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 }; 125 126 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 unsigned int bridge_num = dsa_port_bridge_num_get(dp); 136 struct dsa_switch_tree *dst = dp->ds->dst; 137 138 cmd = DSA_CMD_FORWARD; 139 140 /* When offloading forwarding for a bridge, inject FORWARD 141 * packets on behalf of a virtual switch device with an index 142 * past the physical switches. 143 */ 144 tag_dev = dst->last_switch + bridge_num; 145 tag_port = 0; 146 } else { 147 cmd = DSA_CMD_FROM_CPU; 148 tag_dev = dp->ds->index; 149 tag_port = dp->index; 150 } 151 152 if (skb->protocol == htons(ETH_P_8021Q)) { 153 if (extra) { 154 skb_push(skb, extra); 155 dsa_alloc_etype_header(skb, extra); 156 } 157 158 /* Construct tagged DSA tag from 802.1Q tag. */ 159 dsa_header = dsa_etype_header_pos_tx(skb) + extra; 160 dsa_header[0] = (cmd << 6) | 0x20 | tag_dev; 161 dsa_header[1] = tag_port << 3; 162 163 /* Move CFI field from byte 2 to byte 1. */ 164 if (dsa_header[2] & 0x10) { 165 dsa_header[1] |= 0x01; 166 dsa_header[2] &= ~0x10; 167 } 168 } else { 169 struct net_device *br = dsa_port_bridge_dev_get(dp); 170 u16 vid; 171 172 vid = br ? MV88E6XXX_VID_BRIDGED : MV88E6XXX_VID_STANDALONE; 173 174 skb_push(skb, DSA_HLEN + extra); 175 dsa_alloc_etype_header(skb, DSA_HLEN + extra); 176 177 /* Construct DSA header from untagged frame. */ 178 dsa_header = dsa_etype_header_pos_tx(skb) + extra; 179 180 dsa_header[0] = (cmd << 6) | tag_dev; 181 dsa_header[1] = tag_port << 3; 182 dsa_header[2] = vid >> 8; 183 dsa_header[3] = vid & 0xff; 184 } 185 186 return skb; 187 } 188 189 static struct sk_buff *dsa_rcv_ll(struct sk_buff *skb, struct net_device *dev, 190 u8 extra) 191 { 192 bool trap = false, trunk = false; 193 int source_device, source_port; 194 enum dsa_code code; 195 enum dsa_cmd cmd; 196 u8 *dsa_header; 197 198 /* The ethertype field is part of the DSA header. */ 199 dsa_header = dsa_etype_header_pos_rx(skb); 200 201 cmd = dsa_header[0] >> 6; 202 switch (cmd) { 203 case DSA_CMD_FORWARD: 204 trunk = !!(dsa_header[1] & 4); 205 break; 206 207 case DSA_CMD_TO_CPU: 208 code = (dsa_header[1] & 0x6) | ((dsa_header[2] >> 4) & 1); 209 210 switch (code) { 211 case DSA_CODE_FRAME2REG: 212 /* Remote management is not implemented yet, 213 * drop. 214 */ 215 return NULL; 216 case DSA_CODE_ARP_MIRROR: 217 case DSA_CODE_POLICY_MIRROR: 218 /* Mark mirrored packets to notify any upper 219 * device (like a bridge) that forwarding has 220 * already been done by hardware. 221 */ 222 break; 223 case DSA_CODE_MGMT_TRAP: 224 case DSA_CODE_IGMP_MLD_TRAP: 225 case DSA_CODE_POLICY_TRAP: 226 /* Traps have, by definition, not been 227 * forwarded by hardware, so don't mark them. 228 */ 229 trap = true; 230 break; 231 default: 232 /* Reserved code, this could be anything. Drop 233 * seems like the safest option. 234 */ 235 return NULL; 236 } 237 238 break; 239 240 default: 241 return NULL; 242 } 243 244 source_device = dsa_header[0] & 0x1f; 245 source_port = (dsa_header[1] >> 3) & 0x1f; 246 247 if (trunk) { 248 struct dsa_port *cpu_dp = dev->dsa_ptr; 249 250 /* The exact source port is not available in the tag, 251 * so we inject the frame directly on the upper 252 * team/bond. 253 */ 254 skb->dev = dsa_lag_dev(cpu_dp->dst, source_port); 255 } else { 256 skb->dev = dsa_master_find_slave(dev, source_device, 257 source_port); 258 } 259 260 if (!skb->dev) 261 return NULL; 262 263 /* When using LAG offload, skb->dev is not a DSA slave interface, 264 * so we cannot call dsa_default_offload_fwd_mark and we need to 265 * special-case it. 266 */ 267 if (trunk) 268 skb->offload_fwd_mark = true; 269 else if (!trap) 270 dsa_default_offload_fwd_mark(skb); 271 272 /* If the 'tagged' bit is set; convert the DSA tag to a 802.1Q 273 * tag, and delete the ethertype (extra) if applicable. If the 274 * 'tagged' bit is cleared; delete the DSA tag, and ethertype 275 * if applicable. 276 */ 277 if (dsa_header[0] & 0x20) { 278 u8 new_header[4]; 279 280 /* Insert 802.1Q ethertype and copy the VLAN-related 281 * fields, but clear the bit that will hold CFI (since 282 * DSA uses that bit location for another purpose). 283 */ 284 new_header[0] = (ETH_P_8021Q >> 8) & 0xff; 285 new_header[1] = ETH_P_8021Q & 0xff; 286 new_header[2] = dsa_header[2] & ~0x10; 287 new_header[3] = dsa_header[3]; 288 289 /* Move CFI bit from its place in the DSA header to 290 * its 802.1Q-designated place. 291 */ 292 if (dsa_header[1] & 0x01) 293 new_header[2] |= 0x10; 294 295 /* Update packet checksum if skb is CHECKSUM_COMPLETE. */ 296 if (skb->ip_summed == CHECKSUM_COMPLETE) { 297 __wsum c = skb->csum; 298 c = csum_add(c, csum_partial(new_header + 2, 2, 0)); 299 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0)); 300 skb->csum = c; 301 } 302 303 memcpy(dsa_header, new_header, DSA_HLEN); 304 305 if (extra) 306 dsa_strip_etype_header(skb, extra); 307 } else { 308 skb_pull_rcsum(skb, DSA_HLEN); 309 dsa_strip_etype_header(skb, DSA_HLEN + extra); 310 } 311 312 return skb; 313 } 314 315 #if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA) 316 317 static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev) 318 { 319 return dsa_xmit_ll(skb, dev, 0); 320 } 321 322 static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev) 323 { 324 if (unlikely(!pskb_may_pull(skb, DSA_HLEN))) 325 return NULL; 326 327 return dsa_rcv_ll(skb, dev, 0); 328 } 329 330 static const struct dsa_device_ops dsa_netdev_ops = { 331 .name = "dsa", 332 .proto = DSA_TAG_PROTO_DSA, 333 .xmit = dsa_xmit, 334 .rcv = dsa_rcv, 335 .needed_headroom = DSA_HLEN, 336 }; 337 338 DSA_TAG_DRIVER(dsa_netdev_ops); 339 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_DSA); 340 #endif /* CONFIG_NET_DSA_TAG_DSA */ 341 342 #if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA) 343 344 #define EDSA_HLEN 8 345 346 static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev) 347 { 348 u8 *edsa_header; 349 350 skb = dsa_xmit_ll(skb, dev, EDSA_HLEN - DSA_HLEN); 351 if (!skb) 352 return NULL; 353 354 edsa_header = dsa_etype_header_pos_tx(skb); 355 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff; 356 edsa_header[1] = ETH_P_EDSA & 0xff; 357 edsa_header[2] = 0x00; 358 edsa_header[3] = 0x00; 359 return skb; 360 } 361 362 static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev) 363 { 364 if (unlikely(!pskb_may_pull(skb, EDSA_HLEN))) 365 return NULL; 366 367 skb_pull_rcsum(skb, EDSA_HLEN - DSA_HLEN); 368 369 return dsa_rcv_ll(skb, dev, EDSA_HLEN - DSA_HLEN); 370 } 371 372 static const struct dsa_device_ops edsa_netdev_ops = { 373 .name = "edsa", 374 .proto = DSA_TAG_PROTO_EDSA, 375 .xmit = edsa_xmit, 376 .rcv = edsa_rcv, 377 .needed_headroom = EDSA_HLEN, 378 }; 379 380 DSA_TAG_DRIVER(edsa_netdev_ops); 381 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA); 382 #endif /* CONFIG_NET_DSA_TAG_EDSA */ 383 384 static struct dsa_tag_driver *dsa_tag_drivers[] = { 385 #if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA) 386 &DSA_TAG_DRIVER_NAME(dsa_netdev_ops), 387 #endif 388 #if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA) 389 &DSA_TAG_DRIVER_NAME(edsa_netdev_ops), 390 #endif 391 }; 392 393 module_dsa_tag_drivers(dsa_tag_drivers); 394 395 MODULE_LICENSE("GPL"); 396