x_tables.c

linux 内核源代码

	memcpy(t, ct, sizeof(*ct));
	if (target->compat_from_user)
		target->compat_from_user(t->data, ct->data);
	else
		memcpy(t->data, ct->data, tsize - sizeof(*ct));
	pad = XT_ALIGN(target->targetsize) - target->targetsize;
	if (pad > 0)
		memset(t->data + target->targetsize, 0, pad);

	tsize += off;
	t->u.user.target_size = tsize;

	*size += off;
	*dstptr += tsize;
}
EXPORT_SYMBOL_GPL(xt_compat_target_from_user);

int xt_compat_target_to_user(struct xt_entry_target *t, void __user **dstptr,
			     int *size)
{
	struct xt_target *target = t->u.kernel.target;
	struct compat_xt_entry_target __user *ct = *dstptr;
	int off = xt_compat_target_offset(target);
	u_int16_t tsize = t->u.user.target_size - off;

	if (copy_to_user(ct, t, sizeof(*ct)) ||
	    put_user(tsize, &ct->u.user.target_size) ||
	    copy_to_user(ct->u.user.name, t->u.kernel.target->name,
			 strlen(t->u.kernel.target->name) + 1))
		return -EFAULT;

	if (target->compat_to_user) {
		if (target->compat_to_user((void __user *)ct->data, t->data))
			return -EFAULT;
	} else {
		if (copy_to_user(ct->data, t->data, tsize - sizeof(*ct)))
			return -EFAULT;
	}

	*size -= off;
	*dstptr += tsize;
	return 0;
}
EXPORT_SYMBOL_GPL(xt_compat_target_to_user);
#endif

struct xt_table_info *xt_alloc_table_info(unsigned int size)
{
	struct xt_table_info *newinfo;
	int cpu;

	/* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
	if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > num_physpages)
		return NULL;

	newinfo = kzalloc(sizeof(struct xt_table_info), GFP_KERNEL);
	if (!newinfo)
		return NULL;

	newinfo->size = size;

	for_each_possible_cpu(cpu) {
		if (size <= PAGE_SIZE)
			newinfo->entries[cpu] = kmalloc_node(size,
							GFP_KERNEL,
							cpu_to_node(cpu));
		else
			newinfo->entries[cpu] = vmalloc_node(size,
							cpu_to_node(cpu));

		if (newinfo->entries[cpu] == NULL) {
			xt_free_table_info(newinfo);
			return NULL;
		}
	}

	return newinfo;
}
EXPORT_SYMBOL(xt_alloc_table_info);

void xt_free_table_info(struct xt_table_info *info)
{
	int cpu;

	for_each_possible_cpu(cpu) {
		if (info->size <= PAGE_SIZE)
			kfree(info->entries[cpu]);
		else
			vfree(info->entries[cpu]);
	}
	kfree(info);
}
EXPORT_SYMBOL(xt_free_table_info);

/* Find table by name, grabs mutex & ref.  Returns ERR_PTR() on error. */
struct xt_table *xt_find_table_lock(int af, const char *name)
{
	struct xt_table *t;

	if (mutex_lock_interruptible(&xt[af].mutex) != 0)
		return ERR_PTR(-EINTR);

	list_for_each_entry(t, &xt[af].tables, list)
		if (strcmp(t->name, name) == 0 && try_module_get(t->me))
			return t;
	mutex_unlock(&xt[af].mutex);
	return NULL;
}
EXPORT_SYMBOL_GPL(xt_find_table_lock);

void xt_table_unlock(struct xt_table *table)
{
	mutex_unlock(&xt[table->af].mutex);
}
EXPORT_SYMBOL_GPL(xt_table_unlock);

#ifdef CONFIG_COMPAT
void xt_compat_lock(int af)
{
	mutex_lock(&xt[af].compat_mutex);
}
EXPORT_SYMBOL_GPL(xt_compat_lock);

void xt_compat_unlock(int af)
{
	mutex_unlock(&xt[af].compat_mutex);
}
EXPORT_SYMBOL_GPL(xt_compat_unlock);
#endif

struct xt_table_info *
xt_replace_table(struct xt_table *table,
	      unsigned int num_counters,
	      struct xt_table_info *newinfo,
	      int *error)
{
	struct xt_table_info *oldinfo, *private;

	/* Do the substitution. */
	write_lock_bh(&table->lock);
	private = table->private;
	/* Check inside lock: is the old number correct? */
	if (num_counters != private->number) {
		duprintf("num_counters != table->private->number (%u/%u)\n",
			 num_counters, private->number);
		write_unlock_bh(&table->lock);
		*error = -EAGAIN;
		return NULL;
	}
	oldinfo = private;
	table->private = newinfo;
	newinfo->initial_entries = oldinfo->initial_entries;
	write_unlock_bh(&table->lock);

	return oldinfo;
}
EXPORT_SYMBOL_GPL(xt_replace_table);

int xt_register_table(struct xt_table *table,
		      struct xt_table_info *bootstrap,
		      struct xt_table_info *newinfo)
{
	int ret;
	struct xt_table_info *private;
	struct xt_table *t;

	ret = mutex_lock_interruptible(&xt[table->af].mutex);
	if (ret != 0)
		return ret;

	/* Don't autoload: we'd eat our tail... */
	list_for_each_entry(t, &xt[table->af].tables, list) {
		if (strcmp(t->name, table->name) == 0) {
			ret = -EEXIST;
			goto unlock;
		}
	}

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

	private = table->private;
	duprintf("table->private->number = %u\n", private->number);

	/* save number of initial entries */
	private->initial_entries = private->number;

	list_add(&table->list, &xt[table->af].tables);

	ret = 0;
 unlock:
	mutex_unlock(&xt[table->af].mutex);
	return ret;
}
EXPORT_SYMBOL_GPL(xt_register_table);

void *xt_unregister_table(struct xt_table *table)
{
	struct xt_table_info *private;

	mutex_lock(&xt[table->af].mutex);
	private = table->private;
	list_del(&table->list);
	mutex_unlock(&xt[table->af].mutex);

	return private;
}
EXPORT_SYMBOL_GPL(xt_unregister_table);

#ifdef CONFIG_PROC_FS
static struct list_head *xt_get_idx(struct list_head *list, struct seq_file *seq, loff_t pos)
{
	struct list_head *head = list->next;

	if (!head || list_empty(list))
		return NULL;

	while (pos && (head = head->next)) {
		if (head == list)
			return NULL;
		pos--;
	}
	return pos ? NULL : head;
}

static struct list_head *type2list(u_int16_t af, u_int16_t type)
{
	struct list_head *list;

	switch (type) {
	case TARGET:
		list = &xt[af].target;
		break;
	case MATCH:
		list = &xt[af].match;
		break;
	case TABLE:
		list = &xt[af].tables;
		break;
	default:
		list = NULL;
		break;
	}

	return list;
}

static void *xt_tgt_seq_start(struct seq_file *seq, loff_t *pos)
{
	struct proc_dir_entry *pde = (struct proc_dir_entry *) seq->private;
	u_int16_t af = (unsigned long)pde->data & 0xffff;
	u_int16_t type = (unsigned long)pde->data >> 16;
	struct list_head *list;

	if (af >= NPROTO)
		return NULL;

	list = type2list(af, type);
	if (!list)
		return NULL;

	if (mutex_lock_interruptible(&xt[af].mutex) != 0)
		return NULL;

	return xt_get_idx(list, seq, *pos);
}

static void *xt_tgt_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct proc_dir_entry *pde = seq->private;
	u_int16_t af = (unsigned long)pde->data & 0xffff;
	u_int16_t type = (unsigned long)pde->data >> 16;
	struct list_head *list;

	if (af >= NPROTO)
		return NULL;

	list = type2list(af, type);
	if (!list)
		return NULL;

	(*pos)++;
	return xt_get_idx(list, seq, *pos);
}

static void xt_tgt_seq_stop(struct seq_file *seq, void *v)
{
	struct proc_dir_entry *pde = seq->private;
	u_int16_t af = (unsigned long)pde->data & 0xffff;

	mutex_unlock(&xt[af].mutex);
}

static int xt_name_seq_show(struct seq_file *seq, void *v)
{
	char *name = (char *)v + sizeof(struct list_head);

	if (strlen(name))
		return seq_printf(seq, "%s\n", name);
	else
		return 0;
}

static const struct seq_operations xt_tgt_seq_ops = {
	.start	= xt_tgt_seq_start,
	.next	= xt_tgt_seq_next,
	.stop	= xt_tgt_seq_stop,
	.show	= xt_name_seq_show,
};

static int xt_tgt_open(struct inode *inode, struct file *file)
{
	int ret;

	ret = seq_open(file, &xt_tgt_seq_ops);
	if (!ret) {
		struct seq_file *seq = file->private_data;
		struct proc_dir_entry *pde = PDE(inode);

		seq->private = pde;
	}

	return ret;
}

static const struct file_operations xt_file_ops = {
	.owner	 = THIS_MODULE,
	.open	 = xt_tgt_open,
	.read	 = seq_read,
	.llseek	 = seq_lseek,
	.release = seq_release,
};

#define FORMAT_TABLES	"_tables_names"
#define	FORMAT_MATCHES	"_tables_matches"
#define FORMAT_TARGETS 	"_tables_targets"

#endif /* CONFIG_PROC_FS */

int xt_proto_init(int af)
{
#ifdef CONFIG_PROC_FS
	char buf[XT_FUNCTION_MAXNAMELEN];
	struct proc_dir_entry *proc;
#endif

	if (af >= NPROTO)
		return -EINVAL;


#ifdef CONFIG_PROC_FS
	strlcpy(buf, xt_prefix[af], sizeof(buf));
	strlcat(buf, FORMAT_TABLES, sizeof(buf));
	proc = proc_net_fops_create(&init_net, buf, 0440, &xt_file_ops);
	if (!proc)
		goto out;
	proc->data = (void *) ((unsigned long) af | (TABLE << 16));


	strlcpy(buf, xt_prefix[af], sizeof(buf));
	strlcat(buf, FORMAT_MATCHES, sizeof(buf));
	proc = proc_net_fops_create(&init_net, buf, 0440, &xt_file_ops);
	if (!proc)
		goto out_remove_tables;
	proc->data = (void *) ((unsigned long) af | (MATCH << 16));

	strlcpy(buf, xt_prefix[af], sizeof(buf));
	strlcat(buf, FORMAT_TARGETS, sizeof(buf));
	proc = proc_net_fops_create(&init_net, buf, 0440, &xt_file_ops);
	if (!proc)
		goto out_remove_matches;
	proc->data = (void *) ((unsigned long) af | (TARGET << 16));
#endif

	return 0;

#ifdef CONFIG_PROC_FS
out_remove_matches:
	strlcpy(buf, xt_prefix[af], sizeof(buf));
	strlcat(buf, FORMAT_MATCHES, sizeof(buf));
	proc_net_remove(&init_net, buf);

out_remove_tables:
	strlcpy(buf, xt_prefix[af], sizeof(buf));
	strlcat(buf, FORMAT_TABLES, sizeof(buf));
	proc_net_remove(&init_net, buf);
out:
	return -1;
#endif
}
EXPORT_SYMBOL_GPL(xt_proto_init);

void xt_proto_fini(int af)
{
#ifdef CONFIG_PROC_FS
	char buf[XT_FUNCTION_MAXNAMELEN];

	strlcpy(buf, xt_prefix[af], sizeof(buf));
	strlcat(buf, FORMAT_TABLES, sizeof(buf));
	proc_net_remove(&init_net, buf);

	strlcpy(buf, xt_prefix[af], sizeof(buf));
	strlcat(buf, FORMAT_TARGETS, sizeof(buf));
	proc_net_remove(&init_net, buf);

	strlcpy(buf, xt_prefix[af], sizeof(buf));
	strlcat(buf, FORMAT_MATCHES, sizeof(buf));
	proc_net_remove(&init_net, buf);
#endif /*CONFIG_PROC_FS*/
}
EXPORT_SYMBOL_GPL(xt_proto_fini);


static int __init xt_init(void)
{
	int i;

	xt = kmalloc(sizeof(struct xt_af) * NPROTO, GFP_KERNEL);
	if (!xt)
		return -ENOMEM;

	for (i = 0; i < NPROTO; i++) {
		mutex_init(&xt[i].mutex);
#ifdef CONFIG_COMPAT
		mutex_init(&xt[i].compat_mutex);
#endif
		INIT_LIST_HEAD(&xt[i].target);
		INIT_LIST_HEAD(&xt[i].match);
		INIT_LIST_HEAD(&xt[i].tables);
	}
	return 0;
}

static void __exit xt_fini(void)
{
	kfree(xt);
}

module_init(xt_init);
module_exit(xt_fini);