linux/fs/udf/file.c
Steven J. Magnani c3367a1b47 udf: augment UDF permissions on new inodes
Windows presents files created within Linux as read-only, even when
permissions in Linux indicate the file should be writable.

UDF defines a slightly different set of basic file permissions than Linux.
Specifically, UDF has "delete" and "change attribute" permissions for each
access class (user/group/other). Linux has no equivalents for these.

When the Linux UDF driver creates a file (or directory), no UDF delete or
change attribute permissions are granted. The lack of delete permission
appears to cause Windows to mark an item read-only when its permissions
otherwise indicate that it should be read-write.

Fix this by having UDF delete permissions track Linux write permissions.
Also grant UDF change attribute permission to the owner when creating a
new inode.

Reported by: Ty Young
Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Link: https://lore.kernel.org/r/20190827121359.9954-1-steve@digidescorp.com
Signed-off-by: Jan Kara <jack@suse.cz>
2019-08-27 15:38:46 +02:00

294 lines
7.3 KiB
C

/*
* file.c
*
* PURPOSE
* File handling routines for the OSTA-UDF(tm) filesystem.
*
* COPYRIGHT
* This file is distributed under the terms of the GNU General Public
* License (GPL). Copies of the GPL can be obtained from:
* ftp://prep.ai.mit.edu/pub/gnu/GPL
* Each contributing author retains all rights to their own work.
*
* (C) 1998-1999 Dave Boynton
* (C) 1998-2004 Ben Fennema
* (C) 1999-2000 Stelias Computing Inc
*
* HISTORY
*
* 10/02/98 dgb Attempt to integrate into udf.o
* 10/07/98 Switched to using generic_readpage, etc., like isofs
* And it works!
* 12/06/98 blf Added udf_file_read. uses generic_file_read for all cases but
* ICBTAG_FLAG_AD_IN_ICB.
* 04/06/99 64 bit file handling on 32 bit systems taken from ext2 file.c
* 05/12/99 Preliminary file write support
*/
#include "udfdecl.h"
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/string.h> /* memset */
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/pagemap.h>
#include <linux/uio.h>
#include "udf_i.h"
#include "udf_sb.h"
static void __udf_adinicb_readpage(struct page *page)
{
struct inode *inode = page->mapping->host;
char *kaddr;
struct udf_inode_info *iinfo = UDF_I(inode);
loff_t isize = i_size_read(inode);
/*
* We have to be careful here as truncate can change i_size under us.
* So just sample it once and use the same value everywhere.
*/
kaddr = kmap_atomic(page);
memcpy(kaddr, iinfo->i_ext.i_data + iinfo->i_lenEAttr, isize);
memset(kaddr + isize, 0, PAGE_SIZE - isize);
flush_dcache_page(page);
SetPageUptodate(page);
kunmap_atomic(kaddr);
}
static int udf_adinicb_readpage(struct file *file, struct page *page)
{
BUG_ON(!PageLocked(page));
__udf_adinicb_readpage(page);
unlock_page(page);
return 0;
}
static int udf_adinicb_writepage(struct page *page,
struct writeback_control *wbc)
{
struct inode *inode = page->mapping->host;
char *kaddr;
struct udf_inode_info *iinfo = UDF_I(inode);
BUG_ON(!PageLocked(page));
kaddr = kmap_atomic(page);
memcpy(iinfo->i_ext.i_data + iinfo->i_lenEAttr, kaddr,
i_size_read(inode));
SetPageUptodate(page);
kunmap_atomic(kaddr);
mark_inode_dirty(inode);
unlock_page(page);
return 0;
}
static int udf_adinicb_write_begin(struct file *file,
struct address_space *mapping, loff_t pos,
unsigned len, unsigned flags, struct page **pagep,
void **fsdata)
{
struct page *page;
if (WARN_ON_ONCE(pos >= PAGE_SIZE))
return -EIO;
page = grab_cache_page_write_begin(mapping, 0, flags);
if (!page)
return -ENOMEM;
*pagep = page;
if (!PageUptodate(page))
__udf_adinicb_readpage(page);
return 0;
}
static ssize_t udf_adinicb_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
/* Fallback to buffered I/O. */
return 0;
}
static int udf_adinicb_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
struct inode *inode = page->mapping->host;
loff_t last_pos = pos + copied;
if (last_pos > inode->i_size)
i_size_write(inode, last_pos);
set_page_dirty(page);
unlock_page(page);
put_page(page);
return copied;
}
const struct address_space_operations udf_adinicb_aops = {
.readpage = udf_adinicb_readpage,
.writepage = udf_adinicb_writepage,
.write_begin = udf_adinicb_write_begin,
.write_end = udf_adinicb_write_end,
.direct_IO = udf_adinicb_direct_IO,
};
static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
ssize_t retval;
struct file *file = iocb->ki_filp;
struct inode *inode = file_inode(file);
struct udf_inode_info *iinfo = UDF_I(inode);
int err;
inode_lock(inode);
retval = generic_write_checks(iocb, from);
if (retval <= 0)
goto out;
down_write(&iinfo->i_data_sem);
if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
loff_t end = iocb->ki_pos + iov_iter_count(from);
if (inode->i_sb->s_blocksize <
(udf_file_entry_alloc_offset(inode) + end)) {
err = udf_expand_file_adinicb(inode);
if (err) {
inode_unlock(inode);
udf_debug("udf_expand_adinicb: err=%d\n", err);
return err;
}
} else {
iinfo->i_lenAlloc = max(end, inode->i_size);
up_write(&iinfo->i_data_sem);
}
} else
up_write(&iinfo->i_data_sem);
retval = __generic_file_write_iter(iocb, from);
out:
inode_unlock(inode);
if (retval > 0) {
mark_inode_dirty(inode);
retval = generic_write_sync(iocb, retval);
}
return retval;
}
long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
long old_block, new_block;
int result;
if (inode_permission(inode, MAY_READ) != 0) {
udf_debug("no permission to access inode %lu\n", inode->i_ino);
return -EPERM;
}
if (!arg && ((cmd == UDF_GETVOLIDENT) || (cmd == UDF_GETEASIZE) ||
(cmd == UDF_RELOCATE_BLOCKS) || (cmd == UDF_GETEABLOCK))) {
udf_debug("invalid argument to udf_ioctl\n");
return -EINVAL;
}
switch (cmd) {
case UDF_GETVOLIDENT:
if (copy_to_user((char __user *)arg,
UDF_SB(inode->i_sb)->s_volume_ident, 32))
return -EFAULT;
return 0;
case UDF_RELOCATE_BLOCKS:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (get_user(old_block, (long __user *)arg))
return -EFAULT;
result = udf_relocate_blocks(inode->i_sb,
old_block, &new_block);
if (result == 0)
result = put_user(new_block, (long __user *)arg);
return result;
case UDF_GETEASIZE:
return put_user(UDF_I(inode)->i_lenEAttr, (int __user *)arg);
case UDF_GETEABLOCK:
return copy_to_user((char __user *)arg,
UDF_I(inode)->i_ext.i_data,
UDF_I(inode)->i_lenEAttr) ? -EFAULT : 0;
default:
return -ENOIOCTLCMD;
}
return 0;
}
static int udf_release_file(struct inode *inode, struct file *filp)
{
if (filp->f_mode & FMODE_WRITE &&
atomic_read(&inode->i_writecount) == 1) {
/*
* Grab i_mutex to avoid races with writes changing i_size
* while we are running.
*/
inode_lock(inode);
down_write(&UDF_I(inode)->i_data_sem);
udf_discard_prealloc(inode);
udf_truncate_tail_extent(inode);
up_write(&UDF_I(inode)->i_data_sem);
inode_unlock(inode);
}
return 0;
}
const struct file_operations udf_file_operations = {
.read_iter = generic_file_read_iter,
.unlocked_ioctl = udf_ioctl,
.open = generic_file_open,
.mmap = generic_file_mmap,
.write_iter = udf_file_write_iter,
.release = udf_release_file,
.fsync = generic_file_fsync,
.splice_read = generic_file_splice_read,
.llseek = generic_file_llseek,
};
static int udf_setattr(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = d_inode(dentry);
struct super_block *sb = inode->i_sb;
int error;
error = setattr_prepare(dentry, attr);
if (error)
return error;
if ((attr->ia_valid & ATTR_UID) &&
UDF_QUERY_FLAG(sb, UDF_FLAG_UID_SET) &&
!uid_eq(attr->ia_uid, UDF_SB(sb)->s_uid))
return -EPERM;
if ((attr->ia_valid & ATTR_GID) &&
UDF_QUERY_FLAG(sb, UDF_FLAG_GID_SET) &&
!gid_eq(attr->ia_gid, UDF_SB(sb)->s_gid))
return -EPERM;
if ((attr->ia_valid & ATTR_SIZE) &&
attr->ia_size != i_size_read(inode)) {
error = udf_setsize(inode, attr->ia_size);
if (error)
return error;
}
if (attr->ia_valid & ATTR_MODE)
udf_update_extra_perms(inode, attr->ia_mode);
setattr_copy(inode, attr);
mark_inode_dirty(inode);
return 0;
}
const struct inode_operations udf_file_inode_operations = {
.setattr = udf_setattr,
};