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 
xdr_buf_head_shift_left(const struct xdr_buf * buf,unsigned int base,unsigned int len,unsigned int shift)778 static void xdr_buf_head_shift_left(const struct xdr_buf *buf,
779 				    unsigned int base, unsigned int len,
780 				    unsigned int shift)
781 {
782 	const struct kvec *head = buf->head;
783 	unsigned int bytes;
784 
785 	if (!shift || !len)
786 		return;
787 
788 	if (shift > base) {
789 		bytes = (shift - base);
790 		if (bytes >= len)
791 			return;
792 		base += bytes;
793 		len -= bytes;
794 	}
795 
796 	if (base < head->iov_len) {
797 		bytes = min_t(unsigned int, len, head->iov_len - base);
798 		memmove(head->iov_base + (base - shift),
799 			head->iov_base + base, bytes);
800 		base += bytes;
801 		len -= bytes;
802 	}
803 	xdr_buf_pages_shift_left(buf, base - head->iov_len, len, shift);
804 }
805 
806 /**
807  * xdr_shrink_bufhead
808  * @buf: xdr_buf
809  * @len: new length of buf->head[0]
810  *
811  * Shrinks XDR buffer's header kvec buf->head[0], setting it to
812  * 'len' bytes. The extra data is not lost, but is instead
813  * moved into the inlined pages and/or the tail.
814  */
xdr_shrink_bufhead(struct xdr_buf * buf,unsigned int len)815 static unsigned int xdr_shrink_bufhead(struct xdr_buf *buf, unsigned int len)
816 {
817 	struct kvec *head = buf->head;
818 	unsigned int shift, buflen = max(buf->len, len);
819 
820 	WARN_ON_ONCE(len > head->iov_len);
821 	if (head->iov_len > buflen) {
822 		buf->buflen -= head->iov_len - buflen;
823 		head->iov_len = buflen;
824 	}
825 	if (len >= head->iov_len)
826 		return 0;
827 	shift = head->iov_len - len;
828 	xdr_buf_try_expand(buf, shift);
829 	xdr_buf_head_shift_right(buf, len, buflen - len, shift);
830 	head->iov_len = len;
831 	buf->buflen -= shift;
832 	buf->len -= shift;
833 	return shift;
834 }
835 
836 /**
837  * xdr_shrink_pagelen - shrinks buf->pages to @len bytes
838  * @buf: xdr_buf
839  * @len: new page buffer length
840  *
841  * The extra data is not lost, but is instead moved into buf->tail.
842  * Returns the actual number of bytes moved.
843  */
xdr_shrink_pagelen(struct xdr_buf * buf,unsigned int len)844 static unsigned int xdr_shrink_pagelen(struct xdr_buf *buf, unsigned int len)
845 {
846 	unsigned int shift, buflen = buf->len - buf->head->iov_len;
847 
848 	WARN_ON_ONCE(len > buf->page_len);
849 	if (buf->head->iov_len >= buf->len || len > buflen)
850 		buflen = len;
851 	if (buf->page_len > buflen) {
852 		buf->buflen -= buf->page_len - buflen;
853 		buf->page_len = buflen;
854 	}
855 	if (len >= buf->page_len)
856 		return 0;
857 	shift = buf->page_len - len;
858 	xdr_buf_try_expand(buf, shift);
859 	xdr_buf_pages_shift_right(buf, len, buflen - len, shift);
860 	buf->page_len = len;
861 	buf->len -= shift;
862 	buf->buflen -= shift;
863 	return shift;
864 }
865 
866 void
xdr_shift_buf(struct xdr_buf * buf,size_t len)867 xdr_shift_buf(struct xdr_buf *buf, size_t len)
868 {
869 	xdr_shrink_bufhead(buf, buf->head->iov_len - len);
870 }
871 EXPORT_SYMBOL_GPL(xdr_shift_buf);
872 
873 /**
874  * xdr_stream_pos - Return the current offset from the start of the xdr_stream
875  * @xdr: pointer to struct xdr_stream
876  */
xdr_stream_pos(const struct xdr_stream * xdr)877 unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
878 {
879 	return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
880 }
881 EXPORT_SYMBOL_GPL(xdr_stream_pos);
882 
xdr_stream_set_pos(struct xdr_stream * xdr,unsigned int pos)883 static void xdr_stream_set_pos(struct xdr_stream *xdr, unsigned int pos)
884 {
885 	unsigned int blen = xdr->buf->len;
886 
887 	xdr->nwords = blen > pos ? XDR_QUADLEN(blen) - XDR_QUADLEN(pos) : 0;
888 }
889 
xdr_stream_page_set_pos(struct xdr_stream * xdr,unsigned int pos)890 static void xdr_stream_page_set_pos(struct xdr_stream *xdr, unsigned int pos)
891 {
892 	xdr_stream_set_pos(xdr, pos + xdr->buf->head[0].iov_len);
893 }
894 
895 /**
896  * xdr_page_pos - Return the current offset from the start of the xdr pages
897  * @xdr: pointer to struct xdr_stream
898  */
xdr_page_pos(const struct xdr_stream * xdr)899 unsigned int xdr_page_pos(const struct xdr_stream *xdr)
900 {
901 	unsigned int pos = xdr_stream_pos(xdr);
902 
903 	WARN_ON(pos < xdr->buf->head[0].iov_len);
904 	return pos - xdr->buf->head[0].iov_len;
905 }
906 EXPORT_SYMBOL_GPL(xdr_page_pos);
907 
908 /**
909  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
910  * @xdr: pointer to xdr_stream struct
911  * @buf: pointer to XDR buffer in which to encode data
912  * @p: current pointer inside XDR buffer
913  * @rqst: pointer to controlling rpc_rqst, for debugging
914  *
915  * Note: at the moment the RPC client only passes the length of our
916  *	 scratch buffer in the xdr_buf's header kvec. Previously this
917  *	 meant we needed to call xdr_adjust_iovec() after encoding the
918  *	 data. With the new scheme, the xdr_stream manages the details
919  *	 of the buffer length, and takes care of adjusting the kvec
920  *	 length for us.
921  */
xdr_init_encode(struct xdr_stream * xdr,struct xdr_buf * buf,__be32 * p,struct rpc_rqst * rqst)922 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
923 		     struct rpc_rqst *rqst)
924 {
925 	struct kvec *iov = buf->head;
926 	int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
927 
928 	xdr_reset_scratch_buffer(xdr);
929 	BUG_ON(scratch_len < 0);
930 	xdr->buf = buf;
931 	xdr->iov = iov;
932 	xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
933 	xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
934 	BUG_ON(iov->iov_len > scratch_len);
935 
936 	if (p != xdr->p && p != NULL) {
937 		size_t len;
938 
939 		BUG_ON(p < xdr->p || p > xdr->end);
940 		len = (char *)p - (char *)xdr->p;
941 		xdr->p = p;
942 		buf->len += len;
943 		iov->iov_len += len;
944 	}
945 	xdr->rqst = rqst;
946 }
947 EXPORT_SYMBOL_GPL(xdr_init_encode);
948 
949 /**
950  * xdr_init_encode_pages - Initialize an xdr_stream for encoding into pages
951  * @xdr: pointer to xdr_stream struct
952  * @buf: pointer to XDR buffer into which to encode data
953  * @pages: list of pages to decode into
954  * @rqst: pointer to controlling rpc_rqst, for debugging
955  *
956  */
xdr_init_encode_pages(struct xdr_stream * xdr,struct xdr_buf * buf,struct page ** pages,struct rpc_rqst * rqst)957 void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
958 			   struct page **pages, struct rpc_rqst *rqst)
959 {
960 	xdr_reset_scratch_buffer(xdr);
961 
962 	xdr->buf = buf;
963 	xdr->page_ptr = pages;
964 	xdr->iov = NULL;
965 	xdr->p = page_address(*pages);
966 	xdr->end = (void *)xdr->p + min_t(u32, buf->buflen, PAGE_SIZE);
967 	xdr->rqst = rqst;
968 }
969 EXPORT_SYMBOL_GPL(xdr_init_encode_pages);
970 
971 /**
972  * __xdr_commit_encode - Ensure all data is written to buffer
973  * @xdr: pointer to xdr_stream
974  *
975  * We handle encoding across page boundaries by giving the caller a
976  * temporary location to write to, then later copying the data into
977  * place; xdr_commit_encode does that copying.
978  *
979  * Normally the caller doesn't need to call this directly, as the
980  * following xdr_reserve_space will do it.  But an explicit call may be
981  * required at the end of encoding, or any other time when the xdr_buf
982  * data might be read.
983  */
__xdr_commit_encode(struct xdr_stream * xdr)984 void __xdr_commit_encode(struct xdr_stream *xdr)
985 {
986 	size_t shift = xdr->scratch.iov_len;
987 	void *page;
988 
989 	page = page_address(*xdr->page_ptr);
990 	memcpy(xdr->scratch.iov_base, page, shift);
991 	memmove(page, page + shift, (void *)xdr->p - page);
992 	xdr_reset_scratch_buffer(xdr);
993 }
994 EXPORT_SYMBOL_GPL(__xdr_commit_encode);
995 
996 /*
997  * The buffer space to be reserved crosses the boundary between
998  * xdr->buf->head and xdr->buf->pages, or between two pages
999  * in xdr->buf->pages.
1000  */
xdr_get_next_encode_buffer(struct xdr_stream * xdr,size_t nbytes)1001 static noinline __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
1002 						   size_t nbytes)
1003 {
1004 	int space_left;
1005 	int frag1bytes, frag2bytes;
1006 	void *p;
1007 
1008 	if (nbytes > PAGE_SIZE)
1009 		goto out_overflow; /* Bigger buffers require special handling */
1010 	if (xdr->buf->len + nbytes > xdr->buf->buflen)
1011 		goto out_overflow; /* Sorry, we're totally out of space */
1012 	frag1bytes = (xdr->end - xdr->p) << 2;
1013 	frag2bytes = nbytes - frag1bytes;
1014 	if (xdr->iov)
1015 		xdr->iov->iov_len += frag1bytes;
1016 	else
1017 		xdr->buf->page_len += frag1bytes;
1018 	xdr->page_ptr++;
1019 	xdr->iov = NULL;
1020 
1021 	/*
1022 	 * If the last encode didn't end exactly on a page boundary, the
1023 	 * next one will straddle boundaries.  Encode into the next
1024 	 * page, then copy it back later in xdr_commit_encode.  We use
1025 	 * the "scratch" iov to track any temporarily unused fragment of
1026 	 * space at the end of the previous buffer:
1027 	 */
1028 	xdr_set_scratch_buffer(xdr, xdr->p, frag1bytes);
1029 
1030 	/*
1031 	 * xdr->p is where the next encode will start after
1032 	 * xdr_commit_encode() has shifted this one back:
1033 	 */
1034 	p = page_address(*xdr->page_ptr);
1035 	xdr->p = p + frag2bytes;
1036 	space_left = xdr->buf->buflen - xdr->buf->len;
1037 	if (space_left - frag1bytes >= PAGE_SIZE)
1038 		xdr->end = p + PAGE_SIZE;
1039 	else
1040 		xdr->end = p + space_left - frag1bytes;
1041 
1042 	xdr->buf->page_len += frag2bytes;
1043 	xdr->buf->len += nbytes;
1044 	return p;
1045 out_overflow:
1046 	trace_rpc_xdr_overflow(xdr, nbytes);
1047 	return NULL;
1048 }
1049 
1050 /**
1051  * xdr_reserve_space - Reserve buffer space for sending
1052  * @xdr: pointer to xdr_stream
1053  * @nbytes: number of bytes to reserve
1054  *
1055  * Checks that we have enough buffer space to encode 'nbytes' more
1056  * bytes of data. If so, update the total xdr_buf length, and
1057  * adjust the length of the current kvec.
1058  */
xdr_reserve_space(struct xdr_stream * xdr,size_t nbytes)1059 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
1060 {
1061 	__be32 *p = xdr->p;
1062 	__be32 *q;
1063 
1064 	xdr_commit_encode(xdr);
1065 	/* align nbytes on the next 32-bit boundary */
1066 	nbytes += 3;
1067 	nbytes &= ~3;
1068 	q = p + (nbytes >> 2);
1069 	if (unlikely(q > xdr->end || q < p))
1070 		return xdr_get_next_encode_buffer(xdr, nbytes);
1071 	xdr->p = q;
1072 	if (xdr->iov)
1073 		xdr->iov->iov_len += nbytes;
1074 	else
1075 		xdr->buf->page_len += nbytes;
1076 	xdr->buf->len += nbytes;
1077 	return p;
1078 }
1079 EXPORT_SYMBOL_GPL(xdr_reserve_space);
1080 
1081 
1082 /**
1083  * xdr_reserve_space_vec - Reserves a large amount of buffer space for sending
1084  * @xdr: pointer to xdr_stream
1085  * @vec: pointer to a kvec array
1086  * @nbytes: number of bytes to reserve
1087  *
1088  * Reserves enough buffer space to encode 'nbytes' of data and stores the
1089  * pointers in 'vec'. The size argument passed to xdr_reserve_space() is
1090  * determined based on the number of bytes remaining in the current page to
1091  * avoid invalidating iov_base pointers when xdr_commit_encode() is called.
1092  */
xdr_reserve_space_vec(struct xdr_stream * xdr,struct kvec * vec,size_t nbytes)1093 int xdr_reserve_space_vec(struct xdr_stream *xdr, struct kvec *vec, size_t nbytes)
1094 {
1095 	int thislen;
1096 	int v = 0;
1097 	__be32 *p;
1098 
1099 	/*
1100 	 * svcrdma requires every READ payload to start somewhere
1101 	 * in xdr->pages.
1102 	 */
1103 	if (xdr->iov == xdr->buf->head) {
1104 		xdr->iov = NULL;
1105 		xdr->end = xdr->p;
1106 	}
1107 
1108 	while (nbytes) {
1109 		thislen = xdr->buf->page_len % PAGE_SIZE;
1110 		thislen = min_t(size_t, nbytes, PAGE_SIZE - thislen);
1111 
1112 		p = xdr_reserve_space(xdr, thislen);
1113 		if (!p)
1114 			return -EIO;
1115 
1116 		vec[v].iov_base = p;
1117 		vec[v].iov_len = thislen;
1118 		v++;
1119 		nbytes -= thislen;
1120 	}
1121 
1122 	return v;
1123 }
1124 EXPORT_SYMBOL_GPL(xdr_reserve_space_vec);
1125 
1126 /**
1127  * xdr_truncate_encode - truncate an encode buffer
1128  * @xdr: pointer to xdr_stream
1129  * @len: new length of buffer
1130  *
1131  * Truncates the xdr stream, so that xdr->buf->len == len,
1132  * and xdr->p points at offset len from the start of the buffer, and
1133  * head, tail, and page lengths are adjusted to correspond.
1134  *
1135  * If this means moving xdr->p to a different buffer, we assume that
1136  * the end pointer should be set to the end of the current page,
1137  * except in the case of the head buffer when we assume the head
1138  * buffer's current length represents the end of the available buffer.
1139  *
1140  * This is *not* safe to use on a buffer that already has inlined page
1141  * cache pages (as in a zero-copy server read reply), except for the
1142  * simple case of truncating from one position in the tail to another.
1143  *
1144  */
xdr_truncate_encode(struct xdr_stream * xdr,size_t len)1145 void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
1146 {
1147 	struct xdr_buf *buf = xdr->buf;
1148 	struct kvec *head = buf->head;
1149 	struct kvec *tail = buf->tail;
1150 	int fraglen;
1151 	int new;
1152 
1153 	if (len > buf->len) {
1154 		WARN_ON_ONCE(1);
1155 		return;
1156 	}
1157 	xdr_commit_encode(xdr);
1158 
1159 	fraglen = min_t(int, buf->len - len, tail->iov_len);
1160 	tail->iov_len -= fraglen;
1161 	buf->len -= fraglen;
1162 	if (tail->iov_len) {
1163 		xdr->p = tail->iov_base + tail->iov_len;
1164 		WARN_ON_ONCE(!xdr->end);
1165 		WARN_ON_ONCE(!xdr->iov);
1166 		return;
1167 	}
1168 	WARN_ON_ONCE(fraglen);
1169 	fraglen = min_t(int, buf->len - len, buf->page_len);
1170 	buf->page_len -= fraglen;
1171 	buf->len -= fraglen;
1172 
1173 	new = buf->page_base + buf->page_len;
1174 
1175 	xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
1176 
1177 	if (buf->page_len) {
1178 		xdr->p = page_address(*xdr->page_ptr);
1179 		xdr->end = (void *)xdr->p + PAGE_SIZE;
1180 		xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
1181 		WARN_ON_ONCE(xdr->iov);
1182 		return;
1183 	}
1184 	if (fraglen)
1185 		xdr->end = head->iov_base + head->iov_len;
1186 	/* (otherwise assume xdr->end is already set) */
1187 	xdr->page_ptr--;
1188 	head->iov_len = len;
1189 	buf->len = len;
1190 	xdr->p = head->iov_base + head->iov_len;
1191 	xdr->iov = buf->head;
1192 }
1193 EXPORT_SYMBOL(xdr_truncate_encode);
1194 
1195 /**
1196  * xdr_restrict_buflen - decrease available buffer space
1197  * @xdr: pointer to xdr_stream
1198  * @newbuflen: new maximum number of bytes available
1199  *
1200  * Adjust our idea of how much space is available in the buffer.
1201  * If we've already used too much space in the buffer, returns -1.
1202  * If the available space is already smaller than newbuflen, returns 0
1203  * and does nothing.  Otherwise, adjusts xdr->buf->buflen to newbuflen
1204  * and ensures xdr->end is set at most offset newbuflen from the start
1205  * of the buffer.
1206  */
xdr_restrict_buflen(struct xdr_stream * xdr,int newbuflen)1207 int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen)
1208 {
1209 	struct xdr_buf *buf = xdr->buf;
1210 	int left_in_this_buf = (void *)xdr->end - (void *)xdr->p;
1211 	int end_offset = buf->len + left_in_this_buf;
1212 
1213 	if (newbuflen < 0 || newbuflen < buf->len)
1214 		return -1;
1215 	if (newbuflen > buf->buflen)
1216 		return 0;
1217 	if (newbuflen < end_offset)
1218 		xdr->end = (void *)xdr->end + newbuflen - end_offset;
1219 	buf->buflen = newbuflen;
1220 	return 0;
1221 }
1222 EXPORT_SYMBOL(xdr_restrict_buflen);
1223 
1224 /**
1225  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
1226  * @xdr: pointer to xdr_stream
1227  * @pages: list of pages
1228  * @base: offset of first byte
1229  * @len: length of data in bytes
1230  *
1231  */
xdr_write_pages(struct xdr_stream * xdr,struct page ** pages,unsigned int base,unsigned int len)1232 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
1233 		 unsigned int len)
1234 {
1235 	struct xdr_buf *buf = xdr->buf;
1236 	struct kvec *iov = buf->tail;
1237 	buf->pages = pages;
1238 	buf->page_base = base;
1239 	buf->page_len = len;
1240 
1241 	iov->iov_base = (char *)xdr->p;
1242 	iov->iov_len  = 0;
1243 	xdr->iov = iov;
1244 
1245 	if (len & 3) {
1246 		unsigned int pad = 4 - (len & 3);
1247 
1248 		BUG_ON(xdr->p >= xdr->end);
1249 		iov->iov_base = (char *)xdr->p + (len & 3);
1250 		iov->iov_len  += pad;
1251 		len += pad;
1252 		*xdr->p++ = 0;
1253 	}
1254 	buf->buflen += len;
1255 	buf->len += len;
1256 }
1257 EXPORT_SYMBOL_GPL(xdr_write_pages);
1258 
xdr_set_iov(struct xdr_stream * xdr,struct kvec * iov,unsigned int base,unsigned int len)1259 static unsigned int xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
1260 				unsigned int base, unsigned int len)
1261 {
1262 	if (len > iov->iov_len)
1263 		len = iov->iov_len;
1264 	if (unlikely(base > len))
1265 		base = len;
1266 	xdr->p = (__be32*)(iov->iov_base + base);
1267 	xdr->end = (__be32*)(iov->iov_base + len);
1268 	xdr->iov = iov;
1269 	xdr->page_ptr = NULL;
1270 	return len - base;
1271 }
1272 
xdr_set_tail_base(struct xdr_stream * xdr,unsigned int base,unsigned int len)1273 static unsigned int xdr_set_tail_base(struct xdr_stream *xdr,
1274 				      unsigned int base, unsigned int len)
1275 {
1276 	struct xdr_buf *buf = xdr->buf;
1277 
1278 	xdr_stream_set_pos(xdr, base + buf->page_len + buf->head->iov_len);
1279 	return xdr_set_iov(xdr, buf->tail, base, len);
1280 }
1281 
xdr_set_page_base(struct xdr_stream * xdr,unsigned int base,unsigned int len)1282 static unsigned int xdr_set_page_base(struct xdr_stream *xdr,
1283 				      unsigned int base, unsigned int len)
1284 {
1285 	unsigned int pgnr;
1286 	unsigned int maxlen;
1287 	unsigned int pgoff;
1288 	unsigned int pgend;
1289 	void *kaddr;
1290 
1291 	maxlen = xdr->buf->page_len;
1292 	if (base >= maxlen)
1293 		return 0;
1294 	else
1295 		maxlen -= base;
1296 	if (len > maxlen)
1297 		len = maxlen;
1298 
1299 	xdr_stream_page_set_pos(xdr, base);
1300 	base += xdr->buf->page_base;
1301 
1302 	pgnr = base >> PAGE_SHIFT;
1303 	xdr->page_ptr = &xdr->buf->pages[pgnr];
1304 	kaddr = page_address(*xdr->page_ptr);
1305 
1306 	pgoff = base & ~PAGE_MASK;
1307 	xdr->p = (__be32*)(kaddr + pgoff);
1308 
1309 	pgend = pgoff + len;
1310 	if (pgend > PAGE_SIZE)
1311 		pgend = PAGE_SIZE;
1312 	xdr->end = (__be32*)(kaddr + pgend);
1313 	xdr->iov = NULL;
1314 	return len;
1315 }
1316 
xdr_set_page(struct xdr_stream * xdr,unsigned int base,unsigned int len)1317 static void xdr_set_page(struct xdr_stream *xdr, unsigned int base,
1318 			 unsigned int len)
1319 {
1320 	if (xdr_set_page_base(xdr, base, len) == 0) {
1321 		base -= xdr->buf->page_len;
1322 		xdr_set_tail_base(xdr, base, len);
1323 	}
1324 }
1325 
xdr_set_next_page(struct xdr_stream * xdr)1326 static void xdr_set_next_page(struct xdr_stream *xdr)
1327 {
1328 	unsigned int newbase;
1329 
1330 	newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
1331 	newbase -= xdr->buf->page_base;
1332 	if (newbase < xdr->buf->page_len)
1333 		xdr_set_page_base(xdr, newbase, xdr_stream_remaining(xdr));
1334 	else
1335 		xdr_set_tail_base(xdr, 0, xdr_stream_remaining(xdr));
1336 }
1337 
xdr_set_next_buffer(struct xdr_stream * xdr)1338 static bool xdr_set_next_buffer(struct xdr_stream *xdr)
1339 {
1340 	if (xdr->page_ptr != NULL)
1341 		xdr_set_next_page(xdr);
1342 	else if (xdr->iov == xdr->buf->head)
1343 		xdr_set_page(xdr, 0, xdr_stream_remaining(xdr));
1344 	return xdr->p != xdr->end;
1345 }
1346 
1347 /**
1348  * xdr_init_decode - Initialize an xdr_stream for decoding data.
1349  * @xdr: pointer to xdr_stream struct
1350  * @buf: pointer to XDR buffer from which to decode data
1351  * @p: current pointer inside XDR buffer
1352  * @rqst: pointer to controlling rpc_rqst, for debugging
1353  */
xdr_init_decode(struct xdr_stream * xdr,struct xdr_buf * buf,__be32 * p,struct rpc_rqst * rqst)1354 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
1355 		     struct rpc_rqst *rqst)
1356 {
1357 	xdr->buf = buf;
1358 	xdr_reset_scratch_buffer(xdr);
1359 	xdr->nwords = XDR_QUADLEN(buf->len);
1360 	if (xdr_set_iov(xdr, buf->head, 0, buf->len) == 0 &&
1361 	    xdr_set_page_base(xdr, 0, buf->len) == 0)
1362 		xdr_set_iov(xdr, buf->tail, 0, buf->len);
1363 	if (p != NULL && p > xdr->p && xdr->end >= p) {
1364 		xdr->nwords -= p - xdr->p;
1365 		xdr->p = p;
1366 	}
1367 	xdr->rqst = rqst;
1368 }
1369 EXPORT_SYMBOL_GPL(xdr_init_decode);
1370 
1371 /**
1372  * xdr_init_decode_pages - Initialize an xdr_stream for decoding into pages
1373  * @xdr: pointer to xdr_stream struct
1374  * @buf: pointer to XDR buffer from which to decode data
1375  * @pages: list of pages to decode into
1376  * @len: length in bytes of buffer in pages
1377  */
xdr_init_decode_pages(struct xdr_stream * xdr,struct xdr_buf * buf,struct page ** pages,unsigned int len)1378 void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
1379 			   struct page **pages, unsigned int len)
1380 {
1381 	memset(buf, 0, sizeof(*buf));
1382 	buf->pages =  pages;
1383 	buf->page_len =  len;
1384 	buf->buflen =  len;
1385 	buf->len = len;
1386 	xdr_init_decode(xdr, buf, NULL, NULL);
1387 }
1388 EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
1389 
__xdr_inline_decode(struct xdr_stream * xdr,size_t nbytes)1390 static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
1391 {
1392 	unsigned int nwords = XDR_QUADLEN(nbytes);
1393 	__be32 *p = xdr->p;
1394 	__be32 *q = p + nwords;
1395 
1396 	if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
1397 		return NULL;
1398 	xdr->p = q;
1399 	xdr->nwords -= nwords;
1400 	return p;
1401 }
1402 
xdr_copy_to_scratch(struct xdr_stream * xdr,size_t nbytes)1403 static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
1404 {
1405 	__be32 *p;
1406 	char *cpdest = xdr->scratch.iov_base;
1407 	size_t cplen = (char *)xdr->end - (char *)xdr->p;
1408 
1409 	if (nbytes > xdr->scratch.iov_len)
1410 		goto out_overflow;
1411 	p = __xdr_inline_decode(xdr, cplen);
1412 	if (p == NULL)
1413 		return NULL;
1414 	memcpy(cpdest, p, cplen);
1415 	if (!xdr_set_next_buffer(xdr))
1416 		goto out_overflow;
1417 	cpdest += cplen;
1418 	nbytes -= cplen;
1419 	p = __xdr_inline_decode(xdr, nbytes);
1420 	if (p == NULL)
1421 		return NULL;
1422 	memcpy(cpdest, p, nbytes);
1423 	return xdr->scratch.iov_base;
1424 out_overflow:
1425 	trace_rpc_xdr_overflow(xdr, nbytes);
1426 	return NULL;
1427 }
1428 
1429 /**
1430  * xdr_inline_decode - Retrieve XDR data to decode
1431  * @xdr: pointer to xdr_stream struct
1432  * @nbytes: number of bytes of data to decode
1433  *
1434  * Check if the input buffer is long enough to enable us to decode
1435  * 'nbytes' more bytes of data starting at the current position.
1436  * If so return the current pointer, then update the current
1437  * pointer position.
1438  */
xdr_inline_decode(struct xdr_stream * xdr,size_t nbytes)1439 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
1440 {
1441 	__be32 *p;
1442 
1443 	if (unlikely(nbytes == 0))
1444 		return xdr->p;
1445 	if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
1446 		goto out_overflow;
1447 	p = __xdr_inline_decode(xdr, nbytes);
1448 	if (p != NULL)
1449 		return p;
1450 	return xdr_copy_to_scratch(xdr, nbytes);
1451 out_overflow:
1452 	trace_rpc_xdr_overflow(xdr, nbytes);
1453 	return NULL;
1454 }
1455 EXPORT_SYMBOL_GPL(xdr_inline_decode);
1456 
xdr_realign_pages(struct xdr_stream * xdr)1457 static void xdr_realign_pages(struct xdr_stream *xdr)
1458 {
1459 	struct xdr_buf *buf = xdr->buf;
1460 	struct kvec *iov = buf->head;
1461 	unsigned int cur = xdr_stream_pos(xdr);
1462 	unsigned int copied;
1463 
1464 	/* Realign pages to current pointer position */
1465 	if (iov->iov_len > cur) {
1466 		copied = xdr_shrink_bufhead(buf, cur);
1467 		trace_rpc_xdr_alignment(xdr, cur, copied);
1468 		xdr_set_page(xdr, 0, buf->page_len);
1469 	}
1470 }
1471 
xdr_align_pages(struct xdr_stream * xdr,unsigned int len)1472 static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
1473 {
1474 	struct xdr_buf *buf = xdr->buf;
1475 	unsigned int nwords = XDR_QUADLEN(len);
1476 	unsigned int copied;
1477 
1478 	if (xdr->nwords == 0)
1479 		return 0;
1480 
1481 	xdr_realign_pages(xdr);
1482 	if (nwords > xdr->nwords) {
1483 		nwords = xdr->nwords;
1484 		len = nwords << 2;
1485 	}
1486 	if (buf->page_len <= len)
1487 		len = buf->page_len;
1488 	else if (nwords < xdr->nwords) {
1489 		/* Truncate page data and move it into the tail */
1490 		copied = xdr_shrink_pagelen(buf, len);
1491 		trace_rpc_xdr_alignment(xdr, len, copied);
1492 	}
1493 	return len;
1494 }
1495 
1496 /**
1497  * xdr_read_pages - align page-based XDR data to current pointer position
1498  * @xdr: pointer to xdr_stream struct
1499  * @len: number of bytes of page data
1500  *
1501  * Moves data beyond the current pointer position from the XDR head[] buffer
1502  * into the page list. Any data that lies beyond current position + @len
1503  * bytes is moved into the XDR tail[]. The xdr_stream current position is
1504  * then advanced past that data to align to the next XDR object in the tail.
1505  *
1506  * Returns the number of XDR encoded bytes now contained in the pages
1507  */
xdr_read_pages(struct xdr_stream * xdr,unsigned int len)1508 unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
1509 {
1510 	unsigned int nwords = XDR_QUADLEN(len);
1511 	unsigned int base, end, pglen;
1512 
1513 	pglen = xdr_align_pages(xdr, nwords << 2);
1514 	if (pglen == 0)
1515 		return 0;
1516 
1517 	base = (nwords << 2) - pglen;
1518 	end = xdr_stream_remaining(xdr) - pglen;
1519 
1520 	xdr_set_tail_base(xdr, base, end);
1521 	return len <= pglen ? len : pglen;
1522 }
1523 EXPORT_SYMBOL_GPL(xdr_read_pages);
1524 
1525 /**
1526  * xdr_set_pagelen - Sets the length of the XDR pages
1527  * @xdr: pointer to xdr_stream struct
1528  * @len: new length of the XDR page data
1529  *
1530  * Either grows or shrinks the length of the xdr pages by setting pagelen to
1531  * @len bytes. When shrinking, any extra data is moved into buf->tail, whereas
1532  * when growing any data beyond the current pointer is moved into the tail.
1533  *
1534  * Returns True if the operation was successful, and False otherwise.
1535  */
xdr_set_pagelen(struct xdr_stream * xdr,unsigned int len)1536 void xdr_set_pagelen(struct xdr_stream *xdr, unsigned int len)
1537 {
1538 	struct xdr_buf *buf = xdr->buf;
1539 	size_t remaining = xdr_stream_remaining(xdr);
1540 	size_t base = 0;
1541 
1542 	if (len < buf->page_len) {
1543 		base = buf->page_len - len;
1544 		xdr_shrink_pagelen(buf, len);
1545 	} else {
1546 		xdr_buf_head_shift_right(buf, xdr_stream_pos(xdr),
1547 					 buf->page_len, remaining);
1548 		if (len > buf->page_len)
1549 			xdr_buf_try_expand(buf, len - buf->page_len);
1550 	}
1551 	xdr_set_tail_base(xdr, base, remaining);
1552 }
1553 EXPORT_SYMBOL_GPL(xdr_set_pagelen);
1554 
1555 /**
1556  * xdr_enter_page - decode data from the XDR page
1557  * @xdr: pointer to xdr_stream struct
1558  * @len: number of bytes of page data
1559  *
1560  * Moves data beyond the current pointer position from the XDR head[] buffer
1561  * into the page list. Any data that lies beyond current position + "len"
1562  * bytes is moved into the XDR tail[]. The current pointer is then
1563  * repositioned at the beginning of the first XDR page.
1564  */
xdr_enter_page(struct xdr_stream * xdr,unsigned int len)1565 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
1566 {
1567 	len = xdr_align_pages(xdr, len);
1568 	/*
1569 	 * Position current pointer at beginning of tail, and
1570 	 * set remaining message length.
1571 	 */
1572 	if (len != 0)
1573 		xdr_set_page_base(xdr, 0, len);
1574 }
1575 EXPORT_SYMBOL_GPL(xdr_enter_page);
1576 
1577 static const struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
1578 
xdr_buf_from_iov(const struct kvec * iov,struct xdr_buf * buf)1579 void xdr_buf_from_iov(const struct kvec *iov, struct xdr_buf *buf)
1580 {
1581 	buf->head[0] = *iov;
1582 	buf->tail[0] = empty_iov;
1583 	buf->page_len = 0;
1584 	buf->buflen = buf->len = iov->iov_len;
1585 }
1586 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
1587 
1588 /**
1589  * xdr_buf_subsegment - set subbuf to a portion of buf
1590  * @buf: an xdr buffer
1591  * @subbuf: the result buffer
1592  * @base: beginning of range in bytes
1593  * @len: length of range in bytes
1594  *
1595  * sets @subbuf to an xdr buffer representing the portion of @buf of
1596  * length @len starting at offset @base.
1597  *
1598  * @buf and @subbuf may be pointers to the same struct xdr_buf.
1599  *
1600  * Returns -1 if base or length are out of bounds.
1601  */
xdr_buf_subsegment(const struct xdr_buf * buf,struct xdr_buf * subbuf,unsigned int base,unsigned int len)1602 int xdr_buf_subsegment(const struct xdr_buf *buf, struct xdr_buf *subbuf,
1603 		       unsigned int base, unsigned int len)
1604 {
1605 	subbuf->buflen = subbuf->len = len;
1606 	if (base < buf->head[0].iov_len) {
1607 		subbuf->head[0].iov_base = buf->head[0].iov_base + base;
1608 		subbuf->head[0].iov_len = min_t(unsigned int, len,
1609 						buf->head[0].iov_len - base);
1610 		len -= subbuf->head[0].iov_len;
1611 		base = 0;
1612 	} else {
1613 		base -= buf->head[0].iov_len;
1614 		subbuf->head[0].iov_base = buf->head[0].iov_base;
1615 		subbuf->head[0].iov_len = 0;
1616 	}
1617 
1618 	if (base < buf->page_len) {
1619 		subbuf->page_len = min(buf->page_len - base, len);
1620 		base += buf->page_base;
1621 		subbuf->page_base = base & ~PAGE_MASK;
1622 		subbuf->pages = &buf->pages[base >> PAGE_SHIFT];
1623 		len -= subbuf->page_len;
1624 		base = 0;
1625 	} else {
1626 		base -= buf->page_len;
1627 		subbuf->pages = buf->pages;
1628 		subbuf->page_base = 0;
1629 		subbuf->page_len = 0;
1630 	}
1631 
1632 	if (base < buf->tail[0].iov_len) {
1633 		subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
1634 		subbuf->tail[0].iov_len = min_t(unsigned int, len,
1635 						buf->tail[0].iov_len - base);
1636 		len -= subbuf->tail[0].iov_len;
1637 		base = 0;
1638 	} else {
1639 		base -= buf->tail[0].iov_len;
1640 		subbuf->tail[0].iov_base = buf->tail[0].iov_base;
1641 		subbuf->tail[0].iov_len = 0;
1642 	}
1643 
1644 	if (base || len)
1645 		return -1;
1646 	return 0;
1647 }
1648 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
1649 
1650 /**
1651  * xdr_stream_subsegment - set @subbuf to a portion of @xdr
1652  * @xdr: an xdr_stream set up for decoding
1653  * @subbuf: the result buffer
1654  * @nbytes: length of @xdr to extract, in bytes
1655  *
1656  * Sets up @subbuf to represent a portion of @xdr. The portion
1657  * starts at the current offset in @xdr, and extends for a length
1658  * of @nbytes. If this is successful, @xdr is advanced to the next
1659  * XDR data item following that portion.
1660  *
1661  * Return values:
1662  *   %true: @subbuf has been initialized, and @xdr has been advanced.
1663  *   %false: a bounds error has occurred
1664  */
xdr_stream_subsegment(struct xdr_stream * xdr,struct xdr_buf * subbuf,unsigned int nbytes)1665 bool xdr_stream_subsegment(struct xdr_stream *xdr, struct xdr_buf *subbuf,
1666 			   unsigned int nbytes)
1667 {
1668 	unsigned int start = xdr_stream_pos(xdr);
1669 	unsigned int remaining, len;
1670 
1671 	/* Extract @subbuf and bounds-check the fn arguments */
1672 	if (xdr_buf_subsegment(xdr->buf, subbuf, start, nbytes))
1673 		return false;
1674 
1675 	/* Advance @xdr by @nbytes */
1676 	for (remaining = nbytes; remaining;) {
1677 		if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
1678 			return false;
1679 
1680 		len = (char *)xdr->end - (char *)xdr->p;
1681 		if (remaining <= len) {
1682 			xdr->p = (__be32 *)((char *)xdr->p +
1683 					(remaining + xdr_pad_size(nbytes)));
1684 			break;
1685 		}
1686 
1687 		xdr->p = (__be32 *)((char *)xdr->p + len);
1688 		xdr->end = xdr->p;
1689 		remaining -= len;
1690 	}
1691 
1692 	xdr_stream_set_pos(xdr, start + nbytes);
1693 	return true;
1694 }
1695 EXPORT_SYMBOL_GPL(xdr_stream_subsegment);
1696 
1697 /**
1698  * xdr_stream_move_subsegment - Move part of a stream to another position
1699  * @xdr: the source xdr_stream
1700  * @offset: the source offset of the segment
1701  * @target: the target offset of the segment
1702  * @length: the number of bytes to move
1703  *
1704  * Moves @length bytes from @offset to @target in the xdr_stream, overwriting
1705  * anything in its space. Returns the number of bytes in the segment.
1706  */
xdr_stream_move_subsegment(struct xdr_stream * xdr,unsigned int offset,unsigned int target,unsigned int length)1707 unsigned int xdr_stream_move_subsegment(struct xdr_stream *xdr, unsigned int offset,
1708 					unsigned int target, unsigned int length)
1709 {
1710 	struct xdr_buf buf;
1711 	unsigned int shift;
1712 
1713 	if (offset < target) {
1714 		shift = target - offset;
1715 		if (xdr_buf_subsegment(xdr->buf, &buf, offset, shift + length) < 0)
1716 			return 0;
1717 		xdr_buf_head_shift_right(&buf, 0, length, shift);
1718 	} else if (offset > target) {
1719 		shift = offset - target;
1720 		if (xdr_buf_subsegment(xdr->buf, &buf, target, shift + length) < 0)
1721 			return 0;
1722 		xdr_buf_head_shift_left(&buf, shift, length, shift);
1723 	}
1724 	return length;
1725 }
1726 EXPORT_SYMBOL_GPL(xdr_stream_move_subsegment);
1727 
1728 /**
1729  * xdr_stream_zero - zero out a portion of an xdr_stream
1730  * @xdr: an xdr_stream to zero out
1731  * @offset: the starting point in the stream
1732  * @length: the number of bytes to zero
1733  */
xdr_stream_zero(struct xdr_stream * xdr,unsigned int offset,unsigned int length)1734 unsigned int xdr_stream_zero(struct xdr_stream *xdr, unsigned int offset,
1735 			     unsigned int length)
1736 {
1737 	struct xdr_buf buf;
1738 
1739 	if (xdr_buf_subsegment(xdr->buf, &buf, offset, length) < 0)
1740 		return 0;
1741 	if (buf.head[0].iov_len)
1742 		xdr_buf_iov_zero(buf.head, 0, buf.head[0].iov_len);
1743 	if (buf.page_len > 0)
1744 		xdr_buf_pages_zero(&buf, 0, buf.page_len);
1745 	if (buf.tail[0].iov_len)
1746 		xdr_buf_iov_zero(buf.tail, 0, buf.tail[0].iov_len);
1747 	return length;
1748 }
1749 EXPORT_SYMBOL_GPL(xdr_stream_zero);
1750 
1751 /**
1752  * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
1753  * @buf: buf to be trimmed
1754  * @len: number of bytes to reduce "buf" by
1755  *
1756  * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
1757  * that it's possible that we'll trim less than that amount if the xdr_buf is
1758  * too small, or if (for instance) it's all in the head and the parser has
1759  * already read too far into it.
1760  */
xdr_buf_trim(struct xdr_buf * buf,unsigned int len)1761 void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
1762 {
1763 	size_t cur;
1764 	unsigned int trim = len;
1765 
1766 	if (buf->tail[0].iov_len) {
1767 		cur = min_t(size_t, buf->tail[0].iov_len, trim);
1768 		buf->tail[0].iov_len -= cur;
1769 		trim -= cur;
1770 		if (!trim)
1771 			goto fix_len;
1772 	}
1773 
1774 	if (buf->page_len) {
1775 		cur = min_t(unsigned int, buf->page_len, trim);
1776 		buf->page_len -= cur;
1777 		trim -= cur;
1778 		if (!trim)
1779 			goto fix_len;
1780 	}
1781 
1782 	if (buf->head[0].iov_len) {
1783 		cur = min_t(size_t, buf->head[0].iov_len, trim);
1784 		buf->head[0].iov_len -= cur;
1785 		trim -= cur;
1786 	}
1787 fix_len:
1788 	buf->len -= (len - trim);
1789 }
1790 EXPORT_SYMBOL_GPL(xdr_buf_trim);
1791 
__read_bytes_from_xdr_buf(const struct xdr_buf * subbuf,void * obj,unsigned int len)1792 static void __read_bytes_from_xdr_buf(const struct xdr_buf *subbuf,
1793 				      void *obj, unsigned int len)
1794 {
1795 	unsigned int this_len;
1796 
1797 	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1798 	memcpy(obj, subbuf->head[0].iov_base, this_len);
1799 	len -= this_len;
1800 	obj += this_len;
1801 	this_len = min_t(unsigned int, len, subbuf->page_len);
1802 	_copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
1803 	len -= this_len;
1804 	obj += this_len;
1805 	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1806 	memcpy(obj, subbuf->tail[0].iov_base, this_len);
1807 }
1808 
1809 /* 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)1810 int read_bytes_from_xdr_buf(const struct xdr_buf *buf, unsigned int base,
1811 			    void *obj, unsigned int len)
1812 {
1813 	struct xdr_buf subbuf;
1814 	int status;
1815 
1816 	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1817 	if (status != 0)
1818 		return status;
1819 	__read_bytes_from_xdr_buf(&subbuf, obj, len);
1820 	return 0;
1821 }
1822 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
1823 
__write_bytes_to_xdr_buf(const struct xdr_buf * subbuf,void * obj,unsigned int len)1824 static void __write_bytes_to_xdr_buf(const struct xdr_buf *subbuf,
1825 				     void *obj, unsigned int len)
1826 {
1827 	unsigned int this_len;
1828 
1829 	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1830 	memcpy(subbuf->head[0].iov_base, obj, this_len);
1831 	len -= this_len;
1832 	obj += this_len;
1833 	this_len = min_t(unsigned int, len, subbuf->page_len);
1834 	_copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
1835 	len -= this_len;
1836 	obj += this_len;
1837 	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1838 	memcpy(subbuf->tail[0].iov_base, obj, this_len);
1839 }
1840 
1841 /* 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)1842 int write_bytes_to_xdr_buf(const struct xdr_buf *buf, unsigned int base,
1843 			   void *obj, unsigned int len)
1844 {
1845 	struct xdr_buf subbuf;
1846 	int status;
1847 
1848 	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1849 	if (status != 0)
1850 		return status;
1851 	__write_bytes_to_xdr_buf(&subbuf, obj, len);
1852 	return 0;
1853 }
1854 EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
1855 
xdr_decode_word(const struct xdr_buf * buf,unsigned int base,u32 * obj)1856 int xdr_decode_word(const struct xdr_buf *buf, unsigned int base, u32 *obj)
1857 {
1858 	__be32	raw;
1859 	int	status;
1860 
1861 	status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1862 	if (status)
1863 		return status;
1864 	*obj = be32_to_cpu(raw);
1865 	return 0;
1866 }
1867 EXPORT_SYMBOL_GPL(xdr_decode_word);
1868 
xdr_encode_word(const struct xdr_buf * buf,unsigned int base,u32 obj)1869 int xdr_encode_word(const struct xdr_buf *buf, unsigned int base, u32 obj)
1870 {
1871 	__be32	raw = cpu_to_be32(obj);
1872 
1873 	return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1874 }
1875 EXPORT_SYMBOL_GPL(xdr_encode_word);
1876 
1877 /* 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)1878 static int xdr_xcode_array2(const struct xdr_buf *buf, unsigned int base,
1879 			    struct xdr_array2_desc *desc, int encode)
1880 {
1881 	char *elem = NULL, *c;
1882 	unsigned int copied = 0, todo, avail_here;
1883 	struct page **ppages = NULL;
1884 	int err;
1885 
1886 	if (encode) {
1887 		if (xdr_encode_word(buf, base, desc->array_len) != 0)
1888 			return -EINVAL;
1889 	} else {
1890 		if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1891 		    desc->array_len > desc->array_maxlen ||
1892 		    (unsigned long) base + 4 + desc->array_len *
1893 				    desc->elem_size > buf->len)
1894 			return -EINVAL;
1895 	}
1896 	base += 4;
1897 
1898 	if (!desc->xcode)
1899 		return 0;
1900 
1901 	todo = desc->array_len * desc->elem_size;
1902 
1903 	/* process head */
1904 	if (todo && base < buf->head->iov_len) {
1905 		c = buf->head->iov_base + base;
1906 		avail_here = min_t(unsigned int, todo,
1907 				   buf->head->iov_len - base);
1908 		todo -= avail_here;
1909 
1910 		while (avail_here >= desc->elem_size) {
1911 			err = desc->xcode(desc, c);
1912 			if (err)
1913 				goto out;
1914 			c += desc->elem_size;
1915 			avail_here -= desc->elem_size;
1916 		}
1917 		if (avail_here) {
1918 			if (!elem) {
1919 				elem = kmalloc(desc->elem_size, GFP_KERNEL);
1920 				err = -ENOMEM;
1921 				if (!elem)
1922 					goto out;
1923 			}
1924 			if (encode) {
1925 				err = desc->xcode(desc, elem);
1926 				if (err)
1927 					goto out;
1928 				memcpy(c, elem, avail_here);
1929 			} else
1930 				memcpy(elem, c, avail_here);
1931 			copied = avail_here;
1932 		}
1933 		base = buf->head->iov_len;  /* align to start of pages */
1934 	}
1935 
1936 	/* process pages array */
1937 	base -= buf->head->iov_len;
1938 	if (todo && base < buf->page_len) {
1939 		unsigned int avail_page;
1940 
1941 		avail_here = min(todo, buf->page_len - base);
1942 		todo -= avail_here;
1943 
1944 		base += buf->page_base;
1945 		ppages = buf->pages + (base >> PAGE_SHIFT);
1946 		base &= ~PAGE_MASK;
1947 		avail_page = min_t(unsigned int, PAGE_SIZE - base,
1948 					avail_here);
1949 		c = kmap(*ppages) + base;
1950 
1951 		while (avail_here) {
1952 			avail_here -= avail_page;
1953 			if (copied || avail_page < desc->elem_size) {
1954 				unsigned int l = min(avail_page,
1955 					desc->elem_size - copied);
1956 				if (!elem) {
1957 					elem = kmalloc(desc->elem_size,
1958 						       GFP_KERNEL);
1959 					err = -ENOMEM;
1960 					if (!elem)
1961 						goto out;
1962 				}
1963 				if (encode) {
1964 					if (!copied) {
1965 						err = desc->xcode(desc, elem);
1966 						if (err)
1967 							goto out;
1968 					}
1969 					memcpy(c, elem + copied, l);
1970 					copied += l;
1971 					if (copied == desc->elem_size)
1972 						copied = 0;
1973 				} else {
1974 					memcpy(elem + copied, c, l);
1975 					copied += l;
1976 					if (copied == desc->elem_size) {
1977 						err = desc->xcode(desc, elem);
1978 						if (err)
1979 							goto out;
1980 						copied = 0;
1981 					}
1982 				}
1983 				avail_page -= l;
1984 				c += l;
1985 			}
1986 			while (avail_page >= desc->elem_size) {
1987 				err = desc->xcode(desc, c);
1988 				if (err)
1989 					goto out;
1990 				c += desc->elem_size;
1991 				avail_page -= desc->elem_size;
1992 			}
1993 			if (avail_page) {
1994 				unsigned int l = min(avail_page,
1995 					    desc->elem_size - copied);
1996 				if (!elem) {
1997 					elem = kmalloc(desc->elem_size,
1998 						       GFP_KERNEL);
1999 					err = -ENOMEM;
2000 					if (!elem)
2001 						goto out;
2002 				}
2003 				if (encode) {
2004 					if (!copied) {
2005 						err = desc->xcode(desc, elem);
2006 						if (err)
2007 							goto out;
2008 					}
2009 					memcpy(c, elem + copied, l);
2010 					copied += l;
2011 					if (copied == desc->elem_size)
2012 						copied = 0;
2013 				} else {
2014 					memcpy(elem + copied, c, l);
2015 					copied += l;
2016 					if (copied == desc->elem_size) {
2017 						err = desc->xcode(desc, elem);
2018 						if (err)
2019 							goto out;
2020 						copied = 0;
2021 					}
2022 				}
2023 			}
2024 			if (avail_here) {
2025 				kunmap(*ppages);
2026 				ppages++;
2027 				c = kmap(*ppages);
2028 			}
2029 
2030 			avail_page = min(avail_here,
2031 				 (unsigned int) PAGE_SIZE);
2032 		}
2033 		base = buf->page_len;  /* align to start of tail */
2034 	}
2035 
2036 	/* process tail */
2037 	base -= buf->page_len;
2038 	if (todo) {
2039 		c = buf->tail->iov_base + base;
2040 		if (copied) {
2041 			unsigned int l = desc->elem_size - copied;
2042 
2043 			if (encode)
2044 				memcpy(c, elem + copied, l);
2045 			else {
2046 				memcpy(elem + copied, c, l);
2047 				err = desc->xcode(desc, elem);
2048 				if (err)
2049 					goto out;
2050 			}
2051 			todo -= l;
2052 			c += l;
2053 		}
2054 		while (todo) {
2055 			err = desc->xcode(desc, c);
2056 			if (err)
2057 				goto out;
2058 			c += desc->elem_size;
2059 			todo -= desc->elem_size;
2060 		}
2061 	}
2062 	err = 0;
2063 
2064 out:
2065 	kfree(elem);
2066 	if (ppages)
2067 		kunmap(*ppages);
2068 	return err;
2069 }
2070 
xdr_decode_array2(const struct xdr_buf * buf,unsigned int base,struct xdr_array2_desc * desc)2071 int xdr_decode_array2(const struct xdr_buf *buf, unsigned int base,
2072 		      struct xdr_array2_desc *desc)
2073 {
2074 	if (base >= buf->len)
2075 		return -EINVAL;
2076 
2077 	return xdr_xcode_array2(buf, base, desc, 0);
2078 }
2079 EXPORT_SYMBOL_GPL(xdr_decode_array2);
2080 
xdr_encode_array2(const struct xdr_buf * buf,unsigned int base,struct xdr_array2_desc * desc)2081 int xdr_encode_array2(const struct xdr_buf *buf, unsigned int base,
2082 		      struct xdr_array2_desc *desc)
2083 {
2084 	if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
2085 	    buf->head->iov_len + buf->page_len + buf->tail->iov_len)
2086 		return -EINVAL;
2087 
2088 	return xdr_xcode_array2(buf, base, desc, 1);
2089 }
2090 EXPORT_SYMBOL_GPL(xdr_encode_array2);
2091 
xdr_process_buf(const struct xdr_buf * buf,unsigned int offset,unsigned int len,int (* actor)(struct scatterlist *,void *),void * data)2092 int xdr_process_buf(const struct xdr_buf *buf, unsigned int offset,
2093 		    unsigned int len,
2094 		    int (*actor)(struct scatterlist *, void *), void *data)
2095 {
2096 	int i, ret = 0;
2097 	unsigned int page_len, thislen, page_offset;
2098 	struct scatterlist      sg[1];
2099 
2100 	sg_init_table(sg, 1);
2101 
2102 	if (offset >= buf->head[0].iov_len) {
2103 		offset -= buf->head[0].iov_len;
2104 	} else {
2105 		thislen = buf->head[0].iov_len - offset;
2106 		if (thislen > len)
2107 			thislen = len;
2108 		sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
2109 		ret = actor(sg, data);
2110 		if (ret)
2111 			goto out;
2112 		offset = 0;
2113 		len -= thislen;
2114 	}
2115 	if (len == 0)
2116 		goto out;
2117 
2118 	if (offset >= buf->page_len) {
2119 		offset -= buf->page_len;
2120 	} else {
2121 		page_len = buf->page_len - offset;
2122 		if (page_len > len)
2123 			page_len = len;
2124 		len -= page_len;
2125 		page_offset = (offset + buf->page_base) & (PAGE_SIZE - 1);
2126 		i = (offset + buf->page_base) >> PAGE_SHIFT;
2127 		thislen = PAGE_SIZE - page_offset;
2128 		do {
2129 			if (thislen > page_len)
2130 				thislen = page_len;
2131 			sg_set_page(sg, buf->pages[i], thislen, page_offset);
2132 			ret = actor(sg, data);
2133 			if (ret)
2134 				goto out;
2135 			page_len -= thislen;
2136 			i++;
2137 			page_offset = 0;
2138 			thislen = PAGE_SIZE;
2139 		} while (page_len != 0);
2140 		offset = 0;
2141 	}
2142 	if (len == 0)
2143 		goto out;
2144 	if (offset < buf->tail[0].iov_len) {
2145 		thislen = buf->tail[0].iov_len - offset;
2146 		if (thislen > len)
2147 			thislen = len;
2148 		sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
2149 		ret = actor(sg, data);
2150 		len -= thislen;
2151 	}
2152 	if (len != 0)
2153 		ret = -EINVAL;
2154 out:
2155 	return ret;
2156 }
2157 EXPORT_SYMBOL_GPL(xdr_process_buf);
2158 
2159 /**
2160  * xdr_stream_decode_opaque - Decode variable length opaque
2161  * @xdr: pointer to xdr_stream
2162  * @ptr: location to store opaque data
2163  * @size: size of storage buffer @ptr
2164  *
2165  * Return values:
2166  *   On success, returns size of object stored in *@ptr
2167  *   %-EBADMSG on XDR buffer overflow
2168  *   %-EMSGSIZE on overflow of storage buffer @ptr
2169  */
xdr_stream_decode_opaque(struct xdr_stream * xdr,void * ptr,size_t size)2170 ssize_t xdr_stream_decode_opaque(struct xdr_stream *xdr, void *ptr, size_t size)
2171 {
2172 	ssize_t ret;
2173 	void *p;
2174 
2175 	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
2176 	if (ret <= 0)
2177 		return ret;
2178 	memcpy(ptr, p, ret);
2179 	return ret;
2180 }
2181 EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque);
2182 
2183 /**
2184  * xdr_stream_decode_opaque_dup - Decode and duplicate variable length opaque
2185  * @xdr: pointer to xdr_stream
2186  * @ptr: location to store pointer to opaque data
2187  * @maxlen: maximum acceptable object size
2188  * @gfp_flags: GFP mask to use
2189  *
2190  * Return values:
2191  *   On success, returns size of object stored in *@ptr
2192  *   %-EBADMSG on XDR buffer overflow
2193  *   %-EMSGSIZE if the size of the object would exceed @maxlen
2194  *   %-ENOMEM on memory allocation failure
2195  */
xdr_stream_decode_opaque_dup(struct xdr_stream * xdr,void ** ptr,size_t maxlen,gfp_t gfp_flags)2196 ssize_t xdr_stream_decode_opaque_dup(struct xdr_stream *xdr, void **ptr,
2197 		size_t maxlen, gfp_t gfp_flags)
2198 {
2199 	ssize_t ret;
2200 	void *p;
2201 
2202 	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
2203 	if (ret > 0) {
2204 		*ptr = kmemdup(p, ret, gfp_flags);
2205 		if (*ptr != NULL)
2206 			return ret;
2207 		ret = -ENOMEM;
2208 	}
2209 	*ptr = NULL;
2210 	return ret;
2211 }
2212 EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque_dup);
2213 
2214 /**
2215  * xdr_stream_decode_string - Decode variable length string
2216  * @xdr: pointer to xdr_stream
2217  * @str: location to store string
2218  * @size: size of storage buffer @str
2219  *
2220  * Return values:
2221  *   On success, returns length of NUL-terminated string stored in *@str
2222  *   %-EBADMSG on XDR buffer overflow
2223  *   %-EMSGSIZE on overflow of storage buffer @str
2224  */
xdr_stream_decode_string(struct xdr_stream * xdr,char * str,size_t size)2225 ssize_t xdr_stream_decode_string(struct xdr_stream *xdr, char *str, size_t size)
2226 {
2227 	ssize_t ret;
2228 	void *p;
2229 
2230 	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
2231 	if (ret > 0) {
2232 		memcpy(str, p, ret);
2233 		str[ret] = '\0';
2234 		return strlen(str);
2235 	}
2236 	*str = '\0';
2237 	return ret;
2238 }
2239 EXPORT_SYMBOL_GPL(xdr_stream_decode_string);
2240 
2241 /**
2242  * xdr_stream_decode_string_dup - Decode and duplicate variable length string
2243  * @xdr: pointer to xdr_stream
2244  * @str: location to store pointer to string
2245  * @maxlen: maximum acceptable string length
2246  * @gfp_flags: GFP mask to use
2247  *
2248  * Return values:
2249  *   On success, returns length of NUL-terminated string stored in *@ptr
2250  *   %-EBADMSG on XDR buffer overflow
2251  *   %-EMSGSIZE if the size of the string would exceed @maxlen
2252  *   %-ENOMEM on memory allocation failure
2253  */
xdr_stream_decode_string_dup(struct xdr_stream * xdr,char ** str,size_t maxlen,gfp_t gfp_flags)2254 ssize_t xdr_stream_decode_string_dup(struct xdr_stream *xdr, char **str,
2255 		size_t maxlen, gfp_t gfp_flags)
2256 {
2257 	void *p;
2258 	ssize_t ret;
2259 
2260 	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
2261 	if (ret > 0) {
2262 		char *s = kmemdup_nul(p, ret, gfp_flags);
2263 		if (s != NULL) {
2264 			*str = s;
2265 			return strlen(s);
2266 		}
2267 		ret = -ENOMEM;
2268 	}
2269 	*str = NULL;
2270 	return ret;
2271 }
2272 EXPORT_SYMBOL_GPL(xdr_stream_decode_string_dup);
2273