Re: [PATCH] Netlink messages for multicast HW addr programming

Patrick Ruddy
2016-01-22T15:49:48Z

On Fri, 2016-01-22 at 16:05 +0100, Jiri Pirko wrote:
> Fri, Jan 22, 2016 at 03:51:55PM CET, pruddy@Brocade.com wrote:
> >On Thu, 2016-01-21 at 21:04 +0100, Jiri Pirko wrote:
> >> Thu, Jan 21, 2016 at 12:47:54PM CET, pruddy@brocade.com wrote:
> >> >Add RTM_NEWADDR and RTM_DELADDR netlink messages to indicate
> >> >interest in specific multicast hardware addresses. These messages
> >> >are sent when addressed are added or deleted from the appropriate
> >> >interface driver.
> >> >
> >> >Signed-off-by: Patrick Ruddy <pruddy@brocade.com>
> >> >
> >> >diff --git a/net/core/dev_addr_lists.c b/net/core/dev_addr_lists.c
> >> >index c0548d2..a0ebadd 100644
> >> >--- a/net/core/dev_addr_lists.c
> >> >+++ b/net/core/dev_addr_lists.c
> >> >@@ -12,6 +12,7 @@
> >> > */
> >> >
> >> > #include <linux/netdevice.h>
> >> >+#include <net/netlink.h>
> >> > #include <linux/rtnetlink.h>
> >> > #include <linux/export.h>
> >> > #include <linux/list.h>
> >> >@@ -661,6 +662,62 @@ out:
> >> > }
> >> > EXPORT_SYMBOL(dev_mc_add_excl);
> >> >
> >> >+static int fill_addr(struct sk_buff *skb, struct net_device *dev,
> >> >+ const unsigned char *addr, int type)
> >> >+{
> >> >+ struct nlmsghdr *nlh;
> >> >+ struct ifaddrmsg *ifm;
> >> >+
> >> >+ nlh = nlmsg_put(skb, 0, 0, type, sizeof(*ifm), 0);
> >> >+ if (nlh == NULL)
> >> >+ return -EMSGSIZE;
> >> >+
> >> >+ ifm = nlmsg_data(nlh);
> >> >+ ifm->ifa_family = AF_UNSPEC;
> >> >+ ifm->ifa_prefixlen = 0;
> >> >+ ifm->ifa_flags = IFA_F_PERMANENT;
> >> >+ ifm->ifa_scope = RT_SCOPE_LINK;
> >> >+ ifm->ifa_index = dev->ifindex;
> >> >+ if (nla_put(skb, IFA_ADDRESS, dev->addr_len, addr))
> >> >+ goto nla_put_failure;
> >> >+ nlmsg_end(skb, nlh);
> >>
> >> How can userspace tell if this is a multicast addr? Also, why not add
> >> notifications for unicast addrs so we handle both the same?
> >
> >I am only using this RTM_NEW/DELADDR AF_UNSPEC message for multicast
> >addresses. I understand that the unicast addresses are notified in the
> >RTM_NEW/DELLINK.
>
> dev->dev_addr is notified by that. UC addresses do not have any
> notification now.
It is the multicast MAC address (ie the multicast equivalent of the
dev_addr) that we are notifying here right? Not L3 addresses.

-pr