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