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