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Atmosphere/exosphere/warmboot/source/warmboot_secure_monitor.cpp

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2020-06-11 09:30:30 +01:00
/*
* Copyright (c) Atmosphère-NX
2020-06-11 09:30:30 +01:00
*
* 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 <exosphere.hpp>
#include "warmboot_secure_monitor.hpp"
namespace ams::warmboot {
namespace {
constexpr inline const uintptr_t PMC = secmon::MemoryRegionPhysicalDevicePmc.GetAddress();
constexpr inline const pkg1::AesKeySlot SavedAesKeySlots[] = {
pkg1::AesKeySlot_TzramSaveKek,
pkg1::AesKeySlot_RandomForUserWrap,
pkg1::AesKeySlot_RandomForKeyStorageWrap,
pkg1::AesKeySlot_DeviceMaster,
pkg1::AesKeySlot_Master,
pkg1::AesKeySlot_Device,
};
constexpr ALWAYS_INLINE bool IsSavedAesKeySlot(int slot) {
for (const auto SavedSlot : SavedAesKeySlots) {
if (slot == SavedSlot) {
return true;
}
}
return false;
}
void ClearUnsavedSecurityEngineKeySlots() {
/* Clear unsaved aes keys and all ivs. */
for (int slot = 0; slot < se::AesKeySlotCount; ++slot) {
if (!IsSavedAesKeySlot(slot)) {
se::ClearAesKeySlot(slot);
}
se::ClearAesKeyIv(slot);
}
/* Clear all rsa keys. */
for (int slot = 0; slot < se::RsaKeySlotCount; ++slot) {
se::ClearRsaKeySlot(slot);
}
}
void RestoreEncryptedTzram(void * const tzram_dst, const void * const tzram_src, size_t tzram_size) {
/* Derive the save key from the save kek. */
const u32 key_source[se::AesBlockSize / sizeof(u32)] = { reg::Read(PMC + APBDEV_PMC_SECURE_SCRATCH24), reg::Read(PMC + APBDEV_PMC_SECURE_SCRATCH25), reg::Read(PMC + APBDEV_PMC_SECURE_SCRATCH26), reg::Read(PMC + APBDEV_PMC_SECURE_SCRATCH27)};
se::ClearAesKeySlot(pkg1::AesKeySlot_TzramSaveKey);
se::SetEncryptedAesKey256(pkg1::AesKeySlot_TzramSaveKey, pkg1::AesKeySlot_TzramSaveKek, key_source, sizeof(key_source));
/* Decrypt tzram. */
const u8 tzram_iv[se::AesBlockSize] = {};
se::DecryptAes256Cbc(tzram_dst, tzram_size, pkg1::AesKeySlot_TzramSaveKey, tzram_src, tzram_size, tzram_iv, sizeof(tzram_iv));
/* Calculate the cmac of decrypted tzram. */
u8 tzram_mac[se::AesBlockSize] = {};
se::ComputeAes256Cmac(tzram_mac, sizeof(tzram_mac), pkg1::AesKeySlot_TzramSaveKey, tzram_dst, tzram_size);
/* Get the expected mac from pmc scratch. */
const u32 expected_mac[sizeof(tzram_mac) / sizeof(u32)] = { reg::Read(PMC + APBDEV_PMC_SECURE_SCRATCH112), reg::Read(PMC + APBDEV_PMC_SECURE_SCRATCH113), reg::Read(PMC + APBDEV_PMC_SECURE_SCRATCH114), reg::Read(PMC + APBDEV_PMC_SECURE_SCRATCH115)};
/* Validate that the calculated mac is correct. */
AMS_ABORT_UNLESS(crypto::IsSameBytes(tzram_mac, expected_mac, sizeof(tzram_mac)));
}
void RestoreSecureMonitorToTzramErista(const TargetFirmware target_fw) {
/* Clear all unsaved security engine keyslots. */
ClearUnsavedSecurityEngineKeySlots();
/* Restore encrypted tzram contents. */
void * const tzram_src = secmon::MemoryRegionPhysicalDramSecureDataStoreTzram.GetPointer<void>();
void * const tzram_dst = secmon::MemoryRegionPhysicalTzramNonVolatile.GetPointer<void>();
const size_t tzram_size = secmon::MemoryRegionPhysicalTzramNonVolatile.GetSize();
RestoreEncryptedTzram(tzram_dst, tzram_src, tzram_size);
/* Clear the tzram kek registers. */
reg::Write(PMC + APBDEV_PMC_SECURE_SCRATCH24, 0);
reg::Write(PMC + APBDEV_PMC_SECURE_SCRATCH25, 0);
reg::Write(PMC + APBDEV_PMC_SECURE_SCRATCH26, 0);
reg::Write(PMC + APBDEV_PMC_SECURE_SCRATCH27, 0);
/* Clear the tzram cmac registers. */
reg::Write(PMC + APBDEV_PMC_SECURE_SCRATCH112, 0);
reg::Write(PMC + APBDEV_PMC_SECURE_SCRATCH113, 0);
reg::Write(PMC + APBDEV_PMC_SECURE_SCRATCH114, 0);
reg::Write(PMC + APBDEV_PMC_SECURE_SCRATCH115, 0);
/* Clear the keydata used to protect tzram. */
se::ClearAesKeySlot(pkg1::AesKeySlot_TzramSaveKek);
se::ClearAesKeySlot(pkg1::AesKeySlot_TzramSaveKey);
/* Clear the encrypted copy of tzram in dram. */
/* NOTE: This does not actually clear the encrypted copy, because BPMP access to main memory has been restricted. */
/* Nintendo seems to not realize this, though, so we'll do the same. */
std::memset(tzram_src, 0, tzram_size);
/* Set Tzram to secure-world only. */
se::SetTzramSecure();
}
}
void RestoreSecureMonitorToTzram(const TargetFirmware target_fw) {
/* If erista, perform restoration procedure. */
if (fuse::GetSocType() == fuse::SocType_Erista) {
RestoreSecureMonitorToTzramErista(target_fw);
}
/* Lock secure scratch. */
pmc::LockSecureRegister(static_cast<pmc::SecureRegister>(pmc::SecureRegister_DramParameters | pmc::SecureRegister_Other));
/* Lockout fuses. */
fuse::Lockout();
}
}