path: root/kernel/trace/trace_fprobe.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Fprobe-based tracing events
 * Copyright (C) 2022 Google LLC.
 */
#define pr_fmt(fmt)	"trace_fprobe: " fmt

#include <linux/fprobe.h>
#include <linux/module.h>
#include <linux/rculist.h>
#include <linux/security.h>
#include <linux/tracepoint.h>
#include <linux/uaccess.h>

#include "trace_dynevent.h"
#include "trace_probe.h"
#include "trace_probe_kernel.h"
#include "trace_probe_tmpl.h"

#define FPROBE_EVENT_SYSTEM "fprobes"
#define TRACEPOINT_EVENT_SYSTEM "tracepoints"
#define RETHOOK_MAXACTIVE_MAX 4096

static int trace_fprobe_create(const char *raw_command);
static int trace_fprobe_show(struct seq_file *m, struct dyn_event *ev);
static int trace_fprobe_release(struct dyn_event *ev);
static bool trace_fprobe_is_busy(struct dyn_event *ev);
static bool trace_fprobe_match(const char *system, const char *event,
			int argc, const char **argv, struct dyn_event *ev);

static struct dyn_event_operations trace_fprobe_ops = {
	.create = trace_fprobe_create,
	.show = trace_fprobe_show,
	.is_busy = trace_fprobe_is_busy,
	.free = trace_fprobe_release,
	.match = trace_fprobe_match,
};

/*
 * Fprobe event core functions
 */
struct trace_fprobe {
	struct dyn_event	devent;
	struct fprobe		fp;
	const char		*symbol;
	struct tracepoint	*tpoint;
	struct module		*mod;
	struct trace_probe	tp;
};

static bool is_trace_fprobe(struct dyn_event *ev)
{
	return ev->ops == &trace_fprobe_ops;
}

static struct trace_fprobe *to_trace_fprobe(struct dyn_event *ev)
{
	return container_of(ev, struct trace_fprobe, devent);
}

/**
 * for_each_trace_fprobe - iterate over the trace_fprobe list
 * @pos:	the struct trace_fprobe * for each entry
 * @dpos:	the struct dyn_event * to use as a loop cursor
 */
#define for_each_trace_fprobe(pos, dpos)	\
	for_each_dyn_event(dpos)		\
		if (is_trace_fprobe(dpos) && (pos = to_trace_fprobe(dpos)))

static bool trace_fprobe_is_return(struct trace_fprobe *tf)
{
	return tf->fp.exit_handler != NULL;
}

static bool trace_fprobe_is_tracepoint(struct trace_fprobe *tf)
{
	return tf->tpoint != NULL;
}

static const char *trace_fprobe_symbol(struct trace_fprobe *tf)
{
	return tf->symbol ? tf->symbol : "unknown";
}

static bool trace_fprobe_is_busy(struct dyn_event *ev)
{
	struct trace_fprobe *tf = to_trace_fprobe(ev);

	return trace_probe_is_enabled(&tf->tp);
}

static bool trace_fprobe_match_command_head(struct trace_fprobe *tf,
					    int argc, const char **argv)
{
	char buf[MAX_ARGSTR_LEN + 1];

	if (!argc)
		return true;

	snprintf(buf, sizeof(buf), "%s", trace_fprobe_symbol(tf));
	if (strcmp(buf, argv[0]))
		return false;
	argc--; argv++;

	return trace_probe_match_command_args(&tf->tp, argc, argv);
}

static bool trace_fprobe_match(const char *system, const char *event,
			int argc, const char **argv, struct dyn_event *ev)
{
	struct trace_fprobe *tf = to_trace_fprobe(ev);

	if (event[0] != '\0' && strcmp(trace_probe_name(&tf->tp), event))
		return false;

	if (system && strcmp(trace_probe_group_name(&tf->tp), system))
		return false;

	return <