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>

17 files changed, 2385 insertions, 46 deletions

diff --git a/net/tipc/Kconfig b/net/tipc/Kconfig
index b83e16ade4d2..716b61a701a8 100644
--- a/net/tipc/Kconfig
+++ b/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"
diff --git a/net/tipc/Makefile b/net/tipc/Makefile
index c86aba0282af..11255e970dd4 100644
--- a/net/tipc/Makefile
+++ b/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
diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 6ef1abdd525f..f41096a759fa 100644
--- a/net/tipc/bcast.c
+++ b/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)
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 6e15b9b1f1ef..d7ec26bd739d 100644
--- a/net/tipc/bearer.c
+++ b/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
 
@@ -516,10 +517,15 @@ 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();
 }
 
@@ -527,7 +533,8 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id,
  */
 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;
diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
index faca696d422f..d0c79cc6c0c2 100644
--- a/net/tipc/bearer.h
+++ b/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);
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)
diff --git a/net/tipc/core.h b/net/tipc/core.h
index 8776d32a4a47..775848a5f27e 100644
--- a/net/tipc/core.h
+++ b/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)
diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
new file mode 100644
index 000000000000..05f7ca76e8ce
--- /dev/null
+++ b/net/tipc/crypto.c
@@ -0,0 +1,1986 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * net/tipc/crypto.c: TIPC crypto for key handling & packet en/decryption
+ *
+ * Copyright (c) 2019, Ericsson AB
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <crypto/aead.h>
+#include <crypto/aes.h>
+#include "crypto.h"
+
+#define TIPC_TX_PROBE_LIM	msecs_to_jiffies(1000) /* > 1s */
+#define TIPC_TX_LASTING_LIM	msecs_to_jiffies(120000) /* 2 mins */
+#define TIPC_RX_ACTIVE_LIM	msecs_to_jiffies(3000) /* 3s */
+#define TIPC_RX_PASSIVE_LIM	msecs_to_jiffies(180000) /* 3 mins */
+#define TIPC_MAX_TFMS_DEF	10
+#define TIPC_MAX_TFMS_LIM	1000
+
+/**
+ * TIPC Key ids
+ */
+enum {
+	KEY_UNUSED = 0,
+	KEY_MIN,
+	KEY_1 = KEY_MIN,
+	KEY_2,
+	KEY_3,
+	KEY_MAX = KEY_3,
+};
+
+/**
+ * TIPC Crypto statistics
+ */
+enum {
+	STAT_OK,
+	STAT_NOK,
+	STAT_ASYNC,
+	STAT_ASYNC_OK,
+	STAT_ASYNC_NOK,
+	STAT_BADKEYS, /* tx only */
+	STAT_BADMSGS = STAT_BADKEYS, /* rx only */
+	STAT_NOKEYS,
+	STAT_SWITCHES,
+
+	MAX_STATS,
+};
+
+/* TIPC crypto statistics' header */
+static const char *hstats[MAX_STATS] = {"ok", "nok", "async", "async_ok",
+					"async_nok", "badmsgs", "nokeys",
+					"switches"};
+
+/* Max TFMs number per key */
+int sysctl_tipc_max_tfms __read_mostly = TIPC_MAX_TFMS_DEF;
+
+/**
+ * struct tipc_key - TIPC keys' status indicator
+ *
+ *         7     6     5     4     3     2     1     0
+ *      +-----+-----+-----+-----+-----+-----+-----+-----+
+ * key: | (reserved)|passive idx| active idx|pending idx|
+ *      +-----+-----+-----+-----+-----+-----+-----+-----+
+ */
+struct tipc_key {
+#define KEY_BITS (2)
+#define KEY_MASK ((1 << KEY_BITS) - 1)
+	union {
+		struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+			u8 pending:2,
+			   active:2,
+			   passive:2, /* rx only */
+			   reserved:2;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+			u8 reserved:2,
+			   passive:2, /* rx only */
+			   active:2,
+			   pending:2;
+#else
+#error  "Please fix <asm/byteorder.h>"
+#endif
+		} __packed;
+		u8 keys;
+	};
+};
+
+/**
+ * struct tipc_tfm - TIPC TFM structure to form a list of TFMs
+ */
+struct tipc_tfm {
+	struct crypto_aead *tfm;
+	struct list_head list;
+};
+
+/**
+ * struct tipc_aead - TIPC AEAD key structure
+ * @tfm_entry: per-cpu pointer to one entry in TFM list
+ * @crypto: TIPC crypto owns this key
+ * @cloned: reference to the source key in case cloning
+ * @users: the number of the key users (TX/RX)
+ * @salt: the key's SALT value
+ * @authsize: authentication tag size (max = 16)
+ * @mode: crypto mode is applied to the key
+ * @hint[]: a hint for user key
+ * @rcu: struct rcu_head
+ * @seqno: the key seqno (cluster scope)
+ * @refcnt: the key reference counter
+ */
+struct tipc_aead {
+#define TIPC_AEAD_HINT_LEN (5)
+	struct tipc_tfm * __percpu *tfm_entry;
+	struct tipc_crypto *crypto;
+	struct tipc_aead *cloned;
+	atomic_t users;
+	u32 salt;
+	u8 authsize;
+	u8 mode;
+	char hint[TIPC_AEAD_HINT_LEN + 1];
+	struct rcu_head rcu;
+
+	atomic64_t seqno ____cacheline_aligned;
+	refcount_t refcnt ____cacheline_aligned;
+
+} ____cacheline_aligned;
+
+/**
+ * struct tipc_crypto_stats - TIPC Crypto statistics
+ */
+struct tipc_crypto_stats {
+	unsigned int stat[MAX_STATS];
+};
+
+/**
+ * struct tipc_crypto - TIPC TX/RX crypto structure
+ * @net: struct net
+ * @node: TIPC node (RX)
+ * @aead: array of pointers to AEAD keys for encryption/decryption
+ * @peer_rx_active: replicated peer RX active key index
+ * @key: the key states
+ * @working: the crypto is working or not
+ * @stats: the crypto statistics
+ * @sndnxt: the per-peer sndnxt (TX)
+ * @timer1: general timer 1 (jiffies)
+ * @timer2: general timer 1 (jiffies)
+ * @lock: tipc_key lock
+ */
+struct tipc_crypto {
+	struct net *net;
+	struct tipc_node *node;
+	struct tipc_aead __rcu *aead[KEY_MAX + 1]; /* key[0] is UNUSED */
+	atomic_t peer_rx_active;
+	struct tipc_key key;
+	u8 working:1;
+	struct tipc_crypto_stats __percpu *stats;
+
+	atomic64_t sndnxt ____cacheline_aligned;
+	unsigned long timer1;
+	unsigned long timer2;
+	spinlock_t lock; /* crypto lock */
+
+} ____cacheline_aligned;
+
+/* struct tipc_crypto_tx_ctx - TX context for callbacks */
+struct tipc_crypto_tx_ctx {
+	struct tipc_aead *aead;
+	struct tipc_bearer *bearer;
+	struct tipc_media_addr dst;
+};
+
+/* struct tipc_crypto_rx_ctx - RX context for callbacks */
+struct tipc_crypto_rx_ctx {
+	struct tipc_aead *aead;
+	struct tipc_bearer *bearer;
+};
+
+static struct tipc_aead *tipc_aead_get(struct tipc_aead __rcu *aead);
+static inline void tipc_aead_put(struct tipc_aead *aead);
+static void tipc_aead_free(struct rcu_head *rp);
+static int tipc_aead_users(struct tipc_aead __rcu *aead);
+static void tipc_aead_users_inc(struct tipc_aead __rcu *aead, int lim);
+static void tipc_aead_users_dec(struct tipc_aead __rcu *aead, int lim);
+static void tipc_aead_users_set(struct tipc_aead __rcu *aead, int val);
+static struct crypto_aead *tipc_aead_tfm_next(struct tipc_aead *aead);
+static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
+			  u8 mode);
+static int tipc_aead_clone(struct tipc_aead **dst, struct tipc_aead *src);
+static void *tipc_aead_mem_alloc(struct crypto_aead *tfm,
+				 unsigned int crypto_ctx_size,
+				 u8 **iv, struct aead_request **req,
+				 struct scatterlist **sg, int nsg);
+static int tipc_aead_encrypt(struct tipc_aead *aead, struct sk_buff *skb,
+			     struct tipc_bearer *b,
+			     struct tipc_media_addr *dst,
+			     struct tipc_node *__dnode);
+static void tipc_aead_encrypt_done(struct crypto_async_request *base, int err);
+static int tipc_aead_decrypt(struct net *net, struct tipc_aead *aead,
+			     struct sk_buff *skb, struct tipc_bearer *b);
+static void tipc_aead_decrypt_done(struct crypto_async_request *base, int err);
+static inline int tipc_ehdr_size(struct tipc_ehdr *ehdr);
+static int tipc_ehdr_build(struct net *net, struct tipc_aead *aead,
+			   u8 tx_key, struct sk_buff *skb,
+			   struct tipc_crypto *__rx);
+static inline void tipc_crypto_key_set_state(struct tipc_crypto *c,
+					     u8 new_passive,
+					     u8 new_active,
+					     u8 new_pending);
+static int tipc_crypto_key_attach(struct tipc_crypto *c,
+				  struct tipc_aead *aead, u8 pos);
+static bool tipc_crypto_key_try_align(struct tipc_crypto *rx, u8 new_pending);
+static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
+						 struct tipc_crypto *rx,
+						 struct sk_buff *skb);
+static void tipc_crypto_key_synch(struct tipc_crypto *rx, u8 new_rx_active,
+				  struct tipc_msg *hdr);
+static int tipc_crypto_key_revoke(struct net *net, u8 tx_key);
+static void tipc_crypto_rcv_complete(struct net *net, struct tipc_aead *aead,
+				     struct tipc_bearer *b,
+				     struct sk_buff **skb, int err);
+static void tipc_crypto_do_cmd(struct net *net, int cmd);
+static char *tipc_crypto_key_dump(struct tipc_crypto *c, char *buf);
+#ifdef TIPC_CRYPTO_DEBUG
+static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
+				  char *buf);
+#endif
+
+#define key_next(cur) ((cur) % KEY_MAX + 1)
+
+#define tipc_aead_rcu_ptr(rcu_ptr, lock)				\
+	rcu_dereference_protected((rcu_ptr), lockdep_is_held(lock))
+
+#define tipc_aead_rcu_swap(rcu_ptr, ptr, lock)				\
+	rcu_swap_protected((rcu_ptr), (ptr), lockdep_is_held(lock))
+
+#define tipc_aead_rcu_replace(rcu_ptr, ptr, lock)			\
+do {									\
+	typeof(rcu_ptr) __tmp = rcu_dereference_protected((rcu_ptr),	\
+						lockdep_is_held(lock));	\
+	rcu_assign_pointer((rcu_ptr), (ptr));				\
+	tipc_aead_put(__tmp);						\
+} while (0)
+
+#define tipc_crypto_key_detach(rcu_ptr, lock)				\
+	tipc_aead_rcu_replace((rcu_ptr), NULL, lock)
+
+/**
+ * tipc_aead_key_validate - Validate a AEAD user key
+ */
+int tipc_aead_key_validate(struct tipc_aead_key *ukey)
+{
+	int keylen;
+
+	/* Check if algorithm exists */
+	if (unlikely(!crypto_has_alg(ukey->alg_name, 0, 0))) {
+		pr_info("Not found cipher: \"%s\"!\n", ukey->alg_name);
+		return -ENODEV;
+	}
+
+	/* Currently, we only support the "gcm(aes)" cipher algorithm */
+	if (strcmp(ukey->alg_name, "gcm(aes)"))
+		return -ENOTSUPP;
+
+	/* Check if key size is correct */
+	keylen = ukey->keylen - TIPC_AES_GCM_SALT_SIZE;
+	if (unlikely(keylen != TIPC_AES_GCM_KEY_SIZE_128 &&
+		     keylen != TIPC_AES_GCM_KEY_SIZE_192 &&
+		     keylen != TIPC_AES_GCM_KEY_SIZE_256))
+		return -EINVAL;
+
+	return 0;
+}
+
+static struct tipc_aead *tipc_aead_get(struct tipc_aead __rcu *aead)
+{
+	struct tipc_aead *tmp;
+
+	rcu_read_lock();
+	tmp = rcu_dereference(aead);
+	if (unlikely(!tmp || !refcount_inc_not_zero(&tmp->refcnt)))
+		tmp = NULL;
+	rcu_read_unlock();
+
+	return tmp;
+}
+
+static inline void tipc_aead_put(struct tipc_aead *aead)
+{
+	if (aead && refcount_dec_and_test(&aead->refcnt))
+		call_rcu(&aead->rcu, tipc_aead_free);
+}
+
+/**
+ * tipc_aead_free - Release AEAD key incl. all the TFMs in the list
+ * @rp: rcu head pointer
+ */
+static void tipc_aead_free(struct rcu_head *rp)
+{
+	struct tipc_aead *aead = container_of(rp, struct tipc_aead, rcu);
+	struct tipc_tfm *tfm_entry, *head, *tmp;
+
+	if (aead->cloned) {
+		tipc_aead_put(aead->cloned);
+	} else {
+		head = *this_cpu_ptr(aead->tfm_entry);
+		list_for_each_entry_safe(tfm_entry, tmp, &head->list, list) {
+			crypto_free_aead(tfm_entry->tfm);
+			list_del(&tfm_entry->list);
+			kfree(tfm_entry);
+		}
+		/* Free the head */
+		crypto_free_aead(head->tfm);
+		list_del(&head->list);
+		kfree(head);
+	}
+	free_percpu(aead->tfm_entry);
+	kfree(aead);
+}
+
+static int tipc_aead_users(struct tipc_aead __rcu *aead)
+{
+	struct tipc_aead *tmp;
+	int users = 0;
+
+	rcu_read_lock();
+	tmp = rcu_dereference(aead);
+	if (tmp)
+		users = atomic_read(&tmp->users);
+	rcu_read_unlock();
+
+	return users;
+}
+
+static void tipc_aead_users_inc(struct tipc_aead __rcu *aead, int lim)
+{
+	struct tipc_aead *tmp;
+
+	rcu_read_lock();
+	tmp = rcu_dereference(aead);
+	if (tmp)
+		atomic_add_unless(&tmp->users, 1, lim);
+	rcu_read_unlock();
+}
+
+static void tipc_aead_users_dec(struct tipc_aead __rcu *aead, int lim)
+{
+	struct tipc_aead *tmp;
+
+	rcu_read_lock();
+	tmp = rcu_dereference(aead);
+	if (tmp)
+		atomic_add_unless(&rcu_dereference(aead)->users, -1, lim);
+	rcu_read_unlock();
+}
+
+static void tipc_aead_users_set(struct tipc_aead __rcu *aead, int val)
+{
+	struct tipc_aead *tmp;
+	int cur;
+
+	rcu_read_lock();
+	tmp = rcu_dereference(aead);
+	if (tmp) {
+		do {
+			cur = atomic_read(&tmp->users);
+			if (cur == val)
+				break;
+		} while (atomic_cmpxchg(&tmp->users, cur, val) != cur);
+	}
+	rcu_read_unlock();
+}
+
+/**
+ * tipc_aead_tfm_next - Move TFM entry to the next one in list and return it
+ */
+static struct crypto_aead *tipc_aead_tfm_next(struct tipc_aead *aead)
+{
+	struct tipc_tfm **tfm_entry = this_cpu_ptr(aead->tfm_entry);
+
+	*tfm_entry = list_next_entry(*tfm_entry, list);
+	return (*tfm_entry)->tfm;
+}
+
+/**
+ * tipc_aead_init - Initiate TIPC AEAD
+ * @aead: returned new TIPC AEAD key handle pointer
+ * @ukey: pointer to user key data
+ * @mode: the key mode
+ *
+ * Allocate a (list of) new cipher transformation (TFM) with the specific user
+ * key data if valid. The number of the allocated TFMs can be set via the sysfs
+ * "net/tipc/max_tfms" first.
+ * Also, all the other AEAD data are also initialized.
+ *
+ * Return: 0 if the initiation is successful, otherwise: < 0
+ */
+static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
+			  u8 mode)
+{
+	struct tipc_tfm *tfm_entry, *head;
+	struct crypto_aead *tfm;
+	struct tipc_aead *tmp;
+	int keylen, err, cpu;
+	int tfm_cnt = 0;
+
+	if (unlikely(*aead))
+		return -EEXIST;
+
+	/* Allocate a new AEAD */
+	tmp = kzalloc(sizeof(*tmp), GFP_ATOMIC);
+	if (unlikely(!tmp))
+		return -ENOMEM;
+
+	/* The key consists of two parts: [AES-KEY][SALT] */
+	keylen = ukey->keylen - TIPC_AES_GCM_SALT_SIZE;
+
+	/* Allocate per-cpu TFM entry pointer */
+	tmp->tfm_entry = alloc_percpu(struct tipc_tfm *);
+	if (!tmp->tfm_entry) {
+		kzfree(tmp);
+		return -ENOMEM;
+	}
+
+	/* Make a list of TFMs with the user key data */
+	do {
+		tfm = crypto_alloc_aead(ukey->alg_name, 0, 0);
+		if (IS_ERR(tfm)) {
+			err = PTR_ERR(tfm);
+			break;
+		}
+
+		if (unlikely(!tfm_cnt &&
+			     crypto_aead_ivsize(tfm) != TIPC_AES_GCM_IV_SIZE)) {
+			crypto_free_aead(tfm);
+			err = -ENOTSUPP;
+			break;
+		}
+
+		err |= crypto_aead_setauthsize(tfm, TIPC_AES_GCM_TAG_SIZE);
+		err |= crypto_aead_setkey(tfm, ukey->key, keylen);
+		if (unlikely(err)) {
+			crypto_free_aead(tfm);
+			break;
+		}
+
+		tfm_entry = kmalloc(sizeof(*tfm_entry), GFP_KERNEL);
+		if (unlikely(!tfm_entry)) {
+			crypto_free_aead(tfm);
+			err = -ENOMEM;
+			break;
+		}
+		INIT_LIST_HEAD(&tfm_entry->list);
+		tfm_entry->tfm = tfm;
+
+		/* First entry? */
+		if (!tfm_cnt) {
+			head = tfm_entry;
+			for_each_possible_cpu(cpu) {
+				*per_cpu_ptr(tmp->tfm_entry, cpu) = head;
+			}
+		} else {
+			list_add_tail(&tfm_entry->list, &head->list);
+		}
+
+	} while (++tfm_cnt < sysctl_tipc_max_tfms);
+
+	/* Not any TFM is allocated? */
+	if (!tfm_cnt) {
+		free_percpu(tmp->tfm_entry);
+		kzfree(tmp);
+		return err;
+	}
+
+	/* Copy some chars from the user key as a hint */
+	memcpy(tmp->hint, ukey->key, TIPC_AEAD_HINT_LEN);
+	tmp->hint[TIPC_AEAD_HINT_LEN] = '\0';
+
+	/* Initialize the other data */
+	tmp->mode = mode;
+	tmp->cloned = NULL;
+	tmp->authsize = TIPC_AES_GCM_TAG_SIZE;
+	memcpy(&tmp->salt, ukey->key + keylen, TIPC_AES_GCM_SALT_SIZE);
+	atomic_set(&tmp->users, 0);
+	atomic64_set(&tmp->seqno, 0);
+	refcount_set(&tmp->refcnt, 1);
+
+	*aead = tmp;
+	return 0;
+}
+
+/**
+ * tipc_aead_clone - Clone a TIPC AEAD key
+ * @dst: dest key for the cloning
+ * @src: source key to clone from
+ *
+ * Make a "copy" of the source AEAD key data to the dest, the TFMs list is
+ * common for the keys.
+ * A reference to the source is hold in the "cloned" pointer for the later
+ * freeing purposes.
+ *
+ * Note: this must be done in cluster-key mode only!
+ * Return: 0 in case of success, otherwise < 0
+ */
+static int tipc_aead_clone(struct tipc_aead **dst, struct tipc_aead *src)
+{
+	struct tipc_aead *aead;
+	int cpu;
+
+	if (!src)
+		return -ENOKEY;
+
+	if (src->mode != CLUSTER_KEY)
+		return -EINVAL;
+
+	if (unlikely(*dst))
+		return -EEXIST;
+
+	aead = kzalloc(sizeof(*aead), GFP_ATOMIC);
+	if (unlikely(!aead))
+		return -ENOMEM;
+
+	aead->tfm_entry = alloc_percpu_gfp(struct tipc_tfm *, GFP_ATOMIC);
+	if (unlikely(!aead->tfm_entry)) {
+		kzfree(aead);
+		return -ENOMEM;
+	}
+
+	for_each_possible_cpu(cpu) {
+		*per_cpu_ptr(aead->tfm_entry, cpu) =
+				*per_cpu_ptr(src->tfm_entry, cpu);
+	}
+
+	memcpy(aead->hint, src->hint, sizeof(src->hint));
+	aead->mode = src->mode;
+	aead->salt = src->salt;
+	aead->authsize = src->authsize;
+	atomic_set(&aead->users, 0);
+	atomic64_set(&aead->seqno, 0);
+	refcount_set(&aead->refcnt, 1);
+
+	WARN_ON(!refcount_inc_not_zero(&src->refcnt));
+	aead->cloned = src;
+
+	*dst = aead;
+	return 0;
+}
+
+/**
+ * tipc_aead_mem_alloc - Allocate memory for AEAD request operations
+ * @tfm: cipher handle to be registered with the request
+ * @crypto_ctx_size: size of crypto context for callback
+ * @iv: returned pointer to IV data
+ * @req: returned pointer to AEAD request data
+ * @sg: returned pointer to SG lists
+ * @nsg: number of SG lists to be allocated
+ *
+ * Allocate memory to store the crypto context data, AEAD request, IV and SG
+ * lists, the memory layout is as follows:
+ * crypto_ctx || iv || aead_req || sg[]
+ *
+ * Return: the pointer to the memory areas in case of success, otherwise NULL
+ */
+static void *tipc_aead_mem_alloc(struct crypto_aead *tfm,
+				 unsigned int crypto_ctx_size,
+				 u8 **iv, struct aead_request **req,
+				 struct scatterlist **sg, int nsg)
+{
+	unsigned int iv_size, req_size;
+	unsigned int len;
+	u8 *mem;
+
+	iv_size = crypto_aead_ivsize(tfm);
+	req_size = sizeof(**req) + crypto_aead_reqsize(tfm);
+
+	len = crypto_ctx_size;
+	len += iv_size;
+	len += crypto_aead_alignmask(tfm) & ~(crypto_tfm_ctx_alignment() - 1);
+	len = ALIGN(len, crypto_tfm_ctx_alignment());
+	len += req_size;
+	len = ALIGN(len, __alignof__(struct scatterlist));
+	len += nsg * sizeof(**sg);
+
+	mem = kmalloc(len, GFP_ATOMIC);
+	if (!mem)
+		return NULL;
+
+	*iv = (u8 *)PTR_ALIGN(mem + crypto_ctx_size,
+			      crypto_aead_alignmask(tfm) + 1);
+	*req = (struct aead_request *)PTR_ALIGN(*iv + iv_size,
+						crypto_tfm_ctx_alignment());
+	*sg = (struct scatterlist *)PTR_ALIGN((u8 *)*req + req_size,
+					      __alignof__(struct scatterlist));
+
+	return (void *)mem;
+}
+
+/**
+ * tipc_aead_encrypt - Encrypt a message
+ * @aead: TIPC AEAD key for the message encryption
+ * @skb: the input/output skb
+ * @b: TIPC bearer where the message will be delivered after the encryption
+ * @dst: the destination media address
+ * @__dnode: TIPC dest node if "known"
+ *
+ * Return:
+ * 0                   : if the encryption has completed
+ * -EINPROGRESS/-EBUSY : if a callback will be performed
+ * < 0                 : the encryption has failed
+ */
+static int tipc_aead_encrypt(struct tipc_aead *aead, struct sk_buff *skb,
+			     struct tipc_bearer *b,
+			     struct tipc_media_addr *dst,
+			     struct tipc_node *__dnode)
+{
+	struct crypto_aead *tfm = tipc_aead_tfm_next(aead);
+	struct tipc_crypto_tx_ctx *tx_ctx;
+	struct aead_request *req;
+	struct sk_buff *trailer;
+	struct scatterlist *sg;
+	struct tipc_ehdr *ehdr;
+	int ehsz, len, tailen, nsg, rc;
+	void *ctx;
+	u32 salt;
+	u8 *iv;
+
+	/* Make sure message len at least 4-byte aligned */
+	len = ALIGN(skb->len, 4);
+	tailen = len - skb->len + aead->authsize;
+
+	/* Expand skb tail for authentication tag:
+	 * As for simplicity, we'd have made sure skb having enough tailroom
+	 * for authentication tag @skb allocation. Even when skb is nonlinear
+	 * but there is no frag_list, it should be still fine!
+	 * Otherwise, we must cow it to be a writable buffer with the tailroom.
+	 */
+#ifdef TIPC_CRYPTO_DEBUG
+	SKB_LINEAR_ASSERT(skb);
+	if (tailen > skb_tailroom(skb)) {
+		pr_warn("TX: skb tailroom is not enough: %d, requires: %d\n",
+			skb_tailroom(skb), tailen);
+	}
+#endif
+
+	if (unlikely(!skb_cloned(skb) && tailen <= skb_tailroom(skb))) {
+		nsg = 1;
+		trailer = skb;
+	} else {
+		/* TODO: We could avoid skb_cow_data() if skb has no frag_list
+		 * e.g. by skb_fill_page_desc() to add another page to the skb
+		 * with the wanted tailen... However, page skbs look not often,
+		 * so take it easy now!
+		 * Cloned skbs e.g. from link_xmit() seems no choice though :(
+		 */
+		nsg = skb_cow_data(skb, tailen, &trailer);
+		if (unlikely(nsg < 0)) {
+			pr_err("TX: skb_cow_data() returned %d\n", nsg);
+			return nsg;
+		}
+	}
+
+	pskb_put(skb, trailer, tailen);
+
+	/* Allocate memory for the AEAD operation */
+	ctx = tipc_aead_mem_alloc(tfm, sizeof(*tx_ctx), &iv, &req, &sg, nsg);
+	if (unlikely(!ctx))
+		return -ENOMEM;
+	TIPC_SKB_CB(skb)->crypto_ctx = ctx;
+
+	/* Map skb to the sg lists */
+	sg_init_table(sg, nsg);
+	rc = skb_to_sgvec(skb, sg, 0, skb->len);
+	if (unlikely(rc < 0)) {
+		pr_err("TX: skb_to_sgvec() returned %d, nsg %d!\n", rc, nsg);
+		goto exit;
+	}
+
+	/* Prepare IV: [SALT (4 octets)][SEQNO (8 octets)]
+	 * In case we're in cluster-key mode, SALT is varied by xor-ing with
+	 * the source address (or w0 of id), otherwise with the dest address
+	 * if dest is known.
+	 */
+	ehdr = (struct tipc_ehdr *)skb->data;
+	salt = aead->salt;
+	if (aead->mode == CLUSTER_KEY)
+		salt ^= ehdr->addr; /* __be32 */
+	else if (__dnode)
+		salt ^= tipc_node_get_addr(__dnode);
+	memcpy(iv, &salt, 4);
+	memcpy(iv + 4, (u8 *)&ehdr->seqno, 8);
+
+	/* Prepare request */
+	ehsz = tipc_ehdr_size(ehdr);
+	aead_request_set_tfm(req, tfm);
+	aead_request_set_ad(req, ehsz);
+	aead_request_set_crypt(req, sg, sg, len - ehsz, iv);
+
+	/* Set callback function & data */
+	aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+				  tipc_