diff mbox series

[v2] Bluetooth: Add more enc key size check

Message ID ZXbWcZPq_2zIbqEO@alexlu (mailing list archive)
State Superseded
Headers show
Series [v2] Bluetooth: Add more enc key size check | expand

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Context Check Description
tedd_an/pre-ci_am success Success
tedd_an/CheckPatch success CheckPatch PASS
tedd_an/GitLint success Gitlint PASS
tedd_an/SubjectPrefix success Gitlint PASS
tedd_an/BuildKernel success BuildKernel PASS
tedd_an/CheckAllWarning success CheckAllWarning PASS
tedd_an/CheckSparse success CheckSparse PASS
tedd_an/CheckSmatch success CheckSparse PASS
tedd_an/BuildKernel32 success BuildKernel32 PASS
tedd_an/TestRunnerSetup success TestRunnerSetup PASS
tedd_an/TestRunner_l2cap-tester success TestRunner PASS
tedd_an/TestRunner_iso-tester success TestRunner PASS
tedd_an/TestRunner_bnep-tester success TestRunner PASS
tedd_an/TestRunner_mgmt-tester success TestRunner PASS
tedd_an/TestRunner_rfcomm-tester success TestRunner PASS
tedd_an/TestRunner_sco-tester success TestRunner PASS
tedd_an/TestRunner_ioctl-tester success TestRunner PASS
tedd_an/TestRunner_mesh-tester success TestRunner PASS
tedd_an/TestRunner_smp-tester success TestRunner PASS
tedd_an/TestRunner_userchan-tester success TestRunner PASS
tedd_an/IncrementalBuild success Incremental Build PASS

Commit Message

Alex Lu Dec. 11, 2023, 9:29 a.m. UTC 
From: Alex Lu <alex_lu@realsil.com.cn>

When we are slave role and receives l2cap conn req when encryption has
started, we should check the enc key size to avoid KNOB attack or BLUFFS
attack.
From SIG recommendation, implementations are advised to reject
service-level connections on an encrypted baseband link with key
strengths below 7 octets.

The btmon log below shows the case that lacks enc key size check.

> HCI Event: Connect Request (0x04) plen 10
        Address: BB:22:33:44:55:99 (OUI BB-22-33)
        Class: 0x480104
          Major class: Computer (desktop, notebook, PDA, organizers)
          Minor class: Desktop workstation
          Capturing (Scanner, Microphone)
          Telephony (Cordless telephony, Modem, Headset)
        Link type: ACL (0x01)
< HCI Command: Accept Connection Request (0x01|0x0009) plen 7
        Address: BB:22:33:44:55:99 (OUI BB-22-33)
        Role: Peripheral (0x01)
> HCI Event: Command Status (0x0f) plen 4
      Accept Connection Request (0x01|0x0009) ncmd 2
        Status: Success (0x00)
> HCI Event: Connect Complete (0x03) plen 11
        Status: Success (0x00)
        Handle: 1
        Address: BB:22:33:44:55:99 (OUI BB-22-33)
        Link type: ACL (0x01)
        Encryption: Disabled (0x00)
...

> HCI Event: Encryption Change (0x08) plen 4
        Status: Success (0x00)
        Handle: 1 Address: BB:22:33:44:55:99 (OUI BB-22-33)
        Encryption: Enabled with E0 (0x01)
< HCI Command: Read Encryption Key Size (0x05|0x0008) plen 2
        Handle: 1 Address: BB:22:33:44:55:99 (OUI BB-22-33)
> HCI Event: Command Complete (0x0e) plen 7
      Read Encryption Key Size (0x05|0x0008) ncmd 2
        Status: Success (0x00)
        Handle: 1 Address: BB:22:33:44:55:99 (OUI BB-22-33)
        Key size: 6
...

// We should check the enc key size
> ACL Data RX: Handle 1 flags 0x02 dlen 12
      L2CAP: Connection Request (0x02) ident 3 len 4
        PSM: 25 (0x0019)
        Source CID: 64
< ACL Data TX: Handle 1 flags 0x00 dlen 16
      L2CAP: Connection Response (0x03) ident 3 len 8
        Destination CID: 64
        Source CID: 64
        Result: Connection pending (0x0001)
        Status: Authorization pending (0x0002)
> HCI Event: Number of Completed Packets (0x13) plen 5
        Num handles: 1
        Handle: 1 Address: BB:22:33:44:55:99 (OUI BB-22-33)
        Count: 1
        #35: len 16 (25 Kb/s)
        Latency: 5 msec (2-7 msec ~4 msec)
< ACL Data TX: Handle 1 flags 0x00 dlen 16
      L2CAP: Connection Response (0x03) ident 3 len 8
        Destination CID: 64
        Source CID: 64
        Result: Connection successful (0x0000)
        Status: No further information available (0x0000)

Signed-off-by: Alex Lu <alex_lu@realsil.com.cn>
Signed-off-by: Max Chou <max.chou@realtek.com>
---
Changes in v2:
  - Fix compiling issue reported by sparse

 net/bluetooth/l2cap_core.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

Comments

bluez.test.bot@gmail.com Dec. 11, 2023, 9:57 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=808718

---Test result---

Test Summary:
CheckPatch                    PASS      0.48 seconds
GitLint                       PASS      0.21 seconds
SubjectPrefix                 PASS      0.07 seconds
BuildKernel                   PASS      27.52 seconds
CheckAllWarning               PASS      30.74 seconds
CheckSparse                   PASS      36.91 seconds
CheckSmatch                   PASS      99.35 seconds
BuildKernel32                 PASS      27.19 seconds
TestRunnerSetup               PASS      430.58 seconds
TestRunner_l2cap-tester       PASS      24.23 seconds
TestRunner_iso-tester         PASS      45.04 seconds
TestRunner_bnep-tester        PASS      7.09 seconds
TestRunner_mgmt-tester        PASS      160.98 seconds
TestRunner_rfcomm-tester      PASS      11.03 seconds
TestRunner_sco-tester         PASS      14.59 seconds
TestRunner_ioctl-tester       PASS      12.19 seconds
TestRunner_mesh-tester        PASS      8.72 seconds
TestRunner_smp-tester         PASS      9.77 seconds
TestRunner_userchan-tester    PASS      7.32 seconds
IncrementalBuild              PASS      25.72 seconds



---
Regards,
Linux Bluetooth
Luiz Augusto von Dentz Dec. 11, 2023, 5:52 p.m. UTC | #2 
Hi Alex,

On Mon, Dec 11, 2023 at 4:57 AM <bluez.test.bot@gmail.com> wrote:
>
> 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=808718
>
> ---Test result---
>
> Test Summary:
> CheckPatch                    PASS      0.48 seconds
> GitLint                       PASS      0.21 seconds
> SubjectPrefix                 PASS      0.07 seconds
> BuildKernel                   PASS      27.52 seconds
> CheckAllWarning               PASS      30.74 seconds
> CheckSparse                   PASS      36.91 seconds
> CheckSmatch                   PASS      99.35 seconds
> BuildKernel32                 PASS      27.19 seconds
> TestRunnerSetup               PASS      430.58 seconds
> TestRunner_l2cap-tester       PASS      24.23 seconds
> TestRunner_iso-tester         PASS      45.04 seconds
> TestRunner_bnep-tester        PASS      7.09 seconds
> TestRunner_mgmt-tester        PASS      160.98 seconds
> TestRunner_rfcomm-tester      PASS      11.03 seconds
> TestRunner_sco-tester         PASS      14.59 seconds
> TestRunner_ioctl-tester       PASS      12.19 seconds
> TestRunner_mesh-tester        PASS      8.72 seconds
> TestRunner_smp-tester         PASS      9.77 seconds
> TestRunner_userchan-tester    PASS      7.32 seconds
> IncrementalBuild              PASS      25.72 seconds
>

How about doing the following:

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 2ad7b9f86f74..f9a8fb9fcce2 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -750,9 +750,12 @@ static u8 hci_cc_read_enc_key_size(struct hci_dev
*hdev, void *data,
        } else {
                conn->enc_key_size = rp->key_size;
                status = 0;
+
+               if (conn->enc_key_size < hdev->min_enc_key_size)
+                       status = HCI_ERROR_AUTH_FAILURE;
        }

-       hci_encrypt_cfm(conn, 0);
+       hci_encrypt_cfm(conn, status);

 done:
        hci_dev_unlock(hdev);

That way we don't have to proliferate the checks over to L2CAP, etc,
so we consider that the encryption itself fails if the
conn->enc_key_size < hdev->min_enc_key_size.

>
> ---
> Regards,
> Linux Bluetooth
>
diff mbox series

Patch

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 17ca13e8c044..a9809fbe6b00 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -1669,7 +1669,13 @@  static void l2cap_conn_start(struct l2cap_conn *conn)
 			rsp.dcid = cpu_to_le16(chan->scid);
 
 			if (l2cap_chan_check_security(chan, false)) {
-				if (test_bit(FLAG_DEFER_SETUP, &chan->flags)) {
+				if (!l2cap_check_enc_key_size(conn->hcon)) {
+					l2cap_state_change(chan, BT_DISCONN);
+					__set_chan_timer(chan,
+							 L2CAP_DISC_TIMEOUT);
+					rsp.result = cpu_to_le16(L2CAP_CR_SEC_BLOCK);
+					rsp.status = cpu_to_le16(L2CAP_CS_NO_INFO);
+				} else if (test_bit(FLAG_DEFER_SETUP, &chan->flags)) {
 					rsp.result = cpu_to_le16(L2CAP_CR_PEND);
 					rsp.status = cpu_to_le16(L2CAP_CS_AUTHOR_PEND);
 					chan->ops->defer(chan);
@@ -4202,7 +4208,15 @@  static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn,
 
 	if (conn->info_state & L2CAP_INFO_FEAT_MASK_REQ_DONE) {
 		if (l2cap_chan_check_security(chan, false)) {
-			if (test_bit(FLAG_DEFER_SETUP, &chan->flags)) {
+			/* As slave role, we should check the enc key size when
+			 * l2cap conn req is received.
+			 */
+			if (!l2cap_check_enc_key_size(conn->hcon)) {
+				l2cap_state_change(chan, BT_DISCONN);
+				__set_chan_timer(chan, L2CAP_DISC_TIMEOUT);
+				result = L2CAP_CR_SEC_BLOCK;
+				status = L2CAP_CS_NO_INFO;
+			} else if (test_bit(FLAG_DEFER_SETUP, &chan->flags)) {
 				l2cap_state_change(chan, BT_CONNECT2);
 				result = L2CAP_CR_PEND;
 				status = L2CAP_CS_AUTHOR_PEND;