1From: Simon Farnsworth <simon@farnz.org.uk>
2Date: Sun, 1 Mar 2015 10:54:39 +0000
3Subject: [PATCH] pppoe: Use workqueue to die properly when a PADT is received
4
5When a PADT frame is received, the socket may not be in a good state to
6close down the PPP interface. The current implementation handles this by
7simply blocking all further PPP traffic, and hoping that the lack of traffic
8will trigger the user to investigate.
9
10Use schedule_work to get to a process context from which we clear down the
11PPP interface, in a fashion analogous to hangup on a TTY-based PPP
12interface. This causes pppd to disconnect immediately, and allows tools to
13take immediate corrective action.
14
15Note that pppd's rp_pppoe.so plugin has code in it to disable the session
16when it disconnects; however, as a consequence of this patch, the session is
17already disabled before rp_pppoe.so is asked to disable the session. The
18result is a harmless error message:
19
20Failed to disconnect PPPoE socket: 114 Operation already in progress
21
22This message is safe to ignore, as long as the error is 114 Operation
23already in progress; in that specific case, it means that the PPPoE session
24has already been disabled before pppd tried to disable it.
25
26Signed-off-by: Simon Farnsworth <simon@farnz.org.uk>
27Tested-by: Dan Williams <dcbw@redhat.com>
28Tested-by: Christoph Schulz <develop@kristov.de>
29Signed-off-by: David S. Miller <davem@davemloft.net>
30---
31
32--- a/drivers/net/ppp/pppoe.c
33+++ b/drivers/net/ppp/pppoe.c
34@@ -454,6 +454,18 @@ out:
35 	return NET_RX_DROP;
36 }
37 
38+static void pppoe_unbind_sock_work(struct work_struct *work)
39+{
40+	struct pppox_sock *po = container_of(work, struct pppox_sock,
41+					     proto.pppoe.padt_work);
42+	struct sock *sk = sk_pppox(po);
43+
44+	lock_sock(sk);
45+	pppox_unbind_sock(sk);
46+	release_sock(sk);
47+	sock_put(sk);
48+}
49+
50 /************************************************************************
51  *
52  * Receive a PPPoE Discovery frame.
53@@ -499,7 +511,8 @@ static int pppoe_disc_rcv(struct sk_buff
54 		}
55 
56 		bh_unlock_sock(sk);
57-		sock_put(sk);
58+		if (!schedule_work(&po->proto.pppoe.padt_work))
59+			sock_put(sk);
60 	}
61 
62 abort:
63@@ -612,6 +625,8 @@ static int pppoe_connect(struct socket *
64 
65 	lock_sock(sk);
66 
67+	INIT_WORK(&po->proto.pppoe.padt_work, pppoe_unbind_sock_work);
68+
69 	error = -EINVAL;
70 	if (sp->sa_protocol != PX_PROTO_OE)
71 		goto end;
72--- a/include/linux/if_pppox.h
73+++ b/include/linux/if_pppox.h
74@@ -19,6 +19,7 @@
75 #include <linux/netdevice.h>
76 #include <linux/ppp_channel.h>
77 #include <linux/skbuff.h>
78+#include <linux/workqueue.h>
79 #include <uapi/linux/if_pppox.h>
80 
81 static inline struct pppoe_hdr *pppoe_hdr(const struct sk_buff *skb)
82@@ -32,6 +33,7 @@ struct pppoe_opt {
83 	struct pppoe_addr	pa;	  /* what this socket is bound to*/
84 	struct sockaddr_pppox	relay;	  /* what socket data will be
85 					     relayed to (PPPoE relaying) */
86+	struct work_struct      padt_work;/* Work item for handling PADT */
87 };
88 
89 struct pptp_opt {
90