fib_rules: add route suppression based on ifgroup

This change adds the ability to suppress a routing decision based upon the
interface group the selected interface belongs to. This allows it to
exclude specific devices from a routing decision.

Signed-off-by: Stefan Tomanek <stefan.tomanek@wertarbyte.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 43 insertions, 10 deletions

diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index 2f286dce9259..d13c461b4b59 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -18,6 +18,7 @@ struct fib_rule {
         u32                     pref;
         u32                     flags;
         u32                     table;
+        int                     suppress_ifgroup;
         u8                      table_prefixlen_min;
         u8                      action;
         u32                     target;
@@ -84,6 +85,7 @@ struct fib_rules_ops {
         [FRA_FWMASK]    = { .type = NLA_U32 }, \
         [FRA_TABLE]     = { .type = NLA_U32 }, \
         [FRA_TABLE_PREFIXLEN_MIN] = { .type = NLA_U8 }, \
+        [FRA_SUPPRESS_IFGROUP] = { .type = NLA_U32 }, \
         [FRA_GOTO]      = { .type = NLA_U32 }
 
 static inline void fib_rule_get(struct fib_rule *rule)
diff --git a/include/uapi/linux/fib_rules.h b/include/uapi/linux/fib_rules.h
index 59cd31b3455e..63e31166e85b 100644
--- a/include/uapi/linux/fib_rules.h
+++ b/include/uapi/linux/fib_rules.h
@@ -44,7 +44,7 @@ enum {
         FRA_FWMARK,     /* mark */
         FRA_FLOW,       /* flow/class id */
         FRA_UNUSED6,
-        FRA_UNUSED7,
+        FRA_SUPPRESS_IFGROUP,
         FRA_TABLE_PREFIXLEN_MIN,
         FRA_TABLE,      /* Extended table id */
         FRA_FWMASK,     /* mask for netfilter mark */
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 2ef5040c99c8..5040a61bf28a 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -343,6 +343,9 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh)
         if (tb[FRA_TABLE_PREFIXLEN_MIN])
                 rule->table_prefixlen_min = nla_get_u8(tb[FRA_TABLE_PREFIXLEN_MIN]);
 
+        if (tb[FRA_SUPPRESS_IFGROUP])
+                rule->suppress_ifgroup = nla_get_u32(tb[FRA_SUPPRESS_IFGROUP]);
+
         if (!tb[FRA_PRIORITY] && ops->default_pref)
                 rule->pref = ops->default_pref(ops);
 
@@ -529,6 +532,7 @@ static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
                          + nla_total_size(4) /* FRA_PRIORITY */
                          + nla_total_size(4) /* FRA_TABLE */
                          + nla_total_size(1) /* FRA_TABLE_PREFIXLEN_MIN */
+                         + nla_total_size(4) /* FRA_SUPPRESS_IFGROUP */
                          + nla_total_size(4) /* FRA_FWMARK */
                          + nla_total_size(4); /* FRA_FWMASK */
 
@@ -588,6 +592,12 @@ static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
             (rule->target &&
              nla_put_u32(skb, FRA_GOTO, rule->target)))
                 goto nla_put_failure;
+
+        if (rule->suppress_ifgroup != -1) {
+                if (nla_put_u32(skb, FRA_SUPPRESS_IFGROUP, rule->suppress_ifgroup))
+                        goto nla_put_failure;
+        }
+
         if (ops->fill(rule, skb, frh) < 0)
                 goto nla_put_failure;
 
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 9f2906679d1f..b78fd28970c9 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -103,16 +103,27 @@ errout:
 
 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 {
+        struct fib_result *result = (struct fib_result *) arg->result;
+        struct net_device *dev = result->fi->fib_dev;
+
         /* do not accept result if the route does
          * not meet the required prefix length
          */
-        struct fib_result *result = (struct fib_result *) arg->result;
-        if (result->prefixlen < rule->table_prefixlen_min) {
-                if (!(arg->flags & FIB_LOOKUP_NOREF))
-                        fib_info_put(result->fi);
-                return true;
-        }
+        if (result->prefixlen < rule->table_prefixlen_min)
+                goto suppress_route;
+
+        /* do not accept result if the route uses a device
+         * belonging to a forbidden interface group
+         */
+        if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
+                goto suppress_route;
+
         return false;
+
+suppress_route:
+        if (!(arg->flags & FIB_LOOKUP_NOREF))
+                fib_info_put(result->fi);
+        return true;
 }
 
 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index 554a4fbabfb3..36283267e2f8 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -122,14 +122,24 @@ out:
 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 {
         struct rt6_info *rt = (struct rt6_info *) arg->result;
+        struct net_device *dev = rt->rt6i_idev->dev;
         /* do not accept result if the route does
          * not meet the required prefix length
          */
-        if (rt->rt6i_dst.plen < rule->table_prefixlen_min) {
+        if (rt->rt6i_dst.plen < rule->table_prefixlen_min)
+                goto suppress_route;
+
+        /* do not accept result if the route uses a device
+         * belonging to a forbidden interface group
+         */
+        if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
+                goto suppress_route;
+
+        return false;
+
+suppress_route:
                 ip6_rt_put(rt);
                 return true;
-        }
-        return false;
 }
 
 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)