1 /* Error message handling (ICMP)
2  *
3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #include <linux/module.h>
13 #include <linux/net.h>
14 #include <linux/skbuff.h>
15 #include <linux/errqueue.h>
16 #include <linux/udp.h>
17 #include <linux/in.h>
18 #include <linux/in6.h>
19 #include <linux/icmp.h>
20 #include <net/sock.h>
21 #include <net/af_rxrpc.h>
22 #include <net/ip.h>
23 #include "ar-internal.h"
24 
25 /*
26  * handle an error received on the local endpoint
27  */
rxrpc_UDP_error_report(struct sock * sk)28 void rxrpc_UDP_error_report(struct sock *sk)
29 {
30 	struct sock_exterr_skb *serr;
31 	struct rxrpc_transport *trans;
32 	struct rxrpc_local *local = sk->sk_user_data;
33 	struct rxrpc_peer *peer;
34 	struct sk_buff *skb;
35 	__be32 addr;
36 	__be16 port;
37 
38 	_enter("%p{%d}", sk, local->debug_id);
39 
40 	skb = skb_dequeue(&sk->sk_error_queue);
41 	if (!skb) {
42 		_leave("UDP socket errqueue empty");
43 		return;
44 	}
45 
46 	rxrpc_new_skb(skb);
47 
48 	serr = SKB_EXT_ERR(skb);
49 	addr = *(__be32 *)(skb_network_header(skb) + serr->addr_offset);
50 	port = serr->port;
51 
52 	_net("Rx UDP Error from %pI4:%hu", &addr, ntohs(port));
53 	_debug("Msg l:%d d:%d", skb->len, skb->data_len);
54 
55 	peer = rxrpc_find_peer(local, addr, port);
56 	if (IS_ERR(peer)) {
57 		rxrpc_free_skb(skb);
58 		_leave(" [no peer]");
59 		return;
60 	}
61 
62 	trans = rxrpc_find_transport(local, peer);
63 	if (!trans) {
64 		rxrpc_put_peer(peer);
65 		rxrpc_free_skb(skb);
66 		_leave(" [no trans]");
67 		return;
68 	}
69 
70 	if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP &&
71 	    serr->ee.ee_type == ICMP_DEST_UNREACH &&
72 	    serr->ee.ee_code == ICMP_FRAG_NEEDED
73 	    ) {
74 		u32 mtu = serr->ee.ee_info;
75 
76 		_net("Rx Received ICMP Fragmentation Needed (%d)", mtu);
77 
78 		/* wind down the local interface MTU */
79 		if (mtu > 0 && peer->if_mtu == 65535 && mtu < peer->if_mtu) {
80 			peer->if_mtu = mtu;
81 			_net("I/F MTU %u", mtu);
82 		}
83 
84 		/* ip_rt_frag_needed() may have eaten the info */
85 		if (mtu == 0)
86 			mtu = ntohs(icmp_hdr(skb)->un.frag.mtu);
87 
88 		if (mtu == 0) {
89 			/* they didn't give us a size, estimate one */
90 			if (mtu > 1500) {
91 				mtu >>= 1;
92 				if (mtu < 1500)
93 					mtu = 1500;
94 			} else {
95 				mtu -= 100;
96 				if (mtu < peer->hdrsize)
97 					mtu = peer->hdrsize + 4;
98 			}
99 		}
100 
101 		if (mtu < peer->mtu) {
102 			spin_lock_bh(&peer->lock);
103 			peer->mtu = mtu;
104 			peer->maxdata = peer->mtu - peer->hdrsize;
105 			spin_unlock_bh(&peer->lock);
106 			_net("Net MTU %u (maxdata %u)",
107 			     peer->mtu, peer->maxdata);
108 		}
109 	}
110 
111 	rxrpc_put_peer(peer);
112 
113 	/* pass the transport ref to error_handler to release */
114 	skb_queue_tail(&trans->error_queue, skb);
115 	rxrpc_queue_work(&trans->error_handler);
116 
117 	/* reset and regenerate socket error */
118 	spin_lock_bh(&sk->sk_error_queue.lock);
119 	sk->sk_err = 0;
120 	skb = skb_peek(&sk->sk_error_queue);
121 	if (skb) {
122 		sk->sk_err = SKB_EXT_ERR(skb)->ee.ee_errno;
123 		spin_unlock_bh(&sk->sk_error_queue.lock);
124 		sk->sk_error_report(sk);
125 	} else {
126 		spin_unlock_bh(&sk->sk_error_queue.lock);
127 	}
128 
129 	_leave("");
130 }
131 
132 /*
133  * deal with UDP error messages
134  */
rxrpc_UDP_error_handler(struct work_struct * work)135 void rxrpc_UDP_error_handler(struct work_struct *work)
136 {
137 	struct sock_extended_err *ee;
138 	struct sock_exterr_skb *serr;
139 	struct rxrpc_transport *trans =
140 		container_of(work, struct rxrpc_transport, error_handler);
141 	struct sk_buff *skb;
142 	int err;
143 
144 	_enter("");
145 
146 	skb = skb_dequeue(&trans->error_queue);
147 	if (!skb)
148 		return;
149 
150 	serr = SKB_EXT_ERR(skb);
151 	ee = &serr->ee;
152 
153 	_net("Rx Error o=%d t=%d c=%d e=%d",
154 	     ee->ee_origin, ee->ee_type, ee->ee_code, ee->ee_errno);
155 
156 	err = ee->ee_errno;
157 
158 	switch (ee->ee_origin) {
159 	case SO_EE_ORIGIN_ICMP:
160 		switch (ee->ee_type) {
161 		case ICMP_DEST_UNREACH:
162 			switch (ee->ee_code) {
163 			case ICMP_NET_UNREACH:
164 				_net("Rx Received ICMP Network Unreachable");
165 				err = ENETUNREACH;
166 				break;
167 			case ICMP_HOST_UNREACH:
168 				_net("Rx Received ICMP Host Unreachable");
169 				err = EHOSTUNREACH;
170 				break;
171 			case ICMP_PORT_UNREACH:
172 				_net("Rx Received ICMP Port Unreachable");
173 				err = ECONNREFUSED;
174 				break;
175 			case ICMP_FRAG_NEEDED:
176 				_net("Rx Received ICMP Fragmentation Needed (%d)",
177 				     ee->ee_info);
178 				err = 0; /* dealt with elsewhere */
179 				break;
180 			case ICMP_NET_UNKNOWN:
181 				_net("Rx Received ICMP Unknown Network");
182 				err = ENETUNREACH;
183 				break;
184 			case ICMP_HOST_UNKNOWN:
185 				_net("Rx Received ICMP Unknown Host");
186 				err = EHOSTUNREACH;
187 				break;
188 			default:
189 				_net("Rx Received ICMP DestUnreach code=%u",
190 				     ee->ee_code);
191 				break;
192 			}
193 			break;
194 
195 		case ICMP_TIME_EXCEEDED:
196 			_net("Rx Received ICMP TTL Exceeded");
197 			break;
198 
199 		default:
200 			_proto("Rx Received ICMP error { type=%u code=%u }",
201 			       ee->ee_type, ee->ee_code);
202 			break;
203 		}
204 		break;
205 
206 	case SO_EE_ORIGIN_LOCAL:
207 		_proto("Rx Received local error { error=%d }",
208 		       ee->ee_errno);
209 		break;
210 
211 	case SO_EE_ORIGIN_NONE:
212 	case SO_EE_ORIGIN_ICMP6:
213 	default:
214 		_proto("Rx Received error report { orig=%u }",
215 		       ee->ee_origin);
216 		break;
217 	}
218 
219 	/* terminate all the affected calls if there's an unrecoverable
220 	 * error */
221 	if (err) {
222 		struct rxrpc_call *call, *_n;
223 
224 		_debug("ISSUE ERROR %d", err);
225 
226 		spin_lock_bh(&trans->peer->lock);
227 		trans->peer->net_error = err;
228 
229 		list_for_each_entry_safe(call, _n, &trans->peer->error_targets,
230 					 error_link) {
231 			write_lock(&call->state_lock);
232 			if (call->state != RXRPC_CALL_COMPLETE &&
233 			    call->state < RXRPC_CALL_NETWORK_ERROR) {
234 				call->state = RXRPC_CALL_NETWORK_ERROR;
235 				set_bit(RXRPC_CALL_RCVD_ERROR, &call->events);
236 				rxrpc_queue_call(call);
237 			}
238 			write_unlock(&call->state_lock);
239 			list_del_init(&call->error_link);
240 		}
241 
242 		spin_unlock_bh(&trans->peer->lock);
243 	}
244 
245 	if (!skb_queue_empty(&trans->error_queue))
246 		rxrpc_queue_work(&trans->error_handler);
247 
248 	rxrpc_free_skb(skb);
249 	rxrpc_put_transport(trans);
250 	_leave("");
251 }
252