NFS: Use "krb5i" to establish NFSv4 state whenever possible

Currently our client uses AUTH_UNIX for state management on Kerberos
NFS mounts in some cases.  For example, if the first mount of a
server specifies "sec=sys," the SETCLIENTID operation is performed
with AUTH_UNIX.  Subsequent mounts using stronger security flavors
can not change the flavor used for lease establishment.  This might
be less security than an administrator was expecting.

Dave Noveck's migration issues draft recommends the use of an
integrity-protecting security flavor for the SETCLIENTID operation.
Let's ignore the mount's sec= setting and use krb5i as the default
security flavor for SETCLIENTID.

If our client can't establish a GSS context (eg. because it doesn't
have a keytab or the server doesn't support Kerberos) we fall back
to using AUTH_NULL.  For an operation that requires a
machine credential (which never represents a particular user)
AUTH_NULL is as secure as AUTH_UNIX.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 17b34b2da2df62fd15d7ebda761e8ade3d964af2..bb9789ef1d4987fc5db66e59de92e4a0a8961c53 100644 (file)
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -199,7 +199,7 @@ struct nfs_client *nfs4_init_client(struct nfs_client *clp,
        clp->rpc_ops = &nfs_v4_clientops;
 
        __set_bit(NFS_CS_DISCRTRY, &clp->cl_flags);
-       error = nfs_create_rpc_client(clp, timeparms, authflavour);
+       error = nfs_create_rpc_client(clp, timeparms, RPC_AUTH_GSS_KRB5I);
        if (error < 0)
                goto error;
 

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index b924bdd6949483dd510cc38cf3675259962937b2..a30f51eb048ff6aae289ac1e79bdd704d05b225d 100644 (file)
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1866,26 +1866,13 @@ int nfs4_discover_server_trunking(struct nfs_client *clp,
 {
        const struct nfs4_state_recovery_ops *ops =
                                clp->cl_mvops->reboot_recovery_ops;
-       rpc_authflavor_t *flavors, flav, save;
        struct rpc_clnt *clnt;
        struct rpc_cred *cred;
-       int i, len, status;
+       int i, status;
 
        dprintk("NFS: %s: testing '%s'\n", __func__, clp->cl_hostname);
 
-       len = NFS_MAX_SECFLAVORS;
-       flavors = kcalloc(len, sizeof(*flavors), GFP_KERNEL);
-       if (flavors == NULL) {
-               status = -ENOMEM;
-               goto out;
-       }
-       len = rpcauth_list_flavors(flavors, len);
-       if (len < 0) {
-               status = len;
-               goto out_free;
-       }
        clnt = clp->cl_rpcclient;
-       save = clnt->cl_auth->au_flavor;
        i = 0;
 
        mutex_lock(&nfs_clid_init_mutex);
@@ -1900,12 +1887,6 @@ again:
        switch (status) {
        case 0:
                break;
-
-       case -EACCES:
-               if (clp->cl_machine_cred == NULL)
-                       break;
-               /* Handle case where the user hasn't set up machine creds */
-               nfs4_clear_machine_cred(clp);
        case -NFS4ERR_DELAY:
        case -ETIMEDOUT:
        case -EAGAIN:
@@ -1914,17 +1895,12 @@ again:
                dprintk("NFS: %s after status %d, retrying\n",
                        __func__, status);
                goto again;
-
+       case -EACCES:
+               if (i++)
+                       break;
        case -NFS4ERR_CLID_INUSE:
        case -NFS4ERR_WRONGSEC:
-               status = -EPERM;
-               if (i >= len)
-                       break;
-
-               flav = flavors[i++];
-               if (flav == save)
-                       flav = flavors[i++];
-               clnt = rpc_clone_client_set_auth(clnt, flav);
+               clnt = rpc_clone_client_set_auth(clnt, RPC_AUTH_NULL);
                if (IS_ERR(clnt)) {
                        status = PTR_ERR(clnt);
                        break;
@@ -1944,9 +1920,6 @@ again:
 
 out_unlock:
        mutex_unlock(&nfs_clid_init_mutex);
-out_free:
-       kfree(flavors);
-out:
        dprintk("NFS: %s: status = %d\n", __func__, status);
        return status;
 }