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 2f4cdd290c464b47b75c8a105668cfd7817913db..492688764004803b2a4089a7822b09d982884ce5 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -1387,6 +1387,8 @@ 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;
        }