net: ipmr: add support for dumping routing tables over netlink

The ipmr /proc interface (ip_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/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 41e8fc0ce8b3..eddfd12f55b8 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -128,8 +128,8 @@ static int ip_mr_forward(struct net *net, struct mr_table *mrt,
                          int local);
 static int ipmr_cache_report(struct mr_table *mrt,
                              struct sk_buff *pkt, vifi_t vifi, int assert);
-static int ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
-                            struct mfc_cache *c, struct rtmsg *rtm);
+static int __ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
+                              struct mfc_cache *c, struct rtmsg *rtm);
 static void ipmr_expire_process(unsigned long arg);
 
 #ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
@@ -831,7 +831,7 @@ static void ipmr_cache_resolve(struct net *net, struct mr_table *mrt,
                 if (ip_hdr(skb)->version == 0) {
                         struct nlmsghdr *nlh = (struct nlmsghdr *)skb_pull(skb, sizeof(struct iphdr));
 
-                        if (ipmr_fill_mroute(mrt, skb, c, NLMSG_DATA(nlh)) > 0) {
+                        if (__ipmr_fill_mroute(mrt, skb, c, NLMSG_DATA(nlh)) > 0) {
                                 nlh->nlmsg_len = (skb_tail_pointer(skb) -
                                                   (u8 *)nlh);
                         } else {
@@ -1904,9 +1904,8 @@ drop:
 }
 #endif
 
-static int
-ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb, struct mfc_cache *c,
-                 struct rtmsg *rtm)
+static int __ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
+                              struct mfc_cache *c, struct rtmsg *rtm)
 {
         int ct;
         struct rtnexthop *nhp;
@@ -1994,11 +1993,93 @@ int ipmr_get_route(struct net *net,
 
         if (!nowait && (rtm->rtm_flags&RTM_F_NOTIFY))
                 cache->mfc_flags |= MFC_NOTIFY;
-        err = ipmr_fill_mroute(mrt, skb, cache, rtm);
+        err = __ipmr_fill_mroute(mrt, skb, cache, rtm);
         read_unlock(&mrt_lock);
         return err;
 }
 
+static int ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
+                            u32 pid, u32 seq, struct mfc_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  = 32;
+        rtm->rtm_src_len  = 32;
+        rtm->rtm_tos      = 0;
+        rtm->rtm_table    = mrt->id;
+        NLA_PUT_U32(skb, RTA_TABLE, mrt->id);
+        rtm->rtm_type     = RTN_MULTICAST;
+        rtm->rtm_scope    = RT_SCOPE_UNIVERSE;
+        rtm->rtm_protocol = RTPROT_UNSPEC;
+        rtm->rtm_flags    = 0;
+
+        NLA_PUT_BE32(skb, RTA_SRC, c->mfc_origin);
+        NLA_PUT_BE32(skb, RTA_DST, c->mfc_mcastgrp);
+
+        if (__ipmr_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 ipmr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
+{
+        struct net *net = sock_net(skb->sk);
+        struct mr_table *mrt;
+        struct mfc_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);
+        ipmr_for_each_table(mrt, net) {
+                if (t < s_t)
+                        goto next_table;
+                if (t > s_t)
+                        s_h = 0;
+                for (h = s_h; h < MFC_LINES; h++) {
+                        list_for_each_entry(mfc, &mrt->mfc_cache_array[h], list) {
+                                if (e < s_e)
+                                        goto next_entry;
+                                if (ipmr_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;
+}
+
 #ifdef CONFIG_PROC_FS
 /*
  *      The /proc interfaces to multicast routing /proc/ip_mr_cache /proc/ip_mr_vif
@@ -2355,6 +2436,7 @@ int __init ip_mr_init(void)
                 goto add_proto_fail;
         }
 #endif
+        rtnl_register(RTNL_FAMILY_IPMR, RTM_GETROUTE, NULL, ipmr_rtm_dumproute);
         return 0;
 
 #ifdef CONFIG_IP_PIMSM_V2