ipv4 05/05: add sysctl to accept packets with local source addresses

commit 8ec1e0ebe26087bfc5c0394ada5feb5758014fc8
Author: Patrick McHardy <kaber@trash.net>
Date:   Thu Dec 3 12:16:35 2009 +0100

    ipv4: add sysctl to accept packets with local source addresses

    Change fib_validate_source() to accept packets with a local source address when
    the "accept_local" sysctl is set for the incoming inet device. Combined with the
    previous patches, this allows to communicate between multiple local interfaces
    over the wire.

    Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 989f553..006b39d 100644 (file)
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -731,6 +731,12 @@ accept_source_route - BOOLEAN
        default TRUE (router)
                FALSE (host)
 
+accept_local - BOOLEAN
+       Accept packets with local source addresses. In combination with
+       suitable routing, this can be used to direct packets between two
+       local interfaces over the wire and have them accepted properly.
+       default FALSE
+
 rp_filter - INTEGER
        0 - No source validation.
        1 - Strict mode as defined in RFC3704 Strict Reverse Path

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index eecfa55..699e85c 100644 (file)
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -83,6 +83,7 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev)
 #define IN_DEV_RPFILTER(in_dev)                IN_DEV_MAXCONF((in_dev), RP_FILTER)
 #define IN_DEV_SOURCE_ROUTE(in_dev)    IN_DEV_ANDCONF((in_dev), \
                                                       ACCEPT_SOURCE_ROUTE)
+#define IN_DEV_ACCEPT_LOCAL(in_dev)    IN_DEV_ORCONF((in_dev), ACCEPT_LOCAL)
 #define IN_DEV_BOOTP_RELAY(in_dev)     IN_DEV_ANDCONF((in_dev), BOOTP_RELAY)
 
 #define IN_DEV_LOG_MARTIANS(in_dev)    IN_DEV_ORCONF((in_dev), LOG_MARTIANS)

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 1e4743e..9f047d7 100644 (file)
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -490,6 +490,7 @@ enum
        NET_IPV4_CONF_PROMOTE_SECONDARIES=20,
        NET_IPV4_CONF_ARP_ACCEPT=21,
        NET_IPV4_CONF_ARP_NOTIFY=22,
+       NET_IPV4_CONF_ACCEPT_LOCAL=23,
        __NET_IPV4_CONF_MAX
 };
 

diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
index b6e7aae..f1d676e 100644 (file)
--- a/kernel/sysctl_check.c
+++ b/kernel/sysctl_check.c
@@ -220,6 +220,7 @@ static const struct trans_ctl_table trans_net_ipv4_conf_vars_table[] = {
        { NET_IPV4_CONF_PROMOTE_SECONDARIES,    "promote_secondaries" },
        { NET_IPV4_CONF_ARP_ACCEPT,             "arp_accept" },
        { NET_IPV4_CONF_ARP_NOTIFY,             "arp_notify" },
+       { NET_IPV4_CONF_ACCEPT_LOCAL,           "accept_local" },
        {}
 };
 

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index c100709..e312661 100644 (file)
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1468,6 +1468,7 @@ static struct devinet_sysctl_table {
                DEVINET_SYSCTL_RW_ENTRY(SEND_REDIRECTS, "send_redirects"),
                DEVINET_SYSCTL_RW_ENTRY(ACCEPT_SOURCE_ROUTE,
                                        "accept_source_route"),
+               DEVINET_SYSCTL_RW_ENTRY(ACCEPT_LOCAL, "accept_local"),
                DEVINET_SYSCTL_RW_ENTRY(PROXY_ARP, "proxy_arp"),
                DEVINET_SYSCTL_RW_ENTRY(MEDIUM_ID, "medium_id"),
                DEVINET_SYSCTL_RW_ENTRY(BOOTP_RELAY, "bootp_relay"),

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 3b373a8..3323168 100644 (file)
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -241,16 +241,17 @@ int fib_validate_source(__be32 src, __be32 dst, u8 tos, int oif,
                            .iif = oif };
 
        struct fib_result res;
-       int no_addr, rpf;
+       int no_addr, rpf, accept_local;
        int ret;
        struct net *net;
 
-       no_addr = rpf = 0;
+       no_addr = rpf = accept_local = 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);
+               accept_local = IN_DEV_ACCEPT_LOCAL(in_dev);
        }
        rcu_read_unlock();
 
@@ -260,8 +261,10 @@ int fib_validate_source(__be32 src, __be32 dst, u8 tos, int oif,
        net = dev_net(dev);
        if (fib_lookup(net, &fl, &res))
                goto last_resort;
-       if (res.type != RTN_UNICAST)
-               goto e_inval_res;
+       if (res.type != RTN_UNICAST) {
+               if (res.type != RTN_LOCAL || !accept_local)
+                       goto e_inval_res;
+       }
        *spec_dst = FIB_RES_PREFSRC(res);
        fib_combine_itag(itag, &res);
 #ifdef CONFIG_IP_ROUTE_MULTIPATH