rxrpc: Don't retain the server key in the connection

Don't retain a pointer to the server key in the connection, but rather get it on demand when the server has to deal with a response packet. This is necessary to implement RxGK (GSSAPI-mediated transport class), where we can't know which key we'll need until we've challenged the client and got back the response. This also means that we don't need to do a key search in the accept path in softirq mode. Also, whilst we're at it, allow the security class to ask for a kvno and encoding-type variant of a server key as RxGK needs different keys for different encoding types. Keys of this type have an extra bit in the description: "<service-id>:<security-index>:<kvno>:<enctype>" Signed-off-by: David Howells <[email protected]>
ambv · Nov 23, 2020 · ec832bd · ec832bd
1 parent 41057eb
commit ec832bd
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Showing 7 changed files with 100 additions and 67 deletions.
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
@@ -441,7 +441,6 @@ struct rxrpc_connection {
 	struct list_head	link;		/* link in master connection list */
 	struct sk_buff_head	rx_queue;	/* received conn-level packets */
 	const struct rxrpc_security *security;	/* applied security module */
-	struct key		*server_key;	/* security for this service */
 	struct crypto_sync_skcipher *cipher;	/* encryption handle */
 	struct rxrpc_crypt	csum_iv;	/* packet checksum base */
 	unsigned long		flags;
@@ -890,8 +889,7 @@ struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *,
 						     struct sk_buff *);
 struct rxrpc_connection *rxrpc_prealloc_service_connection(struct rxrpc_net *, gfp_t);
 void rxrpc_new_incoming_connection(struct rxrpc_sock *, struct rxrpc_connection *,
-				   const struct rxrpc_security *, struct key *,
-				   struct sk_buff *);
+				   const struct rxrpc_security *, struct sk_buff *);
 void rxrpc_unpublish_service_conn(struct rxrpc_connection *);
 
 /*
@@ -1056,9 +1054,10 @@ extern const struct rxrpc_security rxkad;
 int __init rxrpc_init_security(void);
 void rxrpc_exit_security(void);
 int rxrpc_init_client_conn_security(struct rxrpc_connection *);
-bool rxrpc_look_up_server_security(struct rxrpc_local *, struct rxrpc_sock *,
-				   const struct rxrpc_security **, struct key **,
-				   struct sk_buff *);
+const struct rxrpc_security *rxrpc_get_incoming_security(struct rxrpc_sock *,
+							 struct sk_buff *);
+struct key *rxrpc_look_up_server_security(struct rxrpc_connection *,
+					  struct sk_buff *, u32, u32);
 
 /*
  * sendmsg.c

diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c
@@ -261,7 +261,6 @@ static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 						    struct rxrpc_peer *peer,
 						    struct rxrpc_connection *conn,
 						    const struct rxrpc_security *sec,
-						    struct key *key,
 						    struct sk_buff *skb)
 {
 	struct rxrpc_backlog *b = rx->backlog;
@@ -309,7 +308,7 @@ static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 		conn->params.local = rxrpc_get_local(local);
 		conn->params.peer = peer;
 		rxrpc_see_connection(conn);
-		rxrpc_new_incoming_connection(rx, conn, sec, key, skb);
+		rxrpc_new_incoming_connection(rx, conn, sec, skb);
 	} else {
 		rxrpc_get_connection(conn);
 	}
@@ -353,7 +352,6 @@ struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 	struct rxrpc_connection *conn;
 	struct rxrpc_peer *peer = NULL;
 	struct rxrpc_call *call = NULL;
-	struct key *key = NULL;
 
 	_enter("");
 
@@ -374,11 +372,13 @@ struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 	 */
 	conn = rxrpc_find_connection_rcu(local, skb, &peer);
 
-	if (!conn && !rxrpc_look_up_server_security(local, rx, &sec, &key, skb))
-		goto no_call;
+	if (!conn) {
+		sec = rxrpc_get_incoming_security(rx, skb);
+		if (!sec)
+			goto no_call;
+	}
 
-	call = rxrpc_alloc_incoming_call(rx, local, peer, conn, sec, key, skb);
-	key_put(key);
+	call = rxrpc_alloc_incoming_call(rx, local, peer, conn, sec, skb);
 	if (!call) {
 		skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
 		goto no_call;

diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c
@@ -378,7 +378,6 @@ static void rxrpc_secure_connection(struct rxrpc_connection *conn)
 	_enter("{%d}", conn->debug_id);
 
 	ASSERT(conn->security_ix != 0);
-	ASSERT(conn->server_key);
 
 	if (conn->security->issue_challenge(conn) < 0) {
 		abort_code = RX_CALL_DEAD;

diff --git a/net/rxrpc/conn_object.c b/net/rxrpc/conn_object.c
@@ -363,7 +363,6 @@ static void rxrpc_destroy_connection(struct rcu_head *rcu)
 
 	conn->security->clear(conn);
 	key_put(conn->params.key);
-	key_put(conn->server_key);
 	rxrpc_put_bundle(conn->bundle);
 	rxrpc_put_peer(conn->params.peer);
 

diff --git a/net/rxrpc/conn_service.c b/net/rxrpc/conn_service.c
@@ -156,7 +156,6 @@ struct rxrpc_connection *rxrpc_prealloc_service_connection(struct rxrpc_net *rxn
 void rxrpc_new_incoming_connection(struct rxrpc_sock *rx,
 				   struct rxrpc_connection *conn,
 				   const struct rxrpc_security *sec,
-				   struct key *key,
 				   struct sk_buff *skb)
 {
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
@@ -170,7 +169,6 @@ void rxrpc_new_incoming_connection(struct rxrpc_sock *rx,
 	conn->security_ix	= sp->hdr.securityIndex;
 	conn->out_clientflag	= 0;
 	conn->security		= sec;
-	conn->server_key	= key_get(key);
 	if (conn->security_ix)
 		conn->state	= RXRPC_CONN_SERVICE_UNSECURED;
 	else

diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c
@@ -647,11 +647,7 @@ static int rxkad_issue_challenge(struct rxrpc_connection *conn)
 	u32 serial;
 	int ret;
 
-	_enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key));
-
-	ret = key_validate(conn->server_key);
-	if (ret < 0)
-		return ret;
+	_enter("{%d}", conn->debug_id);
 
 	get_random_bytes(&conn->security_nonce, sizeof(conn->security_nonce));
 
@@ -891,6 +887,7 @@ static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
  * decrypt the kerberos IV ticket in the response
  */
 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
+				struct key *server_key,
 				struct sk_buff *skb,
 				void *ticket, size_t ticket_len,
 				struct rxrpc_crypt *_session_key,
@@ -910,30 +907,17 @@ static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
 	u32 abort_code;
 	u8 *p, *q, *name, *end;
 
-	_enter("{%d},{%x}", conn->debug_id, key_serial(conn->server_key));
+	_enter("{%d},{%x}", conn->debug_id, key_serial(server_key));
 
 	*_expiry = 0;
 
-	ret = key_validate(conn->server_key);
-	if (ret < 0) {
-		switch (ret) {
-		case -EKEYEXPIRED:
-			abort_code = RXKADEXPIRED;
-			goto other_error;
-		default:
-			abort_code = RXKADNOAUTH;
-			goto other_error;
-		}
-	}
-
-	ASSERT(conn->server_key->payload.data[0] != NULL);
+	ASSERT(server_key->payload.data[0] != NULL);
 	ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
 
-	memcpy(&iv, &conn->server_key->payload.data[2], sizeof(iv));
+	memcpy(&iv, &server_key->payload.data[2], sizeof(iv));
 
 	ret = -ENOMEM;
-	req = skcipher_request_alloc(conn->server_key->payload.data[0],
-				     GFP_NOFS);
+	req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS);
 	if (!req)
 		goto temporary_error;
 
@@ -1089,14 +1073,35 @@ static int rxkad_verify_response(struct rxrpc_connection *conn,
 	struct rxkad_response *response;
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 	struct rxrpc_crypt session_key;
+	struct key *server_key;
 	const char *eproto;
 	time64_t expiry;
 	void *ticket;
 	u32 abort_code, version, kvno, ticket_len, level;
 	__be32 csum;
 	int ret, i;
 
-	_enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key));
+	_enter("{%d}", conn->debug_id);
+
+	server_key = rxrpc_look_up_server_security(conn, skb, 0, 0);
+	if (IS_ERR(server_key)) {
+		switch (PTR_ERR(server_key)) {
+		case -ENOKEY:
+			abort_code = RXKADUNKNOWNKEY;
+			break;
+		case -EKEYEXPIRED:
+			abort_code = RXKADEXPIRED;
+			break;
+		default:
+			abort_code = RXKADNOAUTH;
+			break;
+		}
+		trace_rxrpc_abort(0, "SVK",
+				  sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+				  abort_code, PTR_ERR(server_key));
+		*_abort_code = abort_code;
+		return -EPROTO;
+	}
 
 	ret = -ENOMEM;
 	response = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
@@ -1144,8 +1149,8 @@ static int rxkad_verify_response(struct rxrpc_connection *conn,
 			  ticket, ticket_len) < 0)
 		goto protocol_error_free;
 
-	ret = rxkad_decrypt_ticket(conn, skb, ticket, ticket_len, &session_key,
-				   &expiry, _abort_code);
+	ret = rxkad_decrypt_ticket(conn, server_key, skb, ticket, ticket_len,
+				   &session_key, &expiry, _abort_code);
 	if (ret < 0)
 		goto temporary_error_free_ticket;
 
@@ -1224,6 +1229,7 @@ static int rxkad_verify_response(struct rxrpc_connection *conn,
 protocol_error:
 	kfree(response);
 	trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto);
+	key_put(server_key);
 	*_abort_code = abort_code;
 	return -EPROTO;
 
@@ -1236,6 +1242,7 @@ static int rxkad_verify_response(struct rxrpc_connection *conn,
 	 * ENOMEM.  We just want to send the challenge again.  Note that we
 	 * also come out this way if the ticket decryption fails.
 	 */
+	key_put(server_key);
 	return ret;
 }
 

diff --git a/net/rxrpc/security.c b/net/rxrpc/security.c
@@ -102,58 +102,89 @@ int rxrpc_init_client_conn_security(struct rxrpc_connection *conn)
 }
 
 /*
- * Find the security key for a server connection.
+ * Set the ops a server connection.
  */
-bool rxrpc_look_up_server_security(struct rxrpc_local *local, struct rxrpc_sock *rx,
-				   const struct rxrpc_security **_sec,
-				   struct key **_key,
-				   struct sk_buff *skb)
+const struct rxrpc_security *rxrpc_get_incoming_security(struct rxrpc_sock *rx,
+							 struct sk_buff *skb)
 {
 	const struct rxrpc_security *sec;
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
-	key_ref_t kref = NULL;
-	char kdesc[5 + 1 + 3 + 1];
 
 	_enter("");
 
-	sprintf(kdesc, "%u:%u", sp->hdr.serviceId, sp->hdr.securityIndex);
-
 	sec = rxrpc_security_lookup(sp->hdr.securityIndex);
 	if (!sec) {
 		trace_rxrpc_abort(0, "SVS",
 				  sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
 				  RX_INVALID_OPERATION, EKEYREJECTED);
 		skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
 		skb->priority = RX_INVALID_OPERATION;
-		return false;
+		return NULL;
 	}
 
-	if (sp->hdr.securityIndex == RXRPC_SECURITY_NONE)
-		goto out;
-
-	if (!rx->securities) {
+	if (sp->hdr.securityIndex != RXRPC_SECURITY_NONE &&
+	    !rx->securities) {
 		trace_rxrpc_abort(0, "SVR",
 				  sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
 				  RX_INVALID_OPERATION, EKEYREJECTED);
 		skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
-		skb->priority = RX_INVALID_OPERATION;
-		return false;
+		skb->priority = sec->no_key_abort;
+		return NULL;
 	}
 
+	return sec;
+}
+
+/*
+ * Find the security key for a server connection.
+ */
+struct key *rxrpc_look_up_server_security(struct rxrpc_connection *conn,
+					  struct sk_buff *skb,
+					  u32 kvno, u32 enctype)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	struct rxrpc_sock *rx;
+	struct key *key = ERR_PTR(-EKEYREJECTED);
+	key_ref_t kref = NULL;
+	char kdesc[5 + 1 + 3 + 1 + 12 + 1 + 12 + 1];
+	int ret;
+
+	_enter("");
+
+	if (enctype)
+		sprintf(kdesc, "%u:%u:%u:%u",
+			sp->hdr.serviceId, sp->hdr.securityIndex, kvno, enctype);
+	else if (kvno)
+		sprintf(kdesc, "%u:%u:%u",
+			sp->hdr.serviceId, sp->hdr.securityIndex, kvno);
+	else
+		sprintf(kdesc, "%u:%u",
+			sp->hdr.serviceId, sp->hdr.securityIndex);
+
+	rcu_read_lock();
+
+	rx = rcu_dereference(conn->params.local->service);
+	if (!rx)
+		goto out;
+
 	/* look through the service's keyring */
 	kref = keyring_search(make_key_ref(rx->securities, 1UL),
 			      &key_type_rxrpc_s, kdesc, true);
 	if (IS_ERR(kref)) {
-		trace_rxrpc_abort(0, "SVK",
-				  sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
-				  sec->no_key_abort, EKEYREJECTED);
-		skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
-		skb->priority = sec->no_key_abort;
-		return false;
+		key = ERR_CAST(kref);
+		goto out;
+	}
+
+	key = key_ref_to_ptr(kref);
+
+	ret = key_validate(key);
+	if (ret < 0) {
+		key_put(key);
+		key = ERR_PTR(ret);
+		goto out;
 	}
 
 out:
-	*_sec = sec;
-	*_key = key_ref_to_ptr(kref);
-	return true;
+	rcu_read_unlock();
+	return key;
 }