From 05c2828c72c4eabf62376adfe27bd24797621f62 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 14 Jan 2010 06:17:09 +0000 Subject: 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 Acked-by: Herbert Xu Acked-by: David S. Miller Signed-off-by: David S. Miller --- drivers/net/tun.c | 101 ++++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 82 insertions(+), 19 deletions(-) (limited to 'drivers/net/tun.c') diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 2834a01bae24..5adb3d150552 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -144,6 +144,7 @@ static int tun_attach(struct tun_struct *tun, struct file *file) err = 0; tfile->tun = tun; tun->tfile = tfile; + tun->socket.file = file; dev_hold(tun->dev); sock_hold(tun->socket.sk); atomic_inc(&tfile->count); @@ -158,6 +159,7 @@ static void __tun_detach(struct tun_struct *tun) /* Detach from net device */ netif_tx_lock_bh(tun->dev); tun->tfile = NULL; + tun->socket.file = NULL; netif_tx_unlock_bh(tun->dev); /* Drop read queue */ @@ -387,7 +389,8 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) /* Notify and wake up reader process */ if (tun->flags & TUN_FASYNC) kill_fasync(&tun->fasync, SIGIO, POLL_IN); - wake_up_interruptible(&tun->socket.wait); + wake_up_interruptible_poll(&tun->socket.wait, POLLIN | + POLLRDNORM | POLLRDBAND); return NETDEV_TX_OK; drop: @@ -743,7 +746,7 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun, len = min_t(int, skb->len, len); skb_copy_datagram_const_iovec(skb, 0, iv, total, len); - total += len; + total += skb->len; tun->dev->stats.tx_packets++; tun->dev->stats.tx_bytes += len; @@ -751,34 +754,23 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun, return total; } -static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv, - unsigned long count, loff_t pos) +static ssize_t tun_do_read(struct tun_struct *tun, + struct kiocb *iocb, const struct iovec *iv, + ssize_t len, int noblock) { - struct file *file = iocb->ki_filp; - struct tun_file *tfile = file->private_data; - struct tun_struct *tun = __tun_get(tfile); DECLARE_WAITQUEUE(wait, current); struct sk_buff *skb; - ssize_t len, ret = 0; - - if (!tun) - return -EBADFD; + ssize_t ret = 0; DBG(KERN_INFO "%s: tun_chr_read\n", tun->dev->name); - len = iov_length(iv, count); - if (len < 0) { - ret = -EINVAL; - goto out; - } - add_wait_queue(&tun->socket.wait, &wait); while (len) { current->state = TASK_INTERRUPTIBLE; /* Read frames from the queue */ if (!(skb=skb_dequeue(&tun->socket.sk->sk_receive_queue))) { - if (file->f_flags & O_NONBLOCK) { + if (noblock) { ret = -EAGAIN; break; } @@ -805,6 +797,27 @@ static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv, current->state = TASK_RUNNING; remove_wait_queue(&tun->socket.wait, &wait); + return ret; +} + +static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv, + unsigned long count, loff_t pos) +{ + struct file *file = iocb->ki_filp; + struct tun_file *tfile = file->private_data; + struct tun_struct *tun = __tun_get(tfile); + ssize_t len, ret; + + if (!tun) + return -EBADFD; + len = iov_length(iv, count); + if (len < 0) { + ret = -EINVAL; + goto out; + } + + ret = tun_do_read(tun, iocb, iv, len, file->f_flags & O_NONBLOCK); + ret = min_t(ssize_t, ret, len); out: tun_put(tun); return ret; @@ -847,7 +860,8 @@ static void tun_sock_write_space(struct sock *sk) return; if (sk->sk_sleep && waitqueue_active(sk->sk_sleep)) - wake_up_interruptible_sync(sk->sk_sleep); + wake_up_interruptible_sync_poll(sk->sk_sleep, POLLOUT | + POLLWRNORM | POLLWRBAND); tun = tun_sk(sk)->tun; kill_fasync(&tun->fasync, SIGIO, POLL_OUT); @@ -858,6 +872,37 @@ static void tun_sock_destruct(struct sock *sk) free_netdev(tun_sk(sk)->tun->dev); } +static int tun_sendmsg(struct kiocb *iocb, struct socket *sock, + struct msghdr *m, size_t total_len) +{ + struct tun_struct *tun = container_of(sock, struct tun_struct, socket); + return tun_get_user(tun, m->msg_iov, total_len, + m->msg_flags & MSG_DONTWAIT); +} + +static int tun_recvmsg(struct kiocb *iocb, struct socket *sock, + struct msghdr *m, size_t total_len, + int flags) +{ + struct tun_struct *tun = container_of(sock, struct tun_struct, socket); + int ret; + if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) + return -EINVAL; + ret = tun_do_read(tun, iocb, m->msg_iov, total_len, + flags & MSG_DONTWAIT); + if (ret > total_len) { + m->msg_flags |= MSG_TRUNC; + ret = flags & MSG_TRUNC ? ret : total_len; + } + return ret; +} + +/* Ops structure to mimic raw sockets with tun */ +static const struct proto_ops tun_socket_ops = { + .sendmsg = tun_sendmsg, + .recvmsg = tun_recvmsg, +}; + static struct proto tun_proto = { .name = "tun", .owner = THIS_MODULE, @@ -986,6 +1031,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) goto err_free_dev; init_waitqueue_head(&tun->socket.wait); + tun->socket.ops = &tun_socket_ops; sock_init_data(&tun->socket, sk); sk->sk_write_space = tun_sock_write_space; sk->sk_sndbuf = INT_MAX; @@ -1525,6 +1571,23 @@ static void tun_cleanup(void) rtnl_link_unregister(&tun_link_ops); } +/* Get an underlying socket object from tun file. Returns error unless file is + * attached to a device. The returned object works like a packet socket, it + * can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for + * holding a reference to the file for as long as the socket is in use. */ +struct socket *tun_get_socket(struct file *file) +{ + struct tun_struct *tun; + if (file->f_op != &tun_fops) + return ERR_PTR(-EINVAL); + tun = tun_get(file); + if (!tun) + return ERR_PTR(-EBADFD); + tun_put(tun); + return &tun->socket; +} +EXPORT_SYMBOL_GPL(tun_get_socket); + module_init(tun_init); module_exit(tun_cleanup); MODULE_DESCRIPTION(DRV_DESCRIPTION); -- cgit v1.2.3