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authorTuong Lien <tuong.t.lien@dektech.com.au>2020-09-18 04:17:27 +0300
committerDavid S. Miller <davem@davemloft.net>2020-09-18 23:58:37 +0300
commitdaef1ee3798b25e8464b8eb618eaa74b8f423ac7 (patch)
treeca067230e96b19996bfc5f1844b6628367ee5d1d /net/tipc/crypto.c
parentf779bf792284fed78fedee61b46df2d4652636d3 (diff)
downloadlinux-daef1ee3798b25e8464b8eb618eaa74b8f423ac7.tar.xz
tipc: introduce encryption master key
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> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc/crypto.c')
-rw-r--r--net/tipc/crypto.c210
1 files changed, 155 insertions, 55 deletions
diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 45a8f4d9d9de..2510b82d3cc1 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);
@@ -943,8 +959,6 @@ 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;
}
@@ -997,6 +1011,8 @@ 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;
@@ -1039,6 +1055,7 @@ 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.
@@ -1046,7 +1063,7 @@ 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;
@@ -1056,7 +1073,7 @@ 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);
}
@@ -1069,11 +1086,13 @@ 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;
@@ -1081,6 +1100,10 @@ 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) {
@@ -1112,8 +1135,7 @@ attach:
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:
@@ -1126,7 +1148,7 @@ 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);
@@ -1202,6 +1224,7 @@ 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
@@ -1211,7 +1234,8 @@ 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;
@@ -1230,6 +1254,10 @@ 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);
@@ -1249,9 +1277,12 @@ 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;
@@ -1266,6 +1297,9 @@ 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)
@@ -1276,11 +1310,23 @@ 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 &&
@@ -1338,7 +1384,7 @@ 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);
@@ -1473,6 +1519,12 @@ s4:
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;
@@ -1482,6 +1534,22 @@ 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
@@ -1491,7 +1559,8 @@ 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!
@@ -1514,46 +1583,63 @@ 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:
@@ -1619,15 +1705,16 @@ 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 ||
@@ -1640,7 +1727,7 @@ 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;
@@ -1722,9 +1809,12 @@ 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;
}
@@ -1740,10 +1830,10 @@ 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;
@@ -1865,14 +1955,24 @@ 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();
@@ -1905,7 +2005,7 @@ static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
/* Output format: "[%s %s %s] -> [%s %s %s]", max len = 32 */
again:
i += scnprintf(buf + i, 32 - i, "[");
- for (k = KEY_MIN; k <= KEY_MAX; k++) {
+ for (k = KEY_1; k <= KEY_3; k++) {
if (k == key->passive)
s = "pas";
else if (k == key->active)
@@ -1915,7 +2015,7 @@ again:
else
s = "-";
i += scnprintf(buf + i, 32 - i,
- (k != KEY_MAX) ? "%s " : "%s", s);
+ (k != KEY_3) ? "%s " : "%s", s);
}
if (key != &new) {
i += scnprintf(buf + i, 32 - i, "] -> ");