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* [net-next 0/4] tipc: add more features to TIPC encryption
@ 2020-08-29 19:41 Tuong Lien
  2020-08-29 19:41 ` [net-next 1/4] tipc: optimize key switching time and logic Tuong Lien
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Tuong Lien @ 2020-08-29 19:41 UTC (permalink / raw)
  To: davem, jmaloy, maloy, ying.xue, netdev; +Cc: tipc-discussion

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.

Tuong Lien (4):
  tipc: optimize key switching time and logic
  tipc: introduce encryption master key
  tipc: add automatic session key exchange
  tipc: add automatic rekeying for encryption key

 include/uapi/linux/tipc.h         |   2 +
 include/uapi/linux/tipc_netlink.h |   2 +
 net/tipc/crypto.c                 | 974 ++++++++++++++++++++++--------
 net/tipc/crypto.h                 |  41 +-
 net/tipc/link.c                   |   5 +
 net/tipc/msg.h                    |   8 +-
 net/tipc/netlink.c                |   2 +
 net/tipc/node.c                   |  89 ++-
 net/tipc/node.h                   |   2 +
 net/tipc/sysctl.c                 |   9 +
 10 files changed, 851 insertions(+), 283 deletions(-)

-- 
2.26.2


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [net-next 1/4] tipc: optimize key switching time and logic
  2020-08-29 19:41 [net-next 0/4] tipc: add more features to TIPC encryption Tuong Lien
@ 2020-08-29 19:41 ` Tuong Lien
  2020-08-29 19:41 ` [net-next 2/4] tipc: introduce encryption master key Tuong Lien
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 6+ messages in thread
From: Tuong Lien @ 2020-08-29 19:41 UTC (permalink / raw)
  To: davem, jmaloy, maloy, ying.xue, netdev; +Cc: tipc-discussion

We reduce the lasting time for a pending TX key to be active as well as
for a passive RX key to be freed which generally helps speed up the key
switching. It is not expected to be too fast but should not be too slow
either. Also the key handling logic is simplified that a pending RX key
will be removed automatically if it is found not working after a number
of times; the probing for a pending TX key is now carried on a specific
message user ('LINK_PROTOCOL' or 'LINK_CONFIG') which is more efficient
than using a timer on broadcast messages, the timer is reserved for use
later as needed.

The kernel logs or 'pr***()' are now made as clear as possible to user.
Some prints are added, removed or changed to the debug-level. The
'TIPC_CRYPTO_DEBUG' definition is removed, and the 'pr_debug()' is used
instead which will be much helpful in runtime.

Besides we also optimize the code in some other places as a preparation
for later commits.

This commit does not change the en/decryption functionalities.

Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
---
 net/tipc/crypto.c | 344 +++++++++++++++++++---------------------------
 1 file changed, 141 insertions(+), 203 deletions(-)

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 7c523dc81575..53a3b34b3913 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -38,10 +38,10 @@
 #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_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
 
@@ -144,7 +144,7 @@ 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;
 
 	atomic64_t seqno ____cacheline_aligned;
@@ -168,9 +168,10 @@ struct tipc_crypto_stats {
  * @key: the key states
  * @working: the crypto is working or not
  * @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)
  * @lock: tipc_key lock
  */
 struct tipc_crypto {
@@ -181,6 +182,7 @@ struct tipc_crypto {
 	struct tipc_key key;
 	u8 working:1;
 	struct tipc_crypto_stats __percpu *stats;
+	char name[48];
 
 	atomic64_t sndnxt ____cacheline_aligned;
 	unsigned long timer1;
@@ -239,18 +241,17 @@ 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 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 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 is_tx(crypto) (!(crypto)->node)
+#define is_rx(crypto) (!is_tx(crypto))
 
 #define key_next(cur) ((cur) % KEY_MAX + 1)
 
@@ -290,7 +291,7 @@ int tipc_aead_key_validate(struct tipc_aead_key *ukey)
 	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 -EKEYREJECTED;
 
 	return 0;
 }
@@ -501,9 +502,9 @@ 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;
@@ -663,13 +664,11 @@ 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;
@@ -1019,23 +1018,16 @@ 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));
 }
 
 /**
@@ -1057,20 +1049,20 @@ int tipc_crypto_key_init(struct tipc_crypto *c, struct tipc_aead_key *ukey,
 
 	/* Initiate with the new user key */
 	rc = tipc_aead_init(&aead, ukey, mode);
+	if (unlikely(rc)) {
+		pr_err("%s: unable to init key, err %d\n", c->name, rc);
+		return rc;
+	}
 
 	/* Attach it to the crypto */
-	if (likely(!rc)) {
-		rc = tipc_crypto_key_attach(c, aead, 0);
-		if (rc < 0)
-			tipc_aead_free(&aead->rcu);
+	rc = tipc_crypto_key_attach(c, aead, 0);
+	if (rc < 0) {
+		pr_err("%s: unable to attach key, err %d\n", c->name, rc);
+		tipc_aead_free(&aead->rcu);
+		return rc;
 	}
 
-	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);
-
+	pr_info("%s: key[%d] is successfully attached\n", c->name, rc);
 	return rc;
 }
 
@@ -1085,49 +1077,42 @@ int tipc_crypto_key_init(struct tipc_crypto *c, struct tipc_aead_key *ukey,
 static int tipc_crypto_key_attach(struct tipc_crypto *c,
 				  struct tipc_aead *aead, u8 pos)
 {
-	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 (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);
 	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;
@@ -1206,7 +1191,8 @@ 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);
@@ -1276,8 +1262,7 @@ 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
@@ -1285,44 +1270,35 @@ static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
  *
  * 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;
-
-	/* TX might be even not ready yet */
-	if (unlikely(!tx->key.active && !tx->key.pending))
-		return;
-
-	cur_rx_active = atomic_read(&rx->peer_rx_active);
-	if (likely(cur_rx_active == new_rx_active))
-		return;
+	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;
 
-	/* Make sure this message destined for this node */
-	if (unlikely(msg_short(hdr) ||
-		     msg_destnode(hdr) != tipc_own_addr(net)))
+	/* Ensure this message is destined to us first */
+	if (!ehdr->destined || msg_short(hdr) || msg_destnode(hdr) != self)
 		return;
 
-	/* 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);
+	/* 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 +1316,7 @@ 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;
 }
 
@@ -1373,25 +1349,26 @@ int tipc_crypto_start(struct tipc_crypto **crypto, struct net *net,
 	c->timer1 = jiffies;
 	c->timer2 = jiffies;
 	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));
 
+	*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, *tx, *rx;
 	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;
+	if (is_rx(c)) {
+		rx = c;
 		tx = tipc_net(rx->net)->crypto_tx;
 		k = atomic_read(&rx->peer_rx_active);
 		if (k) {
@@ -1402,15 +1379,10 @@ void tipc_crypto_stop(struct tipc_crypto **crypto)
 	}
 
 	/* Release AEAD keys */
-	c = *crypto;
 	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);
@@ -1424,102 +1396,81 @@ 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_info("%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_info("%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_info("%s: key[%d] is freed\n", rx->name, key.passive);
 
 s5:
 	spin_unlock(&rx->lock);
@@ -1562,10 +1513,12 @@ 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;
+	struct sk_buff *_skb;
 	int rc = -ENOKEY;
+	u32 user = msg_user(hdr);
 	u8 tx_key;
 
 	/* No encryption? */
@@ -1583,17 +1536,18 @@ int tipc_crypto_xmit(struct net *net, struct sk_buff **skb,
 			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)->probe) {
+			pr_debug("%s: probing for key[%d]\n", tx->name,
+				 key.pending);
 			goto encrypt;
-		if (!__rx &&
-		    time_after(jiffies, tx->timer2 + TIPC_TX_PROBE_LIM)) {
-			tx->timer2 = jiffies;
-			probe = skb_clone(*skb, GFP_ATOMIC);
-			if (probe) {
-				TIPC_SKB_CB(probe)->probe = 1;
-				tipc_crypto_xmit(net, &probe, b, dst, __dnode);
-				if (probe)
-					b->media->send_msg(net, probe, b, dst);
+		}
+		if (user == LINK_CONFIG || user == LINK_PROTOCOL) {
+			_skb = skb_clone(*skb, GFP_ATOMIC);
+			if (_skb) {
+				TIPC_SKB_CB(_skb)->probe = 1;
+				tipc_crypto_xmit(net, &_skb, b, dst, __dnode);
+				if (_skb)
+					b->media->send_msg(net, _skb, b, dst);
 			}
 		}
 	}
@@ -1675,22 +1629,12 @@ int tipc_crypto_rcv(struct net *net, struct tipc_crypto *rx,
 	if (unlikely(!rx))
 		goto pick_tx;
 
-	/* Pick RX key according to TX key, three cases are possible:
-	 * 1) The current active key (likely) or;
-	 * 2) The pending (new or deactivated) key (if any) or;
-	 * 3) The passive or old active key (i.e. users > 0);
-	 */
 	tx_key = ((struct tipc_ehdr *)(*skb)->data)->tx_key;
+	/* Pick RX key according to TX key if any */
 	key = rx->key;
-	if (likely(tx_key == key.active))
+	if (tx_key == key.active || tx_key == key.pending ||
+	    tx_key == key.passive)
 		goto decrypt;
-	if (tx_key == key.pending)
-		goto decrypt;
-	if (tx_key == key.passive) {
-		rx->timer2 = jiffies;
-		if (tipc_aead_users(rx->aead[key.passive]) > 0)
-			goto decrypt;
-	}
 
 	/* Unknown key, let's try to align RX key(s) */
 	if (tipc_crypto_key_try_align(rx, tx_key))
@@ -1749,21 +1693,17 @@ static void tipc_crypto_rcv_complete(struct net *net, struct tipc_aead *aead,
 	struct tipc_aead *tmp = NULL;
 	struct tipc_ehdr *ehdr;
 	struct tipc_node *n;
-	u8 rx_key_active;
-	bool destined;
 
 	/* Is this completed by TX? */
-	if (unlikely(!rx->node)) {
+	if (unlikely(is_tx(aead->crypto))) {
 		rx = skb_cb->tx_clone_ctx.rx;
-#ifdef TIPC_CRYPTO_DEBUG
-		pr_info("TX->RX(%s): err %d, aead %p, skb->next %p, flags %x\n",
-			(rx) ? tipc_node_get_id_str(rx->node) : "-", err, aead,
-			(*skb)->next, skb_cb->flags);
-		pr_info("skb_cb [recurs %d, last %p], tx->aead [%p %p %p]\n",
-			skb_cb->tx_clone_ctx.recurs, skb_cb->tx_clone_ctx.last,
-			aead->crypto->aead[1], aead->crypto->aead[2],
-			aead->crypto->aead[3]);
-#endif
+		pr_debug("TX->RX(%s): err %d, aead %p, skb->next %p, flags %x\n",
+			 (rx) ? tipc_node_get_id_str(rx->node) : "-", err, aead,
+			 (*skb)->next, skb_cb->flags);
+		pr_debug("skb_cb [recurs %d, last %p], tx->aead [%p %p %p]\n",
+			 skb_cb->tx_clone_ctx.recurs, skb_cb->tx_clone_ctx.last,
+			 aead->crypto->aead[1], aead->crypto->aead[2],
+			 aead->crypto->aead[3]);
 		if (unlikely(err)) {
 			if (err == -EBADMSG && (*skb)->next)
 				tipc_rcv(net, (*skb)->next, b);
@@ -1784,9 +1724,6 @@ static void tipc_crypto_rcv_complete(struct net *net, struct tipc_aead *aead,
 				goto free_skb;
 		}
 
-		/* Skip cloning this time as we had a RX pending key */
-		if (rx->key.pending)
-			goto rcv;
 		if (tipc_aead_clone(&tmp, aead) < 0)
 			goto rcv;
 		if (tipc_crypto_key_attach(rx, tmp, ehdr->tx_key) < 0) {
@@ -1811,8 +1748,12 @@ static void tipc_crypto_rcv_complete(struct net *net, struct tipc_aead *aead,
 
 	/* Remove ehdr & auth. tag prior to tipc_rcv() */
 	ehdr = (struct tipc_ehdr *)(*skb)->data;
-	destined = ehdr->destined;
-	rx_key_active = ehdr->rx_key_active;
+
+	/* Mark this point, RX passive still works */
+	if (rx->key.passive && ehdr->tx_key == rx->key.passive)
+		rx->timer2 = jiffies;
+
+	skb_reset_network_header(*skb);
 	skb_pull(*skb, tipc_ehdr_size(ehdr));
 	pskb_trim(*skb, (*skb)->len - aead->authsize);
 
@@ -1822,9 +1763,8 @@ static void tipc_crypto_rcv_complete(struct net *net, struct tipc_aead *aead,
 		goto free_skb;
 	}
 
-	/* Update peer RX active key & TX users */
-	if (destined)
-		tipc_crypto_key_synch(rx, rx_key_active, buf_msg(*skb));
+	/* Ok, everything's fine, try to synch own keys according to peers' */
+	tipc_crypto_key_synch(rx, *skb);
 
 	/* Mark skb decrypted */
 	skb_cb->decrypted = 1;
@@ -1883,7 +1823,7 @@ static void tipc_crypto_do_cmd(struct net *net, int cmd)
 	/* Print crypto statistics */
 	for (i = 0, j = 0; i < MAX_STATS; i++)
 		j += scnprintf(buf + j, 200 - j, "|%11s ", hstats[i]);
-	pr_info("\nCounter     %s", buf);
+	pr_info("Counter     %s", buf);
 
 	memset(buf, '-', 115);
 	buf[115] = '\0';
@@ -1941,7 +1881,7 @@ static char *tipc_crypto_key_dump(struct tipc_crypto *c, char *buf)
 		aead = rcu_dereference(c->aead[k]);
 		if (aead)
 			i += scnprintf(buf + i, 200 - i,
-				       "{\"%s...\", \"%s\"}/%d:%d",
+				       "{\"0x...%s\", \"%s\"}/%d:%d",
 				       aead->hint,
 				       (aead->mode == CLUSTER_KEY) ? "c" : "p",
 				       atomic_read(&aead->users),
@@ -1950,14 +1890,13 @@ static char *tipc_crypto_key_dump(struct tipc_crypto *c, char *buf)
 		i += scnprintf(buf + i, 200 - i, "\n");
 	}
 
-	if (c->node)
+	if (is_rx(c))
 		i += scnprintf(buf + i, 200 - i, "\tPeer RX active: %d\n",
 			       atomic_read(&c->peer_rx_active));
 
 	return buf;
 }
 
-#ifdef TIPC_CRYPTO_DEBUG
 static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
 				  char *buf)
 {
@@ -1988,4 +1927,3 @@ static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
 	i += scnprintf(buf + i, 32 - i, "]");
 	return buf;
 }
-#endif
-- 
2.26.2


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [net-next 2/4] tipc: introduce encryption master key
  2020-08-29 19:41 [net-next 0/4] tipc: add more features to TIPC encryption Tuong Lien
  2020-08-29 19:41 ` [net-next 1/4] tipc: optimize key switching time and logic Tuong Lien
@ 2020-08-29 19:41 ` Tuong Lien
  2020-08-29 19:41 ` [net-next 3/4] tipc: add automatic session key exchange Tuong Lien
  2020-08-29 19:41 ` [net-next 4/4] tipc: add automatic rekeying for encryption key Tuong Lien
  3 siblings, 0 replies; 6+ messages in thread
From: Tuong Lien @ 2020-08-29 19:41 UTC (permalink / raw)
  To: davem, jmaloy, maloy, ying.xue, netdev; +Cc: tipc-discussion

In addition to the supported cluster & per-node encryption keys for the
en/decryption of TIPC messages, we now introduce one option for user to
set a cluster key as 'master key', which is simply a symmetric key like
the former but has a longer life cycle. It has two purposes:

- Authentication of new member nodes in the cluster. New nodes, having
  no knowledge of current session keys in the cluster will still be
  able to join the cluster as long as they know the master key. This is
  because all neighbor discovery (LINK_CONFIG) messages must be
  encrypted with this key.

- Encryption of session encryption keys during automatic exchange and
  update of those.This is a feature we will introduce in a later commit
  in this series.

We insert the new key into the currently unused slot 0 in the key array
and start using it immediately once the user has set it.
After joining, a node only knowing the master key should be fully
communicable to existing nodes in the cluster, although those nodes may
have their own session keys activated (i.e. not the master one). To
support this, we define a 'grace period', starting from the time a node
itself reports having no RX keys, so the existing nodes will use the
master key for encryption instead. The grace period can be extended but
will automatically stop after e.g. 5 seconds without a new report. This
is also the basis for later key exchanging feature as the new node will
be impossible to decrypt anything without the support from master key.

For user to set a master key, we define a new netlink flag -
'TIPC_NLA_NODE_KEY_MASTER', so it can be added to the current 'set key'
netlink command to specify the setting key to be a master key.

Above all, the traditional cluster/per-node key mechanism is guaranteed
to work when user comes not to use this master key option. This is also
compatible to legacy nodes without the feature supported.

Even this master key can be updated without any interruption of cluster
connectivity but is so is needed, this has to be coordinated and set by
the user.

Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
---
 include/uapi/linux/tipc_netlink.h |   1 +
 net/tipc/crypto.c                 | 206 ++++++++++++++++++++++--------
 net/tipc/crypto.h                 |  15 ++-
 net/tipc/msg.h                    |   4 +-
 net/tipc/netlink.c                |   1 +
 net/tipc/node.c                   |  46 +++----
 6 files changed, 189 insertions(+), 84 deletions(-)

diff --git a/include/uapi/linux/tipc_netlink.h b/include/uapi/linux/tipc_netlink.h
index dc0d23a50e69..d484baa9d365 100644
--- a/include/uapi/linux/tipc_netlink.h
+++ b/include/uapi/linux/tipc_netlink.h
@@ -165,6 +165,7 @@ 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_MAX,
 	TIPC_NLA_NODE_MAX = __TIPC_NLA_NODE_MAX - 1
diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 53a3b34b3913..b75b817441e5 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -38,6 +38,7 @@
 #include <crypto/aes.h>
 #include "crypto.h"
 
+#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(15000) /* 15s */
@@ -49,9 +50,9 @@
  * 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,
@@ -166,27 +167,36 @@ struct tipc_crypto_stats {
  * @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
  * @name: the crypto name
  * @sndnxt: the per-peer sndnxt (TX)
  * @timer1: 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.)
  * @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;
 	struct tipc_key key;
-	u8 working:1;
 	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 flags;
+	};
 	spinlock_t lock; /* crypto lock */
 
 } ____cacheline_aligned;
@@ -236,13 +246,19 @@ 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);
+						 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);
@@ -939,8 +955,6 @@ 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;
 }
@@ -993,6 +1007,8 @@ 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->key.keys : 0;
+	ehdr->master_key = aead->crypto->key_master;
 	ehdr->reserved_1 = 0;
 	ehdr->reserved_2 = 0;
 
@@ -1035,6 +1051,7 @@ 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.
@@ -1042,7 +1059,7 @@ 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;
@@ -1055,7 +1072,7 @@ int tipc_crypto_key_init(struct tipc_crypto *c, struct tipc_aead_key *ukey,
 	}
 
 	/* Attach it to the crypto */
-	rc = tipc_crypto_key_attach(c, aead, 0);
+	rc = tipc_crypto_key_attach(c, aead, 0, master_key);
 	if (rc < 0) {
 		pr_err("%s: unable to attach key, err %d\n", c->name, rc);
 		tipc_aead_free(&aead->rcu);
@@ -1071,11 +1088,13 @@ 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)
 {
 	struct tipc_key key;
 	int rc = -EBUSY;
@@ -1083,6 +1102,10 @@ static int tipc_crypto_key_attach(struct tipc_crypto *c,
 
 	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.pending) {
@@ -1114,8 +1137,7 @@ static int tipc_crypto_key_attach(struct tipc_crypto *c,
 		tipc_crypto_key_set_state(c, key.passive, key.active,
 					  key.pending);
 	c->working = 1;
-	c->timer1 = jiffies;
-	c->timer2 = jiffies;
+	c->key_master |= master_key;
 	rc = new_key;
 
 exit:
@@ -1128,7 +1150,7 @@ void tipc_crypto_key_flush(struct tipc_crypto *c)
 	int k;
 
 	spin_lock_bh(&c->lock);
-	c->working = 0;
+	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);
@@ -1204,6 +1226,7 @@ static bool tipc_crypto_key_try_align(struct tipc_crypto *rx, u8 new_pending)
  * @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
@@ -1213,7 +1236,8 @@ 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)
+						 struct sk_buff *skb,
+						 u8 tx_key)
 {
 	struct tipc_skb_cb *skb_cb = TIPC_SKB_CB(skb);
 	struct tipc_aead *aead = NULL;
@@ -1232,6 +1256,10 @@ 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);
@@ -1251,9 +1279,12 @@ 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;
@@ -1268,6 +1299,9 @@ static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
  * 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.
+ *
  * The "per-peer" sndnxt is also reset when the peer key has switched.
  */
 static void tipc_crypto_key_synch(struct tipc_crypto *rx, struct sk_buff *skb)
@@ -1278,11 +1312,23 @@ static void tipc_crypto_key_synch(struct tipc_crypto *rx, struct sk_buff *skb)
 	u32 self = tipc_own_addr(rx->net);
 	u8 cur, new;
 
-	/* Ensure this message is destined to us first */
+	/* 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;
+
+	/* For later cases, apply only if message is destined to this node */
 	if (!ehdr->destined || msg_short(hdr) || msg_destnode(hdr) != self)
 		return;
 
-	/* Peer RX active key has changed, let's update own TX users */
+	/* 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;
+
+	/* 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 &&
@@ -1340,7 +1386,7 @@ 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;
 	tipc_crypto_key_set_state(c, 0, 0, 0);
@@ -1475,6 +1521,12 @@ void tipc_crypto_timeout(struct tipc_crypto *rx)
 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;
@@ -1484,6 +1536,22 @@ void tipc_crypto_timeout(struct tipc_crypto *rx)
 	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
@@ -1493,7 +1561,8 @@ void tipc_crypto_timeout(struct tipc_crypto *rx)
  * @__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!
@@ -1516,46 +1585,63 @@ int tipc_crypto_xmit(struct net *net, struct sk_buff **skb,
 	struct tipc_msg *hdr = buf_msg(*skb);
 	struct tipc_key key = tx->key;
 	struct tipc_aead *aead = NULL;
-	struct sk_buff *_skb;
-	int rc = -ENOKEY;
 	u32 user = msg_user(hdr);
-	u8 tx_key;
+	u32 type = msg_type(hdr);
+	int rc = -ENOKEY;
+	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) {
-			_skb = skb_clone(*skb, GFP_ATOMIC);
-			if (_skb) {
-				TIPC_SKB_CB(_skb)->probe = 1;
-				tipc_crypto_xmit(net, &_skb, b, dst, __dnode);
-				if (_skb)
-					b->media->send_msg(net, _skb, b, dst);
+		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)
+			goto encrypt;
+		if (TIPC_SKB_CB(*skb)->xmit_type == SKB_GRACING) {
+			pr_debug("%s: gracing for msg (%d %d)\n", tx->name,
+				 user, type);
+			goto encrypt;
+		}
+		if (user == LINK_CONFIG ||
+		    (user == LINK_PROTOCOL && type == RESET_MSG) ||
+		    time_before(jiffies, tx->timer2 + TIPC_TX_GRACE_PERIOD)) {
+			if (__rx && __rx->key_master &&
+			    !atomic_read(&__rx->peer_rx_active))
+				goto encrypt;
+			if (!__rx) {
+				if (likely(!tx->legacy_user))
+					goto encrypt;
+				tipc_crypto_clone_msg(net, *skb, b, dst,
+						      __dnode, SKB_GRACING);
 			}
 		}
 	}
+
 	/* Else, use the active key if any */
 	if (likely(key.active)) {
 		tx_key = key.active;
 		goto encrypt;
 	}
+
 	goto exit;
 
 encrypt:
@@ -1621,15 +1707,16 @@ int tipc_crypto_rcv(struct net *net, struct tipc_crypto *rx,
 	struct tipc_aead *aead = NULL;
 	struct tipc_key key;
 	int rc = -ENOKEY;
-	u8 tx_key = 0;
+	u8 tx_key;
+
+	tx_key = ((struct tipc_ehdr *)(*skb)->data)->tx_key;
 
 	/* New peer?
 	 * Let's try with TX key (i.e. cluster mode) & verify the skb first!
 	 */
-	if (unlikely(!rx))
+	if (unlikely(!rx || tx_key == KEY_MASTER))
 		goto pick_tx;
 
-	tx_key = ((struct tipc_ehdr *)(*skb)->data)->tx_key;
 	/* Pick RX key according to TX key if any */
 	key = rx->key;
 	if (tx_key == key.active || tx_key == key.pending ||
@@ -1642,7 +1729,7 @@ int tipc_crypto_rcv(struct net *net, struct tipc_crypto *rx,
 
 pick_tx:
 	/* No key suitable? Try to pick one from TX... */
-	aead = tipc_crypto_key_pick_tx(tx, rx, *skb);
+	aead = tipc_crypto_key_pick_tx(tx, rx, *skb, tx_key);
 	if (aead)
 		goto decrypt;
 	goto exit;
@@ -1724,9 +1811,12 @@ static void tipc_crypto_rcv_complete(struct net *net, struct tipc_aead *aead,
 				goto free_skb;
 		}
 
+		/* Ignore cloning if it was TX master key */
+		if (ehdr->tx_key == KEY_MASTER)
+			goto rcv;
 		if (tipc_aead_clone(&tmp, aead) < 0)
 			goto rcv;
-		if (tipc_crypto_key_attach(rx, tmp, ehdr->tx_key) < 0) {
+		if (tipc_crypto_key_attach(rx, tmp, ehdr->tx_key, false) < 0) {
 			tipc_aead_free(&tmp->rcu);
 			goto rcv;
 		}
@@ -1742,10 +1832,10 @@ static void tipc_crypto_rcv_complete(struct net *net, struct tipc_aead *aead,
 	/* Set the RX key's user */
 	tipc_aead_users_set(aead, 1);
 
-rcv:
 	/* Mark this point, RX works */
 	rx->timer1 = jiffies;
 
+rcv:
 	/* Remove ehdr & auth. tag prior to tipc_rcv() */
 	ehdr = (struct tipc_ehdr *)(*skb)->data;
 
@@ -1867,14 +1957,24 @@ static char *tipc_crypto_key_dump(struct tipc_crypto *c, char *buf)
 	char *s;
 
 	for (k = KEY_MIN; k <= KEY_MAX; k++) {
-		if (k == key.passive)
-			s = "PAS";
-		else if (k == key.active)
-			s = "ACT";
-		else if (k == key.pending)
-			s = "PEN";
-		else
-			s = "-";
+		if (k == KEY_MASTER) {
+			if (is_rx(c))
+				continue;
+			if (time_before(jiffies,
+					c->timer2 + TIPC_TX_GRACE_PERIOD))
+				s = "ACT";
+			else
+				s = "PAS";
+		} else {
+			if (k == key.passive)
+				s = "PAS";
+			else if (k == key.active)
+				s = "ACT";
+			else if (k == key.pending)
+				s = "PEN";
+			else
+				s = "-";
+		}
 		i += scnprintf(buf + i, 200 - i, "\tKey%d: %s", k, s);
 
 		rcu_read_lock();
diff --git a/net/tipc/crypto.h b/net/tipc/crypto.h
index c3de769f49e8..7fcb80cb0e8a 100644
--- a/net/tipc/crypto.h
+++ b/net/tipc/crypto.h
@@ -74,7 +74,7 @@ extern int sysctl_tipc_max_tfms __read_mostly;
  *     3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0
  *     1 0 9 8 7 6 5 4|3 2 1 0 9 8 7 6|5 4 3 2 1 0 9 8|7 6 5 4 3 2 1 0
  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- * w0:|Ver=7| User  |D|TX |RX |K|                 Rsvd                |
+ * w0:|Ver=7| User  |D|TX |RX |K|M|N|             Rsvd                |
  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  * w1:|                             Seqno                             |
  * w2:|                           (8 octets)                          |
@@ -101,6 +101,9 @@ extern int sysctl_tipc_max_tfms __read_mostly;
  *	RX	: Currently RX active key corresponding to the destination
  *	          node's TX key (when the "D" bit is set)
  *	K	: Keep-alive bit (for RPS, LINK_PROTOCOL/STATE_MSG only)
+ *	M       : Bit indicates if sender has master key
+ *	N	: Bit indicates if sender has no RX keys corresponding to the
+ *	          receiver's TX (when the "D" bit is set)
  *	Rsvd	: Reserved bit, field
  * Word1-2:
  *	Seqno	: The 64-bit sequence number of the encrypted message, also
@@ -117,7 +120,9 @@ struct tipc_ehdr {
 			__u8	destined:1,
 				user:4,
 				version:3;
-			__u8	reserved_1:3,
+			__u8	reserved_1:1,
+				rx_nokey:1,
+				master_key:1,
 				keepalive:1,
 				rx_key_active:2,
 				tx_key:2;
@@ -128,7 +133,9 @@ struct tipc_ehdr {
 			__u8	tx_key:2,
 				rx_key_active:2,
 				keepalive:1,
-				reserved_1:3;
+				master_key:1,
+				rx_nokey:1,
+				reserved_1:1;
 #else
 #error  "Please fix <asm/byteorder.h>"
 #endif
@@ -158,7 +165,7 @@ int tipc_crypto_xmit(struct net *net, struct sk_buff **skb,
 int tipc_crypto_rcv(struct net *net, struct tipc_crypto *rx,
 		    struct sk_buff **skb, struct tipc_bearer *b);
 int tipc_crypto_key_init(struct tipc_crypto *c, struct tipc_aead_key *ukey,
-			 u8 mode);
+			 u8 mode, bool master_key);
 void tipc_crypto_key_flush(struct tipc_crypto *c);
 int tipc_aead_key_validate(struct tipc_aead_key *ukey);
 bool tipc_ehdr_validate(struct sk_buff *skb);
diff --git a/net/tipc/msg.h b/net/tipc/msg.h
index 1016e96db5c4..25e5c5c8a6ff 100644
--- a/net/tipc/msg.h
+++ b/net/tipc/msg.h
@@ -127,7 +127,9 @@ struct tipc_skb_cb {
 #ifdef CONFIG_TIPC_CRYPTO
 			u8 encrypted:1;
 			u8 decrypted:1;
-			u8 probe:1;
+#define SKB_PROBING	1
+#define SKB_GRACING	2
+			u8 xmit_type:2;
 			u8 tx_clone_deferred:1;
 #endif
 		};
diff --git a/net/tipc/netlink.c b/net/tipc/netlink.c
index c4aee6247d55..1ec00fcc26ee 100644
--- a/net/tipc/netlink.c
+++ b/net/tipc/netlink.c
@@ -108,6 +108,7 @@ const struct nla_policy tipc_nl_node_policy[TIPC_NLA_NODE_MAX + 1] = {
 					    .len = TIPC_NODEID_LEN},
 	[TIPC_NLA_NODE_KEY]		= { .type = NLA_BINARY,
 					    .len = TIPC_AEAD_KEY_SIZE_MAX},
+	[TIPC_NLA_NODE_KEY_MASTER]	= { .type = NLA_FLAG },
 };
 
 /* Properties valid for media, bearer and link */
diff --git a/net/tipc/node.c b/net/tipc/node.c
index 4edcee3088da..a097eb0350dc 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -2872,11 +2872,11 @@ static int __tipc_nl_node_set_key(struct sk_buff *skb, struct genl_info *info)
 {
 	struct nlattr *attrs[TIPC_NLA_NODE_MAX + 1];
 	struct net *net = sock_net(skb->sk);
-	struct tipc_net *tn = tipc_net(net);
+	struct tipc_crypto *tx = tipc_net(net)->crypto_tx, *c = tx;
 	struct tipc_node *n = NULL;
 	struct tipc_aead_key *ukey;
-	struct tipc_crypto *c;
-	u8 *id, *own_id;
+	bool master_key = false;
+	u8 *id, *own_id, mode;
 	int rc = 0;
 
 	if (!info->attrs[TIPC_NLA_NODE])
@@ -2886,51 +2886,45 @@ static int __tipc_nl_node_set_key(struct sk_buff *skb, struct genl_info *info)
 			      info->attrs[TIPC_NLA_NODE],
 			      tipc_nl_node_policy, info->extack);
 	if (rc)
-		goto exit;
+		return rc;
 
 	own_id = tipc_own_id(net);
-	if (!own_id) {
-		rc = -EPERM;
-		goto exit;
-	}
+	if (!own_id)
+		return -EPERM;
 
 	rc = tipc_nl_retrieve_key(attrs, &ukey);
 	if (rc)
-		goto exit;
+		return rc;
 
 	rc = tipc_aead_key_validate(ukey);
 	if (rc)
-		goto exit;
+		return rc;
 
 	rc = tipc_nl_retrieve_nodeid(attrs, &id);
 	switch (rc) {
 	case -ENODATA:
-		/* Cluster key mode */
-		rc = tipc_crypto_key_init(tn->crypto_tx, ukey, CLUSTER_KEY);
+		mode = CLUSTER_KEY;
+		master_key = !!(attrs[TIPC_NLA_NODE_KEY_MASTER]);
 		break;
 	case 0:
-		/* Per-node key mode */
-		if (!memcmp(id, own_id, NODE_ID_LEN)) {
-			c = tn->crypto_tx;
-		} else {
+		mode = PER_NODE_KEY;
+		if (memcmp(id, own_id, NODE_ID_LEN)) {
 			n = tipc_node_find_by_id(net, id) ?:
 				tipc_node_create(net, 0, id, 0xffffu, 0, true);
-			if (unlikely(!n)) {
-				rc = -ENOMEM;
-				break;
-			}
+			if (unlikely(!n))
+				return -ENOMEM;
 			c = n->crypto_rx;
 		}
-
-		rc = tipc_crypto_key_init(c, ukey, PER_NODE_KEY);
-		if (n)
-			tipc_node_put(n);
 		break;
 	default:
-		break;
+		return rc;
 	}
 
-exit:
+	/* Initiate the TX/RX key */
+	rc = tipc_crypto_key_init(c, ukey, mode, master_key);
+	if (n)
+		tipc_node_put(n);
+
 	return (rc < 0) ? rc : 0;
 }
 
-- 
2.26.2


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [net-next 3/4] tipc: add automatic session key exchange
  2020-08-29 19:41 [net-next 0/4] tipc: add more features to TIPC encryption Tuong Lien
  2020-08-29 19:41 ` [net-next 1/4] tipc: optimize key switching time and logic Tuong Lien
  2020-08-29 19:41 ` [net-next 2/4] tipc: introduce encryption master key Tuong Lien
@ 2020-08-29 19:41 ` Tuong Lien
  2020-08-30  5:50   ` kernel test robot
  2020-08-29 19:41 ` [net-next 4/4] tipc: add automatic rekeying for encryption key Tuong Lien
  3 siblings, 1 reply; 6+ messages in thread
From: Tuong Lien @ 2020-08-29 19:41 UTC (permalink / raw)
  To: davem, jmaloy, maloy, ying.xue, netdev; +Cc: tipc-discussion

With support from the master key option in the previous commit, it
becomes easy to make frequent updates/exchanges of session keys between
authenticated cluster nodes.
Basically, there are two situations where the key exchange will take in
place:

- When a new node joins the cluster (with the master key), it will need
  to get its peer's TX key, so that be able to decrypt further messages
  from that peer.

- When a new session key is generated (by either user manual setting or
  later automatic rekeying feature), the key will be distributed to all
  peer nodes in the cluster.

A key to be exchanged is encapsulated in the data part of a 'MSG_CRYPTO
/KEY_DISTR_MSG' TIPC v2 message, then xmit-ed as usual and encrypted by
using the master key before sending out. Upon receipt of the message it
will be decrypted in the same way as regular messages, then attached as
the sender's RX key in the receiver node.

In this way, the key exchange is reliable by the link layer, as well as
security, integrity and authenticity by the crypto layer.

Also, the forward security will be easily achieved by user changing the
master key actively but this should not be required very frequently.

The key exchange feature is independent on the presence of a master key
Note however that the master key still is needed for new nodes to be
able to join the cluster. It is also optional, and can be turned off/on
via the sysfs: 'net/tipc/key_exchange_enabled' [default 1: enabled].

Backward compatibility is guaranteed because for nodes that do not have
master key support, key exchange using master key ie. tx_key = 0 if any
will be shortly discarded at the message validation step. In other
words, the key exchange feature will be automatically disabled to those
nodes.

Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
---
 net/tipc/crypto.c | 359 +++++++++++++++++++++++++++++++++++++++++++---
 net/tipc/crypto.h |  24 ++++
 net/tipc/link.c   |   5 +
 net/tipc/msg.h    |   4 +
 net/tipc/node.c   |  19 ++-
 net/tipc/node.h   |   2 +
 net/tipc/sysctl.c |   9 ++
 7 files changed, 402 insertions(+), 20 deletions(-)

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index b75b817441e5..d29266a9d2ee 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -37,6 +37,8 @@
 #include <crypto/aead.h>
 #include <crypto/aes.h>
 #include "crypto.h"
+#include "msg.h"
+#include "bcast.h"
 
 #define TIPC_TX_GRACE_PERIOD	msecs_to_jiffies(5000) /* 5s */
 #define TIPC_TX_LASTING_TIME	msecs_to_jiffies(10000) /* 10s */
@@ -82,6 +84,8 @@ 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
@@ -133,6 +137,8 @@ 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
  */
@@ -147,6 +153,8 @@ struct tipc_aead {
 	u8 mode;
 	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;
@@ -166,7 +174,13 @@ 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
+ * @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
  * @stats: the crypto statistics
  * @name: the crypto name
  * @sndnxt: the per-peer sndnxt (TX)
@@ -175,6 +189,7 @@ struct tipc_crypto_stats {
  * @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 {
@@ -182,7 +197,16 @@ struct tipc_crypto {
 	struct tipc_node *node;
 	struct tipc_aead __rcu *aead[KEY_MAX + 1];
 	atomic_t peer_rx_active;
+	u16 key_gen;
 	struct tipc_key key;
+	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;
+
 	struct tipc_crypto_stats __percpu *stats;
 	char name[48];
 
@@ -194,6 +218,7 @@ struct tipc_crypto {
 			u8 working:1;
 			u8 key_master:1;
 			u8 legacy_user:1;
+			u8 nokey: 1;
 		};
 		u8 flags;
 	};
@@ -266,6 +291,11 @@ static void tipc_crypto_do_cmd(struct net *net, int cmd);
 static char *tipc_crypto_key_dump(struct tipc_crypto *c, char *buf);
 static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
 				  char *buf);
+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_rx(struct work_struct *work);
+
 #define is_tx(crypto) (!(crypto)->node)
 #define is_rx(crypto) (!is_tx(crypto))
 
@@ -356,6 +386,7 @@ static void tipc_aead_free(struct rcu_head *rp)
 		kfree(head);
 	}
 	free_percpu(aead->tfm_entry);
+	kzfree(aead->key);
 	kfree(aead);
 }
 
@@ -526,6 +557,7 @@ static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
 	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);
@@ -1007,7 +1039,7 @@ 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->key.keys : 0;
+	ehdr->rx_nokey = (__rx) ? __rx->nokey : 0;
 	ehdr->master_key = aead->crypto->key_master;
 	ehdr->reserved_1 = 0;
 	ehdr->reserved_2 = 0;
@@ -1132,11 +1164,13 @@ static int tipc_crypto_key_attach(struct tipc_crypto *c,
 
 attach:
 	aead->crypto = c;
+	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->nokey = 0;
 	c->key_master |= master_key;
 	rc = new_key;
 
@@ -1147,14 +1181,33 @@ static int tipc_crypto_key_attach(struct tipc_crypto *c,
 
 void tipc_crypto_key_flush(struct tipc_crypto *c)
 {
+	struct tipc_crypto *tx, *rx;
 	int k;
 
 	spin_lock_bh(&c->lock);
+	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);
 }
@@ -1300,7 +1353,8 @@ static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
  * 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.
+ * (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.
  */
@@ -1311,6 +1365,7 @@ static void tipc_crypto_key_synch(struct tipc_crypto *rx, struct sk_buff *skb)
 	struct tipc_msg *hdr = buf_msg(skb);
 	u32 self = tipc_own_addr(rx->net);
 	u8 cur, new;
+	unsigned long delay;
 
 	/* Update RX 'key_master' flag according to peer, also mark "legacy" if
 	 * a peer has no master key.
@@ -1324,9 +1379,22 @@ static void tipc_crypto_key_synch(struct tipc_crypto *rx, struct sk_buff *skb)
 		return;
 
 	/* Case 1: Peer has no keys, let's make master key take over */
-	if (ehdr->rx_nokey)
+	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);
+	}
 
 	/* Case 2: Peer RX active key has changed, let's update own TX users */
 	cur = atomic_read(&rx->peer_rx_active);
@@ -1379,6 +1447,15 @@ 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) {
@@ -1389,7 +1466,9 @@ int tipc_crypto_start(struct tipc_crypto **crypto, struct net *net,
 	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;
@@ -1399,32 +1478,27 @@ int tipc_crypto_start(struct tipc_crypto **crypto, struct net *net,
 		  (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);
+
 	*crypto = c;
 	return 0;
 }
 
 void tipc_crypto_stop(struct tipc_crypto **crypto)
 {
-	struct tipc_crypto *c = *crypto, *tx, *rx;
+	struct tipc_crypto *c = *crypto;
 	u8 k;
 
 	if (!c)
 		return;
 
-	rcu_read_lock();
-	/* RX stopping? => decrease TX key users if any */
-	if (is_rx(c)) {
-		rx = c;
-		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))
+		destroy_workqueue(c->wq);
 
 	/* Release AEAD keys */
+	rcu_read_lock();
 	for (k = KEY_MIN; k <= KEY_MAX; k++)
 		tipc_aead_put(rcu_dereference(c->aead[k]));
 	rcu_read_unlock();
@@ -1623,6 +1697,7 @@ int tipc_crypto_xmit(struct net *net, struct sk_buff **skb,
 		}
 		if (user == LINK_CONFIG ||
 		    (user == LINK_PROTOCOL && type == RESET_MSG) ||
+		    (user == MSG_CRYPTO && type == KEY_DISTR_MSG) ||
 		    time_before(jiffies, tx->timer2 + TIPC_TX_GRACE_PERIOD)) {
 			if (__rx && __rx->key_master &&
 			    !atomic_read(&__rx->peer_rx_active))
@@ -1707,7 +1782,7 @@ int tipc_crypto_rcv(struct net *net, struct tipc_crypto *rx,
 	struct tipc_aead *aead = NULL;
 	struct tipc_key key;
 	int rc = -ENOKEY;
-	u8 tx_key;
+	u8 tx_key, n;
 
 	tx_key = ((struct tipc_ehdr *)(*skb)->data)->tx_key;
 
@@ -1757,8 +1832,19 @@ int tipc_crypto_rcv(struct net *net, struct tipc_crypto *rx,
 		if (rc == -ENOKEY) {
 			kfree_skb(*skb);
 			*skb = NULL;
-			if (rx)
+			if (rx) {
+				/* Mark rx->nokey only if we dont have a
+				 * pending received session key, nor a newer
+				 * one i.e. in the next slot.
+				 */
+				n = key_next(tx_key);
+				rx->nokey = !(rx->skey ||
+					      rcu_access_pointer(rx->aead[n]));
+				pr_debug_ratelimited("%s: nokey %d, key %d/%x\n",
+						     rx->name, rx->nokey,
+						     tx_key, rx->key.keys);
 				tipc_node_put(rx->node);
+			}
 			this_cpu_inc(stats->stat[STAT_NOKEYS]);
 			return rc;
 		} else if (rc == -EBADMSG) {
@@ -2027,3 +2113,238 @@ static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
 	i += scnprintf(buf + i, 32 - i, "]");
 	return buf;
 }
+
+/**
+ * tipc_crypto_msg_rcv - Common 'MSG_CRYPTO' processing point
+ * @net: the struct net
+ * @skb: the receiving message buffer
+ */
+void tipc_crypto_msg_rcv(struct net *net, struct sk_buff *skb)
+{
+	struct tipc_msg *hdr = buf_msg(skb);
+	struct tipc_crypto *rx;
+
+	rx = tipc_node_crypto_rx_by_addr(net, msg_prevnode(hdr));
+	if (unlikely(!rx))
+		goto exit;
+
+	switch (msg_type(hdr)) {
+	case KEY_DISTR_MSG:
+		if (tipc_crypto_key_rcv(rx, hdr))
+			goto exit;
+		break;
+	default:
+		break;
+	}
+
+	tipc_node_put(rx->node);
+
+exit:
+	kfree_skb(skb);
+}
+
+/**
+ * tipc_crypto_key_distr - Distribute a TX key
+ * @tx: the TX crypto
+ * @key: the key's index
+ * @dest: the destination tipc node, = NULL if distributing to all nodes
+ *
+ * Return: 0 in case of success, otherwise < 0
+ */
+int tipc_crypto_key_distr(struct tipc_crypto *tx, u8 key,
+			  struct tipc_node *dest)
+{
+	struct tipc_aead *aead;
+	char *dstr = (dest) ? tipc_node_get_id_str(dest) : "all";
+	u32 dnode = tipc_node_get_addr(dest);
+	int rc = -ENOKEY;
+
+	if (!sysctl_tipc_key_exchange_enabled)
+		return 0;
+
+	if (key) {
+		rcu_read_lock();
+		aead = tipc_aead_get(tx->aead[key]);
+		if (likely(aead)) {
+			rc = tipc_crypto_key_xmit(tx->net, aead->key,
+						  aead->gen, aead->mode,
+						  dnode);
+			tipc_aead_put(aead);
+		}
+		rcu_read_unlock();
+	}
+
+	if (likely(!rc))
+		pr_info("%s: key[%d] is distributed to %s\n",
+			tx->name, key, dstr);
+	else
+		pr_warn("%s: unable to distr key[%d] to %s, err %d\n",
+			tx->name, key, dstr, rc);
+
+	return rc;
+}
+
+/**
+ * tipc_crypto_key_xmit - Send a session key
+ * @net: the struct net
+ * @skey: the session key to be sent
+ * @gen: the key's generation
+ * @mode: the key's mode
+ * @dnode: the destination node address, = 0 if broadcasting to all nodes
+ *
+ * The session key 'skey' is packed in a TIPC v2 'MSG_CRYPTO/KEY_DISTR_MSG'
+ * as its data section, then xmit-ed through the uc/bc link.
+ *
+ * Return: 0 in case of success, otherwise < 0
+ */
+static int tipc_crypto_key_xmit(struct net *net, struct tipc_aead_key *skey,
+				u16 gen, u8 mode, u32 dnode)
+{
+	struct sk_buff_head pkts;
+	struct tipc_msg *hdr;
+	struct sk_buff *skb;
+	u16 size, cong_link_cnt;
+	u8 *data;
+	int rc;
+
+	size = tipc_aead_key_size(skey);
+	skb = tipc_buf_acquire(INT_H_SIZE + size, GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	hdr = buf_msg(skb);
+	tipc_msg_init(tipc_own_addr(net), hdr, MSG_CRYPTO, KEY_DISTR_MSG,
+		      INT_H_SIZE, dnode);
+	msg_set_size(hdr, INT_H_SIZE + size);
+	msg_set_key_gen(hdr, gen);
+	msg_set_key_mode(hdr, mode);
+
+	data = msg_data(hdr);
+	*((__be32 *)(data + TIPC_AEAD_ALG_NAME)) = htonl(skey->keylen);
+	memcpy(data, skey->alg_name, TIPC_AEAD_ALG_NAME);
+	memcpy(data + TIPC_AEAD_ALG_NAME + sizeof(__be32), skey->key,
+	       skey->keylen);
+
+	__skb_queue_head_init(&pkts);
+	__skb_queue_tail(&pkts, skb);
+	if (dnode)
+		rc = tipc_node_xmit(net, &pkts, dnode, 0);
+	else
+		rc = tipc_bcast_xmit(net, &pkts, &cong_link_cnt);
+
+	return rc;
+}
+
+/**
+ * tipc_crypto_key_rcv - Receive a session key
+ * @rx: the RX crypto
+ * @hdr: the TIPC v2 message incl. the receiving session key in its data
+ *
+ * This function retrieves the session key in the message from peer, then
+ * schedules a RX work to attach the key to the corresponding RX crypto.
+ *
+ * Return: "true" if the key has been scheduled for attaching, otherwise
+ * "false".
+ */
+static bool tipc_crypto_key_rcv(struct tipc_crypto *rx, struct tipc_msg *hdr)
+{
+	struct tipc_crypto *tx = tipc_net(rx->net)->crypto_tx;
+	struct tipc_aead_key *skey = NULL;
+	u16 key_gen = msg_key_gen(hdr);
+	u16 size = msg_data_sz(hdr);
+	u8 *data = msg_data(hdr);
+
+	spin_lock(&rx->lock);
+	if (unlikely(rx->skey || (key_gen == rx->key_gen && rx->key.keys))) {
+		pr_err("%s: key existed <%p>, gen %d vs %d\n", rx->name,
+		       rx->skey, key_gen, rx->key_gen);
+		goto exit;
+	}
+
+	/* Allocate memory for the key */
+	skey = kmalloc(size, GFP_ATOMIC);
+	if (unlikely(!skey)) {
+		pr_err("%s: unable to allocate memory for skey\n", rx->name);
+		goto exit;
+	}
+
+	/* Copy key from msg data */
+	skey->keylen = ntohl(*((__be32 *)(data + TIPC_AEAD_ALG_NAME)));
+	memcpy(skey->alg_name, data, TIPC_AEAD_ALG_NAME);
+	memcpy(skey->key, data + TIPC_AEAD_ALG_NAME + sizeof(__be32),
+	       skey->keylen);
+
+	/* Sanity check */
+	if (unlikely(size != tipc_aead_key_size(skey))) {
+		kfree(skey);
+		skey = NULL;
+		goto exit;
+	}
+
+	rx->key_gen = key_gen;
+	rx->skey_mode = msg_key_mode(hdr);
+	rx->skey = skey;
+	rx->nokey = 0;
+	mb(); /* for nokey flag */
+
+exit:
+	spin_unlock(&rx->lock);
+
+	/* Schedule the key attaching on this crypto */
+	if (likely(skey && queue_delayed_work(tx->wq, &rx->work, 0)))
+		return true;
+
+	return false;
+}
+
+/**
+ * tipc_crypto_work_rx - Scheduled RX works handler
+ * @work: the struct RX work
+ *
+ * The function processes the previous scheduled works i.e. distributing TX key
+ * or attaching a received session key on RX crypto.
+ */
+static void tipc_crypto_work_rx(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct tipc_crypto *rx = container_of(dwork, struct tipc_crypto, work);
+	struct tipc_crypto *tx = tipc_net(rx->net)->crypto_tx;
+	unsigned long delay = msecs_to_jiffies(5000);
+	bool resched = false;
+	int rc;
+
+	/* Case 1: Distribute TX key to peer if scheduled */
+	if (atomic_cmpxchg(&rx->key_distr,
+			   KEY_DISTR_SCHED,
+			   KEY_DISTR_COMPL) == KEY_DISTR_SCHED) {
+		/* Always pick the newest one for distributing */
+		tipc_crypto_key_distr(tx,
+				      tx->key.pending ?: tx->key.active,
+				      rx->node);
+		/* Sched for key_distr releasing */
+		resched = true;
+	} else {
+		atomic_cmpxchg(&rx->key_distr, KEY_DISTR_COMPL, 0);
+	}
+
+	/* Case 2: Attach a pending received session key from peer if any */
+	if (rx->skey) {
+		rc = tipc_crypto_key_init(rx, rx->skey, rx->skey_mode, false);
+		switch (rc) {
+		case -EBUSY:
+		case -ENOMEM:
+			/* Resched the key attaching */
+			resched = true;
+			break;
+		default:
+			synchronize_rcu();
+			kfree(rx->skey);
+			rx->skey = NULL;
+		}
+	}
+
+	if (resched && queue_delayed_work(tx->wq, &rx->work, delay))
+		return;
+
+	tipc_node_put(rx->node);
+}
diff --git a/net/tipc/crypto.h b/net/tipc/crypto.h
index 7fcb80cb0e8a..70bda3d7e174 100644
--- a/net/tipc/crypto.h
+++ b/net/tipc/crypto.h
@@ -67,6 +67,7 @@ enum {
 };
 
 extern int sysctl_tipc_max_tfms __read_mostly;
+extern int sysctl_tipc_key_exchange_enabled __read_mostly;
 
 /**
  * TIPC encryption message format:
@@ -167,8 +168,31 @@ int tipc_crypto_rcv(struct net *net, struct tipc_crypto *rx,
 int tipc_crypto_key_init(struct tipc_crypto *c, struct tipc_aead_key *ukey,
 			 u8 mode, bool master_key);
 void tipc_crypto_key_flush(struct tipc_crypto *c);
+int tipc_crypto_key_distr(struct tipc_crypto *tx, u8 key,
+			  struct tipc_node *dest);
+void tipc_crypto_msg_rcv(struct net *net, struct sk_buff *skb);
 int tipc_aead_key_validate(struct tipc_aead_key *ukey);
 bool tipc_ehdr_validate(struct sk_buff *skb);
 
+static inline u32 msg_key_gen(struct tipc_msg *m)
+{
+	return msg_bits(m, 4, 16, 0xffff);
+}
+
+static inline void msg_set_key_gen(struct tipc_msg *m, u32 gen)
+{
+	msg_set_bits(m, 4, 16, 0xffff, gen);
+}
+
+static inline u32 msg_key_mode(struct tipc_msg *m)
+{
+	return msg_bits(m, 4, 0, 0xf);
+}
+
+static inline void msg_set_key_mode(struct tipc_msg *m, u32 mode)
+{
+	msg_set_bits(m, 4, 0, 0xf, mode);
+}
+
 #endif /* _TIPC_CRYPTO_H */
 #endif
diff --git a/net/tipc/link.c b/net/tipc/link.c
index b7362556da95..3bad94c37249 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -1255,6 +1255,11 @@ static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
 	case MSG_FRAGMENTER:
 	case BCAST_PROTOCOL:
 		return false;
+#ifdef CONFIG_TIPC_CRYPTO
+	case MSG_CRYPTO:
+		tipc_crypto_msg_rcv(l->net, skb);
+		return true;
+#endif
 	default:
 		pr_warn("Dropping received illegal msg type\n");
 		kfree_skb(skb);
diff --git a/net/tipc/msg.h b/net/tipc/msg.h
index 25e5c5c8a6ff..5d64596ba987 100644
--- a/net/tipc/msg.h
+++ b/net/tipc/msg.h
@@ -82,6 +82,7 @@ struct plist;
 #define  NAME_DISTRIBUTOR     11
 #define  MSG_FRAGMENTER       12
 #define  LINK_CONFIG          13
+#define  MSG_CRYPTO           14
 #define  SOCK_WAKEUP          14       /* pseudo user */
 #define  TOP_SRV              15       /* pseudo user */
 
@@ -749,6 +750,9 @@ static inline void msg_set_nameupper(struct tipc_msg *m, u32 n)
 #define GRP_RECLAIM_MSG      4
 #define GRP_REMIT_MSG        5
 
+/* Crypto message types */
+#define KEY_DISTR_MSG		0
+
 /*
  * Word 1
  */
diff --git a/net/tipc/node.c b/net/tipc/node.c
index a097eb0350dc..4f822a5d82d8 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -278,6 +278,14 @@ struct tipc_crypto *tipc_node_crypto_rx_by_list(struct list_head *pos)
 {
 	return container_of(pos, struct tipc_node, list)->crypto_rx;
 }
+
+struct tipc_crypto *tipc_node_crypto_rx_by_addr(struct net *net, u32 addr)
+{
+	struct tipc_node *n;
+
+	n = tipc_node_find(net, addr);
+	return (n) ? n->crypto_rx : NULL;
+}
 #endif
 
 static void tipc_node_free(struct rcu_head *rp)
@@ -303,7 +311,7 @@ void tipc_node_put(struct tipc_node *node)
 	kref_put(&node->kref, tipc_node_kref_release);
 }
 
-static void tipc_node_get(struct tipc_node *node)
+void tipc_node_get(struct tipc_node *node)
 {
 	kref_get(&node->kref);
 }
@@ -584,6 +592,7 @@ static void tipc_node_calculate_timer(struct tipc_node *n, struct tipc_link *l)
 
 static void tipc_node_delete_from_list(struct tipc_node *node)
 {
+	tipc_crypto_key_flush(node->crypto_rx);
 	list_del_rcu(&node->list);
 	hlist_del_rcu(&node->hash);
 	tipc_node_put(node);
@@ -2922,6 +2931,14 @@ static int __tipc_nl_node_set_key(struct sk_buff *skb, struct genl_info *info)
 
 	/* Initiate the TX/RX key */
 	rc = tipc_crypto_key_init(c, ukey, mode, master_key);
+	if (rc < 0 || c != tx)
+		goto exit;
+
+	/* Distribute TX key but not master one */
+	if (!master_key)
+		tipc_crypto_key_distr(tx, rc, NULL);
+
+exit:
 	if (n)
 		tipc_node_put(n);
 
diff --git a/net/tipc/node.h b/net/tipc/node.h
index 9f6f13f1604f..154a5bbb0d29 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -79,12 +79,14 @@ bool tipc_node_get_id(struct net *net, u32 addr, u8 *id);
 u32 tipc_node_get_addr(struct tipc_node *node);
 char *tipc_node_get_id_str(struct tipc_node *node);
 void tipc_node_put(struct tipc_node *node);
+void tipc_node_get(struct tipc_node *node);
 struct tipc_node *tipc_node_create(struct net *net, u32 addr, u8 *peer_id,
 				   u16 capabilities, u32 hash_mixes,
 				   bool preliminary);
 #ifdef CONFIG_TIPC_CRYPTO
 struct tipc_crypto *tipc_node_crypto_rx(struct tipc_node *__n);
 struct tipc_crypto *tipc_node_crypto_rx_by_list(struct list_head *pos);
+struct tipc_crypto *tipc_node_crypto_rx_by_addr(struct net *net, u32 addr);
 #endif
 u32 tipc_node_try_addr(struct net *net, u8 *id, u32 addr);
 void tipc_node_check_dest(struct net *net, u32 onode, u8 *peer_id128,
diff --git a/net/tipc/sysctl.c b/net/tipc/sysctl.c
index 97a6264a2993..9fb65c988f7f 100644
--- a/net/tipc/sysctl.c
+++ b/net/tipc/sysctl.c
@@ -74,6 +74,15 @@ static struct ctl_table tipc_table[] = {
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1         = SYSCTL_ONE,
 	},
+	{
+		.procname	= "key_exchange_enabled",
+		.data		= &sysctl_tipc_key_exchange_enabled,
+		.maxlen		= sizeof(sysctl_tipc_key_exchange_enabled),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = SYSCTL_ONE,
+	},
 #endif
 	{
 		.procname	= "bc_retruni",
-- 
2.26.2


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [net-next 4/4] tipc: add automatic rekeying for encryption key
  2020-08-29 19:41 [net-next 0/4] tipc: add more features to TIPC encryption Tuong Lien
                   ` (2 preceding siblings ...)
  2020-08-29 19:41 ` [net-next 3/4] tipc: add automatic session key exchange Tuong Lien
@ 2020-08-29 19:41 ` Tuong Lien
  3 siblings, 0 replies; 6+ messages in thread
From: Tuong Lien @ 2020-08-29 19:41 UTC (permalink / raw)
  To: davem, jmaloy, maloy, ying.xue, netdev; +Cc: tipc-discussion

Rekeying is required for security since a key is less secure when using
for a long time. Also, key will be detached when its nonce value (or
seqno ...) is exhausted. We now make the rekeying process automatic and
configurable by user.

Basically, TIPC will at a specific interval generate a new key by using
the kernel 'Random Number Generator' cipher, then attach it as the node
TX key and securely distribute to others in the cluster as RX keys (-
the key exchange). The automatic key switching will then take over, and
make the new key active shortly. Afterwards, the traffic from this node
will be encrypted with the new session key. The same can happen in peer
nodes but not necessarily at the same time.

For simplicity, the automatically generated key will be initiated as a
per node key. It is not too hard to also support a cluster key rekeying
(e.g. a given node will generate a unique cluster key and update to the
others in the cluster...), but that doesn't bring much benefit, while a
per-node key is even more secure.

We also enable user to force a rekeying or change the rekeying interval
via netlink, the new 'set key' command option: 'TIPC_NLA_NODE_REKEYING'
is added for these purposes as follows:
- A value >= 1 will be set as the rekeying interval (in minutes);
- A value of 0 will disable the rekeying;
- A value of 'TIPC_REKEYING_NOW' (~0) will force an immediate rekeying;

The default rekeying interval is (60 * 24) minutes i.e. done every day.
There isn't any restriction for the value but user shouldn't set it too
small or too large which results in an "ineffective" rekeying (thats ok
for testing though).

Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
---
 include/uapi/linux/tipc.h         |   2 +
 include/uapi/linux/tipc_netlink.h |   1 +
 net/tipc/crypto.c                 | 115 +++++++++++++++++++++++++++++-
 net/tipc/crypto.h                 |   2 +
 net/tipc/netlink.c                |   1 +
 net/tipc/node.c                   |  28 +++++++-
 6 files changed, 146 insertions(+), 3 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 d484baa9d365..d847dd671d79 100644
--- a/include/uapi/linux/tipc_netlink.h
+++ b/include/uapi/linux/tipc_netlink.h
@@ -166,6 +166,7 @@ enum {
 	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 d29266a9d2ee..9d4ad832572f 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -36,6 +36,7 @@
 
 #include <crypto/aead.h>
 #include <crypto/aes.h>
+#include <crypto/rng.h>
 #include "crypto.h"
 #include "msg.h"
 #include "bcast.h"
@@ -48,6 +49,8 @@
 #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
  */
@@ -181,6 +184,7 @@ struct tipc_crypto_stats {
  * @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)
@@ -206,6 +210,7 @@ struct tipc_crypto {
 #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];
@@ -294,7 +299,9 @@ static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
 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))
@@ -342,6 +349,27 @@ int tipc_aead_key_validate(struct tipc_aead_key *ukey)
 	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;
@@ -1473,6 +1501,7 @@ int tipc_crypto_start(struct tipc_crypto **crypto, struct net *net,
 	atomic64_set(&c->sndnxt, 0);
 	c->timer1 = jiffies;
 	c->timer2 = jiffies;
+	c->rekeying_intv = TIPC_REKEYING_INTV_DEF;
 	spin_lock_init(&c->lock);
 	scnprintf(c->name, 48, "%s(%s)", (is_rx(c)) ? "RX" : "TX",
 		  (is_rx(c)) ? tipc_node_get_id_str(c->node) :
@@ -1480,6 +1509,8 @@ int tipc_crypto_start(struct tipc_crypto **crypto, struct net *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;
@@ -1494,8 +1525,11 @@ void tipc_crypto_stop(struct tipc_crypto **crypto)
 		return;
 
 	/* Flush any queued works & destroy wq */
-	if (is_tx(c))
+	if (is_tx(c)) {
+		c->rekeying_intv = 0;
+		cancel_delayed_work_sync(&c->work);
 		destroy_workqueue(c->wq);
+	}
 
 	/* Release AEAD keys */
 	rcu_read_lock();
@@ -2348,3 +2382,82 @@ static void tipc_crypto_work_rx(struct work_struct *work)
 
 	tipc_node_put(rx->node);
 }
+
+/**
+ * tipc_crypto_rekeying_sched - (Re)schedule rekeying w/o new interval
+ * @tx: TX crypto
+ * @changed: if the rekeying needs to be rescheduled with new interval
+ * @new_intv: new rekeying interval (when "changed" = true)
+ */
+void tipc_crypto_rekeying_sched(struct tipc_crypto *tx, bool changed,
+				u32 new_intv)
+{
+	unsigned long delay;
+	bool now = false;
+
+	if (changed) {
+		if (new_intv == TIPC_REKEYING_NOW)
+			now = true;
+		else
+			tx->rekeying_intv = new_intv;
+		cancel_delayed_work_sync(&tx->work);
+	}
+
+	if (tx->rekeying_intv || now) {
+		delay = (now) ? 0 : tx->rekeying_intv * 60 * 1000;
+		queue_delayed_work(tx->wq, &tx->work, msecs_to_jiffies(delay));
+	}
+}
+
+/**
+ * tipc_crypto_work_tx - Scheduled TX works handler
+ * @work: the struct TX work
+ *
+ * The function processes the previous scheduled work, i.e. key rekeying, by
+ * generating a new session key based on current one, then attaching it to the
+ * TX crypto and finally distributing it to peers. It also re-schedules the
+ * rekeying if needed.
+ */
+static void tipc_crypto_work_tx(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct tipc_crypto *tx = container_of(dwork, struct tipc_crypto, work);
+	struct tipc_aead_key *skey = NULL;
+	struct tipc_key key = tx->key;
+	struct tipc_aead *aead;
+	int rc = -ENOMEM;
+
+	if (unlikely(key.pending))
+		goto resched;
+
+	/* Take current key as a template */
+	rcu_read_lock();
+	aead = rcu_dereference(tx->aead[key.active ?: KEY_MASTER]);
+	if (unlikely(!aead)) {
+		rcu_read_unlock();
+		/* At least one key should exist for securing */
+		return;
+	}
+
+	/* Lets duplicate it first */
+	skey = kmemdup(aead->key, tipc_aead_key_size(aead->key), GFP_ATOMIC);
+	rcu_read_unlock();
+
+	/* Now, generate new key, initiate & distribute it */
+	if (likely(skey)) {
+		rc = tipc_aead_key_generate(skey) ?:
+		     tipc_crypto_key_init(tx, skey, PER_NODE_KEY, false);
+		if (likely(rc > 0))
+			rc = tipc_crypto_key_distr(tx, rc, NULL);
+		kzfree(skey);
+	}
+
+	if (likely(!rc))
+		pr_info("%s: rekeying has been done\n", tx->name);
+	else
+		pr_warn_ratelimited("%s: rekeying returns %d\n", tx->name, rc);
+
+resched:
+	/* Re-schedule rekeying if any */
+	tipc_crypto_rekeying_sched(tx, false, 0);
+}
diff --git a/net/tipc/crypto.h b/net/tipc/crypto.h
index 70bda3d7e174..e1f4e8fb5c10 100644
--- a/net/tipc/crypto.h
+++ b/net/tipc/crypto.h
@@ -171,6 +171,8 @@ void tipc_crypto_key_flush(struct tipc_crypto *c);
 int tipc_crypto_key_distr(struct tipc_crypto *tx, u8 key,
 			  struct tipc_node *dest);
 void tipc_crypto_msg_rcv(struct net *net, struct sk_buff *skb);
+void tipc_crypto_rekeying_sched(struct tipc_crypto *tx, bool changed,
+				u32 new_intv);
 int tipc_aead_key_validate(struct tipc_aead_key *ukey);
 bool tipc_ehdr_validate(struct sk_buff *skb);
 
diff --git a/net/tipc/netlink.c b/net/tipc/netlink.c
index 1ec00fcc26ee..c447cb5f879e 100644
--- a/net/tipc/netlink.c
+++ b/net/tipc/netlink.c
@@ -109,6 +109,7 @@ const struct nla_policy tipc_nl_node_policy[TIPC_NLA_NODE_MAX + 1] = {
 	[TIPC_NLA_NODE_KEY]		= { .type = NLA_BINARY,
 					    .len = TIPC_AEAD_KEY_SIZE_MAX},
 	[TIPC_NLA_NODE_KEY_MASTER]	= { .type = NLA_FLAG },
+	[TIPC_NLA_NODE_REKEYING]	= { .type = NLA_U32 },
 };
 
 /* Properties valid for media, bearer and link */
diff --git a/net/tipc/node.c b/net/tipc/node.c
index 4f822a5d82d8..c981ef2ad410 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -2877,6 +2877,17 @@ static int tipc_nl_retrieve_nodeid(struct nlattr **attrs, u8 **node_id)
 	return 0;
 }
 
+static int tipc_nl_retrieve_rekeying(struct nlattr **attrs, u32 *intv)
+{
+	struct nlattr *attr = attrs[TIPC_NLA_NODE_REKEYING];
+
+	if (!attr)
+		return -ENODATA;
+
+	*intv = nla_get_u32(attr);
+	return 0;
+}
+
 static int __tipc_nl_node_set_key(struct sk_buff *skb, struct genl_info *info)
 {
 	struct nlattr *attrs[TIPC_NLA_NODE_MAX + 1];
@@ -2884,8 +2895,9 @@ static int __tipc_nl_node_set_key(struct sk_buff *skb, struct genl_info *info)
 	struct tipc_crypto *tx = tipc_net(net)->crypto_tx, *c = tx;
 	struct tipc_node *n = NULL;
 	struct tipc_aead_key *ukey;
-	bool master_key = false;
+	bool rekeying = true, master_key = false;
 	u8 *id, *own_id, mode;
+	u32 intv = 0;
 	int rc = 0;
 
 	if (!info->attrs[TIPC_NLA_NODE])
@@ -2901,9 +2913,17 @@ static int __tipc_nl_node_set_key(struct sk_buff *skb, struct genl_info *info)
 	if (!own_id)
 		return -EPERM;
 
+	rc = tipc_nl_retrieve_rekeying(attrs, &intv);
+	if (rc == -ENODATA)
+		rekeying = false;
+
 	rc = tipc_nl_retrieve_key(attrs, &ukey);
-	if (rc)
+	if (rc == -ENODATA && rekeying) {
+		rc = 0;
+		goto rekeying;
+	} else if (rc) {
 		return rc;
+	}
 
 	rc = tipc_aead_key_validate(ukey);
 	if (rc)
@@ -2938,6 +2958,10 @@ static int __tipc_nl_node_set_key(struct sk_buff *skb, struct genl_info *info)
 	if (!master_key)
 		tipc_crypto_key_distr(tx, rc, NULL);
 
+rekeying:
+	/* Schedule TX rekeying if needed */
+	tipc_crypto_rekeying_sched(tx, rekeying, intv);
+
 exit:
 	if (n)
 		tipc_node_put(n);
-- 
2.26.2


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [net-next 3/4] tipc: add automatic session key exchange
  2020-08-29 19:41 ` [net-next 3/4] tipc: add automatic session key exchange Tuong Lien
@ 2020-08-30  5:50   ` kernel test robot
  0 siblings, 0 replies; 6+ messages in thread
From: kernel test robot @ 2020-08-30  5:50 UTC (permalink / raw)
  To: Tuong Lien, davem, jmaloy, maloy, ying.xue, netdev
  Cc: kbuild-all, clang-built-linux, tipc-discussion

[-- Attachment #1: Type: text/plain, Size: 2191 bytes --]

Hi Tuong,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on net-next/master]

url:    https://github.com/0day-ci/linux/commits/Tuong-Lien/tipc-add-more-features-to-TIPC-encryption/20200830-124405
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 0f091e43310f5c292b7094f9f115e651358e8053
config: arm-randconfig-r002-20200830 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c10e63677f5d20f18010f8f68c631ddc97546f7d)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> net/tipc/node.c:595:2: error: implicit declaration of function 'tipc_crypto_key_flush' [-Werror,-Wimplicit-function-declaration]
           tipc_crypto_key_flush(node->crypto_rx);
           ^
>> net/tipc/node.c:595:30: error: no member named 'crypto_rx' in 'struct tipc_node'
           tipc_crypto_key_flush(node->crypto_rx);
                                 ~~~~  ^
   2 errors generated.

# https://github.com/0day-ci/linux/commit/3b48f8cf565d52118c8adb2c1ec543bdc65e12b9
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Tuong-Lien/tipc-add-more-features-to-TIPC-encryption/20200830-124405
git checkout 3b48f8cf565d52118c8adb2c1ec543bdc65e12b9
vim +/tipc_crypto_key_flush +595 net/tipc/node.c

   592	
   593	static void tipc_node_delete_from_list(struct tipc_node *node)
   594	{
 > 595		tipc_crypto_key_flush(node->crypto_rx);
   596		list_del_rcu(&node->list);
   597		hlist_del_rcu(&node->hash);
   598		tipc_node_put(node);
   599	}
   600	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 27798 bytes --]

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2020-08-30  6:02 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-08-29 19:41 [net-next 0/4] tipc: add more features to TIPC encryption Tuong Lien
2020-08-29 19:41 ` [net-next 1/4] tipc: optimize key switching time and logic Tuong Lien
2020-08-29 19:41 ` [net-next 2/4] tipc: introduce encryption master key Tuong Lien
2020-08-29 19:41 ` [net-next 3/4] tipc: add automatic session key exchange Tuong Lien
2020-08-30  5:50   ` kernel test robot
2020-08-29 19:41 ` [net-next 4/4] tipc: add automatic rekeying for encryption key Tuong Lien

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