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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> | |
7ed20e1a | 18 | #include <linux/signal.h> |
1da177e4 LT |
19 | |
20 | #include <asm/poll.h> | |
21 | #include <asm/siginfo.h> | |
22 | #include <asm/uaccess.h> | |
23 | ||
24 | void fastcall set_close_on_exec(unsigned int fd, int flag) | |
25 | { | |
26 | struct files_struct *files = current->files; | |
27 | spin_lock(&files->file_lock); | |
28 | if (flag) | |
29 | FD_SET(fd, files->close_on_exec); | |
30 | else | |
31 | FD_CLR(fd, files->close_on_exec); | |
32 | spin_unlock(&files->file_lock); | |
33 | } | |
34 | ||
35 | static inline int get_close_on_exec(unsigned int fd) | |
36 | { | |
37 | struct files_struct *files = current->files; | |
38 | int res; | |
39 | spin_lock(&files->file_lock); | |
40 | res = FD_ISSET(fd, files->close_on_exec); | |
41 | spin_unlock(&files->file_lock); | |
42 | return res; | |
43 | } | |
44 | ||
45 | /* | |
46 | * locate_fd finds a free file descriptor in the open_fds fdset, | |
47 | * expanding the fd arrays if necessary. Must be called with the | |
48 | * file_lock held for write. | |
49 | */ | |
50 | ||
51 | static int locate_fd(struct files_struct *files, | |
52 | struct file *file, unsigned int orig_start) | |
53 | { | |
54 | unsigned int newfd; | |
55 | unsigned int start; | |
56 | int error; | |
57 | ||
58 | error = -EINVAL; | |
59 | if (orig_start >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
60 | goto out; | |
61 | ||
62 | repeat: | |
63 | /* | |
64 | * Someone might have closed fd's in the range | |
65 | * orig_start..files->next_fd | |
66 | */ | |
67 | start = orig_start; | |
68 | if (start < files->next_fd) | |
69 | start = files->next_fd; | |
70 | ||
71 | newfd = start; | |
72 | if (start < files->max_fdset) { | |
73 | newfd = find_next_zero_bit(files->open_fds->fds_bits, | |
74 | files->max_fdset, start); | |
75 | } | |
76 | ||
77 | error = -EMFILE; | |
78 | if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
79 | goto out; | |
80 | ||
81 | error = expand_files(files, newfd); | |
82 | if (error < 0) | |
83 | goto out; | |
84 | ||
85 | /* | |
86 | * If we needed to expand the fs array we | |
87 | * might have blocked - try again. | |
88 | */ | |
89 | if (error) | |
90 | goto repeat; | |
91 | ||
92 | if (start <= files->next_fd) | |
93 | files->next_fd = newfd + 1; | |
94 | ||
95 | error = newfd; | |
96 | ||
97 | out: | |
98 | return error; | |
99 | } | |
100 | ||
101 | static int dupfd(struct file *file, unsigned int start) | |
102 | { | |
103 | struct files_struct * files = current->files; | |
104 | int fd; | |
105 | ||
106 | spin_lock(&files->file_lock); | |
107 | fd = locate_fd(files, file, start); | |
108 | if (fd >= 0) { | |
109 | FD_SET(fd, files->open_fds); | |
110 | FD_CLR(fd, files->close_on_exec); | |
111 | spin_unlock(&files->file_lock); | |
112 | fd_install(fd, file); | |
113 | } else { | |
114 | spin_unlock(&files->file_lock); | |
115 | fput(file); | |
116 | } | |
117 | ||
118 | return fd; | |
119 | } | |
120 | ||
121 | asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd) | |
122 | { | |
123 | int err = -EBADF; | |
124 | struct file * file, *tofree; | |
125 | struct files_struct * files = current->files; | |
126 | ||
127 | spin_lock(&files->file_lock); | |
128 | if (!(file = fcheck(oldfd))) | |
129 | goto out_unlock; | |
130 | err = newfd; | |
131 | if (newfd == oldfd) | |
132 | goto out_unlock; | |
133 | err = -EBADF; | |
134 | if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
135 | goto out_unlock; | |
136 | get_file(file); /* We are now finished with oldfd */ | |
137 | ||
138 | err = expand_files(files, newfd); | |
139 | if (err < 0) | |
140 | goto out_fput; | |
141 | ||
142 | /* To avoid races with open() and dup(), we will mark the fd as | |
143 | * in-use in the open-file bitmap throughout the entire dup2() | |
144 | * process. This is quite safe: do_close() uses the fd array | |
145 | * entry, not the bitmap, to decide what work needs to be | |
146 | * done. --sct */ | |
147 | /* Doesn't work. open() might be there first. --AV */ | |
148 | ||
149 | /* Yes. It's a race. In user space. Nothing sane to do */ | |
150 | err = -EBUSY; | |
151 | tofree = files->fd[newfd]; | |
152 | if (!tofree && FD_ISSET(newfd, files->open_fds)) | |
153 | goto out_fput; | |
154 | ||
155 | files->fd[newfd] = file; | |
156 | FD_SET(newfd, files->open_fds); | |
157 | FD_CLR(newfd, files->close_on_exec); | |
158 | spin_unlock(&files->file_lock); | |
159 | ||
160 | if (tofree) | |
161 | filp_close(tofree, files); | |
162 | err = newfd; | |
163 | out: | |
164 | return err; | |
165 | out_unlock: | |
166 | spin_unlock(&files->file_lock); | |
167 | goto out; | |
168 | ||
169 | out_fput: | |
170 | spin_unlock(&files->file_lock); | |
171 | fput(file); | |
172 | goto out; | |
173 | } | |
174 | ||
175 | asmlinkage long sys_dup(unsigned int fildes) | |
176 | { | |
177 | int ret = -EBADF; | |
178 | struct file * file = fget(fildes); | |
179 | ||
180 | if (file) | |
181 | ret = dupfd(file, 0); | |
182 | return ret; | |
183 | } | |
184 | ||
185 | #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | O_DIRECT | O_NOATIME) | |
186 | ||
187 | static int setfl(int fd, struct file * filp, unsigned long arg) | |
188 | { | |
189 | struct inode * inode = filp->f_dentry->d_inode; | |
190 | int error = 0; | |
191 | ||
192 | /* O_APPEND cannot be cleared if the file is marked as append-only */ | |
193 | if (!(arg & O_APPEND) && IS_APPEND(inode)) | |
194 | return -EPERM; | |
195 | ||
196 | /* O_NOATIME can only be set by the owner or superuser */ | |
197 | if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) | |
198 | if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER)) | |
199 | return -EPERM; | |
200 | ||
201 | /* required for strict SunOS emulation */ | |
202 | if (O_NONBLOCK != O_NDELAY) | |
203 | if (arg & O_NDELAY) | |
204 | arg |= O_NONBLOCK; | |
205 | ||
206 | if (arg & O_DIRECT) { | |
207 | if (!filp->f_mapping || !filp->f_mapping->a_ops || | |
208 | !filp->f_mapping->a_ops->direct_IO) | |
209 | return -EINVAL; | |
210 | } | |
211 | ||
212 | if (filp->f_op && filp->f_op->check_flags) | |
213 | error = filp->f_op->check_flags(arg); | |
214 | if (error) | |
215 | return error; | |
216 | ||
217 | lock_kernel(); | |
218 | if ((arg ^ filp->f_flags) & FASYNC) { | |
219 | if (filp->f_op && filp->f_op->fasync) { | |
220 | error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); | |
221 | if (error < 0) | |
222 | goto out; | |
223 | } | |
224 | } | |
225 | ||
226 | filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); | |
227 | out: | |
228 | unlock_kernel(); | |
229 | return error; | |
230 | } | |
231 | ||
232 | static void f_modown(struct file *filp, unsigned long pid, | |
233 | uid_t uid, uid_t euid, int force) | |
234 | { | |
235 | write_lock_irq(&filp->f_owner.lock); | |
236 | if (force || !filp->f_owner.pid) { | |
237 | filp->f_owner.pid = pid; | |
238 | filp->f_owner.uid = uid; | |
239 | filp->f_owner.euid = euid; | |
240 | } | |
241 | write_unlock_irq(&filp->f_owner.lock); | |
242 | } | |
243 | ||
244 | int f_setown(struct file *filp, unsigned long arg, int force) | |
245 | { | |
246 | int err; | |
247 | ||
248 | err = security_file_set_fowner(filp); | |
249 | if (err) | |
250 | return err; | |
251 | ||
252 | f_modown(filp, arg, current->uid, current->euid, force); | |
253 | return 0; | |
254 | } | |
255 | ||
256 | EXPORT_SYMBOL(f_setown); | |
257 | ||
258 | void f_delown(struct file *filp) | |
259 | { | |
260 | f_modown(filp, 0, 0, 0, 1); | |
261 | } | |
262 | ||
263 | static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, | |
264 | struct file *filp) | |
265 | { | |
266 | long err = -EINVAL; | |
267 | ||
268 | switch (cmd) { | |
269 | case F_DUPFD: | |
270 | get_file(filp); | |
271 | err = dupfd(filp, arg); | |
272 | break; | |
273 | case F_GETFD: | |
274 | err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; | |
275 | break; | |
276 | case F_SETFD: | |
277 | err = 0; | |
278 | set_close_on_exec(fd, arg & FD_CLOEXEC); | |
279 | break; | |
280 | case F_GETFL: | |
281 | err = filp->f_flags; | |
282 | break; | |
283 | case F_SETFL: | |
284 | err = setfl(fd, filp, arg); | |
285 | break; | |
286 | case F_GETLK: | |
287 | err = fcntl_getlk(filp, (struct flock __user *) arg); | |
288 | break; | |
289 | case F_SETLK: | |
290 | case F_SETLKW: | |
291 | err = fcntl_setlk(filp, cmd, (struct flock __user *) arg); | |
292 | break; | |
293 | case F_GETOWN: | |
294 | /* | |
295 | * XXX If f_owner is a process group, the | |
296 | * negative return value will get converted | |
297 | * into an error. Oops. If we keep the | |
298 | * current syscall conventions, the only way | |
299 | * to fix this will be in libc. | |
300 | */ | |
301 | err = filp->f_owner.pid; | |
302 | force_successful_syscall_return(); | |
303 | break; | |
304 | case F_SETOWN: | |
305 | err = f_setown(filp, arg, 1); | |
306 | break; | |
307 | case F_GETSIG: | |
308 | err = filp->f_owner.signum; | |
309 | break; | |
310 | case F_SETSIG: | |
311 | /* arg == 0 restores default behaviour. */ | |
7ed20e1a | 312 | if (!valid_signal(arg)) { |
1da177e4 LT |
313 | break; |
314 | } | |
315 | err = 0; | |
316 | filp->f_owner.signum = arg; | |
317 | break; | |
318 | case F_GETLEASE: | |
319 | err = fcntl_getlease(filp); | |
320 | break; | |
321 | case F_SETLEASE: | |
322 | err = fcntl_setlease(fd, filp, arg); | |
323 | break; | |
324 | case F_NOTIFY: | |
325 | err = fcntl_dirnotify(fd, filp, arg); | |
326 | break; | |
327 | default: | |
328 | break; | |
329 | } | |
330 | return err; | |
331 | } | |
332 | ||
333 | asmlinkage long sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg) | |
334 | { | |
335 | struct file *filp; | |
336 | long err = -EBADF; | |
337 | ||
338 | filp = fget(fd); | |
339 | if (!filp) | |
340 | goto out; | |
341 | ||
342 | err = security_file_fcntl(filp, cmd, arg); | |
343 | if (err) { | |
344 | fput(filp); | |
345 | return err; | |
346 | } | |
347 | ||
348 | err = do_fcntl(fd, cmd, arg, filp); | |
349 | ||
350 | fput(filp); | |
351 | out: | |
352 | return err; | |
353 | } | |
354 | ||
355 | #if BITS_PER_LONG == 32 | |
356 | asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg) | |
357 | { | |
358 | struct file * filp; | |
359 | long err; | |
360 | ||
361 | err = -EBADF; | |
362 | filp = fget(fd); | |
363 | if (!filp) | |
364 | goto out; | |
365 | ||
366 | err = security_file_fcntl(filp, cmd, arg); | |
367 | if (err) { | |
368 | fput(filp); | |
369 | return err; | |
370 | } | |
371 | err = -EBADF; | |
372 | ||
373 | switch (cmd) { | |
374 | case F_GETLK64: | |
375 | err = fcntl_getlk64(filp, (struct flock64 __user *) arg); | |
376 | break; | |
377 | case F_SETLK64: | |
378 | case F_SETLKW64: | |
379 | err = fcntl_setlk64(filp, cmd, (struct flock64 __user *) arg); | |
380 | break; | |
381 | default: | |
382 | err = do_fcntl(fd, cmd, arg, filp); | |
383 | break; | |
384 | } | |
385 | fput(filp); | |
386 | out: | |
387 | return err; | |
388 | } | |
389 | #endif | |
390 | ||
391 | /* Table to convert sigio signal codes into poll band bitmaps */ | |
392 | ||
393 | static long band_table[NSIGPOLL] = { | |
394 | POLLIN | POLLRDNORM, /* POLL_IN */ | |
395 | POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */ | |
396 | POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */ | |
397 | POLLERR, /* POLL_ERR */ | |
398 | POLLPRI | POLLRDBAND, /* POLL_PRI */ | |
399 | POLLHUP | POLLERR /* POLL_HUP */ | |
400 | }; | |
401 | ||
402 | static inline int sigio_perm(struct task_struct *p, | |
403 | struct fown_struct *fown, int sig) | |
404 | { | |
405 | return (((fown->euid == 0) || | |
406 | (fown->euid == p->suid) || (fown->euid == p->uid) || | |
407 | (fown->uid == p->suid) || (fown->uid == p->uid)) && | |
408 | !security_file_send_sigiotask(p, fown, sig)); | |
409 | } | |
410 | ||
411 | static void send_sigio_to_task(struct task_struct *p, | |
412 | struct fown_struct *fown, | |
413 | int fd, | |
414 | int reason) | |
415 | { | |
416 | if (!sigio_perm(p, fown, fown->signum)) | |
417 | return; | |
418 | ||
419 | switch (fown->signum) { | |
420 | siginfo_t si; | |
421 | default: | |
422 | /* Queue a rt signal with the appropriate fd as its | |
423 | value. We use SI_SIGIO as the source, not | |
424 | SI_KERNEL, since kernel signals always get | |
425 | delivered even if we can't queue. Failure to | |
426 | queue in this case _should_ be reported; we fall | |
427 | back to SIGIO in that case. --sct */ | |
428 | si.si_signo = fown->signum; | |
429 | si.si_errno = 0; | |
430 | si.si_code = reason; | |
431 | /* Make sure we are called with one of the POLL_* | |
432 | reasons, otherwise we could leak kernel stack into | |
433 | userspace. */ | |
434 | if ((reason & __SI_MASK) != __SI_POLL) | |
435 | BUG(); | |
436 | if (reason - POLL_IN >= NSIGPOLL) | |
437 | si.si_band = ~0L; | |
438 | else | |
439 | si.si_band = band_table[reason - POLL_IN]; | |
440 | si.si_fd = fd; | |
fc9c9ab2 | 441 | if (!send_group_sig_info(fown->signum, &si, p)) |
1da177e4 LT |
442 | break; |
443 | /* fall-through: fall back on the old plain SIGIO signal */ | |
444 | case 0: | |
445 | send_group_sig_info(SIGIO, SEND_SIG_PRIV, p); | |
446 | } | |
447 | } | |
448 | ||
449 | void send_sigio(struct fown_struct *fown, int fd, int band) | |
450 | { | |
451 | struct task_struct *p; | |
452 | int pid; | |
453 | ||
454 | read_lock(&fown->lock); | |
455 | pid = fown->pid; | |
456 | if (!pid) | |
457 | goto out_unlock_fown; | |
458 | ||
459 | read_lock(&tasklist_lock); | |
460 | if (pid > 0) { | |
461 | p = find_task_by_pid(pid); | |
462 | if (p) { | |
463 | send_sigio_to_task(p, fown, fd, band); | |
464 | } | |
465 | } else { | |
466 | do_each_task_pid(-pid, PIDTYPE_PGID, p) { | |
467 | send_sigio_to_task(p, fown, fd, band); | |
468 | } while_each_task_pid(-pid, PIDTYPE_PGID, p); | |
469 | } | |
470 | read_unlock(&tasklist_lock); | |
471 | out_unlock_fown: | |
472 | read_unlock(&fown->lock); | |
473 | } | |
474 | ||
475 | static void send_sigurg_to_task(struct task_struct *p, | |
476 | struct fown_struct *fown) | |
477 | { | |
478 | if (sigio_perm(p, fown, SIGURG)) | |
479 | send_group_sig_info(SIGURG, SEND_SIG_PRIV, p); | |
480 | } | |
481 | ||
482 | int send_sigurg(struct fown_struct *fown) | |
483 | { | |
484 | struct task_struct *p; | |
485 | int pid, ret = 0; | |
486 | ||
487 | read_lock(&fown->lock); | |
488 | pid = fown->pid; | |
489 | if (!pid) | |
490 | goto out_unlock_fown; | |
491 | ||
492 | ret = 1; | |
493 | ||
494 | read_lock(&tasklist_lock); | |
495 | if (pid > 0) { | |
496 | p = find_task_by_pid(pid); | |
497 | if (p) { | |
498 | send_sigurg_to_task(p, fown); | |
499 | } | |
500 | } else { | |
501 | do_each_task_pid(-pid, PIDTYPE_PGID, p) { | |
502 | send_sigurg_to_task(p, fown); | |
503 | } while_each_task_pid(-pid, PIDTYPE_PGID, p); | |
504 | } | |
505 | read_unlock(&tasklist_lock); | |
506 | out_unlock_fown: | |
507 | read_unlock(&fown->lock); | |
508 | return ret; | |
509 | } | |
510 | ||
511 | static DEFINE_RWLOCK(fasync_lock); | |
512 | static kmem_cache_t *fasync_cache; | |
513 | ||
514 | /* | |
515 | * fasync_helper() is used by some character device drivers (mainly mice) | |
516 | * to set up the fasync queue. It returns negative on error, 0 if it did | |
517 | * no changes and positive if it added/deleted the entry. | |
518 | */ | |
519 | int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) | |
520 | { | |
521 | struct fasync_struct *fa, **fp; | |
522 | struct fasync_struct *new = NULL; | |
523 | int result = 0; | |
524 | ||
525 | if (on) { | |
526 | new = kmem_cache_alloc(fasync_cache, SLAB_KERNEL); | |
527 | if (!new) | |
528 | return -ENOMEM; | |
529 | } | |
530 | write_lock_irq(&fasync_lock); | |
531 | for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { | |
532 | if (fa->fa_file == filp) { | |
533 | if(on) { | |
534 | fa->fa_fd = fd; | |
535 | kmem_cache_free(fasync_cache, new); | |
536 | } else { | |
537 | *fp = fa->fa_next; | |
538 | kmem_cache_free(fasync_cache, fa); | |
539 | result = 1; | |
540 | } | |
541 | goto out; | |
542 | } | |
543 | } | |
544 | ||
545 | if (on) { | |
546 | new->magic = FASYNC_MAGIC; | |
547 | new->fa_file = filp; | |
548 | new->fa_fd = fd; | |
549 | new->fa_next = *fapp; | |
550 | *fapp = new; | |
551 | result = 1; | |
552 | } | |
553 | out: | |
554 | write_unlock_irq(&fasync_lock); | |
555 | return result; | |
556 | } | |
557 | ||
558 | EXPORT_SYMBOL(fasync_helper); | |
559 | ||
560 | void __kill_fasync(struct fasync_struct *fa, int sig, int band) | |
561 | { | |
562 | while (fa) { | |
563 | struct fown_struct * fown; | |
564 | if (fa->magic != FASYNC_MAGIC) { | |
565 | printk(KERN_ERR "kill_fasync: bad magic number in " | |
566 | "fasync_struct!\n"); | |
567 | return; | |
568 | } | |
569 | fown = &fa->fa_file->f_owner; | |
570 | /* Don't send SIGURG to processes which have not set a | |
571 | queued signum: SIGURG has its own default signalling | |
572 | mechanism. */ | |
573 | if (!(sig == SIGURG && fown->signum == 0)) | |
574 | send_sigio(fown, fa->fa_fd, band); | |
575 | fa = fa->fa_next; | |
576 | } | |
577 | } | |
578 | ||
579 | EXPORT_SYMBOL(__kill_fasync); | |
580 | ||
581 | void kill_fasync(struct fasync_struct **fp, int sig, int band) | |
582 | { | |
583 | /* First a quick test without locking: usually | |
584 | * the list is empty. | |
585 | */ | |
586 | if (*fp) { | |
587 | read_lock(&fasync_lock); | |
588 | /* reread *fp after obtaining the lock */ | |
589 | __kill_fasync(*fp, sig, band); | |
590 | read_unlock(&fasync_lock); | |
591 | } | |
592 | } | |
593 | EXPORT_SYMBOL(kill_fasync); | |
594 | ||
595 | static int __init fasync_init(void) | |
596 | { | |
597 | fasync_cache = kmem_cache_create("fasync_cache", | |
598 | sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL, NULL); | |
599 | return 0; | |
600 | } | |
601 | ||
602 | module_init(fasync_init) |