smb3: warn on confusing error scenario with sec=krb5

commit 0a018944eee913962bce8ffebbb121960d5125d9 upstream.

When mounting with Kerberos, users have been confused about the
default error returned in scenarios in which either keyutils is
not installed or the user did not properly acquire a krb5 ticket.
Log a warning message in the case that "ENOKEY" is returned
from the get_spnego_key upcall so that users can better understand
why mount failed in those two cases.

CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 0a23b6002ff1228be197159a1b00c7145183c913..cf1a3d2f6ad8bb3d80c65b7055846cf5af7f6ddb 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -776,6 +776,8 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
        spnego_key = cifs_get_spnego_key(ses);
        if (IS_ERR(spnego_key)) {
                rc = PTR_ERR(spnego_key);
+               if (rc == -ENOKEY)
+                       cifs_dbg(VFS, "Verify user has a krb5 ticket and keyutils is installed\n");
                spnego_key = NULL;
                goto out;
        }