[patch net-next v2 06/12] net: mroute: Check if rule is a default rule

[Jiri Pirko]

From: Yotam Gigi <yot...@mellanox.com>

When the ipmr starts, it adds one default FIB rule that matches all packets
and sends them to the DEFAULT (multicast) FIB table. A more complex rule
can be added by user to specify that for a specific interface, a packet
should be look up at either an arbitrary table or according to the l3mdev
of the interface.

For drivers willing to offload the ipmr logic into a hardware but don't
want to offload all the FIB rules functionality, provide a function that
can indicate whether the FIB rule is the default multicast rule, thus only
one routing table is needed.

This way, a driver can register to the FIB notification chain, get
notifications about FIB rules added and trigger some kind of an internal
abort mechanism when a non default rule is added by the user.

Signed-off-by: Yotam Gigi <yot...@mellanox.com>
Reviewed-by: Ido Schimmel <ido...@mellanox.com>
Signed-off-by: Jiri Pirko <j...@mellanox.com>
---
 include/linux/mroute.h |  7 +++++++
 net/ipv4/ipmr.c        | 10 ++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/linux/mroute.h b/include/linux/mroute.h
index 5566580..b072a84 100644
--- a/include/linux/mroute.h
+++ b/include/linux/mroute.h
@@ -5,6 +5,7 @@
 #include <linux/pim.h>
 #include <linux/rhashtable.h>
 #include <net/sock.h>
+#include <net/fib_rules.h>
 #include <net/fib_notifier.h>
 #include <uapi/linux/mroute.h>
 
@@ -19,6 +20,7 @@ int ip_mroute_getsockopt(struct sock *, int, char __user *, 
int __user *);
 int ipmr_ioctl(struct sock *sk, int cmd, void __user *arg);
 int ipmr_compat_ioctl(struct sock *sk, unsigned int cmd, void __user *arg);
 int ip_mr_init(void);
+bool ipmr_rule_default(const struct fib_rule *rule);
 #else
 static inline int ip_mroute_setsockopt(struct sock *sock, int optname,
                                       char __user *optval, unsigned int optlen)
@@ -46,6 +48,11 @@ static inline int ip_mroute_opt(int opt)
 {
        return 0;
 }
+
+static inline bool ipmr_rule_default(const struct fib_rule *rule)
+{
+       return true;
+}
 #endif
 
 struct vif_device {
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 2a795d2..a714f55 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -320,6 +320,16 @@ static unsigned int ipmr_rules_seq_read(struct net *net)
 }
 #endif
 
+bool ipmr_rule_default(const struct fib_rule *rule)
+{
+#if IS_ENABLED(CONFIG_FIB_RULES)
+       return fib_rule_matchall(rule) && rule->table == RT_TABLE_DEFAULT;
+#else
+       return true;
+#endif
+}
+EXPORT_SYMBOL(ipmr_rule_default);
+
 static inline int ipmr_hash_cmp(struct rhashtable_compare_arg *arg,
                                const void *ptr)
 {
-- 
2.9.5