[IPV4]: Add fib rule netlink notifications

To really make sense of route notifications in the presence of
multiple tables, userspace also needs to be notified about routing
rule updates.  Notifications are sent to the so far unused
RTNLGRP_NOP1 (now RTNLGRP_RULE) group.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 27 insertions, 4 deletions

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index d572d5376319..df0cdd41085c 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -839,6 +839,7 @@ enum
 #define RTMGRP_IPV4_IFADDR      0x10
 #define RTMGRP_IPV4_MROUTE      0x20
 #define RTMGRP_IPV4_ROUTE       0x40
+#define RTMGRP_IPV4_RULE        0x80
 
 #define RTMGRP_IPV6_IFADDR      0x100
 #define RTMGRP_IPV6_MROUTE      0x200
@@ -869,7 +870,8 @@ enum rtnetlink_groups {
 #define RTNLGRP_IPV4_MROUTE     RTNLGRP_IPV4_MROUTE
         RTNLGRP_IPV4_ROUTE,
 #define RTNLGRP_IPV4_ROUTE      RTNLGRP_IPV4_ROUTE
-        RTNLGRP_NOP1,
+        RTNLGRP_IPV4_RULE,
+#define RTNLGRP_IPV4_RULE       RTNLGRP_IPV4_RULE
         RTNLGRP_IPV6_IFADDR,
 #define RTNLGRP_IPV6_IFADDR     RTNLGRP_IPV6_IFADDR
         RTNLGRP_IPV6_MROUTE,
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 768e8f5d7daa..ec566f3e66c7 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -104,6 +104,8 @@ static struct hlist_head fib_rules;
 
 /* writer func called from netlink -- rtnl_sem hold*/
 
+static void rtmsg_rule(int, struct fib_rule *);
+
 int inet_rtm_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 {
         struct rtattr **rta = arg;
@@ -131,6 +133,7 @@ int inet_rtm_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 
                         hlist_del_rcu(&r->hlist);
                         r->r_dead = 1;
+                        rtmsg_rule(RTM_DELRULE, r);
                         fib_rule_put(r);
                         err = 0;
                         break;
@@ -253,6 +256,7 @@ int inet_rtm_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
         else
                 hlist_add_before_rcu(&new_r->hlist, &r->hlist);
 
+        rtmsg_rule(RTM_NEWRULE, new_r);
         return 0;
 }
 
@@ -382,14 +386,14 @@ static struct notifier_block fib_rules_notifier = {
 
 static __inline__ int inet_fill_rule(struct sk_buff *skb,
                                      struct fib_rule *r,
-                                     struct netlink_callback *cb,
+                                     u32 pid, u32 seq, int event,
                                      unsigned int flags)
 {
         struct rtmsg *rtm;
         struct nlmsghdr  *nlh;
         unsigned char    *b = skb->tail;
 
-        nlh = NLMSG_NEW_ANSWER(skb, cb, RTM_NEWRULE, sizeof(*rtm), flags);
+        nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*rtm), flags);
         rtm = NLMSG_DATA(nlh);
         rtm->rtm_family = AF_INET;
         rtm->rtm_dst_len = r->r_dst_len;
@@ -430,6 +434,21 @@ rtattr_failure:
 
 /* callers should hold rtnl semaphore */
 
+static void rtmsg_rule(int event, struct fib_rule *r)
+{
+        int size = NLMSG_SPACE(sizeof(struct rtmsg) + 128);
+        struct sk_buff *skb = alloc_skb(size, GFP_KERNEL);
+
+        if (!skb)
+                netlink_set_err(rtnl, 0, RTNLGRP_IPV4_RULE, ENOBUFS);
+        else if (inet_fill_rule(skb, r, 0, 0, event, 0) < 0) {
+                kfree_skb(skb);
+                netlink_set_err(rtnl, 0, RTNLGRP_IPV4_RULE, EINVAL);
+        } else {
+                netlink_broadcast(rtnl, skb, 0, RTNLGRP_IPV4_RULE, GFP_KERNEL);
+        }
+}
+
 int inet_dump_rules(struct sk_buff *skb, struct netlink_callback *cb)
 {
         int idx = 0;
@@ -442,7 +461,9 @@ int inet_dump_rules(struct sk_buff *skb, struct netlink_callback *cb)
 
                 if (idx < s_idx)
                         continue;
-                if (inet_fill_rule(skb, r, cb, NLM_F_MULTI) < 0)
+                if (inet_fill_rule(skb, r, NETLINK_CB(cb->skb).pid,
+                                   cb->nlh->nlmsg_seq,
+                                   RTM_NEWRULE, NLM_F_MULTI) < 0)
                         break;
                 idx++;
         }