/*
 *      Bridge netlink control interface
 *
 *      Authors:
 *      Stephen Hemminger               <shemminger@osdl.org>
 *
 *      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 <net/rtnetlink.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include "br_private.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;

        pr_debug("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;

        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);

        if (dev->addr_len)
                NLA_PUT(skb, IFLA_ADDRESS, dev->addr_len, dev->dev_addr);

        if (dev->ifindex != dev->iflink)
                NLA_PUT_U32(skb, IFLA_LINK, dev->iflink);

        if (event == RTM_NEWLINK)
                NLA_PUT_U8(skb, IFLA_PROTINFO, port->state);

        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;

        pr_debug("bridge notify event=%d\n", 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;
        for_each_netdev(net, dev) {
                /* not a bridge port */
                if (dev->br_port == NULL || idx < cb->args[0])
                        goto skip;

                if (br_fill_ifinfo(skb, dev->br_port, NETLINK_CB(cb->skb).pid,
                                   cb->nlh->nlmsg_seq, RTM_NEWLINK,
                                   NLM_F_MULTI) < 0)
                        break;
skip:
                ++idx;
        }

        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 = dev->br_port;
        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);
        return 0;
}


int __init br_netlink_init(void)
{
        if (__rtnl_register(PF_BRIDGE, RTM_GETLINK, NULL, br_dump_ifinfo))
                return -ENOBUFS;

        /* Only the first call to __rtnl_register can fail */
        __rtnl_register(PF_BRIDGE, RTM_SETLINK, br_rtm_setlink, NULL);

        return 0;
}

void __exit br_netlink_fini(void)
{
        rtnl_unregister_all(PF_BRIDGE);
}