/*
|
* Point-to-Point Tunneling Protocol for Linux
|
*
|
* Authors: Dmitry Kozlov <xeb@mail.ru>
|
*
|
* This program is free software; you can redistribute it and/or
|
* modify it under the terms of the GNU General Public License
|
* as published by the Free Software Foundation; either version
|
* 2 of the License, or (at your option) any later version.
|
*
|
*/
|
|
#include <linux/string.h>
|
#include <linux/module.h>
|
#include <linux/kernel.h>
|
#include <linux/slab.h>
|
#include <linux/errno.h>
|
#include <linux/netdevice.h>
|
#include <linux/net.h>
|
#include <linux/skbuff.h>
|
#include <linux/vmalloc.h>
|
#include <linux/init.h>
|
#include <linux/ppp_channel.h>
|
#include <linux/ppp_defs.h>
|
#include <linux/if_pppox.h>
|
#include <linux/ppp-ioctl.h>
|
#include <linux/notifier.h>
|
#include <linux/file.h>
|
#include <linux/in.h>
|
#include <linux/ip.h>
|
#include <linux/rcupdate.h>
|
#include <linux/spinlock.h>
|
|
#include <net/sock.h>
|
#include <net/protocol.h>
|
#include <net/ip.h>
|
#include <net/icmp.h>
|
#include <net/route.h>
|
#include <net/gre.h>
|
#include <net/pptp.h>
|
|
#include <linux/uaccess.h>
|
|
#define PPTP_DRIVER_VERSION "0.8.5"
|
|
#define MAX_CALLID 65535
|
|
static DECLARE_BITMAP(callid_bitmap, MAX_CALLID + 1);
|
static struct pppox_sock __rcu **callid_sock;
|
|
static DEFINE_SPINLOCK(chan_lock);
|
|
static struct proto pptp_sk_proto __read_mostly;
|
static const struct ppp_channel_ops pptp_chan_ops;
|
static const struct proto_ops pptp_ops;
|
|
static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
|
{
|
struct pppox_sock *sock;
|
struct pptp_opt *opt;
|
|
rcu_read_lock();
|
sock = rcu_dereference(callid_sock[call_id]);
|
if (sock) {
|
opt = &sock->proto.pptp;
|
if (opt->dst_addr.sin_addr.s_addr != s_addr)
|
sock = NULL;
|
else
|
sock_hold(sk_pppox(sock));
|
}
|
rcu_read_unlock();
|
|
return sock;
|
}
|
|
static int lookup_chan_dst(u16 call_id, __be32 d_addr)
|
{
|
struct pppox_sock *sock;
|
struct pptp_opt *opt;
|
int i;
|
|
rcu_read_lock();
|
i = 1;
|
for_each_set_bit_from(i, callid_bitmap, MAX_CALLID) {
|
sock = rcu_dereference(callid_sock[i]);
|
if (!sock)
|
continue;
|
opt = &sock->proto.pptp;
|
if (opt->dst_addr.call_id == call_id &&
|
opt->dst_addr.sin_addr.s_addr == d_addr)
|
break;
|
}
|
rcu_read_unlock();
|
|
return i < MAX_CALLID;
|
}
|
|
static int add_chan(struct pppox_sock *sock,
|
struct pptp_addr *sa)
|
{
|
static int call_id;
|
|
spin_lock(&chan_lock);
|
if (!sa->call_id) {
|
call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
|
if (call_id == MAX_CALLID) {
|
call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
|
if (call_id == MAX_CALLID)
|
goto out_err;
|
}
|
sa->call_id = call_id;
|
} else if (test_bit(sa->call_id, callid_bitmap)) {
|
goto out_err;
|
}
|
|
sock->proto.pptp.src_addr = *sa;
|
set_bit(sa->call_id, callid_bitmap);
|
rcu_assign_pointer(callid_sock[sa->call_id], sock);
|
spin_unlock(&chan_lock);
|
|
return 0;
|
|
out_err:
|
spin_unlock(&chan_lock);
|
return -1;
|
}
|
|
static void del_chan(struct pppox_sock *sock)
|
{
|
spin_lock(&chan_lock);
|
clear_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
|
RCU_INIT_POINTER(callid_sock[sock->proto.pptp.src_addr.call_id], NULL);
|
spin_unlock(&chan_lock);
|
}
|
|
static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
|
{
|
struct sock *sk = (struct sock *) chan->private;
|
struct pppox_sock *po = pppox_sk(sk);
|
struct net *net = sock_net(sk);
|
struct pptp_opt *opt = &po->proto.pptp;
|
struct pptp_gre_header *hdr;
|
unsigned int header_len = sizeof(*hdr);
|
struct flowi4 fl4;
|
int islcp;
|
int len;
|
unsigned char *data;
|
__u32 seq_recv;
|
|
|
struct rtable *rt;
|
struct net_device *tdev;
|
struct iphdr *iph;
|
int max_headroom;
|
|
if (sk_pppox(po)->sk_state & PPPOX_DEAD)
|
goto tx_error;
|
|
rt = ip_route_output_ports(net, &fl4, NULL,
|
opt->dst_addr.sin_addr.s_addr,
|
opt->src_addr.sin_addr.s_addr,
|
0, 0, IPPROTO_GRE,
|
RT_TOS(0), 0);
|
if (IS_ERR(rt))
|
goto tx_error;
|
|
tdev = rt->dst.dev;
|
|
max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(*iph) + sizeof(*hdr) + 2;
|
|
if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
|
struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
|
if (!new_skb) {
|
ip_rt_put(rt);
|
goto tx_error;
|
}
|
if (skb->sk)
|
skb_set_owner_w(new_skb, skb->sk);
|
consume_skb(skb);
|
skb = new_skb;
|
}
|
|
data = skb->data;
|
islcp = ((data[0] << 8) + data[1]) == PPP_LCP && 1 <= data[2] && data[2] <= 7;
|
|
/* compress protocol field */
|
if ((opt->ppp_flags & SC_COMP_PROT) && data[0] == 0 && !islcp)
|
skb_pull(skb, 1);
|
|
/* Put in the address/control bytes if necessary */
|
if ((opt->ppp_flags & SC_COMP_AC) == 0 || islcp) {
|
data = skb_push(skb, 2);
|
data[0] = PPP_ALLSTATIONS;
|
data[1] = PPP_UI;
|
}
|
|
len = skb->len;
|
|
seq_recv = opt->seq_recv;
|
|
if (opt->ack_sent == seq_recv)
|
header_len -= sizeof(hdr->ack);
|
|
/* Push down and install GRE header */
|
skb_push(skb, header_len);
|
hdr = (struct pptp_gre_header *)(skb->data);
|
|
hdr->gre_hd.flags = GRE_KEY | GRE_VERSION_1 | GRE_SEQ;
|
hdr->gre_hd.protocol = GRE_PROTO_PPP;
|
hdr->call_id = htons(opt->dst_addr.call_id);
|
|
hdr->seq = htonl(++opt->seq_sent);
|
if (opt->ack_sent != seq_recv) {
|
/* send ack with this message */
|
hdr->gre_hd.flags |= GRE_ACK;
|
hdr->ack = htonl(seq_recv);
|
opt->ack_sent = seq_recv;
|
}
|
hdr->payload_len = htons(len);
|
|
/* Push down and install the IP header. */
|
|
skb_reset_transport_header(skb);
|
skb_push(skb, sizeof(*iph));
|
skb_reset_network_header(skb);
|
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
|
IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
|
|
iph = ip_hdr(skb);
|
iph->version = 4;
|
iph->ihl = sizeof(struct iphdr) >> 2;
|
if (ip_dont_fragment(sk, &rt->dst))
|
iph->frag_off = htons(IP_DF);
|
else
|
iph->frag_off = 0;
|
iph->protocol = IPPROTO_GRE;
|
iph->tos = 0;
|
iph->daddr = fl4.daddr;
|
iph->saddr = fl4.saddr;
|
iph->ttl = ip4_dst_hoplimit(&rt->dst);
|
iph->tot_len = htons(skb->len);
|
|
skb_dst_drop(skb);
|
skb_dst_set(skb, &rt->dst);
|
|
nf_reset(skb);
|
|
skb->ip_summed = CHECKSUM_NONE;
|
ip_select_ident(net, skb, NULL);
|
ip_send_check(iph);
|
|
ip_local_out(net, skb->sk, skb);
|
return 1;
|
|
tx_error:
|
kfree_skb(skb);
|
return 1;
|
}
|
|
static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
|
{
|
struct pppox_sock *po = pppox_sk(sk);
|
struct pptp_opt *opt = &po->proto.pptp;
|
int headersize, payload_len, seq;
|
__u8 *payload;
|
struct pptp_gre_header *header;
|
|
if (!(sk->sk_state & PPPOX_CONNECTED)) {
|
if (sock_queue_rcv_skb(sk, skb))
|
goto drop;
|
return NET_RX_SUCCESS;
|
}
|
|
header = (struct pptp_gre_header *)(skb->data);
|
headersize = sizeof(*header);
|
|
/* test if acknowledgement present */
|
if (GRE_IS_ACK(header->gre_hd.flags)) {
|
__u32 ack;
|
|
if (!pskb_may_pull(skb, headersize))
|
goto drop;
|
header = (struct pptp_gre_header *)(skb->data);
|
|
/* ack in different place if S = 0 */
|
ack = GRE_IS_SEQ(header->gre_hd.flags) ? header->ack : header->seq;
|
|
ack = ntohl(ack);
|
|
if (ack > opt->ack_recv)
|
opt->ack_recv = ack;
|
/* also handle sequence number wrap-around */
|
if (WRAPPED(ack, opt->ack_recv))
|
opt->ack_recv = ack;
|
} else {
|
headersize -= sizeof(header->ack);
|
}
|
/* test if payload present */
|
if (!GRE_IS_SEQ(header->gre_hd.flags))
|
goto drop;
|
|
payload_len = ntohs(header->payload_len);
|
seq = ntohl(header->seq);
|
|
/* check for incomplete packet (length smaller than expected) */
|
if (!pskb_may_pull(skb, headersize + payload_len))
|
goto drop;
|
|
payload = skb->data + headersize;
|
/* check for expected sequence number */
|
if (seq < opt->seq_recv + 1 || WRAPPED(opt->seq_recv, seq)) {
|
if ((payload[0] == PPP_ALLSTATIONS) && (payload[1] == PPP_UI) &&
|
(PPP_PROTOCOL(payload) == PPP_LCP) &&
|
((payload[4] == PPP_LCP_ECHOREQ) || (payload[4] == PPP_LCP_ECHOREP)))
|
goto allow_packet;
|
} else {
|
opt->seq_recv = seq;
|
allow_packet:
|
skb_pull(skb, headersize);
|
|
if (payload[0] == PPP_ALLSTATIONS && payload[1] == PPP_UI) {
|
/* chop off address/control */
|
if (skb->len < 3)
|
goto drop;
|
skb_pull(skb, 2);
|
}
|
|
skb->ip_summed = CHECKSUM_NONE;
|
skb_set_network_header(skb, skb->head-skb->data);
|
ppp_input(&po->chan, skb);
|
|
return NET_RX_SUCCESS;
|
}
|
drop:
|
kfree_skb(skb);
|
return NET_RX_DROP;
|
}
|
|
static int pptp_rcv(struct sk_buff *skb)
|
{
|
struct pppox_sock *po;
|
struct pptp_gre_header *header;
|
struct iphdr *iph;
|
|
if (skb->pkt_type != PACKET_HOST)
|
goto drop;
|
|
if (!pskb_may_pull(skb, 12))
|
goto drop;
|
|
iph = ip_hdr(skb);
|
|
header = (struct pptp_gre_header *)skb->data;
|
|
if (header->gre_hd.protocol != GRE_PROTO_PPP || /* PPTP-GRE protocol for PPTP */
|
GRE_IS_CSUM(header->gre_hd.flags) || /* flag CSUM should be clear */
|
GRE_IS_ROUTING(header->gre_hd.flags) || /* flag ROUTING should be clear */
|
!GRE_IS_KEY(header->gre_hd.flags) || /* flag KEY should be set */
|
(header->gre_hd.flags & GRE_FLAGS)) /* flag Recursion Ctrl should be clear */
|
/* if invalid, discard this packet */
|
goto drop;
|
|
po = lookup_chan(htons(header->call_id), iph->saddr);
|
if (po) {
|
skb_dst_drop(skb);
|
nf_reset(skb);
|
return sk_receive_skb(sk_pppox(po), skb, 0);
|
}
|
drop:
|
kfree_skb(skb);
|
return NET_RX_DROP;
|
}
|
|
static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
|
int sockaddr_len)
|
{
|
struct sock *sk = sock->sk;
|
struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
|
struct pppox_sock *po = pppox_sk(sk);
|
int error = 0;
|
|
if (sockaddr_len < sizeof(struct sockaddr_pppox))
|
return -EINVAL;
|
|
lock_sock(sk);
|
|
if (sk->sk_state & PPPOX_DEAD) {
|
error = -EALREADY;
|
goto out;
|
}
|
|
if (sk->sk_state & PPPOX_BOUND) {
|
error = -EBUSY;
|
goto out;
|
}
|
|
if (add_chan(po, &sp->sa_addr.pptp))
|
error = -EBUSY;
|
else
|
sk->sk_state |= PPPOX_BOUND;
|
|
out:
|
release_sock(sk);
|
return error;
|
}
|
|
static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
|
int sockaddr_len, int flags)
|
{
|
struct sock *sk = sock->sk;
|
struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
|
struct pppox_sock *po = pppox_sk(sk);
|
struct pptp_opt *opt = &po->proto.pptp;
|
struct rtable *rt;
|
struct flowi4 fl4;
|
int error = 0;
|
|
if (sockaddr_len < sizeof(struct sockaddr_pppox))
|
return -EINVAL;
|
|
if (sp->sa_protocol != PX_PROTO_PPTP)
|
return -EINVAL;
|
|
if (lookup_chan_dst(sp->sa_addr.pptp.call_id, sp->sa_addr.pptp.sin_addr.s_addr))
|
return -EALREADY;
|
|
lock_sock(sk);
|
/* Check for already bound sockets */
|
if (sk->sk_state & PPPOX_CONNECTED) {
|
error = -EBUSY;
|
goto end;
|
}
|
|
/* Check for already disconnected sockets, on attempts to disconnect */
|
if (sk->sk_state & PPPOX_DEAD) {
|
error = -EALREADY;
|
goto end;
|
}
|
|
if (!opt->src_addr.sin_addr.s_addr || !sp->sa_addr.pptp.sin_addr.s_addr) {
|
error = -EINVAL;
|
goto end;
|
}
|
|
po->chan.private = sk;
|
po->chan.ops = &pptp_chan_ops;
|
|
rt = ip_route_output_ports(sock_net(sk), &fl4, sk,
|
opt->dst_addr.sin_addr.s_addr,
|
opt->src_addr.sin_addr.s_addr,
|
0, 0,
|
IPPROTO_GRE, RT_CONN_FLAGS(sk), 0);
|
if (IS_ERR(rt)) {
|
error = -EHOSTUNREACH;
|
goto end;
|
}
|
sk_setup_caps(sk, &rt->dst);
|
|
po->chan.mtu = dst_mtu(&rt->dst);
|
if (!po->chan.mtu)
|
po->chan.mtu = PPP_MRU;
|
po->chan.mtu -= PPTP_HEADER_OVERHEAD;
|
|
po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
|
error = ppp_register_channel(&po->chan);
|
if (error) {
|
pr_err("PPTP: failed to register PPP channel (%d)\n", error);
|
goto end;
|
}
|
|
opt->dst_addr = sp->sa_addr.pptp;
|
sk->sk_state |= PPPOX_CONNECTED;
|
|
end:
|
release_sock(sk);
|
return error;
|
}
|
|
static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
|
int peer)
|
{
|
int len = sizeof(struct sockaddr_pppox);
|
struct sockaddr_pppox sp;
|
|
memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
|
|
sp.sa_family = AF_PPPOX;
|
sp.sa_protocol = PX_PROTO_PPTP;
|
sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;
|
|
memcpy(uaddr, &sp, len);
|
|
return len;
|
}
|
|
static int pptp_release(struct socket *sock)
|
{
|
struct sock *sk = sock->sk;
|
struct pppox_sock *po;
|
int error = 0;
|
|
if (!sk)
|
return 0;
|
|
lock_sock(sk);
|
|
if (sock_flag(sk, SOCK_DEAD)) {
|
release_sock(sk);
|
return -EBADF;
|
}
|
|
po = pppox_sk(sk);
|
del_chan(po);
|
synchronize_rcu();
|
|
pppox_unbind_sock(sk);
|
sk->sk_state = PPPOX_DEAD;
|
|
sock_orphan(sk);
|
sock->sk = NULL;
|
|
release_sock(sk);
|
sock_put(sk);
|
|
return error;
|
}
|
|
static void pptp_sock_destruct(struct sock *sk)
|
{
|
if (!(sk->sk_state & PPPOX_DEAD)) {
|
del_chan(pppox_sk(sk));
|
pppox_unbind_sock(sk);
|
}
|
skb_queue_purge(&sk->sk_receive_queue);
|
dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));
|
}
|
|
static int pptp_create(struct net *net, struct socket *sock, int kern)
|
{
|
int error = -ENOMEM;
|
struct sock *sk;
|
struct pppox_sock *po;
|
struct pptp_opt *opt;
|
|
sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pptp_sk_proto, kern);
|
if (!sk)
|
goto out;
|
|
sock_init_data(sock, sk);
|
|
sock->state = SS_UNCONNECTED;
|
sock->ops = &pptp_ops;
|
|
sk->sk_backlog_rcv = pptp_rcv_core;
|
sk->sk_state = PPPOX_NONE;
|
sk->sk_type = SOCK_STREAM;
|
sk->sk_family = PF_PPPOX;
|
sk->sk_protocol = PX_PROTO_PPTP;
|
sk->sk_destruct = pptp_sock_destruct;
|
|
po = pppox_sk(sk);
|
opt = &po->proto.pptp;
|
|
opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
|
opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
|
|
error = 0;
|
out:
|
return error;
|
}
|
|
static int pptp_ppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
|
unsigned long arg)
|
{
|
struct sock *sk = (struct sock *) chan->private;
|
struct pppox_sock *po = pppox_sk(sk);
|
struct pptp_opt *opt = &po->proto.pptp;
|
void __user *argp = (void __user *)arg;
|
int __user *p = argp;
|
int err, val;
|
|
err = -EFAULT;
|
switch (cmd) {
|
case PPPIOCGFLAGS:
|
val = opt->ppp_flags;
|
if (put_user(val, p))
|
break;
|
err = 0;
|
break;
|
case PPPIOCSFLAGS:
|
if (get_user(val, p))
|
break;
|
opt->ppp_flags = val & ~SC_RCV_BITS;
|
err = 0;
|
break;
|
default:
|
err = -ENOTTY;
|
}
|
|
return err;
|
}
|
|
static const struct ppp_channel_ops pptp_chan_ops = {
|
.start_xmit = pptp_xmit,
|
.ioctl = pptp_ppp_ioctl,
|
};
|
|
static struct proto pptp_sk_proto __read_mostly = {
|
.name = "PPTP",
|
.owner = THIS_MODULE,
|
.obj_size = sizeof(struct pppox_sock),
|
};
|
|
static const struct proto_ops pptp_ops = {
|
.family = AF_PPPOX,
|
.owner = THIS_MODULE,
|
.release = pptp_release,
|
.bind = pptp_bind,
|
.connect = pptp_connect,
|
.socketpair = sock_no_socketpair,
|
.accept = sock_no_accept,
|
.getname = pptp_getname,
|
.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,
|
.ioctl = pppox_ioctl,
|
#ifdef CONFIG_COMPAT
|
.compat_ioctl = pppox_compat_ioctl,
|
#endif
|
};
|
|
static const struct pppox_proto pppox_pptp_proto = {
|
.create = pptp_create,
|
.owner = THIS_MODULE,
|
};
|
|
static const struct gre_protocol gre_pptp_protocol = {
|
.handler = pptp_rcv,
|
};
|
|
static int __init pptp_init_module(void)
|
{
|
int err = 0;
|
pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n");
|
|
callid_sock = vzalloc(array_size(sizeof(void *), (MAX_CALLID + 1)));
|
if (!callid_sock)
|
return -ENOMEM;
|
|
err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
|
if (err) {
|
pr_err("PPTP: can't add gre protocol\n");
|
goto out_mem_free;
|
}
|
|
err = proto_register(&pptp_sk_proto, 0);
|
if (err) {
|
pr_err("PPTP: can't register sk_proto\n");
|
goto out_gre_del_protocol;
|
}
|
|
err = register_pppox_proto(PX_PROTO_PPTP, &pppox_pptp_proto);
|
if (err) {
|
pr_err("PPTP: can't register pppox_proto\n");
|
goto out_unregister_sk_proto;
|
}
|
|
return 0;
|
|
out_unregister_sk_proto:
|
proto_unregister(&pptp_sk_proto);
|
out_gre_del_protocol:
|
gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
|
out_mem_free:
|
vfree(callid_sock);
|
|
return err;
|
}
|
|
static void __exit pptp_exit_module(void)
|
{
|
unregister_pppox_proto(PX_PROTO_PPTP);
|
proto_unregister(&pptp_sk_proto);
|
gre_del_protocol(&gre_pptp_protocol, GREPROTO_PPTP);
|
vfree(callid_sock);
|
}
|
|
module_init(pptp_init_module);
|
module_exit(pptp_exit_module);
|
|
MODULE_DESCRIPTION("Point-to-Point Tunneling Protocol");
|
MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
|
MODULE_LICENSE("GPL");
|
MODULE_ALIAS_NET_PF_PROTO(PF_PPPOX, PX_PROTO_PPTP);
|
