crashpad/util/linux/memory_map_test.cc

// Copyright 2017 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "util/linux/memory_map.h"

#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>

#include "base/files/file_path.h"
#include "gtest/gtest.h"
#include "test/errors.h"
#include "test/file.h"
#include "test/multiprocess.h"
#include "test/scoped_temp_dir.h"
#include "util/file/file_io.h"
#include "util/misc/clock.h"
#include "util/posix/scoped_mmap.h"

namespace crashpad {
namespace test {
namespace {

TEST(MemoryMap, SelfBasic) {
  ScopedMmap mmapping;
  ASSERT_TRUE(mmapping.ResetMmap(nullptr,
                                 getpagesize(),
                                 PROT_EXEC | PROT_READ,
                                 MAP_SHARED | MAP_ANON,
                                 -1,
                                 0));
  MemoryMap map;
  ASSERT_TRUE(map.Initialize(getpid()));

  auto stack_address = reinterpret_cast<LinuxVMAddress>(&map);
  const MemoryMap::Mapping* mapping = map.FindMapping(stack_address);
  ASSERT_TRUE(mapping);
  EXPECT_GE(stack_address, mapping->range.Base());
  EXPECT_LT(stack_address, mapping->range.End());
  EXPECT_TRUE(mapping->readable);
  EXPECT_TRUE(mapping->writable);

  auto code_address = reinterpret_cast<LinuxVMAddress>(getpid);
  mapping = map.FindMapping(code_address);
  ASSERT_TRUE(mapping);
  EXPECT_GE(code_address, mapping->range.Base());
  EXPECT_LT(code_address, mapping->range.End());
  EXPECT_TRUE(mapping->readable);
  EXPECT_FALSE(mapping->writable);
  EXPECT_TRUE(mapping->executable);

  auto mapping_address = mmapping.addr_as<LinuxVMAddress>();
  mapping = map.FindMapping(mapping_address);
  ASSERT_TRUE(mapping);
  mapping = map.FindMapping(mapping_address + mmapping.len() - 1);
  ASSERT_TRUE(mapping);
  EXPECT_EQ(mapping_address, mapping->range.Base());
  EXPECT_EQ(mapping_address + mmapping.len(), mapping->range.End());
  EXPECT_TRUE(mapping->readable);
  EXPECT_FALSE(mapping->writable);
  EXPECT_TRUE(mapping->executable);
  EXPECT_TRUE(mapping->shareable);
}

class MapChildTest : public Multiprocess {
 public:
  MapChildTest() : Multiprocess(), page_size_(getpagesize()) {}
  ~MapChildTest() {}

 private:
  void MultiprocessParent() override {
    LinuxVMAddress code_address;
    CheckedReadFileExactly(
        ReadPipeHandle(), &code_address, sizeof(code_address));

    LinuxVMAddress stack_address;
    CheckedReadFileExactly(
        ReadPipeHandle(), &stack_address, sizeof(stack_address));

    LinuxVMAddress mapped_address;
    CheckedReadFileExactly(
        ReadPipeHandle(), &mapped_address, sizeof(mapped_address));

    LinuxVMAddress mapped_file_address;
    CheckedReadFileExactly(
        ReadPipeHandle(), &mapped_file_address, sizeof(mapped_file_address));
    LinuxVMSize path_length;
    CheckedReadFileExactly(ReadPipeHandle(), &path_length, sizeof(path_length));
    std::string mapped_file_name(path_length, std::string::value_type());
    CheckedReadFileExactly(ReadPipeHandle(), &mapped_file_name[0], path_length);

    MemoryMap map;
    ASSERT_TRUE(map.Initialize(ChildPID()));

    const MemoryMap::Mapping* mapping = map.FindMapping(code_address);
    ASSERT_TRUE(mapping);
    EXPECT_GE(code_address, mapping->range.Base());
    EXPECT_LT(code_address, mapping->range.End());
    EXPECT_TRUE(mapping->readable);
    EXPECT_TRUE(mapping->executable);
    EXPECT_FALSE(mapping->writable);

    mapping = map.FindMapping(stack_address);
    ASSERT_TRUE(mapping);
    EXPECT_GE(stack_address, mapping->range.Base());
    EXPECT_LT(stack_address, mapping->range.End());
    EXPECT_TRUE(mapping->readable);
    EXPECT_TRUE(mapping->writable);

    mapping = map.FindMapping(mapped_address);
    ASSERT_TRUE(mapping);
    EXPECT_EQ(mapped_address, mapping->range.Base());
    EXPECT_EQ(mapped_address + page_size_, mapping->range.End());
    EXPECT_FALSE(mapping->readable);
    EXPECT_FALSE(mapping->writable);
    EXPECT_FALSE(mapping->executable);
    EXPECT_TRUE(mapping->shareable);

    mapping = map.FindMapping(mapped_file_address);
    ASSERT_TRUE(mapping);
    EXPECT_EQ(mapped_file_address, mapping->range.Base());
    EXPECT_EQ(mapping->offset, static_cast<int64_t>(page_size_));
    EXPECT_TRUE(mapping->readable);
    EXPECT_TRUE(mapping->writable);
    EXPECT_FALSE(mapping->executable);
    EXPECT_FALSE(mapping->shareable);
    EXPECT_EQ(mapping->name, mapped_file_name);
    struct stat file_stat;
    ASSERT_EQ(stat(mapped_file_name.c_str(), &file_stat), 0)
        << ErrnoMessage("stat");
    EXPECT_EQ(mapping->device, file_stat.st_dev);
    EXPECT_EQ(mapping->inode, file_stat.st_ino);
  }

  void MultiprocessChild() override {
    auto code_address = reinterpret_cast<LinuxVMAddress>(getpid);
    CheckedWriteFile(WritePipeHandle(), &code_address, sizeof(code_address));

    auto stack_address = reinterpret_cast<LinuxVMAddress>(&code_address);
    CheckedWriteFile(WritePipeHandle(), &stack_address, sizeof(stack_address));

    ScopedMmap mapping;
    ASSERT_TRUE(mapping.ResetMmap(
        nullptr, page_size_, PROT_NONE, MAP_SHARED | MAP_ANON, -1, 0));
    auto mapped_address = mapping.addr_as<LinuxVMAddress>();
    CheckedWriteFile(
        WritePipeHandle(), &mapped_address, sizeof(mapped_address));

    ScopedTempDir temp_dir;
    base::FilePath path =
        temp_dir.path().Append(FILE_PATH_LITERAL("test_file"));
    ASSERT_FALSE(FileExists(path));
    std::string path_string = path.value();
    ScopedFileHandle handle(LoggingOpenFileForReadAndWrite(
        path, FileWriteMode::kReuseOrCreate, FilePermissions::kOwnerOnly));
    ASSERT_TRUE(handle.is_valid());
    std::unique_ptr<char[]> file_contents(new char[page_size_ * 2]);
    CheckedWriteFile(handle.get(), file_contents.get(), page_size_ * 2);

    ScopedMmap file_mapping;
    ASSERT_TRUE(file_mapping.ResetMmap(nullptr,
                                       page_size_,
                                       PROT_READ | PROT_WRITE,
                                       MAP_PRIVATE,
                                       handle.get(),
                                       page_size_));

    auto mapped_file_address = file_mapping.addr_as<LinuxVMAddress>();
    CheckedWriteFile(
        WritePipeHandle(), &mapped_file_address, sizeof(mapped_file_address));
    LinuxVMSize path_length = path_string.size();
    CheckedWriteFile(WritePipeHandle(), &path_length, sizeof(path_length));
    CheckedWriteFile(WritePipeHandle(), path_string.c_str(), path_length);

    CheckedReadFileAtEOF(ReadPipeHandle());
  }

  const size_t page_size_;

  DISALLOW_COPY_AND_ASSIGN(MapChildTest);
};

TEST(MemoryMap, MapChild) {
  MapChildTest test;
  test.Run();
}

// Some systems optimize mappings by allocating new mappings inside existing
// mappings with matching permissions. Work around this by allocating one large
// mapping and then switching up the permissions of individual pages to force
// populating more entries in the maps file.
void InitializeMappings(ScopedMmap* mappings,
                        size_t num_mappings,
                        size_t mapping_size) {
  ASSERT_TRUE(mappings->ResetMmap(nullptr,
                                  mapping_size * num_mappings,
                                  PROT_READ,
                                  MAP_PRIVATE | MAP_ANON,
                                  -1,
                                  0));

  auto region = mappings->addr_as<LinuxVMAddress>();
  for (size_t index = 0; index < num_mappings; index += 2) {
    ASSERT_EQ(mprotect(reinterpret_cast<void*>(region + index * mapping_size),
                       mapping_size,
                       PROT_READ | PROT_WRITE),
              0)
        << ErrnoMessage("mprotect");
  }
}

void ExpectMappings(const MemoryMap& map,
                    LinuxVMAddress region_addr,
                    size_t num_mappings,
                    size_t mapping_size) {
  for (size_t index = 0; index < num_mappings; ++index) {
    auto mapping_address = region_addr + index * mapping_size;
    const MemoryMap::Mapping* mapping = map.FindMapping(mapping_address);
    ASSERT_TRUE(mapping);
    EXPECT_EQ(mapping_address, mapping->range.Base());
    EXPECT_EQ(mapping_address + mapping_size, mapping->range.End());
    EXPECT_TRUE(mapping->readable);
    EXPECT_FALSE(mapping->shareable);
    EXPECT_FALSE(mapping->executable);
    if (index % 2 == 0) {
      EXPECT_TRUE(mapping->writable);
    } else {
      EXPECT_FALSE(mapping->writable);
    }
  }
}

TEST(MemoryMap, SelfLargeMapFile) {
  constexpr size_t kNumMappings = 4096;
  const size_t page_size = getpagesize();
  ScopedMmap mappings;

  ASSERT_NO_FATAL_FAILURE(
      InitializeMappings(&mappings, kNumMappings, page_size));

  MemoryMap map;
  ASSERT_TRUE(map.Initialize(getpid()));

  ExpectMappings(
      map, mappings.addr_as<LinuxVMAddress>(), kNumMappings, page_size);
}

class MapRunningChildTest : public Multiprocess {
 public:
  MapRunningChildTest() : Multiprocess(), page_size_(getpagesize()) {}
  ~MapRunningChildTest() {}

 private:
  void MultiprocessParent() override {
    // Let the child get started
    LinuxVMAddress region_addr;
    CheckedReadFileExactly(ReadPipeHandle(), &region_addr, sizeof(region_addr));

    // Let the child get back to its work
    SleepNanoseconds(1000);

    for (int iter = 0; iter < 8; ++iter) {
      MemoryMap map;
      ASSERT_TRUE(map.Initialize(ChildPID()));

      // We should at least find the original mappings. The extra mappings may
      // or
      // not be found depending on scheduling.
      ExpectMappings(map, region_addr, kNumMappings, page_size_);
    }
  }

  void MultiprocessChild() override {
    ASSERT_EQ(fcntl(ReadPipeHandle(), F_SETFL, O_NONBLOCK), 0)
        << ErrnoMessage("fcntl");

    ScopedMmap mappings;
    ASSERT_NO_FATAL_FAILURE(
        InitializeMappings(&mappings, kNumMappings, page_size_));

    // Let the parent start mapping us
    auto region_addr = mappings.addr_as<LinuxVMAddress>();
    CheckedWriteFile(WritePipeHandle(), &region_addr, sizeof(region_addr));

    // But don't stop there!
    constexpr size_t kNumExtraMappings = 1024;
    ScopedMmap extra_mappings;

    while (true) {
      ASSERT_NO_FATAL_FAILURE(
          InitializeMappings(&extra_mappings, kNumExtraMappings, page_size_));

      // Quit when the parent is done
      char c;
      FileOperationResult res = ReadFile(ReadPipeHandle(), &c, sizeof(c));
      if (res == 0) {
        break;
      }
      ASSERT_EQ(errno, EAGAIN);
    }
  }

  static constexpr size_t kNumMappings = 4096;
  const size_t page_size_;

  DISALLOW_COPY_AND_ASSIGN(MapRunningChildTest);
};

TEST(MemoryMap, MapRunningChild) {
  MapRunningChildTest test;
  test.Run();
}

}  // namespace
}  // namespace test
}  // namespace crashpad