[Bug 271922] Re: Default ACL not applied on files created through CIFS filesystem (mount.cifs)

Steve Langasek steve.langasek at canonical.com
Sat Jan 24 21:30:28 GMT 2009

Disabling Unix CIFS extensions with 'echo 0 >
/proc/fs/cifs/LinuxExtensionsEnabled', the kernel cifs client now works
for me (tested with the current jaunty kernel).  Attached is a network
trace showing the same operation ('touch file-cifs') with POSIX
extensions disabled; the SET_FILE_INFO level is different ('File Basic
Info' vs. 'File Unix Basic'),

I don't see anything special in the /content/ of the file info request
when POSIX extensions are enabled, so I think this should be considered
a server bug.

As an aside, if you're only using user mounts on the client, I would
generally recommend POSIX extensions on the client independent of this
particular bug, especially given a kernel (such as the one in hardy)
that doesn't have CIFS_XATTRS turned on.

Pros of using POSIX extensions for user-only mounts:
- ability to create/use pipes and sockets
- ability to use POSIX locking reliably
- ?

Cons of using POSIX extensions for user-only mounts:
- if you ever authenticate to the server as a user whose remote uid is different from your local uid, the mount will be completely inaccessible to your user because of the pass-through ACL semantics

The current default behavior of mount.cifs is unfortunately really only
suitable for system-level mounts where the client and server have the
same uid/gid mappings.

** Attachment added: "cifs-acl-ok-without-posix-extensions.pcap"

Default ACL not applied on files created through CIFS filesystem (mount.cifs)
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