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1/*
2 * COPYRIGHT (c) 2008
3 * The Regents of the University of Michigan
4 * ALL RIGHTS RESERVED
5 *
6 * Permission is granted to use, copy, create derivative works
7 * and redistribute this software and such derivative works
8 * for any purpose, so long as the name of The University of
9 * Michigan is not used in any advertising or publicity
10 * pertaining to the use of distribution of this software
11 * without specific, written prior authorization. If the
12 * above copyright notice or any other identification of the
13 * University of Michigan is included in any copy of any
14 * portion of this software, then the disclaimer below must
15 * also be included.
16 *
17 * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION
18 * FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY
19 * PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF
20 * MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
21 * WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
22 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
23 * REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE
24 * FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR
25 * CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING
26 * OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
27 * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGES.
29 */
30
31#include <crypto/skcipher.h>
32#include <linux/types.h>
33#include <linux/jiffies.h>
34#include <linux/sunrpc/gss_krb5.h>
35#include <linux/random.h>
36#include <linux/pagemap.h>
37
38#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
39# define RPCDBG_FACILITY RPCDBG_AUTH
40#endif
41
42static inline int
43gss_krb5_padding(int blocksize, int length)
44{
45 return blocksize - (length % blocksize);
46}
47
48static inline void
49gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize)
50{
51 int padding = gss_krb5_padding(blocksize, buf->len - offset);
52 char *p;
53 struct kvec *iov;
54
55 if (buf->page_len || buf->tail[0].iov_len)
56 iov = &buf->tail[0];
57 else
58 iov = &buf->head[0];
59 p = iov->iov_base + iov->iov_len;
60 iov->iov_len += padding;
61 buf->len += padding;
62 memset(p, padding, padding);
63}
64
65static inline int
66gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize)
67{
68 u8 *ptr;
69 u8 pad;
70 size_t len = buf->len;
71
72 if (len <= buf->head[0].iov_len) {
73 pad = *(u8 *)(buf->head[0].iov_base + len - 1);
74 if (pad > buf->head[0].iov_len)
75 return -EINVAL;
76 buf->head[0].iov_len -= pad;
77 goto out;
78 } else
79 len -= buf->head[0].iov_len;
80 if (len <= buf->page_len) {
81 unsigned int last = (buf->page_base + len - 1)
82 >>PAGE_SHIFT;
83 unsigned int offset = (buf->page_base + len - 1)
84 & (PAGE_SIZE - 1);
85 ptr = kmap_atomic(buf->pages[last]);
86 pad = *(ptr + offset);
87 kunmap_atomic(ptr);
88 goto out;
89 } else
90 len -= buf->page_len;
91 BUG_ON(len > buf->tail[0].iov_len);
92 pad = *(u8 *)(buf->tail[0].iov_base + len - 1);
93out:
94 /* XXX: NOTE: we do not adjust the page lengths--they represent
95 * a range of data in the real filesystem page cache, and we need
96 * to know that range so the xdr code can properly place read data.
97 * However adjusting the head length, as we do above, is harmless.
98 * In the case of a request that fits into a single page, the server
99 * also uses length and head length together to determine the original
100 * start of the request to copy the request for deferal; so it's
101 * easier on the server if we adjust head and tail length in tandem.
102 * It's not really a problem that we don't fool with the page and
103 * tail lengths, though--at worst badly formed xdr might lead the
104 * server to attempt to parse the padding.
105 * XXX: Document all these weird requirements for gss mechanism
106 * wrap/unwrap functions. */
107 if (pad > blocksize)
108 return -EINVAL;
109 if (buf->len > pad)
110 buf->len -= pad;
111 else
112 return -EINVAL;
113 return 0;
114}
115
116void
117gss_krb5_make_confounder(char *p, u32 conflen)
118{
119 static u64 i = 0;
120 u64 *q = (u64 *)p;
121
122 /* rfc1964 claims this should be "random". But all that's really
123 * necessary is that it be unique. And not even that is necessary in
124 * our case since our "gssapi" implementation exists only to support
125 * rpcsec_gss, so we know that the only buffers we will ever encrypt
126 * already begin with a unique sequence number. Just to hedge my bets
127 * I'll make a half-hearted attempt at something unique, but ensuring
128 * uniqueness would mean worrying about atomicity and rollover, and I
129 * don't care enough. */
130
131 /* initialize to random value */
132 if (i == 0) {
133 i = get_random_u32();
134 i = (i << 32) | get_random_u32();
135 }
136
137 switch (conflen) {
138 case 16:
139 *q++ = i++;
140 fallthrough;
141 case 8:
142 *q++ = i++;
143 break;
144 default:
145 BUG();
146 }
147}
148
149/* Assumptions: the head and tail of inbuf are ours to play with.
150 * The pages, however, may be real pages in the page cache and we replace
151 * them with scratch pages from **pages before writing to them. */
152/* XXX: obviously the above should be documentation of wrap interface,
153 * and shouldn't be in this kerberos-specific file. */
154
155/* XXX factor out common code with seal/unseal. */
156
157static u32
158gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
159 struct xdr_buf *buf, struct page **pages)
160{
161 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
162 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata),
163 .data = cksumdata};
164 int blocksize = 0, plainlen;
165 unsigned char *ptr, *msg_start;
166 time64_t now;
167 int headlen;
168 struct page **tmp_pages;
169 u32 seq_send;
170 u8 *cksumkey;
171 u32 conflen = kctx->gk5e->conflen;
172
173 dprintk("RPC: %s\n", __func__);
174
175 now = ktime_get_real_seconds();
176
177 blocksize = crypto_sync_skcipher_blocksize(kctx->enc);
178 gss_krb5_add_padding(buf, offset, blocksize);
179 BUG_ON((buf->len - offset) % blocksize);
180 plainlen = conflen + buf->len - offset;
181
182 headlen = g_token_size(&kctx->mech_used,
183 GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen) -
184 (buf->len - offset);
185
186 ptr = buf->head[0].iov_base + offset;
187 /* shift data to make room for header. */
188 xdr_extend_head(buf, offset, headlen);
189
190 /* XXX Would be cleverer to encrypt while copying. */
191 BUG_ON((buf->len - offset - headlen) % blocksize);
192
193 g_make_token_header(&kctx->mech_used,
194 GSS_KRB5_TOK_HDR_LEN +
195 kctx->gk5e->cksumlength + plainlen, &ptr);
196
197
198 /* ptr now at header described in rfc 1964, section 1.2.1: */
199 ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff);
200 ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff);
201
202 msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength;
203
204 /*
205 * signalg and sealalg are stored as if they were converted from LE
206 * to host endian, even though they're opaque pairs of bytes according
207 * to the RFC.
208 */
209 *(__le16 *)(ptr + 2) = cpu_to_le16(kctx->gk5e->signalg);
210 *(__le16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg);
211 ptr[6] = 0xff;
212 ptr[7] = 0xff;
213
214 gss_krb5_make_confounder(msg_start, conflen);
215
216 if (kctx->gk5e->keyed_cksum)
217 cksumkey = kctx->cksum;
218 else
219 cksumkey = NULL;
220
221 /* XXXJBF: UGH!: */
222 tmp_pages = buf->pages;
223 buf->pages = pages;
224 if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen,
225 cksumkey, KG_USAGE_SEAL, &md5cksum))
226 return GSS_S_FAILURE;
227 buf->pages = tmp_pages;
228
229 memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
230
231 seq_send = atomic_fetch_inc(&kctx->seq_send);
232
233 /* XXX would probably be more efficient to compute checksum
234 * and encrypt at the same time: */
235 if ((krb5_make_seq_num(kctx, kctx->seq, kctx->initiate ? 0 : 0xff,
236 seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
237 return GSS_S_FAILURE;
238
239 if (gss_encrypt_xdr_buf(kctx->enc, buf,
240 offset + headlen - conflen, pages))
241 return GSS_S_FAILURE;
242
243 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
244}
245
246static u32
247gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len,
248 struct xdr_buf *buf, unsigned int *slack,
249 unsigned int *align)
250{
251 int signalg;
252 int sealalg;
253 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
254 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata),
255 .data = cksumdata};
256 time64_t now;
257 int direction;
258 s32 seqnum;
259 unsigned char *ptr;
260 int bodysize;
261 void *data_start, *orig_start;
262 int data_len;
263 int blocksize;
264 u32 conflen = kctx->gk5e->conflen;
265 int crypt_offset;
266 u8 *cksumkey;
267 unsigned int saved_len = buf->len;
268
269 dprintk("RPC: gss_unwrap_kerberos\n");
270
271 ptr = (u8 *)buf->head[0].iov_base + offset;
272 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
273 len - offset))
274 return GSS_S_DEFECTIVE_TOKEN;
275
276 if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
277 (ptr[1] != (KG_TOK_WRAP_MSG & 0xff)))
278 return GSS_S_DEFECTIVE_TOKEN;
279
280 /* XXX sanity-check bodysize?? */
281
282 /* get the sign and seal algorithms */
283
284 signalg = ptr[2] + (ptr[3] << 8);
285 if (signalg != kctx->gk5e->signalg)
286 return GSS_S_DEFECTIVE_TOKEN;
287
288 sealalg = ptr[4] + (ptr[5] << 8);
289 if (sealalg != kctx->gk5e->sealalg)
290 return GSS_S_DEFECTIVE_TOKEN;
291
292 if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
293 return GSS_S_DEFECTIVE_TOKEN;
294
295 /*
296 * Data starts after token header and checksum. ptr points
297 * to the beginning of the token header
298 */
299 crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) -
300 (unsigned char *)buf->head[0].iov_base;
301
302 buf->len = len;
303 if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
304 return GSS_S_DEFECTIVE_TOKEN;
305
306 if (kctx->gk5e->keyed_cksum)
307 cksumkey = kctx->cksum;
308 else
309 cksumkey = NULL;
310
311 if (make_checksum(kctx, ptr, 8, buf, crypt_offset,
312 cksumkey, KG_USAGE_SEAL, &md5cksum))
313 return GSS_S_FAILURE;
314
315 if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
316 kctx->gk5e->cksumlength))
317 return GSS_S_BAD_SIG;
318
319 /* it got through unscathed. Make sure the context is unexpired */
320
321 now = ktime_get_real_seconds();
322
323 if (now > kctx->endtime)
324 return GSS_S_CONTEXT_EXPIRED;
325
326 /* do sequencing checks */
327
328 if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
329 ptr + 8, &direction, &seqnum))
330 return GSS_S_BAD_SIG;
331
332 if ((kctx->initiate && direction != 0xff) ||
333 (!kctx->initiate && direction != 0))
334 return GSS_S_BAD_SIG;
335
336 /* Copy the data back to the right position. XXX: Would probably be
337 * better to copy and encrypt at the same time. */
338
339 blocksize = crypto_sync_skcipher_blocksize(kctx->enc);
340 data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) +
341 conflen;
342 orig_start = buf->head[0].iov_base + offset;
343 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
344 memmove(orig_start, data_start, data_len);
345 buf->head[0].iov_len -= (data_start - orig_start);
346 buf->len = len - (data_start - orig_start);
347
348 if (gss_krb5_remove_padding(buf, blocksize))
349 return GSS_S_DEFECTIVE_TOKEN;
350
351 /* slack must include room for krb5 padding */
352 *slack = XDR_QUADLEN(saved_len - buf->len);
353 /* The GSS blob always precedes the RPC message payload */
354 *align = *slack;
355 return GSS_S_COMPLETE;
356}
357
358/*
359 * We can shift data by up to LOCAL_BUF_LEN bytes in a pass. If we need
360 * to do more than that, we shift repeatedly. Kevin Coffman reports
361 * seeing 28 bytes as the value used by Microsoft clients and servers
362 * with AES, so this constant is chosen to allow handling 28 in one pass
363 * without using too much stack space.
364 *
365 * If that proves to a problem perhaps we could use a more clever
366 * algorithm.
367 */
368#define LOCAL_BUF_LEN 32u
369
370static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift)
371{
372 char head[LOCAL_BUF_LEN];
373 char tmp[LOCAL_BUF_LEN];
374 unsigned int this_len, i;
375
376 BUG_ON(shift > LOCAL_BUF_LEN);
377
378 read_bytes_from_xdr_buf(buf, 0, head, shift);
379 for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) {
380 this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift));
381 read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len);
382 write_bytes_to_xdr_buf(buf, i, tmp, this_len);
383 }
384 write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift);
385}
386
387static void _rotate_left(struct xdr_buf *buf, unsigned int shift)
388{
389 int shifted = 0;
390 int this_shift;
391
392 shift %= buf->len;
393 while (shifted < shift) {
394 this_shift = min(shift - shifted, LOCAL_BUF_LEN);
395 rotate_buf_a_little(buf, this_shift);
396 shifted += this_shift;
397 }
398}
399
400static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift)
401{
402 struct xdr_buf subbuf;
403
404 xdr_buf_subsegment(buf, &subbuf, base, buf->len - base);
405 _rotate_left(&subbuf, shift);
406}
407
408static u32
409gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
410 struct xdr_buf *buf, struct page **pages)
411{
412 u8 *ptr;
413 time64_t now;
414 u8 flags = 0x00;
415 __be16 *be16ptr;
416 __be64 *be64ptr;
417 u32 err;
418
419 dprintk("RPC: %s\n", __func__);
420
421 if (kctx->gk5e->encrypt_v2 == NULL)
422 return GSS_S_FAILURE;
423
424 /* make room for gss token header */
425 if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN))
426 return GSS_S_FAILURE;
427
428 /* construct gss token header */
429 ptr = buf->head[0].iov_base + offset;
430 *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff);
431 *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff);
432
433 if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
434 flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR;
435 if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0)
436 flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY;
437 /* We always do confidentiality in wrap tokens */
438 flags |= KG2_TOKEN_FLAG_SEALED;
439
440 *ptr++ = flags;
441 *ptr++ = 0xff;
442 be16ptr = (__be16 *)ptr;
443
444 *be16ptr++ = 0;
445 /* "inner" token header always uses 0 for RRC */
446 *be16ptr++ = 0;
447
448 be64ptr = (__be64 *)be16ptr;
449 *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64));
450
451 err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, pages);
452 if (err)
453 return err;
454
455 now = ktime_get_real_seconds();
456 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
457}
458
459static u32
460gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len,
461 struct xdr_buf *buf, unsigned int *slack,
462 unsigned int *align)
463{
464 time64_t now;
465 u8 *ptr;
466 u8 flags = 0x00;
467 u16 ec, rrc;
468 int err;
469 u32 headskip, tailskip;
470 u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN];
471 unsigned int movelen;
472
473
474 dprintk("RPC: %s\n", __func__);
475
476 if (kctx->gk5e->decrypt_v2 == NULL)
477 return GSS_S_FAILURE;
478
479 ptr = buf->head[0].iov_base + offset;
480
481 if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP)
482 return GSS_S_DEFECTIVE_TOKEN;
483
484 flags = ptr[2];
485 if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
486 (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
487 return GSS_S_BAD_SIG;
488
489 if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) {
490 dprintk("%s: token missing expected sealed flag\n", __func__);
491 return GSS_S_DEFECTIVE_TOKEN;
492 }
493
494 if (ptr[3] != 0xff)
495 return GSS_S_DEFECTIVE_TOKEN;
496
497 ec = be16_to_cpup((__be16 *)(ptr + 4));
498 rrc = be16_to_cpup((__be16 *)(ptr + 6));
499
500 /*
501 * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
502 * doesn't want it checked; see page 6 of rfc 2203.
503 */
504
505 if (rrc != 0)
506 rotate_left(offset + 16, buf, rrc);
507
508 err = (*kctx->gk5e->decrypt_v2)(kctx, offset, len, buf,
509 &headskip, &tailskip);
510 if (err)
511 return GSS_S_FAILURE;
512
513 /*
514 * Retrieve the decrypted gss token header and verify
515 * it against the original
516 */
517 err = read_bytes_from_xdr_buf(buf,
518 len - GSS_KRB5_TOK_HDR_LEN - tailskip,
519 decrypted_hdr, GSS_KRB5_TOK_HDR_LEN);
520 if (err) {
521 dprintk("%s: error %u getting decrypted_hdr\n", __func__, err);
522 return GSS_S_FAILURE;
523 }
524 if (memcmp(ptr, decrypted_hdr, 6)
525 || memcmp(ptr + 8, decrypted_hdr + 8, 8)) {
526 dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__);
527 return GSS_S_FAILURE;
528 }
529
530 /* do sequencing checks */
531
532 /* it got through unscathed. Make sure the context is unexpired */
533 now = ktime_get_real_seconds();
534 if (now > kctx->endtime)
535 return GSS_S_CONTEXT_EXPIRED;
536
537 /*
538 * Move the head data back to the right position in xdr_buf.
539 * We ignore any "ec" data since it might be in the head or
540 * the tail, and we really don't need to deal with it.
541 * Note that buf->head[0].iov_len may indicate the available
542 * head buffer space rather than that actually occupied.
543 */
544 movelen = min_t(unsigned int, buf->head[0].iov_len, len);
545 movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;
546 BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
547 buf->head[0].iov_len);
548 memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
549 buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
550 buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip);
551
552 /* Trim off the trailing "extra count" and checksum blob */
553 xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
554
555 *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip);
556 *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
557 return GSS_S_COMPLETE;
558}
559
560u32
561gss_wrap_kerberos(struct gss_ctx *gctx, int offset,
562 struct xdr_buf *buf, struct page **pages)
563{
564 struct krb5_ctx *kctx = gctx->internal_ctx_id;
565
566 switch (kctx->enctype) {
567 default:
568 BUG();
569 case ENCTYPE_DES_CBC_RAW:
570 case ENCTYPE_DES3_CBC_RAW:
571 return gss_wrap_kerberos_v1(kctx, offset, buf, pages);
572 case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
573 case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
574 return gss_wrap_kerberos_v2(kctx, offset, buf, pages);
575 }
576}
577
578u32
579gss_unwrap_kerberos(struct gss_ctx *gctx, int offset,
580 int len, struct xdr_buf *buf)
581{
582 struct krb5_ctx *kctx = gctx->internal_ctx_id;
583
584 switch (kctx->enctype) {
585 default:
586 BUG();
587 case ENCTYPE_DES_CBC_RAW:
588 case ENCTYPE_DES3_CBC_RAW:
589 return gss_unwrap_kerberos_v1(kctx, offset, len, buf,
590 &gctx->slack, &gctx->align);
591 case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
592 case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
593 return gss_unwrap_kerberos_v2(kctx, offset, len, buf,
594 &gctx->slack, &gctx->align);
595 }
596}
1/*
2 * COPYRIGHT (c) 2008
3 * The Regents of the University of Michigan
4 * ALL RIGHTS RESERVED
5 *
6 * Permission is granted to use, copy, create derivative works
7 * and redistribute this software and such derivative works
8 * for any purpose, so long as the name of The University of
9 * Michigan is not used in any advertising or publicity
10 * pertaining to the use of distribution of this software
11 * without specific, written prior authorization. If the
12 * above copyright notice or any other identification of the
13 * University of Michigan is included in any copy of any
14 * portion of this software, then the disclaimer below must
15 * also be included.
16 *
17 * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION
18 * FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY
19 * PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF
20 * MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
21 * WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
22 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
23 * REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE
24 * FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR
25 * CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING
26 * OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
27 * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGES.
29 */
30
31#include <crypto/skcipher.h>
32#include <linux/types.h>
33#include <linux/jiffies.h>
34#include <linux/sunrpc/gss_krb5.h>
35#include <linux/random.h>
36#include <linux/pagemap.h>
37
38#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
39# define RPCDBG_FACILITY RPCDBG_AUTH
40#endif
41
42static inline int
43gss_krb5_padding(int blocksize, int length)
44{
45 return blocksize - (length % blocksize);
46}
47
48static inline void
49gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize)
50{
51 int padding = gss_krb5_padding(blocksize, buf->len - offset);
52 char *p;
53 struct kvec *iov;
54
55 if (buf->page_len || buf->tail[0].iov_len)
56 iov = &buf->tail[0];
57 else
58 iov = &buf->head[0];
59 p = iov->iov_base + iov->iov_len;
60 iov->iov_len += padding;
61 buf->len += padding;
62 memset(p, padding, padding);
63}
64
65static inline int
66gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize)
67{
68 u8 *ptr;
69 u8 pad;
70 size_t len = buf->len;
71
72 if (len <= buf->head[0].iov_len) {
73 pad = *(u8 *)(buf->head[0].iov_base + len - 1);
74 if (pad > buf->head[0].iov_len)
75 return -EINVAL;
76 buf->head[0].iov_len -= pad;
77 goto out;
78 } else
79 len -= buf->head[0].iov_len;
80 if (len <= buf->page_len) {
81 unsigned int last = (buf->page_base + len - 1)
82 >>PAGE_SHIFT;
83 unsigned int offset = (buf->page_base + len - 1)
84 & (PAGE_SIZE - 1);
85 ptr = kmap_atomic(buf->pages[last]);
86 pad = *(ptr + offset);
87 kunmap_atomic(ptr);
88 goto out;
89 } else
90 len -= buf->page_len;
91 BUG_ON(len > buf->tail[0].iov_len);
92 pad = *(u8 *)(buf->tail[0].iov_base + len - 1);
93out:
94 /* XXX: NOTE: we do not adjust the page lengths--they represent
95 * a range of data in the real filesystem page cache, and we need
96 * to know that range so the xdr code can properly place read data.
97 * However adjusting the head length, as we do above, is harmless.
98 * In the case of a request that fits into a single page, the server
99 * also uses length and head length together to determine the original
100 * start of the request to copy the request for deferal; so it's
101 * easier on the server if we adjust head and tail length in tandem.
102 * It's not really a problem that we don't fool with the page and
103 * tail lengths, though--at worst badly formed xdr might lead the
104 * server to attempt to parse the padding.
105 * XXX: Document all these weird requirements for gss mechanism
106 * wrap/unwrap functions. */
107 if (pad > blocksize)
108 return -EINVAL;
109 if (buf->len > pad)
110 buf->len -= pad;
111 else
112 return -EINVAL;
113 return 0;
114}
115
116void
117gss_krb5_make_confounder(char *p, u32 conflen)
118{
119 static u64 i = 0;
120 u64 *q = (u64 *)p;
121
122 /* rfc1964 claims this should be "random". But all that's really
123 * necessary is that it be unique. And not even that is necessary in
124 * our case since our "gssapi" implementation exists only to support
125 * rpcsec_gss, so we know that the only buffers we will ever encrypt
126 * already begin with a unique sequence number. Just to hedge my bets
127 * I'll make a half-hearted attempt at something unique, but ensuring
128 * uniqueness would mean worrying about atomicity and rollover, and I
129 * don't care enough. */
130
131 /* initialize to random value */
132 if (i == 0) {
133 i = prandom_u32();
134 i = (i << 32) | prandom_u32();
135 }
136
137 switch (conflen) {
138 case 16:
139 *q++ = i++;
140 fallthrough;
141 case 8:
142 *q++ = i++;
143 break;
144 default:
145 BUG();
146 }
147}
148
149/* Assumptions: the head and tail of inbuf are ours to play with.
150 * The pages, however, may be real pages in the page cache and we replace
151 * them with scratch pages from **pages before writing to them. */
152/* XXX: obviously the above should be documentation of wrap interface,
153 * and shouldn't be in this kerberos-specific file. */
154
155/* XXX factor out common code with seal/unseal. */
156
157static u32
158gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
159 struct xdr_buf *buf, struct page **pages)
160{
161 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
162 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata),
163 .data = cksumdata};
164 int blocksize = 0, plainlen;
165 unsigned char *ptr, *msg_start;
166 time64_t now;
167 int headlen;
168 struct page **tmp_pages;
169 u32 seq_send;
170 u8 *cksumkey;
171 u32 conflen = kctx->gk5e->conflen;
172
173 dprintk("RPC: %s\n", __func__);
174
175 now = ktime_get_real_seconds();
176
177 blocksize = crypto_sync_skcipher_blocksize(kctx->enc);
178 gss_krb5_add_padding(buf, offset, blocksize);
179 BUG_ON((buf->len - offset) % blocksize);
180 plainlen = conflen + buf->len - offset;
181
182 headlen = g_token_size(&kctx->mech_used,
183 GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen) -
184 (buf->len - offset);
185
186 ptr = buf->head[0].iov_base + offset;
187 /* shift data to make room for header. */
188 xdr_extend_head(buf, offset, headlen);
189
190 /* XXX Would be cleverer to encrypt while copying. */
191 BUG_ON((buf->len - offset - headlen) % blocksize);
192
193 g_make_token_header(&kctx->mech_used,
194 GSS_KRB5_TOK_HDR_LEN +
195 kctx->gk5e->cksumlength + plainlen, &ptr);
196
197
198 /* ptr now at header described in rfc 1964, section 1.2.1: */
199 ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff);
200 ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff);
201
202 msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength;
203
204 /*
205 * signalg and sealalg are stored as if they were converted from LE
206 * to host endian, even though they're opaque pairs of bytes according
207 * to the RFC.
208 */
209 *(__le16 *)(ptr + 2) = cpu_to_le16(kctx->gk5e->signalg);
210 *(__le16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg);
211 ptr[6] = 0xff;
212 ptr[7] = 0xff;
213
214 gss_krb5_make_confounder(msg_start, conflen);
215
216 if (kctx->gk5e->keyed_cksum)
217 cksumkey = kctx->cksum;
218 else
219 cksumkey = NULL;
220
221 /* XXXJBF: UGH!: */
222 tmp_pages = buf->pages;
223 buf->pages = pages;
224 if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen,
225 cksumkey, KG_USAGE_SEAL, &md5cksum))
226 return GSS_S_FAILURE;
227 buf->pages = tmp_pages;
228
229 memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
230
231 seq_send = atomic_fetch_inc(&kctx->seq_send);
232
233 /* XXX would probably be more efficient to compute checksum
234 * and encrypt at the same time: */
235 if ((krb5_make_seq_num(kctx, kctx->seq, kctx->initiate ? 0 : 0xff,
236 seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
237 return GSS_S_FAILURE;
238
239 if (gss_encrypt_xdr_buf(kctx->enc, buf,
240 offset + headlen - conflen, pages))
241 return GSS_S_FAILURE;
242
243 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
244}
245
246static u32
247gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len,
248 struct xdr_buf *buf, unsigned int *slack,
249 unsigned int *align)
250{
251 int signalg;
252 int sealalg;
253 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
254 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata),
255 .data = cksumdata};
256 time64_t now;
257 int direction;
258 s32 seqnum;
259 unsigned char *ptr;
260 int bodysize;
261 void *data_start, *orig_start;
262 int data_len;
263 int blocksize;
264 u32 conflen = kctx->gk5e->conflen;
265 int crypt_offset;
266 u8 *cksumkey;
267 unsigned int saved_len = buf->len;
268
269 dprintk("RPC: gss_unwrap_kerberos\n");
270
271 ptr = (u8 *)buf->head[0].iov_base + offset;
272 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
273 len - offset))
274 return GSS_S_DEFECTIVE_TOKEN;
275
276 if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
277 (ptr[1] != (KG_TOK_WRAP_MSG & 0xff)))
278 return GSS_S_DEFECTIVE_TOKEN;
279
280 /* XXX sanity-check bodysize?? */
281
282 /* get the sign and seal algorithms */
283
284 signalg = ptr[2] + (ptr[3] << 8);
285 if (signalg != kctx->gk5e->signalg)
286 return GSS_S_DEFECTIVE_TOKEN;
287
288 sealalg = ptr[4] + (ptr[5] << 8);
289 if (sealalg != kctx->gk5e->sealalg)
290 return GSS_S_DEFECTIVE_TOKEN;
291
292 if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
293 return GSS_S_DEFECTIVE_TOKEN;
294
295 /*
296 * Data starts after token header and checksum. ptr points
297 * to the beginning of the token header
298 */
299 crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) -
300 (unsigned char *)buf->head[0].iov_base;
301
302 buf->len = len;
303 if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
304 return GSS_S_DEFECTIVE_TOKEN;
305
306 if (kctx->gk5e->keyed_cksum)
307 cksumkey = kctx->cksum;
308 else
309 cksumkey = NULL;
310
311 if (make_checksum(kctx, ptr, 8, buf, crypt_offset,
312 cksumkey, KG_USAGE_SEAL, &md5cksum))
313 return GSS_S_FAILURE;
314
315 if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
316 kctx->gk5e->cksumlength))
317 return GSS_S_BAD_SIG;
318
319 /* it got through unscathed. Make sure the context is unexpired */
320
321 now = ktime_get_real_seconds();
322
323 if (now > kctx->endtime)
324 return GSS_S_CONTEXT_EXPIRED;
325
326 /* do sequencing checks */
327
328 if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
329 ptr + 8, &direction, &seqnum))
330 return GSS_S_BAD_SIG;
331
332 if ((kctx->initiate && direction != 0xff) ||
333 (!kctx->initiate && direction != 0))
334 return GSS_S_BAD_SIG;
335
336 /* Copy the data back to the right position. XXX: Would probably be
337 * better to copy and encrypt at the same time. */
338
339 blocksize = crypto_sync_skcipher_blocksize(kctx->enc);
340 data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) +
341 conflen;
342 orig_start = buf->head[0].iov_base + offset;
343 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
344 memmove(orig_start, data_start, data_len);
345 buf->head[0].iov_len -= (data_start - orig_start);
346 buf->len = len - (data_start - orig_start);
347
348 if (gss_krb5_remove_padding(buf, blocksize))
349 return GSS_S_DEFECTIVE_TOKEN;
350
351 /* slack must include room for krb5 padding */
352 *slack = XDR_QUADLEN(saved_len - buf->len);
353 /* The GSS blob always precedes the RPC message payload */
354 *align = *slack;
355 return GSS_S_COMPLETE;
356}
357
358/*
359 * We can shift data by up to LOCAL_BUF_LEN bytes in a pass. If we need
360 * to do more than that, we shift repeatedly. Kevin Coffman reports
361 * seeing 28 bytes as the value used by Microsoft clients and servers
362 * with AES, so this constant is chosen to allow handling 28 in one pass
363 * without using too much stack space.
364 *
365 * If that proves to a problem perhaps we could use a more clever
366 * algorithm.
367 */
368#define LOCAL_BUF_LEN 32u
369
370static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift)
371{
372 char head[LOCAL_BUF_LEN];
373 char tmp[LOCAL_BUF_LEN];
374 unsigned int this_len, i;
375
376 BUG_ON(shift > LOCAL_BUF_LEN);
377
378 read_bytes_from_xdr_buf(buf, 0, head, shift);
379 for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) {
380 this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift));
381 read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len);
382 write_bytes_to_xdr_buf(buf, i, tmp, this_len);
383 }
384 write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift);
385}
386
387static void _rotate_left(struct xdr_buf *buf, unsigned int shift)
388{
389 int shifted = 0;
390 int this_shift;
391
392 shift %= buf->len;
393 while (shifted < shift) {
394 this_shift = min(shift - shifted, LOCAL_BUF_LEN);
395 rotate_buf_a_little(buf, this_shift);
396 shifted += this_shift;
397 }
398}
399
400static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift)
401{
402 struct xdr_buf subbuf;
403
404 xdr_buf_subsegment(buf, &subbuf, base, buf->len - base);
405 _rotate_left(&subbuf, shift);
406}
407
408static u32
409gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
410 struct xdr_buf *buf, struct page **pages)
411{
412 u8 *ptr, *plainhdr;
413 time64_t now;
414 u8 flags = 0x00;
415 __be16 *be16ptr;
416 __be64 *be64ptr;
417 u32 err;
418
419 dprintk("RPC: %s\n", __func__);
420
421 if (kctx->gk5e->encrypt_v2 == NULL)
422 return GSS_S_FAILURE;
423
424 /* make room for gss token header */
425 if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN))
426 return GSS_S_FAILURE;
427
428 /* construct gss token header */
429 ptr = plainhdr = buf->head[0].iov_base + offset;
430 *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff);
431 *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff);
432
433 if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
434 flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR;
435 if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0)
436 flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY;
437 /* We always do confidentiality in wrap tokens */
438 flags |= KG2_TOKEN_FLAG_SEALED;
439
440 *ptr++ = flags;
441 *ptr++ = 0xff;
442 be16ptr = (__be16 *)ptr;
443
444 *be16ptr++ = 0;
445 /* "inner" token header always uses 0 for RRC */
446 *be16ptr++ = 0;
447
448 be64ptr = (__be64 *)be16ptr;
449 *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64));
450
451 err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, pages);
452 if (err)
453 return err;
454
455 now = ktime_get_real_seconds();
456 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
457}
458
459static u32
460gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len,
461 struct xdr_buf *buf, unsigned int *slack,
462 unsigned int *align)
463{
464 time64_t now;
465 u8 *ptr;
466 u8 flags = 0x00;
467 u16 ec, rrc;
468 int err;
469 u32 headskip, tailskip;
470 u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN];
471 unsigned int movelen;
472
473
474 dprintk("RPC: %s\n", __func__);
475
476 if (kctx->gk5e->decrypt_v2 == NULL)
477 return GSS_S_FAILURE;
478
479 ptr = buf->head[0].iov_base + offset;
480
481 if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP)
482 return GSS_S_DEFECTIVE_TOKEN;
483
484 flags = ptr[2];
485 if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
486 (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
487 return GSS_S_BAD_SIG;
488
489 if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) {
490 dprintk("%s: token missing expected sealed flag\n", __func__);
491 return GSS_S_DEFECTIVE_TOKEN;
492 }
493
494 if (ptr[3] != 0xff)
495 return GSS_S_DEFECTIVE_TOKEN;
496
497 ec = be16_to_cpup((__be16 *)(ptr + 4));
498 rrc = be16_to_cpup((__be16 *)(ptr + 6));
499
500 /*
501 * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
502 * doesn't want it checked; see page 6 of rfc 2203.
503 */
504
505 if (rrc != 0)
506 rotate_left(offset + 16, buf, rrc);
507
508 err = (*kctx->gk5e->decrypt_v2)(kctx, offset, len, buf,
509 &headskip, &tailskip);
510 if (err)
511 return GSS_S_FAILURE;
512
513 /*
514 * Retrieve the decrypted gss token header and verify
515 * it against the original
516 */
517 err = read_bytes_from_xdr_buf(buf,
518 len - GSS_KRB5_TOK_HDR_LEN - tailskip,
519 decrypted_hdr, GSS_KRB5_TOK_HDR_LEN);
520 if (err) {
521 dprintk("%s: error %u getting decrypted_hdr\n", __func__, err);
522 return GSS_S_FAILURE;
523 }
524 if (memcmp(ptr, decrypted_hdr, 6)
525 || memcmp(ptr + 8, decrypted_hdr + 8, 8)) {
526 dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__);
527 return GSS_S_FAILURE;
528 }
529
530 /* do sequencing checks */
531
532 /* it got through unscathed. Make sure the context is unexpired */
533 now = ktime_get_real_seconds();
534 if (now > kctx->endtime)
535 return GSS_S_CONTEXT_EXPIRED;
536
537 /*
538 * Move the head data back to the right position in xdr_buf.
539 * We ignore any "ec" data since it might be in the head or
540 * the tail, and we really don't need to deal with it.
541 * Note that buf->head[0].iov_len may indicate the available
542 * head buffer space rather than that actually occupied.
543 */
544 movelen = min_t(unsigned int, buf->head[0].iov_len, len);
545 movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;
546 BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
547 buf->head[0].iov_len);
548 memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
549 buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
550 buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip);
551
552 /* Trim off the trailing "extra count" and checksum blob */
553 xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
554
555 *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip);
556 *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
557 return GSS_S_COMPLETE;
558}
559
560u32
561gss_wrap_kerberos(struct gss_ctx *gctx, int offset,
562 struct xdr_buf *buf, struct page **pages)
563{
564 struct krb5_ctx *kctx = gctx->internal_ctx_id;
565
566 switch (kctx->enctype) {
567 default:
568 BUG();
569 case ENCTYPE_DES_CBC_RAW:
570 case ENCTYPE_DES3_CBC_RAW:
571 return gss_wrap_kerberos_v1(kctx, offset, buf, pages);
572 case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
573 case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
574 return gss_wrap_kerberos_v2(kctx, offset, buf, pages);
575 }
576}
577
578u32
579gss_unwrap_kerberos(struct gss_ctx *gctx, int offset,
580 int len, struct xdr_buf *buf)
581{
582 struct krb5_ctx *kctx = gctx->internal_ctx_id;
583
584 switch (kctx->enctype) {
585 default:
586 BUG();
587 case ENCTYPE_DES_CBC_RAW:
588 case ENCTYPE_DES3_CBC_RAW:
589 return gss_unwrap_kerberos_v1(kctx, offset, len, buf,
590 &gctx->slack, &gctx->align);
591 case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
592 case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
593 return gss_unwrap_kerberos_v2(kctx, offset, len, buf,
594 &gctx->slack, &gctx->align);
595 }
596}