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/algapi.h>
38 #include <crypto/hash.h>
39 #include <crypto/skcipher.h>
40 #include <linux/err.h>
41 #include <linux/types.h>
42 #include <linux/mm.h>
43 #include <linux/scatterlist.h>
44 #include <linux/highmem.h>
45 #include <linux/pagemap.h>
46 #include <linux/random.h>
47 #include <linux/sunrpc/gss_krb5.h>
48 #include <linux/sunrpc/xdr.h>
49 #include <kunit/visibility.h>
50 
51 #include "gss_krb5_internal.h"
52 
53 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
54 # define RPCDBG_FACILITY        RPCDBG_AUTH
55 #endif
56 
57 /**
58  * krb5_make_confounder - Generate a confounder string
59  * @p: memory location into which to write the string
60  * @conflen: string length to write, in octets
61  *
62  * RFCs 1964 and 3961 mention only "a random confounder" without going
63  * into detail about its function or cryptographic requirements. The
64  * assumed purpose is to prevent repeated encryption of a plaintext with
65  * the same key from generating the same ciphertext. It is also used to
66  * pad minimum plaintext length to at least a single cipher block.
67  *
68  * However, in situations like the GSS Kerberos 5 mechanism, where the
69  * encryption IV is always all zeroes, the confounder also effectively
70  * functions like an IV. Thus, not only must it be unique from message
71  * to message, but it must also be difficult to predict. Otherwise an
72  * attacker can correlate the confounder to previous or future values,
73  * making the encryption easier to break.
74  *
75  * Given that the primary consumer of this encryption mechanism is a
76  * network storage protocol, a type of traffic that often carries
77  * predictable payloads (eg, all zeroes when reading unallocated blocks
78  * from a file), our confounder generation has to be cryptographically
79  * strong.
80  */
81 void krb5_make_confounder(u8 *p, int conflen)
82 {
83 	get_random_bytes(p, conflen);
84 }
85 
86 /**
87  * krb5_encrypt - simple encryption of an RPCSEC GSS payload
88  * @tfm: initialized cipher transform
89  * @iv: pointer to an IV
90  * @in: plaintext to encrypt
91  * @out: OUT: ciphertext
92  * @length: length of input and output buffers, in bytes
93  *
94  * @iv may be NULL to force the use of an all-zero IV.
95  * The buffer containing the IV must be as large as the
96  * cipher's ivsize.
97  *
98  * Return values:
99  *   %0: @in successfully encrypted into @out
100  *   negative errno: @in not encrypted
101  */
102 u32
103 krb5_encrypt(
104 	struct crypto_sync_skcipher *tfm,
105 	void * iv,
106 	void * in,
107 	void * out,
108 	int length)
109 {
110 	u32 ret = -EINVAL;
111 	struct scatterlist sg[1];
112 	u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
113 	SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
114 
115 	if (length % crypto_sync_skcipher_blocksize(tfm) != 0)
116 		goto out;
117 
118 	if (crypto_sync_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
119 		dprintk("RPC:       gss_k5encrypt: tfm iv size too large %d\n",
120 			crypto_sync_skcipher_ivsize(tfm));
121 		goto out;
122 	}
123 
124 	if (iv)
125 		memcpy(local_iv, iv, crypto_sync_skcipher_ivsize(tfm));
126 
127 	memcpy(out, in, length);
128 	sg_init_one(sg, out, length);
129 
130 	skcipher_request_set_sync_tfm(req, tfm);
131 	skcipher_request_set_callback(req, 0, NULL, NULL);
132 	skcipher_request_set_crypt(req, sg, sg, length, local_iv);
133 
134 	ret = crypto_skcipher_encrypt(req);
135 	skcipher_request_zero(req);
136 out:
137 	dprintk("RPC:       krb5_encrypt returns %d\n", ret);
138 	return ret;
139 }
140 
141 /**
142  * krb5_decrypt - simple decryption of an RPCSEC GSS payload
143  * @tfm: initialized cipher transform
144  * @iv: pointer to an IV
145  * @in: ciphertext to decrypt
146  * @out: OUT: plaintext
147  * @length: length of input and output buffers, in bytes
148  *
149  * @iv may be NULL to force the use of an all-zero IV.
150  * The buffer containing the IV must be as large as the
151  * cipher's ivsize.
152  *
153  * Return values:
154  *   %0: @in successfully decrypted into @out
155  *   negative errno: @in not decrypted
156  */
157 u32
158 krb5_decrypt(
159      struct crypto_sync_skcipher *tfm,
160      void * iv,
161      void * in,
162      void * out,
163      int length)
164 {
165 	u32 ret = -EINVAL;
166 	struct scatterlist sg[1];
167 	u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
168 	SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
169 
170 	if (length % crypto_sync_skcipher_blocksize(tfm) != 0)
171 		goto out;
172 
173 	if (crypto_sync_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
174 		dprintk("RPC:       gss_k5decrypt: tfm iv size too large %d\n",
175 			crypto_sync_skcipher_ivsize(tfm));
176 		goto out;
177 	}
178 	if (iv)
179 		memcpy(local_iv, iv, crypto_sync_skcipher_ivsize(tfm));
180 
181 	memcpy(out, in, length);
182 	sg_init_one(sg, out, length);
183 
184 	skcipher_request_set_sync_tfm(req, tfm);
185 	skcipher_request_set_callback(req, 0, NULL, NULL);
186 	skcipher_request_set_crypt(req, sg, sg, length, local_iv);
187 
188 	ret = crypto_skcipher_decrypt(req);
189 	skcipher_request_zero(req);
190 out:
191 	dprintk("RPC:       gss_k5decrypt returns %d\n",ret);
192 	return ret;
193 }
194 
195 static int
196 checksummer(struct scatterlist *sg, void *data)
197 {
198 	struct ahash_request *req = data;
199 
200 	ahash_request_set_crypt(req, sg, NULL, sg->length);
201 
202 	return crypto_ahash_update(req);
203 }
204 
205 /*
206  * checksum the plaintext data and hdrlen bytes of the token header
207  * The checksum is performed over the first 8 bytes of the
208  * gss token header and then over the data body
209  */
210 u32
211 make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
212 	      struct xdr_buf *body, int body_offset, u8 *cksumkey,
213 	      unsigned int usage, struct xdr_netobj *cksumout)
214 {
215 	struct crypto_ahash *tfm;
216 	struct ahash_request *req;
217 	struct scatterlist              sg[1];
218 	int err = -1;
219 	u8 *checksumdata;
220 	unsigned int checksumlen;
221 
222 	if (cksumout->len < kctx->gk5e->cksumlength) {
223 		dprintk("%s: checksum buffer length, %u, too small for %s\n",
224 			__func__, cksumout->len, kctx->gk5e->name);
225 		return GSS_S_FAILURE;
226 	}
227 
228 	checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_KERNEL);
229 	if (checksumdata == NULL)
230 		return GSS_S_FAILURE;
231 
232 	tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
233 	if (IS_ERR(tfm))
234 		goto out_free_cksum;
235 
236 	req = ahash_request_alloc(tfm, GFP_KERNEL);
237 	if (!req)
238 		goto out_free_ahash;
239 
240 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
241 
242 	checksumlen = crypto_ahash_digestsize(tfm);
243 
244 	if (cksumkey != NULL) {
245 		err = crypto_ahash_setkey(tfm, cksumkey,
246 					  kctx->gk5e->keylength);
247 		if (err)
248 			goto out;
249 	}
250 
251 	err = crypto_ahash_init(req);
252 	if (err)
253 		goto out;
254 	sg_init_one(sg, header, hdrlen);
255 	ahash_request_set_crypt(req, sg, NULL, hdrlen);
256 	err = crypto_ahash_update(req);
257 	if (err)
258 		goto out;
259 	err = xdr_process_buf(body, body_offset, body->len - body_offset,
260 			      checksummer, req);
261 	if (err)
262 		goto out;
263 	ahash_request_set_crypt(req, NULL, checksumdata, 0);
264 	err = crypto_ahash_final(req);
265 	if (err)
266 		goto out;
267 
268 	switch (kctx->gk5e->ctype) {
269 	case CKSUMTYPE_RSA_MD5:
270 		err = krb5_encrypt(kctx->seq, NULL, checksumdata,
271 				   checksumdata, checksumlen);
272 		if (err)
273 			goto out;
274 		memcpy(cksumout->data,
275 		       checksumdata + checksumlen - kctx->gk5e->cksumlength,
276 		       kctx->gk5e->cksumlength);
277 		break;
278 	case CKSUMTYPE_HMAC_SHA1_DES3:
279 		memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
280 		break;
281 	default:
282 		BUG();
283 		break;
284 	}
285 	cksumout->len = kctx->gk5e->cksumlength;
286 out:
287 	ahash_request_free(req);
288 out_free_ahash:
289 	crypto_free_ahash(tfm);
290 out_free_cksum:
291 	kfree(checksumdata);
292 	return err ? GSS_S_FAILURE : 0;
293 }
294 
295 /**
296  * gss_krb5_checksum - Compute the MAC for a GSS Wrap or MIC token
297  * @tfm: an initialized hash transform
298  * @header: pointer to a buffer containing the token header, or NULL
299  * @hdrlen: number of octets in @header
300  * @body: xdr_buf containing an RPC message (body.len is the message length)
301  * @body_offset: byte offset into @body to start checksumming
302  * @cksumout: OUT: a buffer to be filled in with the computed HMAC
303  *
304  * Usually expressed as H = HMAC(K, message)[1..h] .
305  *
306  * Caller provides the truncation length of the output token (h) in
307  * cksumout.len.
308  *
309  * Return values:
310  *   %GSS_S_COMPLETE: Digest computed, @cksumout filled in
311  *   %GSS_S_FAILURE: Call failed
312  */
313 u32
314 gss_krb5_checksum(struct crypto_ahash *tfm, char *header, int hdrlen,
315 		  const struct xdr_buf *body, int body_offset,
316 		  struct xdr_netobj *cksumout)
317 {
318 	struct ahash_request *req;
319 	int err = -ENOMEM;
320 	u8 *checksumdata;
321 
322 	checksumdata = kmalloc(crypto_ahash_digestsize(tfm), GFP_KERNEL);
323 	if (!checksumdata)
324 		return GSS_S_FAILURE;
325 
326 	req = ahash_request_alloc(tfm, GFP_KERNEL);
327 	if (!req)
328 		goto out_free_cksum;
329 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
330 	err = crypto_ahash_init(req);
331 	if (err)
332 		goto out_free_ahash;
333 
334 	/*
335 	 * Per RFC 4121 Section 4.2.4, the checksum is performed over the
336 	 * data body first, then over the octets in "header".
337 	 */
338 	err = xdr_process_buf(body, body_offset, body->len - body_offset,
339 			      checksummer, req);
340 	if (err)
341 		goto out_free_ahash;
342 	if (header) {
343 		struct scatterlist sg[1];
344 
345 		sg_init_one(sg, header, hdrlen);
346 		ahash_request_set_crypt(req, sg, NULL, hdrlen);
347 		err = crypto_ahash_update(req);
348 		if (err)
349 			goto out_free_ahash;
350 	}
351 
352 	ahash_request_set_crypt(req, NULL, checksumdata, 0);
353 	err = crypto_ahash_final(req);
354 	if (err)
355 		goto out_free_ahash;
356 
357 	memcpy(cksumout->data, checksumdata,
358 	       min_t(int, cksumout->len, crypto_ahash_digestsize(tfm)));
359 
360 out_free_ahash:
361 	ahash_request_free(req);
362 out_free_cksum:
363 	kfree_sensitive(checksumdata);
364 	return err ? GSS_S_FAILURE : GSS_S_COMPLETE;
365 }
366 EXPORT_SYMBOL_IF_KUNIT(gss_krb5_checksum);
367 
368 struct encryptor_desc {
369 	u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
370 	struct skcipher_request *req;
371 	int pos;
372 	struct xdr_buf *outbuf;
373 	struct page **pages;
374 	struct scatterlist infrags[4];
375 	struct scatterlist outfrags[4];
376 	int fragno;
377 	int fraglen;
378 };
379 
380 static int
381 encryptor(struct scatterlist *sg, void *data)
382 {
383 	struct encryptor_desc *desc = data;
384 	struct xdr_buf *outbuf = desc->outbuf;
385 	struct crypto_sync_skcipher *tfm =
386 		crypto_sync_skcipher_reqtfm(desc->req);
387 	struct page *in_page;
388 	int thislen = desc->fraglen + sg->length;
389 	int fraglen, ret;
390 	int page_pos;
391 
392 	/* Worst case is 4 fragments: head, end of page 1, start
393 	 * of page 2, tail.  Anything more is a bug. */
394 	BUG_ON(desc->fragno > 3);
395 
396 	page_pos = desc->pos - outbuf->head[0].iov_len;
397 	if (page_pos >= 0 && page_pos < outbuf->page_len) {
398 		/* pages are not in place: */
399 		int i = (page_pos + outbuf->page_base) >> PAGE_SHIFT;
400 		in_page = desc->pages[i];
401 	} else {
402 		in_page = sg_page(sg);
403 	}
404 	sg_set_page(&desc->infrags[desc->fragno], in_page, sg->length,
405 		    sg->offset);
406 	sg_set_page(&desc->outfrags[desc->fragno], sg_page(sg), sg->length,
407 		    sg->offset);
408 	desc->fragno++;
409 	desc->fraglen += sg->length;
410 	desc->pos += sg->length;
411 
412 	fraglen = thislen & (crypto_sync_skcipher_blocksize(tfm) - 1);
413 	thislen -= fraglen;
414 
415 	if (thislen == 0)
416 		return 0;
417 
418 	sg_mark_end(&desc->infrags[desc->fragno - 1]);
419 	sg_mark_end(&desc->outfrags[desc->fragno - 1]);
420 
421 	skcipher_request_set_crypt(desc->req, desc->infrags, desc->outfrags,
422 				   thislen, desc->iv);
423 
424 	ret = crypto_skcipher_encrypt(desc->req);
425 	if (ret)
426 		return ret;
427 
428 	sg_init_table(desc->infrags, 4);
429 	sg_init_table(desc->outfrags, 4);
430 
431 	if (fraglen) {
432 		sg_set_page(&desc->outfrags[0], sg_page(sg), fraglen,
433 				sg->offset + sg->length - fraglen);
434 		desc->infrags[0] = desc->outfrags[0];
435 		sg_assign_page(&desc->infrags[0], in_page);
436 		desc->fragno = 1;
437 		desc->fraglen = fraglen;
438 	} else {
439 		desc->fragno = 0;
440 		desc->fraglen = 0;
441 	}
442 	return 0;
443 }
444 
445 int
446 gss_encrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *buf,
447 		    int offset, struct page **pages)
448 {
449 	int ret;
450 	struct encryptor_desc desc;
451 	SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
452 
453 	BUG_ON((buf->len - offset) % crypto_sync_skcipher_blocksize(tfm) != 0);
454 
455 	skcipher_request_set_sync_tfm(req, tfm);
456 	skcipher_request_set_callback(req, 0, NULL, NULL);
457 
458 	memset(desc.iv, 0, sizeof(desc.iv));
459 	desc.req = req;
460 	desc.pos = offset;
461 	desc.outbuf = buf;
462 	desc.pages = pages;
463 	desc.fragno = 0;
464 	desc.fraglen = 0;
465 
466 	sg_init_table(desc.infrags, 4);
467 	sg_init_table(desc.outfrags, 4);
468 
469 	ret = xdr_process_buf(buf, offset, buf->len - offset, encryptor, &desc);
470 	skcipher_request_zero(req);
471 	return ret;
472 }
473 
474 struct decryptor_desc {
475 	u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
476 	struct skcipher_request *req;
477 	struct scatterlist frags[4];
478 	int fragno;
479 	int fraglen;
480 };
481 
482 static int
483 decryptor(struct scatterlist *sg, void *data)
484 {
485 	struct decryptor_desc *desc = data;
486 	int thislen = desc->fraglen + sg->length;
487 	struct crypto_sync_skcipher *tfm =
488 		crypto_sync_skcipher_reqtfm(desc->req);
489 	int fraglen, ret;
490 
491 	/* Worst case is 4 fragments: head, end of page 1, start
492 	 * of page 2, tail.  Anything more is a bug. */
493 	BUG_ON(desc->fragno > 3);
494 	sg_set_page(&desc->frags[desc->fragno], sg_page(sg), sg->length,
495 		    sg->offset);
496 	desc->fragno++;
497 	desc->fraglen += sg->length;
498 
499 	fraglen = thislen & (crypto_sync_skcipher_blocksize(tfm) - 1);
500 	thislen -= fraglen;
501 
502 	if (thislen == 0)
503 		return 0;
504 
505 	sg_mark_end(&desc->frags[desc->fragno - 1]);
506 
507 	skcipher_request_set_crypt(desc->req, desc->frags, desc->frags,
508 				   thislen, desc->iv);
509 
510 	ret = crypto_skcipher_decrypt(desc->req);
511 	if (ret)
512 		return ret;
513 
514 	sg_init_table(desc->frags, 4);
515 
516 	if (fraglen) {
517 		sg_set_page(&desc->frags[0], sg_page(sg), fraglen,
518 				sg->offset + sg->length - fraglen);
519 		desc->fragno = 1;
520 		desc->fraglen = fraglen;
521 	} else {
522 		desc->fragno = 0;
523 		desc->fraglen = 0;
524 	}
525 	return 0;
526 }
527 
528 int
529 gss_decrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *buf,
530 		    int offset)
531 {
532 	int ret;
533 	struct decryptor_desc desc;
534 	SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
535 
536 	/* XXXJBF: */
537 	BUG_ON((buf->len - offset) % crypto_sync_skcipher_blocksize(tfm) != 0);
538 
539 	skcipher_request_set_sync_tfm(req, tfm);
540 	skcipher_request_set_callback(req, 0, NULL, NULL);
541 
542 	memset(desc.iv, 0, sizeof(desc.iv));
543 	desc.req = req;
544 	desc.fragno = 0;
545 	desc.fraglen = 0;
546 
547 	sg_init_table(desc.frags, 4);
548 
549 	ret = xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
550 	skcipher_request_zero(req);
551 	return ret;
552 }
553 
554 /*
555  * This function makes the assumption that it was ultimately called
556  * from gss_wrap().
557  *
558  * The client auth_gss code moves any existing tail data into a
559  * separate page before calling gss_wrap.
560  * The server svcauth_gss code ensures that both the head and the
561  * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
562  *
563  * Even with that guarantee, this function may be called more than
564  * once in the processing of gss_wrap().  The best we can do is
565  * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
566  * largest expected shift will fit within RPC_MAX_AUTH_SIZE.
567  * At run-time we can verify that a single invocation of this
568  * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
569  */
570 
571 int
572 xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
573 {
574 	u8 *p;
575 
576 	if (shiftlen == 0)
577 		return 0;
578 
579 	BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
580 
581 	p = buf->head[0].iov_base + base;
582 
583 	memmove(p + shiftlen, p, buf->head[0].iov_len - base);
584 
585 	buf->head[0].iov_len += shiftlen;
586 	buf->len += shiftlen;
587 
588 	return 0;
589 }
590 
591 static u32
592 gss_krb5_cts_crypt(struct crypto_sync_skcipher *cipher, struct xdr_buf *buf,
593 		   u32 offset, u8 *iv, struct page **pages, int encrypt)
594 {
595 	u32 ret;
596 	struct scatterlist sg[1];
597 	SYNC_SKCIPHER_REQUEST_ON_STACK(req, cipher);
598 	u8 *data;
599 	struct page **save_pages;
600 	u32 len = buf->len - offset;
601 
602 	if (len > GSS_KRB5_MAX_BLOCKSIZE * 2) {
603 		WARN_ON(0);
604 		return -ENOMEM;
605 	}
606 	data = kmalloc(GSS_KRB5_MAX_BLOCKSIZE * 2, GFP_KERNEL);
607 	if (!data)
608 		return -ENOMEM;
609 
610 	/*
611 	 * For encryption, we want to read from the cleartext
612 	 * page cache pages, and write the encrypted data to
613 	 * the supplied xdr_buf pages.
614 	 */
615 	save_pages = buf->pages;
616 	if (encrypt)
617 		buf->pages = pages;
618 
619 	ret = read_bytes_from_xdr_buf(buf, offset, data, len);
620 	buf->pages = save_pages;
621 	if (ret)
622 		goto out;
623 
624 	sg_init_one(sg, data, len);
625 
626 	skcipher_request_set_sync_tfm(req, cipher);
627 	skcipher_request_set_callback(req, 0, NULL, NULL);
628 	skcipher_request_set_crypt(req, sg, sg, len, iv);
629 
630 	if (encrypt)
631 		ret = crypto_skcipher_encrypt(req);
632 	else
633 		ret = crypto_skcipher_decrypt(req);
634 
635 	skcipher_request_zero(req);
636 
637 	if (ret)
638 		goto out;
639 
640 	ret = write_bytes_to_xdr_buf(buf, offset, data, len);
641 
642 #if IS_ENABLED(CONFIG_KUNIT)
643 	/*
644 	 * CBC-CTS does not define an output IV but RFC 3962 defines it as the
645 	 * penultimate block of ciphertext, so copy that into the IV buffer
646 	 * before returning.
647 	 */
648 	if (encrypt)
649 		memcpy(iv, data, crypto_sync_skcipher_ivsize(cipher));
650 #endif
651 
652 out:
653 	kfree(data);
654 	return ret;
655 }
656 
657 /**
658  * krb5_cbc_cts_encrypt - encrypt in CBC mode with CTS
659  * @cts_tfm: CBC cipher with CTS
660  * @cbc_tfm: base CBC cipher
661  * @offset: starting byte offset for plaintext
662  * @buf: OUT: output buffer
663  * @pages: plaintext
664  * @iv: output CBC initialization vector, or NULL
665  * @ivsize: size of @iv, in octets
666  *
667  * To provide confidentiality, encrypt using cipher block chaining
668  * with ciphertext stealing. Message integrity is handled separately.
669  *
670  * Return values:
671  *   %0: encryption successful
672  *   negative errno: encryption could not be completed
673  */
674 VISIBLE_IF_KUNIT
675 int krb5_cbc_cts_encrypt(struct crypto_sync_skcipher *cts_tfm,
676 			 struct crypto_sync_skcipher *cbc_tfm,
677 			 u32 offset, struct xdr_buf *buf, struct page **pages,
678 			 u8 *iv, unsigned int ivsize)
679 {
680 	u32 blocksize, nbytes, nblocks, cbcbytes;
681 	struct encryptor_desc desc;
682 	int err;
683 
684 	blocksize = crypto_sync_skcipher_blocksize(cts_tfm);
685 	nbytes = buf->len - offset;
686 	nblocks = (nbytes + blocksize - 1) / blocksize;
687 	cbcbytes = 0;
688 	if (nblocks > 2)
689 		cbcbytes = (nblocks - 2) * blocksize;
690 
691 	memset(desc.iv, 0, sizeof(desc.iv));
692 
693 	/* Handle block-sized chunks of plaintext with CBC. */
694 	if (cbcbytes) {
695 		SYNC_SKCIPHER_REQUEST_ON_STACK(req, cbc_tfm);
696 
697 		desc.pos = offset;
698 		desc.fragno = 0;
699 		desc.fraglen = 0;
700 		desc.pages = pages;
701 		desc.outbuf = buf;
702 		desc.req = req;
703 
704 		skcipher_request_set_sync_tfm(req, cbc_tfm);
705 		skcipher_request_set_callback(req, 0, NULL, NULL);
706 
707 		sg_init_table(desc.infrags, 4);
708 		sg_init_table(desc.outfrags, 4);
709 
710 		err = xdr_process_buf(buf, offset, cbcbytes, encryptor, &desc);
711 		skcipher_request_zero(req);
712 		if (err)
713 			return err;
714 	}
715 
716 	/* Remaining plaintext is handled with CBC-CTS. */
717 	err = gss_krb5_cts_crypt(cts_tfm, buf, offset + cbcbytes,
718 				 desc.iv, pages, 1);
719 	if (err)
720 		return err;
721 
722 	if (unlikely(iv))
723 		memcpy(iv, desc.iv, ivsize);
724 	return 0;
725 }
726 EXPORT_SYMBOL_IF_KUNIT(krb5_cbc_cts_encrypt);
727 
728 /**
729  * krb5_cbc_cts_decrypt - decrypt in CBC mode with CTS
730  * @cts_tfm: CBC cipher with CTS
731  * @cbc_tfm: base CBC cipher
732  * @offset: starting byte offset for plaintext
733  * @buf: OUT: output buffer
734  *
735  * Return values:
736  *   %0: decryption successful
737  *   negative errno: decryption could not be completed
738  */
739 VISIBLE_IF_KUNIT
740 int krb5_cbc_cts_decrypt(struct crypto_sync_skcipher *cts_tfm,
741 			 struct crypto_sync_skcipher *cbc_tfm,
742 			 u32 offset, struct xdr_buf *buf)
743 {
744 	u32 blocksize, nblocks, cbcbytes;
745 	struct decryptor_desc desc;
746 	int err;
747 
748 	blocksize = crypto_sync_skcipher_blocksize(cts_tfm);
749 	nblocks = (buf->len + blocksize - 1) / blocksize;
750 	cbcbytes = 0;
751 	if (nblocks > 2)
752 		cbcbytes = (nblocks - 2) * blocksize;
753 
754 	memset(desc.iv, 0, sizeof(desc.iv));
755 
756 	/* Handle block-sized chunks of plaintext with CBC. */
757 	if (cbcbytes) {
758 		SYNC_SKCIPHER_REQUEST_ON_STACK(req, cbc_tfm);
759 
760 		desc.fragno = 0;
761 		desc.fraglen = 0;
762 		desc.req = req;
763 
764 		skcipher_request_set_sync_tfm(req, cbc_tfm);
765 		skcipher_request_set_callback(req, 0, NULL, NULL);
766 
767 		sg_init_table(desc.frags, 4);
768 
769 		err = xdr_process_buf(buf, 0, cbcbytes, decryptor, &desc);
770 		skcipher_request_zero(req);
771 		if (err)
772 			return err;
773 	}
774 
775 	/* Remaining plaintext is handled with CBC-CTS. */
776 	return gss_krb5_cts_crypt(cts_tfm, buf, cbcbytes, desc.iv, NULL, 0);
777 }
778 EXPORT_SYMBOL_IF_KUNIT(krb5_cbc_cts_decrypt);
779 
780 u32
781 gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
782 		     struct xdr_buf *buf, struct page **pages)
783 {
784 	u32 err;
785 	struct xdr_netobj hmac;
786 	u8 *ecptr;
787 	struct crypto_sync_skcipher *cipher, *aux_cipher;
788 	struct crypto_ahash *ahash;
789 	struct page **save_pages;
790 	unsigned int conflen;
791 
792 	if (kctx->initiate) {
793 		cipher = kctx->initiator_enc;
794 		aux_cipher = kctx->initiator_enc_aux;
795 		ahash = kctx->initiator_integ;
796 	} else {
797 		cipher = kctx->acceptor_enc;
798 		aux_cipher = kctx->acceptor_enc_aux;
799 		ahash = kctx->acceptor_integ;
800 	}
801 	conflen = crypto_sync_skcipher_blocksize(cipher);
802 
803 	/* hide the gss token header and insert the confounder */
804 	offset += GSS_KRB5_TOK_HDR_LEN;
805 	if (xdr_extend_head(buf, offset, conflen))
806 		return GSS_S_FAILURE;
807 	krb5_make_confounder(buf->head[0].iov_base + offset, conflen);
808 	offset -= GSS_KRB5_TOK_HDR_LEN;
809 
810 	if (buf->tail[0].iov_base != NULL) {
811 		ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
812 	} else {
813 		buf->tail[0].iov_base = buf->head[0].iov_base
814 							+ buf->head[0].iov_len;
815 		buf->tail[0].iov_len = 0;
816 		ecptr = buf->tail[0].iov_base;
817 	}
818 
819 	/* copy plaintext gss token header after filler (if any) */
820 	memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
821 	buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
822 	buf->len += GSS_KRB5_TOK_HDR_LEN;
823 
824 	hmac.len = kctx->gk5e->cksumlength;
825 	hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
826 
827 	/*
828 	 * When we are called, pages points to the real page cache
829 	 * data -- which we can't go and encrypt!  buf->pages points
830 	 * to scratch pages which we are going to send off to the
831 	 * client/server.  Swap in the plaintext pages to calculate
832 	 * the hmac.
833 	 */
834 	save_pages = buf->pages;
835 	buf->pages = pages;
836 
837 	err = gss_krb5_checksum(ahash, NULL, 0, buf,
838 				offset + GSS_KRB5_TOK_HDR_LEN, &hmac);
839 	buf->pages = save_pages;
840 	if (err)
841 		return GSS_S_FAILURE;
842 
843 	err = krb5_cbc_cts_encrypt(cipher, aux_cipher,
844 				   offset + GSS_KRB5_TOK_HDR_LEN,
845 				   buf, pages, NULL, 0);
846 	if (err)
847 		return GSS_S_FAILURE;
848 
849 	/* Now update buf to account for HMAC */
850 	buf->tail[0].iov_len += kctx->gk5e->cksumlength;
851 	buf->len += kctx->gk5e->cksumlength;
852 
853 	return GSS_S_COMPLETE;
854 }
855 
856 u32
857 gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
858 		     struct xdr_buf *buf, u32 *headskip, u32 *tailskip)
859 {
860 	struct crypto_sync_skcipher *cipher, *aux_cipher;
861 	struct crypto_ahash *ahash;
862 	struct xdr_netobj our_hmac_obj;
863 	u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
864 	u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
865 	struct xdr_buf subbuf;
866 	u32 ret = 0;
867 
868 	if (kctx->initiate) {
869 		cipher = kctx->acceptor_enc;
870 		aux_cipher = kctx->acceptor_enc_aux;
871 		ahash = kctx->acceptor_integ;
872 	} else {
873 		cipher = kctx->initiator_enc;
874 		aux_cipher = kctx->initiator_enc_aux;
875 		ahash = kctx->initiator_integ;
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 				    (len - offset - GSS_KRB5_TOK_HDR_LEN -
881 				     kctx->gk5e->cksumlength));
882 
883 	ret = krb5_cbc_cts_decrypt(cipher, aux_cipher, 0, &subbuf);
884 	if (ret)
885 		goto out_err;
886 
887 	our_hmac_obj.len = kctx->gk5e->cksumlength;
888 	our_hmac_obj.data = our_hmac;
889 	ret = gss_krb5_checksum(ahash, NULL, 0, &subbuf, 0, &our_hmac_obj);
890 	if (ret)
891 		goto out_err;
892 
893 	/* Get the packet's hmac value */
894 	ret = read_bytes_from_xdr_buf(buf, len - kctx->gk5e->cksumlength,
895 				      pkt_hmac, kctx->gk5e->cksumlength);
896 	if (ret)
897 		goto out_err;
898 
899 	if (crypto_memneq(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
900 		ret = GSS_S_BAD_SIG;
901 		goto out_err;
902 	}
903 	*headskip = crypto_sync_skcipher_blocksize(cipher);
904 	*tailskip = kctx->gk5e->cksumlength;
905 out_err:
906 	if (ret && ret != GSS_S_BAD_SIG)
907 		ret = GSS_S_FAILURE;
908 	return ret;
909 }
910 
911 /**
912  * krb5_etm_checksum - Compute a MAC for a GSS Wrap token
913  * @cipher: an initialized cipher transform
914  * @tfm: an initialized hash transform
915  * @body: xdr_buf containing an RPC message (body.len is the message length)
916  * @body_offset: byte offset into @body to start checksumming
917  * @cksumout: OUT: a buffer to be filled in with the computed HMAC
918  *
919  * Usually expressed as H = HMAC(K, IV | ciphertext)[1..h] .
920  *
921  * Caller provides the truncation length of the output token (h) in
922  * cksumout.len.
923  *
924  * Return values:
925  *   %GSS_S_COMPLETE: Digest computed, @cksumout filled in
926  *   %GSS_S_FAILURE: Call failed
927  */
928 VISIBLE_IF_KUNIT
929 u32 krb5_etm_checksum(struct crypto_sync_skcipher *cipher,
930 		      struct crypto_ahash *tfm, const struct xdr_buf *body,
931 		      int body_offset, struct xdr_netobj *cksumout)
932 {
933 	unsigned int ivsize = crypto_sync_skcipher_ivsize(cipher);
934 	struct ahash_request *req;
935 	struct scatterlist sg[1];
936 	u8 *iv, *checksumdata;
937 	int err = -ENOMEM;
938 
939 	checksumdata = kmalloc(crypto_ahash_digestsize(tfm), GFP_KERNEL);
940 	if (!checksumdata)
941 		return GSS_S_FAILURE;
942 	/* For RPCSEC, the "initial cipher state" is always all zeroes. */
943 	iv = kzalloc(ivsize, GFP_KERNEL);
944 	if (!iv)
945 		goto out_free_mem;
946 
947 	req = ahash_request_alloc(tfm, GFP_KERNEL);
948 	if (!req)
949 		goto out_free_mem;
950 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
951 	err = crypto_ahash_init(req);
952 	if (err)
953 		goto out_free_ahash;
954 
955 	sg_init_one(sg, iv, ivsize);
956 	ahash_request_set_crypt(req, sg, NULL, ivsize);
957 	err = crypto_ahash_update(req);
958 	if (err)
959 		goto out_free_ahash;
960 	err = xdr_process_buf(body, body_offset, body->len - body_offset,
961 			      checksummer, req);
962 	if (err)
963 		goto out_free_ahash;
964 
965 	ahash_request_set_crypt(req, NULL, checksumdata, 0);
966 	err = crypto_ahash_final(req);
967 	if (err)
968 		goto out_free_ahash;
969 	memcpy(cksumout->data, checksumdata, cksumout->len);
970 
971 out_free_ahash:
972 	ahash_request_free(req);
973 out_free_mem:
974 	kfree(iv);
975 	kfree_sensitive(checksumdata);
976 	return err ? GSS_S_FAILURE : GSS_S_COMPLETE;
977 }
978 EXPORT_SYMBOL_IF_KUNIT(krb5_etm_checksum);
979 
980 /**
981  * krb5_etm_encrypt - Encrypt using the RFC 8009 rules
982  * @kctx: Kerberos context
983  * @offset: starting offset of the payload, in bytes
984  * @buf: OUT: send buffer to contain the encrypted payload
985  * @pages: plaintext payload
986  *
987  * The main difference with aes_encrypt is that "The HMAC is
988  * calculated over the cipher state concatenated with the AES
989  * output, instead of being calculated over the confounder and
990  * plaintext.  This allows the message receiver to verify the
991  * integrity of the message before decrypting the message."
992  *
993  * RFC 8009 Section 5:
994  *
995  * encryption function: as follows, where E() is AES encryption in
996  * CBC-CS3 mode, and h is the size of truncated HMAC (128 bits or
997  * 192 bits as described above).
998  *
999  *    N = random value of length 128 bits (the AES block size)
1000  *    IV = cipher state
1001  *    C = E(Ke, N | plaintext, IV)
1002  *    H = HMAC(Ki, IV | C)
1003  *    ciphertext = C | H[1..h]
1004  *
1005  * This encryption formula provides AEAD EtM with key separation.
1006  *
1007  * Return values:
1008  *   %GSS_S_COMPLETE: Encryption successful
1009  *   %GSS_S_FAILURE: Encryption failed
1010  */
1011 u32
1012 krb5_etm_encrypt(struct krb5_ctx *kctx, u32 offset,
1013 		 struct xdr_buf *buf, struct page **pages)
1014 {
1015 	struct crypto_sync_skcipher *cipher, *aux_cipher;
1016 	struct crypto_ahash *ahash;
1017 	struct xdr_netobj hmac;
1018 	unsigned int conflen;
1019 	u8 *ecptr;
1020 	u32 err;
1021 
1022 	if (kctx->initiate) {
1023 		cipher = kctx->initiator_enc;
1024 		aux_cipher = kctx->initiator_enc_aux;
1025 		ahash = kctx->initiator_integ;
1026 	} else {
1027 		cipher = kctx->acceptor_enc;
1028 		aux_cipher = kctx->acceptor_enc_aux;
1029 		ahash = kctx->acceptor_integ;
1030 	}
1031 	conflen = crypto_sync_skcipher_blocksize(cipher);
1032 
1033 	offset += GSS_KRB5_TOK_HDR_LEN;
1034 	if (xdr_extend_head(buf, offset, conflen))
1035 		return GSS_S_FAILURE;
1036 	krb5_make_confounder(buf->head[0].iov_base + offset, conflen);
1037 	offset -= GSS_KRB5_TOK_HDR_LEN;
1038 
1039 	if (buf->tail[0].iov_base) {
1040 		ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
1041 	} else {
1042 		buf->tail[0].iov_base = buf->head[0].iov_base
1043 							+ buf->head[0].iov_len;
1044 		buf->tail[0].iov_len = 0;
1045 		ecptr = buf->tail[0].iov_base;
1046 	}
1047 
1048 	memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
1049 	buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
1050 	buf->len += GSS_KRB5_TOK_HDR_LEN;
1051 
1052 	err = krb5_cbc_cts_encrypt(cipher, aux_cipher,
1053 				   offset + GSS_KRB5_TOK_HDR_LEN,
1054 				   buf, pages, NULL, 0);
1055 	if (err)
1056 		return GSS_S_FAILURE;
1057 
1058 	hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
1059 	hmac.len = kctx->gk5e->cksumlength;
1060 	err = krb5_etm_checksum(cipher, ahash,
1061 				buf, offset + GSS_KRB5_TOK_HDR_LEN, &hmac);
1062 	if (err)
1063 		goto out_err;
1064 	buf->tail[0].iov_len += kctx->gk5e->cksumlength;
1065 	buf->len += kctx->gk5e->cksumlength;
1066 
1067 	return GSS_S_COMPLETE;
1068 
1069 out_err:
1070 	return GSS_S_FAILURE;
1071 }
1072 
1073 /**
1074  * krb5_etm_decrypt - Decrypt using the RFC 8009 rules
1075  * @kctx: Kerberos context
1076  * @offset: starting offset of the ciphertext, in bytes
1077  * @len:
1078  * @buf:
1079  * @headskip: OUT: the enctype's confounder length, in octets
1080  * @tailskip: OUT: the enctype's HMAC length, in octets
1081  *
1082  * RFC 8009 Section 5:
1083  *
1084  * decryption function: as follows, where D() is AES decryption in
1085  * CBC-CS3 mode, and h is the size of truncated HMAC.
1086  *
1087  *    (C, H) = ciphertext
1088  *        (Note: H is the last h bits of the ciphertext.)
1089  *    IV = cipher state
1090  *    if H != HMAC(Ki, IV | C)[1..h]
1091  *        stop, report error
1092  *    (N, P) = D(Ke, C, IV)
1093  *
1094  * Return values:
1095  *   %GSS_S_COMPLETE: Decryption successful
1096  *   %GSS_S_BAD_SIG: computed HMAC != received HMAC
1097  *   %GSS_S_FAILURE: Decryption failed
1098  */
1099 u32
1100 krb5_etm_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
1101 		 struct xdr_buf *buf, u32 *headskip, u32 *tailskip)
1102 {
1103 	struct crypto_sync_skcipher *cipher, *aux_cipher;
1104 	u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
1105 	u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
1106 	struct xdr_netobj our_hmac_obj;
1107 	struct crypto_ahash *ahash;
1108 	struct xdr_buf subbuf;
1109 	u32 ret = 0;
1110 
1111 	if (kctx->initiate) {
1112 		cipher = kctx->acceptor_enc;
1113 		aux_cipher = kctx->acceptor_enc_aux;
1114 		ahash = kctx->acceptor_integ;
1115 	} else {
1116 		cipher = kctx->initiator_enc;
1117 		aux_cipher = kctx->initiator_enc_aux;
1118 		ahash = kctx->initiator_integ;
1119 	}
1120 
1121 	/* Extract the ciphertext into @subbuf. */
1122 	xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
1123 			   (len - offset - GSS_KRB5_TOK_HDR_LEN -
1124 			    kctx->gk5e->cksumlength));
1125 
1126 	our_hmac_obj.data = our_hmac;
1127 	our_hmac_obj.len = kctx->gk5e->cksumlength;
1128 	ret = krb5_etm_checksum(cipher, ahash, &subbuf, 0, &our_hmac_obj);
1129 	if (ret)
1130 		goto out_err;
1131 	ret = read_bytes_from_xdr_buf(buf, len - kctx->gk5e->cksumlength,
1132 				      pkt_hmac, kctx->gk5e->cksumlength);
1133 	if (ret)
1134 		goto out_err;
1135 	if (crypto_memneq(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
1136 		ret = GSS_S_BAD_SIG;
1137 		goto out_err;
1138 	}
1139 
1140 	ret = krb5_cbc_cts_decrypt(cipher, aux_cipher, 0, &subbuf);
1141 	if (ret) {
1142 		ret = GSS_S_FAILURE;
1143 		goto out_err;
1144 	}
1145 
1146 	*headskip = crypto_sync_skcipher_blocksize(cipher);
1147 	*tailskip = kctx->gk5e->cksumlength;
1148 	return GSS_S_COMPLETE;
1149 
1150 out_err:
1151 	if (ret != GSS_S_BAD_SIG)
1152 		ret = GSS_S_FAILURE;
1153 	return ret;
1154 }
1155