Merge branch 'tipc-add-more-features-to-TIPC-encryption'

Tuong Lien says:

====================
tipc: add more features to TIPC encryption

This series adds some new features to TIPC encryption:

- Patch 1 ("tipc: optimize key switching time and logic") optimizes the
code and logic in preparation for the following commits.

- Patch 2 ("tipc: introduce encryption master key") introduces support
of 'master key' for authentication of new nodes and key exchange. A
master key can be set/changed by user via netlink (eg. using the same
'tipc node set key' command in iproute2/tipc).

- Patch 3 ("tipc: add automatic session key exchange") allows a session
key to be securely exchanged between nodes as needed.

- Patch 4 ("tipc: add automatic rekeying for encryption key") adds
automatic 'rekeying' of session keys a specific interval. The new key
will be distributed automatically to peer nodes, so become active then.
The rekeying interval is configurable via netlink as well.

v2: update the "tipc: add automatic session key exchange" patch to fix
"implicit declaration" issue when built without "CONFIG_TIPC_CRYPTO".

v3: update the patches according to David comments by using the
"genl_info->extack" for messages in response to netlink user config
requests.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

10 files changed, 859 insertions, 289 deletions

diff --git a/include/uapi/linux/tipc.h b/include/uapi/linux/tipc.h
index add01db1daef..80ea15e12113 100644
--- a/include/uapi/linux/tipc.h
+++ b/include/uapi/linux/tipc.h
@@ -254,6 +254,8 @@ static inline int tipc_aead_key_size(struct tipc_aead_key *key)
 	return sizeof(*key) + key->keylen;
 }
 
+#define TIPC_REKEYING_NOW		(~0U)
+
 /* The macros and functions below are deprecated:
  */
 
diff --git a/include/uapi/linux/tipc_netlink.h b/include/uapi/linux/tipc_netlink.h
index dc0d23a50e69..d847dd671d79 100644
--- a/include/uapi/linux/tipc_netlink.h
+++ b/include/uapi/linux/tipc_netlink.h
@@ -165,6 +165,8 @@ enum {
 	TIPC_NLA_NODE_UP,		/* flag */
 	TIPC_NLA_NODE_ID,		/* data */
 	TIPC_NLA_NODE_KEY,		/* data */
+	TIPC_NLA_NODE_KEY_MASTER,	/* flag */
+	TIPC_NLA_NODE_REKEYING,		/* u32 */
 
 	__TIPC_NLA_NODE_MAX,
 	TIPC_NLA_NODE_MAX = __TIPC_NLA_NODE_MAX - 1
diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 7c523dc81575..40c44101fe8e 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -36,22 +36,28 @@
 
 #include <crypto/aead.h>
 #include <crypto/aes.h>
+#include <crypto/rng.h>
 #include "crypto.h"
+#include "msg.h"
+#include "bcast.h"
 
-#define TIPC_TX_PROBE_LIM	msecs_to_jiffies(1000) /* > 1s */
-#define TIPC_TX_LASTING_LIM	msecs_to_jiffies(120000) /* 2 mins */
+#define TIPC_TX_GRACE_PERIOD	msecs_to_jiffies(5000) /* 5s */
+#define TIPC_TX_LASTING_TIME	msecs_to_jiffies(10000) /* 10s */
 #define TIPC_RX_ACTIVE_LIM	msecs_to_jiffies(3000) /* 3s */
-#define TIPC_RX_PASSIVE_LIM	msecs_to_jiffies(180000) /* 3 mins */
+#define TIPC_RX_PASSIVE_LIM	msecs_to_jiffies(15000) /* 15s */
+
 #define TIPC_MAX_TFMS_DEF	10
 #define TIPC_MAX_TFMS_LIM	1000
 
+#define TIPC_REKEYING_INTV_DEF	(60 * 24) /* default: 1 day */
+
 /**
  * TIPC Key ids
  */
 enum {
-	KEY_UNUSED = 0,
-	KEY_MIN,
-	KEY_1 = KEY_MIN,
+	KEY_MASTER = 0,
+	KEY_MIN = KEY_MASTER,
+	KEY_1 = 1,
 	KEY_2,
 	KEY_3,
 	KEY_MAX = KEY_3,
@@ -81,6 +87,8 @@ static const char *hstats[MAX_STATS] = {"ok", "nok", "async", "async_ok",
 
 /* Max TFMs number per key */
 int sysctl_tipc_max_tfms __read_mostly = TIPC_MAX_TFMS_DEF;
+/* Key exchange switch, default: on */
+int sysctl_tipc_key_exchange_enabled __read_mostly = 1;
 
 /**
  * struct tipc_key - TIPC keys' status indicator
@@ -132,6 +140,8 @@ struct tipc_tfm {
  * @mode: crypto mode is applied to the key
  * @hint[]: a hint for user key
  * @rcu: struct rcu_head
+ * @key: the aead key
+ * @gen: the key's generation
  * @seqno: the key seqno (cluster scope)
  * @refcnt: the key reference counter
  */
@@ -144,8 +154,10 @@ struct tipc_aead {
 	u32 salt;
 	u8 authsize;
 	u8 mode;
-	char hint[TIPC_AEAD_HINT_LEN + 1];
+	char hint[2 * TIPC_AEAD_HINT_LEN + 1];
 	struct rcu_head rcu;
+	struct tipc_aead_key *key;
+	u16 gen;
 
 	atomic64_t seqno ____cacheline_aligned;
 	refcount_t refcnt ____cacheline_aligned;
@@ -165,26 +177,56 @@ struct tipc_crypto_stats {
  * @node: TIPC node (RX)
  * @aead: array of pointers to AEAD keys for encryption/decryption
  * @peer_rx_active: replicated peer RX active key index
+ * @key_gen: TX/RX key generation
  * @key: the key states
- * @working: the crypto is working or not
+ * @skey_mode: session key's mode
+ * @skey: received session key
+ * @wq: common workqueue on TX crypto
+ * @work: delayed work sched for TX/RX
+ * @key_distr: key distributing state
+ * @rekeying_intv: rekeying interval (in minutes)
  * @stats: the crypto statistics
+ * @name: the crypto name
  * @sndnxt: the per-peer sndnxt (TX)
  * @timer1: general timer 1 (jiffies)
- * @timer2: general timer 1 (jiffies)
+ * @timer2: general timer 2 (jiffies)
+ * @working: the crypto is working or not
+ * @key_master: flag indicates if master key exists
+ * @legacy_user: flag indicates if a peer joins w/o master key (for bwd comp.)
+ * @nokey: no key indication
  * @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 */
+	struct tipc_aead __rcu *aead[KEY_MAX + 1];
 	atomic_t peer_rx_active;
+	u16 key_gen;
 	struct tipc_key key;
-	u8 working:1;
+	u8 skey_mode;
+	struct tipc_aead_key *skey;
+	struct workqueue_struct *wq;
+	struct delayed_work work;
+#define KEY_DISTR_SCHED		1
+#define KEY_DISTR_COMPL		2
+	atomic_t key_distr;
+	u32 rekeying_intv;
+
 	struct tipc_crypto_stats __percpu *stats;
+	char name[48];
 
 	atomic64_t sndnxt ____cacheline_aligned;
 	unsigned long timer1;
 	unsigned long timer2;
+	union {
+		struct {
+			u8 working:1;
+			u8 key_master:1;
+			u8 legacy_user:1;
+			u8 nokey: 1;
+		};
+		u8 flags;
+	};
 	spinlock_t lock; /* crypto lock */
 
 } ____cacheline_aligned;
@@ -234,23 +276,35 @@ static inline void tipc_crypto_key_set_state(struct tipc_crypto *c,
 					     u8 new_active,
 					     u8 new_pending);
 static int tipc_crypto_key_attach(struct tipc_crypto *c,
-				  struct tipc_aead *aead, u8 pos);
+				  struct tipc_aead *aead, u8 pos,
+				  bool master_key);
 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);
+						 struct sk_buff *skb,
+						 u8 tx_key);
+static void tipc_crypto_key_synch(struct tipc_crypto *rx, struct sk_buff *skb);
 static int tipc_crypto_key_revoke(struct net *net, u8 tx_key);
+static inline void tipc_crypto_clone_msg(struct net *net, struct sk_buff *_skb,
+					 struct tipc_bearer *b,
+					 struct tipc_media_addr *dst,
+					 struct tipc_node *__dnode, u8 type);
 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
+static int tipc_crypto_key_xmit(struct net *net, struct tipc_aead_key *skey,
+				u16 gen, u8 mode, u32 dnode);
+static bool tipc_crypto_key_rcv(struct tipc_crypto *rx, struct tipc_msg *hdr);
+static void tipc_crypto_work_tx(struct work_struct *work);
+static void tipc_crypto_work_rx(struct work_struct *work);
+static int tipc_aead_key_generate(struct tipc_aead_key *skey);
+
+#define is_tx(crypto) (!(crypto)->node)
+#define is_rx(crypto) (!is_tx(crypto))
 
 #define key_next(cur) ((cur) % KEY_MAX + 1)
 
@@ -271,30 +325,55 @@ do {									\
 /**
  * tipc_aead_key_validate - Validate a AEAD user key
  */
-int tipc_aead_key_validate(struct tipc_aead_key *ukey)
+int tipc_aead_key_validate(struct tipc_aead_key *ukey, struct genl_info *info)
 {
 	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);
+		GENL_SET_ERR_MSG(info, "unable to load the algorithm (module existed?)");
 		return -ENODEV;
 	}
 
 	/* Currently, we only support the "gcm(aes)" cipher algorithm */
-	if (strcmp(ukey->alg_name, "gcm(aes)"))
+	if (strcmp(ukey->alg_name, "gcm(aes)")) {
+		GENL_SET_ERR_MSG(info, "not supported yet the algorithm");
 		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;
+		     keylen != TIPC_AES_GCM_KEY_SIZE_256)) {
+		GENL_SET_ERR_MSG(info, "incorrect key length (20, 28 or 36 octets?)");
+		return -EKEYREJECTED;
+	}
 
 	return 0;
 }
 
+/**
+ * tipc_aead_key_generate - Generate new session key
+ * @skey: input/output key with new content
+ *
+ * Return: 0 in case of success, otherwise < 0
+ */
+static int tipc_aead_key_generate(struct tipc_aead_key *skey)
+{
+	int rc = 0;
+
+	/* Fill the key's content with a random value via RNG cipher */
+	rc = crypto_get_default_rng();
+	if (likely(!rc)) {
+		rc = crypto_rng_get_bytes(crypto_default_rng, skey->key,
+					  skey->keylen);
+		crypto_put_default_rng();
+	}
+
+	return rc;
+}
+
 static struct tipc_aead *tipc_aead_get(struct tipc_aead __rcu *aead)
 {
 	struct tipc_aead *tmp;
@@ -339,6 +418,7 @@ static void tipc_aead_free(struct rcu_head *rp)
 		kfree(head);
 	}
 	free_percpu(aead->tfm_entry);
+	kzfree(aead->key);
 	kfree(aead);
 }
 
@@ -501,14 +581,15 @@ static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
 		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';
+	/* Form a hex string of some last bytes as the key's hint */
+	bin2hex(tmp->hint, ukey->key + keylen - TIPC_AEAD_HINT_LEN,
+		TIPC_AEAD_HINT_LEN);
 
 	/* Initialize the other data */
 	tmp->mode = mode;
 	tmp->cloned = NULL;
 	tmp->authsize = TIPC_AES_GCM_TAG_SIZE;
+	tmp->key = kmemdup(ukey, tipc_aead_key_size(ukey), GFP_KERNEL);
 	memcpy(&tmp->salt, ukey->key + keylen, TIPC_AES_GCM_SALT_SIZE);
 	atomic_set(&tmp->users, 0);
 	atomic64_set(&tmp->seqno, 0);
@@ -663,13 +744,11 @@ static int tipc_aead_encrypt(struct tipc_aead *aead, struct sk_buff *skb,
 	 * 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);
+		pr_debug("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;
@@ -940,8 +1019,6 @@ bool tipc_ehdr_validate(struct sk_buff *skb)
 		return false;
 	if (unlikely(skb->len <= ehsz + TIPC_AES_GCM_TAG_SIZE))
 		return false;
-	if (unlikely(!ehdr->tx_key))
-		return false;
 
 	return true;
 }
@@ -994,6 +1071,8 @@ static int tipc_ehdr_build(struct net *net, struct tipc_aead *aead,
 	ehdr->tx_key = tx_key;
 	ehdr->destined = (__rx) ? 1 : 0;
 	ehdr->rx_key_active = (__rx) ? __rx->key.active : 0;
+	ehdr->rx_nokey = (__rx) ? __rx->nokey : 0;
+	ehdr->master_key = aead->crypto->key_master;
 	ehdr->reserved_1 = 0;
 	ehdr->reserved_2 = 0;
 
@@ -1019,23 +1098,16 @@ static inline void tipc_crypto_key_set_state(struct tipc_crypto *c,
 					     u8 new_active,
 					     u8 new_pending)
 {
-#ifdef TIPC_CRYPTO_DEBUG
 	struct tipc_key old = c->key;
 	char buf[32];
-#endif
 
 	c->key.keys = ((new_passive & KEY_MASK) << (KEY_BITS * 2)) |
 		      ((new_active  & KEY_MASK) << (KEY_BITS)) |
 		      ((new_pending & KEY_MASK));
 
-#ifdef TIPC_CRYPTO_DEBUG
-	pr_info("%s(%s): key changing %s ::%pS\n",
-		(c->node) ? "RX" : "TX",
-		(c->node) ? tipc_node_get_id_str(c->node) :
-			    tipc_own_id_string(c->net),
-		tipc_key_change_dump(old, c->key, buf),
-		__builtin_return_address(0));
-#endif
+	pr_debug("%s: key changing %s ::%pS\n", c->name,
+		 tipc_key_change_dump(old, c->key, buf),
+		 __builtin_return_address(0));
 }
 
 /**
@@ -1043,6 +1115,7 @@ static inline void tipc_crypto_key_set_state(struct tipc_crypto *c,
  * @c: TIPC crypto to which new key is attached
  * @ukey: the user key
  * @mode: the key mode (CLUSTER_KEY or PER_NODE_KEY)
+ * @master_key: specify this is a cluster master key
  *
  * A new TIPC AEAD key will be allocated and initiated with the specified user
  * key, then attached to the TIPC crypto.
@@ -1050,7 +1123,7 @@ static inline void tipc_crypto_key_set_state(struct tipc_crypto *c,
  * Return: new key id in case of success, otherwise: < 0
  */
 int tipc_crypto_key_init(struct tipc_crypto *c, struct tipc_aead_key *ukey,
-			 u8 mode)
+			 u8 mode, bool master_key)
 {
 	struct tipc_aead *aead = NULL;
 	int rc = 0;
@@ -1060,17 +1133,11 @@ int tipc_crypto_key_init(struct tipc_crypto *c, struct tipc_aead_key *ukey,
 
 	/* Attach it to the crypto */
 	if (likely(!rc)) {
-		rc = tipc_crypto_key_attach(c, aead, 0);
+		rc = tipc_crypto_key_attach(c, aead, 0, master_key);
 		if (rc < 0)
 			tipc_aead_free(&aead->rcu);
 	}
 
-	pr_info("%s(%s): key initiating, rc %d!\n",
-		(c->node) ? "RX" : "TX",
-		(c->node) ? tipc_node_get_id_str(c->node) :
-			    tipc_own_id_string(c->net),
-		rc);
-
 	return rc;
 }
 
@@ -1079,58 +1146,58 @@ int tipc_crypto_key_init(struct tipc_crypto *c, struct tipc_aead_key *ukey,
  * @c: TIPC crypto to which the new AEAD key is attached
  * @aead: the new AEAD key pointer
  * @pos: desired slot in the crypto key array, = 0 if any!
+ * @master_key: specify this is a cluster master key
  *
  * Return: new key id in case of success, otherwise: -EBUSY
  */
 static int tipc_crypto_key_attach(struct tipc_crypto *c,
-				  struct tipc_aead *aead, u8 pos)
+				  struct tipc_aead *aead, u8 pos,
+				  bool master_key)
 {
-	u8 new_pending, new_passive, new_key;
 	struct tipc_key key;
 	int rc = -EBUSY;
+	u8 new_key;
 
 	spin_lock_bh(&c->lock);
 	key = c->key;
+	if (master_key) {
+		new_key = KEY_MASTER;
+		goto attach;
+	}
 	if (key.active && key.passive)
 		goto exit;
-	if (key.passive && !tipc_aead_users(c->aead[key.passive]))
-		goto exit;
 	if (key.pending) {
-		if (pos)
-			goto exit;
 		if (tipc_aead_users(c->aead[key.pending]) > 0)
 			goto exit;
+		/* if (pos): ok with replacing, will be aligned when needed */
 		/* Replace it */
-		new_pending = key.pending;
-		new_passive = key.passive;
-		new_key = new_pending;
+		new_key = key.pending;
 	} else {
 		if (pos) {
 			if (key.active && pos != key_next(key.active)) {
-				new_pending = key.pending;
-				new_passive = pos;
-				new_key = new_passive;
+				key.passive = pos;
+				new_key = pos;
 				goto attach;
 			} else if (!key.active && !key.passive) {
-				new_pending = pos;
-				new_passive = key.passive;
-				new_key = new_pending;
+				key.pending = pos;
+				new_key = pos;
 				goto attach;
 			}
 		}
-		new_pending = key_next(key.active ?: key.passive);
-		new_passive = key.passive;
-		new_key = new_pending;
+		key.pending = key_next(key.active ?: key.passive);
+		new_key = key.pending;
 	}
 
 attach:
 	aead->crypto = c;
-	tipc_crypto_key_set_state(c, new_passive, key.active, new_pending);
+	aead->gen = (is_tx(c)) ? ++c->key_gen : c->key_gen;
 	tipc_aead_rcu_replace(c->aead[new_key], aead, &c->lock);
-
+	if (likely(c->key.keys != key.keys))
+		tipc_crypto_key_set_state(c, key.passive, key.active,
+					  key.pending);
 	c->working = 1;
-	c->timer1 = jiffies;
-	c->timer2 = jiffies;
+	c->nokey = 0;
+	c->key_master |= master_key;
 	rc = new_key;
 
 exit:
@@ -1140,14 +1207,33 @@ exit:
 
 void tipc_crypto_key_flush(struct tipc_crypto *c)
 {
+	struct tipc_crypto *tx, *rx;
 	int k;
 
 	spin_lock_bh(&c->lock);
-	c->working = 0;
+	if (is_rx(c)) {
+		/* Try to cancel pending work */
+		rx = c;
+		tx = tipc_net(rx->net)->crypto_tx;
+		if (cancel_delayed_work(&rx->work)) {
+			kfree(rx->skey);
+			rx->skey = NULL;
+			atomic_xchg(&rx->key_distr, 0);
+			tipc_node_put(rx->node);
+		}
+		/* RX stopping => decrease TX key users if any */
+		k = atomic_xchg(&rx->peer_rx_active, 0);
+		if (k) {
+			tipc_aead_users_dec(tx->aead[k], 0);
+			/* Mark the point TX key users changed */
+			tx->timer1 = jiffies;
+		}
+	}
+
+	c->flags = 0;
 	tipc_crypto_key_set_state(c, 0, 0, 0);
 	for (k = KEY_MIN; k <= KEY_MAX; k++)
 		tipc_crypto_key_detach(c->aead[k], &c->lock);
-	atomic_set(&c->peer_rx_active, 0);
 	atomic64_set(&c->sndnxt, 0);
 	spin_unlock_bh(&c->lock);
 }
@@ -1206,7 +1292,8 @@ static bool tipc_crypto_key_try_align(struct tipc_crypto *rx, u8 new_pending)
 		rcu_assign_pointer(rx->aead[new_passive], tmp2);
 	refcount_set(&tmp1->refcnt, 1);
 	aligned = true;
-	pr_info("RX(%s): key is aligned!\n", tipc_node_get_id_str(rx->node));
+	pr_info_ratelimited("%s: key[%d] -> key[%d]\n", rx->name, key.pending,
+			    new_pending);
 
 exit:
 	spin_unlock(&rx->lock);
@@ -1218,6 +1305,7 @@ exit:
  * @tx: TX crypto handle
  * @rx: RX crypto handle (can be NULL)
  * @skb: the message skb which will be decrypted later
+ * @tx_key: peer TX key id
  *
  * This function looks up the existing TX keys and pick one which is suitable
  * for the message decryption, that must be a cluster key and not used before
@@ -1227,7 +1315,8 @@ exit:
  */
 static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
 						 struct tipc_crypto *rx,
-						 struct sk_buff *skb)
+						 struct sk_buff *skb,
+						 u8 tx_key)
 {
 	struct tipc_skb_cb *skb_cb = TIPC_SKB_CB(skb);
 	struct tipc_aead *aead = NULL;
@@ -1246,6 +1335,10 @@ static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
 
 	/* Pick one TX key */
 	spin_lock(&tx->lock);
+	if (tx_key == KEY_MASTER) {
+		aead = tipc_aead_rcu_ptr(tx->aead[KEY_MASTER], &tx->lock);
+		goto done;
+	}
 	do {
 		k = (i == 0) ? key.pending :
 			((i == 1) ? key.active : key.passive);
@@ -1265,9 +1358,12 @@ static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
 		skb->next = skb_clone(skb, GFP_ATOMIC);
 		if (unlikely(!skb->next))
 			pr_warn("Failed to clone skb for next round if any\n");
-		WARN_ON(!refcount_inc_not_zero(&aead->refcnt));
 		break;
 	} while (++i < 3);
+
+done:
+	if (likely(aead))
+		WARN_ON(!refcount_inc_not_zero(&aead->refcnt));
 	spin_unlock(&tx->lock);
 
 	return aead;
@@ -1276,53 +1372,73 @@ static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
 /**
  * tipc_crypto_key_synch: Synch own key data according to peer key status
  * @rx: RX crypto handle
- * @new_rx_active: latest RX active key from peer
- * @hdr: TIPCv2 message
+ * @skb: TIPCv2 message buffer (incl. the ehdr from peer)
  *
  * This function updates the peer node related data as the peer RX active key
  * has changed, so the number of TX keys' users on this node are increased and
  * decreased correspondingly.
  *
+ * It also considers if peer has no key, then we need to make own master key
+ * (if any) taking over i.e. starting grace period and also trigger key
+ * distributing process.
+ *
  * The "per-peer" sndnxt is also reset when the peer key has switched.
  */
-static void tipc_crypto_key_synch(struct tipc_crypto *rx, u8 new_rx_active,
-				  struct tipc_msg *hdr)
+static void tipc_crypto_key_synch(struct tipc_crypto *rx, struct sk_buff *skb)
 {
-	struct net *net = rx->net;
-	struct tipc_crypto *tx = tipc_net(net)->crypto_tx;
-	u8 cur_rx_active;
+	struct tipc_ehdr *ehdr = (struct tipc_ehdr *)skb_network_header(skb);
+	struct tipc_crypto *tx = tipc_net(rx->net)->crypto_tx;
+	struct tipc_msg *hdr = buf_msg(skb);
+	u32 self = tipc_own_addr(rx->net);
+	u8 cur, new;
+	unsigned long delay;
 
-	/* TX might be even not ready yet */
-	if (unlikely(!tx->key.active && !tx->key.pending))
-		return;
+	/* Update RX 'key_master' flag according to peer, also mark "legacy" if
+	 * a peer has no master key.
+	 */
+	rx->key_master = ehdr->master_key;
+	if (!rx->key_master)
+		tx->legacy_user = 1;
 
-	cur_rx_active = atomic_read(&rx->peer_rx_active);
-	if (likely(cur_rx_active == new_rx_active))
+	/* For later cases, apply only if message is destined to this node */
+	if (!ehdr->destined || msg_short(hdr) || msg_destnode(hdr) != self)
 		return;
 
-	/* Make sure this message destined for this node */
-	if (unlikely(msg_short(hdr) ||
-		     msg_destnode(hdr) != tipc_own_addr(net)))
-		return;
+	/* Case 1: Peer has no keys, let's make master key take over */
+	if (ehdr->rx_nokey) {
+		/* Set or extend grace period */
+		tx->timer2 = jiffies;
+		/* Schedule key distributing for the peer if not yet */
+		if (tx->key.keys &&
+		    !atomic_cmpxchg(&rx->key_distr, 0, KEY_DISTR_SCHED)) {
+			get_random_bytes(&delay, 2);
+			delay %= 5;
+			delay = msecs_to_jiffies(500 * ++delay);
+			if (queue_delayed_work(tx->wq, &rx->work, delay))
+				tipc_node_get(rx->node);
+		}
+	} else {
+		/* Cancel a pending key distributing if any */
+		atomic_xchg(&rx->key_distr, 0);
+	}
 
-	/* Peer RX active key has changed, try to update owns' & TX users */
-	if (atomic_cmpxchg(&rx->peer_rx_active,
-			   cur_rx_active,
-			   new_rx_active) == cur_rx_active) {
-		if (new_rx_active)
-			tipc_aead_users_inc(tx->aead[new_rx_active], INT_MAX);
-		if (cur_rx_active)
-			tipc_aead_users_dec(tx->aead[cur_rx_active], 0);
+	/* Case 2: Peer RX active key has changed, let's update own TX users */
+	cur = atomic_read(&rx->peer_rx_active);
+	new = ehdr->rx_key_active;
+	if (tx->key.keys &&
+	    cur != new &&
+	    atomic_cmpxchg(&rx->peer_rx_active, cur, new) == cur) {
+		if (new)
+			tipc_aead_users_inc(tx->aead[new], INT_MAX);
+		if (cur)
+			tipc_aead_users_dec(tx->aead[cur], 0);
 
 		atomic64_set(&rx->sndnxt, 0);
 		/* Mark the point TX key users changed */
 		tx->timer1 = jiffies;
 
-#ifdef TIPC_CRYPTO_DEBUG
-		pr_info("TX(%s): key users changed %d-- %d++, peer RX(%s)\n",
-			tipc_own_id_string(net), cur_rx_active,
-			new_rx_active, tipc_node_get_id_str(rx->node));
-#endif
+		pr_debug("%s: key users changed %d-- %d++, peer %s\n",
+			 tx->name, cur, new, rx->name);
 	}
 }
 
@@ -1340,7 +1456,7 @@ static int tipc_crypto_key_revoke(struct net *net, u8 tx_key)
 	tipc_crypto_key_detach(tx->aead[key.active], &tx->lock);
 	spin_unlock(&tx->lock);
 
-	pr_warn("TX(%s): key is revoked!\n", tipc_own_id_string(net));
+	pr_warn("%s: key is revoked\n", tx->name);
 	return -EKEYREVOKED;
 }
 
@@ -1357,6 +1473,15 @@ int tipc_crypto_start(struct tipc_crypto **crypto, struct net *net,
 	if (!c)
 		return -ENOMEM;
 
+	/* Allocate workqueue on TX */
+	if (!node) {
+		c->wq = alloc_ordered_workqueue("tipc_crypto", 0);
+		if (!c->wq) {
+			kfree(c);
+			return -ENOMEM;
+		}
+	}
+
 	/* Allocate statistic structure */
 	c->stats = alloc_percpu_gfp(struct tipc_crypto_stats, GFP_ATOMIC);
 	if (!c->stats) {
@@ -1364,53 +1489,52 @@ int tipc_crypto_start(struct tipc_crypto **crypto, struct net *net,
 		return -ENOMEM;
 	}
 
-	c->working = 0;
+	c->flags = 0;
 	c->net = net;
 	c->node = node;
+	get_random_bytes(&c->key_gen, 2);
 	tipc_crypto_key_set_state(c, 0, 0, 0);
+	atomic_set(&c->key_distr, 0);
 	atomic_set(&c->peer_rx_active, 0);
 	atomic64_set(&c->sndnxt, 0);
 	c->timer1 = jiffies;
 	c->timer2 = jiffies;
+	c->rekeying_intv = TIPC_REKEYING_INTV_DEF;
 	spin_lock_init(&c->lock);
-	*crypto = c;
+	scnprintf(c->name, 48, "%s(%s)", (is_rx(c)) ? "RX" : "TX",
+		  (is_rx(c)) ? tipc_node_get_id_str(c->node) :
+			       tipc_own_id_string(c->net));
+
+	if (is_rx(c))
+		INIT_DELAYED_WORK(&c->work, tipc_crypto_work_rx);
+	else
+		INIT_DELAYED_WORK(&c->work, tipc_crypto_work_tx);
 
+	*crypto = c;
 	return 0;
 }
 
 void tipc_crypto_stop(struct tipc_crypto **crypto)
 {
-	struct tipc_crypto *c, *tx, *rx;
-	bool is_rx;
+	struct tipc_crypto *c = *crypto;
 	u8 k;
 
-	if (!*crypto)
+	if (!c)
 		return;
 
-	rcu_read_lock();
-	/* RX stopping? => decrease TX key users if any */
-	is_rx = !!((*crypto)->node);
-	if (is_rx) {
-		rx = *crypto;
-		tx = tipc_net(rx->net)->crypto_tx;
-		k = atomic_read(&rx->peer_rx_active);
-		if (k) {
-			tipc_aead_users_dec(tx->aead[k], 0);
-			/* Mark the point TX key users changed */
-			tx->timer1 = jiffies;
-		}
+	/* Flush any queued works & destroy wq */
+	if (is_tx(c)) {
+		c->rekeying_intv = 0;
+		cancel_delayed_work_sync(&c->work);
+		destroy_workqueue(c->wq);
 	}
 
 	/* Release AEAD keys */
-	c = *crypto;
+	rcu_read_lock();
 	for (k = KEY_MIN; k <= KEY_MAX; k++)
 		tipc_aead_put(rcu_dereference(c->aead[k]));
 	rcu_read_unlock();
-
-	pr_warn("%s(%s) has been purged, node left!\n",
-		(is_rx) ? "RX" : "TX",
-		(is_rx) ? tipc_node_get_id_str((*crypto)->node) :
-			  tipc_own_id_string((*crypto)->net));
+	pr_debug("%s: has been stopped\n", c->name);
 
 	/* Free this crypto statistics */
 	free_percpu(c->stats);
@@ -1424,106 +1548,91 @@ void tipc_crypto_timeout(struct tipc_crypto *rx)
 	struct tipc_net *tn = tipc_net(rx->net);
 	struct tipc_crypto *tx = tn->crypto_tx;
 	struct tipc_key key;
-	u8 new_pending, new_passive;
 	int cmd;
 
-	/* TX key activating:
-	 * The pending key (users > 0) -> active
-	 * The active key if any (users == 0) -> free
-	 */
+	/* TX pending: taking all users & stable -> active */
 	spin_lock(&tx->lock);
 	key = tx->key;
 	if (key.active && tipc_aead_users(tx->aead[key.active]) > 0)
 		goto s1;
 	if (!key.pending || tipc_aead_users(tx->aead[key.pending]) <= 0)
 		goto s1;
-	if (time_before(jiffies, tx->timer1 + TIPC_TX_LASTING_LIM))
+	if (time_before(jiffies, tx->timer1 + TIPC_TX_LASTING_TIME))
 		goto s1;
 
 	tipc_crypto_key_set_state(tx, key.passive, key.pending, 0);
 	if (key.active)
 		tipc_crypto_key_detach(tx->aead[key.active], &tx->lock);
 	this_cpu_inc(tx->stats->stat[STAT_SWITCHES]);
-	pr_info("TX(%s): key %d is activated!\n", tipc_own_id_string(tx->net),
-		key.pending);
+	pr_info("%s: key[%d] is activated\n", tx->name, key.pending);
 
 s1:
 	spin_unlock(&tx->lock);
 
-	/* RX key activating:
-	 * The pending key (users > 0) -> active
-	 * The active key if any -> passive, freed later
-	 */
+	/* RX pending: having user -> active */
 	spin_lock(&rx->lock);
 	key = rx->key;
 	if (!key.pending || tipc_aead_users(rx->aead[key.pending]) <= 0)
 		goto s2;
 
-	new_pending = (key.passive &&
-		       !tipc_aead_users(rx->aead[key.passive])) ?
-				       key.passive : 0;
-	new_passive = (key.active) ?: ((new_pending) ? 0 : key.passive);
-	tipc_crypto_key_set_state(rx, new_passive, key.pending, new_pending);
+	if (key.active)
+		key.passive = key.active;
+	key.active = key.pending;
+	rx->timer2 = jiffies;
+	tipc_crypto_key_set_state(rx, key.passive, key.active, 0);
 	this_cpu_inc(rx->stats->stat[STAT_SWITCHES]);
-	pr_info("RX(%s): key %d is activated!\n",
-		tipc_node_get_id_str(rx->node),	key.pending);
+	pr_info("%s: key[%d] is activated\n", rx->name, key.pending);
 	goto s5;
 
 s2:
-	/* RX key "faulty" switching:
-	 * The faulty pending key (users < -30) -> passive
-	 * The passive key (users = 0) -> pending
-	 * Note: This only happens after RX deactivated - s3!
-	 */
-	key = rx->key;
-	if (!key.pending || tipc_aead_users(rx->aead[key.pending]) > -30)
-		goto s3;
-	if (!key.passive || tipc_aead_users(rx->aead[key.passive]) != 0)
+	/* RX pending: not working -> remove */
+	if (!key.pending || tipc_aead_users(rx->aead[key.pending]) > -10)
 		goto s3;
 
-	new_pending = key.passive;
-	new_passive = key.pending;
-	tipc_crypto_key_set_state(rx, new_passive, key.active, new_pending);
+	tipc_crypto_key_set_state(rx, key.passive, key.active, 0);
+	tipc_crypto_key_detach(rx->aead[key.pending], &rx->lock);
+	pr_debug("%s: key[%d] is removed\n", rx->name, key.pending);
 	goto s5;
 
 s3:
-	/* RX key deactivating:
-	 * The passive key if any -> pending
-	 * The active key -> passive (users = 0) / pending
-	 * The pending key if any -> passive (users = 0)
-	 */
-	key = rx->key;
+	/* RX active: timed out or no user -> pending */
 	if (!key.active)
 		goto s4;
-	if (time_before(jiffies, rx->timer1 + TIPC_RX_ACTIVE_LIM))
+	if (time_before(jiffies, rx->timer1 + TIPC_RX_ACTIVE_LIM) &&
+	    tipc_aead_users(rx->aead[key.active]) > 0)
 		goto s4;
 
-	new_pending = (key.passive) ?: key.active;
-	new_passive = (key.passive) ? key.active : key.pending;
-	tipc_aead_users_set(rx->aead[new_pending], 0);
-	if (new_passive)
-		tipc_aead_users_set(rx->aead[new_passive], 0);
-	tipc_crypto_key_set_state(rx, new_passive, 0, new_pending);
-	pr_info("RX(%s): key %d is deactivated!\n",
-		tipc_node_get_id_str(rx->node), key.active);
+	if (key.pending)
+		key.passive = key.active;
+	else
+		key.pending = key.active;
+	rx->timer2 = jiffies;
+	tipc_crypto_key_set_state(rx, key.passive, 0, key.pending);
+	tipc_aead_users_set(rx->aead[key.pending], 0);
+	pr_debug("%s: key[%d] is deactivated\n", rx->name, key.active);
 	goto s5;
 
 s4:
-	/* RX key passive -> freed: */
-	key = rx->key;
-	if (!key.passive || !tipc_aead_users(rx->aead[key.passive]))
+	/* RX passive: outdated or not working -> free */
+	if (!key.passive)
 		goto s5;
-	if (time_before(jiffies, rx->timer2 + TIPC_RX_PASSIVE_LIM))
+	if (time_before(jiffies, rx->timer2 + TIPC_RX_PASSIVE_LIM) &&
+	    tipc_aead_users(rx->aead[key.passive]) > -10)
 		goto s5;
 
 	tipc_crypto_key_set_state(rx, 0, key.active, key.pending);
 	tipc_crypto_key_detach(rx->aead[key.passive], &rx->lock);
-	pr_info("RX(%s): key %d is freed!\n", tipc_node_get_id_str(rx->node),
-		key.passive);
+	pr_debug("%s: key[%d] is freed\n", rx->name, key.passive);
 
 s5:
 	spin_unlock(&rx->lock);
 
+	/* Relax it here, the flag will be set again if it really is, but only
+	 * when we are not in grace period for safety!
+	 */
+	if (time_after(jiffies, tx->timer2 + TIPC_TX_GRACE_PERIOD))
+		tx->legacy_user = 0;
+
 	/* Limit max_tfms & do debug commands if needed */
 	if (likely(sysctl_tipc_max_tfms <= TIPC_MAX_TFMS_LIM))
 		return;
@@ -1533,6 +1642,22 @@ s5:
 	tipc_crypto_do_cmd(rx->net, cmd);
 }
 
+static inline void tipc_crypto_clone_msg(struct net *net, struct sk_buff *_skb,
+					 struct tipc_bearer *b,
+					 struct tipc_media_addr *dst,
+					 struct tipc_node *__dnode, u8 type)
+{
+	struct sk_buff *skb;
+
+	skb = skb_clone(_skb, GFP_ATOMIC);
+	if (skb) {
+		TIPC_SKB_CB(skb)->xmit_type = type;
+		tipc_crypto_xmit(net, &skb, b, dst, __dnode);
+		if (skb)
+			b->media->send_msg(net, skb, b, dst);
+	}
+}
+
 /**
  * tipc_crypto_xmit - Build & encrypt TIPC message for xmit
  * @net: struct net
@@ -1542,7 +1667,8 @@ s5:
  * @__dnode: destination node for reference if any
  *
  * First, build an encryption message header on the top of the message, then
- * encrypt the original TIPC message by using the active or pending TX key.
+ * encrypt the original TIPC message by using the pending, master or active
+ * key with this preference order.
  * If the encryption is successful, the encrypted skb is returned directly or
  * via the callback.
  * Otherwise, the skb is freed!
@@ -1562,46 +1688,67 @@ int tipc_crypto_xmit(struct net *net, struct sk_buff **skb,
 	struct tipc_crypto *__rx = tipc_node_crypto_rx(__dnode);
 	struct tipc_crypto *tx = tipc_net(net)->crypto_tx;
 	struct tipc_crypto_stats __percpu *stats = tx->stats;
+	struct tipc_msg *hdr = buf_msg(*skb);
 	struct tipc_key key = tx->key;
 	struct tipc_aead *aead = NULL;
-	struct sk_buff *probe;
+	u32 user = msg_user(hdr);
+	u32 type = msg_type(hdr);
 	int rc = -ENOKEY;
-	u8 tx_key;
+	u8 tx_key = 0;
 
 	/* No encryption? */
 	if (!tx->working)
 		return 0;
 
-	/* Try with the pending key if available and:
-	 * 1) This is the only choice (i.e. no active key) or;
-	 * 2) Peer has switched to this key (unicast only) or;
-	 * 3) It is time to do a pending key probe;
-	 */
+	/* Pending key if peer has active on it or probing time */
 	if (unlikely(key.pending)) {
 		tx_key = key.pending;
-		if (!key.active)
+		if (!tx->key_master && !key.active)
 			goto encrypt;
 		if (__rx && atomic_read(&__rx->peer_rx_active) == tx_key)
 			goto encrypt;
-		if (TIPC_SKB_CB(*skb)->probe)
+		if (TIPC_SKB_CB(*skb)->xmit_type == SKB_PROBING) {
+			pr_debug("%s: probing for key[%d]\n", tx->name,
+				 key.pending);
+			goto encrypt;
+		}
+		if (user == LINK_CONFIG || user == LINK_PROTOCOL)
+			tipc_crypto_clone_msg(net, *skb, b, dst, __dnode,
+					      SKB_PROBING);
+	}
+
+	/* Master key if this is a *vital* message or in grace period */
+	if (tx->key_master) {
+		tx_key = KEY_MASTER;
+		if (!key.active)