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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/fcntl.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | #include <linux/syscalls.h> | |
8 | #include <linux/init.h> | |
9 | #include <linux/mm.h> | |
10 | #include <linux/fs.h> | |
11 | #include <linux/file.h> | |
12 | #include <linux/dnotify.h> | |
13 | #include <linux/smp_lock.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/security.h> | |
17 | #include <linux/ptrace.h> | |
18 | ||
19 | #include <asm/poll.h> | |
20 | #include <asm/siginfo.h> | |
21 | #include <asm/uaccess.h> | |
22 | ||
23 | void fastcall set_close_on_exec(unsigned int fd, int flag) | |
24 | { | |
25 | struct files_struct *files = current->files; | |
26 | spin_lock(&files->file_lock); | |
27 | if (flag) | |
28 | FD_SET(fd, files->close_on_exec); | |
29 | else | |
30 | FD_CLR(fd, files->close_on_exec); | |
31 | spin_unlock(&files->file_lock); | |
32 | } | |
33 | ||
34 | static inline int get_close_on_exec(unsigned int fd) | |
35 | { | |
36 | struct files_struct *files = current->files; | |
37 | int res; | |
38 | spin_lock(&files->file_lock); | |
39 | res = FD_ISSET(fd, files->close_on_exec); | |
40 | spin_unlock(&files->file_lock); | |
41 | return res; | |
42 | } | |
43 | ||
44 | /* | |
45 | * locate_fd finds a free file descriptor in the open_fds fdset, | |
46 | * expanding the fd arrays if necessary. Must be called with the | |
47 | * file_lock held for write. | |
48 | */ | |
49 | ||
50 | static int locate_fd(struct files_struct *files, | |
51 | struct file *file, unsigned int orig_start) | |
52 | { | |
53 | unsigned int newfd; | |
54 | unsigned int start; | |
55 | int error; | |
56 | ||
57 | error = -EINVAL; | |
58 | if (orig_start >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
59 | goto out; | |
60 | ||
61 | repeat: | |
62 | /* | |
63 | * Someone might have closed fd's in the range | |
64 | * orig_start..files->next_fd | |
65 | */ | |
66 | start = orig_start; | |
67 | if (start < files->next_fd) | |
68 | start = files->next_fd; | |
69 | ||
70 | newfd = start; | |
71 | if (start < files->max_fdset) { | |
72 | newfd = find_next_zero_bit(files->open_fds->fds_bits, | |
73 | files->max_fdset, start); | |
74 | } | |
75 | ||
76 | error = -EMFILE; | |
77 | if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
78 | goto out; | |
79 | ||
80 | error = expand_files(files, newfd); | |
81 | if (error < 0) | |
82 | goto out; | |
83 | ||
84 | /* | |
85 | * If we needed to expand the fs array we | |
86 | * might have blocked - try again. | |
87 | */ | |
88 | if (error) | |
89 | goto repeat; | |
90 | ||
91 | if (start <= files->next_fd) | |
92 | files->next_fd = newfd + 1; | |
93 | ||
94 | error = newfd; | |
95 | ||
96 | out: | |
97 | return error; | |
98 | } | |
99 | ||
100 | static int dupfd(struct file *file, unsigned int start) | |
101 | { | |
102 | struct files_struct * files = current->files; | |
103 | int fd; | |
104 | ||
105 | spin_lock(&files->file_lock); | |
106 | fd = locate_fd(files, file, start); | |
107 | if (fd >= 0) { | |
108 | FD_SET(fd, files->open_fds); | |
109 | FD_CLR(fd, files->close_on_exec); | |
110 | spin_unlock(&files->file_lock); | |
111 | fd_install(fd, file); | |
112 | } else { | |
113 | spin_unlock(&files->file_lock); | |
114 | fput(file); | |
115 | } | |
116 | ||
117 | return fd; | |
118 | } | |
119 | ||
120 | asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd) | |
121 | { | |
122 | int err = -EBADF; | |
123 | struct file * file, *tofree; | |
124 | struct files_struct * files = current->files; | |
125 | ||
126 | spin_lock(&files->file_lock); | |
127 | if (!(file = fcheck(oldfd))) | |
128 | goto out_unlock; | |
129 | err = newfd; | |
130 | if (newfd == oldfd) | |
131 | goto out_unlock; | |
132 | err = -EBADF; | |
133 | if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
134 | goto out_unlock; | |
135 | get_file(file); /* We are now finished with oldfd */ | |
136 | ||
137 | err = expand_files(files, newfd); | |
138 | if (err < 0) | |
139 | goto out_fput; | |
140 | ||
141 | /* To avoid races with open() and dup(), we will mark the fd as | |
142 | * in-use in the open-file bitmap throughout the entire dup2() | |
143 | * process. This is quite safe: do_close() uses the fd array | |
144 | * entry, not the bitmap, to decide what work needs to be | |
145 | * done. --sct */ | |
146 | /* Doesn't work. open() might be there first. --AV */ | |
147 | ||
148 | /* Yes. It's a race. In user space. Nothing sane to do */ | |
149 | err = -EBUSY; | |
150 | tofree = files->fd[newfd]; | |
151 | if (!tofree && FD_ISSET(newfd, files->open_fds)) | |
152 | goto out_fput; | |
153 | ||
154 | files->fd[newfd] = file; | |
155 | FD_SET(newfd, files->open_fds); | |
156 | FD_CLR(newfd, files->close_on_exec); | |
157 | spin_unlock(&files->file_lock); | |
158 | ||
159 | if (tofree) | |
160 | filp_close(tofree, files); | |
161 | err = newfd; | |
162 | out: | |
163 | return err; | |
164 | out_unlock: | |
165 | spin_unlock(&files->file_lock); | |
166 | goto out; | |
167 | ||
168 | out_fput: | |
169 | spin_unlock(&files->file_lock); | |
170 | fput(file); | |
171 | goto out; | |
172 | } | |
173 | ||
174 | asmlinkage long sys_dup(unsigned int fildes) | |
175 | { | |
176 | int ret = -EBADF; | |
177 | struct file * file = fget(fildes); | |
178 | ||
179 | if (file) | |
180 | ret = dupfd(file, 0); | |
181 | return ret; | |
182 | } | |
183 | ||
184 | #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | O_DIRECT | O_NOATIME) | |
185 | ||
186 | static int setfl(int fd, struct file * filp, unsigned long arg) | |
187 | { | |
188 | struct inode * inode = filp->f_dentry->d_inode; | |
189 | int error = 0; | |
190 | ||
191 | /* O_APPEND cannot be cleared if the file is marked as append-only */ | |
192 | if (!(arg & O_APPEND) && IS_APPEND(inode)) | |
193 | return -EPERM; | |
194 | ||
195 | /* O_NOATIME can only be set by the owner or superuser */ | |
196 | if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) | |
197 | if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER)) | |
198 | return -EPERM; | |
199 | ||
200 | /* required for strict SunOS emulation */ | |
201 | if (O_NONBLOCK != O_NDELAY) | |
202 | if (arg & O_NDELAY) | |
203 | arg |= O_NONBLOCK; | |
204 | ||
205 | if (arg & O_DIRECT) { | |
206 | if (!filp->f_mapping || !filp->f_mapping->a_ops || | |
207 | !filp->f_mapping->a_ops->direct_IO) | |
208 | return -EINVAL; | |
209 | } | |
210 | ||
211 | if (filp->f_op && filp->f_op->check_flags) | |
212 | error = filp->f_op->check_flags(arg); | |
213 | if (error) | |
214 | return error; | |
215 | ||
216 | lock_kernel(); | |
217 | if ((arg ^ filp->f_flags) & FASYNC) { | |
218 | if (filp->f_op && filp->f_op->fasync) { | |
219 | error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); | |
220 | if (error < 0) | |
221 | goto out; | |
222 | } | |
223 | } | |
224 | ||
225 | filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); | |
226 | out: | |
227 | unlock_kernel(); | |
228 | return error; | |
229 | } | |
230 | ||
231 | static void f_modown(struct file *filp, unsigned long pid, | |
232 | uid_t uid, uid_t euid, int force) | |
233 | { | |
234 | write_lock_irq(&filp->f_owner.lock); | |
235 | if (force || !filp->f_owner.pid) { | |
236 | filp->f_owner.pid = pid; | |
237 | filp->f_owner.uid = uid; | |
238 | filp->f_owner.euid = euid; | |
239 | } | |
240 | write_unlock_irq(&filp->f_owner.lock); | |
241 | } | |
242 | ||
243 | int f_setown(struct file *filp, unsigned long arg, int force) | |
244 | { | |
245 | int err; | |
246 | ||
247 | err = security_file_set_fowner(filp); | |
248 | if (err) | |
249 | return err; | |
250 | ||
251 | f_modown(filp, arg, current->uid, current->euid, force); | |
252 | return 0; | |
253 | } | |
254 | ||
255 | EXPORT_SYMBOL(f_setown); | |
256 | ||
257 | void f_delown(struct file *filp) | |
258 | { | |
259 | f_modown(filp, 0, 0, 0, 1); | |
260 | } | |
261 | ||
262 | static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, | |
263 | struct file *filp) | |
264 | { | |
265 | long err = -EINVAL; | |
266 | ||
267 | switch (cmd) { | |
268 | case F_DUPFD: | |
269 | get_file(filp); | |
270 | err = dupfd(filp, arg); | |
271 | break; | |
272 | case F_GETFD: | |
273 | err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; | |
274 | break; | |
275 | case F_SETFD: | |
276 | err = 0; | |
277 | set_close_on_exec(fd, arg & FD_CLOEXEC); | |
278 | break; | |
279 | case F_GETFL: | |
280 | err = filp->f_flags; | |
281 | break; | |
282 | case F_SETFL: | |
283 | err = setfl(fd, filp, arg); | |
284 | break; | |
285 | case F_GETLK: | |
286 | err = fcntl_getlk(filp, (struct flock __user *) arg); | |
287 | break; | |
288 | case F_SETLK: | |
289 | case F_SETLKW: | |
290 | err = fcntl_setlk(filp, cmd, (struct flock __user *) arg); | |
291 | break; | |
292 | case F_GETOWN: | |
293 | /* | |
294 | * XXX If f_owner is a process group, the | |
295 | * negative return value will get converted | |
296 | * into an error. Oops. If we keep the | |
297 | * current syscall conventions, the only way | |
298 | * to fix this will be in libc. | |
299 | */ | |
300 | err = filp->f_owner.pid; | |
301 | force_successful_syscall_return(); | |
302 | break; | |
303 | case F_SETOWN: | |
304 | err = f_setown(filp, arg, 1); | |
305 | break; | |
306 | case F_GETSIG: | |
307 | err = filp->f_owner.signum; | |
308 | break; | |
309 | case F_SETSIG: | |
310 | /* arg == 0 restores default behaviour. */ | |
311 | if (arg < 0 || arg > _NSIG) { | |
312 | break; | |
313 | } | |
314 | err = 0; | |
315 | filp->f_owner.signum = arg; | |
316 | break; | |
317 | case F_GETLEASE: | |
318 | err = fcntl_getlease(filp); | |
319 | break; | |
320 | case F_SETLEASE: | |
321 | err = fcntl_setlease(fd, filp, arg); | |
322 | break; | |
323 | case F_NOTIFY: | |
324 | err = fcntl_dirnotify(fd, filp, arg); | |
325 | break; | |
326 | default: | |
327 | break; | |
328 | } | |
329 | return err; | |
330 | } | |
331 | ||
332 | asmlinkage long sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg) | |
333 | { | |
334 | struct file *filp; | |
335 | long err = -EBADF; | |
336 | ||
337 | filp = fget(fd); | |
338 | if (!filp) | |
339 | goto out; | |
340 | ||
341 | err = security_file_fcntl(filp, cmd, arg); | |
342 | if (err) { | |
343 | fput(filp); | |
344 | return err; | |
345 | } | |
346 | ||
347 | err = do_fcntl(fd, cmd, arg, filp); | |
348 | ||
349 | fput(filp); | |
350 | out: | |
351 | return err; | |
352 | } | |
353 | ||
354 | #if BITS_PER_LONG == 32 | |
355 | asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg) | |
356 | { | |
357 | struct file * filp; | |
358 | long err; | |
359 | ||
360 | err = -EBADF; | |
361 | filp = fget(fd); | |
362 | if (!filp) | |
363 | goto out; | |
364 | ||
365 | err = security_file_fcntl(filp, cmd, arg); | |
366 | if (err) { | |
367 | fput(filp); | |
368 | return err; | |
369 | } | |
370 | err = -EBADF; | |
371 | ||
372 | switch (cmd) { | |
373 | case F_GETLK64: | |
374 | err = fcntl_getlk64(filp, (struct flock64 __user *) arg); | |
375 | break; | |
376 | case F_SETLK64: | |
377 | case F_SETLKW64: | |
378 | err = fcntl_setlk64(filp, cmd, (struct flock64 __user *) arg); | |
379 | break; | |
380 | default: | |
381 | err = do_fcntl(fd, cmd, arg, filp); | |
382 | break; | |
383 | } | |
384 | fput(filp); | |
385 | out: | |
386 | return err; | |
387 | } | |
388 | #endif | |
389 | ||
390 | /* Table to convert sigio signal codes into poll band bitmaps */ | |
391 | ||
392 | static long band_table[NSIGPOLL] = { | |
393 | POLLIN | POLLRDNORM, /* POLL_IN */ | |
394 | POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */ | |
395 | POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */ | |
396 | POLLERR, /* POLL_ERR */ | |
397 | POLLPRI | POLLRDBAND, /* POLL_PRI */ | |
398 | POLLHUP | POLLERR /* POLL_HUP */ | |
399 | }; | |
400 | ||
401 | static inline int sigio_perm(struct task_struct *p, | |
402 | struct fown_struct *fown, int sig) | |
403 | { | |
404 | return (((fown->euid == 0) || | |
405 | (fown->euid == p->suid) || (fown->euid == p->uid) || | |
406 | (fown->uid == p->suid) || (fown->uid == p->uid)) && | |
407 | !security_file_send_sigiotask(p, fown, sig)); | |
408 | } | |
409 | ||
410 | static void send_sigio_to_task(struct task_struct *p, | |
411 | struct fown_struct *fown, | |
412 | int fd, | |
413 | int reason) | |
414 | { | |
415 | if (!sigio_perm(p, fown, fown->signum)) | |
416 | return; | |
417 | ||
418 | switch (fown->signum) { | |
419 | siginfo_t si; | |
420 | default: | |
421 | /* Queue a rt signal with the appropriate fd as its | |
422 | value. We use SI_SIGIO as the source, not | |
423 | SI_KERNEL, since kernel signals always get | |
424 | delivered even if we can't queue. Failure to | |
425 | queue in this case _should_ be reported; we fall | |
426 | back to SIGIO in that case. --sct */ | |
427 | si.si_signo = fown->signum; | |
428 | si.si_errno = 0; | |
429 | si.si_code = reason; | |
430 | /* Make sure we are called with one of the POLL_* | |
431 | reasons, otherwise we could leak kernel stack into | |
432 | userspace. */ | |
433 | if ((reason & __SI_MASK) != __SI_POLL) | |
434 | BUG(); | |
435 | if (reason - POLL_IN >= NSIGPOLL) | |
436 | si.si_band = ~0L; | |
437 | else | |
438 | si.si_band = band_table[reason - POLL_IN]; | |
439 | si.si_fd = fd; | |
fc9c9ab2 | 440 | if (!send_group_sig_info(fown->signum, &si, p)) |
1da177e4 LT |
441 | break; |
442 | /* fall-through: fall back on the old plain SIGIO signal */ | |
443 | case 0: | |
444 | send_group_sig_info(SIGIO, SEND_SIG_PRIV, p); | |
445 | } | |
446 | } | |
447 | ||
448 | void send_sigio(struct fown_struct *fown, int fd, int band) | |
449 | { | |
450 | struct task_struct *p; | |
451 | int pid; | |
452 | ||
453 | read_lock(&fown->lock); | |
454 | pid = fown->pid; | |
455 | if (!pid) | |
456 | goto out_unlock_fown; | |
457 | ||
458 | read_lock(&tasklist_lock); | |
459 | if (pid > 0) { | |
460 | p = find_task_by_pid(pid); | |
461 | if (p) { | |
462 | send_sigio_to_task(p, fown, fd, band); | |
463 | } | |
464 | } else { | |
465 | do_each_task_pid(-pid, PIDTYPE_PGID, p) { | |
466 | send_sigio_to_task(p, fown, fd, band); | |
467 | } while_each_task_pid(-pid, PIDTYPE_PGID, p); | |
468 | } | |
469 | read_unlock(&tasklist_lock); | |
470 | out_unlock_fown: | |
471 | read_unlock(&fown->lock); | |
472 | } | |
473 | ||
474 | static void send_sigurg_to_task(struct task_struct *p, | |
475 | struct fown_struct *fown) | |
476 | { | |
477 | if (sigio_perm(p, fown, SIGURG)) | |
478 | send_group_sig_info(SIGURG, SEND_SIG_PRIV, p); | |
479 | } | |
480 | ||
481 | int send_sigurg(struct fown_struct *fown) | |
482 | { | |
483 | struct task_struct *p; | |
484 | int pid, ret = 0; | |
485 | ||
486 | read_lock(&fown->lock); | |
487 | pid = fown->pid; | |
488 | if (!pid) | |
489 | goto out_unlock_fown; | |
490 | ||
491 | ret = 1; | |
492 | ||
493 | read_lock(&tasklist_lock); | |
494 | if (pid > 0) { | |
495 | p = find_task_by_pid(pid); | |
496 | if (p) { | |
497 | send_sigurg_to_task(p, fown); | |
498 | } | |
499 | } else { | |
500 | do_each_task_pid(-pid, PIDTYPE_PGID, p) { | |
501 | send_sigurg_to_task(p, fown); | |
502 | } while_each_task_pid(-pid, PIDTYPE_PGID, p); | |
503 | } | |
504 | read_unlock(&tasklist_lock); | |
505 | out_unlock_fown: | |
506 | read_unlock(&fown->lock); | |
507 | return ret; | |
508 | } | |
509 | ||
510 | static DEFINE_RWLOCK(fasync_lock); | |
511 | static kmem_cache_t *fasync_cache; | |
512 | ||
513 | /* | |
514 | * fasync_helper() is used by some character device drivers (mainly mice) | |
515 | * to set up the fasync queue. It returns negative on error, 0 if it did | |
516 | * no changes and positive if it added/deleted the entry. | |
517 | */ | |
518 | int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) | |
519 | { | |
520 | struct fasync_struct *fa, **fp; | |
521 | struct fasync_struct *new = NULL; | |
522 | int result = 0; | |
523 | ||
524 | if (on) { | |
525 | new = kmem_cache_alloc(fasync_cache, SLAB_KERNEL); | |
526 | if (!new) | |
527 | return -ENOMEM; | |
528 | } | |
529 | write_lock_irq(&fasync_lock); | |
530 | for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { | |
531 | if (fa->fa_file == filp) { | |
532 | if(on) { | |
533 | fa->fa_fd = fd; | |
534 | kmem_cache_free(fasync_cache, new); | |
535 | } else { | |
536 | *fp = fa->fa_next; | |
537 | kmem_cache_free(fasync_cache, fa); | |
538 | result = 1; | |
539 | } | |
540 | goto out; | |
541 | } | |
542 | } | |
543 | ||
544 | if (on) { | |
545 | new->magic = FASYNC_MAGIC; | |
546 | new->fa_file = filp; | |
547 | new->fa_fd = fd; | |
548 | new->fa_next = *fapp; | |
549 | *fapp = new; | |
550 | result = 1; | |
551 | } | |
552 | out: | |
553 | write_unlock_irq(&fasync_lock); | |
554 | return result; | |
555 | } | |
556 | ||
557 | EXPORT_SYMBOL(fasync_helper); | |
558 | ||
559 | void __kill_fasync(struct fasync_struct *fa, int sig, int band) | |
560 | { | |
561 | while (fa) { | |
562 | struct fown_struct * fown; | |
563 | if (fa->magic != FASYNC_MAGIC) { | |
564 | printk(KERN_ERR "kill_fasync: bad magic number in " | |
565 | "fasync_struct!\n"); | |
566 | return; | |
567 | } | |
568 | fown = &fa->fa_file->f_owner; | |
569 | /* Don't send SIGURG to processes which have not set a | |
570 | queued signum: SIGURG has its own default signalling | |
571 | mechanism. */ | |
572 | if (!(sig == SIGURG && fown->signum == 0)) | |
573 | send_sigio(fown, fa->fa_fd, band); | |
574 | fa = fa->fa_next; | |
575 | } | |
576 | } | |
577 | ||
578 | EXPORT_SYMBOL(__kill_fasync); | |
579 | ||
580 | void kill_fasync(struct fasync_struct **fp, int sig, int band) | |
581 | { | |
582 | /* First a quick test without locking: usually | |
583 | * the list is empty. | |
584 | */ | |
585 | if (*fp) { | |
586 | read_lock(&fasync_lock); | |
587 | /* reread *fp after obtaining the lock */ | |
588 | __kill_fasync(*fp, sig, band); | |
589 | read_unlock(&fasync_lock); | |
590 | } | |
591 | } | |
592 | EXPORT_SYMBOL(kill_fasync); | |
593 | ||
594 | static int __init fasync_init(void) | |
595 | { | |
596 | fasync_cache = kmem_cache_create("fasync_cache", | |
597 | sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL, NULL); | |
598 | return 0; | |
599 | } | |
600 | ||
601 | module_init(fasync_init) |