firmware/br-ext-chip-allwinner/board/v83x/kernel/patches/00000-drivers_net_ppp_pppopns.c.patch

diff -drupN a/drivers/net/ppp/pppopns.c b/drivers/net/ppp/pppopns.c
--- a/drivers/net/ppp/pppopns.c	1970-01-01 03:00:00.000000000 +0300
+++ b/drivers/net/ppp/pppopns.c	2022-06-12 05:28:14.000000000 +0300
@@ -0,0 +1,429 @@
+/* drivers/net/pppopns.c
+ *
+ * Driver for PPP on PPTP Network Server / PPPoPNS Socket (RFC 2637)
+ *
+ * Copyright (C) 2009 Google, Inc.
+ *
+ * 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. Outgoing packets are always sent with sequences but
+ * without acknowledgements. Incoming packets with sequences are reordered
+ * within a sliding window of one second. Currently reordering only happens when
+ * a packet is received. It is done for simplicity since no additional locks or
+ * threads are required. This driver should work on both IPv4 and IPv6. */
+
+#include <linux/module.h>
+#include <linux/jiffies.h>
+#include <linux/workqueue.h>
+#include <linux/skbuff.h>
+#include <linux/file.h>
+#include <linux/netdevice.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>
+#include <asm/uaccess.h>
+
+#define GRE_HEADER_SIZE		8
+
+#define PPTP_GRE_BITS		htons(0x2001)
+#define PPTP_GRE_BITS_MASK	htons(0xEF7F)
+#define PPTP_GRE_SEQ_BIT	htons(0x1000)
+#define PPTP_GRE_ACK_BIT	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));
+
+struct meta {
+	__u32 sequence;
+	__u32 timestamp;
+};
+
+static inline struct meta *skb_meta(struct sk_buff *skb)
+{
+	return (struct meta *)skb->cb;
+}
+
+/******************************************************************************/
+
+static int pppopns_recv_core(struct sock *sk_raw, struct sk_buff *skb)
+{
+	struct sock *sk = (struct sock *)sk_raw->sk_user_data;
+	struct pppopns_opt *opt = &pppox_sk(sk)->proto.pns;
+	struct meta *meta = skb_meta(skb);
+	__u32 now = jiffies;
+	struct header *hdr;
+
+	/* Skip transport header */
+	skb_pull(skb, skb_transport_header(skb) - skb->data);
+
+	/* Drop the packet if GRE header is missing. */
+	if (skb->len < GRE_HEADER_SIZE)
+		goto drop;
+	hdr = (struct header *)skb->data;
+
+	/* Check the header. */
+	if (hdr->type != PPTP_GRE_TYPE || hdr->call != opt->local ||
+			(hdr->bits & PPTP_GRE_BITS_MASK) != PPTP_GRE_BITS)
+		goto drop;
+
+	/* Skip all fields including optional ones. */
+	if (!skb_pull(skb, GRE_HEADER_SIZE +
+			(hdr->bits & PPTP_GRE_SEQ_BIT ? 4 : 0) +
+			(hdr->bits & PPTP_GRE_ACK_BIT ? 4 : 0)))
+		goto drop;
+
+	/* Check the length. */
+	if (skb->len != ntohs(hdr->length))
+		goto drop;
+
+	/* Check the sequence if it is present. */
+	if (hdr->bits & PPTP_GRE_SEQ_BIT) {
+		meta->sequence = ntohl(hdr->sequence);
+		if ((__s32)(meta->sequence - opt->recv_sequence) < 0)
+			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;
+
+	/* Drop the packet if PPP protocol is missing. */
+	if (skb->len < 2)
+		goto drop;
+
+	/* Perform reordering if sequencing is enabled. */
+	if (hdr->bits & PPTP_GRE_SEQ_BIT) {
+		struct sk_buff *skb1;
+
+		/* Insert the packet into receive queue in order. */
+		skb_set_owner_r(skb, sk);
+		skb_queue_walk(&sk->sk_receive_queue, skb1) {
+			struct meta *meta1 = skb_meta(skb1);
+			__s32 order = meta->sequence - meta1->sequence;
+			if (order == 0)
+				goto drop;
+			if (order < 0) {
+				meta->timestamp = meta1->timestamp;
+				skb_insert(skb1, skb, &sk->sk_receive_queue);
+				skb = NULL;
+				break;
+			}
+		}
+		if (skb) {
+			meta->timestamp = now;
+			skb_queue_tail(&sk->sk_receive_queue, skb);
+		}
+
+		/* Remove packets from receive queue as long as
+		 * 1. the receive buffer is full,
+		 * 2. they are queued longer than one second, or
+		 * 3. there are no missing packets before them. */
+		skb_queue_walk_safe(&sk->sk_receive_queue, skb, skb1) {
+			meta = skb_meta(skb);
+			if (atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
+					now - meta->timestamp < HZ &&
+					meta->sequence != opt->recv_sequence)
+				break;
+			skb_unlink(skb, &sk->sk_receive_queue);
+			opt->recv_sequence = meta->sequence + 1;
+			skb_orphan(skb);
+			ppp_input(&pppox_sk(sk)->chan, skb);
+		}
+		return NET_RX_SUCCESS;
+	}
+
+	/* Flush receive queue if sequencing is disabled. */
+	skb_queue_purge(&sk->sk_receive_queue);
+	skb_orphan(skb);
+	ppp_input(&pppox_sk(sk)->chan, skb);
+	return NET_RX_SUCCESS;
+drop:
+	kfree_skb(skb);
+	return NET_RX_DROP;
+}
+
+static void pppopns_recv(struct sock *sk_raw)
+{
+	struct sk_buff *skb;
+	while ((skb = skb_dequeue(&sk_raw->sk_receive_queue))) {
+		sock_hold(sk_raw);
+		sk_receive_skb(sk_raw, skb, 0);
+	}
+}
+
+static struct sk_buff_head delivery_queue;
+
+static void pppopns_xmit_core(struct work_struct *delivery_work)
+{
+	mm_segment_t old_fs = get_fs();
+	struct sk_buff *skb;
+
+	set_fs(KERNEL_DS);
+	while ((skb = skb_dequeue(&delivery_queue))) {
+		struct sock *sk_raw = skb->sk;
+		struct kvec iov = {.iov_base = skb->data, .iov_len = skb->len};
+		struct msghdr msg = {
+			.msg_flags = MSG_NOSIGNAL | MSG_DONTWAIT,
+		};
+
+		iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, &iov, 1,
+			      skb->len);
+		sk_raw->sk_prot->sendmsg(sk_raw, &msg, skb->len);
+		kfree_skb(skb);
+	}
+	set_fs(old_fs);
+}
+
+static DECLARE_WORK(delivery_work, pppopns_xmit_core);
+
+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 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_BITS | PPTP_GRE_SEQ_BIT;
+	hdr->type = PPTP_GRE_TYPE;
+	hdr->length = htons(length);
+	hdr->call = opt->remote;
+	hdr->sequence = htonl(opt->xmit_sequence);
+	opt->xmit_sequence++;
+
+	/* Now send the packet via the delivery queue. */
+	skb_set_owner_w(skb, sk_raw);
+	skb_queue_tail(&delivery_queue, skb);
+	schedule_work(&delivery_work);
+	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_tcp;
+	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;
+	sk_tcp = sock_tcp->sk;
+	error = -EPROTONOSUPPORT;
+	if (sk_tcp->sk_protocol != IPPROTO_TCP)
+		goto out;
+	addrlen = sizeof(struct sockaddr_storage);
+	error = kernel_getpeername(sock_tcp, (struct sockaddr *)&ss, &addrlen);
+	if (error)
+		goto out;
+	if (!sk_tcp->sk_bound_dev_if) {
+		struct dst_entry *dst = sk_dst_get(sk_tcp);
+		error = -ENODEV;
+		if (!dst)
+			goto out;
+		sk_tcp->sk_bound_dev_if = dst->dev->ifindex;
+		dst_release(dst);
+	}
+
+	error = sock_create(ss.ss_family, SOCK_RAW, IPPROTO_GRE, &sock_raw);
+	if (error)
+		goto out;
+	sk_raw = sock_raw->sk;
+	sk_raw->sk_bound_dev_if = sk_tcp->sk_bound_dev_if;
+	error = kernel_connect(sock_raw, (struct sockaddr *)&ss, addrlen, 0);
+	if (error)
+		goto out;
+
+	po->chan.hdrlen = 14;
+	po->chan.private = sk_raw;
+	po->chan.ops = &pppopns_channel_ops;
+	po->chan.mtu = PPP_MRU - 80;
+	po->proto.pns.local = addr->local;
+	po->proto.pns.remote = addr->remote;
+	po->proto.pns.data_ready = sk_raw->sk_data_ready;
+	po->proto.pns.backlog_rcv = sk_raw->sk_backlog_rcv;
+
+	error = ppp_register_channel(&po->chan);
+	if (error)
+		goto out;
+
+	sk->sk_state = PPPOX_CONNECTED;
+	lock_sock(sk_raw);
+	sk_raw->sk_data_ready = pppopns_recv;
+	sk_raw->sk_backlog_rcv = pppopns_recv_core;
+	sk_raw->sk_user_data = sk;
+	release_sock(sk_raw);
+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);
+		skb_queue_purge(&sk->sk_receive_queue);
+		pppox_unbind_sock(sk);
+		sk_raw->sk_data_ready = pppox_sk(sk)->proto.pns.data_ready;
+		sk_raw->sk_backlog_rcv = pppox_sk(sk)->proto.pns.backlog_rcv;
+		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, int kern)
+{
+	struct sock *sk;
+
+	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pppopns_proto, kern);
+	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);
+	else
+		skb_queue_head_init(&delivery_queue);
+	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");