rv: Add rv tool

This is the (user-space) runtime verification tool, named rv.

This tool aims to be the interface for in-kernel rv monitors, as
well as the home for monitors in user-space (online asynchronous),
and in *eBPF.

The tool receives a command as the first argument, the current
commands are:

  list	- list all available monitors
  mon	- run a given monitor

Each monitor is an independent piece of software inside the
tool and can have their own arguments.

There is no monitor implemented in this patch, it only
adds the basic structure of the tool, based on rtla.

  # rv --help
    rv version 6.1.0-rc4: help

    usage: rv command [-h] [command_options]

	-h/--help: print this menu

	command: run one of the following command:
	  list: list all available monitors
	  mon:  run a monitor

	[command options]: each command has its own set of options
		           run rv command -h for further information

*dot2bpf is the next patch set, depends on this, doing cleanups.

Link: https://lkml.kernel.org/r/fb51184f3b95aea0d7bfdc33ec09f4153aee84fa.1668180100.git.bristot@kernel.org

Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 185 insertions, 0 deletions

diff --git a/tools/verification/rv/src/rv.c b/tools/verification/rv/src/rv.c
new file mode 100644
index 000000000000..a9ea1c891ce0
--- /dev/null
+++ b/tools/verification/rv/src/rv.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rv tool, the interface for the Linux kernel RV subsystem and home of
+ * user-space controlled monitors.
+ *
+ * Copyright (C) 2022 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
+ */
+
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include <trace.h>
+#include <utils.h>
+
+static int stop_session;
+
+/*
+ * stop_rv - tell monitors to stop
+ */
+static void stop_rv(int sig)
+{
+	stop_session = 1;
+}
+
+/**
+ * should_stop - check if the monitor should stop.
+ *
+ * Returns 1 if the monitor should stop, 0 otherwise.
+ */
+int should_stop(void)
+{
+	return stop_session;
+}
+
+/*
+ * rv_list - list all available monitors
+ */
+static void rv_list(int argc, char **argv)
+{
+	static const char *const usage[] = {
+		"",
+		"  usage: rv list [-h]",
+		"",
+		"	list all available monitors",
+		"",
+		"	-h/--help: print this menu",
+		NULL,
+	};
+	int i;
+
+	if (argc > 1) {
+		fprintf(stderr, "rv version %s\n", VERSION);
+
+		/* more than 1 is always usage */
+		for (i = 0; usage[i]; i++)
+			fprintf(stderr, "%s\n", usage[i]);
+
+		/* but only -h is valid */
+		if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help"))
+			exit(0);
+		else
+			exit(1);
+	}
+
+	exit(0);
+}
+
+/*
+ * rv_mon - try to run a monitor passed as argument
+ */
+static void rv_mon(int argc, char **argv)
+{
+	char *monitor_name;
+	int i, run;
+
+	static const char *const usage[] = {
+		"",
+		"  usage: rv mon [-h] monitor [monitor options]",
+		"",
+		"	run a monitor",
+		"",
+		"	-h/--help: print this menu",
+		"",
+		"	monitor [monitor options]: the monitor, passing",
+		"	the arguments to the [monitor options]",
+		NULL,
+	};
+
+	/* requires at least one argument */
+	if (argc == 1) {
+
+		fprintf(stderr, "rv version %s\n", VERSION);
+
+		for (i = 0; usage[i]; i++)
+			fprintf(stderr, "%s\n", usage[i]);
+		exit(1);
+	} else if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {
+
+		fprintf(stderr, "rv version %s\n", VERSION);
+
+		for (i = 0; usage[i]; i++)
+			fprintf(stderr, "%s\n", usage[i]);
+		exit(0);
+	}
+
+	monitor_name = argv[1];
+	/*
+	 * Call all possible monitor implementations, looking
+	 * for the [monitor].
+	 */
+
+	if (!run)
+		err_msg("rv: monitor %s does not exist\n", monitor_name);
+	exit(!run);
+}
+
+static void usage(int exit_val, const char *fmt, ...)
+{
+	char message[1024];
+	va_list ap;
+	int i;
+
+	static const char *const usage[] = {
+		"",
+		"  usage: rv command [-h] [command_options]",
+		"",
+		"	-h/--help: print this menu",
+		"",
+		"	command: run one of the following command:",
+		"	  list: list all available monitors",
+		"	  mon:  run a monitor",
+		"",
+		"	[command options]: each command has its own set of options",
+		"		           run rv command -h for further information",
+		NULL,
+	};
+
+	va_start(ap, fmt);
+	vsnprintf(message, sizeof(message), fmt, ap);
+	va_end(ap);
+
+	fprintf(stderr, "rv version %s: %s\n", VERSION, message);
+
+	for (i = 0; usage[i]; i++)
+		fprintf(stderr, "%s\n", usage[i]);
+
+	exit(exit_val);
+}
+
+/*
+ * main - select which main sending the command
+ *
+ * main itself redirects the arguments to the sub-commands
+ * to handle the options.
+ *
+ * subcommands should exit.
+ */
+int main(int argc, char **argv)
+{
+	if (geteuid())
+		usage(1, "%s needs root permission", argv[0]);
+
+	if (argc <= 1)
+		usage(1, "%s requires a command", argv[0]);
+
+	if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help"))
+		usage(0, "help");
+
+	if (!strcmp(argv[1], "list"))
+		rv_list(--argc, &argv[1]);
+
+	if (!strcmp(argv[1], "mon")) {
+		/*
+		 * monitor's main should monitor should_stop() function.
+		 * and exit.
+		 */
+		signal(SIGINT, stop_rv);
+
+		rv_mon(argc - 1, &argv[1]);
+	}
+
+	/* invalid sub-command */
+	usage(1, "%s does not know the %s command, old version?", argv[0], argv[1]);
+}