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// 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);
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