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 }; 128 129 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 } 200 201 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) 330 331 static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev) 332 { 333 return dsa_xmit_ll(skb, dev, 0); 334 } 335 336 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 8 359 360 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 } 375 376 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