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c3f668a758
This is essentially free on x86 and allows us to not hold the big process lock just to check the required promises for a syscall.
90 lines
2.6 KiB
C++
90 lines
2.6 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/StringView.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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KResultOr<FlatPtr> Process::sys$pledge(Userspace<const Syscall::SC_pledge_params*> user_params)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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Syscall::SC_pledge_params params;
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if (!copy_from_user(¶ms, user_params))
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return EFAULT;
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if (params.promises.length > 1024 || params.execpromises.length > 1024)
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return E2BIG;
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OwnPtr<KString> promises;
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if (params.promises.characters) {
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auto promises_or_error = try_copy_kstring_from_user(params.promises);
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if (promises_or_error.is_error())
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return promises_or_error.error();
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promises = promises_or_error.release_value();
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}
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OwnPtr<KString> execpromises;
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if (params.execpromises.characters) {
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auto execpromises_or_error = try_copy_kstring_from_user(params.execpromises);
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if (execpromises_or_error.is_error())
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return execpromises_or_error.error();
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execpromises = execpromises_or_error.release_value();
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}
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auto parse_pledge = [&](auto pledge_spec, u32& mask) {
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auto parts = pledge_spec.split_view(' ');
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for (auto& part : parts) {
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#define __ENUMERATE_PLEDGE_PROMISE(x) \
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if (part == StringView { #x }) { \
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mask |= (1u << (u32)Pledge::x); \
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continue; \
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}
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ENUMERATE_PLEDGE_PROMISES
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#undef __ENUMERATE_PLEDGE_PROMISE
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return false;
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}
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return true;
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};
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ProtectedDataMutationScope scope { *this };
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u32 new_promises = 0;
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if (promises) {
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if (!parse_pledge(promises->view(), new_promises))
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return EINVAL;
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if (m_has_promises && (new_promises & ~m_promises))
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return EPERM;
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}
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u32 new_execpromises = 0;
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if (execpromises) {
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if (!parse_pledge(execpromises->view(), new_execpromises))
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return EINVAL;
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if (m_has_execpromises && (new_execpromises & ~m_execpromises))
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return EPERM;
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}
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// Only apply promises after all validation has occurred, this ensures
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// we don't introduce logic bugs like applying the promises, and then
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// erroring out when parsing the exec promises later. Such bugs silently
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// leave the caller in an unexpected state.
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if (promises) {
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m_promises = new_promises;
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m_has_promises = true;
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}
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if (execpromises) {
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m_execpromises = new_execpromises;
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m_has_execpromises = true;
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}
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return 0;
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}
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}
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