/*
   * security/tomoyo/memory.c
   *
   * Copyright (C) 2005-2011  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.
  ",
  		       function);
  		tomoyo_last_pid = pid;
  	}
  	if (!tomoyo_policy_loaded)
  		panic("MAC Initialization failed.
  ");
  }
  
  /* Memoy currently used by policy/audit log/query. */
  unsigned int tomoyo_memory_used[TOMOYO_MAX_MEMORY_STAT];
  /* Memory quota for "policy"/"audit log"/"query". */
  unsigned int tomoyo_memory_quota[TOMOYO_MAX_MEMORY_STAT];
  
  /**
   * 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.
   *
   * Caller holds tomoyo_policy_lock mutex.
   */
  bool tomoyo_memory_ok(void *ptr)
  {
  	if (ptr) {
  		const size_t s = ksize(ptr);
  		tomoyo_memory_used[TOMOYO_MEMORY_POLICY] += s;
  		if (!tomoyo_memory_quota[TOMOYO_MEMORY_POLICY] ||
  		    tomoyo_memory_used[TOMOYO_MEMORY_POLICY] <=
  		    tomoyo_memory_quota[TOMOYO_MEMORY_POLICY])
  			return true;
  		tomoyo_memory_used[TOMOYO_MEMORY_POLICY] -= s;
  	}
  	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.
   *
   * Caller holds tomoyo_policy_lock mutex.
   */
  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;
  	}
  	kfree(ptr);
  	return NULL;
  }
  
  /**
   * tomoyo_get_group - Allocate memory for "struct tomoyo_path_group"/"struct tomoyo_number_group".
   *
   * @param: Pointer to "struct tomoyo_acl_param".
   * @idx:   Index number.
   *
   * Returns pointer to "struct tomoyo_group" on success, NULL otherwise.
   */
  struct tomoyo_group *tomoyo_get_group(struct tomoyo_acl_param *param,
  				      const u8 idx)
  {
  	struct tomoyo_group e = { };
  	struct tomoyo_group *group = NULL;
  	struct list_head *list;
  	const char *group_name = tomoyo_read_token(param);
  	bool found = false;
  	if (!tomoyo_correct_word(group_name) || idx >= TOMOYO_MAX_GROUP)
  		return NULL;
  	e.group_name = tomoyo_get_name(group_name);
  	if (!e.group_name)
  		return NULL;
  	if (mutex_lock_interruptible(&tomoyo_policy_lock))
  		goto out;
  	list = &param->ns->group_list[idx];
  	list_for_each_entry(group, list, head.list) {
  		if (e.group_name != group->group_name ||
  		    atomic_read(&group->head.users) == TOMOYO_GC_IN_PROGRESS)
  			continue;
  		atomic_inc(&group->head.users);
  		found = true;
  		break;
  	}
  	if (!found) {
  		struct tomoyo_group *entry = tomoyo_commit_ok(&e, sizeof(e));
  		if (entry) {
  			INIT_LIST_HEAD(&entry->member_list);
  			atomic_set(&entry->head.users, 1);
  			list_add_tail_rcu(&entry->head.list, list);
  			group = entry;
  			found = true;
  		}
  	}
  	mutex_unlock(&tomoyo_policy_lock);
  out:
  	tomoyo_put_name(e.group_name);
  	return found ? group : NULL;
  }
  
  /*
   * 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 *ptr;
  	unsigned int hash;
  	int 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, head.list) {
  		if (hash != ptr->entry.hash || strcmp(name, ptr->entry.name) ||
  		    atomic_read(&ptr->head.users) == TOMOYO_GC_IN_PROGRESS)
  			continue;
  		atomic_inc(&ptr->head.users);
  		goto out;
  	}
  	ptr = kzalloc(sizeof(*ptr) + len, GFP_NOFS);
  	if (tomoyo_memory_ok(ptr)) {
  		ptr->entry.name = ((char *) ptr) + sizeof(*ptr);
  		memmove((char *) ptr->entry.name, name, len);
  		atomic_set(&ptr->head.users, 1);
  		tomoyo_fill_path_info(&ptr->entry);
  		list_add_tail(&ptr->head.list, head);
  	} else {
  		kfree(ptr);
  		ptr = NULL;
  	}
  out:
  	mutex_unlock(&tomoyo_policy_lock);
  	return ptr ? &ptr->entry : NULL;
  }
  
  /* Initial namespace.*/
  struct tomoyo_policy_namespace tomoyo_kernel_namespace;
  
  /**
   * 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]);
  	tomoyo_kernel_namespace.name = "<kernel>";
  	tomoyo_init_policy_namespace(&tomoyo_kernel_namespace);
  	tomoyo_kernel_domain.ns = &tomoyo_kernel_namespace;
  	INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
  	tomoyo_kernel_domain.domainname = tomoyo_get_name("<kernel>");
  	list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
  }