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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
To:     linux-bluetooth@vger.kernel.org
Subject: [PATCH v4 3/3] Bluetooth: hci_conn: Always allocate unique handles
Date:   Wed, 28 Jun 2023 17:13:10 -0700
Message-Id: <20230629001310.2946122-3-luiz.dentz@gmail.com>
In-Reply-To: <20230629001310.2946122-1-luiz.dentz@gmail.com>
References: <20230629001310.2946122-1-luiz.dentz@gmail.com>
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From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

This attempts to always allocate a unique handle for connections so they
can be properly aborted by the likes of hci_abort_conn, so this uses the
invalid range as a pool of unset handles that way if userspace is trying
to create multiple connections at once each will be given a unique
handle which will be considered unset.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/hci_core.h |  2 +-
 net/bluetooth/hci_conn.c         | 25 ++++++++++++++++++++++---
 net/bluetooth/hci_event.c        |  6 +++---
 3 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 094ca3aca15e..c0ca3f869c92 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -321,8 +321,8 @@ struct adv_monitor {
 
 #define HCI_MAX_SHORT_NAME_LENGTH	10
 
-#define HCI_CONN_HANDLE_UNSET		0xffff
 #define HCI_CONN_HANDLE_MAX		0x0eff
+#define HCI_CONN_HANDLE_UNSET(_handle)	(_handle > HCI_CONN_HANDLE_MAX)
 
 /* Min encryption key size to match with SMP */
 #define HCI_MIN_ENC_KEY_SIZE		7
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 0b717989cd4f..83858e6b674c 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -932,6 +932,25 @@ static void cis_cleanup(struct hci_conn *conn)
 	hci_le_remove_cig(hdev, conn->iso_qos.ucast.cig);
 }
 
+static u16 hci_conn_hash_alloc_unset(struct hci_dev *hdev)
+{
+	struct hci_conn_hash *h = &hdev->conn_hash;
+	struct hci_conn  *c;
+	u16 handle = HCI_CONN_HANDLE_MAX + 1;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(c, &h->list, list) {
+		/* Find the first unused handle */
+		if (handle == 0xffff || c->handle != handle)
+			break;
+		handle++;
+	}
+	rcu_read_unlock();
+
+	return handle;
+}
+
 struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
 			      u8 role)
 {
@@ -945,7 +964,7 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
 
 	bacpy(&conn->dst, dst);
 	bacpy(&conn->src, &hdev->bdaddr);
-	conn->handle = HCI_CONN_HANDLE_UNSET;
+	conn->handle = hci_conn_hash_alloc_unset(hdev);
 	conn->hdev  = hdev;
 	conn->type  = type;
 	conn->role  = role;
@@ -1057,7 +1076,7 @@ static void hci_conn_unlink(struct hci_conn *conn)
 			 */
 			if ((child->type == SCO_LINK ||
 			     child->type == ESCO_LINK) &&
-			    child->handle == HCI_CONN_HANDLE_UNSET)
+			    HCI_CONN_HANDLE_UNSET(child->handle))
 				hci_conn_del(child);
 		}
 
@@ -1943,7 +1962,7 @@ int hci_conn_check_create_cis(struct hci_conn *conn)
 		return -EINVAL;
 
 	if (!conn->parent || conn->parent->state != BT_CONNECTED ||
-	    conn->state != BT_CONNECT || conn->handle == HCI_CONN_HANDLE_UNSET)
+	    conn->state != BT_CONNECT || HCI_CONN_HANDLE_UNSET(conn->handle))
 		return 1;
 
 	return 0;
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 77cbf13037b3..0b4415e79989 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3173,7 +3173,7 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data,
 	 * As the connection handle is set here for the first time, it indicates
 	 * whether the connection is already set up.
 	 */
-	if (conn->handle != HCI_CONN_HANDLE_UNSET) {
+	if (!HCI_CONN_HANDLE_UNSET(conn->handle)) {
 		bt_dev_err(hdev, "Ignoring HCI_Connection_Complete for existing connection");
 		goto unlock;
 	}
@@ -5032,7 +5032,7 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev, void *data,
 	 * As the connection handle is set here for the first time, it indicates
 	 * whether the connection is already set up.
 	 */
-	if (conn->handle != HCI_CONN_HANDLE_UNSET) {
+	if (!HCI_CONN_HANDLE_UNSET(conn->handle)) {
 		bt_dev_err(hdev, "Ignoring HCI_Sync_Conn_Complete event for existing connection");
 		goto unlock;
 	}
@@ -5896,7 +5896,7 @@ static void le_conn_complete_evt(struct hci_dev *hdev, u8 status,
 	 * As the connection handle is set here for the first time, it indicates
 	 * whether the connection is already set up.
 	 */
-	if (conn->handle != HCI_CONN_HANDLE_UNSET) {
+	if (!HCI_CONN_HANDLE_UNSET(conn->handle)) {
 		bt_dev_err(hdev, "Ignoring HCI_Connection_Complete for existing connection");
 		goto unlock;
 	}
-- 
2.40.1