Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/fcntl.c
Parent Directory | Revision Log
Revision 630 -
(show annotations)
(download)
Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 13410 byte(s)
Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 13410 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | #include <linux/signal.h> |
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. */ |
312 | if (!valid_signal(arg)) { |
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; |
441 | if (!send_group_sig_info(fown->signum, &si, p)) |
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) |