kernel/trace/trace_events_inject.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * trace_events_inject - trace event injection
  *
  * Copyright (C) 2019 Cong Wang <cwang@twitter.com>
  */

 #include <linux/module.h>
 #include <linux/ctype.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/rculist.h>

 #include "trace.h"

 static int
 trace_inject_entry(struct trace_event_file *file, void *rec, int len)
 {
 	struct trace_event_buffer fbuffer;
 	int written = 0;
 	void *entry;

 	rcu_read_lock_sched();
 	entry = trace_event_buffer_reserve(&fbuffer, file, len);
 	if (entry) {
 		memcpy(entry, rec, len);
 		written = len;
 		trace_event_buffer_commit(&fbuffer);
 	}
 	rcu_read_unlock_sched();

 	return written;
 }

 static int
 parse_field(char *str, struct trace_event_call *call,
 	    struct ftrace_event_field **pf, u64 *pv)
 {
 	struct ftrace_event_field *field;
 	char *field_name;
 	int s, i = 0;
 	int len;
 	u64 val;

 	if (!str[i])
 		return 0;
 	/* First find the field to associate to */
 	while (isspace(str[i]))
 		i++;
 	s = i;
 	while (isalnum(str[i]) || str[i] == '_')
 		i++;
 	len = i - s;
 	if (!len)
 		return -EINVAL;

 	field_name = kmemdup_nul(str + s, len, GFP_KERNEL);
 	if (!field_name)
 		return -ENOMEM;
 	field = trace_find_event_field(call, field_name);
 	kfree(field_name);
 	if (!field)
 		return -ENOENT;

 	*pf = field;
 	while (isspace(str[i]))
 		i++;
 	if (str[i] != '=')
 		return -EINVAL;
 	i++;
 	while (isspace(str[i]))
 		i++;
 	s = i;
 	if (isdigit(str[i]) || str[i] == '-') {
 		char *num, c;
 		int ret;

 		/* Make sure the field is not a string */
 		if (is_string_field(field))
 			return -EINVAL;

 		if (str[i] == '-')
 			i++;

 		/* We allow 0xDEADBEEF */
 		while (isalnum(str[i]))
 			i++;
 		num = str + s;
 		c = str[i];
 		if (c != '\0' && !isspace(c))
 			return -EINVAL;
 		str[i] = '\0';
 		/* Make sure it is a value */
 		if (field->is_signed)
 			ret = kstrtoll(num, 0, &val);
 		else
 			ret = kstrtoull(num, 0, &val);
 		str[i] = c;
 		if (ret)
 			return ret;

 		*pv = val;
 		return i;
 	} else if (str[i] == '\'' || str[i] == '"') {
 		char q = str[i];

 		/* Make sure the field is OK for strings */
 		if (!is_string_field(field))
 			return -EINVAL;

 		for (i++; str[i]; i++) {
 			if (str[i] == '\\' && str[i + 1]) {
 				i++;
 				continue;
 			}
 			if (str[i] == q)
 				break;
 		}
 		if (!str[i])
 			return -EINVAL;

 		/* Skip quotes */
 		s++;
 		len = i - s;
 		if (len >= MAX_FILTER_STR_VAL)
 			return -EINVAL;

 		*pv = (unsigned long)(str + s);
 		str[i] = 0;
 		/* go past the last quote */
 		i++;
 		return i;
 	}

 	return -EINVAL;
 }

 static int trace_get_entry_size(struct trace_event_call *call)
 {
 	struct ftrace_event_field *field;
 	struct list_head *head;
 	int size = 0;

 	head = trace_get_fields(call);
 	list_for_each_entry(field, head, link) {
 		if (field->size + field->offset > size)
 			size = field->size + field->offset;
 	}

 	return size;
 }

 static void *trace_alloc_entry(struct trace_event_call *call, int *size)
 {
 	int entry_size = trace_get_entry_size(call);
 	struct ftrace_event_field *field;
 	struct list_head *head;
 	void *entry = NULL;

 	/* We need an extra '\0' at the end. */
 	entry = kzalloc(entry_size + 1, GFP_KERNEL);
 	if (!entry)
 		return NULL;

 	head = trace_get_fields(call);
 	list_for_each_entry(field, head, link) {
 		if (!is_string_field(field))
 			continue;
 		if (field->filter_type == FILTER_STATIC_STRING)
 			continue;
 		if (field->filter_type == FILTER_DYN_STRING) {
 			u32 *str_item;
 			int str_loc = entry_size & 0xffff;

 			str_item = (u32 *)(entry + field->offset);
 			*str_item = str_loc; /* string length is 0. */
 		} else {
 			char **paddr;

 			paddr = (char **)(entry + field->offset);
 			*paddr = "";
 		}
 	}

 	*size = entry_size + 1;
 	return entry;
 }

 #define INJECT_STRING "STATIC STRING CAN NOT BE INJECTED"

 /* Caller is responsible to free the *pentry. */
 static int parse_entry(char *str, struct trace_event_call *call, void **pentry)
 {
 	struct ftrace_event_field *field;
 	void *entry = NULL;
 	int entry_size;
 	u64 val = 0;
 	int len;

 	entry = trace_alloc_entry(call, &entry_size);
 	*pentry = entry;
 	if (!entry)
 		return -ENOMEM;

 	tracing_generic_entry_update(entry, call->event.type,
 				     tracing_gen_ctx());

 	while ((len = parse_field(str, call, &field, &val)) > 0) {
 		if (is_function_field(field))
 			return -EINVAL;

 		if (is_string_field(field)) {
 			char *addr = (char *)(unsigned long) val;

 			if (field->filter_type == FILTER_STATIC_STRING) {
 				strlcpy(entry + field->offset, addr, field->size);
 			} else if (field->filter_type == FILTER_DYN_STRING) {
 				int str_len = strlen(addr) + 1;
 				int str_loc = entry_size & 0xffff;
 				u32 *str_item;

 				entry_size += str_len;
 				*pentry = krealloc(entry, entry_size, GFP_KERNEL);
 				if (!*pentry) {
 					kfree(entry);
 					return -ENOMEM;
 				}
 				entry = *pentry;

 				strlcpy(entry + (entry_size - str_len), addr, str_len);
 				str_item = (u32 *)(entry + field->offset);
 				*str_item = (str_len << 16) | str_loc;
 			} else {
 				char **paddr;

 				paddr = (char **)(entry + field->offset);
 				*paddr = INJECT_STRING;
 			}
 		} else {
 			switch (field->size) {
 			case 1: {
 				u8 tmp = (u8) val;

 				memcpy(entry + field->offset, &tmp, 1);
 				break;
 			}
 			case 2: {
 				u16 tmp = (u16) val;

 				memcpy(entry + field->offset, &tmp, 2);
 				break;
 			}
 			case 4: {
 				u32 tmp = (u32) val;

 				memcpy(entry + field->offset, &tmp, 4);
 				break;
 			}
 			case 8:
 				memcpy(entry + field->offset, &val, 8);
 				break;
 			default:
 				return -EINVAL;
 			}
 		}

 		str += len;
 	}

 	if (len < 0)
 		return len;

 	return entry_size;
 }

 static ssize_t
 event_inject_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		   loff_t *ppos)
 {
 	struct trace_event_call *call;
 	struct trace_event_file *file;
 	int err = -ENODEV, size;
 	void *entry = NULL;
 	char *buf;

 	if (cnt >= PAGE_SIZE)
 		return -EINVAL;

 	buf = memdup_user_nul(ubuf, cnt);
 	if (IS_ERR(buf))
 		return PTR_ERR(buf);
 	strim(buf);

 	mutex_lock(&event_mutex);
 	file = event_file_data(filp);
 	if (file) {
 		call = file->event_call;
 		size = parse_entry(buf, call, &entry);
 		if (size < 0)
 			err = size;
 		else
 			err = trace_inject_entry(file, entry, size);
 	}
 	mutex_unlock(&event_mutex);

 	kfree(entry);
 	kfree(buf);

 	if (err < 0)
 		return err;

 	*ppos += err;
 	return cnt;
 }

 static ssize_t
 event_inject_read(struct file *file, char __user *buf, size_t size,
 		  loff_t *ppos)
 {
 	return -EPERM;
 }

 const struct file_operations event_inject_fops = {
 	.open = tracing_open_generic,
 	.read = event_inject_read,
 	.write = event_inject_write,
 };
	// SPDX-License-Identifier: GPL-2.0
	/*
	* trace_events_inject - trace event injection
	*
	* Copyright (C) 2019 Cong Wang <cwang@twitter.com>
	*/

	#include <linux/module.h>
	#include <linux/ctype.h>
	#include <linux/mutex.h>
	#include <linux/slab.h>
	#include <linux/rculist.h>

	#include "trace.h"

	static int
	trace_inject_entry(struct trace_event_file file, void rec, int len)
	{
	struct trace_event_buffer fbuffer;
	int written = 0;
	void *entry;

	rcu_read_lock_sched();
	entry = trace_event_buffer_reserve(&fbuffer, file, len);
	if (entry) {
	memcpy(entry, rec, len);
	written = len;
	trace_event_buffer_commit(&fbuffer);
	}
	rcu_read_unlock_sched();

	return written;
	}

	static int
	parse_field(char str, struct trace_event_call call,
	struct ftrace_event_field *pf, u64 pv)
	{
	struct ftrace_event_field *field;
	char *field_name;
	int s, i = 0;
	int len;
	u64 val;

	if (!str[i])
	return 0;
	/* First find the field to associate to */
	while (isspace(str[i]))
	i++;
	s = i;
	while (isalnum(str[i]) \|\| str[i] == '_')
	i++;
	len = i - s;
	if (!len)
	return -EINVAL;

	field_name = kmemdup_nul(str + s, len, GFP_KERNEL);
	if (!field_name)
	return -ENOMEM;
	field = trace_find_event_field(call, field_name);
	kfree(field_name);
	if (!field)
	return -ENOENT;

	*pf = field;
	while (isspace(str[i]))
	i++;
	if (str[i] != '=')
	return -EINVAL;
	i++;
	while (isspace(str[i]))
	i++;
	s = i;
	if (isdigit(str[i]) \|\| str[i] == '-') {
	char *num, c;
	int ret;

	/* Make sure the field is not a string */
	if (is_string_field(field))
	return -EINVAL;

	if (str[i] == '-')
	i++;

	/* We allow 0xDEADBEEF */
	while (isalnum(str[i]))
	i++;
	num = str + s;
	c = str[i];
	if (c != '\0' && !isspace(c))
	return -EINVAL;
	str[i] = '\0';
	/* Make sure it is a value */
	if (field->is_signed)
	ret = kstrtoll(num, 0, &val);
	else
	ret = kstrtoull(num, 0, &val);
	str[i] = c;
	if (ret)
	return ret;

	*pv = val;
	return i;
	} else if (str[i] == '\'' \|\| str[i] == '"') {
	char q = str[i];

	/* Make sure the field is OK for strings */
	if (!is_string_field(field))
	return -EINVAL;

	for (i++; str[i]; i++) {
	if (str[i] == '\\' && str[i + 1]) {
	i++;
	continue;
	}
	if (str[i] == q)
	break;
	}
	if (!str[i])
	return -EINVAL;

	/* Skip quotes */
	s++;
	len = i - s;
	if (len >= MAX_FILTER_STR_VAL)
	return -EINVAL;

	*pv = (unsigned long)(str + s);
	str[i] = 0;
	/* go past the last quote */
	i++;
	return i;
	}

	return -EINVAL;
	}

	static int trace_get_entry_size(struct trace_event_call *call)
	{
	struct ftrace_event_field *field;
	struct list_head *head;
	int size = 0;

	head = trace_get_fields(call);
	list_for_each_entry(field, head, link) {
	if (field->size + field->offset > size)
	size = field->size + field->offset;
	}

	return size;
	}

	static void trace_alloc_entry(struct trace_event_call call, int *size)
	{
	int entry_size = trace_get_entry_size(call);
	struct ftrace_event_field *field;
	struct list_head *head;
	void *entry = NULL;

	/* We need an extra '\0' at the end. */
	entry = kzalloc(entry_size + 1, GFP_KERNEL);
	if (!entry)
	return NULL;

	head = trace_get_fields(call);
	list_for_each_entry(field, head, link) {
	if (!is_string_field(field))
	continue;
	if (field->filter_type == FILTER_STATIC_STRING)
	continue;
	if (field->filter_type == FILTER_DYN_STRING) {
	u32 *str_item;
	int str_loc = entry_size & 0xffff;

	str_item = (u32 *)(entry + field->offset);
	str_item = str_loc; / string length is 0. */
	} else {
	char **paddr;

	paddr = (char **)(entry + field->offset);
	*paddr = "";
	}
	}

	*size = entry_size + 1;
	return entry;
	}

	#define INJECT_STRING "STATIC STRING CAN NOT BE INJECTED"

	/* Caller is responsible to free the pentry. /
	static int parse_entry(char str, struct trace_event_call call, void **pentry)
	{
	struct ftrace_event_field *field;
	void *entry = NULL;
	int entry_size;
	u64 val = 0;
	int len;

	entry = trace_alloc_entry(call, &entry_size);
	*pentry = entry;
	if (!entry)
	return -ENOMEM;

	tracing_generic_entry_update(entry, call->event.type,
	tracing_gen_ctx());

	while ((len = parse_field(str, call, &field, &val)) > 0) {
	if (is_function_field(field))
	return -EINVAL;

	if (is_string_field(field)) {
	char addr = (char )(unsigned long) val;

	if (field->filter_type == FILTER_STATIC_STRING) {
	strlcpy(entry + field->offset, addr, field->size);
	} else if (field->filter_type == FILTER_DYN_STRING) {
	int str_len = strlen(addr) + 1;
	int str_loc = entry_size & 0xffff;
	u32 *str_item;

	entry_size += str_len;
	*pentry = krealloc(entry, entry_size, GFP_KERNEL);
	if (!*pentry) {
	kfree(entry);
	return -ENOMEM;
	}
	entry = *pentry;

	strlcpy(entry + (entry_size - str_len), addr, str_len);
	str_item = (u32 *)(entry + field->offset);
	*str_item = (str_len << 16) \| str_loc;
	} else {
	char **paddr;

	paddr = (char **)(entry + field->offset);
	*paddr = INJECT_STRING;
	}
	} else {
	switch (field->size) {
	case 1: {
	u8 tmp = (u8) val;

	memcpy(entry + field->offset, &tmp, 1);
	break;
	}
	case 2: {
	u16 tmp = (u16) val;

	memcpy(entry + field->offset, &tmp, 2);
	break;
	}
	case 4: {
	u32 tmp = (u32) val;

	memcpy(entry + field->offset, &tmp, 4);
	break;
	}
	case 8:
	memcpy(entry + field->offset, &val, 8);
	break;
	default:
	return -EINVAL;
	}
	}

	str += len;
	}

	if (len < 0)
	return len;

	return entry_size;
	}

	static ssize_t
	event_inject_write(struct file filp, const char __user ubuf, size_t cnt,
	loff_t *ppos)
	{
	struct trace_event_call *call;
	struct trace_event_file *file;
	int err = -ENODEV, size;
	void *entry = NULL;
	char *buf;

	if (cnt >= PAGE_SIZE)
	return -EINVAL;

	buf = memdup_user_nul(ubuf, cnt);
	if (IS_ERR(buf))
	return PTR_ERR(buf);
	strim(buf);

	mutex_lock(&event_mutex);
	file = event_file_data(filp);
	if (file) {
	call = file->event_call;
	size = parse_entry(buf, call, &entry);
	if (size < 0)
	err = size;
	else
	err = trace_inject_entry(file, entry, size);
	}
	mutex_unlock(&event_mutex);

	kfree(entry);
	kfree(buf);

	if (err < 0)
	return err;

	*ppos += err;
	return cnt;
	}

	static ssize_t
	event_inject_read(struct file file, char __user buf, size_t size,
	loff_t *ppos)
	{
	return -EPERM;
	}

	const struct file_operations event_inject_fops = {
	.open = tracing_open_generic,
	.read = event_inject_read,
	.write = event_inject_write,
	};