tun: export underlying socket
Tun device looks similar to a packet socket in that both pass complete frames from/to userspace. This patch fills in enough fields in the socket underlying tun driver to support sendmsg/recvmsg operations, and message flags MSG_TRUNC and MSG_DONTWAIT, and exports access to this socket to modules. Regular read/write behaviour is unchanged. This way, code using raw sockets to inject packets into a physical device, can support injecting packets into host network stack almost without modification. First user of this interface will be vhost virtualization accelerator. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael S. Tsirkin
David S. Miller
Родитель
ad72c347e5
Коммит
05c2828c72
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@ -144,6 +144,7 @@ static int tun_attach(struct tun_struct *tun, struct file *file)
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err = 0;
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tfile->tun = tun;
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tun->tfile = tfile;
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tun->socket.file = file;
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dev_hold(tun->dev);
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sock_hold(tun->socket.sk);
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atomic_inc(&tfile->count);
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@ -158,6 +159,7 @@ static void __tun_detach(struct tun_struct *tun)
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/* Detach from net device */
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netif_tx_lock_bh(tun->dev);
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tun->tfile = NULL;
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tun->socket.file = NULL;
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netif_tx_unlock_bh(tun->dev);
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/* Drop read queue */
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@ -387,7 +389,8 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
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/* Notify and wake up reader process */
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if (tun->flags & TUN_FASYNC)
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kill_fasync(&tun->fasync, SIGIO, POLL_IN);
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wake_up_interruptible(&tun->socket.wait);
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wake_up_interruptible_poll(&tun->socket.wait, POLLIN |
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POLLRDNORM | POLLRDBAND);
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return NETDEV_TX_OK;
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drop:
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@ -743,7 +746,7 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
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len = min_t(int, skb->len, len);
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skb_copy_datagram_const_iovec(skb, 0, iv, total, len);
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total += len;
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total += skb->len;
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tun->dev->stats.tx_packets++;
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tun->dev->stats.tx_bytes += len;
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@ -751,34 +754,23 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
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return total;
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}
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static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
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unsigned long count, loff_t pos)
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static ssize_t tun_do_read(struct tun_struct *tun,
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struct kiocb *iocb, const struct iovec *iv,
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ssize_t len, int noblock)
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{
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struct file *file = iocb->ki_filp;
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struct tun_file *tfile = file->private_data;
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struct tun_struct *tun = __tun_get(tfile);
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DECLARE_WAITQUEUE(wait, current);
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struct sk_buff *skb;
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ssize_t len, ret = 0;
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if (!tun)
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return -EBADFD;
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ssize_t ret = 0;
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DBG(KERN_INFO "%s: tun_chr_read\n", tun->dev->name);
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len = iov_length(iv, count);
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if (len < 0) {
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ret = -EINVAL;
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goto out;
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}
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add_wait_queue(&tun->socket.wait, &wait);
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while (len) {
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current->state = TASK_INTERRUPTIBLE;
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/* Read frames from the queue */
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if (!(skb=skb_dequeue(&tun->socket.sk->sk_receive_queue))) {
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if (file->f_flags & O_NONBLOCK) {
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if (noblock) {
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ret = -EAGAIN;
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break;
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}
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@ -805,6 +797,27 @@ static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
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current->state = TASK_RUNNING;
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remove_wait_queue(&tun->socket.wait, &wait);
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return ret;
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}
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static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
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unsigned long count, loff_t pos)
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{
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struct file *file = iocb->ki_filp;
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struct tun_file *tfile = file->private_data;
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struct tun_struct *tun = __tun_get(tfile);
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ssize_t len, ret;
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if (!tun)
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return -EBADFD;
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len = iov_length(iv, count);
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if (len < 0) {
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ret = -EINVAL;
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goto out;
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}
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ret = tun_do_read(tun, iocb, iv, len, file->f_flags & O_NONBLOCK);
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ret = min_t(ssize_t, ret, len);
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out:
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tun_put(tun);
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return ret;
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@ -847,7 +860,8 @@ static void tun_sock_write_space(struct sock *sk)
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return;
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if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
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wake_up_interruptible_sync(sk->sk_sleep);
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wake_up_interruptible_sync_poll(sk->sk_sleep, POLLOUT |
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POLLWRNORM | POLLWRBAND);
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tun = tun_sk(sk)->tun;
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kill_fasync(&tun->fasync, SIGIO, POLL_OUT);
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@ -858,6 +872,37 @@ static void tun_sock_destruct(struct sock *sk)
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free_netdev(tun_sk(sk)->tun->dev);
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}
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static int tun_sendmsg(struct kiocb *iocb, struct socket *sock,
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struct msghdr *m, size_t total_len)
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{
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struct tun_struct *tun = container_of(sock, struct tun_struct, socket);
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return tun_get_user(tun, m->msg_iov, total_len,
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m->msg_flags & MSG_DONTWAIT);
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}
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static int tun_recvmsg(struct kiocb *iocb, struct socket *sock,
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struct msghdr *m, size_t total_len,
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int flags)
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{
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struct tun_struct *tun = container_of(sock, struct tun_struct, socket);
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int ret;
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if (flags & ~(MSG_DONTWAIT|MSG_TRUNC))
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return -EINVAL;
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ret = tun_do_read(tun, iocb, m->msg_iov, total_len,
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flags & MSG_DONTWAIT);
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if (ret > total_len) {
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m->msg_flags |= MSG_TRUNC;
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ret = flags & MSG_TRUNC ? ret : total_len;
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}
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return ret;
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}
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/* Ops structure to mimic raw sockets with tun */
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static const struct proto_ops tun_socket_ops = {
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.sendmsg = tun_sendmsg,
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.recvmsg = tun_recvmsg,
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};
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static struct proto tun_proto = {
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.name = "tun",
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.owner = THIS_MODULE,
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@ -986,6 +1031,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
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goto err_free_dev;
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init_waitqueue_head(&tun->socket.wait);
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tun->socket.ops = &tun_socket_ops;
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sock_init_data(&tun->socket, sk);
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sk->sk_write_space = tun_sock_write_space;
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sk->sk_sndbuf = INT_MAX;
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@ -1525,6 +1571,23 @@ static void tun_cleanup(void)
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rtnl_link_unregister(&tun_link_ops);
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}
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/* Get an underlying socket object from tun file. Returns error unless file is
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* attached to a device. The returned object works like a packet socket, it
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* can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for
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* holding a reference to the file for as long as the socket is in use. */
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struct socket *tun_get_socket(struct file *file)
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{
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struct tun_struct *tun;
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if (file->f_op != &tun_fops)
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return ERR_PTR(-EINVAL);
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tun = tun_get(file);
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if (!tun)
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return ERR_PTR(-EBADFD);
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tun_put(tun);
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return &tun->socket;
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}
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EXPORT_SYMBOL_GPL(tun_get_socket);
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module_init(tun_init);
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module_exit(tun_cleanup);
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MODULE_DESCRIPTION(DRV_DESCRIPTION);
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@ -86,4 +86,18 @@ struct tun_filter {
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__u8 addr[0][ETH_ALEN];
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};
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#ifdef __KERNEL__
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#if defined(CONFIG_TUN) || defined(CONFIG_TUN_MODULE)
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struct socket *tun_get_socket(struct file *);
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#else
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#include <linux/err.h>
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#include <linux/errno.h>
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struct file;
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struct socket;
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static inline struct socket *tun_get_socket(struct file *f)
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{
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return ERR_PTR(-EINVAL);
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}
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#endif /* CONFIG_TUN */
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#endif /* __KERNEL__ */
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#endif /* __IF_TUN_H */
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