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613 lines
14 KiB
613 lines
14 KiB
/*
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* linux/fs/fcntl.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/syscalls.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/capability.h>
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#include <linux/dnotify.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/security.h>
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#include <linux/ptrace.h>
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#include <linux/signal.h>
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#include <linux/rcupdate.h>
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#include <linux/pid_namespace.h>
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#include <linux/smp_lock.h>
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#include <asm/poll.h>
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#include <asm/siginfo.h>
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#include <asm/uaccess.h>
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void set_close_on_exec(unsigned int fd, int flag)
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{
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struct files_struct *files = current->files;
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struct fdtable *fdt;
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spin_lock(&files->file_lock);
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fdt = files_fdtable(files);
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if (flag)
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FD_SET(fd, fdt->close_on_exec);
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else
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FD_CLR(fd, fdt->close_on_exec);
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spin_unlock(&files->file_lock);
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}
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static int get_close_on_exec(unsigned int fd)
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{
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struct files_struct *files = current->files;
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struct fdtable *fdt;
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int res;
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rcu_read_lock();
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fdt = files_fdtable(files);
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res = FD_ISSET(fd, fdt->close_on_exec);
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rcu_read_unlock();
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return res;
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}
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SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags)
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{
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int err = -EBADF;
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struct file * file, *tofree;
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struct files_struct * files = current->files;
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struct fdtable *fdt;
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if ((flags & ~O_CLOEXEC) != 0)
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return -EINVAL;
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if (unlikely(oldfd == newfd))
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return -EINVAL;
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spin_lock(&files->file_lock);
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err = expand_files(files, newfd);
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file = fcheck(oldfd);
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if (unlikely(!file))
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goto Ebadf;
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if (unlikely(err < 0)) {
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if (err == -EMFILE)
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goto Ebadf;
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goto out_unlock;
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}
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/*
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* We need to detect attempts to do dup2() over allocated but still
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* not finished descriptor. NB: OpenBSD avoids that at the price of
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* extra work in their equivalent of fget() - they insert struct
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* file immediately after grabbing descriptor, mark it larval if
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* more work (e.g. actual opening) is needed and make sure that
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* fget() treats larval files as absent. Potentially interesting,
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* but while extra work in fget() is trivial, locking implications
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* and amount of surgery on open()-related paths in VFS are not.
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* FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
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* deadlocks in rather amusing ways, AFAICS. All of that is out of
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* scope of POSIX or SUS, since neither considers shared descriptor
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* tables and this condition does not arise without those.
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*/
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err = -EBUSY;
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fdt = files_fdtable(files);
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tofree = fdt->fd[newfd];
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if (!tofree && FD_ISSET(newfd, fdt->open_fds))
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goto out_unlock;
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get_file(file);
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rcu_assign_pointer(fdt->fd[newfd], file);
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FD_SET(newfd, fdt->open_fds);
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if (flags & O_CLOEXEC)
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FD_SET(newfd, fdt->close_on_exec);
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else
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FD_CLR(newfd, fdt->close_on_exec);
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spin_unlock(&files->file_lock);
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if (tofree)
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filp_close(tofree, files);
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return newfd;
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Ebadf:
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err = -EBADF;
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out_unlock:
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spin_unlock(&files->file_lock);
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return err;
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}
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SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
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{
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if (unlikely(newfd == oldfd)) { /* corner case */
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struct files_struct *files = current->files;
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rcu_read_lock();
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if (!fcheck_files(files, oldfd))
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oldfd = -EBADF;
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rcu_read_unlock();
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return oldfd;
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}
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return sys_dup3(oldfd, newfd, 0);
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}
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SYSCALL_DEFINE1(dup, unsigned int, fildes)
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{
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int ret = -EBADF;
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struct file *file = fget(fildes);
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if (file) {
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ret = get_unused_fd();
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if (ret >= 0)
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fd_install(ret, file);
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else
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fput(file);
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}
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return ret;
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}
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#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
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static int setfl(int fd, struct file * filp, unsigned long arg)
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{
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struct inode * inode = filp->f_path.dentry->d_inode;
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int error = 0;
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/*
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* O_APPEND cannot be cleared if the file is marked as append-only
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* and the file is open for write.
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*/
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if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
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return -EPERM;
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/* O_NOATIME can only be set by the owner or superuser */
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if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
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if (!is_owner_or_cap(inode))
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return -EPERM;
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/* required for strict SunOS emulation */
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if (O_NONBLOCK != O_NDELAY)
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if (arg & O_NDELAY)
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arg |= O_NONBLOCK;
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if (arg & O_DIRECT) {
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if (!filp->f_mapping || !filp->f_mapping->a_ops ||
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!filp->f_mapping->a_ops->direct_IO)
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return -EINVAL;
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}
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if (filp->f_op && filp->f_op->check_flags)
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error = filp->f_op->check_flags(arg);
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if (error)
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return error;
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/*
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* ->fasync() is responsible for setting the FASYNC bit.
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*/
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if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op &&
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filp->f_op->fasync) {
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error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
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if (error < 0)
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goto out;
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if (error > 0)
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error = 0;
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}
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spin_lock(&filp->f_lock);
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filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
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spin_unlock(&filp->f_lock);
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out:
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return error;
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}
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static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
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uid_t uid, uid_t euid, int force)
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{
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write_lock_irq(&filp->f_owner.lock);
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if (force || !filp->f_owner.pid) {
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put_pid(filp->f_owner.pid);
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filp->f_owner.pid = get_pid(pid);
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filp->f_owner.pid_type = type;
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filp->f_owner.uid = uid;
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filp->f_owner.euid = euid;
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}
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write_unlock_irq(&filp->f_owner.lock);
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}
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int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
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int force)
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{
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const struct cred *cred = current_cred();
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int err;
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err = security_file_set_fowner(filp);
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if (err)
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return err;
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f_modown(filp, pid, type, cred->uid, cred->euid, force);
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return 0;
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}
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EXPORT_SYMBOL(__f_setown);
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int f_setown(struct file *filp, unsigned long arg, int force)
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{
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enum pid_type type;
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struct pid *pid;
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int who = arg;
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int result;
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type = PIDTYPE_PID;
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if (who < 0) {
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type = PIDTYPE_PGID;
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who = -who;
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}
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rcu_read_lock();
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pid = find_vpid(who);
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result = __f_setown(filp, pid, type, force);
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rcu_read_unlock();
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return result;
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}
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EXPORT_SYMBOL(f_setown);
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void f_delown(struct file *filp)
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{
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f_modown(filp, NULL, PIDTYPE_PID, 0, 0, 1);
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}
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pid_t f_getown(struct file *filp)
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{
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pid_t pid;
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read_lock(&filp->f_owner.lock);
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pid = pid_vnr(filp->f_owner.pid);
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if (filp->f_owner.pid_type == PIDTYPE_PGID)
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pid = -pid;
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read_unlock(&filp->f_owner.lock);
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return pid;
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}
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static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
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struct file *filp)
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{
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long err = -EINVAL;
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switch (cmd) {
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case F_DUPFD:
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case F_DUPFD_CLOEXEC:
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if (arg >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
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break;
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err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);
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if (err >= 0) {
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get_file(filp);
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fd_install(err, filp);
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}
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break;
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case F_GETFD:
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err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
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break;
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case F_SETFD:
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err = 0;
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set_close_on_exec(fd, arg & FD_CLOEXEC);
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break;
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case F_GETFL:
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err = filp->f_flags;
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break;
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case F_SETFL:
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err = setfl(fd, filp, arg);
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break;
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case F_GETLK:
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err = fcntl_getlk(filp, (struct flock __user *) arg);
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break;
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case F_SETLK:
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case F_SETLKW:
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err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
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break;
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case F_GETOWN:
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/*
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* XXX If f_owner is a process group, the
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* negative return value will get converted
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* into an error. Oops. If we keep the
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* current syscall conventions, the only way
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* to fix this will be in libc.
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*/
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err = f_getown(filp);
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force_successful_syscall_return();
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break;
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case F_SETOWN:
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err = f_setown(filp, arg, 1);
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break;
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case F_GETSIG:
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err = filp->f_owner.signum;
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break;
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case F_SETSIG:
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/* arg == 0 restores default behaviour. */
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if (!valid_signal(arg)) {
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break;
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}
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err = 0;
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filp->f_owner.signum = arg;
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break;
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case F_GETLEASE:
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err = fcntl_getlease(filp);
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break;
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case F_SETLEASE:
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err = fcntl_setlease(fd, filp, arg);
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break;
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case F_NOTIFY:
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err = fcntl_dirnotify(fd, filp, arg);
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break;
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default:
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break;
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}
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return err;
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}
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SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
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{
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struct file *filp;
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long err = -EBADF;
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filp = fget(fd);
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if (!filp)
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goto out;
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err = security_file_fcntl(filp, cmd, arg);
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if (err) {
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fput(filp);
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return err;
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}
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err = do_fcntl(fd, cmd, arg, filp);
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fput(filp);
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out:
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return err;
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}
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#if BITS_PER_LONG == 32
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SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
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unsigned long, arg)
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{
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struct file * filp;
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long err;
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err = -EBADF;
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filp = fget(fd);
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if (!filp)
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goto out;
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err = security_file_fcntl(filp, cmd, arg);
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if (err) {
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fput(filp);
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return err;
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}
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err = -EBADF;
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switch (cmd) {
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case F_GETLK64:
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err = fcntl_getlk64(filp, (struct flock64 __user *) arg);
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break;
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case F_SETLK64:
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case F_SETLKW64:
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err = fcntl_setlk64(fd, filp, cmd,
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(struct flock64 __user *) arg);
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break;
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default:
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err = do_fcntl(fd, cmd, arg, filp);
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break;
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}
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fput(filp);
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out:
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return err;
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}
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#endif
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/* Table to convert sigio signal codes into poll band bitmaps */
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static const long band_table[NSIGPOLL] = {
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POLLIN | POLLRDNORM, /* POLL_IN */
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POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */
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POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */
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POLLERR, /* POLL_ERR */
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POLLPRI | POLLRDBAND, /* POLL_PRI */
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POLLHUP | POLLERR /* POLL_HUP */
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};
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static inline int sigio_perm(struct task_struct *p,
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struct fown_struct *fown, int sig)
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{
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const struct cred *cred;
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int ret;
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rcu_read_lock();
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cred = __task_cred(p);
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ret = ((fown->euid == 0 ||
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fown->euid == cred->suid || fown->euid == cred->uid ||
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fown->uid == cred->suid || fown->uid == cred->uid) &&
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!security_file_send_sigiotask(p, fown, sig));
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rcu_read_unlock();
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return ret;
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}
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static void send_sigio_to_task(struct task_struct *p,
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struct fown_struct *fown,
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int fd,
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int reason)
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{
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if (!sigio_perm(p, fown, fown->signum))
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return;
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switch (fown->signum) {
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siginfo_t si;
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default:
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/* Queue a rt signal with the appropriate fd as its
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value. We use SI_SIGIO as the source, not
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SI_KERNEL, since kernel signals always get
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delivered even if we can't queue. Failure to
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queue in this case _should_ be reported; we fall
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back to SIGIO in that case. --sct */
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si.si_signo = fown->signum;
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si.si_errno = 0;
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si.si_code = reason;
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/* Make sure we are called with one of the POLL_*
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reasons, otherwise we could leak kernel stack into
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userspace. */
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BUG_ON((reason & __SI_MASK) != __SI_POLL);
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if (reason - POLL_IN >= NSIGPOLL)
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si.si_band = ~0L;
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else
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si.si_band = band_table[reason - POLL_IN];
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si.si_fd = fd;
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if (!group_send_sig_info(fown->signum, &si, p))
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break;
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/* fall-through: fall back on the old plain SIGIO signal */
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case 0:
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group_send_sig_info(SIGIO, SEND_SIG_PRIV, p);
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}
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}
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void send_sigio(struct fown_struct *fown, int fd, int band)
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{
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struct task_struct *p;
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enum pid_type type;
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struct pid *pid;
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read_lock(&fown->lock);
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type = fown->pid_type;
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pid = fown->pid;
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if (!pid)
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goto out_unlock_fown;
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read_lock(&tasklist_lock);
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do_each_pid_task(pid, type, p) {
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send_sigio_to_task(p, fown, fd, band);
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} while_each_pid_task(pid, type, p);
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read_unlock(&tasklist_lock);
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out_unlock_fown:
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read_unlock(&fown->lock);
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}
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static void send_sigurg_to_task(struct task_struct *p,
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struct fown_struct *fown)
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{
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if (sigio_perm(p, fown, SIGURG))
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group_send_sig_info(SIGURG, SEND_SIG_PRIV, p);
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}
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int send_sigurg(struct fown_struct *fown)
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{
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struct task_struct *p;
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enum pid_type type;
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struct pid *pid;
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int ret = 0;
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read_lock(&fown->lock);
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type = fown->pid_type;
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pid = fown->pid;
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if (!pid)
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goto out_unlock_fown;
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ret = 1;
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read_lock(&tasklist_lock);
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do_each_pid_task(pid, type, p) {
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send_sigurg_to_task(p, fown);
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} while_each_pid_task(pid, type, p);
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read_unlock(&tasklist_lock);
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out_unlock_fown:
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read_unlock(&fown->lock);
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return ret;
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}
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|
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static DEFINE_RWLOCK(fasync_lock);
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static struct kmem_cache *fasync_cache __read_mostly;
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|
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/*
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* fasync_helper() is used by almost all character device drivers
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* to set up the fasync queue. It returns negative on error, 0 if it did
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|
* no changes and positive if it added/deleted the entry.
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*/
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|
int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
|
|
{
|
|
struct fasync_struct *fa, **fp;
|
|
struct fasync_struct *new = NULL;
|
|
int result = 0;
|
|
|
|
if (on) {
|
|
new = kmem_cache_alloc(fasync_cache, GFP_KERNEL);
|
|
if (!new)
|
|
return -ENOMEM;
|
|
}
|
|
write_lock_irq(&fasync_lock);
|
|
for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
|
|
if (fa->fa_file == filp) {
|
|
if(on) {
|
|
fa->fa_fd = fd;
|
|
kmem_cache_free(fasync_cache, new);
|
|
} else {
|
|
*fp = fa->fa_next;
|
|
kmem_cache_free(fasync_cache, fa);
|
|
result = 1;
|
|
}
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
if (on) {
|
|
new->magic = FASYNC_MAGIC;
|
|
new->fa_file = filp;
|
|
new->fa_fd = fd;
|
|
new->fa_next = *fapp;
|
|
*fapp = new;
|
|
result = 1;
|
|
}
|
|
out:
|
|
/* Fix up FASYNC bit while still holding fasync_lock */
|
|
spin_lock(&filp->f_lock);
|
|
if (on)
|
|
filp->f_flags |= FASYNC;
|
|
else
|
|
filp->f_flags &= ~FASYNC;
|
|
spin_unlock(&filp->f_lock);
|
|
write_unlock_irq(&fasync_lock);
|
|
return result;
|
|
}
|
|
|
|
EXPORT_SYMBOL(fasync_helper);
|
|
|
|
void __kill_fasync(struct fasync_struct *fa, int sig, int band)
|
|
{
|
|
while (fa) {
|
|
struct fown_struct * fown;
|
|
if (fa->magic != FASYNC_MAGIC) {
|
|
printk(KERN_ERR "kill_fasync: bad magic number in "
|
|
"fasync_struct!\n");
|
|
return;
|
|
}
|
|
fown = &fa->fa_file->f_owner;
|
|
/* Don't send SIGURG to processes which have not set a
|
|
queued signum: SIGURG has its own default signalling
|
|
mechanism. */
|
|
if (!(sig == SIGURG && fown->signum == 0))
|
|
send_sigio(fown, fa->fa_fd, band);
|
|
fa = fa->fa_next;
|
|
}
|
|
}
|
|
|
|
EXPORT_SYMBOL(__kill_fasync);
|
|
|
|
void kill_fasync(struct fasync_struct **fp, int sig, int band)
|
|
{
|
|
/* First a quick test without locking: usually
|
|
* the list is empty.
|
|
*/
|
|
if (*fp) {
|
|
read_lock(&fasync_lock);
|
|
/* reread *fp after obtaining the lock */
|
|
__kill_fasync(*fp, sig, band);
|
|
read_unlock(&fasync_lock);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(kill_fasync);
|
|
|
|
static int __init fasync_init(void)
|
|
{
|
|
fasync_cache = kmem_cache_create("fasync_cache",
|
|
sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
|
|
return 0;
|
|
}
|
|
|
|
module_init(fasync_init)
|
|
|