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>

net/tipc/Kconfig

@@ -35,6 +35,21 @@ config TIPC_MEDIA_UDP
 	  Saying Y here will enable support for running TIPC over IP/UDP
 	bool
 	default y
+config TIPC_CRYPTO
+	bool "TIPC encryption support"
+	depends on TIPC
+	select CRYPTO
+	select CRYPTO_AES
+	select CRYPTO_GCM
+	help
+	  Saying Y here will enable support for TIPC encryption.
+	  All TIPC messages will be encrypted/decrypted by using the currently most
+	  advanced algorithm: AEAD AES-GCM (like IPSec or TLS) before leaving/
+	  entering the TIPC stack.
+	  Key setting from user-space is performed via netlink by a user program
+	  (e.g. the iproute2 'tipc' tool).
+	bool
+	default y
 
 config TIPC_DIAG
 	tristate "TIPC: socket monitoring interface"

net/tipc/Makefile

@@ -16,6 +16,7 @@ CFLAGS_trace.o += -I$(src)
 tipc-$(CONFIG_TIPC_MEDIA_UDP)	+= udp_media.o
 tipc-$(CONFIG_TIPC_MEDIA_IB)	+= ib_media.o
 tipc-$(CONFIG_SYSCTL)		+= sysctl.o
+tipc-$(CONFIG_TIPC_CRYPTO)	+= crypto.o
 
 
 obj-$(CONFIG_TIPC_DIAG)	+= diag.o

net/tipc/bcast.c

@@ -84,7 +84,7 @@ static struct tipc_bc_base *tipc_bc_base(struct net *net)
  */
 int tipc_bcast_get_mtu(struct net *net)
 {
-	return tipc_link_mtu(tipc_bc_sndlink(net)) - INT_H_SIZE;
+	return tipc_link_mss(tipc_bc_sndlink(net));
 }
 
 void tipc_bcast_disable_rcast(struct net *net)

net/tipc/bearer.c

@@ -44,6 +44,7 @@
 #include "netlink.h"
 #include "udp_media.h"
 #include "trace.h"
+#include "crypto.h"
 
 #define MAX_ADDR_STR 60
 
@@ -516,18 +517,24 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id,
 
 	rcu_read_lock();
 	b = bearer_get(net, bearer_id);
-	if (likely(b && (test_bit(0, &b->up) || msg_is_reset(hdr))))
-		b->media->send_msg(net, skb, b, dest);
-	else
+	if (likely(b && (test_bit(0, &b->up) || msg_is_reset(hdr)))) {
+#ifdef CONFIG_TIPC_CRYPTO
+		tipc_crypto_xmit(net, &skb, b, dest, NULL);
+		if (skb)
+#endif
+			b->media->send_msg(net, skb, b, dest);
+	} else {
 		kfree_skb(skb);
+	}
 	rcu_read_unlock();
 }
 
 /* tipc_bearer_xmit() -send buffer to destination over bearer
  */
 void tipc_bearer_xmit(struct net *net, u32 bearer_id,
 		      struct sk_buff_head *xmitq,
-		      struct tipc_media_addr *dst)
+		      struct tipc_media_addr *dst,
+		      struct tipc_node *__dnode)
 {
 	struct tipc_bearer *b;
 	struct sk_buff *skb, *tmp;
@@ -541,10 +548,15 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id,
 		__skb_queue_purge(xmitq);
 	skb_queue_walk_safe(xmitq, skb, tmp) {
 		__skb_dequeue(xmitq);
-		if (likely(test_bit(0, &b->up) || msg_is_reset(buf_msg(skb))))
-			b->media->send_msg(net, skb, b, dst);
-		else
+		if (likely(test_bit(0, &b->up) || msg_is_reset(buf_msg(skb)))) {
+#ifdef CONFIG_TIPC_CRYPTO
+			tipc_crypto_xmit(net, &skb, b, dst, __dnode);
+			if (skb)
+#endif
+				b->media->send_msg(net, skb, b, dst);
+		} else {
 			kfree_skb(skb);
+		}
 	}
 	rcu_read_unlock();
 }
@@ -555,6 +567,7 @@ void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id,
 			 struct sk_buff_head *xmitq)
 {
 	struct tipc_net *tn = tipc_net(net);
+	struct tipc_media_addr *dst;
 	int net_id = tn->net_id;
 	struct tipc_bearer *b;
 	struct sk_buff *skb, *tmp;
@@ -569,7 +582,12 @@ void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id,
 		msg_set_non_seq(hdr, 1);
 		msg_set_mc_netid(hdr, net_id);
 		__skb_dequeue(xmitq);
-		b->media->send_msg(net, skb, b, &b->bcast_addr);
+		dst = &b->bcast_addr;
+#ifdef CONFIG_TIPC_CRYPTO
+		tipc_crypto_xmit(net, &skb, b, dst, NULL);
+		if (skb)
+#endif
+			b->media->send_msg(net, skb, b, dst);
 	}
 	rcu_read_unlock();
 }
@@ -596,6 +614,7 @@ static int tipc_l2_rcv_msg(struct sk_buff *skb, struct net_device *dev,
 	if (likely(b && test_bit(0, &b->up) &&
 		   (skb->pkt_type <= PACKET_MULTICAST))) {
 		skb_mark_not_on_list(skb);
+		TIPC_SKB_CB(skb)->flags = 0;
 		tipc_rcv(dev_net(b->pt.dev), skb, b);
 		rcu_read_unlock();
 		return NET_RX_SUCCESS;

net/tipc/bearer.h

@@ -232,7 +232,8 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id,
 			  struct tipc_media_addr *dest);
 void tipc_bearer_xmit(struct net *net, u32 bearer_id,
 		      struct sk_buff_head *xmitq,
-		      struct tipc_media_addr *dst);
+		      struct tipc_media_addr *dst,
+		      struct tipc_node *__dnode);
 void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id,
 			 struct sk_buff_head *xmitq);
 void tipc_clone_to_loopback(struct net *net, struct sk_buff_head *pkts);

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 @@ static int __net_init tipc_init_net(struct net *net)
 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)

net/tipc/core.h

@@ -68,6 +68,9 @@ struct tipc_link;
 struct tipc_name_table;
 struct tipc_topsrv;
 struct tipc_monitor;
+#ifdef CONFIG_TIPC_CRYPTO
+struct tipc_crypto;
+#endif
 
 #define TIPC_MOD_VER "2.0.0"
 
@@ -129,6 +132,11 @@ struct tipc_net {
 
 	/* Tracing of node internal messages */
 	struct packet_type loopback_pt;
+
+#ifdef CONFIG_TIPC_CRYPTO
+	/* TX crypto handler */
+	struct tipc_crypto *crypto_tx;
+#endif
 };
 
 static inline struct tipc_net *tipc_net(struct net *net)