I can confirm this bug. My system configuration is: Ubuntu Linux Dapper (kernel package linux-image-2.6.15-23-386_2.6.15-23.39_i386.deb) client accessing Windows Server 2003 3790 Service Pack 1 (no UNIX extensions).
Problem description: When all write permission bits are removed from a file on the Windows share (e.g. using chmod ugo-w filename), the read-only bit is set in the file (as seen in the Windows Explorer). Now it is not possible to get the write permissions back (e.g. using chmod ugo+w filename). The read-only bit has to be removed in the Windows Explorer. When this is done, the file is still displayed to be read-only (ls -l filename), but it can be made writeable (chmod ugo+w filename). When the following patch is applied (discovered by Alan Tyson of HP, reported by Jeff Layton), the writeable bits are displayed correctly as soon as the read-only bit is removed in the Windows Explorer. The main problem, however, still exists as it is not possible to make the file writeable from the Linux CIFS client. see: http://lists.samba.org/archive/linux-cifs-client/2007-January/001668.html http://lists.samba.org/archive/linux-cifs-client/2007-March/001808.html http://lists.samba.org/archive/linux-cifs-client/2007-March/001827.html --BEGIN OF PATCH---------------------------------------------------------------- --- linux-source-2.6.15-2.6.15.orig/fs/cifs/inode.c 2006-03-02 22:18:38.000000000 +0100 +++ linux-source-2.6.15-2.6.15/fs/cifs/inode.c 2007-03-15 16:37:45.000000000 +0100 @@ -475,6 +475,12 @@ mode e.g. 555 */ if (cifsInfo->cifsAttrs & ATTR_READONLY) inode->i_mode &= ~(S_IWUGO); + else if ((inode->i_mode & S_IWUGO) == 0) + /* the ATTR_READONLY flag may have been */ + /* changed on server -- set any w bits */ + /* allowed by mnt_file_mode */ + inode->i_mode |= (S_IWUGO & + cifs_sb->mnt_file_mode); /* BB add code here - validate if device or weird share or device type? */ } --- linux-source-2.6.15-2.6.15.orig/fs/cifs/readdir.c 2006-03-02 22:18:38.000000000 +0100 +++ linux-source-2.6.15-2.6.15/fs/cifs/readdir.c 2007-03-15 16:39:05.000000000 +0100 @@ -178,6 +178,10 @@ tmp_inode->i_mode |= S_IFREG; if (attr & ATTR_READONLY) tmp_inode->i_mode &= ~(S_IWUGO); + else if ((tmp_inode->i_mode & S_IWUGO) == 0) + /* the ATTR_READONLY flag may have been changed on */ + /* server -- set any w bits allowed by mnt_file_mode */ + tmp_inode->i_mode |= (S_IWUGO & cifs_sb->mnt_file_mode); } /* could add code here - to validate if device or weird share type? */ /* can not fill in nlink here as in qpathinfo version and Unx search */ --END OF PATCH------------------------------------------------------------------ Investigating the problem further, I found out that the problem occurs only if no other attribute is set on the file. If I set the archived or hidden bit in the Windows Explorer or unmark the "for fast searching, allow Indexing Service to index this file" checkbox (which sets the ATTR_NOT_CONTENT_INDEXED bit), the read-only bit can be cleared from the Linux client. Looking into the function cifs_setattr() in fs/cifs/inode.c and adding some debug output, it can be seen that time_buf.Attributes is zero in the problem case and the attribute will not be set. Sending the attributes with a zero value does not help as this seems to mean that no attributes have to be changed. So I added the ATTR_NORMAL bit in the case where ATTR_READONLY has to be cleared and no other attribute is set. I made another small change: The ATTR_READONLY is only cleared if all writeable bits are set in the Linux permissions (the file is writeable for user, group and others). This is caused by the check ((mode & S_IWUGO) == S_IWUGO). I think that this does not make sense, as soon as any write flag is set, the file is no longer read-only. The following patch was applied after the patch above and solves the problem. --BEGIN OF PATCH---------------------------------------------------------------- --- linux-source-2.6.15-2.6.15.orig/fs/cifs/inode.c 2007-03-16 08:41:42.000000000 +0100 +++ linux-source-2.6.15-2.6.15/fs/cifs/inode.c 2007-03-16 14:26:15.000000000 +0100 @@ -1261,11 +1261,15 @@ time_buf.Attributes = cpu_to_le32(cifsInode->cifsAttrs | ATTR_READONLY); - } else if ((mode & S_IWUGO) == S_IWUGO) { - if (cifsInode->cifsAttrs & ATTR_READONLY) + } else { + if (cifsInode->cifsAttrs & ATTR_READONLY) { time_buf.Attributes = cpu_to_le32(cifsInode->cifsAttrs & (~ATTR_READONLY)); + if (!time_buf.Attributes) + time_buf.Attributes = + cpu_to_le32(ATTR_NORMAL); + } } /* BB to be implemented - via Windows security descriptors or streams */ --END OF PATCH------------------------------------------------------------------ I posted this patch on the linux-cifs-client mailing list: http://lists.samba.org/archive/linux-cifs-client/2007-March/001843.html I suggest that this bug should be fixed as it is really a show-stopper for companies accessing Windows servers from Linux clients. The bug should be assigned to the linux-source packages. Urs ** Attachment added: "CIFS: reset file mode when CIFS client notices that ATTR_READONLY is no longer set; reset ATTR_READONLY on Windows share when Linux client allows write permission" http://librarian.launchpad.net/6846651/cifs_readoly_patch.txt -- (smbfs, Dapper) multiple cifs issues https://launchpad.net/bugs/62607 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
