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/pipe_fs_i.h>
18 #include <linux/security.h>
19 #include <linux/ptrace.h>
20 #include <linux/signal.h>
21 #include <linux/rcupdate.h>
22 #include <linux/pid_namespace.h>
23 #include <linux/shmem_fs.h>
26 #include <asm/siginfo.h>
27 #include <asm/uaccess.h>
29 void set_close_on_exec(unsigned int fd, int flag)
31 struct files_struct *files = current->files;
33 spin_lock(&files->file_lock);
34 fdt = files_fdtable(files);
36 __set_close_on_exec(fd, fdt);
38 __clear_close_on_exec(fd, fdt);
39 spin_unlock(&files->file_lock);
42 static bool get_close_on_exec(unsigned int fd)
44 struct files_struct *files = current->files;
48 fdt = files_fdtable(files);
49 res = close_on_exec(fd, fdt);
54 SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags)
57 struct file * file, *tofree;
58 struct files_struct * files = current->files;
61 if ((flags & ~O_CLOEXEC) != 0)
64 if (unlikely(oldfd == newfd))
67 spin_lock(&files->file_lock);
68 err = expand_files(files, newfd);
72 if (unlikely(err < 0)) {
78 * We need to detect attempts to do dup2() over allocated but still
79 * not finished descriptor. NB: OpenBSD avoids that at the price of
80 * extra work in their equivalent of fget() - they insert struct
81 * file immediately after grabbing descriptor, mark it larval if
82 * more work (e.g. actual opening) is needed and make sure that
83 * fget() treats larval files as absent. Potentially interesting,
84 * but while extra work in fget() is trivial, locking implications
85 * and amount of surgery on open()-related paths in VFS are not.
86 * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
87 * deadlocks in rather amusing ways, AFAICS. All of that is out of
88 * scope of POSIX or SUS, since neither considers shared descriptor
89 * tables and this condition does not arise without those.
92 fdt = files_fdtable(files);
93 tofree = fdt->fd[newfd];
94 if (!tofree && fd_is_open(newfd, fdt))
97 rcu_assign_pointer(fdt->fd[newfd], file);
98 __set_open_fd(newfd, fdt);
99 if (flags & O_CLOEXEC)
100 __set_close_on_exec(newfd, fdt);
102 __clear_close_on_exec(newfd, fdt);
103 spin_unlock(&files->file_lock);
106 filp_close(tofree, files);
113 spin_unlock(&files->file_lock);
117 SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
119 if (unlikely(newfd == oldfd)) { /* corner case */
120 struct files_struct *files = current->files;
124 if (!fcheck_files(files, oldfd))
129 return sys_dup3(oldfd, newfd, 0);
132 SYSCALL_DEFINE1(dup, unsigned int, fildes)
135 struct file *file = fget_raw(fildes);
138 ret = get_unused_fd();
140 fd_install(ret, file);
147 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
149 static int setfl(int fd, struct file * filp, unsigned long arg)
151 struct inode * inode = filp->f_path.dentry->d_inode;
155 * O_APPEND cannot be cleared if the file is marked as append-only
156 * and the file is open for write.
158 if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
161 /* O_NOATIME can only be set by the owner or superuser */
162 if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
163 if (!inode_owner_or_capable(inode))
166 /* required for strict SunOS emulation */
167 if (O_NONBLOCK != O_NDELAY)
171 if (arg & O_DIRECT) {
172 if (!filp->f_mapping || !filp->f_mapping->a_ops ||
173 !filp->f_mapping->a_ops->direct_IO)
177 if (filp->f_op && filp->f_op->check_flags)
178 error = filp->f_op->check_flags(arg);
183 * ->fasync() is responsible for setting the FASYNC bit.
185 if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op &&
186 filp->f_op->fasync) {
187 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
193 spin_lock(&filp->f_lock);
194 filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
195 spin_unlock(&filp->f_lock);
201 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
204 write_lock_irq(&filp->f_owner.lock);
205 if (force || !filp->f_owner.pid) {
206 put_pid(filp->f_owner.pid);
207 filp->f_owner.pid = get_pid(pid);
208 filp->f_owner.pid_type = type;
211 const struct cred *cred = current_cred();
212 filp->f_owner.uid = cred->uid;
213 filp->f_owner.euid = cred->euid;
216 write_unlock_irq(&filp->f_owner.lock);
219 int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
224 err = security_file_set_fowner(filp);
228 f_modown(filp, pid, type, force);
231 EXPORT_SYMBOL(__f_setown);
233 int f_setown(struct file *filp, unsigned long arg, int force)
245 pid = find_vpid(who);
246 result = __f_setown(filp, pid, type, force);
250 EXPORT_SYMBOL(f_setown);
252 void f_delown(struct file *filp)
254 f_modown(filp, NULL, PIDTYPE_PID, 1);
257 pid_t f_getown(struct file *filp)
260 read_lock(&filp->f_owner.lock);
261 pid = pid_vnr(filp->f_owner.pid);
262 if (filp->f_owner.pid_type == PIDTYPE_PGID)
264 read_unlock(&filp->f_owner.lock);
268 static int f_setown_ex(struct file *filp, unsigned long arg)
270 struct f_owner_ex * __user owner_p = (void * __user)arg;
271 struct f_owner_ex owner;
276 ret = copy_from_user(&owner, owner_p, sizeof(owner));
280 switch (owner.type) {
298 pid = find_vpid(owner.pid);
299 if (owner.pid && !pid)
302 ret = __f_setown(filp, pid, type, 1);
308 static int f_getown_ex(struct file *filp, unsigned long arg)
310 struct f_owner_ex * __user owner_p = (void * __user)arg;
311 struct f_owner_ex owner;
314 read_lock(&filp->f_owner.lock);
315 owner.pid = pid_vnr(filp->f_owner.pid);
316 switch (filp->f_owner.pid_type) {
318 owner.type = F_OWNER_TID;
322 owner.type = F_OWNER_PID;
326 owner.type = F_OWNER_PGRP;
334 read_unlock(&filp->f_owner.lock);
337 ret = copy_to_user(owner_p, &owner, sizeof(owner));
344 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
351 case F_DUPFD_CLOEXEC:
352 if (arg >= rlimit(RLIMIT_NOFILE))
354 err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);
357 fd_install(err, filp);
361 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
365 set_close_on_exec(fd, arg & FD_CLOEXEC);
371 err = setfl(fd, filp, arg);
374 err = fcntl_getlk(filp, (struct flock __user *) arg);
378 err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
382 * XXX If f_owner is a process group, the
383 * negative return value will get converted
384 * into an error. Oops. If we keep the
385 * current syscall conventions, the only way
386 * to fix this will be in libc.
388 err = f_getown(filp);
389 force_successful_syscall_return();
392 err = f_setown(filp, arg, 1);
395 err = f_getown_ex(filp, arg);
398 err = f_setown_ex(filp, arg);
401 err = filp->f_owner.signum;
404 /* arg == 0 restores default behaviour. */
405 if (!valid_signal(arg)) {
409 filp->f_owner.signum = arg;
412 err = fcntl_getlease(filp);
415 err = fcntl_setlease(fd, filp, arg);
418 err = fcntl_dirnotify(fd, filp, arg);
422 err = pipe_fcntl(filp, cmd, arg);
426 err = shmem_fcntl(filp, cmd, arg);
434 static int check_fcntl_cmd(unsigned cmd)
438 case F_DUPFD_CLOEXEC:
447 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
456 if (unlikely(filp->f_mode & FMODE_PATH)) {
457 if (!check_fcntl_cmd(cmd)) {
463 err = security_file_fcntl(filp, cmd, arg);
469 err = do_fcntl(fd, cmd, arg, filp);
476 #if BITS_PER_LONG == 32
477 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
488 if (unlikely(filp->f_mode & FMODE_PATH)) {
489 if (!check_fcntl_cmd(cmd)) {
495 err = security_file_fcntl(filp, cmd, arg);
504 err = fcntl_getlk64(filp, (struct flock64 __user *) arg);
508 err = fcntl_setlk64(fd, filp, cmd,
509 (struct flock64 __user *) arg);
512 err = do_fcntl(fd, cmd, arg, filp);
521 /* Table to convert sigio signal codes into poll band bitmaps */
523 static const long band_table[NSIGPOLL] = {
524 POLLIN | POLLRDNORM, /* POLL_IN */
525 POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */
526 POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */
527 POLLERR, /* POLL_ERR */
528 POLLPRI | POLLRDBAND, /* POLL_PRI */
529 POLLHUP | POLLERR /* POLL_HUP */
532 static inline int sigio_perm(struct task_struct *p,
533 struct fown_struct *fown, int sig)
535 const struct cred *cred;
539 cred = __task_cred(p);
540 ret = ((fown->euid == 0 ||
541 fown->euid == cred->suid || fown->euid == cred->uid ||
542 fown->uid == cred->suid || fown->uid == cred->uid) &&
543 !security_file_send_sigiotask(p, fown, sig));
548 static void send_sigio_to_task(struct task_struct *p,
549 struct fown_struct *fown,
550 int fd, int reason, int group)
553 * F_SETSIG can change ->signum lockless in parallel, make
554 * sure we read it once and use the same value throughout.
556 int signum = ACCESS_ONCE(fown->signum);
558 if (!sigio_perm(p, fown, signum))
564 /* Queue a rt signal with the appropriate fd as its
565 value. We use SI_SIGIO as the source, not
566 SI_KERNEL, since kernel signals always get
567 delivered even if we can't queue. Failure to
568 queue in this case _should_ be reported; we fall
569 back to SIGIO in that case. --sct */
570 si.si_signo = signum;
573 /* Make sure we are called with one of the POLL_*
574 reasons, otherwise we could leak kernel stack into
576 BUG_ON((reason & __SI_MASK) != __SI_POLL);
577 if (reason - POLL_IN >= NSIGPOLL)
580 si.si_band = band_table[reason - POLL_IN];
582 if (!do_send_sig_info(signum, &si, p, group))
584 /* fall-through: fall back on the old plain SIGIO signal */
586 do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
590 void send_sigio(struct fown_struct *fown, int fd, int band)
592 struct task_struct *p;
597 read_lock(&fown->lock);
599 type = fown->pid_type;
600 if (type == PIDTYPE_MAX) {
607 goto out_unlock_fown;
609 read_lock(&tasklist_lock);
610 do_each_pid_task(pid, type, p) {
611 send_sigio_to_task(p, fown, fd, band, group);
612 } while_each_pid_task(pid, type, p);
613 read_unlock(&tasklist_lock);
615 read_unlock(&fown->lock);
618 static void send_sigurg_to_task(struct task_struct *p,
619 struct fown_struct *fown, int group)
621 if (sigio_perm(p, fown, SIGURG))
622 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
625 int send_sigurg(struct fown_struct *fown)
627 struct task_struct *p;
633 read_lock(&fown->lock);
635 type = fown->pid_type;
636 if (type == PIDTYPE_MAX) {
643 goto out_unlock_fown;
647 read_lock(&tasklist_lock);
648 do_each_pid_task(pid, type, p) {
649 send_sigurg_to_task(p, fown, group);
650 } while_each_pid_task(pid, type, p);
651 read_unlock(&tasklist_lock);
653 read_unlock(&fown->lock);
657 static DEFINE_SPINLOCK(fasync_lock);
658 static struct kmem_cache *fasync_cache __read_mostly;
660 static void fasync_free_rcu(struct rcu_head *head)
662 kmem_cache_free(fasync_cache,
663 container_of(head, struct fasync_struct, fa_rcu));
667 * Remove a fasync entry. If successfully removed, return
668 * positive and clear the FASYNC flag. If no entry exists,
669 * do nothing and return 0.
671 * NOTE! It is very important that the FASYNC flag always
672 * match the state "is the filp on a fasync list".
675 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
677 struct fasync_struct *fa, **fp;
680 spin_lock(&filp->f_lock);
681 spin_lock(&fasync_lock);
682 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
683 if (fa->fa_file != filp)
686 spin_lock_irq(&fa->fa_lock);
688 spin_unlock_irq(&fa->fa_lock);
691 call_rcu(&fa->fa_rcu, fasync_free_rcu);
692 filp->f_flags &= ~FASYNC;
696 spin_unlock(&fasync_lock);
697 spin_unlock(&filp->f_lock);
701 struct fasync_struct *fasync_alloc(void)
703 return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
707 * NOTE! This can be used only for unused fasync entries:
708 * entries that actually got inserted on the fasync list
709 * need to be released by rcu - see fasync_remove_entry.
711 void fasync_free(struct fasync_struct *new)
713 kmem_cache_free(fasync_cache, new);
717 * Insert a new entry into the fasync list. Return the pointer to the
718 * old one if we didn't use the new one.
720 * NOTE! It is very important that the FASYNC flag always
721 * match the state "is the filp on a fasync list".
723 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
725 struct fasync_struct *fa, **fp;
727 spin_lock(&filp->f_lock);
728 spin_lock(&fasync_lock);
729 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
730 if (fa->fa_file != filp)
733 spin_lock_irq(&fa->fa_lock);
735 spin_unlock_irq(&fa->fa_lock);
739 spin_lock_init(&new->fa_lock);
740 new->magic = FASYNC_MAGIC;
743 new->fa_next = *fapp;
744 rcu_assign_pointer(*fapp, new);
745 filp->f_flags |= FASYNC;
748 spin_unlock(&fasync_lock);
749 spin_unlock(&filp->f_lock);
754 * Add a fasync entry. Return negative on error, positive if
755 * added, and zero if did nothing but change an existing one.
757 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
759 struct fasync_struct *new;
761 new = fasync_alloc();
766 * fasync_insert_entry() returns the old (update) entry if
769 * So free the (unused) new entry and return 0 to let the
770 * caller know that we didn't add any new fasync entries.
772 if (fasync_insert_entry(fd, filp, fapp, new)) {
781 * fasync_helper() is used by almost all character device drivers
782 * to set up the fasync queue, and for regular files by the file
783 * lease code. It returns negative on error, 0 if it did no changes
784 * and positive if it added/deleted the entry.
786 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
789 return fasync_remove_entry(filp, fapp);
790 return fasync_add_entry(fd, filp, fapp);
793 EXPORT_SYMBOL(fasync_helper);
796 * rcu_read_lock() is held
798 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
801 struct fown_struct *fown;
804 if (fa->magic != FASYNC_MAGIC) {
805 printk(KERN_ERR "kill_fasync: bad magic number in "
809 spin_lock_irqsave(&fa->fa_lock, flags);
811 fown = &fa->fa_file->f_owner;
812 /* Don't send SIGURG to processes which have not set a
813 queued signum: SIGURG has its own default signalling
815 if (!(sig == SIGURG && fown->signum == 0))
816 send_sigio(fown, fa->fa_fd, band);
818 spin_unlock_irqrestore(&fa->fa_lock, flags);
819 fa = rcu_dereference(fa->fa_next);
823 void kill_fasync(struct fasync_struct **fp, int sig, int band)
825 /* First a quick test without locking: usually
830 kill_fasync_rcu(rcu_dereference(*fp), sig, band);
834 EXPORT_SYMBOL(kill_fasync);
836 static int __init fcntl_init(void)
839 * Please add new bits here to ensure allocation uniqueness.
840 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
841 * is defined as O_NONBLOCK on some platforms and not on others.
843 BUILD_BUG_ON(19 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
844 O_RDONLY | O_WRONLY | O_RDWR |
845 O_CREAT | O_EXCL | O_NOCTTY |
846 O_TRUNC | O_APPEND | /* O_NONBLOCK | */
847 __O_SYNC | O_DSYNC | FASYNC |
848 O_DIRECT | O_LARGEFILE | O_DIRECTORY |
849 O_NOFOLLOW | O_NOATIME | O_CLOEXEC |
850 __FMODE_EXEC | O_PATH
853 fasync_cache = kmem_cache_create("fasync_cache",
854 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
858 module_init(fcntl_init)