--- /dev/null
+/* drivers/net/pppopns.c
+ *
+ * Driver for PPP on PPTP Network Server / PPPoPNS Socket (RFC 2637)
+ *
+ * Copyright (C) 2009 Google, Inc.
+ * Author: Chia-chi Yeh <chiachi@android.com>
+ *
+ * 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. To keep things simple, packets are always sent with
+ * sequence but without acknowledgement. This driver should work on both IPv4
+ * and IPv6. */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/file.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>
+
+#define GRE_HEADER_SIZE 8
+
+#define PPTP_GRE_MASK htons(0x2001)
+#define PPTP_GRE_SEQ_MASK htons(0x1000)
+#define PPTP_GRE_ACK_MASK 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));
+
+static void pppopns_recv(struct sock *sk_raw, int length)
+{
+ struct sock *sk;
+ struct pppopns_opt *opt;
+ struct sk_buff *skb;
+ struct header *hdr;
+
+ /* Lock sk_raw to prevent sk from being closed. */
+ lock_sock(sk_raw);
+ sk = (struct sock *)sk_raw->sk_user_data;
+ if (!sk) {
+ release_sock(sk_raw);
+ return;
+ }
+ sock_hold(sk);
+ release_sock(sk_raw);
+ opt = &pppox_sk(sk)->proto.pns;
+
+ /* Process packets from the receive queue. */
+ while ((skb = skb_dequeue(&sk_raw->sk_receive_queue))) {
+ skb_pull(skb, skb_transport_header(skb) - skb->data);
+
+ /* Drop the packet if it is too short. */
+ if (skb->len < GRE_HEADER_SIZE)
+ goto drop;
+
+ /* Check the header. */
+ hdr = (struct header *)skb->data;
+ if (hdr->type != PPTP_GRE_TYPE || hdr->call != opt->local ||
+ (hdr->bits & PPTP_GRE_MASK) != PPTP_GRE_MASK)
+ goto drop;
+
+ /* Skip all fields including optional ones. */
+ if (!skb_pull(skb, GRE_HEADER_SIZE +
+ (hdr->bits & PPTP_GRE_SEQ_MASK ? 4 : 0) +
+ (hdr->bits & PPTP_GRE_ACK_MASK ? 4 : 0)))
+ goto drop;
+
+ /* Check the length. */
+ if (skb->len != ntohs(hdr->length))
+ 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;
+
+ /* Deliver the packet to PPP channel. We have to lock sk to
+ * prevent another thread from calling pppox_unbind_sock(). */
+ skb_orphan(skb);
+ lock_sock(sk);
+ ppp_input(&pppox_sk(sk)->chan, skb);
+ release_sock(sk);
+ continue;
+drop:
+ kfree_skb(skb);
+ }
+ sock_put(sk);
+}
+
+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 msghdr msg = {.msg_flags = MSG_NOSIGNAL | MSG_DONTWAIT};
+ struct kvec iov;
+ 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_MASK | PPTP_GRE_SEQ_MASK;
+ hdr->type = PPTP_GRE_TYPE;
+ hdr->length = htons(length);
+ hdr->call = opt->remote;
+ hdr->sequence = htonl(opt->sequence);
+ opt->sequence++;
+
+ /* Now send the packet via RAW socket. */
+ iov.iov_base = skb->data;
+ iov.iov_len = skb->len;
+ kernel_sendmsg(sk_raw->sk_socket, &msg, &iov, 1, skb->len);
+ kfree_skb(skb);
+ 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_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;
+ error = -EPROTONOSUPPORT;
+ if (sock_tcp->sk->sk_protocol != IPPROTO_TCP)
+ goto out;
+ addrlen = sizeof(struct sockaddr_storage);
+ error = kernel_getpeername(sock_tcp, (struct sockaddr *)&ss, &addrlen);
+ if (error)
+ goto out;
+
+ error = sock_create(ss.ss_family, SOCK_RAW, IPPROTO_GRE, &sock_raw);
+ if (error)
+ goto out;
+ error = kernel_connect(sock_raw, (struct sockaddr *)&ss, addrlen, 0);
+ if (error)
+ goto out;
+ sk_raw = sock_raw->sk;
+
+ po->chan.hdrlen = 14;
+ po->chan.private = sk_raw;
+ po->chan.ops = &pppopns_channel_ops;
+ po->chan.mtu = PPP_MTU - 80;
+ po->proto.pns.local = addr->local;
+ po->proto.pns.remote = addr->remote;
+
+ error = ppp_register_channel(&po->chan);
+ if (error)
+ goto out;
+
+ sk->sk_state = PPPOX_CONNECTED;
+ sk_raw->sk_user_data = sk;
+ sk_raw->sk_data_ready = pppopns_recv;
+
+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);
+ pppox_unbind_sock(sk);
+ 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);
+ 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");
projects / firefly-linux-kernel-4.4.55.git / commitdiff