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https://github.com/Atmosphere-NX/Atmosphere.git
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77 lines
2.9 KiB
C++
77 lines
2.9 KiB
C++
/*
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* Copyright (c) 2018-2020 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 <exosphere.hpp>
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#include "../secmon_error.hpp"
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#include "secmon_smc_random.hpp"
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#include "secmon_random_cache.hpp"
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#include "secmon_smc_se_lock.hpp"
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namespace ams::secmon::smc {
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namespace {
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SmcResult GenerateRandomBytesImpl(SmcArguments &args) {
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/* Validate the input size. */
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const size_t size = args.r[1];
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SMC_R_UNLESS(size <= MaxRandomBytes, InvalidArgument);
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/* Create a buffer that the se can generate bytes into. */
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util::AlignedBuffer<hw::DataCacheLineSize, MaxRandomBytes> buffer;
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hw::FlushDataCache(buffer, size);
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hw::DataSynchronizationBarrierInnerShareable();
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/* Generate random bytes into the buffer. */
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se::GenerateRandomBytes(buffer, size);
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/* Ensure that the cpu sees consistent data. */
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hw::DataSynchronizationBarrierInnerShareable();
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hw::FlushDataCache(buffer, size);
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hw::DataSynchronizationBarrierInnerShareable();
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/* Copy the bytes to output. */
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std::memcpy(std::addressof(args.r[1]), buffer, size);
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return SmcResult::Success;
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}
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}
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SmcResult SmcGenerateRandomBytes(SmcArguments &args) {
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return LockSecurityEngineAndInvoke(args, GenerateRandomBytesImpl);
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}
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SmcResult SmcGenerateRandomBytesNonBlocking(SmcArguments &args) {
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/* Try to lock the security engine, so that we can call the standard impl. */
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if (TryLockSecurityEngine()) {
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/* Ensure we unlock the security engine when done. */
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ON_SCOPE_EXIT { UnlockSecurityEngine(); };
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/* Take advantage of our lock to refill lthe random cache. */
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ON_SCOPE_EXIT { RefillRandomCache(); };
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/* If we lock it successfully, we can just call the blocking impl. */
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return GenerateRandomBytesImpl(args);
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} else {
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/* Otherwise, we'll retrieve some bytes from the cache. */
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const size_t size = args.r[1];
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SMC_R_UNLESS(size <= MaxRandomBytes, InvalidArgument);
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/* Get random bytes from the cache. */
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GetRandomFromCache(std::addressof(args.r[1]), size);
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return SmcResult::Success;
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}
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}
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}
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