executor: add runner mode

Move all syz-fuzzer logic into syz-executor and remove syz-fuzzer.
Also restore syz-runtest functionality in the manager.

Update #4917 (sets most signal handlers to SIG_IGN)

1 files changed, 129 insertions, 0 deletions

diff --git a/executor/subprocess.h b/executor/subprocess.h
new file mode 100644
index 000000000..ef4bd9656
--- /dev/null
+++ b/executor/subprocess.h
@@ -0,0 +1,129 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+#include <spawn.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <vector>
+
+// Subprocess allows to start and wait for a subprocess.
+class Subprocess
+{
+public:
+	Subprocess(const char** argv, const std::vector<std::pair<int, int>>& fds)
+	{
+		posix_spawn_file_actions_t actions;
+		if (posix_spawn_file_actions_init(&actions))
+			fail("posix_spawn_file_actions_init failed");
+		int max_fd = 0;
+		for (auto pair : fds) {
+			max_fd = std::max(max_fd, pair.second);
+			if (pair.first != -1) {
+				if (posix_spawn_file_actions_adddup2(&actions, pair.first, pair.second))
+					fail("posix_spawn_file_actions_adddup2 failed");
+			} else {
+				if (posix_spawn_file_actions_addclose(&actions, pair.second))
+					fail("posix_spawn_file_actions_addclose failed");
+			}
+		}
+		for (int i = max_fd + 1; i < kFdLimit; i++) {
+			if (posix_spawn_file_actions_addclose(&actions, i))
+				fail("posix_spawn_file_actions_addclose failed");
+		}
+
+		posix_spawnattr_t attr;
+		if (posix_spawnattr_init(&attr))
+			fail("posix_spawnattr_init failed");
+		// Create new process group so that we can kill all processes in the group.
+		if (posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETPGROUP))
+			fail("posix_spawnattr_setflags failed");
+
+		const char* child_envp[] = {
+		    // Tell ASAN to not mess with our NONFAILING.
+		    "ASAN_OPTIONS=handle_segv=0 allow_user_segv_handler=1",
+		    // Disable rseq since we don't use it and we want to [ab]use it ourselves for kernel testing.
+		    "GLIBC_TUNABLES=glibc.pthread.rseq=0",
+		    nullptr};
+
+		if (posix_spawn(&pid_, argv[0], &actions, &attr,
+				const_cast<char**>(argv), const_cast<char**>(child_envp)))
+			fail("posix_spawn failed");
+
+		if (posix_spawn_file_actions_destroy(&actions))
+			fail("posix_spawn_file_actions_destroy failed");
+		if (posix_spawnattr_destroy(&attr))
+			fail("posix_spawnattr_destroy failed");
+	}
+
+	~Subprocess()
+	{
+		if (pid_)
+			KillAndWait();
+	}
+
+	int KillAndWait()
+	{
+		if (!pid_)
+			fail("subprocess hasn't started or already waited");
+		kill(-pid_, SIGKILL);
+		kill(pid_, SIGKILL);
+		int pid = 0;
+		int wstatus = 0;
+		do
+			pid = waitpid(pid_, &wstatus, WAIT_FLAGS);
+		while (pid == -1 && errno == EINTR);
+		if (pid != pid_)
+			failmsg("child wait failed", "pid_=%d pid=%d", pid_, pid);
+		if (WIFSTOPPED(wstatus))
+			failmsg("child stopped", "status=%d", wstatus);
+		pid_ = 0;
+		return ExitStatus(wstatus);
+	}
+
+	int WaitAndKill(uint64 timeout_ms)
+	{
+		if (!pid_)
+			fail("subprocess hasn't started or already waited");
+		uint64 start = current_time_ms();
+		int wstatus = 0;
+		for (;;) {
+			sleep_ms(10);
+			if (waitpid(pid_, &wstatus, WNOHANG | WAIT_FLAGS) == pid_)
+				break;
+			if (current_time_ms() - start > timeout_ms) {
+				kill(-pid_, SIGKILL);
+				kill(pid_, SIGKILL);
+			}
+		}
+		pid_ = 0;
+		return ExitStatus(wstatus);
+	}
+
+private:
+	int pid_ = 0;
+
+	static int ExitStatus(int wstatus)
+	{
+		if (WIFEXITED(wstatus))
+			return WEXITSTATUS(wstatus);
+		if (WIFSIGNALED(wstatus)) {
+			// Map signal numbers to some reasonable exit statuses.
+			// We only log them and compare to kFailStatus, so ensure it's not kFailStatus
+			// and not 0, otherwise return the signal as is (e.g. exit status 11 is SIGSEGV).
+			switch (WTERMSIG(wstatus)) {
+			case kFailStatus:
+				return kFailStatus - 1;
+			case 0:
+				return kFailStatus - 2;
+			default:
+				return WTERMSIG(wstatus);
+			}
+		}
+		// This may be possible in WIFSTOPPED case for C programs.
+		return kFailStatus - 3;
+	}
+
+	Subprocess(const Subprocess&) = delete;
+	Subprocess& operator=(const Subprocess&) = delete;
+};