48 lines
1.6 KiB
C++
48 lines
1.6 KiB
C++
// Copyright 2018 The Crashpad Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "test/scoped_guarded_page.h"
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#include <sys/mman.h>
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#include "base/check.h"
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#include "base/memory/page_size.h"
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namespace crashpad {
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namespace test {
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ScopedGuardedPage::ScopedGuardedPage() {
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ptr_ = mmap(nullptr,
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base::GetPageSize() * 2,
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PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS,
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-1,
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0);
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PCHECK(ptr_ != MAP_FAILED) << "mmap";
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// Simply mprotect()ing the guard page PROT_NONE does not make it inaccessible
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// using ptrace() or /proc/$pid/mem so we munmap() the following page instead.
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// Unfortunately, this means that the guarded page is not thread safe from
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// other threads mapping a single page into the empty region.
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char* second_page = static_cast<char*>(ptr_) + base::GetPageSize();
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PCHECK(munmap(second_page, base::GetPageSize()) >= 0) << "munmap";
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}
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ScopedGuardedPage::~ScopedGuardedPage() {
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PCHECK(munmap(ptr_, base::GetPageSize()) >= 0) << "munmap";
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}
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} // namespace test
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} // namespace crashpad
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