2013-12-21 04:39:14

by Alexander Aring

[permalink] [raw]
Subject: [PATCH] nfs: fix dead code of ipv6_addr_scope

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 <[email protected]>
---
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



2013-12-21 12:44:42

by Hannes Frederic Sowa

[permalink] [raw]
Subject: Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

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 <[email protected]>
> ---
> 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


2013-12-22 02:30:57

by Hannes Frederic Sowa

[permalink] [raw]
Subject: Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

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 <[email protected]>
> > > ---
> > > 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


2013-12-21 13:33:01

by Alexander Aring

[permalink] [raw]
Subject: Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

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 <[email protected]>
> > ---
> > 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

2013-12-22 12:30:22

by Alexander Aring

[permalink] [raw]
Subject: Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

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 <[email protected]>
> > > > ---
> > > > 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

2013-12-22 12:38:38

by Hannes Frederic Sowa

[permalink] [raw]
Subject: Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

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 <[email protected]>
> > > > > ---
> > > > > 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


2013-12-21 08:17:14

by Alexander Aring

[permalink] [raw]
Subject: Re: [PATCH] nfs: fix dead code of ipv6_addr_scope

Hi,

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

- Alex