| Message ID | 20200921155004.v2.1.I67a8b8cd4def8166970ca37109db46d731b62bb6@changeid |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] Bluetooth: Check for encryption key size on connect | expand |
Hi Archie, On Mon, Sep 21, 2020 at 12:56 AM Archie Pusaka <apusaka@google.com> wrote: > > From: Archie Pusaka <apusaka@chromium.org> > > When receiving connection, we only check whether the link has been > encrypted, but not the encryption key size of the link. > > This patch adds check for encryption key size, and reject L2CAP > connection which size is below the specified threshold (default 7) > with security block. > > Here is some btmon trace. > @ MGMT Event: New Link Key (0x0009) plen 26 {0x0001} [hci0] 5.847722 > Store hint: No (0x00) > BR/EDR Address: 38:00:25:F7:F1:B0 (OUI 38-00-25) > Key type: Unauthenticated Combination key from P-192 (0x04) > Link key: 7bf2f68c81305d63a6b0ee2c5a7a34bc > PIN length: 0 > > HCI Event: Encryption Change (0x08) plen 4 #29 [hci0] 5.871537 > Status: Success (0x00) > Handle: 256 > Encryption: Enabled with E0 (0x01) > < HCI Command: Read Encryp... (0x05|0x0008) plen 2 #30 [hci0] 5.871609 > Handle: 256 > > HCI Event: Command Complete (0x0e) plen 7 #31 [hci0] 5.872524 > Read Encryption Key Size (0x05|0x0008) ncmd 1 > Status: Success (0x00) > Handle: 256 > Key size: 3 > > ////// WITHOUT PATCH ////// > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 5.895023 > L2CAP: Connection Request (0x02) ident 3 len 4 > PSM: 4097 (0x1001) > Source CID: 64 > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 5.895213 > L2CAP: Connection Response (0x03) ident 3 len 8 > Destination CID: 64 > Source CID: 64 > Result: Connection successful (0x0000) > Status: No further information available (0x0000) > > ////// WITH PATCH ////// > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 4.887024 > L2CAP: Connection Request (0x02) ident 3 len 4 > PSM: 4097 (0x1001) > Source CID: 64 > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 4.887127 > L2CAP: Connection Response (0x03) ident 3 len 8 > Destination CID: 0 > Source CID: 64 > Result: Connection refused - security block (0x0003) > Status: No further information available (0x0000) > > Signed-off-by: Archie Pusaka <apusaka@chromium.org> > Reviewed-by: Alain Michaud <alainm@chromium.org> > > --- > Btw, it looks like the patch sent by Alex Lu with the title > [PATCH] Bluetooth: Fix the vulnerable issue on enc key size > also solves the exact same issue. > > Changes in v2: > * Add btmon trace to the commit message > > net/bluetooth/l2cap_core.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c > index ade83e224567..b4fc0ad38aaa 100644 > --- a/net/bluetooth/l2cap_core.c > +++ b/net/bluetooth/l2cap_core.c > @@ -4101,7 +4101,8 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, > > /* Check if the ACL is secure enough (if not SDP) */ > if (psm != cpu_to_le16(L2CAP_PSM_SDP) && > - !hci_conn_check_link_mode(conn->hcon)) { > + (!hci_conn_check_link_mode(conn->hcon) || > + !l2cap_check_enc_key_size(conn->hcon))) { I wonder if we couldn't incorporate the check of key size into hci_conn_check_link_mode, like I said in the first patch checking the enc key size should not be specific to L2CAP. > conn->disc_reason = HCI_ERROR_AUTH_FAILURE; > result = L2CAP_CR_SEC_BLOCK; > goto response; > -- > 2.28.0.681.g6f77f65b4e-goog > -- Luiz Augusto von Dentz
Hi Luiz, On Tue, 22 Sep 2020 at 01:15, Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote: > > Hi Archie, > > > On Mon, Sep 21, 2020 at 12:56 AM Archie Pusaka <apusaka@google.com> wrote: > > > > From: Archie Pusaka <apusaka@chromium.org> > > > > When receiving connection, we only check whether the link has been > > encrypted, but not the encryption key size of the link. > > > > This patch adds check for encryption key size, and reject L2CAP > > connection which size is below the specified threshold (default 7) > > with security block. > > > > Here is some btmon trace. > > @ MGMT Event: New Link Key (0x0009) plen 26 {0x0001} [hci0] 5.847722 > > Store hint: No (0x00) > > BR/EDR Address: 38:00:25:F7:F1:B0 (OUI 38-00-25) > > Key type: Unauthenticated Combination key from P-192 (0x04) > > Link key: 7bf2f68c81305d63a6b0ee2c5a7a34bc > > PIN length: 0 > > > HCI Event: Encryption Change (0x08) plen 4 #29 [hci0] 5.871537 > > Status: Success (0x00) > > Handle: 256 > > Encryption: Enabled with E0 (0x01) > > < HCI Command: Read Encryp... (0x05|0x0008) plen 2 #30 [hci0] 5.871609 > > Handle: 256 > > > HCI Event: Command Complete (0x0e) plen 7 #31 [hci0] 5.872524 > > Read Encryption Key Size (0x05|0x0008) ncmd 1 > > Status: Success (0x00) > > Handle: 256 > > Key size: 3 > > > > ////// WITHOUT PATCH ////// > > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 5.895023 > > L2CAP: Connection Request (0x02) ident 3 len 4 > > PSM: 4097 (0x1001) > > Source CID: 64 > > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 5.895213 > > L2CAP: Connection Response (0x03) ident 3 len 8 > > Destination CID: 64 > > Source CID: 64 > > Result: Connection successful (0x0000) > > Status: No further information available (0x0000) > > > > ////// WITH PATCH ////// > > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 4.887024 > > L2CAP: Connection Request (0x02) ident 3 len 4 > > PSM: 4097 (0x1001) > > Source CID: 64 > > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 4.887127 > > L2CAP: Connection Response (0x03) ident 3 len 8 > > Destination CID: 0 > > Source CID: 64 > > Result: Connection refused - security block (0x0003) > > Status: No further information available (0x0000) > > > > Signed-off-by: Archie Pusaka <apusaka@chromium.org> > > Reviewed-by: Alain Michaud <alainm@chromium.org> > > > > --- > > Btw, it looks like the patch sent by Alex Lu with the title > > [PATCH] Bluetooth: Fix the vulnerable issue on enc key size > > also solves the exact same issue. > > > > Changes in v2: > > * Add btmon trace to the commit message > > > > net/bluetooth/l2cap_core.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c > > index ade83e224567..b4fc0ad38aaa 100644 > > --- a/net/bluetooth/l2cap_core.c > > +++ b/net/bluetooth/l2cap_core.c > > @@ -4101,7 +4101,8 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, > > > > /* Check if the ACL is secure enough (if not SDP) */ > > if (psm != cpu_to_le16(L2CAP_PSM_SDP) && > > - !hci_conn_check_link_mode(conn->hcon)) { > > + (!hci_conn_check_link_mode(conn->hcon) || > > + !l2cap_check_enc_key_size(conn->hcon))) { > > I wonder if we couldn't incorporate the check of key size into > hci_conn_check_link_mode, like I said in the first patch checking the > enc key size should not be specific to L2CAP. Yes, I could move the check into hci_conn_check_link_mode. At first look, this function is also called by AMP which I am not familiar with. In addition, I found this patch which moves this check outside hci_conn, so I have my doubts there. https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/commit/?id=693cd8ce3f882524a5d06f7800dd8492411877b3 > > > conn->disc_reason = HCI_ERROR_AUTH_FAILURE; > > result = L2CAP_CR_SEC_BLOCK; > > goto response; > > -- > > 2.28.0.681.g6f77f65b4e-goog > > > > > -- > Luiz Augusto von Dentz Thanks, Archie
Hi Archie, On Tue, Sep 22, 2020 at 12:48 AM Archie Pusaka <apusaka@google.com> wrote: > > Hi Luiz, > > On Tue, 22 Sep 2020 at 01:15, Luiz Augusto von Dentz > <luiz.dentz@gmail.com> wrote: > > > > Hi Archie, > > > > > > On Mon, Sep 21, 2020 at 12:56 AM Archie Pusaka <apusaka@google.com> wrote: > > > > > > From: Archie Pusaka <apusaka@chromium.org> > > > > > > When receiving connection, we only check whether the link has been > > > encrypted, but not the encryption key size of the link. > > > > > > This patch adds check for encryption key size, and reject L2CAP > > > connection which size is below the specified threshold (default 7) > > > with security block. > > > > > > Here is some btmon trace. > > > @ MGMT Event: New Link Key (0x0009) plen 26 {0x0001} [hci0] 5.847722 > > > Store hint: No (0x00) > > > BR/EDR Address: 38:00:25:F7:F1:B0 (OUI 38-00-25) > > > Key type: Unauthenticated Combination key from P-192 (0x04) > > > Link key: 7bf2f68c81305d63a6b0ee2c5a7a34bc > > > PIN length: 0 > > > > HCI Event: Encryption Change (0x08) plen 4 #29 [hci0] 5.871537 > > > Status: Success (0x00) > > > Handle: 256 > > > Encryption: Enabled with E0 (0x01) > > > < HCI Command: Read Encryp... (0x05|0x0008) plen 2 #30 [hci0] 5.871609 > > > Handle: 256 > > > > HCI Event: Command Complete (0x0e) plen 7 #31 [hci0] 5.872524 > > > Read Encryption Key Size (0x05|0x0008) ncmd 1 > > > Status: Success (0x00) > > > Handle: 256 > > > Key size: 3 > > > > > > ////// WITHOUT PATCH ////// > > > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 5.895023 > > > L2CAP: Connection Request (0x02) ident 3 len 4 > > > PSM: 4097 (0x1001) > > > Source CID: 64 > > > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 5.895213 > > > L2CAP: Connection Response (0x03) ident 3 len 8 > > > Destination CID: 64 > > > Source CID: 64 > > > Result: Connection successful (0x0000) > > > Status: No further information available (0x0000) > > > > > > ////// WITH PATCH ////// > > > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 4.887024 > > > L2CAP: Connection Request (0x02) ident 3 len 4 > > > PSM: 4097 (0x1001) > > > Source CID: 64 > > > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 4.887127 > > > L2CAP: Connection Response (0x03) ident 3 len 8 > > > Destination CID: 0 > > > Source CID: 64 > > > Result: Connection refused - security block (0x0003) > > > Status: No further information available (0x0000) > > > > > > Signed-off-by: Archie Pusaka <apusaka@chromium.org> > > > Reviewed-by: Alain Michaud <alainm@chromium.org> > > > > > > --- > > > Btw, it looks like the patch sent by Alex Lu with the title > > > [PATCH] Bluetooth: Fix the vulnerable issue on enc key size > > > also solves the exact same issue. > > > > > > Changes in v2: > > > * Add btmon trace to the commit message > > > > > > net/bluetooth/l2cap_core.c | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c > > > index ade83e224567..b4fc0ad38aaa 100644 > > > --- a/net/bluetooth/l2cap_core.c > > > +++ b/net/bluetooth/l2cap_core.c > > > @@ -4101,7 +4101,8 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, > > > > > > /* Check if the ACL is secure enough (if not SDP) */ > > > if (psm != cpu_to_le16(L2CAP_PSM_SDP) && > > > - !hci_conn_check_link_mode(conn->hcon)) { > > > + (!hci_conn_check_link_mode(conn->hcon) || > > > + !l2cap_check_enc_key_size(conn->hcon))) { > > > > I wonder if we couldn't incorporate the check of key size into > > hci_conn_check_link_mode, like I said in the first patch checking the > > enc key size should not be specific to L2CAP. > > Yes, I could move the check into hci_conn_check_link_mode. > At first look, this function is also called by AMP which I am not > familiar with. In addition, I found this patch which moves this check > outside hci_conn, so I have my doubts there. > https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/commit/?id=693cd8ce3f882524a5d06f7800dd8492411877b3 Right, I think we can have it as part of the hci_conn_check_link_mode, that said it is perhaps better to have it as hci_conn_check_enc_key_size instead as it is not L2CAP expecific. Other than that it looks good to me. > > > > > conn->disc_reason = HCI_ERROR_AUTH_FAILURE; > > > result = L2CAP_CR_SEC_BLOCK; > > > goto response; > > > -- > > > 2.28.0.681.g6f77f65b4e-goog > > > > > > > > > -- > > Luiz Augusto von Dentz > > Thanks, > Archie -- Luiz Augusto von Dentz
Hi Luiz, On Wed, 23 Sep 2020 at 01:03, Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote: > > Hi Archie, > > On Tue, Sep 22, 2020 at 12:48 AM Archie Pusaka <apusaka@google.com> wrote: > > > > Hi Luiz, > > > > On Tue, 22 Sep 2020 at 01:15, Luiz Augusto von Dentz > > <luiz.dentz@gmail.com> wrote: > > > > > > Hi Archie, > > > > > > > > > On Mon, Sep 21, 2020 at 12:56 AM Archie Pusaka <apusaka@google.com> wrote: > > > > > > > > From: Archie Pusaka <apusaka@chromium.org> > > > > > > > > When receiving connection, we only check whether the link has been > > > > encrypted, but not the encryption key size of the link. > > > > > > > > This patch adds check for encryption key size, and reject L2CAP > > > > connection which size is below the specified threshold (default 7) > > > > with security block. > > > > > > > > Here is some btmon trace. > > > > @ MGMT Event: New Link Key (0x0009) plen 26 {0x0001} [hci0] 5.847722 > > > > Store hint: No (0x00) > > > > BR/EDR Address: 38:00:25:F7:F1:B0 (OUI 38-00-25) > > > > Key type: Unauthenticated Combination key from P-192 (0x04) > > > > Link key: 7bf2f68c81305d63a6b0ee2c5a7a34bc > > > > PIN length: 0 > > > > > HCI Event: Encryption Change (0x08) plen 4 #29 [hci0] 5.871537 > > > > Status: Success (0x00) > > > > Handle: 256 > > > > Encryption: Enabled with E0 (0x01) > > > > < HCI Command: Read Encryp... (0x05|0x0008) plen 2 #30 [hci0] 5.871609 > > > > Handle: 256 > > > > > HCI Event: Command Complete (0x0e) plen 7 #31 [hci0] 5.872524 > > > > Read Encryption Key Size (0x05|0x0008) ncmd 1 > > > > Status: Success (0x00) > > > > Handle: 256 > > > > Key size: 3 > > > > > > > > ////// WITHOUT PATCH ////// > > > > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 5.895023 > > > > L2CAP: Connection Request (0x02) ident 3 len 4 > > > > PSM: 4097 (0x1001) > > > > Source CID: 64 > > > > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 5.895213 > > > > L2CAP: Connection Response (0x03) ident 3 len 8 > > > > Destination CID: 64 > > > > Source CID: 64 > > > > Result: Connection successful (0x0000) > > > > Status: No further information available (0x0000) > > > > > > > > ////// WITH PATCH ////// > > > > > ACL Data RX: Handle 256 flags 0x02 dlen 12 #42 [hci0] 4.887024 > > > > L2CAP: Connection Request (0x02) ident 3 len 4 > > > > PSM: 4097 (0x1001) > > > > Source CID: 64 > > > > < ACL Data TX: Handle 256 flags 0x00 dlen 16 #43 [hci0] 4.887127 > > > > L2CAP: Connection Response (0x03) ident 3 len 8 > > > > Destination CID: 0 > > > > Source CID: 64 > > > > Result: Connection refused - security block (0x0003) > > > > Status: No further information available (0x0000) > > > > > > > > Signed-off-by: Archie Pusaka <apusaka@chromium.org> > > > > Reviewed-by: Alain Michaud <alainm@chromium.org> > > > > > > > > --- > > > > Btw, it looks like the patch sent by Alex Lu with the title > > > > [PATCH] Bluetooth: Fix the vulnerable issue on enc key size > > > > also solves the exact same issue. > > > > > > > > Changes in v2: > > > > * Add btmon trace to the commit message > > > > > > > > net/bluetooth/l2cap_core.c | 3 ++- > > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c > > > > index ade83e224567..b4fc0ad38aaa 100644 > > > > --- a/net/bluetooth/l2cap_core.c > > > > +++ b/net/bluetooth/l2cap_core.c > > > > @@ -4101,7 +4101,8 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, > > > > > > > > /* Check if the ACL is secure enough (if not SDP) */ > > > > if (psm != cpu_to_le16(L2CAP_PSM_SDP) && > > > > - !hci_conn_check_link_mode(conn->hcon)) { > > > > + (!hci_conn_check_link_mode(conn->hcon) || > > > > + !l2cap_check_enc_key_size(conn->hcon))) { > > > > > > I wonder if we couldn't incorporate the check of key size into > > > hci_conn_check_link_mode, like I said in the first patch checking the > > > enc key size should not be specific to L2CAP. > > > > Yes, I could move the check into hci_conn_check_link_mode. > > At first look, this function is also called by AMP which I am not > > familiar with. In addition, I found this patch which moves this check > > outside hci_conn, so I have my doubts there. > > https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/commit/?id=693cd8ce3f882524a5d06f7800dd8492411877b3 > > Right, I think we can have it as part of the hci_conn_check_link_mode, > that said it is perhaps better to have it as > hci_conn_check_enc_key_size instead as it is not L2CAP expecific. > Other than that it looks good to me. Do you mean we should move l2cap_conn_check_enc_key_size to hci_conn_check_enc_key_size? I think that is a good idea. We also have hci_conn_check_secure which I am unsure what the purpose is. I'll try to merge them together. > > > > > > > > conn->disc_reason = HCI_ERROR_AUTH_FAILURE; > > > > result = L2CAP_CR_SEC_BLOCK; > > > > goto response; > > > > -- > > > > 2.28.0.681.g6f77f65b4e-goog > > > > > > > > > > > > > -- > > > Luiz Augusto von Dentz > > > > Thanks, > > Archie > > > > -- > Luiz Augusto von Dentz Thanks, Archie
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index ade83e224567..b4fc0ad38aaa 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -4101,7 +4101,8 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, /* Check if the ACL is secure enough (if not SDP) */ if (psm != cpu_to_le16(L2CAP_PSM_SDP) && - !hci_conn_check_link_mode(conn->hcon)) { + (!hci_conn_check_link_mode(conn->hcon) || + !l2cap_check_enc_key_size(conn->hcon))) { conn->disc_reason = HCI_ERROR_AUTH_FAILURE; result = L2CAP_CR_SEC_BLOCK; goto response;