Bluetooth: Fix DHKey Check sending order for slave role

According to the LE SC specification the initiating device sends its
DHKey check first and the non-initiating devices sends its DHKey check
as a response to this. It's also important that the non-initiating
device doesn't send the response if it's still waiting for user input.
In order to synchronize all this a new flag is added.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 43 insertions, 17 deletions

diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 8cfa1c1b205c..9a4ce4581475 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -56,6 +56,7 @@ enum {
         SMP_FLAG_REMOTE_PK,
         SMP_FLAG_DEBUG_KEY,
         SMP_FLAG_WAIT_USER,
+        SMP_FLAG_DHKEY_PENDING,
 };
 
 struct smp_chan {
@@ -994,6 +995,29 @@ static void smp_notify_keys(struct l2cap_conn *conn)
         }
 }
 
+static void sc_add_ltk(struct smp_chan *smp)
+{
+        struct hci_conn *hcon = smp->conn->hcon;
+        u8 key_type, auth;
+
+        if (test_bit(SMP_FLAG_DEBUG_KEY, &smp->flags))
+                key_type = SMP_LTK_P256_DEBUG;
+        else
+                key_type = SMP_LTK_P256;
+
+        if (hcon->pending_sec_level == BT_SECURITY_FIPS)
+                auth = 1;
+        else
+                auth = 0;
+
+        memset(smp->tk + smp->enc_key_size, 0,
+               SMP_MAX_ENC_KEY_SIZE - smp->enc_key_size);
+
+        smp->ltk = hci_add_ltk(hcon->hdev, &hcon->dst, hcon->dst_type,
+                               key_type, auth, smp->tk, smp->enc_key_size,
+                               0, 0);
+}
+
 static void sc_generate_link_key(struct smp_chan *smp)
 {
         /* These constants are as specified in the core specification.
@@ -1312,12 +1336,10 @@ static u8 sc_passkey_round(struct smp_chan *smp, u8 smp_op)
                 if (!hcon->out) {
                         smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM,
                                      sizeof(smp->prnd), smp->prnd);
-                        if (smp->passkey_round == 20) {
-                                sc_dhkey_check(smp);
+                        if (smp->passkey_round == 20)
                                 SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK);
-                        } else {
+                        else
                                 SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM);
-                        }
                         return 0;
                 }
 
@@ -1394,7 +1416,14 @@ static int sc_user_reply(struct smp_chan *smp, u16 mgmt_op, __le32 passkey)
                 return 0;
         }
 
-        sc_dhkey_check(smp);
+        /* Initiator sends DHKey check first */
+        if (hcon->out) {
+                sc_dhkey_check(smp);
+                SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK);
+        } else if (test_and_clear_bit(SMP_FLAG_DHKEY_PENDING, &smp->flags)) {
+                sc_dhkey_check(smp);
+                sc_add_ltk(smp);
+        }
 
         return 0;
 }
@@ -2262,7 +2291,6 @@ static int smp_cmd_dhkey_check(struct l2cap_conn *conn, struct sk_buff *skb)
         struct smp_chan *smp = chan->data;
         u8 a[7], b[7], *local_addr, *remote_addr;
         u8 io_cap[3], r[16], e[16];
-        u8 key_type, auth;
         int err;
 
         BT_DBG("conn %p", conn);
@@ -2298,19 +2326,17 @@ static int smp_cmd_dhkey_check(struct l2cap_conn *conn, struct sk_buff *skb)
         if (memcmp(check->e, e, 16))
                 return SMP_DHKEY_CHECK_FAILED;
 
-        if (test_bit(SMP_FLAG_DEBUG_KEY, &smp->flags))
-                key_type = SMP_LTK_P256_DEBUG;
-        else
-                key_type = SMP_LTK_P256;
+        if (!hcon->out) {
+                if (test_bit(SMP_FLAG_WAIT_USER, &smp->flags)) {
+                        set_bit(SMP_FLAG_DHKEY_PENDING, &smp->flags);
+                        return 0;
+                }
 
-        if (hcon->pending_sec_level == BT_SECURITY_FIPS)
-                auth = 1;
-        else
-                auth = 0;
+                /* Slave sends DHKey check as response to master */
+                sc_dhkey_check(smp);
+        }
 
-        smp->ltk = hci_add_ltk(hcon->hdev, &hcon->dst, hcon->dst_type,
-                               key_type, auth, smp->tk, smp->enc_key_size,
-                               0, 0);
+        sc_add_ltk(smp);
 
         if (hcon->out) {
                 hci_le_start_enc(hcon, 0, 0, smp->tk);