sept-s: Implement key derivation

fusee/fusee-secondary/src/nxboot.c

@@ -28,6 +28,7 @@
 #include "mc.h"
 #include "se.h"
 #include "pmc.h"
+#include "emc.h"
 #include "fuse.h"
 #include "i2c.h"
 #include "ips.h"
@@ -308,6 +309,12 @@ static void nxboot_move_bootconfig() {
     free(bootconfig);
 }
 
+static bool get_and_clear_has_run_sept(void) {
+    bool has_run_sept = (MAKE_EMC_REG(EMC_SCRATCH0) & 0x80000000) != 0;
+    MAKE_EMC_REG(EMC_SCRATCH0) &= ~0x80000000;
+    return has_run_sept;
+}
+
 /* This is the main function responsible for booting Horizon. */
 static nx_keyblob_t __attribute__((aligned(16))) g_keyblobs[32];
 uint32_t nxboot_main(void) {
@@ -412,23 +419,15 @@ uint32_t nxboot_main(void) {
         }
     }
 
-    if (target_firmware == ATMOSPHERE_TARGET_FIRMWARE_700) {
-        /* TODO: Detect when we have been loaded by sept-secondary, and thus have keys provided for us. */
-        reboot_to_sept(tsec_fw, tsec_fw_size, sept_secondary_enc, sept_secondary_enc_size);
-    }
-
     print(SCREEN_LOG_LEVEL_MANDATORY, "[NXBOOT]: Loaded firmware from eMMC...\n");
 
     /* Get the TSEC keys. */
     uint8_t tsec_key[0x10] = {0};
     uint8_t tsec_root_keys[0x20][0x10] = {0};
     if (target_firmware >= ATMOSPHERE_TARGET_FIRMWARE_700) {
-        /* TODO: what else to do here? */
-        
-        /* Patch TSEC firmware to exit after generating TSEC key. */
-        *((volatile uint16_t *)((uintptr_t)tsec_fw + 0x2DB5)) = 0x02F8;
-        if (tsec_get_key(tsec_key, 1, tsec_fw, tsec_fw_size) != 0) {
-            fatal_error("[NXBOOT]: Failed to get TSEC key!\n");
+        /* Detect whether we need to run sept-secondary in order to derive keys. */
+        if (!get_and_clear_has_run_sept()) {
+            reboot_to_sept(tsec_fw, tsec_fw_size, sept_secondary_enc, sept_secondary_enc_size);
         }
     } else if (target_firmware == ATMOSPHERE_TARGET_FIRMWARE_620) {
         uint8_t tsec_keys[0x20] = {0};
@@ -446,11 +445,13 @@ uint32_t nxboot_main(void) {
         }
     }
     
-    /* Derive keydata. */
+    /* Derive keydata. If on 7.0.0+, sept has already derived keys for us. */
     unsigned int keygen_type = 0;
+    if (target_firmware < ATMOSPHERE_TARGET_FIRMWARE_700) {
         if (derive_nx_keydata(target_firmware, g_keyblobs, available_revision, tsec_key, tsec_root_keys, &keygen_type) != 0) {
             fatal_error("[NXBOOT]: Key derivation failed!\n");
         }
+    }
 
     /* Setup boot configuration for Exosphère. */
     nxboot_configure_exosphere(target_firmware, keygen_type);

sept/sept-secondary/src/key_derivation.c

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include "key_derivation.h"
+#include "se.h"
+#include "fuse.h"
+#include "utils.h"
+
+#define AL16 ALIGN(16)
+
+static const uint8_t AL16 keyblob_seed_00[0x10] = {
+    0xDF, 0x20, 0x6F, 0x59, 0x44, 0x54, 0xEF, 0xDC, 0x70, 0x74, 0x48, 0x3B, 0x0D, 0xED, 0x9F, 0xD3
+};
+
+static const uint8_t AL16 masterkey_seed[0x10] = {
+    0xD8, 0xA2, 0x41, 0x0A, 0xC6, 0xC5, 0x90, 0x01, 0xC6, 0x1D, 0x6A, 0x26, 0x7C, 0x51, 0x3F, 0x3C
+};
+
+static const uint8_t AL16 devicekey_seed[0x10] = {
+    0x4F, 0x02, 0x5F, 0x0E, 0xB6, 0x6D, 0x11, 0x0E, 0xDC, 0x32, 0x7D, 0x41, 0x86, 0xC2, 0xF4, 0x78
+};
+
+static const uint8_t AL16 devicekey_4x_seed[0x10] = {
+    0x0C, 0x91, 0x09, 0xDB, 0x93, 0x93, 0x07, 0x81, 0x07, 0x3C, 0xC4, 0x16, 0x22, 0x7C, 0x6C, 0x28
+};
+
+static const uint8_t AL16 masterkey_4x_seed[0x10] = {
+    0x2D, 0xC1, 0xF4, 0x8D, 0xF3, 0x5B, 0x69, 0x33, 0x42, 0x10, 0xAC, 0x65, 0xDA, 0x90, 0x46, 0x66
+};
+
+static const uint8_t AL16 new_master_kek_seed_7x[0x10] = {
+    0x9A, 0x3E, 0xA9, 0xAB, 0xFD, 0x56, 0x46, 0x1C, 0x9B, 0xF6, 0x48, 0x7F, 0x5C, 0xFA, 0x09, 0x5C
+};
+
+void derive_7x_keys(const void *tsec_key, void *tsec_root_key) {
+    uint8_t AL16 work_buffer[0x10];
+    uint8_t AL16 master_kek[0x10];
+
+    /* Set keyslot flags properly in preparation of derivation. */
+    set_aes_keyslot_flags(0xE, 0x15);
+    set_aes_keyslot_flags(0xD, 0x15);
+    
+    /* Set the TSEC key. */
+    set_aes_keyslot(0xD, tsec_key, 0x10);
+    
+    /* Derive keyblob key 0. */
+    se_aes_ecb_decrypt_block(0xD, work_buffer, 0x10, keyblob_seed_00, 0x10);
+    decrypt_data_into_keyslot(0xF, 0xE, work_buffer, 0x10);
+    
+    /* Derive the master kek. */
+    set_aes_keyslot(0xC, tsec_root_key, 0x10);
+    se_aes_ecb_decrypt_block(0xC, master_kek, 0x10, new_master_kek_seed_7x, 0x10);
+    
+    /* Clear the SBK. */
+    clear_aes_keyslot(0xE);
+
+    /* Set master kek. */
+    set_aes_keyslot(0xC, master_kek, 0x10);
+    
+    /* Derive keys for exosphere. */
+    decrypt_data_into_keyslot(0xA, 0xF, devicekey_4x_seed, 0x10);
+    decrypt_data_into_keyslot(0xF, 0xF, devicekey_seed, 0x10);
+    decrypt_data_into_keyslot(0xE, 0xC, masterkey_4x_seed, 0x10);
+    decrypt_data_into_keyslot(0xC, 0xC, masterkey_seed, 0x10);
+    
+    /* Clear master kek from memory. */
+    for (size_t i = 0; i < sizeof(master_kek); i++) {
+        master_kek[i]  = 0xCC;
+        work_buffer[i] = 0xCC;
+    }
+}

sept/sept-secondary/src/key_derivation.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+ 
+#ifndef SEPT_KEYDERIVATION_H
+#define SEPT_KEYDERIVATION_H
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+void derive_7x_keys(const void *tsec_key, void *tsec_root_key);
+
+#endif

sept/sept-secondary/src/main.c

@@ -21,6 +21,8 @@
 #include "di.h"
 #include "se.h"
 #include "pmc.h"
+#include "emc.h"
+#include "key_derivation.h"
 #include "timers.h"
 #include "fs_utils.h"
 #include "stage2.h"
@@ -151,9 +153,20 @@ int main(void) {
     
     /* Say hello. */
     print(SCREEN_LOG_LEVEL_MANDATORY, "Welcome to Atmosph\xe8re sept-secondary!\n");
-    while (true) { }
     
-    /* TODO: Derive keys. */
+    /* Derive keys. */
+    derive_7x_keys(g_tsec_key, g_tsec_root_key);
+    
+    /* Cleanup keys in memory. */
+    for (size_t i = 0; i < 0x10; i += 4) {
+        g_tsec_root_key[i/4] = 0xCCCCCCCC;
+        g_tsec_key[i/4] = 0xCCCCCCCC;
+    }
+    
+    /* Mark EMC scratch to say that sept has run. */
+    MAKE_EMC_REG(EMC_SCRATCH0) |= 0x80000000;
+    
+    while (true) { }
     
     /* TODO: Chainload to payload. */