On Saturday 05 October 2024 20:44:53 Pali Rohár wrote: > On Saturday 05 October 2024 13:32:12 Steve French wrote: > > The obvious question to check is whether this would lead to any issues > > if desired_access is not passed in in oparms in any cases (ie if it > > ends up 0), > > This is good point. IIRC if zero value is in OPEN/CREATE desired_access > request then SMB server returns STATUS_ACCESS_DENIED. > > So it needs to be checked that desired_access is filled in all usage > correctly. I have done checks and seems that all callers put some non-zero desired access to smb2_open_file() call. So I think this should not be an issue. > > and also that this would not hurt any cases where we want > > to keep the handle cached (deferred close) but don't have sufficient > > permission for it to be usable by the subsequent operation (e.g. > > revalidate or stat) > > I see, so the code needs to be properly checked or tested that all these > conditions are handled. It looks like that when rdwr_for_fscache is used then proper read/write desired access is asked. During testing I have not spotted issues. Also to note, I checked SMB1 code and it already does not automatically add FILE_READ_ATTRIBUTES to desired access during open. Could you schedule this change for some testing? > > On Sat, Oct 5, 2024 at 11:10 AM Pali Rohár <pali@xxxxxxxxxx> wrote: > > > > > > Linux SMB client currently is not able to access files for which do not > > > have FILE_READ_ATTRIBUTES permission. > > > > > > For example it is not able to write data into file on SMB server to > > > which has only write access (no read or read attributes access). And > > > applications are not able to get result of stat() syscall on such file. > > > > > > Test case against Windows SMB server: > > > > > > 1) On SMB server prepare file with only GENERIC_WRITE access for Everyone: > > > ACL:S-1-1-0:ALLOWED/0x0/0x40000000 > > > > > > 2) On SMB server remove all access for file's parent directory > > > > > > 3) Mount share by Linux SMB client and try to append data to that file: > > > echo test >> /mnt/share/dir/file > > > > > > 4) Try to call: stat /mnt/share/dir/file > > > > > > Without this change the write test fails because Linux SMB client is trying > > > to open SMB path "\dir\file" with GENERIC_WRITE|FILE_READ_ATTRIBUTES. With > > > this change the test pass as Linux SMB client is not opening file with > > > FILE_READ_ATTRIBUTES access anymore. > > > > > > Similarly without this change the stat test always fails as Linux SMB > > > client is trying to read attributes via SMB2_OP_QUERY_INFO. With this > > > change, if SMB2_OP_QUERY_INFO fails then Linux SMB client fallbacks for > > > reading stat attributes via OPEN with MAXIMUM_ALLOWED access (which will > > > pass if there is some permission) and OPEN reply will contain attributes > > > required for stat(). > > > > > > Pali Rohár (2): > > > cifs: Do not issue SMB2 CREATE always with FILE_READ_ATTRIBUTES > > > cifs: Improve stat() to work also without FILE_READ_ATTRIBUTES > > > > > > fs/smb/client/cifspdu.h | 1 + > > > fs/smb/client/smb2file.c | 1 - > > > fs/smb/client/smb2glob.h | 1 + > > > fs/smb/client/smb2inode.c | 71 ++++++++++++++++++++++++++++++++++++++- > > > 4 files changed, 72 insertions(+), 2 deletions(-) > > > > > > -- > > > 2.20.1 > > > > > > > > > > > > -- > > Thanks, > > > > Steve
