[PATCH net] ipv6: avoid dad-failures for addresses with NODAD

[PATCH net] ipv6: avoid dad-failures for addresses with NODAD

[Mahesh Bandewar]

From: Mahesh Bandewar <maheshb@google.com>

Every address gets added with TENTATIVE flag even for the addresses with
IFA_F_NODAD flag and dad-work is scheduled for them. During this DAD process
we realize it's an address with NODAD and complete the process without
sending any probe. However the TENTATIVE flags stays on the
address for sometime enough to cause misinterpretation when we receive a NS.
While processing NS, if the address has TENTATIVE flag, we mark it DADFAILED
and endup with an address that was originally configured as NODAD with
DADFAILED.

We can't avoid scheduling dad_work for addresses with NODAD but we can
avoid adding TENTATIVE flag to avoid this racy situation.

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
---
 net/ipv6/addrconf.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index b09ac38d8dc4..53f2dc092023 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1022,7 +1022,10 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr,
 	INIT_HLIST_NODE(&ifa->addr_lst);
 	ifa->scope = scope;
 	ifa->prefix_len = pfxlen;
-	ifa->flags = flags | IFA_F_TENTATIVE;
+	ifa->flags = flags;
+	/* No need to add the TENTATIVE flag for addresses with NODAD */
+	if (!(flags & IFA_F_NODAD))
+		ifa->flags |= IFA_F_TENTATIVE;
 	ifa->valid_lft = valid_lft;
 	ifa->prefered_lft = prefered_lft;
 	ifa->cstamp = ifa->tstamp = jiffies;
-- 
2.13.0.rc2.291.g57267f2277-goog

Re: [PATCH net] ipv6: avoid dad-failures for addresses with NODAD

[David Ahern]

On 5/12/17 6:03 PM, Mahesh Bandewar wrote:
> From: Mahesh Bandewar <maheshb@google.com>
> 
> Every address gets added with TENTATIVE flag even for the addresses with
> IFA_F_NODAD flag and dad-work is scheduled for them. During this DAD process
> we realize it's an address with NODAD and complete the process without
> sending any probe. However the TENTATIVE flags stays on the
> address for sometime enough to cause misinterpretation when we receive a NS.
> While processing NS, if the address has TENTATIVE flag, we mark it DADFAILED
> and endup with an address that was originally configured as NODAD with
> DADFAILED.
> 
> We can't avoid scheduling dad_work for addresses with NODAD but we can
> avoid adding TENTATIVE flag to avoid this racy situation.
> 
> Signed-off-by: Mahesh Bandewar <maheshb@google.com>
> ---
>  net/ipv6/addrconf.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index b09ac38d8dc4..53f2dc092023 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -1022,7 +1022,10 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr,
>  	INIT_HLIST_NODE(&ifa->addr_lst);
>  	ifa->scope = scope;
>  	ifa->prefix_len = pfxlen;
> -	ifa->flags = flags | IFA_F_TENTATIVE;
> +	ifa->flags = flags;
> +	/* No need to add the TENTATIVE flag for addresses with NODAD */
> +	if (!(flags & IFA_F_NODAD))
> +		ifa->flags |= IFA_F_TENTATIVE;
>  	ifa->valid_lft = valid_lft;
>  	ifa->prefered_lft = prefered_lft;
>  	ifa->cstamp = ifa->tstamp = jiffies;
> 

LGTM.

Acked-by: David Ahern <dsahern@gmail.com>

Re: [PATCH net] ipv6: avoid dad-failures for addresses with NODAD

[David Miller]

From: Mahesh Bandewar <mahesh@bandewar.net>
Date: Fri, 12 May 2017 17:03:39 -0700

> From: Mahesh Bandewar <maheshb@google.com>
> 
> Every address gets added with TENTATIVE flag even for the addresses with
> IFA_F_NODAD flag and dad-work is scheduled for them. During this DAD process
> we realize it's an address with NODAD and complete the process without
> sending any probe. However the TENTATIVE flags stays on the
> address for sometime enough to cause misinterpretation when we receive a NS.
> While processing NS, if the address has TENTATIVE flag, we mark it DADFAILED
> and endup with an address that was originally configured as NODAD with
> DADFAILED.
> 
> We can't avoid scheduling dad_work for addresses with NODAD but we can
> avoid adding TENTATIVE flag to avoid this racy situation.
> 
> Signed-off-by: Mahesh Bandewar <maheshb@google.com>

This doesn't apply cleanly to the net tree, please respin.

Thank you.

Re: [PATCH net] ipv6: avoid dad-failures for addresses with NODAD

[David Miller]

From: David Miller <davem@davemloft.net>
Date: Mon, 15 May 2017 14:26:55 -0400 (EDT)

> From: Mahesh Bandewar <mahesh@bandewar.net>
> Date: Fri, 12 May 2017 17:03:39 -0700
> 
>> From: Mahesh Bandewar <maheshb@google.com>
>> 
>> Every address gets added with TENTATIVE flag even for the addresses with
>> IFA_F_NODAD flag and dad-work is scheduled for them. During this DAD process
>> we realize it's an address with NODAD and complete the process without
>> sending any probe. However the TENTATIVE flags stays on the
>> address for sometime enough to cause misinterpretation when we receive a NS.
>> While processing NS, if the address has TENTATIVE flag, we mark it DADFAILED
>> and endup with an address that was originally configured as NODAD with
>> DADFAILED.
>> 
>> We can't avoid scheduling dad_work for addresses with NODAD but we can
>> avoid adding TENTATIVE flag to avoid this racy situation.
>> 
>> Signed-off-by: Mahesh Bandewar <maheshb@google.com>
> 
> This doesn't apply cleanly to the net tree, please respin.

Ignore this, I was trying to apply the wrong patch.

Applied, thank you.