Dump the list of DAT cache entries via the netlink socket.

Signed-off-by: Linus Lüssing <linus.luess...@c0d3.blue>
---
 compat-include/net/netlink.h           |  51 +++++++++++
 include/uapi/linux/batman_adv.h        |  20 +++++
 net/batman-adv/distributed-arp-table.c | 152 +++++++++++++++++++++++++++++++++
 net/batman-adv/distributed-arp-table.h |   8 ++
 net/batman-adv/netlink.c               |  76 ++++++++++-------
 5 files changed, 274 insertions(+), 33 deletions(-)
 create mode 100644 compat-include/net/netlink.h

diff --git a/compat-include/net/netlink.h b/compat-include/net/netlink.h
new file mode 100644
index 00000000..d43576e2
--- /dev/null
+++ b/compat-include/net/netlink.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2007-2018  B.A.T.M.A.N. contributors:
+ *
+ * Marek Lindner, Simon Wunderlich
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * This file contains macros for maintaining compatibility with older versions
+ * of the Linux kernel.
+ */
+
+#ifndef _NET_BATMAN_ADV_COMPAT_NET_NETLINK_H_
+#define _NET_BATMAN_ADV_COMPAT_NET_NETLINK_H_
+
+#include <linux/version.h>
+#include_next <net/netlink.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 5, 0)
+
+static inline int nla_put_be32(struct sk_buff *skb, int attrtype, __be32 value)
+{
+       __be32 tmp = value;
+
+       return nla_put(skb, attrtype, sizeof(__be32), &tmp);
+}
+
+#endif /* < KERNEL_VERSION(3, 5, 0) */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 0)
+
+static inline int nla_put_in_addr(struct sk_buff *skb, int attrtype,
+                                 __be32 addr)
+{
+       __be32 tmp = addr;
+
+       return nla_put_be32(skb, attrtype, tmp);
+}
+
+#endif /* < KERNEL_VERSION(4, 1, 0) */
+
+#endif /* _NET_BATMAN_ADV_COMPAT_NET_NETLINK_H_ */
diff --git a/include/uapi/linux/batman_adv.h b/include/uapi/linux/batman_adv.h
index 56ae2893..95ab5dbd 100644
--- a/include/uapi/linux/batman_adv.h
+++ b/include/uapi/linux/batman_adv.h
@@ -272,6 +272,21 @@ enum batadv_nl_attrs {
         */
        BATADV_ATTR_BLA_CRC,
 
+       /**
+        * @BATADV_ATTR_DAT_CACHE_IP4ADDRESS: Client IPv4 address
+        */
+       BATADV_ATTR_DAT_CACHE_IP4ADDRESS,
+
+       /**
+        * @BATADV_ATTR_DAT_CACHE_HWADDRESS: Client MAC address
+        */
+       BATADV_ATTR_DAT_CACHE_HWADDRESS,
+
+       /**
+        * @BATADV_ATTR_DAT_CACHE_VID: VLAN ID
+        */
+       BATADV_ATTR_DAT_CACHE_VID,
+
        /* add attributes above here, update the policy in netlink.c */
 
        /**
@@ -361,6 +376,11 @@ enum batadv_nl_commands {
         */
        BATADV_CMD_GET_BLA_BACKBONE,
 
+       /**
+        * @BATADV_CMD_GET_DAT_CACHE: Query list of DAT cache entries
+        */
+       BATADV_CMD_GET_DAT_CACHE,
+
        /* add new commands above here */
 
        /**
diff --git a/net/batman-adv/distributed-arp-table.c 
b/net/batman-adv/distributed-arp-table.c
index 19b15de4..023b8750 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -33,6 +33,7 @@
 #include <linux/kernel.h>
 #include <linux/kref.h>
 #include <linux/list.h>
+#include <linux/netlink.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
 #include <linux/seq_file.h>
@@ -43,13 +44,19 @@
 #include <linux/string.h>
 #include <linux/workqueue.h>
 #include <net/arp.h>
+#include <net/genetlink.h>
+#include <net/netlink.h>
+#include <net/sock.h>
+#include <uapi/linux/batman_adv.h>
 
 #include "bridge_loop_avoidance.h"
 #include "hard-interface.h"
 #include "hash.h"
 #include "log.h"
+#include "netlink.h"
 #include "originator.h"
 #include "send.h"
+#include "soft-interface.h"
 #include "translation-table.h"
 #include "tvlv.h"
 
@@ -852,6 +859,151 @@ int batadv_dat_cache_seq_print_text(struct seq_file *seq, 
void *offset)
 #endif
 
 /**
+ * batadv_dat_cache_dump_entry() - dump one entry of the DAT cache table to a
+ *  netlink socket
+ * @msg: buffer for the message
+ * @portid: netlink port
+ * @seq: Sequence number of netlink message
+ * @dat_entry: entry to dump
+ *
+ * Return: 0 or error code.
+ */
+static int
+batadv_dat_cache_dump_entry(struct sk_buff *msg, u32 portid, u32 seq,
+                           struct batadv_dat_entry *dat_entry)
+{
+       int msecs;
+       void *hdr;
+
+       hdr = genlmsg_put(msg, portid, seq, &batadv_netlink_family,
+                         NLM_F_MULTI, BATADV_CMD_GET_DAT_CACHE);
+       if (!hdr)
+               return -ENOBUFS;
+
+       msecs = jiffies_to_msecs(jiffies - dat_entry->last_update);
+
+       if (nla_put_in_addr(msg, BATADV_ATTR_DAT_CACHE_IP4ADDRESS,
+                           dat_entry->ip) ||
+           nla_put(msg, BATADV_ATTR_DAT_CACHE_HWADDRESS, ETH_ALEN,
+                   dat_entry->mac_addr) ||
+           nla_put_u16(msg, BATADV_ATTR_DAT_CACHE_VID, dat_entry->vid) ||
+           nla_put_u32(msg, BATADV_ATTR_LAST_SEEN_MSECS, msecs)) {
+               genlmsg_cancel(msg, hdr);
+               return -EMSGSIZE;
+       }
+
+       genlmsg_end(msg, hdr);
+       return 0;
+}
+
+/**
+ * batadv_dat_cache_dump_bucket() - dump one bucket of the DAT cache table to
+ *  a netlink socket
+ * @msg: buffer for the message
+ * @portid: netlink port
+ * @seq: Sequence number of netlink message
+ * @head: bucket to dump
+ * @idx_skip: How many entries to skip
+ *
+ * Return: 0 or error code.
+ */
+static int
+batadv_dat_cache_dump_bucket(struct sk_buff *msg, u32 portid, u32 seq,
+                            struct hlist_head *head, int *idx_skip)
+{
+       struct batadv_dat_entry *dat_entry;
+       int idx = 0;
+
+       rcu_read_lock();
+       hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
+               if (idx < *idx_skip)
+                       goto skip;
+
+               if (batadv_dat_cache_dump_entry(msg, portid, seq,
+                                               dat_entry)) {
+                       rcu_read_unlock();
+                       *idx_skip = idx;
+
+                       return -EMSGSIZE;
+               }
+
+skip:
+               idx++;
+       }
+       rcu_read_unlock();
+
+       return 0;
+}
+
+/**
+ * batadv_dat_cache_dump() - dump DAT cache table to a netlink socket
+ * @msg: buffer for the message
+ * @cb: callback structure containing arguments
+ *
+ * Return: message length.
+ */
+int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
+{
+       struct batadv_hard_iface *primary_if = NULL;
+       int portid = NETLINK_CB(cb->skb).portid;
+       struct net *net = sock_net(cb->skb->sk);
+       struct net_device *soft_iface;
+       struct batadv_hashtable *hash;
+       struct batadv_priv *bat_priv;
+       int bucket = cb->args[0];
+       struct hlist_head *head;
+       int idx = cb->args[1];
+       int ifindex;
+       int ret = 0;
+
+       ifindex = batadv_netlink_get_ifindex(cb->nlh,
+                                            BATADV_ATTR_MESH_IFINDEX);
+       if (!ifindex)
+               return -EINVAL;
+
+       soft_iface = dev_get_by_index(net, ifindex);
+       if (!soft_iface || !batadv_softif_is_valid(soft_iface)) {
+               ret = -ENODEV;
+               goto out;
+       }
+
+       bat_priv = netdev_priv(soft_iface);
+       hash = bat_priv->dat.hash;
+
+       primary_if = batadv_primary_if_get_selected(bat_priv);
+       if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
+               ret = -ENOENT;
+               goto out;
+       }
+
+       while (bucket < hash->size) {
+               head = &hash->table[bucket];
+
+               if (batadv_dat_cache_dump_bucket(msg, portid,
+                                                cb->nlh->nlmsg_seq, head,
+                                                &idx))
+                       break;
+
+               bucket++;
+               idx = 0;
+       }
+
+       cb->args[0] = bucket;
+       cb->args[1] = idx;
+
+       ret = msg->len;
+
+out:
+       if (primary_if)
+               batadv_hardif_put(primary_if);
+
+       if (soft_iface)
+               dev_put(soft_iface);
+
+       return ret;
+}
+
+/**
  * batadv_arp_get_type() - parse an ARP packet and gets the type
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: packet to analyse
diff --git a/net/batman-adv/distributed-arp-table.h 
b/net/batman-adv/distributed-arp-table.h
index e24aa960..a0459602 100644
--- a/net/batman-adv/distributed-arp-table.h
+++ b/net/batman-adv/distributed-arp-table.h
@@ -28,6 +28,7 @@
 
 #include "originator.h"
 
+struct netlink_callback;
 struct seq_file;
 struct sk_buff;
 
@@ -81,6 +82,7 @@ batadv_dat_init_own_addr(struct batadv_priv *bat_priv,
 int batadv_dat_init(struct batadv_priv *bat_priv);
 void batadv_dat_free(struct batadv_priv *bat_priv);
 int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset);
+int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb);
 
 /**
  * batadv_dat_inc_counter() - increment the correct DAT packet counter
@@ -169,6 +171,12 @@ static inline void batadv_dat_free(struct batadv_priv 
*bat_priv)
 {
 }
 
+static inline int
+batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
+{
+       return -EOPNOTSUPP;
+}
+
 static inline void batadv_dat_inc_counter(struct batadv_priv *bat_priv,
                                          u8 subtype)
 {
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index 129af56b..2b3e7c3f 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -45,6 +45,7 @@
 
 #include "bat_algo.h"
 #include "bridge_loop_avoidance.h"
+#include "distributed-arp-table.h"
 #include "gateway_client.h"
 #include "hard-interface.h"
 #include "originator.h"
@@ -64,39 +65,42 @@ static const struct genl_multicast_group 
batadv_netlink_mcgrps[] = {
 };
 
 static const struct nla_policy batadv_netlink_policy[NUM_BATADV_ATTR] = {
-       [BATADV_ATTR_VERSION]           = { .type = NLA_STRING },
-       [BATADV_ATTR_ALGO_NAME]         = { .type = NLA_STRING },
-       [BATADV_ATTR_MESH_IFINDEX]      = { .type = NLA_U32 },
-       [BATADV_ATTR_MESH_IFNAME]       = { .type = NLA_STRING },
-       [BATADV_ATTR_MESH_ADDRESS]      = { .len = ETH_ALEN },
-       [BATADV_ATTR_HARD_IFINDEX]      = { .type = NLA_U32 },
-       [BATADV_ATTR_HARD_IFNAME]       = { .type = NLA_STRING },
-       [BATADV_ATTR_HARD_ADDRESS]      = { .len = ETH_ALEN },
-       [BATADV_ATTR_ORIG_ADDRESS]      = { .len = ETH_ALEN },
-       [BATADV_ATTR_TPMETER_RESULT]    = { .type = NLA_U8 },
-       [BATADV_ATTR_TPMETER_TEST_TIME] = { .type = NLA_U32 },
-       [BATADV_ATTR_TPMETER_BYTES]     = { .type = NLA_U64 },
-       [BATADV_ATTR_TPMETER_COOKIE]    = { .type = NLA_U32 },
-       [BATADV_ATTR_ACTIVE]            = { .type = NLA_FLAG },
-       [BATADV_ATTR_TT_ADDRESS]        = { .len = ETH_ALEN },
-       [BATADV_ATTR_TT_TTVN]           = { .type = NLA_U8 },
-       [BATADV_ATTR_TT_LAST_TTVN]      = { .type = NLA_U8 },
-       [BATADV_ATTR_TT_CRC32]          = { .type = NLA_U32 },
-       [BATADV_ATTR_TT_VID]            = { .type = NLA_U16 },
-       [BATADV_ATTR_TT_FLAGS]          = { .type = NLA_U32 },
-       [BATADV_ATTR_FLAG_BEST]         = { .type = NLA_FLAG },
-       [BATADV_ATTR_LAST_SEEN_MSECS]   = { .type = NLA_U32 },
-       [BATADV_ATTR_NEIGH_ADDRESS]     = { .len = ETH_ALEN },
-       [BATADV_ATTR_TQ]                = { .type = NLA_U8 },
-       [BATADV_ATTR_THROUGHPUT]        = { .type = NLA_U32 },
-       [BATADV_ATTR_BANDWIDTH_UP]      = { .type = NLA_U32 },
-       [BATADV_ATTR_BANDWIDTH_DOWN]    = { .type = NLA_U32 },
-       [BATADV_ATTR_ROUTER]            = { .len = ETH_ALEN },
-       [BATADV_ATTR_BLA_OWN]           = { .type = NLA_FLAG },
-       [BATADV_ATTR_BLA_ADDRESS]       = { .len = ETH_ALEN },
-       [BATADV_ATTR_BLA_VID]           = { .type = NLA_U16 },
-       [BATADV_ATTR_BLA_BACKBONE]      = { .len = ETH_ALEN },
-       [BATADV_ATTR_BLA_CRC]           = { .type = NLA_U16 },
+       [BATADV_ATTR_VERSION]                   = { .type = NLA_STRING },
+       [BATADV_ATTR_ALGO_NAME]                 = { .type = NLA_STRING },
+       [BATADV_ATTR_MESH_IFINDEX]              = { .type = NLA_U32 },
+       [BATADV_ATTR_MESH_IFNAME]               = { .type = NLA_STRING },
+       [BATADV_ATTR_MESH_ADDRESS]              = { .len = ETH_ALEN },
+       [BATADV_ATTR_HARD_IFINDEX]              = { .type = NLA_U32 },
+       [BATADV_ATTR_HARD_IFNAME]               = { .type = NLA_STRING },
+       [BATADV_ATTR_HARD_ADDRESS]              = { .len = ETH_ALEN },
+       [BATADV_ATTR_ORIG_ADDRESS]              = { .len = ETH_ALEN },
+       [BATADV_ATTR_TPMETER_RESULT]            = { .type = NLA_U8 },
+       [BATADV_ATTR_TPMETER_TEST_TIME]         = { .type = NLA_U32 },
+       [BATADV_ATTR_TPMETER_BYTES]             = { .type = NLA_U64 },
+       [BATADV_ATTR_TPMETER_COOKIE]            = { .type = NLA_U32 },
+       [BATADV_ATTR_ACTIVE]                    = { .type = NLA_FLAG },
+       [BATADV_ATTR_TT_ADDRESS]                = { .len = ETH_ALEN },
+       [BATADV_ATTR_TT_TTVN]                   = { .type = NLA_U8 },
+       [BATADV_ATTR_TT_LAST_TTVN]              = { .type = NLA_U8 },
+       [BATADV_ATTR_TT_CRC32]                  = { .type = NLA_U32 },
+       [BATADV_ATTR_TT_VID]                    = { .type = NLA_U16 },
+       [BATADV_ATTR_TT_FLAGS]                  = { .type = NLA_U32 },
+       [BATADV_ATTR_FLAG_BEST]                 = { .type = NLA_FLAG },
+       [BATADV_ATTR_LAST_SEEN_MSECS]           = { .type = NLA_U32 },
+       [BATADV_ATTR_NEIGH_ADDRESS]             = { .len = ETH_ALEN },
+       [BATADV_ATTR_TQ]                        = { .type = NLA_U8 },
+       [BATADV_ATTR_THROUGHPUT]                = { .type = NLA_U32 },
+       [BATADV_ATTR_BANDWIDTH_UP]              = { .type = NLA_U32 },
+       [BATADV_ATTR_BANDWIDTH_DOWN]            = { .type = NLA_U32 },
+       [BATADV_ATTR_ROUTER]                    = { .len = ETH_ALEN },
+       [BATADV_ATTR_BLA_OWN]                   = { .type = NLA_FLAG },
+       [BATADV_ATTR_BLA_ADDRESS]               = { .len = ETH_ALEN },
+       [BATADV_ATTR_BLA_VID]                   = { .type = NLA_U16 },
+       [BATADV_ATTR_BLA_BACKBONE]              = { .len = ETH_ALEN },
+       [BATADV_ATTR_BLA_CRC]                   = { .type = NLA_U16 },
+       [BATADV_ATTR_DAT_CACHE_IP4ADDRESS]      = { .type = NLA_U32 },
+       [BATADV_ATTR_DAT_CACHE_HWADDRESS]       = { .len = ETH_ALEN },
+       [BATADV_ATTR_DAT_CACHE_VID]             = { .type = NLA_U16 },
 };
 
 /**
@@ -604,6 +608,12 @@ static const struct genl_ops batadv_netlink_ops[] = {
                .policy = batadv_netlink_policy,
                .dumpit = batadv_bla_backbone_dump,
        },
+       {
+               .cmd = BATADV_CMD_GET_DAT_CACHE,
+               .flags = GENL_ADMIN_PERM,
+               .policy = batadv_netlink_policy,
+               .dumpit = batadv_dat_cache_dump,
+       },
 
 };
 
-- 
2.11.0

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