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Message-Id: <20190513160335.24128-1-mcmahon@arista.com>
Date: Mon, 13 May 2019 17:03:35 +0100
From: mcmahon@...sta.com
To: davem@...emloft.net, dsahern@...il.com, roopa@...ulusnetworks.com,
christian@...uner.io, khlebnikov@...dex-team.ru,
lzgrablic@...sta.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, mowat@...sta.com, dmia@...sta.com
Cc: Ben McMahon <mcmahon@...sta.com>
Subject: getneigh: add nondump to retrieve single entry
From: Leonard Zgrablic <lzgrablic@...sta.com>
Currently there is only a dump version of RTM_GETNEIGH for PF_UNSPEC in
RTNETLINK that dumps neighbor entries, no non-dump version that can be used to
retrieve a single neighbor entry.
Add support for the non-dump (doit) version of RTM_GETNEIGH for PF_UNSPEC so
that a single neighbor entry can be retrieved.
Signed-off-by: Leonard Zgrablic <lzgrablic@...sta.com>
Signed-off-by: Ben McMahon <mcmahon@...sta.com>
---
net/core/neighbour.c | 160 +++++++++++++++++++++++++++++++++++++++----
1 file changed, 147 insertions(+), 13 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 30f6fd8f68e0..981f1568710b 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2733,6 +2733,149 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
return skb->len;
}
+static inline size_t neigh_nlmsg_size(void)
+{
+ return NLMSG_ALIGN(sizeof(struct ndmsg))
+ + nla_total_size(MAX_ADDR_LEN) /* NDA_DST */
+ + nla_total_size(MAX_ADDR_LEN) /* NDA_LLADDR */
+ + nla_total_size(sizeof(struct nda_cacheinfo))
+ + nla_total_size(4); /* NDA_PROBES */
+}
+
+static int neigh_find_fill(struct neigh_table *tbl, const void *pkey,
+ struct net_device *dev, struct sk_buff *skb, u32 pid,
+ u32 seq)
+{
+ struct neighbour *neigh;
+ int key_len = tbl->key_len;
+ u32 hash_val;
+ struct neigh_hash_table *nht;
+ int err;
+
+ if (dev == NULL)
+ return -EINVAL;
+
+ NEIGH_CACHE_STAT_INC(tbl, lookups);
+
+ rcu_read_lock_bh();
+ nht = rcu_dereference_bh(tbl->nht);
+ hash_val = tbl->hash(pkey, dev, nht->hash_rnd) >>
+ (32 - nht->hash_shift);
+
+ for (neigh = rcu_dereference_bh(nht->hash_buckets[hash_val]);
+ neigh != NULL;
+ neigh = rcu_dereference_bh(neigh->next)) {
+ if (dev == neigh->dev &&
+ !memcmp(neigh->primary_key, pkey, key_len)) {
+ if (!atomic_read(&neigh->refcnt))
+ neigh = NULL;
+ NEIGH_CACHE_STAT_INC(tbl, hits);
+ break;
+ }
+ }
+ if (neigh == NULL) {
+ err = -ENOENT;
+ goto out_rcu_read_unlock;
+ }
+
+ err = neigh_fill_info(skb, neigh, pid, seq, RTM_NEWNEIGH, 0);
+
+out_rcu_read_unlock:
+ rcu_read_unlock_bh();
+ return err;
+}
+
+static int pneigh_find_fill(struct neigh_table *tbl, const void *pkey,
+ struct net_device *dev, struct net *net,
+ struct sk_buff *skb, u32 pid, u32 seq)
+{
+ struct pneigh_entry *pneigh;
+ int key_len = tbl->key_len;
+ u32 hash_val = pneigh_hash(pkey, key_len);
+ int err;
+
+ read_lock_bh(&tbl->lock);
+
+ pneigh = __pneigh_lookup_1(tbl->phash_buckets[hash_val], net, pkey,
+ key_len, dev);
+ if (pneigh == NULL) {
+ err = -ENOENT;
+ goto out_read_unlock;
+ }
+
+ err = pneigh_fill_info(skb, pneigh, pid, seq, RTM_NEWNEIGH, 0, tbl);
+
+out_read_unlock:
+ read_unlock_bh(&tbl->lock);
+ return err;
+}
+
+static int neigh_get(struct sk_buff *skb, struct nlmsghdr *nlh)
+{
+ struct net *net = sock_net(skb->sk);
+ struct ndmsg *ndm;
+ struct nlattr *dst_attr;
+ struct neigh_table *tbl;
+ struct net_device *dev = NULL;
+
+ ASSERT_RTNL();
+ if (nlmsg_len(nlh) < sizeof(*ndm))
+ return -EINVAL;
+
+ dst_attr = nlmsg_find_attr(nlh, sizeof(*ndm), NDA_DST);
+ if (dst_attr == NULL)
+ return -EINVAL;
+
+ ndm = nlmsg_data(nlh);
+ if (ndm->ndm_ifindex) {
+ dev = __dev_get_by_index(net, ndm->ndm_ifindex);
+ if (dev == NULL)
+ return -ENODEV;
+ }
+
+ read_lock(&neigh_tbl_lock);
+ for (tbl = neigh_tables; tbl; tbl = tbl->next) {
+ struct sk_buff *nskb;
+ int err;
+
+ if (tbl->family != ndm->ndm_family)
+ continue;
+
+ read_unlock(&neigh_tbl_lock);
+
+ if (nla_len(dst_attr) < tbl->key_len)
+ return -EINVAL;
+
+ nskb = nlmsg_new(neigh_nlmsg_size(), GFP_KERNEL);
+ if (nskb == NULL)
+ return -ENOBUFS;
+
+ if (ndm->ndm_flags & NTF_PROXY)
+ err = pneigh_find_fill(tbl, nla_data(dst_attr), dev,
+ net, nskb,
+ NETLINK_CB(skb).portid,
+ nlh->nlmsg_seq);
+ else
+ err = neigh_find_fill(tbl, nla_data(dst_attr), dev,
+ nskb, NETLINK_CB(skb).portid,
+ nlh->nlmsg_seq);
+
+ if (err < 0) {
+ /* -EMSGSIZE implies BUG in neigh_nlmsg_size */
+ WARN_ON(err == -EMSGSIZE);
+ kfree_skb(nskb);
+ } else {
+ err = rtnl_unicast(nskb, net, NETLINK_CB(skb).portid);
+ }
+
+ return err;
+ }
+ read_unlock(&neigh_tbl_lock);
+ return -EAFNOSUPPORT;
+}
+
+
+
static int neigh_valid_get_req(const struct nlmsghdr *nlh,
struct neigh_table **tbl,
void **dst, int *dev_idx, u8 *ndm_flags,
@@ -2793,16 +2936,6 @@ static int neigh_valid_get_req(const struct nlmsghdr *nlh,
return 0;
}
-static inline size_t neigh_nlmsg_size(void)
-{
- return NLMSG_ALIGN(sizeof(struct ndmsg))
- + nla_total_size(MAX_ADDR_LEN) /* NDA_DST */
- + nla_total_size(MAX_ADDR_LEN) /* NDA_LLADDR */
- + nla_total_size(sizeof(struct nda_cacheinfo))
- + nla_total_size(4) /* NDA_PROBES */
- + nla_total_size(1); /* NDA_PROTOCOL */
-}
-
static int neigh_get_reply(struct net *net, struct neighbour *neigh,
u32 pid, u32 seq)
{
@@ -2827,8 +2960,8 @@ static int neigh_get_reply(struct net *net, struct neighbour *neigh,
static inline size_t pneigh_nlmsg_size(void)
{
return NLMSG_ALIGN(sizeof(struct ndmsg))
- + nla_total_size(MAX_ADDR_LEN) /* NDA_DST */
- + nla_total_size(1); /* NDA_PROTOCOL */
+ + nla_total_size(MAX_ADDR_LEN) /* NDA_DST */
+ + nla_total_size(1); /* NDA_PROTOCOL */
}
static int pneigh_get_reply(struct net *net, struct pneigh_entry *neigh,
@@ -3703,7 +3836,8 @@ static int __init neigh_init(void)
{
rtnl_register(PF_UNSPEC, RTM_NEWNEIGH, neigh_add, NULL, 0);
rtnl_register(PF_UNSPEC, RTM_DELNEIGH, neigh_delete, NULL, 0);
- rtnl_register(PF_UNSPEC, RTM_GETNEIGH, neigh_get, neigh_dump_info, 0);
+ rtnl_register(PF_UNSPEC, RTM_GETNEIGH, neigh_get, neigh_dump_info,
+ NULL);
rtnl_register(PF_UNSPEC, RTM_GETNEIGHTBL, NULL, neightbl_dump_info,
0);
--
2.21.0
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