diff -urp v2.6.25/linux/Documentation/filesystems/proc.txt linux/Documentation/filesystems/proc.txt --- v2.6.25/linux/Documentation/filesystems/proc.txt 2008-04-17 09:57:59.000000000 +0300 +++ linux/Documentation/filesystems/proc.txt 2008-04-19 18:42:08.000000000 +0300 @@ -1905,6 +1905,15 @@ log_martians Log packets with source addresses with no known route to kernel log. +loop +---- + +By default (loop=0) the traffic between local IP addresses +is routed via interface "lo". Setting this flag for two +interfaces allows traffic between their IP addresses to +be looped externally. This is useful for setups where the +interfaces are attached to same broadcast medium. + mc_forwarding ------------- diff -urp v2.6.25/linux/Documentation/networking/ip-sysctl.txt linux/Documentation/networking/ip-sysctl.txt --- v2.6.25/linux/Documentation/networking/ip-sysctl.txt 2008-04-17 09:57:59.000000000 +0300 +++ linux/Documentation/networking/ip-sysctl.txt 2008-04-19 18:42:08.000000000 +0300 @@ -627,6 +627,13 @@ accept_redirects - BOOLEAN forwarding - BOOLEAN Enable IP forwarding on this interface. +loop - BOOLEAN + By default (loop=0) the traffic between local IP addresses + is routed via interface "lo". Setting this flag for two + interfaces allows traffic between their IP addresses to + be looped externally. This is useful for setups where the + interfaces are attached to same broadcast medium. + mc_forwarding - BOOLEAN Do multicast routing. The kernel needs to be compiled with CONFIG_MROUTE and a multicast routing daemon is required. diff -urp v2.6.25/linux/include/linux/inetdevice.h linux/include/linux/inetdevice.h --- v2.6.25/linux/include/linux/inetdevice.h 2008-04-17 09:58:08.000000000 +0300 +++ linux/include/linux/inetdevice.h 2008-04-19 18:42:08.000000000 +0300 @@ -105,6 +105,7 @@ static inline void ipv4_devconf_setall(s IN_DEV_ORCONF((in_dev), ACCEPT_REDIRECTS))) #define IN_DEV_ARPFILTER(in_dev) IN_DEV_ORCONF((in_dev), ARPFILTER) +#define IN_DEV_LOOP(in_dev) IN_DEV_CONF_GET(in_dev, LOOP) #define IN_DEV_ARP_ANNOUNCE(in_dev) IN_DEV_MAXCONF((in_dev), ARP_ANNOUNCE) #define IN_DEV_ARP_IGNORE(in_dev) IN_DEV_MAXCONF((in_dev), ARP_IGNORE) diff -urp v2.6.25/linux/include/linux/sysctl.h linux/include/linux/sysctl.h --- v2.6.25/linux/include/linux/sysctl.h 2008-04-17 09:58:08.000000000 +0300 +++ linux/include/linux/sysctl.h 2008-04-19 18:42:08.000000000 +0300 @@ -490,6 +490,7 @@ enum NET_IPV4_CONF_ARP_IGNORE=19, NET_IPV4_CONF_PROMOTE_SECONDARIES=20, NET_IPV4_CONF_ARP_ACCEPT=21, + NET_IPV4_CONF_LOOP=22, __NET_IPV4_CONF_MAX }; diff -urp v2.6.25/linux/kernel/sysctl_check.c linux/kernel/sysctl_check.c --- v2.6.25/linux/kernel/sysctl_check.c 2008-04-17 09:58:08.000000000 +0300 +++ linux/kernel/sysctl_check.c 2008-04-19 18:42:08.000000000 +0300 @@ -219,6 +219,7 @@ static const struct trans_ctl_table tran { NET_IPV4_CONF_ARP_IGNORE, "arp_ignore" }, { NET_IPV4_CONF_PROMOTE_SECONDARIES, "promote_secondaries" }, { NET_IPV4_CONF_ARP_ACCEPT, "arp_accept" }, + { NET_IPV4_CONF_LOOP, "loop" }, {} }; diff -urp v2.6.25/linux/net/ipv4/devinet.c linux/net/ipv4/devinet.c --- v2.6.25/linux/net/ipv4/devinet.c 2008-04-17 09:58:09.000000000 +0300 +++ linux/net/ipv4/devinet.c 2008-04-19 18:42:08.000000000 +0300 @@ -1447,6 +1447,7 @@ static struct devinet_sysctl_table { DEVINET_SYSCTL_RW_ENTRY(ARP_ANNOUNCE, "arp_announce"), DEVINET_SYSCTL_RW_ENTRY(ARP_IGNORE, "arp_ignore"), DEVINET_SYSCTL_RW_ENTRY(ARP_ACCEPT, "arp_accept"), + DEVINET_SYSCTL_RW_ENTRY(LOOP, "loop"), DEVINET_SYSCTL_FLUSHING_ENTRY(NOXFRM, "disable_xfrm"), DEVINET_SYSCTL_FLUSHING_ENTRY(NOPOLICY, "disable_policy"), diff -urp v2.6.25/linux/net/ipv4/fib_frontend.c linux/net/ipv4/fib_frontend.c --- v2.6.25/linux/net/ipv4/fib_frontend.c 2008-04-17 09:58:09.000000000 +0300 +++ linux/net/ipv4/fib_frontend.c 2008-04-19 18:43:47.000000000 +0300 @@ -241,16 +241,17 @@ int fib_validate_source(__be32 src, __be .tos = tos } }, .iif = oif }; struct fib_result res; - int no_addr, rpf; + int no_addr, rpf, loop; int ret; struct net *net; - no_addr = rpf = 0; + no_addr = rpf = loop = 0; rcu_read_lock(); in_dev = __in_dev_get_rcu(dev); if (in_dev) { no_addr = in_dev->ifa_list == NULL; rpf = IN_DEV_RPFILTER(in_dev); + loop = IN_DEV_LOOP(in_dev); } rcu_read_unlock(); @@ -260,6 +261,11 @@ int fib_validate_source(__be32 src, __be net = dev->nd_net; if (fib_lookup(net, &fl, &res)) goto last_resort; + if (loop && res.type == RTN_LOCAL) { + *spec_dst = FIB_RES_PREFSRC(res); + fib_res_put(&res); + return 0; + } if (res.type != RTN_UNICAST) goto e_inval_res; *spec_dst = FIB_RES_PREFSRC(res); diff -urp v2.6.25/linux/net/ipv4/route.c linux/net/ipv4/route.c --- v2.6.25/linux/net/ipv4/route.c 2008-04-17 09:58:09.000000000 +0300 +++ linux/net/ipv4/route.c 2008-04-19 18:45:48.000000000 +0300 @@ -2327,6 +2327,11 @@ static int ip_route_output_slow(struct n dev_put(dev_out); goto out; /* Wrong error code */ } + err = -ENETDOWN; + if (!(dev_out->flags&IFF_UP)) { + dev_put(dev_out); + goto out; + } if (ipv4_is_local_multicast(oldflp->fl4_dst) || oldflp->fl4_dst == htonl(0xFFFFFFFF)) { @@ -2394,10 +2399,41 @@ static int ip_route_output_slow(struct n free_res = 1; if (res.type == RTN_LOCAL) { - if (!fl.fl4_src) - fl.fl4_src = fl.fl4_dst; + struct in_device *in_dev; + __be32 src; + if (dev_out) dev_put(dev_out); + dev_out = FIB_RES_DEV(res); + in_dev = in_dev_get(dev_out); + src = fl.fl4_src? : FIB_RES_PREFSRC(res); + if (in_dev && IN_DEV_LOOP(in_dev) && src) { + struct net_device *dev_src; + + in_dev_put(in_dev); + in_dev = NULL; + dev_src = ip_dev_find(dev_out->nd_net, src); + if (dev_src && dev_src != dev_out && + (in_dev = in_dev_get(dev_src)) && + IN_DEV_LOOP(in_dev)) { + in_dev_put(in_dev); + dev_out = dev_src; + fl.fl4_src = src; + fl.oif = dev_out->ifindex; + res.type = RTN_UNICAST; + if (res.fi) { + fib_info_put(res.fi); + res.fi = NULL; + } + goto make_route; + } + if (dev_src) + dev_put(dev_src); + } + if (in_dev) + in_dev_put(in_dev); + if (!fl.fl4_src) + fl.fl4_src = fl.fl4_dst; dev_out = net->loopback_dev; dev_hold(dev_out); fl.oif = dev_out->ifindex;