un-deprecate "acl check permissions"

Jeremy Allison jra at samba.org
Fri May 20 22:03:07 UTC 2016

On Fri, May 20, 2016 at 05:00:49PM +0300, Uri Simchoni wrote:
> Hi,
> I think I have a valid use for the deprecated "acl check permissions"
> parameter, and would like feedback - if it makes sense maybe we can
> "undeprecate" it.
> The use case is a non-POSIX file system implemented by FUSE. The file
> system has its own peculiar authorization checks. Usually, Samba would
> just try the operation and report failure if it fails, without assuming
> anything. The problem is with file deletion, where samba has to guess
> the outcome of deletion attempt.
> To solve that, I can have a VFS module that overrides create_file_fn,
> and if the access mask includes DELETE, fail the call according to the
> FUSE file system's rules (a simple implementation can be to call
> access(dirname, W_OK) on the file's parent dir, and let the FUSE
> implementation of access() decide - that's mostly correct even for POSIX
> file systems, except for the sticky bit).
> However, while such a scheme would block undesired deletions, valid
> deletions can be blocked by the default file open checks, which, I
> believe, are bypassed by setting "acl check permissions".
> Comments?

Can't you also fix this by overriding get_acl_fn() to set the
DELETE bit as appropriate ?

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