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 static void _copy_to_pages(struct page **, size_t, const char *, size_t);
23 
24 
25 /*
26  * XDR functions for basic NFS types
27  */
28 __be32 *
xdr_encode_netobj(__be32 * p,const struct xdr_netobj * obj)29 xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
30 {
31 	unsigned int	quadlen = XDR_QUADLEN(obj->len);
32 
33 	p[quadlen] = 0;		/* zero trailing bytes */
34 	*p++ = cpu_to_be32(obj->len);
35 	memcpy(p, obj->data, obj->len);
36 	return p + XDR_QUADLEN(obj->len);
37 }
38 EXPORT_SYMBOL_GPL(xdr_encode_netobj);
39 
40 __be32 *
xdr_decode_netobj(__be32 * p,struct xdr_netobj * obj)41 xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
42 {
43 	unsigned int	len;
44 
45 	if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
46 		return NULL;
47 	obj->len  = len;
48 	obj->data = (u8 *) p;
49 	return p + XDR_QUADLEN(len);
50 }
51 EXPORT_SYMBOL_GPL(xdr_decode_netobj);
52 
53 /**
54  * xdr_encode_opaque_fixed - Encode fixed length opaque data
55  * @p: pointer to current position in XDR buffer.
56  * @ptr: pointer to data to encode (or NULL)
57  * @nbytes: size of data.
58  *
59  * Copy the array of data of length nbytes at ptr to the XDR buffer
60  * at position p, then align to the next 32-bit boundary by padding
61  * with zero bytes (see RFC1832).
62  * Note: if ptr is NULL, only the padding is performed.
63  *
64  * Returns the updated current XDR buffer position
65  *
66  */
xdr_encode_opaque_fixed(__be32 * p,const void * ptr,unsigned int nbytes)67 __be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
68 {
69 	if (likely(nbytes != 0)) {
70 		unsigned int quadlen = XDR_QUADLEN(nbytes);
71 		unsigned int padding = (quadlen << 2) - nbytes;
72 
73 		if (ptr != NULL)
74 			memcpy(p, ptr, nbytes);
75 		if (padding != 0)
76 			memset((char *)p + nbytes, 0, padding);
77 		p += quadlen;
78 	}
79 	return p;
80 }
81 EXPORT_SYMBOL_GPL(xdr_encode_opaque_fixed);
82 
83 /**
84  * xdr_encode_opaque - Encode variable length opaque data
85  * @p: pointer to current position in XDR buffer.
86  * @ptr: pointer to data to encode (or NULL)
87  * @nbytes: size of data.
88  *
89  * Returns the updated current XDR buffer position
90  */
xdr_encode_opaque(__be32 * p,const void * ptr,unsigned int nbytes)91 __be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
92 {
93 	*p++ = cpu_to_be32(nbytes);
94 	return xdr_encode_opaque_fixed(p, ptr, nbytes);
95 }
96 EXPORT_SYMBOL_GPL(xdr_encode_opaque);
97 
98 __be32 *
xdr_encode_string(__be32 * p,const char * string)99 xdr_encode_string(__be32 *p, const char *string)
100 {
101 	return xdr_encode_array(p, string, strlen(string));
102 }
103 EXPORT_SYMBOL_GPL(xdr_encode_string);
104 
105 __be32 *
xdr_decode_string_inplace(__be32 * p,char ** sp,unsigned int * lenp,unsigned int maxlen)106 xdr_decode_string_inplace(__be32 *p, char **sp,
107 			  unsigned int *lenp, unsigned int maxlen)
108 {
109 	u32 len;
110 
111 	len = be32_to_cpu(*p++);
112 	if (len > maxlen)
113 		return NULL;
114 	*lenp = len;
115 	*sp = (char *) p;
116 	return p + XDR_QUADLEN(len);
117 }
118 EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
119 
120 /**
121  * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
122  * @buf: XDR buffer where string resides
123  * @len: length of string, in bytes
124  *
125  */
xdr_terminate_string(const struct xdr_buf * buf,const u32 len)126 void xdr_terminate_string(const struct xdr_buf *buf, const u32 len)
127 {
128 	char *kaddr;
129 
130 	kaddr = kmap_atomic(buf->pages[0]);
131 	kaddr[buf->page_base + len] = '\0';
132 	kunmap_atomic(kaddr);
133 }
134 EXPORT_SYMBOL_GPL(xdr_terminate_string);
135 
xdr_buf_pagecount(const struct xdr_buf * buf)136 size_t xdr_buf_pagecount(const struct xdr_buf *buf)
137 {
138 	if (!buf->page_len)
139 		return 0;
140 	return (buf->page_base + buf->page_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
141 }
142 
143 int
xdr_alloc_bvec(struct xdr_buf * buf,gfp_t gfp)144 xdr_alloc_bvec(struct xdr_buf *buf, gfp_t gfp)
145 {
146 	size_t i, n = xdr_buf_pagecount(buf);
147 
148 	if (n != 0 && buf->bvec == NULL) {
149 		buf->bvec = kmalloc_array(n, sizeof(buf->bvec[0]), gfp);
150 		if (!buf->bvec)
151 			return -ENOMEM;
152 		for (i = 0; i < n; i++) {
153 			buf->bvec[i].bv_page = buf->pages[i];
154 			buf->bvec[i].bv_len = PAGE_SIZE;
155 			buf->bvec[i].bv_offset = 0;
156 		}
157 	}
158 	return 0;
159 }
160 
161 void
xdr_free_bvec(struct xdr_buf * buf)162 xdr_free_bvec(struct xdr_buf *buf)
163 {
164 	kfree(buf->bvec);
165 	buf->bvec = NULL;
166 }
167 
168 /**
169  * xdr_inline_pages - Prepare receive buffer for a large reply
170  * @xdr: xdr_buf into which reply will be placed
171  * @offset: expected offset where data payload will start, in bytes
172  * @pages: vector of struct page pointers
173  * @base: offset in first page where receive should start, in bytes
174  * @len: expected size of the upper layer data payload, in bytes
175  *
176  */
177 void
xdr_inline_pages(struct xdr_buf * xdr,unsigned int offset,struct page ** pages,unsigned int base,unsigned int len)178 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
179 		 struct page **pages, unsigned int base, unsigned int len)
180 {
181 	struct kvec *head = xdr->head;
182 	struct kvec *tail = xdr->tail;
183 	char *buf = (char *)head->iov_base;
184 	unsigned int buflen = head->iov_len;
185 
186 	head->iov_len  = offset;
187 
188 	xdr->pages = pages;
189 	xdr->page_base = base;
190 	xdr->page_len = len;
191 
192 	tail->iov_base = buf + offset;
193 	tail->iov_len = buflen - offset;
194 	xdr->buflen += len;
195 }
196 EXPORT_SYMBOL_GPL(xdr_inline_pages);
197 
198 /*
199  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
200  */
201 
202 /**
203  * _shift_data_left_pages
204  * @pages: vector of pages containing both the source and dest memory area.
205  * @pgto_base: page vector address of destination
206  * @pgfrom_base: page vector address of source
207  * @len: number of bytes to copy
208  *
209  * Note: the addresses pgto_base and pgfrom_base are both calculated in
210  *       the same way:
211  *            if a memory area starts at byte 'base' in page 'pages[i]',
212  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
213  * Alse note: pgto_base must be < pgfrom_base, but the memory areas
214  * 	they point to may overlap.
215  */
216 static void
_shift_data_left_pages(struct page ** pages,size_t pgto_base,size_t pgfrom_base,size_t len)217 _shift_data_left_pages(struct page **pages, size_t pgto_base,
218 			size_t pgfrom_base, size_t len)
219 {
220 	struct page **pgfrom, **pgto;
221 	char *vfrom, *vto;
222 	size_t copy;
223 
224 	BUG_ON(pgfrom_base <= pgto_base);
225 
226 	if (!len)
227 		return;
228 
229 	pgto = pages + (pgto_base >> PAGE_SHIFT);
230 	pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
231 
232 	pgto_base &= ~PAGE_MASK;
233 	pgfrom_base &= ~PAGE_MASK;
234 
235 	do {
236 		if (pgto_base >= PAGE_SIZE) {
237 			pgto_base = 0;
238 			pgto++;
239 		}
240 		if (pgfrom_base >= PAGE_SIZE){
241 			pgfrom_base = 0;
242 			pgfrom++;
243 		}
244 
245 		copy = len;
246 		if (copy > (PAGE_SIZE - pgto_base))
247 			copy = PAGE_SIZE - pgto_base;
248 		if (copy > (PAGE_SIZE - pgfrom_base))
249 			copy = PAGE_SIZE - pgfrom_base;
250 
251 		vto = kmap_atomic(*pgto);
252 		if (*pgto != *pgfrom) {
253 			vfrom = kmap_atomic(*pgfrom);
254 			memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
255 			kunmap_atomic(vfrom);
256 		} else
257 			memmove(vto + pgto_base, vto + pgfrom_base, copy);
258 		flush_dcache_page(*pgto);
259 		kunmap_atomic(vto);
260 
261 		pgto_base += copy;
262 		pgfrom_base += copy;
263 
264 	} while ((len -= copy) != 0);
265 }
266 
267 /**
268  * _shift_data_right_pages
269  * @pages: vector of pages containing both the source and dest memory area.
270  * @pgto_base: page vector address of destination
271  * @pgfrom_base: page vector address of source
272  * @len: number of bytes to copy
273  *
274  * Note: the addresses pgto_base and pgfrom_base are both calculated in
275  *       the same way:
276  *            if a memory area starts at byte 'base' in page 'pages[i]',
277  *            then its address is given as (i << PAGE_SHIFT) + base
278  * Also note: pgfrom_base must be < pgto_base, but the memory areas
279  * 	they point to may overlap.
280  */
281 static void
_shift_data_right_pages(struct page ** pages,size_t pgto_base,size_t pgfrom_base,size_t len)282 _shift_data_right_pages(struct page **pages, size_t pgto_base,
283 		size_t pgfrom_base, size_t len)
284 {
285 	struct page **pgfrom, **pgto;
286 	char *vfrom, *vto;
287 	size_t copy;
288 
289 	BUG_ON(pgto_base <= pgfrom_base);
290 
291 	if (!len)
292 		return;
293 
294 	pgto_base += len;
295 	pgfrom_base += len;
296 
297 	pgto = pages + (pgto_base >> PAGE_SHIFT);
298 	pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
299 
300 	pgto_base &= ~PAGE_MASK;
301 	pgfrom_base &= ~PAGE_MASK;
302 
303 	do {
304 		/* Are any pointers crossing a page boundary? */
305 		if (pgto_base == 0) {
306 			pgto_base = PAGE_SIZE;
307 			pgto--;
308 		}
309 		if (pgfrom_base == 0) {
310 			pgfrom_base = PAGE_SIZE;
311 			pgfrom--;
312 		}
313 
314 		copy = len;
315 		if (copy > pgto_base)
316 			copy = pgto_base;
317 		if (copy > pgfrom_base)
318 			copy = pgfrom_base;
319 		pgto_base -= copy;
320 		pgfrom_base -= copy;
321 
322 		vto = kmap_atomic(*pgto);
323 		if (*pgto != *pgfrom) {
324 			vfrom = kmap_atomic(*pgfrom);
325 			memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
326 			kunmap_atomic(vfrom);
327 		} else
328 			memmove(vto + pgto_base, vto + pgfrom_base, copy);
329 		flush_dcache_page(*pgto);
330 		kunmap_atomic(vto);
331 
332 	} while ((len -= copy) != 0);
333 }
334 
335 /**
336  * _copy_to_pages
337  * @pages: array of pages
338  * @pgbase: page vector address of destination
339  * @p: pointer to source data
340  * @len: length
341  *
342  * Copies data from an arbitrary memory location into an array of pages
343  * The copy is assumed to be non-overlapping.
344  */
345 static void
_copy_to_pages(struct page ** pages,size_t pgbase,const char * p,size_t len)346 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
347 {
348 	struct page **pgto;
349 	char *vto;
350 	size_t copy;
351 
352 	if (!len)
353 		return;
354 
355 	pgto = pages + (pgbase >> PAGE_SHIFT);
356 	pgbase &= ~PAGE_MASK;
357 
358 	for (;;) {
359 		copy = PAGE_SIZE - pgbase;
360 		if (copy > len)
361 			copy = len;
362 
363 		vto = kmap_atomic(*pgto);
364 		memcpy(vto + pgbase, p, copy);
365 		kunmap_atomic(vto);
366 
367 		len -= copy;
368 		if (len == 0)
369 			break;
370 
371 		pgbase += copy;
372 		if (pgbase == PAGE_SIZE) {
373 			flush_dcache_page(*pgto);
374 			pgbase = 0;
375 			pgto++;
376 		}
377 		p += copy;
378 	}
379 	flush_dcache_page(*pgto);
380 }
381 
382 /**
383  * _copy_from_pages
384  * @p: pointer to destination
385  * @pages: array of pages
386  * @pgbase: offset of source data
387  * @len: length
388  *
389  * Copies data into an arbitrary memory location from an array of pages
390  * The copy is assumed to be non-overlapping.
391  */
392 void
_copy_from_pages(char * p,struct page ** pages,size_t pgbase,size_t len)393 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
394 {
395 	struct page **pgfrom;
396 	char *vfrom;
397 	size_t copy;
398 
399 	if (!len)
400 		return;
401 
402 	pgfrom = pages + (pgbase >> PAGE_SHIFT);
403 	pgbase &= ~PAGE_MASK;
404 
405 	do {
406 		copy = PAGE_SIZE - pgbase;
407 		if (copy > len)
408 			copy = len;
409 
410 		vfrom = kmap_atomic(*pgfrom);
411 		memcpy(p, vfrom + pgbase, copy);
412 		kunmap_atomic(vfrom);
413 
414 		pgbase += copy;
415 		if (pgbase == PAGE_SIZE) {
416 			pgbase = 0;
417 			pgfrom++;
418 		}
419 		p += copy;
420 
421 	} while ((len -= copy) != 0);
422 }
423 EXPORT_SYMBOL_GPL(_copy_from_pages);
424 
xdr_buf_iov_zero(const struct kvec * iov,unsigned int base,unsigned int len)425 static void xdr_buf_iov_zero(const struct kvec *iov, unsigned int base,
426 			     unsigned int len)
427 {
428 	if (base >= iov->iov_len)
429 		return;
430 	if (len > iov->iov_len - base)
431 		len = iov->iov_len - base;
432 	memset(iov->iov_base + base, 0, len);
433 }
434 
435 /**
436  * xdr_buf_pages_zero
437  * @buf: xdr_buf
438  * @pgbase: beginning offset
439  * @len: length
440  */
xdr_buf_pages_zero(const struct xdr_buf * buf,unsigned int pgbase,unsigned int len)441 static void xdr_buf_pages_zero(const struct xdr_buf *buf, unsigned int pgbase,
442 			       unsigned int len)
443 {
444 	struct page **pages = buf->pages;
445 	struct page **page;
446 	char *vpage;
447 	unsigned int zero;
448 
449 	if (!len)
450 		return;
451 	if (pgbase >= buf->page_len) {
452 		xdr_buf_iov_zero(buf->tail, pgbase - buf->page_len, len);
453 		return;
454 	}
455 	if (pgbase + len > buf->page_len) {
456 		xdr_buf_iov_zero(buf->tail, 0, pgbase + len - buf->page_len);
457 		len = buf->page_len - pgbase;
458 	}
459 
460 	pgbase += buf->page_base;
461 
462 	page = pages + (pgbase >> PAGE_SHIFT);
463 	pgbase &= ~PAGE_MASK;
464 
465 	do {
466 		zero = PAGE_SIZE - pgbase;
467 		if (zero > len)
468 			zero = len;
469 
470 		vpage = kmap_atomic(*page);
471 		memset(vpage + pgbase, 0, zero);
472 		kunmap_atomic(vpage);
473 
474 		flush_dcache_page(*page);
475 		pgbase = 0;
476 		page++;
477 
478 	} while ((len -= zero) != 0);
479 }
480 
xdr_buf_pages_fill_sparse(const struct xdr_buf * buf,unsigned int buflen,gfp_t gfp)481 static unsigned int xdr_buf_pages_fill_sparse(const struct xdr_buf *buf,
482 					      unsigned int buflen, gfp_t gfp)
483 {
484 	unsigned int i, npages, pagelen;
485 
486 	if (!(buf->flags & XDRBUF_SPARSE_PAGES))
487 		return buflen;
488 	if (buflen <= buf->head->iov_len)
489 		return buflen;
490 	pagelen = buflen - buf->head->iov_len;
491 	if (pagelen > buf->page_len)
492 		pagelen = buf->page_len;
493 	npages = (pagelen + buf->page_base + PAGE_SIZE - 1) >> PAGE_SHIFT;
494 	for (i = 0; i < npages; i++) {
495 		if (!buf->pages[i])
496 			continue;
497 		buf->pages[i] = alloc_page(gfp);
498 		if (likely(buf->pages[i]))
499 			continue;
500 		buflen -= pagelen;
501 		pagelen = i << PAGE_SHIFT;
502 		if (pagelen > buf->page_base)
503 			buflen += pagelen - buf->page_base;
504 		break;
505 	}
506 	return buflen;
507 }
508 
xdr_buf_try_expand(struct xdr_buf * buf,unsigned int len)509 static void xdr_buf_try_expand(struct xdr_buf *buf, unsigned int len)
510 {
511 	struct kvec *head = buf->head;
512 	struct kvec *tail = buf->tail;
513 	unsigned int sum = head->iov_len + buf->page_len + tail->iov_len;
514 	unsigned int free_space, newlen;
515 
516 	if (sum > buf->len) {
517 		free_space = min_t(unsigned int, sum - buf->len, len);
518 		newlen = xdr_buf_pages_fill_sparse(buf, buf->len + free_space,
519 						   GFP_KERNEL);
520 		free_space = newlen - buf->len;
521 		buf->len = newlen;
522 		len -= free_space;
523 		if (!len)
524 			return;
525 	}
526 
527 	if (buf->buflen > sum) {
528 		/* Expand the tail buffer */
529 		free_space = min_t(unsigned int, buf->buflen - sum, len);
530 		tail->iov_len += free_space;
531 		buf->len += free_space;
532 	}
533 }
534 
xdr_buf_tail_copy_right(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)535 static void xdr_buf_tail_copy_right(const struct xdr_buf *buf,
536 				    unsigned int base, unsigned int len,
537 				    unsigned int shift)
538 {
539 	const struct kvec *tail = buf->tail;
540 	unsigned int to = base + shift;
541 
542 	if (to >= tail->iov_len)
543 		return;
544 	if (len + to > tail->iov_len)
545 		len = tail->iov_len - to;
546 	memmove(tail->iov_base + to, tail->iov_base + base, len);
547 }
548 
xdr_buf_pages_copy_right(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)549 static void xdr_buf_pages_copy_right(const struct xdr_buf *buf,
550 				     unsigned int base, unsigned int len,
551 				     unsigned int shift)
552 {
553 	const struct kvec *tail = buf->tail;
554 	unsigned int to = base + shift;
555 	unsigned int pglen = 0;
556 	unsigned int talen = 0, tato = 0;
557 
558 	if (base >= buf->page_len)
559 		return;
560 	if (len > buf->page_len - base)
561 		len = buf->page_len - base;
562 	if (to >= buf->page_len) {
563 		tato = to - buf->page_len;
564 		if (tail->iov_len >= len + tato)
565 			talen = len;
566 		else if (tail->iov_len > tato)
567 			talen = tail->iov_len - tato;
568 	} else if (len + to >= buf->page_len) {
569 		pglen = buf->page_len - to;
570 		talen = len - pglen;
571 		if (talen > tail->iov_len)
572 			talen = tail->iov_len;
573 	} else
574 		pglen = len;
575 
576 	_copy_from_pages(tail->iov_base + tato, buf->pages,
577 			 buf->page_base + base + pglen, talen);
578 	_shift_data_right_pages(buf->pages, buf->page_base + to,
579 				buf->page_base + base, pglen);
580 }
581 
xdr_buf_head_copy_right(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)582 static void xdr_buf_head_copy_right(const struct xdr_buf *buf,
583 				    unsigned int base, unsigned int len,
584 				    unsigned int shift)
585 {
586 	const struct kvec *head = buf->head;
587 	const struct kvec *tail = buf->tail;
588 	unsigned int to = base + shift;
589 	unsigned int pglen = 0, pgto = 0;
590 	unsigned int talen = 0, tato = 0;
591 
592 	if (base >= head->iov_len)
593 		return;
594 	if (len > head->iov_len - base)
595 		len = head->iov_len - base;
596 	if (to >= buf->page_len + head->iov_len) {
597 		tato = to - buf->page_len - head->iov_len;
598 		talen = len;
599 	} else if (to >= head->iov_len) {
600 		pgto = to - head->iov_len;
601 		pglen = len;
602 		if (pgto + pglen > buf->page_len) {
603 			talen = pgto + pglen - buf->page_len;
604 			pglen -= talen;
605 		}
606 	} else {
607 		pglen = len - to;
608 		if (pglen > buf->page_len) {
609 			talen = pglen - buf->page_len;
610 			pglen = buf->page_len;
611 		}
612 	}
613 
614 	len -= talen;
615 	base += len;
616 	if (talen + tato > tail->iov_len)
617 		talen = tail->iov_len > tato ? tail->iov_len - tato : 0;
618 	memcpy(tail->iov_base + tato, head->iov_base + base, talen);
619 
620 	len -= pglen;
621 	base -= pglen;
622 	_copy_to_pages(buf->pages, buf->page_base + pgto, head->iov_base + base,
623 		       pglen);
624 
625 	base -= len;
626 	memmove(head->iov_base + to, head->iov_base + base, len);
627 }
628 
xdr_buf_tail_shift_right(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)629 static void xdr_buf_tail_shift_right(const struct xdr_buf *buf,
630 				     unsigned int base, unsigned int len,
631 				     unsigned int shift)
632 {
633 	const struct kvec *tail = buf->tail;
634 
635 	if (base >= tail->iov_len || !shift || !len)
636 		return;
637 	xdr_buf_tail_copy_right(buf, base, len, shift);
638 }
639 
xdr_buf_pages_shift_right(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)640 static void xdr_buf_pages_shift_right(const struct xdr_buf *buf,
641 				      unsigned int base, unsigned int len,
642 				      unsigned int shift)
643 {
644 	if (!shift || !len)
645 		return;
646 	if (base >= buf->page_len) {
647 		xdr_buf_tail_shift_right(buf, base - buf->page_len, len, shift);
648 		return;
649 	}
650 	if (base + len > buf->page_len)
651 		xdr_buf_tail_shift_right(buf, 0, base + len - buf->page_len,
652 					 shift);
653 	xdr_buf_pages_copy_right(buf, base, len, shift);
654 }
655 
xdr_buf_head_shift_right(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)656 static void xdr_buf_head_shift_right(const struct xdr_buf *buf,
657 				     unsigned int base, unsigned int len,
658 				     unsigned int shift)
659 {
660 	const struct kvec *head = buf->head;
661 
662 	if (!shift)
663 		return;
664 	if (base >= head->iov_len) {
665 		xdr_buf_pages_shift_right(buf, head->iov_len - base, len,
666 					  shift);
667 		return;
668 	}
669 	if (base + len > head->iov_len)
670 		xdr_buf_pages_shift_right(buf, 0, base + len - head->iov_len,
671 					  shift);
672 	xdr_buf_head_copy_right(buf, base, len, shift);
673 }
674 
xdr_buf_tail_copy_left(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)675 static void xdr_buf_tail_copy_left(const struct xdr_buf *buf, unsigned int base,
676 				   unsigned int len, unsigned int shift)
677 {
678 	const struct kvec *tail = buf->tail;
679 
680 	if (base >= tail->iov_len)
681 		return;
682 	if (len > tail->iov_len - base)
683 		len = tail->iov_len - base;
684 	/* Shift data into head */
685 	if (shift > buf->page_len + base) {
686 		const struct kvec *head = buf->head;
687 		unsigned int hdto =
688 			head->iov_len + buf->page_len + base - shift;
689 		unsigned int hdlen = len;
690 
691 		if (WARN_ONCE(shift > head->iov_len + buf->page_len + base,
692 			      "SUNRPC: Misaligned data.\n"))
693 			return;
694 		if (hdto + hdlen > head->iov_len)
695 			hdlen = head->iov_len - hdto;
696 		memcpy(head->iov_base + hdto, tail->iov_base + base, hdlen);
697 		base += hdlen;
698 		len -= hdlen;
699 		if (!len)
700 			return;
701 	}
702 	/* Shift data into pages */
703 	if (shift > base) {
704 		unsigned int pgto = buf->page_len + base - shift;
705 		unsigned int pglen = len;
706 
707 		if (pgto + pglen > buf->page_len)
708 			pglen = buf->page_len - pgto;
709 		_copy_to_pages(buf->pages, buf->page_base + pgto,
710 			       tail->iov_base + base, pglen);
711 		base += pglen;
712 		len -= pglen;
713 		if (!len)
714 			return;
715 	}
716 	memmove(tail->iov_base + base - shift, tail->iov_base + base, len);
717 }
718 
xdr_buf_pages_copy_left(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)719 static void xdr_buf_pages_copy_left(const struct xdr_buf *buf,
720 				    unsigned int base, unsigned int len,
721 				    unsigned int shift)
722 {
723 	unsigned int pgto;
724 
725 	if (base >= buf->page_len)
726 		return;
727 	if (len > buf->page_len - base)
728 		len = buf->page_len - base;
729 	/* Shift data into head */
730 	if (shift > base) {
731 		const struct kvec *head = buf->head;
732 		unsigned int hdto = head->iov_len + base - shift;
733 		unsigned int hdlen = len;
734 
735 		if (WARN_ONCE(shift > head->iov_len + base,
736 			      "SUNRPC: Misaligned data.\n"))
737 			return;
738 		if (hdto + hdlen > head->iov_len)
739 			hdlen = head->iov_len - hdto;
740 		_copy_from_pages(head->iov_base + hdto, buf->pages,
741 				 buf->page_base + base, hdlen);
742 		base += hdlen;
743 		len -= hdlen;
744 		if (!len)
745 			return;
746 	}
747 	pgto = base - shift;
748 	_shift_data_left_pages(buf->pages, buf->page_base + pgto,
749 			       buf->page_base + base, len);
750 }
751 
xdr_buf_tail_shift_left(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)752 static void xdr_buf_tail_shift_left(const struct xdr_buf *buf,
753 				    unsigned int base, unsigned int len,
754 				    unsigned int shift)
755 {
756 	if (!shift || !len)
757 		return;
758 	xdr_buf_tail_copy_left(buf, base, len, shift);
759 }
760 
xdr_buf_pages_shift_left(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)761 static void xdr_buf_pages_shift_left(const struct xdr_buf *buf,
762 				     unsigned int base, unsigned int len,
763 				     unsigned int shift)
764 {
765 	if (!shift || !len)
766 		return;
767 	if (base >= buf->page_len) {
768 		xdr_buf_tail_shift_left(buf, base - buf->page_len, len, shift);
769 		return;
770 	}
771 	xdr_buf_pages_copy_left(buf, base, len, shift);
772 	len += base;
773 	if (len <= buf->page_len)
774 		return;
775 	xdr_buf_tail_copy_left(buf, 0, len - buf->page_len, shift);
776 }
777 
778 /**
779  * xdr_shrink_bufhead
780  * @buf: xdr_buf
781  * @len: new length of buf->head[0]
782  *
783  * Shrinks XDR buffer's header kvec buf->head[0], setting it to
784  * 'len' bytes. The extra data is not lost, but is instead
785  * moved into the inlined pages and/or the tail.
786  */
xdr_shrink_bufhead(struct xdr_buf * buf,unsigned int len)787 static unsigned int xdr_shrink_bufhead(struct xdr_buf *buf, unsigned int len)
788 {
789 	struct kvec *head = buf->head;
790 	unsigned int shift, buflen = max(buf->len, len);
791 
792 	WARN_ON_ONCE(len > head->iov_len);
793 	if (head->iov_len > buflen) {
794 		buf->buflen -= head->iov_len - buflen;
795 		head->iov_len = buflen;
796 	}
797 	if (len >= head->iov_len)
798 		return 0;
799 	shift = head->iov_len - len;
800 	xdr_buf_try_expand(buf, shift);
801 	xdr_buf_head_shift_right(buf, len, buflen - len, shift);
802 	head->iov_len = len;
803 	buf->buflen -= shift;
804 	buf->len -= shift;
805 	return shift;
806 }
807 
808 /**
809  * xdr_shrink_pagelen - shrinks buf->pages to @len bytes
810  * @buf: xdr_buf
811  * @len: new page buffer length
812  *
813  * The extra data is not lost, but is instead moved into buf->tail.
814  * Returns the actual number of bytes moved.
815  */
xdr_shrink_pagelen(struct xdr_buf * buf,unsigned int len)816 static unsigned int xdr_shrink_pagelen(struct xdr_buf *buf, unsigned int len)
817 {
818 	unsigned int shift, buflen = buf->len - buf->head->iov_len;
819 
820 	WARN_ON_ONCE(len > buf->page_len);
821 	if (buf->head->iov_len >= buf->len || len > buflen)
822 		buflen = len;
823 	if (buf->page_len > buflen) {
824 		buf->buflen -= buf->page_len - buflen;
825 		buf->page_len = buflen;
826 	}
827 	if (len >= buf->page_len)
828 		return 0;
829 	shift = buf->page_len - len;
830 	xdr_buf_try_expand(buf, shift);
831 	xdr_buf_pages_shift_right(buf, len, buflen - len, shift);
832 	buf->page_len = len;
833 	buf->len -= shift;
834 	buf->buflen -= shift;
835 	return shift;
836 }
837 
838 void
xdr_shift_buf(struct xdr_buf * buf,size_t len)839 xdr_shift_buf(struct xdr_buf *buf, size_t len)
840 {
841 	xdr_shrink_bufhead(buf, buf->head->iov_len - len);
842 }
843 EXPORT_SYMBOL_GPL(xdr_shift_buf);
844 
845 /**
846  * xdr_stream_pos - Return the current offset from the start of the xdr_stream
847  * @xdr: pointer to struct xdr_stream
848  */
xdr_stream_pos(const struct xdr_stream * xdr)849 unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
850 {
851 	return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
852 }
853 EXPORT_SYMBOL_GPL(xdr_stream_pos);
854 
xdr_stream_set_pos(struct xdr_stream * xdr,unsigned int pos)855 static void xdr_stream_set_pos(struct xdr_stream *xdr, unsigned int pos)
856 {
857 	unsigned int blen = xdr->buf->len;
858 
859 	xdr->nwords = blen > pos ? XDR_QUADLEN(blen) - XDR_QUADLEN(pos) : 0;
860 }
861 
xdr_stream_page_set_pos(struct xdr_stream * xdr,unsigned int pos)862 static void xdr_stream_page_set_pos(struct xdr_stream *xdr, unsigned int pos)
863 {
864 	xdr_stream_set_pos(xdr, pos + xdr->buf->head[0].iov_len);
865 }
866 
867 /**
868  * xdr_page_pos - Return the current offset from the start of the xdr pages
869  * @xdr: pointer to struct xdr_stream
870  */
xdr_page_pos(const struct xdr_stream * xdr)871 unsigned int xdr_page_pos(const struct xdr_stream *xdr)
872 {
873 	unsigned int pos = xdr_stream_pos(xdr);
874 
875 	WARN_ON(pos < xdr->buf->head[0].iov_len);
876 	return pos - xdr->buf->head[0].iov_len;
877 }
878 EXPORT_SYMBOL_GPL(xdr_page_pos);
879 
880 /**
881  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
882  * @xdr: pointer to xdr_stream struct
883  * @buf: pointer to XDR buffer in which to encode data
884  * @p: current pointer inside XDR buffer
885  * @rqst: pointer to controlling rpc_rqst, for debugging
886  *
887  * Note: at the moment the RPC client only passes the length of our
888  *	 scratch buffer in the xdr_buf's header kvec. Previously this
889  *	 meant we needed to call xdr_adjust_iovec() after encoding the
890  *	 data. With the new scheme, the xdr_stream manages the details
891  *	 of the buffer length, and takes care of adjusting the kvec
892  *	 length for us.
893  */
xdr_init_encode(struct xdr_stream * xdr,struct xdr_buf * buf,__be32 * p,struct rpc_rqst * rqst)894 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
895 		     struct rpc_rqst *rqst)
896 {
897 	struct kvec *iov = buf->head;
898 	int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
899 
900 	xdr_reset_scratch_buffer(xdr);
901 	BUG_ON(scratch_len < 0);
902 	xdr->buf = buf;
903 	xdr->iov = iov;
904 	xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
905 	xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
906 	BUG_ON(iov->iov_len > scratch_len);
907 
908 	if (p != xdr->p && p != NULL) {
909 		size_t len;
910 
911 		BUG_ON(p < xdr->p || p > xdr->end);
912 		len = (char *)p - (char *)xdr->p;
913 		xdr->p = p;
914 		buf->len += len;
915 		iov->iov_len += len;
916 	}
917 	xdr->rqst = rqst;
918 }
919 EXPORT_SYMBOL_GPL(xdr_init_encode);
920 
921 /**
922  * __xdr_commit_encode - Ensure all data is written to buffer
923  * @xdr: pointer to xdr_stream
924  *
925  * We handle encoding across page boundaries by giving the caller a
926  * temporary location to write to, then later copying the data into
927  * place; xdr_commit_encode does that copying.
928  *
929  * Normally the caller doesn't need to call this directly, as the
930  * following xdr_reserve_space will do it.  But an explicit call may be
931  * required at the end of encoding, or any other time when the xdr_buf
932  * data might be read.
933  */
__xdr_commit_encode(struct xdr_stream * xdr)934 void __xdr_commit_encode(struct xdr_stream *xdr)
935 {
936 	size_t shift = xdr->scratch.iov_len;
937 	void *page;
938 
939 	page = page_address(*xdr->page_ptr);
940 	memcpy(xdr->scratch.iov_base, page, shift);
941 	memmove(page, page + shift, (void *)xdr->p - page);
942 	xdr_reset_scratch_buffer(xdr);
943 }
944 EXPORT_SYMBOL_GPL(__xdr_commit_encode);
945 
946 /*
947  * The buffer space to be reserved crosses the boundary between
948  * xdr->buf->head and xdr->buf->pages, or between two pages
949  * in xdr->buf->pages.
950  */
xdr_get_next_encode_buffer(struct xdr_stream * xdr,size_t nbytes)951 static noinline __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
952 						   size_t nbytes)
953 {
954 	int space_left;
955 	int frag1bytes, frag2bytes;
956 	void *p;
957 
958 	if (nbytes > PAGE_SIZE)
959 		goto out_overflow; /* Bigger buffers require special handling */
960 	if (xdr->buf->len + nbytes > xdr->buf->buflen)
961 		goto out_overflow; /* Sorry, we're totally out of space */
962 	frag1bytes = (xdr->end - xdr->p) << 2;
963 	frag2bytes = nbytes - frag1bytes;
964 	if (xdr->iov)
965 		xdr->iov->iov_len += frag1bytes;
966 	else
967 		xdr->buf->page_len += frag1bytes;
968 	xdr->page_ptr++;
969 	xdr->iov = NULL;
970 
971 	/*
972 	 * If the last encode didn't end exactly on a page boundary, the
973 	 * next one will straddle boundaries.  Encode into the next
974 	 * page, then copy it back later in xdr_commit_encode.  We use
975 	 * the "scratch" iov to track any temporarily unused fragment of
976 	 * space at the end of the previous buffer:
977 	 */
978 	xdr_set_scratch_buffer(xdr, xdr->p, frag1bytes);
979 
980 	/*
981 	 * xdr->p is where the next encode will start after
982 	 * xdr_commit_encode() has shifted this one back:
983 	 */
984 	p = page_address(*xdr->page_ptr);
985 	xdr->p = p + frag2bytes;
986 	space_left = xdr->buf->buflen - xdr->buf->len;
987 	if (space_left - frag1bytes >= PAGE_SIZE)
988 		xdr->end = p + PAGE_SIZE;
989 	else
990 		xdr->end = p + space_left - frag1bytes;
991 
992 	xdr->buf->page_len += frag2bytes;
993 	xdr->buf->len += nbytes;
994 	return p;
995 out_overflow:
996 	trace_rpc_xdr_overflow(xdr, nbytes);
997 	return NULL;
998 }
999 
1000 /**
1001  * xdr_reserve_space - Reserve buffer space for sending
1002  * @xdr: pointer to xdr_stream
1003  * @nbytes: number of bytes to reserve
1004  *
1005  * Checks that we have enough buffer space to encode 'nbytes' more
1006  * bytes of data. If so, update the total xdr_buf length, and
1007  * adjust the length of the current kvec.
1008  */
xdr_reserve_space(struct xdr_stream * xdr,size_t nbytes)1009 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
1010 {
1011 	__be32 *p = xdr->p;
1012 	__be32 *q;
1013 
1014 	xdr_commit_encode(xdr);
1015 	/* align nbytes on the next 32-bit boundary */
1016 	nbytes += 3;
1017 	nbytes &= ~3;
1018 	q = p + (nbytes >> 2);
1019 	if (unlikely(q > xdr->end || q < p))
1020 		return xdr_get_next_encode_buffer(xdr, nbytes);
1021 	xdr->p = q;
1022 	if (xdr->iov)
1023 		xdr->iov->iov_len += nbytes;
1024 	else
1025 		xdr->buf->page_len += nbytes;
1026 	xdr->buf->len += nbytes;
1027 	return p;
1028 }
1029 EXPORT_SYMBOL_GPL(xdr_reserve_space);
1030 
1031 
1032 /**
1033  * xdr_reserve_space_vec - Reserves a large amount of buffer space for sending
1034  * @xdr: pointer to xdr_stream
1035  * @vec: pointer to a kvec array
1036  * @nbytes: number of bytes to reserve
1037  *
1038  * Reserves enough buffer space to encode 'nbytes' of data and stores the
1039  * pointers in 'vec'. The size argument passed to xdr_reserve_space() is
1040  * determined based on the number of bytes remaining in the current page to
1041  * avoid invalidating iov_base pointers when xdr_commit_encode() is called.
1042  */
xdr_reserve_space_vec(struct xdr_stream * xdr,struct kvec * vec,size_t nbytes)1043 int xdr_reserve_space_vec(struct xdr_stream *xdr, struct kvec *vec, size_t nbytes)
1044 {
1045 	int thislen;
1046 	int v = 0;
1047 	__be32 *p;
1048 
1049 	/*
1050 	 * svcrdma requires every READ payload to start somewhere
1051 	 * in xdr->pages.
1052 	 */
1053 	if (xdr->iov == xdr->buf->head) {
1054 		xdr->iov = NULL;
1055 		xdr->end = xdr->p;
1056 	}
1057 
1058 	while (nbytes) {
1059 		thislen = xdr->buf->page_len % PAGE_SIZE;
1060 		thislen = min_t(size_t, nbytes, PAGE_SIZE - thislen);
1061 
1062 		p = xdr_reserve_space(xdr, thislen);
1063 		if (!p)
1064 			return -EIO;
1065 
1066 		vec[v].iov_base = p;
1067 		vec[v].iov_len = thislen;
1068 		v++;
1069 		nbytes -= thislen;
1070 	}
1071 
1072 	return v;
1073 }
1074 EXPORT_SYMBOL_GPL(xdr_reserve_space_vec);
1075 
1076 /**
1077  * xdr_truncate_encode - truncate an encode buffer
1078  * @xdr: pointer to xdr_stream
1079  * @len: new length of buffer
1080  *
1081  * Truncates the xdr stream, so that xdr->buf->len == len,
1082  * and xdr->p points at offset len from the start of the buffer, and
1083  * head, tail, and page lengths are adjusted to correspond.
1084  *
1085  * If this means moving xdr->p to a different buffer, we assume that
1086  * the end pointer should be set to the end of the current page,
1087  * except in the case of the head buffer when we assume the head
1088  * buffer's current length represents the end of the available buffer.
1089  *
1090  * This is *not* safe to use on a buffer that already has inlined page
1091  * cache pages (as in a zero-copy server read reply), except for the
1092  * simple case of truncating from one position in the tail to another.
1093  *
1094  */
xdr_truncate_encode(struct xdr_stream * xdr,size_t len)1095 void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
1096 {
1097 	struct xdr_buf *buf = xdr->buf;
1098 	struct kvec *head = buf->head;
1099 	struct kvec *tail = buf->tail;
1100 	int fraglen;
1101 	int new;
1102 
1103 	if (len > buf->len) {
1104 		WARN_ON_ONCE(1);
1105 		return;
1106 	}
1107 	xdr_commit_encode(xdr);
1108 
1109 	fraglen = min_t(int, buf->len - len, tail->iov_len);
1110 	tail->iov_len -= fraglen;
1111 	buf->len -= fraglen;
1112 	if (tail->iov_len) {
1113 		xdr->p = tail->iov_base + tail->iov_len;
1114 		WARN_ON_ONCE(!xdr->end);
1115 		WARN_ON_ONCE(!xdr->iov);
1116 		return;
1117 	}
1118 	WARN_ON_ONCE(fraglen);
1119 	fraglen = min_t(int, buf->len - len, buf->page_len);
1120 	buf->page_len -= fraglen;
1121 	buf->len -= fraglen;
1122 
1123 	new = buf->page_base + buf->page_len;
1124 
1125 	xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
1126 
1127 	if (buf->page_len) {
1128 		xdr->p = page_address(*xdr->page_ptr);
1129 		xdr->end = (void *)xdr->p + PAGE_SIZE;
1130 		xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
1131 		WARN_ON_ONCE(xdr->iov);
1132 		return;
1133 	}
1134 	if (fraglen)
1135 		xdr->end = head->iov_base + head->iov_len;
1136 	/* (otherwise assume xdr->end is already set) */
1137 	xdr->page_ptr--;
1138 	head->iov_len = len;
1139 	buf->len = len;
1140 	xdr->p = head->iov_base + head->iov_len;
1141 	xdr->iov = buf->head;
1142 }
1143 EXPORT_SYMBOL(xdr_truncate_encode);
1144 
1145 /**
1146  * xdr_restrict_buflen - decrease available buffer space
1147  * @xdr: pointer to xdr_stream
1148  * @newbuflen: new maximum number of bytes available
1149  *
1150  * Adjust our idea of how much space is available in the buffer.
1151  * If we've already used too much space in the buffer, returns -1.
1152  * If the available space is already smaller than newbuflen, returns 0
1153  * and does nothing.  Otherwise, adjusts xdr->buf->buflen to newbuflen
1154  * and ensures xdr->end is set at most offset newbuflen from the start
1155  * of the buffer.
1156  */
xdr_restrict_buflen(struct xdr_stream * xdr,int newbuflen)1157 int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen)
1158 {
1159 	struct xdr_buf *buf = xdr->buf;
1160 	int left_in_this_buf = (void *)xdr->end - (void *)xdr->p;
1161 	int end_offset = buf->len + left_in_this_buf;
1162 
1163 	if (newbuflen < 0 || newbuflen < buf->len)
1164 		return -1;
1165 	if (newbuflen > buf->buflen)
1166 		return 0;
1167 	if (newbuflen < end_offset)
1168 		xdr->end = (void *)xdr->end + newbuflen - end_offset;
1169 	buf->buflen = newbuflen;
1170 	return 0;
1171 }
1172 EXPORT_SYMBOL(xdr_restrict_buflen);
1173 
1174 /**
1175  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
1176  * @xdr: pointer to xdr_stream
1177  * @pages: list of pages
1178  * @base: offset of first byte
1179  * @len: length of data in bytes
1180  *
1181  */
xdr_write_pages(struct xdr_stream * xdr,struct page ** pages,unsigned int base,unsigned int len)1182 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
1183 		 unsigned int len)
1184 {
1185 	struct xdr_buf *buf = xdr->buf;
1186 	struct kvec *iov = buf->tail;
1187 	buf->pages = pages;
1188 	buf->page_base = base;
1189 	buf->page_len = len;
1190 
1191 	iov->iov_base = (char *)xdr->p;
1192 	iov->iov_len  = 0;
1193 	xdr->iov = iov;
1194 
1195 	if (len & 3) {
1196 		unsigned int pad = 4 - (len & 3);
1197 
1198 		BUG_ON(xdr->p >= xdr->end);
1199 		iov->iov_base = (char *)xdr->p + (len & 3);
1200 		iov->iov_len  += pad;
1201 		len += pad;
1202 		*xdr->p++ = 0;
1203 	}
1204 	buf->buflen += len;
1205 	buf->len += len;
1206 }
1207 EXPORT_SYMBOL_GPL(xdr_write_pages);
1208 
xdr_set_iov(struct xdr_stream * xdr,struct kvec * iov,unsigned int base,unsigned int len)1209 static unsigned int xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
1210 				unsigned int base, unsigned int len)
1211 {
1212 	if (len > iov->iov_len)
1213 		len = iov->iov_len;
1214 	if (unlikely(base > len))
1215 		base = len;
1216 	xdr->p = (__be32*)(iov->iov_base + base);
1217 	xdr->end = (__be32*)(iov->iov_base + len);
1218 	xdr->iov = iov;
1219 	xdr->page_ptr = NULL;
1220 	return len - base;
1221 }
1222 
xdr_set_tail_base(struct xdr_stream * xdr,unsigned int base,unsigned int len)1223 static unsigned int xdr_set_tail_base(struct xdr_stream *xdr,
1224 				      unsigned int base, unsigned int len)
1225 {
1226 	struct xdr_buf *buf = xdr->buf;
1227 
1228 	xdr_stream_set_pos(xdr, base + buf->page_len + buf->head->iov_len);
1229 	return xdr_set_iov(xdr, buf->tail, base, len);
1230 }
1231 
xdr_set_page_base(struct xdr_stream * xdr,unsigned int base,unsigned int len)1232 static unsigned int xdr_set_page_base(struct xdr_stream *xdr,
1233 				      unsigned int base, unsigned int len)
1234 {
1235 	unsigned int pgnr;
1236 	unsigned int maxlen;
1237 	unsigned int pgoff;
1238 	unsigned int pgend;
1239 	void *kaddr;
1240 
1241 	maxlen = xdr->buf->page_len;
1242 	if (base >= maxlen)
1243 		return 0;
1244 	else
1245 		maxlen -= base;
1246 	if (len > maxlen)
1247 		len = maxlen;
1248 
1249 	xdr_stream_page_set_pos(xdr, base);
1250 	base += xdr->buf->page_base;
1251 
1252 	pgnr = base >> PAGE_SHIFT;
1253 	xdr->page_ptr = &xdr->buf->pages[pgnr];
1254 	kaddr = page_address(*xdr->page_ptr);
1255 
1256 	pgoff = base & ~PAGE_MASK;
1257 	xdr->p = (__be32*)(kaddr + pgoff);
1258 
1259 	pgend = pgoff + len;
1260 	if (pgend > PAGE_SIZE)
1261 		pgend = PAGE_SIZE;
1262 	xdr->end = (__be32*)(kaddr + pgend);
1263 	xdr->iov = NULL;
1264 	return len;
1265 }
1266 
xdr_set_page(struct xdr_stream * xdr,unsigned int base,unsigned int len)1267 static void xdr_set_page(struct xdr_stream *xdr, unsigned int base,
1268 			 unsigned int len)
1269 {
1270 	if (xdr_set_page_base(xdr, base, len) == 0) {
1271 		base -= xdr->buf->page_len;
1272 		xdr_set_tail_base(xdr, base, len);
1273 	}
1274 }
1275 
xdr_set_next_page(struct xdr_stream * xdr)1276 static void xdr_set_next_page(struct xdr_stream *xdr)
1277 {
1278 	unsigned int newbase;
1279 
1280 	newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
1281 	newbase -= xdr->buf->page_base;
1282 	if (newbase < xdr->buf->page_len)
1283 		xdr_set_page_base(xdr, newbase, xdr_stream_remaining(xdr));
1284 	else
1285 		xdr_set_tail_base(xdr, 0, xdr_stream_remaining(xdr));
1286 }
1287 
xdr_set_next_buffer(struct xdr_stream * xdr)1288 static bool xdr_set_next_buffer(struct xdr_stream *xdr)
1289 {
1290 	if (xdr->page_ptr != NULL)
1291 		xdr_set_next_page(xdr);
1292 	else if (xdr->iov == xdr->buf->head)
1293 		xdr_set_page(xdr, 0, xdr_stream_remaining(xdr));
1294 	return xdr->p != xdr->end;
1295 }
1296 
1297 /**
1298  * xdr_init_decode - Initialize an xdr_stream for decoding data.
1299  * @xdr: pointer to xdr_stream struct
1300  * @buf: pointer to XDR buffer from which to decode data
1301  * @p: current pointer inside XDR buffer
1302  * @rqst: pointer to controlling rpc_rqst, for debugging
1303  */
xdr_init_decode(struct xdr_stream * xdr,struct xdr_buf * buf,__be32 * p,struct rpc_rqst * rqst)1304 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
1305 		     struct rpc_rqst *rqst)
1306 {
1307 	xdr->buf = buf;
1308 	xdr_reset_scratch_buffer(xdr);
1309 	xdr->nwords = XDR_QUADLEN(buf->len);
1310 	if (xdr_set_iov(xdr, buf->head, 0, buf->len) == 0 &&
1311 	    xdr_set_page_base(xdr, 0, buf->len) == 0)
1312 		xdr_set_iov(xdr, buf->tail, 0, buf->len);
1313 	if (p != NULL && p > xdr->p && xdr->end >= p) {
1314 		xdr->nwords -= p - xdr->p;
1315 		xdr->p = p;
1316 	}
1317 	xdr->rqst = rqst;
1318 }
1319 EXPORT_SYMBOL_GPL(xdr_init_decode);
1320 
1321 /**
1322  * xdr_init_decode_pages - Initialize an xdr_stream for decoding into pages
1323  * @xdr: pointer to xdr_stream struct
1324  * @buf: pointer to XDR buffer from which to decode data
1325  * @pages: list of pages to decode into
1326  * @len: length in bytes of buffer in pages
1327  */
xdr_init_decode_pages(struct xdr_stream * xdr,struct xdr_buf * buf,struct page ** pages,unsigned int len)1328 void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
1329 			   struct page **pages, unsigned int len)
1330 {
1331 	memset(buf, 0, sizeof(*buf));
1332 	buf->pages =  pages;
1333 	buf->page_len =  len;
1334 	buf->buflen =  len;
1335 	buf->len = len;
1336 	xdr_init_decode(xdr, buf, NULL, NULL);
1337 }
1338 EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
1339 
__xdr_inline_decode(struct xdr_stream * xdr,size_t nbytes)1340 static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
1341 {
1342 	unsigned int nwords = XDR_QUADLEN(nbytes);
1343 	__be32 *p = xdr->p;
1344 	__be32 *q = p + nwords;
1345 
1346 	if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
1347 		return NULL;
1348 	xdr->p = q;
1349 	xdr->nwords -= nwords;
1350 	return p;
1351 }
1352 
xdr_copy_to_scratch(struct xdr_stream * xdr,size_t nbytes)1353 static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
1354 {
1355 	__be32 *p;
1356 	char *cpdest = xdr->scratch.iov_base;
1357 	size_t cplen = (char *)xdr->end - (char *)xdr->p;
1358 
1359 	if (nbytes > xdr->scratch.iov_len)
1360 		goto out_overflow;
1361 	p = __xdr_inline_decode(xdr, cplen);
1362 	if (p == NULL)
1363 		return NULL;
1364 	memcpy(cpdest, p, cplen);
1365 	if (!xdr_set_next_buffer(xdr))
1366 		goto out_overflow;
1367 	cpdest += cplen;
1368 	nbytes -= cplen;
1369 	p = __xdr_inline_decode(xdr, nbytes);
1370 	if (p == NULL)
1371 		return NULL;
1372 	memcpy(cpdest, p, nbytes);
1373 	return xdr->scratch.iov_base;
1374 out_overflow:
1375 	trace_rpc_xdr_overflow(xdr, nbytes);
1376 	return NULL;
1377 }
1378 
1379 /**
1380  * xdr_inline_decode - Retrieve XDR data to decode
1381  * @xdr: pointer to xdr_stream struct
1382  * @nbytes: number of bytes of data to decode
1383  *
1384  * Check if the input buffer is long enough to enable us to decode
1385  * 'nbytes' more bytes of data starting at the current position.
1386  * If so return the current pointer, then update the current
1387  * pointer position.
1388  */
xdr_inline_decode(struct xdr_stream * xdr,size_t nbytes)1389 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
1390 {
1391 	__be32 *p;
1392 
1393 	if (unlikely(nbytes == 0))
1394 		return xdr->p;
1395 	if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
1396 		goto out_overflow;
1397 	p = __xdr_inline_decode(xdr, nbytes);
1398 	if (p != NULL)
1399 		return p;
1400 	return xdr_copy_to_scratch(xdr, nbytes);
1401 out_overflow:
1402 	trace_rpc_xdr_overflow(xdr, nbytes);
1403 	return NULL;
1404 }
1405 EXPORT_SYMBOL_GPL(xdr_inline_decode);
1406 
xdr_realign_pages(struct xdr_stream * xdr)1407 static void xdr_realign_pages(struct xdr_stream *xdr)
1408 {
1409 	struct xdr_buf *buf = xdr->buf;
1410 	struct kvec *iov = buf->head;
1411 	unsigned int cur = xdr_stream_pos(xdr);
1412 	unsigned int copied;
1413 
1414 	/* Realign pages to current pointer position */
1415 	if (iov->iov_len > cur) {
1416 		copied = xdr_shrink_bufhead(buf, cur);
1417 		trace_rpc_xdr_alignment(xdr, cur, copied);
1418 		xdr_set_page(xdr, 0, buf->page_len);
1419 	}
1420 }
1421 
xdr_align_pages(struct xdr_stream * xdr,unsigned int len)1422 static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
1423 {
1424 	struct xdr_buf *buf = xdr->buf;
1425 	unsigned int nwords = XDR_QUADLEN(len);
1426 	unsigned int copied;
1427 
1428 	if (xdr->nwords == 0)
1429 		return 0;
1430 
1431 	xdr_realign_pages(xdr);
1432 	if (nwords > xdr->nwords) {
1433 		nwords = xdr->nwords;
1434 		len = nwords << 2;
1435 	}
1436 	if (buf->page_len <= len)
1437 		len = buf->page_len;
1438 	else if (nwords < xdr->nwords) {
1439 		/* Truncate page data and move it into the tail */
1440 		copied = xdr_shrink_pagelen(buf, len);
1441 		trace_rpc_xdr_alignment(xdr, len, copied);
1442 	}
1443 	return len;
1444 }
1445 
1446 /**
1447  * xdr_read_pages - align page-based XDR data to current pointer position
1448  * @xdr: pointer to xdr_stream struct
1449  * @len: number of bytes of page data
1450  *
1451  * Moves data beyond the current pointer position from the XDR head[] buffer
1452  * into the page list. Any data that lies beyond current position + @len
1453  * bytes is moved into the XDR tail[]. The xdr_stream current position is
1454  * then advanced past that data to align to the next XDR object in the tail.
1455  *
1456  * Returns the number of XDR encoded bytes now contained in the pages
1457  */
xdr_read_pages(struct xdr_stream * xdr,unsigned int len)1458 unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
1459 {
1460 	unsigned int nwords = XDR_QUADLEN(len);
1461 	unsigned int base, end, pglen;
1462 
1463 	pglen = xdr_align_pages(xdr, nwords << 2);
1464 	if (pglen == 0)
1465 		return 0;
1466 
1467 	base = (nwords << 2) - pglen;
1468 	end = xdr_stream_remaining(xdr) - pglen;
1469 
1470 	xdr_set_tail_base(xdr, base, end);
1471 	return len <= pglen ? len : pglen;
1472 }
1473 EXPORT_SYMBOL_GPL(xdr_read_pages);
1474 
xdr_align_data(struct xdr_stream * xdr,unsigned int offset,unsigned int length)1475 unsigned int xdr_align_data(struct xdr_stream *xdr, unsigned int offset,
1476 			    unsigned int length)
1477 {
1478 	struct xdr_buf *buf = xdr->buf;
1479 	unsigned int from, bytes, len;
1480 	unsigned int shift;
1481 
1482 	xdr_realign_pages(xdr);
1483 	from = xdr_page_pos(xdr);
1484 
1485 	if (from >= buf->page_len + buf->tail->iov_len)
1486 		return 0;
1487 	if (from + buf->head->iov_len >= buf->len)
1488 		return 0;
1489 
1490 	len = buf->len - buf->head->iov_len;
1491 
1492 	/* We only shift data left! */
1493 	if (WARN_ONCE(from < offset, "SUNRPC: misaligned data src=%u dst=%u\n",
1494 		      from, offset))
1495 		return 0;
1496 	if (WARN_ONCE(offset > buf->page_len,
1497 		      "SUNRPC: buffer overflow. offset=%u, page_len=%u\n",
1498 		      offset, buf->page_len))
1499 		return 0;
1500 
1501 	/* Move page data to the left */
1502 	shift = from - offset;
1503 	xdr_buf_pages_shift_left(buf, from, len, shift);
1504 
1505 	bytes = xdr_stream_remaining(xdr);
1506 	if (length > bytes)
1507 		length = bytes;
1508 	bytes -= length;
1509 
1510 	xdr->buf->len -= shift;
1511 	xdr_set_page(xdr, offset + length, bytes);
1512 	return length;
1513 }
1514 EXPORT_SYMBOL_GPL(xdr_align_data);
1515 
xdr_expand_hole(struct xdr_stream * xdr,unsigned int offset,unsigned int length)1516 unsigned int xdr_expand_hole(struct xdr_stream *xdr, unsigned int offset,
1517 			     unsigned int length)
1518 {
1519 	struct xdr_buf *buf = xdr->buf;
1520 	unsigned int from, to, shift;
1521 
1522 	xdr_realign_pages(xdr);
1523 	from = xdr_page_pos(xdr);
1524 	to = xdr_align_size(offset + length);
1525 
1526 	/* Could the hole be behind us? */
1527 	if (to > from) {
1528 		unsigned int buflen = buf->len - buf->head->iov_len;
1529 		shift = to - from;
1530 		xdr_buf_try_expand(buf, shift);
1531 		xdr_buf_pages_shift_right(buf, from, buflen, shift);
1532 		xdr_set_page(xdr, to, xdr_stream_remaining(xdr));
1533 	} else if (to != from)
1534 		xdr_align_data(xdr, to, 0);
1535 	xdr_buf_pages_zero(buf, offset, length);
1536 
1537 	return length;
1538 }
1539 EXPORT_SYMBOL_GPL(xdr_expand_hole);
1540 
1541 /**
1542  * xdr_enter_page - decode data from the XDR page
1543  * @xdr: pointer to xdr_stream struct
1544  * @len: number of bytes of page data
1545  *
1546  * Moves data beyond the current pointer position from the XDR head[] buffer
1547  * into the page list. Any data that lies beyond current position + "len"
1548  * bytes is moved into the XDR tail[]. The current pointer is then
1549  * repositioned at the beginning of the first XDR page.
1550  */
xdr_enter_page(struct xdr_stream * xdr,unsigned int len)1551 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
1552 {
1553 	len = xdr_align_pages(xdr, len);
1554 	/*
1555 	 * Position current pointer at beginning of tail, and
1556 	 * set remaining message length.
1557 	 */
1558 	if (len != 0)
1559 		xdr_set_page_base(xdr, 0, len);
1560 }
1561 EXPORT_SYMBOL_GPL(xdr_enter_page);
1562 
1563 static const struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
1564 
xdr_buf_from_iov(const struct kvec * iov,struct xdr_buf * buf)1565 void xdr_buf_from_iov(const struct kvec *iov, struct xdr_buf *buf)
1566 {
1567 	buf->head[0] = *iov;
1568 	buf->tail[0] = empty_iov;
1569 	buf->page_len = 0;
1570 	buf->buflen = buf->len = iov->iov_len;
1571 }
1572 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
1573 
1574 /**
1575  * xdr_buf_subsegment - set subbuf to a portion of buf
1576  * @buf: an xdr buffer
1577  * @subbuf: the result buffer
1578  * @base: beginning of range in bytes
1579  * @len: length of range in bytes
1580  *
1581  * sets @subbuf to an xdr buffer representing the portion of @buf of
1582  * length @len starting at offset @base.
1583  *
1584  * @buf and @subbuf may be pointers to the same struct xdr_buf.
1585  *
1586  * Returns -1 if base of length are out of bounds.
1587  */
xdr_buf_subsegment(const struct xdr_buf * buf,struct xdr_buf * subbuf,unsigned int base,unsigned int len)1588 int xdr_buf_subsegment(const struct xdr_buf *buf, struct xdr_buf *subbuf,
1589 		       unsigned int base, unsigned int len)
1590 {
1591 	subbuf->buflen = subbuf->len = len;
1592 	if (base < buf->head[0].iov_len) {
1593 		subbuf->head[0].iov_base = buf->head[0].iov_base + base;
1594 		subbuf->head[0].iov_len = min_t(unsigned int, len,
1595 						buf->head[0].iov_len - base);
1596 		len -= subbuf->head[0].iov_len;
1597 		base = 0;
1598 	} else {
1599 		base -= buf->head[0].iov_len;
1600 		subbuf->head[0].iov_base = buf->head[0].iov_base;
1601 		subbuf->head[0].iov_len = 0;
1602 	}
1603 
1604 	if (base < buf->page_len) {
1605 		subbuf->page_len = min(buf->page_len - base, len);
1606 		base += buf->page_base;
1607 		subbuf->page_base = base & ~PAGE_MASK;
1608 		subbuf->pages = &buf->pages[base >> PAGE_SHIFT];
1609 		len -= subbuf->page_len;
1610 		base = 0;
1611 	} else {
1612 		base -= buf->page_len;
1613 		subbuf->pages = buf->pages;
1614 		subbuf->page_base = 0;
1615 		subbuf->page_len = 0;
1616 	}
1617 
1618 	if (base < buf->tail[0].iov_len) {
1619 		subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
1620 		subbuf->tail[0].iov_len = min_t(unsigned int, len,
1621 						buf->tail[0].iov_len - base);
1622 		len -= subbuf->tail[0].iov_len;
1623 		base = 0;
1624 	} else {
1625 		base -= buf->tail[0].iov_len;
1626 		subbuf->tail[0].iov_base = buf->tail[0].iov_base;
1627 		subbuf->tail[0].iov_len = 0;
1628 	}
1629 
1630 	if (base || len)
1631 		return -1;
1632 	return 0;
1633 }
1634 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
1635 
1636 /**
1637  * xdr_stream_subsegment - set @subbuf to a portion of @xdr
1638  * @xdr: an xdr_stream set up for decoding
1639  * @subbuf: the result buffer
1640  * @nbytes: length of @xdr to extract, in bytes
1641  *
1642  * Sets up @subbuf to represent a portion of @xdr. The portion
1643  * starts at the current offset in @xdr, and extends for a length
1644  * of @nbytes. If this is successful, @xdr is advanced to the next
1645  * XDR data item following that portion.
1646  *
1647  * Return values:
1648  *   %true: @subbuf has been initialized, and @xdr has been advanced.
1649  *   %false: a bounds error has occurred
1650  */
xdr_stream_subsegment(struct xdr_stream * xdr,struct xdr_buf * subbuf,unsigned int nbytes)1651 bool xdr_stream_subsegment(struct xdr_stream *xdr, struct xdr_buf *subbuf,
1652 			   unsigned int nbytes)
1653 {
1654 	unsigned int start = xdr_stream_pos(xdr);
1655 	unsigned int remaining, len;
1656 
1657 	/* Extract @subbuf and bounds-check the fn arguments */
1658 	if (xdr_buf_subsegment(xdr->buf, subbuf, start, nbytes))
1659 		return false;
1660 
1661 	/* Advance @xdr by @nbytes */
1662 	for (remaining = nbytes; remaining;) {
1663 		if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
1664 			return false;
1665 
1666 		len = (char *)xdr->end - (char *)xdr->p;
1667 		if (remaining <= len) {
1668 			xdr->p = (__be32 *)((char *)xdr->p +
1669 					(remaining + xdr_pad_size(nbytes)));
1670 			break;
1671 		}
1672 
1673 		xdr->p = (__be32 *)((char *)xdr->p + len);
1674 		xdr->end = xdr->p;
1675 		remaining -= len;
1676 	}
1677 
1678 	xdr_stream_set_pos(xdr, start + nbytes);
1679 	return true;
1680 }
1681 EXPORT_SYMBOL_GPL(xdr_stream_subsegment);
1682 
1683 /**
1684  * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
1685  * @buf: buf to be trimmed
1686  * @len: number of bytes to reduce "buf" by
1687  *
1688  * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
1689  * that it's possible that we'll trim less than that amount if the xdr_buf is
1690  * too small, or if (for instance) it's all in the head and the parser has
1691  * already read too far into it.
1692  */
xdr_buf_trim(struct xdr_buf * buf,unsigned int len)1693 void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
1694 {
1695 	size_t cur;
1696 	unsigned int trim = len;
1697 
1698 	if (buf->tail[0].iov_len) {
1699 		cur = min_t(size_t, buf->tail[0].iov_len, trim);
1700 		buf->tail[0].iov_len -= cur;
1701 		trim -= cur;
1702 		if (!trim)
1703 			goto fix_len;
1704 	}
1705 
1706 	if (buf->page_len) {
1707 		cur = min_t(unsigned int, buf->page_len, trim);
1708 		buf->page_len -= cur;
1709 		trim -= cur;
1710 		if (!trim)
1711 			goto fix_len;
1712 	}
1713 
1714 	if (buf->head[0].iov_len) {
1715 		cur = min_t(size_t, buf->head[0].iov_len, trim);
1716 		buf->head[0].iov_len -= cur;
1717 		trim -= cur;
1718 	}
1719 fix_len:
1720 	buf->len -= (len - trim);
1721 }
1722 EXPORT_SYMBOL_GPL(xdr_buf_trim);
1723 
__read_bytes_from_xdr_buf(const struct xdr_buf * subbuf,void * obj,unsigned int len)1724 static void __read_bytes_from_xdr_buf(const struct xdr_buf *subbuf,
1725 				      void *obj, unsigned int len)
1726 {
1727 	unsigned int this_len;
1728 
1729 	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1730 	memcpy(obj, subbuf->head[0].iov_base, this_len);
1731 	len -= this_len;
1732 	obj += this_len;
1733 	this_len = min_t(unsigned int, len, subbuf->page_len);
1734 	_copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
1735 	len -= this_len;
1736 	obj += this_len;
1737 	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1738 	memcpy(obj, subbuf->tail[0].iov_base, this_len);
1739 }
1740 
1741 /* obj is assumed to point to allocated memory of size at least len: */
read_bytes_from_xdr_buf(const struct xdr_buf * buf,unsigned int base,void * obj,unsigned int len)1742 int read_bytes_from_xdr_buf(const struct xdr_buf *buf, unsigned int base,
1743 			    void *obj, unsigned int len)
1744 {
1745 	struct xdr_buf subbuf;
1746 	int status;
1747 
1748 	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1749 	if (status != 0)
1750 		return status;
1751 	__read_bytes_from_xdr_buf(&subbuf, obj, len);
1752 	return 0;
1753 }
1754 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
1755 
__write_bytes_to_xdr_buf(const struct xdr_buf * subbuf,void * obj,unsigned int len)1756 static void __write_bytes_to_xdr_buf(const struct xdr_buf *subbuf,
1757 				     void *obj, unsigned int len)
1758 {
1759 	unsigned int this_len;
1760 
1761 	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1762 	memcpy(subbuf->head[0].iov_base, obj, this_len);
1763 	len -= this_len;
1764 	obj += this_len;
1765 	this_len = min_t(unsigned int, len, subbuf->page_len);
1766 	_copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
1767 	len -= this_len;
1768 	obj += this_len;
1769 	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1770 	memcpy(subbuf->tail[0].iov_base, obj, this_len);
1771 }
1772 
1773 /* obj is assumed to point to allocated memory of size at least len: */
write_bytes_to_xdr_buf(const struct xdr_buf * buf,unsigned int base,void * obj,unsigned int len)1774 int write_bytes_to_xdr_buf(const struct xdr_buf *buf, unsigned int base,
1775 			   void *obj, unsigned int len)
1776 {
1777 	struct xdr_buf subbuf;
1778 	int status;
1779 
1780 	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1781 	if (status != 0)
1782 		return status;
1783 	__write_bytes_to_xdr_buf(&subbuf, obj, len);
1784 	return 0;
1785 }
1786 EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
1787 
xdr_decode_word(const struct xdr_buf * buf,unsigned int base,u32 * obj)1788 int xdr_decode_word(const struct xdr_buf *buf, unsigned int base, u32 *obj)
1789 {
1790 	__be32	raw;
1791 	int	status;
1792 
1793 	status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1794 	if (status)
1795 		return status;
1796 	*obj = be32_to_cpu(raw);
1797 	return 0;
1798 }
1799 EXPORT_SYMBOL_GPL(xdr_decode_word);
1800 
xdr_encode_word(const struct xdr_buf * buf,unsigned int base,u32 obj)1801 int xdr_encode_word(const struct xdr_buf *buf, unsigned int base, u32 obj)
1802 {
1803 	__be32	raw = cpu_to_be32(obj);
1804 
1805 	return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1806 }
1807 EXPORT_SYMBOL_GPL(xdr_encode_word);
1808 
1809 /* Returns 0 on success, or else a negative error code. */
xdr_xcode_array2(const struct xdr_buf * buf,unsigned int base,struct xdr_array2_desc * desc,int encode)1810 static int xdr_xcode_array2(const struct xdr_buf *buf, unsigned int base,
1811 			    struct xdr_array2_desc *desc, int encode)
1812 {
1813 	char *elem = NULL, *c;
1814 	unsigned int copied = 0, todo, avail_here;
1815 	struct page **ppages = NULL;
1816 	int err;
1817 
1818 	if (encode) {
1819 		if (xdr_encode_word(buf, base, desc->array_len) != 0)
1820 			return -EINVAL;
1821 	} else {
1822 		if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1823 		    desc->array_len > desc->array_maxlen ||
1824 		    (unsigned long) base + 4 + desc->array_len *
1825 				    desc->elem_size > buf->len)
1826 			return -EINVAL;
1827 	}
1828 	base += 4;
1829 
1830 	if (!desc->xcode)
1831 		return 0;
1832 
1833 	todo = desc->array_len * desc->elem_size;
1834 
1835 	/* process head */
1836 	if (todo && base < buf->head->iov_len) {
1837 		c = buf->head->iov_base + base;
1838 		avail_here = min_t(unsigned int, todo,
1839 				   buf->head->iov_len - base);
1840 		todo -= avail_here;
1841 
1842 		while (avail_here >= desc->elem_size) {
1843 			err = desc->xcode(desc, c);
1844 			if (err)
1845 				goto out;
1846 			c += desc->elem_size;
1847 			avail_here -= desc->elem_size;
1848 		}
1849 		if (avail_here) {
1850 			if (!elem) {
1851 				elem = kmalloc(desc->elem_size, GFP_KERNEL);
1852 				err = -ENOMEM;
1853 				if (!elem)
1854 					goto out;
1855 			}
1856 			if (encode) {
1857 				err = desc->xcode(desc, elem);
1858 				if (err)
1859 					goto out;
1860 				memcpy(c, elem, avail_here);
1861 			} else
1862 				memcpy(elem, c, avail_here);
1863 			copied = avail_here;
1864 		}
1865 		base = buf->head->iov_len;  /* align to start of pages */
1866 	}
1867 
1868 	/* process pages array */
1869 	base -= buf->head->iov_len;
1870 	if (todo && base < buf->page_len) {
1871 		unsigned int avail_page;
1872 
1873 		avail_here = min(todo, buf->page_len - base);
1874 		todo -= avail_here;
1875 
1876 		base += buf->page_base;
1877 		ppages = buf->pages + (base >> PAGE_SHIFT);
1878 		base &= ~PAGE_MASK;
1879 		avail_page = min_t(unsigned int, PAGE_SIZE - base,
1880 					avail_here);
1881 		c = kmap(*ppages) + base;
1882 
1883 		while (avail_here) {
1884 			avail_here -= avail_page;
1885 			if (copied || avail_page < desc->elem_size) {
1886 				unsigned int l = min(avail_page,
1887 					desc->elem_size - copied);
1888 				if (!elem) {
1889 					elem = kmalloc(desc->elem_size,
1890 						       GFP_KERNEL);
1891 					err = -ENOMEM;
1892 					if (!elem)
1893 						goto out;
1894 				}
1895 				if (encode) {
1896 					if (!copied) {
1897 						err = desc->xcode(desc, elem);
1898 						if (err)
1899 							goto out;
1900 					}
1901 					memcpy(c, elem + copied, l);
1902 					copied += l;
1903 					if (copied == desc->elem_size)
1904 						copied = 0;
1905 				} else {
1906 					memcpy(elem + copied, c, l);
1907 					copied += l;
1908 					if (copied == desc->elem_size) {
1909 						err = desc->xcode(desc, elem);
1910 						if (err)
1911 							goto out;
1912 						copied = 0;
1913 					}
1914 				}
1915 				avail_page -= l;
1916 				c += l;
1917 			}
1918 			while (avail_page >= desc->elem_size) {
1919 				err = desc->xcode(desc, c);
1920 				if (err)
1921 					goto out;
1922 				c += desc->elem_size;
1923 				avail_page -= desc->elem_size;
1924 			}
1925 			if (avail_page) {
1926 				unsigned int l = min(avail_page,
1927 					    desc->elem_size - copied);
1928 				if (!elem) {
1929 					elem = kmalloc(desc->elem_size,
1930 						       GFP_KERNEL);
1931 					err = -ENOMEM;
1932 					if (!elem)
1933 						goto out;
1934 				}
1935 				if (encode) {
1936 					if (!copied) {
1937 						err = desc->xcode(desc, elem);
1938 						if (err)
1939 							goto out;
1940 					}
1941 					memcpy(c, elem + copied, l);
1942 					copied += l;
1943 					if (copied == desc->elem_size)
1944 						copied = 0;
1945 				} else {
1946 					memcpy(elem + copied, c, l);
1947 					copied += l;
1948 					if (copied == desc->elem_size) {
1949 						err = desc->xcode(desc, elem);
1950 						if (err)
1951 							goto out;
1952 						copied = 0;
1953 					}
1954 				}
1955 			}
1956 			if (avail_here) {
1957 				kunmap(*ppages);
1958 				ppages++;
1959 				c = kmap(*ppages);
1960 			}
1961 
1962 			avail_page = min(avail_here,
1963 				 (unsigned int) PAGE_SIZE);
1964 		}
1965 		base = buf->page_len;  /* align to start of tail */
1966 	}
1967 
1968 	/* process tail */
1969 	base -= buf->page_len;
1970 	if (todo) {
1971 		c = buf->tail->iov_base + base;
1972 		if (copied) {
1973 			unsigned int l = desc->elem_size - copied;
1974 
1975 			if (encode)
1976 				memcpy(c, elem + copied, l);
1977 			else {
1978 				memcpy(elem + copied, c, l);
1979 				err = desc->xcode(desc, elem);
1980 				if (err)
1981 					goto out;
1982 			}
1983 			todo -= l;
1984 			c += l;
1985 		}
1986 		while (todo) {
1987 			err = desc->xcode(desc, c);
1988 			if (err)
1989 				goto out;
1990 			c += desc->elem_size;
1991 			todo -= desc->elem_size;
1992 		}
1993 	}
1994 	err = 0;
1995 
1996 out:
1997 	kfree(elem);
1998 	if (ppages)
1999 		kunmap(*ppages);
2000 	return err;
2001 }
2002 
xdr_decode_array2(const struct xdr_buf * buf,unsigned int base,struct xdr_array2_desc * desc)2003 int xdr_decode_array2(const struct xdr_buf *buf, unsigned int base,
2004 		      struct xdr_array2_desc *desc)
2005 {
2006 	if (base >= buf->len)
2007 		return -EINVAL;
2008 
2009 	return xdr_xcode_array2(buf, base, desc, 0);
2010 }
2011 EXPORT_SYMBOL_GPL(xdr_decode_array2);
2012 
xdr_encode_array2(const struct xdr_buf * buf,unsigned int base,struct xdr_array2_desc * desc)2013 int xdr_encode_array2(const struct xdr_buf *buf, unsigned int base,
2014 		      struct xdr_array2_desc *desc)
2015 {
2016 	if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
2017 	    buf->head->iov_len + buf->page_len + buf->tail->iov_len)
2018 		return -EINVAL;
2019 
2020 	return xdr_xcode_array2(buf, base, desc, 1);
2021 }
2022 EXPORT_SYMBOL_GPL(xdr_encode_array2);
2023 
xdr_process_buf(const struct xdr_buf * buf,unsigned int offset,unsigned int len,int (* actor)(struct scatterlist *,void *),void * data)2024 int xdr_process_buf(const struct xdr_buf *buf, unsigned int offset,
2025 		    unsigned int len,
2026 		    int (*actor)(struct scatterlist *, void *), void *data)
2027 {
2028 	int i, ret = 0;
2029 	unsigned int page_len, thislen, page_offset;
2030 	struct scatterlist      sg[1];
2031 
2032 	sg_init_table(sg, 1);
2033 
2034 	if (offset >= buf->head[0].iov_len) {
2035 		offset -= buf->head[0].iov_len;
2036 	} else {
2037 		thislen = buf->head[0].iov_len - offset;
2038 		if (thislen > len)
2039 			thislen = len;
2040 		sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
2041 		ret = actor(sg, data);
2042 		if (ret)
2043 			goto out;
2044 		offset = 0;
2045 		len -= thislen;
2046 	}
2047 	if (len == 0)
2048 		goto out;
2049 
2050 	if (offset >= buf->page_len) {
2051 		offset -= buf->page_len;
2052 	} else {
2053 		page_len = buf->page_len - offset;
2054 		if (page_len > len)
2055 			page_len = len;
2056 		len -= page_len;
2057 		page_offset = (offset + buf->page_base) & (PAGE_SIZE - 1);
2058 		i = (offset + buf->page_base) >> PAGE_SHIFT;
2059 		thislen = PAGE_SIZE - page_offset;
2060 		do {
2061 			if (thislen > page_len)
2062 				thislen = page_len;
2063 			sg_set_page(sg, buf->pages[i], thislen, page_offset);
2064 			ret = actor(sg, data);
2065 			if (ret)
2066 				goto out;
2067 			page_len -= thislen;
2068 			i++;
2069 			page_offset = 0;
2070 			thislen = PAGE_SIZE;
2071 		} while (page_len != 0);
2072 		offset = 0;
2073 	}
2074 	if (len == 0)
2075 		goto out;
2076 	if (offset < buf->tail[0].iov_len) {
2077 		thislen = buf->tail[0].iov_len - offset;
2078 		if (thislen > len)
2079 			thislen = len;
2080 		sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
2081 		ret = actor(sg, data);
2082 		len -= thislen;
2083 	}
2084 	if (len != 0)
2085 		ret = -EINVAL;
2086 out:
2087 	return ret;
2088 }
2089 EXPORT_SYMBOL_GPL(xdr_process_buf);
2090 
2091 /**
2092  * xdr_stream_decode_opaque - Decode variable length opaque
2093  * @xdr: pointer to xdr_stream
2094  * @ptr: location to store opaque data
2095  * @size: size of storage buffer @ptr
2096  *
2097  * Return values:
2098  *   On success, returns size of object stored in *@ptr
2099  *   %-EBADMSG on XDR buffer overflow
2100  *   %-EMSGSIZE on overflow of storage buffer @ptr
2101  */
xdr_stream_decode_opaque(struct xdr_stream * xdr,void * ptr,size_t size)2102 ssize_t xdr_stream_decode_opaque(struct xdr_stream *xdr, void *ptr, size_t size)
2103 {
2104 	ssize_t ret;
2105 	void *p;
2106 
2107 	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
2108 	if (ret <= 0)
2109 		return ret;
2110 	memcpy(ptr, p, ret);
2111 	return ret;
2112 }
2113 EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque);
2114 
2115 /**
2116  * xdr_stream_decode_opaque_dup - Decode and duplicate variable length opaque
2117  * @xdr: pointer to xdr_stream
2118  * @ptr: location to store pointer to opaque data
2119  * @maxlen: maximum acceptable object size
2120  * @gfp_flags: GFP mask to use
2121  *
2122  * Return values:
2123  *   On success, returns size of object stored in *@ptr
2124  *   %-EBADMSG on XDR buffer overflow
2125  *   %-EMSGSIZE if the size of the object would exceed @maxlen
2126  *   %-ENOMEM on memory allocation failure
2127  */
xdr_stream_decode_opaque_dup(struct xdr_stream * xdr,void ** ptr,size_t maxlen,gfp_t gfp_flags)2128 ssize_t xdr_stream_decode_opaque_dup(struct xdr_stream *xdr, void **ptr,
2129 		size_t maxlen, gfp_t gfp_flags)
2130 {
2131 	ssize_t ret;
2132 	void *p;
2133 
2134 	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
2135 	if (ret > 0) {
2136 		*ptr = kmemdup(p, ret, gfp_flags);
2137 		if (*ptr != NULL)
2138 			return ret;
2139 		ret = -ENOMEM;
2140 	}
2141 	*ptr = NULL;
2142 	return ret;
2143 }
2144 EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque_dup);
2145 
2146 /**
2147  * xdr_stream_decode_string - Decode variable length string
2148  * @xdr: pointer to xdr_stream
2149  * @str: location to store string
2150  * @size: size of storage buffer @str
2151  *
2152  * Return values:
2153  *   On success, returns length of NUL-terminated string stored in *@str
2154  *   %-EBADMSG on XDR buffer overflow
2155  *   %-EMSGSIZE on overflow of storage buffer @str
2156  */
xdr_stream_decode_string(struct xdr_stream * xdr,char * str,size_t size)2157 ssize_t xdr_stream_decode_string(struct xdr_stream *xdr, char *str, size_t size)
2158 {
2159 	ssize_t ret;
2160 	void *p;
2161 
2162 	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
2163 	if (ret > 0) {
2164 		memcpy(str, p, ret);
2165 		str[ret] = '\0';
2166 		return strlen(str);
2167 	}
2168 	*str = '\0';
2169 	return ret;
2170 }
2171 EXPORT_SYMBOL_GPL(xdr_stream_decode_string);
2172 
2173 /**
2174  * xdr_stream_decode_string_dup - Decode and duplicate variable length string
2175  * @xdr: pointer to xdr_stream
2176  * @str: location to store pointer to string
2177  * @maxlen: maximum acceptable string length
2178  * @gfp_flags: GFP mask to use
2179  *
2180  * Return values:
2181  *   On success, returns length of NUL-terminated string stored in *@ptr
2182  *   %-EBADMSG on XDR buffer overflow
2183  *   %-EMSGSIZE if the size of the string would exceed @maxlen
2184  *   %-ENOMEM on memory allocation failure
2185  */
xdr_stream_decode_string_dup(struct xdr_stream * xdr,char ** str,size_t maxlen,gfp_t gfp_flags)2186 ssize_t xdr_stream_decode_string_dup(struct xdr_stream *xdr, char **str,
2187 		size_t maxlen, gfp_t gfp_flags)
2188 {
2189 	void *p;
2190 	ssize_t ret;
2191 
2192 	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
2193 	if (ret > 0) {
2194 		char *s = kmemdup_nul(p, ret, gfp_flags);
2195 		if (s != NULL) {
2196 			*str = s;
2197 			return strlen(s);
2198 		}
2199 		ret = -ENOMEM;
2200 	}
2201 	*str = NULL;
2202 	return ret;
2203 }
2204 EXPORT_SYMBOL_GPL(xdr_stream_decode_string_dup);
2205