On Wed, 9 Dec 2009 13:50:50 -0500
"J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
> On Tue, Dec 08, 2009 at 03:44:51PM -0500, Jeff Layton wrote:
> > Recent kernels (2.6.32) have started displaying the scopeid for some
> > addresses in the upcall.
>
> Does this mean we lost compatibility with old gssd's?
>
> (Would it be better to keep the "address" line the same (if that's the
> problematic line), and add a new line that old gssd's can avoid?)
>
> Or are the new addresses only going to occur in cases that would have
> stumped old gssd's anyway? (In which case, how did old gssd's fail?)
>
The problem is only with IPv6 addresses (obviously) and even then, it
only tacks them onto certain addresses -- link-local and site-local
addrs. I only happened to notice because I was using a site-local
prefix on a private network segment for testing.
IMO, NFS+IPv6+krb5 is new enough that we can just chalk this up to a bug
and not worry too much about backward compatibility.
I think the only real kernel changes that we need to consider are:
1) should site-local addresses have a scopeid appended to them at all
when displayed in presentation format?
2) should we avoid displaying the scopeid on any address when it's 0?
The RFC's surrounding site-local addresses are very confusing and often
contradictory unfortunately so Chuck has been trying to get
clarification on the netdev list. They've been deprecated in some later
RFC's but we're still a bit unclear on what that means.
Most of the existing code out there seems to treat a zero scopeid and
an absent scopeid the same, so I think the answer to #2 should probably
be "yes".
>
> > gssd doesn't know how to deal with them. Change
> > gssd to use getaddrinfo instead of inet_pton since that can deal with
> > scopeid's in addresses. That also allows us to elminate the port
> > conversion in read_service_info.
> >
> > If getaddrinfo returns an address with a non-zero sin6_scope_id however,
> > reject it. getnameinfo ignores that field and just uses the sin6_addr
> > part when resolving. But, two addresses that differ only in
> > sin6_scope_id could refer to completely different hosts.
> >
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > ---
> > utils/gssd/gssd_proc.c | 60 ++++++++++++++++++++++++++++--------------------
> > 1 files changed, 35 insertions(+), 25 deletions(-)
> >
> > diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
> > index 33a31c3..795e06c 100644
> > --- a/utils/gssd/gssd_proc.c
> > +++ b/utils/gssd/gssd_proc.c
> > @@ -108,7 +108,7 @@ int pollsize; /* the size of pollaray (in pollfd's) */
> >
> > /*
> > * convert a presentation address string to a sockaddr_storage struct. Returns
> > - * true on success and false on failure.
> > + * true on success or false on failure.
> > *
> > * Note that we do not populate the sin6_scope_id field here for IPv6 addrs.
> > * gssd nececessarily relies on hostname resolution and DNS AAAA records
> > @@ -120,26 +120,43 @@ int pollsize; /* the size of pollaray (in pollfd's) */
> > * not really feasible at present.
> > */
> > static int
> > -addrstr_to_sockaddr(struct sockaddr *sa, const char *addr, const int port)
> > +addrstr_to_sockaddr(struct sockaddr *sa, const char *node, const char *port)
> > {
> > - struct sockaddr_in *s4 = (struct sockaddr_in *) sa;
> > -#ifdef IPV6_SUPPORTED
> > - struct sockaddr_in6 *s6 = (struct sockaddr_in6 *) sa;
> > -#endif /* IPV6_SUPPORTED */
> > + int rc;
> > + struct addrinfo *res;
> > + struct addrinfo hints = { .ai_flags = AI_NUMERICHOST | AI_NUMERICSERV };
> >
> > - if (inet_pton(AF_INET, addr, &s4->sin_addr)) {
> > - s4->sin_family = AF_INET;
> > - s4->sin_port = htons(port);
> > -#ifdef IPV6_SUPPORTED
> > - } else if (inet_pton(AF_INET6, addr, &s6->sin6_addr)) {
> > - s6->sin6_family = AF_INET6;
> > - s6->sin6_port = htons(port);
> > +#ifndef IPV6_SUPPORTED
> > + hints.ai_family = AF_INET;
> > #endif /* IPV6_SUPPORTED */
> > - } else {
> > - printerr(0, "ERROR: unable to convert %s to address\n", addr);
> > +
> > + rc = getaddrinfo(node, port, &hints, &res);
> > + if (rc) {
> > + printerr(0, "ERROR: unable to convert %s|%s to sockaddr: %s\n",
> > + node, port, rc == EAI_SYSTEM ? strerror(errno) :
> > + gai_strerror(rc));
> > return 0;
> > }
> >
> > +#ifdef IPV6_SUPPORTED
> > + /*
> > + * getnameinfo ignores the scopeid. If the address turns out to have
> > + * a non-zero scopeid, we can't use it -- the resolved host might be
> > + * completely different from the one intended.
> > + */
> > + if (res->ai_addr->sa_family == AF_INET6) {
> > + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)res->ai_addr;
> > + if (sin6->sin6_scope_id) {
> > + printerr(0, "ERROR: address %s has non-zero "
> > + "sin6_scope_id!\n", node);
> > + freeaddrinfo(res);
> > + return 0;
> > + }
> > + }
> > +#endif /* IPV6_SUPPORTED */
> > +
> > + memcpy(sa, res->ai_addr, res->ai_addrlen);
> > + freeaddrinfo(res);
> > return 1;
> > }
> >
> > @@ -197,11 +214,10 @@ read_service_info(char *info_file_name, char **servicename, char **servername,
> > char program[16];
> > char version[16];
> > char protoname[16];
> > - char cb_port[128];
> > + char port[128];
> > char *p;
> > int fd = -1;
> > int numfields;
> > - int port = 0;
> >
> > *servicename = *servername = *protocol = NULL;
> >
> > @@ -230,9 +246,9 @@ read_service_info(char *info_file_name, char **servicename, char **servername,
> > goto fail;
> > }
> >
> > - cb_port[0] = '\0';
> > + port[0] = '\0';
> > if ((p = strstr(buf, "port")) != NULL)
> > - sscanf(p, "port: %127s\n", cb_port);
> > + sscanf(p, "port: %127s\n", port);
> >
> > /* check service, program, and version */
> > if (memcmp(service, "nfs", 3) != 0)
> > @@ -249,12 +265,6 @@ read_service_info(char *info_file_name, char **servicename, char **servername,
> > goto fail;
> > }
> >
> > - if (cb_port[0] != '\0') {
> > - port = atoi(cb_port);
> > - if (port < 0 || port > 65535)
> > - goto fail;
> > - }
> > -
> > if (!addrstr_to_sockaddr(addr, address, port))
> > goto fail;
> >
> > --
> > 1.6.5.2
> >
--
Jeff Layton <jlayton@xxxxxxxxxx>
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