Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/lib/iov_iter.c

  1 #include <linux/export.h>
  2 #include <linux/bvec.h>
  3 #include <linux/uio.h>
  4 #include <linux/pagemap.h>
  5 #include <linux/slab.h>
  6 #include <linux/vmalloc.h>
  7 #include <linux/splice.h>
  8 #include <net/checksum.h>
  9 
 10 #define PIPE_PARANOIA /* for now */
 11 
 12 #define iterate_iovec(i, n, __v, __p, skip, STEP) {     \
 13         size_t left;                                    \
 14         size_t wanted = n;                              \
 15         __p = i->iov;                                   \
 16         __v.iov_len = min(n, __p->iov_len - skip);      \
 17         if (likely(__v.iov_len)) {                      \
 18                 __v.iov_base = __p->iov_base + skip;    \
 19                 left = (STEP);                          \
 20                 __v.iov_len -= left;                    \
 21                 skip += __v.iov_len;                    \
 22                 n -= __v.iov_len;                       \
 23         } else {                                        \
 24                 left = 0;                               \
 25         }                                               \
 26         while (unlikely(!left && n)) {                  \
 27                 __p++;                                  \
 28                 __v.iov_len = min(n, __p->iov_len);     \
 29                 if (unlikely(!__v.iov_len))             \
 30                         continue;                       \
 31                 __v.iov_base = __p->iov_base;           \
 32                 left = (STEP);                          \
 33                 __v.iov_len -= left;                    \
 34                 skip = __v.iov_len;                     \
 35                 n -= __v.iov_len;                       \
 36         }                                               \
 37         n = wanted - n;                                 \
 38 }
 39 
 40 #define iterate_kvec(i, n, __v, __p, skip, STEP) {      \
 41         size_t wanted = n;                              \
 42         __p = i->kvec;                                  \
 43         __v.iov_len = min(n, __p->iov_len - skip);      \
 44         if (likely(__v.iov_len)) {                      \
 45                 __v.iov_base = __p->iov_base + skip;    \
 46                 (void)(STEP);                           \
 47                 skip += __v.iov_len;                    \
 48                 n -= __v.iov_len;                       \
 49         }                                               \
 50         while (unlikely(n)) {                           \
 51                 __p++;                                  \
 52                 __v.iov_len = min(n, __p->iov_len);     \
 53                 if (unlikely(!__v.iov_len))             \
 54                         continue;                       \
 55                 __v.iov_base = __p->iov_base;           \
 56                 (void)(STEP);                           \
 57                 skip = __v.iov_len;                     \
 58                 n -= __v.iov_len;                       \
 59         }                                               \
 60         n = wanted;                                     \
 61 }
 62 
 63 #define iterate_bvec(i, n, __v, __bi, skip, STEP) {     \
 64         struct bvec_iter __start;                       \
 65         __start.bi_size = n;                            \
 66         __start.bi_bvec_done = skip;                    \
 67         __start.bi_idx = 0;                             \
 68         for_each_bvec(__v, i->bvec, __bi, __start) {    \
 69                 if (!__v.bv_len)                        \
 70                         continue;                       \
 71                 (void)(STEP);                           \
 72         }                                               \
 73 }
 74 
 75 #define iterate_all_kinds(i, n, v, I, B, K) {                   \
 76         if (likely(n)) {                                        \
 77                 size_t skip = i->iov_offset;                    \
 78                 if (unlikely(i->type & ITER_BVEC)) {            \
 79                         struct bio_vec v;                       \
 80                         struct bvec_iter __bi;                  \
 81                         iterate_bvec(i, n, v, __bi, skip, (B))  \
 82                 } else if (unlikely(i->type & ITER_KVEC)) {     \
 83                         const struct kvec *kvec;                \
 84                         struct kvec v;                          \
 85                         iterate_kvec(i, n, v, kvec, skip, (K))  \
 86                 } else {                                        \
 87                         const struct iovec *iov;                \
 88                         struct iovec v;                         \
 89                         iterate_iovec(i, n, v, iov, skip, (I))  \
 90                 }                                               \
 91         }                                                       \
 92 }
 93 
 94 #define iterate_and_advance(i, n, v, I, B, K) {                 \
 95         if (unlikely(i->count < n))                             \
 96                 n = i->count;                                   \
 97         if (i->count) {                                         \
 98                 size_t skip = i->iov_offset;                    \
 99                 if (unlikely(i->type & ITER_BVEC)) {            \
100                         const struct bio_vec *bvec = i->bvec;   \
101                         struct bio_vec v;                       \
102                         struct bvec_iter __bi;                  \
103                         iterate_bvec(i, n, v, __bi, skip, (B))  \
104                         i->bvec = __bvec_iter_bvec(i->bvec, __bi);      \
105                         i->nr_segs -= i->bvec - bvec;           \
106                         skip = __bi.bi_bvec_done;               \
107                 } else if (unlikely(i->type & ITER_KVEC)) {     \
108                         const struct kvec *kvec;                \
109                         struct kvec v;                          \
110                         iterate_kvec(i, n, v, kvec, skip, (K))  \
111                         if (skip == kvec->iov_len) {            \
112                                 kvec++;                         \
113                                 skip = 0;                       \
114                         }                                       \
115                         i->nr_segs -= kvec - i->kvec;           \
116                         i->kvec = kvec;                         \
117                 } else {                                        \
118                         const struct iovec *iov;                \
119                         struct iovec v;                         \
120                         iterate_iovec(i, n, v, iov, skip, (I))  \
121                         if (skip == iov->iov_len) {             \
122                                 iov++;                          \
123                                 skip = 0;                       \
124                         }                                       \
125                         i->nr_segs -= iov - i->iov;             \
126                         i->iov = iov;                           \
127                 }                                               \
128                 i->count -= n;                                  \
129                 i->iov_offset = skip;                           \
130         }                                                       \
131 }
132 
133 static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
134                          struct iov_iter *i)
135 {
136         size_t skip, copy, left, wanted;
137         const struct iovec *iov;
138         char __user *buf;
139         void *kaddr, *from;
140 
141         if (unlikely(bytes > i->count))
142                 bytes = i->count;
143 
144         if (unlikely(!bytes))
145                 return 0;
146 
147         wanted = bytes;
148         iov = i->iov;
149         skip = i->iov_offset;
150         buf = iov->iov_base + skip;
151         copy = min(bytes, iov->iov_len - skip);
152 
153         if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) {
154                 kaddr = kmap_atomic(page);
155                 from = kaddr + offset;
156 
157                 /* first chunk, usually the only one */
158                 left = __copy_to_user_inatomic(buf, from, copy);
159                 copy -= left;
160                 skip += copy;
161                 from += copy;
162                 bytes -= copy;
163 
164                 while (unlikely(!left && bytes)) {
165                         iov++;
166                         buf = iov->iov_base;
167                         copy = min(bytes, iov->iov_len);
168                         left = __copy_to_user_inatomic(buf, from, copy);
169                         copy -= left;
170                         skip = copy;
171                         from += copy;
172                         bytes -= copy;
173                 }
174                 if (likely(!bytes)) {
175                         kunmap_atomic(kaddr);
176                         goto done;
177                 }
178                 offset = from - kaddr;
179                 buf += copy;
180                 kunmap_atomic(kaddr);
181                 copy = min(bytes, iov->iov_len - skip);
182         }
183         /* Too bad - revert to non-atomic kmap */
184 
185         kaddr = kmap(page);
186         from = kaddr + offset;
187         left = __copy_to_user(buf, from, copy);
188         copy -= left;
189         skip += copy;
190         from += copy;
191         bytes -= copy;
192         while (unlikely(!left && bytes)) {
193                 iov++;
194                 buf = iov->iov_base;
195                 copy = min(bytes, iov->iov_len);
196                 left = __copy_to_user(buf, from, copy);
197                 copy -= left;
198                 skip = copy;
199                 from += copy;
200                 bytes -= copy;
201         }
202         kunmap(page);
203 
204 done:
205         if (skip == iov->iov_len) {
206                 iov++;
207                 skip = 0;
208         }
209         i->count -= wanted - bytes;
210         i->nr_segs -= iov - i->iov;
211         i->iov = iov;
212         i->iov_offset = skip;
213         return wanted - bytes;
214 }
215 
216 static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
217                          struct iov_iter *i)
218 {
219         size_t skip, copy, left, wanted;
220         const struct iovec *iov;
221         char __user *buf;
222         void *kaddr, *to;
223 
224         if (unlikely(bytes > i->count))
225                 bytes = i->count;
226 
227         if (unlikely(!bytes))
228                 return 0;
229 
230         wanted = bytes;
231         iov = i->iov;
232         skip = i->iov_offset;
233         buf = iov->iov_base + skip;
234         copy = min(bytes, iov->iov_len - skip);
235 
236         if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) {
237                 kaddr = kmap_atomic(page);
238                 to = kaddr + offset;
239 
240                 /* first chunk, usually the only one */
241                 left = __copy_from_user_inatomic(to, buf, copy);
242                 copy -= left;
243                 skip += copy;
244                 to += copy;
245                 bytes -= copy;
246 
247                 while (unlikely(!left && bytes)) {
248                         iov++;
249                         buf = iov->iov_base;
250                         copy = min(bytes, iov->iov_len);
251                         left = __copy_from_user_inatomic(to, buf, copy);
252                         copy -= left;
253                         skip = copy;
254                         to += copy;
255                         bytes -= copy;
256                 }
257                 if (likely(!bytes)) {
258                         kunmap_atomic(kaddr);
259                         goto done;
260                 }
261                 offset = to - kaddr;
262                 buf += copy;
263                 kunmap_atomic(kaddr);
264                 copy = min(bytes, iov->iov_len - skip);
265         }
266         /* Too bad - revert to non-atomic kmap */
267 
268         kaddr = kmap(page);
269         to = kaddr + offset;
270         left = __copy_from_user(to, buf, copy);
271         copy -= left;
272         skip += copy;
273         to += copy;
274         bytes -= copy;
275         while (unlikely(!left && bytes)) {
276                 iov++;
277                 buf = iov->iov_base;
278                 copy = min(bytes, iov->iov_len);
279                 left = __copy_from_user(to, buf, copy);
280                 copy -= left;
281                 skip = copy;
282                 to += copy;
283                 bytes -= copy;
284         }
285         kunmap(page);
286 
287 done:
288         if (skip == iov->iov_len) {
289                 iov++;
290                 skip = 0;
291         }
292         i->count -= wanted - bytes;
293         i->nr_segs -= iov - i->iov;
294         i->iov = iov;
295         i->iov_offset = skip;
296         return wanted - bytes;
297 }
298 
299 #ifdef PIPE_PARANOIA
300 static bool sanity(const struct iov_iter *i)
301 {
302         struct pipe_inode_info *pipe = i->pipe;
303         int idx = i->idx;
304         int next = pipe->curbuf + pipe->nrbufs;
305         if (i->iov_offset) {
306                 struct pipe_buffer *p;
307                 if (unlikely(!pipe->nrbufs))
308                         goto Bad;       // pipe must be non-empty
309                 if (unlikely(idx != ((next - 1) & (pipe->buffers - 1))))
310                         goto Bad;       // must be at the last buffer...
311 
312                 p = &pipe->bufs[idx];
313                 if (unlikely(p->offset + p->len != i->iov_offset))
314                         goto Bad;       // ... at the end of segment
315         } else {
316                 if (idx != (next & (pipe->buffers - 1)))
317                         goto Bad;       // must be right after the last buffer
318         }
319         return true;
320 Bad:
321         printk(KERN_ERR "idx = %d, offset = %zd\n", i->idx, i->iov_offset);
322         printk(KERN_ERR "curbuf = %d, nrbufs = %d, buffers = %d\n",
323                         pipe->curbuf, pipe->nrbufs, pipe->buffers);
324         for (idx = 0; idx < pipe->buffers; idx++)
325                 printk(KERN_ERR "[%p %p %d %d]\n",
326                         pipe->bufs[idx].ops,
327                         pipe->bufs[idx].page,
328                         pipe->bufs[idx].offset,
329                         pipe->bufs[idx].len);
330         WARN_ON(1);
331         return false;
332 }
333 #else
334 #define sanity(i) true
335 #endif
336 
337 static inline int next_idx(int idx, struct pipe_inode_info *pipe)
338 {
339         return (idx + 1) & (pipe->buffers - 1);
340 }
341 
342 static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
343                          struct iov_iter *i)
344 {
345         struct pipe_inode_info *pipe = i->pipe;
346         struct pipe_buffer *buf;
347         size_t off;
348         int idx;
349 
350         if (unlikely(bytes > i->count))
351                 bytes = i->count;
352 
353         if (unlikely(!bytes))
354                 return 0;
355 
356         if (!sanity(i))
357                 return 0;
358 
359         off = i->iov_offset;
360         idx = i->idx;
361         buf = &pipe->bufs[idx];
362         if (off) {
363                 if (offset == off && buf->page == page) {
364                         /* merge with the last one */
365                         buf->len += bytes;
366                         i->iov_offset += bytes;
367                         goto out;
368                 }
369                 idx = next_idx(idx, pipe);
370                 buf = &pipe->bufs[idx];
371         }
372         if (idx == pipe->curbuf && pipe->nrbufs)
373                 return 0;
374         pipe->nrbufs++;
375         buf->ops = &page_cache_pipe_buf_ops;
376         get_page(buf->page = page);
377         buf->offset = offset;
378         buf->len = bytes;
379         i->iov_offset = offset + bytes;
380         i->idx = idx;
381 out:
382         i->count -= bytes;
383         return bytes;
384 }
385 
386 /*
387  * Fault in one or more iovecs of the given iov_iter, to a maximum length of
388  * bytes.  For each iovec, fault in each page that constitutes the iovec.
389  *
390  * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
391  * because it is an invalid address).
392  */
393 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
394 {
395         size_t skip = i->iov_offset;
396         const struct iovec *iov;
397         int err;
398         struct iovec v;
399 
400         if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
401                 iterate_iovec(i, bytes, v, iov, skip, ({
402                         err = fault_in_pages_readable(v.iov_base, v.iov_len);
403                         if (unlikely(err))
404                         return err;
405                 0;}))
406         }
407         return 0;
408 }
409 EXPORT_SYMBOL(iov_iter_fault_in_readable);
410 
411 void iov_iter_init(struct iov_iter *i, int direction,
412                         const struct iovec *iov, unsigned long nr_segs,
413                         size_t count)
414 {
415         /* It will get better.  Eventually... */
416         if (segment_eq(get_fs(), KERNEL_DS)) {
417                 direction |= ITER_KVEC;
418                 i->type = direction;
419                 i->kvec = (struct kvec *)iov;
420         } else {
421                 i->type = direction;
422                 i->iov = iov;
423         }
424         i->nr_segs = nr_segs;
425         i->iov_offset = 0;
426         i->count = count;
427 }
428 EXPORT_SYMBOL(iov_iter_init);
429 
430 static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
431 {
432         char *from = kmap_atomic(page);
433         memcpy(to, from + offset, len);
434         kunmap_atomic(from);
435 }
436 
437 static void memcpy_to_page(struct page *page, size_t offset, const char *from, size_t len)
438 {
439         char *to = kmap_atomic(page);
440         memcpy(to + offset, from, len);
441         kunmap_atomic(to);
442 }
443 
444 static void memzero_page(struct page *page, size_t offset, size_t len)
445 {
446         char *addr = kmap_atomic(page);
447         memset(addr + offset, 0, len);
448         kunmap_atomic(addr);
449 }
450 
451 static inline bool allocated(struct pipe_buffer *buf)
452 {
453         return buf->ops == &default_pipe_buf_ops;
454 }
455 
456 static inline void data_start(const struct iov_iter *i, int *idxp, size_t *offp)
457 {
458         size_t off = i->iov_offset;
459         int idx = i->idx;
460         if (off && (!allocated(&i->pipe->bufs[idx]) || off == PAGE_SIZE)) {
461                 idx = next_idx(idx, i->pipe);
462                 off = 0;
463         }
464         *idxp = idx;
465         *offp = off;
466 }
467 
468 static size_t push_pipe(struct iov_iter *i, size_t size,
469                         int *idxp, size_t *offp)
470 {
471         struct pipe_inode_info *pipe = i->pipe;
472         size_t off;
473         int idx;
474         ssize_t left;
475 
476         if (unlikely(size > i->count))
477                 size = i->count;
478         if (unlikely(!size))
479                 return 0;
480 
481         left = size;
482         data_start(i, &idx, &off);
483         *idxp = idx;
484         *offp = off;
485         if (off) {
486                 left -= PAGE_SIZE - off;
487                 if (left <= 0) {
488                         pipe->bufs[idx].len += size;
489                         return size;
490                 }
491                 pipe->bufs[idx].len = PAGE_SIZE;
492                 idx = next_idx(idx, pipe);
493         }
494         while (idx != pipe->curbuf || !pipe->nrbufs) {
495                 struct page *page = alloc_page(GFP_USER);
496                 if (!page)
497                         break;
498                 pipe->nrbufs++;
499                 pipe->bufs[idx].ops = &default_pipe_buf_ops;
500                 pipe->bufs[idx].page = page;
501                 pipe->bufs[idx].offset = 0;
502                 if (left <= PAGE_SIZE) {
503                         pipe->bufs[idx].len = left;
504                         return size;
505                 }
506                 pipe->bufs[idx].len = PAGE_SIZE;
507                 left -= PAGE_SIZE;
508                 idx = next_idx(idx, pipe);
509         }
510         return size - left;
511 }
512 
513 static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
514                                 struct iov_iter *i)
515 {
516         struct pipe_inode_info *pipe = i->pipe;
517         size_t n, off;
518         int idx;
519 
520         if (!sanity(i))
521                 return 0;
522 
523         bytes = n = push_pipe(i, bytes, &idx, &off);
524         if (unlikely(!n))
525                 return 0;
526         for ( ; n; idx = next_idx(idx, pipe), off = 0) {
527                 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
528                 memcpy_to_page(pipe->bufs[idx].page, off, addr, chunk);
529                 i->idx = idx;
530                 i->iov_offset = off + chunk;
531                 n -= chunk;
532                 addr += chunk;
533         }
534         i->count -= bytes;
535         return bytes;
536 }
537 
538 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
539 {
540         const char *from = addr;
541         if (unlikely(i->type & ITER_PIPE))
542                 return copy_pipe_to_iter(addr, bytes, i);
543         iterate_and_advance(i, bytes, v,
544                 __copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len,
545                                v.iov_len),
546                 memcpy_to_page(v.bv_page, v.bv_offset,
547                                (from += v.bv_len) - v.bv_len, v.bv_len),
548                 memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
549         )
550 
551         return bytes;
552 }
553 EXPORT_SYMBOL(copy_to_iter);
554 
555 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
556 {
557         char *to = addr;
558         if (unlikely(i->type & ITER_PIPE)) {
559                 WARN_ON(1);
560                 return 0;
561         }
562         iterate_and_advance(i, bytes, v,
563                 __copy_from_user((to += v.iov_len) - v.iov_len, v.iov_base,
564                                  v.iov_len),
565                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
566                                  v.bv_offset, v.bv_len),
567                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
568         )
569 
570         return bytes;
571 }
572 EXPORT_SYMBOL(copy_from_iter);
573 
574 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
575 {
576         char *to = addr;
577         if (unlikely(i->type & ITER_PIPE)) {
578                 WARN_ON(1);
579                 return false;
580         }
581         if (unlikely(i->count < bytes))
582                 return false;
583 
584         iterate_all_kinds(i, bytes, v, ({
585                 if (__copy_from_user((to += v.iov_len) - v.iov_len,
586                                       v.iov_base, v.iov_len))
587                         return false;
588                 0;}),
589                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
590                                  v.bv_offset, v.bv_len),
591                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
592         )
593 
594         iov_iter_advance(i, bytes);
595         return true;
596 }
597 EXPORT_SYMBOL(copy_from_iter_full);
598 
599 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
600 {
601         char *to = addr;
602         if (unlikely(i->type & ITER_PIPE)) {
603                 WARN_ON(1);
604                 return 0;
605         }
606         iterate_and_advance(i, bytes, v,
607                 __copy_from_user_nocache((to += v.iov_len) - v.iov_len,
608                                          v.iov_base, v.iov_len),
609                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
610                                  v.bv_offset, v.bv_len),
611                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
612         )
613 
614         return bytes;
615 }
616 EXPORT_SYMBOL(copy_from_iter_nocache);
617 
618 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
619 {
620         char *to = addr;
621         if (unlikely(i->type & ITER_PIPE)) {
622                 WARN_ON(1);
623                 return false;
624         }
625         if (unlikely(i->count < bytes))
626                 return false;
627         iterate_all_kinds(i, bytes, v, ({
628                 if (__copy_from_user_nocache((to += v.iov_len) - v.iov_len,
629                                              v.iov_base, v.iov_len))
630                         return false;
631                 0;}),
632                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
633                                  v.bv_offset, v.bv_len),
634                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
635         )
636 
637         iov_iter_advance(i, bytes);
638         return true;
639 }
640 EXPORT_SYMBOL(copy_from_iter_full_nocache);
641 
642 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
643                          struct iov_iter *i)
644 {
645         if (i->type & (ITER_BVEC|ITER_KVEC)) {
646                 void *kaddr = kmap_atomic(page);
647                 size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
648                 kunmap_atomic(kaddr);
649                 return wanted;
650         } else if (likely(!(i->type & ITER_PIPE)))
651                 return copy_page_to_iter_iovec(page, offset, bytes, i);
652         else
653                 return copy_page_to_iter_pipe(page, offset, bytes, i);
654 }
655 EXPORT_SYMBOL(copy_page_to_iter);
656 
657 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
658                          struct iov_iter *i)
659 {
660         if (unlikely(i->type & ITER_PIPE)) {
661                 WARN_ON(1);
662                 return 0;
663         }
664         if (i->type & (ITER_BVEC|ITER_KVEC)) {
665                 void *kaddr = kmap_atomic(page);
666                 size_t wanted = copy_from_iter(kaddr + offset, bytes, i);
667                 kunmap_atomic(kaddr);
668                 return wanted;
669         } else
670                 return copy_page_from_iter_iovec(page, offset, bytes, i);
671 }
672 EXPORT_SYMBOL(copy_page_from_iter);
673 
674 static size_t pipe_zero(size_t bytes, struct iov_iter *i)
675 {
676         struct pipe_inode_info *pipe = i->pipe;
677         size_t n, off;
678         int idx;
679 
680         if (!sanity(i))
681                 return 0;
682 
683         bytes = n = push_pipe(i, bytes, &idx, &off);
684         if (unlikely(!n))
685                 return 0;
686 
687         for ( ; n; idx = next_idx(idx, pipe), off = 0) {
688                 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
689                 memzero_page(pipe->bufs[idx].page, off, chunk);
690                 i->idx = idx;
691                 i->iov_offset = off + chunk;
692                 n -= chunk;
693         }
694         i->count -= bytes;
695         return bytes;
696 }
697 
698 size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
699 {
700         if (unlikely(i->type & ITER_PIPE))
701                 return pipe_zero(bytes, i);
702         iterate_and_advance(i, bytes, v,
703                 __clear_user(v.iov_base, v.iov_len),
704                 memzero_page(v.bv_page, v.bv_offset, v.bv_len),
705                 memset(v.iov_base, 0, v.iov_len)
706         )
707 
708         return bytes;
709 }
710 EXPORT_SYMBOL(iov_iter_zero);
711 
712 size_t iov_iter_copy_from_user_atomic(struct page *page,
713                 struct iov_iter *i, unsigned long offset, size_t bytes)
714 {
715         char *kaddr = kmap_atomic(page), *p = kaddr + offset;
716         if (unlikely(i->type & ITER_PIPE)) {
717                 kunmap_atomic(kaddr);
718                 WARN_ON(1);
719                 return 0;
720         }
721         iterate_all_kinds(i, bytes, v,
722                 __copy_from_user_inatomic((p += v.iov_len) - v.iov_len,
723                                           v.iov_base, v.iov_len),
724                 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
725                                  v.bv_offset, v.bv_len),
726                 memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
727         )
728         kunmap_atomic(kaddr);
729         return bytes;
730 }
731 EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
732 
733 static inline void pipe_truncate(struct iov_iter *i)
734 {
735         struct pipe_inode_info *pipe = i->pipe;
736         if (pipe->nrbufs) {
737                 size_t off = i->iov_offset;
738                 int idx = i->idx;
739                 int nrbufs = (idx - pipe->curbuf) & (pipe->buffers - 1);
740                 if (off) {
741                         pipe->bufs[idx].len = off - pipe->bufs[idx].offset;
742                         idx = next_idx(idx, pipe);
743                         nrbufs++;
744                 }
745                 while (pipe->nrbufs > nrbufs) {
746                         pipe_buf_release(pipe, &pipe->bufs[idx]);
747                         idx = next_idx(idx, pipe);
748                         pipe->nrbufs--;
749                 }
750         }
751 }
752 
753 static void pipe_advance(struct iov_iter *i, size_t size)
754 {
755         struct pipe_inode_info *pipe = i->pipe;
756         if (unlikely(i->count < size))
757                 size = i->count;
758         if (size) {
759                 struct pipe_buffer *buf;
760                 size_t off = i->iov_offset, left = size;
761                 int idx = i->idx;
762                 if (off) /* make it relative to the beginning of buffer */
763                         left += off - pipe->bufs[idx].offset;
764                 while (1) {
765                         buf = &pipe->bufs[idx];
766                         if (left <= buf->len)
767                                 break;
768                         left -= buf->len;
769                         idx = next_idx(idx, pipe);
770                 }
771                 i->idx = idx;
772                 i->iov_offset = buf->offset + left;
773         }
774         i->count -= size;
775         /* ... and discard everything past that point */
776         pipe_truncate(i);
777 }
778 
779 void iov_iter_advance(struct iov_iter *i, size_t size)
780 {
781         if (unlikely(i->type & ITER_PIPE)) {
782                 pipe_advance(i, size);
783                 return;
784         }
785         iterate_and_advance(i, size, v, 0, 0, 0)
786 }
787 EXPORT_SYMBOL(iov_iter_advance);
788 
789 /*
790  * Return the count of just the current iov_iter segment.
791  */
792 size_t iov_iter_single_seg_count(const struct iov_iter *i)
793 {
794         if (unlikely(i->type & ITER_PIPE))
795                 return i->count;        // it is a silly place, anyway
796         if (i->nr_segs == 1)
797                 return i->count;
798         else if (i->type & ITER_BVEC)
799                 return min(i->count, i->bvec->bv_len - i->iov_offset);
800         else
801                 return min(i->count, i->iov->iov_len - i->iov_offset);
802 }
803 EXPORT_SYMBOL(iov_iter_single_seg_count);
804 
805 void iov_iter_kvec(struct iov_iter *i, int direction,
806                         const struct kvec *kvec, unsigned long nr_segs,
807                         size_t count)
808 {
809         BUG_ON(!(direction & ITER_KVEC));
810         i->type = direction;
811         i->kvec = kvec;
812         i->nr_segs = nr_segs;
813         i->iov_offset = 0;
814         i->count = count;
815 }
816 EXPORT_SYMBOL(iov_iter_kvec);
817 
818 void iov_iter_bvec(struct iov_iter *i, int direction,
819                         const struct bio_vec *bvec, unsigned long nr_segs,
820                         size_t count)
821 {
822         BUG_ON(!(direction & ITER_BVEC));
823         i->type = direction;
824         i->bvec = bvec;
825         i->nr_segs = nr_segs;
826         i->iov_offset = 0;
827         i->count = count;
828 }
829 EXPORT_SYMBOL(iov_iter_bvec);
830 
831 void iov_iter_pipe(struct iov_iter *i, int direction,
832                         struct pipe_inode_info *pipe,
833                         size_t count)
834 {
835         BUG_ON(direction != ITER_PIPE);
836         WARN_ON(pipe->nrbufs == pipe->buffers);
837         i->type = direction;
838         i->pipe = pipe;
839         i->idx = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
840         i->iov_offset = 0;
841         i->count = count;
842 }
843 EXPORT_SYMBOL(iov_iter_pipe);
844 
845 unsigned long iov_iter_alignment(const struct iov_iter *i)
846 {
847         unsigned long res = 0;
848         size_t size = i->count;
849 
850         if (unlikely(i->type & ITER_PIPE)) {
851                 if (size && i->iov_offset && allocated(&i->pipe->bufs[i->idx]))
852                         return size | i->iov_offset;
853                 return size;
854         }
855         iterate_all_kinds(i, size, v,
856                 (res |= (unsigned long)v.iov_base | v.iov_len, 0),
857                 res |= v.bv_offset | v.bv_len,
858                 res |= (unsigned long)v.iov_base | v.iov_len
859         )
860         return res;
861 }
862 EXPORT_SYMBOL(iov_iter_alignment);
863 
864 unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
865 {
866         unsigned long res = 0;
867         size_t size = i->count;
868 
869         if (unlikely(i->type & ITER_PIPE)) {
870                 WARN_ON(1);
871                 return ~0U;
872         }
873 
874         iterate_all_kinds(i, size, v,
875                 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
876                         (size != v.iov_len ? size : 0), 0),
877                 (res |= (!res ? 0 : (unsigned long)v.bv_offset) |
878                         (size != v.bv_len ? size : 0)),
879                 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
880                         (size != v.iov_len ? size : 0))
881                 );
882         return res;
883 }
884 EXPORT_SYMBOL(iov_iter_gap_alignment);
885 
886 static inline size_t __pipe_get_pages(struct iov_iter *i,
887                                 size_t maxsize,
888                                 struct page **pages,
889                                 int idx,
890                                 size_t *start)
891 {
892         struct pipe_inode_info *pipe = i->pipe;
893         ssize_t n = push_pipe(i, maxsize, &idx, start);
894         if (!n)
895                 return -EFAULT;
896 
897         maxsize = n;
898         n += *start;
899         while (n > 0) {
900                 get_page(*pages++ = pipe->bufs[idx].page);
901                 idx = next_idx(idx, pipe);
902                 n -= PAGE_SIZE;
903         }
904 
905         return maxsize;
906 }
907 
908 static ssize_t pipe_get_pages(struct iov_iter *i,
909                    struct page **pages, size_t maxsize, unsigned maxpages,
910                    size_t *start)
911 {
912         unsigned npages;
913         size_t capacity;
914         int idx;
915 
916         if (!maxsize)
917                 return 0;
918 
919         if (!sanity(i))
920                 return -EFAULT;
921 
922         data_start(i, &idx, start);
923         /* some of this one + all after this one */
924         npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
925         capacity = min(npages,maxpages) * PAGE_SIZE - *start;
926 
927         return __pipe_get_pages(i, min(maxsize, capacity), pages, idx, start);
928 }
929 
930 ssize_t iov_iter_get_pages(struct iov_iter *i,
931                    struct page **pages, size_t maxsize, unsigned maxpages,
932                    size_t *start)
933 {
934         if (maxsize > i->count)
935                 maxsize = i->count;
936 
937         if (unlikely(i->type & ITER_PIPE))
938                 return pipe_get_pages(i, pages, maxsize, maxpages, start);
939         iterate_all_kinds(i, maxsize, v, ({
940                 unsigned long addr = (unsigned long)v.iov_base;
941                 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
942                 int n;
943                 int res;
944 
945                 if (len > maxpages * PAGE_SIZE)
946                         len = maxpages * PAGE_SIZE;
947                 addr &= ~(PAGE_SIZE - 1);
948                 n = DIV_ROUND_UP(len, PAGE_SIZE);
949                 res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages);
950                 if (unlikely(res < 0))
951                         return res;
952                 return (res == n ? len : res * PAGE_SIZE) - *start;
953         0;}),({
954                 /* can't be more than PAGE_SIZE */
955                 *start = v.bv_offset;
956                 get_page(*pages = v.bv_page);
957                 return v.bv_len;
958         }),({
959                 return -EFAULT;
960         })
961         )
962         return 0;
963 }
964 EXPORT_SYMBOL(iov_iter_get_pages);
965 
966 static struct page **get_pages_array(size_t n)
967 {
968         struct page **p = kmalloc(n * sizeof(struct page *), GFP_KERNEL);
969         if (!p)
970                 p = vmalloc(n * sizeof(struct page *));
971         return p;
972 }
973 
974 static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
975                    struct page ***pages, size_t maxsize,
976                    size_t *start)
977 {
978         struct page **p;
979         size_t n;
980         int idx;
981         int npages;
982 
983         if (!maxsize)
984                 return 0;
985 
986         if (!sanity(i))
987                 return -EFAULT;
988 
989         data_start(i, &idx, start);
990         /* some of this one + all after this one */
991         npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
992         n = npages * PAGE_SIZE - *start;
993         if (maxsize > n)
994                 maxsize = n;
995         else
996                 npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
997         p = get_pages_array(npages);
998         if (!p)
999                 return -ENOMEM;
1000         n = __pipe_get_pages(i, maxsize, p, idx, start);
1001         if (n > 0)
1002                 *pages = p;
1003         else
1004                 kvfree(p);
1005         return n;
1006 }
1007 
1008 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
1009                    struct page ***pages, size_t maxsize,
1010                    size_t *start)
1011 {
1012         struct page **p;
1013 
1014         if (maxsize > i->count)
1015                 maxsize = i->count;
1016 
1017         if (unlikely(i->type & ITER_PIPE))
1018                 return pipe_get_pages_alloc(i, pages, maxsize, start);
1019         iterate_all_kinds(i, maxsize, v, ({
1020                 unsigned long addr = (unsigned long)v.iov_base;
1021                 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
1022                 int n;
1023                 int res;
1024 
1025                 addr &= ~(PAGE_SIZE - 1);
1026                 n = DIV_ROUND_UP(len, PAGE_SIZE);
1027                 p = get_pages_array(n);
1028                 if (!p)
1029                         return -ENOMEM;
1030                 res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
1031                 if (unlikely(res < 0)) {
1032                         kvfree(p);
1033                         return res;
1034                 }
1035                 *pages = p;
1036                 return (res == n ? len : res * PAGE_SIZE) - *start;
1037         0;}),({
1038                 /* can't be more than PAGE_SIZE */
1039                 *start = v.bv_offset;
1040                 *pages = p = get_pages_array(1);
1041                 if (!p)
1042                         return -ENOMEM;
1043                 get_page(*p = v.bv_page);
1044                 return v.bv_len;
1045         }),({
1046                 return -EFAULT;
1047         })
1048         )
1049         return 0;
1050 }
1051 EXPORT_SYMBOL(iov_iter_get_pages_alloc);
1052 
1053 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
1054                                struct iov_iter *i)
1055 {
1056         char *to = addr;
1057         __wsum sum, next;
1058         size_t off = 0;
1059         sum = *csum;
1060         if (unlikely(i->type & ITER_PIPE)) {
1061                 WARN_ON(1);
1062                 return 0;
1063         }
1064         iterate_and_advance(i, bytes, v, ({
1065                 int err = 0;
1066                 next = csum_and_copy_from_user(v.iov_base,
1067                                                (to += v.iov_len) - v.iov_len,
1068                                                v.iov_len, 0, &err);
1069                 if (!err) {
1070                         sum = csum_block_add(sum, next, off);
1071                         off += v.iov_len;
1072                 }
1073                 err ? v.iov_len : 0;
1074         }), ({
1075                 char *p = kmap_atomic(v.bv_page);
1076                 next = csum_partial_copy_nocheck(p + v.bv_offset,
1077                                                  (to += v.bv_len) - v.bv_len,
1078                                                  v.bv_len, 0);
1079                 kunmap_atomic(p);
1080                 sum = csum_block_add(sum, next, off);
1081                 off += v.bv_len;
1082         }),({
1083                 next = csum_partial_copy_nocheck(v.iov_base,
1084                                                  (to += v.iov_len) - v.iov_len,
1085                                                  v.iov_len, 0);
1086                 sum = csum_block_add(sum, next, off);
1087                 off += v.iov_len;
1088         })
1089         )
1090         *csum = sum;
1091         return bytes;
1092 }
1093 EXPORT_SYMBOL(csum_and_copy_from_iter);
1094 
1095 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
1096                                struct iov_iter *i)
1097 {
1098         char *to = addr;
1099         __wsum sum, next;
1100         size_t off = 0;
1101         sum = *csum;
1102         if (unlikely(i->type & ITER_PIPE)) {
1103                 WARN_ON(1);
1104                 return false;
1105         }
1106         if (unlikely(i->count < bytes))
1107                 return false;
1108         iterate_all_kinds(i, bytes, v, ({
1109                 int err = 0;
1110                 next = csum_and_copy_from_user(v.iov_base,
1111                                                (to += v.iov_len) - v.iov_len,
1112                                                v.iov_len, 0, &err);
1113                 if (err)
1114                         return false;
1115                 sum = csum_block_add(sum, next, off);
1116                 off += v.iov_len;
1117                 0;
1118         }), ({
1119                 char *p = kmap_atomic(v.bv_page);
1120                 next = csum_partial_copy_nocheck(p + v.bv_offset,
1121                                                  (to += v.bv_len) - v.bv_len,
1122                                                  v.bv_len, 0);
1123                 kunmap_atomic(p);
1124                 sum = csum_block_add(sum, next, off);
1125                 off += v.bv_len;
1126         }),({
1127                 next = csum_partial_copy_nocheck(v.iov_base,
1128                                                  (to += v.iov_len) - v.iov_len,
1129                                                  v.iov_len, 0);
1130                 sum = csum_block_add(sum, next, off);
1131                 off += v.iov_len;
1132         })
1133         )
1134         *csum = sum;
1135         iov_iter_advance(i, bytes);
1136         return true;
1137 }
1138 EXPORT_SYMBOL(csum_and_copy_from_iter_full);
1139 
1140 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum,
1141                              struct iov_iter *i)
1142 {
1143         const char *from = addr;
1144         __wsum sum, next;
1145         size_t off = 0;
1146         sum = *csum;
1147         if (unlikely(i->type & ITER_PIPE)) {
1148                 WARN_ON(1);     /* for now */
1149                 return 0;
1150         }
1151         iterate_and_advance(i, bytes, v, ({
1152                 int err = 0;
1153                 next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
1154                                              v.iov_base,
1155                                              v.iov_len, 0, &err);
1156                 if (!err) {
1157                         sum = csum_block_add(sum, next, off);
1158                         off += v.iov_len;
1159                 }
1160                 err ? v.iov_len : 0;
1161         }), ({
1162                 char *p = kmap_atomic(v.bv_page);
1163                 next = csum_partial_copy_nocheck((from += v.bv_len) - v.bv_len,
1164                                                  p + v.bv_offset,
1165                                                  v.bv_len, 0);
1166                 kunmap_atomic(p);
1167                 sum = csum_block_add(sum, next, off);
1168                 off += v.bv_len;
1169         }),({
1170                 next = csum_partial_copy_nocheck((from += v.iov_len) - v.iov_len,
1171                                                  v.iov_base,
1172                                                  v.iov_len, 0);
1173                 sum = csum_block_add(sum, next, off);
1174                 off += v.iov_len;
1175         })
1176         )
1177         *csum = sum;
1178         return bytes;
1179 }
1180 EXPORT_SYMBOL(csum_and_copy_to_iter);
1181 
1182 int iov_iter_npages(const struct iov_iter *i, int maxpages)
1183 {
1184         size_t size = i->count;
1185         int npages = 0;
1186 
1187         if (!size)
1188                 return 0;
1189 
1190         if (unlikely(i->type & ITER_PIPE)) {
1191                 struct pipe_inode_info *pipe = i->pipe;
1192                 size_t off;
1193                 int idx;
1194 
1195                 if (!sanity(i))
1196                         return 0;
1197 
1198                 data_start(i, &idx, &off);
1199                 /* some of this one + all after this one */
1200                 npages = ((pipe->curbuf - idx - 1) & (pipe->buffers - 1)) + 1;
1201                 if (npages >= maxpages)
1202                         return maxpages;
1203         } else iterate_all_kinds(i, size, v, ({
1204                 unsigned long p = (unsigned long)v.iov_base;
1205                 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1206                         - p / PAGE_SIZE;
1207                 if (npages >= maxpages)
1208                         return maxpages;
1209         0;}),({
1210                 npages++;
1211                 if (npages >= maxpages)
1212                         return maxpages;
1213         }),({
1214                 unsigned long p = (unsigned long)v.iov_base;
1215                 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1216                         - p / PAGE_SIZE;
1217                 if (npages >= maxpages)
1218                         return maxpages;
1219         })
1220         )
1221         return npages;
1222 }
1223 EXPORT_SYMBOL(iov_iter_npages);
1224 
1225 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
1226 {
1227         *new = *old;
1228         if (unlikely(new->type & ITER_PIPE)) {
1229                 WARN_ON(1);
1230                 return NULL;
1231         }
1232         if (new->type & ITER_BVEC)
1233                 return new->bvec = kmemdup(new->bvec,
1234                                     new->nr_segs * sizeof(struct bio_vec),
1235                                     flags);
1236         else
1237                 /* iovec and kvec have identical layout */
1238                 return new->iov = kmemdup(new->iov,
1239                                    new->nr_segs * sizeof(struct iovec),
1240                                    flags);
1241 }
1242 EXPORT_SYMBOL(dup_iter);
1243 
1244 /**
1245  * import_iovec() - Copy an array of &struct iovec from userspace
1246  *     into the kernel, check that it is valid, and initialize a new
1247  *     &struct iov_iter iterator to access it.
1248  *
1249  * @type: One of %READ or %WRITE.
1250  * @uvector: Pointer to the userspace array.
1251  * @nr_segs: Number of elements in userspace array.
1252  * @fast_segs: Number of elements in @iov.
1253  * @iov: (input and output parameter) Pointer to pointer to (usually small
1254  *     on-stack) kernel array.
1255  * @i: Pointer to iterator that will be initialized on success.
1256  *
1257  * If the array pointed to by *@iov is large enough to hold all @nr_segs,
1258  * then this function places %NULL in *@iov on return. Otherwise, a new
1259  * array will be allocated and the result placed in *@iov. This means that
1260  * the caller may call kfree() on *@iov regardless of whether the small
1261  * on-stack array was used or not (and regardless of whether this function
1262  * returns an error or not).
1263  *
1264  * Return: 0 on success or negative error code on error.
1265  */
1266 int import_iovec(int type, const struct iovec __user * uvector,
1267                  unsigned nr_segs, unsigned fast_segs,
1268                  struct iovec **iov, struct iov_iter *i)
1269 {
1270         ssize_t n;
1271         struct iovec *p;
1272         n = rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
1273                                   *iov, &p);
1274         if (n < 0) {
1275                 if (p != *iov)
1276                         kfree(p);
1277                 *iov = NULL;
1278                 return n;
1279         }
1280         iov_iter_init(i, type, p, nr_segs, n);
1281         *iov = p == *iov ? NULL : p;
1282         return 0;
1283 }
1284 EXPORT_SYMBOL(import_iovec);
1285 
1286 #ifdef CONFIG_COMPAT
1287 #include <linux/compat.h>
1288 
1289 int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
1290                  unsigned nr_segs, unsigned fast_segs,
1291                  struct iovec **iov, struct iov_iter *i)
1292 {
1293         ssize_t n;
1294         struct iovec *p;
1295         n = compat_rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
1296                                   *iov, &p);
1297         if (n < 0) {
1298                 if (p != *iov)
1299                         kfree(p);
1300                 *iov = NULL;
1301                 return n;
1302         }
1303         iov_iter_init(i, type, p, nr_segs, n);
1304         *iov = p == *iov ? NULL : p;
1305         return 0;
1306 }
1307 #endif
1308 
1309 int import_single_range(int rw, void __user *buf, size_t len,
1310                  struct iovec *iov, struct iov_iter *i)
1311 {
1312         if (len > MAX_RW_COUNT)
1313                 len = MAX_RW_COUNT;
1314         if (unlikely(!access_ok(!rw, buf, len)))
1315                 return -EFAULT;
1316 
1317         iov->iov_base = buf;
1318         iov->iov_len = len;
1319         iov_iter_init(i, rw, iov, 1, len);
1320         return 0;
1321 }
1322 EXPORT_SYMBOL(import_single_range);
1323 

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