SMB3 POSIX and deleting files with FILE_ATTRIBUTE_READONLY

[Jeremy Allison]

On Wed, Apr 09, 2025 at 08:18:22PM +0200, Ralph Boehme wrote:
>Hi folks,
>
>what should be the behavior with SMB3 POSIX when a POSIX client tries 
>to delete a file that has FILE_ATTRIBUTE_READONLY set?
>
>The major question that we must answer is, if this we would want to 
>allow for POSIX clients to ignore this in some way: either completely 
>ignore it on POSIX handles or first check if the handle has requested 
>and been granted WRITE_ATTRIBUTES access.
>
>Checking WRITE_ATTRIBUTES first means we would correctly honor 
>permissions and the client could have removed FILE_ATTRIBUTE_READONLY 
>anyway to then remove the file.
>
>Windows has some new bits FILE_DISPOSITION_IGNORE_READONLY_ATTRIBUTE 
>to handle this locally (!) and it seems to be doing it without 
>checking WRITE_ATTRIBUTES on the server.
>
><https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/2e860264-018a-47b3-8555-565a13b35a45>
>
>Thoughts?

Does Windows ever send FILE_DISPOSITION_IGNORE_READONLY_ATTRIBUTE over
the wire ? What happens if smbclient does ?