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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "sandbox/mac/seatbelt_extension.h"
#include <sys/stat.h>
#include <unistd.h>
#include "base/command_line.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/files/scoped_file.h"
#include "base/files/scoped_temp_dir.h"
#include "base/test/bind.h"
#include "base/test/multiprocess_test.h"
#include "base/test/test_timeouts.h"
#include "sandbox/mac/sandbox_serializer.h"
#include "sandbox/mac/sandbox_test.h"
#include "sandbox/mac/seatbelt_extension_token.h"
#include "testing/multiprocess_func_list.h"
namespace sandbox {
namespace {
const char kSandboxProfile[] = R"(
(version 1)
(deny default (with no-log))
(allow file-read* (extension "com.apple.app-sandbox.read"))
(allow file-read* file-write*
(extension "com.apple.app-sandbox.read-write")
)
)";
const char kTestData[] = "hello world";
const char kSwitchFile[] = "test-file";
const char kSwitchExtension[] = "test-extension";
class SeatbeltExtensionTest : public SandboxTest {
public:
void SetUp() override {
ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
file_path_ = temp_dir_.GetPath().AppendASCII("sbox.test");
ASSERT_TRUE(base::WriteFile(file_path_, kTestData));
}
base::FilePath file_path() { return file_path_; }
base::Process SpawnChildForPathWithToken(
const std::string& procname,
const base::FilePath& path,
const SeatbeltExtensionToken& token) {
// Ensure any symlinks in the path are canonicalized.
const base::FilePath canonicalized_path = base::MakeAbsoluteFilePath(path);
const std::string token_value = token.token();
CHECK(!canonicalized_path.empty());
CHECK(!token_value.empty());
return SpawnChild(
procname,
base::BindLambdaForTesting([&](base::CommandLine& command_line) {
command_line.AppendSwitchPath(kSwitchFile, canonicalized_path);
command_line.AppendSwitchASCII(kSwitchExtension, token_value);
}));
}
private:
base::ScopedTempDir temp_dir_;
base::FilePath file_path_;
};
TEST_F(SeatbeltExtensionTest, FileReadAccess) {
base::CommandLine command_line(
base::GetMultiProcessTestChildBaseCommandLine());
auto token = SeatbeltExtension::Issue(SeatbeltExtension::FILE_READ,
file_path().value());
ASSERT_TRUE(token.get());
base::Process test_child =
SpawnChildForPathWithToken("FileReadAccess", file_path(), *token);
int exit_code = 42;
test_child.WaitForExitWithTimeout(TestTimeouts::action_max_timeout(),
&exit_code);
EXPECT_EQ(0, exit_code);
}
MULTIPROCESS_TEST_MAIN(FileReadAccess) {
SandboxSerializer serializer(SandboxSerializer::Target::kSource);
serializer.SetProfile(kSandboxProfile);
std::string error, serialized;
CHECK(serializer.SerializePolicy(serialized, error)) << error;
CHECK(serializer.ApplySerializedPolicy(serialized));
auto* command_line = base::CommandLine::ForCurrentProcess();
base::FilePath file_path = command_line->GetSwitchValuePath(kSwitchFile);
CHECK(!file_path.empty());
const char* path = file_path.value().c_str();
std::string token_str = command_line->GetSwitchValueASCII(kSwitchExtension);
CHECK(!token_str.empty());
auto token = SeatbeltExtensionToken::CreateForTesting(token_str);
auto extension = SeatbeltExtension::FromToken(std::move(token));
CHECK(extension);
CHECK(token.token().empty());
// Without consuming the extension, file access is denied.
errno = 0;
base::ScopedFD fd(open(path, O_RDONLY));
CHECK_EQ(-1, fd.get());
CHECK_EQ(EPERM, errno);
CHECK(extension->Consume());
// After consuming the extension, file access is still denied for writing.
errno = 0;
fd.reset(open(path, O_RDWR));
CHECK_EQ(-1, fd.get());
CHECK_EQ(EPERM, errno);
// ... but it is allowed to read.
errno = 0;
fd.reset(open(path, O_RDONLY));
PCHECK(fd.get() > 0);
// Close the file and revoke the extension.
fd.reset();
extension->Revoke();
// File access is denied again.
errno = 0;
fd.reset(open(path, O_RDONLY));
CHECK_EQ(-1, fd.get());
CHECK_EQ(EPERM, errno);
// Re-acquire the access by using the token, but this time consume it
// permanetly.
token = SeatbeltExtensionToken::CreateForTesting(token_str);
extension = SeatbeltExtension::FromToken(std::move(token));
CHECK(extension);
CHECK(extension->ConsumePermanently());
// Check that reading still works.
errno = 0;
fd.reset(open(path, O_RDONLY));
PCHECK(fd.get() > 0);
return 0;
}
TEST_F(SeatbeltExtensionTest, DirReadWriteAccess) {
base::CommandLine command_line(
base::GetMultiProcessTestChildBaseCommandLine());
auto token = SeatbeltExtension::Issue(SeatbeltExtension::FILE_READ_WRITE,
file_path().DirName().value());
ASSERT_TRUE(token.get());
base::Process test_child =
SpawnChildForPathWithToken("DirReadWriteAccess", file_path(), *token);
int exit_code = 42;
test_child.WaitForExitWithTimeout(TestTimeouts::action_max_timeout(),
&exit_code);
EXPECT_EQ(0, exit_code);
}
MULTIPROCESS_TEST_MAIN(DirReadWriteAccess) {
SandboxSerializer serializer(SandboxSerializer::Target::kSource);
serializer.SetProfile(kSandboxProfile);
std::string serialized, error;
CHECK(serializer.SerializePolicy(serialized, error)) << error;
CHECK(serializer.ApplySerializedPolicy(serialized));
auto* command_line = base::CommandLine::ForCurrentProcess();
base::FilePath file_path = command_line->GetSwitchValuePath(kSwitchFile);
CHECK(!file_path.empty());
const char* path = file_path.value().c_str();
std::string token_str = command_line->GetSwitchValueASCII(kSwitchExtension);
CHECK(!token_str.empty());
auto token = SeatbeltExtensionToken::CreateForTesting(token_str);
auto extension = SeatbeltExtension::FromToken(std::move(token));
CHECK(extension);
CHECK(token.token().empty());
// Without consuming the extension, file access is denied.
errno = 0;
base::ScopedFD fd(open(path, O_RDONLY));
CHECK_EQ(-1, fd.get());
CHECK_EQ(EPERM, errno);
CHECK(extension->ConsumePermanently());
// After consuming the extension, file read/write access is allowed.
errno = 0;
fd.reset(open(path, O_RDWR));
PCHECK(fd.get() > 0);
char c = 'a';
PCHECK(write(fd.get(), &c, sizeof(c)) == sizeof(c));
// A new file can be created in the extension directory.
base::FilePath new_file = file_path.DirName().AppendASCII("new_file.txt");
fd.reset(open(path, O_RDWR | O_CREAT));
PCHECK(fd.get() > 0);
// Test reading and writing to the new file.
PCHECK(write(fd.get(), &c, sizeof(c)) == sizeof(c));
PCHECK(lseek(fd.get(), 0, SEEK_SET) == 0);
c = 'b';
PCHECK(read(fd.get(), &c, sizeof(c)) == sizeof(c));
CHECK_EQ(c, 'a');
// Accessing the parent directory is forbidden.
errno = 0;
struct stat sb;
PCHECK(stat(file_path.DirName().DirName().value().c_str(), &sb) == -1);
CHECK_EQ(EPERM, errno);
// ... but the dir itself is okay.
errno = 0;
PCHECK(stat(file_path.DirName().value().c_str(), &sb) == 0);
return 0;
}
} // namespace
} // namespace sandbox
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