ipv4: Loosen source address check on IPv4 output

ip_route_output() contains a check to make sure that no flows with
non-local source IP addresses are routed. This obviously makes using
such addresses impossible.

This patch introduces a flowi flag which makes omitting this check
possible. The new flag provides a way of handling transparent and
non-transparent connections differently.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: KOVACS Krisztian <hidden@sch.bme.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/flow.h b/include/net/flow.h
index 228b247..b45a5e4 100644 (file)
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -47,6 +47,8 @@ struct flowi {
 #define fl4_scope      nl_u.ip4_u.scope
 
        __u8    proto;
+       __u8    flags;
+#define FLOWI_FLAG_ANYSRC 0x01
        union {
                struct {
                        __be16  sport;

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index f62187b..a6d7c58 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2361,11 +2361,6 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
                    ipv4_is_zeronet(oldflp->fl4_src))
                        goto out;
 
-               /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
-               dev_out = ip_dev_find(net, oldflp->fl4_src);
-               if (dev_out == NULL)
-                       goto out;
-
                /* I removed check for oif == dev_out->oif here.
                   It was wrong for two reasons:
                   1. ip_dev_find(net, saddr) can return wrong iface, if saddr
@@ -2377,6 +2372,11 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
                if (oldflp->oif == 0
                    && (ipv4_is_multicast(oldflp->fl4_dst) ||
                        oldflp->fl4_dst == htonl(0xFFFFFFFF))) {
+                       /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
+                       dev_out = ip_dev_find(net, oldflp->fl4_src);
+                       if (dev_out == NULL)
+                               goto out;
+
                        /* Special hack: user can direct multicasts
                           and limited broadcast via necessary interface
                           without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
@@ -2395,9 +2395,15 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
                        fl.oif = dev_out->ifindex;
                        goto make_route;
                }
-               if (dev_out)
+
+               if (!(oldflp->flags & FLOWI_FLAG_ANYSRC)) {
+                       /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
+                       dev_out = ip_dev_find(net, oldflp->fl4_src);
+                       if (dev_out == NULL)
+                               goto out;
                        dev_put(dev_out);
-               dev_out = NULL;
+                       dev_out = NULL;
+               }
        }