[PATCH] nfs: fix dead code of ipv6_addr_scope

[PATCH] nfs: fix dead code of ipv6_addr_scope

[Alexander Aring]

The correct way to check on IPV6_ADDR_SCOPE_LINKLOCAL is to check with
the ipv6_addr_src_scope function.

Currently this can't be work, because ipv6_addr_scope returns a int with
a mask of IPV6_ADDR_SCOPE_MASK (0x00f0U) and IPV6_ADDR_SCOPE_LINKLOCAL
is 0x02. So the condition is always false.

Signed-off-by: Alexander Aring <alex.aring-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
I think ipv6_addr_src_scope should be correct, can somebody from netdev ml
confirm this please?
I stumple over that and I did not compile and test it. Maybe this is something
for stable?

 fs/nfs/nfs4filelayoutdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/nfs4filelayoutdev.c b/fs/nfs/nfs4filelayoutdev.c
index c7c295e5..efac602 100644
--- a/fs/nfs/nfs4filelayoutdev.c
+++ b/fs/nfs/nfs4filelayoutdev.c
@@ -95,7 +95,7 @@ same_sockaddr(struct sockaddr *addr1, struct sockaddr *addr2)
 		b6 = (struct sockaddr_in6 *)addr2;
 
 		/* LINKLOCAL addresses must have matching scope_id */
-		if (ipv6_addr_scope(&a6->sin6_addr) ==
+		if (ipv6_addr_src_scope(&a6->sin6_addr) ==
 		    IPV6_ADDR_SCOPE_LINKLOCAL &&
 		    a6->sin6_scope_id != b6->sin6_scope_id)
 			return false;
-- 
1.8.5.2

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Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

[Alexander Aring]

Hi,

I saw right now file "./net/sctp/ipv6.c" in function sctp_v6_scope has
the same issue.

- Alex

Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

[Hannes Frederic Sowa]

On Sat, Dec 21, 2013 at 05:39:04AM +0100, Alexander Aring wrote:
> The correct way to check on IPV6_ADDR_SCOPE_LINKLOCAL is to check with
> the ipv6_addr_src_scope function.
> 
> Currently this can't be work, because ipv6_addr_scope returns a int with
> a mask of IPV6_ADDR_SCOPE_MASK (0x00f0U) and IPV6_ADDR_SCOPE_LINKLOCAL
> is 0x02. So the condition is always false.
> 
> Signed-off-by: Alexander Aring <alex.aring-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
> I think ipv6_addr_src_scope should be correct, can somebody from netdev ml
> confirm this please?
> I stumple over that and I did not compile and test it. Maybe this is something
> for stable?
> 
>  fs/nfs/nfs4filelayoutdev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/nfs/nfs4filelayoutdev.c b/fs/nfs/nfs4filelayoutdev.c
> index c7c295e5..efac602 100644
> --- a/fs/nfs/nfs4filelayoutdev.c
> +++ b/fs/nfs/nfs4filelayoutdev.c
> @@ -95,7 +95,7 @@ same_sockaddr(struct sockaddr *addr1, struct sockaddr *addr2)
>  		b6 = (struct sockaddr_in6 *)addr2;
>  
>  		/* LINKLOCAL addresses must have matching scope_id */
> -		if (ipv6_addr_scope(&a6->sin6_addr) ==
> +		if (ipv6_addr_src_scope(&a6->sin6_addr) ==
>  		    IPV6_ADDR_SCOPE_LINKLOCAL &&
>  		    a6->sin6_scope_id != b6->sin6_scope_id)
>  			return false;

Good catch!

SCOPE_TYPE also can be compared and is no bitfield, so the patch is
good. Do you mind also proposing a patch for sctp?

Thanks,

  Hannes

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Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

[Alexander Aring]

Hi Hannes,

On Sat, Dec 21, 2013 at 01:44:40PM +0100, Hannes Frederic Sowa wrote:
> On Sat, Dec 21, 2013 at 05:39:04AM +0100, Alexander Aring wrote:
> > The correct way to check on IPV6_ADDR_SCOPE_LINKLOCAL is to check with
> > the ipv6_addr_src_scope function.
> > 
> > Currently this can't be work, because ipv6_addr_scope returns a int with
> > a mask of IPV6_ADDR_SCOPE_MASK (0x00f0U) and IPV6_ADDR_SCOPE_LINKLOCAL
> > is 0x02. So the condition is always false.
> > 
> > Signed-off-by: Alexander Aring <alex.aring-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > ---
> > I think ipv6_addr_src_scope should be correct, can somebody from netdev ml
> > confirm this please?
> > I stumple over that and I did not compile and test it. Maybe this is something
> > for stable?
> > 
> >  fs/nfs/nfs4filelayoutdev.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/nfs/nfs4filelayoutdev.c b/fs/nfs/nfs4filelayoutdev.c
> > index c7c295e5..efac602 100644
> > --- a/fs/nfs/nfs4filelayoutdev.c
> > +++ b/fs/nfs/nfs4filelayoutdev.c
> > @@ -95,7 +95,7 @@ same_sockaddr(struct sockaddr *addr1, struct sockaddr *addr2)
> >  		b6 = (struct sockaddr_in6 *)addr2;
> >  
> >  		/* LINKLOCAL addresses must have matching scope_id */
> > -		if (ipv6_addr_scope(&a6->sin6_addr) ==
> > +		if (ipv6_addr_src_scope(&a6->sin6_addr) ==
> >  		    IPV6_ADDR_SCOPE_LINKLOCAL &&
> >  		    a6->sin6_scope_id != b6->sin6_scope_id)
> >  			return false;
> 
> Good catch!
> 
thanks.

I am still unsure if sctp is correct or not, I think it isn't correct.
Because we compare and don't check if any bit is set.

We don't use IPV6_ADDR_SCOPE_TYPE here. We use IPV6_ADDR_TYPE. But we can't
compare it.

Current implementation is:

	v6scope = ipv6_addr_scope(&addr->v6.sin6_addr);
        switch (v6scope) {      
        case IFA_HOST:          
                retval = SCTP_SCOPE_LOOPBACK;
                break;
        case IFA_LINK:
                retval = SCTP_SCOPE_LINK;
                break;
        case IFA_SITE:
                retval = SCTP_SCOPE_PRIVATE;
                break;
        default:
                retval = SCTP_SCOPE_GLOBAL;
                break;
        }

and should be something like:

        v6scope = ipv6_addr_src_scope(&addr->v6.sin6_addr);
        switch (v6scope) {      
        case IPV6_ADDR_SCOPE_NODELOCAL:          
                retval = SCTP_SCOPE_LOOPBACK;
                break;
        case IPV6_ADDR_SCOPE_LINKLOCAL:
                retval = SCTP_SCOPE_LINK;
                break;
        case IPV6_ADDR_SCOPE_SITELOCAL:
                retval = SCTP_SCOPE_PRIVATE;
                break;
	case IPV6_ADDR_SCOPE_GLOBAL:
                retval = SCTP_SCOPE_GLOBAL;
		break;
        default:
                retval = SCTP_SCOPE_UNUSABLE;
                break;
        }

Looks this okay for you? Then we can handle SCTP_SCOPE_UNUSABLE, too.

- Alex
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Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

[Hannes Frederic Sowa]

On Sat, Dec 21, 2013 at 02:32:54PM +0100, Alexander Aring wrote:
> Hi Hannes,
> 
> On Sat, Dec 21, 2013 at 01:44:40PM +0100, Hannes Frederic Sowa wrote:
> > On Sat, Dec 21, 2013 at 05:39:04AM +0100, Alexander Aring wrote:
> > > The correct way to check on IPV6_ADDR_SCOPE_LINKLOCAL is to check with
> > > the ipv6_addr_src_scope function.
> > > 
> > > Currently this can't be work, because ipv6_addr_scope returns a int with
> > > a mask of IPV6_ADDR_SCOPE_MASK (0x00f0U) and IPV6_ADDR_SCOPE_LINKLOCAL
> > > is 0x02. So the condition is always false.
> > > 
> > > Signed-off-by: Alexander Aring <alex.aring-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > > ---
> > > I think ipv6_addr_src_scope should be correct, can somebody from netdev ml
> > > confirm this please?
> > > I stumple over that and I did not compile and test it. Maybe this is something
> > > for stable?
> > > 
> > >  fs/nfs/nfs4filelayoutdev.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/fs/nfs/nfs4filelayoutdev.c b/fs/nfs/nfs4filelayoutdev.c
> > > index c7c295e5..efac602 100644
> > > --- a/fs/nfs/nfs4filelayoutdev.c
> > > +++ b/fs/nfs/nfs4filelayoutdev.c
> > > @@ -95,7 +95,7 @@ same_sockaddr(struct sockaddr *addr1, struct sockaddr *addr2)
> > >  		b6 = (struct sockaddr_in6 *)addr2;
> > >  
> > >  		/* LINKLOCAL addresses must have matching scope_id */
> > > -		if (ipv6_addr_scope(&a6->sin6_addr) ==
> > > +		if (ipv6_addr_src_scope(&a6->sin6_addr) ==
> > >  		    IPV6_ADDR_SCOPE_LINKLOCAL &&
> > >  		    a6->sin6_scope_id != b6->sin6_scope_id)
> > >  			return false;
> > 
> > Good catch!
> > 
> thanks.
> 
> I am still unsure if sctp is correct or not, I think it isn't correct.
> Because we compare and don't check if any bit is set.
> 
> We don't use IPV6_ADDR_SCOPE_TYPE here. We use IPV6_ADDR_TYPE. But we can't
> compare it.

Actually, this is fine, too. ipv6_addr_scope does mask the addr_type with
IPV6_ADDR_SCOPE_MASK (which is 0x00f0U). If you look at addrconf_core.c you
see that the 4 bits stand by itself each time.

Actually it seems ipv6_addr_src_scope is better suitable for multicast scope
handling and ipv6_addr_scope with IFA_{HOST,LINK,SITE} is fine for
non-multicast. In this case there is no difference.

Maybe an int ipv6_cmp_sockaddr(struct in6_addr *a1, int scope1,
			  struct in6_addr *a2, int scope2)
or
int ipv6_cmp_sockaddr(struct sockaddr_in6 *s1,
		      struct sockaddr_in6 *s2)

would be nice so we don't need to open code it everywhere.

Greetings,

  Hannes

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Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

[Alexander Aring]

Hi Hannes,

On Sun, Dec 22, 2013 at 03:30:54AM +0100, Hannes Frederic Sowa wrote:
> On Sat, Dec 21, 2013 at 02:32:54PM +0100, Alexander Aring wrote:
> > Hi Hannes,
> > 
> > On Sat, Dec 21, 2013 at 01:44:40PM +0100, Hannes Frederic Sowa wrote:
> > > On Sat, Dec 21, 2013 at 05:39:04AM +0100, Alexander Aring wrote:
> > > > The correct way to check on IPV6_ADDR_SCOPE_LINKLOCAL is to check with
> > > > the ipv6_addr_src_scope function.
> > > > 
> > > > Currently this can't be work, because ipv6_addr_scope returns a int with
> > > > a mask of IPV6_ADDR_SCOPE_MASK (0x00f0U) and IPV6_ADDR_SCOPE_LINKLOCAL
> > > > is 0x02. So the condition is always false.
> > > > 
> > > > Signed-off-by: Alexander Aring <alex.aring-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > > > ---
> > > > I think ipv6_addr_src_scope should be correct, can somebody from netdev ml
> > > > confirm this please?
> > > > I stumple over that and I did not compile and test it. Maybe this is something
> > > > for stable?
> > > > 
> > > >  fs/nfs/nfs4filelayoutdev.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/fs/nfs/nfs4filelayoutdev.c b/fs/nfs/nfs4filelayoutdev.c
> > > > index c7c295e5..efac602 100644
> > > > --- a/fs/nfs/nfs4filelayoutdev.c
> > > > +++ b/fs/nfs/nfs4filelayoutdev.c
> > > > @@ -95,7 +95,7 @@ same_sockaddr(struct sockaddr *addr1, struct sockaddr *addr2)
> > > >  		b6 = (struct sockaddr_in6 *)addr2;
> > > >  
> > > >  		/* LINKLOCAL addresses must have matching scope_id */
> > > > -		if (ipv6_addr_scope(&a6->sin6_addr) ==
> > > > +		if (ipv6_addr_src_scope(&a6->sin6_addr) ==
> > > >  		    IPV6_ADDR_SCOPE_LINKLOCAL &&
> > > >  		    a6->sin6_scope_id != b6->sin6_scope_id)
> > > >  			return false;
> > > 
> > > Good catch!
> > > 
> > thanks.
> > 
> > I am still unsure if sctp is correct or not, I think it isn't correct.
> > Because we compare and don't check if any bit is set.
> > 
> > We don't use IPV6_ADDR_SCOPE_TYPE here. We use IPV6_ADDR_TYPE. But we can't
> > compare it.
> 
> Actually, this is fine, too. ipv6_addr_scope does mask the addr_type with
> IPV6_ADDR_SCOPE_MASK (which is 0x00f0U). If you look at addrconf_core.c you
> see that the 4 bits stand by itself each time.
> 
> Actually it seems ipv6_addr_src_scope is better suitable for multicast scope
> handling and ipv6_addr_scope with IFA_{HOST,LINK,SITE} is fine for
> non-multicast. In this case there is no difference.
> 
ah thanks, now I understand it!

so an alternative would be:

if (ipv6_addr_scope(&a6->sin6_addr) & IPV6_ADDR_LINKLOCAL &&
	a6->sin6_scope_id != b6->sin6_scope_id)
	...

maybe this is a little bit faster instead of ipv6_addr_src_scope.
Should I resend a v2 with the faster solution?

> Maybe an int ipv6_cmp_sockaddr(struct in6_addr *a1, int scope1,
> 			  struct in6_addr *a2, int scope2)
> or
> int ipv6_cmp_sockaddr(struct sockaddr_in6 *s1,
> 		      struct sockaddr_in6 *s2)
> 

I don't understand why we need such a function here. We only check if
"a6" is linklocal and has a different sin6_scope_id than "b6" sin6_scope_id
and we don't compare "a6" and "b6" here (then "b6" should be a
linklocal, too). I think it's too abstract for me what exactly "compare"
means in this case. :-)

- Alex
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Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

[Hannes Frederic Sowa]

On Sun, Dec 22, 2013 at 01:30:14PM +0100, Alexander Aring wrote:
> On Sun, Dec 22, 2013 at 03:30:54AM +0100, Hannes Frederic Sowa wrote:
> > On Sat, Dec 21, 2013 at 02:32:54PM +0100, Alexander Aring wrote:
> > > Hi Hannes,
> > > 
> > > On Sat, Dec 21, 2013 at 01:44:40PM +0100, Hannes Frederic Sowa wrote:
> > > > On Sat, Dec 21, 2013 at 05:39:04AM +0100, Alexander Aring wrote:
> > > > > The correct way to check on IPV6_ADDR_SCOPE_LINKLOCAL is to check with
> > > > > the ipv6_addr_src_scope function.
> > > > > 
> > > > > Currently this can't be work, because ipv6_addr_scope returns a int with
> > > > > a mask of IPV6_ADDR_SCOPE_MASK (0x00f0U) and IPV6_ADDR_SCOPE_LINKLOCAL
> > > > > is 0x02. So the condition is always false.
> > > > > 
> > > > > Signed-off-by: Alexander Aring <alex.aring-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > > > > ---
> > > > > I think ipv6_addr_src_scope should be correct, can somebody from netdev ml
> > > > > confirm this please?
> > > > > I stumple over that and I did not compile and test it. Maybe this is something
> > > > > for stable?
> > > > > 
> > > > >  fs/nfs/nfs4filelayoutdev.c | 2 +-
> > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/fs/nfs/nfs4filelayoutdev.c b/fs/nfs/nfs4filelayoutdev.c
> > > > > index c7c295e5..efac602 100644
> > > > > --- a/fs/nfs/nfs4filelayoutdev.c
> > > > > +++ b/fs/nfs/nfs4filelayoutdev.c
> > > > > @@ -95,7 +95,7 @@ same_sockaddr(struct sockaddr *addr1, struct sockaddr *addr2)
> > > > >  		b6 = (struct sockaddr_in6 *)addr2;
> > > > >  
> > > > >  		/* LINKLOCAL addresses must have matching scope_id */
> > > > > -		if (ipv6_addr_scope(&a6->sin6_addr) ==
> > > > > +		if (ipv6_addr_src_scope(&a6->sin6_addr) ==
> > > > >  		    IPV6_ADDR_SCOPE_LINKLOCAL &&
> > > > >  		    a6->sin6_scope_id != b6->sin6_scope_id)
> > > > >  			return false;
> > > > 
> > > > Good catch!
> > > > 
> > > thanks.
> > > 
> > > I am still unsure if sctp is correct or not, I think it isn't correct.
> > > Because we compare and don't check if any bit is set.
> > > 
> > > We don't use IPV6_ADDR_SCOPE_TYPE here. We use IPV6_ADDR_TYPE. But we can't
> > > compare it.
> > 
> > Actually, this is fine, too. ipv6_addr_scope does mask the addr_type with
> > IPV6_ADDR_SCOPE_MASK (which is 0x00f0U). If you look at addrconf_core.c you
> > see that the 4 bits stand by itself each time.
> > 
> > Actually it seems ipv6_addr_src_scope is better suitable for multicast scope
> > handling and ipv6_addr_scope with IFA_{HOST,LINK,SITE} is fine for
> > non-multicast. In this case there is no difference.
> > 
> ah thanks, now I understand it!
> 
> so an alternative would be:
> 
> if (ipv6_addr_scope(&a6->sin6_addr) & IPV6_ADDR_LINKLOCAL &&
> 	a6->sin6_scope_id != b6->sin6_scope_id)
> 	...
> 
> maybe this is a little bit faster instead of ipv6_addr_src_scope.
> Should I resend a v2 with the faster solution?

Yes, please do so. Thanks!

> > Maybe an int ipv6_cmp_sockaddr(struct in6_addr *a1, int scope1,
> > 			  struct in6_addr *a2, int scope2)
> > or
> > int ipv6_cmp_sockaddr(struct sockaddr_in6 *s1,
> > 		      struct sockaddr_in6 *s2)
> > 
> 
> I don't understand why we need such a function here. We only check if
> "a6" is linklocal and has a different sin6_scope_id than "b6" sin6_scope_id
> and we don't compare "a6" and "b6" here (then "b6" should be a
> linklocal, too). I think it's too abstract for me what exactly "compare"
> means in this case. :-)

That were exactly the semantics I had in mind. Something like
ipv6_equal_sockaddr would be a better name, you are right.

Trying to sort ipv6 addresses depends on the specific code and I would
leave that open-coded in the specific case.

Greetings,

  Hannes

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