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 = -1;
170 	u8 *checksumdata;
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 	checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
191 	if (!checksumdata)
192 		return GSS_S_FAILURE;
193 
194 	md5 = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
195 	if (IS_ERR(md5))
196 		goto out_free_cksum;
197 
198 	hmac_md5 = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0,
199 				      CRYPTO_ALG_ASYNC);
200 	if (IS_ERR(hmac_md5))
201 		goto out_free_md5;
202 
203 	req = ahash_request_alloc(md5, GFP_NOFS);
204 	if (!req)
205 		goto out_free_hmac_md5;
206 
207 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
208 
209 	err = crypto_ahash_init(req);
210 	if (err)
211 		goto out;
212 	sg_init_one(sg, rc4salt, 4);
213 	ahash_request_set_crypt(req, sg, NULL, 4);
214 	err = crypto_ahash_update(req);
215 	if (err)
216 		goto out;
217 
218 	sg_init_one(sg, header, hdrlen);
219 	ahash_request_set_crypt(req, sg, NULL, hdrlen);
220 	err = crypto_ahash_update(req);
221 	if (err)
222 		goto out;
223 	err = xdr_process_buf(body, body_offset, body->len - body_offset,
224 			      checksummer, req);
225 	if (err)
226 		goto out;
227 	ahash_request_set_crypt(req, NULL, checksumdata, 0);
228 	err = crypto_ahash_final(req);
229 	if (err)
230 		goto out;
231 
232 	ahash_request_free(req);
233 	req = ahash_request_alloc(hmac_md5, GFP_NOFS);
234 	if (!req)
235 		goto out_free_hmac_md5;
236 
237 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
238 
239 	err = crypto_ahash_init(req);
240 	if (err)
241 		goto out;
242 	err = crypto_ahash_setkey(hmac_md5, cksumkey, kctx->gk5e->keylength);
243 	if (err)
244 		goto out;
245 
246 	sg_init_one(sg, checksumdata, crypto_ahash_digestsize(md5));
247 	ahash_request_set_crypt(req, sg, checksumdata,
248 				crypto_ahash_digestsize(md5));
249 	err = crypto_ahash_digest(req);
250 	if (err)
251 		goto out;
252 
253 	memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
254 	cksumout->len = kctx->gk5e->cksumlength;
255 out:
256 	ahash_request_free(req);
257 out_free_hmac_md5:
258 	crypto_free_ahash(hmac_md5);
259 out_free_md5:
260 	crypto_free_ahash(md5);
261 out_free_cksum:
262 	kfree(checksumdata);
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 = -1;
280 	u8 *checksumdata;
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 	checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
295 	if (checksumdata == NULL)
296 		return GSS_S_FAILURE;
297 
298 	tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
299 	if (IS_ERR(tfm))
300 		goto out_free_cksum;
301 
302 	req = ahash_request_alloc(tfm, GFP_NOFS);
303 	if (!req)
304 		goto out_free_ahash;
305 
306 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
307 
308 	checksumlen = crypto_ahash_digestsize(tfm);
309 
310 	if (cksumkey != NULL) {
311 		err = crypto_ahash_setkey(tfm, cksumkey,
312 					  kctx->gk5e->keylength);
313 		if (err)
314 			goto out;
315 	}
316 
317 	err = crypto_ahash_init(req);
318 	if (err)
319 		goto out;
320 	sg_init_one(sg, header, hdrlen);
321 	ahash_request_set_crypt(req, sg, NULL, hdrlen);
322 	err = crypto_ahash_update(req);
323 	if (err)
324 		goto out;
325 	err = xdr_process_buf(body, body_offset, body->len - body_offset,
326 			      checksummer, req);
327 	if (err)
328 		goto out;
329 	ahash_request_set_crypt(req, NULL, checksumdata, 0);
330 	err = crypto_ahash_final(req);
331 	if (err)
332 		goto out;
333 
334 	switch (kctx->gk5e->ctype) {
335 	case CKSUMTYPE_RSA_MD5:
336 		err = kctx->gk5e->encrypt(kctx->seq, NULL, checksumdata,
337 					  checksumdata, checksumlen);
338 		if (err)
339 			goto out;
340 		memcpy(cksumout->data,
341 		       checksumdata + checksumlen - kctx->gk5e->cksumlength,
342 		       kctx->gk5e->cksumlength);
343 		break;
344 	case CKSUMTYPE_HMAC_SHA1_DES3:
345 		memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
346 		break;
347 	default:
348 		BUG();
349 		break;
350 	}
351 	cksumout->len = kctx->gk5e->cksumlength;
352 out:
353 	ahash_request_free(req);
354 out_free_ahash:
355 	crypto_free_ahash(tfm);
356 out_free_cksum:
357 	kfree(checksumdata);
358 	return err ? GSS_S_FAILURE : 0;
359 }
360 
361 /*
362  * checksum the plaintext data and hdrlen bytes of the token header
363  * Per rfc4121, sec. 4.2.4, the checksum is performed over the data
364  * body then over the first 16 octets of the MIC token
365  * Inclusion of the header data in the calculation of the
366  * checksum is optional.
367  */
368 u32
369 make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen,
370 		 struct xdr_buf *body, int body_offset, u8 *cksumkey,
371 		 unsigned int usage, struct xdr_netobj *cksumout)
372 {
373 	struct crypto_ahash *tfm;
374 	struct ahash_request *req;
375 	struct scatterlist sg[1];
376 	int err = -1;
377 	u8 *checksumdata;
378 	unsigned int checksumlen;
379 
380 	if (kctx->gk5e->keyed_cksum == 0) {
381 		dprintk("%s: expected keyed hash for %s\n",
382 			__func__, kctx->gk5e->name);
383 		return GSS_S_FAILURE;
384 	}
385 	if (cksumkey == NULL) {
386 		dprintk("%s: no key supplied for %s\n",
387 			__func__, kctx->gk5e->name);
388 		return GSS_S_FAILURE;
389 	}
390 
391 	checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
392 	if (!checksumdata)
393 		return GSS_S_FAILURE;
394 
395 	tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
396 	if (IS_ERR(tfm))
397 		goto out_free_cksum;
398 	checksumlen = crypto_ahash_digestsize(tfm);
399 
400 	req = ahash_request_alloc(tfm, GFP_NOFS);
401 	if (!req)
402 		goto out_free_ahash;
403 
404 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
405 
406 	err = crypto_ahash_setkey(tfm, cksumkey, kctx->gk5e->keylength);
407 	if (err)
408 		goto out;
409 
410 	err = crypto_ahash_init(req);
411 	if (err)
412 		goto out;
413 	err = xdr_process_buf(body, body_offset, body->len - body_offset,
414 			      checksummer, req);
415 	if (err)
416 		goto out;
417 	if (header != NULL) {
418 		sg_init_one(sg, header, hdrlen);
419 		ahash_request_set_crypt(req, sg, NULL, hdrlen);
420 		err = crypto_ahash_update(req);
421 		if (err)
422 			goto out;
423 	}
424 	ahash_request_set_crypt(req, NULL, checksumdata, 0);
425 	err = crypto_ahash_final(req);
426 	if (err)
427 		goto out;
428 
429 	cksumout->len = kctx->gk5e->cksumlength;
430 
431 	switch (kctx->gk5e->ctype) {
432 	case CKSUMTYPE_HMAC_SHA1_96_AES128:
433 	case CKSUMTYPE_HMAC_SHA1_96_AES256:
434 		/* note that this truncates the hash */
435 		memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
436 		break;
437 	default:
438 		BUG();
439 		break;
440 	}
441 out:
442 	ahash_request_free(req);
443 out_free_ahash:
444 	crypto_free_ahash(tfm);
445 out_free_cksum:
446 	kfree(checksumdata);
447 	return err ? GSS_S_FAILURE : 0;
448 }
449 
450 struct encryptor_desc {
451 	u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
452 	struct skcipher_request *req;
453 	int pos;
454 	struct xdr_buf *outbuf;
455 	struct page **pages;
456 	struct scatterlist infrags[4];
457 	struct scatterlist outfrags[4];
458 	int fragno;
459 	int fraglen;
460 };
461 
462 static int
463 encryptor(struct scatterlist *sg, void *data)
464 {
465 	struct encryptor_desc *desc = data;
466 	struct xdr_buf *outbuf = desc->outbuf;
467 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(desc->req);
468 	struct page *in_page;
469 	int thislen = desc->fraglen + sg->length;
470 	int fraglen, ret;
471 	int page_pos;
472 
473 	/* Worst case is 4 fragments: head, end of page 1, start
474 	 * of page 2, tail.  Anything more is a bug. */
475 	BUG_ON(desc->fragno > 3);
476 
477 	page_pos = desc->pos - outbuf->head[0].iov_len;
478 	if (page_pos >= 0 && page_pos < outbuf->page_len) {
479 		/* pages are not in place: */
480 		int i = (page_pos + outbuf->page_base) >> PAGE_SHIFT;
481 		in_page = desc->pages[i];
482 	} else {
483 		in_page = sg_page(sg);
484 	}
485 	sg_set_page(&desc->infrags[desc->fragno], in_page, sg->length,
486 		    sg->offset);
487 	sg_set_page(&desc->outfrags[desc->fragno], sg_page(sg), sg->length,
488 		    sg->offset);
489 	desc->fragno++;
490 	desc->fraglen += sg->length;
491 	desc->pos += sg->length;
492 
493 	fraglen = thislen & (crypto_skcipher_blocksize(tfm) - 1);
494 	thislen -= fraglen;
495 
496 	if (thislen == 0)
497 		return 0;
498 
499 	sg_mark_end(&desc->infrags[desc->fragno - 1]);
500 	sg_mark_end(&desc->outfrags[desc->fragno - 1]);
501 
502 	skcipher_request_set_crypt(desc->req, desc->infrags, desc->outfrags,
503 				   thislen, desc->iv);
504 
505 	ret = crypto_skcipher_encrypt(desc->req);
506 	if (ret)
507 		return ret;
508 
509 	sg_init_table(desc->infrags, 4);
510 	sg_init_table(desc->outfrags, 4);
511 
512 	if (fraglen) {
513 		sg_set_page(&desc->outfrags[0], sg_page(sg), fraglen,
514 				sg->offset + sg->length - fraglen);
515 		desc->infrags[0] = desc->outfrags[0];
516 		sg_assign_page(&desc->infrags[0], in_page);
517 		desc->fragno = 1;
518 		desc->fraglen = fraglen;
519 	} else {
520 		desc->fragno = 0;
521 		desc->fraglen = 0;
522 	}
523 	return 0;
524 }
525 
526 int
527 gss_encrypt_xdr_buf(struct crypto_skcipher *tfm, struct xdr_buf *buf,
528 		    int offset, struct page **pages)
529 {
530 	int ret;
531 	struct encryptor_desc desc;
532 	SKCIPHER_REQUEST_ON_STACK(req, tfm);
533 
534 	BUG_ON((buf->len - offset) % crypto_skcipher_blocksize(tfm) != 0);
535 
536 	skcipher_request_set_tfm(req, tfm);
537 	skcipher_request_set_callback(req, 0, NULL, NULL);
538 
539 	memset(desc.iv, 0, sizeof(desc.iv));
540 	desc.req = req;
541 	desc.pos = offset;
542 	desc.outbuf = buf;
543 	desc.pages = pages;
544 	desc.fragno = 0;
545 	desc.fraglen = 0;
546 
547 	sg_init_table(desc.infrags, 4);
548 	sg_init_table(desc.outfrags, 4);
549 
550 	ret = xdr_process_buf(buf, offset, buf->len - offset, encryptor, &desc);
551 	skcipher_request_zero(req);
552 	return ret;
553 }
554 
555 struct decryptor_desc {
556 	u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
557 	struct skcipher_request *req;
558 	struct scatterlist frags[4];
559 	int fragno;
560 	int fraglen;
561 };
562 
563 static int
564 decryptor(struct scatterlist *sg, void *data)
565 {
566 	struct decryptor_desc *desc = data;
567 	int thislen = desc->fraglen + sg->length;
568 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(desc->req);
569 	int fraglen, ret;
570 
571 	/* Worst case is 4 fragments: head, end of page 1, start
572 	 * of page 2, tail.  Anything more is a bug. */
573 	BUG_ON(desc->fragno > 3);
574 	sg_set_page(&desc->frags[desc->fragno], sg_page(sg), sg->length,
575 		    sg->offset);
576 	desc->fragno++;
577 	desc->fraglen += sg->length;
578 
579 	fraglen = thislen & (crypto_skcipher_blocksize(tfm) - 1);
580 	thislen -= fraglen;
581 
582 	if (thislen == 0)
583 		return 0;
584 
585 	sg_mark_end(&desc->frags[desc->fragno - 1]);
586 
587 	skcipher_request_set_crypt(desc->req, desc->frags, desc->frags,
588 				   thislen, desc->iv);
589 
590 	ret = crypto_skcipher_decrypt(desc->req);
591 	if (ret)
592 		return ret;
593 
594 	sg_init_table(desc->frags, 4);
595 
596 	if (fraglen) {
597 		sg_set_page(&desc->frags[0], sg_page(sg), fraglen,
598 				sg->offset + sg->length - fraglen);
599 		desc->fragno = 1;
600 		desc->fraglen = fraglen;
601 	} else {
602 		desc->fragno = 0;
603 		desc->fraglen = 0;
604 	}
605 	return 0;
606 }
607 
608 int
609 gss_decrypt_xdr_buf(struct crypto_skcipher *tfm, struct xdr_buf *buf,
610 		    int offset)
611 {
612 	int ret;
613 	struct decryptor_desc desc;
614 	SKCIPHER_REQUEST_ON_STACK(req, tfm);
615 
616 	/* XXXJBF: */
617 	BUG_ON((buf->len - offset) % crypto_skcipher_blocksize(tfm) != 0);
618 
619 	skcipher_request_set_tfm(req, tfm);
620 	skcipher_request_set_callback(req, 0, NULL, NULL);
621 
622 	memset(desc.iv, 0, sizeof(desc.iv));
623 	desc.req = req;
624 	desc.fragno = 0;
625 	desc.fraglen = 0;
626 
627 	sg_init_table(desc.frags, 4);
628 
629 	ret = xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
630 	skcipher_request_zero(req);
631 	return ret;
632 }
633 
634 /*
635  * This function makes the assumption that it was ultimately called
636  * from gss_wrap().
637  *
638  * The client auth_gss code moves any existing tail data into a
639  * separate page before calling gss_wrap.
640  * The server svcauth_gss code ensures that both the head and the
641  * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
642  *
643  * Even with that guarantee, this function may be called more than
644  * once in the processing of gss_wrap().  The best we can do is
645  * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
646  * largest expected shift will fit within RPC_MAX_AUTH_SIZE.
647  * At run-time we can verify that a single invocation of this
648  * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
649  */
650 
651 int
652 xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
653 {
654 	u8 *p;
655 
656 	if (shiftlen == 0)
657 		return 0;
658 
659 	BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE);
660 	BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
661 
662 	p = buf->head[0].iov_base + base;
663 
664 	memmove(p + shiftlen, p, buf->head[0].iov_len - base);
665 
666 	buf->head[0].iov_len += shiftlen;
667 	buf->len += shiftlen;
668 
669 	return 0;
670 }
671 
672 static u32
673 gss_krb5_cts_crypt(struct crypto_skcipher *cipher, struct xdr_buf *buf,
674 		   u32 offset, u8 *iv, struct page **pages, int encrypt)
675 {
676 	u32 ret;
677 	struct scatterlist sg[1];
678 	SKCIPHER_REQUEST_ON_STACK(req, cipher);
679 	u8 *data;
680 	struct page **save_pages;
681 	u32 len = buf->len - offset;
682 
683 	if (len > GSS_KRB5_MAX_BLOCKSIZE * 2) {
684 		WARN_ON(0);
685 		return -ENOMEM;
686 	}
687 	data = kmalloc(GSS_KRB5_MAX_BLOCKSIZE * 2, GFP_NOFS);
688 	if (!data)
689 		return -ENOMEM;
690 
691 	/*
692 	 * For encryption, we want to read from the cleartext
693 	 * page cache pages, and write the encrypted data to
694 	 * the supplied xdr_buf pages.
695 	 */
696 	save_pages = buf->pages;
697 	if (encrypt)
698 		buf->pages = pages;
699 
700 	ret = read_bytes_from_xdr_buf(buf, offset, data, len);
701 	buf->pages = save_pages;
702 	if (ret)
703 		goto out;
704 
705 	sg_init_one(sg, data, len);
706 
707 	skcipher_request_set_tfm(req, cipher);
708 	skcipher_request_set_callback(req, 0, NULL, NULL);
709 	skcipher_request_set_crypt(req, sg, sg, len, iv);
710 
711 	if (encrypt)
712 		ret = crypto_skcipher_encrypt(req);
713 	else
714 		ret = crypto_skcipher_decrypt(req);
715 
716 	skcipher_request_zero(req);
717 
718 	if (ret)
719 		goto out;
720 
721 	ret = write_bytes_to_xdr_buf(buf, offset, data, len);
722 
723 out:
724 	kfree(data);
725 	return ret;
726 }
727 
728 u32
729 gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
730 		     struct xdr_buf *buf, struct page **pages)
731 {
732 	u32 err;
733 	struct xdr_netobj hmac;
734 	u8 *cksumkey;
735 	u8 *ecptr;
736 	struct crypto_skcipher *cipher, *aux_cipher;
737 	int blocksize;
738 	struct page **save_pages;
739 	int nblocks, nbytes;
740 	struct encryptor_desc desc;
741 	u32 cbcbytes;
742 	unsigned int usage;
743 
744 	if (kctx->initiate) {
745 		cipher = kctx->initiator_enc;
746 		aux_cipher = kctx->initiator_enc_aux;
747 		cksumkey = kctx->initiator_integ;
748 		usage = KG_USAGE_INITIATOR_SEAL;
749 	} else {
750 		cipher = kctx->acceptor_enc;
751 		aux_cipher = kctx->acceptor_enc_aux;
752 		cksumkey = kctx->acceptor_integ;
753 		usage = KG_USAGE_ACCEPTOR_SEAL;
754 	}
755 	blocksize = crypto_skcipher_blocksize(cipher);
756 
757 	/* hide the gss token header and insert the confounder */
758 	offset += GSS_KRB5_TOK_HDR_LEN;
759 	if (xdr_extend_head(buf, offset, kctx->gk5e->conflen))
760 		return GSS_S_FAILURE;
761 	gss_krb5_make_confounder(buf->head[0].iov_base + offset, kctx->gk5e->conflen);
762 	offset -= GSS_KRB5_TOK_HDR_LEN;
763 
764 	if (buf->tail[0].iov_base != NULL) {
765 		ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
766 	} else {
767 		buf->tail[0].iov_base = buf->head[0].iov_base
768 							+ buf->head[0].iov_len;
769 		buf->tail[0].iov_len = 0;
770 		ecptr = buf->tail[0].iov_base;
771 	}
772 
773 	/* copy plaintext gss token header after filler (if any) */
774 	memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
775 	buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
776 	buf->len += GSS_KRB5_TOK_HDR_LEN;
777 
778 	/* Do the HMAC */
779 	hmac.len = GSS_KRB5_MAX_CKSUM_LEN;
780 	hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
781 
782 	/*
783 	 * When we are called, pages points to the real page cache
784 	 * data -- which we can't go and encrypt!  buf->pages points
785 	 * to scratch pages which we are going to send off to the
786 	 * client/server.  Swap in the plaintext pages to calculate
787 	 * the hmac.
788 	 */
789 	save_pages = buf->pages;
790 	buf->pages = pages;
791 
792 	err = make_checksum_v2(kctx, NULL, 0, buf,
793 			       offset + GSS_KRB5_TOK_HDR_LEN,
794 			       cksumkey, usage, &hmac);
795 	buf->pages = save_pages;
796 	if (err)
797 		return GSS_S_FAILURE;
798 
799 	nbytes = buf->len - offset - GSS_KRB5_TOK_HDR_LEN;
800 	nblocks = (nbytes + blocksize - 1) / blocksize;
801 	cbcbytes = 0;
802 	if (nblocks > 2)
803 		cbcbytes = (nblocks - 2) * blocksize;
804 
805 	memset(desc.iv, 0, sizeof(desc.iv));
806 
807 	if (cbcbytes) {
808 		SKCIPHER_REQUEST_ON_STACK(req, aux_cipher);
809 
810 		desc.pos = offset + GSS_KRB5_TOK_HDR_LEN;
811 		desc.fragno = 0;
812 		desc.fraglen = 0;
813 		desc.pages = pages;
814 		desc.outbuf = buf;
815 		desc.req = req;
816 
817 		skcipher_request_set_tfm(req, aux_cipher);
818 		skcipher_request_set_callback(req, 0, NULL, NULL);
819 
820 		sg_init_table(desc.infrags, 4);
821 		sg_init_table(desc.outfrags, 4);
822 
823 		err = xdr_process_buf(buf, offset + GSS_KRB5_TOK_HDR_LEN,
824 				      cbcbytes, encryptor, &desc);
825 		skcipher_request_zero(req);
826 		if (err)
827 			goto out_err;
828 	}
829 
830 	/* Make sure IV carries forward from any CBC results. */
831 	err = gss_krb5_cts_crypt(cipher, buf,
832 				 offset + GSS_KRB5_TOK_HDR_LEN + cbcbytes,
833 				 desc.iv, pages, 1);
834 	if (err) {
835 		err = GSS_S_FAILURE;
836 		goto out_err;
837 	}
838 
839 	/* Now update buf to account for HMAC */
840 	buf->tail[0].iov_len += kctx->gk5e->cksumlength;
841 	buf->len += kctx->gk5e->cksumlength;
842 
843 out_err:
844 	if (err)
845 		err = GSS_S_FAILURE;
846 	return err;
847 }
848 
849 u32
850 gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
851 		     u32 *headskip, u32 *tailskip)
852 {
853 	struct xdr_buf subbuf;
854 	u32 ret = 0;
855 	u8 *cksum_key;
856 	struct crypto_skcipher *cipher, *aux_cipher;
857 	struct xdr_netobj our_hmac_obj;
858 	u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
859 	u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
860 	int nblocks, blocksize, cbcbytes;
861 	struct decryptor_desc desc;
862 	unsigned int usage;
863 
864 	if (kctx->initiate) {
865 		cipher = kctx->acceptor_enc;
866 		aux_cipher = kctx->acceptor_enc_aux;
867 		cksum_key = kctx->acceptor_integ;
868 		usage = KG_USAGE_ACCEPTOR_SEAL;
869 	} else {
870 		cipher = kctx->initiator_enc;
871 		aux_cipher = kctx->initiator_enc_aux;
872 		cksum_key = kctx->initiator_integ;
873 		usage = KG_USAGE_INITIATOR_SEAL;
874 	}
875 	blocksize = crypto_skcipher_blocksize(cipher);
876 
877 
878 	/* create a segment skipping the header and leaving out the checksum */
879 	xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
880 				    (buf->len - offset - GSS_KRB5_TOK_HDR_LEN -
881 				     kctx->gk5e->cksumlength));
882 
883 	nblocks = (subbuf.len + blocksize - 1) / blocksize;
884 
885 	cbcbytes = 0;
886 	if (nblocks > 2)
887 		cbcbytes = (nblocks - 2) * blocksize;
888 
889 	memset(desc.iv, 0, sizeof(desc.iv));
890 
891 	if (cbcbytes) {
892 		SKCIPHER_REQUEST_ON_STACK(req, aux_cipher);
893 
894 		desc.fragno = 0;
895 		desc.fraglen = 0;
896 		desc.req = req;
897 
898 		skcipher_request_set_tfm(req, aux_cipher);
899 		skcipher_request_set_callback(req, 0, NULL, NULL);
900 
901 		sg_init_table(desc.frags, 4);
902 
903 		ret = xdr_process_buf(&subbuf, 0, cbcbytes, decryptor, &desc);
904 		skcipher_request_zero(req);
905 		if (ret)
906 			goto out_err;
907 	}
908 
909 	/* Make sure IV carries forward from any CBC results. */
910 	ret = gss_krb5_cts_crypt(cipher, &subbuf, cbcbytes, desc.iv, NULL, 0);
911 	if (ret)
912 		goto out_err;
913 
914 
915 	/* Calculate our hmac over the plaintext data */
916 	our_hmac_obj.len = sizeof(our_hmac);
917 	our_hmac_obj.data = our_hmac;
918 
919 	ret = make_checksum_v2(kctx, NULL, 0, &subbuf, 0,
920 			       cksum_key, usage, &our_hmac_obj);
921 	if (ret)
922 		goto out_err;
923 
924 	/* Get the packet's hmac value */
925 	ret = read_bytes_from_xdr_buf(buf, buf->len - kctx->gk5e->cksumlength,
926 				      pkt_hmac, kctx->gk5e->cksumlength);
927 	if (ret)
928 		goto out_err;
929 
930 	if (memcmp(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
931 		ret = GSS_S_BAD_SIG;
932 		goto out_err;
933 	}
934 	*headskip = kctx->gk5e->conflen;
935 	*tailskip = kctx->gk5e->cksumlength;
936 out_err:
937 	if (ret && ret != GSS_S_BAD_SIG)
938 		ret = GSS_S_FAILURE;
939 	return ret;
940 }
941 
942 /*
943  * Compute Kseq given the initial session key and the checksum.
944  * Set the key of the given cipher.
945  */
946 int
947 krb5_rc4_setup_seq_key(struct krb5_ctx *kctx, struct crypto_skcipher *cipher,
948 		       unsigned char *cksum)
949 {
950 	struct crypto_shash *hmac;
951 	struct shash_desc *desc;
952 	u8 Kseq[GSS_KRB5_MAX_KEYLEN];
953 	u32 zeroconstant = 0;
954 	int err;
955 
956 	dprintk("%s: entered\n", __func__);
957 
958 	hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
959 	if (IS_ERR(hmac)) {
960 		dprintk("%s: error %ld, allocating hash '%s'\n",
961 			__func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
962 		return PTR_ERR(hmac);
963 	}
964 
965 	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
966 		       GFP_NOFS);
967 	if (!desc) {
968 		dprintk("%s: failed to allocate shash descriptor for '%s'\n",
969 			__func__, kctx->gk5e->cksum_name);
970 		crypto_free_shash(hmac);
971 		return -ENOMEM;
972 	}
973 
974 	desc->tfm = hmac;
975 	desc->flags = 0;
976 
977 	/* Compute intermediate Kseq from session key */
978 	err = crypto_shash_setkey(hmac, kctx->Ksess, kctx->gk5e->keylength);
979 	if (err)
980 		goto out_err;
981 
982 	err = crypto_shash_digest(desc, (u8 *)&zeroconstant, 4, Kseq);
983 	if (err)
984 		goto out_err;
985 
986 	/* Compute final Kseq from the checksum and intermediate Kseq */
987 	err = crypto_shash_setkey(hmac, Kseq, kctx->gk5e->keylength);
988 	if (err)
989 		goto out_err;
990 
991 	err = crypto_shash_digest(desc, cksum, 8, Kseq);
992 	if (err)
993 		goto out_err;
994 
995 	err = crypto_skcipher_setkey(cipher, Kseq, kctx->gk5e->keylength);
996 	if (err)
997 		goto out_err;
998 
999 	err = 0;
1000 
1001 out_err:
1002 	kzfree(desc);
1003 	crypto_free_shash(hmac);
1004 	dprintk("%s: returning %d\n", __func__, err);
1005 	return err;
1006 }
1007 
1008 /*
1009  * Compute Kcrypt given the initial session key and the plaintext seqnum.
1010  * Set the key of cipher kctx->enc.
1011  */
1012 int
1013 krb5_rc4_setup_enc_key(struct krb5_ctx *kctx, struct crypto_skcipher *cipher,
1014 		       s32 seqnum)
1015 {
1016 	struct crypto_shash *hmac;
1017 	struct shash_desc *desc;
1018 	u8 Kcrypt[GSS_KRB5_MAX_KEYLEN];
1019 	u8 zeroconstant[4] = {0};
1020 	u8 seqnumarray[4];
1021 	int err, i;
1022 
1023 	dprintk("%s: entered, seqnum %u\n", __func__, seqnum);
1024 
1025 	hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
1026 	if (IS_ERR(hmac)) {
1027 		dprintk("%s: error %ld, allocating hash '%s'\n",
1028 			__func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
1029 		return PTR_ERR(hmac);
1030 	}
1031 
1032 	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
1033 		       GFP_NOFS);
1034 	if (!desc) {
1035 		dprintk("%s: failed to allocate shash descriptor for '%s'\n",
1036 			__func__, kctx->gk5e->cksum_name);
1037 		crypto_free_shash(hmac);
1038 		return -ENOMEM;
1039 	}
1040 
1041 	desc->tfm = hmac;
1042 	desc->flags = 0;
1043 
1044 	/* Compute intermediate Kcrypt from session key */
1045 	for (i = 0; i < kctx->gk5e->keylength; i++)
1046 		Kcrypt[i] = kctx->Ksess[i] ^ 0xf0;
1047 
1048 	err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
1049 	if (err)
1050 		goto out_err;
1051 
1052 	err = crypto_shash_digest(desc, zeroconstant, 4, Kcrypt);
1053 	if (err)
1054 		goto out_err;
1055 
1056 	/* Compute final Kcrypt from the seqnum and intermediate Kcrypt */
1057 	err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
1058 	if (err)
1059 		goto out_err;
1060 
1061 	seqnumarray[0] = (unsigned char) ((seqnum >> 24) & 0xff);
1062 	seqnumarray[1] = (unsigned char) ((seqnum >> 16) & 0xff);
1063 	seqnumarray[2] = (unsigned char) ((seqnum >> 8) & 0xff);
1064 	seqnumarray[3] = (unsigned char) ((seqnum >> 0) & 0xff);
1065 
1066 	err = crypto_shash_digest(desc, seqnumarray, 4, Kcrypt);
1067 	if (err)
1068 		goto out_err;
1069 
1070 	err = crypto_skcipher_setkey(cipher, Kcrypt, kctx->gk5e->keylength);
1071 	if (err)
1072 		goto out_err;
1073 
1074 	err = 0;
1075 
1076 out_err:
1077 	kzfree(desc);
1078 	crypto_free_shash(hmac);
1079 	dprintk("%s: returning %d\n", __func__, err);
1080 	return err;
1081 }
1082 
1083