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1419 lines
34 KiB
1419 lines
34 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
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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> |
|
#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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|
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#include "internal.h" |
|
|
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int do_truncate(struct user_namespace *mnt_userns, struct dentry *dentry, |
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loff_t length, unsigned int time_attrs, struct file *filp) |
|
{ |
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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(mnt_userns, 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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{ |
|
struct user_namespace *mnt_userns; |
|
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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mnt_userns = mnt_user_ns(path->mnt); |
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error = inode_permission(mnt_userns, 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(mnt_userns, path->dentry, length, 0, NULL); |
|
|
|
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; |
|
|
|
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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return error; |
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} |
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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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|
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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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|
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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; |
|
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)) |
|
goto out_putf; |
|
|
|
error = -EINVAL; |
|
/* Cannot ftruncate over 2^31 bytes without large file support */ |
|
if (small && length > MAX_NON_LFS) |
|
goto out_putf; |
|
|
|
error = -EPERM; |
|
/* Check IS_APPEND on real upper inode */ |
|
if (IS_APPEND(file_inode(f.file))) |
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goto out_putf; |
|
sb_start_write(inode->i_sb); |
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error = locks_verify_truncate(inode, f.file, length); |
|
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(file_mnt_user_ns(f.file), dentry, length, |
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ATTR_MTIME | ATTR_CTIME, f.file); |
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sb_end_write(inode->i_sb); |
|
out_putf: |
|
fdput(f); |
|
out: |
|
return error; |
|
} |
|
|
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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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#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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|
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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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|
|
|
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int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len) |
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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; |
|
|
|
/* 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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|
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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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|
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if (!(file->f_mode & FMODE_WRITE)) |
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return -EBADF; |
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|
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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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|
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if (IS_IMMUTABLE(inode)) |
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return -EPERM; |
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|
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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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/* |
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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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|
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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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|
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file_start_write(file); |
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ret = file->f_op->fallocate(file, mode, offset, len); |
|
|
|
/* |
|
* Create inotify and fanotify events. |
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* |
|
* To keep the logic simple always create events if fallocate succeeds. |
|
* This implies that events are even created if the file size remains |
|
* 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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|
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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; |
|
|
|
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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} |
|
return error; |
|
} |
|
|
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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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* 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. |
|
*/ |
|
static const struct cred *access_override_creds(void) |
|
{ |
|
const struct cred *old_cred; |
|
struct cred *override_cred; |
|
|
|
override_cred = prepare_creds(); |
|
if (!override_cred) |
|
return NULL; |
|
|
|
override_cred->fsuid = override_cred->uid; |
|
override_cred->fsgid = override_cred->gid; |
|
|
|
if (!issecure(SECURE_NO_SETUID_FIXUP)) { |
|
/* Clear the capabilities if we switch to a non-root user */ |
|
kuid_t root_uid = make_kuid(override_cred->user_ns, 0); |
|
if (!uid_eq(override_cred->uid, root_uid)) |
|
cap_clear(override_cred->cap_effective); |
|
else |
|
override_cred->cap_effective = |
|
override_cred->cap_permitted; |
|
} |
|
|
|
/* |
|
* The new set of credentials can *only* be used in |
|
* task-synchronous circumstances, and does not need |
|
* RCU freeing, unless somebody then takes a separate |
|
* reference to it. |
|
* |
|
* NOTE! This is _only_ true because this credential |
|
* is used purely for override_creds() that installs |
|
* it as the subjective cred. Other threads will be |
|
* accessing ->real_cred, not the subjective cred. |
|
* |
|
* If somebody _does_ make a copy of this (using the |
|
* 'get_current_cred()' function), that will clear the |
|
* non_rcu field, because now that other user may be |
|
* expecting RCU freeing. But normal thread-synchronous |
|
* cred accesses will keep things non-RCY. |
|
*/ |
|
override_cred->non_rcu = 1; |
|
|
|
old_cred = override_creds(override_cred); |
|
|
|
/* override_cred() gets its own ref */ |
|
put_cred(override_cred); |
|
|
|
return old_cred; |
|
} |
|
|
|
static long do_faccessat(int dfd, const char __user *filename, int mode, int flags) |
|
{ |
|
struct path path; |
|
struct inode *inode; |
|
int res; |
|
unsigned int lookup_flags = LOOKUP_FOLLOW; |
|
const struct cred *old_cred = NULL; |
|
|
|
if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ |
|
return -EINVAL; |
|
|
|
if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) |
|
return -EINVAL; |
|
|
|
if (flags & AT_SYMLINK_NOFOLLOW) |
|
lookup_flags &= ~LOOKUP_FOLLOW; |
|
if (flags & AT_EMPTY_PATH) |
|
lookup_flags |= LOOKUP_EMPTY; |
|
|
|
if (!(flags & AT_EACCESS)) { |
|
old_cred = access_override_creds(); |
|
if (!old_cred) |
|
return -ENOMEM; |
|
} |
|
|
|
retry: |
|
res = user_path_at(dfd, filename, lookup_flags, &path); |
|
if (res) |
|
goto out; |
|
|
|
inode = d_backing_inode(path.dentry); |
|
|
|
if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) { |
|
/* |
|
* MAY_EXEC on regular files is denied if the fs is mounted |
|
* with the "noexec" flag. |
|
*/ |
|
res = -EACCES; |
|
if (path_noexec(&path)) |
|
goto out_path_release; |
|
} |
|
|
|
res = inode_permission(mnt_user_ns(path.mnt), inode, mode | MAY_ACCESS); |
|
/* SuS v2 requires we report a read only fs too */ |
|
if (res || !(mode & S_IWOTH) || special_file(inode->i_mode)) |
|
goto out_path_release; |
|
/* |
|
* This is a rare case where using __mnt_is_readonly() |
|
* is OK without a mnt_want/drop_write() pair. Since |
|
* no actual write to the fs is performed here, we do |
|
* not need to telegraph to that to anyone. |
|
* |
|
* By doing this, we accept that this access is |
|
* inherently racy and know that the fs may change |
|
* state before we even see this result. |
|
*/ |
|
if (__mnt_is_readonly(path.mnt)) |
|
res = -EROFS; |
|
|
|
out_path_release: |
|
path_put(&path); |
|
if (retry_estale(res, lookup_flags)) { |
|
lookup_flags |= LOOKUP_REVAL; |
|
goto retry; |
|
} |
|
out: |
|
if (old_cred) |
|
revert_creds(old_cred); |
|
|
|
return res; |
|
} |
|
|
|
SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode) |
|
{ |
|
return do_faccessat(dfd, filename, mode, 0); |
|
} |
|
|
|
SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode, |
|
int, flags) |
|
{ |
|
return do_faccessat(dfd, filename, mode, flags); |
|
} |
|
|
|
SYSCALL_DEFINE2(access, const char __user *, filename, int, mode) |
|
{ |
|
return do_faccessat(AT_FDCWD, filename, mode, 0); |
|
} |
|
|
|
SYSCALL_DEFINE1(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 = path_permission(&path, 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(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 = file_permission(f.file, MAY_EXEC | MAY_CHDIR); |
|
if (!error) |
|
set_fs_pwd(current->fs, &f.file->f_path); |
|
out_putf: |
|
fdput(f); |
|
out: |
|
return error; |
|
} |
|
|
|
SYSCALL_DEFINE1(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 = path_permission(&path, 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; |
|
} |
|
|
|
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(mnt_user_ns(path->mnt), 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 vfs_fchmod(struct file *file, umode_t mode) |
|
{ |
|
audit_file(file); |
|
return chmod_common(&file->f_path, mode); |
|
} |
|
|
|
SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode) |
|
{ |
|
struct fd f = fdget(fd); |
|
int err = -EBADF; |
|
|
|
if (f.file) { |
|
err = vfs_fchmod(f.file, mode); |
|
fdput(f); |
|
} |
|
return err; |
|
} |
|
|
|
static 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); |
|
} |
|
|
|
int chown_common(const struct path *path, uid_t user, gid_t group) |
|
{ |
|
struct user_namespace *mnt_userns; |
|
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); |
|
|
|
mnt_userns = mnt_user_ns(path->mnt); |
|
uid = kuid_from_mnt(mnt_userns, uid); |
|
gid = kgid_from_mnt(mnt_userns, gid); |
|
|
|
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(mnt_userns, 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 vfs_fchown(struct file *file, uid_t user, gid_t group) |
|
{ |
|
int error; |
|
|
|
error = mnt_want_write_file(file); |
|
if (error) |
|
return error; |
|
audit_file(file); |
|
error = chown_common(&file->f_path, user, group); |
|
mnt_drop_write_file(file); |
|
return error; |
|
} |
|
|
|
int ksys_fchown(unsigned int fd, uid_t user, gid_t group) |
|
{ |
|
struct fd f = fdget(fd); |
|
int error = -EBADF; |
|
|
|
if (f.file) { |
|
error = vfs_fchown(f.file, user, group); |
|
fdput(f); |
|
} |
|
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; |
|
f->f_wb_err = filemap_sample_wb_err(f->f_mapping); |
|
f->f_sb_err = file_sample_sb_err(f); |
|
|
|
if (unlikely(f->f_flags & O_PATH)) { |
|
f->f_mode = FMODE_PATH | FMODE_OPENED; |
|
f->f_op = &empty_fops; |
|
return 0; |
|
} |
|
|
|
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) { |
|
/* |
|
* Paired with smp_mb() in collapse_file() to ensure nr_thps |
|
* is up to date and the update to i_writecount by |
|
* get_write_access() is visible. Ensures subsequent insertion |
|
* of THPs into the page cache will fail. |
|
*/ |
|
smp_mb(); |
|
if (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(). |
|
* |
|
* 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); |
|
|
|
#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE)) |
|
#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC) |
|
|
|
inline struct open_how build_open_how(int flags, umode_t mode) |
|
{ |
|
struct open_how how = { |
|
.flags = flags & VALID_OPEN_FLAGS, |
|
.mode = mode & S_IALLUGO, |
|
}; |
|
|
|
/* O_PATH beats everything else. */ |
|
if (how.flags & O_PATH) |
|
how.flags &= O_PATH_FLAGS; |
|
/* Modes should only be set for create-like flags. */ |
|
if (!WILL_CREATE(how.flags)) |
|
how.mode = 0; |
|
return how; |
|
} |
|
|
|
inline int build_open_flags(const struct open_how *how, struct open_flags *op) |
|
{ |
|
u64 flags = how->flags; |
|
u64 strip = FMODE_NONOTIFY | O_CLOEXEC; |
|
int lookup_flags = 0; |
|
int acc_mode = ACC_MODE(flags); |
|
|
|
BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS), |
|
"struct open_flags doesn't yet handle flags > 32 bits"); |
|
|
|
/* |
|
* Strip flags that either shouldn't be set by userspace like |
|
* FMODE_NONOTIFY or that aren't relevant in determining struct |
|
* open_flags like O_CLOEXEC. |
|
*/ |
|
flags &= ~strip; |
|
|
|
/* |
|
* Older syscalls implicitly clear all of the invalid flags or argument |
|
* values before calling build_open_flags(), but openat2(2) checks all |
|
* of its arguments. |
|
*/ |
|
if (flags & ~VALID_OPEN_FLAGS) |
|
return -EINVAL; |
|
if (how->resolve & ~VALID_RESOLVE_FLAGS) |
|
return -EINVAL; |
|
|
|
/* Scoping flags are mutually exclusive. */ |
|
if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT)) |
|
return -EINVAL; |
|
|
|
/* Deal with the mode. */ |
|
if (WILL_CREATE(flags)) { |
|
if (how->mode & ~S_IALLUGO) |
|
return -EINVAL; |
|
op->mode = how->mode | S_IFREG; |
|
} else { |
|
if (how->mode != 0) |
|
return -EINVAL; |
|
op->mode = 0; |
|
} |
|
|
|
/* |
|
* In order to ensure programs get explicit errors when trying to use |
|
* O_TMPFILE on old kernels, O_TMPFILE is implemented such that it |
|
* looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we |
|
* have to require userspace to explicitly set it. |
|
*/ |
|
if (flags & __O_TMPFILE) { |
|
if ((flags & O_TMPFILE_MASK) != O_TMPFILE) |
|
return -EINVAL; |
|
if (!(acc_mode & MAY_WRITE)) |
|
return -EINVAL; |
|
} |
|
if (flags & O_PATH) { |
|
/* O_PATH only permits certain other flags to be set. */ |
|
if (flags & ~O_PATH_FLAGS) |
|
return -EINVAL; |
|
acc_mode = 0; |
|
} |
|
|
|
/* |
|
* 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; |
|
|
|
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; |
|
flags |= O_NOFOLLOW; |
|
} |
|
} |
|
|
|
if (flags & O_DIRECTORY) |
|
lookup_flags |= LOOKUP_DIRECTORY; |
|
if (!(flags & O_NOFOLLOW)) |
|
lookup_flags |= LOOKUP_FOLLOW; |
|
|
|
if (how->resolve & RESOLVE_NO_XDEV) |
|
lookup_flags |= LOOKUP_NO_XDEV; |
|
if (how->resolve & RESOLVE_NO_MAGICLINKS) |
|
lookup_flags |= LOOKUP_NO_MAGICLINKS; |
|
if (how->resolve & RESOLVE_NO_SYMLINKS) |
|
lookup_flags |= LOOKUP_NO_SYMLINKS; |
|
if (how->resolve & RESOLVE_BENEATH) |
|
lookup_flags |= LOOKUP_BENEATH; |
|
if (how->resolve & RESOLVE_IN_ROOT) |
|
lookup_flags |= LOOKUP_IN_ROOT; |
|
if (how->resolve & RESOLVE_CACHED) { |
|
/* Don't bother even trying for create/truncate/tmpfile open */ |
|
if (flags & (O_TRUNC | O_CREAT | O_TMPFILE)) |
|
return -EAGAIN; |
|
lookup_flags |= LOOKUP_CACHED; |
|
} |
|
|
|
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; |
|
struct open_how how = build_open_how(flags, mode); |
|
int err = build_open_flags(&how, &op); |
|
if (err) |
|
return ERR_PTR(err); |
|
return 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(const struct path *root, |
|
const char *filename, int flags, umode_t mode) |
|
{ |
|
struct open_flags op; |
|
struct open_how how = build_open_how(flags, mode); |
|
int err = build_open_flags(&how, &op); |
|
if (err) |
|
return ERR_PTR(err); |
|
return do_file_open_root(root, filename, &op); |
|
} |
|
EXPORT_SYMBOL(file_open_root); |
|
|
|
static long do_sys_openat2(int dfd, const char __user *filename, |
|
struct open_how *how) |
|
{ |
|
struct open_flags op; |
|
int fd = build_open_flags(how, &op); |
|
struct filename *tmp; |
|
|
|
if (fd) |
|
return fd; |
|
|
|
tmp = getname(filename); |
|
if (IS_ERR(tmp)) |
|
return PTR_ERR(tmp); |
|
|
|
fd = get_unused_fd_flags(how->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; |
|
} |
|
|
|
long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) |
|
{ |
|
struct open_how how = build_open_how(flags, mode); |
|
return do_sys_openat2(dfd, filename, &how); |
|
} |
|
|
|
|
|
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); |
|
} |
|
|
|
SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename, |
|
struct open_how __user *, how, size_t, usize) |
|
{ |
|
int err; |
|
struct open_how tmp; |
|
|
|
BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0); |
|
BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST); |
|
|
|
if (unlikely(usize < OPEN_HOW_SIZE_VER0)) |
|
return -EINVAL; |
|
|
|
err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize); |
|
if (err) |
|
return err; |
|
|
|
/* O_LARGEFILE is only allowed for non-O_PATH. */ |
|
if (!(tmp.flags & O_PATH) && force_o_largefile()) |
|
tmp.flags |= O_LARGEFILE; |
|
|
|
return do_sys_openat2(dfd, filename, &tmp); |
|
} |
|
|
|
#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) |
|
{ |
|
int flags = O_CREAT | O_WRONLY | O_TRUNC; |
|
|
|
if (force_o_largefile()) |
|
flags |= O_LARGEFILE; |
|
return do_sys_open(AT_FDCWD, pathname, flags, 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(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; |
|
} |
|
|
|
/** |
|
* close_range() - Close all file descriptors in a given range. |
|
* |
|
* @fd: starting file descriptor to close |
|
* @max_fd: last file descriptor to close |
|
* @flags: reserved for future extensions |
|
* |
|
* This closes a range of file descriptors. All file descriptors |
|
* from @fd up to and including @max_fd are closed. |
|
* Currently, errors to close a given file descriptor are ignored. |
|
*/ |
|
SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd, |
|
unsigned int, flags) |
|
{ |
|
return __close_range(fd, max_fd, flags); |
|
} |
|
|
|
/* |
|
* 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);
|
|
|