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![Denis Efremov](/assets/img/avatar_default.png)
"unlikely(WARN_ON(x))" is excessive. WARN_ON() already uses unlikely() internally. Link: http://lkml.kernel.org/r/20190829165025.15750-5-efremov@linux.com Signed-off-by: Denis Efremov <efremov@linux.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1264 lines
30 KiB
C
1264 lines
30 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/fs/open.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/string.h>
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#include <linux/mm.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/fsnotify.h>
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#include <linux/module.h>
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#include <linux/tty.h>
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#include <linux/namei.h>
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#include <linux/backing-dev.h>
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#include <linux/capability.h>
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#include <linux/securebits.h>
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#include <linux/security.h>
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#include <linux/mount.h>
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#include <linux/fcntl.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/fs.h>
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#include <linux/personality.h>
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#include <linux/pagemap.h>
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#include <linux/syscalls.h>
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#include <linux/rcupdate.h>
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#include <linux/audit.h>
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#include <linux/falloc.h>
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#include <linux/fs_struct.h>
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#include <linux/ima.h>
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#include <linux/dnotify.h>
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#include <linux/compat.h>
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#include "internal.h"
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int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
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struct file *filp)
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{
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int ret;
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struct iattr newattrs;
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/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
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if (length < 0)
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return -EINVAL;
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newattrs.ia_size = length;
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newattrs.ia_valid = ATTR_SIZE | time_attrs;
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if (filp) {
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newattrs.ia_file = filp;
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newattrs.ia_valid |= ATTR_FILE;
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}
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/* Remove suid, sgid, and file capabilities on truncate too */
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ret = dentry_needs_remove_privs(dentry);
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if (ret < 0)
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return ret;
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if (ret)
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newattrs.ia_valid |= ret | ATTR_FORCE;
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inode_lock(dentry->d_inode);
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/* Note any delegations or leases have already been broken: */
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ret = notify_change(dentry, &newattrs, NULL);
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inode_unlock(dentry->d_inode);
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return ret;
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}
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long vfs_truncate(const struct path *path, loff_t length)
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{
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struct inode *inode;
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long error;
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inode = path->dentry->d_inode;
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/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
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if (S_ISDIR(inode->i_mode))
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return -EISDIR;
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if (!S_ISREG(inode->i_mode))
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return -EINVAL;
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error = mnt_want_write(path->mnt);
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if (error)
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goto out;
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error = inode_permission(inode, MAY_WRITE);
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if (error)
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goto mnt_drop_write_and_out;
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error = -EPERM;
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if (IS_APPEND(inode))
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goto mnt_drop_write_and_out;
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error = get_write_access(inode);
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if (error)
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goto mnt_drop_write_and_out;
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/*
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* Make sure that there are no leases. get_write_access() protects
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* against the truncate racing with a lease-granting setlease().
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*/
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error = break_lease(inode, O_WRONLY);
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if (error)
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goto put_write_and_out;
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error = locks_verify_truncate(inode, NULL, length);
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if (!error)
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error = security_path_truncate(path);
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if (!error)
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error = do_truncate(path->dentry, length, 0, NULL);
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put_write_and_out:
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put_write_access(inode);
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mnt_drop_write_and_out:
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mnt_drop_write(path->mnt);
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out:
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return error;
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}
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EXPORT_SYMBOL_GPL(vfs_truncate);
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long do_sys_truncate(const char __user *pathname, loff_t length)
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{
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unsigned int lookup_flags = LOOKUP_FOLLOW;
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struct path path;
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int error;
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if (length < 0) /* sorry, but loff_t says... */
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return -EINVAL;
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retry:
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error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
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if (!error) {
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error = vfs_truncate(&path, length);
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path_put(&path);
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}
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if (retry_estale(error, lookup_flags)) {
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lookup_flags |= LOOKUP_REVAL;
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goto retry;
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}
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return error;
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}
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SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
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{
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return do_sys_truncate(path, length);
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}
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#ifdef CONFIG_COMPAT
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COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
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{
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return do_sys_truncate(path, length);
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}
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#endif
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long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
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{
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struct inode *inode;
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struct dentry *dentry;
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struct fd f;
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int error;
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error = -EINVAL;
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if (length < 0)
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goto out;
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error = -EBADF;
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f = fdget(fd);
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if (!f.file)
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goto out;
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/* explicitly opened as large or we are on 64-bit box */
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if (f.file->f_flags & O_LARGEFILE)
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small = 0;
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dentry = f.file->f_path.dentry;
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inode = dentry->d_inode;
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error = -EINVAL;
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if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
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goto out_putf;
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error = -EINVAL;
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/* Cannot ftruncate over 2^31 bytes without large file support */
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if (small && length > MAX_NON_LFS)
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goto out_putf;
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error = -EPERM;
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/* Check IS_APPEND on real upper inode */
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if (IS_APPEND(file_inode(f.file)))
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goto out_putf;
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sb_start_write(inode->i_sb);
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error = locks_verify_truncate(inode, f.file, length);
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if (!error)
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error = security_path_truncate(&f.file->f_path);
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if (!error)
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error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
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sb_end_write(inode->i_sb);
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out_putf:
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fdput(f);
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out:
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return error;
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}
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SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
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{
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return do_sys_ftruncate(fd, length, 1);
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}
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#ifdef CONFIG_COMPAT
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COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
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{
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return do_sys_ftruncate(fd, length, 1);
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}
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#endif
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/* LFS versions of truncate are only needed on 32 bit machines */
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#if BITS_PER_LONG == 32
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SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
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{
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return do_sys_truncate(path, length);
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}
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SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
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{
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return do_sys_ftruncate(fd, length, 0);
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}
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#endif /* BITS_PER_LONG == 32 */
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int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
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{
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struct inode *inode = file_inode(file);
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long ret;
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if (offset < 0 || len <= 0)
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return -EINVAL;
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/* Return error if mode is not supported */
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if (mode & ~FALLOC_FL_SUPPORTED_MASK)
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return -EOPNOTSUPP;
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/* Punch hole and zero range are mutually exclusive */
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if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
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(FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
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return -EOPNOTSUPP;
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/* Punch hole must have keep size set */
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if ((mode & FALLOC_FL_PUNCH_HOLE) &&
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!(mode & FALLOC_FL_KEEP_SIZE))
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return -EOPNOTSUPP;
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/* Collapse range should only be used exclusively. */
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if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
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(mode & ~FALLOC_FL_COLLAPSE_RANGE))
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return -EINVAL;
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/* Insert range should only be used exclusively. */
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if ((mode & FALLOC_FL_INSERT_RANGE) &&
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(mode & ~FALLOC_FL_INSERT_RANGE))
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return -EINVAL;
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/* Unshare range should only be used with allocate mode. */
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if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
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(mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
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return -EINVAL;
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if (!(file->f_mode & FMODE_WRITE))
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return -EBADF;
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/*
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* We can only allow pure fallocate on append only files
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*/
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if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
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return -EPERM;
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if (IS_IMMUTABLE(inode))
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return -EPERM;
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/*
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* We cannot allow any fallocate operation on an active swapfile
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*/
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if (IS_SWAPFILE(inode))
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return -ETXTBSY;
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/*
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* Revalidate the write permissions, in case security policy has
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* changed since the files were opened.
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*/
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ret = security_file_permission(file, MAY_WRITE);
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if (ret)
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return ret;
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if (S_ISFIFO(inode->i_mode))
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return -ESPIPE;
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if (S_ISDIR(inode->i_mode))
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return -EISDIR;
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if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
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return -ENODEV;
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/* Check for wrap through zero too */
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if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
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return -EFBIG;
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if (!file->f_op->fallocate)
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return -EOPNOTSUPP;
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file_start_write(file);
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ret = file->f_op->fallocate(file, mode, offset, len);
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/*
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* Create inotify and fanotify events.
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*
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* To keep the logic simple always create events if fallocate succeeds.
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* This implies that events are even created if the file size remains
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* unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
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*/
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if (ret == 0)
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fsnotify_modify(file);
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file_end_write(file);
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return ret;
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}
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EXPORT_SYMBOL_GPL(vfs_fallocate);
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int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
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{
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struct fd f = fdget(fd);
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int error = -EBADF;
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if (f.file) {
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error = vfs_fallocate(f.file, mode, offset, len);
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fdput(f);
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}
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return error;
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}
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SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
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{
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return ksys_fallocate(fd, mode, offset, len);
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}
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/*
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* access() needs to use the real uid/gid, not the effective uid/gid.
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* We do this by temporarily clearing all FS-related capabilities and
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* switching the fsuid/fsgid around to the real ones.
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*/
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long do_faccessat(int dfd, const char __user *filename, int mode)
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{
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const struct cred *old_cred;
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struct cred *override_cred;
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struct path path;
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struct inode *inode;
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int res;
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unsigned int lookup_flags = LOOKUP_FOLLOW;
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if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
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return -EINVAL;
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override_cred = prepare_creds();
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if (!override_cred)
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return -ENOMEM;
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override_cred->fsuid = override_cred->uid;
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override_cred->fsgid = override_cred->gid;
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if (!issecure(SECURE_NO_SETUID_FIXUP)) {
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/* Clear the capabilities if we switch to a non-root user */
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kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
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if (!uid_eq(override_cred->uid, root_uid))
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cap_clear(override_cred->cap_effective);
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else
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override_cred->cap_effective =
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override_cred->cap_permitted;
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}
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|
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/*
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* The new set of credentials can *only* be used in
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* task-synchronous circumstances, and does not need
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* RCU freeing, unless somebody then takes a separate
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* reference to it.
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*
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* NOTE! This is _only_ true because this credential
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* is used purely for override_creds() that installs
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* it as the subjective cred. Other threads will be
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* accessing ->real_cred, not the subjective cred.
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*
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* If somebody _does_ make a copy of this (using the
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* 'get_current_cred()' function), that will clear the
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* non_rcu field, because now that other user may be
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* expecting RCU freeing. But normal thread-synchronous
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* cred accesses will keep things non-RCY.
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*/
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override_cred->non_rcu = 1;
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old_cred = override_creds(override_cred);
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retry:
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res = user_path_at(dfd, filename, lookup_flags, &path);
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if (res)
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goto out;
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inode = d_backing_inode(path.dentry);
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|
|
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if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
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/*
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* MAY_EXEC on regular files is denied if the fs is mounted
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* with the "noexec" flag.
|
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*/
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res = -EACCES;
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if (path_noexec(&path))
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goto out_path_release;
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}
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|
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res = inode_permission(inode, mode | MAY_ACCESS);
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/* SuS v2 requires we report a read only fs too */
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if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
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goto out_path_release;
|
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/*
|
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* This is a rare case where using __mnt_is_readonly()
|
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* is OK without a mnt_want/drop_write() pair. Since
|
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* no actual write to the fs is performed here, we do
|
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* not need to telegraph to that to anyone.
|
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*
|
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* By doing this, we accept that this access is
|
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* inherently racy and know that the fs may change
|
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* state before we even see this result.
|
|
*/
|
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if (__mnt_is_readonly(path.mnt))
|
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res = -EROFS;
|
|
|
|
out_path_release:
|
|
path_put(&path);
|
|
if (retry_estale(res, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out:
|
|
revert_creds(old_cred);
|
|
put_cred(override_cred);
|
|
return res;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
|
|
{
|
|
return do_faccessat(dfd, filename, mode);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
|
|
{
|
|
return do_faccessat(AT_FDCWD, filename, mode);
|
|
}
|
|
|
|
int ksys_chdir(const char __user *filename)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
|
|
retry:
|
|
error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
|
|
if (error)
|
|
goto dput_and_out;
|
|
|
|
set_fs_pwd(current->fs, &path);
|
|
|
|
dput_and_out:
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(chdir, const char __user *, filename)
|
|
{
|
|
return ksys_chdir(filename);
|
|
}
|
|
|
|
SYSCALL_DEFINE1(fchdir, unsigned int, fd)
|
|
{
|
|
struct fd f = fdget_raw(fd);
|
|
int error;
|
|
|
|
error = -EBADF;
|
|
if (!f.file)
|
|
goto out;
|
|
|
|
error = -ENOTDIR;
|
|
if (!d_can_lookup(f.file->f_path.dentry))
|
|
goto out_putf;
|
|
|
|
error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
|
|
if (!error)
|
|
set_fs_pwd(current->fs, &f.file->f_path);
|
|
out_putf:
|
|
fdput(f);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
int ksys_chroot(const char __user *filename)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
|
|
retry:
|
|
error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
|
|
if (error)
|
|
goto dput_and_out;
|
|
|
|
error = -EPERM;
|
|
if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
|
|
goto dput_and_out;
|
|
error = security_path_chroot(&path);
|
|
if (error)
|
|
goto dput_and_out;
|
|
|
|
set_fs_root(current->fs, &path);
|
|
error = 0;
|
|
dput_and_out:
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(chroot, const char __user *, filename)
|
|
{
|
|
return ksys_chroot(filename);
|
|
}
|
|
|
|
static int chmod_common(const struct path *path, umode_t mode)
|
|
{
|
|
struct inode *inode = path->dentry->d_inode;
|
|
struct inode *delegated_inode = NULL;
|
|
struct iattr newattrs;
|
|
int error;
|
|
|
|
error = mnt_want_write(path->mnt);
|
|
if (error)
|
|
return error;
|
|
retry_deleg:
|
|
inode_lock(inode);
|
|
error = security_path_chmod(path, mode);
|
|
if (error)
|
|
goto out_unlock;
|
|
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
|
|
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
|
|
error = notify_change(path->dentry, &newattrs, &delegated_inode);
|
|
out_unlock:
|
|
inode_unlock(inode);
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error)
|
|
goto retry_deleg;
|
|
}
|
|
mnt_drop_write(path->mnt);
|
|
return error;
|
|
}
|
|
|
|
int ksys_fchmod(unsigned int fd, umode_t mode)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
int err = -EBADF;
|
|
|
|
if (f.file) {
|
|
audit_file(f.file);
|
|
err = chmod_common(&f.file->f_path, mode);
|
|
fdput(f);
|
|
}
|
|
return err;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
|
|
{
|
|
return ksys_fchmod(fd, mode);
|
|
}
|
|
|
|
int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = LOOKUP_FOLLOW;
|
|
retry:
|
|
error = user_path_at(dfd, filename, lookup_flags, &path);
|
|
if (!error) {
|
|
error = chmod_common(&path, mode);
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
|
|
umode_t, mode)
|
|
{
|
|
return do_fchmodat(dfd, filename, mode);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
|
|
{
|
|
return do_fchmodat(AT_FDCWD, filename, mode);
|
|
}
|
|
|
|
static int chown_common(const struct path *path, uid_t user, gid_t group)
|
|
{
|
|
struct inode *inode = path->dentry->d_inode;
|
|
struct inode *delegated_inode = NULL;
|
|
int error;
|
|
struct iattr newattrs;
|
|
kuid_t uid;
|
|
kgid_t gid;
|
|
|
|
uid = make_kuid(current_user_ns(), user);
|
|
gid = make_kgid(current_user_ns(), group);
|
|
|
|
retry_deleg:
|
|
newattrs.ia_valid = ATTR_CTIME;
|
|
if (user != (uid_t) -1) {
|
|
if (!uid_valid(uid))
|
|
return -EINVAL;
|
|
newattrs.ia_valid |= ATTR_UID;
|
|
newattrs.ia_uid = uid;
|
|
}
|
|
if (group != (gid_t) -1) {
|
|
if (!gid_valid(gid))
|
|
return -EINVAL;
|
|
newattrs.ia_valid |= ATTR_GID;
|
|
newattrs.ia_gid = gid;
|
|
}
|
|
if (!S_ISDIR(inode->i_mode))
|
|
newattrs.ia_valid |=
|
|
ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
|
|
inode_lock(inode);
|
|
error = security_path_chown(path, uid, gid);
|
|
if (!error)
|
|
error = notify_change(path->dentry, &newattrs, &delegated_inode);
|
|
inode_unlock(inode);
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error)
|
|
goto retry_deleg;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
|
|
int flag)
|
|
{
|
|
struct path path;
|
|
int error = -EINVAL;
|
|
int lookup_flags;
|
|
|
|
if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
|
|
goto out;
|
|
|
|
lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
|
|
if (flag & AT_EMPTY_PATH)
|
|
lookup_flags |= LOOKUP_EMPTY;
|
|
retry:
|
|
error = user_path_at(dfd, filename, lookup_flags, &path);
|
|
if (error)
|
|
goto out;
|
|
error = mnt_want_write(path.mnt);
|
|
if (error)
|
|
goto out_release;
|
|
error = chown_common(&path, user, group);
|
|
mnt_drop_write(path.mnt);
|
|
out_release:
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
|
|
gid_t, group, int, flag)
|
|
{
|
|
return do_fchownat(dfd, filename, user, group, flag);
|
|
}
|
|
|
|
SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
|
|
{
|
|
return do_fchownat(AT_FDCWD, filename, user, group, 0);
|
|
}
|
|
|
|
SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
|
|
{
|
|
return do_fchownat(AT_FDCWD, filename, user, group,
|
|
AT_SYMLINK_NOFOLLOW);
|
|
}
|
|
|
|
int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
int error = -EBADF;
|
|
|
|
if (!f.file)
|
|
goto out;
|
|
|
|
error = mnt_want_write_file(f.file);
|
|
if (error)
|
|
goto out_fput;
|
|
audit_file(f.file);
|
|
error = chown_common(&f.file->f_path, user, group);
|
|
mnt_drop_write_file(f.file);
|
|
out_fput:
|
|
fdput(f);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
|
|
{
|
|
return ksys_fchown(fd, user, group);
|
|
}
|
|
|
|
static int do_dentry_open(struct file *f,
|
|
struct inode *inode,
|
|
int (*open)(struct inode *, struct file *))
|
|
{
|
|
static const struct file_operations empty_fops = {};
|
|
int error;
|
|
|
|
path_get(&f->f_path);
|
|
f->f_inode = inode;
|
|
f->f_mapping = inode->i_mapping;
|
|
|
|
/* Ensure that we skip any errors that predate opening of the file */
|
|
f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
|
|
|
|
if (unlikely(f->f_flags & O_PATH)) {
|
|
f->f_mode = FMODE_PATH | FMODE_OPENED;
|
|
f->f_op = &empty_fops;
|
|
return 0;
|
|
}
|
|
|
|
/* Any file opened for execve()/uselib() has to be a regular file. */
|
|
if (unlikely(f->f_flags & FMODE_EXEC && !S_ISREG(inode->i_mode))) {
|
|
error = -EACCES;
|
|
goto cleanup_file;
|
|
}
|
|
|
|
if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
|
|
error = get_write_access(inode);
|
|
if (unlikely(error))
|
|
goto cleanup_file;
|
|
error = __mnt_want_write(f->f_path.mnt);
|
|
if (unlikely(error)) {
|
|
put_write_access(inode);
|
|
goto cleanup_file;
|
|
}
|
|
f->f_mode |= FMODE_WRITER;
|
|
}
|
|
|
|
/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
|
|
if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
|
|
f->f_mode |= FMODE_ATOMIC_POS;
|
|
|
|
f->f_op = fops_get(inode->i_fop);
|
|
if (WARN_ON(!f->f_op)) {
|
|
error = -ENODEV;
|
|
goto cleanup_all;
|
|
}
|
|
|
|
error = security_file_open(f);
|
|
if (error)
|
|
goto cleanup_all;
|
|
|
|
error = break_lease(locks_inode(f), f->f_flags);
|
|
if (error)
|
|
goto cleanup_all;
|
|
|
|
/* normally all 3 are set; ->open() can clear them if needed */
|
|
f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
|
|
if (!open)
|
|
open = f->f_op->open;
|
|
if (open) {
|
|
error = open(inode, f);
|
|
if (error)
|
|
goto cleanup_all;
|
|
}
|
|
f->f_mode |= FMODE_OPENED;
|
|
if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
|
|
i_readcount_inc(inode);
|
|
if ((f->f_mode & FMODE_READ) &&
|
|
likely(f->f_op->read || f->f_op->read_iter))
|
|
f->f_mode |= FMODE_CAN_READ;
|
|
if ((f->f_mode & FMODE_WRITE) &&
|
|
likely(f->f_op->write || f->f_op->write_iter))
|
|
f->f_mode |= FMODE_CAN_WRITE;
|
|
|
|
f->f_write_hint = WRITE_LIFE_NOT_SET;
|
|
f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
|
|
|
|
file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
|
|
|
|
/* NB: we're sure to have correct a_ops only after f_op->open */
|
|
if (f->f_flags & O_DIRECT) {
|
|
if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* XXX: Huge page cache doesn't support writing yet. Drop all page
|
|
* cache for this file before processing writes.
|
|
*/
|
|
if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping))
|
|
truncate_pagecache(inode, 0);
|
|
|
|
return 0;
|
|
|
|
cleanup_all:
|
|
if (WARN_ON_ONCE(error > 0))
|
|
error = -EINVAL;
|
|
fops_put(f->f_op);
|
|
if (f->f_mode & FMODE_WRITER) {
|
|
put_write_access(inode);
|
|
__mnt_drop_write(f->f_path.mnt);
|
|
}
|
|
cleanup_file:
|
|
path_put(&f->f_path);
|
|
f->f_path.mnt = NULL;
|
|
f->f_path.dentry = NULL;
|
|
f->f_inode = NULL;
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* finish_open - finish opening a file
|
|
* @file: file pointer
|
|
* @dentry: pointer to dentry
|
|
* @open: open callback
|
|
* @opened: state of open
|
|
*
|
|
* This can be used to finish opening a file passed to i_op->atomic_open().
|
|
*
|
|
* If the open callback is set to NULL, then the standard f_op->open()
|
|
* filesystem callback is substituted.
|
|
*
|
|
* NB: the dentry reference is _not_ consumed. If, for example, the dentry is
|
|
* the return value of d_splice_alias(), then the caller needs to perform dput()
|
|
* on it after finish_open().
|
|
*
|
|
* On successful return @file is a fully instantiated open file. After this, if
|
|
* an error occurs in ->atomic_open(), it needs to clean up with fput().
|
|
*
|
|
* Returns zero on success or -errno if the open failed.
|
|
*/
|
|
int finish_open(struct file *file, struct dentry *dentry,
|
|
int (*open)(struct inode *, struct file *))
|
|
{
|
|
BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
|
|
|
|
file->f_path.dentry = dentry;
|
|
return do_dentry_open(file, d_backing_inode(dentry), open);
|
|
}
|
|
EXPORT_SYMBOL(finish_open);
|
|
|
|
/**
|
|
* finish_no_open - finish ->atomic_open() without opening the file
|
|
*
|
|
* @file: file pointer
|
|
* @dentry: dentry or NULL (as returned from ->lookup())
|
|
*
|
|
* This can be used to set the result of a successful lookup in ->atomic_open().
|
|
*
|
|
* NB: unlike finish_open() this function does consume the dentry reference and
|
|
* the caller need not dput() it.
|
|
*
|
|
* Returns "0" which must be the return value of ->atomic_open() after having
|
|
* called this function.
|
|
*/
|
|
int finish_no_open(struct file *file, struct dentry *dentry)
|
|
{
|
|
file->f_path.dentry = dentry;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(finish_no_open);
|
|
|
|
char *file_path(struct file *filp, char *buf, int buflen)
|
|
{
|
|
return d_path(&filp->f_path, buf, buflen);
|
|
}
|
|
EXPORT_SYMBOL(file_path);
|
|
|
|
/**
|
|
* vfs_open - open the file at the given path
|
|
* @path: path to open
|
|
* @file: newly allocated file with f_flag initialized
|
|
* @cred: credentials to use
|
|
*/
|
|
int vfs_open(const struct path *path, struct file *file)
|
|
{
|
|
file->f_path = *path;
|
|
return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
|
|
}
|
|
|
|
struct file *dentry_open(const struct path *path, int flags,
|
|
const struct cred *cred)
|
|
{
|
|
int error;
|
|
struct file *f;
|
|
|
|
validate_creds(cred);
|
|
|
|
/* We must always pass in a valid mount pointer. */
|
|
BUG_ON(!path->mnt);
|
|
|
|
f = alloc_empty_file(flags, cred);
|
|
if (!IS_ERR(f)) {
|
|
error = vfs_open(path, f);
|
|
if (error) {
|
|
fput(f);
|
|
f = ERR_PTR(error);
|
|
}
|
|
}
|
|
return f;
|
|
}
|
|
EXPORT_SYMBOL(dentry_open);
|
|
|
|
struct file *open_with_fake_path(const struct path *path, int flags,
|
|
struct inode *inode, const struct cred *cred)
|
|
{
|
|
struct file *f = alloc_empty_file_noaccount(flags, cred);
|
|
if (!IS_ERR(f)) {
|
|
int error;
|
|
|
|
f->f_path = *path;
|
|
error = do_dentry_open(f, inode, NULL);
|
|
if (error) {
|
|
fput(f);
|
|
f = ERR_PTR(error);
|
|
}
|
|
}
|
|
return f;
|
|
}
|
|
EXPORT_SYMBOL(open_with_fake_path);
|
|
|
|
static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
|
|
{
|
|
int lookup_flags = 0;
|
|
int acc_mode = ACC_MODE(flags);
|
|
|
|
/*
|
|
* Clear out all open flags we don't know about so that we don't report
|
|
* them in fcntl(F_GETFD) or similar interfaces.
|
|
*/
|
|
flags &= VALID_OPEN_FLAGS;
|
|
|
|
if (flags & (O_CREAT | __O_TMPFILE))
|
|
op->mode = (mode & S_IALLUGO) | S_IFREG;
|
|
else
|
|
op->mode = 0;
|
|
|
|
/* Must never be set by userspace */
|
|
flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
|
|
|
|
/*
|
|
* O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
|
|
* check for O_DSYNC if the need any syncing at all we enforce it's
|
|
* always set instead of having to deal with possibly weird behaviour
|
|
* for malicious applications setting only __O_SYNC.
|
|
*/
|
|
if (flags & __O_SYNC)
|
|
flags |= O_DSYNC;
|
|
|
|
if (flags & __O_TMPFILE) {
|
|
if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
|
|
return -EINVAL;
|
|
if (!(acc_mode & MAY_WRITE))
|
|
return -EINVAL;
|
|
} else if (flags & O_PATH) {
|
|
/*
|
|
* If we have O_PATH in the open flag. Then we
|
|
* cannot have anything other than the below set of flags
|
|
*/
|
|
flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
|
|
acc_mode = 0;
|
|
}
|
|
|
|
op->open_flag = flags;
|
|
|
|
/* O_TRUNC implies we need access checks for write permissions */
|
|
if (flags & O_TRUNC)
|
|
acc_mode |= MAY_WRITE;
|
|
|
|
/* Allow the LSM permission hook to distinguish append
|
|
access from general write access. */
|
|
if (flags & O_APPEND)
|
|
acc_mode |= MAY_APPEND;
|
|
|
|
op->acc_mode = acc_mode;
|
|
|
|
op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
|
|
|
|
if (flags & O_CREAT) {
|
|
op->intent |= LOOKUP_CREATE;
|
|
if (flags & O_EXCL)
|
|
op->intent |= LOOKUP_EXCL;
|
|
}
|
|
|
|
if (flags & O_DIRECTORY)
|
|
lookup_flags |= LOOKUP_DIRECTORY;
|
|
if (!(flags & O_NOFOLLOW))
|
|
lookup_flags |= LOOKUP_FOLLOW;
|
|
op->lookup_flags = lookup_flags;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* file_open_name - open file and return file pointer
|
|
*
|
|
* @name: struct filename containing path to open
|
|
* @flags: open flags as per the open(2) second argument
|
|
* @mode: mode for the new file if O_CREAT is set, else ignored
|
|
*
|
|
* This is the helper to open a file from kernelspace if you really
|
|
* have to. But in generally you should not do this, so please move
|
|
* along, nothing to see here..
|
|
*/
|
|
struct file *file_open_name(struct filename *name, int flags, umode_t mode)
|
|
{
|
|
struct open_flags op;
|
|
int err = build_open_flags(flags, mode, &op);
|
|
return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
|
|
}
|
|
|
|
/**
|
|
* filp_open - open file and return file pointer
|
|
*
|
|
* @filename: path to open
|
|
* @flags: open flags as per the open(2) second argument
|
|
* @mode: mode for the new file if O_CREAT is set, else ignored
|
|
*
|
|
* This is the helper to open a file from kernelspace if you really
|
|
* have to. But in generally you should not do this, so please move
|
|
* along, nothing to see here..
|
|
*/
|
|
struct file *filp_open(const char *filename, int flags, umode_t mode)
|
|
{
|
|
struct filename *name = getname_kernel(filename);
|
|
struct file *file = ERR_CAST(name);
|
|
|
|
if (!IS_ERR(name)) {
|
|
file = file_open_name(name, flags, mode);
|
|
putname(name);
|
|
}
|
|
return file;
|
|
}
|
|
EXPORT_SYMBOL(filp_open);
|
|
|
|
struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
|
|
const char *filename, int flags, umode_t mode)
|
|
{
|
|
struct open_flags op;
|
|
int err = build_open_flags(flags, mode, &op);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
return do_file_open_root(dentry, mnt, filename, &op);
|
|
}
|
|
EXPORT_SYMBOL(file_open_root);
|
|
|
|
long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
|
|
{
|
|
struct open_flags op;
|
|
int fd = build_open_flags(flags, mode, &op);
|
|
struct filename *tmp;
|
|
|
|
if (fd)
|
|
return fd;
|
|
|
|
tmp = getname(filename);
|
|
if (IS_ERR(tmp))
|
|
return PTR_ERR(tmp);
|
|
|
|
fd = get_unused_fd_flags(flags);
|
|
if (fd >= 0) {
|
|
struct file *f = do_filp_open(dfd, tmp, &op);
|
|
if (IS_ERR(f)) {
|
|
put_unused_fd(fd);
|
|
fd = PTR_ERR(f);
|
|
} else {
|
|
fsnotify_open(f);
|
|
fd_install(fd, f);
|
|
}
|
|
}
|
|
putname(tmp);
|
|
return fd;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
|
|
{
|
|
if (force_o_largefile())
|
|
flags |= O_LARGEFILE;
|
|
|
|
return do_sys_open(AT_FDCWD, filename, flags, mode);
|
|
}
|
|
|
|
SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
|
|
umode_t, mode)
|
|
{
|
|
if (force_o_largefile())
|
|
flags |= O_LARGEFILE;
|
|
|
|
return do_sys_open(dfd, filename, flags, mode);
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
/*
|
|
* Exactly like sys_open(), except that it doesn't set the
|
|
* O_LARGEFILE flag.
|
|
*/
|
|
COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
|
|
{
|
|
return do_sys_open(AT_FDCWD, filename, flags, mode);
|
|
}
|
|
|
|
/*
|
|
* Exactly like sys_openat(), except that it doesn't set the
|
|
* O_LARGEFILE flag.
|
|
*/
|
|
COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
|
|
{
|
|
return do_sys_open(dfd, filename, flags, mode);
|
|
}
|
|
#endif
|
|
|
|
#ifndef __alpha__
|
|
|
|
/*
|
|
* For backward compatibility? Maybe this should be moved
|
|
* into arch/i386 instead?
|
|
*/
|
|
SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
|
|
{
|
|
return ksys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
|
|
}
|
|
|
|
#endif
|
|
|
|
/*
|
|
* "id" is the POSIX thread ID. We use the
|
|
* files pointer for this..
|
|
*/
|
|
int filp_close(struct file *filp, fl_owner_t id)
|
|
{
|
|
int retval = 0;
|
|
|
|
if (!file_count(filp)) {
|
|
printk(KERN_ERR "VFS: Close: file count is 0\n");
|
|
return 0;
|
|
}
|
|
|
|
if (filp->f_op->flush)
|
|
retval = filp->f_op->flush(filp, id);
|
|
|
|
if (likely(!(filp->f_mode & FMODE_PATH))) {
|
|
dnotify_flush(filp, id);
|
|
locks_remove_posix(filp, id);
|
|
}
|
|
fput(filp);
|
|
return retval;
|
|
}
|
|
|
|
EXPORT_SYMBOL(filp_close);
|
|
|
|
/*
|
|
* Careful here! We test whether the file pointer is NULL before
|
|
* releasing the fd. This ensures that one clone task can't release
|
|
* an fd while another clone is opening it.
|
|
*/
|
|
SYSCALL_DEFINE1(close, unsigned int, fd)
|
|
{
|
|
int retval = __close_fd(current->files, fd);
|
|
|
|
/* can't restart close syscall because file table entry was cleared */
|
|
if (unlikely(retval == -ERESTARTSYS ||
|
|
retval == -ERESTARTNOINTR ||
|
|
retval == -ERESTARTNOHAND ||
|
|
retval == -ERESTART_RESTARTBLOCK))
|
|
retval = -EINTR;
|
|
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* This routine simulates a hangup on the tty, to arrange that users
|
|
* are given clean terminals at login time.
|
|
*/
|
|
SYSCALL_DEFINE0(vhangup)
|
|
{
|
|
if (capable(CAP_SYS_TTY_CONFIG)) {
|
|
tty_vhangup_self();
|
|
return 0;
|
|
}
|
|
return -EPERM;
|
|
}
|
|
|
|
/*
|
|
* Called when an inode is about to be open.
|
|
* We use this to disallow opening large files on 32bit systems if
|
|
* the caller didn't specify O_LARGEFILE. On 64bit systems we force
|
|
* on this flag in sys_open.
|
|
*/
|
|
int generic_file_open(struct inode * inode, struct file * filp)
|
|
{
|
|
if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
|
|
return -EOVERFLOW;
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_file_open);
|
|
|
|
/*
|
|
* This is used by subsystems that don't want seekable
|
|
* file descriptors. The function is not supposed to ever fail, the only
|
|
* reason it returns an 'int' and not 'void' is so that it can be plugged
|
|
* directly into file_operations structure.
|
|
*/
|
|
int nonseekable_open(struct inode *inode, struct file *filp)
|
|
{
|
|
filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(nonseekable_open);
|
|
|
|
/*
|
|
* stream_open is used by subsystems that want stream-like file descriptors.
|
|
* Such file descriptors are not seekable and don't have notion of position
|
|
* (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
|
|
* Contrary to file descriptors of other regular files, .read() and .write()
|
|
* can run simultaneously.
|
|
*
|
|
* stream_open never fails and is marked to return int so that it could be
|
|
* directly used as file_operations.open .
|
|
*/
|
|
int stream_open(struct inode *inode, struct file *filp)
|
|
{
|
|
filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
|
|
filp->f_mode |= FMODE_STREAM;
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(stream_open);
|