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68 lines
2.1 KiB
C++
68 lines
2.1 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2014.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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random.cpp
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Kernel entropy gathering.
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*******************************************************************************/
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#include <errno.h>
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#include <sortix/clock.h>
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#include <sortix/kernel/copy.h>
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#include <sortix/kernel/interlock.h>
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#include <sortix/kernel/syscall.h>
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#include <sortix/kernel/time.h>
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namespace Sortix {
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static unsigned long sequence = 0;
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int sys_getentropy(void* user_buffer, size_t size)
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{
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union
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{
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unsigned char buffer[256];
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struct
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{
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struct timespec realtime;
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struct timespec monotonic;
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unsigned long sequence;
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} seed;
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};
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if ( sizeof(buffer) < size )
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return errno = EIO, -1;
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// TODO: SECURITY: We need to actually gather entropy and deliver it.
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for ( size_t i = 0; i < size; i++ )
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buffer[i] = i;
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// NOTE: This is not random and is not meant to be random, this is just
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// meant to make the returned entropy a little different each time
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// until we have real randomness, even across reboots. The userland
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// arc4random mixer will mix it around and the produced streams will
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// look random and should not repeat in practice.
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seed.realtime = Time::Get(CLOCK_REALTIME);
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seed.monotonic = Time::Get(CLOCK_MONOTONIC);
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seed.sequence = InterlockedIncrement(&sequence).o;
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if ( !CopyToUser(user_buffer, buffer, size) )
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return -1;
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return 0;
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}
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} // namespace Sortix
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