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

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Date:	Fri, 22 Jan 2016 16:05:09 +0100
From:	Jiri Pirko <jiri@...nulli.us>
To:	Patrick Ruddy <pruddy@...cade.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	David Stapleton <dstaplet@...cade.com>,
	Olufemi Komolafe <okomolaf@...cade.com>,
	Stephen Hemminger <shemming@...cade.com>
Subject: Re: [PATCH] Netlink messages for multicast HW addr programming

Fri, Jan 22, 2016 at 03:51:55PM CET, pruddy@...cade.com wrote:
>On Thu, 2016-01-21 at 21:04 +0100, Jiri Pirko wrote:
>> Thu, Jan 21, 2016 at 12:47:54PM CET, pruddy@...cade.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@...cade.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.