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f3c7691e8d
In setlease, we use i_writecount to decide whether we can give out a read lease. In open, we break leases before incrementing i_writecount. There is therefore a window between the break lease and the i_writecount increment when setlease could add a new read lease. This would leave us with a simultaneous write open and read lease, which shouldn't happen. Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
1144 lines
26 KiB
C
1144 lines
26 KiB
C
/*
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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 <asm/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 "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 on truncate too */
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ret = should_remove_suid(dentry);
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if (ret)
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newattrs.ia_valid |= ret | ATTR_FORCE;
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mutex_lock(&dentry->d_inode->i_mutex);
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ret = notify_change(dentry, &newattrs);
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mutex_unlock(&dentry->d_inode->i_mutex);
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return ret;
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}
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static long do_sys_truncate(const char __user *pathname, loff_t length)
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{
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struct path path;
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struct inode *inode;
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int error;
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error = -EINVAL;
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if (length < 0) /* sorry, but loff_t says... */
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goto out;
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error = user_path(pathname, &path);
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if (error)
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goto out;
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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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error = -EISDIR;
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if (S_ISDIR(inode->i_mode))
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goto dput_and_out;
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error = -EINVAL;
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if (!S_ISREG(inode->i_mode))
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goto dput_and_out;
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error = mnt_want_write(path.mnt);
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if (error)
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goto dput_and_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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dput_and_out:
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path_put(&path);
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out:
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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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static 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 file * file;
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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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file = fget(fd);
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if (!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 (file->f_flags & O_LARGEFILE)
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small = 0;
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dentry = 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) || !(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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if (IS_APPEND(inode))
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goto out_putf;
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error = locks_verify_truncate(inode, file, length);
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if (!error)
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error = security_path_truncate(&file->f_path);
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if (!error)
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error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
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out_putf:
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fput(file);
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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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long ret = do_sys_ftruncate(fd, length, 1);
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/* avoid REGPARM breakage on x86: */
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asmlinkage_protect(2, ret, fd, length);
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return ret;
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}
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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_DEFINE(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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#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
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asmlinkage long SyS_truncate64(long path, loff_t length)
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{
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return SYSC_truncate64((const char __user *) path, length);
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}
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SYSCALL_ALIAS(sys_truncate64, SyS_truncate64);
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#endif
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SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
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{
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long ret = do_sys_ftruncate(fd, length, 0);
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/* avoid REGPARM breakage on x86: */
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asmlinkage_protect(2, ret, fd, length);
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return ret;
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}
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#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
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asmlinkage long SyS_ftruncate64(long fd, loff_t length)
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{
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return SYSC_ftruncate64((unsigned int) fd, length);
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}
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SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
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#endif
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#endif /* BITS_PER_LONG == 32 */
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int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
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{
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struct inode *inode = file->f_path.dentry->d_inode;
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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_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
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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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if (!(file->f_mode & FMODE_WRITE))
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return -EBADF;
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/* It's not possible punch hole on append only file */
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if (mode & FALLOC_FL_PUNCH_HOLE && 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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* 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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/*
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* Let individual file system decide if it supports preallocation
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* for directories or not.
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*/
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if (!S_ISREG(inode->i_mode) && !S_ISDIR(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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return file->f_op->fallocate(file, mode, offset, len);
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}
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SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
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{
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struct file *file;
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int error = -EBADF;
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file = fget(fd);
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if (file) {
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error = do_fallocate(file, mode, offset, len);
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fput(file);
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}
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return error;
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}
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#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
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asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len)
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{
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return SYSC_fallocate((int)fd, (int)mode, offset, len);
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}
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SYSCALL_ALIAS(sys_fallocate, SyS_fallocate);
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#endif
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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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SYSCALL_DEFINE3(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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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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if (override_cred->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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old_cred = override_creds(override_cred);
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res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
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if (res)
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goto out;
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inode = path.dentry->d_inode;
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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.mnt->mnt_flags & MNT_NOEXEC)
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goto out_path_release;
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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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*/
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if (__mnt_is_readonly(path.mnt))
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res = -EROFS;
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out_path_release:
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path_put(&path);
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out:
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revert_creds(old_cred);
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put_cred(override_cred);
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return res;
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}
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SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
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{
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return sys_faccessat(AT_FDCWD, filename, mode);
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}
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SYSCALL_DEFINE1(chdir, const char __user *, filename)
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{
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struct path path;
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int error;
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error = user_path_dir(filename, &path);
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if (error)
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goto out;
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error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
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if (error)
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goto dput_and_out;
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set_fs_pwd(current->fs, &path);
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dput_and_out:
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path_put(&path);
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out:
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return error;
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}
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SYSCALL_DEFINE1(fchdir, unsigned int, fd)
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{
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struct file *file;
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struct inode *inode;
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int error;
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error = -EBADF;
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file = fget(fd);
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if (!file)
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goto out;
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inode = file->f_path.dentry->d_inode;
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error = -ENOTDIR;
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if (!S_ISDIR(inode->i_mode))
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goto out_putf;
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error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
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if (!error)
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set_fs_pwd(current->fs, &file->f_path);
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out_putf:
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fput(file);
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out:
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return error;
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}
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SYSCALL_DEFINE1(chroot, const char __user *, filename)
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{
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struct path path;
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int error;
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error = user_path_dir(filename, &path);
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if (error)
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goto out;
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error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
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if (error)
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goto dput_and_out;
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error = -EPERM;
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if (!capable(CAP_SYS_CHROOT))
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goto dput_and_out;
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error = security_path_chroot(&path);
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if (error)
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goto dput_and_out;
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set_fs_root(current->fs, &path);
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error = 0;
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dput_and_out:
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path_put(&path);
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out:
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return error;
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}
|
|
|
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static int chmod_common(struct path *path, umode_t mode)
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{
|
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struct inode *inode = path->dentry->d_inode;
|
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struct iattr newattrs;
|
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int error;
|
|
|
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error = mnt_want_write(path->mnt);
|
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if (error)
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return error;
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mutex_lock(&inode->i_mutex);
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error = security_path_chmod(path->dentry, path->mnt, mode);
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if (error)
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goto out_unlock;
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newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
|
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newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
|
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error = notify_change(path->dentry, &newattrs);
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out_unlock:
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mutex_unlock(&inode->i_mutex);
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mnt_drop_write(path->mnt);
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return error;
|
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}
|
|
|
|
SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
|
|
{
|
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struct file * file;
|
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int err = -EBADF;
|
|
|
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file = fget(fd);
|
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if (file) {
|
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audit_inode(NULL, file->f_path.dentry);
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err = chmod_common(&file->f_path, mode);
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fput(file);
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}
|
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return err;
|
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}
|
|
|
|
SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
|
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error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
|
|
if (!error) {
|
|
error = chmod_common(&path, mode);
|
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path_put(&path);
|
|
}
|
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return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode)
|
|
{
|
|
return sys_fchmodat(AT_FDCWD, filename, mode);
|
|
}
|
|
|
|
static int chown_common(struct path *path, uid_t user, gid_t group)
|
|
{
|
|
struct inode *inode = path->dentry->d_inode;
|
|
int error;
|
|
struct iattr newattrs;
|
|
|
|
newattrs.ia_valid = ATTR_CTIME;
|
|
if (user != (uid_t) -1) {
|
|
newattrs.ia_valid |= ATTR_UID;
|
|
newattrs.ia_uid = user;
|
|
}
|
|
if (group != (gid_t) -1) {
|
|
newattrs.ia_valid |= ATTR_GID;
|
|
newattrs.ia_gid = group;
|
|
}
|
|
if (!S_ISDIR(inode->i_mode))
|
|
newattrs.ia_valid |=
|
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ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
|
|
mutex_lock(&inode->i_mutex);
|
|
error = security_path_chown(path, user, group);
|
|
if (!error)
|
|
error = notify_change(path->dentry, &newattrs);
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
|
|
error = user_path(filename, &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);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE5(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;
|
|
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);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
|
|
error = user_lpath(filename, &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);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
|
|
{
|
|
struct file * file;
|
|
int error = -EBADF;
|
|
struct dentry * dentry;
|
|
|
|
file = fget(fd);
|
|
if (!file)
|
|
goto out;
|
|
|
|
error = mnt_want_write_file(file);
|
|
if (error)
|
|
goto out_fput;
|
|
dentry = file->f_path.dentry;
|
|
audit_inode(NULL, dentry);
|
|
error = chown_common(&file->f_path, user, group);
|
|
mnt_drop_write(file->f_path.mnt);
|
|
out_fput:
|
|
fput(file);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* You have to be very careful that these write
|
|
* counts get cleaned up in error cases and
|
|
* upon __fput(). This should probably never
|
|
* be called outside of __dentry_open().
|
|
*/
|
|
static inline int __get_file_write_access(struct inode *inode,
|
|
struct vfsmount *mnt)
|
|
{
|
|
int error;
|
|
error = get_write_access(inode);
|
|
if (error)
|
|
return error;
|
|
/*
|
|
* Do not take mount writer counts on
|
|
* special files since no writes to
|
|
* the mount itself will occur.
|
|
*/
|
|
if (!special_file(inode->i_mode)) {
|
|
/*
|
|
* Balanced in __fput()
|
|
*/
|
|
error = mnt_want_write(mnt);
|
|
if (error)
|
|
put_write_access(inode);
|
|
}
|
|
return error;
|
|
}
|
|
|
|
static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
|
|
struct file *f,
|
|
int (*open)(struct inode *, struct file *),
|
|
const struct cred *cred)
|
|
{
|
|
static const struct file_operations empty_fops = {};
|
|
struct inode *inode;
|
|
int error;
|
|
|
|
f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
|
|
FMODE_PREAD | FMODE_PWRITE;
|
|
|
|
if (unlikely(f->f_flags & O_PATH))
|
|
f->f_mode = FMODE_PATH;
|
|
|
|
inode = dentry->d_inode;
|
|
if (f->f_mode & FMODE_WRITE) {
|
|
error = __get_file_write_access(inode, mnt);
|
|
if (error)
|
|
goto cleanup_file;
|
|
if (!special_file(inode->i_mode))
|
|
file_take_write(f);
|
|
}
|
|
|
|
f->f_mapping = inode->i_mapping;
|
|
f->f_path.dentry = dentry;
|
|
f->f_path.mnt = mnt;
|
|
f->f_pos = 0;
|
|
file_sb_list_add(f, inode->i_sb);
|
|
|
|
if (unlikely(f->f_mode & FMODE_PATH)) {
|
|
f->f_op = &empty_fops;
|
|
return f;
|
|
}
|
|
|
|
f->f_op = fops_get(inode->i_fop);
|
|
|
|
error = security_dentry_open(f, cred);
|
|
if (error)
|
|
goto cleanup_all;
|
|
|
|
error = break_lease(inode, f->f_flags);
|
|
if (error)
|
|
goto cleanup_all;
|
|
|
|
if (!open && f->f_op)
|
|
open = f->f_op->open;
|
|
if (open) {
|
|
error = open(inode, f);
|
|
if (error)
|
|
goto cleanup_all;
|
|
}
|
|
if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
|
|
i_readcount_inc(inode);
|
|
|
|
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) &&
|
|
(!f->f_mapping->a_ops->get_xip_mem))) {
|
|
fput(f);
|
|
f = ERR_PTR(-EINVAL);
|
|
}
|
|
}
|
|
|
|
return f;
|
|
|
|
cleanup_all:
|
|
fops_put(f->f_op);
|
|
if (f->f_mode & FMODE_WRITE) {
|
|
put_write_access(inode);
|
|
if (!special_file(inode->i_mode)) {
|
|
/*
|
|
* We don't consider this a real
|
|
* mnt_want/drop_write() pair
|
|
* because it all happenend right
|
|
* here, so just reset the state.
|
|
*/
|
|
file_reset_write(f);
|
|
mnt_drop_write(mnt);
|
|
}
|
|
}
|
|
file_sb_list_del(f);
|
|
f->f_path.dentry = NULL;
|
|
f->f_path.mnt = NULL;
|
|
cleanup_file:
|
|
put_filp(f);
|
|
dput(dentry);
|
|
mntput(mnt);
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
/**
|
|
* lookup_instantiate_filp - instantiates the open intent filp
|
|
* @nd: pointer to nameidata
|
|
* @dentry: pointer to dentry
|
|
* @open: open callback
|
|
*
|
|
* Helper for filesystems that want to use lookup open intents and pass back
|
|
* a fully instantiated struct file to the caller.
|
|
* This function is meant to be called from within a filesystem's
|
|
* lookup method.
|
|
* Beware of calling it for non-regular files! Those ->open methods might block
|
|
* (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
|
|
* leading to a deadlock, as nobody can open that fifo anymore, because
|
|
* another process to open fifo will block on locked parent when doing lookup).
|
|
* Note that in case of error, nd->intent.open.file is destroyed, but the
|
|
* path information remains valid.
|
|
* If the open callback is set to NULL, then the standard f_op->open()
|
|
* filesystem callback is substituted.
|
|
*/
|
|
struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
|
|
int (*open)(struct inode *, struct file *))
|
|
{
|
|
const struct cred *cred = current_cred();
|
|
|
|
if (IS_ERR(nd->intent.open.file))
|
|
goto out;
|
|
if (IS_ERR(dentry))
|
|
goto out_err;
|
|
nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
|
|
nd->intent.open.file,
|
|
open, cred);
|
|
out:
|
|
return nd->intent.open.file;
|
|
out_err:
|
|
release_open_intent(nd);
|
|
nd->intent.open.file = ERR_CAST(dentry);
|
|
goto out;
|
|
}
|
|
EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
|
|
|
|
/**
|
|
* nameidata_to_filp - convert a nameidata to an open filp.
|
|
* @nd: pointer to nameidata
|
|
* @flags: open flags
|
|
*
|
|
* Note that this function destroys the original nameidata
|
|
*/
|
|
struct file *nameidata_to_filp(struct nameidata *nd)
|
|
{
|
|
const struct cred *cred = current_cred();
|
|
struct file *filp;
|
|
|
|
/* Pick up the filp from the open intent */
|
|
filp = nd->intent.open.file;
|
|
nd->intent.open.file = NULL;
|
|
|
|
/* Has the filesystem initialised the file for us? */
|
|
if (filp->f_path.dentry == NULL) {
|
|
path_get(&nd->path);
|
|
filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp,
|
|
NULL, cred);
|
|
}
|
|
return filp;
|
|
}
|
|
|
|
/*
|
|
* dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
|
|
* error.
|
|
*/
|
|
struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, 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(!mnt);
|
|
|
|
error = -ENFILE;
|
|
f = get_empty_filp();
|
|
if (f == NULL) {
|
|
dput(dentry);
|
|
mntput(mnt);
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
f->f_flags = flags;
|
|
return __dentry_open(dentry, mnt, f, NULL, cred);
|
|
}
|
|
EXPORT_SYMBOL(dentry_open);
|
|
|
|
static void __put_unused_fd(struct files_struct *files, unsigned int fd)
|
|
{
|
|
struct fdtable *fdt = files_fdtable(files);
|
|
__FD_CLR(fd, fdt->open_fds);
|
|
if (fd < files->next_fd)
|
|
files->next_fd = fd;
|
|
}
|
|
|
|
void put_unused_fd(unsigned int fd)
|
|
{
|
|
struct files_struct *files = current->files;
|
|
spin_lock(&files->file_lock);
|
|
__put_unused_fd(files, fd);
|
|
spin_unlock(&files->file_lock);
|
|
}
|
|
|
|
EXPORT_SYMBOL(put_unused_fd);
|
|
|
|
/*
|
|
* Install a file pointer in the fd array.
|
|
*
|
|
* The VFS is full of places where we drop the files lock between
|
|
* setting the open_fds bitmap and installing the file in the file
|
|
* array. At any such point, we are vulnerable to a dup2() race
|
|
* installing a file in the array before us. We need to detect this and
|
|
* fput() the struct file we are about to overwrite in this case.
|
|
*
|
|
* It should never happen - if we allow dup2() do it, _really_ bad things
|
|
* will follow.
|
|
*/
|
|
|
|
void fd_install(unsigned int fd, struct file *file)
|
|
{
|
|
struct files_struct *files = current->files;
|
|
struct fdtable *fdt;
|
|
spin_lock(&files->file_lock);
|
|
fdt = files_fdtable(files);
|
|
BUG_ON(fdt->fd[fd] != NULL);
|
|
rcu_assign_pointer(fdt->fd[fd], file);
|
|
spin_unlock(&files->file_lock);
|
|
}
|
|
|
|
EXPORT_SYMBOL(fd_install);
|
|
|
|
static inline int build_open_flags(int flags, int mode, struct open_flags *op)
|
|
{
|
|
int lookup_flags = 0;
|
|
int acc_mode;
|
|
|
|
if (!(flags & O_CREAT))
|
|
mode = 0;
|
|
op->mode = mode;
|
|
|
|
/* Must never be set by userspace */
|
|
flags &= ~FMODE_NONOTIFY;
|
|
|
|
/*
|
|
* 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 we have O_PATH in the open flag. Then we
|
|
* cannot have anything other than the below set of flags
|
|
*/
|
|
if (flags & O_PATH) {
|
|
flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
|
|
acc_mode = 0;
|
|
} else {
|
|
acc_mode = MAY_OPEN | ACC_MODE(flags);
|
|
}
|
|
|
|
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;
|
|
return lookup_flags;
|
|
}
|
|
|
|
/**
|
|
* 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, int mode)
|
|
{
|
|
struct open_flags op;
|
|
int lookup = build_open_flags(flags, mode, &op);
|
|
return do_filp_open(AT_FDCWD, filename, &op, lookup);
|
|
}
|
|
EXPORT_SYMBOL(filp_open);
|
|
|
|
struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
|
|
const char *filename, int flags)
|
|
{
|
|
struct open_flags op;
|
|
int lookup = build_open_flags(flags, 0, &op);
|
|
if (flags & O_CREAT)
|
|
return ERR_PTR(-EINVAL);
|
|
if (!filename && (flags & O_DIRECTORY))
|
|
if (!dentry->d_inode->i_op->lookup)
|
|
return ERR_PTR(-ENOTDIR);
|
|
return do_file_open_root(dentry, mnt, filename, &op, lookup);
|
|
}
|
|
EXPORT_SYMBOL(file_open_root);
|
|
|
|
long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
|
|
{
|
|
struct open_flags op;
|
|
int lookup = build_open_flags(flags, mode, &op);
|
|
char *tmp = getname(filename);
|
|
int fd = PTR_ERR(tmp);
|
|
|
|
if (!IS_ERR(tmp)) {
|
|
fd = get_unused_fd_flags(flags);
|
|
if (fd >= 0) {
|
|
struct file *f = do_filp_open(dfd, tmp, &op, lookup);
|
|
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, int, mode)
|
|
{
|
|
long ret;
|
|
|
|
if (force_o_largefile())
|
|
flags |= O_LARGEFILE;
|
|
|
|
ret = do_sys_open(AT_FDCWD, filename, flags, mode);
|
|
/* avoid REGPARM breakage on x86: */
|
|
asmlinkage_protect(3, ret, filename, flags, mode);
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
|
|
int, mode)
|
|
{
|
|
long ret;
|
|
|
|
if (force_o_largefile())
|
|
flags |= O_LARGEFILE;
|
|
|
|
ret = do_sys_open(dfd, filename, flags, mode);
|
|
/* avoid REGPARM breakage on x86: */
|
|
asmlinkage_protect(4, ret, dfd, filename, flags, mode);
|
|
return ret;
|
|
}
|
|
|
|
#ifndef __alpha__
|
|
|
|
/*
|
|
* For backward compatibility? Maybe this should be moved
|
|
* into arch/i386 instead?
|
|
*/
|
|
SYSCALL_DEFINE2(creat, const char __user *, pathname, int, mode)
|
|
{
|
|
return sys_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 && 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)
|
|
{
|
|
struct file * filp;
|
|
struct files_struct *files = current->files;
|
|
struct fdtable *fdt;
|
|
int retval;
|
|
|
|
spin_lock(&files->file_lock);
|
|
fdt = files_fdtable(files);
|
|
if (fd >= fdt->max_fds)
|
|
goto out_unlock;
|
|
filp = fdt->fd[fd];
|
|
if (!filp)
|
|
goto out_unlock;
|
|
rcu_assign_pointer(fdt->fd[fd], NULL);
|
|
FD_CLR(fd, fdt->close_on_exec);
|
|
__put_unused_fd(files, fd);
|
|
spin_unlock(&files->file_lock);
|
|
retval = filp_close(filp, files);
|
|
|
|
/* 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;
|
|
|
|
out_unlock:
|
|
spin_unlock(&files->file_lock);
|
|
return -EBADF;
|
|
}
|
|
EXPORT_SYMBOL(sys_close);
|
|
|
|
/*
|
|
* 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);
|