br_netlink.c

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/*
 *  Bridge netlink control interface
 *
 *  Authors:
 *  Stephen Hemminger       <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/etherdevice.h>
#include <net/rtnetlink.h>
#include <net/net_namespace.h>
#include <net/sock.h>

#include "br_private.h"
#include "br_private_stp.h"

static inline size_t br_nlmsg_size(void)
{
    return NLMSG_ALIGN(sizeof(struct ifinfomsg))
           + nla_total_size(IFNAMSIZ) /* IFLA_IFNAME */
           + nla_total_size(MAX_ADDR_LEN) /* IFLA_ADDRESS */
           + nla_total_size(4) /* IFLA_MASTER */
           + nla_total_size(4) /* IFLA_MTU */
           + nla_total_size(4) /* IFLA_LINK */
           + nla_total_size(1) /* IFLA_OPERSTATE */
           + nla_total_size(1); /* IFLA_PROTINFO */
}

/*
 * Create one netlink message for one interface
 * Contains port and master info as well as carrier and bridge state.
 */
static int br_fill_ifinfo(struct sk_buff *skb, const struct net_bridge_port *port,
              u32 pid, u32 seq, int event, unsigned int flags)
{
    const struct net_bridge *br = port->br;
    const struct net_device *dev = port->dev;
    struct ifinfomsg *hdr;
    struct nlmsghdr *nlh;
    u8 operstate = netif_running(dev) ? dev->operstate : IF_OPER_DOWN;

    br_debug(br, "br_fill_info event %d port %s master %s\n",
             event, dev->name, br->dev->name);

    nlh = nlmsg_put(skb, pid, seq, event, sizeof(*hdr), flags);
    if (nlh == NULL)
        return -EMSGSIZE;

    hdr = nlmsg_data(nlh);
    hdr->ifi_family = AF_BRIDGE;
    hdr->__ifi_pad = 0;
    hdr->ifi_type = dev->type;
    hdr->ifi_index = dev->ifindex;
    hdr->ifi_flags = dev_get_flags(dev);
    hdr->ifi_change = 0;

    if (nla_put_string(skb, IFLA_IFNAME, dev->name) ||
        nla_put_u32(skb, IFLA_MASTER, br->dev->ifindex) ||
        nla_put_u32(skb, IFLA_MTU, dev->mtu) ||
        nla_put_u8(skb, IFLA_OPERSTATE, operstate) ||
        (dev->addr_len &&
         nla_put(skb, IFLA_ADDRESS, dev->addr_len, dev->dev_addr)) ||
        (dev->ifindex != dev->iflink &&
         nla_put_u32(skb, IFLA_LINK, dev->iflink)) ||
        (event == RTM_NEWLINK &&
         nla_put_u8(skb, IFLA_PROTINFO, port->state)))
        goto nla_put_failure;
    return nlmsg_end(skb, nlh);

nla_put_failure:
    nlmsg_cancel(skb, nlh);
    return -EMSGSIZE;
}

/*
 * Notify listeners of a change in port information
 */
void br_ifinfo_notify(int event, struct net_bridge_port *port)
{
    struct net *net = dev_net(port->dev);
    struct sk_buff *skb;
    int err = -ENOBUFS;

    br_debug(port->br, "port %u(%s) event %d\n",
         (unsigned int)port->port_no, port->dev->name, event);

    skb = nlmsg_new(br_nlmsg_size(), GFP_ATOMIC);
    if (skb == NULL)
        goto errout;

    err = br_fill_ifinfo(skb, port, 0, 0, event, 0);
    if (err < 0) {
        /* -EMSGSIZE implies BUG in br_nlmsg_size() */
        WARN_ON(err == -EMSGSIZE);
        kfree_skb(skb);
        goto errout;
    }
    rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_ATOMIC);
    return;
errout:
    if (err < 0)
        rtnl_set_sk_err(net, RTNLGRP_LINK, err);
}

/*
 * Dump information about all ports, in response to GETLINK
 */
static int br_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
{
    struct net *net = sock_net(skb->sk);
    struct net_device *dev;
    int idx;

    idx = 0;
    rcu_read_lock();
    for_each_netdev_rcu(net, dev) {
        struct net_bridge_port *port = br_port_get_rcu(dev);

        /* not a bridge port */
        if (!port || idx < cb->args[0])
            goto skip;

        if (br_fill_ifinfo(skb, port,
                   NETLINK_CB(cb->skb).portid,
                   cb->nlh->nlmsg_seq, RTM_NEWLINK,
                   NLM_F_MULTI) < 0)
            break;
skip:
        ++idx;
    }
    rcu_read_unlock();
    cb->args[0] = idx;

    return skb->len;
}

/*
 * Change state of port (ie from forwarding to blocking etc)
 * Used by spanning tree in user space.
 */
static int br_rtm_setlink(struct sk_buff *skb,  struct nlmsghdr *nlh, void *arg)
{
    struct net *net = sock_net(skb->sk);
    struct ifinfomsg *ifm;
    struct nlattr *protinfo;
    struct net_device *dev;
    struct net_bridge_port *p;
    u8 new_state;

    if (nlmsg_len(nlh) < sizeof(*ifm))
        return -EINVAL;

    ifm = nlmsg_data(nlh);
    if (ifm->ifi_family != AF_BRIDGE)
        return -EPFNOSUPPORT;

    protinfo = nlmsg_find_attr(nlh, sizeof(*ifm), IFLA_PROTINFO);
    if (!protinfo || nla_len(protinfo) < sizeof(u8))
        return -EINVAL;

    new_state = nla_get_u8(protinfo);
    if (new_state > BR_STATE_BLOCKING)
        return -EINVAL;

    dev = __dev_get_by_index(net, ifm->ifi_index);
    if (!dev)
        return -ENODEV;

    p = br_port_get_rtnl(dev);
    if (!p)
        return -EINVAL;

    /* if kernel STP is running, don't allow changes */
    if (p->br->stp_enabled == BR_KERNEL_STP)
        return -EBUSY;

    if (!netif_running(dev) ||
        (!netif_carrier_ok(dev) && new_state != BR_STATE_DISABLED))
        return -ENETDOWN;

    p->state = new_state;
    br_log_state(p);

    spin_lock_bh(&p->br->lock);
    br_port_state_selection(p->br);
    spin_unlock_bh(&p->br->lock);

    br_ifinfo_notify(RTM_NEWLINK, p);

    return 0;
}

static int br_validate(struct nlattr *tb[], struct nlattr *data[])
{
    if (tb[IFLA_ADDRESS]) {
        if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
            return -EINVAL;
        if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
            return -EADDRNOTAVAIL;
    }

    return 0;
}

struct rtnl_link_ops br_link_ops __read_mostly = {
    .kind       = "bridge",
    .priv_size  = sizeof(struct net_bridge),
    .setup      = br_dev_setup,
    .validate   = br_validate,
    .dellink    = br_dev_delete,
};

int __init br_netlink_init(void)
{
    int err;

    err = rtnl_link_register(&br_link_ops);
    if (err < 0)
        goto err1;

    err = __rtnl_register(PF_BRIDGE, RTM_GETLINK, NULL,
                  br_dump_ifinfo, NULL);
    if (err)
        goto err2;
    err = __rtnl_register(PF_BRIDGE, RTM_SETLINK,
                  br_rtm_setlink, NULL, NULL);
    if (err)
        goto err3;

    return 0;

err3:
    rtnl_unregister_all(PF_BRIDGE);
err2:
    rtnl_link_unregister(&br_link_ops);
err1:
    return err;
}

void __exit br_netlink_fini(void)
{
    rtnl_link_unregister(&br_link_ops);
    rtnl_unregister_all(PF_BRIDGE);
}