[NET] rules: Add support to invert selectors

Introduces a new flag FIB_RULE_INVERT causing rules to apply
if the specified selector doesn't match.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 18 insertions, 7 deletions

diff --git a/include/linux/fib_rules.h b/include/linux/fib_rules.h
index adcdfbdd14d5..8270aac2aa5d 100644
--- a/include/linux/fib_rules.h
+++ b/include/linux/fib_rules.h
@@ -6,6 +6,7 @@
 
 /* rule is permanent, and cannot be deleted */
 #define FIB_RULE_PERMANENT      1
+#define FIB_RULE_INVERT         2
 
 struct fib_rule_hdr
 {
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index da91bf2e6151..4148e274a204 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -107,6 +107,22 @@ out:
 
 EXPORT_SYMBOL_GPL(fib_rules_unregister);
 
+static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
+                          struct flowi *fl, int flags)
+{
+        int ret = 0;
+
+        if (rule->ifindex && (rule->ifindex != fl->iif))
+                goto out;
+
+        if ((rule->mark ^ fl->mark) & rule->mark_mask)
+                goto out;
+
+        ret = ops->match(rule, fl, flags);
+out:
+        return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
+}
+
 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
                      int flags, struct fib_lookup_arg *arg)
 {
@@ -116,13 +132,7 @@ int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
         rcu_read_lock();
 
         list_for_each_entry_rcu(rule, ops->rules_list, list) {
-                if (rule->ifindex && (rule->ifindex != fl->iif))
-                        continue;
-
-                if ((rule->mark ^ fl->mark) & rule->mark_mask)
-                        continue;
-
-                if (!ops->match(rule, fl, flags))
+                if (!fib_rule_match(rule, ops, fl, flags))
                         continue;
 
                 err = ops->action(rule, fl, flags, arg);