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 <crypto/utils.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
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