net/dsa/tag_dsa.c

0001 // SPDX-License-Identifier: GPL-2.0+
0002 /*
0003  * Regular and Ethertype DSA tagging
0004  * Copyright (c) 2008-2009 Marvell Semiconductor
0005  *
0006  * Regular DSA
0007  * -----------
0008
0009  * For untagged (in 802.1Q terms) packets, the switch will splice in
0010  * the tag between the SA and the ethertype of the original
0011  * packet. Tagged frames will instead have their outermost .1Q tag
0012  * converted to a DSA tag. It expects the same layout when receiving
0013  * packets from the CPU.
0014  *
0015  * Example:
0016  *
0017  *     .----.----.----.---------
0018  * Pu: | DA | SA | ET | Payload ...
0019  *     '----'----'----'---------
0020  *       6    6    2       N
0021  *     .----.----.--------.-----.----.---------
0022  * Pt: | DA | SA | 0x8100 | TCI | ET | Payload ...
0023  *     '----'----'--------'-----'----'---------
0024  *       6    6       2      2    2       N
0025  *     .----.----.-----.----.---------
0026  * Pd: | DA | SA | DSA | ET | Payload ...
0027  *     '----'----'-----'----'---------
0028  *       6    6     4    2       N
0029  *
0030  * No matter if a packet is received untagged (Pu) or tagged (Pt),
0031  * they will both have the same layout (Pd) when they are sent to the
0032  * CPU. This is done by ignoring 802.3, replacing the ethertype field
0033  * with more metadata, among which is a bit to signal if the original
0034  * packet was tagged or not.
0035  *
0036  * Ethertype DSA
0037  * -------------
0038  * Uses the exact same tag format as regular DSA, but also includes a
0039  * proper ethertype field (which the mv88e6xxx driver sets to
0040  * ETH_P_EDSA/0xdada) followed by two zero bytes:
0041  *
0042  * .----.----.--------.--------.-----.----.---------
0043  * | DA | SA | 0xdada | 0x0000 | DSA | ET | Payload ...
0044  * '----'----'--------'--------'-----'----'---------
0045  *   6    6       2        2      4    2       N
0046  */
0047
0048 #include <linux/dsa/mv88e6xxx.h>
0049 #include <linux/etherdevice.h>
0050 #include <linux/list.h>
0051 #include <linux/slab.h>
0052
0053 #include "dsa_priv.h"
0054
0055 #define DSA_HLEN    4
0056
0057 /**
0058  * enum dsa_cmd - DSA Command
0059  * @DSA_CMD_TO_CPU: Set on packets that were trapped or mirrored to
0060  *     the CPU port. This is needed to implement control protocols,
0061  *     e.g. STP and LLDP, that must not allow those control packets to
0062  *     be switched according to the normal rules.
0063  * @DSA_CMD_FROM_CPU: Used by the CPU to send a packet to a specific
0064  *     port, ignoring all the barriers that the switch normally
0065  *     enforces (VLANs, STP port states etc.). No source address
0066  *     learning takes place. "sudo send packet"
0067  * @DSA_CMD_TO_SNIFFER: Set on the copies of packets that matched some
0068  *     user configured ingress or egress monitor criteria. These are
0069  *     forwarded by the switch tree to the user configured ingress or
0070  *     egress monitor port, which can be set to the CPU port or a
0071  *     regular port. If the destination is a regular port, the tag
0072  *     will be removed before egressing the port. If the destination
0073  *     is the CPU port, the tag will not be removed.
0074  * @DSA_CMD_FORWARD: This tag is used on all bulk traffic passing
0075  *     through the switch tree, including the flows that are directed
0076  *     towards the CPU. Its device/port tuple encodes the original
0077  *     source port on which the packet ingressed. It can also be used
0078  *     on transmit by the CPU to defer the forwarding decision to the
0079  *     hardware, based on the current config of PVT/VTU/ATU
0080  *     etc. Source address learning takes places if enabled on the
0081  *     receiving DSA/CPU port.
0082  */
0083 enum dsa_cmd {
0084     DSA_CMD_TO_CPU     = 0,
0085     DSA_CMD_FROM_CPU   = 1,
0086     DSA_CMD_TO_SNIFFER = 2,
0087     DSA_CMD_FORWARD    = 3
0088 };
0089
0090 /**
0091  * enum dsa_code - TO_CPU Code
0092  *
0093  * @DSA_CODE_MGMT_TRAP: DA was classified as a management
0094  *     address. Typical examples include STP BPDUs and LLDP.
0095  * @DSA_CODE_FRAME2REG: Response to a "remote management" request.
0096  * @DSA_CODE_IGMP_MLD_TRAP: IGMP/MLD signaling.
0097  * @DSA_CODE_POLICY_TRAP: Frame matched some policy configuration on
0098  *     the device. Typical examples are matching on DA/SA/VID and DHCP
0099  *     snooping.
0100  * @DSA_CODE_ARP_MIRROR: The name says it all really.
0101  * @DSA_CODE_POLICY_MIRROR: Same as @DSA_CODE_POLICY_TRAP, but the
0102  *     particular policy was set to trigger a mirror instead of a
0103  *     trap.
0104  * @DSA_CODE_RESERVED_6: Unused on all devices up to at least 6393X.
0105  * @DSA_CODE_RESERVED_7: Unused on all devices up to at least 6393X.
0106  *
0107  * A 3-bit code is used to relay why a particular frame was sent to
0108  * the CPU. We only use this to determine if the packet was mirrored
0109  * or trapped, i.e. whether the packet has been forwarded by hardware
0110  * or not.
0111  *
0112  * This is the superset of all possible codes. Any particular device
0113  * may only implement a subset.
0114  */
0115 enum dsa_code {
0116     DSA_CODE_MGMT_TRAP     = 0,
0117     DSA_CODE_FRAME2REG     = 1,
0118     DSA_CODE_IGMP_MLD_TRAP = 2,
0119     DSA_CODE_POLICY_TRAP   = 3,
0120     DSA_CODE_ARP_MIRROR    = 4,
0121     DSA_CODE_POLICY_MIRROR = 5,
0122     DSA_CODE_RESERVED_6    = 6,
0123     DSA_CODE_RESERVED_7    = 7
0124 };
0125
0126 static struct sk_buff *dsa_xmit_ll(struct sk_buff *skb, struct net_device *dev,
0127                    u8 extra)
0128 {
0129     struct dsa_port *dp = dsa_slave_to_port(dev);
0130     struct net_device *br_dev;
0131     u8 tag_dev, tag_port;
0132     enum dsa_cmd cmd;
0133     u8 *dsa_header;
0134
0135     if (skb->offload_fwd_mark) {
0136         unsigned int bridge_num = dsa_port_bridge_num_get(dp);
0137         struct dsa_switch_tree *dst = dp->ds->dst;
0138
0139         cmd = DSA_CMD_FORWARD;
0140
0141         /* When offloading forwarding for a bridge, inject FORWARD
0142          * packets on behalf of a virtual switch device with an index
0143          * past the physical switches.
0144          */
0145         tag_dev = dst->last_switch + bridge_num;
0146         tag_port = 0;
0147     } else {
0148         cmd = DSA_CMD_FROM_CPU;
0149         tag_dev = dp->ds->index;
0150         tag_port = dp->index;
0151     }
0152
0153     br_dev = dsa_port_bridge_dev_get(dp);
0154
0155     /* If frame is already 802.1Q tagged, we can convert it to a DSA
0156      * tag (avoiding a memmove), but only if the port is standalone
0157      * (in which case we always send FROM_CPU) or if the port's
0158      * bridge has VLAN filtering enabled (in which case the CPU port
0159      * will be a member of the VLAN).
0160      */
0161     if (skb->protocol == htons(ETH_P_8021Q) &&
0162         (!br_dev || br_vlan_enabled(br_dev))) {
0163         if (extra) {
0164             skb_push(skb, extra);
0165             dsa_alloc_etype_header(skb, extra);
0166         }
0167
0168         /* Construct tagged DSA tag from 802.1Q tag. */
0169         dsa_header = dsa_etype_header_pos_tx(skb) + extra;
0170         dsa_header[0] = (cmd << 6) | 0x20 | tag_dev;
0171         dsa_header[1] = tag_port << 3;
0172
0173         /* Move CFI field from byte 2 to byte 1. */
0174         if (dsa_header[2] & 0x10) {
0175             dsa_header[1] |= 0x01;
0176             dsa_header[2] &= ~0x10;
0177         }
0178     } else {
0179         u16 vid;
0180
0181         vid = br_dev ? MV88E6XXX_VID_BRIDGED : MV88E6XXX_VID_STANDALONE;
0182
0183         skb_push(skb, DSA_HLEN + extra);
0184         dsa_alloc_etype_header(skb, DSA_HLEN + extra);
0185
0186         /* Construct DSA header from untagged frame. */
0187         dsa_header = dsa_etype_header_pos_tx(skb) + extra;
0188
0189         dsa_header[0] = (cmd << 6) | tag_dev;
0190         dsa_header[1] = tag_port << 3;
0191         dsa_header[2] = vid >> 8;
0192         dsa_header[3] = vid & 0xff;
0193     }
0194
0195     return skb;
0196 }
0197
0198 static struct sk_buff *dsa_rcv_ll(struct sk_buff *skb, struct net_device *dev,
0199                   u8 extra)
0200 {
0201     bool trap = false, trunk = false;
0202     int source_device, source_port;
0203     enum dsa_code code;
0204     enum dsa_cmd cmd;
0205     u8 *dsa_header;
0206
0207     /* The ethertype field is part of the DSA header. */
0208     dsa_header = dsa_etype_header_pos_rx(skb);
0209
0210     cmd = dsa_header[0] >> 6;
0211     switch (cmd) {
0212     case DSA_CMD_FORWARD:
0213         trunk = !!(dsa_header[1] & 4);
0214         break;
0215
0216     case DSA_CMD_TO_CPU:
0217         code = (dsa_header[1] & 0x6) | ((dsa_header[2] >> 4) & 1);
0218
0219         switch (code) {
0220         case DSA_CODE_FRAME2REG:
0221             /* Remote management is not implemented yet,
0222              * drop.
0223              */
0224             return NULL;
0225         case DSA_CODE_ARP_MIRROR:
0226         case DSA_CODE_POLICY_MIRROR:
0227             /* Mark mirrored packets to notify any upper
0228              * device (like a bridge) that forwarding has
0229              * already been done by hardware.
0230              */
0231             break;
0232         case DSA_CODE_MGMT_TRAP:
0233         case DSA_CODE_IGMP_MLD_TRAP:
0234         case DSA_CODE_POLICY_TRAP:
0235             /* Traps have, by definition, not been
0236              * forwarded by hardware, so don't mark them.
0237              */
0238             trap = true;
0239             break;
0240         default:
0241             /* Reserved code, this could be anything. Drop
0242              * seems like the safest option.
0243              */
0244             return NULL;
0245         }
0246
0247         break;
0248
0249     default:
0250         return NULL;
0251     }
0252
0253     source_device = dsa_header[0] & 0x1f;
0254     source_port = (dsa_header[1] >> 3) & 0x1f;
0255
0256     if (trunk) {
0257         struct dsa_port *cpu_dp = dev->dsa_ptr;
0258         struct dsa_lag *lag;
0259
0260         /* The exact source port is not available in the tag,
0261          * so we inject the frame directly on the upper
0262          * team/bond.
0263          */
0264         lag = dsa_lag_by_id(cpu_dp->dst, source_port + 1);
0265         skb->dev = lag ? lag->dev : NULL;
0266     } else {
0267         skb->dev = dsa_master_find_slave(dev, source_device,
0268                          source_port);
0269     }
0270
0271     if (!skb->dev)
0272         return NULL;
0273
0274     /* When using LAG offload, skb->dev is not a DSA slave interface,
0275      * so we cannot call dsa_default_offload_fwd_mark and we need to
0276      * special-case it.
0277      */
0278     if (trunk)
0279         skb->offload_fwd_mark = true;
0280     else if (!trap)
0281         dsa_default_offload_fwd_mark(skb);
0282
0283     /* If the 'tagged' bit is set; convert the DSA tag to a 802.1Q
0284      * tag, and delete the ethertype (extra) if applicable. If the
0285      * 'tagged' bit is cleared; delete the DSA tag, and ethertype
0286      * if applicable.
0287      */
0288     if (dsa_header[0] & 0x20) {
0289         u8 new_header[4];
0290
0291         /* Insert 802.1Q ethertype and copy the VLAN-related
0292          * fields, but clear the bit that will hold CFI (since
0293          * DSA uses that bit location for another purpose).
0294          */
0295         new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
0296         new_header[1] = ETH_P_8021Q & 0xff;
0297         new_header[2] = dsa_header[2] & ~0x10;
0298         new_header[3] = dsa_header[3];
0299
0300         /* Move CFI bit from its place in the DSA header to
0301          * its 802.1Q-designated place.
0302          */
0303         if (dsa_header[1] & 0x01)
0304             new_header[2] |= 0x10;
0305
0306         /* Update packet checksum if skb is CHECKSUM_COMPLETE. */
0307         if (skb->ip_summed == CHECKSUM_COMPLETE) {
0308             __wsum c = skb->csum;
0309             c = csum_add(c, csum_partial(new_header + 2, 2, 0));
0310             c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
0311             skb->csum = c;
0312         }
0313
0314         memcpy(dsa_header, new_header, DSA_HLEN);
0315
0316         if (extra)
0317             dsa_strip_etype_header(skb, extra);
0318     } else {
0319         skb_pull_rcsum(skb, DSA_HLEN);
0320         dsa_strip_etype_header(skb, DSA_HLEN + extra);
0321     }
0322
0323     return skb;
0324 }
0325
0326 #if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA)
0327
0328 static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
0329 {
0330     return dsa_xmit_ll(skb, dev, 0);
0331 }
0332
0333 static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev)
0334 {
0335     if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
0336         return NULL;
0337
0338     return dsa_rcv_ll(skb, dev, 0);
0339 }
0340
0341 static const struct dsa_device_ops dsa_netdev_ops = {
0342     .name     = "dsa",
0343     .proto    = DSA_TAG_PROTO_DSA,
0344     .xmit     = dsa_xmit,
0345     .rcv      = dsa_rcv,
0346     .needed_headroom = DSA_HLEN,
0347 };
0348
0349 DSA_TAG_DRIVER(dsa_netdev_ops);
0350 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_DSA);
0351 #endif  /* CONFIG_NET_DSA_TAG_DSA */
0352
0353 #if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA)
0354
0355 #define EDSA_HLEN 8
0356
0357 static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
0358 {
0359     u8 *edsa_header;
0360
0361     skb = dsa_xmit_ll(skb, dev, EDSA_HLEN - DSA_HLEN);
0362     if (!skb)
0363         return NULL;
0364
0365     edsa_header = dsa_etype_header_pos_tx(skb);
0366     edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
0367     edsa_header[1] = ETH_P_EDSA & 0xff;
0368     edsa_header[2] = 0x00;
0369     edsa_header[3] = 0x00;
0370     return skb;
0371 }
0372
0373 static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev)
0374 {
0375     if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
0376         return NULL;
0377
0378     skb_pull_rcsum(skb, EDSA_HLEN - DSA_HLEN);
0379
0380     return dsa_rcv_ll(skb, dev, EDSA_HLEN - DSA_HLEN);
0381 }
0382
0383 static const struct dsa_device_ops edsa_netdev_ops = {
0384     .name     = "edsa",
0385     .proto    = DSA_TAG_PROTO_EDSA,
0386     .xmit     = edsa_xmit,
0387     .rcv      = edsa_rcv,
0388     .needed_headroom = EDSA_HLEN,
0389 };
0390
0391 DSA_TAG_DRIVER(edsa_netdev_ops);
0392 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA);
0393 #endif  /* CONFIG_NET_DSA_TAG_EDSA */
0394
0395 static struct dsa_tag_driver *dsa_tag_drivers[] = {
0396 #if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA)
0397     &DSA_TAG_DRIVER_NAME(dsa_netdev_ops),
0398 #endif
0399 #if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA)
0400     &DSA_TAG_DRIVER_NAME(edsa_netdev_ops),
0401 #endif
0402 };
0403
0404 module_dsa_tag_drivers(dsa_tag_drivers);
0405
0406 MODULE_LICENSE("GPL");