[NETNS]: Modify the neighbour table code so it handles multiple network namespaces

I'm actually surprised at how much was involved.  At first glance it
appears that the neighbour table data structures are already split by
network device so all that should be needed is to modify the user
interface commands to filter the set of neighbours by the network
namespace of their devices.

However a couple things turned up while I was reading through the
code.  The proxy neighbour table allows entries with no network
device, and the neighbour parms are per network device (except for the
defaults) so they now need a per network namespace default.

So I updated the two structures (which surprised me) with their very
own network namespace parameter.  Updated the relevant lookup and
destroy routines with a network namespace parameter and modified the
code that interacts with users to filter out neighbour table entries
for devices of other namespaces.

I'm a little concerned that we can modify and display the global table
configuration and from all network namespaces.  But this appears good
enough for now.

I keep thinking modifying the neighbour table to have per network
namespace instances of each table type would should be cleaner.  The
hash table is already dynamically sized so there are it is not a
limiter.  The default parameter would be straight forward to take care
of.  However when I look at the how the network table is built and
used I still find some assumptions that there is only a single
neighbour table for each type of table in the kernel.  The netlink
operations, neigh_seq_start, the non-core network users that call
neigh_lookup.  So while it might be doable it would require more
refactoring than my current approach of just doing a little extra
filtering in the code.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 72 insertions, 44 deletions

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 9a283fc..bd899d5 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -375,7 +375,8 @@ struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
 	return n;
 }
 
-struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, const void *pkey)
+struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
+				     const void *pkey)
 {
 	struct neighbour *n;
 	int key_len = tbl->key_len;
@@ -385,7 +386,8 @@ struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, const void *pkey)
 
 	read_lock_bh(&tbl->lock);
 	for (n = tbl->hash_buckets[hash_val & tbl->hash_mask]; n; n = n->next) {
-		if (!memcmp(n->primary_key, pkey, key_len)) {
+		if (!memcmp(n->primary_key, pkey, key_len) &&
+		    (net == n->dev->nd_net)) {
 			neigh_hold(n);
 			NEIGH_CACHE_STAT_INC(tbl, hits);
 			break;
@@ -463,7 +465,8 @@ out_neigh_release:
 	goto out;
 }
 
-struct pneigh_entry * pneigh_lookup(struct neigh_table *tbl, const void *pkey,
+struct pneigh_entry * pneigh_lookup(struct neigh_table *tbl,
+				    struct net *net, const void *pkey,
 				    struct net_device *dev, int creat)
 {
 	struct pneigh_entry *n;
@@ -479,6 +482,7 @@ struct pneigh_entry * pneigh_lookup(struct neigh_table *tbl, const void *pkey,
 
 	for (n = tbl->phash_buckets[hash_val]; n; n = n->next) {
 		if (!memcmp(n->key, pkey, key_len) &&
+		    (n->net == net) &&
 		    (n->dev == dev || !n->dev)) {
 			read_unlock_bh(&tbl->lock);
 			goto out;
@@ -495,6 +499,7 @@ struct pneigh_entry * pneigh_lookup(struct neigh_table *tbl, const void *pkey,
 	if (!n)
 		goto out;
 
+	n->net = hold_net(net);
 	memcpy(n->key, pkey, key_len);
 	n->dev = dev;
 	if (dev)
@@ -517,7 +522,7 @@ out:
 }
 
 
-int pneigh_delete(struct neigh_table *tbl, const void *pkey,
+int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *pkey,
 		  struct net_device *dev)
 {
 	struct pneigh_entry *n, **np;
@@ -532,13 +537,15 @@ int pneigh_delete(struct neigh_table *tbl, const void *pkey,
 	write_lock_bh(&tbl->lock);
 	for (np = &tbl->phash_buckets[hash_val]; (n = *np) != NULL;
 	     np = &n->next) {
-		if (!memcmp(n->key, pkey, key_len) && n->dev == dev) {
+		if (!memcmp(n->key, pkey, key_len) && n->dev == dev &&
+		    (n->net == net)) {
 			*np = n->next;
 			write_unlock_bh(&tbl->lock);
 			if (tbl->pdestructor)
 				tbl->pdestructor(n);
 			if (n->dev)
 				dev_put(n->dev);
+			release_net(n->net);
 			kfree(n);
 			return 0;
 		}
@@ -561,6 +568,7 @@ static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
 					tbl->pdestructor(n);
 				if (n->dev)
 					dev_put(n->dev);
+				release_net(n->net);
 				kfree(n);
 				continue;
 			}
@@ -1261,12 +1269,37 @@ void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
 	spin_unlock(&tbl->proxy_queue.lock);
 }
 
+static inline struct neigh_parms *lookup_neigh_params(struct neigh_table *tbl,
+						      struct net *net, int ifindex)
+{
+	struct neigh_parms *p;
+
+	for (p = &tbl->parms; p; p = p->next) {
+		if (p->net != net)
+			continue;
+		if ((p->dev && p->dev->ifindex == ifindex) ||
+		    (!p->dev && !ifindex))
+			return p;
+	}
+
+	return NULL;
+}
 
 struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
 				      struct neigh_table *tbl)
 {
-	struct neigh_parms *p = kmemdup(&tbl->parms, sizeof(*p), GFP_KERNEL);
+	struct neigh_parms *p, *ref;
+	struct net *net;
+
+	net = &init_net;
+	if (dev)
+		net = dev->nd_net;
+
+	ref = lookup_neigh_params(tbl, net, 0);
+	if (!ref)
+		return NULL;
 
+	p = kmemdup(ref, sizeof(*p), GFP_KERNEL);
 	if (p) {
 		p->tbl		  = tbl;
 		atomic_set(&p->refcnt, 1);
@@ -1282,6 +1315,7 @@ struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
 			dev_hold(dev);
 			p->dev = dev;
 		}
+		p->net = hold_net(net);
 		p->sysctl_table = NULL;
 		write_lock_bh(&tbl->lock);
 		p->next		= tbl->parms.next;
@@ -1323,6 +1357,7 @@ void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms)
 
 void neigh_parms_destroy(struct neigh_parms *parms)
 {
+	release_net(parms->net);
 	kfree(parms);
 }
 
@@ -1333,6 +1368,7 @@ void neigh_table_init_no_netlink(struct neigh_table *tbl)
 	unsigned long now = jiffies;
 	unsigned long phsize;
 
+	tbl->parms.net = &init_net;
 	atomic_set(&tbl->parms.refcnt, 1);
 	INIT_RCU_HEAD(&tbl->parms.rcu_head);
 	tbl->parms.reachable_time =
@@ -1446,9 +1482,6 @@ static int neigh_delete(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 	struct net_device *dev = NULL;
 	int err = -EINVAL;
 
-	if (net != &init_net)
-		return -EINVAL;
-
 	if (nlmsg_len(nlh) < sizeof(*ndm))
 		goto out;
 
@@ -1477,7 +1510,7 @@ static int neigh_delete(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 			goto out_dev_put;
 
 		if (ndm->ndm_flags & NTF_PROXY) {
-			err = pneigh_delete(tbl, nla_data(dst_attr), dev);
+			err = pneigh_delete(tbl, net, nla_data(dst_attr), dev);
 			goto out_dev_put;
 		}
 
@@ -1515,9 +1548,6 @@ static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 	struct net_device *dev = NULL;
 	int err;
 
-	if (net != &init_net)
-		return -EINVAL;
-
 	err = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, NULL);
 	if (err < 0)
 		goto out;
@@ -1557,7 +1587,7 @@ static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 			struct pneigh_entry *pn;
 
 			err = -ENOBUFS;
-			pn = pneigh_lookup(tbl, dst, dev, 1);
+			pn = pneigh_lookup(tbl, net, dst, dev, 1);
 			if (pn) {
 				pn->flags = ndm->ndm_flags;
 				err = 0;
@@ -1752,19 +1782,6 @@ errout:
 	return -EMSGSIZE;
 }
 
-static inline struct neigh_parms *lookup_neigh_params(struct neigh_table *tbl,
-						      int ifindex)
-{
-	struct neigh_parms *p;
-
-	for (p = &tbl->parms; p; p = p->next)
-		if ((p->dev && p->dev->ifindex == ifindex) ||
-		    (!p->dev && !ifindex))
-			return p;
-
-	return NULL;
-}
-
 static const struct nla_policy nl_neightbl_policy[NDTA_MAX+1] = {
 	[NDTA_NAME]		= { .type = NLA_STRING },
 	[NDTA_THRESH1]		= { .type = NLA_U32 },
@@ -1798,9 +1815,6 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 	struct nlattr *tb[NDTA_MAX+1];
 	int err;
 
-	if (net != &init_net)
-		return -EINVAL;
-
 	err = nlmsg_parse(nlh, sizeof(*ndtmsg), tb, NDTA_MAX,
 			  nl_neightbl_policy);
 	if (err < 0)
@@ -1845,7 +1859,7 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 		if (tbp[NDTPA_IFINDEX])
 			ifindex = nla_get_u32(tbp[NDTPA_IFINDEX]);
 
-		p = lookup_neigh_params(tbl, ifindex);
+		p = lookup_neigh_params(tbl, net, ifindex);
 		if (p == NULL) {
 			err = -ENOENT;
 			goto errout_tbl_lock;
@@ -1926,9 +1940,6 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
 	int neigh_skip = cb->args[1];
 	struct neigh_table *tbl;
 
-	if (net != &init_net)
-		return 0;
-
 	family = ((struct rtgenmsg *) nlmsg_data(cb->nlh))->rtgen_family;
 
 	read_lock(&neigh_tbl_lock);
@@ -1943,8 +1954,11 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
 				       NLM_F_MULTI) <= 0)
 			break;
 
-		for (nidx = 0, p = tbl->parms.next; p; p = p->next, nidx++) {
-			if (nidx < neigh_skip)
+		for (nidx = 0, p = tbl->parms.next; p; p = p->next) {
+			if (net != p->net)
+				continue;
+
+			if (nidx++ < neigh_skip)
 				continue;
 
 			if (neightbl_fill_param_info(skb, tbl, p,
@@ -2020,6 +2034,7 @@ static void neigh_update_notify(struct neighbour *neigh)
 static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
 			    struct netlink_callback *cb)
 {
+	struct net * net = skb->sk->sk_net;
 	struct neighbour *n;
 	int rc, h, s_h = cb->args[1];
 	int idx, s_idx = idx = cb->args[2];
@@ -2030,8 +2045,12 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
 			continue;
 		if (h > s_h)
 			s_idx = 0;
-		for (n = tbl->hash_buckets[h], idx = 0; n; n = n->next, idx++) {
-			if (idx < s_idx)
+		for (n = tbl->hash_buckets[h], idx = 0; n; n = n->next) {
+			int lidx;
+			if (n->dev->nd_net != net)
+				continue;
+			lidx = idx++;
+			if (lidx < s_idx)
 				continue;
 			if (neigh_fill_info(skb, n, NETLINK_CB(cb->skb).pid,
 					    cb->nlh->nlmsg_seq,
@@ -2053,13 +2072,9 @@ out:
 
 static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
 {
-	struct net *net = skb->sk->sk_net;
 	struct neigh_table *tbl;
 	int t, family, s_t;
 
-	if (net != &init_net)
-		return 0;
-
 	read_lock(&neigh_tbl_lock);
 	family = ((struct rtgenmsg *) nlmsg_data(cb->nlh))->rtgen_family;
 	s_t = cb->args[0];
@@ -2127,6 +2142,7 @@ EXPORT_SYMBOL(__neigh_for_each_release);
 static struct neighbour *neigh_get_first(struct seq_file *seq)
 {
 	struct neigh_seq_state *state = seq->private;
+	struct net *net = state->net;
 	struct neigh_table *tbl = state->tbl;
 	struct neighbour *n = NULL;
 	int bucket = state->bucket;
@@ -2136,6 +2152,8 @@ static struct neighbour *neigh_get_first(struct seq_file *seq)
 		n = tbl->hash_buckets[bucket];
 
 		while (n) {
+			if (n->dev->nd_net != net)
+				goto next;
 			if (state->neigh_sub_iter) {
 				loff_t fakep = 0;
 				void *v;
@@ -2165,6 +2183,7 @@ static struct neighbour *neigh_get_next(struct seq_file *seq,
 					loff_t *pos)
 {
 	struct neigh_seq_state *state = seq->private;
+	struct net *net = state->net;
 	struct neigh_table *tbl = state->tbl;
 
 	if (state->neigh_sub_iter) {
@@ -2176,6 +2195,8 @@ static struct neighbour *neigh_get_next(struct seq_file *seq,
 
 	while (1) {
 		while (n) {
+			if (n->dev->nd_net != net)
+				goto next;
 			if (state->neigh_sub_iter) {
 				void *v = state->neigh_sub_iter(state, n, pos);
 				if (v)
@@ -2222,6 +2243,7 @@ static struct neighbour *neigh_get_idx(struct seq_file *seq, loff_t *pos)
 static struct pneigh_entry *pneigh_get_first(struct seq_file *seq)
 {
 	struct neigh_seq_state *state = seq->private;
+	struct net * net = state->net;
 	struct neigh_table *tbl = state->tbl;
 	struct pneigh_entry *pn = NULL;
 	int bucket = state->bucket;
@@ -2229,6 +2251,8 @@ static struct pneigh_entry *pneigh_get_first(struct seq_file *seq)
 	state->flags |= NEIGH_SEQ_IS_PNEIGH;
 	for (bucket = 0; bucket <= PNEIGH_HASHMASK; bucket++) {
 		pn = tbl->phash_buckets[bucket];
+		while (pn && (pn->net != net))
+			pn = pn->next;
 		if (pn)
 			break;
 	}
@@ -2242,6 +2266,7 @@ static struct pneigh_entry *pneigh_get_next(struct seq_file *seq,
 					    loff_t *pos)
 {
 	struct neigh_seq_state *state = seq->private;
+	struct net * net = state->net;
 	struct neigh_table *tbl = state->tbl;
 
 	pn = pn->next;
@@ -2249,6 +2274,8 @@ static struct pneigh_entry *pneigh_get_next(struct seq_file *seq,
 		if (++state->bucket > PNEIGH_HASHMASK)
 			break;
 		pn = tbl->phash_buckets[state->bucket];
+		while (pn && (pn->net != net))
+			pn = pn->next;
 		if (pn)
 			break;
 	}
@@ -2450,6 +2477,7 @@ static inline size_t neigh_nlmsg_size(void)
 
 static void __neigh_notify(struct neighbour *n, int type, int flags)
 {
+	struct net *net = n->dev->nd_net;
 	struct sk_buff *skb;
 	int err = -ENOBUFS;
 
@@ -2464,10 +2492,10 @@ static void __neigh_notify(struct neighbour *n, int type, int flags)
 		kfree_skb(skb);
 		goto errout;
 	}
-	err = rtnl_notify(skb, &init_net, 0, RTNLGRP_NEIGH, NULL, GFP_ATOMIC);
+	err = rtnl_notify(skb, net, 0, RTNLGRP_NEIGH, NULL, GFP_ATOMIC);
 errout:
 	if (err < 0)
-		rtnl_set_sk_err(&init_net, RTNLGRP_NEIGH, err);
+		rtnl_set_sk_err(net, RTNLGRP_NEIGH, err);
 }
 
 #ifdef CONFIG_ARPD