1/* Copyright 2011-2014 Autronica Fire and Security AS
2 *
3 * This program is free software; you can redistribute it and/or modify it
4 * under the terms of the GNU General Public License as published by the Free
5 * Software Foundation; either version 2 of the License, or (at your option)
6 * any later version.
7 *
8 * Author(s):
9 *	2011-2014 Arvid Brodin, arvid.brodin@alten.se
10 */
11
12#include "hsr_forward.h"
13#include <linux/types.h>
14#include <linux/skbuff.h>
15#include <linux/etherdevice.h>
16#include <linux/if_vlan.h>
17#include "hsr_main.h"
18#include "hsr_framereg.h"
19
20
21struct hsr_node;
22
23struct hsr_frame_info {
24	struct sk_buff *skb_std;
25	struct sk_buff *skb_hsr;
26	struct hsr_port *port_rcv;
27	struct hsr_node *node_src;
28	u16 sequence_nr;
29	bool is_supervision;
30	bool is_vlan;
31	bool is_local_dest;
32	bool is_local_exclusive;
33};
34
35
36/* The uses I can see for these HSR supervision frames are:
37 * 1) Use the frames that are sent after node initialization ("HSR_TLV.Type =
38 *    22") to reset any sequence_nr counters belonging to that node. Useful if
39 *    the other node's counter has been reset for some reason.
40 *    --
41 *    Or not - resetting the counter and bridging the frame would create a
42 *    loop, unfortunately.
43 *
44 * 2) Use the LifeCheck frames to detect ring breaks. I.e. if no LifeCheck
45 *    frame is received from a particular node, we know something is wrong.
46 *    We just register these (as with normal frames) and throw them away.
47 *
48 * 3) Allow different MAC addresses for the two slave interfaces, using the
49 *    MacAddressA field.
50 */
51static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
52{
53	struct hsr_ethhdr_sp *hdr;
54
55	WARN_ON_ONCE(!skb_mac_header_was_set(skb));
56	hdr = (struct hsr_ethhdr_sp *) skb_mac_header(skb);
57
58	if (!ether_addr_equal(hdr->ethhdr.h_dest,
59			      hsr->sup_multicast_addr))
60		return false;
61
62	if (get_hsr_stag_path(&hdr->hsr_sup) != 0x0f)
63		return false;
64	if ((hdr->hsr_sup.HSR_TLV_Type != HSR_TLV_ANNOUNCE) &&
65	    (hdr->hsr_sup.HSR_TLV_Type != HSR_TLV_LIFE_CHECK))
66		return false;
67	if (hdr->hsr_sup.HSR_TLV_Length != 12)
68		return false;
69
70	return true;
71}
72
73
74static struct sk_buff *create_stripped_skb(struct sk_buff *skb_in,
75					   struct hsr_frame_info *frame)
76{
77	struct sk_buff *skb;
78	int copylen;
79	unsigned char *dst, *src;
80
81	skb_pull(skb_in, HSR_HLEN);
82	skb = __pskb_copy(skb_in, skb_headroom(skb_in) - HSR_HLEN, GFP_ATOMIC);
83	skb_push(skb_in, HSR_HLEN);
84	if (skb == NULL)
85		return NULL;
86
87	skb_reset_mac_header(skb);
88
89	if (skb->ip_summed == CHECKSUM_PARTIAL)
90		skb->csum_start -= HSR_HLEN;
91
92	copylen = 2*ETH_ALEN;
93	if (frame->is_vlan)
94		copylen += VLAN_HLEN;
95	src = skb_mac_header(skb_in);
96	dst = skb_mac_header(skb);
97	memcpy(dst, src, copylen);
98
99	skb->protocol = eth_hdr(skb)->h_proto;
100	return skb;
101}
102
103static struct sk_buff *frame_get_stripped_skb(struct hsr_frame_info *frame,
104					      struct hsr_port *port)
105{
106	if (!frame->skb_std)
107		frame->skb_std = create_stripped_skb(frame->skb_hsr, frame);
108	return skb_clone(frame->skb_std, GFP_ATOMIC);
109}
110
111
112static void hsr_fill_tag(struct sk_buff *skb, struct hsr_frame_info *frame,
113			 struct hsr_port *port)
114{
115	struct hsr_ethhdr *hsr_ethhdr;
116	int lane_id;
117	int lsdu_size;
118
119	if (port->type == HSR_PT_SLAVE_A)
120		lane_id = 0;
121	else
122		lane_id = 1;
123
124	lsdu_size = skb->len - 14;
125	if (frame->is_vlan)
126		lsdu_size -= 4;
127
128	hsr_ethhdr = (struct hsr_ethhdr *) skb_mac_header(skb);
129
130	set_hsr_tag_path(&hsr_ethhdr->hsr_tag, lane_id);
131	set_hsr_tag_LSDU_size(&hsr_ethhdr->hsr_tag, lsdu_size);
132	hsr_ethhdr->hsr_tag.sequence_nr = htons(frame->sequence_nr);
133	hsr_ethhdr->hsr_tag.encap_proto = hsr_ethhdr->ethhdr.h_proto;
134	hsr_ethhdr->ethhdr.h_proto = htons(ETH_P_PRP);
135}
136
137static struct sk_buff *create_tagged_skb(struct sk_buff *skb_o,
138					 struct hsr_frame_info *frame,
139					 struct hsr_port *port)
140{
141	int movelen;
142	unsigned char *dst, *src;
143	struct sk_buff *skb;
144
145	/* Create the new skb with enough headroom to fit the HSR tag */
146	skb = __pskb_copy(skb_o, skb_headroom(skb_o) + HSR_HLEN, GFP_ATOMIC);
147	if (skb == NULL)
148		return NULL;
149	skb_reset_mac_header(skb);
150
151	if (skb->ip_summed == CHECKSUM_PARTIAL)
152		skb->csum_start += HSR_HLEN;
153
154	movelen = ETH_HLEN;
155	if (frame->is_vlan)
156		movelen += VLAN_HLEN;
157
158	src = skb_mac_header(skb);
159	dst = skb_push(skb, HSR_HLEN);
160	memmove(dst, src, movelen);
161	skb_reset_mac_header(skb);
162
163	hsr_fill_tag(skb, frame, port);
164
165	return skb;
166}
167
168/* If the original frame was an HSR tagged frame, just clone it to be sent
169 * unchanged. Otherwise, create a private frame especially tagged for 'port'.
170 */
171static struct sk_buff *frame_get_tagged_skb(struct hsr_frame_info *frame,
172					    struct hsr_port *port)
173{
174	if (frame->skb_hsr)
175		return skb_clone(frame->skb_hsr, GFP_ATOMIC);
176
177	if ((port->type != HSR_PT_SLAVE_A) && (port->type != HSR_PT_SLAVE_B)) {
178		WARN_ONCE(1, "HSR: Bug: trying to create a tagged frame for a non-ring port");
179		return NULL;
180	}
181
182	return create_tagged_skb(frame->skb_std, frame, port);
183}
184
185
186static void hsr_deliver_master(struct sk_buff *skb, struct net_device *dev,
187			       struct hsr_node *node_src)
188{
189	bool was_multicast_frame;
190	int res;
191
192	was_multicast_frame = (skb->pkt_type == PACKET_MULTICAST);
193	hsr_addr_subst_source(node_src, skb);
194	skb_pull(skb, ETH_HLEN);
195	res = netif_rx(skb);
196	if (res == NET_RX_DROP) {
197		dev->stats.rx_dropped++;
198	} else {
199		dev->stats.rx_packets++;
200		dev->stats.rx_bytes += skb->len;
201		if (was_multicast_frame)
202			dev->stats.multicast++;
203	}
204}
205
206static int hsr_xmit(struct sk_buff *skb, struct hsr_port *port,
207		    struct hsr_frame_info *frame)
208{
209	if (frame->port_rcv->type == HSR_PT_MASTER) {
210		hsr_addr_subst_dest(frame->node_src, skb, port);
211
212		/* Address substitution (IEC62439-3 pp 26, 50): replace mac
213		 * address of outgoing frame with that of the outgoing slave's.
214		 */
215		ether_addr_copy(eth_hdr(skb)->h_source, port->dev->dev_addr);
216	}
217	return dev_queue_xmit(skb);
218}
219
220
221/* Forward the frame through all devices except:
222 * - Back through the receiving device
223 * - If it's a HSR frame: through a device where it has passed before
224 * - To the local HSR master only if the frame is directly addressed to it, or
225 *   a non-supervision multicast or broadcast frame.
226 *
227 * HSR slave devices should insert a HSR tag into the frame, or forward the
228 * frame unchanged if it's already tagged. Interlink devices should strip HSR
229 * tags if they're of the non-HSR type (but only after duplicate discard). The
230 * master device always strips HSR tags.
231 */
232static void hsr_forward_do(struct hsr_frame_info *frame)
233{
234	struct hsr_port *port;
235	struct sk_buff *skb;
236
237	hsr_for_each_port(frame->port_rcv->hsr, port) {
238		/* Don't send frame back the way it came */
239		if (port == frame->port_rcv)
240			continue;
241
242		/* Don't deliver locally unless we should */
243		if ((port->type == HSR_PT_MASTER) && !frame->is_local_dest)
244			continue;
245
246		/* Deliver frames directly addressed to us to master only */
247		if ((port->type != HSR_PT_MASTER) && frame->is_local_exclusive)
248			continue;
249
250		/* Don't send frame over port where it has been sent before */
251		if (hsr_register_frame_out(port, frame->node_src,
252					   frame->sequence_nr))
253			continue;
254
255		if (frame->is_supervision && (port->type == HSR_PT_MASTER)) {
256			hsr_handle_sup_frame(frame->skb_hsr,
257					     frame->node_src,
258					     frame->port_rcv);
259			continue;
260		}
261
262		if (port->type != HSR_PT_MASTER)
263			skb = frame_get_tagged_skb(frame, port);
264		else
265			skb = frame_get_stripped_skb(frame, port);
266		if (skb == NULL) {
267			/* FIXME: Record the dropped frame? */
268			continue;
269		}
270
271		skb->dev = port->dev;
272		if (port->type == HSR_PT_MASTER)
273			hsr_deliver_master(skb, port->dev, frame->node_src);
274		else
275			hsr_xmit(skb, port, frame);
276	}
277}
278
279
280static void check_local_dest(struct hsr_priv *hsr, struct sk_buff *skb,
281			     struct hsr_frame_info *frame)
282{
283	struct net_device *master_dev;
284
285	master_dev = hsr_port_get_hsr(hsr, HSR_PT_MASTER)->dev;
286
287	if (hsr_addr_is_self(hsr, eth_hdr(skb)->h_dest)) {
288		frame->is_local_exclusive = true;
289		skb->pkt_type = PACKET_HOST;
290	} else {
291		frame->is_local_exclusive = false;
292	}
293
294	if ((skb->pkt_type == PACKET_HOST) ||
295	    (skb->pkt_type == PACKET_MULTICAST) ||
296	    (skb->pkt_type == PACKET_BROADCAST)) {
297		frame->is_local_dest = true;
298	} else {
299		frame->is_local_dest = false;
300	}
301}
302
303
304static int hsr_fill_frame_info(struct hsr_frame_info *frame,
305			       struct sk_buff *skb, struct hsr_port *port)
306{
307	struct ethhdr *ethhdr;
308	unsigned long irqflags;
309
310	frame->is_supervision = is_supervision_frame(port->hsr, skb);
311	frame->node_src = hsr_get_node(&port->hsr->node_db, skb,
312				       frame->is_supervision);
313	if (frame->node_src == NULL)
314		return -1; /* Unknown node and !is_supervision, or no mem */
315
316	ethhdr = (struct ethhdr *) skb_mac_header(skb);
317	frame->is_vlan = false;
318	if (ethhdr->h_proto == htons(ETH_P_8021Q)) {
319		frame->is_vlan = true;
320		/* FIXME: */
321		WARN_ONCE(1, "HSR: VLAN not yet supported");
322	}
323	if (ethhdr->h_proto == htons(ETH_P_PRP)) {
324		frame->skb_std = NULL;
325		frame->skb_hsr = skb;
326		frame->sequence_nr = hsr_get_skb_sequence_nr(skb);
327	} else {
328		frame->skb_std = skb;
329		frame->skb_hsr = NULL;
330		/* Sequence nr for the master node */
331		spin_lock_irqsave(&port->hsr->seqnr_lock, irqflags);
332		frame->sequence_nr = port->hsr->sequence_nr;
333		port->hsr->sequence_nr++;
334		spin_unlock_irqrestore(&port->hsr->seqnr_lock, irqflags);
335	}
336
337	frame->port_rcv = port;
338	check_local_dest(port->hsr, skb, frame);
339
340	return 0;
341}
342
343/* Must be called holding rcu read lock (because of the port parameter) */
344void hsr_forward_skb(struct sk_buff *skb, struct hsr_port *port)
345{
346	struct hsr_frame_info frame;
347
348	if (skb_mac_header(skb) != skb->data) {
349		WARN_ONCE(1, "%s:%d: Malformed frame (port_src %s)\n",
350			  __FILE__, __LINE__, port->dev->name);
351		goto out_drop;
352	}
353
354	if (hsr_fill_frame_info(&frame, skb, port) < 0)
355		goto out_drop;
356	hsr_register_frame_in(frame.node_src, port, frame.sequence_nr);
357	hsr_forward_do(&frame);
358
359	if (frame.skb_hsr != NULL)
360		kfree_skb(frame.skb_hsr);
361	if (frame.skb_std != NULL)
362		kfree_skb(frame.skb_std);
363	return;
364
365out_drop:
366	port->dev->stats.tx_dropped++;
367	kfree_skb(skb);
368}
369