tipc: introduce TIPC encryption & authentication

This commit offers an option to encrypt and authenticate all messaging,
including the neighbor discovery messages. The currently most advanced
algorithm supported is the AEAD AES-GCM (like IPSec or TLS). All
encryption/decryption is done at the bearer layer, just before leaving
or after entering TIPC.

Supported features:
- Encryption & authentication of all TIPC messages (header + data);
- Two symmetric-key modes: Cluster and Per-node;
- Automatic key switching;
- Key-expired revoking (sequence number wrapped);
- Lock-free encryption/decryption (RCU);
- Asynchronous crypto, Intel AES-NI supported;
- Multiple cipher transforms;
- Logs & statistics;

Two key modes:
- Cluster key mode: One single key is used for both TX & RX in all
nodes in the cluster.
- Per-node key mode: Each nodes in the cluster has one specific TX key.
For RX, a node requires its peers' TX key to be able to decrypt the
messages from those peers.

Key setting from user-space is performed via netlink by a user program
(e.g. the iproute2 'tipc' tool).

Internal key state machine:

                                 Attach    Align(RX)
                                     +-+   +-+
                                     | V   | V
        +---------+      Attach     +---------+
        |  IDLE   |---------------->| PENDING |(user = 0)
        +---------+                 +---------+
           A   A                   Switch|  A
           |   |                         |  |
           |   | Free(switch/revoked)    |  |
     (Free)|   +----------------------+  |  |Timeout
           |              (TX)        |  |  |(RX)
           |                          |  |  |
           |                          |  v  |
        +---------+      Switch     +---------+
        | PASSIVE |<----------------| ACTIVE  |
        +---------+       (RX)      +---------+
        (user = 1)                  (user >= 1)

The number of TFMs is 10 by default and can be changed via the procfs
'net/tipc/max_tfms'. At this moment, as for simplicity, this file is
also used to print the crypto statistics at runtime:

echo 0xfff1 > /proc/sys/net/tipc/max_tfms

The patch defines a new TIPC version (v7) for the encryption message (-
backward compatibility as well). The message is basically encapsulated
as follows:

   +----------------------------------------------------------+
   | TIPCv7 encryption  | Original TIPCv2    | Authentication |
   | header             | packet (encrypted) | Tag            |
   +----------------------------------------------------------+

The throughput is about ~40% for small messages (compared with non-
encryption) and ~9% for large messages. With the support from hardware
crypto i.e. the Intel AES-NI CPU instructions, the throughput increases
upto ~85% for small messages and ~55% for large messages.

By default, the new feature is inactive (i.e. no encryption) until user
sets a key for TIPC. There is however also a new option - "TIPC_CRYPTO"
in the kernel configuration to enable/disable the new code when needed.

MAINTAINERS | add two new files 'crypto.h' & 'crypto.c' in tipc

Acked-by: Ying Xue <ying.xue@windreiver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/net/tipc/core.c b/net/tipc/core.c
index ab648dd150ee..fc01a13d7462 100644
--- a/net/tipc/core.c
+++ b/net/tipc/core.c
@@ -44,6 +44,7 @@
 #include "socket.h"
 #include "bcast.h"
 #include "node.h"
+#include "crypto.h"
 
 #include <linux/module.h>
 
@@ -68,6 +69,11 @@ static int __net_init tipc_init_net(struct net *net)
 	INIT_LIST_HEAD(&tn->node_list);
 	spin_lock_init(&tn->node_list_lock);
 
+#ifdef CONFIG_TIPC_CRYPTO
+	err = tipc_crypto_start(&tn->crypto_tx, net, NULL);
+	if (err)
+		goto out_crypto;
+#endif
 	err = tipc_sk_rht_init(net);
 	if (err)
 		goto out_sk_rht;
@@ -93,6 +99,11 @@ out_bclink:
 out_nametbl:
 	tipc_sk_rht_destroy(net);
 out_sk_rht:
+
+#ifdef CONFIG_TIPC_CRYPTO
+	tipc_crypto_stop(&tn->crypto_tx);
+out_crypto:
+#endif
 	return err;
 }
 
@@ -103,6 +114,9 @@ static void __net_exit tipc_exit_net(struct net *net)
 	tipc_bcast_stop(net);
 	tipc_nametbl_stop(net);
 	tipc_sk_rht_destroy(net);
+#ifdef CONFIG_TIPC_CRYPTO
+	tipc_crypto_stop(&tipc_net(net)->crypto_tx);
+#endif
 }
 
 static void __net_exit tipc_pernet_pre_exit(struct net *net)