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// Copyright 2021 The gVisor Authors.
//
// 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 <stdint.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <string>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "test/util/capability_util.h"
#include "test/util/fs_util.h"
#include "test/util/memory_util.h"
#include "test/util/temp_path.h"
#include "test/util/test_util.h"
#include "test/util/verity_util.h"
namespace gvisor {
namespace testing {
namespace {
class MmapTest : public ::testing::Test {
protected:
void SetUp() override {
// Verity is implemented in VFS2.
SKIP_IF(IsRunningWithVFS1());
SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN)));
// Mount a tmpfs file system, to be wrapped by a verity fs.
tmpfs_dir_ = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
ASSERT_THAT(mount("", tmpfs_dir_.path().c_str(), "tmpfs", 0, ""),
SyscallSucceeds());
// Create a new file in the tmpfs mount.
file_ = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateFileWith(tmpfs_dir_.path(), kContents, 0777));
filename_ = Basename(file_.path());
}
TempPath tmpfs_dir_;
TempPath file_;
std::string filename_;
};
TEST_F(MmapTest, MmapRead) {
std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(
MountVerity(tmpfs_dir_.path(), filename_, /*targets=*/{}));
// Make sure the file can be open and mmapped in the mounted verity fs.
auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(verity_dir, filename_), O_RDONLY, 0777));
Mapping const m =
ASSERT_NO_ERRNO_AND_VALUE(Mmap(nullptr, sizeof(kContents) - 1, PROT_READ,
MAP_SHARED, verity_fd.get(), 0));
EXPECT_THAT(std::string(m.view()), ::testing::StrEq(kContents));
}
TEST_F(MmapTest, ModifiedBeforeMmap) {
std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(
MountVerity(tmpfs_dir_.path(), filename_, /*targets=*/{}));
// Modify the file and check verification failure upon mmapping.
auto const fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(tmpfs_dir_.path(), filename_), O_RDWR, 0777));
ASSERT_NO_ERRNO(FlipRandomBit(fd.get(), sizeof(kContents) - 1));
auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(verity_dir, filename_), O_RDONLY, 0777));
Mapping const m =
ASSERT_NO_ERRNO_AND_VALUE(Mmap(nullptr, sizeof(kContents) - 1, PROT_READ,
MAP_SHARED, verity_fd.get(), 0));
// Memory fault is expected when Translate fails.
EXPECT_EXIT(std::string(m.view()), ::testing::KilledBySignal(SIGSEGV), "");
}
TEST_F(MmapTest, ModifiedAfterMmap) {
std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(
MountVerity(tmpfs_dir_.path(), filename_, /*targets=*/{}));
auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(verity_dir, filename_), O_RDONLY, 0777));
Mapping const m =
ASSERT_NO_ERRNO_AND_VALUE(Mmap(nullptr, sizeof(kContents) - 1, PROT_READ,
MAP_SHARED, verity_fd.get(), 0));
// Modify the file after mapping and check verification failure upon mmapping.
auto const fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(tmpfs_dir_.path(), filename_), O_RDWR, 0777));
ASSERT_NO_ERRNO(FlipRandomBit(fd.get(), sizeof(kContents) - 1));
// Memory fault is expected when Translate fails.
EXPECT_EXIT(std::string(m.view()), ::testing::KilledBySignal(SIGSEGV), "");
}
class MmapParamTest
: public MmapTest,
public ::testing::WithParamInterface<std::tuple<int, int>> {
protected:
int prot() const { return std::get<0>(GetParam()); }
int flags() const { return std::get<1>(GetParam()); }
};
INSTANTIATE_TEST_SUITE_P(
WriteExecNoneSharedPrivate, MmapParamTest,
::testing::Combine(::testing::ValuesIn({
PROT_WRITE,
PROT_EXEC,
PROT_NONE,
}),
::testing::ValuesIn({MAP_SHARED, MAP_PRIVATE})));
TEST_P(MmapParamTest, Mmap) {
std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(
MountVerity(tmpfs_dir_.path(), filename_, /*targets=*/{}));
// Make sure the file can be open and mmapped in the mounted verity fs.
auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(verity_dir, filename_), O_RDONLY, 0777));
if (prot() == PROT_WRITE && flags() == MAP_SHARED) {
// Verity file system is read-only.
EXPECT_THAT(
reinterpret_cast<intptr_t>(mmap(nullptr, sizeof(kContents) - 1, prot(),
flags(), verity_fd.get(), 0)),
SyscallFailsWithErrno(EACCES));
} else {
Mapping const m = ASSERT_NO_ERRNO_AND_VALUE(Mmap(
nullptr, sizeof(kContents) - 1, prot(), flags(), verity_fd.get(), 0));
if (prot() == PROT_NONE) {
// Memory mapped by MAP_NONE cannot be accessed.
EXPECT_EXIT(std::string(m.view()), ::testing::KilledBySignal(SIGSEGV),
"");
} else {
EXPECT_THAT(std::string(m.view()), ::testing::StrEq(kContents));
}
}
}
} // namespace
} // namespace testing
} // namespace gvisor
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