This change is used to relieve CVE-2020-26555. The description of the
CVE:
Bluetooth legacy BR/EDR PIN code pairing in Bluetooth Core Specification
1.0B through 5.2 may permit an unauthenticated nearby device to spoof
the BD_ADDR of the peer device to complete pairing without knowledge
of the PIN. [1]
The detail of this attack is in IEEE paper:
BlueMirror: Reflections on Bluetooth Pairing and Provisioning Protocols
[2]
It's a reflection attack. Base on the paper, attacker can induce the
attacked target to generate null link key (zero key) without PIN code.
We can ignore null link key in the handler of "Link Key Notification
event" to relieve the attack. A similar implementation also shows in
btstack project. [3]
v2:
- Used Link: tag instead of Closes:
- Used bt_dev_dbg instead of BT_DBG
- Added Fixes: tag
Fixes: 55ed8ca10f35 ("Bluetooth: Implement link key handling for the management interface")
Link: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26555 [1]
Link: https://ieeexplore.ieee.org/abstract/document/9474325/authors#authors [2]
Link: https://github.com/bluekitchen/btstack/blob/master/src/hci.c#L3722 [3]
Signed-off-by: "Lee, Chun-Yi" <[email protected]>
---
net/bluetooth/hci_event.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 95816a938cea..ff0c331f53d6 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4684,6 +4684,12 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, void *data,
bool persistent;
u8 pin_len = 0;
+ /* Ignore NULL link key against CVE-2020-26555 */
+ if (!memcmp(ev->link_key, ZERO_KEY, HCI_LINK_KEY_SIZE)) {
+ bt_dev_dbg(hdev, "Ignore NULL link key (ZERO KEY) for %pMR", &ev->bdaddr);
+ return;
+ }
+
bt_dev_dbg(hdev, "");
hci_dev_lock(hdev);
--
2.35.3
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=766763
---Test result---
Test Summary:
CheckPatch FAIL 0.81 seconds
GitLint PASS 0.27 seconds
SubjectPrefix PASS 0.09 seconds
BuildKernel PASS 32.47 seconds
CheckAllWarning PASS 35.57 seconds
CheckSparse WARNING 40.49 seconds
CheckSmatch WARNING 111.98 seconds
BuildKernel32 PASS 31.15 seconds
TestRunnerSetup PASS 476.51 seconds
TestRunner_l2cap-tester PASS 22.02 seconds
TestRunner_iso-tester PASS 40.00 seconds
TestRunner_bnep-tester PASS 10.08 seconds
TestRunner_mgmt-tester PASS 211.97 seconds
TestRunner_rfcomm-tester PASS 15.18 seconds
TestRunner_sco-tester PASS 16.01 seconds
TestRunner_ioctl-tester PASS 16.96 seconds
TestRunner_mesh-tester PASS 12.81 seconds
TestRunner_smp-tester PASS 13.44 seconds
TestRunner_userchan-tester PASS 10.61 seconds
IncrementalBuild PASS 29.63 seconds
Details
##############################
Test: CheckPatch - FAIL
Desc: Run checkpatch.pl script
Output:
[v2] Bluetooth: hci_event: Ignore NULL link key
WARNING: From:/Signed-off-by: email address mismatch: 'From: "Lee, Chun-Yi" <[email protected]>' != 'Signed-off-by: "Lee, Chun-Yi" <[email protected]>'
total: 0 errors, 1 warnings, 0 checks, 12 lines checked
NOTE: For some of the reported defects, checkpatch may be able to
mechanically convert to the typical style using --fix or --fix-inplace.
/github/workspace/src/src/13316718.patch has style problems, please review.
NOTE: Ignored message types: UNKNOWN_COMMIT_ID
NOTE: If any of the errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
##############################
Test: CheckSparse - WARNING
Desc: Run sparse tool with linux kernel
Output:
net/bluetooth/hci_event.c: note: in included file (through include/net/bluetooth/hci_core.h):
##############################
Test: CheckSmatch - WARNING
Desc: Run smatch tool with source
Output:
net/bluetooth/hci_event.c: note: in included file (through include/net/bluetooth/hci_core.h):
---
Regards,
Linux Bluetooth
Dear Chun-Yi,
Thank you for your patch.
Am 18.07.23 um 05:43 schrieb Lee, Chun-Yi <[email protected]>:
[…]
> Signed-off-by: "Lee, Chun-Yi" <[email protected]>
As checkpatch.pl also reports, please make sure the author and
Signed-off-by entry match.
$ git config --global user.name "Chun-Yi Lee"
$ git commit --amend --author="Chun-Yi Lee <[email protected]>" -s
(It’s also common to write the name in the order, so no comma is needed.)
`git format-patch` should not generate a patch with a dedicated `From:`
at the beginning, so you can send it from a different email account. (No
idea, why upstream Linux kernel development shouldn’t work with your
SUSE address.)
Kind regards,
Paul
Hi Paul,
Thanks for your review!
On Tue, Jul 18, 2023 at 07:40:37AM +0200, Paul Menzel wrote:
> Dear Chun-Yi,
>
>
> Thank you for your patch.
>
> Am 18.07.23 um 05:43 schrieb Lee, Chun-Yi <[email protected]>:
>
> […]
>
> > Signed-off-by: "Lee, Chun-Yi" <[email protected]>
>
> As checkpatch.pl also reports, please make sure the author and Signed-off-by
> entry match.
>
> $ git config --global user.name "Chun-Yi Lee"
> $ git commit --amend --author="Chun-Yi Lee <[email protected]>" -s
>
> (It’s also common to write the name in the order, so no comma is needed.)
>
> `git format-patch` should not generate a patch with a dedicated `From:` at
> the beginning, so you can send it from a different email account. (No idea,
> why upstream Linux kernel development shouldn’t work with your SUSE
> address.)
>
I have set the from in .gitconfig and also tried git send-email --from "Lee, Chun-Yi <[email protected]>".
But gmail always modified it to From: Lee, Chun-Yi <[email protected]>. I have no idea why.
In next version, I will put Signed-off-by: "Lee, Chun-Yi" <[email protected]>
to keep the From: to be sync with Signed-off-by.
Thanks a lot!
Joey Lee
Hi Markus,
On Tue, Jul 18, 2023 at 07:50:13AM +0200, Markus Elfring wrote:
> > … Base on the paper, attacker can induce the
> > attacked target to generate …
>
> Would you like to avoid also any wording weaknesses here?
>
>
> > We can ignore null link key in the handler of "Link Key Notification
> > event" to relieve the attack. …
>
> Will corresponding imperative change descriptions become more helpful?
>
> See also:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.5-rc2#n94
>
If possible, could you please direct change my original patch description
for your suggestion? Then I will put it in next version.
Thanks a lot!
Joey Lee
Hi Luiz Augusto von Dentz,
On Tue, Jul 18, 2023 at 10:22:26AM -0700, Luiz Augusto von Dentz wrote:
> Hi Chun-Yi,
>
> On Mon, Jul 17, 2023 at 8:43 PM Lee, Chun-Yi <[email protected]> wrote:
> >
> > This change is used to relieve CVE-2020-26555. The description of the
> > CVE:
> >
> > Bluetooth legacy BR/EDR PIN code pairing in Bluetooth Core Specification
> > 1.0B through 5.2 may permit an unauthenticated nearby device to spoof
> > the BD_ADDR of the peer device to complete pairing without knowledge
> > of the PIN. [1]
>
> Btw, it is probably worth mentioning that in BR/EDR the key generation
> is actually handled in the controller, below HCI.
>
Yes, the key generation be handled by link manager. I will mention it
in patch description.
> > The detail of this attack is in IEEE paper:
> > BlueMirror: Reflections on Bluetooth Pairing and Provisioning Protocols
> > [2]
> >
> > It's a reflection attack. Base on the paper, attacker can induce the
> > attacked target to generate null link key (zero key) without PIN code.
> >
> > We can ignore null link key in the handler of "Link Key Notification
> > event" to relieve the attack. A similar implementation also shows in
> > btstack project. [3]
>
> Perhaps we could clarify this statement by stating that if we ignore
> the link key it means the stack will not consider the device is bonded
> and will not persist the link key, that said the controller will still
> consider it as paired, so I perhaps we should go one step forward and
> disconnect if we detect such a key is being used.
>
I am new on bluetooth field. Did you mean like this patch? Sending
HCI_Disconnect when we found zero link key?
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index ff0c331f53d6..3482031cbbb8 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4698,6 +4700,15 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, void *data,
if (!conn)
goto unlock;
+ /* Ignore NULL link key against CVE-2020-26555 */
+ if (!memcmp(ev->link_key, ZERO_KEY, HCI_LINK_KEY_SIZE)) {
+ bt_dev_dbg(hdev, "Ignore NULL link key (ZERO KEY) for %pMR", &ev->bdaddr);
+ hci_disconnect(conn, HCI_ERROR_AUTH_FAILURE);
+ hci_conn_drop(conn);
+ goto unlock;
+ }
+
hci_conn_hold(conn);
conn->disc_timeout = HCI_DISCONN_TIMEOUT;
hci_conn_drop(conn);
Is there anything I'm missing? Thanks a lot!
> > v2:
> > - Used Link: tag instead of Closes:
> > - Used bt_dev_dbg instead of BT_DBG
> > - Added Fixes: tag
> >
> > Fixes: 55ed8ca10f35 ("Bluetooth: Implement link key handling for the management interface")
> > Link: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26555 [1]
> > Link: https://ieeexplore.ieee.org/abstract/document/9474325/authors#authors [2]
> > Link: https://github.com/bluekitchen/btstack/blob/master/src/hci.c#L3722 [3]
> > Signed-off-by: "Lee, Chun-Yi" <[email protected]>
> > ---
> > net/bluetooth/hci_event.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > index 95816a938cea..ff0c331f53d6 100644
> > --- a/net/bluetooth/hci_event.c
> > +++ b/net/bluetooth/hci_event.c
> > @@ -4684,6 +4684,12 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, void *data,
> > bool persistent;
> > u8 pin_len = 0;
> >
> > + /* Ignore NULL link key against CVE-2020-26555 */
> > + if (!memcmp(ev->link_key, ZERO_KEY, HCI_LINK_KEY_SIZE)) {
> > + bt_dev_dbg(hdev, "Ignore NULL link key (ZERO KEY) for %pMR", &ev->bdaddr);
> > + return;
> > + }
> > +
> > bt_dev_dbg(hdev, "");
> >
> > hci_dev_lock(hdev);
> > --
> > 2.35.3
> >
Thanks a lot!
Joey Lee
Hi Joeyli,
On Wed, Jul 19, 2023 at 5:25 PM Luiz Augusto von Dentz
<[email protected]> wrote:
>
> Hi Joeyli,
>
> On Wed, Jul 19, 2023 at 8:49 AM joeyli <[email protected]> wrote:
> >
> > Hi Luiz Augusto von Dentz,
> >
> > On Tue, Jul 18, 2023 at 10:22:26AM -0700, Luiz Augusto von Dentz wrote:
> > > Hi Chun-Yi,
> > >
> > > On Mon, Jul 17, 2023 at 8:43 PM Lee, Chun-Yi <[email protected]> wrote:
> > > >
> > > > This change is used to relieve CVE-2020-26555. The description of the
> > > > CVE:
> > > >
> > > > Bluetooth legacy BR/EDR PIN code pairing in Bluetooth Core Specification
> > > > 1.0B through 5.2 may permit an unauthenticated nearby device to spoof
> > > > the BD_ADDR of the peer device to complete pairing without knowledge
> > > > of the PIN. [1]
> > >
> > > Btw, it is probably worth mentioning that in BR/EDR the key generation
> > > is actually handled in the controller, below HCI.
> > >
> >
> > Yes, the key generation be handled by link manager. I will mention it
> > in patch description.
> >
> > > > The detail of this attack is in IEEE paper:
> > > > BlueMirror: Reflections on Bluetooth Pairing and Provisioning Protocols
> > > > [2]
> > > >
> > > > It's a reflection attack. Base on the paper, attacker can induce the
> > > > attacked target to generate null link key (zero key) without PIN code.
> > > >
> > > > We can ignore null link key in the handler of "Link Key Notification
> > > > event" to relieve the attack. A similar implementation also shows in
> > > > btstack project. [3]
> > >
> > > Perhaps we could clarify this statement by stating that if we ignore
> > > the link key it means the stack will not consider the device is bonded
> > > and will not persist the link key, that said the controller will still
> > > consider it as paired, so I perhaps we should go one step forward and
> > > disconnect if we detect such a key is being used.
> > >
> >
> > I am new on bluetooth field. Did you mean like this patch? Sending
> > HCI_Disconnect when we found zero link key?
> >
> > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > index ff0c331f53d6..3482031cbbb8 100644
> > --- a/net/bluetooth/hci_event.c
> > +++ b/net/bluetooth/hci_event.c
> > @@ -4698,6 +4700,15 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, void *data,
> > if (!conn)
> > goto unlock;
> >
> > + /* Ignore NULL link key against CVE-2020-26555 */
> > + if (!memcmp(ev->link_key, ZERO_KEY, HCI_LINK_KEY_SIZE)) {
> > + bt_dev_dbg(hdev, "Ignore NULL link key (ZERO KEY) for %pMR", &ev->bdaddr);
> > + hci_disconnect(conn, HCI_ERROR_AUTH_FAILURE);
> > + hci_conn_drop(conn);
> > + goto unlock;
> > + }
>
> Yeah, something like that should do it, btw I hope you are testing
> these changes do actually work properly, even better if you could
> introduce a test into the likes of mgmt-tester to generate a ZERO_KEY
> so we are not caught by surprise if something doesn't quite work as
> expected, or some change cause a regression where this key is accepted
> again.
Are you still planning on updating these changes so we can apply it?
> > hci_conn_hold(conn);
> > conn->disc_timeout = HCI_DISCONN_TIMEOUT;
> > hci_conn_drop(conn);
> >
> >
> > Is there anything I'm missing? Thanks a lot!
> >
> > > > v2:
> > > > - Used Link: tag instead of Closes:
> > > > - Used bt_dev_dbg instead of BT_DBG
> > > > - Added Fixes: tag
> > > >
> > > > Fixes: 55ed8ca10f35 ("Bluetooth: Implement link key handling for the management interface")
> > > > Link: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26555 [1]
> > > > Link: https://ieeexplore.ieee.org/abstract/document/9474325/authors#authors [2]
> > > > Link: https://github.com/bluekitchen/btstack/blob/master/src/hci.c#L3722 [3]
> > > > Signed-off-by: "Lee, Chun-Yi" <[email protected]>
> > > > ---
> > > > net/bluetooth/hci_event.c | 6 ++++++
> > > > 1 file changed, 6 insertions(+)
> > > >
> > > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > > > index 95816a938cea..ff0c331f53d6 100644
> > > > --- a/net/bluetooth/hci_event.c
> > > > +++ b/net/bluetooth/hci_event.c
> > > > @@ -4684,6 +4684,12 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, void *data,
> > > > bool persistent;
> > > > u8 pin_len = 0;
> > > >
> > > > + /* Ignore NULL link key against CVE-2020-26555 */
> > > > + if (!memcmp(ev->link_key, ZERO_KEY, HCI_LINK_KEY_SIZE)) {
> > > > + bt_dev_dbg(hdev, "Ignore NULL link key (ZERO KEY) for %pMR", &ev->bdaddr);
> > > > + return;
> > > > + }
> > > > +
> > > > bt_dev_dbg(hdev, "");
> > > >
> > > > hci_dev_lock(hdev);
> > > > --
> > > > 2.35.3
> > > >
> >
> > Thanks a lot!
> > Joey Lee
>
>
>
> --
> Luiz Augusto von Dentz
--
Luiz Augusto von Dentz
Hi Luiz Augusto von Dentz,
On Thu, Jul 27, 2023 at 03:29:42PM -0700, Luiz Augusto von Dentz wrote:
> Hi Joeyli,
>
> On Wed, Jul 19, 2023 at 5:25 PM Luiz Augusto von Dentz
> <[email protected]> wrote:
> >
> > Hi Joeyli,
> >
> > On Wed, Jul 19, 2023 at 8:49 AM joeyli <[email protected]> wrote:
> > >
> > > Hi Luiz Augusto von Dentz,
> > >
> > > On Tue, Jul 18, 2023 at 10:22:26AM -0700, Luiz Augusto von Dentz wrote:
> > > > Hi Chun-Yi,
> > > >
> > > > On Mon, Jul 17, 2023 at 8:43 PM Lee, Chun-Yi <[email protected]> wrote:
> > > > >
> > > > > This change is used to relieve CVE-2020-26555. The description of the
> > > > > CVE:
> > > > >
> > > > > Bluetooth legacy BR/EDR PIN code pairing in Bluetooth Core Specification
> > > > > 1.0B through 5.2 may permit an unauthenticated nearby device to spoof
> > > > > the BD_ADDR of the peer device to complete pairing without knowledge
> > > > > of the PIN. [1]
> > > >
> > > > Btw, it is probably worth mentioning that in BR/EDR the key generation
> > > > is actually handled in the controller, below HCI.
> > > >
> > >
> > > Yes, the key generation be handled by link manager. I will mention it
> > > in patch description.
> > >
> > > > > The detail of this attack is in IEEE paper:
> > > > > BlueMirror: Reflections on Bluetooth Pairing and Provisioning Protocols
> > > > > [2]
> > > > >
> > > > > It's a reflection attack. Base on the paper, attacker can induce the
> > > > > attacked target to generate null link key (zero key) without PIN code.
> > > > >
> > > > > We can ignore null link key in the handler of "Link Key Notification
> > > > > event" to relieve the attack. A similar implementation also shows in
> > > > > btstack project. [3]
> > > >
> > > > Perhaps we could clarify this statement by stating that if we ignore
> > > > the link key it means the stack will not consider the device is bonded
> > > > and will not persist the link key, that said the controller will still
> > > > consider it as paired, so I perhaps we should go one step forward and
> > > > disconnect if we detect such a key is being used.
> > > >
> > >
> > > I am new on bluetooth field. Did you mean like this patch? Sending
> > > HCI_Disconnect when we found zero link key?
> > >
> > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > > index ff0c331f53d6..3482031cbbb8 100644
> > > --- a/net/bluetooth/hci_event.c
> > > +++ b/net/bluetooth/hci_event.c
> > > @@ -4698,6 +4700,15 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, void *data,
> > > if (!conn)
> > > goto unlock;
> > >
> > > + /* Ignore NULL link key against CVE-2020-26555 */
> > > + if (!memcmp(ev->link_key, ZERO_KEY, HCI_LINK_KEY_SIZE)) {
> > > + bt_dev_dbg(hdev, "Ignore NULL link key (ZERO KEY) for %pMR", &ev->bdaddr);
> > > + hci_disconnect(conn, HCI_ERROR_AUTH_FAILURE);
> > > + hci_conn_drop(conn);
> > > + goto unlock;
> > > + }
> >
> > Yeah, something like that should do it, btw I hope you are testing
> > these changes do actually work properly, even better if you could
> > introduce a test into the likes of mgmt-tester to generate a ZERO_KEY
> > so we are not caught by surprise if something doesn't quite work as
> > expected, or some change cause a regression where this key is accepted
> > again.
>
> Are you still planning on updating these changes so we can apply it?
>
Sorry for my delay! I am stucking at other stuff.
I will improve the patch and send new version again.
THanks a lot!
Joey Lee
> > > hci_conn_hold(conn);
> > > conn->disc_timeout = HCI_DISCONN_TIMEOUT;
> > > hci_conn_drop(conn);
> > >
> > >
> > > Is there anything I'm missing? Thanks a lot!
> > >
> > > > > v2:
> > > > > - Used Link: tag instead of Closes:
> > > > > - Used bt_dev_dbg instead of BT_DBG
> > > > > - Added Fixes: tag
> > > > >
> > > > > Fixes: 55ed8ca10f35 ("Bluetooth: Implement link key handling for the management interface")
> > > > > Link: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26555 [1]
> > > > > Link: https://ieeexplore.ieee.org/abstract/document/9474325/authors#authors [2]
> > > > > Link: https://github.com/bluekitchen/btstack/blob/master/src/hci.c#L3722 [3]
> > > > > Signed-off-by: "Lee, Chun-Yi" <[email protected]>
> > > > > ---
> > > > > net/bluetooth/hci_event.c | 6 ++++++
> > > > > 1 file changed, 6 insertions(+)
> > > > >
> > > > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > > > > index 95816a938cea..ff0c331f53d6 100644
> > > > > --- a/net/bluetooth/hci_event.c
> > > > > +++ b/net/bluetooth/hci_event.c
> > > > > @@ -4684,6 +4684,12 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, void *data,
> > > > > bool persistent;
> > > > > u8 pin_len = 0;
> > > > >
> > > > > + /* Ignore NULL link key against CVE-2020-26555 */
> > > > > + if (!memcmp(ev->link_key, ZERO_KEY, HCI_LINK_KEY_SIZE)) {
> > > > > + bt_dev_dbg(hdev, "Ignore NULL link key (ZERO KEY) for %pMR", &ev->bdaddr);
> > > > > + return;
> > > > > + }
> > > > > +
> > > > > bt_dev_dbg(hdev, "");
> > > > >
> > > > > hci_dev_lock(hdev);
> > > > > --
> > > > > 2.35.3
> > > > >
> > >
> > > Thanks a lot!
> > > Joey Lee
> >
> >
> >
> > --
> > Luiz Augusto von Dentz
>
>
>
> --
> Luiz Augusto von Dentz