ladybird/Kernel/Syscalls/getrandom.cpp
Idan Horowitz 48325e2959 Kernel: Disable big process lock for sys$getrandom
This syscall doesn't touch any intra-process shared resources and
already holds the global kernel RNG lock so there's no reason to hold
the big lock.
2021-08-06 23:36:12 +02:00

36 lines
1.1 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Process.h>
#include <Kernel/Random.h>
#include <Kernel/UserOrKernelBuffer.h>
namespace Kernel {
// We don't use the flag yet, but we could use it for distinguishing
// random source like Linux, unlike the OpenBSD equivalent. However, if we
// do, we should be able of the caveats that Linux has dealt with.
KResultOr<FlatPtr> Process::sys$getrandom(Userspace<void*> buffer, size_t buffer_size, [[maybe_unused]] unsigned flags)
{
VERIFY_NO_PROCESS_BIG_LOCK(this);
REQUIRE_PROMISE(stdio);
if (buffer_size > NumericLimits<ssize_t>::max())
return EINVAL;
auto data_buffer = UserOrKernelBuffer::for_user_buffer(buffer, buffer_size);
if (!data_buffer.has_value())
return EFAULT;
auto result = data_buffer.value().write_buffered<1024>(buffer_size, [&](u8* buffer, size_t buffer_bytes) {
get_good_random_bytes(buffer, buffer_bytes);
return buffer_bytes;
});
if (result.is_error())
return result.error();
else
return result.release_value();
}
}