1 /*
2  * Neil Brown <neilb@cse.unsw.edu.au>
3  * J. Bruce Fields <bfields@umich.edu>
4  * Andy Adamson <andros@umich.edu>
5  * Dug Song <dugsong@monkey.org>
6  *
7  * RPCSEC_GSS server authentication.
8  * This implements RPCSEC_GSS as defined in rfc2203 (rpcsec_gss) and rfc2078
9  * (gssapi)
10  *
11  * The RPCSEC_GSS involves three stages:
12  *  1/ context creation
13  *  2/ data exchange
14  *  3/ context destruction
15  *
16  * Context creation is handled largely by upcalls to user-space.
17  *  In particular, GSS_Accept_sec_context is handled by an upcall
18  * Data exchange is handled entirely within the kernel
19  *  In particular, GSS_GetMIC, GSS_VerifyMIC, GSS_Seal, GSS_Unseal are in-kernel.
20  * Context destruction is handled in-kernel
21  *  GSS_Delete_sec_context is in-kernel
22  *
23  * Context creation is initiated by a RPCSEC_GSS_INIT request arriving.
24  * The context handle and gss_token are used as a key into the rpcsec_init cache.
25  * The content of this cache includes some of the outputs of GSS_Accept_sec_context,
26  * being major_status, minor_status, context_handle, reply_token.
27  * These are sent back to the client.
28  * Sequence window management is handled by the kernel.  The window size if currently
29  * a compile time constant.
30  *
31  * When user-space is happy that a context is established, it places an entry
32  * in the rpcsec_context cache. The key for this cache is the context_handle.
33  * The content includes:
34  *   uid/gidlist - for determining access rights
35  *   mechanism type
36  *   mechanism specific information, such as a key
37  *
38  */
39 
40 #include <linux/types.h>
41 #include <linux/module.h>
42 #include <linux/pagemap.h>
43 
44 #include <linux/sunrpc/auth_gss.h>
45 #include <linux/sunrpc/gss_err.h>
46 #include <linux/sunrpc/svcauth.h>
47 #include <linux/sunrpc/svcauth_gss.h>
48 #include <linux/sunrpc/cache.h>
49 
50 #ifdef RPC_DEBUG
51 # define RPCDBG_FACILITY	RPCDBG_AUTH
52 #endif
53 
54 /* The rpcsec_init cache is used for mapping RPCSEC_GSS_{,CONT_}INIT requests
55  * into replies.
56  *
57  * Key is context handle (\x if empty) and gss_token.
58  * Content is major_status minor_status (integers) context_handle, reply_token.
59  *
60  */
61 
62 static int netobj_equal(struct xdr_netobj *a, struct xdr_netobj *b)
63 {
64 	return a->len == b->len && 0 == memcmp(a->data, b->data, a->len);
65 }
66 
67 #define	RSI_HASHBITS	6
68 #define	RSI_HASHMAX	(1<<RSI_HASHBITS)
69 #define	RSI_HASHMASK	(RSI_HASHMAX-1)
70 
71 struct rsi {
72 	struct cache_head	h;
73 	struct xdr_netobj	in_handle, in_token;
74 	struct xdr_netobj	out_handle, out_token;
75 	int			major_status, minor_status;
76 };
77 
78 static struct cache_head *rsi_table[RSI_HASHMAX];
79 static struct cache_detail rsi_cache;
80 static struct rsi *rsi_update(struct rsi *new, struct rsi *old);
81 static struct rsi *rsi_lookup(struct rsi *item);
82 
83 static void rsi_free(struct rsi *rsii)
84 {
85 	kfree(rsii->in_handle.data);
86 	kfree(rsii->in_token.data);
87 	kfree(rsii->out_handle.data);
88 	kfree(rsii->out_token.data);
89 }
90 
91 static void rsi_put(struct kref *ref)
92 {
93 	struct rsi *rsii = container_of(ref, struct rsi, h.ref);
94 	rsi_free(rsii);
95 	kfree(rsii);
96 }
97 
98 static inline int rsi_hash(struct rsi *item)
99 {
100 	return hash_mem(item->in_handle.data, item->in_handle.len, RSI_HASHBITS)
101 	     ^ hash_mem(item->in_token.data, item->in_token.len, RSI_HASHBITS);
102 }
103 
104 static int rsi_match(struct cache_head *a, struct cache_head *b)
105 {
106 	struct rsi *item = container_of(a, struct rsi, h);
107 	struct rsi *tmp = container_of(b, struct rsi, h);
108 	return netobj_equal(&item->in_handle, &tmp->in_handle)
109 		&& netobj_equal(&item->in_token, &tmp->in_token);
110 }
111 
112 static int dup_to_netobj(struct xdr_netobj *dst, char *src, int len)
113 {
114 	dst->len = len;
115 	dst->data = (len ? kmemdup(src, len, GFP_KERNEL) : NULL);
116 	if (len && !dst->data)
117 		return -ENOMEM;
118 	return 0;
119 }
120 
121 static inline int dup_netobj(struct xdr_netobj *dst, struct xdr_netobj *src)
122 {
123 	return dup_to_netobj(dst, src->data, src->len);
124 }
125 
126 static void rsi_init(struct cache_head *cnew, struct cache_head *citem)
127 {
128 	struct rsi *new = container_of(cnew, struct rsi, h);
129 	struct rsi *item = container_of(citem, struct rsi, h);
130 
131 	new->out_handle.data = NULL;
132 	new->out_handle.len = 0;
133 	new->out_token.data = NULL;
134 	new->out_token.len = 0;
135 	new->in_handle.len = item->in_handle.len;
136 	item->in_handle.len = 0;
137 	new->in_token.len = item->in_token.len;
138 	item->in_token.len = 0;
139 	new->in_handle.data = item->in_handle.data;
140 	item->in_handle.data = NULL;
141 	new->in_token.data = item->in_token.data;
142 	item->in_token.data = NULL;
143 }
144 
145 static void update_rsi(struct cache_head *cnew, struct cache_head *citem)
146 {
147 	struct rsi *new = container_of(cnew, struct rsi, h);
148 	struct rsi *item = container_of(citem, struct rsi, h);
149 
150 	BUG_ON(new->out_handle.data || new->out_token.data);
151 	new->out_handle.len = item->out_handle.len;
152 	item->out_handle.len = 0;
153 	new->out_token.len = item->out_token.len;
154 	item->out_token.len = 0;
155 	new->out_handle.data = item->out_handle.data;
156 	item->out_handle.data = NULL;
157 	new->out_token.data = item->out_token.data;
158 	item->out_token.data = NULL;
159 
160 	new->major_status = item->major_status;
161 	new->minor_status = item->minor_status;
162 }
163 
164 static struct cache_head *rsi_alloc(void)
165 {
166 	struct rsi *rsii = kmalloc(sizeof(*rsii), GFP_KERNEL);
167 	if (rsii)
168 		return &rsii->h;
169 	else
170 		return NULL;
171 }
172 
173 static void rsi_request(struct cache_detail *cd,
174 		       struct cache_head *h,
175 		       char **bpp, int *blen)
176 {
177 	struct rsi *rsii = container_of(h, struct rsi, h);
178 
179 	qword_addhex(bpp, blen, rsii->in_handle.data, rsii->in_handle.len);
180 	qword_addhex(bpp, blen, rsii->in_token.data, rsii->in_token.len);
181 	(*bpp)[-1] = '\n';
182 }
183 
184 
185 static int rsi_parse(struct cache_detail *cd,
186 		    char *mesg, int mlen)
187 {
188 	/* context token expiry major minor context token */
189 	char *buf = mesg;
190 	char *ep;
191 	int len;
192 	struct rsi rsii, *rsip = NULL;
193 	time_t expiry;
194 	int status = -EINVAL;
195 
196 	memset(&rsii, 0, sizeof(rsii));
197 	/* handle */
198 	len = qword_get(&mesg, buf, mlen);
199 	if (len < 0)
200 		goto out;
201 	status = -ENOMEM;
202 	if (dup_to_netobj(&rsii.in_handle, buf, len))
203 		goto out;
204 
205 	/* token */
206 	len = qword_get(&mesg, buf, mlen);
207 	status = -EINVAL;
208 	if (len < 0)
209 		goto out;
210 	status = -ENOMEM;
211 	if (dup_to_netobj(&rsii.in_token, buf, len))
212 		goto out;
213 
214 	rsip = rsi_lookup(&rsii);
215 	if (!rsip)
216 		goto out;
217 
218 	rsii.h.flags = 0;
219 	/* expiry */
220 	expiry = get_expiry(&mesg);
221 	status = -EINVAL;
222 	if (expiry == 0)
223 		goto out;
224 
225 	/* major/minor */
226 	len = qword_get(&mesg, buf, mlen);
227 	if (len < 0)
228 		goto out;
229 	if (len == 0) {
230 		goto out;
231 	} else {
232 		rsii.major_status = simple_strtoul(buf, &ep, 10);
233 		if (*ep)
234 			goto out;
235 		len = qword_get(&mesg, buf, mlen);
236 		if (len <= 0)
237 			goto out;
238 		rsii.minor_status = simple_strtoul(buf, &ep, 10);
239 		if (*ep)
240 			goto out;
241 
242 		/* out_handle */
243 		len = qword_get(&mesg, buf, mlen);
244 		if (len < 0)
245 			goto out;
246 		status = -ENOMEM;
247 		if (dup_to_netobj(&rsii.out_handle, buf, len))
248 			goto out;
249 
250 		/* out_token */
251 		len = qword_get(&mesg, buf, mlen);
252 		status = -EINVAL;
253 		if (len < 0)
254 			goto out;
255 		status = -ENOMEM;
256 		if (dup_to_netobj(&rsii.out_token, buf, len))
257 			goto out;
258 	}
259 	rsii.h.expiry_time = expiry;
260 	rsip = rsi_update(&rsii, rsip);
261 	status = 0;
262 out:
263 	rsi_free(&rsii);
264 	if (rsip)
265 		cache_put(&rsip->h, &rsi_cache);
266 	else
267 		status = -ENOMEM;
268 	return status;
269 }
270 
271 static struct cache_detail rsi_cache = {
272 	.owner		= THIS_MODULE,
273 	.hash_size	= RSI_HASHMAX,
274 	.hash_table     = rsi_table,
275 	.name           = "auth.rpcsec.init",
276 	.cache_put      = rsi_put,
277 	.cache_request  = rsi_request,
278 	.cache_parse    = rsi_parse,
279 	.match		= rsi_match,
280 	.init		= rsi_init,
281 	.update		= update_rsi,
282 	.alloc		= rsi_alloc,
283 };
284 
285 static struct rsi *rsi_lookup(struct rsi *item)
286 {
287 	struct cache_head *ch;
288 	int hash = rsi_hash(item);
289 
290 	ch = sunrpc_cache_lookup(&rsi_cache, &item->h, hash);
291 	if (ch)
292 		return container_of(ch, struct rsi, h);
293 	else
294 		return NULL;
295 }
296 
297 static struct rsi *rsi_update(struct rsi *new, struct rsi *old)
298 {
299 	struct cache_head *ch;
300 	int hash = rsi_hash(new);
301 
302 	ch = sunrpc_cache_update(&rsi_cache, &new->h,
303 				 &old->h, hash);
304 	if (ch)
305 		return container_of(ch, struct rsi, h);
306 	else
307 		return NULL;
308 }
309 
310 
311 /*
312  * The rpcsec_context cache is used to store a context that is
313  * used in data exchange.
314  * The key is a context handle. The content is:
315  *  uid, gidlist, mechanism, service-set, mech-specific-data
316  */
317 
318 #define	RSC_HASHBITS	10
319 #define	RSC_HASHMAX	(1<<RSC_HASHBITS)
320 #define	RSC_HASHMASK	(RSC_HASHMAX-1)
321 
322 #define GSS_SEQ_WIN	128
323 
324 struct gss_svc_seq_data {
325 	/* highest seq number seen so far: */
326 	int			sd_max;
327 	/* for i such that sd_max-GSS_SEQ_WIN < i <= sd_max, the i-th bit of
328 	 * sd_win is nonzero iff sequence number i has been seen already: */
329 	unsigned long		sd_win[GSS_SEQ_WIN/BITS_PER_LONG];
330 	spinlock_t		sd_lock;
331 };
332 
333 struct rsc {
334 	struct cache_head	h;
335 	struct xdr_netobj	handle;
336 	struct svc_cred		cred;
337 	struct gss_svc_seq_data	seqdata;
338 	struct gss_ctx		*mechctx;
339 };
340 
341 static struct cache_head *rsc_table[RSC_HASHMAX];
342 static struct cache_detail rsc_cache;
343 static struct rsc *rsc_update(struct rsc *new, struct rsc *old);
344 static struct rsc *rsc_lookup(struct rsc *item);
345 
346 static void rsc_free(struct rsc *rsci)
347 {
348 	kfree(rsci->handle.data);
349 	if (rsci->mechctx)
350 		gss_delete_sec_context(&rsci->mechctx);
351 	if (rsci->cred.cr_group_info)
352 		put_group_info(rsci->cred.cr_group_info);
353 }
354 
355 static void rsc_put(struct kref *ref)
356 {
357 	struct rsc *rsci = container_of(ref, struct rsc, h.ref);
358 
359 	rsc_free(rsci);
360 	kfree(rsci);
361 }
362 
363 static inline int
364 rsc_hash(struct rsc *rsci)
365 {
366 	return hash_mem(rsci->handle.data, rsci->handle.len, RSC_HASHBITS);
367 }
368 
369 static int
370 rsc_match(struct cache_head *a, struct cache_head *b)
371 {
372 	struct rsc *new = container_of(a, struct rsc, h);
373 	struct rsc *tmp = container_of(b, struct rsc, h);
374 
375 	return netobj_equal(&new->handle, &tmp->handle);
376 }
377 
378 static void
379 rsc_init(struct cache_head *cnew, struct cache_head *ctmp)
380 {
381 	struct rsc *new = container_of(cnew, struct rsc, h);
382 	struct rsc *tmp = container_of(ctmp, struct rsc, h);
383 
384 	new->handle.len = tmp->handle.len;
385 	tmp->handle.len = 0;
386 	new->handle.data = tmp->handle.data;
387 	tmp->handle.data = NULL;
388 	new->mechctx = NULL;
389 	new->cred.cr_group_info = NULL;
390 }
391 
392 static void
393 update_rsc(struct cache_head *cnew, struct cache_head *ctmp)
394 {
395 	struct rsc *new = container_of(cnew, struct rsc, h);
396 	struct rsc *tmp = container_of(ctmp, struct rsc, h);
397 
398 	new->mechctx = tmp->mechctx;
399 	tmp->mechctx = NULL;
400 	memset(&new->seqdata, 0, sizeof(new->seqdata));
401 	spin_lock_init(&new->seqdata.sd_lock);
402 	new->cred = tmp->cred;
403 	tmp->cred.cr_group_info = NULL;
404 }
405 
406 static struct cache_head *
407 rsc_alloc(void)
408 {
409 	struct rsc *rsci = kmalloc(sizeof(*rsci), GFP_KERNEL);
410 	if (rsci)
411 		return &rsci->h;
412 	else
413 		return NULL;
414 }
415 
416 static int rsc_parse(struct cache_detail *cd,
417 		     char *mesg, int mlen)
418 {
419 	/* contexthandle expiry [ uid gid N <n gids> mechname ...mechdata... ] */
420 	char *buf = mesg;
421 	int len, rv;
422 	struct rsc rsci, *rscp = NULL;
423 	time_t expiry;
424 	int status = -EINVAL;
425 	struct gss_api_mech *gm = NULL;
426 
427 	memset(&rsci, 0, sizeof(rsci));
428 	/* context handle */
429 	len = qword_get(&mesg, buf, mlen);
430 	if (len < 0) goto out;
431 	status = -ENOMEM;
432 	if (dup_to_netobj(&rsci.handle, buf, len))
433 		goto out;
434 
435 	rsci.h.flags = 0;
436 	/* expiry */
437 	expiry = get_expiry(&mesg);
438 	status = -EINVAL;
439 	if (expiry == 0)
440 		goto out;
441 
442 	rscp = rsc_lookup(&rsci);
443 	if (!rscp)
444 		goto out;
445 
446 	/* uid, or NEGATIVE */
447 	rv = get_int(&mesg, &rsci.cred.cr_uid);
448 	if (rv == -EINVAL)
449 		goto out;
450 	if (rv == -ENOENT)
451 		set_bit(CACHE_NEGATIVE, &rsci.h.flags);
452 	else {
453 		int N, i;
454 
455 		/* gid */
456 		if (get_int(&mesg, &rsci.cred.cr_gid))
457 			goto out;
458 
459 		/* number of additional gid's */
460 		if (get_int(&mesg, &N))
461 			goto out;
462 		status = -ENOMEM;
463 		rsci.cred.cr_group_info = groups_alloc(N);
464 		if (rsci.cred.cr_group_info == NULL)
465 			goto out;
466 
467 		/* gid's */
468 		status = -EINVAL;
469 		for (i=0; i<N; i++) {
470 			gid_t gid;
471 			if (get_int(&mesg, &gid))
472 				goto out;
473 			GROUP_AT(rsci.cred.cr_group_info, i) = gid;
474 		}
475 
476 		/* mech name */
477 		len = qword_get(&mesg, buf, mlen);
478 		if (len < 0)
479 			goto out;
480 		gm = gss_mech_get_by_name(buf);
481 		status = -EOPNOTSUPP;
482 		if (!gm)
483 			goto out;
484 
485 		status = -EINVAL;
486 		/* mech-specific data: */
487 		len = qword_get(&mesg, buf, mlen);
488 		if (len < 0)
489 			goto out;
490 		status = gss_import_sec_context(buf, len, gm, &rsci.mechctx);
491 		if (status)
492 			goto out;
493 	}
494 	rsci.h.expiry_time = expiry;
495 	rscp = rsc_update(&rsci, rscp);
496 	status = 0;
497 out:
498 	gss_mech_put(gm);
499 	rsc_free(&rsci);
500 	if (rscp)
501 		cache_put(&rscp->h, &rsc_cache);
502 	else
503 		status = -ENOMEM;
504 	return status;
505 }
506 
507 static struct cache_detail rsc_cache = {
508 	.owner		= THIS_MODULE,
509 	.hash_size	= RSC_HASHMAX,
510 	.hash_table	= rsc_table,
511 	.name		= "auth.rpcsec.context",
512 	.cache_put	= rsc_put,
513 	.cache_parse	= rsc_parse,
514 	.match		= rsc_match,
515 	.init		= rsc_init,
516 	.update		= update_rsc,
517 	.alloc		= rsc_alloc,
518 };
519 
520 static struct rsc *rsc_lookup(struct rsc *item)
521 {
522 	struct cache_head *ch;
523 	int hash = rsc_hash(item);
524 
525 	ch = sunrpc_cache_lookup(&rsc_cache, &item->h, hash);
526 	if (ch)
527 		return container_of(ch, struct rsc, h);
528 	else
529 		return NULL;
530 }
531 
532 static struct rsc *rsc_update(struct rsc *new, struct rsc *old)
533 {
534 	struct cache_head *ch;
535 	int hash = rsc_hash(new);
536 
537 	ch = sunrpc_cache_update(&rsc_cache, &new->h,
538 				 &old->h, hash);
539 	if (ch)
540 		return container_of(ch, struct rsc, h);
541 	else
542 		return NULL;
543 }
544 
545 
546 static struct rsc *
547 gss_svc_searchbyctx(struct xdr_netobj *handle)
548 {
549 	struct rsc rsci;
550 	struct rsc *found;
551 
552 	memset(&rsci, 0, sizeof(rsci));
553 	if (dup_to_netobj(&rsci.handle, handle->data, handle->len))
554 		return NULL;
555 	found = rsc_lookup(&rsci);
556 	rsc_free(&rsci);
557 	if (!found)
558 		return NULL;
559 	if (cache_check(&rsc_cache, &found->h, NULL))
560 		return NULL;
561 	return found;
562 }
563 
564 /* Implements sequence number algorithm as specified in RFC 2203. */
565 static int
566 gss_check_seq_num(struct rsc *rsci, int seq_num)
567 {
568 	struct gss_svc_seq_data *sd = &rsci->seqdata;
569 
570 	spin_lock(&sd->sd_lock);
571 	if (seq_num > sd->sd_max) {
572 		if (seq_num >= sd->sd_max + GSS_SEQ_WIN) {
573 			memset(sd->sd_win,0,sizeof(sd->sd_win));
574 			sd->sd_max = seq_num;
575 		} else while (sd->sd_max < seq_num) {
576 			sd->sd_max++;
577 			__clear_bit(sd->sd_max % GSS_SEQ_WIN, sd->sd_win);
578 		}
579 		__set_bit(seq_num % GSS_SEQ_WIN, sd->sd_win);
580 		goto ok;
581 	} else if (seq_num <= sd->sd_max - GSS_SEQ_WIN) {
582 		goto drop;
583 	}
584 	/* sd_max - GSS_SEQ_WIN < seq_num <= sd_max */
585 	if (__test_and_set_bit(seq_num % GSS_SEQ_WIN, sd->sd_win))
586 		goto drop;
587 ok:
588 	spin_unlock(&sd->sd_lock);
589 	return 1;
590 drop:
591 	spin_unlock(&sd->sd_lock);
592 	return 0;
593 }
594 
595 static inline u32 round_up_to_quad(u32 i)
596 {
597 	return (i + 3 ) & ~3;
598 }
599 
600 static inline int
601 svc_safe_getnetobj(struct kvec *argv, struct xdr_netobj *o)
602 {
603 	int l;
604 
605 	if (argv->iov_len < 4)
606 		return -1;
607 	o->len = svc_getnl(argv);
608 	l = round_up_to_quad(o->len);
609 	if (argv->iov_len < l)
610 		return -1;
611 	o->data = argv->iov_base;
612 	argv->iov_base += l;
613 	argv->iov_len -= l;
614 	return 0;
615 }
616 
617 static inline int
618 svc_safe_putnetobj(struct kvec *resv, struct xdr_netobj *o)
619 {
620 	u8 *p;
621 
622 	if (resv->iov_len + 4 > PAGE_SIZE)
623 		return -1;
624 	svc_putnl(resv, o->len);
625 	p = resv->iov_base + resv->iov_len;
626 	resv->iov_len += round_up_to_quad(o->len);
627 	if (resv->iov_len > PAGE_SIZE)
628 		return -1;
629 	memcpy(p, o->data, o->len);
630 	memset(p + o->len, 0, round_up_to_quad(o->len) - o->len);
631 	return 0;
632 }
633 
634 /*
635  * Verify the checksum on the header and return SVC_OK on success.
636  * Otherwise, return SVC_DROP (in the case of a bad sequence number)
637  * or return SVC_DENIED and indicate error in authp.
638  */
639 static int
640 gss_verify_header(struct svc_rqst *rqstp, struct rsc *rsci,
641 		  __be32 *rpcstart, struct rpc_gss_wire_cred *gc, __be32 *authp)
642 {
643 	struct gss_ctx		*ctx_id = rsci->mechctx;
644 	struct xdr_buf		rpchdr;
645 	struct xdr_netobj	checksum;
646 	u32			flavor = 0;
647 	struct kvec		*argv = &rqstp->rq_arg.head[0];
648 	struct kvec		iov;
649 
650 	/* data to compute the checksum over: */
651 	iov.iov_base = rpcstart;
652 	iov.iov_len = (u8 *)argv->iov_base - (u8 *)rpcstart;
653 	xdr_buf_from_iov(&iov, &rpchdr);
654 
655 	*authp = rpc_autherr_badverf;
656 	if (argv->iov_len < 4)
657 		return SVC_DENIED;
658 	flavor = svc_getnl(argv);
659 	if (flavor != RPC_AUTH_GSS)
660 		return SVC_DENIED;
661 	if (svc_safe_getnetobj(argv, &checksum))
662 		return SVC_DENIED;
663 
664 	if (rqstp->rq_deferred) /* skip verification of revisited request */
665 		return SVC_OK;
666 	if (gss_verify_mic(ctx_id, &rpchdr, &checksum) != GSS_S_COMPLETE) {
667 		*authp = rpcsec_gsserr_credproblem;
668 		return SVC_DENIED;
669 	}
670 
671 	if (gc->gc_seq > MAXSEQ) {
672 		dprintk("RPC:       svcauth_gss: discarding request with "
673 				"large sequence number %d\n", gc->gc_seq);
674 		*authp = rpcsec_gsserr_ctxproblem;
675 		return SVC_DENIED;
676 	}
677 	if (!gss_check_seq_num(rsci, gc->gc_seq)) {
678 		dprintk("RPC:       svcauth_gss: discarding request with "
679 				"old sequence number %d\n", gc->gc_seq);
680 		return SVC_DROP;
681 	}
682 	return SVC_OK;
683 }
684 
685 static int
686 gss_write_null_verf(struct svc_rqst *rqstp)
687 {
688 	__be32     *p;
689 
690 	svc_putnl(rqstp->rq_res.head, RPC_AUTH_NULL);
691 	p = rqstp->rq_res.head->iov_base + rqstp->rq_res.head->iov_len;
692 	/* don't really need to check if head->iov_len > PAGE_SIZE ... */
693 	*p++ = 0;
694 	if (!xdr_ressize_check(rqstp, p))
695 		return -1;
696 	return 0;
697 }
698 
699 static int
700 gss_write_verf(struct svc_rqst *rqstp, struct gss_ctx *ctx_id, u32 seq)
701 {
702 	__be32			xdr_seq;
703 	u32			maj_stat;
704 	struct xdr_buf		verf_data;
705 	struct xdr_netobj	mic;
706 	__be32			*p;
707 	struct kvec		iov;
708 
709 	svc_putnl(rqstp->rq_res.head, RPC_AUTH_GSS);
710 	xdr_seq = htonl(seq);
711 
712 	iov.iov_base = &xdr_seq;
713 	iov.iov_len = sizeof(xdr_seq);
714 	xdr_buf_from_iov(&iov, &verf_data);
715 	p = rqstp->rq_res.head->iov_base + rqstp->rq_res.head->iov_len;
716 	mic.data = (u8 *)(p + 1);
717 	maj_stat = gss_get_mic(ctx_id, &verf_data, &mic);
718 	if (maj_stat != GSS_S_COMPLETE)
719 		return -1;
720 	*p++ = htonl(mic.len);
721 	memset((u8 *)p + mic.len, 0, round_up_to_quad(mic.len) - mic.len);
722 	p += XDR_QUADLEN(mic.len);
723 	if (!xdr_ressize_check(rqstp, p))
724 		return -1;
725 	return 0;
726 }
727 
728 struct gss_domain {
729 	struct auth_domain	h;
730 	u32			pseudoflavor;
731 };
732 
733 static struct auth_domain *
734 find_gss_auth_domain(struct gss_ctx *ctx, u32 svc)
735 {
736 	char *name;
737 
738 	name = gss_service_to_auth_domain_name(ctx->mech_type, svc);
739 	if (!name)
740 		return NULL;
741 	return auth_domain_find(name);
742 }
743 
744 static struct auth_ops svcauthops_gss;
745 
746 u32 svcauth_gss_flavor(struct auth_domain *dom)
747 {
748 	struct gss_domain *gd = container_of(dom, struct gss_domain, h);
749 
750 	return gd->pseudoflavor;
751 }
752 
753 EXPORT_SYMBOL(svcauth_gss_flavor);
754 
755 int
756 svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name)
757 {
758 	struct gss_domain	*new;
759 	struct auth_domain	*test;
760 	int			stat = -ENOMEM;
761 
762 	new = kmalloc(sizeof(*new), GFP_KERNEL);
763 	if (!new)
764 		goto out;
765 	kref_init(&new->h.ref);
766 	new->h.name = kstrdup(name, GFP_KERNEL);
767 	if (!new->h.name)
768 		goto out_free_dom;
769 	new->h.flavour = &svcauthops_gss;
770 	new->pseudoflavor = pseudoflavor;
771 
772 	stat = 0;
773 	test = auth_domain_lookup(name, &new->h);
774 	if (test != &new->h) { /* Duplicate registration */
775 		auth_domain_put(test);
776 		kfree(new->h.name);
777 		goto out_free_dom;
778 	}
779 	return 0;
780 
781 out_free_dom:
782 	kfree(new);
783 out:
784 	return stat;
785 }
786 
787 EXPORT_SYMBOL(svcauth_gss_register_pseudoflavor);
788 
789 static inline int
790 read_u32_from_xdr_buf(struct xdr_buf *buf, int base, u32 *obj)
791 {
792 	__be32  raw;
793 	int     status;
794 
795 	status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
796 	if (status)
797 		return status;
798 	*obj = ntohl(raw);
799 	return 0;
800 }
801 
802 /* It would be nice if this bit of code could be shared with the client.
803  * Obstacles:
804  *	The client shouldn't malloc(), would have to pass in own memory.
805  *	The server uses base of head iovec as read pointer, while the
806  *	client uses separate pointer. */
807 static int
808 unwrap_integ_data(struct xdr_buf *buf, u32 seq, struct gss_ctx *ctx)
809 {
810 	int stat = -EINVAL;
811 	u32 integ_len, maj_stat;
812 	struct xdr_netobj mic;
813 	struct xdr_buf integ_buf;
814 
815 	integ_len = svc_getnl(&buf->head[0]);
816 	if (integ_len & 3)
817 		return stat;
818 	if (integ_len > buf->len)
819 		return stat;
820 	if (xdr_buf_subsegment(buf, &integ_buf, 0, integ_len))
821 		BUG();
822 	/* copy out mic... */
823 	if (read_u32_from_xdr_buf(buf, integ_len, &mic.len))
824 		BUG();
825 	if (mic.len > RPC_MAX_AUTH_SIZE)
826 		return stat;
827 	mic.data = kmalloc(mic.len, GFP_KERNEL);
828 	if (!mic.data)
829 		return stat;
830 	if (read_bytes_from_xdr_buf(buf, integ_len + 4, mic.data, mic.len))
831 		goto out;
832 	maj_stat = gss_verify_mic(ctx, &integ_buf, &mic);
833 	if (maj_stat != GSS_S_COMPLETE)
834 		goto out;
835 	if (svc_getnl(&buf->head[0]) != seq)
836 		goto out;
837 	stat = 0;
838 out:
839 	kfree(mic.data);
840 	return stat;
841 }
842 
843 static inline int
844 total_buf_len(struct xdr_buf *buf)
845 {
846 	return buf->head[0].iov_len + buf->page_len + buf->tail[0].iov_len;
847 }
848 
849 static void
850 fix_priv_head(struct xdr_buf *buf, int pad)
851 {
852 	if (buf->page_len == 0) {
853 		/* We need to adjust head and buf->len in tandem in this
854 		 * case to make svc_defer() work--it finds the original
855 		 * buffer start using buf->len - buf->head[0].iov_len. */
856 		buf->head[0].iov_len -= pad;
857 	}
858 }
859 
860 static int
861 unwrap_priv_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct gss_ctx *ctx)
862 {
863 	u32 priv_len, maj_stat;
864 	int pad, saved_len, remaining_len, offset;
865 
866 	rqstp->rq_splice_ok = 0;
867 
868 	priv_len = svc_getnl(&buf->head[0]);
869 	if (rqstp->rq_deferred) {
870 		/* Already decrypted last time through! The sequence number
871 		 * check at out_seq is unnecessary but harmless: */
872 		goto out_seq;
873 	}
874 	/* buf->len is the number of bytes from the original start of the
875 	 * request to the end, where head[0].iov_len is just the bytes
876 	 * not yet read from the head, so these two values are different: */
877 	remaining_len = total_buf_len(buf);
878 	if (priv_len > remaining_len)
879 		return -EINVAL;
880 	pad = remaining_len - priv_len;
881 	buf->len -= pad;
882 	fix_priv_head(buf, pad);
883 
884 	/* Maybe it would be better to give gss_unwrap a length parameter: */
885 	saved_len = buf->len;
886 	buf->len = priv_len;
887 	maj_stat = gss_unwrap(ctx, 0, buf);
888 	pad = priv_len - buf->len;
889 	buf->len = saved_len;
890 	buf->len -= pad;
891 	/* The upper layers assume the buffer is aligned on 4-byte boundaries.
892 	 * In the krb5p case, at least, the data ends up offset, so we need to
893 	 * move it around. */
894 	/* XXX: This is very inefficient.  It would be better to either do
895 	 * this while we encrypt, or maybe in the receive code, if we can peak
896 	 * ahead and work out the service and mechanism there. */
897 	offset = buf->head[0].iov_len % 4;
898 	if (offset) {
899 		buf->buflen = RPCSVC_MAXPAYLOAD;
900 		xdr_shift_buf(buf, offset);
901 		fix_priv_head(buf, pad);
902 	}
903 	if (maj_stat != GSS_S_COMPLETE)
904 		return -EINVAL;
905 out_seq:
906 	if (svc_getnl(&buf->head[0]) != seq)
907 		return -EINVAL;
908 	return 0;
909 }
910 
911 struct gss_svc_data {
912 	/* decoded gss client cred: */
913 	struct rpc_gss_wire_cred	clcred;
914 	/* save a pointer to the beginning of the encoded verifier,
915 	 * for use in encryption/checksumming in svcauth_gss_release: */
916 	__be32				*verf_start;
917 	struct rsc			*rsci;
918 };
919 
920 static int
921 svcauth_gss_set_client(struct svc_rqst *rqstp)
922 {
923 	struct gss_svc_data *svcdata = rqstp->rq_auth_data;
924 	struct rsc *rsci = svcdata->rsci;
925 	struct rpc_gss_wire_cred *gc = &svcdata->clcred;
926 	int stat;
927 
928 	/*
929 	 * A gss export can be specified either by:
930 	 * 	export	*(sec=krb5,rw)
931 	 * or by
932 	 * 	export gss/krb5(rw)
933 	 * The latter is deprecated; but for backwards compatibility reasons
934 	 * the nfsd code will still fall back on trying it if the former
935 	 * doesn't work; so we try to make both available to nfsd, below.
936 	 */
937 	rqstp->rq_gssclient = find_gss_auth_domain(rsci->mechctx, gc->gc_svc);
938 	if (rqstp->rq_gssclient == NULL)
939 		return SVC_DENIED;
940 	stat = svcauth_unix_set_client(rqstp);
941 	if (stat == SVC_DROP)
942 		return stat;
943 	return SVC_OK;
944 }
945 
946 static inline int
947 gss_write_init_verf(struct svc_rqst *rqstp, struct rsi *rsip)
948 {
949 	struct rsc *rsci;
950 	int        rc;
951 
952 	if (rsip->major_status != GSS_S_COMPLETE)
953 		return gss_write_null_verf(rqstp);
954 	rsci = gss_svc_searchbyctx(&rsip->out_handle);
955 	if (rsci == NULL) {
956 		rsip->major_status = GSS_S_NO_CONTEXT;
957 		return gss_write_null_verf(rqstp);
958 	}
959 	rc = gss_write_verf(rqstp, rsci->mechctx, GSS_SEQ_WIN);
960 	cache_put(&rsci->h, &rsc_cache);
961 	return rc;
962 }
963 
964 /*
965  * Having read the cred already and found we're in the context
966  * initiation case, read the verifier and initiate (or check the results
967  * of) upcalls to userspace for help with context initiation.  If
968  * the upcall results are available, write the verifier and result.
969  * Otherwise, drop the request pending an answer to the upcall.
970  */
971 static int svcauth_gss_handle_init(struct svc_rqst *rqstp,
972 			struct rpc_gss_wire_cred *gc, __be32 *authp)
973 {
974 	struct kvec *argv = &rqstp->rq_arg.head[0];
975 	struct kvec *resv = &rqstp->rq_res.head[0];
976 	struct xdr_netobj tmpobj;
977 	struct rsi *rsip, rsikey;
978 	int ret;
979 
980 	/* Read the verifier; should be NULL: */
981 	*authp = rpc_autherr_badverf;
982 	if (argv->iov_len < 2 * 4)
983 		return SVC_DENIED;
984 	if (svc_getnl(argv) != RPC_AUTH_NULL)
985 		return SVC_DENIED;
986 	if (svc_getnl(argv) != 0)
987 		return SVC_DENIED;
988 
989 	/* Martial context handle and token for upcall: */
990 	*authp = rpc_autherr_badcred;
991 	if (gc->gc_proc == RPC_GSS_PROC_INIT && gc->gc_ctx.len != 0)
992 		return SVC_DENIED;
993 	memset(&rsikey, 0, sizeof(rsikey));
994 	if (dup_netobj(&rsikey.in_handle, &gc->gc_ctx))
995 		return SVC_DROP;
996 	*authp = rpc_autherr_badverf;
997 	if (svc_safe_getnetobj(argv, &tmpobj)) {
998 		kfree(rsikey.in_handle.data);
999 		return SVC_DENIED;
1000 	}
1001 	if (dup_netobj(&rsikey.in_token, &tmpobj)) {
1002 		kfree(rsikey.in_handle.data);
1003 		return SVC_DROP;
1004 	}
1005 
1006 	/* Perform upcall, or find upcall result: */
1007 	rsip = rsi_lookup(&rsikey);
1008 	rsi_free(&rsikey);
1009 	if (!rsip)
1010 		return SVC_DROP;
1011 	switch (cache_check(&rsi_cache, &rsip->h, &rqstp->rq_chandle)) {
1012 	case -EAGAIN:
1013 	case -ETIMEDOUT:
1014 	case -ENOENT:
1015 		/* No upcall result: */
1016 		return SVC_DROP;
1017 	case 0:
1018 		ret = SVC_DROP;
1019 		/* Got an answer to the upcall; use it: */
1020 		if (gss_write_init_verf(rqstp, rsip))
1021 			goto out;
1022 		if (resv->iov_len + 4 > PAGE_SIZE)
1023 			goto out;
1024 		svc_putnl(resv, RPC_SUCCESS);
1025 		if (svc_safe_putnetobj(resv, &rsip->out_handle))
1026 			goto out;
1027 		if (resv->iov_len + 3 * 4 > PAGE_SIZE)
1028 			goto out;
1029 		svc_putnl(resv, rsip->major_status);
1030 		svc_putnl(resv, rsip->minor_status);
1031 		svc_putnl(resv, GSS_SEQ_WIN);
1032 		if (svc_safe_putnetobj(resv, &rsip->out_token))
1033 			goto out;
1034 	}
1035 	ret = SVC_COMPLETE;
1036 out:
1037 	cache_put(&rsip->h, &rsi_cache);
1038 	return ret;
1039 }
1040 
1041 /*
1042  * Accept an rpcsec packet.
1043  * If context establishment, punt to user space
1044  * If data exchange, verify/decrypt
1045  * If context destruction, handle here
1046  * In the context establishment and destruction case we encode
1047  * response here and return SVC_COMPLETE.
1048  */
1049 static int
1050 svcauth_gss_accept(struct svc_rqst *rqstp, __be32 *authp)
1051 {
1052 	struct kvec	*argv = &rqstp->rq_arg.head[0];
1053 	struct kvec	*resv = &rqstp->rq_res.head[0];
1054 	u32		crlen;
1055 	struct gss_svc_data *svcdata = rqstp->rq_auth_data;
1056 	struct rpc_gss_wire_cred *gc;
1057 	struct rsc	*rsci = NULL;
1058 	__be32		*rpcstart;
1059 	__be32		*reject_stat = resv->iov_base + resv->iov_len;
1060 	int		ret;
1061 
1062 	dprintk("RPC:       svcauth_gss: argv->iov_len = %zd\n",
1063 			argv->iov_len);
1064 
1065 	*authp = rpc_autherr_badcred;
1066 	if (!svcdata)
1067 		svcdata = kmalloc(sizeof(*svcdata), GFP_KERNEL);
1068 	if (!svcdata)
1069 		goto auth_err;
1070 	rqstp->rq_auth_data = svcdata;
1071 	svcdata->verf_start = NULL;
1072 	svcdata->rsci = NULL;
1073 	gc = &svcdata->clcred;
1074 
1075 	/* start of rpc packet is 7 u32's back from here:
1076 	 * xid direction rpcversion prog vers proc flavour
1077 	 */
1078 	rpcstart = argv->iov_base;
1079 	rpcstart -= 7;
1080 
1081 	/* credential is:
1082 	 *   version(==1), proc(0,1,2,3), seq, service (1,2,3), handle
1083 	 * at least 5 u32s, and is preceeded by length, so that makes 6.
1084 	 */
1085 
1086 	if (argv->iov_len < 5 * 4)
1087 		goto auth_err;
1088 	crlen = svc_getnl(argv);
1089 	if (svc_getnl(argv) != RPC_GSS_VERSION)
1090 		goto auth_err;
1091 	gc->gc_proc = svc_getnl(argv);
1092 	gc->gc_seq = svc_getnl(argv);
1093 	gc->gc_svc = svc_getnl(argv);
1094 	if (svc_safe_getnetobj(argv, &gc->gc_ctx))
1095 		goto auth_err;
1096 	if (crlen != round_up_to_quad(gc->gc_ctx.len) + 5 * 4)
1097 		goto auth_err;
1098 
1099 	if ((gc->gc_proc != RPC_GSS_PROC_DATA) && (rqstp->rq_proc != 0))
1100 		goto auth_err;
1101 
1102 	*authp = rpc_autherr_badverf;
1103 	switch (gc->gc_proc) {
1104 	case RPC_GSS_PROC_INIT:
1105 	case RPC_GSS_PROC_CONTINUE_INIT:
1106 		return svcauth_gss_handle_init(rqstp, gc, authp);
1107 	case RPC_GSS_PROC_DATA:
1108 	case RPC_GSS_PROC_DESTROY:
1109 		/* Look up the context, and check the verifier: */
1110 		*authp = rpcsec_gsserr_credproblem;
1111 		rsci = gss_svc_searchbyctx(&gc->gc_ctx);
1112 		if (!rsci)
1113 			goto auth_err;
1114 		switch (gss_verify_header(rqstp, rsci, rpcstart, gc, authp)) {
1115 		case SVC_OK:
1116 			break;
1117 		case SVC_DENIED:
1118 			goto auth_err;
1119 		case SVC_DROP:
1120 			goto drop;
1121 		}
1122 		break;
1123 	default:
1124 		*authp = rpc_autherr_rejectedcred;
1125 		goto auth_err;
1126 	}
1127 
1128 	/* now act upon the command: */
1129 	switch (gc->gc_proc) {
1130 	case RPC_GSS_PROC_DESTROY:
1131 		if (gss_write_verf(rqstp, rsci->mechctx, gc->gc_seq))
1132 			goto auth_err;
1133 		set_bit(CACHE_NEGATIVE, &rsci->h.flags);
1134 		if (resv->iov_len + 4 > PAGE_SIZE)
1135 			goto drop;
1136 		svc_putnl(resv, RPC_SUCCESS);
1137 		goto complete;
1138 	case RPC_GSS_PROC_DATA:
1139 		*authp = rpcsec_gsserr_ctxproblem;
1140 		svcdata->verf_start = resv->iov_base + resv->iov_len;
1141 		if (gss_write_verf(rqstp, rsci->mechctx, gc->gc_seq))
1142 			goto auth_err;
1143 		rqstp->rq_cred = rsci->cred;
1144 		get_group_info(rsci->cred.cr_group_info);
1145 		*authp = rpc_autherr_badcred;
1146 		switch (gc->gc_svc) {
1147 		case RPC_GSS_SVC_NONE:
1148 			break;
1149 		case RPC_GSS_SVC_INTEGRITY:
1150 			if (unwrap_integ_data(&rqstp->rq_arg,
1151 					gc->gc_seq, rsci->mechctx))
1152 				goto auth_err;
1153 			/* placeholders for length and seq. number: */
1154 			svc_putnl(resv, 0);
1155 			svc_putnl(resv, 0);
1156 			break;
1157 		case RPC_GSS_SVC_PRIVACY:
1158 			if (unwrap_priv_data(rqstp, &rqstp->rq_arg,
1159 					gc->gc_seq, rsci->mechctx))
1160 				goto auth_err;
1161 			/* placeholders for length and seq. number: */
1162 			svc_putnl(resv, 0);
1163 			svc_putnl(resv, 0);
1164 			break;
1165 		default:
1166 			goto auth_err;
1167 		}
1168 		svcdata->rsci = rsci;
1169 		cache_get(&rsci->h);
1170 		rqstp->rq_flavor = gss_svc_to_pseudoflavor(
1171 					rsci->mechctx->mech_type, gc->gc_svc);
1172 		ret = SVC_OK;
1173 		goto out;
1174 	}
1175 auth_err:
1176 	/* Restore write pointer to its original value: */
1177 	xdr_ressize_check(rqstp, reject_stat);
1178 	ret = SVC_DENIED;
1179 	goto out;
1180 complete:
1181 	ret = SVC_COMPLETE;
1182 	goto out;
1183 drop:
1184 	ret = SVC_DROP;
1185 out:
1186 	if (rsci)
1187 		cache_put(&rsci->h, &rsc_cache);
1188 	return ret;
1189 }
1190 
1191 static __be32 *
1192 svcauth_gss_prepare_to_wrap(struct xdr_buf *resbuf, struct gss_svc_data *gsd)
1193 {
1194 	__be32 *p;
1195 	u32 verf_len;
1196 
1197 	p = gsd->verf_start;
1198 	gsd->verf_start = NULL;
1199 
1200 	/* If the reply stat is nonzero, don't wrap: */
1201 	if (*(p-1) != rpc_success)
1202 		return NULL;
1203 	/* Skip the verifier: */
1204 	p += 1;
1205 	verf_len = ntohl(*p++);
1206 	p += XDR_QUADLEN(verf_len);
1207 	/* move accept_stat to right place: */
1208 	memcpy(p, p + 2, 4);
1209 	/* Also don't wrap if the accept stat is nonzero: */
1210 	if (*p != rpc_success) {
1211 		resbuf->head[0].iov_len -= 2 * 4;
1212 		return NULL;
1213 	}
1214 	p++;
1215 	return p;
1216 }
1217 
1218 static inline int
1219 svcauth_gss_wrap_resp_integ(struct svc_rqst *rqstp)
1220 {
1221 	struct gss_svc_data *gsd = (struct gss_svc_data *)rqstp->rq_auth_data;
1222 	struct rpc_gss_wire_cred *gc = &gsd->clcred;
1223 	struct xdr_buf *resbuf = &rqstp->rq_res;
1224 	struct xdr_buf integ_buf;
1225 	struct xdr_netobj mic;
1226 	struct kvec *resv;
1227 	__be32 *p;
1228 	int integ_offset, integ_len;
1229 	int stat = -EINVAL;
1230 
1231 	p = svcauth_gss_prepare_to_wrap(resbuf, gsd);
1232 	if (p == NULL)
1233 		goto out;
1234 	integ_offset = (u8 *)(p + 1) - (u8 *)resbuf->head[0].iov_base;
1235 	integ_len = resbuf->len - integ_offset;
1236 	BUG_ON(integ_len % 4);
1237 	*p++ = htonl(integ_len);
1238 	*p++ = htonl(gc->gc_seq);
1239 	if (xdr_buf_subsegment(resbuf, &integ_buf, integ_offset,
1240 				integ_len))
1241 		BUG();
1242 	if (resbuf->tail[0].iov_base == NULL) {
1243 		if (resbuf->head[0].iov_len + RPC_MAX_AUTH_SIZE > PAGE_SIZE)
1244 			goto out_err;
1245 		resbuf->tail[0].iov_base = resbuf->head[0].iov_base
1246 						+ resbuf->head[0].iov_len;
1247 		resbuf->tail[0].iov_len = 0;
1248 		resv = &resbuf->tail[0];
1249 	} else {
1250 		resv = &resbuf->tail[0];
1251 	}
1252 	mic.data = (u8 *)resv->iov_base + resv->iov_len + 4;
1253 	if (gss_get_mic(gsd->rsci->mechctx, &integ_buf, &mic))
1254 		goto out_err;
1255 	svc_putnl(resv, mic.len);
1256 	memset(mic.data + mic.len, 0,
1257 			round_up_to_quad(mic.len) - mic.len);
1258 	resv->iov_len += XDR_QUADLEN(mic.len) << 2;
1259 	/* not strictly required: */
1260 	resbuf->len += XDR_QUADLEN(mic.len) << 2;
1261 	BUG_ON(resv->iov_len > PAGE_SIZE);
1262 out:
1263 	stat = 0;
1264 out_err:
1265 	return stat;
1266 }
1267 
1268 static inline int
1269 svcauth_gss_wrap_resp_priv(struct svc_rqst *rqstp)
1270 {
1271 	struct gss_svc_data *gsd = (struct gss_svc_data *)rqstp->rq_auth_data;
1272 	struct rpc_gss_wire_cred *gc = &gsd->clcred;
1273 	struct xdr_buf *resbuf = &rqstp->rq_res;
1274 	struct page **inpages = NULL;
1275 	__be32 *p, *len;
1276 	int offset;
1277 	int pad;
1278 
1279 	p = svcauth_gss_prepare_to_wrap(resbuf, gsd);
1280 	if (p == NULL)
1281 		return 0;
1282 	len = p++;
1283 	offset = (u8 *)p - (u8 *)resbuf->head[0].iov_base;
1284 	*p++ = htonl(gc->gc_seq);
1285 	inpages = resbuf->pages;
1286 	/* XXX: Would be better to write some xdr helper functions for
1287 	 * nfs{2,3,4}xdr.c that place the data right, instead of copying: */
1288 	if (resbuf->tail[0].iov_base) {
1289 		BUG_ON(resbuf->tail[0].iov_base >= resbuf->head[0].iov_base
1290 							+ PAGE_SIZE);
1291 		BUG_ON(resbuf->tail[0].iov_base < resbuf->head[0].iov_base);
1292 		if (resbuf->tail[0].iov_len + resbuf->head[0].iov_len
1293 				+ 2 * RPC_MAX_AUTH_SIZE > PAGE_SIZE)
1294 			return -ENOMEM;
1295 		memmove(resbuf->tail[0].iov_base + RPC_MAX_AUTH_SIZE,
1296 			resbuf->tail[0].iov_base,
1297 			resbuf->tail[0].iov_len);
1298 		resbuf->tail[0].iov_base += RPC_MAX_AUTH_SIZE;
1299 	}
1300 	if (resbuf->tail[0].iov_base == NULL) {
1301 		if (resbuf->head[0].iov_len + 2*RPC_MAX_AUTH_SIZE > PAGE_SIZE)
1302 			return -ENOMEM;
1303 		resbuf->tail[0].iov_base = resbuf->head[0].iov_base
1304 			+ resbuf->head[0].iov_len + RPC_MAX_AUTH_SIZE;
1305 		resbuf->tail[0].iov_len = 0;
1306 	}
1307 	if (gss_wrap(gsd->rsci->mechctx, offset, resbuf, inpages))
1308 		return -ENOMEM;
1309 	*len = htonl(resbuf->len - offset);
1310 	pad = 3 - ((resbuf->len - offset - 1)&3);
1311 	p = (__be32 *)(resbuf->tail[0].iov_base + resbuf->tail[0].iov_len);
1312 	memset(p, 0, pad);
1313 	resbuf->tail[0].iov_len += pad;
1314 	resbuf->len += pad;
1315 	return 0;
1316 }
1317 
1318 static int
1319 svcauth_gss_release(struct svc_rqst *rqstp)
1320 {
1321 	struct gss_svc_data *gsd = (struct gss_svc_data *)rqstp->rq_auth_data;
1322 	struct rpc_gss_wire_cred *gc = &gsd->clcred;
1323 	struct xdr_buf *resbuf = &rqstp->rq_res;
1324 	int stat = -EINVAL;
1325 
1326 	if (gc->gc_proc != RPC_GSS_PROC_DATA)
1327 		goto out;
1328 	/* Release can be called twice, but we only wrap once. */
1329 	if (gsd->verf_start == NULL)
1330 		goto out;
1331 	/* normally not set till svc_send, but we need it here: */
1332 	/* XXX: what for?  Do we mess it up the moment we call svc_putu32
1333 	 * or whatever? */
1334 	resbuf->len = total_buf_len(resbuf);
1335 	switch (gc->gc_svc) {
1336 	case RPC_GSS_SVC_NONE:
1337 		break;
1338 	case RPC_GSS_SVC_INTEGRITY:
1339 		stat = svcauth_gss_wrap_resp_integ(rqstp);
1340 		if (stat)
1341 			goto out_err;
1342 		break;
1343 	case RPC_GSS_SVC_PRIVACY:
1344 		stat = svcauth_gss_wrap_resp_priv(rqstp);
1345 		if (stat)
1346 			goto out_err;
1347 		break;
1348 	default:
1349 		goto out_err;
1350 	}
1351 
1352 out:
1353 	stat = 0;
1354 out_err:
1355 	if (rqstp->rq_client)
1356 		auth_domain_put(rqstp->rq_client);
1357 	rqstp->rq_client = NULL;
1358 	if (rqstp->rq_gssclient)
1359 		auth_domain_put(rqstp->rq_gssclient);
1360 	rqstp->rq_gssclient = NULL;
1361 	if (rqstp->rq_cred.cr_group_info)
1362 		put_group_info(rqstp->rq_cred.cr_group_info);
1363 	rqstp->rq_cred.cr_group_info = NULL;
1364 	if (gsd->rsci)
1365 		cache_put(&gsd->rsci->h, &rsc_cache);
1366 	gsd->rsci = NULL;
1367 
1368 	return stat;
1369 }
1370 
1371 static void
1372 svcauth_gss_domain_release(struct auth_domain *dom)
1373 {
1374 	struct gss_domain *gd = container_of(dom, struct gss_domain, h);
1375 
1376 	kfree(dom->name);
1377 	kfree(gd);
1378 }
1379 
1380 static struct auth_ops svcauthops_gss = {
1381 	.name		= "rpcsec_gss",
1382 	.owner		= THIS_MODULE,
1383 	.flavour	= RPC_AUTH_GSS,
1384 	.accept		= svcauth_gss_accept,
1385 	.release	= svcauth_gss_release,
1386 	.domain_release = svcauth_gss_domain_release,
1387 	.set_client	= svcauth_gss_set_client,
1388 };
1389 
1390 int
1391 gss_svc_init(void)
1392 {
1393 	int rv = svc_auth_register(RPC_AUTH_GSS, &svcauthops_gss);
1394 	if (rv)
1395 		return rv;
1396 	rv = cache_register(&rsc_cache);
1397 	if (rv)
1398 		goto out1;
1399 	rv = cache_register(&rsi_cache);
1400 	if (rv)
1401 		goto out2;
1402 	return 0;
1403 out2:
1404 	cache_unregister(&rsc_cache);
1405 out1:
1406 	svc_auth_unregister(RPC_AUTH_GSS);
1407 	return rv;
1408 }
1409 
1410 void
1411 gss_svc_shutdown(void)
1412 {
1413 	cache_unregister(&rsc_cache);
1414 	cache_unregister(&rsi_cache);
1415 	svc_auth_unregister(RPC_AUTH_GSS);
1416 }
1417