diff options
Diffstat (limited to 'net/dsa/tag_8021q.c')
| -rw-r--r-- | net/dsa/tag_8021q.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/net/dsa/tag_8021q.c b/net/dsa/tag_8021q.c new file mode 100644 index 000000000000..8ae48c7e1e76 --- /dev/null +++ b/net/dsa/tag_8021q.c @@ -0,0 +1,222 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com> + * + * 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 <linux/if_bridge.h> +#include <linux/if_vlan.h> + +#include "dsa_priv.h" + +/* Allocating two VLAN tags per port - one for the RX VID and + * the other for the TX VID - see below + */ +#define DSA_8021Q_VID_RANGE (DSA_MAX_SWITCHES * DSA_MAX_PORTS) +#define DSA_8021Q_VID_BASE (VLAN_N_VID - 2 * DSA_8021Q_VID_RANGE - 1) +#define DSA_8021Q_RX_VID_BASE (DSA_8021Q_VID_BASE) +#define DSA_8021Q_TX_VID_BASE (DSA_8021Q_VID_BASE + DSA_8021Q_VID_RANGE) + +/* 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_TX_VID_BASE + (DSA_MAX_PORTS * ds->index) + 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_RX_VID_BASE + (DSA_MAX_PORTS * ds->index) + 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_RX_VID_BASE) / DSA_MAX_PORTS); +} +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_RX_VID_BASE) % DSA_MAX_PORTS); +} +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) + /* CPU port needs to see this port's RX VID + * as tagged egress. + */ + flags = 0; + 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; + } + } + /* 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); |