diff options
Diffstat (limited to 'drivers/net/pptp.c')
| -rw-r--r-- | drivers/net/pptp.c | 726 |
1 files changed, 726 insertions, 0 deletions
diff --git a/drivers/net/pptp.c b/drivers/net/pptp.c new file mode 100644 index 000000000000..ccbc91326bfa --- /dev/null +++ b/drivers/net/pptp.c @@ -0,0 +1,726 @@ +/* + * 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/if_ppp.h> +#include <linux/notifier.h> +#include <linux/file.h> +#include <linux/in.h> +#include <linux/ip.h> +#include <linux/netfilter.h> +#include <linux/netfilter_ipv4.h> +#include <linux/version.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 <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 **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; + +#define PPP_LCP_ECHOREQ 0x09 +#define PPP_LCP_ECHOREP 0x0A +#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP) + +#define MISSING_WINDOW 20 +#define WRAPPED(curseq, lastseq)\ + ((((curseq) & 0xffffff00) == 0) &&\ + (((lastseq) & 0xffffff00) == 0xffffff00)) + +#define PPTP_GRE_PROTO 0x880B +#define PPTP_GRE_VER 0x1 + +#define PPTP_GRE_FLAG_C 0x80 +#define PPTP_GRE_FLAG_R 0x40 +#define PPTP_GRE_FLAG_K 0x20 +#define PPTP_GRE_FLAG_S 0x10 +#define PPTP_GRE_FLAG_A 0x80 + +#define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C) +#define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R) +#define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K) +#define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S) +#define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A) + +#define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header)) +struct pptp_gre_header { + u8 flags; + u8 ver; + u16 protocol; + u16 payload_len; + u16 call_id; + u32 seq; + u32 ack; +} __packed; + +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(); + for (i = find_next_bit(callid_bitmap, MAX_CALLID, 1); i < MAX_CALLID; + i = find_next_bit(callid_bitmap, MAX_CALLID, i + 1)) { + 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) +{ + static int call_id; + + spin_lock(&chan_lock); + if (!sock->proto.pptp.src_addr.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; + } + sock->proto.pptp.src_addr.call_id = call_id; + } else if (test_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap)) + goto out_err; + + set_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap); + rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.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_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], NULL); + spin_unlock(&chan_lock); + synchronize_rcu(); +} + +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 pptp_opt *opt = &po->proto.pptp; + struct pptp_gre_header *hdr; + unsigned int header_len = sizeof(*hdr); + int err = 0; + 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; + + { + struct flowi fl = { .oif = 0, + .nl_u = { + .ip4_u = { + .daddr = opt->dst_addr.sin_addr.s_addr, + .saddr = opt->src_addr.sin_addr.s_addr, + .tos = RT_TOS(0) } }, + .proto = IPPROTO_GRE }; + err = ip_route_output_key(&init_net, &rt, &fl); + if (err) + 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); + kfree_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->flags = PPTP_GRE_FLAG_K; + hdr->ver = PPTP_GRE_VER; + hdr->protocol = htons(PPTP_GRE_PROTO); + hdr->call_id = htons(opt->dst_addr.call_id); + + hdr->flags |= PPTP_GRE_FLAG_S; + hdr->seq = htonl(++opt->seq_sent); + if (opt->ack_sent != seq_recv) { + /* send ack with this message */ + hdr->ver |= PPTP_GRE_FLAG_A; + 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 = rt->rt_dst; + iph->saddr = rt->rt_src; + iph->ttl = dst_metric(&rt->dst, RTAX_HOPLIMIT); + 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(iph, &rt->dst, NULL); + ip_send_check(iph); + + ip_local_out(skb); + +tx_error: + 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); + + /* test if acknowledgement present */ + if (PPTP_GRE_IS_A(header->ver)) { + __u32 ack = (PPTP_GRE_IS_S(header->flags)) ? + header->ack : header->seq; /* ack in different place if S = 0 */ + + 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; + } + + /* test if payload present */ + if (!PPTP_GRE_IS_S(header->flags)) + goto drop; + + headersize = sizeof(*header); + payload_len = ntohs(header->payload_len); + seq = ntohl(header->seq); + + /* no ack present? */ + if (!PPTP_GRE_IS_A(header->ver)) + headersize -= sizeof(header->ack); + /* check for incomplete packet (length smaller than expected) */ + if (skb->len - 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); + } + + if ((*skb->data) & 1) { + /* protocol is compressed */ + skb_push(skb, 1)[0] = 0; + } + + 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 (ntohs(header->protocol) != PPTP_GRE_PROTO || /* PPTP-GRE protocol for PPTP */ + PPTP_GRE_IS_C(header->flags) || /* flag C should be clear */ + PPTP_GRE_IS_R(header->flags) || /* flag R should be clear */ + !PPTP_GRE_IS_K(header->flags) || /* flag K should be set */ + (header->flags&0xF) != 0) /* routing and recursion ctrl = 0 */ + /* 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); + struct pptp_opt *opt = &po->proto.pptp; + int error = 0; + + lock_sock(sk); + + opt->src_addr = sp->sa_addr.pptp; + if (add_chan(po)) { + release_sock(sk); + error = -EBUSY; + } + + 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; + int error = 0; + + 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; + + { + struct flowi fl = { + .nl_u = { + .ip4_u = { + .daddr = opt->dst_addr.sin_addr.s_addr, + .saddr = opt->src_addr.sin_addr.s_addr, + .tos = RT_CONN_FLAGS(sk) } }, + .proto = IPPROTO_GRE }; + security_sk_classify_flow(sk, &fl); + if (ip_route_output_key(&init_net, &rt, &fl)) { + 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_MTU; + ip_rt_put(rt); + 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 *usockaddr_len, int peer) +{ + int len = sizeof(struct sockaddr_pppox); + struct sockaddr_pppox sp; + + 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); + + *usockaddr_len = len; + + return 0; +} + +static int pptp_release(struct socket *sock) +{ + struct sock *sk = sock->sk; + struct pppox_sock *po; + struct pptp_opt *opt; + 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); + opt = &po->proto.pptp; + del_chan(po); + + 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); +} + +static int pptp_create(struct net *net, struct socket *sock) +{ + 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); + 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 = 0; + opt->ack_recv = 0; opt->ack_sent = 0; + + 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, + .poll = sock_no_poll, + .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, +}; + +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 = __vmalloc((MAX_CALLID + 1) * sizeof(void *), + GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL); + if (!callid_sock) { + pr_err("PPTP: cann't allocate memory\n"); + 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"); |