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385fe6615f
This also enhances ScopedMmapDeathTest.Mprotect to better ensure that ScopedMmap::Mprotect() works properly. Bug: crashpad:30 Test: crashpad_util_test ScopedMmap*.* Change-Id: Iff35dba9fa993086f3f4cd8f4a862d802e637bb1 Reviewed-on: https://chromium-review.googlesource.com/464547 Reviewed-by: Joshua Peraza <jperaza@chromium.org>
116 lines
3.0 KiB
C++
116 lines
3.0 KiB
C++
// Copyright 2017 The Crashpad Authors. All rights reserved.
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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 "util/posix/scoped_mmap.h"
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#include <unistd.h>
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#include <algorithm>
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#include "base/logging.h"
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#include "base/numerics/safe_math.h"
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namespace {
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bool Munmap(uintptr_t addr, size_t len) {
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if (munmap(reinterpret_cast<void*>(addr), len) != 0) {
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PLOG(ERROR) << "munmap";
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return false;
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}
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return true;
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}
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} // namespace
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namespace crashpad {
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ScopedMmap::ScopedMmap() {}
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ScopedMmap::~ScopedMmap() {
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if (is_valid()) {
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Munmap(reinterpret_cast<uintptr_t>(addr_), len_);
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}
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}
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bool ScopedMmap::Reset() {
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return ResetAddrLen(MAP_FAILED, 0);
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}
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bool ScopedMmap::ResetAddrLen(void* addr, size_t len) {
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const uintptr_t new_addr = reinterpret_cast<uintptr_t>(addr);
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if (addr == MAP_FAILED) {
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DCHECK_EQ(len, 0u);
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} else {
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DCHECK_NE(len, 0u);
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DCHECK_EQ(new_addr % getpagesize(), 0u);
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DCHECK_EQ(len % getpagesize(), 0u);
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DCHECK((base::CheckedNumeric<uintptr_t>(new_addr) + (len - 1)).IsValid());
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}
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bool result = true;
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if (is_valid()) {
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const uintptr_t old_addr = reinterpret_cast<uintptr_t>(addr_);
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if (old_addr < new_addr) {
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result &= Munmap(old_addr, std::min(len_, new_addr - old_addr));
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}
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if (old_addr + len_ > new_addr + len) {
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uintptr_t unmap_start = std::max(old_addr, new_addr + len);
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result &= Munmap(unmap_start, old_addr + len_ - unmap_start);
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}
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}
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addr_ = addr;
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len_ = len;
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return result;
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}
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bool ScopedMmap::ResetMmap(void* addr,
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size_t len,
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int prot,
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int flags,
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int fd,
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off_t offset) {
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// Reset() first, so that a new anonymous mapping can use the address space
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// occupied by the old mapping if appropriate. The new mapping will be
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// attempted even if there was something wrong with the old mapping, so don’t
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// consider the return value from Reset().
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Reset();
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void* new_addr = mmap(addr, len, prot, flags, fd, offset);
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if (new_addr == MAP_FAILED) {
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PLOG(ERROR) << "mmap";
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return false;
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}
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// The new mapping is effective even if there was something wrong with the old
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// mapping, so don’t consider the return value from ResetAddrLen().
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ResetAddrLen(new_addr, len);
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return true;
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}
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bool ScopedMmap::Mprotect(int prot) {
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if (mprotect(addr_, len_, prot) < 0) {
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PLOG(ERROR) << "mprotect";
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return false;
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}
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return true;
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}
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} // namespace crashpad
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