// SPDX-License-Identifier: GPL-2.0+
/*
* Regular and Ethertype DSA tagging
* Copyright (c) 2008-2009 Marvell Semiconductor
*
* Regular DSA
* -----------
* For untagged (in 802.1Q terms) packets, the switch will splice in
* the tag between the SA and the ethertype of the original
* packet. Tagged frames will instead have their outermost .1Q tag
* converted to a DSA tag. It expects the same layout when receiving
* packets from the CPU.
*
* Example:
*
* .----.----.----.---------
* Pu: | DA | SA | ET | Payload ...
* '----'----'----'---------
* 6 6 2 N
* .----.----.--------.-----.----.---------
* Pt: | DA | SA | 0x8100 | TCI | ET | Payload ...
* '----'----'--------'-----'----'---------
* 6 6 2 2 2 N
* .----.----.-----.----.---------
* Pd: | DA | SA | DSA | ET | Payload ...
* '----'----'-----'----'---------
* 6 6 4 2 N
*
* No matter if a packet is received untagged (Pu) or tagged (Pt),
* they will both have the same layout (Pd) when they are sent to the
* CPU. This is done by ignoring 802.3, replacing the ethertype field
* with more metadata, among which is a bit to signal if the original
* packet was tagged or not.
*
* Ethertype DSA
* -------------
* Uses the exact same tag format as regular DSA, but also includes a
* proper ethertype field (which the mv88e6xxx driver sets to
* ETH_P_EDSA/0xdada) followed by two zero bytes:
*
* .----.----.--------.--------.-----.----.---------
* | DA | SA | 0xdada | 0x0000 | DSA | ET | Payload ...
* '----'----'--------'--------'-----'----'---------
* 6 6 2 2 4 2 N
*/
#include <linux/dsa/mv88e6xxx.h>
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/slab.h>
#include "tag.h"
#define DSA_NAME "dsa"
#define EDSA_NAME "edsa"
#define DSA_HLEN 4
/**
* enum dsa_cmd - DSA Command
* @DSA_CMD_TO_CPU: Set on packets that were trapped or mirrored to
* the CPU port. This is needed to implement control protocols,
* e.g. STP and LLDP, that must not allow those control packets to
* be switched according to the normal rules.
* @DSA_CMD_FROM_CPU: Used by the CPU to send a packet to a specific
* port, ignoring all the barriers that the switch normally
* enforces (VLANs, STP port states etc.). No source address
* learning takes place. "sudo send packet"
* @DSA_CMD_TO_SNIFFER: Set on the copies of packets that matched some
* user configured ingress or egress monitor criteria. These are
* forwarded by the switch tree to the user configured ingress or
* egress monitor port, which can be set to the CPU port or a
* regular port. If the destination is a regular port, the tag
* will be removed before egressing the port. If the destination
* is the CPU port, the tag will not be removed.
* @DSA_CMD_FORWARD: This tag is used on all bulk traffic passing
* through the switch tree, including the flows that are directed
* towards the CPU. Its device/port tuple encodes the original
* source port on which the packet ingressed. It can also be used
* on transmit by the CPU to defer the forwarding decision to the
* hardware, based on the current config of PVT/VTU/ATU
* etc. Source address learning takes places if enabled on the
* receiving DSA/CPU port.
*/
enum dsa_cmd {
DSA_CMD_TO_CPU = 0,
DSA_CMD_FROM_CPU = 1,
DSA_CMD_TO_SNIFFER = 2,
DSA_CMD_FORWARD = 3
};
/**
* enum dsa_code - TO_CPU Code
*
* @DSA_CODE_MGMT_TRAP: DA was classified as a management
* address. Typical examples include STP BPDUs and LLDP.
* @DSA_CODE_FRAME2REG: Response to a "remote management" request.
* @DSA_CODE_IGMP_MLD_TRAP: IGMP/MLD signaling.
* @DSA_CODE_POLICY_TRAP: Frame matched some policy configuration on
* the device. Typical examples are matching on DA/SA/VID and DHCP
* snooping.
* @DSA_CODE_ARP_MIRROR: The name says it all really.
* @DSA_CODE_POLICY_MIRROR: Same as @DSA_CODE_POLICY_TRAP, but the
* particular policy was set to trigger a mirror instead of a
* trap.
* @DSA_CODE_RESERVED_6: Unused on all devices up to at least 6393X.
* @DSA_CODE_RESERVED_7: Unused on all devices up to at least 6393X.
*
* A 3-bit code is used to relay why a particular frame was sent to
* the CPU. We only use this to determine if the packet was mirrored
* or trapped, i.e. whether the packet has been forwarded by hardware
* or not.
*
* This is the superset of all possible codes. Any particular device
* may only implement a subset.
*/
enum dsa_code {
DSA_CODE_MGMT_TRAP = 0,
DSA_CODE_FRAME2REG = 1,
DSA_CODE_IGMP_MLD_TRAP = 2,
DSA_CODE_POLICY_TRAP = 3,
DSA_CODE_ARP_MIRROR = 4,
DSA_CODE_POLICY_MIRROR = 5,
DSA_CODE_RESERVED_6 = 6,
DSA_CODE_RESERVED_7 = 7
};
static struct sk_buff *dsa_xmit_ll(struct sk_buff *skb, struct net_device *dev,
u8 extra)
{
struct dsa_port *dp = dsa_user_to_port(dev);
struct net_device *br_dev;
u8 tag_dev, tag_port;
enum dsa_cmd cmd;
u8 *dsa_header;
if (skb->offload_fwd_mark) {
unsigned int bridge_num = dsa_port_bridge_num_get(dp);
struct dsa_switch_tree *dst = dp->ds->dst;
cmd = DSA_CMD_FORWARD;
/* When offloading forwarding for a bridge, inject FORWARD
* packets on behalf of a virtual switch device with an index
* past the physical switches.
*/
tag_dev = dst->last_switch + bridge_num;
tag_port = 0;
} else {
cmd = DSA_CMD_FROM_CPU;
tag_dev = dp->ds->index;
tag_port = dp->index;
}
br_dev = dsa_port_bridge_dev_get(dp);
/* If frame is already 802.1Q tagged, we can convert it to a DSA
* tag (avoiding a memmove), but only if the port is standalone
* (in which case we always send FROM_CPU) or if the port's
* bridge has VLAN filtering enabled (in which case the CPU port
* will be a member of the VLAN).
*/
if (skb->protocol == htons(ETH_P_8021Q) &&
(!br_dev || br_vlan_enabled(br_dev))) {
if (extra) {
skb_push(skb, extra);
dsa_alloc_etype_header(skb, extra);
}
/* Construct tagged DSA tag from 802.1Q tag. */
dsa_header = dsa_etype_header_pos_tx(skb) + extra;
dsa_header[0] = (cmd << 6) | 0x20 | tag_dev;
dsa_header[1] = tag_port << 3;
/* Move CFI field from byte 2 to byte 1. */
if (dsa_header[2] & 0x10) {
dsa_header[1] |= 0x01;
dsa_header[2] &= ~0x10;
}
} else {
u16 vid;
vid = br_dev ? MV88E6XXX_VID_BRIDGED : MV88E6XXX_VID_STANDALONE;
skb_push(skb, DSA_HLEN + extra);
dsa_alloc_etype_header(skb, DSA_HLEN + extra);
/* Construct DSA header from untagged frame. */
dsa_header = dsa_etype_header_pos_tx(skb) + extra;
dsa_header[0] = (cmd << 6) | tag_dev;
dsa_header[1] = tag_port << 3;
dsa_header[2] = vid >> 8;
dsa_header[3] = vid & 0xff;
}
return skb;
}
static struct sk_buff *dsa_rcv_ll(struct sk_buff *skb, struct net_device *dev,
u8 extra)
{
bool trap = false, trunk = false;
int source_device, source_port;
enum dsa_code code;
enum dsa_cmd cmd;
u8 *dsa_header;
/* The ethertype field is part of the DSA header. */
dsa_header = dsa_etype_header_pos_rx(skb);
cmd = dsa_header[0] >> 6;
switch (cmd) {
case DSA_CMD_FORWARD:
trunk = !!(dsa_header[1] & 4);
break;
case DSA_CMD_TO_CPU:
code = (dsa_header[1] & 0x6) | ((dsa_header[2] >> 4) & 1);
switch (code) {
case DSA_CODE_FRAME2REG:
/* Remote management is not implemented yet,
* drop.
*/
return NULL;
case DSA_CODE_ARP_MIRROR:
case DSA_CODE_POLICY_MIRROR:
/* Mark mirrored packets to notify any upper
* device (like a bridge) that forwarding has
* already been done by hardware.
*/
break;
case DSA_CODE_MGMT_TRAP:
case DSA_CODE_IGMP_MLD_TRAP:
case DSA_CODE_POLICY_TRAP:
/* Traps have, by definition, not been
* forwarded by hardware, so don't mark them.
*/
trap = true;
break;
default:
/* Reserved code, this could be anything. Drop
* seems like the safest option.
*/
return NULL;
}
break;
default:
return NULL;
}
source_device = dsa_header[0] & 0x1f;
source_port = (dsa_header[1] >> 3) & 0x1f;
if (trunk) {
struct dsa_port *cpu_dp = dev->dsa_ptr;
struct dsa_lag *lag;
/* The exact source port is not available in the tag,
* so we inject the frame directly on the upper
* team/bond.
*/
lag = dsa_lag_by_id(cpu_dp->dst, source_port + 1);
skb->dev = lag ? lag->dev : NULL;
} else {
skb->dev = dsa_conduit_find_user(dev, source_device,
source_port);
}
if (!skb->dev)
return NULL;
/* When using LAG offload, skb->dev is not a DSA user interface,
* so we cannot call dsa_default_offload_fwd_mark and we need to
* special-case it.
*/
if (trunk)
skb->offload_fwd_mark = true;
else if (!trap)
dsa_default_offload_fwd_mark(skb);
/* If the 'tagged' bit is set; convert the DSA tag to a 802.1Q
* tag, and delete the ethertype (extra) if applicable. If the
* 'tagged' bit is cleared; delete the DSA tag, and ethertype
* if applicable.
*/
if (dsa_header[0] & 0x20) {
u8 new_header[4];
/* Insert 802.1Q ethertype and copy the VLAN-related
* fields, but clear the bit that will hold CFI (since
* DSA uses that bit location for another purpose).
*/
new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
new_header[1] = ETH_P_8021Q & 0xff;
new_header[2] = dsa_header[2] & ~0x10;
new_header[3] = dsa_header[3];
/* Move CFI bit from its place in the DSA header to
* its 802.1Q-designated place.
*/
if (dsa_header[1] & 0x01)
new_header[2] |= 0x10;
/* Update packet checksum if skb is CHECKSUM_COMPLETE. */
if (skb->ip_summed == CHECKSUM_COMPLETE) {
__wsum c = skb->csum;
c = csum_add(c, csum_partial(new_header + 2, 2, 0));
c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
skb->csum = c;
}
memcpy(dsa_header, new_header, DSA_HLEN);
if (extra)
dsa_strip_etype_header(skb, extra);
} else {
skb_pull_rcsum(skb, DSA_HLEN);
dsa_strip_etype_header(skb, DSA_HLEN + extra);
}
return skb;
}
#if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA)
static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
{
return dsa_xmit_ll(skb, dev, 0);
}
static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev)
{
if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
return NULL;
return dsa_rcv_ll(skb, dev, 0);
}
static const struct dsa_device_ops dsa_netdev_ops = {
.name = DSA_NAME,
.proto = DSA_TAG_PROTO_DSA,
.xmit = dsa_xmit,
.rcv = dsa_rcv,
.needed_headroom = DSA_HLEN,
};
DSA_TAG_DRIVER(dsa_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_DSA, DSA_NAME);
#endif /* CONFIG_NET_DSA_TAG_DSA */
#if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA)
#define EDSA_HLEN 8
static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
{
u8 *edsa_header;
skb = dsa_xmit_ll(skb, dev, EDSA_HLEN - DSA_HLEN);
if (!skb)
return NULL;
edsa_header = dsa_etype_header_pos_tx(skb);
edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
edsa_header[1] = ETH_P_EDSA & 0xff;
edsa_header[2] = 0x00;
edsa_header[3] = 0x00;
return skb;
}
static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev)
{
if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
return NULL;
skb_pull_rcsum(skb, EDSA_HLEN - DSA_HLEN);
return dsa_rcv_ll(skb, dev, EDSA_HLEN - DSA_HLEN);
}
static const struct dsa_device_ops edsa_netdev_ops = {
.name = EDSA_NAME,
.proto = DSA_TAG_PROTO_EDSA,
.xmit = edsa_xmit,
.rcv = edsa_rcv,
.needed_headroom = EDSA_HLEN,
};
DSA_TAG_DRIVER(edsa_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA, EDSA_NAME);
#endif /* CONFIG_NET_DSA_TAG_EDSA */
static struct dsa_tag_driver *dsa_tag_drivers[] = {
#if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA)
&DSA_TAG_DRIVER_NAME(dsa_netdev_ops),
#endif
#if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA)
&DSA_TAG_DRIVER_NAME(edsa_netdev_ops),
#endif
};
module_dsa_tag_drivers(dsa_tag_drivers);
MODULE_DESCRIPTION("DSA tag driver for Marvell switches using DSA headers");
MODULE_LICENSE("GPL");
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