net: devinet: Add support for RTM_DELNETCONF

Send RTM_DELNETCONF notifications when a device is deleted. The message only
needs the device index, so modify inet_netconf_fill_devconf to skip devconf
references if it is NULL.

Allows a userspace cache to remove entries as devices are deleted.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 11 deletions

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index fd3218cd1870..6d3602ec640c 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1802,6 +1802,9 @@ static int inet_netconf_fill_devconf(struct sk_buff *skb, int ifindex,
         if (nla_put_s32(skb, NETCONFA_IFINDEX, ifindex) < 0)
                 goto nla_put_failure;
 
+        if (!devconf)
+                goto out;
+
         if ((all || type == NETCONFA_FORWARDING) &&
             nla_put_s32(skb, NETCONFA_FORWARDING,
                         IPV4_DEVCONF(*devconf, FORWARDING)) < 0)
@@ -1823,6 +1826,7 @@ static int inet_netconf_fill_devconf(struct sk_buff *skb, int ifindex,
                         IPV4_DEVCONF(*devconf, IGNORE_ROUTES_WITH_LINKDOWN)) < 0)
                 goto nla_put_failure;
 
+out:
         nlmsg_end(skb, nlh);
         return 0;
 
@@ -2276,16 +2280,18 @@ out:
         return -ENOBUFS;
 }
 
-static void __devinet_sysctl_unregister(struct ipv4_devconf *cnf)
+static void __devinet_sysctl_unregister(struct net *net,
+                                        struct ipv4_devconf *cnf, int ifindex)
 {
         struct devinet_sysctl_table *t = cnf->sysctl;
 
-        if (!t)
-                return;
+        if (t) {
+                cnf->sysctl = NULL;
+                unregister_net_sysctl_table(t->sysctl_header);
+                kfree(t);
+        }
 
-        cnf->sysctl = NULL;
-        unregister_net_sysctl_table(t->sysctl_header);
-        kfree(t);
+        inet_netconf_notify_devconf(net, RTM_DELNETCONF, 0, ifindex, NULL);
 }
 
 static int devinet_sysctl_register(struct in_device *idev)
@@ -2307,7 +2313,9 @@ static int devinet_sysctl_register(struct in_device *idev)
 
 static void devinet_sysctl_unregister(struct in_device *idev)
 {
-        __devinet_sysctl_unregister(&idev->cnf);
+        struct net *net = dev_net(idev->dev);
+
+        __devinet_sysctl_unregister(net, &idev->cnf, idev->dev->ifindex);
         neigh_sysctl_unregister(idev->arp_parms);
 }
 
@@ -2382,9 +2390,9 @@ static __net_init int devinet_init_net(struct net *net)
 
 #ifdef CONFIG_SYSCTL
 err_reg_ctl:
-        __devinet_sysctl_unregister(dflt);
+        __devinet_sysctl_unregister(net, dflt, NETCONFA_IFINDEX_DEFAULT);
 err_reg_dflt:
-        __devinet_sysctl_unregister(all);
+        __devinet_sysctl_unregister(net, all, NETCONFA_IFINDEX_ALL);
 err_reg_all:
         if (tbl != ctl_forward_entry)
                 kfree(tbl);
@@ -2406,8 +2414,10 @@ static __net_exit void devinet_exit_net(struct net *net)
 
         tbl = net->ipv4.forw_hdr->ctl_table_arg;
         unregister_net_sysctl_table(net->ipv4.forw_hdr);
-        __devinet_sysctl_unregister(net->ipv4.devconf_dflt);
-        __devinet_sysctl_unregister(net->ipv4.devconf_all);
+        __devinet_sysctl_unregister(net, net->ipv4.devconf_dflt,
+                                    NETCONFA_IFINDEX_DEFAULT);
+        __devinet_sysctl_unregister(net, net->ipv4.devconf_all,
+                                    NETCONFA_IFINDEX_ALL);
         kfree(tbl);
 #endif
         kfree(net->ipv4.devconf_dflt);