// SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2019, Vladimir Oltean * * This module is not a complete tagger implementation. It only provides * primitives for taggers that rely on 802.1Q VLAN tags to use. The * dsa_8021q_netdev_ops is registered for API compliance and not used * directly by callers. */ #include #include #include "dsa_priv.h" /* Binary structure of the fake 12-bit VID field (when the TPID is * ETH_P_DSA_8021Q): * * | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | * +-----------+-----+-----------------+-----------+-----------------------+ * | DIR | RSV | SWITCH_ID | RSV | PORT | * +-----------+-----+-----------------+-----------+-----------------------+ * * DIR - VID[11:10]: * Direction flags. * * 1 (0b01) for RX VLAN, * * 2 (0b10) for TX VLAN. * These values make the special VIDs of 0, 1 and 4095 to be left * unused by this coding scheme. * * RSV - VID[9]: * To be used for further expansion of SWITCH_ID or for other purposes. * * SWITCH_ID - VID[8:6]: * Index of switch within DSA tree. Must be between 0 and * DSA_MAX_SWITCHES - 1. * * RSV - VID[5:4]: * To be used for further expansion of PORT or for other purposes. * * PORT - VID[3:0]: * Index of switch port. Must be between 0 and DSA_MAX_PORTS - 1. */ #define DSA_8021Q_DIR_SHIFT 10 #define DSA_8021Q_DIR_MASK GENMASK(11, 10) #define DSA_8021Q_DIR(x) (((x) << DSA_8021Q_DIR_SHIFT) & \ DSA_8021Q_DIR_MASK) #define DSA_8021Q_DIR_RX DSA_8021Q_DIR(1) #define DSA_8021Q_DIR_TX DSA_8021Q_DIR(2) #define DSA_8021Q_SWITCH_ID_SHIFT 6 #define DSA_8021Q_SWITCH_ID_MASK GENMASK(8, 6) #define DSA_8021Q_SWITCH_ID(x) (((x) << DSA_8021Q_SWITCH_ID_SHIFT) & \ DSA_8021Q_SWITCH_ID_MASK) #define DSA_8021Q_PORT_SHIFT 0 #define DSA_8021Q_PORT_MASK GENMASK(3, 0) #define DSA_8021Q_PORT(x) (((x) << DSA_8021Q_PORT_SHIFT) & \ DSA_8021Q_PORT_MASK) /* Returns the VID to be inserted into the frame from xmit for switch steering * instructions on egress. Encodes switch ID and port ID. */ u16 dsa_8021q_tx_vid(struct dsa_switch *ds, int port) { return DSA_8021Q_DIR_TX | DSA_8021Q_SWITCH_ID(ds->index) | DSA_8021Q_PORT(port); } EXPORT_SYMBOL_GPL(dsa_8021q_tx_vid); /* Returns the VID that will be installed as pvid for this switch port, sent as * tagged egress towards the CPU port and decoded by the rcv function. */ u16 dsa_8021q_rx_vid(struct dsa_switch *ds, int port) { return DSA_8021Q_DIR_RX | DSA_8021Q_SWITCH_ID(ds->index) | DSA_8021Q_PORT(port); } EXPORT_SYMBOL_GPL(dsa_8021q_rx_vid); /* Returns the decoded switch ID from the RX VID. */ int dsa_8021q_rx_switch_id(u16 vid) { return (vid & DSA_8021Q_SWITCH_ID_MASK) >> DSA_8021Q_SWITCH_ID_SHIFT; } EXPORT_SYMBOL_GPL(dsa_8021q_rx_switch_id); /* Returns the decoded port ID from the RX VID. */ int dsa_8021q_rx_source_port(u16 vid) { return (vid & DSA_8021Q_PORT_MASK) >> DSA_8021Q_PORT_SHIFT; } EXPORT_SYMBOL_GPL(dsa_8021q_rx_source_port); /* RX VLAN tagging (left) and TX VLAN tagging (right) setup shown for a single * front-panel switch port (here swp0). * * Port identification through VLAN (802.1Q) tags has different requirements * for it to work effectively: * - On RX (ingress from network): each front-panel port must have a pvid * that uniquely identifies it, and the egress of this pvid must be tagged * towards the CPU port, so that software can recover the source port based * on the VID in the frame. But this would only work for standalone ports; * if bridged, this VLAN setup would break autonomous forwarding and would * force all switched traffic to pass through the CPU. So we must also make * the other front-panel ports members of this VID we're adding, albeit * we're not making it their PVID (they'll still have their own). * By the way - just because we're installing the same VID in multiple * switch ports doesn't mean that they'll start to talk to one another, even * while not bridged: the final forwarding decision is still an AND between * the L2 forwarding information (which is limiting forwarding in this case) * and the VLAN-based restrictions (of which there are none in this case, * since all ports are members). * - On TX (ingress from CPU and towards network) we are faced with a problem. * If we were to tag traffic (from within DSA) with the port's pvid, all * would be well, assuming the switch ports were standalone. Frames would * have no choice but to be directed towards the correct front-panel port. * But because we also want the RX VLAN to not break bridging, then * inevitably that means that we have to give them a choice (of what * front-panel port to go out on), and therefore we cannot steer traffic * based on the RX VID. So what we do is simply install one more VID on the * front-panel and CPU ports, and profit off of the fact that steering will * work just by virtue of the fact that there is only one other port that's * a member of the VID we're tagging the traffic with - the desired one. * * So at the end, each front-panel port will have one RX VID (also the PVID), * the RX VID of all other front-panel ports, and one TX VID. Whereas the CPU * port will have the RX and TX VIDs of all front-panel ports, and on top of * that, is also tagged-input and tagged-output (VLAN trunk). * * CPU port CPU port * +-------------+-----+-------------+ +-------------+-----+-------------+ * | RX VID | | | | TX VID | | | * | of swp0 | | | | of swp0 | | | * | +-----+ | | +-----+ | * | ^ T | | | Tagged | * | | | | | ingress | * | +-------+---+---+-------+ | | +-----------+ | * | | | | | | | | Untagged | * | | U v U v U v | | v egress | * | +-----+ +-----+ +-----+ +-----+ | | +-----+ +-----+ +-----+ +-----+ | * | | | | | | | | | | | | | | | | | | | | * | |PVID | | | | | | | | | | | | | | | | | | * +-+-----+-+-----+-+-----+-+-----+-+ +-+-----+-+-----+-+-----+-+-----+-+ * swp0 swp1 swp2 swp3 swp0 swp1 swp2 swp3 */ int dsa_port_setup_8021q_tagging(struct dsa_switch *ds, int port, bool enabled) { int upstream = dsa_upstream_port(ds, port); struct dsa_port *dp = &ds->ports[port]; struct dsa_port *upstream_dp = &ds->ports[upstream]; u16 rx_vid = dsa_8021q_rx_vid(ds, port); u16 tx_vid = dsa_8021q_tx_vid(ds, port); int i, err; /* The CPU port is implicitly configured by * configuring the front-panel ports */ if (!dsa_is_user_port(ds, port)) return 0; /* Add this user port's RX VID to the membership list of all others * (including itself). This is so that bridging will not be hindered. * L2 forwarding rules still take precedence when there are no VLAN * restrictions, so there are no concerns about leaking traffic. */ for (i = 0; i < ds->num_ports; i++) { struct dsa_port *other_dp = &ds->ports[i]; u16 flags; if (i == upstream) continue; else if (i == port) /* The RX VID is pvid on this port */ flags = BRIDGE_VLAN_INFO_UNTAGGED | BRIDGE_VLAN_INFO_PVID; else /* The RX VID is a regular VLAN on all others */ flags = BRIDGE_VLAN_INFO_UNTAGGED; if (enabled) err = dsa_port_vid_add(other_dp, rx_vid, flags); else err = dsa_port_vid_del(other_dp, rx_vid); if (err) { dev_err(ds->dev, "Failed to apply RX VID %d to port %d: %d\n", rx_vid, port, err); return err; } } /* CPU port needs to see this port's RX VID * as tagged egress. */ if (enabled) err = dsa_port_vid_add(upstream_dp, rx_vid, 0); else err = dsa_port_vid_del(upstream_dp, rx_vid); if (err) { dev_err(ds->dev, "Failed to apply RX VID %d to port %d: %d\n", rx_vid, port, err); return err; } /* Finally apply the TX VID on this port and on the CPU port */ if (enabled) err = dsa_port_vid_add(dp, tx_vid, BRIDGE_VLAN_INFO_UNTAGGED); else err = dsa_port_vid_del(dp, tx_vid); if (err) { dev_err(ds->dev, "Failed to apply TX VID %d on port %d: %d\n", tx_vid, port, err); return err; } if (enabled) err = dsa_port_vid_add(upstream_dp, tx_vid, 0); else err = dsa_port_vid_del(upstream_dp, tx_vid); if (err) { dev_err(ds->dev, "Failed to apply TX VID %d on port %d: %d\n", tx_vid, upstream, err); return err; } return 0; } EXPORT_SYMBOL_GPL(dsa_port_setup_8021q_tagging); struct sk_buff *dsa_8021q_xmit(struct sk_buff *skb, struct net_device *netdev, u16 tpid, u16 tci) { /* skb->data points at skb_mac_header, which * is fine for vlan_insert_tag. */ return vlan_insert_tag(skb, htons(tpid), tci); } EXPORT_SYMBOL_GPL(dsa_8021q_xmit); struct sk_buff *dsa_8021q_rcv(struct sk_buff *skb, struct net_device *netdev, struct packet_type *pt, u16 *tpid, u16 *tci) { struct vlan_ethhdr *tag; if (unlikely(!pskb_may_pull(skb, VLAN_HLEN))) return NULL; tag = vlan_eth_hdr(skb); *tpid = ntohs(tag->h_vlan_proto); *tci = ntohs(tag->h_vlan_TCI); /* skb->data points in the middle of the VLAN tag, * after tpid and before tci. This is because so far, * ETH_HLEN (DMAC, SMAC, EtherType) bytes were pulled. * There are 2 bytes of VLAN tag left in skb->data, and upper * layers expect the 'real' EtherType to be consumed as well. * Coincidentally, a VLAN header is also of the same size as * the number of bytes that need to be pulled. */ skb_pull_rcsum(skb, VLAN_HLEN); return skb; } EXPORT_SYMBOL_GPL(dsa_8021q_rcv); static const struct dsa_device_ops dsa_8021q_netdev_ops = { .name = "8021q", .proto = DSA_TAG_PROTO_8021Q, .overhead = VLAN_HLEN, }; MODULE_LICENSE("GPL v2"); MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_8021Q); module_dsa_tag_driver(dsa_8021q_netdev_ops);