| Message ID | 20110322.215655.245381151.davem@davemloft.net |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
Hello, On Tue, 22 Mar 2011, David Miller wrote: > I just got back to this, sorry for taking so long :-) > > Here is the patch I've come up with and will commit to > net-2.6, thanks! > > -------------------- > ipv4: Fallback to FIB local table in __ip_dev_find(). > > In commit 9435eb1cf0b76b323019cebf8d16762a50a12a19 > ("ipv4: Implement __ip_dev_find using new interface address hash.") > we reimplemented __ip_dev_find() so that it doesn't have to > do a full FIB table lookup. > > Instead, it consults a hash table of addresses configured to > interfaces. > > This works identically to the old code in all except one case, > and that is for loopback subnets. > > The old code would match the loopback device for any IP address > that falls within a subnet configured to the loopback device. > > Handle this corner case by doing the FIB lookup. > > We could implement this via inet_addr_onlink() but: > > 1) Someone could configure many addresses to loopback and > inet_addr_onlink() is a simple list traversal. > > 2) We know the old code works. > > Reported-by: Julian Anastasov <ja@ssi.bg> > Signed-off-by: David S. Miller <davem@davemloft.net> > --- > net/ipv4/devinet.c | 16 ++++++++++++++++ > 1 files changed, 16 insertions(+), 0 deletions(-) > > diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c > index d5a4553..5345b0b 100644 > --- a/net/ipv4/devinet.c > +++ b/net/ipv4/devinet.c > @@ -64,6 +64,8 @@ > #include <net/rtnetlink.h> > #include <net/net_namespace.h> > > +#include "fib_lookup.h" > + > static struct ipv4_devconf ipv4_devconf = { > .data = { > [IPV4_DEVCONF_ACCEPT_REDIRECTS - 1] = 1, > @@ -151,6 +153,20 @@ struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref) > break; > } > } > + if (!result) { > + struct flowi4 fl4 = { .daddr = addr }; > + struct fib_result res = { 0 }; > + struct fib_table *local; > + > + /* Fallback to FIB local table so that communication > + * over loopback subnets work. > + */ > + local = fib_get_table(net, RT_TABLE_LOCAL); > + if (local && > + !fib_table_lookup(local, &fl4, &res, FIB_LOOKUP_NOREF) && > + res.type == RTN_LOCAL) > + result = FIB_RES_DEV(res); > + } > if (result && devref) > dev_hold(result); > rcu_read_unlock(); > -- > 1.7.4.1 Not tested but looks ok for me. Regards -- Julian Anastasov <ja@ssi.bg> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 22 Mar 2011 21:56:55 -0700 (PDT) David Miller <davem@davemloft.net> wrote: > From: Julian Anastasov <ja@ssi.bg> > Date: Fri, 4 Mar 2011 10:39:55 +0200 (EET) > > > On Thu, 3 Mar 2011, David Miller wrote: > > > >> I suspect that even if we need to handle prefixes, we can still use > >> the hash for optimistic lookup, and fallback to a local table FIB > >> inspection if that fails. > > > > Yes, as ip_route_output_slow uses __ip_dev_find for > > fl4_src there should be some kind of fallback to local table, > > so that traffic from 127.0.0.2 to 127.0.0.3 or other local > > subnets on loopback can work. Another option is to use > > inet_addr_onlink but I suspect people can add many addresses > > on loopback: inet_addr_onlink(loopback_indev, addr, 0) > > I just got back to this, sorry for taking so long :-) > > Here is the patch I've come up with and will commit to > net-2.6, thanks! > > -------------------- > ipv4: Fallback to FIB local table in __ip_dev_find(). > > In commit 9435eb1cf0b76b323019cebf8d16762a50a12a19 > ("ipv4: Implement __ip_dev_find using new interface address hash.") > we reimplemented __ip_dev_find() so that it doesn't have to > do a full FIB table lookup. > > Instead, it consults a hash table of addresses configured to > interfaces. > > This works identically to the old code in all except one case, > and that is for loopback subnets. > > The old code would match the loopback device for any IP address > that falls within a subnet configured to the loopback device. > > Handle this corner case by doing the FIB lookup. > > We could implement this via inet_addr_onlink() but: > > 1) Someone could configure many addresses to loopback and > inet_addr_onlink() is a simple list traversal. > > 2) We know the old code works. > > Reported-by: Julian Anastasov <ja@ssi.bg> > Signed-off-by: David S. Miller <davem@davemloft.net> > --- > net/ipv4/devinet.c | 16 ++++++++++++++++ > 1 files changed, 16 insertions(+), 0 deletions(-) > > diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c > index d5a4553..5345b0b 100644 > --- a/net/ipv4/devinet.c > +++ b/net/ipv4/devinet.c > @@ -64,6 +64,8 @@ > #include <net/rtnetlink.h> > #include <net/net_namespace.h> > > +#include "fib_lookup.h" > + > static struct ipv4_devconf ipv4_devconf = { > .data = { > [IPV4_DEVCONF_ACCEPT_REDIRECTS - 1] = 1, > @@ -151,6 +153,20 @@ struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref) > break; > } > } > + if (!result) { > + struct flowi4 fl4 = { .daddr = addr }; > + struct fib_result res = { 0 }; > + struct fib_table *local; > + > + /* Fallback to FIB local table so that communication > + * over loopback subnets work. > + */ > + local = fib_get_table(net, RT_TABLE_LOCAL); > + if (local && > + !fib_table_lookup(local, &fl4, &res, FIB_LOOKUP_NOREF) && > + res.type == RTN_LOCAL) > + result = FIB_RES_DEV(res); > + } > if (result && devref) > dev_hold(result); > rcu_read_unlock(); Acked-by: Stephen Hemminger <shemminger@vyatta.com>
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index d5a4553..5345b0b 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -64,6 +64,8 @@ #include <net/rtnetlink.h> #include <net/net_namespace.h> +#include "fib_lookup.h" + static struct ipv4_devconf ipv4_devconf = { .data = { [IPV4_DEVCONF_ACCEPT_REDIRECTS - 1] = 1, @@ -151,6 +153,20 @@ struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref) break; } } + if (!result) { + struct flowi4 fl4 = { .daddr = addr }; + struct fib_result res = { 0 }; + struct fib_table *local; + + /* Fallback to FIB local table so that communication + * over loopback subnets work. + */ + local = fib_get_table(net, RT_TABLE_LOCAL); + if (local && + !fib_table_lookup(local, &fl4, &res, FIB_LOOKUP_NOREF) && + res.type == RTN_LOCAL) + result = FIB_RES_DEV(res); + } if (result && devref) dev_hold(result); rcu_read_unlock();