[PATCH 6.6 01/88] NFSD: Fix permission check for read access to executable-only files

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Scott Mayhew <smayhew@redhat.com>

commit e901c7fce59e72d9f3c92733c379849c4034ac50 upstream.

Commit abc02e5602f7 ("NFSD: Support write delegations in LAYOUTGET")
added NFSD_MAY_OWNER_OVERRIDE to the access flags passed from
nfsd4_layoutget() to fh_verify().  This causes LAYOUTGET to fail for
executable-only files, and causes xfstests generic/126 to fail on
pNFS SCSI.

To allow read access to executable-only files, what we really want is:
1. The "permissions" portion of the access flags (the lower 6 bits)
   must be exactly NFSD_MAY_READ
2. The "hints" portion of the access flags (the upper 26 bits) can
   contain any combination of NFSD_MAY_OWNER_OVERRIDE and
   NFSD_MAY_READ_IF_EXEC

Fixes: abc02e5602f7 ("NFSD: Support write delegations in LAYOUTGET")
Cc: stable@vger.kernel.org # v6.6+
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/nfsd/vfs.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -2474,8 +2474,8 @@ nfsd_permission(struct svc_rqst *rqstp,
 
 	/* Allow read access to binaries even when mode 111 */
 	if (err == -EACCES && S_ISREG(inode->i_mode) &&
-	     (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
-	      acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
+	     (((acc & NFSD_MAY_MASK) == NFSD_MAY_READ) &&
+	      (acc & (NFSD_MAY_OWNER_OVERRIDE | NFSD_MAY_READ_IF_EXEC))))
 		err = inode_permission(&nop_mnt_idmap, inode, MAY_EXEC);
 
 	return err? nfserrno(err) : 0;