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TOMOYO Linux Cross Reference
Linux/net/sunrpc/auth_gss/gss_krb5_crypto.c

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  1 /*
  2  *  linux/net/sunrpc/gss_krb5_crypto.c
  3  *
  4  *  Copyright (c) 2000-2008 The Regents of the University of Michigan.
  5  *  All rights reserved.
  6  *
  7  *  Andy Adamson   <andros@umich.edu>
  8  *  Bruce Fields   <bfields@umich.edu>
  9  */
 10 
 11 /*
 12  * Copyright (C) 1998 by the FundsXpress, INC.
 13  *
 14  * All rights reserved.
 15  *
 16  * Export of this software from the United States of America may require
 17  * a specific license from the United States Government.  It is the
 18  * responsibility of any person or organization contemplating export to
 19  * obtain such a license before exporting.
 20  *
 21  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 22  * distribute this software and its documentation for any purpose and
 23  * without fee is hereby granted, provided that the above copyright
 24  * notice appear in all copies and that both that copyright notice and
 25  * this permission notice appear in supporting documentation, and that
 26  * the name of FundsXpress. not be used in advertising or publicity pertaining
 27  * to distribution of the software without specific, written prior
 28  * permission.  FundsXpress makes no representations about the suitability of
 29  * this software for any purpose.  It is provided "as is" without express
 30  * or implied warranty.
 31  *
 32  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 33  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 34  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 35  */
 36 
 37 #include <crypto/hash.h>
 38 #include <crypto/skcipher.h>
 39 #include <linux/err.h>
 40 #include <linux/types.h>
 41 #include <linux/mm.h>
 42 #include <linux/scatterlist.h>
 43 #include <linux/highmem.h>
 44 #include <linux/pagemap.h>
 45 #include <linux/random.h>
 46 #include <linux/sunrpc/gss_krb5.h>
 47 #include <linux/sunrpc/xdr.h>
 48 
 49 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 50 # define RPCDBG_FACILITY        RPCDBG_AUTH
 51 #endif
 52 
 53 u32
 54 krb5_encrypt(
 55         struct crypto_skcipher *tfm,
 56         void * iv,
 57         void * in,
 58         void * out,
 59         int length)
 60 {
 61         u32 ret = -EINVAL;
 62         struct scatterlist sg[1];
 63         u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
 64         SKCIPHER_REQUEST_ON_STACK(req, tfm);
 65 
 66         if (length % crypto_skcipher_blocksize(tfm) != 0)
 67                 goto out;
 68 
 69         if (crypto_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
 70                 dprintk("RPC:       gss_k5encrypt: tfm iv size too large %d\n",
 71                         crypto_skcipher_ivsize(tfm));
 72                 goto out;
 73         }
 74 
 75         if (iv)
 76                 memcpy(local_iv, iv, crypto_skcipher_ivsize(tfm));
 77 
 78         memcpy(out, in, length);
 79         sg_init_one(sg, out, length);
 80 
 81         skcipher_request_set_tfm(req, tfm);
 82         skcipher_request_set_callback(req, 0, NULL, NULL);
 83         skcipher_request_set_crypt(req, sg, sg, length, local_iv);
 84 
 85         ret = crypto_skcipher_encrypt(req);
 86         skcipher_request_zero(req);
 87 out:
 88         dprintk("RPC:       krb5_encrypt returns %d\n", ret);
 89         return ret;
 90 }
 91 
 92 u32
 93 krb5_decrypt(
 94      struct crypto_skcipher *tfm,
 95      void * iv,
 96      void * in,
 97      void * out,
 98      int length)
 99 {
100         u32 ret = -EINVAL;
101         struct scatterlist sg[1];
102         u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
103         SKCIPHER_REQUEST_ON_STACK(req, tfm);
104 
105         if (length % crypto_skcipher_blocksize(tfm) != 0)
106                 goto out;
107 
108         if (crypto_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
109                 dprintk("RPC:       gss_k5decrypt: tfm iv size too large %d\n",
110                         crypto_skcipher_ivsize(tfm));
111                 goto out;
112         }
113         if (iv)
114                 memcpy(local_iv,iv, crypto_skcipher_ivsize(tfm));
115 
116         memcpy(out, in, length);
117         sg_init_one(sg, out, length);
118 
119         skcipher_request_set_tfm(req, tfm);
120         skcipher_request_set_callback(req, 0, NULL, NULL);
121         skcipher_request_set_crypt(req, sg, sg, length, local_iv);
122 
123         ret = crypto_skcipher_decrypt(req);
124         skcipher_request_zero(req);
125 out:
126         dprintk("RPC:       gss_k5decrypt returns %d\n",ret);
127         return ret;
128 }
129 
130 static int
131 checksummer(struct scatterlist *sg, void *data)
132 {
133         struct ahash_request *req = data;
134 
135         ahash_request_set_crypt(req, sg, NULL, sg->length);
136 
137         return crypto_ahash_update(req);
138 }
139 
140 static int
141 arcfour_hmac_md5_usage_to_salt(unsigned int usage, u8 salt[4])
142 {
143         unsigned int ms_usage;
144 
145         switch (usage) {
146         case KG_USAGE_SIGN:
147                 ms_usage = 15;
148                 break;
149         case KG_USAGE_SEAL:
150                 ms_usage = 13;
151                 break;
152         default:
153                 return -EINVAL;
154         }
155         salt[0] = (ms_usage >> 0) & 0xff;
156         salt[1] = (ms_usage >> 8) & 0xff;
157         salt[2] = (ms_usage >> 16) & 0xff;
158         salt[3] = (ms_usage >> 24) & 0xff;
159 
160         return 0;
161 }
162 
163 static u32
164 make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
165                        struct xdr_buf *body, int body_offset, u8 *cksumkey,
166                        unsigned int usage, struct xdr_netobj *cksumout)
167 {
168         struct scatterlist              sg[1];
169         int err;
170         u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
171         u8 rc4salt[4];
172         struct crypto_ahash *md5;
173         struct crypto_ahash *hmac_md5;
174         struct ahash_request *req;
175 
176         if (cksumkey == NULL)
177                 return GSS_S_FAILURE;
178 
179         if (cksumout->len < kctx->gk5e->cksumlength) {
180                 dprintk("%s: checksum buffer length, %u, too small for %s\n",
181                         __func__, cksumout->len, kctx->gk5e->name);
182                 return GSS_S_FAILURE;
183         }
184 
185         if (arcfour_hmac_md5_usage_to_salt(usage, rc4salt)) {
186                 dprintk("%s: invalid usage value %u\n", __func__, usage);
187                 return GSS_S_FAILURE;
188         }
189 
190         md5 = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
191         if (IS_ERR(md5))
192                 return GSS_S_FAILURE;
193 
194         hmac_md5 = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0,
195                                       CRYPTO_ALG_ASYNC);
196         if (IS_ERR(hmac_md5)) {
197                 crypto_free_ahash(md5);
198                 return GSS_S_FAILURE;
199         }
200 
201         req = ahash_request_alloc(md5, GFP_KERNEL);
202         if (!req) {
203                 crypto_free_ahash(hmac_md5);
204                 crypto_free_ahash(md5);
205                 return GSS_S_FAILURE;
206         }
207 
208         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
209 
210         err = crypto_ahash_init(req);
211         if (err)
212                 goto out;
213         sg_init_one(sg, rc4salt, 4);
214         ahash_request_set_crypt(req, sg, NULL, 4);
215         err = crypto_ahash_update(req);
216         if (err)
217                 goto out;
218 
219         sg_init_one(sg, header, hdrlen);
220         ahash_request_set_crypt(req, sg, NULL, hdrlen);
221         err = crypto_ahash_update(req);
222         if (err)
223                 goto out;
224         err = xdr_process_buf(body, body_offset, body->len - body_offset,
225                               checksummer, req);
226         if (err)
227                 goto out;
228         ahash_request_set_crypt(req, NULL, checksumdata, 0);
229         err = crypto_ahash_final(req);
230         if (err)
231                 goto out;
232 
233         ahash_request_free(req);
234         req = ahash_request_alloc(hmac_md5, GFP_KERNEL);
235         if (!req) {
236                 crypto_free_ahash(hmac_md5);
237                 crypto_free_ahash(md5);
238                 return GSS_S_FAILURE;
239         }
240 
241         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
242 
243         err = crypto_ahash_init(req);
244         if (err)
245                 goto out;
246         err = crypto_ahash_setkey(hmac_md5, cksumkey, kctx->gk5e->keylength);
247         if (err)
248                 goto out;
249 
250         sg_init_one(sg, checksumdata, crypto_ahash_digestsize(md5));
251         ahash_request_set_crypt(req, sg, checksumdata,
252                                 crypto_ahash_digestsize(md5));
253         err = crypto_ahash_digest(req);
254         if (err)
255                 goto out;
256 
257         memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
258         cksumout->len = kctx->gk5e->cksumlength;
259 out:
260         ahash_request_free(req);
261         crypto_free_ahash(md5);
262         crypto_free_ahash(hmac_md5);
263         return err ? GSS_S_FAILURE : 0;
264 }
265 
266 /*
267  * checksum the plaintext data and hdrlen bytes of the token header
268  * The checksum is performed over the first 8 bytes of the
269  * gss token header and then over the data body
270  */
271 u32
272 make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
273               struct xdr_buf *body, int body_offset, u8 *cksumkey,
274               unsigned int usage, struct xdr_netobj *cksumout)
275 {
276         struct crypto_ahash *tfm;
277         struct ahash_request *req;
278         struct scatterlist              sg[1];
279         int err;
280         u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
281         unsigned int checksumlen;
282 
283         if (kctx->gk5e->ctype == CKSUMTYPE_HMAC_MD5_ARCFOUR)
284                 return make_checksum_hmac_md5(kctx, header, hdrlen,
285                                               body, body_offset,
286                                               cksumkey, usage, cksumout);
287 
288         if (cksumout->len < kctx->gk5e->cksumlength) {
289                 dprintk("%s: checksum buffer length, %u, too small for %s\n",
290                         __func__, cksumout->len, kctx->gk5e->name);
291                 return GSS_S_FAILURE;
292         }
293 
294         tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
295         if (IS_ERR(tfm))
296                 return GSS_S_FAILURE;
297 
298         req = ahash_request_alloc(tfm, GFP_KERNEL);
299         if (!req) {
300                 crypto_free_ahash(tfm);
301                 return GSS_S_FAILURE;
302         }
303 
304         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
305 
306         checksumlen = crypto_ahash_digestsize(tfm);
307 
308         if (cksumkey != NULL) {
309                 err = crypto_ahash_setkey(tfm, cksumkey,
310                                           kctx->gk5e->keylength);
311                 if (err)
312                         goto out;
313         }
314 
315         err = crypto_ahash_init(req);
316         if (err)
317                 goto out;
318         sg_init_one(sg, header, hdrlen);
319         ahash_request_set_crypt(req, sg, NULL, hdrlen);
320         err = crypto_ahash_update(req);
321         if (err)
322                 goto out;
323         err = xdr_process_buf(body, body_offset, body->len - body_offset,
324                               checksummer, req);
325         if (err)
326                 goto out;
327         ahash_request_set_crypt(req, NULL, checksumdata, 0);
328         err = crypto_ahash_final(req);
329         if (err)
330                 goto out;
331 
332         switch (kctx->gk5e->ctype) {
333         case CKSUMTYPE_RSA_MD5:
334                 err = kctx->gk5e->encrypt(kctx->seq, NULL, checksumdata,
335                                           checksumdata, checksumlen);
336                 if (err)
337                         goto out;
338                 memcpy(cksumout->data,
339                        checksumdata + checksumlen - kctx->gk5e->cksumlength,
340                        kctx->gk5e->cksumlength);
341                 break;
342         case CKSUMTYPE_HMAC_SHA1_DES3:
343                 memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
344                 break;
345         default:
346                 BUG();
347                 break;
348         }
349         cksumout->len = kctx->gk5e->cksumlength;
350 out:
351         ahash_request_free(req);
352         crypto_free_ahash(tfm);
353         return err ? GSS_S_FAILURE : 0;
354 }
355 
356 /*
357  * checksum the plaintext data and hdrlen bytes of the token header
358  * Per rfc4121, sec. 4.2.4, the checksum is performed over the data
359  * body then over the first 16 octets of the MIC token
360  * Inclusion of the header data in the calculation of the
361  * checksum is optional.
362  */
363 u32
364 make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen,
365                  struct xdr_buf *body, int body_offset, u8 *cksumkey,
366                  unsigned int usage, struct xdr_netobj *cksumout)
367 {
368         struct crypto_ahash *tfm;
369         struct ahash_request *req;
370         struct scatterlist sg[1];
371         int err;
372         u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
373         unsigned int checksumlen;
374 
375         if (kctx->gk5e->keyed_cksum == 0) {
376                 dprintk("%s: expected keyed hash for %s\n",
377                         __func__, kctx->gk5e->name);
378                 return GSS_S_FAILURE;
379         }
380         if (cksumkey == NULL) {
381                 dprintk("%s: no key supplied for %s\n",
382                         __func__, kctx->gk5e->name);
383                 return GSS_S_FAILURE;
384         }
385 
386         tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
387         if (IS_ERR(tfm))
388                 return GSS_S_FAILURE;
389         checksumlen = crypto_ahash_digestsize(tfm);
390 
391         req = ahash_request_alloc(tfm, GFP_KERNEL);
392         if (!req) {
393                 crypto_free_ahash(tfm);
394                 return GSS_S_FAILURE;
395         }
396 
397         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
398 
399         err = crypto_ahash_setkey(tfm, cksumkey, kctx->gk5e->keylength);
400         if (err)
401                 goto out;
402 
403         err = crypto_ahash_init(req);
404         if (err)
405                 goto out;
406         err = xdr_process_buf(body, body_offset, body->len - body_offset,
407                               checksummer, req);
408         if (err)
409                 goto out;
410         if (header != NULL) {
411                 sg_init_one(sg, header, hdrlen);
412                 ahash_request_set_crypt(req, sg, NULL, hdrlen);
413                 err = crypto_ahash_update(req);
414                 if (err)
415                         goto out;
416         }
417         ahash_request_set_crypt(req, NULL, checksumdata, 0);
418         err = crypto_ahash_final(req);
419         if (err)
420                 goto out;
421 
422         cksumout->len = kctx->gk5e->cksumlength;
423 
424         switch (kctx->gk5e->ctype) {
425         case CKSUMTYPE_HMAC_SHA1_96_AES128:
426         case CKSUMTYPE_HMAC_SHA1_96_AES256:
427                 /* note that this truncates the hash */
428                 memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
429                 break;
430         default:
431                 BUG();
432                 break;
433         }
434 out:
435         ahash_request_free(req);
436         crypto_free_ahash(tfm);
437         return err ? GSS_S_FAILURE : 0;
438 }
439 
440 struct encryptor_desc {
441         u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
442         struct skcipher_request *req;
443         int pos;
444         struct xdr_buf *outbuf;
445         struct page **pages;
446         struct scatterlist infrags[4];
447         struct scatterlist outfrags[4];
448         int fragno;
449         int fraglen;
450 };
451 
452 static int
453 encryptor(struct scatterlist *sg, void *data)
454 {
455         struct encryptor_desc *desc = data;
456         struct xdr_buf *outbuf = desc->outbuf;
457         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(desc->req);
458         struct page *in_page;
459         int thislen = desc->fraglen + sg->length;
460         int fraglen, ret;
461         int page_pos;
462 
463         /* Worst case is 4 fragments: head, end of page 1, start
464          * of page 2, tail.  Anything more is a bug. */
465         BUG_ON(desc->fragno > 3);
466 
467         page_pos = desc->pos - outbuf->head[0].iov_len;
468         if (page_pos >= 0 && page_pos < outbuf->page_len) {
469                 /* pages are not in place: */
470                 int i = (page_pos + outbuf->page_base) >> PAGE_SHIFT;
471                 in_page = desc->pages[i];
472         } else {
473                 in_page = sg_page(sg);
474         }
475         sg_set_page(&desc->infrags[desc->fragno], in_page, sg->length,
476                     sg->offset);
477         sg_set_page(&desc->outfrags[desc->fragno], sg_page(sg), sg->length,
478                     sg->offset);
479         desc->fragno++;
480         desc->fraglen += sg->length;
481         desc->pos += sg->length;
482 
483         fraglen = thislen & (crypto_skcipher_blocksize(tfm) - 1);
484         thislen -= fraglen;
485 
486         if (thislen == 0)
487                 return 0;
488 
489         sg_mark_end(&desc->infrags[desc->fragno - 1]);
490         sg_mark_end(&desc->outfrags[desc->fragno - 1]);
491 
492         skcipher_request_set_crypt(desc->req, desc->infrags, desc->outfrags,
493                                    thislen, desc->iv);
494 
495         ret = crypto_skcipher_encrypt(desc->req);
496         if (ret)
497                 return ret;
498 
499         sg_init_table(desc->infrags, 4);
500         sg_init_table(desc->outfrags, 4);
501 
502         if (fraglen) {
503                 sg_set_page(&desc->outfrags[0], sg_page(sg), fraglen,
504                                 sg->offset + sg->length - fraglen);
505                 desc->infrags[0] = desc->outfrags[0];
506                 sg_assign_page(&desc->infrags[0], in_page);
507                 desc->fragno = 1;
508                 desc->fraglen = fraglen;
509         } else {
510                 desc->fragno = 0;
511                 desc->fraglen = 0;
512         }
513         return 0;
514 }
515 
516 int
517 gss_encrypt_xdr_buf(struct crypto_skcipher *tfm, struct xdr_buf *buf,
518                     int offset, struct page **pages)
519 {
520         int ret;
521         struct encryptor_desc desc;
522         SKCIPHER_REQUEST_ON_STACK(req, tfm);
523 
524         BUG_ON((buf->len - offset) % crypto_skcipher_blocksize(tfm) != 0);
525 
526         skcipher_request_set_tfm(req, tfm);
527         skcipher_request_set_callback(req, 0, NULL, NULL);
528 
529         memset(desc.iv, 0, sizeof(desc.iv));
530         desc.req = req;
531         desc.pos = offset;
532         desc.outbuf = buf;
533         desc.pages = pages;
534         desc.fragno = 0;
535         desc.fraglen = 0;
536 
537         sg_init_table(desc.infrags, 4);
538         sg_init_table(desc.outfrags, 4);
539 
540         ret = xdr_process_buf(buf, offset, buf->len - offset, encryptor, &desc);
541         skcipher_request_zero(req);
542         return ret;
543 }
544 
545 struct decryptor_desc {
546         u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
547         struct skcipher_request *req;
548         struct scatterlist frags[4];
549         int fragno;
550         int fraglen;
551 };
552 
553 static int
554 decryptor(struct scatterlist *sg, void *data)
555 {
556         struct decryptor_desc *desc = data;
557         int thislen = desc->fraglen + sg->length;
558         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(desc->req);
559         int fraglen, ret;
560 
561         /* Worst case is 4 fragments: head, end of page 1, start
562          * of page 2, tail.  Anything more is a bug. */
563         BUG_ON(desc->fragno > 3);
564         sg_set_page(&desc->frags[desc->fragno], sg_page(sg), sg->length,
565                     sg->offset);
566         desc->fragno++;
567         desc->fraglen += sg->length;
568 
569         fraglen = thislen & (crypto_skcipher_blocksize(tfm) - 1);
570         thislen -= fraglen;
571 
572         if (thislen == 0)
573                 return 0;
574 
575         sg_mark_end(&desc->frags[desc->fragno - 1]);
576 
577         skcipher_request_set_crypt(desc->req, desc->frags, desc->frags,
578                                    thislen, desc->iv);
579 
580         ret = crypto_skcipher_decrypt(desc->req);
581         if (ret)
582                 return ret;
583 
584         sg_init_table(desc->frags, 4);
585 
586         if (fraglen) {
587                 sg_set_page(&desc->frags[0], sg_page(sg), fraglen,
588                                 sg->offset + sg->length - fraglen);
589                 desc->fragno = 1;
590                 desc->fraglen = fraglen;
591         } else {
592                 desc->fragno = 0;
593                 desc->fraglen = 0;
594         }
595         return 0;
596 }
597 
598 int
599 gss_decrypt_xdr_buf(struct crypto_skcipher *tfm, struct xdr_buf *buf,
600                     int offset)
601 {
602         int ret;
603         struct decryptor_desc desc;
604         SKCIPHER_REQUEST_ON_STACK(req, tfm);
605 
606         /* XXXJBF: */
607         BUG_ON((buf->len - offset) % crypto_skcipher_blocksize(tfm) != 0);
608 
609         skcipher_request_set_tfm(req, tfm);
610         skcipher_request_set_callback(req, 0, NULL, NULL);
611 
612         memset(desc.iv, 0, sizeof(desc.iv));
613         desc.req = req;
614         desc.fragno = 0;
615         desc.fraglen = 0;
616 
617         sg_init_table(desc.frags, 4);
618 
619         ret = xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
620         skcipher_request_zero(req);
621         return ret;
622 }
623 
624 /*
625  * This function makes the assumption that it was ultimately called
626  * from gss_wrap().
627  *
628  * The client auth_gss code moves any existing tail data into a
629  * separate page before calling gss_wrap.
630  * The server svcauth_gss code ensures that both the head and the
631  * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
632  *
633  * Even with that guarantee, this function may be called more than
634  * once in the processing of gss_wrap().  The best we can do is
635  * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
636  * largest expected shift will fit within RPC_MAX_AUTH_SIZE.
637  * At run-time we can verify that a single invocation of this
638  * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
639  */
640 
641 int
642 xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
643 {
644         u8 *p;
645 
646         if (shiftlen == 0)
647                 return 0;
648 
649         BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE);
650         BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
651 
652         p = buf->head[0].iov_base + base;
653 
654         memmove(p + shiftlen, p, buf->head[0].iov_len - base);
655 
656         buf->head[0].iov_len += shiftlen;
657         buf->len += shiftlen;
658 
659         return 0;
660 }
661 
662 static u32
663 gss_krb5_cts_crypt(struct crypto_skcipher *cipher, struct xdr_buf *buf,
664                    u32 offset, u8 *iv, struct page **pages, int encrypt)
665 {
666         u32 ret;
667         struct scatterlist sg[1];
668         SKCIPHER_REQUEST_ON_STACK(req, cipher);
669         u8 data[GSS_KRB5_MAX_BLOCKSIZE * 2];
670         struct page **save_pages;
671         u32 len = buf->len - offset;
672 
673         if (len > ARRAY_SIZE(data)) {
674                 WARN_ON(0);
675                 return -ENOMEM;
676         }
677 
678         /*
679          * For encryption, we want to read from the cleartext
680          * page cache pages, and write the encrypted data to
681          * the supplied xdr_buf pages.
682          */
683         save_pages = buf->pages;
684         if (encrypt)
685                 buf->pages = pages;
686 
687         ret = read_bytes_from_xdr_buf(buf, offset, data, len);
688         buf->pages = save_pages;
689         if (ret)
690                 goto out;
691 
692         sg_init_one(sg, data, len);
693 
694         skcipher_request_set_tfm(req, cipher);
695         skcipher_request_set_callback(req, 0, NULL, NULL);
696         skcipher_request_set_crypt(req, sg, sg, len, iv);
697 
698         if (encrypt)
699                 ret = crypto_skcipher_encrypt(req);
700         else
701                 ret = crypto_skcipher_decrypt(req);
702 
703         skcipher_request_zero(req);
704 
705         if (ret)
706                 goto out;
707 
708         ret = write_bytes_to_xdr_buf(buf, offset, data, len);
709 
710 out:
711         return ret;
712 }
713 
714 u32
715 gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
716                      struct xdr_buf *buf, struct page **pages)
717 {
718         u32 err;
719         struct xdr_netobj hmac;
720         u8 *cksumkey;
721         u8 *ecptr;
722         struct crypto_skcipher *cipher, *aux_cipher;
723         int blocksize;
724         struct page **save_pages;
725         int nblocks, nbytes;
726         struct encryptor_desc desc;
727         u32 cbcbytes;
728         unsigned int usage;
729 
730         if (kctx->initiate) {
731                 cipher = kctx->initiator_enc;
732                 aux_cipher = kctx->initiator_enc_aux;
733                 cksumkey = kctx->initiator_integ;
734                 usage = KG_USAGE_INITIATOR_SEAL;
735         } else {
736                 cipher = kctx->acceptor_enc;
737                 aux_cipher = kctx->acceptor_enc_aux;
738                 cksumkey = kctx->acceptor_integ;
739                 usage = KG_USAGE_ACCEPTOR_SEAL;
740         }
741         blocksize = crypto_skcipher_blocksize(cipher);
742 
743         /* hide the gss token header and insert the confounder */
744         offset += GSS_KRB5_TOK_HDR_LEN;
745         if (xdr_extend_head(buf, offset, kctx->gk5e->conflen))
746                 return GSS_S_FAILURE;
747         gss_krb5_make_confounder(buf->head[0].iov_base + offset, kctx->gk5e->conflen);
748         offset -= GSS_KRB5_TOK_HDR_LEN;
749 
750         if (buf->tail[0].iov_base != NULL) {
751                 ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
752         } else {
753                 buf->tail[0].iov_base = buf->head[0].iov_base
754                                                         + buf->head[0].iov_len;
755                 buf->tail[0].iov_len = 0;
756                 ecptr = buf->tail[0].iov_base;
757         }
758 
759         /* copy plaintext gss token header after filler (if any) */
760         memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
761         buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
762         buf->len += GSS_KRB5_TOK_HDR_LEN;
763 
764         /* Do the HMAC */
765         hmac.len = GSS_KRB5_MAX_CKSUM_LEN;
766         hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
767 
768         /*
769          * When we are called, pages points to the real page cache
770          * data -- which we can't go and encrypt!  buf->pages points
771          * to scratch pages which we are going to send off to the
772          * client/server.  Swap in the plaintext pages to calculate
773          * the hmac.
774          */
775         save_pages = buf->pages;
776         buf->pages = pages;
777 
778         err = make_checksum_v2(kctx, NULL, 0, buf,
779                                offset + GSS_KRB5_TOK_HDR_LEN,
780                                cksumkey, usage, &hmac);
781         buf->pages = save_pages;
782         if (err)
783                 return GSS_S_FAILURE;
784 
785         nbytes = buf->len - offset - GSS_KRB5_TOK_HDR_LEN;
786         nblocks = (nbytes + blocksize - 1) / blocksize;
787         cbcbytes = 0;
788         if (nblocks > 2)
789                 cbcbytes = (nblocks - 2) * blocksize;
790 
791         memset(desc.iv, 0, sizeof(desc.iv));
792 
793         if (cbcbytes) {
794                 SKCIPHER_REQUEST_ON_STACK(req, aux_cipher);
795 
796                 desc.pos = offset + GSS_KRB5_TOK_HDR_LEN;
797                 desc.fragno = 0;
798                 desc.fraglen = 0;
799                 desc.pages = pages;
800                 desc.outbuf = buf;
801                 desc.req = req;
802 
803                 skcipher_request_set_tfm(req, aux_cipher);
804                 skcipher_request_set_callback(req, 0, NULL, NULL);
805 
806                 sg_init_table(desc.infrags, 4);
807                 sg_init_table(desc.outfrags, 4);
808 
809                 err = xdr_process_buf(buf, offset + GSS_KRB5_TOK_HDR_LEN,
810                                       cbcbytes, encryptor, &desc);
811                 skcipher_request_zero(req);
812                 if (err)
813                         goto out_err;
814         }
815 
816         /* Make sure IV carries forward from any CBC results. */
817         err = gss_krb5_cts_crypt(cipher, buf,
818                                  offset + GSS_KRB5_TOK_HDR_LEN + cbcbytes,
819                                  desc.iv, pages, 1);
820         if (err) {
821                 err = GSS_S_FAILURE;
822                 goto out_err;
823         }
824 
825         /* Now update buf to account for HMAC */
826         buf->tail[0].iov_len += kctx->gk5e->cksumlength;
827         buf->len += kctx->gk5e->cksumlength;
828 
829 out_err:
830         if (err)
831                 err = GSS_S_FAILURE;
832         return err;
833 }
834 
835 u32
836 gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
837                      u32 *headskip, u32 *tailskip)
838 {
839         struct xdr_buf subbuf;
840         u32 ret = 0;
841         u8 *cksum_key;
842         struct crypto_skcipher *cipher, *aux_cipher;
843         struct xdr_netobj our_hmac_obj;
844         u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
845         u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
846         int nblocks, blocksize, cbcbytes;
847         struct decryptor_desc desc;
848         unsigned int usage;
849 
850         if (kctx->initiate) {
851                 cipher = kctx->acceptor_enc;
852                 aux_cipher = kctx->acceptor_enc_aux;
853                 cksum_key = kctx->acceptor_integ;
854                 usage = KG_USAGE_ACCEPTOR_SEAL;
855         } else {
856                 cipher = kctx->initiator_enc;
857                 aux_cipher = kctx->initiator_enc_aux;
858                 cksum_key = kctx->initiator_integ;
859                 usage = KG_USAGE_INITIATOR_SEAL;
860         }
861         blocksize = crypto_skcipher_blocksize(cipher);
862 
863 
864         /* create a segment skipping the header and leaving out the checksum */
865         xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
866                                     (buf->len - offset - GSS_KRB5_TOK_HDR_LEN -
867                                      kctx->gk5e->cksumlength));
868 
869         nblocks = (subbuf.len + blocksize - 1) / blocksize;
870 
871         cbcbytes = 0;
872         if (nblocks > 2)
873                 cbcbytes = (nblocks - 2) * blocksize;
874 
875         memset(desc.iv, 0, sizeof(desc.iv));
876 
877         if (cbcbytes) {
878                 SKCIPHER_REQUEST_ON_STACK(req, aux_cipher);
879 
880                 desc.fragno = 0;
881                 desc.fraglen = 0;
882                 desc.req = req;
883 
884                 skcipher_request_set_tfm(req, aux_cipher);
885                 skcipher_request_set_callback(req, 0, NULL, NULL);
886 
887                 sg_init_table(desc.frags, 4);
888 
889                 ret = xdr_process_buf(&subbuf, 0, cbcbytes, decryptor, &desc);
890                 skcipher_request_zero(req);
891                 if (ret)
892                         goto out_err;
893         }
894 
895         /* Make sure IV carries forward from any CBC results. */
896         ret = gss_krb5_cts_crypt(cipher, &subbuf, cbcbytes, desc.iv, NULL, 0);
897         if (ret)
898                 goto out_err;
899 
900 
901         /* Calculate our hmac over the plaintext data */
902         our_hmac_obj.len = sizeof(our_hmac);
903         our_hmac_obj.data = our_hmac;
904 
905         ret = make_checksum_v2(kctx, NULL, 0, &subbuf, 0,
906                                cksum_key, usage, &our_hmac_obj);
907         if (ret)
908                 goto out_err;
909 
910         /* Get the packet's hmac value */
911         ret = read_bytes_from_xdr_buf(buf, buf->len - kctx->gk5e->cksumlength,
912                                       pkt_hmac, kctx->gk5e->cksumlength);
913         if (ret)
914                 goto out_err;
915 
916         if (memcmp(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
917                 ret = GSS_S_BAD_SIG;
918                 goto out_err;
919         }
920         *headskip = kctx->gk5e->conflen;
921         *tailskip = kctx->gk5e->cksumlength;
922 out_err:
923         if (ret && ret != GSS_S_BAD_SIG)
924                 ret = GSS_S_FAILURE;
925         return ret;
926 }
927 
928 /*
929  * Compute Kseq given the initial session key and the checksum.
930  * Set the key of the given cipher.
931  */
932 int
933 krb5_rc4_setup_seq_key(struct krb5_ctx *kctx, struct crypto_skcipher *cipher,
934                        unsigned char *cksum)
935 {
936         struct crypto_shash *hmac;
937         struct shash_desc *desc;
938         u8 Kseq[GSS_KRB5_MAX_KEYLEN];
939         u32 zeroconstant = 0;
940         int err;
941 
942         dprintk("%s: entered\n", __func__);
943 
944         hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
945         if (IS_ERR(hmac)) {
946                 dprintk("%s: error %ld, allocating hash '%s'\n",
947                         __func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
948                 return PTR_ERR(hmac);
949         }
950 
951         desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
952                        GFP_KERNEL);
953         if (!desc) {
954                 dprintk("%s: failed to allocate shash descriptor for '%s'\n",
955                         __func__, kctx->gk5e->cksum_name);
956                 crypto_free_shash(hmac);
957                 return -ENOMEM;
958         }
959 
960         desc->tfm = hmac;
961         desc->flags = 0;
962 
963         /* Compute intermediate Kseq from session key */
964         err = crypto_shash_setkey(hmac, kctx->Ksess, kctx->gk5e->keylength);
965         if (err)
966                 goto out_err;
967 
968         err = crypto_shash_digest(desc, (u8 *)&zeroconstant, 4, Kseq);
969         if (err)
970                 goto out_err;
971 
972         /* Compute final Kseq from the checksum and intermediate Kseq */
973         err = crypto_shash_setkey(hmac, Kseq, kctx->gk5e->keylength);
974         if (err)
975                 goto out_err;
976 
977         err = crypto_shash_digest(desc, cksum, 8, Kseq);
978         if (err)
979                 goto out_err;
980 
981         err = crypto_skcipher_setkey(cipher, Kseq, kctx->gk5e->keylength);
982         if (err)
983                 goto out_err;
984 
985         err = 0;
986 
987 out_err:
988         kzfree(desc);
989         crypto_free_shash(hmac);
990         dprintk("%s: returning %d\n", __func__, err);
991         return err;
992 }
993 
994 /*
995  * Compute Kcrypt given the initial session key and the plaintext seqnum.
996  * Set the key of cipher kctx->enc.
997  */
998 int
999 krb5_rc4_setup_enc_key(struct krb5_ctx *kctx, struct crypto_skcipher *cipher,
1000                        s32 seqnum)
1001 {
1002         struct crypto_shash *hmac;
1003         struct shash_desc *desc;
1004         u8 Kcrypt[GSS_KRB5_MAX_KEYLEN];
1005         u8 zeroconstant[4] = {0};
1006         u8 seqnumarray[4];
1007         int err, i;
1008 
1009         dprintk("%s: entered, seqnum %u\n", __func__, seqnum);
1010 
1011         hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
1012         if (IS_ERR(hmac)) {
1013                 dprintk("%s: error %ld, allocating hash '%s'\n",
1014                         __func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
1015                 return PTR_ERR(hmac);
1016         }
1017 
1018         desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
1019                        GFP_KERNEL);
1020         if (!desc) {
1021                 dprintk("%s: failed to allocate shash descriptor for '%s'\n",
1022                         __func__, kctx->gk5e->cksum_name);
1023                 crypto_free_shash(hmac);
1024                 return -ENOMEM;
1025         }
1026 
1027         desc->tfm = hmac;
1028         desc->flags = 0;
1029 
1030         /* Compute intermediate Kcrypt from session key */
1031         for (i = 0; i < kctx->gk5e->keylength; i++)
1032                 Kcrypt[i] = kctx->Ksess[i] ^ 0xf0;
1033 
1034         err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
1035         if (err)
1036                 goto out_err;
1037 
1038         err = crypto_shash_digest(desc, zeroconstant, 4, Kcrypt);
1039         if (err)
1040                 goto out_err;
1041 
1042         /* Compute final Kcrypt from the seqnum and intermediate Kcrypt */
1043         err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
1044         if (err)
1045                 goto out_err;
1046 
1047         seqnumarray[0] = (unsigned char) ((seqnum >> 24) & 0xff);
1048         seqnumarray[1] = (unsigned char) ((seqnum >> 16) & 0xff);
1049         seqnumarray[2] = (unsigned char) ((seqnum >> 8) & 0xff);
1050         seqnumarray[3] = (unsigned char) ((seqnum >> 0) & 0xff);
1051 
1052         err = crypto_shash_digest(desc, seqnumarray, 4, Kcrypt);
1053         if (err)
1054                 goto out_err;
1055 
1056         err = crypto_skcipher_setkey(cipher, Kcrypt, kctx->gk5e->keylength);
1057         if (err)
1058                 goto out_err;
1059 
1060         err = 0;
1061 
1062 out_err:
1063         kzfree(desc);
1064         crypto_free_shash(hmac);
1065         dprintk("%s: returning %d\n", __func__, err);
1066         return err;
1067 }
1068 
1069 

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