diff options
| -rw-r--r-- | net/bluetooth/smp.c | 75 |
1 files changed, 67 insertions, 8 deletions
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c index 60180b47ce71..6a5afb972358 100644 --- a/net/bluetooth/smp.c +++ b/net/bluetooth/smp.c @@ -880,6 +880,12 @@ static int tk_request(struct l2cap_conn *conn, u8 remote_oob, u8 auth, return 0; } + /* If this function is used for SC -> legacy fallback we + * can only recover the just-works case. + */ + if (test_bit(SMP_FLAG_SC, &smp->flags)) + return -EINVAL; + /* Not Just Works/Confirm results in MITM Authentication */ if (smp->method != JUST_CFM) { set_bit(SMP_FLAG_MITM_AUTH, &smp->flags); @@ -1806,6 +1812,13 @@ static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb) clear_bit(SMP_FLAG_INITIATOR, &smp->flags); + /* Strictly speaking we shouldn't allow Pairing Confirm for the + * SC case, however some implementations incorrectly copy RFU auth + * req bits from our security request, which may create a false + * positive SC enablement. + */ + SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM); + if (test_bit(SMP_FLAG_SC, &smp->flags)) { SMP_ALLOW_CMD(smp, SMP_CMD_PUBLIC_KEY); /* Clear bits which are generated but not distributed */ @@ -1814,8 +1827,6 @@ static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb) return 0; } - SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM); - /* Request setup of TK */ ret = tk_request(conn, 0, auth, rsp.io_capability, req->io_capability); if (ret) @@ -1981,10 +1992,6 @@ static u8 sc_check_confirm(struct smp_chan *smp) BT_DBG(""); - /* Public Key exchange must happen before any other steps */ - if (!test_bit(SMP_FLAG_REMOTE_PK, &smp->flags)) - return SMP_UNSPECIFIED; - if (smp->method == REQ_PASSKEY || smp->method == DSP_PASSKEY) return sc_passkey_round(smp, SMP_CMD_PAIRING_CONFIRM); @@ -1997,6 +2004,47 @@ static u8 sc_check_confirm(struct smp_chan *smp) return 0; } +/* Work-around for some implementations that incorrectly copy RFU bits + * from our security request and thereby create the impression that + * we're doing SC when in fact the remote doesn't support it. + */ +static int fixup_sc_false_positive(struct smp_chan *smp) +{ + struct l2cap_conn *conn = smp->conn; + struct hci_conn *hcon = conn->hcon; + struct hci_dev *hdev = hcon->hdev; + struct smp_cmd_pairing *req, *rsp; + u8 auth; + + /* The issue is only observed when we're in slave role */ + if (hcon->out) + return SMP_UNSPECIFIED; + + if (hci_dev_test_flag(hdev, HCI_SC_ONLY)) { + BT_ERR("Refusing SMP SC -> legacy fallback in SC-only mode"); + return SMP_UNSPECIFIED; + } + + BT_ERR("Trying to fall back to legacy SMP"); + + req = (void *) &smp->preq[1]; + rsp = (void *) &smp->prsp[1]; + + /* Rebuild key dist flags which may have been cleared for SC */ + smp->remote_key_dist = (req->init_key_dist & rsp->resp_key_dist); + + auth = req->auth_req & AUTH_REQ_MASK(hdev); + + if (tk_request(conn, 0, auth, rsp->io_capability, req->io_capability)) { + BT_ERR("Failed to fall back to legacy SMP"); + return SMP_UNSPECIFIED; + } + + clear_bit(SMP_FLAG_SC, &smp->flags); + + return 0; +} + static u8 smp_cmd_pairing_confirm(struct l2cap_conn *conn, struct sk_buff *skb) { struct l2cap_chan *chan = conn->smp; @@ -2010,8 +2058,19 @@ static u8 smp_cmd_pairing_confirm(struct l2cap_conn *conn, struct sk_buff *skb) memcpy(smp->pcnf, skb->data, sizeof(smp->pcnf)); skb_pull(skb, sizeof(smp->pcnf)); - if (test_bit(SMP_FLAG_SC, &smp->flags)) - return sc_check_confirm(smp); + if (test_bit(SMP_FLAG_SC, &smp->flags)) { + int ret; + + /* Public Key exchange must happen before any other steps */ + if (test_bit(SMP_FLAG_REMOTE_PK, &smp->flags)) + return sc_check_confirm(smp); + + BT_ERR("Unexpected SMP Pairing Confirm"); + + ret = fixup_sc_false_positive(smp); + if (ret) + return ret; + } if (conn->hcon->out) { smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd), |