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  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 ethhdr *ethHdr;
 54	struct hsr_sup_tag *hsrSupTag;
 55	struct hsrv1_ethhdr_sp *hsrV1Hdr;
 56
 57	WARN_ON_ONCE(!skb_mac_header_was_set(skb));
 58	ethHdr = (struct ethhdr *) skb_mac_header(skb);
 59
 60	/* Correct addr? */
 61	if (!ether_addr_equal(ethHdr->h_dest,
 62			      hsr->sup_multicast_addr))
 63		return false;
 64
 65	/* Correct ether type?. */
 66	if (!(ethHdr->h_proto == htons(ETH_P_PRP)
 67			|| ethHdr->h_proto == htons(ETH_P_HSR)))
 68		return false;
 69
 70	/* Get the supervision header from correct location. */
 71	if (ethHdr->h_proto == htons(ETH_P_HSR)) { /* Okay HSRv1. */
 72		hsrV1Hdr = (struct hsrv1_ethhdr_sp *) skb_mac_header(skb);
 73		if (hsrV1Hdr->hsr.encap_proto != htons(ETH_P_PRP))
 74			return false;
 75
 76		hsrSupTag = &hsrV1Hdr->hsr_sup;
 77	} else {
 78		hsrSupTag = &((struct hsrv0_ethhdr_sp *) skb_mac_header(skb))->hsr_sup;
 79	}
 80
 81	if ((hsrSupTag->HSR_TLV_Type != HSR_TLV_ANNOUNCE) &&
 82	    (hsrSupTag->HSR_TLV_Type != HSR_TLV_LIFE_CHECK))
 83		return false;
 84	if ((hsrSupTag->HSR_TLV_Length != 12) &&
 85			(hsrSupTag->HSR_TLV_Length !=
 86					sizeof(struct hsr_sup_payload)))
 87		return false;
 88
 89	return true;
 90}
 91
 92
 93static struct sk_buff *create_stripped_skb(struct sk_buff *skb_in,
 94					   struct hsr_frame_info *frame)
 95{
 96	struct sk_buff *skb;
 97	int copylen;
 98	unsigned char *dst, *src;
 99
100	skb_pull(skb_in, HSR_HLEN);
101	skb = __pskb_copy(skb_in, skb_headroom(skb_in) - HSR_HLEN, GFP_ATOMIC);
102	skb_push(skb_in, HSR_HLEN);
103	if (skb == NULL)
104		return NULL;
105
106	skb_reset_mac_header(skb);
107
108	if (skb->ip_summed == CHECKSUM_PARTIAL)
109		skb->csum_start -= HSR_HLEN;
110
111	copylen = 2*ETH_ALEN;
112	if (frame->is_vlan)
113		copylen += VLAN_HLEN;
114	src = skb_mac_header(skb_in);
115	dst = skb_mac_header(skb);
116	memcpy(dst, src, copylen);
117
118	skb->protocol = eth_hdr(skb)->h_proto;
119	return skb;
120}
121
122static struct sk_buff *frame_get_stripped_skb(struct hsr_frame_info *frame,
123					      struct hsr_port *port)
124{
125	if (!frame->skb_std)
126		frame->skb_std = create_stripped_skb(frame->skb_hsr, frame);
127	return skb_clone(frame->skb_std, GFP_ATOMIC);
128}
129
130
131static void hsr_fill_tag(struct sk_buff *skb, struct hsr_frame_info *frame,
132			 struct hsr_port *port, u8 protoVersion)
133{
134	struct hsr_ethhdr *hsr_ethhdr;
135	int lane_id;
136	int lsdu_size;
137
138	if (port->type == HSR_PT_SLAVE_A)
139		lane_id = 0;
140	else
141		lane_id = 1;
142
143	lsdu_size = skb->len - 14;
144	if (frame->is_vlan)
145		lsdu_size -= 4;
146
147	hsr_ethhdr = (struct hsr_ethhdr *) skb_mac_header(skb);
148
149	set_hsr_tag_path(&hsr_ethhdr->hsr_tag, lane_id);
150	set_hsr_tag_LSDU_size(&hsr_ethhdr->hsr_tag, lsdu_size);
151	hsr_ethhdr->hsr_tag.sequence_nr = htons(frame->sequence_nr);
152	hsr_ethhdr->hsr_tag.encap_proto = hsr_ethhdr->ethhdr.h_proto;
153	hsr_ethhdr->ethhdr.h_proto = htons(protoVersion ?
154			ETH_P_HSR : ETH_P_PRP);
155}
156
157static struct sk_buff *create_tagged_skb(struct sk_buff *skb_o,
158					 struct hsr_frame_info *frame,
159					 struct hsr_port *port)
160{
161	int movelen;
162	unsigned char *dst, *src;
163	struct sk_buff *skb;
164
165	/* Create the new skb with enough headroom to fit the HSR tag */
166	skb = __pskb_copy(skb_o, skb_headroom(skb_o) + HSR_HLEN, GFP_ATOMIC);
167	if (skb == NULL)
168		return NULL;
169	skb_reset_mac_header(skb);
170
171	if (skb->ip_summed == CHECKSUM_PARTIAL)
172		skb->csum_start += HSR_HLEN;
173
174	movelen = ETH_HLEN;
175	if (frame->is_vlan)
176		movelen += VLAN_HLEN;
177
178	src = skb_mac_header(skb);
179	dst = skb_push(skb, HSR_HLEN);
180	memmove(dst, src, movelen);
181	skb_reset_mac_header(skb);
182
183	hsr_fill_tag(skb, frame, port, port->hsr->protVersion);
184
185	return skb;
186}
187
188/* If the original frame was an HSR tagged frame, just clone it to be sent
189 * unchanged. Otherwise, create a private frame especially tagged for 'port'.
190 */
191static struct sk_buff *frame_get_tagged_skb(struct hsr_frame_info *frame,
192					    struct hsr_port *port)
193{
194	if (frame->skb_hsr)
195		return skb_clone(frame->skb_hsr, GFP_ATOMIC);
196
197	if ((port->type != HSR_PT_SLAVE_A) && (port->type != HSR_PT_SLAVE_B)) {
198		WARN_ONCE(1, "HSR: Bug: trying to create a tagged frame for a non-ring port");
199		return NULL;
200	}
201
202	return create_tagged_skb(frame->skb_std, frame, port);
203}
204
205
206static void hsr_deliver_master(struct sk_buff *skb, struct net_device *dev,
207			       struct hsr_node *node_src)
208{
209	bool was_multicast_frame;
210	int res;
211
212	was_multicast_frame = (skb->pkt_type == PACKET_MULTICAST);
213	hsr_addr_subst_source(node_src, skb);
214	skb_pull(skb, ETH_HLEN);
215	res = netif_rx(skb);
216	if (res == NET_RX_DROP) {
217		dev->stats.rx_dropped++;
218	} else {
219		dev->stats.rx_packets++;
220		dev->stats.rx_bytes += skb->len;
221		if (was_multicast_frame)
222			dev->stats.multicast++;
223	}
224}
225
226static int hsr_xmit(struct sk_buff *skb, struct hsr_port *port,
227		    struct hsr_frame_info *frame)
228{
229	if (frame->port_rcv->type == HSR_PT_MASTER) {
230		hsr_addr_subst_dest(frame->node_src, skb, port);
231
232		/* Address substitution (IEC62439-3 pp 26, 50): replace mac
233		 * address of outgoing frame with that of the outgoing slave's.
234		 */
235		ether_addr_copy(eth_hdr(skb)->h_source, port->dev->dev_addr);
236	}
237	return dev_queue_xmit(skb);
238}
239
240
241/* Forward the frame through all devices except:
242 * - Back through the receiving device
243 * - If it's a HSR frame: through a device where it has passed before
244 * - To the local HSR master only if the frame is directly addressed to it, or
245 *   a non-supervision multicast or broadcast frame.
246 *
247 * HSR slave devices should insert a HSR tag into the frame, or forward the
248 * frame unchanged if it's already tagged. Interlink devices should strip HSR
249 * tags if they're of the non-HSR type (but only after duplicate discard). The
250 * master device always strips HSR tags.
251 */
252static void hsr_forward_do(struct hsr_frame_info *frame)
253{
254	struct hsr_port *port;
255	struct sk_buff *skb;
256
257	hsr_for_each_port(frame->port_rcv->hsr, port) {
258		/* Don't send frame back the way it came */
259		if (port == frame->port_rcv)
260			continue;
261
262		/* Don't deliver locally unless we should */
263		if ((port->type == HSR_PT_MASTER) && !frame->is_local_dest)
264			continue;
265
266		/* Deliver frames directly addressed to us to master only */
267		if ((port->type != HSR_PT_MASTER) && frame->is_local_exclusive)
268			continue;
269
270		/* Don't send frame over port where it has been sent before */
271		if (hsr_register_frame_out(port, frame->node_src,
272					   frame->sequence_nr))
273			continue;
274
275		if (frame->is_supervision && (port->type == HSR_PT_MASTER)) {
276			hsr_handle_sup_frame(frame->skb_hsr,
277					     frame->node_src,
278					     frame->port_rcv);
279			continue;
280		}
281
282		if (port->type != HSR_PT_MASTER)
283			skb = frame_get_tagged_skb(frame, port);
284		else
285			skb = frame_get_stripped_skb(frame, port);
286		if (skb == NULL) {
287			/* FIXME: Record the dropped frame? */
288			continue;
289		}
290
291		skb->dev = port->dev;
292		if (port->type == HSR_PT_MASTER)
293			hsr_deliver_master(skb, port->dev, frame->node_src);
294		else
295			hsr_xmit(skb, port, frame);
296	}
297}
298
299
300static void check_local_dest(struct hsr_priv *hsr, struct sk_buff *skb,
301			     struct hsr_frame_info *frame)
302{
303	if (hsr_addr_is_self(hsr, eth_hdr(skb)->h_dest)) {
304		frame->is_local_exclusive = true;
305		skb->pkt_type = PACKET_HOST;
306	} else {
307		frame->is_local_exclusive = false;
308	}
309
310	if ((skb->pkt_type == PACKET_HOST) ||
311	    (skb->pkt_type == PACKET_MULTICAST) ||
312	    (skb->pkt_type == PACKET_BROADCAST)) {
313		frame->is_local_dest = true;
314	} else {
315		frame->is_local_dest = false;
316	}
317}
318
319
320static int hsr_fill_frame_info(struct hsr_frame_info *frame,
321			       struct sk_buff *skb, struct hsr_port *port)
322{
323	struct ethhdr *ethhdr;
324	unsigned long irqflags;
325
326	frame->is_supervision = is_supervision_frame(port->hsr, skb);
327	frame->node_src = hsr_get_node(port, skb, frame->is_supervision);
328	if (frame->node_src == NULL)
329		return -1; /* Unknown node and !is_supervision, or no mem */
330
331	ethhdr = (struct ethhdr *) skb_mac_header(skb);
332	frame->is_vlan = false;
333	if (ethhdr->h_proto == htons(ETH_P_8021Q)) {
334		frame->is_vlan = true;
335		/* FIXME: */
336		WARN_ONCE(1, "HSR: VLAN not yet supported");
337	}
338	if (ethhdr->h_proto == htons(ETH_P_PRP)
339			|| ethhdr->h_proto == htons(ETH_P_HSR)) {
340		frame->skb_std = NULL;
341		frame->skb_hsr = skb;
342		frame->sequence_nr = hsr_get_skb_sequence_nr(skb);
343	} else {
344		frame->skb_std = skb;
345		frame->skb_hsr = NULL;
346		/* Sequence nr for the master node */
347		spin_lock_irqsave(&port->hsr->seqnr_lock, irqflags);
348		frame->sequence_nr = port->hsr->sequence_nr;
349		port->hsr->sequence_nr++;
350		spin_unlock_irqrestore(&port->hsr->seqnr_lock, irqflags);
351	}
352
353	frame->port_rcv = port;
354	check_local_dest(port->hsr, skb, frame);
355
356	return 0;
357}
358
359/* Must be called holding rcu read lock (because of the port parameter) */
360void hsr_forward_skb(struct sk_buff *skb, struct hsr_port *port)
361{
362	struct hsr_frame_info frame;
363
364	if (skb_mac_header(skb) != skb->data) {
365		WARN_ONCE(1, "%s:%d: Malformed frame (port_src %s)\n",
366			  __FILE__, __LINE__, port->dev->name);
367		goto out_drop;
368	}
369
370	if (hsr_fill_frame_info(&frame, skb, port) < 0)
371		goto out_drop;
372	hsr_register_frame_in(frame.node_src, port, frame.sequence_nr);
373	hsr_forward_do(&frame);
374
375	if (frame.skb_hsr != NULL)
376		kfree_skb(frame.skb_hsr);
377	if (frame.skb_std != NULL)
378		kfree_skb(frame.skb_std);
379	return;
380
381out_drop:
382	port->dev->stats.tx_dropped++;
383	kfree_skb(skb);
384}