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Diffstat (limited to 'test/syscalls/linux/ptrace.cc')
| -rw-r--r-- | test/syscalls/linux/ptrace.cc | 1215 |
1 files changed, 0 insertions, 1215 deletions
diff --git a/test/syscalls/linux/ptrace.cc b/test/syscalls/linux/ptrace.cc deleted file mode 100644 index 8f3800380..000000000 --- a/test/syscalls/linux/ptrace.cc +++ /dev/null @@ -1,1215 +0,0 @@ -// Copyright 2018 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 <elf.h> -#include <signal.h> -#include <stddef.h> -#include <sys/ptrace.h> -#include <sys/time.h> -#include <sys/types.h> -#include <sys/user.h> -#include <sys/wait.h> -#include <unistd.h> - -#include <iostream> -#include <utility> - -#include "gmock/gmock.h" -#include "gtest/gtest.h" -#include "absl/flags/flag.h" -#include "absl/time/clock.h" -#include "absl/time/time.h" -#include "test/util/logging.h" -#include "test/util/multiprocess_util.h" -#include "test/util/signal_util.h" -#include "test/util/test_util.h" -#include "test/util/thread_util.h" -#include "test/util/time_util.h" - -ABSL_FLAG(bool, ptrace_test_execve_child, false, - "If true, run the " - "PtraceExecveTest_Execve_GetRegs_PeekUser_SIGKILL_TraceClone_" - "TraceExit child workload."); - -namespace gvisor { -namespace testing { - -namespace { - -// PTRACE_GETSIGMASK and PTRACE_SETSIGMASK are not defined until glibc 2.23 -// (fb53a27c5741 "Add new header definitions from Linux 4.4 (plus older ptrace -// definitions)"). -constexpr auto kPtraceGetSigMask = static_cast<__ptrace_request>(0x420a); -constexpr auto kPtraceSetSigMask = static_cast<__ptrace_request>(0x420b); - -// PTRACE_SYSEMU is not defined until glibc 2.27 (c48831d0eebf "linux/x86: sync -// sys/ptrace.h with Linux 4.14 [BZ #22433]"). -constexpr auto kPtraceSysemu = static_cast<__ptrace_request>(31); - -// PTRACE_EVENT_STOP is not defined until glibc 2.26 (3f67d1a7021e "Add Linux -// PTRACE_EVENT_STOP"). -constexpr int kPtraceEventStop = 128; - -// Sends sig to the current process with tgkill(2). -// -// glibc's raise(2) may change the signal mask before sending the signal. These -// extra syscalls make tests of syscall, signal interception, etc. difficult to -// write. -void RaiseSignal(int sig) { - pid_t pid = getpid(); - TEST_PCHECK(pid > 0); - pid_t tid = gettid(); - TEST_PCHECK(tid > 0); - TEST_PCHECK(tgkill(pid, tid, sig) == 0); -} - -// Returns the Yama ptrace scope. -PosixErrorOr<int> YamaPtraceScope() { - constexpr char kYamaPtraceScopePath[] = "/proc/sys/kernel/yama/ptrace_scope"; - - ASSIGN_OR_RETURN_ERRNO(bool exists, Exists(kYamaPtraceScopePath)); - if (!exists) { - // File doesn't exist means no Yama, so the scope is disabled -> 0. - return 0; - } - - std::string contents; - RETURN_IF_ERRNO(GetContents(kYamaPtraceScopePath, &contents)); - - int scope; - if (!absl::SimpleAtoi(contents, &scope)) { - return PosixError(EINVAL, absl::StrCat(contents, ": not a valid number")); - } - - return scope; -} - -TEST(PtraceTest, AttachSelf) { - EXPECT_THAT(ptrace(PTRACE_ATTACH, gettid(), 0, 0), - SyscallFailsWithErrno(EPERM)); -} - -TEST(PtraceTest, AttachSameThreadGroup) { - pid_t const tid = gettid(); - ScopedThread([&] { - EXPECT_THAT(ptrace(PTRACE_ATTACH, tid, 0, 0), SyscallFailsWithErrno(EPERM)); - }); -} - -TEST(PtraceTest, AttachParent_PeekData_PokeData_SignalSuppression) { - // Yama prevents attaching to a parent. Skip the test if the scope is anything - // except disabled. - SKIP_IF(ASSERT_NO_ERRNO_AND_VALUE(YamaPtraceScope()) > 0); - - constexpr long kBeforePokeDataValue = 10; - constexpr long kAfterPokeDataValue = 20; - - volatile long word = kBeforePokeDataValue; - - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - - // Attach to the parent. - pid_t const parent_pid = getppid(); - TEST_PCHECK(ptrace(PTRACE_ATTACH, parent_pid, 0, 0) == 0); - MaybeSave(); - - // Block until the parent enters signal-delivery-stop as a result of the - // SIGSTOP sent by PTRACE_ATTACH. - int status; - TEST_PCHECK(waitpid(parent_pid, &status, 0) == parent_pid); - MaybeSave(); - TEST_CHECK(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP); - - // Replace the value of word in the parent process with kAfterPokeDataValue. - long const parent_word = ptrace(PTRACE_PEEKDATA, parent_pid, &word, 0); - MaybeSave(); - TEST_CHECK(parent_word == kBeforePokeDataValue); - TEST_PCHECK( - ptrace(PTRACE_POKEDATA, parent_pid, &word, kAfterPokeDataValue) == 0); - MaybeSave(); - - // Detach from the parent and suppress the SIGSTOP. If the SIGSTOP is not - // suppressed, the parent will hang in group-stop, causing the test to time - // out. - TEST_PCHECK(ptrace(PTRACE_DETACH, parent_pid, 0, 0) == 0); - MaybeSave(); - _exit(0); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to complete. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) - << " status " << status; - - // Check that the child's PTRACE_POKEDATA was effective. - EXPECT_EQ(kAfterPokeDataValue, word); -} - -TEST(PtraceTest, GetSigMask) { - // glibc and the Linux kernel define a sigset_t with different sizes. To avoid - // creating a kernel_sigset_t and recreating all the modification functions - // (sigemptyset, etc), we just hardcode the kernel sigset size. - constexpr int kSizeofKernelSigset = 8; - constexpr int kBlockSignal = SIGUSR1; - sigset_t blocked; - sigemptyset(&blocked); - sigaddset(&blocked, kBlockSignal); - - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - - // Install a signal handler for kBlockSignal to avoid termination and block - // it. - TEST_PCHECK(signal(kBlockSignal, +[](int signo) {}) != SIG_ERR); - MaybeSave(); - TEST_PCHECK(sigprocmask(SIG_SETMASK, &blocked, nullptr) == 0); - MaybeSave(); - - // Enable tracing. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - MaybeSave(); - - // This should be blocked. - RaiseSignal(kBlockSignal); - - // This should be suppressed by parent, who will change signal mask in the - // meantime, which means kBlockSignal should be delivered once this resumes. - RaiseSignal(SIGSTOP); - - _exit(0); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to send itself SIGSTOP and enter signal-delivery-stop. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Get current signal mask. - sigset_t set; - EXPECT_THAT(ptrace(kPtraceGetSigMask, child_pid, kSizeofKernelSigset, &set), - SyscallSucceeds()); - EXPECT_THAT(blocked, EqualsSigset(set)); - - // Try to get current signal mask with bad size argument. - EXPECT_THAT(ptrace(kPtraceGetSigMask, child_pid, 0, nullptr), - SyscallFailsWithErrno(EINVAL)); - - // Try to set bad signal mask. - sigset_t* bad_addr = reinterpret_cast<sigset_t*>(-1); - EXPECT_THAT( - ptrace(kPtraceSetSigMask, child_pid, kSizeofKernelSigset, bad_addr), - SyscallFailsWithErrno(EFAULT)); - - // Set signal mask to empty set. - sigset_t set1; - sigemptyset(&set1); - EXPECT_THAT(ptrace(kPtraceSetSigMask, child_pid, kSizeofKernelSigset, &set1), - SyscallSucceeds()); - - // Suppress SIGSTOP and resume the child. It should re-enter - // signal-delivery-stop for kBlockSignal. - ASSERT_THAT(ptrace(PTRACE_CONT, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == kBlockSignal) - << " status " << status; - - ASSERT_THAT(ptrace(PTRACE_CONT, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - // Let's see that process exited normally. - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) - << " status " << status; -} - -TEST(PtraceTest, GetSiginfo_SetSiginfo_SignalInjection) { - constexpr int kOriginalSigno = SIGUSR1; - constexpr int kInjectedSigno = SIGUSR2; - - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - - // Override all signal handlers. - struct sigaction sa = {}; - sa.sa_handler = +[](int signo) { _exit(signo); }; - TEST_PCHECK(sigfillset(&sa.sa_mask) == 0); - for (int signo = 1; signo < 32; signo++) { - if (signo == SIGKILL || signo == SIGSTOP) { - continue; - } - TEST_PCHECK(sigaction(signo, &sa, nullptr) == 0); - } - for (int signo = SIGRTMIN; signo <= SIGRTMAX; signo++) { - TEST_PCHECK(sigaction(signo, &sa, nullptr) == 0); - } - - // Unblock all signals. - TEST_PCHECK(sigprocmask(SIG_UNBLOCK, &sa.sa_mask, nullptr) == 0); - MaybeSave(); - - // Send ourselves kOriginalSignal while ptraced and exit with the signal we - // actually receive via the signal handler, if any, or 0 if we don't receive - // a signal. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - MaybeSave(); - RaiseSignal(kOriginalSigno); - _exit(0); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to send itself kOriginalSigno and enter - // signal-delivery-stop. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == kOriginalSigno) - << " status " << status; - - siginfo_t siginfo = {}; - ASSERT_THAT(ptrace(PTRACE_GETSIGINFO, child_pid, 0, &siginfo), - SyscallSucceeds()); - EXPECT_EQ(kOriginalSigno, siginfo.si_signo); - EXPECT_EQ(SI_TKILL, siginfo.si_code); - - // Replace the signal with kInjectedSigno, and check that the child exits - // with kInjectedSigno, indicating that signal injection was successful. - siginfo.si_signo = kInjectedSigno; - ASSERT_THAT(ptrace(PTRACE_SETSIGINFO, child_pid, 0, &siginfo), - SyscallSucceeds()); - ASSERT_THAT(ptrace(PTRACE_DETACH, child_pid, 0, kInjectedSigno), - SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == kInjectedSigno) - << " status " << status; -} - -TEST(PtraceTest, SIGKILLDoesNotCauseSignalDeliveryStop) { - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - MaybeSave(); - RaiseSignal(SIGKILL); - TEST_CHECK_MSG(false, "Survived SIGKILL?"); - _exit(1); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Expect the child to die to SIGKILL without entering signal-delivery-stop. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL) - << " status " << status; -} - -TEST(PtraceTest, PtraceKill) { - constexpr int kOriginalSigno = SIGUSR1; - - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - MaybeSave(); - - // PTRACE_KILL only works if tracee has entered signal-delivery-stop. - RaiseSignal(kOriginalSigno); - TEST_CHECK_MSG(false, "Failed to kill the process?"); - _exit(0); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to send itself kOriginalSigno and enter - // signal-delivery-stop. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == kOriginalSigno) - << " status " << status; - - ASSERT_THAT(ptrace(PTRACE_KILL, child_pid, 0, 0), SyscallSucceeds()); - - // Expect the child to die with SIGKILL. - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL) - << " status " << status; -} - -TEST(PtraceTest, GetRegSet) { - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - - // Enable tracing. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - MaybeSave(); - - // Use kill explicitly because we check the syscall argument register below. - kill(getpid(), SIGSTOP); - - _exit(0); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to send itself SIGSTOP and enter signal-delivery-stop. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Get the general registers. - struct user_regs_struct regs; - struct iovec iov; - iov.iov_base = ®s; - iov.iov_len = sizeof(regs); - EXPECT_THAT(ptrace(PTRACE_GETREGSET, child_pid, NT_PRSTATUS, &iov), - SyscallSucceeds()); - - // Read exactly the full register set. - EXPECT_EQ(iov.iov_len, sizeof(regs)); - -#ifdef __x86_64__ - // Child called kill(2), with SIGSTOP as arg 2. - EXPECT_EQ(regs.rsi, SIGSTOP); -#endif - - // Suppress SIGSTOP and resume the child. - ASSERT_THAT(ptrace(PTRACE_CONT, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - // Let's see that process exited normally. - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) - << " status " << status; -} - -TEST(PtraceTest, AttachingConvertsGroupStopToPtraceStop) { - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - while (true) { - pause(); - } - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // SIGSTOP the child and wait for it to stop. - ASSERT_THAT(kill(child_pid, SIGSTOP), SyscallSucceeds()); - int status; - ASSERT_THAT(waitpid(child_pid, &status, WUNTRACED), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Attach to the child and expect it to re-enter a traced group-stop despite - // already being stopped. - ASSERT_THAT(ptrace(PTRACE_ATTACH, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Verify that the child is ptrace-stopped by checking that it can receive - // ptrace commands requiring a ptrace-stop. - EXPECT_THAT(ptrace(PTRACE_SETOPTIONS, child_pid, 0, 0), SyscallSucceeds()); - - // Group-stop is distinguished from signal-delivery-stop by PTRACE_GETSIGINFO - // failing with EINVAL. - siginfo_t siginfo = {}; - EXPECT_THAT(ptrace(PTRACE_GETSIGINFO, child_pid, 0, &siginfo), - SyscallFailsWithErrno(EINVAL)); - - // Detach from the child and expect it to stay stopped without a notification. - ASSERT_THAT(ptrace(PTRACE_DETACH, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, WUNTRACED | WNOHANG), - SyscallSucceedsWithValue(0)); - - // Sending it SIGCONT should cause it to leave its stop. - ASSERT_THAT(kill(child_pid, SIGCONT), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, WCONTINUED), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFCONTINUED(status)) << " status " << status; - - // Clean up the child. - ASSERT_THAT(kill(child_pid, SIGKILL), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL) - << " status " << status; -} - -// Fixture for tests parameterized by whether or not to use PTRACE_O_TRACEEXEC. -class PtraceExecveTest : public ::testing::TestWithParam<bool> { - protected: - bool TraceExec() const { return GetParam(); } -}; - -TEST_P(PtraceExecveTest, Execve_GetRegs_PeekUser_SIGKILL_TraceClone_TraceExit) { - ExecveArray const owned_child_argv = {"/proc/self/exe", - "--ptrace_test_execve_child"}; - char* const* const child_argv = owned_child_argv.get(); - - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. The test relies on calling execve() in a non-leader - // thread; pthread_create() isn't async-signal-safe, so the safest way to - // do this is to execve() first, then enable tracing and run the expected - // child process behavior in the new subprocess. - execve(child_argv[0], child_argv, /* envp = */ nullptr); - TEST_PCHECK_MSG(false, "Survived execve to test child"); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to send itself SIGSTOP and enter signal-delivery-stop. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Enable PTRACE_O_TRACECLONE so we can get the ID of the child's non-leader - // thread, PTRACE_O_TRACEEXIT so we can observe the leader's death, and - // PTRACE_O_TRACEEXEC if required by the test. (The leader doesn't call - // execve, but options should be inherited across clone.) - long opts = PTRACE_O_TRACECLONE | PTRACE_O_TRACEEXIT; - if (TraceExec()) { - opts |= PTRACE_O_TRACEEXEC; - } - ASSERT_THAT(ptrace(PTRACE_SETOPTIONS, child_pid, 0, opts), SyscallSucceeds()); - - // Suppress the SIGSTOP and wait for the child's leader thread to report - // PTRACE_EVENT_CLONE. Get the new thread's ID from the event. - ASSERT_THAT(ptrace(PTRACE_CONT, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_EQ(SIGTRAP | (PTRACE_EVENT_CLONE << 8), status >> 8); - unsigned long eventmsg; - ASSERT_THAT(ptrace(PTRACE_GETEVENTMSG, child_pid, 0, &eventmsg), - SyscallSucceeds()); - pid_t const nonleader_tid = eventmsg; - pid_t const leader_tid = child_pid; - - // The new thread should be ptraced and in signal-delivery-stop by SIGSTOP due - // to PTRACE_O_TRACECLONE. - // - // Before bf959931ddb88c4e4366e96dd22e68fa0db9527c "wait/ptrace: assume __WALL - // if the child is traced" (4.7) , waiting on it requires __WCLONE since, as a - // non-leader, its termination signal is 0. After, a standard wait is - // sufficient. - ASSERT_THAT(waitpid(nonleader_tid, &status, __WCLONE), - SyscallSucceedsWithValue(nonleader_tid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Resume both child threads. - for (pid_t const tid : {leader_tid, nonleader_tid}) { - ASSERT_THAT(ptrace(PTRACE_CONT, tid, 0, 0), SyscallSucceeds()); - } - - // The non-leader child thread should call execve, causing the leader thread - // to enter PTRACE_EVENT_EXIT with an apparent exit code of 0. At this point, - // the leader has not yet exited, so the non-leader should be blocked in - // execve. - ASSERT_THAT(waitpid(leader_tid, &status, 0), - SyscallSucceedsWithValue(leader_tid)); - EXPECT_EQ(SIGTRAP | (PTRACE_EVENT_EXIT << 8), status >> 8); - ASSERT_THAT(ptrace(PTRACE_GETEVENTMSG, leader_tid, 0, &eventmsg), - SyscallSucceeds()); - EXPECT_TRUE(WIFEXITED(eventmsg) && WEXITSTATUS(eventmsg) == 0) - << " eventmsg " << eventmsg; - EXPECT_THAT(waitpid(nonleader_tid, &status, __WCLONE | WNOHANG), - SyscallSucceedsWithValue(0)); - - // Allow the leader to continue exiting. This should allow the non-leader to - // complete its execve, causing the original leader to be reaped without - // further notice and the non-leader to steal its ID. - ASSERT_THAT(ptrace(PTRACE_CONT, leader_tid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(leader_tid, &status, 0), - SyscallSucceedsWithValue(leader_tid)); - if (TraceExec()) { - // If PTRACE_O_TRACEEXEC was enabled, the execing thread should be in - // PTRACE_EVENT_EXEC-stop, with the event message set to its old thread ID. - EXPECT_EQ(SIGTRAP | (PTRACE_EVENT_EXEC << 8), status >> 8); - ASSERT_THAT(ptrace(PTRACE_GETEVENTMSG, leader_tid, 0, &eventmsg), - SyscallSucceeds()); - EXPECT_EQ(nonleader_tid, eventmsg); - } else { - // Otherwise, the execing thread should have received SIGTRAP and should now - // be in signal-delivery-stop. - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) - << " status " << status; - } - -#ifdef __x86_64__ - { - // CS should be 0x33, indicating an 64-bit binary. - constexpr uint64_t kAMD64UserCS = 0x33; - EXPECT_THAT(ptrace(PTRACE_PEEKUSER, leader_tid, - offsetof(struct user_regs_struct, cs), 0), - SyscallSucceedsWithValue(kAMD64UserCS)); - struct user_regs_struct regs = {}; - ASSERT_THAT(ptrace(PTRACE_GETREGS, leader_tid, 0, ®s), - SyscallSucceeds()); - EXPECT_EQ(kAMD64UserCS, regs.cs); - } -#endif // defined(__x86_64__) - - // PTRACE_O_TRACEEXIT should have been inherited across execve. Send SIGKILL, - // which should end the PTRACE_EVENT_EXEC-stop or signal-delivery-stop and - // leave the child in PTRACE_EVENT_EXIT-stop. - ASSERT_THAT(kill(leader_tid, SIGKILL), SyscallSucceeds()); - ASSERT_THAT(waitpid(leader_tid, &status, 0), - SyscallSucceedsWithValue(leader_tid)); - EXPECT_EQ(SIGTRAP | (PTRACE_EVENT_EXIT << 8), status >> 8); - ASSERT_THAT(ptrace(PTRACE_GETEVENTMSG, leader_tid, 0, &eventmsg), - SyscallSucceeds()); - EXPECT_TRUE(WIFSIGNALED(eventmsg) && WTERMSIG(eventmsg) == SIGKILL) - << " eventmsg " << eventmsg; - - // End the PTRACE_EVENT_EXIT stop, allowing the child to exit. - ASSERT_THAT(ptrace(PTRACE_CONT, leader_tid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(leader_tid, &status, 0), - SyscallSucceedsWithValue(leader_tid)); - EXPECT_TRUE(WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL) - << " status " << status; -} - -[[noreturn]] void RunExecveChild() { - // Enable tracing, then raise SIGSTOP and expect our parent to suppress it. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - MaybeSave(); - RaiseSignal(SIGSTOP); - MaybeSave(); - - // Call execve() in a non-leader thread. As long as execve() succeeds, what - // exactly we execve() shouldn't really matter, since the tracer should kill - // us after execve() completes. - ScopedThread t([&] { - ExecveArray const owned_child_argv = {"/proc/self/exe", - "--this_flag_shouldnt_exist"}; - char* const* const child_argv = owned_child_argv.get(); - execve(child_argv[0], child_argv, /* envp = */ nullptr); - TEST_PCHECK_MSG(false, "Survived execve? (thread)"); - }); - t.Join(); - TEST_CHECK_MSG(false, "Survived execve? (main)"); - _exit(1); -} - -INSTANTIATE_TEST_SUITE_P(TraceExec, PtraceExecveTest, ::testing::Bool()); - -// This test has expectations on when syscall-enter/exit-stops occur that are -// violated if saving occurs, since saving interrupts all syscalls, causing -// premature syscall-exit. -TEST(PtraceTest, - ExitWhenParentIsNotTracer_Syscall_TraceVfork_TraceVforkDone_NoRandomSave) { - constexpr int kExitTraceeExitCode = 99; - - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - - // Block SIGCHLD so it doesn't interrupt wait4. - sigset_t mask; - TEST_PCHECK(sigemptyset(&mask) == 0); - TEST_PCHECK(sigaddset(&mask, SIGCHLD) == 0); - TEST_PCHECK(sigprocmask(SIG_SETMASK, &mask, nullptr) == 0); - MaybeSave(); - - // Enable tracing, then raise SIGSTOP and expect our parent to suppress it. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - MaybeSave(); - RaiseSignal(SIGSTOP); - MaybeSave(); - - // Spawn a vfork child that exits immediately, and reap it. Don't save - // after vfork since the parent expects to see wait4 as the next syscall. - pid_t const pid = vfork(); - if (pid == 0) { - _exit(kExitTraceeExitCode); - } - TEST_PCHECK_MSG(pid > 0, "vfork failed"); - - int status; - TEST_PCHECK(wait4(pid, &status, 0, nullptr) > 0); - MaybeSave(); - TEST_CHECK(WIFEXITED(status) && WEXITSTATUS(status) == kExitTraceeExitCode); - _exit(0); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to send itself SIGSTOP and enter signal-delivery-stop. - int status; - ASSERT_THAT(child_pid, SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Enable PTRACE_O_TRACEVFORK so we can get the ID of the grandchild, - // PTRACE_O_TRACEVFORKDONE so we can observe PTRACE_EVENT_VFORK_DONE, and - // PTRACE_O_TRACESYSGOOD so syscall-enter/exit-stops are unambiguously - // indicated by a stop signal of SIGTRAP|0x80 rather than just SIGTRAP. - ASSERT_THAT(ptrace(PTRACE_SETOPTIONS, child_pid, 0, - PTRACE_O_TRACEVFORK | PTRACE_O_TRACEVFORKDONE | - PTRACE_O_TRACESYSGOOD), - SyscallSucceeds()); - - // Suppress the SIGSTOP and wait for the child to report PTRACE_EVENT_VFORK. - // Get the new process' ID from the event. - ASSERT_THAT(ptrace(PTRACE_CONT, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_EQ(SIGTRAP | (PTRACE_EVENT_VFORK << 8), status >> 8); - unsigned long eventmsg; - ASSERT_THAT(ptrace(PTRACE_GETEVENTMSG, child_pid, 0, &eventmsg), - SyscallSucceeds()); - pid_t const grandchild_pid = eventmsg; - - // The grandchild should be traced by us and in signal-delivery-stop by - // SIGSTOP due to PTRACE_O_TRACEVFORK. This allows us to wait on it even - // though we're not its parent. - ASSERT_THAT(waitpid(grandchild_pid, &status, 0), - SyscallSucceedsWithValue(grandchild_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Resume the child with PTRACE_SYSCALL. Since the grandchild is still in - // signal-delivery-stop, the child should remain in vfork() waiting for the - // grandchild to exec or exit. - ASSERT_THAT(ptrace(PTRACE_SYSCALL, child_pid, 0, 0), SyscallSucceeds()); - absl::SleepFor(absl::Seconds(1)); - ASSERT_THAT(waitpid(child_pid, &status, WNOHANG), - SyscallSucceedsWithValue(0)); - - // Suppress the grandchild's SIGSTOP and wait for the grandchild to exit. Pass - // WNOWAIT to waitid() so that we don't acknowledge the grandchild's exit yet. - ASSERT_THAT(ptrace(PTRACE_CONT, grandchild_pid, 0, 0), SyscallSucceeds()); - siginfo_t siginfo = {}; - ASSERT_THAT(waitid(P_PID, grandchild_pid, &siginfo, WEXITED | WNOWAIT), - SyscallSucceeds()); - EXPECT_EQ(SIGCHLD, siginfo.si_signo); - EXPECT_EQ(CLD_EXITED, siginfo.si_code); - EXPECT_EQ(kExitTraceeExitCode, siginfo.si_status); - EXPECT_EQ(grandchild_pid, siginfo.si_pid); - EXPECT_EQ(getuid(), siginfo.si_uid); - - // The child should now be in PTRACE_EVENT_VFORK_DONE stop. The event - // message should still be the grandchild's PID. - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_EQ(SIGTRAP | (PTRACE_EVENT_VFORK_DONE << 8), status >> 8); - ASSERT_THAT(ptrace(PTRACE_GETEVENTMSG, child_pid, 0, &eventmsg), - SyscallSucceeds()); - EXPECT_EQ(grandchild_pid, eventmsg); - - // Resume the child with PTRACE_SYSCALL again and expect it to enter - // syscall-exit-stop for vfork() or clone(), either of which should return the - // grandchild's PID from the syscall. Aside from PTRACE_O_TRACESYSGOOD, - // syscall-stops are distinguished from signal-delivery-stop by - // PTRACE_GETSIGINFO returning a siginfo for which si_code == SIGTRAP or - // SIGTRAP|0x80. - ASSERT_THAT(ptrace(PTRACE_SYSCALL, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == (SIGTRAP | 0x80)) - << " status " << status; - ASSERT_THAT(ptrace(PTRACE_GETSIGINFO, child_pid, 0, &siginfo), - SyscallSucceeds()); - EXPECT_TRUE(siginfo.si_code == SIGTRAP || siginfo.si_code == (SIGTRAP | 0x80)) - << "si_code = " << siginfo.si_code; -#ifdef __x86_64__ - { - struct user_regs_struct regs = {}; - ASSERT_THAT(ptrace(PTRACE_GETREGS, child_pid, 0, ®s), SyscallSucceeds()); - EXPECT_TRUE(regs.orig_rax == SYS_vfork || regs.orig_rax == SYS_clone) - << "orig_rax = " << regs.orig_rax; - EXPECT_EQ(grandchild_pid, regs.rax); - } -#endif // defined(__x86_64__) - - // After this point, the child will be making wait4 syscalls that will be - // interrupted by saving, so saving is not permitted. Note that this is - // explicitly released below once the grandchild exits. - DisableSave ds; - - // Resume the child with PTRACE_SYSCALL again and expect it to enter - // syscall-enter-stop for wait4(). - ASSERT_THAT(ptrace(PTRACE_SYSCALL, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == (SIGTRAP | 0x80)) - << " status " << status; - ASSERT_THAT(ptrace(PTRACE_GETSIGINFO, child_pid, 0, &siginfo), - SyscallSucceeds()); - EXPECT_TRUE(siginfo.si_code == SIGTRAP || siginfo.si_code == (SIGTRAP | 0x80)) - << "si_code = " << siginfo.si_code; -#ifdef __x86_64__ - { - EXPECT_THAT(ptrace(PTRACE_PEEKUSER, child_pid, - offsetof(struct user_regs_struct, orig_rax), 0), - SyscallSucceedsWithValue(SYS_wait4)); - } -#endif // defined(__x86_64__) - - // Resume the child with PTRACE_SYSCALL again. Since the grandchild is - // waiting for the tracer (us) to acknowledge its exit first, wait4 should - // block. - ASSERT_THAT(ptrace(PTRACE_SYSCALL, child_pid, 0, 0), SyscallSucceeds()); - absl::SleepFor(absl::Seconds(1)); - ASSERT_THAT(waitpid(child_pid, &status, WNOHANG), - SyscallSucceedsWithValue(0)); - - // Acknowledge the grandchild's exit. - ASSERT_THAT(waitpid(grandchild_pid, &status, 0), - SyscallSucceedsWithValue(grandchild_pid)); - ds.reset(); - - // Now the child should enter syscall-exit-stop for wait4, returning with the - // grandchild's PID. - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == (SIGTRAP | 0x80)) - << " status " << status; -#ifdef __x86_64__ - { - struct user_regs_struct regs = {}; - ASSERT_THAT(ptrace(PTRACE_GETREGS, child_pid, 0, ®s), SyscallSucceeds()); - EXPECT_EQ(SYS_wait4, regs.orig_rax); - EXPECT_EQ(grandchild_pid, regs.rax); - } -#endif // defined(__x86_64__) - - // Detach from the child and wait for it to exit. - ASSERT_THAT(ptrace(PTRACE_DETACH, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) - << " status " << status; -} - -// These tests requires knowledge of architecture-specific syscall convention. -#ifdef __x86_64__ -TEST(PtraceTest, Int3) { - switch (GvisorPlatform()) { - case Platform::kKVM: - // TODO(b/124248694): int3 isn't handled properly. - return; - default: - break; - } - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - - // Enable tracing. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - - // Interrupt 3 - trap to debugger - asm("int3"); - - _exit(56); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) - << " status " << status; - - ASSERT_THAT(ptrace(PTRACE_CONT, child_pid, 0, 0), SyscallSucceeds()); - - // The child should validate the injected return value and then exit normally. - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 56) - << " status " << status; -} - -TEST(PtraceTest, Sysemu_PokeUser) { - constexpr int kSysemuHelperFirstExitCode = 126; - constexpr uint64_t kSysemuInjectedExitGroupReturn = 42; - - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - - // Enable tracing, then raise SIGSTOP and expect our parent to suppress it. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - RaiseSignal(SIGSTOP); - - // Try to exit_group, expecting the tracer to skip the syscall and set its - // own return value. - int const rv = syscall(SYS_exit_group, kSysemuHelperFirstExitCode); - TEST_PCHECK_MSG(rv == kSysemuInjectedExitGroupReturn, - "exit_group returned incorrect value"); - - _exit(0); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to send itself SIGSTOP and enter signal-delivery-stop. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Suppress the SIGSTOP and wait for the child to enter syscall-enter-stop - // for its first exit_group syscall. - ASSERT_THAT(ptrace(kPtraceSysemu, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) - << " status " << status; - - struct user_regs_struct regs = {}; - ASSERT_THAT(ptrace(PTRACE_GETREGS, child_pid, 0, ®s), SyscallSucceeds()); - EXPECT_EQ(SYS_exit_group, regs.orig_rax); - EXPECT_EQ(-ENOSYS, regs.rax); - EXPECT_EQ(kSysemuHelperFirstExitCode, regs.rdi); - - // Replace the exit_group return value, then resume the child, which should - // automatically skip the syscall. - ASSERT_THAT( - ptrace(PTRACE_POKEUSER, child_pid, offsetof(struct user_regs_struct, rax), - kSysemuInjectedExitGroupReturn), - SyscallSucceeds()); - ASSERT_THAT(ptrace(PTRACE_DETACH, child_pid, 0, 0), SyscallSucceeds()); - - // The child should validate the injected return value and then exit normally. - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) - << " status " << status; -} - -// This test also cares about syscall-exit-stop. -TEST(PtraceTest, ERESTART_NoRandomSave) { - constexpr int kSigno = SIGUSR1; - - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - - // Ignore, but unblock, kSigno. - struct sigaction sa = {}; - sa.sa_handler = SIG_IGN; - TEST_PCHECK(sigfillset(&sa.sa_mask) == 0); - TEST_PCHECK(sigaction(kSigno, &sa, nullptr) == 0); - MaybeSave(); - TEST_PCHECK(sigprocmask(SIG_UNBLOCK, &sa.sa_mask, nullptr) == 0); - MaybeSave(); - - // Enable tracing, then raise SIGSTOP and expect our parent to suppress it. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - RaiseSignal(SIGSTOP); - - // Invoke the pause syscall, which normally should not return until we - // receive a signal that "either terminates the process or causes the - // invocation of a signal-catching function". - pause(); - - _exit(0); - } - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to send itself SIGSTOP and enter signal-delivery-stop. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // After this point, the child's pause syscall will be interrupted by saving, - // so saving is not permitted. Note that this is explicitly released below - // once the child is stopped. - DisableSave ds; - - // Suppress the SIGSTOP and wait for the child to enter syscall-enter-stop for - // its pause syscall. - ASSERT_THAT(ptrace(PTRACE_SYSCALL, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) - << " status " << status; - - struct user_regs_struct regs = {}; - ASSERT_THAT(ptrace(PTRACE_GETREGS, child_pid, 0, ®s), SyscallSucceeds()); - EXPECT_EQ(SYS_pause, regs.orig_rax); - EXPECT_EQ(-ENOSYS, regs.rax); - - // Resume the child with PTRACE_SYSCALL and expect it to block in the pause - // syscall. - ASSERT_THAT(ptrace(PTRACE_SYSCALL, child_pid, 0, 0), SyscallSucceeds()); - absl::SleepFor(absl::Seconds(1)); - ASSERT_THAT(waitpid(child_pid, &status, WNOHANG), - SyscallSucceedsWithValue(0)); - - // Send the child kSigno, causing it to return ERESTARTNOHAND and enter - // syscall-exit-stop from the pause syscall. - constexpr int ERESTARTNOHAND = 514; - ASSERT_THAT(kill(child_pid, kSigno), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) - << " status " << status; - ds.reset(); - - ASSERT_THAT(ptrace(PTRACE_GETREGS, child_pid, 0, ®s), SyscallSucceeds()); - EXPECT_EQ(SYS_pause, regs.orig_rax); - EXPECT_EQ(-ERESTARTNOHAND, regs.rax); - - // Replace the return value from pause with 0, causing pause to not be - // restarted despite kSigno being ignored. - ASSERT_THAT(ptrace(PTRACE_POKEUSER, child_pid, - offsetof(struct user_regs_struct, rax), 0), - SyscallSucceeds()); - - // Detach from the child and wait for it to exit. - ASSERT_THAT(ptrace(PTRACE_DETACH, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) - << " status " << status; -} -#endif // defined(__x86_64__) - -TEST(PtraceTest, Seize_Interrupt_Listen) { - volatile long child_should_spin = 1; - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - while (child_should_spin) { - SleepSafe(absl::Seconds(1)); - } - _exit(1); - } - - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Attach to the child with PTRACE_SEIZE; doing so should not stop the child. - ASSERT_THAT(ptrace(PTRACE_SEIZE, child_pid, 0, 0), SyscallSucceeds()); - int status; - EXPECT_THAT(waitpid(child_pid, &status, WNOHANG), - SyscallSucceedsWithValue(0)); - - // Stop the child with PTRACE_INTERRUPT. - ASSERT_THAT(ptrace(PTRACE_INTERRUPT, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_EQ(SIGTRAP | (kPtraceEventStop << 8), status >> 8); - - // Unset child_should_spin to verify that the child never leaves the spin - // loop. - ASSERT_THAT(ptrace(PTRACE_POKEDATA, child_pid, &child_should_spin, 0), - SyscallSucceeds()); - - // Send SIGSTOP to the child, then resume it, allowing it to proceed to - // signal-delivery-stop. - ASSERT_THAT(kill(child_pid, SIGSTOP), SyscallSucceeds()); - ASSERT_THAT(ptrace(PTRACE_CONT, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // Release the child from signal-delivery-stop without suppressing the - // SIGSTOP, causing it to enter group-stop. - ASSERT_THAT(ptrace(PTRACE_CONT, child_pid, 0, SIGSTOP), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_EQ(SIGSTOP | (kPtraceEventStop << 8), status >> 8); - - // "The state of the tracee after PTRACE_LISTEN is somewhat of a gray area: it - // is not in any ptrace-stop (ptrace commands won't work on it, and it will - // deliver waitpid(2) notifications), but it also may be considered 'stopped' - // because it is not executing instructions (is not scheduled), and if it was - // in group-stop before PTRACE_LISTEN, it will not respond to signals until - // SIGCONT is received." - ptrace(2). - ASSERT_THAT(ptrace(PTRACE_LISTEN, child_pid, 0, 0), SyscallSucceeds()); - EXPECT_THAT(ptrace(PTRACE_CONT, child_pid, 0, 0), - SyscallFailsWithErrno(ESRCH)); - EXPECT_THAT(waitpid(child_pid, &status, WNOHANG), - SyscallSucceedsWithValue(0)); - EXPECT_THAT(kill(child_pid, SIGTERM), SyscallSucceeds()); - absl::SleepFor(absl::Seconds(1)); - EXPECT_THAT(waitpid(child_pid, &status, WNOHANG), - SyscallSucceedsWithValue(0)); - - // Send SIGCONT to the child, causing it to leave group-stop and re-trap due - // to PTRACE_LISTEN. - EXPECT_THAT(kill(child_pid, SIGCONT), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_EQ(SIGTRAP | (kPtraceEventStop << 8), status >> 8); - - // Detach the child and expect it to exit due to the SIGTERM we sent while - // it was stopped by PTRACE_LISTEN. - ASSERT_THAT(ptrace(PTRACE_DETACH, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSIGNALED(status) && WTERMSIG(status) == SIGTERM) - << " status " << status; -} - -TEST(PtraceTest, Interrupt_Listen_RequireSeize) { - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, 0, 0) == 0); - MaybeSave(); - raise(SIGSTOP); - _exit(0); - } - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Wait for the child to send itself SIGSTOP and enter signal-delivery-stop. - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP) - << " status " << status; - - // PTRACE_INTERRUPT and PTRACE_LISTEN should fail since the child wasn't - // attached with PTRACE_SEIZE, leaving the child in signal-delivery-stop. - EXPECT_THAT(ptrace(PTRACE_INTERRUPT, child_pid, 0, 0), - SyscallFailsWithErrno(EIO)); - EXPECT_THAT(ptrace(PTRACE_LISTEN, child_pid, 0, 0), - SyscallFailsWithErrno(EIO)); - - // Suppress SIGSTOP and detach from the child, expecting it to exit normally. - ASSERT_THAT(ptrace(PTRACE_DETACH, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) - << " status " << status; -} - -TEST(PtraceTest, SeizeSetOptions) { - pid_t const child_pid = fork(); - if (child_pid == 0) { - // In child process. - while (true) { - SleepSafe(absl::Seconds(1)); - } - } - - // In parent process. - ASSERT_THAT(child_pid, SyscallSucceeds()); - - // Attach to the child with PTRACE_SEIZE while setting PTRACE_O_TRACESYSGOOD. - ASSERT_THAT(ptrace(PTRACE_SEIZE, child_pid, 0, PTRACE_O_TRACESYSGOOD), - SyscallSucceeds()); - - // Stop the child with PTRACE_INTERRUPT. - ASSERT_THAT(ptrace(PTRACE_INTERRUPT, child_pid, 0, 0), SyscallSucceeds()); - int status; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_EQ(SIGTRAP | (kPtraceEventStop << 8), status >> 8); - - // Resume the child with PTRACE_SYSCALL and wait for it to enter - // syscall-enter-stop. The stop signal status from the syscall stop should be - // SIGTRAP|0x80, reflecting PTRACE_O_TRACESYSGOOD. - ASSERT_THAT(ptrace(PTRACE_SYSCALL, child_pid, 0, 0), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == (SIGTRAP | 0x80)) - << " status " << status; - - // Clean up the child. - ASSERT_THAT(kill(child_pid, SIGKILL), SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - if (WIFSTOPPED(status) && WSTOPSIG(status) == (SIGTRAP | 0x80)) { - // "SIGKILL kills even within system calls (syscall-exit-stop is not - // generated prior to death by SIGKILL). The net effect is that SIGKILL - // always kills the process (all its threads), even if some threads of the - // process are ptraced." - ptrace(2). This is technically true, but... - // - // When we send SIGKILL to the child, kernel/signal.c:complete_signal() => - // signal_wake_up(resume=1) kicks the tracee out of the syscall-enter-stop. - // The pending SIGKILL causes the syscall to be skipped, but the child - // thread still reports syscall-exit before checking for pending signals; in - // current kernels, this is - // arch/x86/entry/common.c:syscall_return_slowpath() => - // syscall_slow_exit_work() => - // include/linux/tracehook.h:tracehook_report_syscall_exit() => - // ptrace_report_syscall() => kernel/signal.c:ptrace_notify() => - // ptrace_do_notify() => ptrace_stop(). - // - // ptrace_stop() sets the task's state to TASK_TRACED and the task's - // exit_code to SIGTRAP|0x80 (passed by ptrace_report_syscall()), then calls - // freezable_schedule(). freezable_schedule() eventually reaches - // __schedule(), which detects signal_pending_state() due to the pending - // SIGKILL, sets the task's state back to TASK_RUNNING, and returns without - // descheduling. Thus, the task never enters syscall-exit-stop. However, if - // our wait4() => kernel/exit.c:wait_task_stopped() racily observes the - // TASK_TRACED state and the non-zero exit code set by ptrace_stop() before - // __schedule() sets the state back to TASK_RUNNING, it will return the - // task's exit_code as status W_STOPCODE(SIGTRAP|0x80). So we get a spurious - // syscall-exit-stop notification, and need to wait4() again for task exit. - // - // gVisor is not susceptible to this race because - // kernel.Task.waitCollectTraceeStopLocked() checks specifically for an - // active ptraceStop, which is not initiated if SIGKILL is pending. - std::cout << "Observed syscall-exit after SIGKILL"; - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - } - EXPECT_TRUE(WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL) - << " status " << status; -} - -} // namespace - -} // namespace testing -} // namespace gvisor - -int main(int argc, char** argv) { - gvisor::testing::TestInit(&argc, &argv); - - if (absl::GetFlag(FLAGS_ptrace_test_execve_child)) { - gvisor::testing::RunExecveChild(); - } - - return RUN_ALL_TESTS(); -} |