A client that wants to execute a file must be able to read it. Read
opens over nfs are therefore implicitly allowed for executable files
even when those files are not readable.
NFSv2/v3 get this right by using a passed-in NFSD_MAY_OWNER_OVERRIDE on
read requests, but NFSv4 has gotten this wrong ever since
dc730e1737 "nfsd4: fix owner-override on
open", when we realized that the file owner shouldn't override
permissions on non-reclaim NFSv4 opens.
So we can't use NFSD_MAY_OWNER_OVERRIDE to tell nfsd_permission to allow
reads of executable files.
So, do the same thing we do whenever we encounter another weird NFS
permission nit: define yet another NFSD_MAY_* flag.
The industry's future standardization on 128-bit processors will be
motivated primarily by the need for integers with enough bits for all
the NFSD_MAY_* flags.
Reported-by: Leonardo Borda <leonardoborda@gmail.com>
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
a043226bc1