linux/net/bridge/br_netlink.c
Pablo Neira Ayuso 1ce85fe402 netlink: change nlmsg_notify() return value logic
This patch changes the return value of nlmsg_notify() as follows:

If NETLINK_BROADCAST_ERROR is set by any of the listeners and
an error in the delivery happened, return the broadcast error;
else if there are no listeners apart from the socket that
requested a change with the echo flag, return the result of the
unicast notification. Thus, with this patch, the unicast
notification is handled in the same way of a broadcast listener
that has set the NETLINK_BROADCAST_ERROR socket flag.

This patch is useful in case that the caller of nlmsg_notify()
wants to know the result of the delivery of a netlink notification
(including the broadcast delivery) and take any action in case
that the delivery failed. For example, ctnetlink can drop packets
if the event delivery failed to provide reliable logging and
state-synchronization at the cost of dropping packets.

This patch also modifies the rtnetlink code to ignore the return
value of rtnl_notify() in all callers. The function rtnl_notify()
(before this patch) returned the error of the unicast notification
which makes rtnl_set_sk_err() reports errors to all listeners. This
is not of any help since the origin of the change (the socket that
requested the echoing) notices the ENOBUFS error if the notification
fails and should resync itself.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-02-24 23:18:28 -08:00

202 lines
4.8 KiB
C

/*
* 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);
}