netfilter: xtables: avoid percpu ruleset duplication

We store the rule blob per (possible) cpu.  Unfortunately this means we can
waste lot of memory on big smp machines. ipt_entry structure ('rule head')
is 112 byte, so e.g. with maxcpu=64 one single rule eats
close to 8k RAM.

Since previous patch made counters percpu it appears there is nothing
left in the rule blob that needs to be percpu.

On my test system (144 possible cpus, 400k dummy rules) this
change saves close to 9 Gigabyte of RAM.

Reported-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 16 insertions, 49 deletions

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index a1190ee14723..80a7f0d38aa4 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -283,15 +283,13 @@ static void trace_packet(const struct sk_buff *skb,
 			 const struct xt_table_info *private,
 			 const struct ip6t_entry *e)
 {
-	const void *table_base;
 	const struct ip6t_entry *root;
 	const char *hookname, *chainname, *comment;
 	const struct ip6t_entry *iter;
 	unsigned int rulenum = 0;
 	struct net *net = dev_net(in ? in : out);
 
-	table_base = private->entries[smp_processor_id()];
-	root = get_entry(table_base, private->hook_entry[hook]);
+	root = get_entry(private->entries, private->hook_entry[hook]);
 
 	hookname = chainname = hooknames[hook];
 	comment = comments[NF_IP6_TRACE_COMMENT_RULE];
@@ -357,7 +355,7 @@ ip6t_do_table(struct sk_buff *skb,
 	 */
 	smp_read_barrier_depends();
 	cpu        = smp_processor_id();
-	table_base = private->entries[cpu];
+	table_base = private->entries;
 	jumpstack  = (struct ip6t_entry **)private->jumpstack[cpu];
 	stackptr   = per_cpu_ptr(private->stackptr, cpu);
 	origptr    = *stackptr;
@@ -890,12 +888,6 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
 		return ret;
 	}
 
-	/* And one copy for every other CPU */
-	for_each_possible_cpu(i) {
-		if (newinfo->entries[i] && newinfo->entries[i] != entry0)
-			memcpy(newinfo->entries[i], entry0, newinfo->size);
-	}
-
 	return ret;
 }
 
@@ -911,7 +903,7 @@ get_counters(const struct xt_table_info *t,
 		seqcount_t *s = &per_cpu(xt_recseq, cpu);
 
 		i = 0;
-		xt_entry_foreach(iter, t->entries[cpu], t->size) {
+		xt_entry_foreach(iter, t->entries, t->size) {
 			struct xt_counters *tmp;
 			u64 bcnt, pcnt;
 			unsigned int start;
@@ -959,17 +951,13 @@ copy_entries_to_user(unsigned int total_size,
 	struct xt_counters *counters;
 	const struct xt_table_info *private = table->private;
 	int ret = 0;
-	const void *loc_cpu_entry;
+	void *loc_cpu_entry;
 
 	counters = alloc_counters(table);
 	if (IS_ERR(counters))
 		return PTR_ERR(counters);
 
-	/* choose the copy that is on our node/cpu, ...
-	 * This choice is lazy (because current thread is
-	 * allowed to migrate to another cpu)
-	 */
-	loc_cpu_entry = private->entries[raw_smp_processor_id()];
+	loc_cpu_entry = private->entries;
 	if (copy_to_user(userptr, loc_cpu_entry, total_size) != 0) {
 		ret = -EFAULT;
 		goto free_counters;
@@ -1083,10 +1071,10 @@ static int compat_table_info(const struct xt_table_info *info,
 	if (!newinfo || !info)
 		return -EINVAL;
 
-	/* we dont care about newinfo->entries[] */
+	/* we dont care about newinfo->entries */
 	memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
 	newinfo->initial_entries = 0;
-	loc_cpu_entry = info->entries[raw_smp_processor_id()];
+	loc_cpu_entry = info->entries;
 	xt_compat_init_offsets(AF_INET6, info->number);
 	xt_entry_foreach(iter, loc_cpu_entry, info->size) {
 		ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
@@ -1207,7 +1195,6 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
 	struct xt_table *t;
 	struct xt_table_info *oldinfo;
 	struct xt_counters *counters;
-	const void *loc_cpu_old_entry;
 	struct ip6t_entry *iter;
 
 	ret = 0;
@@ -1250,8 +1237,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
 	get_counters(oldinfo, counters);
 
 	/* Decrease module usage counts and free resource */
-	loc_cpu_old_entry = oldinfo->entries[raw_smp_processor_id()];
-	xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
+	xt_entry_foreach(iter, oldinfo->entries, oldinfo->size)
 		cleanup_entry(iter, net);
 
 	xt_free_table_info(oldinfo);
@@ -1297,8 +1283,7 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
 	if (!newinfo)
 		return -ENOMEM;
 
-	/* choose the copy that is on our node/cpu */
-	loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
+	loc_cpu_entry = newinfo->entries;
 	if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
 			   tmp.size) != 0) {
 		ret = -EFAULT;
@@ -1329,7 +1314,7 @@ static int
 do_add_counters(struct net *net, const void __user *user, unsigned int len,
 		int compat)
 {
-	unsigned int i, curcpu;
+	unsigned int i;
 	struct xt_counters_info tmp;
 	struct xt_counters *paddc;
 	unsigned int num_counters;
@@ -1339,7 +1324,6 @@ do_add_counters(struct net *net, const void __user *user, unsigned int len,
 	struct xt_table *t;
 	const struct xt_table_info *private;
 	int ret = 0;
-	const void *loc_cpu_entry;
 	struct ip6t_entry *iter;
 	unsigned int addend;
 #ifdef CONFIG_COMPAT
@@ -1395,11 +1379,8 @@ do_add_counters(struct net *net, const void __user *user, unsigned int len,
 	}
 
 	i = 0;
-	/* Choose the copy that is on our node */
-	curcpu = smp_processor_id();
 	addend = xt_write_recseq_begin();
-	loc_cpu_entry = private->entries[curcpu];
-	xt_entry_foreach(iter, loc_cpu_entry, private->size) {
+	xt_entry_foreach(iter, private->entries, private->size) {
 		struct xt_counters *tmp;
 
 		tmp = xt_get_this_cpu_counter(&iter->counters);
@@ -1407,7 +1388,6 @@ do_add_counters(struct net *net, const void __user *user, unsigned int len,
 		++i;
 	}
 	xt_write_recseq_end(addend);
-
  unlock_up_free:
 	local_bh_enable();
 	xt_table_unlock(t);
@@ -1750,7 +1730,7 @@ translate_compat_table(struct net *net,
 		newinfo->hook_entry[i] = info->hook_entry[i];
 		newinfo->underflow[i] = info->underflow[i];
 	}
-	entry1 = newinfo->entries[raw_smp_processor_id()];
+	entry1 = newinfo->entries;
 	pos = entry1;
 	size = total_size;
 	xt_entry_foreach(iter0, entry0, total_size) {
@@ -1802,11 +1782,6 @@ translate_compat_table(struct net *net,
 		return ret;
 	}
 
-	/* And one copy for every other CPU */
-	for_each_possible_cpu(i)
-		if (newinfo->entries[i] && newinfo->entries[i] != entry1)
-			memcpy(newinfo->entries[i], entry1, newinfo->size);
-
 	*pinfo = newinfo;
 	*pentry0 = entry1;
 	xt_free_table_info(info);
@@ -1853,8 +1828,7 @@ compat_do_replace(struct net *net, void __user *user, unsigned int len)
 	if (!newinfo)
 		return -ENOMEM;
 
-	/* choose the copy that is on our node/cpu */
-	loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
+	loc_cpu_entry = newinfo->entries;
 	if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
 			   tmp.size) != 0) {
 		ret = -EFAULT;
@@ -1925,7 +1899,6 @@ compat_copy_entries_to_user(unsigned int total_size, struct xt_table *table,
 	void __user *pos;
 	unsigned int size;
 	int ret = 0;
-	const void *loc_cpu_entry;
 	unsigned int i = 0;
 	struct ip6t_entry *iter;
 
@@ -1933,14 +1906,9 @@ compat_copy_entries_to_user(unsigned int total_size, struct xt_table *table,
 	if (IS_ERR(counters))
 		return PTR_ERR(counters);
 
-	/* choose the copy that is on our node/cpu, ...
-	 * This choice is lazy (because current thread is
-	 * allowed to migrate to another cpu)
-	 */
-	loc_cpu_entry = private->entries[raw_smp_processor_id()];
 	pos = userptr;
 	size = total_size;
-	xt_entry_foreach(iter, loc_cpu_entry, total_size) {
+	xt_entry_foreach(iter, private->entries, total_size) {
 		ret = compat_copy_entry_to_user(iter, &pos,
 						&size, counters, i++);
 		if (ret != 0)
@@ -2115,8 +2083,7 @@ struct xt_table *ip6t_register_table(struct net *net,
 		goto out;
 	}
 
-	/* choose the copy on our node/cpu, but dont care about preemption */
-	loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
+	loc_cpu_entry = newinfo->entries;
 	memcpy(loc_cpu_entry, repl->entries, repl->size);
 
 	ret = translate_table(net, newinfo, loc_cpu_entry, repl);
@@ -2146,7 +2113,7 @@ void ip6t_unregister_table(struct net *net, struct xt_table *table)
 	private = xt_unregister_table(table);
 
 	/* Decrease module usage counts and free resources */
-	loc_cpu_entry = private->entries[raw_smp_processor_id()];
+	loc_cpu_entry = private->entries;
 	xt_entry_foreach(iter, loc_cpu_entry, private->size)
 		cleanup_entry(iter, net);
 	if (private->number > private->initial_entries)