On Thu, Sep 29, 2022 at 12:04:47PM +0200, Mickaël Salaün wrote: > A kernel daemon should not rely on the current thread, which is unknown > and might be malicious. Before this security fix, > ksmbd_override_fsids() didn't correctly override FS UID/GID which means > that arbitrary user space threads could trick the kernel to impersonate > arbitrary users or groups for file system access checks, leading to > file system access bypass. > > This was found while investigating truncate support for Landlock: > https://lore.kernel.org/r/CAKYAXd8fpMJ7guizOjHgxEyyjoUwPsx3jLOPZP=wPYcbhkVXqA@xxxxxxxxxxxxxx > > Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") > Cc: Hyunchul Lee <hyc.lee@xxxxxxxxx> > Cc: Namjae Jeon <linkinjeon@xxxxxxxxxx> > Cc: Steve French <smfrench@xxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx> > Link: https://lore.kernel.org/r/20220929100447.108468-1-mic@xxxxxxxxxxx > --- I think this is ok. The alternative would probably be to somehow use a relevant userns when struct ksmbd_user is created when the session is established. But these are deeper ksmbd design questions. The fix proposed here itself seems good.
