net/sunrpc/xdr.c

   1 /*
   2  * linux/net/sunrpc/xdr.c
   3  *
   4  * Generic XDR support.
   5  *
   6  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/socket.h>
  11 #include <linux/string.h>
  12 #include <linux/kernel.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/errno.h>
  15 #include <linux/in.h>
  16 #include <linux/net.h>
  17 #include <net/sock.h>
  18 #include <linux/sunrpc/xdr.h>
  19 #include <linux/sunrpc/msg_prot.h>
  20
  21 /*
  22  * XDR functions for basic NFS types
  23  */
  24 u32 *
  25 xdr_encode_netobj(u32 *p, const struct xdr_netobj *obj)
  26 {
  27         unsigned int    quadlen = XDR_QUADLEN(obj->len);
  28
  29         p[quadlen] = 0;         /* zero trailing bytes */
  30         *p++ = htonl(obj->len);
  31         memcpy(p, obj->data, obj->len);
  32         return p + XDR_QUADLEN(obj->len);
  33 }
  34
  35 u32 *
  36 xdr_decode_netobj(u32 *p, struct xdr_netobj *obj)
  37 {
  38         unsigned int    len;
  39
  40         if ((len = ntohl(*p++)) > XDR_MAX_NETOBJ)
  41                 return NULL;
  42         obj->len  = len;
  43         obj->data = (u8 *) p;
  44         return p + XDR_QUADLEN(len);
  45 }
  46
  47 /**
  48  * xdr_encode_opaque_fixed - Encode fixed length opaque data
  49  * @p: pointer to current position in XDR buffer.
  50  * @ptr: pointer to data to encode (or NULL)
  51  * @nbytes: size of data.
  52  *
  53  * Copy the array of data of length nbytes at ptr to the XDR buffer
  54  * at position p, then align to the next 32-bit boundary by padding
  55  * with zero bytes (see RFC1832).
  56  * Note: if ptr is NULL, only the padding is performed.
  57  *
  58  * Returns the updated current XDR buffer position
  59  *
  60  */
  61 u32 *xdr_encode_opaque_fixed(u32 *p, const void *ptr, unsigned int nbytes)
  62 {
  63         if (likely(nbytes != 0)) {
  64                 unsigned int quadlen = XDR_QUADLEN(nbytes);
  65                 unsigned int padding = (quadlen << 2) - nbytes;
  66
  67                 if (ptr != NULL)
  68                         memcpy(p, ptr, nbytes);
  69                 if (padding != 0)
  70                         memset((char *)p + nbytes, 0, padding);
  71                 p += quadlen;
  72         }
  73         return p;
  74 }
  75 EXPORT_SYMBOL(xdr_encode_opaque_fixed);
  76
  77 /**
  78  * xdr_encode_opaque - Encode variable length opaque data
  79  * @p: pointer to current position in XDR buffer.
  80  * @ptr: pointer to data to encode (or NULL)
  81  * @nbytes: size of data.
  82  *
  83  * Returns the updated current XDR buffer position
  84  */
  85 u32 *xdr_encode_opaque(u32 *p, const void *ptr, unsigned int nbytes)
  86 {
  87         *p++ = htonl(nbytes);
  88         return xdr_encode_opaque_fixed(p, ptr, nbytes);
  89 }
  90 EXPORT_SYMBOL(xdr_encode_opaque);
  91
  92 u32 *
  93 xdr_encode_string(u32 *p, const char *string)
  94 {
  95         return xdr_encode_array(p, string, strlen(string));
  96 }
  97
  98 u32 *
  99 xdr_decode_string(u32 *p, char **sp, int *lenp, int maxlen)
 100 {
 101         unsigned int    len;
 102         char            *string;
 103
 104         if ((len = ntohl(*p++)) > maxlen)
 105                 return NULL;
 106         if (lenp)
 107                 *lenp = len;
 108         if ((len % 4) != 0) {
 109                 string = (char *) p;
 110         } else {
 111                 string = (char *) (p - 1);
 112                 memmove(string, p, len);
 113         }
 114         string[len] = '\0';
 115         *sp = string;
 116         return p + XDR_QUADLEN(len);
 117 }
 118
 119 u32 *
 120 xdr_decode_string_inplace(u32 *p, char **sp, int *lenp, int maxlen)
 121 {
 122         unsigned int    len;
 123
 124         if ((len = ntohl(*p++)) > maxlen)
 125                 return NULL;
 126         *lenp = len;
 127         *sp = (char *) p;
 128         return p + XDR_QUADLEN(len);
 129 }
 130
 131 void
 132 xdr_encode_pages(struct xdr_buf *xdr, struct page **pages, unsigned int base,
 133                  unsigned int len)
 134 {
 135         struct kvec *tail = xdr->tail;
 136         u32 *p;
 137
 138         xdr->pages = pages;
 139         xdr->page_base = base;
 140         xdr->page_len = len;
 141
 142         p = (u32 *)xdr->head[0].iov_base + XDR_QUADLEN(xdr->head[0].iov_len);
 143         tail->iov_base = p;
 144         tail->iov_len = 0;
 145
 146         if (len & 3) {
 147                 unsigned int pad = 4 - (len & 3);
 148
 149                 *p = 0;
 150                 tail->iov_base = (char *)p + (len & 3);
 151                 tail->iov_len  = pad;
 152                 len += pad;
 153         }
 154         xdr->buflen += len;
 155         xdr->len += len;
 156 }
 157
 158 void
 159 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
 160                  struct page **pages, unsigned int base, unsigned int len)
 161 {
 162         struct kvec *head = xdr->head;
 163         struct kvec *tail = xdr->tail;
 164         char *buf = (char *)head->iov_base;
 165         unsigned int buflen = head->iov_len;
 166
 167         head->iov_len  = offset;
 168
 169         xdr->pages = pages;
 170         xdr->page_base = base;
 171         xdr->page_len = len;
 172
 173         tail->iov_base = buf + offset;
 174         tail->iov_len = buflen - offset;
 175
 176         xdr->buflen += len;
 177 }
 178
 179 ssize_t
 180 xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base,
 181                           skb_reader_t *desc,
 182                           skb_read_actor_t copy_actor)
 183 {
 184         struct page     **ppage = xdr->pages;
 185         unsigned int    len, pglen = xdr->page_len;
 186         ssize_t         copied = 0;
 187         int             ret;
 188
 189         len = xdr->head[0].iov_len;
 190         if (base < len) {
 191                 len -= base;
 192                 ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
 193                 copied += ret;
 194                 if (ret != len || !desc->count)
 195                         goto out;
 196                 base = 0;
 197         } else
 198                 base -= len;
 199
 200         if (pglen == 0)
 201                 goto copy_tail;
 202         if (base >= pglen) {
 203                 base -= pglen;
 204                 goto copy_tail;
 205         }
 206         if (base || xdr->page_base) {
 207                 pglen -= base;
 208                 base  += xdr->page_base;
 209                 ppage += base >> PAGE_CACHE_SHIFT;
 210                 base &= ~PAGE_CACHE_MASK;
 211         }
 212         do {
 213                 char *kaddr;
 214
 215                 /* ACL likes to be lazy in allocating pages - ACLs
 216                  * are small by default but can get huge. */
 217                 if (unlikely(*ppage == NULL)) {
 218                         *ppage = alloc_page(GFP_ATOMIC);
 219                         if (unlikely(*ppage == NULL)) {
 220                                 if (copied == 0)
 221                                         copied = -ENOMEM;
 222                                 goto out;
 223                         }
 224                 }
 225
 226                 len = PAGE_CACHE_SIZE;
 227                 kaddr = kmap_atomic(*ppage, KM_SKB_SUNRPC_DATA);
 228                 if (base) {
 229                         len -= base;
 230                         if (pglen < len)
 231                                 len = pglen;
 232                         ret = copy_actor(desc, kaddr + base, len);
 233                         base = 0;
 234                 } else {
 235                         if (pglen < len)
 236                                 len = pglen;
 237                         ret = copy_actor(desc, kaddr, len);
 238                 }
 239                 flush_dcache_page(*ppage);
 240                 kunmap_atomic(kaddr, KM_SKB_SUNRPC_DATA);
 241                 copied += ret;
 242                 if (ret != len || !desc->count)
 243                         goto out;
 244                 ppage++;
 245         } while ((pglen -= len) != 0);
 246 copy_tail:
 247         len = xdr->tail[0].iov_len;
 248         if (base < len)
 249                 copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
 250 out:
 251         return copied;
 252 }
 253
 254
 255 int
 256 xdr_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen,
 257                 struct xdr_buf *xdr, unsigned int base, int msgflags)
 258 {
 259         struct page **ppage = xdr->pages;
 260         unsigned int len, pglen = xdr->page_len;
 261         int err, ret = 0;
 262         ssize_t (*sendpage)(struct socket *, struct page *, int, size_t, int);
 263
 264         len = xdr->head[0].iov_len;
 265         if (base < len || (addr != NULL && base == 0)) {
 266                 struct kvec iov = {
 267                         .iov_base = xdr->head[0].iov_base + base,
 268                         .iov_len  = len - base,
 269                 };
 270                 struct msghdr msg = {
 271                         .msg_name    = addr,
 272                         .msg_namelen = addrlen,
 273                         .msg_flags   = msgflags,
 274                 };
 275                 if (xdr->len > len)
 276                         msg.msg_flags |= MSG_MORE;
 277
 278                 if (iov.iov_len != 0)
 279                         err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
 280                 else
 281                         err = kernel_sendmsg(sock, &msg, NULL, 0, 0);
 282                 if (ret == 0)
 283                         ret = err;
 284                 else if (err > 0)
 285                         ret += err;
 286                 if (err != iov.iov_len)
 287                         goto out;
 288                 base = 0;
 289         } else
 290                 base -= len;
 291
 292         if (pglen == 0)
 293                 goto copy_tail;
 294         if (base >= pglen) {
 295                 base -= pglen;
 296                 goto copy_tail;
 297         }
 298         if (base || xdr->page_base) {
 299                 pglen -= base;
 300                 base  += xdr->page_base;
 301                 ppage += base >> PAGE_CACHE_SHIFT;
 302                 base &= ~PAGE_CACHE_MASK;
 303         }
 304
 305         sendpage = sock->ops->sendpage ? : sock_no_sendpage;
 306         do {
 307                 int flags = msgflags;
 308
 309                 len = PAGE_CACHE_SIZE;
 310                 if (base)
 311                         len -= base;
 312                 if (pglen < len)
 313                         len = pglen;
 314
 315                 if (pglen != len || xdr->tail[0].iov_len != 0)
 316                         flags |= MSG_MORE;
 317
 318                 /* Hmm... We might be dealing with highmem pages */
 319                 if (PageHighMem(*ppage))
 320                         sendpage = sock_no_sendpage;
 321                 err = sendpage(sock, *ppage, base, len, flags);
 322                 if (ret == 0)
 323                         ret = err;
 324                 else if (err > 0)
 325                         ret += err;
 326                 if (err != len)
 327                         goto out;
 328                 base = 0;
 329                 ppage++;
 330         } while ((pglen -= len) != 0);
 331 copy_tail:
 332         len = xdr->tail[0].iov_len;
 333         if (base < len) {
 334                 struct kvec iov = {
 335                         .iov_base = xdr->tail[0].iov_base + base,
 336                         .iov_len  = len - base,
 337                 };
 338                 struct msghdr msg = {
 339                         .msg_flags   = msgflags,
 340                 };
 341                 err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
 342                 if (ret == 0)
 343                         ret = err;
 344                 else if (err > 0)
 345                         ret += err;
 346         }
 347 out:
 348         return ret;
 349 }
 350
 351
 352 /*
 353  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
 354  *
 355  * _shift_data_right_pages
 356  * @pages: vector of pages containing both the source and dest memory area.
 357  * @pgto_base: page vector address of destination
 358  * @pgfrom_base: page vector address of source
 359  * @len: number of bytes to copy
 360  *
 361  * Note: the addresses pgto_base and pgfrom_base are both calculated in
 362  *       the same way:
 363  *            if a memory area starts at byte 'base' in page 'pages[i]',
 364  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
 365  * Also note: pgfrom_base must be < pgto_base, but the memory areas
 366  *      they point to may overlap.
 367  */
 368 static void
 369 _shift_data_right_pages(struct page **pages, size_t pgto_base,
 370                 size_t pgfrom_base, size_t len)
 371 {
 372         struct page **pgfrom, **pgto;
 373         char *vfrom, *vto;
 374         size_t copy;
 375
 376         BUG_ON(pgto_base <= pgfrom_base);
 377
 378         pgto_base += len;
 379         pgfrom_base += len;
 380
 381         pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
 382         pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);
 383
 384         pgto_base &= ~PAGE_CACHE_MASK;
 385         pgfrom_base &= ~PAGE_CACHE_MASK;
 386
 387         do {
 388                 /* Are any pointers crossing a page boundary? */
 389                 if (pgto_base == 0) {
 390                         flush_dcache_page(*pgto);
 391                         pgto_base = PAGE_CACHE_SIZE;
 392                         pgto--;
 393                 }
 394                 if (pgfrom_base == 0) {
 395                         pgfrom_base = PAGE_CACHE_SIZE;
 396                         pgfrom--;
 397                 }
 398
 399                 copy = len;
 400                 if (copy > pgto_base)
 401                         copy = pgto_base;
 402                 if (copy > pgfrom_base)
 403                         copy = pgfrom_base;
 404                 pgto_base -= copy;
 405                 pgfrom_base -= copy;
 406
 407                 vto = kmap_atomic(*pgto, KM_USER0);
 408                 vfrom = kmap_atomic(*pgfrom, KM_USER1);
 409                 memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
 410                 kunmap_atomic(vfrom, KM_USER1);
 411                 kunmap_atomic(vto, KM_USER0);
 412
 413         } while ((len -= copy) != 0);
 414         flush_dcache_page(*pgto);
 415 }
 416
 417 /*
 418  * _copy_to_pages
 419  * @pages: array of pages
 420  * @pgbase: page vector address of destination
 421  * @p: pointer to source data
 422  * @len: length
 423  *
 424  * Copies data from an arbitrary memory location into an array of pages
 425  * The copy is assumed to be non-overlapping.
 426  */
 427 static void
 428 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
 429 {
 430         struct page **pgto;
 431         char *vto;
 432         size_t copy;
 433
 434         pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
 435         pgbase &= ~PAGE_CACHE_MASK;
 436
 437         do {
 438                 copy = PAGE_CACHE_SIZE - pgbase;
 439                 if (copy > len)
 440                         copy = len;
 441
 442                 vto = kmap_atomic(*pgto, KM_USER0);
 443                 memcpy(vto + pgbase, p, copy);
 444                 kunmap_atomic(vto, KM_USER0);
 445
 446                 pgbase += copy;
 447                 if (pgbase == PAGE_CACHE_SIZE) {
 448                         flush_dcache_page(*pgto);
 449                         pgbase = 0;
 450                         pgto++;
 451                 }
 452                 p += copy;
 453
 454         } while ((len -= copy) != 0);
 455         flush_dcache_page(*pgto);
 456 }
 457
 458 /*
 459  * _copy_from_pages
 460  * @p: pointer to destination
 461  * @pages: array of pages
 462  * @pgbase: offset of source data
 463  * @len: length
 464  *
 465  * Copies data into an arbitrary memory location from an array of pages
 466  * The copy is assumed to be non-overlapping.
 467  */
 468 static void
 469 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
 470 {
 471         struct page **pgfrom;
 472         char *vfrom;
 473         size_t copy;
 474
 475         pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
 476         pgbase &= ~PAGE_CACHE_MASK;
 477
 478         do {
 479                 copy = PAGE_CACHE_SIZE - pgbase;
 480                 if (copy > len)
 481                         copy = len;
 482
 483                 vfrom = kmap_atomic(*pgfrom, KM_USER0);
 484                 memcpy(p, vfrom + pgbase, copy);
 485                 kunmap_atomic(vfrom, KM_USER0);
 486
 487                 pgbase += copy;
 488                 if (pgbase == PAGE_CACHE_SIZE) {
 489                         pgbase = 0;
 490                         pgfrom++;
 491                 }
 492                 p += copy;
 493
 494         } while ((len -= copy) != 0);
 495 }
 496
 497 /*
 498  * xdr_shrink_bufhead
 499  * @buf: xdr_buf
 500  * @len: bytes to remove from buf->head[0]
 501  *
 502  * Shrinks XDR buffer's header kvec buf->head[0] by
 503  * 'len' bytes. The extra data is not lost, but is instead
 504  * moved into the inlined pages and/or the tail.
 505  */
 506 static void
 507 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
 508 {
 509         struct kvec *head, *tail;
 510         size_t copy, offs;
 511         unsigned int pglen = buf->page_len;
 512
 513         tail = buf->tail;
 514         head = buf->head;
 515         BUG_ON (len > head->iov_len);
 516
 517         /* Shift the tail first */
 518         if (tail->iov_len != 0) {
 519                 if (tail->iov_len > len) {
 520                         copy = tail->iov_len - len;
 521                         memmove((char *)tail->iov_base + len,
 522                                         tail->iov_base, copy);
 523                 }
 524                 /* Copy from the inlined pages into the tail */
 525                 copy = len;
 526                 if (copy > pglen)
 527                         copy = pglen;
 528                 offs = len - copy;
 529                 if (offs >= tail->iov_len)
 530                         copy = 0;
 531                 else if (copy > tail->iov_len - offs)
 532                         copy = tail->iov_len - offs;
 533                 if (copy != 0)
 534                         _copy_from_pages((char *)tail->iov_base + offs,
 535                                         buf->pages,
 536                                         buf->page_base + pglen + offs - len,
 537                                         copy);
 538                 /* Do we also need to copy data from the head into the tail ? */
 539                 if (len > pglen) {
 540                         offs = copy = len - pglen;
 541                         if (copy > tail->iov_len)
 542                                 copy = tail->iov_len;
 543                         memcpy(tail->iov_base,
 544                                         (char *)head->iov_base +
 545                                         head->iov_len - offs,
 546                                         copy);
 547                 }
 548         }
 549         /* Now handle pages */
 550         if (pglen != 0) {
 551                 if (pglen > len)
 552                         _shift_data_right_pages(buf->pages,
 553                                         buf->page_base + len,
 554                                         buf->page_base,
 555                                         pglen - len);
 556                 copy = len;
 557                 if (len > pglen)
 558                         copy = pglen;
 559                 _copy_to_pages(buf->pages, buf->page_base,
 560                                 (char *)head->iov_base + head->iov_len - len,
 561                                 copy);
 562         }
 563         head->iov_len -= len;
 564         buf->buflen -= len;
 565         /* Have we truncated the message? */
 566         if (buf->len > buf->buflen)
 567                 buf->len = buf->buflen;
 568 }
 569
 570 /*
 571  * xdr_shrink_pagelen
 572  * @buf: xdr_buf
 573  * @len: bytes to remove from buf->pages
 574  *
 575  * Shrinks XDR buffer's page array buf->pages by
 576  * 'len' bytes. The extra data is not lost, but is instead
 577  * moved into the tail.
 578  */
 579 static void
 580 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
 581 {
 582         struct kvec *tail;
 583         size_t copy;
 584         char *p;
 585         unsigned int pglen = buf->page_len;
 586
 587         tail = buf->tail;
 588         BUG_ON (len > pglen);
 589
 590         /* Shift the tail first */
 591         if (tail->iov_len != 0) {
 592                 p = (char *)tail->iov_base + len;
 593                 if (tail->iov_len > len) {
 594                         copy = tail->iov_len - len;
 595                         memmove(p, tail->iov_base, copy);
 596                 } else
 597                         buf->buflen -= len;
 598                 /* Copy from the inlined pages into the tail */
 599                 copy = len;
 600                 if (copy > tail->iov_len)
 601                         copy = tail->iov_len;
 602                 _copy_from_pages((char *)tail->iov_base,
 603                                 buf->pages, buf->page_base + pglen - len,
 604                                 copy);
 605         }
 606         buf->page_len -= len;
 607         buf->buflen -= len;
 608         /* Have we truncated the message? */
 609         if (buf->len > buf->buflen)
 610                 buf->len = buf->buflen;
 611 }
 612
 613 void
 614 xdr_shift_buf(struct xdr_buf *buf, size_t len)
 615 {
 616         xdr_shrink_bufhead(buf, len);
 617 }
 618
 619 /**
 620  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
 621  * @xdr: pointer to xdr_stream struct
 622  * @buf: pointer to XDR buffer in which to encode data
 623  * @p: current pointer inside XDR buffer
 624  *
 625  * Note: at the moment the RPC client only passes the length of our
 626  *       scratch buffer in the xdr_buf's header kvec. Previously this
 627  *       meant we needed to call xdr_adjust_iovec() after encoding the
 628  *       data. With the new scheme, the xdr_stream manages the details
 629  *       of the buffer length, and takes care of adjusting the kvec
 630  *       length for us.
 631  */
 632 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
 633 {
 634         struct kvec *iov = buf->head;
 635         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
 636
 637         BUG_ON(scratch_len < 0);
 638         xdr->buf = buf;
 639         xdr->iov = iov;
 640         xdr->p = (uint32_t *)((char *)iov->iov_base + iov->iov_len);
 641         xdr->end = (uint32_t *)((char *)iov->iov_base + scratch_len);
 642         BUG_ON(iov->iov_len > scratch_len);
 643
 644         if (p != xdr->p && p != NULL) {
 645                 size_t len;
 646
 647                 BUG_ON(p < xdr->p || p > xdr->end);
 648                 len = (char *)p - (char *)xdr->p;
 649                 xdr->p = p;
 650                 buf->len += len;
 651                 iov->iov_len += len;
 652         }
 653 }
 654 EXPORT_SYMBOL(xdr_init_encode);
 655
 656 /**
 657  * xdr_reserve_space - Reserve buffer space for sending
 658  * @xdr: pointer to xdr_stream
 659  * @nbytes: number of bytes to reserve
 660  *
 661  * Checks that we have enough buffer space to encode 'nbytes' more
 662  * bytes of data. If so, update the total xdr_buf length, and
 663  * adjust the length of the current kvec.
 664  */
 665 uint32_t * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
 666 {
 667         uint32_t *p = xdr->p;
 668         uint32_t *q;
 669
 670         /* align nbytes on the next 32-bit boundary */
 671         nbytes += 3;
 672         nbytes &= ~3;
 673         q = p + (nbytes >> 2);
 674         if (unlikely(q > xdr->end || q < p))
 675                 return NULL;
 676         xdr->p = q;
 677         xdr->iov->iov_len += nbytes;
 678         xdr->buf->len += nbytes;
 679         return p;
 680 }
 681 EXPORT_SYMBOL(xdr_reserve_space);
 682
 683 /**
 684  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
 685  * @xdr: pointer to xdr_stream
 686  * @pages: list of pages
 687  * @base: offset of first byte
 688  * @len: length of data in bytes
 689  *
 690  */
 691 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
 692                  unsigned int len)
 693 {
 694         struct xdr_buf *buf = xdr->buf;
 695         struct kvec *iov = buf->tail;
 696         buf->pages = pages;
 697         buf->page_base = base;
 698         buf->page_len = len;
 699
 700         iov->iov_base = (char *)xdr->p;
 701         iov->iov_len  = 0;
 702         xdr->iov = iov;
 703
 704         if (len & 3) {
 705                 unsigned int pad = 4 - (len & 3);
 706
 707                 BUG_ON(xdr->p >= xdr->end);
 708                 iov->iov_base = (char *)xdr->p + (len & 3);
 709                 iov->iov_len  += pad;
 710                 len += pad;
 711                 *xdr->p++ = 0;
 712         }
 713         buf->buflen += len;
 714         buf->len += len;
 715 }
 716 EXPORT_SYMBOL(xdr_write_pages);
 717
 718 /**
 719  * xdr_init_decode - Initialize an xdr_stream for decoding data.
 720  * @xdr: pointer to xdr_stream struct
 721  * @buf: pointer to XDR buffer from which to decode data
 722  * @p: current pointer inside XDR buffer
 723  */
 724 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
 725 {
 726         struct kvec *iov = buf->head;
 727         unsigned int len = iov->iov_len;
 728
 729         if (len > buf->len)
 730                 len = buf->len;
 731         xdr->buf = buf;
 732         xdr->iov = iov;
 733         xdr->p = p;
 734         xdr->end = (uint32_t *)((char *)iov->iov_base + len);
 735 }
 736 EXPORT_SYMBOL(xdr_init_decode);
 737
 738 /**
 739  * xdr_inline_decode - Retrieve non-page XDR data to decode
 740  * @xdr: pointer to xdr_stream struct
 741  * @nbytes: number of bytes of data to decode
 742  *
 743  * Check if the input buffer is long enough to enable us to decode
 744  * 'nbytes' more bytes of data starting at the current position.
 745  * If so return the current pointer, then update the current
 746  * pointer position.
 747  */
 748 uint32_t * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 749 {
 750         uint32_t *p = xdr->p;
 751         uint32_t *q = p + XDR_QUADLEN(nbytes);
 752
 753         if (unlikely(q > xdr->end || q < p))
 754                 return NULL;
 755         xdr->p = q;
 756         return p;
 757 }
 758 EXPORT_SYMBOL(xdr_inline_decode);
 759
 760 /**
 761  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
 762  * @xdr: pointer to xdr_stream struct
 763  * @len: number of bytes of page data
 764  *
 765  * Moves data beyond the current pointer position from the XDR head[] buffer
 766  * into the page list. Any data that lies beyond current position + "len"
 767  * bytes is moved into the XDR tail[]. The current pointer is then
 768  * repositioned at the beginning of the XDR tail.
 769  */
 770 void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
 771 {
 772         struct xdr_buf *buf = xdr->buf;
 773         struct kvec *iov;
 774         ssize_t shift;
 775         unsigned int end;
 776         int padding;
 777
 778         /* Realign pages to current pointer position */
 779         iov  = buf->head;
 780         shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
 781         if (shift > 0)
 782                 xdr_shrink_bufhead(buf, shift);
 783
 784         /* Truncate page data and move it into the tail */
 785         if (buf->page_len > len)
 786                 xdr_shrink_pagelen(buf, buf->page_len - len);
 787         padding = (XDR_QUADLEN(len) << 2) - len;
 788         xdr->iov = iov = buf->tail;
 789         /* Compute remaining message length.  */
 790         end = iov->iov_len;
 791         shift = buf->buflen - buf->len;
 792         if (shift < end)
 793                 end -= shift;
 794         else if (shift > 0)
 795                 end = 0;
 796         /*
 797          * Position current pointer at beginning of tail, and
 798          * set remaining message length.
 799          */
 800         xdr->p = (uint32_t *)((char *)iov->iov_base + padding);
 801         xdr->end = (uint32_t *)((char *)iov->iov_base + end);
 802 }
 803 EXPORT_SYMBOL(xdr_read_pages);
 804
 805 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
 806
 807 void
 808 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
 809 {
 810         buf->head[0] = *iov;
 811         buf->tail[0] = empty_iov;
 812         buf->page_len = 0;
 813         buf->buflen = buf->len = iov->iov_len;
 814 }
 815
 816 /* Sets subiov to the intersection of iov with the buffer of length len
 817  * starting base bytes after iov.  Indicates empty intersection by setting
 818  * length of subiov to zero.  Decrements len by length of subiov, sets base
 819  * to zero (or decrements it by length of iov if subiov is empty). */
 820 static void
 821 iov_subsegment(struct kvec *iov, struct kvec *subiov, int *base, int *len)
 822 {
 823         if (*base > iov->iov_len) {
 824                 subiov->iov_base = NULL;
 825                 subiov->iov_len = 0;
 826                 *base -= iov->iov_len;
 827         } else {
 828                 subiov->iov_base = iov->iov_base + *base;
 829                 subiov->iov_len = min(*len, (int)iov->iov_len - *base);
 830                 *base = 0;
 831         }
 832         *len -= subiov->iov_len;
 833 }
 834
 835 /* Sets subbuf to the portion of buf of length len beginning base bytes
 836  * from the start of buf. Returns -1 if base of length are out of bounds. */
 837 int
 838 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
 839                         int base, int len)
 840 {
 841         int i;
 842
 843         subbuf->buflen = subbuf->len = len;
 844         iov_subsegment(buf->head, subbuf->head, &base, &len);
 845
 846         if (base < buf->page_len) {
 847                 i = (base + buf->page_base) >> PAGE_CACHE_SHIFT;
 848                 subbuf->pages = &buf->pages[i];
 849                 subbuf->page_base = (base + buf->page_base) & ~PAGE_CACHE_MASK;
 850                 subbuf->page_len = min((int)buf->page_len - base, len);
 851                 len -= subbuf->page_len;
 852                 base = 0;
 853         } else {
 854                 base -= buf->page_len;
 855                 subbuf->page_len = 0;
 856         }
 857
 858         iov_subsegment(buf->tail, subbuf->tail, &base, &len);
 859         if (base || len)
 860                 return -1;
 861         return 0;
 862 }
 863
 864 /* obj is assumed to point to allocated memory of size at least len: */
 865 int
 866 read_bytes_from_xdr_buf(struct xdr_buf *buf, int base, void *obj, int len)
 867 {
 868         struct xdr_buf subbuf;
 869         int this_len;
 870         int status;
 871
 872         status = xdr_buf_subsegment(buf, &subbuf, base, len);
 873         if (status)
 874                 goto out;
 875         this_len = min(len, (int)subbuf.head[0].iov_len);
 876         memcpy(obj, subbuf.head[0].iov_base, this_len);
 877         len -= this_len;
 878         obj += this_len;
 879         this_len = min(len, (int)subbuf.page_len);
 880         if (this_len)
 881                 _copy_from_pages(obj, subbuf.pages, subbuf.page_base, this_len);
 882         len -= this_len;
 883         obj += this_len;
 884         this_len = min(len, (int)subbuf.tail[0].iov_len);
 885         memcpy(obj, subbuf.tail[0].iov_base, this_len);
 886 out:
 887         return status;
 888 }
 889
 890 /* obj is assumed to point to allocated memory of size at least len: */
 891 int
 892 write_bytes_to_xdr_buf(struct xdr_buf *buf, int base, void *obj, int len)
 893 {
 894         struct xdr_buf subbuf;
 895         int this_len;
 896         int status;
 897
 898         status = xdr_buf_subsegment(buf, &subbuf, base, len);
 899         if (status)
 900                 goto out;
 901         this_len = min(len, (int)subbuf.head[0].iov_len);
 902         memcpy(subbuf.head[0].iov_base, obj, this_len);
 903         len -= this_len;
 904         obj += this_len;
 905         this_len = min(len, (int)subbuf.page_len);
 906         if (this_len)
 907                 _copy_to_pages(subbuf.pages, subbuf.page_base, obj, this_len);
 908         len -= this_len;
 909         obj += this_len;
 910         this_len = min(len, (int)subbuf.tail[0].iov_len);
 911         memcpy(subbuf.tail[0].iov_base, obj, this_len);
 912 out:
 913         return status;
 914 }
 915
 916 int
 917 xdr_decode_word(struct xdr_buf *buf, int base, u32 *obj)
 918 {
 919         u32     raw;
 920         int     status;
 921
 922         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
 923         if (status)
 924                 return status;
 925         *obj = ntohl(raw);
 926         return 0;
 927 }
 928
 929 int
 930 xdr_encode_word(struct xdr_buf *buf, int base, u32 obj)
 931 {
 932         u32     raw = htonl(obj);
 933
 934         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
 935 }
 936
 937 /* If the netobj starting offset bytes from the start of xdr_buf is contained
 938  * entirely in the head or the tail, set object to point to it; otherwise
 939  * try to find space for it at the end of the tail, copy it there, and
 940  * set obj to point to it. */
 941 int
 942 xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, int offset)
 943 {
 944         u32     tail_offset = buf->head[0].iov_len + buf->page_len;
 945         u32     obj_end_offset;
 946
 947         if (xdr_decode_word(buf, offset, &obj->len))
 948                 goto out;
 949         obj_end_offset = offset + 4 + obj->len;
 950
 951         if (obj_end_offset <= buf->head[0].iov_len) {
 952                 /* The obj is contained entirely in the head: */
 953                 obj->data = buf->head[0].iov_base + offset + 4;
 954         } else if (offset + 4 >= tail_offset) {
 955                 if (obj_end_offset - tail_offset
 956                                 > buf->tail[0].iov_len)
 957                         goto out;
 958                 /* The obj is contained entirely in the tail: */
 959                 obj->data = buf->tail[0].iov_base
 960                         + offset - tail_offset + 4;
 961         } else {
 962                 /* use end of tail as storage for obj:
 963                  * (We don't copy to the beginning because then we'd have
 964                  * to worry about doing a potentially overlapping copy.
 965                  * This assumes the object is at most half the length of the
 966                  * tail.) */
 967                 if (obj->len > buf->tail[0].iov_len)
 968                         goto out;
 969                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len -
 970                                 obj->len;
 971                 if (read_bytes_from_xdr_buf(buf, offset + 4,
 972                                         obj->data, obj->len))
 973                         goto out;
 974
 975         }
 976         return 0;
 977 out:
 978         return -1;
 979 }
 980
 981 /* Returns 0 on success, or else a negative error code. */
 982 static int
 983 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
 984                  struct xdr_array2_desc *desc, int encode)
 985 {
 986         char *elem = NULL, *c;
 987         unsigned int copied = 0, todo, avail_here;
 988         struct page **ppages = NULL;
 989         int err;
 990
 991         if (encode) {
 992                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
 993                         return -EINVAL;
 994         } else {
 995                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
 996                     desc->array_len > desc->array_maxlen ||
 997                     (unsigned long) base + 4 + desc->array_len *
 998                                     desc->elem_size > buf->len)
 999                         return -EINVAL;
1000         }
1001         base += 4;
1002
1003         if (!desc->xcode)
1004                 return 0;
1005
1006         todo = desc->array_len * desc->elem_size;
1007
1008         /* process head */
1009         if (todo && base < buf->head->iov_len) {
1010                 c = buf->head->iov_base + base;
1011                 avail_here = min_t(unsigned int, todo,
1012                                    buf->head->iov_len - base);
1013                 todo -= avail_here;
1014
1015                 while (avail_here >= desc->elem_size) {
1016                         err = desc->xcode(desc, c);
1017                         if (err)
1018                                 goto out;
1019                         c += desc->elem_size;
1020                         avail_here -= desc->elem_size;
1021                 }
1022                 if (avail_here) {
1023                         if (!elem) {
1024                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
1025                                 err = -ENOMEM;
1026                                 if (!elem)
1027                                         goto out;
1028                         }
1029                         if (encode) {
1030                                 err = desc->xcode(desc, elem);
1031                                 if (err)
1032                                         goto out;
1033                                 memcpy(c, elem, avail_here);
1034                         } else
1035                                 memcpy(elem, c, avail_here);
1036                         copied = avail_here;
1037                 }
1038                 base = buf->head->iov_len;  /* align to start of pages */
1039         }
1040
1041         /* process pages array */
1042         base -= buf->head->iov_len;
1043         if (todo && base < buf->page_len) {
1044                 unsigned int avail_page;
1045
1046                 avail_here = min(todo, buf->page_len - base);
1047                 todo -= avail_here;
1048
1049                 base += buf->page_base;
1050                 ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
1051                 base &= ~PAGE_CACHE_MASK;
1052                 avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
1053                                         avail_here);
1054                 c = kmap(*ppages) + base;
1055
1056                 while (avail_here) {
1057                         avail_here -= avail_page;
1058                         if (copied || avail_page < desc->elem_size) {
1059                                 unsigned int l = min(avail_page,
1060                                         desc->elem_size - copied);
1061                                 if (!elem) {
1062                                         elem = kmalloc(desc->elem_size,
1063                                                        GFP_KERNEL);
1064                                         err = -ENOMEM;
1065                                         if (!elem)
1066                                                 goto out;
1067                                 }
1068                                 if (encode) {
1069                                         if (!copied) {
1070                                                 err = desc->xcode(desc, elem);
1071                                                 if (err)
1072                                                         goto out;
1073                                         }
1074                                         memcpy(c, elem + copied, l);
1075                                         copied += l;
1076                                         if (copied == desc->elem_size)
1077                                                 copied = 0;
1078                                 } else {
1079                                         memcpy(elem + copied, c, l);
1080                                         copied += l;
1081                                         if (copied == desc->elem_size) {
1082                                                 err = desc->xcode(desc, elem);
1083                                                 if (err)
1084                                                         goto out;
1085                                                 copied = 0;
1086                                         }
1087                                 }
1088                                 avail_page -= l;
1089                                 c += l;
1090                         }
1091                         while (avail_page >= desc->elem_size) {
1092                                 err = desc->xcode(desc, c);
1093                                 if (err)
1094                                         goto out;
1095                                 c += desc->elem_size;
1096                                 avail_page -= desc->elem_size;
1097                         }
1098                         if (avail_page) {
1099                                 unsigned int l = min(avail_page,
1100                                             desc->elem_size - copied);
1101                                 if (!elem) {
1102                                         elem = kmalloc(desc->elem_size,
1103                                                        GFP_KERNEL);
1104                                         err = -ENOMEM;
1105                                         if (!elem)
1106                                                 goto out;
1107                                 }
1108                                 if (encode) {
1109                                         if (!copied) {
1110                                                 err = desc->xcode(desc, elem);
1111                                                 if (err)
1112                                                         goto out;
1113                                         }
1114                                         memcpy(c, elem + copied, l);
1115                                         copied += l;
1116                                         if (copied == desc->elem_size)
1117                                                 copied = 0;
1118                                 } else {
1119                                         memcpy(elem + copied, c, l);
1120                                         copied += l;
1121                                         if (copied == desc->elem_size) {
1122                                                 err = desc->xcode(desc, elem);
1123                                                 if (err)
1124                                                         goto out;
1125                                                 copied = 0;
1126                                         }
1127                                 }
1128                         }
1129                         if (avail_here) {
1130                                 kunmap(*ppages);
1131                                 ppages++;
1132                                 c = kmap(*ppages);
1133                         }
1134
1135                         avail_page = min(avail_here,
1136                                  (unsigned int) PAGE_CACHE_SIZE);
1137                 }
1138                 base = buf->page_len;  /* align to start of tail */
1139         }
1140
1141         /* process tail */
1142         base -= buf->page_len;
1143         if (todo) {
1144                 c = buf->tail->iov_base + base;
1145                 if (copied) {
1146                         unsigned int l = desc->elem_size - copied;
1147
1148                         if (encode)
1149                                 memcpy(c, elem + copied, l);
1150                         else {
1151                                 memcpy(elem + copied, c, l);
1152                                 err = desc->xcode(desc, elem);
1153                                 if (err)
1154                                         goto out;
1155                         }
1156                         todo -= l;
1157                         c += l;
1158                 }
1159                 while (todo) {
1160                         err = desc->xcode(desc, c);
1161                         if (err)
1162                                 goto out;
1163                         c += desc->elem_size;
1164                         todo -= desc->elem_size;
1165                 }
1166         }
1167         err = 0;
1168
1169 out:
1170         if (elem)
1171                 kfree(elem);
1172         if (ppages)
1173                 kunmap(*ppages);
1174         return err;
1175 }
1176
1177 int
1178 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1179                   struct xdr_array2_desc *desc)
1180 {
1181         if (base >= buf->len)
1182                 return -EINVAL;
1183
1184         return xdr_xcode_array2(buf, base, desc, 0);
1185 }
1186
1187 int
1188 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1189                   struct xdr_array2_desc *desc)
1190 {
1191         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1192             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1193                 return -EINVAL;
1194
1195         return xdr_xcode_array2(buf, base, desc, 1);
1196 }