992 }
993 
994 /*
995  * Compute Kcrypt given the initial session key and the plaintext seqnum.
996  * Set the key of cipher kctx->enc.
997  */
998 int
999 krb5_rc4_setup_enc_key(struct krb5_ctx *kctx, struct crypto_skcipher *cipher,
1000 		       s32 seqnum)
1001 {
1002 	struct crypto_shash *hmac;
1003 	struct shash_desc *desc;
1004 	u8 Kcrypt[GSS_KRB5_MAX_KEYLEN];
1005 	u8 zeroconstant[4] = {0};
1006 	u8 seqnumarray[4];
1007 	int err, i;
1008 
1009 	dprintk("%s: entered, seqnum %u\n", __func__, seqnum);
1010 
1011 	hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
1012 	if (IS_ERR(hmac)) {
1013 		dprintk("%s: error %ld, allocating hash '%s'\n",
1014 			__func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
1015 		return PTR_ERR(hmac);
1016 	}
1017 
1018 	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
1019 		       GFP_KERNEL);
1020 	if (!desc) {
1021 		dprintk("%s: failed to allocate shash descriptor for '%s'\n",
1022 			__func__, kctx->gk5e->cksum_name);
1023 		crypto_free_shash(hmac);
1024 		return -ENOMEM;
1025 	}
1026 
1027 	desc->tfm = hmac;
1028 	desc->flags = 0;
1029 
1030 	/* Compute intermediate Kcrypt from session key */
1031 	for (i = 0; i < kctx->gk5e->keylength; i++)
1032 		Kcrypt[i] = kctx->Ksess[i] ^ 0xf0;
1033 
1034 	err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
1035 	if (err)
1036 		goto out_err;
1037 
1038 	err = crypto_shash_digest(desc, zeroconstant, 4, Kcrypt);
1039 	if (err)
1040 		goto out_err;
1041 
1042 	/* Compute final Kcrypt from the seqnum and intermediate Kcrypt */
1043 	err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
1044 	if (err)
1045 		goto out_err;
1046 
1047 	seqnumarray[0] = (unsigned char) ((seqnum >> 24) & 0xff);
1048 	seqnumarray[1] = (unsigned char) ((seqnum >> 16) & 0xff);
1049 	seqnumarray[2] = (unsigned char) ((seqnum >> 8) & 0xff);
1050 	seqnumarray[3] = (unsigned char) ((seqnum >> 0) & 0xff);
1051 
1052 	err = crypto_shash_digest(desc, seqnumarray, 4, Kcrypt);
1053 	if (err)
1054 		goto out_err;
1055 
1056 	err = crypto_skcipher_setkey(cipher, Kcrypt, kctx->gk5e->keylength);
1057 	if (err)
1058 		goto out_err;
1059 
1060 	err = 0;
1061 
1062 out_err:
1063 	kzfree(desc);
1064 	crypto_free_shash(hmac);
1065 	dprintk("%s: returning %d\n", __func__, err);
1066 	return err;
1067 }
1068 
1069