1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Regular and Ethertype DSA tagging
4 * Copyright (c) 2008-2009 Marvell Semiconductor
5 *
6 * Regular DSA
7 * -----------
8
9 * For untagged (in 802.1Q terms) packets, the switch will splice in
10 * the tag between the SA and the ethertype of the original
11 * packet. Tagged frames will instead have their outermost .1Q tag
12 * converted to a DSA tag. It expects the same layout when receiving
13 * packets from the CPU.
14 *
15 * Example:
16 *
17 * .----.----.----.---------
18 * Pu: | DA | SA | ET | Payload ...
19 * '----'----'----'---------
20 * 6 6 2 N
21 * .----.----.--------.-----.----.---------
22 * Pt: | DA | SA | 0x8100 | TCI | ET | Payload ...
23 * '----'----'--------'-----'----'---------
24 * 6 6 2 2 2 N
25 * .----.----.-----.----.---------
26 * Pd: | DA | SA | DSA | ET | Payload ...
27 * '----'----'-----'----'---------
28 * 6 6 4 2 N
29 *
30 * No matter if a packet is received untagged (Pu) or tagged (Pt),
31 * they will both have the same layout (Pd) when they are sent to the
32 * CPU. This is done by ignoring 802.3, replacing the ethertype field
33 * with more metadata, among which is a bit to signal if the original
34 * packet was tagged or not.
35 *
36 * Ethertype DSA
37 * -------------
38 * Uses the exact same tag format as regular DSA, but also includes a
39 * proper ethertype field (which the mv88e6xxx driver sets to
40 * ETH_P_EDSA/0xdada) followed by two zero bytes:
41 *
42 * .----.----.--------.--------.-----.----.---------
43 * | DA | SA | 0xdada | 0x0000 | DSA | ET | Payload ...
44 * '----'----'--------'--------'-----'----'---------
45 * 6 6 2 2 4 2 N
46 */
47
48 #include <linux/dsa/mv88e6xxx.h>
49 #include <linux/etherdevice.h>
50 #include <linux/list.h>
51 #include <linux/slab.h>
52
53 #include "tag.h"
54
55 #define DSA_NAME "dsa"
56 #define EDSA_NAME "edsa"
57
58 #define DSA_HLEN 4
59
60 /**
61 * enum dsa_cmd - DSA Command
62 * @DSA_CMD_TO_CPU: Set on packets that were trapped or mirrored to
63 * the CPU port. This is needed to implement control protocols,
64 * e.g. STP and LLDP, that must not allow those control packets to
65 * be switched according to the normal rules.
66 * @DSA_CMD_FROM_CPU: Used by the CPU to send a packet to a specific
67 * port, ignoring all the barriers that the switch normally
68 * enforces (VLANs, STP port states etc.). No source address
69 * learning takes place. "sudo send packet"
70 * @DSA_CMD_TO_SNIFFER: Set on the copies of packets that matched some
71 * user configured ingress or egress monitor criteria. These are
72 * forwarded by the switch tree to the user configured ingress or
73 * egress monitor port, which can be set to the CPU port or a
74 * regular port. If the destination is a regular port, the tag
75 * will be removed before egressing the port. If the destination
76 * is the CPU port, the tag will not be removed.
77 * @DSA_CMD_FORWARD: This tag is used on all bulk traffic passing
78 * through the switch tree, including the flows that are directed
79 * towards the CPU. Its device/port tuple encodes the original
80 * source port on which the packet ingressed. It can also be used
81 * on transmit by the CPU to defer the forwarding decision to the
82 * hardware, based on the current config of PVT/VTU/ATU
83 * etc. Source address learning takes places if enabled on the
84 * receiving DSA/CPU port.
85 */
86 enum dsa_cmd {
87 DSA_CMD_TO_CPU = 0,
88 DSA_CMD_FROM_CPU = 1,
89 DSA_CMD_TO_SNIFFER = 2,
90 DSA_CMD_FORWARD = 3
91 };
92
93 /**
94 * enum dsa_code - TO_CPU Code
95 *
96 * @DSA_CODE_MGMT_TRAP: DA was classified as a management
97 * address. Typical examples include STP BPDUs and LLDP.
98 * @DSA_CODE_FRAME2REG: Response to a "remote management" request.
99 * @DSA_CODE_IGMP_MLD_TRAP: IGMP/MLD signaling.
100 * @DSA_CODE_POLICY_TRAP: Frame matched some policy configuration on
101 * the device. Typical examples are matching on DA/SA/VID and DHCP
102 * snooping.
103 * @DSA_CODE_ARP_MIRROR: The name says it all really.
104 * @DSA_CODE_POLICY_MIRROR: Same as @DSA_CODE_POLICY_TRAP, but the
105 * particular policy was set to trigger a mirror instead of a
106 * trap.
107 * @DSA_CODE_RESERVED_6: Unused on all devices up to at least 6393X.
108 * @DSA_CODE_RESERVED_7: Unused on all devices up to at least 6393X.
109 *
110 * A 3-bit code is used to relay why a particular frame was sent to
111 * the CPU. We only use this to determine if the packet was mirrored
112 * or trapped, i.e. whether the packet has been forwarded by hardware
113 * or not.
114 *
115 * This is the superset of all possible codes. Any particular device
116 * may only implement a subset.
117 */
118 enum dsa_code {
119 DSA_CODE_MGMT_TRAP = 0,
120 DSA_CODE_FRAME2REG = 1,
121 DSA_CODE_IGMP_MLD_TRAP = 2,
122 DSA_CODE_POLICY_TRAP = 3,
123 DSA_CODE_ARP_MIRROR = 4,
124 DSA_CODE_POLICY_MIRROR = 5,
125 DSA_CODE_RESERVED_6 = 6,
126 DSA_CODE_RESERVED_7 = 7
127 };
128
dsa_xmit_ll(struct sk_buff * skb,struct net_device * dev,u8 extra)129 static struct sk_buff *dsa_xmit_ll(struct sk_buff *skb, struct net_device *dev,
130 u8 extra)
131 {
132 struct dsa_port *dp = dsa_user_to_port(dev);
133 struct net_device *br_dev;
134 u8 tag_dev, tag_port;
135 enum dsa_cmd cmd;
136 u8 *dsa_header;
137
138 if (skb->offload_fwd_mark) {
139 unsigned int bridge_num = dsa_port_bridge_num_get(dp);
140 struct dsa_switch_tree *dst = dp->ds->dst;
141
142 cmd = DSA_CMD_FORWARD;
143
144 /* When offloading forwarding for a bridge, inject FORWARD
145 * packets on behalf of a virtual switch device with an index
146 * past the physical switches.
147 */
148 tag_dev = dst->last_switch + bridge_num;
149 tag_port = 0;
150 } else {
151 cmd = DSA_CMD_FROM_CPU;
152 tag_dev = dp->ds->index;
153 tag_port = dp->index;
154 }
155
156 br_dev = dsa_port_bridge_dev_get(dp);
157
158 /* If frame is already 802.1Q tagged, we can convert it to a DSA
159 * tag (avoiding a memmove), but only if the port is standalone
160 * (in which case we always send FROM_CPU) or if the port's
161 * bridge has VLAN filtering enabled (in which case the CPU port
162 * will be a member of the VLAN).
163 */
164 if (skb->protocol == htons(ETH_P_8021Q) &&
165 (!br_dev || br_vlan_enabled(br_dev))) {
166 if (extra) {
167 skb_push(skb, extra);
168 dsa_alloc_etype_header(skb, extra);
169 }
170
171 /* Construct tagged DSA tag from 802.1Q tag. */
172 dsa_header = dsa_etype_header_pos_tx(skb) + extra;
173 dsa_header[0] = (cmd << 6) | 0x20 | tag_dev;
174 dsa_header[1] = tag_port << 3;
175
176 /* Move CFI field from byte 2 to byte 1. */
177 if (dsa_header[2] & 0x10) {
178 dsa_header[1] |= 0x01;
179 dsa_header[2] &= ~0x10;
180 }
181 } else {
182 u16 vid;
183
184 vid = br_dev ? MV88E6XXX_VID_BRIDGED : MV88E6XXX_VID_STANDALONE;
185
186 skb_push(skb, DSA_HLEN + extra);
187 dsa_alloc_etype_header(skb, DSA_HLEN + extra);
188
189 /* Construct DSA header from untagged frame. */
190 dsa_header = dsa_etype_header_pos_tx(skb) + extra;
191
192 dsa_header[0] = (cmd << 6) | tag_dev;
193 dsa_header[1] = tag_port << 3;
194 dsa_header[2] = vid >> 8;
195 dsa_header[3] = vid & 0xff;
196 }
197
198 return skb;
199 }
200
dsa_rcv_ll(struct sk_buff * skb,struct net_device * dev,u8 extra)201 static struct sk_buff *dsa_rcv_ll(struct sk_buff *skb, struct net_device *dev,
202 u8 extra)
203 {
204 bool trap = false, trunk = false;
205 int source_device, source_port;
206 enum dsa_code code;
207 enum dsa_cmd cmd;
208 u8 *dsa_header;
209
210 /* The ethertype field is part of the DSA header. */
211 dsa_header = dsa_etype_header_pos_rx(skb);
212
213 cmd = dsa_header[0] >> 6;
214 switch (cmd) {
215 case DSA_CMD_FORWARD:
216 trunk = !!(dsa_header[1] & 4);
217 break;
218
219 case DSA_CMD_TO_CPU:
220 code = (dsa_header[1] & 0x6) | ((dsa_header[2] >> 4) & 1);
221
222 switch (code) {
223 case DSA_CODE_FRAME2REG:
224 /* Remote management is not implemented yet,
225 * drop.
226 */
227 return NULL;
228 case DSA_CODE_ARP_MIRROR:
229 case DSA_CODE_POLICY_MIRROR:
230 /* Mark mirrored packets to notify any upper
231 * device (like a bridge) that forwarding has
232 * already been done by hardware.
233 */
234 break;
235 case DSA_CODE_MGMT_TRAP:
236 case DSA_CODE_IGMP_MLD_TRAP:
237 case DSA_CODE_POLICY_TRAP:
238 /* Traps have, by definition, not been
239 * forwarded by hardware, so don't mark them.
240 */
241 trap = true;
242 break;
243 default:
244 /* Reserved code, this could be anything. Drop
245 * seems like the safest option.
246 */
247 return NULL;
248 }
249
250 break;
251
252 default:
253 return NULL;
254 }
255
256 source_device = dsa_header[0] & 0x1f;
257 source_port = (dsa_header[1] >> 3) & 0x1f;
258
259 if (trunk) {
260 struct dsa_port *cpu_dp = dev->dsa_ptr;
261 struct dsa_lag *lag;
262
263 /* The exact source port is not available in the tag,
264 * so we inject the frame directly on the upper
265 * team/bond.
266 */
267 lag = dsa_lag_by_id(cpu_dp->dst, source_port + 1);
268 skb->dev = lag ? lag->dev : NULL;
269 } else {
270 skb->dev = dsa_conduit_find_user(dev, source_device,
271 source_port);
272 }
273
274 if (!skb->dev)
275 return NULL;
276
277 /* When using LAG offload, skb->dev is not a DSA user interface,
278 * so we cannot call dsa_default_offload_fwd_mark and we need to
279 * special-case it.
280 */
281 if (trunk)
282 skb->offload_fwd_mark = true;
283 else if (!trap)
284 dsa_default_offload_fwd_mark(skb);
285
286 /* If the 'tagged' bit is set; convert the DSA tag to a 802.1Q
287 * tag, and delete the ethertype (extra) if applicable. If the
288 * 'tagged' bit is cleared; delete the DSA tag, and ethertype
289 * if applicable.
290 */
291 if (dsa_header[0] & 0x20) {
292 u8 new_header[4];
293
294 /* Insert 802.1Q ethertype and copy the VLAN-related
295 * fields, but clear the bit that will hold CFI (since
296 * DSA uses that bit location for another purpose).
297 */
298 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
299 new_header[1] = ETH_P_8021Q & 0xff;
300 new_header[2] = dsa_header[2] & ~0x10;
301 new_header[3] = dsa_header[3];
302
303 /* Move CFI bit from its place in the DSA header to
304 * its 802.1Q-designated place.
305 */
306 if (dsa_header[1] & 0x01)
307 new_header[2] |= 0x10;
308
309 /* Update packet checksum if skb is CHECKSUM_COMPLETE. */
310 if (skb->ip_summed == CHECKSUM_COMPLETE) {
311 __wsum c = skb->csum;
312 c = csum_add(c, csum_partial(new_header + 2, 2, 0));
313 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
314 skb->csum = c;
315 }
316
317 memcpy(dsa_header, new_header, DSA_HLEN);
318
319 if (extra)
320 dsa_strip_etype_header(skb, extra);
321 } else {
322 skb_pull_rcsum(skb, DSA_HLEN);
323 dsa_strip_etype_header(skb, DSA_HLEN + extra);
324 }
325
326 return skb;
327 }
328
329 #if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA)
330
dsa_xmit(struct sk_buff * skb,struct net_device * dev)331 static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
332 {
333 return dsa_xmit_ll(skb, dev, 0);
334 }
335
dsa_rcv(struct sk_buff * skb,struct net_device * dev)336 static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev)
337 {
338 if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
339 return NULL;
340
341 return dsa_rcv_ll(skb, dev, 0);
342 }
343
344 static const struct dsa_device_ops dsa_netdev_ops = {
345 .name = DSA_NAME,
346 .proto = DSA_TAG_PROTO_DSA,
347 .xmit = dsa_xmit,
348 .rcv = dsa_rcv,
349 .needed_headroom = DSA_HLEN,
350 };
351
352 DSA_TAG_DRIVER(dsa_netdev_ops);
353 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_DSA, DSA_NAME);
354 #endif /* CONFIG_NET_DSA_TAG_DSA */
355
356 #if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA)
357
358 #define EDSA_HLEN 8
359
edsa_xmit(struct sk_buff * skb,struct net_device * dev)360 static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
361 {
362 u8 *edsa_header;
363
364 skb = dsa_xmit_ll(skb, dev, EDSA_HLEN - DSA_HLEN);
365 if (!skb)
366 return NULL;
367
368 edsa_header = dsa_etype_header_pos_tx(skb);
369 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
370 edsa_header[1] = ETH_P_EDSA & 0xff;
371 edsa_header[2] = 0x00;
372 edsa_header[3] = 0x00;
373 return skb;
374 }
375
edsa_rcv(struct sk_buff * skb,struct net_device * dev)376 static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev)
377 {
378 if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
379 return NULL;
380
381 skb_pull_rcsum(skb, EDSA_HLEN - DSA_HLEN);
382
383 return dsa_rcv_ll(skb, dev, EDSA_HLEN - DSA_HLEN);
384 }
385
386 static const struct dsa_device_ops edsa_netdev_ops = {
387 .name = EDSA_NAME,
388 .proto = DSA_TAG_PROTO_EDSA,
389 .xmit = edsa_xmit,
390 .rcv = edsa_rcv,
391 .needed_headroom = EDSA_HLEN,
392 };
393
394 DSA_TAG_DRIVER(edsa_netdev_ops);
395 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA, EDSA_NAME);
396 #endif /* CONFIG_NET_DSA_TAG_EDSA */
397
398 static struct dsa_tag_driver *dsa_tag_drivers[] = {
399 #if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA)
400 &DSA_TAG_DRIVER_NAME(dsa_netdev_ops),
401 #endif
402 #if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA)
403 &DSA_TAG_DRIVER_NAME(edsa_netdev_ops),
404 #endif
405 };
406
407 module_dsa_tag_drivers(dsa_tag_drivers);
408
409 MODULE_DESCRIPTION("DSA tag driver for Marvell switches using DSA headers");
410 MODULE_LICENSE("GPL");
411