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CommitLineData
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>
9f3acc31 12#include <linux/fdtable.h>
16f7e0fe 13#include <linux/capability.h>
1da177e4 14#include <linux/dnotify.h>
1da177e4
LT
15#include <linux/slab.h>
16#include <linux/module.h>
17#include <linux/security.h>
18#include <linux/ptrace.h>
7ed20e1a 19#include <linux/signal.h>
ab2af1f5 20#include <linux/rcupdate.h>
b488893a 21#include <linux/pid_namespace.h>
1da177e4
LT
22
23#include <asm/poll.h>
24#include <asm/siginfo.h>
25#include <asm/uaccess.h>
26
fc9b52cd 27void set_close_on_exec(unsigned int fd, int flag)
1da177e4
LT
28{
29 struct files_struct *files = current->files;
badf1662 30 struct fdtable *fdt;
1da177e4 31 spin_lock(&files->file_lock);
badf1662 32 fdt = files_fdtable(files);
1da177e4 33 if (flag)
badf1662 34 FD_SET(fd, fdt->close_on_exec);
1da177e4 35 else
badf1662 36 FD_CLR(fd, fdt->close_on_exec);
1da177e4
LT
37 spin_unlock(&files->file_lock);
38}
39
858119e1 40static int get_close_on_exec(unsigned int fd)
1da177e4
LT
41{
42 struct files_struct *files = current->files;
badf1662 43 struct fdtable *fdt;
1da177e4 44 int res;
b835996f 45 rcu_read_lock();
badf1662
DS
46 fdt = files_fdtable(files);
47 res = FD_ISSET(fd, fdt->close_on_exec);
b835996f 48 rcu_read_unlock();
1da177e4
LT
49 return res;
50}
51
336dd1f7 52asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags)
1da177e4
LT
53{
54 int err = -EBADF;
55 struct file * file, *tofree;
56 struct files_struct * files = current->files;
badf1662 57 struct fdtable *fdt;
1da177e4 58
336dd1f7
UD
59 if ((flags & ~O_CLOEXEC) != 0)
60 return -EINVAL;
61
6c5d0512
AV
62 if (unlikely(oldfd == newfd))
63 return -EINVAL;
64
1da177e4 65 spin_lock(&files->file_lock);
1da177e4 66 err = expand_files(files, newfd);
1b7e190b
AV
67 file = fcheck(oldfd);
68 if (unlikely(!file))
69 goto Ebadf;
4e1e018e
AV
70 if (unlikely(err < 0)) {
71 if (err == -EMFILE)
1b7e190b
AV
72 goto Ebadf;
73 goto out_unlock;
4e1e018e 74 }
1b7e190b
AV
75 /*
76 * We need to detect attempts to do dup2() over allocated but still
77 * not finished descriptor. NB: OpenBSD avoids that at the price of
78 * extra work in their equivalent of fget() - they insert struct
79 * file immediately after grabbing descriptor, mark it larval if
80 * more work (e.g. actual opening) is needed and make sure that
81 * fget() treats larval files as absent. Potentially interesting,
82 * but while extra work in fget() is trivial, locking implications
83 * and amount of surgery on open()-related paths in VFS are not.
84 * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
85 * deadlocks in rather amusing ways, AFAICS. All of that is out of
86 * scope of POSIX or SUS, since neither considers shared descriptor
87 * tables and this condition does not arise without those.
88 */
1da177e4 89 err = -EBUSY;
badf1662
DS
90 fdt = files_fdtable(files);
91 tofree = fdt->fd[newfd];
92 if (!tofree && FD_ISSET(newfd, fdt->open_fds))
1b7e190b
AV
93 goto out_unlock;
94 get_file(file);
ab2af1f5 95 rcu_assign_pointer(fdt->fd[newfd], file);
badf1662 96 FD_SET(newfd, fdt->open_fds);
336dd1f7
UD
97 if (flags & O_CLOEXEC)
98 FD_SET(newfd, fdt->close_on_exec);
99 else
100 FD_CLR(newfd, fdt->close_on_exec);
1da177e4
LT
101 spin_unlock(&files->file_lock);
102
103 if (tofree)
104 filp_close(tofree, files);
1da177e4 105
1b7e190b
AV
106 return newfd;
107
108Ebadf:
109 err = -EBADF;
110out_unlock:
1da177e4 111 spin_unlock(&files->file_lock);
1b7e190b 112 return err;
1da177e4 113}
336dd1f7
UD
114
115asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)
116{
6c5d0512
AV
117 if (unlikely(newfd == oldfd)) { /* corner case */
118 struct files_struct *files = current->files;
119 rcu_read_lock();
120 if (!fcheck_files(files, oldfd))
121 oldfd = -EBADF;
122 rcu_read_unlock();
123 return oldfd;
124 }
336dd1f7
UD
125 return sys_dup3(oldfd, newfd, 0);
126}
1da177e4
LT
127
128asmlinkage long sys_dup(unsigned int fildes)
129{
130 int ret = -EBADF;
1027abe8
AV
131 struct file *file = fget(fildes);
132
133 if (file) {
134 ret = get_unused_fd();
135 if (ret >= 0)
136 fd_install(ret, file);
137 else
138 fput(file);
139 }
1da177e4
LT
140 return ret;
141}
142
143#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | O_DIRECT | O_NOATIME)
144
145static int setfl(int fd, struct file * filp, unsigned long arg)
146{
0f7fc9e4 147 struct inode * inode = filp->f_path.dentry->d_inode;
1da177e4
LT
148 int error = 0;
149
7d95c8f2 150 /*
151 * O_APPEND cannot be cleared if the file is marked as append-only
152 * and the file is open for write.
153 */
154 if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
1da177e4
LT
155 return -EPERM;
156
157 /* O_NOATIME can only be set by the owner or superuser */
158 if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
3bd858ab 159 if (!is_owner_or_cap(inode))
1da177e4
LT
160 return -EPERM;
161
162 /* required for strict SunOS emulation */
163 if (O_NONBLOCK != O_NDELAY)
164 if (arg & O_NDELAY)
165 arg |= O_NONBLOCK;
166
167 if (arg & O_DIRECT) {
168 if (!filp->f_mapping || !filp->f_mapping->a_ops ||
169 !filp->f_mapping->a_ops->direct_IO)
170 return -EINVAL;
171 }
172
173 if (filp->f_op && filp->f_op->check_flags)
174 error = filp->f_op->check_flags(arg);
175 if (error)
176 return error;
177
1da177e4
LT
178 if ((arg ^ filp->f_flags) & FASYNC) {
179 if (filp->f_op && filp->f_op->fasync) {
180 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
181 if (error < 0)
182 goto out;
183 }
184 }
185
186 filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
187 out:
1da177e4
LT
188 return error;
189}
190
609d7fa9 191static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
1da177e4
LT
192 uid_t uid, uid_t euid, int force)
193{
194 write_lock_irq(&filp->f_owner.lock);
195 if (force || !filp->f_owner.pid) {
609d7fa9
EB
196 put_pid(filp->f_owner.pid);
197 filp->f_owner.pid = get_pid(pid);
198 filp->f_owner.pid_type = type;
1da177e4
LT
199 filp->f_owner.uid = uid;
200 filp->f_owner.euid = euid;
201 }
202 write_unlock_irq(&filp->f_owner.lock);
203}
204
609d7fa9
EB
205int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
206 int force)
1da177e4
LT
207{
208 int err;
209
210 err = security_file_set_fowner(filp);
211 if (err)
212 return err;
213
609d7fa9 214 f_modown(filp, pid, type, current->uid, current->euid, force);
1da177e4
LT
215 return 0;
216}
609d7fa9 217EXPORT_SYMBOL(__f_setown);
1da177e4 218
609d7fa9
EB
219int f_setown(struct file *filp, unsigned long arg, int force)
220{
221 enum pid_type type;
222 struct pid *pid;
223 int who = arg;
224 int result;
225 type = PIDTYPE_PID;
226 if (who < 0) {
227 type = PIDTYPE_PGID;
228 who = -who;
229 }
230 rcu_read_lock();
b488893a 231 pid = find_vpid(who);
609d7fa9
EB
232 result = __f_setown(filp, pid, type, force);
233 rcu_read_unlock();
234 return result;
235}
1da177e4
LT
236EXPORT_SYMBOL(f_setown);
237
238void f_delown(struct file *filp)
239{
609d7fa9
EB
240 f_modown(filp, NULL, PIDTYPE_PID, 0, 0, 1);
241}
242
243pid_t f_getown(struct file *filp)
244{
245 pid_t pid;
43fa1adb 246 read_lock(&filp->f_owner.lock);
6c5f3e7b 247 pid = pid_vnr(filp->f_owner.pid);
609d7fa9
EB
248 if (filp->f_owner.pid_type == PIDTYPE_PGID)
249 pid = -pid;
43fa1adb 250 read_unlock(&filp->f_owner.lock);
609d7fa9 251 return pid;
1da177e4
LT
252}
253
254static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
255 struct file *filp)
256{
257 long err = -EINVAL;
258
259 switch (cmd) {
260 case F_DUPFD:
22d2b35b 261 case F_DUPFD_CLOEXEC:
4e1e018e
AV
262 if (arg >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
263 break;
1027abe8
AV
264 err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);
265 if (err >= 0) {
266 get_file(filp);
267 fd_install(err, filp);
268 }
1da177e4
LT
269 break;
270 case F_GETFD:
271 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
272 break;
273 case F_SETFD:
274 err = 0;
275 set_close_on_exec(fd, arg & FD_CLOEXEC);
276 break;
277 case F_GETFL:
278 err = filp->f_flags;
279 break;
280 case F_SETFL:
281 err = setfl(fd, filp, arg);
282 break;
283 case F_GETLK:
284 err = fcntl_getlk(filp, (struct flock __user *) arg);
285 break;
286 case F_SETLK:
287 case F_SETLKW:
c293621b 288 err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
1da177e4
LT
289 break;
290 case F_GETOWN:
291 /*
292 * XXX If f_owner is a process group, the
293 * negative return value will get converted
294 * into an error. Oops. If we keep the
295 * current syscall conventions, the only way
296 * to fix this will be in libc.
297 */
609d7fa9 298 err = f_getown(filp);
1da177e4
LT
299 force_successful_syscall_return();
300 break;
301 case F_SETOWN:
302 err = f_setown(filp, arg, 1);
303 break;
304 case F_GETSIG:
305 err = filp->f_owner.signum;
306 break;
307 case F_SETSIG:
308 /* arg == 0 restores default behaviour. */
7ed20e1a 309 if (!valid_signal(arg)) {
1da177e4
LT
310 break;
311 }
312 err = 0;
313 filp->f_owner.signum = arg;
314 break;
315 case F_GETLEASE:
316 err = fcntl_getlease(filp);
317 break;
318 case F_SETLEASE:
319 err = fcntl_setlease(fd, filp, arg);
320 break;
321 case F_NOTIFY:
322 err = fcntl_dirnotify(fd, filp, arg);
323 break;
324 default:
325 break;
326 }
327 return err;
328}
329
330asmlinkage long sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg)
331{
332 struct file *filp;
333 long err = -EBADF;
334
335 filp = fget(fd);
336 if (!filp)
337 goto out;
338
339 err = security_file_fcntl(filp, cmd, arg);
340 if (err) {
341 fput(filp);
342 return err;
343 }
344
345 err = do_fcntl(fd, cmd, arg, filp);
346
347 fput(filp);
348out:
349 return err;
350}
351
352#if BITS_PER_LONG == 32
353asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg)
354{
355 struct file * filp;
356 long err;
357
358 err = -EBADF;
359 filp = fget(fd);
360 if (!filp)
361 goto out;
362
363 err = security_file_fcntl(filp, cmd, arg);
364 if (err) {
365 fput(filp);
366 return err;
367 }
368 err = -EBADF;
369
370 switch (cmd) {
371 case F_GETLK64:
372 err = fcntl_getlk64(filp, (struct flock64 __user *) arg);
373 break;
374 case F_SETLK64:
375 case F_SETLKW64:
c293621b
PS
376 err = fcntl_setlk64(fd, filp, cmd,
377 (struct flock64 __user *) arg);
1da177e4
LT
378 break;
379 default:
380 err = do_fcntl(fd, cmd, arg, filp);
381 break;
382 }
383 fput(filp);
384out:
385 return err;
386}
387#endif
388
389/* Table to convert sigio signal codes into poll band bitmaps */
390
fa3536cc 391static const long band_table[NSIGPOLL] = {
1da177e4
LT
392 POLLIN | POLLRDNORM, /* POLL_IN */
393 POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */
394 POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */
395 POLLERR, /* POLL_ERR */
396 POLLPRI | POLLRDBAND, /* POLL_PRI */
397 POLLHUP | POLLERR /* POLL_HUP */
398};
399
400static inline int sigio_perm(struct task_struct *p,
401 struct fown_struct *fown, int sig)
402{
403 return (((fown->euid == 0) ||
404 (fown->euid == p->suid) || (fown->euid == p->uid) ||
405 (fown->uid == p->suid) || (fown->uid == p->uid)) &&
406 !security_file_send_sigiotask(p, fown, sig));
407}
408
409static void send_sigio_to_task(struct task_struct *p,
410 struct fown_struct *fown,
411 int fd,
412 int reason)
413{
414 if (!sigio_perm(p, fown, fown->signum))
415 return;
416
417 switch (fown->signum) {
418 siginfo_t si;
419 default:
420 /* Queue a rt signal with the appropriate fd as its
421 value. We use SI_SIGIO as the source, not
422 SI_KERNEL, since kernel signals always get
423 delivered even if we can't queue. Failure to
424 queue in this case _should_ be reported; we fall
425 back to SIGIO in that case. --sct */
426 si.si_signo = fown->signum;
427 si.si_errno = 0;
428 si.si_code = reason;
429 /* Make sure we are called with one of the POLL_*
430 reasons, otherwise we could leak kernel stack into
431 userspace. */
f6298aab 432 BUG_ON((reason & __SI_MASK) != __SI_POLL);
1da177e4
LT
433 if (reason - POLL_IN >= NSIGPOLL)
434 si.si_band = ~0L;
435 else
436 si.si_band = band_table[reason - POLL_IN];
437 si.si_fd = fd;
850d6fbe 438 if (!group_send_sig_info(fown->signum, &si, p))
1da177e4
LT
439 break;
440 /* fall-through: fall back on the old plain SIGIO signal */
441 case 0:
850d6fbe 442 group_send_sig_info(SIGIO, SEND_SIG_PRIV, p);
1da177e4
LT
443 }
444}
445
446void send_sigio(struct fown_struct *fown, int fd, int band)
447{
448 struct task_struct *p;
609d7fa9
EB
449 enum pid_type type;
450 struct pid *pid;
1da177e4
LT
451
452 read_lock(&fown->lock);
609d7fa9 453 type = fown->pid_type;
1da177e4
LT
454 pid = fown->pid;
455 if (!pid)
456 goto out_unlock_fown;
457
458 read_lock(&tasklist_lock);
609d7fa9
EB
459 do_each_pid_task(pid, type, p) {
460 send_sigio_to_task(p, fown, fd, band);
461 } while_each_pid_task(pid, type, p);
1da177e4
LT
462 read_unlock(&tasklist_lock);
463 out_unlock_fown:
464 read_unlock(&fown->lock);
465}
466
467static void send_sigurg_to_task(struct task_struct *p,
468 struct fown_struct *fown)
469{
470 if (sigio_perm(p, fown, SIGURG))
850d6fbe 471 group_send_sig_info(SIGURG, SEND_SIG_PRIV, p);
1da177e4
LT
472}
473
474int send_sigurg(struct fown_struct *fown)
475{
476 struct task_struct *p;
609d7fa9
EB
477 enum pid_type type;
478 struct pid *pid;
479 int ret = 0;
1da177e4
LT
480
481 read_lock(&fown->lock);
609d7fa9 482 type = fown->pid_type;
1da177e4
LT
483 pid = fown->pid;
484 if (!pid)
485 goto out_unlock_fown;
486
487 ret = 1;
488
489 read_lock(&tasklist_lock);
609d7fa9
EB
490 do_each_pid_task(pid, type, p) {
491 send_sigurg_to_task(p, fown);
492 } while_each_pid_task(pid, type, p);
1da177e4
LT
493 read_unlock(&tasklist_lock);
494 out_unlock_fown:
495 read_unlock(&fown->lock);
496 return ret;
497}
498
499static DEFINE_RWLOCK(fasync_lock);
e18b890b 500static struct kmem_cache *fasync_cache __read_mostly;
1da177e4
LT
501
502/*
503 * fasync_helper() is used by some character device drivers (mainly mice)
504 * to set up the fasync queue. It returns negative on error, 0 if it did
505 * no changes and positive if it added/deleted the entry.
506 */
507int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
508{
509 struct fasync_struct *fa, **fp;
510 struct fasync_struct *new = NULL;
511 int result = 0;
512
513 if (on) {
e94b1766 514 new = kmem_cache_alloc(fasync_cache, GFP_KERNEL);
1da177e4
LT
515 if (!new)
516 return -ENOMEM;
517 }
518 write_lock_irq(&fasync_lock);
519 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
520 if (fa->fa_file == filp) {
521 if(on) {
522 fa->fa_fd = fd;
523 kmem_cache_free(fasync_cache, new);
524 } else {
525 *fp = fa->fa_next;
526 kmem_cache_free(fasync_cache, fa);
527 result = 1;
528 }
529 goto out;
530 }
531 }
532
533 if (on) {
534 new->magic = FASYNC_MAGIC;
535 new->fa_file = filp;
536 new->fa_fd = fd;
537 new->fa_next = *fapp;
538 *fapp = new;
539 result = 1;
540 }
541out:
542 write_unlock_irq(&fasync_lock);
543 return result;
544}
545
546EXPORT_SYMBOL(fasync_helper);
547
548void __kill_fasync(struct fasync_struct *fa, int sig, int band)
549{
550 while (fa) {
551 struct fown_struct * fown;
552 if (fa->magic != FASYNC_MAGIC) {
553 printk(KERN_ERR "kill_fasync: bad magic number in "
554 "fasync_struct!\n");
555 return;
556 }
557 fown = &fa->fa_file->f_owner;
558 /* Don't send SIGURG to processes which have not set a
559 queued signum: SIGURG has its own default signalling
560 mechanism. */
561 if (!(sig == SIGURG && fown->signum == 0))
562 send_sigio(fown, fa->fa_fd, band);
563 fa = fa->fa_next;
564 }
565}
566
567EXPORT_SYMBOL(__kill_fasync);
568
569void kill_fasync(struct fasync_struct **fp, int sig, int band)
570{
571 /* First a quick test without locking: usually
572 * the list is empty.
573 */
574 if (*fp) {
575 read_lock(&fasync_lock);
576 /* reread *fp after obtaining the lock */
577 __kill_fasync(*fp, sig, band);
578 read_unlock(&fasync_lock);
579 }
580}
581EXPORT_SYMBOL(kill_fasync);
582
583static int __init fasync_init(void)
584{
585 fasync_cache = kmem_cache_create("fasync_cache",
20c2df83 586 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
1da177e4
LT
587 return 0;
588}
589
590module_init(fasync_init)