ipv6: If a public address is deleted then also delete all temporary addresses still referring to it

PATCH In review Heiner Kallweit 2 participants 9 messages Mar 18, 2014 – Apr 6, 2014

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Networking Network drivers IPv4/IPv6

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Heiner Kallweit

author

2014-03-18 20:47 UTC #0 lore raw

PATCH 1/1 ipv6: If a public address is deleted then also delete all temporary addresses still referring to it

If a public address is deleted by an external trigger (e.g. via inet6_rtm_deladdr) then temporary addresses still referring to it may remain. Happened here when the WiFi link broke and netifd deleted the public address. Once the link was back and prefix_rcv created new public addresses ipv6_create_tempaddr complained that the temporary address already existed.
IMHO no temporary address should live longer than its parent, especially because ifpub of the temporary address still points to the then deleted public address otherwise.

Therefore delete all related temporary addresses before a public address is deleted in inet6_addr_del which is called by inet6_rtm_del.

Also ensure in ipv6_del_addr that no temporary address lives longer than its parent. However in addrconf_verify it might not be predetermined in which order a public address and the related temporary address are deleted if they expire at the same time. Not sure about that ..

Signed-off-by Heiner Kallweit <[email protected]>

---
 net/ipv6/addrconf.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

net/ipv6/addrconf.c +31 -0

index 344e972..e5fd81d 100644
@@ -126,6 +126,7 @@ static void ipv6_regen_rndid(unsigned long data);
 
 static int ipv6_generate_eui64(u8 *eui, struct net_device *dev);
 static int ipv6_count_addresses(struct inet6_dev *idev);
+static void ipv6_del_addr(struct inet6_ifaddr *ifp);
 
 /*
  *	Configured unicast address hash table

@@ -308,6 +309,31 @@ err_ip:
 	return -ENOMEM;
 }
 
+/* delete all temporary addresses referring to ifp
+   returns true if there have been addresses to be deleted */
+static int ifa_del_tempaddrs(struct inet6_ifaddr *ifp)
+{
+        struct inet6_dev *idev = ifp->idev;
+        struct inet6_ifaddr *ift;
+        int deleted = 0;
+
+        if(!(ifp->flags & IFA_F_MANAGETEMPADDR))
+                return 0;
+restart:
+        read_lock_bh(&idev->lock);
+        list_for_each_entry(ift, &idev->tempaddr_list, tmp_list) {
+                if (ifp != ift->ifpub)
+                        continue;
+                in6_ifa_hold(ift);
+                read_unlock_bh(&idev->lock);
+                deleted = 1;
+                ipv6_del_addr(ift);
+                goto restart;
+        }
+        read_unlock_bh(&idev->lock);
+        return deleted;
+}
+
 static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
 {
 	struct inet6_dev *ndev;

@@ -990,6 +1016,10 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
 	enum cleanup_prefix_rt_t action = CLEANUP_PREFIX_RT_NOP;
 	unsigned long expires;
 
+	/* there should be no temporary address still referring to ifp */
+        if(ifa_del_tempaddrs(ifp))
+                pr_info("%s: stale temporary address(es) deleted\n", __func__);
+
 	spin_lock_bh(&ifp->state_lock);
 	state = ifp->state;
 	ifp->state = INET6_IFADDR_STATE_DEAD;

@@ -2506,6 +2536,7 @@ static int inet6_addr_del(struct net *net, int ifindex, const struct in6_addr *p
 			in6_ifa_hold(ifp);
 			read_unlock_bh(&idev->lock);
 
+			ifa_del_tempaddrs(ifp);
 			ipv6_del_addr(ifp);
 			return 0;
 		}

Signature · 1 line

1.9.0.258.g00eda23.dirty

Hannes Frederic Sowa

2014-03-19 20:21 UTC #1 lore raw

Quoted 4 lines · Heiner Kallweit

If a public address is deleted by an external trigger (e.g. via inet6_rtm_deladdr) then temporary addresses still referring to it may remain. Happened here when the WiFi link broke and netifd deleted the public address. Once the link was back and prefix_rcv created new public addresses ipv6_create_tempaddr complained that the temporary address already existed.

Which error was it specifically?

Quoted 2 lines

IMHO no temporary address should live longer than its parent, especially because ifpub of the temporary address still points to the then deleted public address otherwise.

Reference counting will take care of that.

Quoted 2 lines

Therefore delete all related temporary addresses before a public address is deleted in inet6_addr_del which is called by inet6_rtm_del.

I am a bit concerend with backward compatibility here.

Quoted 1 line

Also ensure in ipv6_del_addr that no temporary address lives longer than its parent.

I currently don't see a problem with that.

Greetings,

Hannes

Heiner Kallweit

author

2014-03-19 21:17 UTC #2 lore raw

Am 19.03.2014 21:21, schrieb Hannes Frederic Sowa:

Quoted 13 lines · Heiner Kallweit

Quoted 4 lines
If a public address is deleted by an external trigger (e.g. via inet6_rtm_deladdr) then temporary addresses still referring to it may remain. Happened here when the WiFi link broke and netifd deleted the public address. Once the link was back and prefix_rcv created new public addresses ipv6_create_tempaddr complained that the temporary address already existed.
Which error was it specifically?
Quoted 2 lines
IMHO no temporary address should live longer than its parent, especially because ifpub of the temporary address still points to the then deleted public address otherwise.
Reference counting will take care of that.
Quoted 2 lines
Therefore delete all related temporary addresses before a public address is deleted in inet6_addr_del which is called by inet6_rtm_del.

Quoted 10 lines

I am a bit concerend with backward compatibility here.
Quoted 1 line
Also ensure in ipv6_del_addr that no temporary address lives longer than its parent.
I currently don't see a problem with that.
Greetings,
Hannes

The specific error was "retry temporary address regeneration" caused by ipv6_add_addr returning EEXIST.

First question is whether it's correct that in case of link loss the public address is deleted but not the temporary addresses. I don't think it's correct.
If it's not correct then the question is who's reponsibility it is to delete temporary addresses if the parent public address is deleted. My solution was to do it in the kernel but this might not be the best / correct approach.
Would you prefer that userspace / netifd take care to also delete the temporary addresses?

Last but not least the question is whether the kernel should care in general about the situation that a public address is deleted and orphaned temporary addresses are left behind.

Rgds, Heiner

Hannes Frederic Sowa

2014-03-19 22:41 UTC #3 lore raw

Quoted 21 lines · Heiner Kallweit

Am 19.03.2014 21:21, schrieb Hannes Frederic Sowa:
Quoted 20 lines · Heiner Kallweit
Quoted 4 lines
If a public address is deleted by an external trigger (e.g. via inet6_rtm_deladdr) then temporary addresses still referring to it may remain. Happened here when the WiFi link broke and netifd deleted the public address. Once the link was back and prefix_rcv created new public addresses ipv6_create_tempaddr complained that the temporary address already existed.
Which error was it specifically?
Quoted 2 lines
IMHO no temporary address should live longer than its parent, especially because ifpub of the temporary address still points to the then deleted public address otherwise.
Reference counting will take care of that.
Quoted 2 lines
Therefore delete all related temporary addresses before a public address is deleted in inet6_addr_del which is called by inet6_rtm_del.
I am a bit concerend with backward compatibility here.
Quoted 1 line
Also ensure in ipv6_del_addr that no temporary address lives longer than its parent.
I currently don't see a problem with that.
Greetings,

Quoted 8 lines

Quoted 3 lines
Hannes
The specific error was "retry temporary address regeneration" caused by ipv6_add_addr returning EEXIST.
First question is whether it's correct that in case of link loss the public address is deleted but not the temporary addresses. I don't think it's correct.

The kernel doesn't delete any addresses in case of link loss. netifd must have done so. In this case netifd should have flushed all addresses from the prefix.

Sure, this is racy and the error therefore looks justified for me.

Quoted 1 line

If it's not correct then the question is who's reponsibility it is to delete temporary addresses if the parent public address is deleted.

In my opinion those addresses are simple standalone addresses. The link to the public addresses is just for management purposes and should be hidden from user space.

So I would be ok, if we enhance the error case a bit, maybe reparent the old temporary address, drop them and silently generate them anew or only update prefix information from the new received prefix information. This should happen without disturbing TCP connections etc. I think this already works, but I don't know if it is worth the effort.

Quoted 2 lines

My solution was to do it in the kernel but this might not be the best / correct approach. Would you prefer that userspace / netifd take care to also delete the temporary addresses?

Yes, I would prefer that.

Quoted 2 lines

Last but not least the question is whether the kernel should care in general about the situation that a public address is deleted and orphaned temporary addresses are left behind.

I think that we should think of temporary addresses as stand-alone (IFA_F_MANAGETEMPADDR is a different story).

Btw. there was already lots of discussions whether automatically drop addresses of an interface in case of link-loss, you can read the IMHO most relevant here:
<http://markmail.org/thread/wcb6f6lcuyfuli7b>

Greetings,

Hannes

Heiner Kallweit

author

2014-03-19 23:41 UTC #4 lore raw

Am 19.03.2014 23:41, schrieb Hannes Frederic Sowa:

Quoted 55 lines · Heiner Kallweit

Quoted 21 lines
Am 19.03.2014 21:21, schrieb Hannes Frederic Sowa:
Quoted 20 lines · Heiner Kallweit
Quoted 4 lines
If a public address is deleted by an external trigger (e.g. via inet6_rtm_deladdr) then temporary addresses still referring to it may remain. Happened here when the WiFi link broke and netifd deleted the public address. Once the link was back and prefix_rcv created new public addresses ipv6_create_tempaddr complained that the temporary address already existed.
Which error was it specifically?
Quoted 2 lines
IMHO no temporary address should live longer than its parent, especially because ifpub of the temporary address still points to the then deleted public address otherwise.
Reference counting will take care of that.
Quoted 2 lines
Therefore delete all related temporary addresses before a public address is deleted in inet6_addr_del which is called by inet6_rtm_del.
I am a bit concerend with backward compatibility here.
Quoted 1 line
Also ensure in ipv6_del_addr that no temporary address lives longer than its parent.
I currently don't see a problem with that.
Greetings,
Quoted 7 lines
Quoted 3 lines
Hannes
The specific error was "retry temporary address regeneration" caused by ipv6_add_addr returning EEXIST.
First question is whether it's correct that in case of link loss the public address is deleted but not the temporary addresses. I don't think it's correct.
The kernel doesn't delete any addresses in case of link loss. netifd must have done so. In this case netifd should have flushed all addresses from the prefix.
Sure, this is racy and the error therefore looks justified for me.
Quoted 1 line
If it's not correct then the question is who's reponsibility it is to delete temporary addresses if the parent public address is deleted.
In my opinion those addresses are simple standalone addresses. The link to the public addresses is just for management purposes and should be hidden from user space.
So I would be ok, if we enhance the error case a bit, maybe reparent the old temporary address, drop them and silently generate them anew or only update prefix information from the new received prefix information. This should happen without disturbing TCP connections etc. I think this already works, but I don't know if it is worth the effort.
Quoted 2 lines
My solution was to do it in the kernel but this might not be the best / correct approach. Would you prefer that userspace / netifd take care to also delete the temporary addresses?
Yes, I would prefer that.
Quoted 2 lines
Last but not least the question is whether the kernel should care in general about the situation that a public address is deleted and orphaned temporary addresses are left behind.
I think that we should think of temporary addresses as stand-alone (IFA_F_MANAGETEMPADDR is a different story).

Quoted 9 lines

Btw. there was already lots of discussions whether automatically drop addresses of an interface in case of link-loss, you can read the IMHO most relevant here:
<http://markmail.org/thread/wcb6f6lcuyfuli7b>
Greetings,
Hannes

Thanks for the link, Hannes. Interesting read .. The discussion somehow stopped in the middle but they also tended to handle such issues in user space. Will think about it again, check the netifd sources and maybe follow-up on this with the OpenWRT guys.

Rgds, Heiner

Heiner Kallweit

author

2014-03-26 20:29 UTC #5 lore raw

In reply to Hannes Frederic Sowa

Am 19.03.2014 23:41, schrieb Hannes Frederic Sowa:

Quoted 55 lines · Heiner Kallweit

Quoted 21 lines
Am 19.03.2014 21:21, schrieb Hannes Frederic Sowa:
Quoted 20 lines · Heiner Kallweit
Quoted 4 lines
If a public address is deleted by an external trigger (e.g. via inet6_rtm_deladdr) then temporary addresses still referring to it may remain. Happened here when the WiFi link broke and netifd deleted the public address. Once the link was back and prefix_rcv created new public addresses ipv6_create_tempaddr complained that the temporary address already existed.
Which error was it specifically?
Quoted 2 lines
IMHO no temporary address should live longer than its parent, especially because ifpub of the temporary address still points to the then deleted public address otherwise.
Reference counting will take care of that.
Quoted 2 lines
Therefore delete all related temporary addresses before a public address is deleted in inet6_addr_del which is called by inet6_rtm_del.
I am a bit concerend with backward compatibility here.
Quoted 1 line
Also ensure in ipv6_del_addr that no temporary address lives longer than its parent.
I currently don't see a problem with that.
Greetings,
Quoted 7 lines
Quoted 3 lines
Hannes
The specific error was "retry temporary address regeneration" caused by ipv6_add_addr returning EEXIST.
First question is whether it's correct that in case of link loss the public address is deleted but not the temporary addresses. I don't think it's correct.
The kernel doesn't delete any addresses in case of link loss. netifd must have done so. In this case netifd should have flushed all addresses from the prefix.
Sure, this is racy and the error therefore looks justified for me.
Quoted 1 line
If it's not correct then the question is who's reponsibility it is to delete temporary addresses if the parent public address is deleted.
In my opinion those addresses are simple standalone addresses. The link to the public addresses is just for management purposes and should be hidden from user space.
So I would be ok, if we enhance the error case a bit, maybe reparent the old temporary address, drop them and silently generate them anew or only update prefix information from the new received prefix information. This should happen without disturbing TCP connections etc. I think this already works, but I don't know if it is worth the effort.
Quoted 2 lines
My solution was to do it in the kernel but this might not be the best / correct approach. Would you prefer that userspace / netifd take care to also delete the temporary addresses?
Yes, I would prefer that.
Quoted 2 lines
Last but not least the question is whether the kernel should care in general about the situation that a public address is deleted and orphaned temporary addresses are left behind.
I think that we should think of temporary addresses as stand-alone (IFA_F_MANAGETEMPADDR is a different story).

Quoted 7 lines

Btw. there was already lots of discussions whether automatically drop addresses of an interface in case of link-loss, you can read the IMHO most relevant here:
<http://markmail.org/thread/wcb6f6lcuyfuli7b>
Greetings,
Hannes

I spent some thoughts on this topic and it seems to me that deleting a temporary address from user space will break TCP connections most of the time as the newly created temporary address will be different from the old one.
Setting a temporary address to deprecated is also not possible from user space currently as netlink RTM_NEWADDR doesn't allow to modify the IFA_F_DEPRECATED flag:

/* We ignore other flags so far. */

	ifa_flags &= IFA_F_NODAD | IFA_F_HOMEADDRESS | IFA_F_MANAGETEMPADDR |
		     IFA_F_NOPREFIXROUTE;

Having said that your suggestion seems to be the most appropriate way to tackle the issue:

"So I would be ok, if we enhance the error case a bit, maybe reparent the old temporary address, drop them and silently generate them anew or only update prefix information from the new received prefix information. This should happen without disturbing TCP connections etc. I think this already works, but I don't know if it is worth the effort."

The following patch works fine for me, I'd appreciate if you could have a look at it.

Rgds, Heiner

net/ipv6/addrconf.c +17 -2

index 344e972..7cc3dae 100644
@@ -2063,8 +2063,23 @@ static void manage_tempaddrs(struct inet6_dev *idev,
     list_for_each_entry(ift, &idev->tempaddr_list, tmp_list) {
         int age, max_valid, max_prefered;
 
-        if (ifp != ift->ifpub)
-            continue;
+        spin_lock(&ift->lock);
+        if (ifp != ift->ifpub) {
+            /* reparent if orphaned temporary addresses with same prefix is found */
+            if(ift->prefix_len == ifp->prefix_len && ipv6_prefix_equal(&ift->addr,&ifp->addr,ift->prefix_len)) {
+                in6_ifa_hold(ifp);
+                in6_ifa_put(ift->ifpub);
+                ift->ifpub = ifp;
+                spin_unlock(&ift->lock);
+                create = false;
+                pr_info("%s: reparent orphaned temporary address\n", __func__);
+            } else {
+                spin_unlock(&ift->lock);
+                continue;
+            }
+        } else {
+            spin_unlock(&ift->lock);
+        }
 
         /* RFC 4941 section 3.3:
          * If a received option will extend the lifetime of a public

Heiner Kallweit

author

2014-03-26 21:50 UTC #6 lore raw

Am 26.03.2014 21:27, schrieb Heiner Kallweit:

Quoted 104 lines

Am 19.03.2014 23:41, schrieb Hannes Frederic Sowa:
Quoted 55 lines · Heiner Kallweit
Quoted 21 lines
Am 19.03.2014 21:21, schrieb Hannes Frederic Sowa:
Quoted 20 lines · Heiner Kallweit
Quoted 4 lines
If a public address is deleted by an external trigger (e.g. via inet6_rtm_deladdr) then temporary addresses still referring to it may remain. Happened here when the WiFi link broke and netifd deleted the public address. Once the link was back and prefix_rcv created new public addresses ipv6_create_tempaddr complained that the temporary address already existed.
Which error was it specifically?
Quoted 2 lines
IMHO no temporary address should live longer than its parent, especially because ifpub of the temporary address still points to the then deleted public address otherwise.
Reference counting will take care of that.
Quoted 2 lines
Therefore delete all related temporary addresses before a public address is deleted in inet6_addr_del which is called by inet6_rtm_del.
I am a bit concerend with backward compatibility here.
Quoted 1 line
Also ensure in ipv6_del_addr that no temporary address lives longer than its parent.
I currently don't see a problem with that.
Greetings,
Quoted 7 lines
Quoted 3 lines
Hannes
The specific error was "retry temporary address regeneration" caused by ipv6_add_addr returning EEXIST.
First question is whether it's correct that in case of link loss the public address is deleted but not the temporary addresses. I don't think it's correct.
The kernel doesn't delete any addresses in case of link loss. netifd must have done so. In this case netifd should have flushed all addresses from the prefix.
Sure, this is racy and the error therefore looks justified for me.
Quoted 1 line
If it's not correct then the question is who's reponsibility it is to delete temporary addresses if the parent public address is deleted.
In my opinion those addresses are simple standalone addresses. The link to the public addresses is just for management purposes and should be hidden from user space.
So I would be ok, if we enhance the error case a bit, maybe reparent the old temporary address, drop them and silently generate them anew or only update prefix information from the new received prefix information. This should happen without disturbing TCP connections etc. I think this already works, but I don't know if it is worth the effort.
Quoted 2 lines
My solution was to do it in the kernel but this might not be the best / correct approach. Would you prefer that userspace / netifd take care to also delete the temporary addresses?
Yes, I would prefer that.
Quoted 2 lines
Last but not least the question is whether the kernel should care in general about the situation that a public address is deleted and orphaned temporary addresses are left behind.
I think that we should think of temporary addresses as stand-alone (IFA_F_MANAGETEMPADDR is a different story).
Quoted 7 lines
Btw. there was already lots of discussions whether automatically drop addresses of an interface in case of link-loss, you can read the IMHO most relevant here:
<http://markmail.org/thread/wcb6f6lcuyfuli7b>
Greetings,
Hannes
I spent some thoughts on this topic and it seems to me that deleting a temporary address from user space will break TCP connections most of the time as the newly created temporary address will be different from the old one.
Setting a temporary address to deprecated is also not possible from user space currently as netlink RTM_NEWADDR doesn't allow to modify the IFA_F_DEPRECATED flag:
/* We ignore other flags so far. */
	ifa_flags &= IFA_F_NODAD | IFA_F_HOMEADDRESS | IFA_F_MANAGETEMPADDR |
		     IFA_F_NOPREFIXROUTE;
Having said that your suggestion seems to be the most appropriate way to tackle the issue:
"So I would be ok, if we enhance the error case a bit, maybe reparent the old temporary address, drop them and silently generate them anew or only update prefix information from the new received prefix information. This should happen without disturbing TCP connections etc. I think this already works, but I don't know if it is worth the effort."
The following patch works fine for me, I'd appreciate if you could have a look at it.
Rgds, Heiner
net/ipv6/addrconf.c +10 -2
index 344e972..7cc3dae 100644
@@ -2063,8 +2063,23 @@ static void manage_tempaddrs(struct inet6_dev *idev,
     list_for_each_entry(ift, &idev->tempaddr_list, tmp_list) {
         int age, max_valid, max_prefered;
 
-        if (ifp != ift->ifpub)
-            continue;
+        spin_lock(&ift->lock);
+        if (ifp != ift->ifpub) {
+            /* reparent if orphaned temporary addresses with same prefix is found */
+            if(ift->prefix_len == ifp->prefix_len && ipv6_prefix_equal(&ift->addr,&ifp->addr,ift->prefix_len)) {
+                in6_ifa_hold(ifp);
+                in6_ifa_put(ift->ifpub);
+                ift->ifpub = ifp;
+                spin_unlock(&ift->lock);
+                create = false;
+                pr_info("%s: reparent orphaned temporary address\n", __func__);

net/ipv6/addrconf.c static void manage_tempaddrs(struct inet6_dev *idev, · line 2085

Quoted 10 lines

net/ipv6/addrconf.c +7 -0

+            } else {
+                spin_unlock(&ift->lock);
+                continue;
+            }
+        } else {
+            spin_unlock(&ift->lock);
+        }
 
         /* RFC 4941 section 3.3:
          * If a received option will extend the lifetime of a public

After further checking it seems like the timer of the reparented temporary address was deleted. When the reparented address expires no new address is generated. Have to dig deeper into it ..

Rgds, Heiner

Hannes Frederic Sowa

2014-03-27 02:53 UTC #7 lore raw

Quoted 2 lines · Heiner Kallweit

Quoted 2 lines
I spent some thoughts on this topic and it seems to me that deleting a temporary address from user space will break TCP connections most of the time as the newly created temporary address will be different from the old one.

Yes, I can confirm that we will generate new rndid and thus will generate a new address.

Quoted 46 lines

Quoted 46 lines
Setting a temporary address to deprecated is also not possible from user space currently as netlink RTM_NEWADDR doesn't allow to modify the IFA_F_DEPRECATED flag:
/* We ignore other flags so far. */
	ifa_flags &= IFA_F_NODAD | IFA_F_HOMEADDRESS | IFA_F_MANAGETEMPADDR |
		     IFA_F_NOPREFIXROUTE;
Having said that your suggestion seems to be the most appropriate way to tackle the issue:
"So I would be ok, if we enhance the error case a bit, maybe reparent the old temporary address, drop them and silently generate them anew or only update prefix information from the new received prefix information. This should happen without disturbing TCP connections etc. I think this already works, but I don't know if it is worth the effort."
The following patch works fine for me, I'd appreciate if you could have a look at it.
Rgds, Heiner
net/ipv6/addrconf.c +17 -2
index 344e972..7cc3dae 100644
@@ -2063,8 +2063,23 @@ static void manage_tempaddrs(struct inet6_dev *idev,
     list_for_each_entry(ift, &idev->tempaddr_list, tmp_list) {
         int age, max_valid, max_prefered;
 
-        if (ifp != ift->ifpub)
-            continue;
+        spin_lock(&ift->lock);
+        if (ifp != ift->ifpub) {
+            /* reparent if orphaned temporary addresses with same prefix is found */
+            if(ift->prefix_len == ifp->prefix_len && ipv6_prefix_equal(&ift->addr,&ifp->addr,ift->prefix_len)) {
+                in6_ifa_hold(ifp);
+                in6_ifa_put(ift->ifpub);
+                ift->ifpub = ifp;
+                spin_unlock(&ift->lock);
+                create = false;
+                pr_info("%s: reparent orphaned temporary address\n", __func__);
+            } else {
+                spin_unlock(&ift->lock);
+                continue;
+            }
+        } else {
+            spin_unlock(&ift->lock);
+        }
 

Quoted 5 lines

net/ipv6/addrconf.c static void manage_tempaddrs(struct inet6_dev *idev, · line 2085
Quoted 3 lines
net/ipv6/addrconf.c +0 -0
         /* RFC 4941 section 3.3:
          * If a received option will extend the lifetime of a public
After further checking it seems like the timer of the reparented temporary address was deleted. When the reparented address expires no new address is generated. Have to dig deeper into it ..

You need to reset ift->regen_count=0 to avoid that I guess.

The approach seems reasonable to me.

Thanks,

Hannes

Heiner Kallweit

author

2014-04-06 19:04 UTC #8 lore raw

Am 27.03.2014 03:53, schrieb Hannes Frederic Sowa:

Quoted 57 lines · Heiner Kallweit

Quoted 2 lines
Quoted 2 lines
I spent some thoughts on this topic and it seems to me that deleting a temporary address from user space will break TCP connections most of the time as the newly created temporary address will be different from the old one.
Yes, I can confirm that we will generate new rndid and thus will generate a new address.
Quoted 46 lines
Quoted 46 lines
Setting a temporary address to deprecated is also not possible from user space currently as netlink RTM_NEWADDR doesn't allow to modify the IFA_F_DEPRECATED flag:
/* We ignore other flags so far. */
	ifa_flags &= IFA_F_NODAD | IFA_F_HOMEADDRESS | IFA_F_MANAGETEMPADDR |
		     IFA_F_NOPREFIXROUTE;
Having said that your suggestion seems to be the most appropriate way to tackle the issue:
"So I would be ok, if we enhance the error case a bit, maybe reparent the old temporary address, drop them and silently generate them anew or only update prefix information from the new received prefix information. This should happen without disturbing TCP connections etc. I think this already works, but I don't know if it is worth the effort."
The following patch works fine for me, I'd appreciate if you could have a look at it.
Rgds, Heiner
net/ipv6/addrconf.c +17 -2
index 344e972..7cc3dae 100644
@@ -2063,8 +2063,23 @@ static void manage_tempaddrs(struct inet6_dev *idev,
     list_for_each_entry(ift, &idev->tempaddr_list, tmp_list) {
         int age, max_valid, max_prefered;
 
-        if (ifp != ift->ifpub)
-            continue;
+        spin_lock(&ift->lock);
+        if (ifp != ift->ifpub) {
+            /* reparent if orphaned temporary addresses with same prefix is found */
+            if(ift->prefix_len == ifp->prefix_len && ipv6_prefix_equal(&ift->addr,&ifp->addr,ift->prefix_len)) {
+                in6_ifa_hold(ifp);
+                in6_ifa_put(ift->ifpub);
+                ift->ifpub = ifp;
+                spin_unlock(&ift->lock);
+                create = false;
+                pr_info("%s: reparent orphaned temporary address\n", __func__);
+            } else {
+                spin_unlock(&ift->lock);
+                continue;
+            }
+        } else {
+            spin_unlock(&ift->lock);
+        }
 
Quoted 5 lines
net/ipv6/addrconf.c static void manage_tempaddrs(struct inet6_dev *idev, · line 2085
Quoted 3 lines
net/ipv6/addrconf.c +0 -0
         /* RFC 4941 section 3.3:
          * If a received option will extend the lifetime of a public
After further checking it seems like the timer of the reparented temporary address was deleted. When the reparented address expires no new address is generated. Have to dig deeper into it ..

Quoted 8 lines

You need to reset ift->regen_count=0 to avoid that I guess.
The approach seems reasonable to me.
Thanks,
Hannes

Last problem I mentioned was caused by another issue. The decribed patch has been working fine in the meantime so I'll submit it to the list.

Rgds, Heiner