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 */
krb5_make_confounder(u8 * p,int conflen)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
krb5_encrypt(struct crypto_sync_skcipher * tfm,void * iv,void * in,void * out,int length)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
krb5_decrypt(struct crypto_sync_skcipher * tfm,void * iv,void * in,void * out,int length)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
checksummer(struct scatterlist * sg,void * data)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
make_checksum(struct krb5_ctx * kctx,char * header,int hdrlen,struct xdr_buf * body,int body_offset,u8 * cksumkey,unsigned int usage,struct xdr_netobj * cksumout)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
gss_krb5_checksum(struct crypto_ahash * tfm,char * header,int hdrlen,const struct xdr_buf * body,int body_offset,struct xdr_netobj * cksumout)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 memcpy(cksumout->data, checksumdata, cksumout->len);
357
358 out_free_ahash:
359 ahash_request_free(req);
360 out_free_cksum:
361 kfree_sensitive(checksumdata);
362 return err ? GSS_S_FAILURE : GSS_S_COMPLETE;
363 }
364 EXPORT_SYMBOL_IF_KUNIT(gss_krb5_checksum);
365
366 struct encryptor_desc {
367 u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
368 struct skcipher_request *req;
369 int pos;
370 struct xdr_buf *outbuf;
371 struct page **pages;
372 struct scatterlist infrags[4];
373 struct scatterlist outfrags[4];
374 int fragno;
375 int fraglen;
376 };
377
378 static int
encryptor(struct scatterlist * sg,void * data)379 encryptor(struct scatterlist *sg, void *data)
380 {
381 struct encryptor_desc *desc = data;
382 struct xdr_buf *outbuf = desc->outbuf;
383 struct crypto_sync_skcipher *tfm =
384 crypto_sync_skcipher_reqtfm(desc->req);
385 struct page *in_page;
386 int thislen = desc->fraglen + sg->length;
387 int fraglen, ret;
388 int page_pos;
389
390 /* Worst case is 4 fragments: head, end of page 1, start
391 * of page 2, tail. Anything more is a bug. */
392 BUG_ON(desc->fragno > 3);
393
394 page_pos = desc->pos - outbuf->head[0].iov_len;
395 if (page_pos >= 0 && page_pos < outbuf->page_len) {
396 /* pages are not in place: */
397 int i = (page_pos + outbuf->page_base) >> PAGE_SHIFT;
398 in_page = desc->pages[i];
399 } else {
400 in_page = sg_page(sg);
401 }
402 sg_set_page(&desc->infrags[desc->fragno], in_page, sg->length,
403 sg->offset);
404 sg_set_page(&desc->outfrags[desc->fragno], sg_page(sg), sg->length,
405 sg->offset);
406 desc->fragno++;
407 desc->fraglen += sg->length;
408 desc->pos += sg->length;
409
410 fraglen = thislen & (crypto_sync_skcipher_blocksize(tfm) - 1);
411 thislen -= fraglen;
412
413 if (thislen == 0)
414 return 0;
415
416 sg_mark_end(&desc->infrags[desc->fragno - 1]);
417 sg_mark_end(&desc->outfrags[desc->fragno - 1]);
418
419 skcipher_request_set_crypt(desc->req, desc->infrags, desc->outfrags,
420 thislen, desc->iv);
421
422 ret = crypto_skcipher_encrypt(desc->req);
423 if (ret)
424 return ret;
425
426 sg_init_table(desc->infrags, 4);
427 sg_init_table(desc->outfrags, 4);
428
429 if (fraglen) {
430 sg_set_page(&desc->outfrags[0], sg_page(sg), fraglen,
431 sg->offset + sg->length - fraglen);
432 desc->infrags[0] = desc->outfrags[0];
433 sg_assign_page(&desc->infrags[0], in_page);
434 desc->fragno = 1;
435 desc->fraglen = fraglen;
436 } else {
437 desc->fragno = 0;
438 desc->fraglen = 0;
439 }
440 return 0;
441 }
442
443 int
gss_encrypt_xdr_buf(struct crypto_sync_skcipher * tfm,struct xdr_buf * buf,int offset,struct page ** pages)444 gss_encrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *buf,
445 int offset, struct page **pages)
446 {
447 int ret;
448 struct encryptor_desc desc;
449 SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
450
451 BUG_ON((buf->len - offset) % crypto_sync_skcipher_blocksize(tfm) != 0);
452
453 skcipher_request_set_sync_tfm(req, tfm);
454 skcipher_request_set_callback(req, 0, NULL, NULL);
455
456 memset(desc.iv, 0, sizeof(desc.iv));
457 desc.req = req;
458 desc.pos = offset;
459 desc.outbuf = buf;
460 desc.pages = pages;
461 desc.fragno = 0;
462 desc.fraglen = 0;
463
464 sg_init_table(desc.infrags, 4);
465 sg_init_table(desc.outfrags, 4);
466
467 ret = xdr_process_buf(buf, offset, buf->len - offset, encryptor, &desc);
468 skcipher_request_zero(req);
469 return ret;
470 }
471
472 struct decryptor_desc {
473 u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
474 struct skcipher_request *req;
475 struct scatterlist frags[4];
476 int fragno;
477 int fraglen;
478 };
479
480 static int
decryptor(struct scatterlist * sg,void * data)481 decryptor(struct scatterlist *sg, void *data)
482 {
483 struct decryptor_desc *desc = data;
484 int thislen = desc->fraglen + sg->length;
485 struct crypto_sync_skcipher *tfm =
486 crypto_sync_skcipher_reqtfm(desc->req);
487 int fraglen, ret;
488
489 /* Worst case is 4 fragments: head, end of page 1, start
490 * of page 2, tail. Anything more is a bug. */
491 BUG_ON(desc->fragno > 3);
492 sg_set_page(&desc->frags[desc->fragno], sg_page(sg), sg->length,
493 sg->offset);
494 desc->fragno++;
495 desc->fraglen += sg->length;
496
497 fraglen = thislen & (crypto_sync_skcipher_blocksize(tfm) - 1);
498 thislen -= fraglen;
499
500 if (thislen == 0)
501 return 0;
502
503 sg_mark_end(&desc->frags[desc->fragno - 1]);
504
505 skcipher_request_set_crypt(desc->req, desc->frags, desc->frags,
506 thislen, desc->iv);
507
508 ret = crypto_skcipher_decrypt(desc->req);
509 if (ret)
510 return ret;
511
512 sg_init_table(desc->frags, 4);
513
514 if (fraglen) {
515 sg_set_page(&desc->frags[0], sg_page(sg), fraglen,
516 sg->offset + sg->length - fraglen);
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
gss_decrypt_xdr_buf(struct crypto_sync_skcipher * tfm,struct xdr_buf * buf,int offset)527 gss_decrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *buf,
528 int offset)
529 {
530 int ret;
531 struct decryptor_desc desc;
532 SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
533
534 /* XXXJBF: */
535 BUG_ON((buf->len - offset) % crypto_sync_skcipher_blocksize(tfm) != 0);
536
537 skcipher_request_set_sync_tfm(req, tfm);
538 skcipher_request_set_callback(req, 0, NULL, NULL);
539
540 memset(desc.iv, 0, sizeof(desc.iv));
541 desc.req = req;
542 desc.fragno = 0;
543 desc.fraglen = 0;
544
545 sg_init_table(desc.frags, 4);
546
547 ret = xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
548 skcipher_request_zero(req);
549 return ret;
550 }
551
552 /*
553 * This function makes the assumption that it was ultimately called
554 * from gss_wrap().
555 *
556 * The client auth_gss code moves any existing tail data into a
557 * separate page before calling gss_wrap.
558 * The server svcauth_gss code ensures that both the head and the
559 * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
560 *
561 * Even with that guarantee, this function may be called more than
562 * once in the processing of gss_wrap(). The best we can do is
563 * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
564 * largest expected shift will fit within RPC_MAX_AUTH_SIZE.
565 * At run-time we can verify that a single invocation of this
566 * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
567 */
568
569 int
xdr_extend_head(struct xdr_buf * buf,unsigned int base,unsigned int shiftlen)570 xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
571 {
572 u8 *p;
573
574 if (shiftlen == 0)
575 return 0;
576
577 BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
578
579 p = buf->head[0].iov_base + base;
580
581 memmove(p + shiftlen, p, buf->head[0].iov_len - base);
582
583 buf->head[0].iov_len += shiftlen;
584 buf->len += shiftlen;
585
586 return 0;
587 }
588
589 static u32
gss_krb5_cts_crypt(struct crypto_sync_skcipher * cipher,struct xdr_buf * buf,u32 offset,u8 * iv,struct page ** pages,int encrypt)590 gss_krb5_cts_crypt(struct crypto_sync_skcipher *cipher, struct xdr_buf *buf,
591 u32 offset, u8 *iv, struct page **pages, int encrypt)
592 {
593 u32 ret;
594 struct scatterlist sg[1];
595 SYNC_SKCIPHER_REQUEST_ON_STACK(req, cipher);
596 u8 *data;
597 struct page **save_pages;
598 u32 len = buf->len - offset;
599
600 if (len > GSS_KRB5_MAX_BLOCKSIZE * 2) {
601 WARN_ON(0);
602 return -ENOMEM;
603 }
604 data = kmalloc(GSS_KRB5_MAX_BLOCKSIZE * 2, GFP_KERNEL);
605 if (!data)
606 return -ENOMEM;
607
608 /*
609 * For encryption, we want to read from the cleartext
610 * page cache pages, and write the encrypted data to
611 * the supplied xdr_buf pages.
612 */
613 save_pages = buf->pages;
614 if (encrypt)
615 buf->pages = pages;
616
617 ret = read_bytes_from_xdr_buf(buf, offset, data, len);
618 buf->pages = save_pages;
619 if (ret)
620 goto out;
621
622 sg_init_one(sg, data, len);
623
624 skcipher_request_set_sync_tfm(req, cipher);
625 skcipher_request_set_callback(req, 0, NULL, NULL);
626 skcipher_request_set_crypt(req, sg, sg, len, iv);
627
628 if (encrypt)
629 ret = crypto_skcipher_encrypt(req);
630 else
631 ret = crypto_skcipher_decrypt(req);
632
633 skcipher_request_zero(req);
634
635 if (ret)
636 goto out;
637
638 ret = write_bytes_to_xdr_buf(buf, offset, data, len);
639
640 out:
641 kfree(data);
642 return ret;
643 }
644
645 /**
646 * krb5_cbc_cts_encrypt - encrypt in CBC mode with CTS
647 * @cts_tfm: CBC cipher with CTS
648 * @cbc_tfm: base CBC cipher
649 * @offset: starting byte offset for plaintext
650 * @buf: OUT: output buffer
651 * @pages: plaintext
652 * @iv: output CBC initialization vector, or NULL
653 * @ivsize: size of @iv, in octets
654 *
655 * To provide confidentiality, encrypt using cipher block chaining
656 * with ciphertext stealing. Message integrity is handled separately.
657 *
658 * Return values:
659 * %0: encryption successful
660 * negative errno: encryption could not be completed
661 */
662 VISIBLE_IF_KUNIT
krb5_cbc_cts_encrypt(struct crypto_sync_skcipher * cts_tfm,struct crypto_sync_skcipher * cbc_tfm,u32 offset,struct xdr_buf * buf,struct page ** pages,u8 * iv,unsigned int ivsize)663 int krb5_cbc_cts_encrypt(struct crypto_sync_skcipher *cts_tfm,
664 struct crypto_sync_skcipher *cbc_tfm,
665 u32 offset, struct xdr_buf *buf, struct page **pages,
666 u8 *iv, unsigned int ivsize)
667 {
668 u32 blocksize, nbytes, nblocks, cbcbytes;
669 struct encryptor_desc desc;
670 int err;
671
672 blocksize = crypto_sync_skcipher_blocksize(cts_tfm);
673 nbytes = buf->len - offset;
674 nblocks = (nbytes + blocksize - 1) / blocksize;
675 cbcbytes = 0;
676 if (nblocks > 2)
677 cbcbytes = (nblocks - 2) * blocksize;
678
679 memset(desc.iv, 0, sizeof(desc.iv));
680
681 /* Handle block-sized chunks of plaintext with CBC. */
682 if (cbcbytes) {
683 SYNC_SKCIPHER_REQUEST_ON_STACK(req, cbc_tfm);
684
685 desc.pos = offset;
686 desc.fragno = 0;
687 desc.fraglen = 0;
688 desc.pages = pages;
689 desc.outbuf = buf;
690 desc.req = req;
691
692 skcipher_request_set_sync_tfm(req, cbc_tfm);
693 skcipher_request_set_callback(req, 0, NULL, NULL);
694
695 sg_init_table(desc.infrags, 4);
696 sg_init_table(desc.outfrags, 4);
697
698 err = xdr_process_buf(buf, offset, cbcbytes, encryptor, &desc);
699 skcipher_request_zero(req);
700 if (err)
701 return err;
702 }
703
704 /* Remaining plaintext is handled with CBC-CTS. */
705 err = gss_krb5_cts_crypt(cts_tfm, buf, offset + cbcbytes,
706 desc.iv, pages, 1);
707 if (err)
708 return err;
709
710 if (unlikely(iv))
711 memcpy(iv, desc.iv, ivsize);
712 return 0;
713 }
714 EXPORT_SYMBOL_IF_KUNIT(krb5_cbc_cts_encrypt);
715
716 /**
717 * krb5_cbc_cts_decrypt - decrypt in CBC mode with CTS
718 * @cts_tfm: CBC cipher with CTS
719 * @cbc_tfm: base CBC cipher
720 * @offset: starting byte offset for plaintext
721 * @buf: OUT: output buffer
722 *
723 * Return values:
724 * %0: decryption successful
725 * negative errno: decryption could not be completed
726 */
727 VISIBLE_IF_KUNIT
krb5_cbc_cts_decrypt(struct crypto_sync_skcipher * cts_tfm,struct crypto_sync_skcipher * cbc_tfm,u32 offset,struct xdr_buf * buf)728 int krb5_cbc_cts_decrypt(struct crypto_sync_skcipher *cts_tfm,
729 struct crypto_sync_skcipher *cbc_tfm,
730 u32 offset, struct xdr_buf *buf)
731 {
732 u32 blocksize, nblocks, cbcbytes;
733 struct decryptor_desc desc;
734 int err;
735
736 blocksize = crypto_sync_skcipher_blocksize(cts_tfm);
737 nblocks = (buf->len + blocksize - 1) / blocksize;
738 cbcbytes = 0;
739 if (nblocks > 2)
740 cbcbytes = (nblocks - 2) * blocksize;
741
742 memset(desc.iv, 0, sizeof(desc.iv));
743
744 /* Handle block-sized chunks of plaintext with CBC. */
745 if (cbcbytes) {
746 SYNC_SKCIPHER_REQUEST_ON_STACK(req, cbc_tfm);
747
748 desc.fragno = 0;
749 desc.fraglen = 0;
750 desc.req = req;
751
752 skcipher_request_set_sync_tfm(req, cbc_tfm);
753 skcipher_request_set_callback(req, 0, NULL, NULL);
754
755 sg_init_table(desc.frags, 4);
756
757 err = xdr_process_buf(buf, 0, cbcbytes, decryptor, &desc);
758 skcipher_request_zero(req);
759 if (err)
760 return err;
761 }
762
763 /* Remaining plaintext is handled with CBC-CTS. */
764 return gss_krb5_cts_crypt(cts_tfm, buf, cbcbytes, desc.iv, NULL, 0);
765 }
766 EXPORT_SYMBOL_IF_KUNIT(krb5_cbc_cts_decrypt);
767
768 u32
gss_krb5_aes_encrypt(struct krb5_ctx * kctx,u32 offset,struct xdr_buf * buf,struct page ** pages)769 gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
770 struct xdr_buf *buf, struct page **pages)
771 {
772 u32 err;
773 struct xdr_netobj hmac;
774 u8 *ecptr;
775 struct crypto_sync_skcipher *cipher, *aux_cipher;
776 struct crypto_ahash *ahash;
777 struct page **save_pages;
778 unsigned int conflen;
779
780 if (kctx->initiate) {
781 cipher = kctx->initiator_enc;
782 aux_cipher = kctx->initiator_enc_aux;
783 ahash = kctx->initiator_integ;
784 } else {
785 cipher = kctx->acceptor_enc;
786 aux_cipher = kctx->acceptor_enc_aux;
787 ahash = kctx->acceptor_integ;
788 }
789 conflen = crypto_sync_skcipher_blocksize(cipher);
790
791 /* hide the gss token header and insert the confounder */
792 offset += GSS_KRB5_TOK_HDR_LEN;
793 if (xdr_extend_head(buf, offset, conflen))
794 return GSS_S_FAILURE;
795 krb5_make_confounder(buf->head[0].iov_base + offset, conflen);
796 offset -= GSS_KRB5_TOK_HDR_LEN;
797
798 if (buf->tail[0].iov_base != NULL) {
799 ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
800 } else {
801 buf->tail[0].iov_base = buf->head[0].iov_base
802 + buf->head[0].iov_len;
803 buf->tail[0].iov_len = 0;
804 ecptr = buf->tail[0].iov_base;
805 }
806
807 /* copy plaintext gss token header after filler (if any) */
808 memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
809 buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
810 buf->len += GSS_KRB5_TOK_HDR_LEN;
811
812 /* Do the HMAC */
813 hmac.len = GSS_KRB5_MAX_CKSUM_LEN;
814 hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
815
816 /*
817 * When we are called, pages points to the real page cache
818 * data -- which we can't go and encrypt! buf->pages points
819 * to scratch pages which we are going to send off to the
820 * client/server. Swap in the plaintext pages to calculate
821 * the hmac.
822 */
823 save_pages = buf->pages;
824 buf->pages = pages;
825
826 err = gss_krb5_checksum(ahash, NULL, 0, buf,
827 offset + GSS_KRB5_TOK_HDR_LEN, &hmac);
828 buf->pages = save_pages;
829 if (err)
830 return GSS_S_FAILURE;
831
832 err = krb5_cbc_cts_encrypt(cipher, aux_cipher,
833 offset + GSS_KRB5_TOK_HDR_LEN,
834 buf, pages, NULL, 0);
835 if (err)
836 return GSS_S_FAILURE;
837
838 /* Now update buf to account for HMAC */
839 buf->tail[0].iov_len += kctx->gk5e->cksumlength;
840 buf->len += kctx->gk5e->cksumlength;
841
842 return GSS_S_COMPLETE;
843 }
844
845 u32
gss_krb5_aes_decrypt(struct krb5_ctx * kctx,u32 offset,u32 len,struct xdr_buf * buf,u32 * headskip,u32 * tailskip)846 gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
847 struct xdr_buf *buf, u32 *headskip, u32 *tailskip)
848 {
849 struct crypto_sync_skcipher *cipher, *aux_cipher;
850 struct crypto_ahash *ahash;
851 struct xdr_netobj our_hmac_obj;
852 u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
853 u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
854 struct xdr_buf subbuf;
855 u32 ret = 0;
856
857 if (kctx->initiate) {
858 cipher = kctx->acceptor_enc;
859 aux_cipher = kctx->acceptor_enc_aux;
860 ahash = kctx->acceptor_integ;
861 } else {
862 cipher = kctx->initiator_enc;
863 aux_cipher = kctx->initiator_enc_aux;
864 ahash = kctx->initiator_integ;
865 }
866
867 /* create a segment skipping the header and leaving out the checksum */
868 xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
869 (len - offset - GSS_KRB5_TOK_HDR_LEN -
870 kctx->gk5e->cksumlength));
871
872 ret = krb5_cbc_cts_decrypt(cipher, aux_cipher, 0, &subbuf);
873 if (ret)
874 goto out_err;
875
876 /* Calculate our hmac over the plaintext data */
877 our_hmac_obj.len = sizeof(our_hmac);
878 our_hmac_obj.data = our_hmac;
879 ret = gss_krb5_checksum(ahash, NULL, 0, &subbuf, 0, &our_hmac_obj);
880 if (ret)
881 goto out_err;
882
883 /* Get the packet's hmac value */
884 ret = read_bytes_from_xdr_buf(buf, len - kctx->gk5e->cksumlength,
885 pkt_hmac, kctx->gk5e->cksumlength);
886 if (ret)
887 goto out_err;
888
889 if (crypto_memneq(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
890 ret = GSS_S_BAD_SIG;
891 goto out_err;
892 }
893 *headskip = crypto_sync_skcipher_blocksize(cipher);
894 *tailskip = kctx->gk5e->cksumlength;
895 out_err:
896 if (ret && ret != GSS_S_BAD_SIG)
897 ret = GSS_S_FAILURE;
898 return ret;
899 }
900
901 /**
902 * krb5_etm_checksum - Compute a MAC for a GSS Wrap token
903 * @cipher: an initialized cipher transform
904 * @tfm: an initialized hash transform
905 * @body: xdr_buf containing an RPC message (body.len is the message length)
906 * @body_offset: byte offset into @body to start checksumming
907 * @cksumout: OUT: a buffer to be filled in with the computed HMAC
908 *
909 * Usually expressed as H = HMAC(K, IV | ciphertext)[1..h] .
910 *
911 * Caller provides the truncation length of the output token (h) in
912 * cksumout.len.
913 *
914 * Return values:
915 * %GSS_S_COMPLETE: Digest computed, @cksumout filled in
916 * %GSS_S_FAILURE: Call failed
917 */
918 VISIBLE_IF_KUNIT
krb5_etm_checksum(struct crypto_sync_skcipher * cipher,struct crypto_ahash * tfm,const struct xdr_buf * body,int body_offset,struct xdr_netobj * cksumout)919 u32 krb5_etm_checksum(struct crypto_sync_skcipher *cipher,
920 struct crypto_ahash *tfm, const struct xdr_buf *body,
921 int body_offset, struct xdr_netobj *cksumout)
922 {
923 unsigned int ivsize = crypto_sync_skcipher_ivsize(cipher);
924 struct ahash_request *req;
925 struct scatterlist sg[1];
926 u8 *iv, *checksumdata;
927 int err = -ENOMEM;
928
929 checksumdata = kmalloc(crypto_ahash_digestsize(tfm), GFP_KERNEL);
930 if (!checksumdata)
931 return GSS_S_FAILURE;
932 /* For RPCSEC, the "initial cipher state" is always all zeroes. */
933 iv = kzalloc(ivsize, GFP_KERNEL);
934 if (!iv)
935 goto out_free_mem;
936
937 req = ahash_request_alloc(tfm, GFP_KERNEL);
938 if (!req)
939 goto out_free_mem;
940 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
941 err = crypto_ahash_init(req);
942 if (err)
943 goto out_free_ahash;
944
945 sg_init_one(sg, iv, ivsize);
946 ahash_request_set_crypt(req, sg, NULL, ivsize);
947 err = crypto_ahash_update(req);
948 if (err)
949 goto out_free_ahash;
950 err = xdr_process_buf(body, body_offset, body->len - body_offset,
951 checksummer, req);
952 if (err)
953 goto out_free_ahash;
954
955 ahash_request_set_crypt(req, NULL, checksumdata, 0);
956 err = crypto_ahash_final(req);
957 if (err)
958 goto out_free_ahash;
959 memcpy(cksumout->data, checksumdata, cksumout->len);
960
961 out_free_ahash:
962 ahash_request_free(req);
963 out_free_mem:
964 kfree(iv);
965 kfree_sensitive(checksumdata);
966 return err ? GSS_S_FAILURE : GSS_S_COMPLETE;
967 }
968 EXPORT_SYMBOL_IF_KUNIT(krb5_etm_checksum);
969
970 /**
971 * krb5_etm_encrypt - Encrypt using the RFC 8009 rules
972 * @kctx: Kerberos context
973 * @offset: starting offset of the payload, in bytes
974 * @buf: OUT: send buffer to contain the encrypted payload
975 * @pages: plaintext payload
976 *
977 * The main difference with aes_encrypt is that "The HMAC is
978 * calculated over the cipher state concatenated with the AES
979 * output, instead of being calculated over the confounder and
980 * plaintext. This allows the message receiver to verify the
981 * integrity of the message before decrypting the message."
982 *
983 * RFC 8009 Section 5:
984 *
985 * encryption function: as follows, where E() is AES encryption in
986 * CBC-CS3 mode, and h is the size of truncated HMAC (128 bits or
987 * 192 bits as described above).
988 *
989 * N = random value of length 128 bits (the AES block size)
990 * IV = cipher state
991 * C = E(Ke, N | plaintext, IV)
992 * H = HMAC(Ki, IV | C)
993 * ciphertext = C | H[1..h]
994 *
995 * This encryption formula provides AEAD EtM with key separation.
996 *
997 * Return values:
998 * %GSS_S_COMPLETE: Encryption successful
999 * %GSS_S_FAILURE: Encryption failed
1000 */
1001 u32
krb5_etm_encrypt(struct krb5_ctx * kctx,u32 offset,struct xdr_buf * buf,struct page ** pages)1002 krb5_etm_encrypt(struct krb5_ctx *kctx, u32 offset,
1003 struct xdr_buf *buf, struct page **pages)
1004 {
1005 struct crypto_sync_skcipher *cipher, *aux_cipher;
1006 struct crypto_ahash *ahash;
1007 struct xdr_netobj hmac;
1008 unsigned int conflen;
1009 u8 *ecptr;
1010 u32 err;
1011
1012 if (kctx->initiate) {
1013 cipher = kctx->initiator_enc;
1014 aux_cipher = kctx->initiator_enc_aux;
1015 ahash = kctx->initiator_integ;
1016 } else {
1017 cipher = kctx->acceptor_enc;
1018 aux_cipher = kctx->acceptor_enc_aux;
1019 ahash = kctx->acceptor_integ;
1020 }
1021 conflen = crypto_sync_skcipher_blocksize(cipher);
1022
1023 offset += GSS_KRB5_TOK_HDR_LEN;
1024 if (xdr_extend_head(buf, offset, conflen))
1025 return GSS_S_FAILURE;
1026 krb5_make_confounder(buf->head[0].iov_base + offset, conflen);
1027 offset -= GSS_KRB5_TOK_HDR_LEN;
1028
1029 if (buf->tail[0].iov_base) {
1030 ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
1031 } else {
1032 buf->tail[0].iov_base = buf->head[0].iov_base
1033 + buf->head[0].iov_len;
1034 buf->tail[0].iov_len = 0;
1035 ecptr = buf->tail[0].iov_base;
1036 }
1037
1038 memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
1039 buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
1040 buf->len += GSS_KRB5_TOK_HDR_LEN;
1041
1042 err = krb5_cbc_cts_encrypt(cipher, aux_cipher,
1043 offset + GSS_KRB5_TOK_HDR_LEN,
1044 buf, pages, NULL, 0);
1045 if (err)
1046 return GSS_S_FAILURE;
1047
1048 hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
1049 hmac.len = kctx->gk5e->cksumlength;
1050 err = krb5_etm_checksum(cipher, ahash,
1051 buf, offset + GSS_KRB5_TOK_HDR_LEN, &hmac);
1052 if (err)
1053 goto out_err;
1054 buf->tail[0].iov_len += kctx->gk5e->cksumlength;
1055 buf->len += kctx->gk5e->cksumlength;
1056
1057 return GSS_S_COMPLETE;
1058
1059 out_err:
1060 return GSS_S_FAILURE;
1061 }
1062
1063 /**
1064 * krb5_etm_decrypt - Decrypt using the RFC 8009 rules
1065 * @kctx: Kerberos context
1066 * @offset: starting offset of the ciphertext, in bytes
1067 * @len:
1068 * @buf:
1069 * @headskip: OUT: the enctype's confounder length, in octets
1070 * @tailskip: OUT: the enctype's HMAC length, in octets
1071 *
1072 * RFC 8009 Section 5:
1073 *
1074 * decryption function: as follows, where D() is AES decryption in
1075 * CBC-CS3 mode, and h is the size of truncated HMAC.
1076 *
1077 * (C, H) = ciphertext
1078 * (Note: H is the last h bits of the ciphertext.)
1079 * IV = cipher state
1080 * if H != HMAC(Ki, IV | C)[1..h]
1081 * stop, report error
1082 * (N, P) = D(Ke, C, IV)
1083 *
1084 * Return values:
1085 * %GSS_S_COMPLETE: Decryption successful
1086 * %GSS_S_BAD_SIG: computed HMAC != received HMAC
1087 * %GSS_S_FAILURE: Decryption failed
1088 */
1089 u32
krb5_etm_decrypt(struct krb5_ctx * kctx,u32 offset,u32 len,struct xdr_buf * buf,u32 * headskip,u32 * tailskip)1090 krb5_etm_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
1091 struct xdr_buf *buf, u32 *headskip, u32 *tailskip)
1092 {
1093 struct crypto_sync_skcipher *cipher, *aux_cipher;
1094 u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
1095 u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
1096 struct xdr_netobj our_hmac_obj;
1097 struct crypto_ahash *ahash;
1098 struct xdr_buf subbuf;
1099 u32 ret = 0;
1100
1101 if (kctx->initiate) {
1102 cipher = kctx->acceptor_enc;
1103 aux_cipher = kctx->acceptor_enc_aux;
1104 ahash = kctx->acceptor_integ;
1105 } else {
1106 cipher = kctx->initiator_enc;
1107 aux_cipher = kctx->initiator_enc_aux;
1108 ahash = kctx->initiator_integ;
1109 }
1110
1111 /* Extract the ciphertext into @subbuf. */
1112 xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
1113 (len - offset - GSS_KRB5_TOK_HDR_LEN -
1114 kctx->gk5e->cksumlength));
1115
1116 our_hmac_obj.data = our_hmac;
1117 our_hmac_obj.len = kctx->gk5e->cksumlength;
1118 ret = krb5_etm_checksum(cipher, ahash, &subbuf, 0, &our_hmac_obj);
1119 if (ret)
1120 goto out_err;
1121 ret = read_bytes_from_xdr_buf(buf, len - kctx->gk5e->cksumlength,
1122 pkt_hmac, kctx->gk5e->cksumlength);
1123 if (ret)
1124 goto out_err;
1125 if (crypto_memneq(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
1126 ret = GSS_S_BAD_SIG;
1127 goto out_err;
1128 }
1129
1130 ret = krb5_cbc_cts_decrypt(cipher, aux_cipher, 0, &subbuf);
1131 if (ret) {
1132 ret = GSS_S_FAILURE;
1133 goto out_err;
1134 }
1135
1136 *headskip = crypto_sync_skcipher_blocksize(cipher);
1137 *tailskip = kctx->gk5e->cksumlength;
1138 return GSS_S_COMPLETE;
1139
1140 out_err:
1141 if (ret != GSS_S_BAD_SIG)
1142 ret = GSS_S_FAILURE;
1143 return ret;
1144 }
1145