Vladimir Oltean | f9bbe44 | 2019-05-05 13:19:22 +0300 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com> |
| 3 | * |
| 4 | * This module is not a complete tagger implementation. It only provides |
| 5 | * primitives for taggers that rely on 802.1Q VLAN tags to use. The |
| 6 | * dsa_8021q_netdev_ops is registered for API compliance and not used |
| 7 | * directly by callers. |
| 8 | */ |
| 9 | #include <linux/if_bridge.h> |
| 10 | #include <linux/if_vlan.h> |
| 11 | |
| 12 | #include "dsa_priv.h" |
| 13 | |
| 14 | /* Allocating two VLAN tags per port - one for the RX VID and |
| 15 | * the other for the TX VID - see below |
| 16 | */ |
| 17 | #define DSA_8021Q_VID_RANGE (DSA_MAX_SWITCHES * DSA_MAX_PORTS) |
| 18 | #define DSA_8021Q_VID_BASE (VLAN_N_VID - 2 * DSA_8021Q_VID_RANGE - 1) |
| 19 | #define DSA_8021Q_RX_VID_BASE (DSA_8021Q_VID_BASE) |
| 20 | #define DSA_8021Q_TX_VID_BASE (DSA_8021Q_VID_BASE + DSA_8021Q_VID_RANGE) |
| 21 | |
| 22 | /* Returns the VID to be inserted into the frame from xmit for switch steering |
| 23 | * instructions on egress. Encodes switch ID and port ID. |
| 24 | */ |
| 25 | u16 dsa_8021q_tx_vid(struct dsa_switch *ds, int port) |
| 26 | { |
| 27 | return DSA_8021Q_TX_VID_BASE + (DSA_MAX_PORTS * ds->index) + port; |
| 28 | } |
| 29 | EXPORT_SYMBOL_GPL(dsa_8021q_tx_vid); |
| 30 | |
| 31 | /* Returns the VID that will be installed as pvid for this switch port, sent as |
| 32 | * tagged egress towards the CPU port and decoded by the rcv function. |
| 33 | */ |
| 34 | u16 dsa_8021q_rx_vid(struct dsa_switch *ds, int port) |
| 35 | { |
| 36 | return DSA_8021Q_RX_VID_BASE + (DSA_MAX_PORTS * ds->index) + port; |
| 37 | } |
| 38 | EXPORT_SYMBOL_GPL(dsa_8021q_rx_vid); |
| 39 | |
| 40 | /* Returns the decoded switch ID from the RX VID. */ |
| 41 | int dsa_8021q_rx_switch_id(u16 vid) |
| 42 | { |
| 43 | return ((vid - DSA_8021Q_RX_VID_BASE) / DSA_MAX_PORTS); |
| 44 | } |
| 45 | EXPORT_SYMBOL_GPL(dsa_8021q_rx_switch_id); |
| 46 | |
| 47 | /* Returns the decoded port ID from the RX VID. */ |
| 48 | int dsa_8021q_rx_source_port(u16 vid) |
| 49 | { |
| 50 | return ((vid - DSA_8021Q_RX_VID_BASE) % DSA_MAX_PORTS); |
| 51 | } |
| 52 | EXPORT_SYMBOL_GPL(dsa_8021q_rx_source_port); |
| 53 | |
| 54 | /* RX VLAN tagging (left) and TX VLAN tagging (right) setup shown for a single |
| 55 | * front-panel switch port (here swp0). |
| 56 | * |
| 57 | * Port identification through VLAN (802.1Q) tags has different requirements |
| 58 | * for it to work effectively: |
| 59 | * - On RX (ingress from network): each front-panel port must have a pvid |
| 60 | * that uniquely identifies it, and the egress of this pvid must be tagged |
| 61 | * towards the CPU port, so that software can recover the source port based |
| 62 | * on the VID in the frame. But this would only work for standalone ports; |
| 63 | * if bridged, this VLAN setup would break autonomous forwarding and would |
| 64 | * force all switched traffic to pass through the CPU. So we must also make |
| 65 | * the other front-panel ports members of this VID we're adding, albeit |
| 66 | * we're not making it their PVID (they'll still have their own). |
| 67 | * By the way - just because we're installing the same VID in multiple |
| 68 | * switch ports doesn't mean that they'll start to talk to one another, even |
| 69 | * while not bridged: the final forwarding decision is still an AND between |
| 70 | * the L2 forwarding information (which is limiting forwarding in this case) |
| 71 | * and the VLAN-based restrictions (of which there are none in this case, |
| 72 | * since all ports are members). |
| 73 | * - On TX (ingress from CPU and towards network) we are faced with a problem. |
| 74 | * If we were to tag traffic (from within DSA) with the port's pvid, all |
| 75 | * would be well, assuming the switch ports were standalone. Frames would |
| 76 | * have no choice but to be directed towards the correct front-panel port. |
| 77 | * But because we also want the RX VLAN to not break bridging, then |
| 78 | * inevitably that means that we have to give them a choice (of what |
| 79 | * front-panel port to go out on), and therefore we cannot steer traffic |
| 80 | * based on the RX VID. So what we do is simply install one more VID on the |
| 81 | * front-panel and CPU ports, and profit off of the fact that steering will |
| 82 | * work just by virtue of the fact that there is only one other port that's |
| 83 | * a member of the VID we're tagging the traffic with - the desired one. |
| 84 | * |
| 85 | * So at the end, each front-panel port will have one RX VID (also the PVID), |
| 86 | * the RX VID of all other front-panel ports, and one TX VID. Whereas the CPU |
| 87 | * port will have the RX and TX VIDs of all front-panel ports, and on top of |
| 88 | * that, is also tagged-input and tagged-output (VLAN trunk). |
| 89 | * |
| 90 | * CPU port CPU port |
| 91 | * +-------------+-----+-------------+ +-------------+-----+-------------+ |
| 92 | * | RX VID | | | | TX VID | | | |
| 93 | * | of swp0 | | | | of swp0 | | | |
| 94 | * | +-----+ | | +-----+ | |
| 95 | * | ^ T | | | Tagged | |
| 96 | * | | | | | ingress | |
| 97 | * | +-------+---+---+-------+ | | +-----------+ | |
| 98 | * | | | | | | | | Untagged | |
| 99 | * | | U v U v U v | | v egress | |
| 100 | * | +-----+ +-----+ +-----+ +-----+ | | +-----+ +-----+ +-----+ +-----+ | |
| 101 | * | | | | | | | | | | | | | | | | | | | | |
| 102 | * | |PVID | | | | | | | | | | | | | | | | | | |
| 103 | * +-+-----+-+-----+-+-----+-+-----+-+ +-+-----+-+-----+-+-----+-+-----+-+ |
| 104 | * swp0 swp1 swp2 swp3 swp0 swp1 swp2 swp3 |
| 105 | */ |
| 106 | int dsa_port_setup_8021q_tagging(struct dsa_switch *ds, int port, bool enabled) |
| 107 | { |
| 108 | int upstream = dsa_upstream_port(ds, port); |
| 109 | struct dsa_port *dp = &ds->ports[port]; |
| 110 | struct dsa_port *upstream_dp = &ds->ports[upstream]; |
| 111 | u16 rx_vid = dsa_8021q_rx_vid(ds, port); |
| 112 | u16 tx_vid = dsa_8021q_tx_vid(ds, port); |
| 113 | int i, err; |
| 114 | |
| 115 | /* The CPU port is implicitly configured by |
| 116 | * configuring the front-panel ports |
| 117 | */ |
| 118 | if (!dsa_is_user_port(ds, port)) |
| 119 | return 0; |
| 120 | |
| 121 | /* Add this user port's RX VID to the membership list of all others |
| 122 | * (including itself). This is so that bridging will not be hindered. |
| 123 | * L2 forwarding rules still take precedence when there are no VLAN |
| 124 | * restrictions, so there are no concerns about leaking traffic. |
| 125 | */ |
| 126 | for (i = 0; i < ds->num_ports; i++) { |
| 127 | struct dsa_port *other_dp = &ds->ports[i]; |
| 128 | u16 flags; |
| 129 | |
| 130 | if (i == upstream) |
| 131 | /* CPU port needs to see this port's RX VID |
| 132 | * as tagged egress. |
| 133 | */ |
| 134 | flags = 0; |
| 135 | else if (i == port) |
| 136 | /* The RX VID is pvid on this port */ |
| 137 | flags = BRIDGE_VLAN_INFO_UNTAGGED | |
| 138 | BRIDGE_VLAN_INFO_PVID; |
| 139 | else |
| 140 | /* The RX VID is a regular VLAN on all others */ |
| 141 | flags = BRIDGE_VLAN_INFO_UNTAGGED; |
| 142 | |
| 143 | if (enabled) |
| 144 | err = dsa_port_vid_add(other_dp, rx_vid, flags); |
| 145 | else |
| 146 | err = dsa_port_vid_del(other_dp, rx_vid); |
| 147 | if (err) { |
| 148 | dev_err(ds->dev, "Failed to apply RX VID %d to port %d: %d\n", |
| 149 | rx_vid, port, err); |
| 150 | return err; |
| 151 | } |
| 152 | } |
| 153 | /* Finally apply the TX VID on this port and on the CPU port */ |
| 154 | if (enabled) |
| 155 | err = dsa_port_vid_add(dp, tx_vid, BRIDGE_VLAN_INFO_UNTAGGED); |
| 156 | else |
| 157 | err = dsa_port_vid_del(dp, tx_vid); |
| 158 | if (err) { |
| 159 | dev_err(ds->dev, "Failed to apply TX VID %d on port %d: %d\n", |
| 160 | tx_vid, port, err); |
| 161 | return err; |
| 162 | } |
| 163 | if (enabled) |
| 164 | err = dsa_port_vid_add(upstream_dp, tx_vid, 0); |
| 165 | else |
| 166 | err = dsa_port_vid_del(upstream_dp, tx_vid); |
| 167 | if (err) { |
| 168 | dev_err(ds->dev, "Failed to apply TX VID %d on port %d: %d\n", |
| 169 | tx_vid, upstream, err); |
| 170 | return err; |
| 171 | } |
| 172 | |
| 173 | return 0; |
| 174 | } |
| 175 | EXPORT_SYMBOL_GPL(dsa_port_setup_8021q_tagging); |
| 176 | |
| 177 | struct sk_buff *dsa_8021q_xmit(struct sk_buff *skb, struct net_device *netdev, |
| 178 | u16 tpid, u16 tci) |
| 179 | { |
| 180 | /* skb->data points at skb_mac_header, which |
| 181 | * is fine for vlan_insert_tag. |
| 182 | */ |
| 183 | return vlan_insert_tag(skb, htons(tpid), tci); |
| 184 | } |
| 185 | EXPORT_SYMBOL_GPL(dsa_8021q_xmit); |
| 186 | |
| 187 | struct sk_buff *dsa_8021q_rcv(struct sk_buff *skb, struct net_device *netdev, |
| 188 | struct packet_type *pt, u16 *tpid, u16 *tci) |
| 189 | { |
| 190 | struct vlan_ethhdr *tag; |
| 191 | |
| 192 | if (unlikely(!pskb_may_pull(skb, VLAN_HLEN))) |
| 193 | return NULL; |
| 194 | |
| 195 | tag = vlan_eth_hdr(skb); |
| 196 | *tpid = ntohs(tag->h_vlan_proto); |
| 197 | *tci = ntohs(tag->h_vlan_TCI); |
| 198 | |
| 199 | /* skb->data points in the middle of the VLAN tag, |
| 200 | * after tpid and before tci. This is because so far, |
| 201 | * ETH_HLEN (DMAC, SMAC, EtherType) bytes were pulled. |
| 202 | * There are 2 bytes of VLAN tag left in skb->data, and upper |
| 203 | * layers expect the 'real' EtherType to be consumed as well. |
| 204 | * Coincidentally, a VLAN header is also of the same size as |
| 205 | * the number of bytes that need to be pulled. |
| 206 | */ |
| 207 | skb_pull_rcsum(skb, VLAN_HLEN); |
| 208 | |
| 209 | return skb; |
| 210 | } |
| 211 | EXPORT_SYMBOL_GPL(dsa_8021q_rcv); |
| 212 | |
| 213 | static const struct dsa_device_ops dsa_8021q_netdev_ops = { |
| 214 | .name = "8021q", |
| 215 | .proto = DSA_TAG_PROTO_8021Q, |
| 216 | .overhead = VLAN_HLEN, |
| 217 | }; |
| 218 | |
| 219 | MODULE_LICENSE("GPL v2"); |
| 220 | MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_8021Q); |
| 221 | |
| 222 | module_dsa_tag_driver(dsa_8021q_netdev_ops); |