ipv6: ip6mr: add support for dumping routing tables over netlink

The ip6mr /proc interface (ip6_mr_cache) can't be extended to dump routes
from any tables but the main table in a backwards compatible fashion since
the output format ends in a variable amount of output interfaces.

Introduce a new netlink interface to dump multicast routes from all tables,
similar to the netlink interface for regular routes.

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 89 insertions, 7 deletions

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index c2920a1a6db3..163850e22b11 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -112,8 +112,10 @@ static int ip6_mr_forward(struct net *net, struct mr6_table *mrt,
                           struct sk_buff *skb, struct mfc6_cache *cache);
 static int ip6mr_cache_report(struct mr6_table *mrt, struct sk_buff *pkt,
                               mifi_t mifi, int assert);
-static int ip6mr_fill_mroute(struct mr6_table *mrt, struct sk_buff *skb,
-                             struct mfc6_cache *c, struct rtmsg *rtm);
+static int __ip6mr_fill_mroute(struct mr6_table *mrt, struct sk_buff *skb,
+                               struct mfc6_cache *c, struct rtmsg *rtm);
+static int ip6mr_rtm_dumproute(struct sk_buff *skb,
+                               struct netlink_callback *cb);
 static void mroute_clean_tables(struct mr6_table *mrt);
 static void ipmr_expire_process(unsigned long arg);
 
@@ -1038,7 +1040,7 @@ static void ip6mr_cache_resolve(struct net *net, struct mr6_table *mrt,
                         int err;
                         struct nlmsghdr *nlh = (struct nlmsghdr *)skb_pull(skb, sizeof(struct ipv6hdr));
 
-                        if (ip6mr_fill_mroute(mrt, skb, c, NLMSG_DATA(nlh)) > 0) {
+                        if (__ip6mr_fill_mroute(mrt, skb, c, NLMSG_DATA(nlh)) > 0) {
                                 nlh->nlmsg_len = skb_tail_pointer(skb) - (u8 *)nlh;
                         } else {
                                 nlh->nlmsg_type = NLMSG_ERROR;
@@ -1350,6 +1352,7 @@ int __init ip6_mr_init(void)
                 goto add_proto_fail;
         }
 #endif
+        rtnl_register(RTNL_FAMILY_IP6MR, RTM_GETROUTE, NULL, ip6mr_rtm_dumproute);
         return 0;
 #ifdef CONFIG_IPV6_PIMSM_V2
 add_proto_fail:
@@ -2007,9 +2010,8 @@ int ip6_mr_input(struct sk_buff *skb)
 }
 
 
-static int
-ip6mr_fill_mroute(struct mr6_table *mrt, struct sk_buff *skb,
-                  struct mfc6_cache *c, struct rtmsg *rtm)
+static int __ip6mr_fill_mroute(struct mr6_table *mrt, struct sk_buff *skb,
+                               struct mfc6_cache *c, struct rtmsg *rtm)
 {
         int ct;
         struct rtnexthop *nhp;
@@ -2111,8 +2113,88 @@ int ip6mr_get_route(struct net *net,
         if (!nowait && (rtm->rtm_flags&RTM_F_NOTIFY))
                 cache->mfc_flags |= MFC_NOTIFY;
 
-        err = ip6mr_fill_mroute(mrt, skb, cache, rtm);
+        err = __ip6mr_fill_mroute(mrt, skb, cache, rtm);
         read_unlock(&mrt_lock);
         return err;
 }
 
+static int ip6mr_fill_mroute(struct mr6_table *mrt, struct sk_buff *skb,
+                             u32 pid, u32 seq, struct mfc6_cache *c)
+{
+        struct nlmsghdr *nlh;
+        struct rtmsg *rtm;
+
+        nlh = nlmsg_put(skb, pid, seq, RTM_NEWROUTE, sizeof(*rtm), NLM_F_MULTI);
+        if (nlh == NULL)
+                return -EMSGSIZE;
+
+        rtm = nlmsg_data(nlh);
+        rtm->rtm_family   = RTNL_FAMILY_IPMR;
+        rtm->rtm_dst_len  = 128;
+        rtm->rtm_src_len  = 128;
+        rtm->rtm_tos      = 0;
+        rtm->rtm_table    = mrt->id;
+        NLA_PUT_U32(skb, RTA_TABLE, mrt->id);
+        rtm->rtm_scope    = RT_SCOPE_UNIVERSE;
+        rtm->rtm_protocol = RTPROT_UNSPEC;
+        rtm->rtm_flags    = 0;
+
+        NLA_PUT(skb, RTA_SRC, 16, &c->mf6c_origin);
+        NLA_PUT(skb, RTA_DST, 16, &c->mf6c_mcastgrp);
+
+        if (__ip6mr_fill_mroute(mrt, skb, c, rtm) < 0)
+                goto nla_put_failure;
+
+        return nlmsg_end(skb, nlh);
+
+nla_put_failure:
+        nlmsg_cancel(skb, nlh);
+        return -EMSGSIZE;
+}
+
+static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
+{
+        struct net *net = sock_net(skb->sk);
+        struct mr6_table *mrt;
+        struct mfc6_cache *mfc;
+        unsigned int t = 0, s_t;
+        unsigned int h = 0, s_h;
+        unsigned int e = 0, s_e;
+
+        s_t = cb->args[0];
+        s_h = cb->args[1];
+        s_e = cb->args[2];
+
+        read_lock(&mrt_lock);
+        ip6mr_for_each_table(mrt, net) {
+                if (t < s_t)
+                        goto next_table;
+                if (t > s_t)
+                        s_h = 0;
+                for (h = s_h; h < MFC6_LINES; h++) {
+                        list_for_each_entry(mfc, &mrt->mfc6_cache_array[h], list) {
+                                if (e < s_e)
+                                        goto next_entry;
+                                if (ip6mr_fill_mroute(mrt, skb,
+                                                      NETLINK_CB(cb->skb).pid,
+                                                      cb->nlh->nlmsg_seq,
+                                                      mfc) < 0)
+                                        goto done;
+next_entry:
+                                e++;
+                        }
+                        e = s_e = 0;
+                }
+                s_h = 0;
+next_table:
+                t++;
+        }
+done:
+        read_unlock(&mrt_lock);
+
+        cb->args[2] = e;
+        cb->args[1] = h;
+        cb->args[0] = t;
+
+        return skb->len;
+}