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path: root/drivers/net/ppp/pppopns.c
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Diffstat (limited to 'drivers/net/ppp/pppopns.c')
-rw-r--r--drivers/net/ppp/pppopns.c428
1 files changed, 428 insertions, 0 deletions
diff --git a/drivers/net/ppp/pppopns.c b/drivers/net/ppp/pppopns.c
new file mode 100644
index 00000000000..6016d29c066
--- /dev/null
+++ b/drivers/net/ppp/pppopns.c
@@ -0,0 +1,428 @@
+/* drivers/net/pppopns.c
+ *
+ * Driver for PPP on PPTP Network Server / PPPoPNS Socket (RFC 2637)
+ *
+ * Copyright (C) 2009 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+/* This driver handles PPTP data packets between a RAW socket and a PPP channel.
+ * The socket is created in the kernel space and connected to the same address
+ * of the control socket. Outgoing packets are always sent with sequences but
+ * without acknowledgements. Incoming packets with sequences are reordered
+ * within a sliding window of one second. Currently reordering only happens when
+ * a packet is received. It is done for simplicity since no additional locks or
+ * threads are required. This driver should work on both IPv4 and IPv6. */
+
+#include <linux/module.h>
+#include <linux/jiffies.h>
+#include <linux/workqueue.h>
+#include <linux/skbuff.h>
+#include <linux/file.h>
+#include <linux/netdevice.h>
+#include <linux/net.h>
+#include <linux/ppp_defs.h>
+#include <linux/if.h>
+#include <linux/if_ppp.h>
+#include <linux/if_pppox.h>
+#include <linux/ppp_channel.h>
+#include <asm/uaccess.h>
+
+#define GRE_HEADER_SIZE 8
+
+#define PPTP_GRE_BITS htons(0x2001)
+#define PPTP_GRE_BITS_MASK htons(0xEF7F)
+#define PPTP_GRE_SEQ_BIT htons(0x1000)
+#define PPTP_GRE_ACK_BIT htons(0x0080)
+#define PPTP_GRE_TYPE htons(0x880B)
+
+#define PPP_ADDR 0xFF
+#define PPP_CTRL 0x03
+
+struct header {
+ __u16 bits;
+ __u16 type;
+ __u16 length;
+ __u16 call;
+ __u32 sequence;
+} __attribute__((packed));
+
+struct meta {
+ __u32 sequence;
+ __u32 timestamp;
+};
+
+static inline struct meta *skb_meta(struct sk_buff *skb)
+{
+ return (struct meta *)skb->cb;
+}
+
+/******************************************************************************/
+
+static int pppopns_recv_core(struct sock *sk_raw, struct sk_buff *skb)
+{
+ struct sock *sk = (struct sock *)sk_raw->sk_user_data;
+ struct pppopns_opt *opt = &pppox_sk(sk)->proto.pns;
+ struct meta *meta = skb_meta(skb);
+ __u32 now = jiffies;
+ struct header *hdr;
+
+ /* Skip transport header */
+ skb_pull(skb, skb_transport_header(skb) - skb->data);
+
+ /* Drop the packet if GRE header is missing. */
+ if (skb->len < GRE_HEADER_SIZE)
+ goto drop;
+ hdr = (struct header *)skb->data;
+
+ /* Check the header. */
+ if (hdr->type != PPTP_GRE_TYPE || hdr->call != opt->local ||
+ (hdr->bits & PPTP_GRE_BITS_MASK) != PPTP_GRE_BITS)
+ goto drop;
+
+ /* Skip all fields including optional ones. */
+ if (!skb_pull(skb, GRE_HEADER_SIZE +
+ (hdr->bits & PPTP_GRE_SEQ_BIT ? 4 : 0) +
+ (hdr->bits & PPTP_GRE_ACK_BIT ? 4 : 0)))
+ goto drop;
+
+ /* Check the length. */
+ if (skb->len != ntohs(hdr->length))
+ goto drop;
+
+ /* Check the sequence if it is present. */
+ if (hdr->bits & PPTP_GRE_SEQ_BIT) {
+ meta->sequence = ntohl(hdr->sequence);
+ if ((__s32)(meta->sequence - opt->recv_sequence) < 0)
+ goto drop;
+ }
+
+ /* Skip PPP address and control if they are present. */
+ if (skb->len >= 2 && skb->data[0] == PPP_ADDR &&
+ skb->data[1] == PPP_CTRL)
+ skb_pull(skb, 2);
+
+ /* Fix PPP protocol if it is compressed. */
+ if (skb->len >= 1 && skb->data[0] & 1)
+ skb_push(skb, 1)[0] = 0;
+
+ /* Drop the packet if PPP protocol is missing. */
+ if (skb->len < 2)
+ goto drop;
+
+ /* Perform reordering if sequencing is enabled. */
+ if (hdr->bits & PPTP_GRE_SEQ_BIT) {
+ struct sk_buff *skb1;
+
+ /* Insert the packet into receive queue in order. */
+ skb_set_owner_r(skb, sk);
+ skb_queue_walk(&sk->sk_receive_queue, skb1) {
+ struct meta *meta1 = skb_meta(skb1);
+ __s32 order = meta->sequence - meta1->sequence;
+ if (order == 0)
+ goto drop;
+ if (order < 0) {
+ meta->timestamp = meta1->timestamp;
+ skb_insert(skb1, skb, &sk->sk_receive_queue);
+ skb = NULL;
+ break;
+ }
+ }
+ if (skb) {
+ meta->timestamp = now;
+ skb_queue_tail(&sk->sk_receive_queue, skb);
+ }
+
+ /* Remove packets from receive queue as long as
+ * 1. the receive buffer is full,
+ * 2. they are queued longer than one second, or
+ * 3. there are no missing packets before them. */
+ skb_queue_walk_safe(&sk->sk_receive_queue, skb, skb1) {
+ meta = skb_meta(skb);
+ if (atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
+ now - meta->timestamp < HZ &&
+ meta->sequence != opt->recv_sequence)
+ break;
+ skb_unlink(skb, &sk->sk_receive_queue);
+ opt->recv_sequence = meta->sequence + 1;
+ skb_orphan(skb);
+ ppp_input(&pppox_sk(sk)->chan, skb);
+ }
+ return NET_RX_SUCCESS;
+ }
+
+ /* Flush receive queue if sequencing is disabled. */
+ skb_queue_purge(&sk->sk_receive_queue);
+ skb_orphan(skb);
+ ppp_input(&pppox_sk(sk)->chan, skb);
+ return NET_RX_SUCCESS;
+drop:
+ kfree_skb(skb);
+ return NET_RX_DROP;
+}
+
+static void pppopns_recv(struct sock *sk_raw, int length)
+{
+ struct sk_buff *skb;
+ while ((skb = skb_dequeue(&sk_raw->sk_receive_queue))) {
+ sock_hold(sk_raw);
+ sk_receive_skb(sk_raw, skb, 0);
+ }
+}
+
+static struct sk_buff_head delivery_queue;
+
+static void pppopns_xmit_core(struct work_struct *delivery_work)
+{
+ mm_segment_t old_fs = get_fs();
+ struct sk_buff *skb;
+
+ set_fs(KERNEL_DS);
+ while ((skb = skb_dequeue(&delivery_queue))) {
+ struct sock *sk_raw = skb->sk;
+ struct kvec iov = {.iov_base = skb->data, .iov_len = skb->len};
+ struct msghdr msg = {
+ .msg_iov = (struct iovec *)&iov,
+ .msg_iovlen = 1,
+ .msg_flags = MSG_NOSIGNAL | MSG_DONTWAIT,
+ };
+ sk_raw->sk_prot->sendmsg(NULL, sk_raw, &msg, skb->len);
+ kfree_skb(skb);
+ }
+ set_fs(old_fs);
+}
+
+static DECLARE_WORK(delivery_work, pppopns_xmit_core);
+
+static int pppopns_xmit(struct ppp_channel *chan, struct sk_buff *skb)
+{
+ struct sock *sk_raw = (struct sock *)chan->private;
+ struct pppopns_opt *opt = &pppox_sk(sk_raw->sk_user_data)->proto.pns;
+ struct header *hdr;
+ __u16 length;
+
+ /* Install PPP address and control. */
+ skb_push(skb, 2);
+ skb->data[0] = PPP_ADDR;
+ skb->data[1] = PPP_CTRL;
+ length = skb->len;
+
+ /* Install PPTP GRE header. */
+ hdr = (struct header *)skb_push(skb, 12);
+ hdr->bits = PPTP_GRE_BITS | PPTP_GRE_SEQ_BIT;
+ hdr->type = PPTP_GRE_TYPE;
+ hdr->length = htons(length);
+ hdr->call = opt->remote;
+ hdr->sequence = htonl(opt->xmit_sequence);
+ opt->xmit_sequence++;
+
+ /* Now send the packet via the delivery queue. */
+ skb_set_owner_w(skb, sk_raw);
+ skb_queue_tail(&delivery_queue, skb);
+ schedule_work(&delivery_work);
+ return 1;
+}
+
+/******************************************************************************/
+
+static struct ppp_channel_ops pppopns_channel_ops = {
+ .start_xmit = pppopns_xmit,
+};
+
+static int pppopns_connect(struct socket *sock, struct sockaddr *useraddr,
+ int addrlen, int flags)
+{
+ struct sock *sk = sock->sk;
+ struct pppox_sock *po = pppox_sk(sk);
+ struct sockaddr_pppopns *addr = (struct sockaddr_pppopns *)useraddr;
+ struct sockaddr_storage ss;
+ struct socket *sock_tcp = NULL;
+ struct socket *sock_raw = NULL;
+ struct sock *sk_tcp;
+ struct sock *sk_raw;
+ int error;
+
+ if (addrlen != sizeof(struct sockaddr_pppopns))
+ return -EINVAL;
+
+ lock_sock(sk);
+ error = -EALREADY;
+ if (sk->sk_state != PPPOX_NONE)
+ goto out;
+
+ sock_tcp = sockfd_lookup(addr->tcp_socket, &error);
+ if (!sock_tcp)
+ goto out;
+ sk_tcp = sock_tcp->sk;
+ error = -EPROTONOSUPPORT;
+ if (sk_tcp->sk_protocol != IPPROTO_TCP)
+ goto out;
+ addrlen = sizeof(struct sockaddr_storage);
+ error = kernel_getpeername(sock_tcp, (struct sockaddr *)&ss, &addrlen);
+ if (error)
+ goto out;
+ if (!sk_tcp->sk_bound_dev_if) {
+ struct dst_entry *dst = sk_dst_get(sk_tcp);
+ error = -ENODEV;
+ if (!dst)
+ goto out;
+ sk_tcp->sk_bound_dev_if = dst->dev->ifindex;
+ dst_release(dst);
+ }
+
+ error = sock_create(ss.ss_family, SOCK_RAW, IPPROTO_GRE, &sock_raw);
+ if (error)
+ goto out;
+ sk_raw = sock_raw->sk;
+ sk_raw->sk_bound_dev_if = sk_tcp->sk_bound_dev_if;
+ error = kernel_connect(sock_raw, (struct sockaddr *)&ss, addrlen, 0);
+ if (error)
+ goto out;
+
+ po->chan.hdrlen = 14;
+ po->chan.private = sk_raw;
+ po->chan.ops = &pppopns_channel_ops;
+ po->chan.mtu = PPP_MRU - 80;
+ po->proto.pns.local = addr->local;
+ po->proto.pns.remote = addr->remote;
+ po->proto.pns.data_ready = sk_raw->sk_data_ready;
+ po->proto.pns.backlog_rcv = sk_raw->sk_backlog_rcv;
+
+ error = ppp_register_channel(&po->chan);
+ if (error)
+ goto out;
+
+ sk->sk_state = PPPOX_CONNECTED;
+ lock_sock(sk_raw);
+ sk_raw->sk_data_ready = pppopns_recv;
+ sk_raw->sk_backlog_rcv = pppopns_recv_core;
+ sk_raw->sk_user_data = sk;
+ release_sock(sk_raw);
+out:
+ if (sock_tcp)
+ sockfd_put(sock_tcp);
+ if (error && sock_raw)
+ sock_release(sock_raw);
+ release_sock(sk);
+ return error;
+}
+
+static int pppopns_release(struct socket *sock)
+{
+ struct sock *sk = sock->sk;
+
+ if (!sk)
+ return 0;
+
+ lock_sock(sk);
+ if (sock_flag(sk, SOCK_DEAD)) {
+ release_sock(sk);
+ return -EBADF;
+ }
+
+ if (sk->sk_state != PPPOX_NONE) {
+ struct sock *sk_raw = (struct sock *)pppox_sk(sk)->chan.private;
+ lock_sock(sk_raw);
+ skb_queue_purge(&sk->sk_receive_queue);
+ pppox_unbind_sock(sk);
+ sk_raw->sk_data_ready = pppox_sk(sk)->proto.pns.data_ready;
+ sk_raw->sk_backlog_rcv = pppox_sk(sk)->proto.pns.backlog_rcv;
+ sk_raw->sk_user_data = NULL;
+ release_sock(sk_raw);
+ sock_release(sk_raw->sk_socket);
+ }
+
+ sock_orphan(sk);
+ sock->sk = NULL;
+ release_sock(sk);
+ sock_put(sk);
+ return 0;
+}
+
+/******************************************************************************/
+
+static struct proto pppopns_proto = {
+ .name = "PPPOPNS",
+ .owner = THIS_MODULE,
+ .obj_size = sizeof(struct pppox_sock),
+};
+
+static struct proto_ops pppopns_proto_ops = {
+ .family = PF_PPPOX,
+ .owner = THIS_MODULE,
+ .release = pppopns_release,
+ .bind = sock_no_bind,
+ .connect = pppopns_connect,
+ .socketpair = sock_no_socketpair,
+ .accept = sock_no_accept,
+ .getname = sock_no_getname,
+ .poll = sock_no_poll,
+ .ioctl = pppox_ioctl,
+ .listen = sock_no_listen,
+ .shutdown = sock_no_shutdown,
+ .setsockopt = sock_no_setsockopt,
+ .getsockopt = sock_no_getsockopt,
+ .sendmsg = sock_no_sendmsg,
+ .recvmsg = sock_no_recvmsg,
+ .mmap = sock_no_mmap,
+};
+
+static int pppopns_create(struct net *net, struct socket *sock)
+{
+ struct sock *sk;
+
+ sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pppopns_proto);
+ if (!sk)
+ return -ENOMEM;
+
+ sock_init_data(sock, sk);
+ sock->state = SS_UNCONNECTED;
+ sock->ops = &pppopns_proto_ops;
+ sk->sk_protocol = PX_PROTO_OPNS;
+ sk->sk_state = PPPOX_NONE;
+ return 0;
+}
+
+/******************************************************************************/
+
+static struct pppox_proto pppopns_pppox_proto = {
+ .create = pppopns_create,
+ .owner = THIS_MODULE,
+};
+
+static int __init pppopns_init(void)
+{
+ int error;
+
+ error = proto_register(&pppopns_proto, 0);
+ if (error)
+ return error;
+
+ error = register_pppox_proto(PX_PROTO_OPNS, &pppopns_pppox_proto);
+ if (error)
+ proto_unregister(&pppopns_proto);
+ else
+ skb_queue_head_init(&delivery_queue);
+ return error;
+}
+
+static void __exit pppopns_exit(void)
+{
+ unregister_pppox_proto(PX_PROTO_OPNS);
+ proto_unregister(&pppopns_proto);
+}
+
+module_init(pppopns_init);
+module_exit(pppopns_exit);
+
+MODULE_DESCRIPTION("PPP on PPTP Network Server (PPPoPNS)");
+MODULE_AUTHOR("Chia-chi Yeh <chiachi@android.com>");
+MODULE_LICENSE("GPL");