arp_tables.c

该文件是rt_linux

			  + SMP_ALIGN(tmp.size) * smp_num_cpus);
	if (!newinfo)
		return -ENOMEM;

	if (copy_from_user(newinfo->entries, user + sizeof(tmp),
			   tmp.size) != 0) {
		ret = -EFAULT;
		goto free_newinfo;
	}

	counters = vmalloc(tmp.num_counters * sizeof(struct arpt_counters));
	if (!counters) {
		ret = -ENOMEM;
		goto free_newinfo;
	}
	memset(counters, 0, tmp.num_counters * sizeof(struct arpt_counters));

	ret = translate_table(tmp.name, tmp.valid_hooks,
			      newinfo, tmp.size, tmp.num_entries,
			      tmp.hook_entry, tmp.underflow);
	if (ret != 0)
		goto free_newinfo_counters;

	duprintf("arp_tables: Translated table\n");

	t = find_table_lock(tmp.name, &ret, &arpt_mutex);
	if (!t)
		goto free_newinfo_counters_untrans;

	/* You lied! */
	if (tmp.valid_hooks != t->valid_hooks) {
		duprintf("Valid hook crap: %08X vs %08X\n",
			 tmp.valid_hooks, t->valid_hooks);
		ret = -EINVAL;
		goto free_newinfo_counters_untrans_unlock;
	}

	oldinfo = replace_table(t, tmp.num_counters, newinfo, &ret);
	if (!oldinfo)
		goto free_newinfo_counters_untrans_unlock;

	/* Update module usage count based on number of rules */
	duprintf("do_replace: oldnum=%u, initnum=%u, newnum=%u\n",
		oldinfo->number, oldinfo->initial_entries, newinfo->number);
	if (t->me && (oldinfo->number <= oldinfo->initial_entries) &&
 	    (newinfo->number > oldinfo->initial_entries))
		__MOD_INC_USE_COUNT(t->me);
	else if (t->me && (oldinfo->number > oldinfo->initial_entries) &&
	 	 (newinfo->number <= oldinfo->initial_entries))
		__MOD_DEC_USE_COUNT(t->me);

	/* Get the old counters. */
	get_counters(oldinfo, counters);
	/* Decrease module usage counts and free resource */
	ARPT_ENTRY_ITERATE(oldinfo->entries, oldinfo->size, cleanup_entry,NULL);
	vfree(oldinfo);
	/* Silent error: too late now. */
	copy_to_user(tmp.counters, counters,
		     sizeof(struct arpt_counters) * tmp.num_counters);
	vfree(counters);
	up(&arpt_mutex);
	return 0;

 free_newinfo_counters_untrans_unlock:
	up(&arpt_mutex);
 free_newinfo_counters_untrans:
	ARPT_ENTRY_ITERATE(newinfo->entries, newinfo->size, cleanup_entry, NULL);
 free_newinfo_counters:
	vfree(counters);
 free_newinfo:
	vfree(newinfo);
	return ret;
}

/* We're lazy, and add to the first CPU; overflow works its fey magic
 * and everything is OK.
 */
static inline int add_counter_to_entry(struct arpt_entry *e,
				       const struct arpt_counters addme[],
				       unsigned int *i)
{

	ADD_COUNTER(e->counters, addme[*i].bcnt, addme[*i].pcnt);

	(*i)++;
	return 0;
}

static int do_add_counters(void *user, unsigned int len)
{
	unsigned int i;
	struct arpt_counters_info tmp, *paddc;
	struct arpt_table *t;
	int ret;

	if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
		return -EFAULT;

	if (len != sizeof(tmp) + tmp.num_counters*sizeof(struct arpt_counters))
		return -EINVAL;

	paddc = vmalloc(len);
	if (!paddc)
		return -ENOMEM;

	if (copy_from_user(paddc, user, len) != 0) {
		ret = -EFAULT;
		goto free;
	}

	t = find_table_lock(tmp.name, &ret, &arpt_mutex);
	if (!t)
		goto free;

	write_lock_bh(&t->lock);
	if (t->private->number != paddc->num_counters) {
		ret = -EINVAL;
		goto unlock_up_free;
	}

	i = 0;
	ARPT_ENTRY_ITERATE(t->private->entries,
			   t->private->size,
			   add_counter_to_entry,
			   paddc->counters,
			   &i);
 unlock_up_free:
	write_unlock_bh(&t->lock);
	up(&arpt_mutex);
 free:
	vfree(paddc);

	return ret;
}

static int do_arpt_set_ctl(struct sock *sk, int cmd, void *user, unsigned int len)
{
	int ret;

	if (!capable(CAP_NET_ADMIN))
		return -EPERM;

	switch (cmd) {
	case ARPT_SO_SET_REPLACE:
		ret = do_replace(user, len);
		break;

	case ARPT_SO_SET_ADD_COUNTERS:
		ret = do_add_counters(user, len);
		break;

	default:
		duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
		ret = -EINVAL;
	}

	return ret;
}

static int do_arpt_get_ctl(struct sock *sk, int cmd, void *user, int *len)
{
	int ret;

	if (!capable(CAP_NET_ADMIN))
		return -EPERM;

	switch (cmd) {
	case ARPT_SO_GET_INFO: {
		char name[ARPT_TABLE_MAXNAMELEN];
		struct arpt_table *t;

		if (*len != sizeof(struct arpt_getinfo)) {
			duprintf("length %u != %Zu\n", *len,
				 sizeof(struct arpt_getinfo));
			ret = -EINVAL;
			break;
		}

		if (copy_from_user(name, user, sizeof(name)) != 0) {
			ret = -EFAULT;
			break;
		}
		name[ARPT_TABLE_MAXNAMELEN-1] = '\0';
		t = find_table_lock(name, &ret, &arpt_mutex);
		if (t) {
			struct arpt_getinfo info;

			info.valid_hooks = t->valid_hooks;
			memcpy(info.hook_entry, t->private->hook_entry,
			       sizeof(info.hook_entry));
			memcpy(info.underflow, t->private->underflow,
			       sizeof(info.underflow));
			info.num_entries = t->private->number;
			info.size = t->private->size;
			strcpy(info.name, name);

			if (copy_to_user(user, &info, *len) != 0)
				ret = -EFAULT;
			else
				ret = 0;

			up(&arpt_mutex);
		}
	}
	break;

	case ARPT_SO_GET_ENTRIES: {
		struct arpt_get_entries get;

		if (*len < sizeof(get)) {
			duprintf("get_entries: %u < %Zu\n", *len, sizeof(get));
			ret = -EINVAL;
		} else if (copy_from_user(&get, user, sizeof(get)) != 0) {
			ret = -EFAULT;
		} else if (*len != sizeof(struct arpt_get_entries) + get.size) {
			duprintf("get_entries: %u != %Zu\n", *len,
				 sizeof(struct arpt_get_entries) + get.size);
			ret = -EINVAL;
		} else
			ret = get_entries(&get, user);
		break;
	}

	default:
		duprintf("do_arpt_get_ctl: unknown request %i\n", cmd);
		ret = -EINVAL;
	}

	return ret;
}

/* Registration hooks for targets. */
int arpt_register_target(struct arpt_target *target)
{
	int ret;

	MOD_INC_USE_COUNT;
	ret = down_interruptible(&arpt_mutex);
	if (ret != 0) {
		MOD_DEC_USE_COUNT;
		return ret;
	}
	if (!list_named_insert(&arpt_target, target)) {
		duprintf("arpt_register_target: `%s' already in list!\n",
			 target->name);
		ret = -EINVAL;
		MOD_DEC_USE_COUNT;
	}
	up(&arpt_mutex);
	return ret;
}

void arpt_unregister_target(struct arpt_target *target)
{
	down(&arpt_mutex);
	LIST_DELETE(&arpt_target, target);
	up(&arpt_mutex);
	MOD_DEC_USE_COUNT;
}

int arpt_register_table(struct arpt_table *table)
{
	int ret;
	struct arpt_table_info *newinfo;
	static struct arpt_table_info bootstrap
		= { 0, 0, 0, { 0 }, { 0 }, { } };

	MOD_INC_USE_COUNT;
	newinfo = vmalloc(sizeof(struct arpt_table_info)
			  + SMP_ALIGN(table->table->size) * smp_num_cpus);
	if (!newinfo) {
		ret = -ENOMEM;
		MOD_DEC_USE_COUNT;
		return ret;
	}
	memcpy(newinfo->entries, table->table->entries, table->table->size);

	ret = translate_table(table->name, table->valid_hooks,
			      newinfo, table->table->size,
			      table->table->num_entries,
			      table->table->hook_entry,
			      table->table->underflow);
	duprintf("arpt_register_table: translate table gives %d\n", ret);
	if (ret != 0) {
		vfree(newinfo);
		MOD_DEC_USE_COUNT;
		return ret;
	}

	ret = down_interruptible(&arpt_mutex);
	if (ret != 0) {
		vfree(newinfo);
		MOD_DEC_USE_COUNT;
		return ret;
	}

	/* Don't autoload: we'd eat our tail... */
	if (list_named_find(&arpt_tables, table->name)) {
		ret = -EEXIST;
		goto free_unlock;
	}

	/* Simplifies replace_table code. */
	table->private = &bootstrap;
	if (!replace_table(table, 0, newinfo, &ret))
		goto free_unlock;

	duprintf("table->private->number = %u\n",
		 table->private->number);
	
	/* save number of initial entries */
	table->private->initial_entries = table->private->number;

	table->lock = RW_LOCK_UNLOCKED;
	list_prepend(&arpt_tables, table);

 unlock:
	up(&arpt_mutex);
	return ret;

 free_unlock:
	vfree(newinfo);
	MOD_DEC_USE_COUNT;
	goto unlock;
}

void arpt_unregister_table(struct arpt_table *table)
{
	down(&arpt_mutex);
	LIST_DELETE(&arpt_tables, table);
	up(&arpt_mutex);

	/* Decrease module usage counts and free resources */
	ARPT_ENTRY_ITERATE(table->private->entries, table->private->size,
			   cleanup_entry, NULL);
	vfree(table->private);
	MOD_DEC_USE_COUNT;
}

/* The built-in targets: standard (NULL) and error. */
static struct arpt_target arpt_standard_target
= { { NULL, NULL }, ARPT_STANDARD_TARGET, NULL, NULL, NULL };
static struct arpt_target arpt_error_target
= { { NULL, NULL }, ARPT_ERROR_TARGET, arpt_error, NULL, NULL };

static struct nf_sockopt_ops arpt_sockopts
= { { NULL, NULL }, PF_INET, ARPT_BASE_CTL, ARPT_SO_SET_MAX+1, do_arpt_set_ctl,
    ARPT_BASE_CTL, ARPT_SO_GET_MAX+1, do_arpt_get_ctl, 0, NULL  };

#ifdef CONFIG_PROC_FS
static inline int print_name(const struct arpt_table *t,
			     off_t start_offset, char *buffer, int length,
			     off_t *pos, unsigned int *count)
{
	if ((*count)++ >= start_offset) {
		unsigned int namelen;

		namelen = sprintf(buffer + *pos, "%s\n", t->name);
		if (*pos + namelen > length) {
			/* Stop iterating */
			return 1;
		}
		*pos += namelen;
	}
	return 0;
}

static int arpt_get_tables(char *buffer, char **start, off_t offset, int length)
{
	off_t pos = 0;
	unsigned int count = 0;

	if (down_interruptible(&arpt_mutex) != 0)
		return 0;

	LIST_FIND(&arpt_tables, print_name, struct arpt_table *,
		  offset, buffer, length, &pos, &count);

	up(&arpt_mutex);

	/* `start' hack - see fs/proc/generic.c line ~105 */
	*start=(char *)((unsigned long)count-offset);
	return pos;
}
#endif /*CONFIG_PROC_FS*/

static int __init init(void)
{
	int ret;

	/* Noone else will be downing sem now, so we won't sleep */
	down(&arpt_mutex);
	list_append(&arpt_target, &arpt_standard_target);
	list_append(&arpt_target, &arpt_error_target);
	up(&arpt_mutex);

	/* Register setsockopt */
	ret = nf_register_sockopt(&arpt_sockopts);
	if (ret < 0) {
		duprintf("Unable to register sockopts.\n");
		return ret;
	}

#ifdef CONFIG_PROC_FS
	{
		struct proc_dir_entry *proc;

		proc = proc_net_create("arp_tables_names", 0, arpt_get_tables);
		if (!proc) {
			nf_unregister_sockopt(&arpt_sockopts);
			return -ENOMEM;
		}
		proc->owner = THIS_MODULE;
	}
#endif

	printk("arp_tables: (C) 2002 David S. Miller\n");
	return 0;
}

static void __exit fini(void)
{
	nf_unregister_sockopt(&arpt_sockopts);
#ifdef CONFIG_PROC_FS
	proc_net_remove("arp_tables_names");
#endif
}

EXPORT_SYMBOL(arpt_register_table);
EXPORT_SYMBOL(arpt_unregister_table);
EXPORT_SYMBOL(arpt_do_table);
EXPORT_SYMBOL(arpt_register_target);
EXPORT_SYMBOL(arpt_unregister_target);

module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");