1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/net/sunrpc/xdr.c
4 *
5 * Generic XDR support.
6 *
7 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
8 */
9
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <linux/types.h>
13 #include <linux/string.h>
14 #include <linux/kernel.h>
15 #include <linux/pagemap.h>
16 #include <linux/errno.h>
17 #include <linux/sunrpc/xdr.h>
18 #include <linux/sunrpc/msg_prot.h>
19 #include <linux/bvec.h>
20 #include <trace/events/sunrpc.h>
21
22 /*
23 * XDR functions for basic NFS types
24 */
25 __be32 *
xdr_encode_netobj(__be32 * p,const struct xdr_netobj * obj)26 xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
27 {
28 unsigned int quadlen = XDR_QUADLEN(obj->len);
29
30 p[quadlen] = 0; /* zero trailing bytes */
31 *p++ = cpu_to_be32(obj->len);
32 memcpy(p, obj->data, obj->len);
33 return p + XDR_QUADLEN(obj->len);
34 }
35 EXPORT_SYMBOL_GPL(xdr_encode_netobj);
36
37 __be32 *
xdr_decode_netobj(__be32 * p,struct xdr_netobj * obj)38 xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
39 {
40 unsigned int len;
41
42 if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
43 return NULL;
44 obj->len = len;
45 obj->data = (u8 *) p;
46 return p + XDR_QUADLEN(len);
47 }
48 EXPORT_SYMBOL_GPL(xdr_decode_netobj);
49
50 /**
51 * xdr_encode_opaque_fixed - Encode fixed length opaque data
52 * @p: pointer to current position in XDR buffer.
53 * @ptr: pointer to data to encode (or NULL)
54 * @nbytes: size of data.
55 *
56 * Copy the array of data of length nbytes at ptr to the XDR buffer
57 * at position p, then align to the next 32-bit boundary by padding
58 * with zero bytes (see RFC1832).
59 * Note: if ptr is NULL, only the padding is performed.
60 *
61 * Returns the updated current XDR buffer position
62 *
63 */
xdr_encode_opaque_fixed(__be32 * p,const void * ptr,unsigned int nbytes)64 __be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
65 {
66 if (likely(nbytes != 0)) {
67 unsigned int quadlen = XDR_QUADLEN(nbytes);
68 unsigned int padding = (quadlen << 2) - nbytes;
69
70 if (ptr != NULL)
71 memcpy(p, ptr, nbytes);
72 if (padding != 0)
73 memset((char *)p + nbytes, 0, padding);
74 p += quadlen;
75 }
76 return p;
77 }
78 EXPORT_SYMBOL_GPL(xdr_encode_opaque_fixed);
79
80 /**
81 * xdr_encode_opaque - Encode variable length opaque data
82 * @p: pointer to current position in XDR buffer.
83 * @ptr: pointer to data to encode (or NULL)
84 * @nbytes: size of data.
85 *
86 * Returns the updated current XDR buffer position
87 */
xdr_encode_opaque(__be32 * p,const void * ptr,unsigned int nbytes)88 __be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
89 {
90 *p++ = cpu_to_be32(nbytes);
91 return xdr_encode_opaque_fixed(p, ptr, nbytes);
92 }
93 EXPORT_SYMBOL_GPL(xdr_encode_opaque);
94
95 __be32 *
xdr_encode_string(__be32 * p,const char * string)96 xdr_encode_string(__be32 *p, const char *string)
97 {
98 return xdr_encode_array(p, string, strlen(string));
99 }
100 EXPORT_SYMBOL_GPL(xdr_encode_string);
101
102 __be32 *
xdr_decode_string_inplace(__be32 * p,char ** sp,unsigned int * lenp,unsigned int maxlen)103 xdr_decode_string_inplace(__be32 *p, char **sp,
104 unsigned int *lenp, unsigned int maxlen)
105 {
106 u32 len;
107
108 len = be32_to_cpu(*p++);
109 if (len > maxlen)
110 return NULL;
111 *lenp = len;
112 *sp = (char *) p;
113 return p + XDR_QUADLEN(len);
114 }
115 EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
116
117 /**
118 * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
119 * @buf: XDR buffer where string resides
120 * @len: length of string, in bytes
121 *
122 */
123 void
xdr_terminate_string(struct xdr_buf * buf,const u32 len)124 xdr_terminate_string(struct xdr_buf *buf, const u32 len)
125 {
126 char *kaddr;
127
128 kaddr = kmap_atomic(buf->pages[0]);
129 kaddr[buf->page_base + len] = '\0';
130 kunmap_atomic(kaddr);
131 }
132 EXPORT_SYMBOL_GPL(xdr_terminate_string);
133
134 size_t
xdr_buf_pagecount(struct xdr_buf * buf)135 xdr_buf_pagecount(struct xdr_buf *buf)
136 {
137 if (!buf->page_len)
138 return 0;
139 return (buf->page_base + buf->page_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
140 }
141
142 int
xdr_alloc_bvec(struct xdr_buf * buf,gfp_t gfp)143 xdr_alloc_bvec(struct xdr_buf *buf, gfp_t gfp)
144 {
145 size_t i, n = xdr_buf_pagecount(buf);
146
147 if (n != 0 && buf->bvec == NULL) {
148 buf->bvec = kmalloc_array(n, sizeof(buf->bvec[0]), gfp);
149 if (!buf->bvec)
150 return -ENOMEM;
151 for (i = 0; i < n; i++) {
152 buf->bvec[i].bv_page = buf->pages[i];
153 buf->bvec[i].bv_len = PAGE_SIZE;
154 buf->bvec[i].bv_offset = 0;
155 }
156 }
157 return 0;
158 }
159
160 void
xdr_free_bvec(struct xdr_buf * buf)161 xdr_free_bvec(struct xdr_buf *buf)
162 {
163 kfree(buf->bvec);
164 buf->bvec = NULL;
165 }
166
167 /**
168 * xdr_inline_pages - Prepare receive buffer for a large reply
169 * @xdr: xdr_buf into which reply will be placed
170 * @offset: expected offset where data payload will start, in bytes
171 * @pages: vector of struct page pointers
172 * @base: offset in first page where receive should start, in bytes
173 * @len: expected size of the upper layer data payload, in bytes
174 *
175 */
176 void
xdr_inline_pages(struct xdr_buf * xdr,unsigned int offset,struct page ** pages,unsigned int base,unsigned int len)177 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
178 struct page **pages, unsigned int base, unsigned int len)
179 {
180 struct kvec *head = xdr->head;
181 struct kvec *tail = xdr->tail;
182 char *buf = (char *)head->iov_base;
183 unsigned int buflen = head->iov_len;
184
185 head->iov_len = offset;
186
187 xdr->pages = pages;
188 xdr->page_base = base;
189 xdr->page_len = len;
190
191 tail->iov_base = buf + offset;
192 tail->iov_len = buflen - offset;
193 if ((xdr->page_len & 3) == 0)
194 tail->iov_len -= sizeof(__be32);
195
196 xdr->buflen += len;
197 }
198 EXPORT_SYMBOL_GPL(xdr_inline_pages);
199
200 /*
201 * Helper routines for doing 'memmove' like operations on a struct xdr_buf
202 */
203
204 /**
205 * _shift_data_right_pages
206 * @pages: vector of pages containing both the source and dest memory area.
207 * @pgto_base: page vector address of destination
208 * @pgfrom_base: page vector address of source
209 * @len: number of bytes to copy
210 *
211 * Note: the addresses pgto_base and pgfrom_base are both calculated in
212 * the same way:
213 * if a memory area starts at byte 'base' in page 'pages[i]',
214 * then its address is given as (i << PAGE_SHIFT) + base
215 * Also note: pgfrom_base must be < pgto_base, but the memory areas
216 * they point to may overlap.
217 */
218 static void
_shift_data_right_pages(struct page ** pages,size_t pgto_base,size_t pgfrom_base,size_t len)219 _shift_data_right_pages(struct page **pages, size_t pgto_base,
220 size_t pgfrom_base, size_t len)
221 {
222 struct page **pgfrom, **pgto;
223 char *vfrom, *vto;
224 size_t copy;
225
226 BUG_ON(pgto_base <= pgfrom_base);
227
228 pgto_base += len;
229 pgfrom_base += len;
230
231 pgto = pages + (pgto_base >> PAGE_SHIFT);
232 pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
233
234 pgto_base &= ~PAGE_MASK;
235 pgfrom_base &= ~PAGE_MASK;
236
237 do {
238 /* Are any pointers crossing a page boundary? */
239 if (pgto_base == 0) {
240 pgto_base = PAGE_SIZE;
241 pgto--;
242 }
243 if (pgfrom_base == 0) {
244 pgfrom_base = PAGE_SIZE;
245 pgfrom--;
246 }
247
248 copy = len;
249 if (copy > pgto_base)
250 copy = pgto_base;
251 if (copy > pgfrom_base)
252 copy = pgfrom_base;
253 pgto_base -= copy;
254 pgfrom_base -= copy;
255
256 vto = kmap_atomic(*pgto);
257 if (*pgto != *pgfrom) {
258 vfrom = kmap_atomic(*pgfrom);
259 memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
260 kunmap_atomic(vfrom);
261 } else
262 memmove(vto + pgto_base, vto + pgfrom_base, copy);
263 flush_dcache_page(*pgto);
264 kunmap_atomic(vto);
265
266 } while ((len -= copy) != 0);
267 }
268
269 /**
270 * _copy_to_pages
271 * @pages: array of pages
272 * @pgbase: page vector address of destination
273 * @p: pointer to source data
274 * @len: length
275 *
276 * Copies data from an arbitrary memory location into an array of pages
277 * The copy is assumed to be non-overlapping.
278 */
279 static void
_copy_to_pages(struct page ** pages,size_t pgbase,const char * p,size_t len)280 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
281 {
282 struct page **pgto;
283 char *vto;
284 size_t copy;
285
286 pgto = pages + (pgbase >> PAGE_SHIFT);
287 pgbase &= ~PAGE_MASK;
288
289 for (;;) {
290 copy = PAGE_SIZE - pgbase;
291 if (copy > len)
292 copy = len;
293
294 vto = kmap_atomic(*pgto);
295 memcpy(vto + pgbase, p, copy);
296 kunmap_atomic(vto);
297
298 len -= copy;
299 if (len == 0)
300 break;
301
302 pgbase += copy;
303 if (pgbase == PAGE_SIZE) {
304 flush_dcache_page(*pgto);
305 pgbase = 0;
306 pgto++;
307 }
308 p += copy;
309 }
310 flush_dcache_page(*pgto);
311 }
312
313 /**
314 * _copy_from_pages
315 * @p: pointer to destination
316 * @pages: array of pages
317 * @pgbase: offset of source data
318 * @len: length
319 *
320 * Copies data into an arbitrary memory location from an array of pages
321 * The copy is assumed to be non-overlapping.
322 */
323 void
_copy_from_pages(char * p,struct page ** pages,size_t pgbase,size_t len)324 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
325 {
326 struct page **pgfrom;
327 char *vfrom;
328 size_t copy;
329
330 pgfrom = pages + (pgbase >> PAGE_SHIFT);
331 pgbase &= ~PAGE_MASK;
332
333 do {
334 copy = PAGE_SIZE - pgbase;
335 if (copy > len)
336 copy = len;
337
338 vfrom = kmap_atomic(*pgfrom);
339 memcpy(p, vfrom + pgbase, copy);
340 kunmap_atomic(vfrom);
341
342 pgbase += copy;
343 if (pgbase == PAGE_SIZE) {
344 pgbase = 0;
345 pgfrom++;
346 }
347 p += copy;
348
349 } while ((len -= copy) != 0);
350 }
351 EXPORT_SYMBOL_GPL(_copy_from_pages);
352
353 /**
354 * xdr_shrink_bufhead
355 * @buf: xdr_buf
356 * @len: bytes to remove from buf->head[0]
357 *
358 * Shrinks XDR buffer's header kvec buf->head[0] by
359 * 'len' bytes. The extra data is not lost, but is instead
360 * moved into the inlined pages and/or the tail.
361 */
362 static unsigned int
xdr_shrink_bufhead(struct xdr_buf * buf,size_t len)363 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
364 {
365 struct kvec *head, *tail;
366 size_t copy, offs;
367 unsigned int pglen = buf->page_len;
368 unsigned int result;
369
370 result = 0;
371 tail = buf->tail;
372 head = buf->head;
373
374 WARN_ON_ONCE(len > head->iov_len);
375 if (len > head->iov_len)
376 len = head->iov_len;
377
378 /* Shift the tail first */
379 if (tail->iov_len != 0) {
380 if (tail->iov_len > len) {
381 copy = tail->iov_len - len;
382 memmove((char *)tail->iov_base + len,
383 tail->iov_base, copy);
384 result += copy;
385 }
386 /* Copy from the inlined pages into the tail */
387 copy = len;
388 if (copy > pglen)
389 copy = pglen;
390 offs = len - copy;
391 if (offs >= tail->iov_len)
392 copy = 0;
393 else if (copy > tail->iov_len - offs)
394 copy = tail->iov_len - offs;
395 if (copy != 0) {
396 _copy_from_pages((char *)tail->iov_base + offs,
397 buf->pages,
398 buf->page_base + pglen + offs - len,
399 copy);
400 result += copy;
401 }
402 /* Do we also need to copy data from the head into the tail ? */
403 if (len > pglen) {
404 offs = copy = len - pglen;
405 if (copy > tail->iov_len)
406 copy = tail->iov_len;
407 memcpy(tail->iov_base,
408 (char *)head->iov_base +
409 head->iov_len - offs,
410 copy);
411 result += copy;
412 }
413 }
414 /* Now handle pages */
415 if (pglen != 0) {
416 if (pglen > len)
417 _shift_data_right_pages(buf->pages,
418 buf->page_base + len,
419 buf->page_base,
420 pglen - len);
421 copy = len;
422 if (len > pglen)
423 copy = pglen;
424 _copy_to_pages(buf->pages, buf->page_base,
425 (char *)head->iov_base + head->iov_len - len,
426 copy);
427 result += copy;
428 }
429 head->iov_len -= len;
430 buf->buflen -= len;
431 /* Have we truncated the message? */
432 if (buf->len > buf->buflen)
433 buf->len = buf->buflen;
434
435 return result;
436 }
437
438 /**
439 * xdr_shrink_pagelen - shrinks buf->pages by up to @len bytes
440 * @buf: xdr_buf
441 * @len: bytes to remove from buf->pages
442 *
443 * The extra data is not lost, but is instead moved into buf->tail.
444 * Returns the actual number of bytes moved.
445 */
446 static unsigned int
xdr_shrink_pagelen(struct xdr_buf * buf,size_t len)447 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
448 {
449 struct kvec *tail;
450 size_t copy;
451 unsigned int pglen = buf->page_len;
452 unsigned int tailbuf_len;
453 unsigned int result;
454
455 result = 0;
456 tail = buf->tail;
457 if (len > buf->page_len)
458 len = buf-> page_len;
459 tailbuf_len = buf->buflen - buf->head->iov_len - buf->page_len;
460
461 /* Shift the tail first */
462 if (tailbuf_len != 0) {
463 unsigned int free_space = tailbuf_len - tail->iov_len;
464
465 if (len < free_space)
466 free_space = len;
467 tail->iov_len += free_space;
468
469 copy = len;
470 if (tail->iov_len > len) {
471 char *p = (char *)tail->iov_base + len;
472 memmove(p, tail->iov_base, tail->iov_len - len);
473 result += tail->iov_len - len;
474 } else
475 copy = tail->iov_len;
476 /* Copy from the inlined pages into the tail */
477 _copy_from_pages((char *)tail->iov_base,
478 buf->pages, buf->page_base + pglen - len,
479 copy);
480 result += copy;
481 }
482 buf->page_len -= len;
483 buf->buflen -= len;
484 /* Have we truncated the message? */
485 if (buf->len > buf->buflen)
486 buf->len = buf->buflen;
487
488 return result;
489 }
490
491 void
xdr_shift_buf(struct xdr_buf * buf,size_t len)492 xdr_shift_buf(struct xdr_buf *buf, size_t len)
493 {
494 xdr_shrink_bufhead(buf, len);
495 }
496 EXPORT_SYMBOL_GPL(xdr_shift_buf);
497
498 /**
499 * xdr_stream_pos - Return the current offset from the start of the xdr_stream
500 * @xdr: pointer to struct xdr_stream
501 */
xdr_stream_pos(const struct xdr_stream * xdr)502 unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
503 {
504 return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
505 }
506 EXPORT_SYMBOL_GPL(xdr_stream_pos);
507
508 /**
509 * xdr_init_encode - Initialize a struct xdr_stream for sending data.
510 * @xdr: pointer to xdr_stream struct
511 * @buf: pointer to XDR buffer in which to encode data
512 * @p: current pointer inside XDR buffer
513 * @rqst: pointer to controlling rpc_rqst, for debugging
514 *
515 * Note: at the moment the RPC client only passes the length of our
516 * scratch buffer in the xdr_buf's header kvec. Previously this
517 * meant we needed to call xdr_adjust_iovec() after encoding the
518 * data. With the new scheme, the xdr_stream manages the details
519 * of the buffer length, and takes care of adjusting the kvec
520 * length for us.
521 */
xdr_init_encode(struct xdr_stream * xdr,struct xdr_buf * buf,__be32 * p,struct rpc_rqst * rqst)522 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
523 struct rpc_rqst *rqst)
524 {
525 struct kvec *iov = buf->head;
526 int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
527
528 xdr_set_scratch_buffer(xdr, NULL, 0);
529 BUG_ON(scratch_len < 0);
530 xdr->buf = buf;
531 xdr->iov = iov;
532 xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
533 xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
534 BUG_ON(iov->iov_len > scratch_len);
535
536 if (p != xdr->p && p != NULL) {
537 size_t len;
538
539 BUG_ON(p < xdr->p || p > xdr->end);
540 len = (char *)p - (char *)xdr->p;
541 xdr->p = p;
542 buf->len += len;
543 iov->iov_len += len;
544 }
545 xdr->rqst = rqst;
546 }
547 EXPORT_SYMBOL_GPL(xdr_init_encode);
548
549 /**
550 * xdr_commit_encode - Ensure all data is written to buffer
551 * @xdr: pointer to xdr_stream
552 *
553 * We handle encoding across page boundaries by giving the caller a
554 * temporary location to write to, then later copying the data into
555 * place; xdr_commit_encode does that copying.
556 *
557 * Normally the caller doesn't need to call this directly, as the
558 * following xdr_reserve_space will do it. But an explicit call may be
559 * required at the end of encoding, or any other time when the xdr_buf
560 * data might be read.
561 */
xdr_commit_encode(struct xdr_stream * xdr)562 inline void xdr_commit_encode(struct xdr_stream *xdr)
563 {
564 int shift = xdr->scratch.iov_len;
565 void *page;
566
567 if (shift == 0)
568 return;
569 page = page_address(*xdr->page_ptr);
570 memcpy(xdr->scratch.iov_base, page, shift);
571 memmove(page, page + shift, (void *)xdr->p - page);
572 xdr->scratch.iov_len = 0;
573 }
574 EXPORT_SYMBOL_GPL(xdr_commit_encode);
575
xdr_get_next_encode_buffer(struct xdr_stream * xdr,size_t nbytes)576 static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
577 size_t nbytes)
578 {
579 __be32 *p;
580 int space_left;
581 int frag1bytes, frag2bytes;
582
583 if (nbytes > PAGE_SIZE)
584 goto out_overflow; /* Bigger buffers require special handling */
585 if (xdr->buf->len + nbytes > xdr->buf->buflen)
586 goto out_overflow; /* Sorry, we're totally out of space */
587 frag1bytes = (xdr->end - xdr->p) << 2;
588 frag2bytes = nbytes - frag1bytes;
589 if (xdr->iov)
590 xdr->iov->iov_len += frag1bytes;
591 else
592 xdr->buf->page_len += frag1bytes;
593 xdr->page_ptr++;
594 xdr->iov = NULL;
595 /*
596 * If the last encode didn't end exactly on a page boundary, the
597 * next one will straddle boundaries. Encode into the next
598 * page, then copy it back later in xdr_commit_encode. We use
599 * the "scratch" iov to track any temporarily unused fragment of
600 * space at the end of the previous buffer:
601 */
602 xdr->scratch.iov_base = xdr->p;
603 xdr->scratch.iov_len = frag1bytes;
604 p = page_address(*xdr->page_ptr);
605 /*
606 * Note this is where the next encode will start after we've
607 * shifted this one back:
608 */
609 xdr->p = (void *)p + frag2bytes;
610 space_left = xdr->buf->buflen - xdr->buf->len;
611 if (space_left - frag1bytes >= PAGE_SIZE)
612 xdr->end = (void *)p + PAGE_SIZE;
613 else
614 xdr->end = (void *)p + space_left - frag1bytes;
615
616 xdr->buf->page_len += frag2bytes;
617 xdr->buf->len += nbytes;
618 return p;
619 out_overflow:
620 trace_rpc_xdr_overflow(xdr, nbytes);
621 return NULL;
622 }
623
624 /**
625 * xdr_reserve_space - Reserve buffer space for sending
626 * @xdr: pointer to xdr_stream
627 * @nbytes: number of bytes to reserve
628 *
629 * Checks that we have enough buffer space to encode 'nbytes' more
630 * bytes of data. If so, update the total xdr_buf length, and
631 * adjust the length of the current kvec.
632 */
xdr_reserve_space(struct xdr_stream * xdr,size_t nbytes)633 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
634 {
635 __be32 *p = xdr->p;
636 __be32 *q;
637
638 xdr_commit_encode(xdr);
639 /* align nbytes on the next 32-bit boundary */
640 nbytes += 3;
641 nbytes &= ~3;
642 q = p + (nbytes >> 2);
643 if (unlikely(q > xdr->end || q < p))
644 return xdr_get_next_encode_buffer(xdr, nbytes);
645 xdr->p = q;
646 if (xdr->iov)
647 xdr->iov->iov_len += nbytes;
648 else
649 xdr->buf->page_len += nbytes;
650 xdr->buf->len += nbytes;
651 return p;
652 }
653 EXPORT_SYMBOL_GPL(xdr_reserve_space);
654
655 /**
656 * xdr_truncate_encode - truncate an encode buffer
657 * @xdr: pointer to xdr_stream
658 * @len: new length of buffer
659 *
660 * Truncates the xdr stream, so that xdr->buf->len == len,
661 * and xdr->p points at offset len from the start of the buffer, and
662 * head, tail, and page lengths are adjusted to correspond.
663 *
664 * If this means moving xdr->p to a different buffer, we assume that
665 * that the end pointer should be set to the end of the current page,
666 * except in the case of the head buffer when we assume the head
667 * buffer's current length represents the end of the available buffer.
668 *
669 * This is *not* safe to use on a buffer that already has inlined page
670 * cache pages (as in a zero-copy server read reply), except for the
671 * simple case of truncating from one position in the tail to another.
672 *
673 */
xdr_truncate_encode(struct xdr_stream * xdr,size_t len)674 void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
675 {
676 struct xdr_buf *buf = xdr->buf;
677 struct kvec *head = buf->head;
678 struct kvec *tail = buf->tail;
679 int fraglen;
680 int new;
681
682 if (len > buf->len) {
683 WARN_ON_ONCE(1);
684 return;
685 }
686 xdr_commit_encode(xdr);
687
688 fraglen = min_t(int, buf->len - len, tail->iov_len);
689 tail->iov_len -= fraglen;
690 buf->len -= fraglen;
691 if (tail->iov_len) {
692 xdr->p = tail->iov_base + tail->iov_len;
693 WARN_ON_ONCE(!xdr->end);
694 WARN_ON_ONCE(!xdr->iov);
695 return;
696 }
697 WARN_ON_ONCE(fraglen);
698 fraglen = min_t(int, buf->len - len, buf->page_len);
699 buf->page_len -= fraglen;
700 buf->len -= fraglen;
701
702 new = buf->page_base + buf->page_len;
703
704 xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
705
706 if (buf->page_len) {
707 xdr->p = page_address(*xdr->page_ptr);
708 xdr->end = (void *)xdr->p + PAGE_SIZE;
709 xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
710 WARN_ON_ONCE(xdr->iov);
711 return;
712 }
713 if (fraglen)
714 xdr->end = head->iov_base + head->iov_len;
715 /* (otherwise assume xdr->end is already set) */
716 xdr->page_ptr--;
717 head->iov_len = len;
718 buf->len = len;
719 xdr->p = head->iov_base + head->iov_len;
720 xdr->iov = buf->head;
721 }
722 EXPORT_SYMBOL(xdr_truncate_encode);
723
724 /**
725 * xdr_restrict_buflen - decrease available buffer space
726 * @xdr: pointer to xdr_stream
727 * @newbuflen: new maximum number of bytes available
728 *
729 * Adjust our idea of how much space is available in the buffer.
730 * If we've already used too much space in the buffer, returns -1.
731 * If the available space is already smaller than newbuflen, returns 0
732 * and does nothing. Otherwise, adjusts xdr->buf->buflen to newbuflen
733 * and ensures xdr->end is set at most offset newbuflen from the start
734 * of the buffer.
735 */
xdr_restrict_buflen(struct xdr_stream * xdr,int newbuflen)736 int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen)
737 {
738 struct xdr_buf *buf = xdr->buf;
739 int left_in_this_buf = (void *)xdr->end - (void *)xdr->p;
740 int end_offset = buf->len + left_in_this_buf;
741
742 if (newbuflen < 0 || newbuflen < buf->len)
743 return -1;
744 if (newbuflen > buf->buflen)
745 return 0;
746 if (newbuflen < end_offset)
747 xdr->end = (void *)xdr->end + newbuflen - end_offset;
748 buf->buflen = newbuflen;
749 return 0;
750 }
751 EXPORT_SYMBOL(xdr_restrict_buflen);
752
753 /**
754 * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
755 * @xdr: pointer to xdr_stream
756 * @pages: list of pages
757 * @base: offset of first byte
758 * @len: length of data in bytes
759 *
760 */
xdr_write_pages(struct xdr_stream * xdr,struct page ** pages,unsigned int base,unsigned int len)761 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
762 unsigned int len)
763 {
764 struct xdr_buf *buf = xdr->buf;
765 struct kvec *iov = buf->tail;
766 buf->pages = pages;
767 buf->page_base = base;
768 buf->page_len = len;
769
770 iov->iov_base = (char *)xdr->p;
771 iov->iov_len = 0;
772 xdr->iov = iov;
773
774 if (len & 3) {
775 unsigned int pad = 4 - (len & 3);
776
777 BUG_ON(xdr->p >= xdr->end);
778 iov->iov_base = (char *)xdr->p + (len & 3);
779 iov->iov_len += pad;
780 len += pad;
781 *xdr->p++ = 0;
782 }
783 buf->buflen += len;
784 buf->len += len;
785 }
786 EXPORT_SYMBOL_GPL(xdr_write_pages);
787
xdr_set_iov(struct xdr_stream * xdr,struct kvec * iov,unsigned int len)788 static void xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
789 unsigned int len)
790 {
791 if (len > iov->iov_len)
792 len = iov->iov_len;
793 xdr->p = (__be32*)iov->iov_base;
794 xdr->end = (__be32*)(iov->iov_base + len);
795 xdr->iov = iov;
796 xdr->page_ptr = NULL;
797 }
798
xdr_set_page_base(struct xdr_stream * xdr,unsigned int base,unsigned int len)799 static int xdr_set_page_base(struct xdr_stream *xdr,
800 unsigned int base, unsigned int len)
801 {
802 unsigned int pgnr;
803 unsigned int maxlen;
804 unsigned int pgoff;
805 unsigned int pgend;
806 void *kaddr;
807
808 maxlen = xdr->buf->page_len;
809 if (base >= maxlen)
810 return -EINVAL;
811 maxlen -= base;
812 if (len > maxlen)
813 len = maxlen;
814
815 base += xdr->buf->page_base;
816
817 pgnr = base >> PAGE_SHIFT;
818 xdr->page_ptr = &xdr->buf->pages[pgnr];
819 kaddr = page_address(*xdr->page_ptr);
820
821 pgoff = base & ~PAGE_MASK;
822 xdr->p = (__be32*)(kaddr + pgoff);
823
824 pgend = pgoff + len;
825 if (pgend > PAGE_SIZE)
826 pgend = PAGE_SIZE;
827 xdr->end = (__be32*)(kaddr + pgend);
828 xdr->iov = NULL;
829 return 0;
830 }
831
xdr_set_next_page(struct xdr_stream * xdr)832 static void xdr_set_next_page(struct xdr_stream *xdr)
833 {
834 unsigned int newbase;
835
836 newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
837 newbase -= xdr->buf->page_base;
838
839 if (xdr_set_page_base(xdr, newbase, PAGE_SIZE) < 0)
840 xdr_set_iov(xdr, xdr->buf->tail, xdr->nwords << 2);
841 }
842
xdr_set_next_buffer(struct xdr_stream * xdr)843 static bool xdr_set_next_buffer(struct xdr_stream *xdr)
844 {
845 if (xdr->page_ptr != NULL)
846 xdr_set_next_page(xdr);
847 else if (xdr->iov == xdr->buf->head) {
848 if (xdr_set_page_base(xdr, 0, PAGE_SIZE) < 0)
849 xdr_set_iov(xdr, xdr->buf->tail, xdr->nwords << 2);
850 }
851 return xdr->p != xdr->end;
852 }
853
854 /**
855 * xdr_init_decode - Initialize an xdr_stream for decoding data.
856 * @xdr: pointer to xdr_stream struct
857 * @buf: pointer to XDR buffer from which to decode data
858 * @p: current pointer inside XDR buffer
859 * @rqst: pointer to controlling rpc_rqst, for debugging
860 */
xdr_init_decode(struct xdr_stream * xdr,struct xdr_buf * buf,__be32 * p,struct rpc_rqst * rqst)861 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
862 struct rpc_rqst *rqst)
863 {
864 xdr->buf = buf;
865 xdr->scratch.iov_base = NULL;
866 xdr->scratch.iov_len = 0;
867 xdr->nwords = XDR_QUADLEN(buf->len);
868 if (buf->head[0].iov_len != 0)
869 xdr_set_iov(xdr, buf->head, buf->len);
870 else if (buf->page_len != 0)
871 xdr_set_page_base(xdr, 0, buf->len);
872 else
873 xdr_set_iov(xdr, buf->head, buf->len);
874 if (p != NULL && p > xdr->p && xdr->end >= p) {
875 xdr->nwords -= p - xdr->p;
876 xdr->p = p;
877 }
878 xdr->rqst = rqst;
879 }
880 EXPORT_SYMBOL_GPL(xdr_init_decode);
881
882 /**
883 * xdr_init_decode_pages - Initialize an xdr_stream for decoding into pages
884 * @xdr: pointer to xdr_stream struct
885 * @buf: pointer to XDR buffer from which to decode data
886 * @pages: list of pages to decode into
887 * @len: length in bytes of buffer in pages
888 */
xdr_init_decode_pages(struct xdr_stream * xdr,struct xdr_buf * buf,struct page ** pages,unsigned int len)889 void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
890 struct page **pages, unsigned int len)
891 {
892 memset(buf, 0, sizeof(*buf));
893 buf->pages = pages;
894 buf->page_len = len;
895 buf->buflen = len;
896 buf->len = len;
897 xdr_init_decode(xdr, buf, NULL, NULL);
898 }
899 EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
900
__xdr_inline_decode(struct xdr_stream * xdr,size_t nbytes)901 static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
902 {
903 unsigned int nwords = XDR_QUADLEN(nbytes);
904 __be32 *p = xdr->p;
905 __be32 *q = p + nwords;
906
907 if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
908 return NULL;
909 xdr->p = q;
910 xdr->nwords -= nwords;
911 return p;
912 }
913
914 /**
915 * xdr_set_scratch_buffer - Attach a scratch buffer for decoding data.
916 * @xdr: pointer to xdr_stream struct
917 * @buf: pointer to an empty buffer
918 * @buflen: size of 'buf'
919 *
920 * The scratch buffer is used when decoding from an array of pages.
921 * If an xdr_inline_decode() call spans across page boundaries, then
922 * we copy the data into the scratch buffer in order to allow linear
923 * access.
924 */
xdr_set_scratch_buffer(struct xdr_stream * xdr,void * buf,size_t buflen)925 void xdr_set_scratch_buffer(struct xdr_stream *xdr, void *buf, size_t buflen)
926 {
927 xdr->scratch.iov_base = buf;
928 xdr->scratch.iov_len = buflen;
929 }
930 EXPORT_SYMBOL_GPL(xdr_set_scratch_buffer);
931
xdr_copy_to_scratch(struct xdr_stream * xdr,size_t nbytes)932 static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
933 {
934 __be32 *p;
935 char *cpdest = xdr->scratch.iov_base;
936 size_t cplen = (char *)xdr->end - (char *)xdr->p;
937
938 if (nbytes > xdr->scratch.iov_len)
939 goto out_overflow;
940 p = __xdr_inline_decode(xdr, cplen);
941 if (p == NULL)
942 return NULL;
943 memcpy(cpdest, p, cplen);
944 if (!xdr_set_next_buffer(xdr))
945 goto out_overflow;
946 cpdest += cplen;
947 nbytes -= cplen;
948 p = __xdr_inline_decode(xdr, nbytes);
949 if (p == NULL)
950 return NULL;
951 memcpy(cpdest, p, nbytes);
952 return xdr->scratch.iov_base;
953 out_overflow:
954 trace_rpc_xdr_overflow(xdr, nbytes);
955 return NULL;
956 }
957
958 /**
959 * xdr_inline_decode - Retrieve XDR data to decode
960 * @xdr: pointer to xdr_stream struct
961 * @nbytes: number of bytes of data to decode
962 *
963 * Check if the input buffer is long enough to enable us to decode
964 * 'nbytes' more bytes of data starting at the current position.
965 * If so return the current pointer, then update the current
966 * pointer position.
967 */
xdr_inline_decode(struct xdr_stream * xdr,size_t nbytes)968 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
969 {
970 __be32 *p;
971
972 if (unlikely(nbytes == 0))
973 return xdr->p;
974 if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
975 goto out_overflow;
976 p = __xdr_inline_decode(xdr, nbytes);
977 if (p != NULL)
978 return p;
979 return xdr_copy_to_scratch(xdr, nbytes);
980 out_overflow:
981 trace_rpc_xdr_overflow(xdr, nbytes);
982 return NULL;
983 }
984 EXPORT_SYMBOL_GPL(xdr_inline_decode);
985
xdr_align_pages(struct xdr_stream * xdr,unsigned int len)986 static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
987 {
988 struct xdr_buf *buf = xdr->buf;
989 struct kvec *iov;
990 unsigned int nwords = XDR_QUADLEN(len);
991 unsigned int cur = xdr_stream_pos(xdr);
992 unsigned int copied, offset;
993
994 if (xdr->nwords == 0)
995 return 0;
996
997 /* Realign pages to current pointer position */
998 iov = buf->head;
999 if (iov->iov_len > cur) {
1000 offset = iov->iov_len - cur;
1001 copied = xdr_shrink_bufhead(buf, offset);
1002 trace_rpc_xdr_alignment(xdr, offset, copied);
1003 xdr->nwords = XDR_QUADLEN(buf->len - cur);
1004 }
1005
1006 if (nwords > xdr->nwords) {
1007 nwords = xdr->nwords;
1008 len = nwords << 2;
1009 }
1010 if (buf->page_len <= len)
1011 len = buf->page_len;
1012 else if (nwords < xdr->nwords) {
1013 /* Truncate page data and move it into the tail */
1014 offset = buf->page_len - len;
1015 copied = xdr_shrink_pagelen(buf, offset);
1016 trace_rpc_xdr_alignment(xdr, offset, copied);
1017 xdr->nwords = XDR_QUADLEN(buf->len - cur);
1018 }
1019 return len;
1020 }
1021
1022 /**
1023 * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
1024 * @xdr: pointer to xdr_stream struct
1025 * @len: number of bytes of page data
1026 *
1027 * Moves data beyond the current pointer position from the XDR head[] buffer
1028 * into the page list. Any data that lies beyond current position + "len"
1029 * bytes is moved into the XDR tail[].
1030 *
1031 * Returns the number of XDR encoded bytes now contained in the pages
1032 */
xdr_read_pages(struct xdr_stream * xdr,unsigned int len)1033 unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
1034 {
1035 struct xdr_buf *buf = xdr->buf;
1036 struct kvec *iov;
1037 unsigned int nwords;
1038 unsigned int end;
1039 unsigned int padding;
1040
1041 len = xdr_align_pages(xdr, len);
1042 if (len == 0)
1043 return 0;
1044 nwords = XDR_QUADLEN(len);
1045 padding = (nwords << 2) - len;
1046 xdr->iov = iov = buf->tail;
1047 /* Compute remaining message length. */
1048 end = ((xdr->nwords - nwords) << 2) + padding;
1049 if (end > iov->iov_len)
1050 end = iov->iov_len;
1051
1052 /*
1053 * Position current pointer at beginning of tail, and
1054 * set remaining message length.
1055 */
1056 xdr->p = (__be32 *)((char *)iov->iov_base + padding);
1057 xdr->end = (__be32 *)((char *)iov->iov_base + end);
1058 xdr->page_ptr = NULL;
1059 xdr->nwords = XDR_QUADLEN(end - padding);
1060 return len;
1061 }
1062 EXPORT_SYMBOL_GPL(xdr_read_pages);
1063
1064 /**
1065 * xdr_enter_page - decode data from the XDR page
1066 * @xdr: pointer to xdr_stream struct
1067 * @len: number of bytes of page data
1068 *
1069 * Moves data beyond the current pointer position from the XDR head[] buffer
1070 * into the page list. Any data that lies beyond current position + "len"
1071 * bytes is moved into the XDR tail[]. The current pointer is then
1072 * repositioned at the beginning of the first XDR page.
1073 */
xdr_enter_page(struct xdr_stream * xdr,unsigned int len)1074 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
1075 {
1076 len = xdr_align_pages(xdr, len);
1077 /*
1078 * Position current pointer at beginning of tail, and
1079 * set remaining message length.
1080 */
1081 if (len != 0)
1082 xdr_set_page_base(xdr, 0, len);
1083 }
1084 EXPORT_SYMBOL_GPL(xdr_enter_page);
1085
1086 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
1087
1088 void
xdr_buf_from_iov(struct kvec * iov,struct xdr_buf * buf)1089 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
1090 {
1091 buf->head[0] = *iov;
1092 buf->tail[0] = empty_iov;
1093 buf->page_len = 0;
1094 buf->buflen = buf->len = iov->iov_len;
1095 }
1096 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
1097
1098 /**
1099 * xdr_buf_subsegment - set subbuf to a portion of buf
1100 * @buf: an xdr buffer
1101 * @subbuf: the result buffer
1102 * @base: beginning of range in bytes
1103 * @len: length of range in bytes
1104 *
1105 * sets @subbuf to an xdr buffer representing the portion of @buf of
1106 * length @len starting at offset @base.
1107 *
1108 * @buf and @subbuf may be pointers to the same struct xdr_buf.
1109 *
1110 * Returns -1 if base of length are out of bounds.
1111 */
1112 int
xdr_buf_subsegment(struct xdr_buf * buf,struct xdr_buf * subbuf,unsigned int base,unsigned int len)1113 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
1114 unsigned int base, unsigned int len)
1115 {
1116 subbuf->buflen = subbuf->len = len;
1117 if (base < buf->head[0].iov_len) {
1118 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
1119 subbuf->head[0].iov_len = min_t(unsigned int, len,
1120 buf->head[0].iov_len - base);
1121 len -= subbuf->head[0].iov_len;
1122 base = 0;
1123 } else {
1124 base -= buf->head[0].iov_len;
1125 subbuf->head[0].iov_base = buf->head[0].iov_base;
1126 subbuf->head[0].iov_len = 0;
1127 }
1128
1129 if (base < buf->page_len) {
1130 subbuf->page_len = min(buf->page_len - base, len);
1131 base += buf->page_base;
1132 subbuf->page_base = base & ~PAGE_MASK;
1133 subbuf->pages = &buf->pages[base >> PAGE_SHIFT];
1134 len -= subbuf->page_len;
1135 base = 0;
1136 } else {
1137 base -= buf->page_len;
1138 subbuf->pages = buf->pages;
1139 subbuf->page_base = 0;
1140 subbuf->page_len = 0;
1141 }
1142
1143 if (base < buf->tail[0].iov_len) {
1144 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
1145 subbuf->tail[0].iov_len = min_t(unsigned int, len,
1146 buf->tail[0].iov_len - base);
1147 len -= subbuf->tail[0].iov_len;
1148 base = 0;
1149 } else {
1150 base -= buf->tail[0].iov_len;
1151 subbuf->tail[0].iov_base = buf->tail[0].iov_base;
1152 subbuf->tail[0].iov_len = 0;
1153 }
1154
1155 if (base || len)
1156 return -1;
1157 return 0;
1158 }
1159 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
1160
1161 /**
1162 * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
1163 * @buf: buf to be trimmed
1164 * @len: number of bytes to reduce "buf" by
1165 *
1166 * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
1167 * that it's possible that we'll trim less than that amount if the xdr_buf is
1168 * too small, or if (for instance) it's all in the head and the parser has
1169 * already read too far into it.
1170 */
xdr_buf_trim(struct xdr_buf * buf,unsigned int len)1171 void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
1172 {
1173 size_t cur;
1174 unsigned int trim = len;
1175
1176 if (buf->tail[0].iov_len) {
1177 cur = min_t(size_t, buf->tail[0].iov_len, trim);
1178 buf->tail[0].iov_len -= cur;
1179 trim -= cur;
1180 if (!trim)
1181 goto fix_len;
1182 }
1183
1184 if (buf->page_len) {
1185 cur = min_t(unsigned int, buf->page_len, trim);
1186 buf->page_len -= cur;
1187 trim -= cur;
1188 if (!trim)
1189 goto fix_len;
1190 }
1191
1192 if (buf->head[0].iov_len) {
1193 cur = min_t(size_t, buf->head[0].iov_len, trim);
1194 buf->head[0].iov_len -= cur;
1195 trim -= cur;
1196 }
1197 fix_len:
1198 buf->len -= (len - trim);
1199 }
1200 EXPORT_SYMBOL_GPL(xdr_buf_trim);
1201
__read_bytes_from_xdr_buf(struct xdr_buf * subbuf,void * obj,unsigned int len)1202 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1203 {
1204 unsigned int this_len;
1205
1206 this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1207 memcpy(obj, subbuf->head[0].iov_base, this_len);
1208 len -= this_len;
1209 obj += this_len;
1210 this_len = min_t(unsigned int, len, subbuf->page_len);
1211 if (this_len)
1212 _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
1213 len -= this_len;
1214 obj += this_len;
1215 this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1216 memcpy(obj, subbuf->tail[0].iov_base, this_len);
1217 }
1218
1219 /* obj is assumed to point to allocated memory of size at least len: */
read_bytes_from_xdr_buf(struct xdr_buf * buf,unsigned int base,void * obj,unsigned int len)1220 int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1221 {
1222 struct xdr_buf subbuf;
1223 int status;
1224
1225 status = xdr_buf_subsegment(buf, &subbuf, base, len);
1226 if (status != 0)
1227 return status;
1228 __read_bytes_from_xdr_buf(&subbuf, obj, len);
1229 return 0;
1230 }
1231 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
1232
__write_bytes_to_xdr_buf(struct xdr_buf * subbuf,void * obj,unsigned int len)1233 static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1234 {
1235 unsigned int this_len;
1236
1237 this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1238 memcpy(subbuf->head[0].iov_base, obj, this_len);
1239 len -= this_len;
1240 obj += this_len;
1241 this_len = min_t(unsigned int, len, subbuf->page_len);
1242 if (this_len)
1243 _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
1244 len -= this_len;
1245 obj += this_len;
1246 this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1247 memcpy(subbuf->tail[0].iov_base, obj, this_len);
1248 }
1249
1250 /* obj is assumed to point to allocated memory of size at least len: */
write_bytes_to_xdr_buf(struct xdr_buf * buf,unsigned int base,void * obj,unsigned int len)1251 int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1252 {
1253 struct xdr_buf subbuf;
1254 int status;
1255
1256 status = xdr_buf_subsegment(buf, &subbuf, base, len);
1257 if (status != 0)
1258 return status;
1259 __write_bytes_to_xdr_buf(&subbuf, obj, len);
1260 return 0;
1261 }
1262 EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
1263
1264 int
xdr_decode_word(struct xdr_buf * buf,unsigned int base,u32 * obj)1265 xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
1266 {
1267 __be32 raw;
1268 int status;
1269
1270 status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1271 if (status)
1272 return status;
1273 *obj = be32_to_cpu(raw);
1274 return 0;
1275 }
1276 EXPORT_SYMBOL_GPL(xdr_decode_word);
1277
1278 int
xdr_encode_word(struct xdr_buf * buf,unsigned int base,u32 obj)1279 xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
1280 {
1281 __be32 raw = cpu_to_be32(obj);
1282
1283 return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1284 }
1285 EXPORT_SYMBOL_GPL(xdr_encode_word);
1286
1287 /**
1288 * xdr_buf_read_mic() - obtain the address of the GSS mic from xdr buf
1289 * @buf: pointer to buffer containing a mic
1290 * @mic: on success, returns the address of the mic
1291 * @offset: the offset in buf where mic may be found
1292 *
1293 * This function may modify the xdr buf if the mic is found to be straddling
1294 * a boundary between head, pages, and tail. On success the mic can be read
1295 * from the address returned. There is no need to free the mic.
1296 *
1297 * Return: Success returns 0, otherwise an integer error.
1298 */
xdr_buf_read_mic(struct xdr_buf * buf,struct xdr_netobj * mic,unsigned int offset)1299 int xdr_buf_read_mic(struct xdr_buf *buf, struct xdr_netobj *mic, unsigned int offset)
1300 {
1301 struct xdr_buf subbuf;
1302 unsigned int boundary;
1303
1304 if (xdr_decode_word(buf, offset, &mic->len))
1305 return -EFAULT;
1306 offset += 4;
1307
1308 /* Is the mic partially in the head? */
1309 boundary = buf->head[0].iov_len;
1310 if (offset < boundary && (offset + mic->len) > boundary)
1311 xdr_shift_buf(buf, boundary - offset);
1312
1313 /* Is the mic partially in the pages? */
1314 boundary += buf->page_len;
1315 if (offset < boundary && (offset + mic->len) > boundary)
1316 xdr_shrink_pagelen(buf, boundary - offset);
1317
1318 if (xdr_buf_subsegment(buf, &subbuf, offset, mic->len))
1319 return -EFAULT;
1320
1321 /* Is the mic contained entirely in the head? */
1322 mic->data = subbuf.head[0].iov_base;
1323 if (subbuf.head[0].iov_len == mic->len)
1324 return 0;
1325 /* ..or is the mic contained entirely in the tail? */
1326 mic->data = subbuf.tail[0].iov_base;
1327 if (subbuf.tail[0].iov_len == mic->len)
1328 return 0;
1329
1330 /* Find a contiguous area in @buf to hold all of @mic */
1331 if (mic->len > buf->buflen - buf->len)
1332 return -ENOMEM;
1333 if (buf->tail[0].iov_len != 0)
1334 mic->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
1335 else
1336 mic->data = buf->head[0].iov_base + buf->head[0].iov_len;
1337 __read_bytes_from_xdr_buf(&subbuf, mic->data, mic->len);
1338 return 0;
1339 }
1340 EXPORT_SYMBOL_GPL(xdr_buf_read_mic);
1341
1342 /* Returns 0 on success, or else a negative error code. */
1343 static int
xdr_xcode_array2(struct xdr_buf * buf,unsigned int base,struct xdr_array2_desc * desc,int encode)1344 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
1345 struct xdr_array2_desc *desc, int encode)
1346 {
1347 char *elem = NULL, *c;
1348 unsigned int copied = 0, todo, avail_here;
1349 struct page **ppages = NULL;
1350 int err;
1351
1352 if (encode) {
1353 if (xdr_encode_word(buf, base, desc->array_len) != 0)
1354 return -EINVAL;
1355 } else {
1356 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1357 desc->array_len > desc->array_maxlen ||
1358 (unsigned long) base + 4 + desc->array_len *
1359 desc->elem_size > buf->len)
1360 return -EINVAL;
1361 }
1362 base += 4;
1363
1364 if (!desc->xcode)
1365 return 0;
1366
1367 todo = desc->array_len * desc->elem_size;
1368
1369 /* process head */
1370 if (todo && base < buf->head->iov_len) {
1371 c = buf->head->iov_base + base;
1372 avail_here = min_t(unsigned int, todo,
1373 buf->head->iov_len - base);
1374 todo -= avail_here;
1375
1376 while (avail_here >= desc->elem_size) {
1377 err = desc->xcode(desc, c);
1378 if (err)
1379 goto out;
1380 c += desc->elem_size;
1381 avail_here -= desc->elem_size;
1382 }
1383 if (avail_here) {
1384 if (!elem) {
1385 elem = kmalloc(desc->elem_size, GFP_KERNEL);
1386 err = -ENOMEM;
1387 if (!elem)
1388 goto out;
1389 }
1390 if (encode) {
1391 err = desc->xcode(desc, elem);
1392 if (err)
1393 goto out;
1394 memcpy(c, elem, avail_here);
1395 } else
1396 memcpy(elem, c, avail_here);
1397 copied = avail_here;
1398 }
1399 base = buf->head->iov_len; /* align to start of pages */
1400 }
1401
1402 /* process pages array */
1403 base -= buf->head->iov_len;
1404 if (todo && base < buf->page_len) {
1405 unsigned int avail_page;
1406
1407 avail_here = min(todo, buf->page_len - base);
1408 todo -= avail_here;
1409
1410 base += buf->page_base;
1411 ppages = buf->pages + (base >> PAGE_SHIFT);
1412 base &= ~PAGE_MASK;
1413 avail_page = min_t(unsigned int, PAGE_SIZE - base,
1414 avail_here);
1415 c = kmap(*ppages) + base;
1416
1417 while (avail_here) {
1418 avail_here -= avail_page;
1419 if (copied || avail_page < desc->elem_size) {
1420 unsigned int l = min(avail_page,
1421 desc->elem_size - copied);
1422 if (!elem) {
1423 elem = kmalloc(desc->elem_size,
1424 GFP_KERNEL);
1425 err = -ENOMEM;
1426 if (!elem)
1427 goto out;
1428 }
1429 if (encode) {
1430 if (!copied) {
1431 err = desc->xcode(desc, elem);
1432 if (err)
1433 goto out;
1434 }
1435 memcpy(c, elem + copied, l);
1436 copied += l;
1437 if (copied == desc->elem_size)
1438 copied = 0;
1439 } else {
1440 memcpy(elem + copied, c, l);
1441 copied += l;
1442 if (copied == desc->elem_size) {
1443 err = desc->xcode(desc, elem);
1444 if (err)
1445 goto out;
1446 copied = 0;
1447 }
1448 }
1449 avail_page -= l;
1450 c += l;
1451 }
1452 while (avail_page >= desc->elem_size) {
1453 err = desc->xcode(desc, c);
1454 if (err)
1455 goto out;
1456 c += desc->elem_size;
1457 avail_page -= desc->elem_size;
1458 }
1459 if (avail_page) {
1460 unsigned int l = min(avail_page,
1461 desc->elem_size - copied);
1462 if (!elem) {
1463 elem = kmalloc(desc->elem_size,
1464 GFP_KERNEL);
1465 err = -ENOMEM;
1466 if (!elem)
1467 goto out;
1468 }
1469 if (encode) {
1470 if (!copied) {
1471 err = desc->xcode(desc, elem);
1472 if (err)
1473 goto out;
1474 }
1475 memcpy(c, elem + copied, l);
1476 copied += l;
1477 if (copied == desc->elem_size)
1478 copied = 0;
1479 } else {
1480 memcpy(elem + copied, c, l);
1481 copied += l;
1482 if (copied == desc->elem_size) {
1483 err = desc->xcode(desc, elem);
1484 if (err)
1485 goto out;
1486 copied = 0;
1487 }
1488 }
1489 }
1490 if (avail_here) {
1491 kunmap(*ppages);
1492 ppages++;
1493 c = kmap(*ppages);
1494 }
1495
1496 avail_page = min(avail_here,
1497 (unsigned int) PAGE_SIZE);
1498 }
1499 base = buf->page_len; /* align to start of tail */
1500 }
1501
1502 /* process tail */
1503 base -= buf->page_len;
1504 if (todo) {
1505 c = buf->tail->iov_base + base;
1506 if (copied) {
1507 unsigned int l = desc->elem_size - copied;
1508
1509 if (encode)
1510 memcpy(c, elem + copied, l);
1511 else {
1512 memcpy(elem + copied, c, l);
1513 err = desc->xcode(desc, elem);
1514 if (err)
1515 goto out;
1516 }
1517 todo -= l;
1518 c += l;
1519 }
1520 while (todo) {
1521 err = desc->xcode(desc, c);
1522 if (err)
1523 goto out;
1524 c += desc->elem_size;
1525 todo -= desc->elem_size;
1526 }
1527 }
1528 err = 0;
1529
1530 out:
1531 kfree(elem);
1532 if (ppages)
1533 kunmap(*ppages);
1534 return err;
1535 }
1536
1537 int
xdr_decode_array2(struct xdr_buf * buf,unsigned int base,struct xdr_array2_desc * desc)1538 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1539 struct xdr_array2_desc *desc)
1540 {
1541 if (base >= buf->len)
1542 return -EINVAL;
1543
1544 return xdr_xcode_array2(buf, base, desc, 0);
1545 }
1546 EXPORT_SYMBOL_GPL(xdr_decode_array2);
1547
1548 int
xdr_encode_array2(struct xdr_buf * buf,unsigned int base,struct xdr_array2_desc * desc)1549 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1550 struct xdr_array2_desc *desc)
1551 {
1552 if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1553 buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1554 return -EINVAL;
1555
1556 return xdr_xcode_array2(buf, base, desc, 1);
1557 }
1558 EXPORT_SYMBOL_GPL(xdr_encode_array2);
1559
1560 int
xdr_process_buf(struct xdr_buf * buf,unsigned int offset,unsigned int len,int (* actor)(struct scatterlist *,void *),void * data)1561 xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1562 int (*actor)(struct scatterlist *, void *), void *data)
1563 {
1564 int i, ret = 0;
1565 unsigned int page_len, thislen, page_offset;
1566 struct scatterlist sg[1];
1567
1568 sg_init_table(sg, 1);
1569
1570 if (offset >= buf->head[0].iov_len) {
1571 offset -= buf->head[0].iov_len;
1572 } else {
1573 thislen = buf->head[0].iov_len - offset;
1574 if (thislen > len)
1575 thislen = len;
1576 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1577 ret = actor(sg, data);
1578 if (ret)
1579 goto out;
1580 offset = 0;
1581 len -= thislen;
1582 }
1583 if (len == 0)
1584 goto out;
1585
1586 if (offset >= buf->page_len) {
1587 offset -= buf->page_len;
1588 } else {
1589 page_len = buf->page_len - offset;
1590 if (page_len > len)
1591 page_len = len;
1592 len -= page_len;
1593 page_offset = (offset + buf->page_base) & (PAGE_SIZE - 1);
1594 i = (offset + buf->page_base) >> PAGE_SHIFT;
1595 thislen = PAGE_SIZE - page_offset;
1596 do {
1597 if (thislen > page_len)
1598 thislen = page_len;
1599 sg_set_page(sg, buf->pages[i], thislen, page_offset);
1600 ret = actor(sg, data);
1601 if (ret)
1602 goto out;
1603 page_len -= thislen;
1604 i++;
1605 page_offset = 0;
1606 thislen = PAGE_SIZE;
1607 } while (page_len != 0);
1608 offset = 0;
1609 }
1610 if (len == 0)
1611 goto out;
1612 if (offset < buf->tail[0].iov_len) {
1613 thislen = buf->tail[0].iov_len - offset;
1614 if (thislen > len)
1615 thislen = len;
1616 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1617 ret = actor(sg, data);
1618 len -= thislen;
1619 }
1620 if (len != 0)
1621 ret = -EINVAL;
1622 out:
1623 return ret;
1624 }
1625 EXPORT_SYMBOL_GPL(xdr_process_buf);
1626
1627 /**
1628 * xdr_stream_decode_opaque - Decode variable length opaque
1629 * @xdr: pointer to xdr_stream
1630 * @ptr: location to store opaque data
1631 * @size: size of storage buffer @ptr
1632 *
1633 * Return values:
1634 * On success, returns size of object stored in *@ptr
1635 * %-EBADMSG on XDR buffer overflow
1636 * %-EMSGSIZE on overflow of storage buffer @ptr
1637 */
xdr_stream_decode_opaque(struct xdr_stream * xdr,void * ptr,size_t size)1638 ssize_t xdr_stream_decode_opaque(struct xdr_stream *xdr, void *ptr, size_t size)
1639 {
1640 ssize_t ret;
1641 void *p;
1642
1643 ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
1644 if (ret <= 0)
1645 return ret;
1646 memcpy(ptr, p, ret);
1647 return ret;
1648 }
1649 EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque);
1650
1651 /**
1652 * xdr_stream_decode_opaque_dup - Decode and duplicate variable length opaque
1653 * @xdr: pointer to xdr_stream
1654 * @ptr: location to store pointer to opaque data
1655 * @maxlen: maximum acceptable object size
1656 * @gfp_flags: GFP mask to use
1657 *
1658 * Return values:
1659 * On success, returns size of object stored in *@ptr
1660 * %-EBADMSG on XDR buffer overflow
1661 * %-EMSGSIZE if the size of the object would exceed @maxlen
1662 * %-ENOMEM on memory allocation failure
1663 */
xdr_stream_decode_opaque_dup(struct xdr_stream * xdr,void ** ptr,size_t maxlen,gfp_t gfp_flags)1664 ssize_t xdr_stream_decode_opaque_dup(struct xdr_stream *xdr, void **ptr,
1665 size_t maxlen, gfp_t gfp_flags)
1666 {
1667 ssize_t ret;
1668 void *p;
1669
1670 ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
1671 if (ret > 0) {
1672 *ptr = kmemdup(p, ret, gfp_flags);
1673 if (*ptr != NULL)
1674 return ret;
1675 ret = -ENOMEM;
1676 }
1677 *ptr = NULL;
1678 return ret;
1679 }
1680 EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque_dup);
1681
1682 /**
1683 * xdr_stream_decode_string - Decode variable length string
1684 * @xdr: pointer to xdr_stream
1685 * @str: location to store string
1686 * @size: size of storage buffer @str
1687 *
1688 * Return values:
1689 * On success, returns length of NUL-terminated string stored in *@str
1690 * %-EBADMSG on XDR buffer overflow
1691 * %-EMSGSIZE on overflow of storage buffer @str
1692 */
xdr_stream_decode_string(struct xdr_stream * xdr,char * str,size_t size)1693 ssize_t xdr_stream_decode_string(struct xdr_stream *xdr, char *str, size_t size)
1694 {
1695 ssize_t ret;
1696 void *p;
1697
1698 ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
1699 if (ret > 0) {
1700 memcpy(str, p, ret);
1701 str[ret] = '\0';
1702 return strlen(str);
1703 }
1704 *str = '\0';
1705 return ret;
1706 }
1707 EXPORT_SYMBOL_GPL(xdr_stream_decode_string);
1708
1709 /**
1710 * xdr_stream_decode_string_dup - Decode and duplicate variable length string
1711 * @xdr: pointer to xdr_stream
1712 * @str: location to store pointer to string
1713 * @maxlen: maximum acceptable string length
1714 * @gfp_flags: GFP mask to use
1715 *
1716 * Return values:
1717 * On success, returns length of NUL-terminated string stored in *@ptr
1718 * %-EBADMSG on XDR buffer overflow
1719 * %-EMSGSIZE if the size of the string would exceed @maxlen
1720 * %-ENOMEM on memory allocation failure
1721 */
xdr_stream_decode_string_dup(struct xdr_stream * xdr,char ** str,size_t maxlen,gfp_t gfp_flags)1722 ssize_t xdr_stream_decode_string_dup(struct xdr_stream *xdr, char **str,
1723 size_t maxlen, gfp_t gfp_flags)
1724 {
1725 void *p;
1726 ssize_t ret;
1727
1728 ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
1729 if (ret > 0) {
1730 char *s = kmalloc(ret + 1, gfp_flags);
1731 if (s != NULL) {
1732 memcpy(s, p, ret);
1733 s[ret] = '\0';
1734 *str = s;
1735 return strlen(s);
1736 }
1737 ret = -ENOMEM;
1738 }
1739 *str = NULL;
1740 return ret;
1741 }
1742 EXPORT_SYMBOL_GPL(xdr_stream_decode_string_dup);
1743