// 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/security.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(&sock->sk); } 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 struct rtable *pptp_route_output(const struct pppox_sock *po, struct flowi4 *fl4){ const struct sock *sk = &po->sk; struct net *net; net = sock_net(sk); flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark, 0, RT_SCOPE_UNIVERSE, IPPROTO_GRE, 0, po->proto.pptp.dst_addr.sin_addr.s_addr, po->proto.pptp.src_addr.sin_addr.s_addr, 0, 0, sock_net_uid(net, sk)); security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4)); return ip_route_output_flow(net, fl4, sk);} static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb){ struct sock *sk = 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 (po->sk.sk_state & PPPOX_DEAD) goto tx_drop; rt = pptp_route_output(po, &fl4); if (IS_ERR(rt)) goto tx_drop; 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) goto tx_error; if (skb->sk) skb_set_owner_w(new_skb, skb->sk); consume_skb(skb); skb = new_skb; } /* Ensure we can safely access protocol field and LCP code */ if (!pskb_may_pull(skb, 3)) goto tx_error; 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: ip_rt_put(rt);tx_drop: 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)) goto drop; 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) ? ntohl(header->ack) : ntohl(header->seq); 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(ntohs(header->call_id), iph->saddr); if (po) { skb_dst_drop(skb); nf_reset_ct(skb); return sk_receive_skb(&po->sk, skb, 0); }drop: kfree_skb(skb); return NET_RX_DROP;} static int pptp_bind(struct socket *sock, struct sockaddr_unsized *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_unsized *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 = pptp_route_output(po, &fl4); 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); po->chan.direct_xmit = true; 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;} Lines 1–500 of 700. 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// 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/security.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(&sock->sk); } 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 struct rtable *pptp_route_output(const struct pppox_sock *po, struct flowi4 *fl4) { const struct sock *sk = &po->sk; struct net *net; net = sock_net(sk); flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark, 0, RT_SCOPE_UNIVERSE, IPPROTO_GRE, 0, po->proto.pptp.dst_addr.sin_addr.s_addr, po->proto.pptp.src_addr.sin_addr.s_addr, 0, 0, sock_net_uid(net, sk)); security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4)); return ip_route_output_flow(net, fl4, sk); } static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb) { struct sock *sk = 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 (po->sk.sk_state & PPPOX_DEAD) goto tx_drop; rt = pptp_route_output(po, &fl4); if (IS_ERR(rt)) goto tx_drop; 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) goto tx_error; if (skb->sk) skb_set_owner_w(new_skb, skb->sk); consume_skb(skb); skb = new_skb; } /* Ensure we can safely access protocol field and LCP code */ if (!pskb_may_pull(skb, 3)) goto tx_error; 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: ip_rt_put(rt); tx_drop: 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)) goto drop; 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) ? ntohl(header->ack) : ntohl(header->seq); 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(ntohs(header->call_id), iph->saddr); if (po) { skb_dst_drop(skb); nf_reset_ct(skb); return sk_receive_skb(&po->sk, skb, 0); } drop: kfree_skb(skb); return NET_RX_DROP; } static int pptp_bind(struct socket *sock, struct sockaddr_unsized *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_unsized *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 = pptp_route_output(po, &fl4); 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); po->chan.direct_xmit = true; 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; }