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9#include <linux/syscalls.h>
10#include <linux/export.h>
11#include <linux/fs.h>
12#include <linux/mm.h>
13#include <linux/mmzone.h>
14#include <linux/time.h>
15#include <linux/sched.h>
16#include <linux/slab.h>
17#include <linux/vmalloc.h>
18#include <linux/file.h>
19#include <linux/fdtable.h>
20#include <linux/bitops.h>
21#include <linux/interrupt.h>
22#include <linux/spinlock.h>
23#include <linux/rcupdate.h>
24#include <linux/workqueue.h>
25
26int sysctl_nr_open __read_mostly = 1024*1024;
27int sysctl_nr_open_min = BITS_PER_LONG;
28
29#define __const_max(x, y) ((x) < (y) ? (x) : (y))
30int sysctl_nr_open_max = __const_max(INT_MAX, ~(size_t)0/sizeof(void *)) &
31 -BITS_PER_LONG;
32
33static void *alloc_fdmem(size_t size)
34{
35
36
37
38
39 if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
40 void *data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY);
41 if (data != NULL)
42 return data;
43 }
44 return vmalloc(size);
45}
46
47static void __free_fdtable(struct fdtable *fdt)
48{
49 kvfree(fdt->fd);
50 kvfree(fdt->open_fds);
51 kfree(fdt);
52}
53
54static void free_fdtable_rcu(struct rcu_head *rcu)
55{
56 __free_fdtable(container_of(rcu, struct fdtable, rcu));
57}
58
59
60
61
62
63static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
64{
65 unsigned int cpy, set;
66
67 BUG_ON(nfdt->max_fds < ofdt->max_fds);
68
69 cpy = ofdt->max_fds * sizeof(struct file *);
70 set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);
71 memcpy(nfdt->fd, ofdt->fd, cpy);
72 memset((char *)(nfdt->fd) + cpy, 0, set);
73
74 cpy = ofdt->max_fds / BITS_PER_BYTE;
75 set = (nfdt->max_fds - ofdt->max_fds) / BITS_PER_BYTE;
76 memcpy(nfdt->open_fds, ofdt->open_fds, cpy);
77 memset((char *)(nfdt->open_fds) + cpy, 0, set);
78 memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy);
79 memset((char *)(nfdt->close_on_exec) + cpy, 0, set);
80}
81
82static struct fdtable * alloc_fdtable(unsigned int nr)
83{
84 struct fdtable *fdt;
85 void *data;
86
87
88
89
90
91
92
93
94 nr /= (1024 / sizeof(struct file *));
95 nr = roundup_pow_of_two(nr + 1);
96 nr *= (1024 / sizeof(struct file *));
97
98
99
100
101
102
103
104
105 if (unlikely(nr > sysctl_nr_open))
106 nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1;
107
108 fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL);
109 if (!fdt)
110 goto out;
111 fdt->max_fds = nr;
112 data = alloc_fdmem(nr * sizeof(struct file *));
113 if (!data)
114 goto out_fdt;
115 fdt->fd = data;
116
117 data = alloc_fdmem(max_t(size_t,
118 2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES));
119 if (!data)
120 goto out_arr;
121 fdt->open_fds = data;
122 data += nr / BITS_PER_BYTE;
123 fdt->close_on_exec = data;
124
125 return fdt;
126
127out_arr:
128 kvfree(fdt->fd);
129out_fdt:
130 kfree(fdt);
131out:
132 return NULL;
133}
134
135
136
137
138
139
140
141
142static int expand_fdtable(struct files_struct *files, int nr)
143 __releases(files->file_lock)
144 __acquires(files->file_lock)
145{
146 struct fdtable *new_fdt, *cur_fdt;
147
148 spin_unlock(&files->file_lock);
149 new_fdt = alloc_fdtable(nr);
150 spin_lock(&files->file_lock);
151 if (!new_fdt)
152 return -ENOMEM;
153
154
155
156
157 if (unlikely(new_fdt->max_fds <= nr)) {
158 __free_fdtable(new_fdt);
159 return -EMFILE;
160 }
161
162
163
164
165 cur_fdt = files_fdtable(files);
166 if (nr >= cur_fdt->max_fds) {
167
168 copy_fdtable(new_fdt, cur_fdt);
169 rcu_assign_pointer(files->fdt, new_fdt);
170 if (cur_fdt != &files->fdtab)
171 call_rcu(&cur_fdt->rcu, free_fdtable_rcu);
172 } else {
173
174 __free_fdtable(new_fdt);
175 }
176 return 1;
177}
178
179
180
181
182
183
184
185
186
187static int expand_files(struct files_struct *files, int nr)
188{
189 struct fdtable *fdt;
190
191 fdt = files_fdtable(files);
192
193
194 if (nr < fdt->max_fds)
195 return 0;
196
197
198 if (nr >= sysctl_nr_open)
199 return -EMFILE;
200
201
202 return expand_fdtable(files, nr);
203}
204
205static inline void __set_close_on_exec(int fd, struct fdtable *fdt)
206{
207 __set_bit(fd, fdt->close_on_exec);
208}
209
210static inline void __clear_close_on_exec(int fd, struct fdtable *fdt)
211{
212 __clear_bit(fd, fdt->close_on_exec);
213}
214
215static inline void __set_open_fd(int fd, struct fdtable *fdt)
216{
217 __set_bit(fd, fdt->open_fds);
218}
219
220static inline void __clear_open_fd(int fd, struct fdtable *fdt)
221{
222 __clear_bit(fd, fdt->open_fds);
223}
224
225static int count_open_files(struct fdtable *fdt)
226{
227 int size = fdt->max_fds;
228 int i;
229
230
231 for (i = size / BITS_PER_LONG; i > 0; ) {
232 if (fdt->open_fds[--i])
233 break;
234 }
235 i = (i + 1) * BITS_PER_LONG;
236 return i;
237}
238
239
240
241
242
243
244struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
245{
246 struct files_struct *newf;
247 struct file **old_fds, **new_fds;
248 int open_files, size, i;
249 struct fdtable *old_fdt, *new_fdt;
250
251 *errorp = -ENOMEM;
252 newf = kmem_cache_alloc(files_cachep, GFP_KERNEL);
253 if (!newf)
254 goto out;
255
256 atomic_set(&newf->count, 1);
257
258 spin_lock_init(&newf->file_lock);
259 newf->next_fd = 0;
260 new_fdt = &newf->fdtab;
261 new_fdt->max_fds = NR_OPEN_DEFAULT;
262 new_fdt->close_on_exec = newf->close_on_exec_init;
263 new_fdt->open_fds = newf->open_fds_init;
264 new_fdt->fd = &newf->fd_array[0];
265
266 spin_lock(&oldf->file_lock);
267 old_fdt = files_fdtable(oldf);
268 open_files = count_open_files(old_fdt);
269
270
271
272
273 while (unlikely(open_files > new_fdt->max_fds)) {
274 spin_unlock(&oldf->file_lock);
275
276 if (new_fdt != &newf->fdtab)
277 __free_fdtable(new_fdt);
278
279 new_fdt = alloc_fdtable(open_files - 1);
280 if (!new_fdt) {
281 *errorp = -ENOMEM;
282 goto out_release;
283 }
284
285
286 if (unlikely(new_fdt->max_fds < open_files)) {
287 __free_fdtable(new_fdt);
288 *errorp = -EMFILE;
289 goto out_release;
290 }
291
292
293
294
295
296
297 spin_lock(&oldf->file_lock);
298 old_fdt = files_fdtable(oldf);
299 open_files = count_open_files(old_fdt);
300 }
301
302 old_fds = old_fdt->fd;
303 new_fds = new_fdt->fd;
304
305 memcpy(new_fdt->open_fds, old_fdt->open_fds, open_files / 8);
306 memcpy(new_fdt->close_on_exec, old_fdt->close_on_exec, open_files / 8);
307
308 for (i = open_files; i != 0; i--) {
309 struct file *f = *old_fds++;
310 if (f) {
311 get_file(f);
312 } else {
313
314
315
316
317
318
319 __clear_open_fd(open_files - i, new_fdt);
320 }
321 rcu_assign_pointer(*new_fds++, f);
322 }
323 spin_unlock(&oldf->file_lock);
324
325
326 size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
327
328
329 memset(new_fds, 0, size);
330
331 if (new_fdt->max_fds > open_files) {
332 int left = (new_fdt->max_fds - open_files) / 8;
333 int start = open_files / BITS_PER_LONG;
334
335 memset(&new_fdt->open_fds[start], 0, left);
336 memset(&new_fdt->close_on_exec[start], 0, left);
337 }
338
339 rcu_assign_pointer(newf->fdt, new_fdt);
340
341 return newf;
342
343out_release:
344 kmem_cache_free(files_cachep, newf);
345out:
346 return NULL;
347}
348
349static struct fdtable *close_files(struct files_struct * files)
350{
351
352
353
354
355
356 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
357 int i, j = 0;
358
359 for (;;) {
360 unsigned long set;
361 i = j * BITS_PER_LONG;
362 if (i >= fdt->max_fds)
363 break;
364 set = fdt->open_fds[j++];
365 while (set) {
366 if (set & 1) {
367 struct file * file = xchg(&fdt->fd[i], NULL);
368 if (file) {
369 filp_close(file, files);
370 cond_resched_rcu_qs();
371 }
372 }
373 i++;
374 set >>= 1;
375 }
376 }
377
378 return fdt;
379}
380
381struct files_struct *get_files_struct(struct task_struct *task)
382{
383 struct files_struct *files;
384
385 task_lock(task);
386 files = task->files;
387 if (files)
388 atomic_inc(&files->count);
389 task_unlock(task);
390
391 return files;
392}
393
394void put_files_struct(struct files_struct *files)
395{
396 if (atomic_dec_and_test(&files->count)) {
397 struct fdtable *fdt = close_files(files);
398
399
400 if (fdt != &files->fdtab)
401 __free_fdtable(fdt);
402 kmem_cache_free(files_cachep, files);
403 }
404}
405
406void reset_files_struct(struct files_struct *files)
407{
408 struct task_struct *tsk = current;
409 struct files_struct *old;
410
411 old = tsk->files;
412 task_lock(tsk);
413 tsk->files = files;
414 task_unlock(tsk);
415 put_files_struct(old);
416}
417
418void exit_files(struct task_struct *tsk)
419{
420 struct files_struct * files = tsk->files;
421
422 if (files) {
423 task_lock(tsk);
424 tsk->files = NULL;
425 task_unlock(tsk);
426 put_files_struct(files);
427 }
428}
429
430struct files_struct init_files = {
431 .count = ATOMIC_INIT(1),
432 .fdt = &init_files.fdtab,
433 .fdtab = {
434 .max_fds = NR_OPEN_DEFAULT,
435 .fd = &init_files.fd_array[0],
436 .close_on_exec = init_files.close_on_exec_init,
437 .open_fds = init_files.open_fds_init,
438 },
439 .file_lock = __SPIN_LOCK_UNLOCKED(init_files.file_lock),
440};
441
442
443
444
445int __alloc_fd(struct files_struct *files,
446 unsigned start, unsigned end, unsigned flags)
447{
448 unsigned int fd;
449 int error;
450 struct fdtable *fdt;
451
452 spin_lock(&files->file_lock);
453repeat:
454 fdt = files_fdtable(files);
455 fd = start;
456 if (fd < files->next_fd)
457 fd = files->next_fd;
458
459 if (fd < fdt->max_fds)
460 fd = find_next_zero_bit(fdt->open_fds, fdt->max_fds, fd);
461
462
463
464
465
466 error = -EMFILE;
467 if (fd >= end)
468 goto out;
469
470 error = expand_files(files, fd);
471 if (error < 0)
472 goto out;
473
474
475
476
477
478 if (error)
479 goto repeat;
480
481 if (start <= files->next_fd)
482 files->next_fd = fd + 1;
483
484 __set_open_fd(fd, fdt);
485 if (flags & O_CLOEXEC)
486 __set_close_on_exec(fd, fdt);
487 else
488 __clear_close_on_exec(fd, fdt);
489 error = fd;
490#if 1
491
492 if (rcu_access_pointer(fdt->fd[fd]) != NULL) {
493 printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
494 rcu_assign_pointer(fdt->fd[fd], NULL);
495 }
496#endif
497
498out:
499 spin_unlock(&files->file_lock);
500 return error;
501}
502
503static int alloc_fd(unsigned start, unsigned flags)
504{
505 return __alloc_fd(current->files, start, rlimit(RLIMIT_NOFILE), flags);
506}
507
508int get_unused_fd_flags(unsigned flags)
509{
510 return __alloc_fd(current->files, 0, rlimit(RLIMIT_NOFILE), flags);
511}
512EXPORT_SYMBOL(get_unused_fd_flags);
513
514static void __put_unused_fd(struct files_struct *files, unsigned int fd)
515{
516 struct fdtable *fdt = files_fdtable(files);
517 __clear_open_fd(fd, fdt);
518 if (fd < files->next_fd)
519 files->next_fd = fd;
520}
521
522void put_unused_fd(unsigned int fd)
523{
524 struct files_struct *files = current->files;
525 spin_lock(&files->file_lock);
526 __put_unused_fd(files, fd);
527 spin_unlock(&files->file_lock);
528}
529
530EXPORT_SYMBOL(put_unused_fd);
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551
552void __fd_install(struct files_struct *files, unsigned int fd,
553 struct file *file)
554{
555 struct fdtable *fdt;
556 spin_lock(&files->file_lock);
557 fdt = files_fdtable(files);
558 BUG_ON(fdt->fd[fd] != NULL);
559 rcu_assign_pointer(fdt->fd[fd], file);
560 spin_unlock(&files->file_lock);
561}
562
563void fd_install(unsigned int fd, struct file *file)
564{
565 __fd_install(current->files, fd, file);
566}
567
568EXPORT_SYMBOL(fd_install);
569
570
571
572
573int __close_fd(struct files_struct *files, unsigned fd)
574{
575 struct file *file;
576 struct fdtable *fdt;
577
578 spin_lock(&files->file_lock);
579 fdt = files_fdtable(files);
580 if (fd >= fdt->max_fds)
581 goto out_unlock;
582 file = fdt->fd[fd];
583 if (!file)
584 goto out_unlock;
585 rcu_assign_pointer(fdt->fd[fd], NULL);
586 __clear_close_on_exec(fd, fdt);
587 __put_unused_fd(files, fd);
588 spin_unlock(&files->file_lock);
589 return filp_close(file, files);
590
591out_unlock:
592 spin_unlock(&files->file_lock);
593 return -EBADF;
594}
595
596void do_close_on_exec(struct files_struct *files)
597{
598 unsigned i;
599 struct fdtable *fdt;
600
601
602 spin_lock(&files->file_lock);
603 for (i = 0; ; i++) {
604 unsigned long set;
605 unsigned fd = i * BITS_PER_LONG;
606 fdt = files_fdtable(files);
607 if (fd >= fdt->max_fds)
608 break;
609 set = fdt->close_on_exec[i];
610 if (!set)
611 continue;
612 fdt->close_on_exec[i] = 0;
613 for ( ; set ; fd++, set >>= 1) {
614 struct file *file;
615 if (!(set & 1))
616 continue;
617 file = fdt->fd[fd];
618 if (!file)
619 continue;
620 rcu_assign_pointer(fdt->fd[fd], NULL);
621 __put_unused_fd(files, fd);
622 spin_unlock(&files->file_lock);
623 filp_close(file, files);
624 cond_resched();
625 spin_lock(&files->file_lock);
626 }
627
628 }
629 spin_unlock(&files->file_lock);
630}
631
632static struct file *__fget(unsigned int fd, fmode_t mask)
633{
634 struct files_struct *files = current->files;
635 struct file *file;
636
637 rcu_read_lock();
638 file = fcheck_files(files, fd);
639 if (file) {
640
641 if ((file->f_mode & mask) ||
642 !atomic_long_inc_not_zero(&file->f_count))
643 file = NULL;
644 }
645 rcu_read_unlock();
646
647 return file;
648}
649
650struct file *fget(unsigned int fd)
651{
652 return __fget(fd, FMODE_PATH);
653}
654EXPORT_SYMBOL(fget);
655
656struct file *fget_raw(unsigned int fd)
657{
658 return __fget(fd, 0);
659}
660EXPORT_SYMBOL(fget_raw);
661
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664
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669
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676
677
678static unsigned long __fget_light(unsigned int fd, fmode_t mask)
679{
680 struct files_struct *files = current->files;
681 struct file *file;
682
683 if (atomic_read(&files->count) == 1) {
684 file = __fcheck_files(files, fd);
685 if (!file || unlikely(file->f_mode & mask))
686 return 0;
687 return (unsigned long)file;
688 } else {
689 file = __fget(fd, mask);
690 if (!file)
691 return 0;
692 return FDPUT_FPUT | (unsigned long)file;
693 }
694}
695unsigned long __fdget(unsigned int fd)
696{
697 return __fget_light(fd, FMODE_PATH);
698}
699EXPORT_SYMBOL(__fdget);
700
701unsigned long __fdget_raw(unsigned int fd)
702{
703 return __fget_light(fd, 0);
704}
705
706unsigned long __fdget_pos(unsigned int fd)
707{
708 unsigned long v = __fdget(fd);
709 struct file *file = (struct file *)(v & ~3);
710
711 if (file && (file->f_mode & FMODE_ATOMIC_POS)) {
712 if (file_count(file) > 1) {
713 v |= FDPUT_POS_UNLOCK;
714 mutex_lock(&file->f_pos_lock);
715 }
716 }
717 return v;
718}
719
720
721
722
723
724
725
726void set_close_on_exec(unsigned int fd, int flag)
727{
728 struct files_struct *files = current->files;
729 struct fdtable *fdt;
730 spin_lock(&files->file_lock);
731 fdt = files_fdtable(files);
732 if (flag)
733 __set_close_on_exec(fd, fdt);
734 else
735 __clear_close_on_exec(fd, fdt);
736 spin_unlock(&files->file_lock);
737}
738
739bool get_close_on_exec(unsigned int fd)
740{
741 struct files_struct *files = current->files;
742 struct fdtable *fdt;
743 bool res;
744 rcu_read_lock();
745 fdt = files_fdtable(files);
746 res = close_on_exec(fd, fdt);
747 rcu_read_unlock();
748 return res;
749}
750
751static int do_dup2(struct files_struct *files,
752 struct file *file, unsigned fd, unsigned flags)
753__releases(&files->file_lock)
754{
755 struct file *tofree;
756 struct fdtable *fdt;
757
758
759
760
761
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764
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766
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768
769
770
771
772 fdt = files_fdtable(files);
773 tofree = fdt->fd[fd];
774 if (!tofree && fd_is_open(fd, fdt))
775 goto Ebusy;
776 get_file(file);
777 rcu_assign_pointer(fdt->fd[fd], file);
778 __set_open_fd(fd, fdt);
779 if (flags & O_CLOEXEC)
780 __set_close_on_exec(fd, fdt);
781 else
782 __clear_close_on_exec(fd, fdt);
783 spin_unlock(&files->file_lock);
784
785 if (tofree)
786 filp_close(tofree, files);
787
788 return fd;
789
790Ebusy:
791 spin_unlock(&files->file_lock);
792 return -EBUSY;
793}
794
795int replace_fd(unsigned fd, struct file *file, unsigned flags)
796{
797 int err;
798 struct files_struct *files = current->files;
799
800 if (!file)
801 return __close_fd(files, fd);
802
803 if (fd >= rlimit(RLIMIT_NOFILE))
804 return -EBADF;
805
806 spin_lock(&files->file_lock);
807 err = expand_files(files, fd);
808 if (unlikely(err < 0))
809 goto out_unlock;
810 return do_dup2(files, file, fd, flags);
811
812out_unlock:
813 spin_unlock(&files->file_lock);
814 return err;
815}
816
817SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags)
818{
819 int err = -EBADF;
820 struct file *file;
821 struct files_struct *files = current->files;
822
823 if ((flags & ~O_CLOEXEC) != 0)
824 return -EINVAL;
825
826 if (unlikely(oldfd == newfd))
827 return -EINVAL;
828
829 if (newfd >= rlimit(RLIMIT_NOFILE))
830 return -EBADF;
831
832 spin_lock(&files->file_lock);
833 err = expand_files(files, newfd);
834 file = fcheck(oldfd);
835 if (unlikely(!file))
836 goto Ebadf;
837 if (unlikely(err < 0)) {
838 if (err == -EMFILE)
839 goto Ebadf;
840 goto out_unlock;
841 }
842 return do_dup2(files, file, newfd, flags);
843
844Ebadf:
845 err = -EBADF;
846out_unlock:
847 spin_unlock(&files->file_lock);
848 return err;
849}
850
851SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
852{
853 if (unlikely(newfd == oldfd)) {
854 struct files_struct *files = current->files;
855 int retval = oldfd;
856
857 rcu_read_lock();
858 if (!fcheck_files(files, oldfd))
859 retval = -EBADF;
860 rcu_read_unlock();
861 return retval;
862 }
863 return sys_dup3(oldfd, newfd, 0);
864}
865
866SYSCALL_DEFINE1(dup, unsigned int, fildes)
867{
868 int ret = -EBADF;
869 struct file *file = fget_raw(fildes);
870
871 if (file) {
872 ret = get_unused_fd_flags(0);
873 if (ret >= 0)
874 fd_install(ret, file);
875 else
876 fput(file);
877 }
878 return ret;
879}
880
881int f_dupfd(unsigned int from, struct file *file, unsigned flags)
882{
883 int err;
884 if (from >= rlimit(RLIMIT_NOFILE))
885 return -EINVAL;
886 err = alloc_fd(from, flags);
887 if (err >= 0) {
888 get_file(file);
889 fd_install(err, file);
890 }
891 return err;
892}
893
894int iterate_fd(struct files_struct *files, unsigned n,
895 int (*f)(const void *, struct file *, unsigned),
896 const void *p)
897{
898 struct fdtable *fdt;
899 int res = 0;
900 if (!files)
901 return 0;
902 spin_lock(&files->file_lock);
903 for (fdt = files_fdtable(files); n < fdt->max_fds; n++) {
904 struct file *file;
905 file = rcu_dereference_check_fdtable(files, fdt->fd[n]);
906 if (!file)
907 continue;
908 res = f(p, file, n);
909 if (res)
910 break;
911 }
912 spin_unlock(&files->file_lock);
913 return res;
914}
915EXPORT_SYMBOL(iterate_fd);
916