/drivers/net/ppp/pptp.c
http://github.com/mirrors/linux · C · 694 lines · 545 code · 128 blank · 21 comment · 97 complexity · 5fad80f730d93d376ce8bd2afb6029d8 MD5 · raw file
- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * Point-to-Point Tunneling Protocol for Linux
- *
- * Authors: Dmitry Kozlov <xeb@mail.ru>
- */
- #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), sk->sk_bound_dev_if);
- 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_ct(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_ct(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),
- sk->sk_bound_dev_if);
- 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);