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https://github.com/Atmosphere-NX/Atmosphere.git
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115 lines
3.9 KiB
C
115 lines
3.9 KiB
C
/*
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* Copyright (c) 2018-2019 Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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#include "utils.h"
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#include "lp0.h"
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#include "secmon.h"
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#include "se.h"
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#include "fuse.h"
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#include "pmc.h"
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/* "private" functions. */
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static bool secmon_should_clear_aes_keyslot(unsigned int keyslot);
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static void secmon_clear_unused_keyslots(void);
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static void secmon_decrypt_saved_image(void *dst, const void *src, size_t size);
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void secmon_restore_to_tzram(const uint32_t target_firmware) {
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/* Newer warmboot binaries clear the untouched keyslots for safety. */
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if (target_firmware >= ATMOSPHERE_TARGET_FIRMWARE_500) {
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secmon_clear_unused_keyslots();
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}
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/* Decrypt Secure Monitor from DRAM into TZRAM. */
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void *tzram_src = (void *)(0x80010000);
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void *tzram_dst = (void *)(target_firmware >= ATMOSPHERE_TARGET_FIRMWARE_500 ? 0x7C012000 : 0x7C010000);
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const size_t tzram_size = 0xE000;
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secmon_decrypt_saved_image(tzram_dst, tzram_src, tzram_size);
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/* Nintendo clears DRAM, but I'm not sure why, given they lock out BPMP access to DRAM. */
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for (size_t i = 0; i < tzram_size/sizeof(uint32_t); i++) {
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((volatile uint32_t *)tzram_src)[i] = 0;
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}
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/* Make security engine require secure busmaster. */
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se_get_regs()->_0x4 = 0;
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/* TODO: se_verify_keys_unreadable(); */
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/* TODO: pmc_lockout_wb_scratch_registers(); */
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/* Disable fuse programming. */
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fuse_disable_programming();
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}
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void secmon_decrypt_saved_image(void *dst, const void *src, size_t size) {
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/* First, AES-256-CBC decrypt the image into TZRAM. */
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se_aes_256_cbc_decrypt(KEYSLOT_SWITCH_LP0TZRAMKEY, dst, size, src, size);
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/* Next, calculate CMAC. */
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uint32_t tzram_cmac[4] = {0, 0, 0, 0};
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se_compute_aes_256_cmac(KEYSLOT_SWITCH_LP0TZRAMKEY, tzram_cmac, sizeof(tzram_cmac), dst, size);
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/* Validate the MAC against saved one in PMC scratch. */
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if (tzram_cmac[0] != APBDEV_PMC_SECURE_SCRATCH112_0 ||
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tzram_cmac[1] != APBDEV_PMC_SECURE_SCRATCH113_0 ||
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tzram_cmac[2] != APBDEV_PMC_SECURE_SCRATCH114_0 ||
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tzram_cmac[3] != APBDEV_PMC_SECURE_SCRATCH115_0) {
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reboot();
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}
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/* Clear the PMC scratch registers that hold the CMAC. */
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APBDEV_PMC_SECURE_SCRATCH112_0 = 0;
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APBDEV_PMC_SECURE_SCRATCH113_0 = 0;
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APBDEV_PMC_SECURE_SCRATCH114_0 = 0;
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APBDEV_PMC_SECURE_SCRATCH115_0 = 0;
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/* Clear keyslot now that we're done with it. */
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clear_aes_keyslot(KEYSLOT_SWITCH_LP0TZRAMKEY);
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}
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bool secmon_should_clear_aes_keyslot(unsigned int keyslot) {
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/* We'll just compare keyslot against a hardcoded list of keys. */
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static const uint8_t saved_keyslots[6] = {
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KEYSLOT_SWITCH_LP0TZRAMKEY,
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KEYSLOT_SWITCH_SESSIONKEY,
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KEYSLOT_SWITCH_RNGKEY,
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KEYSLOT_SWITCH_MASTERKEY,
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KEYSLOT_SWITCH_DEVICEKEY,
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KEYSLOT_SWITCH_4XOLDDEVICEKEY
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};
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for (unsigned int i = 0; i < sizeof(saved_keyslots)/sizeof(saved_keyslots[0]); i++) {
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if (keyslot == saved_keyslots[i]) {
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return false;
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}
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}
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return true;
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}
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void secmon_clear_unused_keyslots(void) {
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/* Clear unused keyslots. */
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for (unsigned int i = 0; i < KEYSLOT_AES_MAX; i++) {
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if (secmon_should_clear_aes_keyslot(i)) {
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clear_aes_keyslot(i);
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}
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clear_aes_keyslot_iv(i);
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}
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for (unsigned int i = 0; i < KEYSLOT_RSA_MAX; i++) {
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clear_rsa_keyslot(i);
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}
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}
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