/*
 * security/tomoyo/memory.c
 *
 * Memory management functions for TOMOYO.
 *
 * Copyright (C) 2005-2010  NTT DATA CORPORATION
 */

#include <linux/hash.h>
#include <linux/slab.h>
#include "common.h"

/**
 * tomoyo_warn_oom - Print out of memory warning message.
 *
 * @function: Function's name.
 */
void tomoyo_warn_oom(const char *function)
{
	/* Reduce error messages. */
	static pid_t tomoyo_last_pid;
	const pid_t pid = current->pid;
	if (tomoyo_last_pid != pid) {
		printk(KERN_WARNING "ERROR: Out of memory at %s.\n",
		       function);
		tomoyo_last_pid = pid;
	}
	if (!tomoyo_policy_loaded)
		panic("MAC Initialization failed.\n");
}

/* Memory allocated for policy. */
static atomic_t tomoyo_policy_memory_size;
/* Quota for holding policy. */
static unsigned int tomoyo_quota_for_policy;

/**
 * tomoyo_memory_ok - Check memory quota.
 *
 * @ptr: Pointer to allocated memory.
 *
 * Returns true on success, false otherwise.
 *
 * Returns true if @ptr is not NULL and quota not exceeded, false otherwise.
 */
bool tomoyo_memory_ok(void *ptr)
{
	size_t s = ptr ? ksize(ptr) : 0;
	atomic_add(s, &tomoyo_policy_memory_size);
	if (ptr && (!tomoyo_quota_for_policy ||
		    atomic_read(&tomoyo_policy_memory_size)
		    <= tomoyo_quota_for_policy)) {
		memset(ptr, 0, s);
		return true;
	}
	atomic_sub(s, &tomoyo_policy_memory_size);
	tomoyo_warn_oom(__func__);
	return false;
}

/**
 * tomoyo_commit_ok - Check memory quota.
 *
 * @data:   Data to copy from.
 * @size:   Size in byte.
 *
 * Returns pointer to allocated memory on success, NULL otherwise.
 * @data is zero-cleared on success.
 */
void *tomoyo_commit_ok(void *data, const unsigned int size)
{
	void *ptr = kzalloc(size, GFP_NOFS);
	if (tomoyo_memory_ok(ptr)) {
		memmove(ptr, data, size);
		memset(data, 0, size);
		return ptr;
	}
	return NULL;
}

/**
 * tomoyo_memory_free - Free memory for elements.
 *
 * @ptr:  Pointer to allocated memory.
 */
void tomoyo_memory_free(void *ptr)
{
	atomic_sub(ksize(ptr), &tomoyo_policy_memory_size);
	kfree(ptr);
}

/*
 * tomoyo_name_list is used for holding string data used by TOMOYO.
 * Since same string data is likely used for multiple times (e.g.
 * "/lib/libc-2.5.so"), TOMOYO shares string data in the form of
 * "const struct tomoyo_path_info *".
 */
struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];

/**
 * tomoyo_get_name - Allocate permanent memory for string data.
 *
 * @name: The string to store into the permernent memory.
 *
 * Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
 */
const struct tomoyo_path_info *tomoyo_get_name(const char *name)
{
	struct tomoyo_name_entry *ptr;
	unsigned int hash;
	int len;
	int allocated_len;
	struct list_head *head;

	if (!name)
		return NULL;
	len = strlen(name) + 1;
	hash = full_name_hash((const unsigned char *) name, len - 1);
	head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
	if (mutex_lock_interruptible(&tomoyo_policy_lock))
		return NULL;
	list_for_each_entry(ptr, head, list) {
		if (hash != ptr->entry.hash || strcmp(name, ptr->entry.name))
			continue;
		atomic_inc(&ptr->users);
		goto out;
	}
	ptr = kzalloc(sizeof(*ptr) + len, GFP_NOFS);
	allocated_len = ptr ? ksize(ptr) : 0;
	if (!ptr || (tomoyo_quota_for_policy &&
		     atomic_read(&tomoyo_policy_memory_size) + allocated_len
		     > tomoyo_quota_for_policy)) {
		kfree(ptr);
		ptr = NULL;
		tomoyo_warn_oom(__func__);
		goto out;
	}
	atomic_add(allocated_len, &tomoyo_policy_memory_size);
	ptr->entry.name = ((char *) ptr) + sizeof(*ptr);
	memmove((char *) ptr->entry.name, name, len);
	atomic_set(&ptr->users, 1);
	tomoyo_fill_path_info(&ptr->entry);
	list_add_tail(&ptr->list, head);
 out:
	mutex_unlock(&tomoyo_policy_lock);
	return ptr ? &ptr->entry : NULL;
}

/**
 * tomoyo_mm_init - Initialize mm related code.
 */
void __init tomoyo_mm_init(void)
{
	int idx;

	for (idx = 0; idx < TOMOYO_MAX_HASH; idx++)
		INIT_LIST_HEAD(&tomoyo_name_list[idx]);
	INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
	tomoyo_kernel_domain.domainname = tomoyo_get_name(TOMOYO_ROOT_NAME);
	list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
	idx = tomoyo_read_lock();
	if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
		panic("Can't register tomoyo_kernel_domain");
	{
		/* Load built-in policy. */
		tomoyo_write_domain_initializer_policy("/sbin/hotplug",
						       false, false);
		tomoyo_write_domain_initializer_policy("/sbin/modprobe",
						       false, false);
	}
	tomoyo_read_unlock(idx);
}


/* Memory allocated for query lists. */
unsigned int tomoyo_query_memory_size;
/* Quota for holding query lists. */
unsigned int tomoyo_quota_for_query;

/**
 * tomoyo_read_memory_counter - Check for memory usage in bytes.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns memory usage.
 */
int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head)
{
	if (!head->read_eof) {
		const unsigned int policy
			= atomic_read(&tomoyo_policy_memory_size);
		const unsigned int query = tomoyo_query_memory_size;
		char buffer[64];

		memset(buffer, 0, sizeof(buffer));
		if (tomoyo_quota_for_policy)
			snprintf(buffer, sizeof(buffer) - 1,
				 "   (Quota: %10u)",
				 tomoyo_quota_for_policy);
		else
			buffer[0] = '\0';
		tomoyo_io_printf(head, "Policy:       %10u%s\n", policy,
				 buffer);
		if (tomoyo_quota_for_query)
			snprintf(buffer, sizeof(buffer) - 1,
				 "   (Quota: %10u)",
				 tomoyo_quota_for_query);
		else
			buffer[0] = '\0';
		tomoyo_io_printf(head, "Query lists:  %10u%s\n", query,
				 buffer);
		tomoyo_io_printf(head, "Total:        %10u\n", policy + query);
		head->read_eof = true;
	}
	return 0;
}

/**
 * tomoyo_write_memory_quota - Set memory quota.
 *
 * @head: Pointer to "struct tomoyo_io_buffer".
 *
 * Returns 0.
 */
int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head)
{
	char *data = head->write_buf;
	unsigned int size;

	if (sscanf(data, "Policy: %u", &size) == 1)
		tomoyo_quota_for_policy = size;
	else if (sscanf(data, "Query lists: %u", &size) == 1)
		tomoyo_quota_for_query = size;
	return 0;
}