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