* [PATCH] Bluetooth: Add more enc key size check
@ 2023-12-11 8:29 Alex Lu
2023-12-11 8:59 ` bluez.test.bot
0 siblings, 1 reply; 2+ messages in thread
From: Alex Lu @ 2023-12-11 8:29 UTC (permalink / raw)
To: Marcel Holtmann, Johan Hedberg, Luiz Augusto von Dentz,
linux-bluetooth, linux-kernel
Cc: Max Chou, Karen Hsu
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>
---
net/bluetooth/l2cap_core.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 17ca13e8c044..b0f31d798132 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 = L2CAP_CR_SEC_BLOCK;
+ rsp.status = 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;
--
2.39.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* RE: Bluetooth: Add more enc key size check
2023-12-11 8:29 [PATCH] Bluetooth: Add more enc key size check Alex Lu
@ 2023-12-11 8:59 ` bluez.test.bot
0 siblings, 0 replies; 2+ messages in thread
From: bluez.test.bot @ 2023-12-11 8:59 UTC (permalink / raw)
To: linux-bluetooth, alex_lu
[-- Attachment #1: Type: text/plain, Size: 2043 bytes --]
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=808696
---Test result---
Test Summary:
CheckPatch PASS 0.52 seconds
GitLint PASS 0.24 seconds
SubjectPrefix PASS 0.19 seconds
BuildKernel PASS 27.94 seconds
CheckAllWarning PASS 30.11 seconds
CheckSparse WARNING 36.38 seconds
CheckSmatch PASS 98.37 seconds
BuildKernel32 PASS 26.50 seconds
TestRunnerSetup PASS 425.18 seconds
TestRunner_l2cap-tester PASS 23.09 seconds
TestRunner_iso-tester PASS 44.69 seconds
TestRunner_bnep-tester PASS 6.99 seconds
TestRunner_mgmt-tester FAIL 168.41 seconds
TestRunner_rfcomm-tester PASS 10.96 seconds
TestRunner_sco-tester PASS 14.52 seconds
TestRunner_ioctl-tester PASS 12.26 seconds
TestRunner_mesh-tester PASS 8.79 seconds
TestRunner_smp-tester PASS 10.18 seconds
TestRunner_userchan-tester PASS 7.36 seconds
IncrementalBuild PASS 25.61 seconds
Details
##############################
Test: CheckSparse - WARNING
Desc: Run sparse tool with linux kernel
Output:
net/bluetooth/l2cap_core.c:1676:52: warning: incorrect type in assignment (different base types)net/bluetooth/l2cap_core.c:1676:52: expected restricted __le16 [assigned] [usertype] resultnet/bluetooth/l2cap_core.c:1676:52: got int
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 497, Passed: 496 (99.8%), Failed: 1, Not Run: 0
Failed Test Cases
LL Privacy - Start Discovery 2 (Disable RL) Failed 0.289 seconds
---
Regards,
Linux Bluetooth
^ permalink raw reply [flat|nested] 2+ messages in thread
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