[PATCH v3] Bluetooth: MGMT: Add management security level changed event

["Frédéric Danis" <frederic.danis@collabora.com>]

Add an event on device security level or encryption type change to
let user space know which level is currently in use.
Reset security level to 0 on disconnection so further connections
will correctly report security level changes.

This will be used for BlueZ qualification automation.

Assisted-by: GPT:GPT-5.3-Codex
Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
---
v1->v2:
 - Add encryption type to the mgmt event
 - Send event on security level or encryption type change
v2->v3:
 - Replace fixed security level and ancryption type parameters by TLV array
   to allow later enhancement.

 include/net/bluetooth/hci_core.h | 15 +++++++++++--
 include/net/bluetooth/mgmt.h     | 13 ++++++++++++
 net/bluetooth/hci_conn.c         |  8 +++++++
 net/bluetooth/hci_event.c        | 20 ++++++++++++++++--
 net/bluetooth/mgmt.c             | 36 ++++++++++++++++++++++++++++++++
 5 files changed, 88 insertions(+), 4 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 4ca09298e11a..43099102075a 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -2178,6 +2178,8 @@ static inline void hci_auth_cfm(struct hci_conn *conn, __u8 status)
 		conn->security_cfm_cb(conn, status);
 }
 
+void mgmt_security_level_changed(struct hci_conn *conn);
+
 static inline void hci_encrypt_cfm(struct hci_conn *conn, __u8 status)
 {
 	struct hci_cb *cb;
@@ -2200,11 +2202,20 @@ static inline void hci_encrypt_cfm(struct hci_conn *conn, __u8 status)
 		encrypt = 0x01;
 
 	if (!status) {
-		if (conn->sec_level == BT_SECURITY_SDP)
+		bool sec_level_changed  = false;
+
+		if (conn->sec_level == BT_SECURITY_SDP) {
 			conn->sec_level = BT_SECURITY_LOW;
+			sec_level_changed = true;
+		}
 
-		if (conn->pending_sec_level > conn->sec_level)
+		if (conn->pending_sec_level > conn->sec_level) {
 			conn->sec_level = conn->pending_sec_level;
+			sec_level_changed = true;
+		}
+
+		if (sec_level_changed)
+			mgmt_security_level_changed(conn);
 	}
 
 	mutex_lock(&hci_cb_list_lock);
diff --git a/include/net/bluetooth/mgmt.h b/include/net/bluetooth/mgmt.h
index 08daed7a96d5..d9f7f2df9209 100644
--- a/include/net/bluetooth/mgmt.h
+++ b/include/net/bluetooth/mgmt.h
@@ -1192,3 +1192,16 @@ struct mgmt_ev_mesh_device_found {
 struct mgmt_ev_mesh_pkt_cmplt {
 	__u8	handle;
 } __packed;
+
+#define MGMT_CONN_SEC_ENCRYPT_NONE		0x00
+#define MGMT_CONN_SEC_ENCRYPT_E0		0x01
+#define MGMT_CONN_SEC_ENCRYPT_AES_CCM		0x02
+
+#define MGMT_SEC_LEVEL_CHANGED_PARAM_LEVEL	0x0000
+#define MGMT_SEC_LEVEL_CHANGED_PARAM_ENC_TYPE	0x0001
+
+#define MGMT_EV_SECURITY_LEVEL_CHANGED		0x0033
+struct mgmt_ev_security_level_changed {
+	struct mgmt_addr_info addr;
+	__u8   tlv_data[];
+} __packed;
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 1966cd153d97..376bde85ce6d 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1200,6 +1200,11 @@ static void hci_conn_unlink(struct hci_conn *conn)
 	if (!conn->parent) {
 		struct hci_link *link, *t;
 
+		conn->sec_level = BT_SECURITY_SDP;
+		clear_bit(HCI_CONN_ENCRYPT, &conn->flags);
+		clear_bit(HCI_CONN_AES_CCM, &conn->flags);
+		mgmt_security_level_changed(conn);
+
 		list_for_each_entry_safe(link, t, &conn->link_list, list) {
 			struct hci_conn *child = link->conn;
 
@@ -1502,6 +1507,7 @@ struct hci_conn *hci_connect_le(struct hci_dev *hdev, bdaddr_t *dst,
 	}
 
 	conn->sec_level = BT_SECURITY_LOW;
+	mgmt_security_level_changed(conn);
 	conn->conn_timeout = conn_timeout;
 	conn->le_adv_phy = phy;
 	conn->le_adv_sec_phy = sec_phy;
@@ -1729,6 +1735,7 @@ struct hci_conn *hci_connect_le_scan(struct hci_dev *hdev, bdaddr_t *dst,
 	conn->state = BT_CONNECT;
 	set_bit(HCI_CONN_SCANNING, &conn->flags);
 	conn->sec_level = BT_SECURITY_LOW;
+	mgmt_security_level_changed(conn);
 	conn->pending_sec_level = sec_level;
 	conn->conn_timeout = conn_timeout;
 	conn->conn_reason = conn_reason;
@@ -1777,6 +1784,7 @@ struct hci_conn *hci_connect_acl(struct hci_dev *hdev, bdaddr_t *dst,
 		int err;
 
 		acl->sec_level = BT_SECURITY_LOW;
+		mgmt_security_level_changed(acl);
 		acl->pending_sec_level = sec_level;
 		acl->auth_type = auth_type;
 		acl->conn_timeout = timeout;
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 5b867aa99332..2cbae697f361 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -765,6 +765,7 @@ static u8 hci_cc_read_enc_key_size(struct hci_dev *hdev, void *data,
 			status = HCI_ERROR_AUTH_FAILURE;
 			clear_bit(HCI_CONN_ENCRYPT, &conn->flags);
 			clear_bit(HCI_CONN_AES_CCM, &conn->flags);
+			mgmt_security_level_changed(conn);
 		}
 
 		/* Update the key encryption size with the connection one */
@@ -3187,6 +3188,8 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data,
 	}
 
 	if (!status) {
+		bool encrypt_change = false;
+
 		status = hci_conn_set_handle(conn, __le16_to_cpu(ev->handle));
 		if (status)
 			goto done;
@@ -3209,8 +3212,10 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data,
 		if (test_bit(HCI_AUTH, &hdev->flags))
 			set_bit(HCI_CONN_AUTH, &conn->flags);
 
-		if (test_bit(HCI_ENCRYPT, &hdev->flags))
+		if (test_bit(HCI_ENCRYPT, &hdev->flags)) {
 			set_bit(HCI_CONN_ENCRYPT, &conn->flags);
+			encrypt_change = true;
+		}
 
 		/* "Link key request" completed ahead of "connect request" completes */
 		if (ev->encr_mode == 1 && !test_bit(HCI_CONN_ENCRYPT, &conn->flags) &&
@@ -3220,11 +3225,15 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data,
 			key = hci_find_link_key(hdev, &ev->bdaddr);
 			if (key) {
 				set_bit(HCI_CONN_ENCRYPT, &conn->flags);
+				encrypt_change = true;
 				hci_read_enc_key_size(hdev, conn);
 				hci_encrypt_cfm(conn, ev->status);
 			}
 		}
 
+		if (encrypt_change)
+			mgmt_security_level_changed(conn);
+
 		/* Get remote features */
 		if (conn->type == ACL_LINK) {
 			struct hci_cp_read_remote_features cp;
@@ -3510,6 +3519,7 @@ static void hci_auth_complete_evt(struct hci_dev *hdev, void *data,
 		clear_bit(HCI_CONN_AUTH_FAILURE, &conn->flags);
 		set_bit(HCI_CONN_AUTH, &conn->flags);
 		conn->sec_level = conn->pending_sec_level;
+		mgmt_security_level_changed(conn);
 	} else {
 		if (ev->status == HCI_ERROR_PIN_OR_KEY_MISSING)
 			set_bit(HCI_CONN_AUTH_FAILURE, &conn->flags);
@@ -3625,9 +3635,12 @@ static void hci_encrypt_change_evt(struct hci_dev *hdev, void *data,
 			if ((conn->type == ACL_LINK && ev->encrypt == 0x02) ||
 			    conn->type == LE_LINK)
 				set_bit(HCI_CONN_AES_CCM, &conn->flags);
+
+			mgmt_security_level_changed(conn);
 		} else {
 			clear_bit(HCI_CONN_ENCRYPT, &conn->flags);
 			clear_bit(HCI_CONN_AES_CCM, &conn->flags);
+			mgmt_security_level_changed(conn);
 		}
 	}
 
@@ -5218,8 +5231,10 @@ static void hci_key_refresh_complete_evt(struct hci_dev *hdev, void *data,
 	if (conn->type != LE_LINK)
 		goto unlock;
 
-	if (!ev->status)
+	if (!ev->status) {
 		conn->sec_level = conn->pending_sec_level;
+		mgmt_security_level_changed(conn);
+	}
 
 	clear_bit(HCI_CONN_ENCRYPT_PEND, &conn->flags);
 
@@ -5850,6 +5865,7 @@ static void le_conn_complete_evt(struct hci_dev *hdev, u8 status,
 	mgmt_device_connected(hdev, conn, NULL, 0);
 
 	conn->sec_level = BT_SECURITY_LOW;
+	mgmt_security_level_changed(conn);
 	conn->state = BT_CONFIG;
 
 	/* Store current advertising instance as connection advertising instance
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 733a4b70e10c..d398bf20a545 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -177,6 +177,7 @@ static const u16 mgmt_events[] = {
 	MGMT_EV_CONTROLLER_RESUME,
 	MGMT_EV_ADV_MONITOR_DEVICE_FOUND,
 	MGMT_EV_ADV_MONITOR_DEVICE_LOST,
+	MGMT_EV_SECURITY_LEVEL_CHANGED,
 };
 
 static const u16 mgmt_untrusted_commands[] = {
@@ -10536,6 +10537,41 @@ void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
 	mgmt_adv_monitor_device_found(hdev, bdaddr, report_device, skb, NULL);
 }
 
+void mgmt_security_level_changed(struct hci_conn *conn)
+{
+	struct {
+		struct mgmt_ev_security_level_changed ev;
+		struct {
+			struct mgmt_tlv_hdr hdr;
+			__u8 value;
+		} __packed level;
+		struct {
+			struct mgmt_tlv_hdr hdr;
+			__u8 value;
+		} __packed enc_type;
+	} __packed data;
+
+	bacpy(&data.ev.addr.bdaddr, &conn->dst);
+	data.ev.addr.type = link_to_bdaddr(conn->type, conn->dst_type);
+
+	data.level.hdr.type = cpu_to_le16(MGMT_SEC_LEVEL_CHANGED_PARAM_LEVEL);
+	data.level.hdr.length = sizeof(__u8);
+	data.level.value = conn->sec_level;
+
+	data.enc_type.hdr.type = cpu_to_le16(
+				MGMT_SEC_LEVEL_CHANGED_PARAM_ENC_TYPE);
+	data.enc_type.hdr.length = sizeof(__u8);
+	if (!test_bit(HCI_CONN_ENCRYPT, &conn->flags))
+		data.enc_type.value = MGMT_CONN_SEC_ENCRYPT_NONE;
+	else if (test_bit(HCI_CONN_AES_CCM, &conn->flags))
+		data.enc_type.value = MGMT_CONN_SEC_ENCRYPT_AES_CCM;
+	else
+		data.enc_type.value = MGMT_CONN_SEC_ENCRYPT_E0;
+
+	mgmt_event(MGMT_EV_SECURITY_LEVEL_CHANGED, conn->hdev, &data,
+		   sizeof(data), NULL);
+}
+
 void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
 		      u8 addr_type, s8 rssi, u8 *name, u8 name_len)
 {
-- 
2.43.0