gvisor/test/syscalls/linux/exec.cc

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// Copyright 2018 Google LLC
//
// 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 "test/syscalls/linux/exec.h"
#include <errno.h>
#include <fcntl.h>
#include <sys/eventfd.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <unistd.h>
#include <memory>
#include <string>
#include <vector>
#include "gtest/gtest.h"
#include "absl/strings/match.h"
#include "absl/strings/numbers.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/str_split.h"
#include "absl/strings/string_view.h"
#include "absl/synchronization/mutex.h"
#include "test/util/file_descriptor.h"
#include "test/util/fs_util.h"
#include "test/util/multiprocess_util.h"
#include "test/util/posix_error.h"
#include "test/util/temp_path.h"
#include "test/util/test_util.h"
#include "test/util/thread_util.h"
namespace gvisor {
namespace testing {
namespace {
constexpr char kBasicWorkload[] = "exec_basic_workload";
constexpr char kExitScript[] = "exit_script";
constexpr char kStateWorkload[] = "exec_state_workload";
constexpr char kProcExeWorkload[] = "exec_proc_exe_workload";
constexpr char kAssertClosedWorkload[] = "exec_assert_closed_workload";
constexpr char kPriorityWorkload[] = "priority_execve";
std::string WorkloadPath(absl::string_view binary) {
std::string full_path;
char* test_src = getenv("TEST_SRCDIR");
if (test_src) {
full_path = JoinPath(test_src, "__main__/test/syscalls/linux", binary);
}
TEST_CHECK(full_path.empty() == false);
return full_path;
}
constexpr char kExit42[] = "--exec_exit_42";
constexpr char kExecWithThread[] = "--exec_exec_with_thread";
constexpr char kExecFromThread[] = "--exec_exec_from_thread";
// Runs filename with argv and checks that the exit status is expect_status and
// that stderr contains expect_stderr.
void CheckOutput(const std::string& filename, const ExecveArray& argv,
const ExecveArray& envv, int expect_status,
const std::string& expect_stderr) {
int pipe_fds[2];
ASSERT_THAT(pipe2(pipe_fds, O_CLOEXEC), SyscallSucceeds());
FileDescriptor read_fd(pipe_fds[0]);
FileDescriptor write_fd(pipe_fds[1]);
pid_t child;
int execve_errno;
const auto remap_stderr = [pipe_fds] {
// Remap stdin and stdout to /dev/null.
int fd = open("/dev/null", O_RDWR | O_CLOEXEC);
if (fd < 0) {
_exit(errno);
}
int ret = dup2(fd, 0);
if (ret < 0) {
_exit(errno);
}
ret = dup2(fd, 1);
if (ret < 0) {
_exit(errno);
}
// And stderr to the pipe.
ret = dup2(pipe_fds[1], 2);
if (ret < 0) {
_exit(errno);
}
// Here, we'd ideally close all other FDs inherited from the parent.
// However, that's not worth the effort and CloexecNormalFile and
// CloexecEventfd depend on that not happening.
};
auto kill = ASSERT_NO_ERRNO_AND_VALUE(
ForkAndExec(filename, argv, envv, remap_stderr, &child, &execve_errno));
ASSERT_EQ(0, execve_errno);
// Not needed anymore.
write_fd.reset();
// Read stderr until the child exits.
std::string output;
constexpr int kSize = 128;
char buf[kSize];
int n;
do {
ASSERT_THAT(n = ReadFd(read_fd.get(), buf, kSize), SyscallSucceeds());
if (n > 0) {
output.append(buf, n);
}
} while (n > 0);
int status;
ASSERT_THAT(RetryEINTR(waitpid)(child, &status, 0), SyscallSucceeds());
EXPECT_EQ(status, expect_status);
// Process cleanup no longer needed.
kill.Release();
EXPECT_TRUE(absl::StrContains(output, expect_stderr)) << output;
}
TEST(ExecDeathTest, EmptyPath) {
int execve_errno;
ASSERT_NO_ERRNO_AND_VALUE(ForkAndExec("", {}, {}, nullptr, &execve_errno));
EXPECT_EQ(execve_errno, ENOENT);
}
TEST(ExecDeathTest, Basic) {
CheckOutput(WorkloadPath(kBasicWorkload), {WorkloadPath(kBasicWorkload)}, {},
ArgEnvExitStatus(0, 0),
absl::StrCat(WorkloadPath(kBasicWorkload), "\n"));
}
TEST(ExecDeathTest, OneArg) {
CheckOutput(WorkloadPath(kBasicWorkload), {WorkloadPath(kBasicWorkload), "1"},
{}, ArgEnvExitStatus(1, 0),
absl::StrCat(WorkloadPath(kBasicWorkload), "\n1\n"));
}
TEST(ExecDeathTest, FiveArg) {
CheckOutput(WorkloadPath(kBasicWorkload),
{WorkloadPath(kBasicWorkload), "1", "2", "3", "4", "5"}, {},
ArgEnvExitStatus(5, 0),
absl::StrCat(WorkloadPath(kBasicWorkload), "\n1\n2\n3\n4\n5\n"));
}
TEST(ExecDeathTest, OneEnv) {
CheckOutput(WorkloadPath(kBasicWorkload), {WorkloadPath(kBasicWorkload)},
{"1"}, ArgEnvExitStatus(0, 1),
absl::StrCat(WorkloadPath(kBasicWorkload), "\n1\n"));
}
TEST(ExecDeathTest, FiveEnv) {
CheckOutput(WorkloadPath(kBasicWorkload), {WorkloadPath(kBasicWorkload)},
{"1", "2", "3", "4", "5"}, ArgEnvExitStatus(0, 5),
absl::StrCat(WorkloadPath(kBasicWorkload), "\n1\n2\n3\n4\n5\n"));
}
TEST(ExecDeathTest, OneArgOneEnv) {
CheckOutput(WorkloadPath(kBasicWorkload),
{WorkloadPath(kBasicWorkload), "arg"}, {"env"},
ArgEnvExitStatus(1, 1),
absl::StrCat(WorkloadPath(kBasicWorkload), "\narg\nenv\n"));
}
TEST(ExecDeathTest, InterpreterScript) {
CheckOutput(WorkloadPath(kExitScript), {WorkloadPath(kExitScript), "25"}, {},
ArgEnvExitStatus(25, 0), "");
}
// Everything after the path in the interpreter script is a single argument.
TEST(ExecDeathTest, InterpreterScriptArgSplit) {
// Symlink through /tmp to ensure the path is short enough.
TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateSymlinkTo("/tmp", WorkloadPath(kBasicWorkload)));
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
GetAbsoluteTestTmpdir(), absl::StrCat("#!", link.path(), " foo bar"),
0755));
CheckOutput(script.path(), {script.path()}, {}, ArgEnvExitStatus(2, 0),
absl::StrCat(link.path(), "\nfoo bar\n", script.path(), "\n"));
}
// Original argv[0] is replaced with the script path.
TEST(ExecDeathTest, InterpreterScriptArgvZero) {
// Symlink through /tmp to ensure the path is short enough.
TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateSymlinkTo("/tmp", WorkloadPath(kBasicWorkload)));
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
GetAbsoluteTestTmpdir(), absl::StrCat("#!", link.path()), 0755));
CheckOutput(script.path(), {"REPLACED"}, {}, ArgEnvExitStatus(1, 0),
absl::StrCat(link.path(), "\n", script.path(), "\n"));
}
// Original argv[0] is replaced with the script path, exactly as passed to
// execve.
TEST(ExecDeathTest, InterpreterScriptArgvZeroRelative) {
// Symlink through /tmp to ensure the path is short enough.
TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateSymlinkTo("/tmp", WorkloadPath(kBasicWorkload)));
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
GetAbsoluteTestTmpdir(), absl::StrCat("#!", link.path()), 0755));
auto cwd = ASSERT_NO_ERRNO_AND_VALUE(GetCWD());
auto script_relative =
ASSERT_NO_ERRNO_AND_VALUE(GetRelativePath(cwd, script.path()));
CheckOutput(script_relative, {"REPLACED"}, {}, ArgEnvExitStatus(1, 0),
absl::StrCat(link.path(), "\n", script_relative, "\n"));
}
// argv[0] is added as the script path, even if there was none.
TEST(ExecDeathTest, InterpreterScriptArgvZeroAdded) {
// Symlink through /tmp to ensure the path is short enough.
TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateSymlinkTo("/tmp", WorkloadPath(kBasicWorkload)));
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
GetAbsoluteTestTmpdir(), absl::StrCat("#!", link.path()), 0755));
CheckOutput(script.path(), {}, {}, ArgEnvExitStatus(1, 0),
absl::StrCat(link.path(), "\n", script.path(), "\n"));
}
// A NUL byte in the script line ends parsing.
TEST(ExecDeathTest, InterpreterScriptArgNUL) {
// Symlink through /tmp to ensure the path is short enough.
TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateSymlinkTo("/tmp", WorkloadPath(kBasicWorkload)));
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
GetAbsoluteTestTmpdir(),
absl::StrCat("#!", link.path(), " foo", std::string(1, '\0'), "bar"), 0755));
CheckOutput(script.path(), {script.path()}, {}, ArgEnvExitStatus(2, 0),
absl::StrCat(link.path(), "\nfoo\n", script.path(), "\n"));
}
// Trailing whitespace following interpreter path is ignored.
TEST(ExecDeathTest, InterpreterScriptTrailingWhitespace) {
// Symlink through /tmp to ensure the path is short enough.
TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateSymlinkTo("/tmp", WorkloadPath(kBasicWorkload)));
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
GetAbsoluteTestTmpdir(), absl::StrCat("#!", link.path(), " "), 0755));
CheckOutput(script.path(), {script.path()}, {}, ArgEnvExitStatus(1, 0),
absl::StrCat(link.path(), "\n", script.path(), "\n"));
}
// Multiple whitespace characters between interpreter and arg allowed.
TEST(ExecDeathTest, InterpreterScriptArgWhitespace) {
// Symlink through /tmp to ensure the path is short enough.
TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateSymlinkTo("/tmp", WorkloadPath(kBasicWorkload)));
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
GetAbsoluteTestTmpdir(), absl::StrCat("#!", link.path(), " foo"), 0755));
CheckOutput(script.path(), {script.path()}, {}, ArgEnvExitStatus(2, 0),
absl::StrCat(link.path(), "\nfoo\n", script.path(), "\n"));
}
TEST(ExecDeathTest, InterpreterScriptNoPath) {
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateFileWith(GetAbsoluteTestTmpdir(), "#!", 0755));
int execve_errno;
ASSERT_NO_ERRNO_AND_VALUE(
ForkAndExec(script.path(), {script.path()}, {}, nullptr, &execve_errno));
EXPECT_EQ(execve_errno, ENOEXEC);
}
// AT_EXECFN is the path passed to execve.
TEST(ExecDeathTest, ExecFn) {
// Symlink through /tmp to ensure the path is short enough.
TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateSymlinkTo("/tmp", WorkloadPath(kStateWorkload)));
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
GetAbsoluteTestTmpdir(), absl::StrCat("#!", link.path(), " PrintExecFn"),
0755));
// Pass the script as a relative path and assert that is what appears in
// AT_EXECFN.
auto cwd = ASSERT_NO_ERRNO_AND_VALUE(GetCWD());
auto script_relative =
ASSERT_NO_ERRNO_AND_VALUE(GetRelativePath(cwd, script.path()));
CheckOutput(script_relative, {script_relative}, {}, ArgEnvExitStatus(0, 0),
absl::StrCat(script_relative, "\n"));
}
TEST(ExecDeathTest, ExecName) {
std::string path = WorkloadPath(kStateWorkload);
CheckOutput(path, {path, "PrintExecName"}, {}, ArgEnvExitStatus(0, 0),
absl::StrCat(Basename(path).substr(0, 15), "\n"));
}
TEST(ExecDeathTest, ExecNameScript) {
// Symlink through /tmp to ensure the path is short enough.
TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateSymlinkTo("/tmp", WorkloadPath(kStateWorkload)));
TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
GetAbsoluteTestTmpdir(),
absl::StrCat("#!", link.path(), " PrintExecName"), 0755));
std::string script_path = script.path();
CheckOutput(script_path, {script_path}, {}, ArgEnvExitStatus(0, 0),
absl::StrCat(Basename(script_path).substr(0, 15), "\n"));
}
// execve may be called by a multithreaded process.
TEST(ExecDeathTest, WithSiblingThread) {
CheckOutput("/proc/self/exe", {"/proc/self/exe", kExecWithThread}, {},
W_EXITCODE(42, 0), "");
}
// execve may be called from a thread other than the leader of a multithreaded
// process.
TEST(ExecDeathTest, FromSiblingThread) {
CheckOutput("/proc/self/exe", {"/proc/self/exe", kExecFromThread}, {},
W_EXITCODE(42, 0), "");
}
TEST(ExecTest, NotFound) {
char* const argv[] = {nullptr};
char* const envp[] = {nullptr};
EXPECT_THAT(execve("/file/does/not/exist", argv, envp),
SyscallFailsWithErrno(ENOENT));
}
TEST(ExecTest, NoExecPerm) {
char* const argv[] = {nullptr};
char* const envp[] = {nullptr};
auto f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
EXPECT_THAT(execve(f.path().c_str(), argv, envp),
SyscallFailsWithErrno(EACCES));
}
// A signal handler we never expect to be called.
void SignalHandler(int signo) {
std::cerr << "Signal " << signo << " raised." << std::endl;
exit(1);
}
// Signal handlers are reset on execve(2), unless they have default or ignored
// disposition.
TEST(ExecStateDeathTest, HandlerReset) {
struct sigaction sa;
sa.sa_handler = SignalHandler;
ASSERT_THAT(sigaction(SIGUSR1, &sa, nullptr), SyscallSucceeds());
ExecveArray args = {
WorkloadPath(kStateWorkload),
"CheckSigHandler",
absl::StrCat(SIGUSR1),
absl::StrCat(absl::Hex(reinterpret_cast<uintptr_t>(SIG_DFL))),
};
CheckOutput(WorkloadPath(kStateWorkload), args, {}, W_EXITCODE(0, 0), "");
}
// Ignored signal dispositions are not reset.
TEST(ExecStateDeathTest, IgnorePreserved) {
struct sigaction sa;
sa.sa_handler = SIG_IGN;
ASSERT_THAT(sigaction(SIGUSR1, &sa, nullptr), SyscallSucceeds());
ExecveArray args = {
WorkloadPath(kStateWorkload),
"CheckSigHandler",
absl::StrCat(SIGUSR1),
absl::StrCat(absl::Hex(reinterpret_cast<uintptr_t>(SIG_IGN))),
};
CheckOutput(WorkloadPath(kStateWorkload), args, {}, W_EXITCODE(0, 0), "");
}
// Signal masks are not reset on exec
TEST(ExecStateDeathTest, SignalMask) {
sigset_t s;
sigemptyset(&s);
sigaddset(&s, SIGUSR1);
ASSERT_THAT(sigprocmask(SIG_BLOCK, &s, nullptr), SyscallSucceeds());
ExecveArray args = {
WorkloadPath(kStateWorkload),
"CheckSigBlocked",
absl::StrCat(SIGUSR1),
};
CheckOutput(WorkloadPath(kStateWorkload), args, {}, W_EXITCODE(0, 0), "");
}
// itimers persist across execve.
// N.B. Timers created with timer_create(2) should not be preserved!
TEST(ExecStateDeathTest, ItimerPreserved) {
// The fork in ForkAndExec clears itimers, so only set them up after fork.
auto setup_itimer = [] {
// Ignore SIGALRM, as we don't actually care about timer
// expirations.
struct sigaction sa;
sa.sa_handler = SIG_IGN;
int ret = sigaction(SIGALRM, &sa, nullptr);
if (ret < 0) {
_exit(errno);
}
struct itimerval itv;
itv.it_interval.tv_sec = 1;
itv.it_interval.tv_usec = 0;
itv.it_value.tv_sec = 1;
itv.it_value.tv_usec = 0;
ret = setitimer(ITIMER_REAL, &itv, nullptr);
if (ret < 0) {
_exit(errno);
}
};
std::string filename = WorkloadPath(kStateWorkload);
ExecveArray argv = {
filename,
"CheckItimerEnabled",
absl::StrCat(ITIMER_REAL),
};
pid_t child;
int execve_errno;
auto kill = ASSERT_NO_ERRNO_AND_VALUE(
ForkAndExec(filename, argv, {}, setup_itimer, &child, &execve_errno));
ASSERT_EQ(0, execve_errno);
int status;
ASSERT_THAT(RetryEINTR(waitpid)(child, &status, 0), SyscallSucceeds());
EXPECT_EQ(0, status);
// Process cleanup no longer needed.
kill.Release();
}
TEST(ProcSelfExe, ChangesAcrossExecve) {
// See exec_proc_exe_workload for more details. We simply
// assert that the /proc/self/exe link changes across execve.
CheckOutput(WorkloadPath(kProcExeWorkload),
{WorkloadPath(kProcExeWorkload),
ASSERT_NO_ERRNO_AND_VALUE(ProcessExePath(getpid()))},
{}, W_EXITCODE(0, 0), "");
}
TEST(ExecTest, CloexecNormalFile) {
const FileDescriptor fd_closed_on_exec = ASSERT_NO_ERRNO_AND_VALUE(
Open("/usr/share/zoneinfo", O_RDONLY | O_CLOEXEC));
CheckOutput(WorkloadPath(kAssertClosedWorkload),
{WorkloadPath(kAssertClosedWorkload),
absl::StrCat(fd_closed_on_exec.get())},
{}, W_EXITCODE(0, 0), "");
// The assert closed workload exits with code 2 if the file still exists. We
// can use this to do a negative test.
const FileDescriptor fd_open_on_exec =
ASSERT_NO_ERRNO_AND_VALUE(Open("/usr/share/zoneinfo", O_RDONLY));
CheckOutput(WorkloadPath(kAssertClosedWorkload),
{WorkloadPath(kAssertClosedWorkload),
absl::StrCat(fd_open_on_exec.get())},
{}, W_EXITCODE(2, 0), "");
}
TEST(ExecTest, CloexecEventfd) {
int efd;
ASSERT_THAT(efd = eventfd(0, EFD_CLOEXEC), SyscallSucceeds());
FileDescriptor fd(efd);
CheckOutput(WorkloadPath(kAssertClosedWorkload),
{WorkloadPath(kAssertClosedWorkload), absl::StrCat(fd.get())}, {},
W_EXITCODE(0, 0), "");
}
// Priority consistent across calls to execve()
TEST(GetpriorityTest, ExecveMaintainsPriority) {
int prio = 16;
ASSERT_THAT(setpriority(PRIO_PROCESS, getpid(), prio), SyscallSucceeds());
// To avoid trying to use negative exit values, check for
// 20 - prio. Since prio should always be in the range [-20, 19],
// this leave expected_exit_code in the range [1, 40].
int expected_exit_code = 20 - prio;
// Program run (priority_execve) will exit(X) where
// X=getpriority(PRIO_PROCESS,0). Check that this exit value is prio.
CheckOutput(WorkloadPath(kPriorityWorkload),
{WorkloadPath(kPriorityWorkload)}, {},
W_EXITCODE(expected_exit_code, 0), "");
}
void ExecWithThread() {
// Used to ensure that the thread has actually started.
absl::Mutex mu;
bool started = false;
ScopedThread t([&] {
mu.Lock();
started = true;
mu.Unlock();
while (true) {
pause();
}
});
mu.LockWhen(absl::Condition(&started));
mu.Unlock();
const ExecveArray argv = {"/proc/self/exe", kExit42};
const ExecveArray envv;
execve("/proc/self/exe", argv.get(), envv.get());
exit(errno);
}
void ExecFromThread() {
ScopedThread t([] {
const ExecveArray argv = {"/proc/self/exe", kExit42};
const ExecveArray envv;
execve("/proc/self/exe", argv.get(), envv.get());
exit(errno);
});
while (true) {
pause();
}
}
bool ValidateProcCmdlineVsArgv(const int argc, const char* const* argv) {
auto contents_or = GetContents("/proc/self/cmdline");
if (!contents_or.ok()) {
LOG(ERROR) << "Unable to get /proc/self/cmdline: " << contents_or.error();
return false;
}
auto contents = contents_or.ValueOrDie();
if (contents.back() != '\0') {
LOG(ERROR) << "Non-null terminated /proc/self/cmdline!";
return false;
}
contents.pop_back();
std::vector<std::string> procfs_cmdline = absl::StrSplit(contents, '\0');
if (static_cast<int>(procfs_cmdline.size()) != argc) {
LOG(ERROR) << "argc = " << argc << " != " << procfs_cmdline.size();
return false;
}
for (int i = 0; i < argc; ++i) {
if (procfs_cmdline[i] != argv[i]) {
LOG(ERROR) << "Procfs command line argument " << i << " mismatch "
<< procfs_cmdline[i] << " != " << argv[i];
return false;
}
}
return true;
}
} // namespace
} // namespace testing
} // namespace gvisor
int main(int argc, char** argv) {
// Start by validating that the stack argv is consistent with procfs.
if (!gvisor::testing::ValidateProcCmdlineVsArgv(argc, argv)) {
return 1;
}
// Some of these tests require no background threads, so check for them before
// TestInit.
for (int i = 0; i < argc; i++) {
absl::string_view arg(argv[i]);
if (arg == gvisor::testing::kExit42) {
return 42;
}
if (arg == gvisor::testing::kExecWithThread) {
gvisor::testing::ExecWithThread();
return 1;
}
if (arg == gvisor::testing::kExecFromThread) {
gvisor::testing::ExecFromThread();
return 1;
}
}
gvisor::testing::TestInit(&argc, &argv);
return RUN_ALL_TESTS();
}