Re: [PATCH net-2.6][NEIGH] Updating affected neighbours when about MAC address change
Hello,
First, it indeed can be handled by user space. (even though it should
be done twice, once for ifconig of net-tools and once for ip of
iproute2) / However, we have already
methods which deal with bringing down an interface - neigh_ifdown(),
and changing MAC address of an interface (neigh_changeaddr). So why
not do it from
the kernel ?
DS
On Dec 23, 2007 4:02 PM, Herbert Xu [EMAIL PROTECTED] wrote:
David Shwatrz [EMAIL PROTECTED] wrote:
Hi,
Oop, I am TWICE sorry ! I wrongly attached a wrong, empty file.
Attached here is the patch.
Regarding your answer; I accept it and I will soon send a revised
version of this patch (making changes to
arp_netdev_event() and ndisc_netdev_event().)
I had IPv4 in mind, there is no reason that it will no be also in IPv6.
Hmm, why can't you do this from user-space?
Cheers,
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[PATCH net-2.6][NEIGH] Updating affected neighbours about MAC address change
Hello, We know that changes in MAC addresses are not frequent but we are working on a special, highly advanced networking Linux based project in our LABs, where we do change MAC addresses of an interface quite frequently. (We do not go totally wild; the MAC addresses we are changing into are from a set of given MAC addresses). Normally, when we change a MAC address of some interface, the relevant neighbours in the LAN which have entries with the previous MAC address are not sent any update notification; instead, it is there regular timers mechanisms which update the MAC address to the new one in their ARP tables. I had written a small patch to neigh_changeaddr() in net/core/neighbour.c against the 2.6 git net tree, which sends a gratuitous ARP to update the list of all the involved neighbours with the change of MAC address. The patch is for neigh_changeaddr() only. This patch was tested and it does work in my LAB; if such a patch is not needed, I wonder why ? It seems to me that it could not cause any troubles. BTW, I had noticed that in irlan driver, there is such a mechanism of sending a gratuitous ARP to update all the neighbours when a MAC address is changed. Signed-off-by: David Shwatrz [EMAIL PROTECTED] -- To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH net-2.6][NEIGH] Updating affected neighbours when about MAC address change
Hello, Attached here is the patch - please read the following text here below: We know that changes in MAC addresses are not frequent but we are working on a special, highly advanced networking Linux based project in our LABs, where we do change MAC addresses of an interface quite frequently. (We do not go totally wild; the MAC addresses we are changing into are from a set of given MAC addresses). Normally, when we change a MAC address of some interface, the relevant neighbours in the LAN which have entries with the previous MAC address are not sent any update notification; instead, it is there regular timers mechanisms which update the MAC address to the new one in their ARP tables. I had written a small patch to neigh_changeaddr() in net/core/neighbour.c against the 2.6 git net tree, which sends a gratuitous ARP to update the list of all the involved neighbours with the change of MAC address. The patch is for neigh_changeaddr() only. This patch was tested and it does work in my LAB; if such a patch is not needed, I wonder why ? It seems to me that it could not cause any troubles. BTW, I had noticed that in irlan driver, there is such a mechanism of sending a gratuitous ARP to update all the neighbours when a MAC address is changed. Signed-off-by: David Shwatrz [EMAIL PROTECTED] -- To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH net-2.6][NEIGH] Updating affected neighbours when about MAC address change
Hi,
Oop, I am TWICE sorry ! I wrongly attached a wrong, empty file.
Attached here is the patch.
Regarding your answer; I accept it and I will soon send a revised
version of this patch (making changes to
arp_netdev_event() and ndisc_netdev_event().)
I had IPv4 in mind, there is no reason that it will no be also in IPv6.
Regads,
David Shwatrz
On Dec 23, 2007 2:11 PM, YOSHIFUJI Hideaki / 吉藤英明
[EMAIL PROTECTED] wrote:
In article [EMAIL PROTECTED] (at Sun, 23 Dec 2007 13:41:36 +0200), David
Shwatrz [EMAIL PROTECTED] says:
I had written a small patch to neigh_changeaddr() in net/core/neighbour.c
against the 2.6 git net tree, which sends a gratuitous ARP to update
the list of
all the involved neighbours with the change of MAC address.
The patch is for neigh_changeaddr() only.
Though I can see no patch, but I disagree. ;-)
I do think you should change arp_netdev_event() and ndisc_netdev_event().
--yoshfuji
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 29b8ee4..ddeae82 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -36,6 +36,9 @@
#include linux/string.h
#include linux/log2.h
+#include linux/inetdevice.h
+#include net/arp.h
+
#define NEIGH_DEBUG 1
#define NEIGH_PRINTK(x...) printk(x)
@@ -228,9 +231,26 @@ static void neigh_flush_dev(struct neigh_table *tbl,
struct net_device *dev)
void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev)
{
+ struct in_device *in_dev;
write_lock_bh(tbl-lock);
neigh_flush_dev(tbl, dev);
write_unlock_bh(tbl-lock);
+
+ /* Send a gratuitous ARP to the neighbours to update their arp tables */
+
+ rcu_read_lock();
+ in_dev = __in_dev_get_rcu(dev);
+ if (in_dev == NULL)
+ goto out;
+ if (in_dev-ifa_list)
+
+ arp_send(ARPOP_REQUEST, ETH_P_ARP,
+in_dev-ifa_list-ifa_address,
+dev,
+in_dev-ifa_list-ifa_address,
+NULL, dev-dev_addr, NULL);
+out:
+ rcu_read_unlock();
}
int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
Re: [PATCH net-2.6][NEIGH] Updating affected neighbours when about MAC address change
Hello, You should iterate all of ifa_list (for IPv4) / addr_list (for IPv6). For IPv6, we also have anycast (maintained by ac_list) as well. I am not sure that we need to iterate all of ifa_list in IPv4. The reason is that we end with arp_send, and it initiates a broadcast. So all neighbours will receive it and update their arp tables accordingly. The dest hw in the arp_send is NULL according to this patch ; this means that we will assign dev-broadcast to dest_hw in apr_create(). It seems to me there's no reason to send more than one broadcast. In IPv6, I need to check, since it is multicast. Thoughts ? Regards, DS On Dec 23, 2007 2:38 PM, YOSHIFUJI Hideaki / 吉藤英明 [EMAIL PROTECTED] wrote: In article [EMAIL PROTECTED] (at Sun, 23 Dec 2007 14:24:00 +0200), David Shwatrz [EMAIL PROTECTED] says: Regarding your answer; I accept it and I will soon send a revised version of this patch (making changes to arp_netdev_event() and ndisc_netdev_event().) I had IPv4 in mind, there is no reason that it will no be also in IPv6. You should iterate all of ifa_list (for IPv4) / addr_list (for IPv6). For IPv6, we also have anycast (maintained by ac_list) as well. --yoshfuji -- To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH net-2.6][NEIGH] Updating affected neighbours when about MAC address change
Yoshfuji, Thanks, you are right ! soon I will send the patches. Thanks ! DS On Dec 23, 2007 3:13 PM, YOSHIFUJI Hideaki / 吉藤英明 [EMAIL PROTECTED] wrote: In article [EMAIL PROTECTED] (at Sun, 23 Dec 2007 15:04:37 +0200), David Shwatrz [EMAIL PROTECTED] says: Hello, You should iterate all of ifa_list (for IPv4) / addr_list (for IPv6). For IPv6, we also have anycast (maintained by ac_list) as well. I am not sure that we need to iterate all of ifa_list in IPv4. The reason is that we end with arp_send, and it initiates a broadcast. So all neighbours will receive it and update their arp tables accordingly. The dest hw in the arp_send is NULL according to this patch ; this means that we will assign dev-broadcast to dest_hw in apr_create(). It seems to me there's no reason to send more than one broadcast. Urgh? what is happend if you have multiple IPv4 addresses on the device? In IPv6, I need to check, since it is multicast. Please read RFC2461 Section 7.2.6. In short we should send a few unsolicited NA, but I think you can start from sending once per an address. --yoshfuji -- To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH net-2.6] [NEIGH] [resend] Updating affected neighbours when about MAC address change in arp_netdev_event()
Hello,
This is a resend of the patch according to Yoshifuji comment. I will
send a patch for IPv6 later.
We know that changes in MAC addresses are not frequent but
we are working on a special, highly advanced networking Linux based project
in our LABs, where we do change MAC addresses of an interface quite frequently.
(We do not go totally wild; the MAC addresses we are changing into are
from a set of given MAC addresses).
Normally, when we change a MAC address of some interface, the
relevant neighbours in the LAN which have entries with the previous MAC
address are not sent any update notification; instead, it is there
regular timers mechanisms which update the MAC address to the new
one in their ARP tables.
I had written a small patch to neigh_changeaddr() in net/ipv4/arp.c
against the 2.6 git net tree, which sends a gratuitous ARP to update
the list of
all the involved neighbours with the change of MAC address.
The patch is for arp_netdev_event() only.
This patch was tested and it does work in my LAB; if such a patch is
not needed,
I wonder why ?
It seems to me that it could not cause any troubles.
BTW, I had noticed that in irlan driver, there is such a mechanism
of sending a gratuitous ARP to update all the
neighbours when a MAC address is changed.
Signed-off-by: David Shwartz [EMAIL PROTECTED]
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 08174a2..7b1162b 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1185,6 +1185,8 @@ out:
static int arp_netdev_event(struct notifier_block *this, unsigned long event,
void *ptr)
{
+ struct in_device *in_dev;
+ struct in_ifaddr *ifa;
struct net_device *dev = ptr;
if (dev-nd_net != init_net)
@@ -1194,6 +1196,22 @@ static int arp_netdev_event(struct notifier_block *this,
unsigned long event, vo
case NETDEV_CHANGEADDR:
neigh_changeaddr(arp_tbl, dev);
rt_cache_flush(0);
+
+ /* Send gratuitous ARP to the neighbours to update their arp
tables */
+
+ rcu_read_lock();
+ in_dev = __in_dev_get_rcu(dev);
+ if (in_dev == NULL)
+ goto out;
+ for (ifa = in_dev-ifa_list; ifa; ifa = ifa-ifa_next)
+ arp_send(ARPOP_REQUEST, ETH_P_ARP,
+ ifa-ifa_address,
+ dev,
+ ifa-ifa_address,
+ NULL, dev-dev_addr, NULL);
+out:
+ rcu_read_unlock();
+
break;
default:
break;
A short question about net git tree and patches
Hello, I have a short question regarding the net git tree and patches: I want to write and send patches against the most recent and bleeding edge kernel networking code. I see in: http://kernel.org/pub/scm/linux/kernel/git/davem/?C=M;O=A that there are 3 git trees which can be candidates for git-clone and making patches against; these are: netdev-2.6.git, net-2.6.25.git and net-2.6.git. It seems to me that net-2.6.git is the most suitable one to work against; am I right ? what is the difference, in short, between the three repositories? Regards, DS -- To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
