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![Vadim Lobanov](/assets/img/avatar_default.png)
Currently, each fdtable supports three dynamically-sized arrays of data: the fdarray and two fdsets. The code allows the number of fds supported by the fdarray (fdtable->max_fds) to differ from the number of fds supported by each of the fdsets (fdtable->max_fdset). In practice, it is wasteful for these two sizes to differ: whenever we hit a limit on the smaller-capacity structure, we will reallocate the entire fdtable and all the dynamic arrays within it, so any delta in the memory used by the larger-capacity structure will never be touched at all. Rather than hogging this excess, we shouldn't even allocate it in the first place, and keep the capacities of the fdarray and the fdsets equal. This patch removes fdtable->max_fdset. As an added bonus, most of the supporting code becomes simpler. Signed-off-by: Vadim Lobanov <vlobanov@speakeasy.net> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dipankar Sarma <dipankar@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
645 lines
14 KiB
C
645 lines
14 KiB
C
/*
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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/capability.h>
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#include <linux/dnotify.h>
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#include <linux/smp_lock.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 <asm/poll.h>
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#include <asm/siginfo.h>
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#include <asm/uaccess.h>
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void fastcall 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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/*
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* locate_fd finds a free file descriptor in the open_fds fdset,
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* expanding the fd arrays if necessary. Must be called with the
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* file_lock held for write.
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*/
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static int locate_fd(struct files_struct *files,
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struct file *file, unsigned int orig_start)
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{
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unsigned int newfd;
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unsigned int start;
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int error;
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struct fdtable *fdt;
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error = -EINVAL;
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if (orig_start >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
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goto out;
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repeat:
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fdt = files_fdtable(files);
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/*
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* Someone might have closed fd's in the range
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* orig_start..fdt->next_fd
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*/
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start = orig_start;
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if (start < files->next_fd)
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start = files->next_fd;
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newfd = start;
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if (start < fdt->max_fds)
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newfd = find_next_zero_bit(fdt->open_fds->fds_bits,
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fdt->max_fds, start);
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error = -EMFILE;
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if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
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goto out;
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error = expand_files(files, newfd);
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if (error < 0)
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goto out;
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/*
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* If we needed to expand the fs array we
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* might have blocked - try again.
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*/
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if (error)
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goto repeat;
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/*
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* We reacquired files_lock, so we are safe as long as
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* we reacquire the fdtable pointer and use it while holding
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* the lock, no one can free it during that time.
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*/
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if (start <= files->next_fd)
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files->next_fd = newfd + 1;
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error = newfd;
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out:
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return error;
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}
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static int dupfd(struct file *file, unsigned int start)
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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 fd;
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spin_lock(&files->file_lock);
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fd = locate_fd(files, file, start);
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if (fd >= 0) {
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/* locate_fd() may have expanded fdtable, load the ptr */
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fdt = files_fdtable(files);
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FD_SET(fd, fdt->open_fds);
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FD_CLR(fd, fdt->close_on_exec);
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spin_unlock(&files->file_lock);
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fd_install(fd, file);
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} else {
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spin_unlock(&files->file_lock);
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fput(file);
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}
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return fd;
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}
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asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)
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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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spin_lock(&files->file_lock);
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if (!(file = fcheck(oldfd)))
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goto out_unlock;
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err = newfd;
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if (newfd == oldfd)
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goto out_unlock;
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err = -EBADF;
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if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
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goto out_unlock;
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get_file(file); /* We are now finished with oldfd */
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err = expand_files(files, newfd);
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if (err < 0)
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goto out_fput;
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/* To avoid races with open() and dup(), we will mark the fd as
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* in-use in the open-file bitmap throughout the entire dup2()
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* process. This is quite safe: do_close() uses the fd array
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* entry, not the bitmap, to decide what work needs to be
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* done. --sct */
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/* Doesn't work. open() might be there first. --AV */
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/* Yes. It's a race. In user space. Nothing sane to do */
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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_fput;
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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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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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err = newfd;
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out:
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return err;
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out_unlock:
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spin_unlock(&files->file_lock);
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goto out;
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out_fput:
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spin_unlock(&files->file_lock);
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fput(file);
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goto out;
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}
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asmlinkage long sys_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 = dupfd(file, 0);
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return ret;
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}
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#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | 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 (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
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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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lock_kernel();
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if ((arg ^ filp->f_flags) & FASYNC) {
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if (filp->f_op && 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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}
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}
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filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
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out:
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unlock_kernel();
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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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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, current->uid, current->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_pid(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_nr(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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get_file(filp);
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err = dupfd(filp, arg);
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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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asmlinkage long sys_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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asmlinkage long sys_fcntl64(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;
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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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return (((fown->euid == 0) ||
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(fown->euid == p->suid) || (fown->euid == p->uid) ||
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(fown->uid == p->suid) || (fown->uid == p->uid)) &&
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!security_file_send_sigiotask(p, fown, sig));
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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;
|
|
|
|
read_lock(&tasklist_lock);
|
|
do_each_pid_task(pid, type, p) {
|
|
send_sigio_to_task(p, fown, fd, band);
|
|
} while_each_pid_task(pid, type, p);
|
|
read_unlock(&tasklist_lock);
|
|
out_unlock_fown:
|
|
read_unlock(&fown->lock);
|
|
}
|
|
|
|
static void send_sigurg_to_task(struct task_struct *p,
|
|
struct fown_struct *fown)
|
|
{
|
|
if (sigio_perm(p, fown, SIGURG))
|
|
group_send_sig_info(SIGURG, SEND_SIG_PRIV, p);
|
|
}
|
|
|
|
int send_sigurg(struct fown_struct *fown)
|
|
{
|
|
struct task_struct *p;
|
|
enum pid_type type;
|
|
struct pid *pid;
|
|
int ret = 0;
|
|
|
|
read_lock(&fown->lock);
|
|
type = fown->pid_type;
|
|
pid = fown->pid;
|
|
if (!pid)
|
|
goto out_unlock_fown;
|
|
|
|
ret = 1;
|
|
|
|
read_lock(&tasklist_lock);
|
|
do_each_pid_task(pid, type, p) {
|
|
send_sigurg_to_task(p, fown);
|
|
} while_each_pid_task(pid, type, p);
|
|
read_unlock(&tasklist_lock);
|
|
out_unlock_fown:
|
|
read_unlock(&fown->lock);
|
|
return ret;
|
|
}
|
|
|
|
static DEFINE_RWLOCK(fasync_lock);
|
|
static struct kmem_cache *fasync_cache __read_mostly;
|
|
|
|
/*
|
|
* fasync_helper() is used by some character device drivers (mainly mice)
|
|
* to set up the fasync queue. It returns negative on error, 0 if it did
|
|
* no changes and positive if it added/deleted the entry.
|
|
*/
|
|
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:
|
|
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, NULL);
|
|
return 0;
|
|
}
|
|
|
|
module_init(fasync_init)
|