[v2] Bluetooth: Avoid redundant authentication

Commit Message

Ying Hsu Sept. 7, 2023, 4:39 a.m. UTC

While executing the Android 13 CTS Verifier Secure Server test on a
ChromeOS device, it was observed that the Bluetooth host initiates
authentication for an RFCOMM connection after SSP completes.
When this happens, some Intel Bluetooth controllers, like AC9560, would
disconnect with "Connection Rejected due to Security Reasons (0x0e)".

Historically, BlueZ did not mandate this authentication while an
authenticated combination key was already in use for the connection.
This behavior was changed since commit 7b5a9241b780
("Bluetooth: Introduce requirements for security level 4").
So, this patch addresses the aforementioned disconnection issue by
restoring the previous behavior.

Signed-off-by: Ying Hsu <[e-mail]>
---
- Tested CTS Verifier 13 Secure Server test on a chromebook with AC9560.
- Manual tests on classic mouse/keyboard/headset, BLE keyboard/mouse.

Changes in v2:
- Transitioned from multiple 'if' blocks to a 'switch-case' structure
  for clarity and maintainability.

 net/bluetooth/hci_conn.c | 63 ++++++++++++++++++++++------------------
 1 file changed, 35 insertions(+), 28 deletions(-)

Comments

[e-mail] Sept. 7, 2023, 5:36 a.m. UTC | #1

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=782141

---Test result---

Test Summary:
CheckPatch                    PASS      0.66 seconds
GitLint                       PASS      0.30 seconds
SubjectPrefix                 PASS      0.11 seconds
BuildKernel                   PASS      32.62 seconds
CheckAllWarning               PASS      35.64 seconds
CheckSparse                   PASS      40.47 seconds
CheckSmatch                   PASS      113.20 seconds
BuildKernel32                 PASS      30.92 seconds
TestRunnerSetup               PASS      475.32 seconds
TestRunner_l2cap-tester       PASS      26.90 seconds
TestRunner_iso-tester         PASS      47.91 seconds
TestRunner_bnep-tester        PASS      10.35 seconds
TestRunner_mgmt-tester        PASS      220.23 seconds
TestRunner_rfcomm-tester      PASS      15.73 seconds
TestRunner_sco-tester         PASS      19.14 seconds
TestRunner_ioctl-tester       PASS      17.48 seconds
TestRunner_mesh-tester        PASS      13.01 seconds
TestRunner_smp-tester         PASS      13.90 seconds
TestRunner_userchan-tester    PASS      10.87 seconds
IncrementalBuild              PASS      29.19 seconds



---
Regards,
Linux Bluetooth

[e-mail] Sept. 8, 2023, 8:50 p.m. UTC | #2

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <[e-mail]>:

On Thu,  7 Sep 2023 04:39:34 +0000 you wrote:
> While executing the Android 13 CTS Verifier Secure Server test on a
> ChromeOS device, it was observed that the Bluetooth host initiates
> authentication for an RFCOMM connection after SSP completes.
> When this happens, some Intel Bluetooth controllers, like AC9560, would
> disconnect with "Connection Rejected due to Security Reasons (0x0e)".
> 
> Historically, BlueZ did not mandate this authentication while an
> authenticated combination key was already in use for the connection.
> This behavior was changed since commit 7b5a9241b780
> ("Bluetooth: Introduce requirements for security level 4").
> So, this patch addresses the aforementioned disconnection issue by
> restoring the previous behavior.
> 
> [...]

Here is the summary with links:
  - [v2] Bluetooth: Avoid redundant authentication
    https://git.kernel.org/bluetooth/bluetooth-next/c/4c8a783f3882

You are awesome, thank you!

Patch

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 9d5057cef30a..7a6f20338db8 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -2413,34 +2413,41 @@  int hci_conn_security(struct hci_conn *conn, __u8 sec_level, __u8 auth_type,
 	if (!test_bit(HCI_CONN_AUTH, &conn->flags))
 		goto auth;
 
-	/* An authenticated FIPS approved combination key has sufficient
-	 * security for security level 4. */
-	if (conn->key_type == HCI_LK_AUTH_COMBINATION_P256 &&
-	    sec_level == BT_SECURITY_FIPS)
-		goto encrypt;
-
-	/* An authenticated combination key has sufficient security for
-	   security level 3. */
-	if ((conn->key_type == HCI_LK_AUTH_COMBINATION_P192 ||
-	     conn->key_type == HCI_LK_AUTH_COMBINATION_P256) &&
-	    sec_level == BT_SECURITY_HIGH)
-		goto encrypt;
-
-	/* An unauthenticated combination key has sufficient security for
-	   security level 1 and 2. */
-	if ((conn->key_type == HCI_LK_UNAUTH_COMBINATION_P192 ||
-	     conn->key_type == HCI_LK_UNAUTH_COMBINATION_P256) &&
-	    (sec_level == BT_SECURITY_MEDIUM || sec_level == BT_SECURITY_LOW))
-		goto encrypt;
-
-	/* A combination key has always sufficient security for the security
-	   levels 1 or 2. High security level requires the combination key
-	   is generated using maximum PIN code length (16).
-	   For pre 2.1 units. */
-	if (conn->key_type == HCI_LK_COMBINATION &&
-	    (sec_level == BT_SECURITY_MEDIUM || sec_level == BT_SECURITY_LOW ||
-	     conn->pin_length == 16))
-		goto encrypt;
+	switch (conn->key_type) {
+	case HCI_LK_AUTH_COMBINATION_P256:
+		/* An authenticated FIPS approved combination key has
+		 * sufficient security for security level 4 or lower.
+		 */
+		if (sec_level <= BT_SECURITY_FIPS)
+			goto encrypt;
+		break;
+	case HCI_LK_AUTH_COMBINATION_P192:
+		/* An authenticated combination key has sufficient security for
+		 * security level 3 or lower.
+		 */
+		if (sec_level <= BT_SECURITY_HIGH)
+			goto encrypt;
+		break;
+	case HCI_LK_UNAUTH_COMBINATION_P192:
+	case HCI_LK_UNAUTH_COMBINATION_P256:
+		/* An unauthenticated combination key has sufficient security
+		 * for security level 2 or lower.
+		 */
+		if (sec_level <= BT_SECURITY_MEDIUM)
+			goto encrypt;
+		break;
+	case HCI_LK_COMBINATION:
+		/* A combination key has always sufficient security for the
+		 * security levels 2 or lower. High security level requires the
+		 * combination key is generated using maximum PIN code length
+		 * (16). For pre 2.1 units.
+		 */
+		if (sec_level <= BT_SECURITY_MEDIUM || conn->pin_length == 16)
+			goto encrypt;
+		break;
+	default:
+		break;
+	}
 
 auth:
 	if (test_bit(HCI_CONN_ENCRYPT_PEND, &conn->flags))