4 * Copyright (C) 1991, 1992 Linus Torvalds
7 #include <linux/syscalls.h>
8 #include <linux/init.h>
11 #include <linux/file.h>
12 #include <linux/fdtable.h>
13 #include <linux/capability.h>
14 #include <linux/dnotify.h>
15 #include <linux/slab.h>
16 #include <linux/module.h>
17 #include <linux/security.h>
18 #include <linux/ptrace.h>
19 #include <linux/signal.h>
20 #include <linux/rcupdate.h>
21 #include <linux/pid_namespace.h>
22 #include <linux/smp_lock.h>
25 #include <asm/siginfo.h>
26 #include <asm/uaccess.h>
28 void set_close_on_exec(unsigned int fd, int flag)
30 struct files_struct *files = current->files;
32 spin_lock(&files->file_lock);
33 fdt = files_fdtable(files);
35 FD_SET(fd, fdt->close_on_exec);
37 FD_CLR(fd, fdt->close_on_exec);
38 spin_unlock(&files->file_lock);
41 static int get_close_on_exec(unsigned int fd)
43 struct files_struct *files = current->files;
47 fdt = files_fdtable(files);
48 res = FD_ISSET(fd, fdt->close_on_exec);
53 SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags)
56 struct file * file, *tofree;
57 struct files_struct * files = current->files;
60 if ((flags & ~O_CLOEXEC) != 0)
63 if (unlikely(oldfd == newfd))
66 spin_lock(&files->file_lock);
67 err = expand_files(files, newfd);
71 if (unlikely(err < 0)) {
77 * We need to detect attempts to do dup2() over allocated but still
78 * not finished descriptor. NB: OpenBSD avoids that at the price of
79 * extra work in their equivalent of fget() - they insert struct
80 * file immediately after grabbing descriptor, mark it larval if
81 * more work (e.g. actual opening) is needed and make sure that
82 * fget() treats larval files as absent. Potentially interesting,
83 * but while extra work in fget() is trivial, locking implications
84 * and amount of surgery on open()-related paths in VFS are not.
85 * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
86 * deadlocks in rather amusing ways, AFAICS. All of that is out of
87 * scope of POSIX or SUS, since neither considers shared descriptor
88 * tables and this condition does not arise without those.
91 fdt = files_fdtable(files);
92 tofree = fdt->fd[newfd];
93 if (!tofree && FD_ISSET(newfd, fdt->open_fds))
96 rcu_assign_pointer(fdt->fd[newfd], file);
97 FD_SET(newfd, fdt->open_fds);
98 if (flags & O_CLOEXEC)
99 FD_SET(newfd, fdt->close_on_exec);
101 FD_CLR(newfd, fdt->close_on_exec);
102 spin_unlock(&files->file_lock);
105 filp_close(tofree, files);
112 spin_unlock(&files->file_lock);
116 SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
118 if (unlikely(newfd == oldfd)) { /* corner case */
119 struct files_struct *files = current->files;
121 if (!fcheck_files(files, oldfd))
126 return sys_dup3(oldfd, newfd, 0);
129 SYSCALL_DEFINE1(dup, unsigned int, fildes)
132 struct file *file = fget(fildes);
135 ret = get_unused_fd();
137 fd_install(ret, file);
144 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
146 static int setfl(int fd, struct file * filp, unsigned long arg)
148 struct inode * inode = filp->f_path.dentry->d_inode;
152 * O_APPEND cannot be cleared if the file is marked as append-only
153 * and the file is open for write.
155 if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
158 /* O_NOATIME can only be set by the owner or superuser */
159 if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
160 if (!is_owner_or_cap(inode))
163 /* required for strict SunOS emulation */
164 if (O_NONBLOCK != O_NDELAY)
168 if (arg & O_DIRECT) {
169 if (!filp->f_mapping || !filp->f_mapping->a_ops ||
170 !filp->f_mapping->a_ops->direct_IO)
174 if (filp->f_op && filp->f_op->check_flags)
175 error = filp->f_op->check_flags(arg);
180 * ->fasync() is responsible for setting the FASYNC bit.
182 if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op &&
183 filp->f_op->fasync) {
184 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
188 spin_lock(&filp->f_lock);
189 filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
190 spin_unlock(&filp->f_lock);
196 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
197 uid_t uid, uid_t euid, int force)
199 write_lock_irq(&filp->f_owner.lock);
200 if (force || !filp->f_owner.pid) {
201 put_pid(filp->f_owner.pid);
202 filp->f_owner.pid = get_pid(pid);
203 filp->f_owner.pid_type = type;
204 filp->f_owner.uid = uid;
205 filp->f_owner.euid = euid;
207 write_unlock_irq(&filp->f_owner.lock);
210 int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
213 const struct cred *cred = current_cred();
216 err = security_file_set_fowner(filp);
220 f_modown(filp, pid, type, cred->uid, cred->euid, force);
223 EXPORT_SYMBOL(__f_setown);
225 int f_setown(struct file *filp, unsigned long arg, int force)
237 pid = find_vpid(who);
238 result = __f_setown(filp, pid, type, force);
242 EXPORT_SYMBOL(f_setown);
244 void f_delown(struct file *filp)
246 f_modown(filp, NULL, PIDTYPE_PID, 0, 0, 1);
249 pid_t f_getown(struct file *filp)
252 read_lock(&filp->f_owner.lock);
253 pid = pid_vnr(filp->f_owner.pid);
254 if (filp->f_owner.pid_type == PIDTYPE_PGID)
256 read_unlock(&filp->f_owner.lock);
260 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
267 case F_DUPFD_CLOEXEC:
268 if (arg >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
270 err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);
273 fd_install(err, filp);
277 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
281 set_close_on_exec(fd, arg & FD_CLOEXEC);
287 err = setfl(fd, filp, arg);
290 err = fcntl_getlk(filp, (struct flock __user *) arg);
294 err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
298 * XXX If f_owner is a process group, the
299 * negative return value will get converted
300 * into an error. Oops. If we keep the
301 * current syscall conventions, the only way
302 * to fix this will be in libc.
304 err = f_getown(filp);
305 force_successful_syscall_return();
308 err = f_setown(filp, arg, 1);
311 err = filp->f_owner.signum;
314 /* arg == 0 restores default behaviour. */
315 if (!valid_signal(arg)) {
319 filp->f_owner.signum = arg;
322 err = fcntl_getlease(filp);
325 err = fcntl_setlease(fd, filp, arg);
328 err = fcntl_dirnotify(fd, filp, arg);
336 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
345 err = security_file_fcntl(filp, cmd, arg);
351 err = do_fcntl(fd, cmd, arg, filp);
358 #if BITS_PER_LONG == 32
359 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
370 err = security_file_fcntl(filp, cmd, arg);
379 err = fcntl_getlk64(filp, (struct flock64 __user *) arg);
383 err = fcntl_setlk64(fd, filp, cmd,
384 (struct flock64 __user *) arg);
387 err = do_fcntl(fd, cmd, arg, filp);
396 /* Table to convert sigio signal codes into poll band bitmaps */
398 static const long band_table[NSIGPOLL] = {
399 POLLIN | POLLRDNORM, /* POLL_IN */
400 POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */
401 POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */
402 POLLERR, /* POLL_ERR */
403 POLLPRI | POLLRDBAND, /* POLL_PRI */
404 POLLHUP | POLLERR /* POLL_HUP */
407 static inline int sigio_perm(struct task_struct *p,
408 struct fown_struct *fown, int sig)
410 const struct cred *cred;
414 cred = __task_cred(p);
415 ret = ((fown->euid == 0 ||
416 fown->euid == cred->suid || fown->euid == cred->uid ||
417 fown->uid == cred->suid || fown->uid == cred->uid) &&
418 !security_file_send_sigiotask(p, fown, sig));
423 static void send_sigio_to_task(struct task_struct *p,
424 struct fown_struct *fown,
428 if (!sigio_perm(p, fown, fown->signum))
431 switch (fown->signum) {
434 /* Queue a rt signal with the appropriate fd as its
435 value. We use SI_SIGIO as the source, not
436 SI_KERNEL, since kernel signals always get
437 delivered even if we can't queue. Failure to
438 queue in this case _should_ be reported; we fall
439 back to SIGIO in that case. --sct */
440 si.si_signo = fown->signum;
443 /* Make sure we are called with one of the POLL_*
444 reasons, otherwise we could leak kernel stack into
446 BUG_ON((reason & __SI_MASK) != __SI_POLL);
447 if (reason - POLL_IN >= NSIGPOLL)
450 si.si_band = band_table[reason - POLL_IN];
452 if (!group_send_sig_info(fown->signum, &si, p))
454 /* fall-through: fall back on the old plain SIGIO signal */
456 group_send_sig_info(SIGIO, SEND_SIG_PRIV, p);
460 void send_sigio(struct fown_struct *fown, int fd, int band)
462 struct task_struct *p;
466 read_lock(&fown->lock);
467 type = fown->pid_type;
470 goto out_unlock_fown;
472 read_lock(&tasklist_lock);
473 do_each_pid_task(pid, type, p) {
474 send_sigio_to_task(p, fown, fd, band);
475 } while_each_pid_task(pid, type, p);
476 read_unlock(&tasklist_lock);
478 read_unlock(&fown->lock);
481 static void send_sigurg_to_task(struct task_struct *p,
482 struct fown_struct *fown)
484 if (sigio_perm(p, fown, SIGURG))
485 group_send_sig_info(SIGURG, SEND_SIG_PRIV, p);
488 int send_sigurg(struct fown_struct *fown)
490 struct task_struct *p;
495 read_lock(&fown->lock);
496 type = fown->pid_type;
499 goto out_unlock_fown;
503 read_lock(&tasklist_lock);
504 do_each_pid_task(pid, type, p) {
505 send_sigurg_to_task(p, fown);
506 } while_each_pid_task(pid, type, p);
507 read_unlock(&tasklist_lock);
509 read_unlock(&fown->lock);
513 static DEFINE_RWLOCK(fasync_lock);
514 static struct kmem_cache *fasync_cache __read_mostly;
517 * fasync_helper() is used by almost all character device drivers
518 * to set up the fasync queue. It returns negative on error, 0 if it did
519 * no changes and positive if it added/deleted the entry.
521 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
523 struct fasync_struct *fa, **fp;
524 struct fasync_struct *new = NULL;
528 new = kmem_cache_alloc(fasync_cache, GFP_KERNEL);
532 write_lock_irq(&fasync_lock);
533 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
534 if (fa->fa_file == filp) {
537 kmem_cache_free(fasync_cache, new);
540 kmem_cache_free(fasync_cache, fa);
548 new->magic = FASYNC_MAGIC;
551 new->fa_next = *fapp;
556 /* Fix up FASYNC bit while still holding fasync_lock */
557 spin_lock(&filp->f_lock);
559 filp->f_flags |= FASYNC;
561 filp->f_flags &= ~FASYNC;
562 spin_unlock(&filp->f_lock);
563 write_unlock_irq(&fasync_lock);
567 EXPORT_SYMBOL(fasync_helper);
569 void __kill_fasync(struct fasync_struct *fa, int sig, int band)
572 struct fown_struct * fown;
573 if (fa->magic != FASYNC_MAGIC) {
574 printk(KERN_ERR "kill_fasync: bad magic number in "
578 fown = &fa->fa_file->f_owner;
579 /* Don't send SIGURG to processes which have not set a
580 queued signum: SIGURG has its own default signalling
582 if (!(sig == SIGURG && fown->signum == 0))
583 send_sigio(fown, fa->fa_fd, band);
588 EXPORT_SYMBOL(__kill_fasync);
590 void kill_fasync(struct fasync_struct **fp, int sig, int band)
592 /* First a quick test without locking: usually
596 read_lock(&fasync_lock);
597 /* reread *fp after obtaining the lock */
598 __kill_fasync(*fp, sig, band);
599 read_unlock(&fasync_lock);
602 EXPORT_SYMBOL(kill_fasync);
604 static int __init fasync_init(void)
606 fasync_cache = kmem_cache_create("fasync_cache",
607 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
611 module_init(fasync_init)