From 36d16f1e59fd173df576a94b2c017ecc6de9e87c Mon Sep 17 00:00:00 2001
From: Sumeet Singh <sumeet.singh@espressif.com>
Date: Sat, 7 Sep 2024 17:08:40 +0800
Subject: [PATCH] feat(nimble): Added host config to enable or disable SC Only
 mode during runtime

---
 nimble/host/include/host/ble_hs.h | 8 ++++++++
 nimble/host/src/ble_att_svr.c     | 2 +-
 nimble/host/src/ble_hs_cfg.c      | 1 +
 nimble/host/src/ble_sm.c          | 4 ++--
 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/nimble/host/include/host/ble_hs.h b/nimble/host/include/host/ble_hs.h
index 4eba4b440..9aa6b88c7 100644
--- a/nimble/host/include/host/ble_hs.h
+++ b/nimble/host/include/host/ble_hs.h
@@ -315,6 +315,14 @@ struct ble_hs_cfg {
      */
     unsigned sm_sc:1;
 
+    /** @brief Security Manager - Enable/Disable Secure Connections Only flag
+     *
+     * If set, this will enforce P-256 elliptic curve encryption algorithm
+     * during pairing.
+     * It will force the max key size to be used during pairing.
+     */
+    unsigned sm_sc_only:1;
+
     /** @brief Security Manager Key Press Notification flag
      *
      * Currently unsupported and should not be set.
diff --git a/nimble/host/src/ble_att_svr.c b/nimble/host/src/ble_att_svr.c
index 4190db9ca..f9f688f00 100644
--- a/nimble/host/src/ble_att_svr.c
+++ b/nimble/host/src/ble_att_svr.c
@@ -325,7 +325,7 @@ ble_att_svr_check_perms(uint16_t conn_handle, int is_read,
     /* In SC Only mode all characteristics requiring security
      * require it on level 4
      */
-    if (MYNEWT_VAL(BLE_SM_SC_ONLY)) {
+    if (ble_hs_cfg.sm_sc_only) {
         if (!sec_state.authenticated ||
             !sec_state.encrypted) {
             *out_att_err = BLE_ATT_ERR_INSUFFICIENT_AUTHEN;
diff --git a/nimble/host/src/ble_hs_cfg.c b/nimble/host/src/ble_hs_cfg.c
index a46a604ac..b3cf33c74 100644
--- a/nimble/host/src/ble_hs_cfg.c
+++ b/nimble/host/src/ble_hs_cfg.c
@@ -27,6 +27,7 @@ struct ble_hs_cfg ble_hs_cfg = {
     .sm_bonding = MYNEWT_VAL(BLE_SM_BONDING),
     .sm_mitm = MYNEWT_VAL(BLE_SM_MITM),
     .sm_sc = MYNEWT_VAL(BLE_SM_SC),
+    .sm_sc_only = MYNEWT_VAL(BLE_SM_SC_ONLY),
     .sm_keypress = MYNEWT_VAL(BLE_SM_KEYPRESS),
     .sm_our_key_dist = MYNEWT_VAL(BLE_SM_OUR_KEY_DIST),
     .sm_their_key_dist = MYNEWT_VAL(BLE_SM_THEIR_KEY_DIST),
diff --git a/nimble/host/src/ble_sm.c b/nimble/host/src/ble_sm.c
index 40acbc25a..92caa3b7f 100644
--- a/nimble/host/src/ble_sm.c
+++ b/nimble/host/src/ble_sm.c
@@ -1930,7 +1930,7 @@ ble_sm_pair_req_rx(uint16_t conn_handle, struct os_mbuf **om,
         } else if (req->max_enc_key_size > BLE_SM_PAIR_KEY_SZ_MAX) {
             res->sm_err = BLE_SM_ERR_INVAL;
             res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_INVAL);
-        } else if (MYNEWT_VAL(BLE_SM_SC_ONLY)) {
+        } else if (ble_hs_cfg.sm_sc_only) {
             /* Fail if Secure Connections Only mode is on and remote does not
              * meet key size requirements - MITM was checked in last step.
              * Fail if SC is not supported by peer or key size is too small
@@ -2005,7 +2005,7 @@ ble_sm_pair_rsp_rx(uint16_t conn_handle, struct os_mbuf **om,
         } else if (rsp->max_enc_key_size > BLE_SM_PAIR_KEY_SZ_MAX) {
             res->sm_err = BLE_SM_ERR_INVAL;
             res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_INVAL);
-        } else if (MYNEWT_VAL(BLE_SM_SC_ONLY) && (rsp->max_enc_key_size != BLE_SM_PAIR_KEY_SZ_MAX)) {
+        } else if (ble_hs_cfg.sm_sc_only && (rsp->max_enc_key_size != BLE_SM_PAIR_KEY_SZ_MAX)) {
             /* Fail if Secure Connections Only mode is on and remote does not meet
             * key size requirements - MITM was checked in last step
             */