nimble/ll: Add vs hci to set local IRK

This adds vendor-specific HCI command to set local IRK in controller.

Local IRK, if set, is used to generate local RPA in use cases where own
address type was set to 0x02 or 0x03 but peer address is not added to
resolving list. This for example allows to handle initiating connection
to a new peer using RPA as our local address entirely in LL. Without
that command it would be required for host to generate an RPA, set it as
random address and connect using random address. This however doesn't
work well with NimBLE host.

If no IRK is set (or set to all-zero), the controller behaves as usual
which makes it safe to enable as it won't break anything.

nimble/controller/include/controller/ble_ll_resolv.h

@@ -115,6 +115,17 @@ int ble_ll_resolv_peer_rpa_any(const uint8_t *rpa);
 /* Initialize resolv*/
 void ble_ll_resolv_init(void);
 
+#if MYNEWT_VAL(BLE_LL_HCI_VS_LOCAL_IRK)
+int ble_ll_resolv_local_irk_set(const uint8_t *irk);
+int ble_ll_resolv_local_rpa_get(uint8_t *rpa);
+#else
+static inline int
+ble_ll_resolv_local_rpa_get(uint8_t *rpa)
+{
+    return -ENOENT;
+}
+#endif
+
 #ifdef __cplusplus
 }
 #endif

nimble/controller/src/ble_ll_conn.c

@@ -3118,15 +3118,18 @@ ble_ll_conn_prepare_connect_ind(struct ble_ll_conn_sm *connsm,
 
     /* XXX: do this ahead of time? Calculate the local rpa I mean */
 #if MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_PRIVACY)
-        if ((connsm->own_addr_type > BLE_HCI_ADV_OWN_ADDR_RANDOM) &&
-            (addrd->rpa_index >= 0)) {
-            /* We are using RPA and advertiser was on our resolving list, so
-             * we'll use RPA to reply (see Core 5.3, Vol 6, Part B, 6.4).
-             */
-            rl = &g_ble_ll_resolv_list[addrd->rpa_index];
-            if (rl->rl_has_local) {
-                hdr |= BLE_ADV_PDU_HDR_TXADD_RAND;
-                ble_ll_resolv_get_priv_addr(rl, 1, pdu_data->inita);
+        if (connsm->own_addr_type > BLE_HCI_ADV_OWN_ADDR_RANDOM) {
+            if (addrd->rpa_index >= 0) {
+                /* We are using RPA and advertiser was on our resolving list, so
+                 * we'll use RPA to reply (see Core 5.3, Vol 6, Part B, 6.4).
+                 */
+                rl = &g_ble_ll_resolv_list[addrd->rpa_index];
+                if (rl->rl_has_local) {
+                    hdr |= BLE_ADV_PDU_HDR_TXADD_RAND;
+                    ble_ll_resolv_get_priv_addr(rl, 1, pdu_data->inita);
+                    addr = NULL;
+                }
+            } else if (ble_ll_resolv_local_rpa_get(pdu_data->inita) == 0) {
                 addr = NULL;
             }
         }

nimble/controller/src/ble_ll_hci_vs.c

@@ -29,6 +29,7 @@
 #include "controller/ble_fem.h"
 #include "ble_ll_conn_priv.h"
 #include "ble_ll_priv.h"
+#include "controller/ble_ll_resolv.h"
 
 #if MYNEWT_VAL(BLE_LL_HCI_VS)
 
@@ -328,6 +329,29 @@ ble_ll_hci_vs_set_antenna(uint16_t ocf, const uint8_t *cmdbuf, uint8_t cmdlen,
 }
 #endif
 
+#if MYNEWT_VAL(BLE_LL_HCI_VS_LOCAL_IRK)
+static int
+ble_ll_hci_vs_set_local_irk(uint16_t ocf, const uint8_t *cmdbuf, uint8_t cmdlen,
+                            uint8_t *rspbuf, uint8_t *rsplen)
+{
+    const struct ble_hci_vs_set_local_irk_cp *cmd = (const void *)cmdbuf;
+    int rc;
+
+    if (cmdlen != sizeof(*cmd)) {
+        return BLE_ERR_INV_HCI_CMD_PARMS;
+    }
+
+    rc = ble_ll_resolv_local_irk_set(cmd->irk);
+    if (rc) {
+        return rc;
+    }
+
+    *rsplen = 0;
+
+    return 0;
+}
+#endif
+
 static struct ble_ll_hci_vs_cmd g_ble_ll_hci_vs_cmds[] = {
     BLE_LL_HCI_VS_CMD(BLE_HCI_OCF_VS_RD_STATIC_ADDR,
                       ble_ll_hci_vs_rd_static_addr),
@@ -354,6 +378,10 @@ static struct ble_ll_hci_vs_cmd g_ble_ll_hci_vs_cmds[] = {
 #if MYNEWT_VAL(BLE_FEM_ANTENNA)
     BLE_LL_HCI_VS_CMD(BLE_HCI_OCF_VS_SET_ANTENNA, ble_ll_hci_vs_set_antenna),
 #endif
+#if MYNEWT_VAL(BLE_LL_HCI_VS_LOCAL_IRK)
+    BLE_LL_HCI_VS_CMD(BLE_HCI_OCF_VS_SET_LOCAL_IRK,
+                      ble_ll_hci_vs_set_local_irk),
+#endif
 };
 
 static struct ble_ll_hci_vs_cmd *

nimble/controller/src/ble_ll_resolv.c

@@ -19,6 +19,7 @@
 #include <stdint.h>
 #include <assert.h>
 #include <string.h>
+#include <sys/errno.h>
 #include "syscfg/syscfg.h"
 #include "os/os.h"
 #include "nimble/ble.h"
@@ -48,6 +49,15 @@ struct ble_ll_resolv_data g_ble_ll_resolv_data;
 __attribute__((aligned(4)))
 struct ble_ll_resolv_entry g_ble_ll_resolv_list[MYNEWT_VAL(BLE_LL_RESOLV_LIST_SIZE)];
 
+#if MYNEWT_VAL(BLE_LL_HCI_VS_LOCAL_IRK)
+struct local_irk_data {
+    uint8_t is_set;
+    uint8_t irk[16];
+    uint8_t rpa[6];
+};
+static struct local_irk_data g_local_irk;
+#endif
+
 /**
  * Called to determine if a change is allowed to the resolving list at this
  * time. We are not allowed to modify the resolving list if address translation
@@ -70,6 +80,30 @@ ble_ll_resolv_list_chg_allowed(void)
     return rc;
 }
 
+static void
+generate_rpa(const uint8_t *irk, uint8_t *rpa)
+{
+    uint8_t *prand;
+    struct ble_encryption_block ecb;
+
+    /* Get prand */
+    prand = rpa + 3;
+    ble_ll_rand_prand_get(prand);
+
+    /* Calculate hash, hash = ah(local IRK, prand) */
+    memcpy(ecb.key, irk, 16);
+    memset(ecb.plain_text, 0, 13);
+    ecb.plain_text[13] = prand[2];
+    ecb.plain_text[14] = prand[1];
+    ecb.plain_text[15] = prand[0];
+
+    /* Calculate hash */
+    ble_hw_encrypt_block(&ecb);
+
+    rpa[0] = ecb.cipher_text[15];
+    rpa[1] = ecb.cipher_text[14];
+    rpa[2] = ecb.cipher_text[13];
+}
 
 /**
  * Called to generate a resolvable private address in rl structure
@@ -81,8 +115,6 @@ static void
 ble_ll_resolv_gen_priv_addr(struct ble_ll_resolv_entry *rl, int local)
 {
     uint8_t *irk;
-    uint8_t *prand;
-    struct ble_encryption_block ecb;
     uint8_t *addr;
 
     BLE_LL_ASSERT(rl != NULL);
@@ -95,23 +127,7 @@ ble_ll_resolv_gen_priv_addr(struct ble_ll_resolv_entry *rl, int local)
         irk = rl->rl_peer_irk;
     }
 
-    /* Get prand */
-    prand = addr + 3;
-    ble_ll_rand_prand_get(prand);
-
-    /* Calculate hash, hash = ah(local IRK, prand) */
-    memcpy(ecb.key, irk, 16);
-    memset(ecb.plain_text, 0, 13);
-    ecb.plain_text[13] = prand[2];
-    ecb.plain_text[14] = prand[1];
-    ecb.plain_text[15] = prand[0];
-
-    /* Calculate hash */
-    ble_hw_encrypt_block(&ecb);
-
-    addr[0] = ecb.cipher_text[15];
-    addr[1] = ecb.cipher_text[14];
-    addr[2] = ecb.cipher_text[13];
+    generate_rpa(irk, addr);
 }
 
 /**
@@ -141,6 +157,14 @@ ble_ll_resolv_rpa_timer_cb(struct ble_npl_event *ev)
         ++rl;
     }
 
+#if MYNEWT_VAL(BLE_LL_HCI_VS_LOCAL_IRK)
+    OS_ENTER_CRITICAL(sr);
+    if (g_local_irk.is_set) {
+        generate_rpa(g_local_irk.irk, g_local_irk.rpa);
+    }
+    OS_EXIT_CRITICAL(sr);
+#endif
+
     ble_npl_callout_reset(&g_ble_ll_resolv_data.rpa_timer,
                           g_ble_ll_resolv_data.rpa_tmo);
 
@@ -637,6 +661,41 @@ ble_ll_resolv_gen_rpa(uint8_t *addr, uint8_t addr_type, uint8_t *rpa, int local)
     return 0;
 }
 
+#if MYNEWT_VAL(BLE_LL_HCI_VS_LOCAL_IRK)
+int
+ble_ll_resolv_local_irk_set(const uint8_t *irk)
+{
+    int i;
+
+    memcpy(g_local_irk.irk, irk, 16);
+
+    g_local_irk.is_set = 0;
+
+    for (i = 0; i < 16; i++) {
+        if (irk[i]) {
+            g_local_irk.is_set = 1;
+            break;
+        }
+    }
+
+    if (g_local_irk.is_set) {
+        generate_rpa(g_local_irk.irk, g_local_irk.rpa);
+    }
+
+    return 0;
+}
+
+int
+ble_ll_resolv_local_rpa_get(uint8_t *rpa)
+{
+    if (!g_local_irk.is_set) {
+        return -ENOENT;
+    }
+
+    return 0;
+}
+#endif
+
 /**
  * Resolve a Resolvable Private Address
  *
@@ -738,6 +797,10 @@ ble_ll_resolv_init(void)
                          &g_ble_ll_data.ll_evq,
                          ble_ll_resolv_rpa_timer_cb,
                          NULL);
+
+#if MYNEWT_VAL(BLE_LL_HCI_VS_LOCAL_IRK)
+    memset(&g_local_irk, 0, sizeof(g_local_irk));
+#endif
 }
 
 #endif  /* if MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_PRIVACY) */

nimble/controller/syscfg.yml

@@ -417,6 +417,18 @@ syscfg.defs:
         value: 0
         restrictions:
             - BLE_LL_HCI_VS if 1
+    BLE_LL_HCI_VS_LOCAL_IRK:
+        description: >
+            Enables HCI command to set local IRK.
+            The local IRK is used by controller to generate RPA address in case
+            own address type 0x02 or 0x03 was requested by host but there is no
+            corresponding entry on resolving list. This allows to handle privacy
+            scenarios almost entirely in controller. If no local IRK is set, the
+            controller behaves as if feature is not enabled.
+        value: 0
+        restrictions:
+            - BLE_LL_HCI_VS if 1
+
 
     BLE_LL_HCI_VS_EVENT_ON_ASSERT:
         description: >

nimble/include/nimble/hci_common.h

@@ -1208,8 +1208,10 @@ struct ble_hci_vs_set_data_len_rp {
 struct ble_hci_vs_set_antenna_cp {
     uint8_t antenna;
 } __attribute__((packed));
-
-
+#define BLE_HCI_OCF_VS_SET_LOCAL_IRK                   (MYNEWT_VAL(BLE_HCI_VS_OCF_OFFSET) + (0x000A))
+struct ble_hci_vs_set_local_irk_cp {
+    uint8_t irk[16];
+} __attribute__((packed));
 
 /* Command Specific Definitions */
 /* --- Set controller to host flow control (OGF 0x03, OCF 0x0031) --- */