[IPV6] FIB6RULE: Find source address during looking up route.

When looking up route for destination with rules with
source address restrictions, we may need to find a source
address for the traffic if not given.

Based on patch from Noriaki TAKAMIYA <takamiya@po.ntts.co.jp>.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 31 insertions, 3 deletions

diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index dd9720e700e..fc3882c9060 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -17,6 +17,7 @@
 
 #include <net/fib_rules.h>
 #include <net/ipv6.h>
+#include <net/addrconf.h>
 #include <net/ip6_route.h>
 #include <net/netlink.h>
 
@@ -95,8 +96,27 @@ static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
         if (table)
                 rt = lookup(table, flp, flags);
 
-        if (rt != &ip6_null_entry)
+        if (rt != &ip6_null_entry) {
+                struct fib6_rule *r = (struct fib6_rule *)rule;
+
+                /*
+                 * If we need to find a source address for this traffic,
+                 * we check the result if it meets requirement of the rule.
+                 */
+                if ((rule->flags & FIB_RULE_FIND_SADDR) &&
+                    r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
+                        struct in6_addr saddr;
+                        if (ipv6_get_saddr(&rt->u.dst, &flp->fl6_dst,
+                                           &saddr))
+                                goto again;
+                        if (!ipv6_prefix_equal(&saddr, &r->src.addr,
+                                               r->src.plen))
+                                goto again;
+                        ipv6_addr_copy(&flp->fl6_src, &saddr);
+                }
                 goto out;
+        }
+again:
         dst_release(&rt->u.dst);
         rt = NULL;
         goto out;
@@ -117,9 +137,17 @@ static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
             !ipv6_prefix_equal(&fl->fl6_dst, &r->dst.addr, r->dst.plen))
                 return 0;
 
+        /*
+         * If FIB_RULE_FIND_SADDR is set and we do not have a
+         * source address for the traffic, we defer check for
+         * source address.
+         */
         if (r->src.plen) {
-                if (!(flags & RT6_LOOKUP_F_HAS_SADDR) ||
-                    !ipv6_prefix_equal(&fl->fl6_src, &r->src.addr, r->src.plen))
+                if (flags & RT6_LOOKUP_F_HAS_SADDR) {
+                        if (!ipv6_prefix_equal(&fl->fl6_src, &r->src.addr,
+                                               r->src.plen))
+                                return 0;
+                } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
                         return 0;
         }