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Atmosphere/fusee/program/source/fusee_package2.cpp

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6.3 KiB
C++

/*
* Copyright (c) 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 <exosphere.hpp>
#include "fusee_package2.hpp"
#include "fusee_key_derivation.hpp"
#include "fusee_fatal.hpp"
namespace ams::nxboot {
namespace {
alignas(se::AesBlockSize) constexpr inline const u8 Package2KeySource[se::AesBlockSize] = {
0xFB, 0x8B, 0x6A, 0x9C, 0x79, 0x00, 0xC8, 0x49, 0xEF, 0xD2, 0x4D, 0x85, 0x4D, 0x30, 0xA0, 0xC7
};
void PreparePackage2Key(int pkg2_slot, int key_generation) {
/* Get keyslot for the desired master key. */
const int master_slot = PrepareMasterKey(key_generation);
/* Load the package2 key into the desired keyslot. */
se::SetEncryptedAesKey128(pkg2_slot, master_slot, Package2KeySource, sizeof(Package2KeySource));
}
void DecryptPackage2(void *dst, size_t dst_size, const void *src, size_t src_size, const void *iv, size_t iv_size, u8 key_generation) {
/* Ensure that the SE sees consistent data. */
hw::FlushDataCache(src, src_size);
if (src != dst) {
hw::FlushDataCache(dst, dst_size);
}
/* Load the package2 key into the temporary keyslot. */
PreparePackage2Key(pkg1::AesKeySlot_Temporary, key_generation);
/* Decrypt the data. */
se::ComputeAes128Ctr(dst, dst_size, pkg1::AesKeySlot_Temporary, src, src_size, iv, iv_size);
/* Clear the keyslot we just used. */
se::ClearAesKeySlot(pkg1::AesKeySlot_Temporary);
/* Ensure that the cpu sees consistent data. */
hw::InvalidateDataCache(dst, dst_size);
}
void DecryptPackage2Header(pkg2::Package2Meta *dst, const pkg2::Package2Meta &src) {
constexpr int IvSize = 0x10;
/* Decrypt the header. */
DecryptPackage2(dst, sizeof(*dst), std::addressof(src), sizeof(src), std::addressof(src), IvSize, src.GetKeyGeneration());
/* Copy back the iv, which encodes encrypted metadata. */
std::memcpy(dst, std::addressof(src), IvSize);
}
bool VerifyPackage2Meta(const pkg2::Package2Meta &meta) {
/* Get the obfuscated metadata. */
const size_t size = meta.GetSize();
const u8 key_generation = meta.GetKeyGeneration();
/* Check that size is big enough for the header. */
if (size <= sizeof(pkg2::Package2Header)) {
return false;
}
/* Check that the size isn't larger than what we allow. */
if (size > pkg2::Package2SizeMax) {
return false;
}
/* Check that the key generation is one that we can use. */
static_assert(pkg1::KeyGeneration_Count == 17);
if (key_generation >= pkg1::KeyGeneration_Count) {
return false;
}
/* Check the magic number. */
if (!crypto::IsSameBytes(meta.magic, pkg2::Package2Meta::Magic::String, sizeof(meta.magic))) {
return false;
}
/* Check the payload alignments. */
if ((meta.entrypoint % pkg2::PayloadAlignment) != 0) {
return false;
}
for (int i = 0; i < pkg2::PayloadCount; ++i) {
if ((meta.payload_sizes[i] % pkg2::PayloadAlignment) != 0) {
return false;
}
}
/* Check that the sizes sum to the total. */
if (size != sizeof(pkg2::Package2Header) + meta.payload_sizes[0] + meta.payload_sizes[1] + meta.payload_sizes[2]) {
return false;
}
/* Check that the payloads do not overflow. */
for (int i = 0; i < pkg2::PayloadCount; ++i) {
if (meta.payload_offsets[i] > meta.payload_offsets[i] + meta.payload_sizes[i]) {
return false;
}
}
/* Verify that no payloads overlap. */
for (int i = 0; i < pkg2::PayloadCount - 1; ++i) {
for (int j = i + 1; j < pkg2::PayloadCount; ++j) {
if (util::HasOverlap(meta.payload_offsets[i], meta.payload_sizes[i], meta.payload_offsets[j], meta.payload_sizes[j])) {
return false;
}
}
}
/* Check whether any payload contains the entrypoint. */
for (int i = 0; i < pkg2::PayloadCount; ++i) {
if (util::Contains(meta.payload_offsets[i], meta.payload_sizes[i], meta.entrypoint)) {
return true;
}
}
/* No payload contains the entrypoint, so we're not valid. */
return false;
}
}
void DecryptPackage2(u8 *package2) {
/* Decrypt package2 header. */
pkg2::Package2Header *header = reinterpret_cast<pkg2::Package2Header *>(package2);
{
pkg2::Package2Header tmp = *header;
DecryptPackage2Header(std::addressof(header->meta), tmp.meta);
}
/* Check package2 magic. */
if (!VerifyPackage2Meta(header->meta)) {
ShowFatalError("Package2 meta is invalid!\n");
}
/* Decrypt package2 payloads. */
u8 *payload = package2 + sizeof(*header);
const u8 key_generation = header->meta.GetKeyGeneration();
for (int i = 0; i < pkg2::PayloadCount; ++i) {
if (header->meta.payload_sizes[i] == 0) {
continue;
}
DecryptPackage2(payload, header->meta.payload_sizes[i], payload, header->meta.payload_sizes[i], header->meta.payload_ivs[i], sizeof(header->meta.payload_ivs[i]), key_generation);
payload += header->meta.payload_sizes[i];
}
}
}