[NETFILTER]: nf_conntrack: properly use RCU API for nf_ct_protos/nf_ct_l3protos arrays

Replace preempt_{enable,disable} based RCU by proper use of the RCU API and add missing rcu_read_lock/rcu_read_unlock calls in all paths not obviously only used within packet process context (nfnetlink_conntrack). Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: nf_conntrack: properly use RCU API for nf_ct_protos/nf_ct_l3protos arrays
Replace preempt_{enable,disable} based RCU by proper use of the RCU API and add missing rcu_read_lock/rcu_read_unlock calls in all paths not obviously only used within packet process context (nfnetlink_conntrack). Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Patrick McHardy · David S. Miller
1 parent 642d628b2c
Showing 6 changed files with 44 additions and 30 deletions Side-by-side Diff
include/net/netfilter/nf_conntrack_l3proto.h
net/ipv4/netfilter/nf_conntrack_proto_icmp.c
net/ipv4/netfilter/nf_nat_core.c
net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
net/netfilter/nf_conntrack_core.c
net/netfilter/nf_conntrack_proto.c
@@ -106,7 +106,7 @@
 {
 	if (unlikely(l3proto >= AF_MAX))
 		return &nf_conntrack_l3proto_generic;
-	return nf_ct_l3protos[l3proto];
+	return rcu_dereference(nf_ct_l3protos[l3proto]);
 }
  
 #endif /*_NF_CONNTRACK_L3PROTO_H*/
@@ -170,7 +170,9 @@
 		return -NF_ACCEPT;
 	}
  
+	/* rcu_read_lock()ed by nf_hook_slow */
 	innerproto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
+
 	dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp);
 	/* Are they talking about one of our connections? */
 	if (!nf_ct_get_tuple(skb, dataoff, dataoff + inside->ip.ihl*4, PF_INET,
@@ -429,6 +429,7 @@
 		struct icmphdr icmp;
 		struct iphdr ip;
 	} *inside;
+	struct nf_conntrack_l4proto *l4proto;
 	struct nf_conntrack_tuple inner, target;
 	int hdrlen = (*pskb)->nh.iph->ihl * 4;
 	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
  
@@ -464,16 +465,16 @@
 	DEBUGP("icmp_reply_translation: translating error %p manp %u dir %s\n",
 	       *pskb, manip, dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY");
  
+	/* rcu_read_lock()ed by nf_hook_slow */
+	l4proto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
+
 	if (!nf_ct_get_tuple(*pskb,
 			     (*pskb)->nh.iph->ihl*4 + sizeof(struct icmphdr),
 			     (*pskb)->nh.iph->ihl*4 +
 			     sizeof(struct icmphdr) + inside->ip.ihl*4,
 			     (u_int16_t)AF_INET,
 			     inside->ip.protocol,
-			     &inner,
-			     l3proto,
-			     __nf_ct_l4proto_find((u_int16_t)PF_INET,
-						  inside->ip.protocol)))
+			     &inner, l3proto, l4proto))
 		return 0;
  
 	/* Change inner back to look like incoming packet.  We do the
@@ -182,6 +182,7 @@
 		return -NF_ACCEPT;
 	}
  
+	/* rcu_read_lock()ed by nf_hook_slow */
 	inproto = __nf_ct_l4proto_find(PF_INET6, inprotonum);
  
 	/* Are they talking about one of our connections? */
@@ -332,13 +332,16 @@
 	/* To make sure we don't get any weird locking issues here:
 	 * destroy_conntrack() MUST NOT be called with a write lock
 	 * to nf_conntrack_lock!!! -HW */
+	rcu_read_lock();
 	l3proto = __nf_ct_l3proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num);
 	if (l3proto && l3proto->destroy)
 		l3proto->destroy(ct);
  
-	l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num, ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
+	l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num,
+				       ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
 	if (l4proto && l4proto->destroy)
 		l4proto->destroy(ct);
+	rcu_read_unlock();
  
 	if (nf_conntrack_destroyed)
 		nf_conntrack_destroyed(ct);
  
  
@@ -647,9 +650,14 @@
 				   const struct nf_conntrack_tuple *repl)
 {
 	struct nf_conntrack_l3proto *l3proto;
+	struct nf_conn *ct;
  
+	rcu_read_lock();
 	l3proto = __nf_ct_l3proto_find(orig->src.l3num);
-	return __nf_conntrack_alloc(orig, repl, l3proto, 0);
+	ct = __nf_conntrack_alloc(orig, repl, l3proto, 0);
+	rcu_read_unlock();
+
+	return ct;
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_alloc);
  
  
@@ -817,7 +825,9 @@
 		return NF_ACCEPT;
 	}
  
+	/* rcu_read_lock()ed by nf_hook_slow */
 	l3proto = __nf_ct_l3proto_find((u_int16_t)pf);
+
 	if ((ret = l3proto->prepare(pskb, hooknum, &dataoff, &protonum)) <= 0) {
 		DEBUGP("not prepared to track yet or error occured\n");
 		return -ret;
@@ -872,10 +882,15 @@
 int nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse,
 			 const struct nf_conntrack_tuple *orig)
 {
-	return nf_ct_invert_tuple(inverse, orig,
-				  __nf_ct_l3proto_find(orig->src.l3num),
-				  __nf_ct_l4proto_find(orig->src.l3num,
-						     orig->dst.protonum));
+	int ret;
+
+	rcu_read_lock();
+	ret = nf_ct_invert_tuple(inverse, orig,
+				 __nf_ct_l3proto_find(orig->src.l3num),
+				 __nf_ct_l4proto_find(orig->src.l3num,
+						      orig->dst.protonum));
+	rcu_read_unlock();
+	return ret;
 }
 EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr);
  
@@ -66,7 +66,7 @@
 	if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
 		return &nf_conntrack_l4proto_generic;
  
-	return nf_ct_protos[l3proto][l4proto];
+	return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
 }
 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
  
  
@@ -77,11 +77,11 @@
 {
 	struct nf_conntrack_l4proto *p;
  
-	preempt_disable();
+	rcu_read_lock();
 	p = __nf_ct_l4proto_find(l3proto, l4proto);
 	if (!try_module_get(p->me))
 		p = &nf_conntrack_l4proto_generic;
-	preempt_enable();
+	rcu_read_unlock();
  
 	return p;
 }
  
@@ -98,11 +98,11 @@
 {
 	struct nf_conntrack_l3proto *p;
  
-	preempt_disable();
+	rcu_read_lock();
 	p = __nf_ct_l3proto_find(l3proto);
 	if (!try_module_get(p->me))
 		p = &nf_conntrack_l3proto_generic;
-	preempt_enable();
+	rcu_read_unlock();
  
 	return p;
 }
  
@@ -137,10 +137,8 @@
 {
 	struct nf_conntrack_l3proto *p;
  
-	preempt_disable();
+	/* rcu_read_lock not necessary since the caller holds a reference */
 	p = __nf_ct_l3proto_find(l3proto);
-	preempt_enable();
-
 	module_put(p->me);
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
@@ -202,7 +200,7 @@
 		ret = -EBUSY;
 		goto out_unlock;
 	}
-	nf_ct_l3protos[proto->l3proto] = proto;
+	rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 	write_unlock_bh(&nf_conntrack_lock);
  
 	ret = nf_ct_l3proto_register_sysctl(proto);
  
  
@@ -233,14 +231,13 @@
 		goto out;
 	}
  
-	nf_ct_l3protos[proto->l3proto] = &nf_conntrack_l3proto_generic;
+	rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
+			   &nf_conntrack_l3proto_generic);
 	write_unlock_bh(&nf_conntrack_lock);
+	synchronize_rcu();
  
 	nf_ct_l3proto_unregister_sysctl(proto);
  
-	/* Somebody could be still looking at the proto in bh. */
-	synchronize_net();
-
 	/* Remove all contrack entries for this protocol */
 	nf_ct_iterate_cleanup(kill_l3proto, proto);
  
@@ -356,7 +353,7 @@
 		goto retry;
 	}
  
-	nf_ct_protos[l4proto->l3proto][l4proto->l4proto] = l4proto;
+	rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto], l4proto);
 	write_unlock_bh(&nf_conntrack_lock);
  
 	ret = nf_ct_l4proto_register_sysctl(l4proto);
  
  
@@ -392,14 +389,12 @@
 		ret = -EBUSY;
 		goto out;
 	}
-	nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
-		= &nf_conntrack_l4proto_generic;
+	rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
+			   &nf_conntrack_l4proto_generic);
 	write_unlock_bh(&nf_conntrack_lock);
+	synchronize_rcu();
  
 	nf_ct_l4proto_unregister_sysctl(l4proto);
-
-	/* Somebody could be still looking at the proto in bh. */
-	synchronize_net();
  
 	/* Remove all contrack entries for this protocol */
 	nf_ct_iterate_cleanup(kill_l4proto, l4proto);
...	...	@@ -106,7 +106,7 @@
106	106	{
107	107	if (unlikely(l3proto >= AF_MAX))
108	108	return &nf_conntrack_l3proto_generic;
109		- return nf_ct_l3protos[l3proto];
	109	+ return rcu_dereference(nf_ct_l3protos[l3proto]);
110	110	}
111	111
112	112	#endif /_NF_CONNTRACK_L3PROTO_H/
...	...	@@ -170,7 +170,9 @@
170	170	return -NF_ACCEPT;
171	171	}
172	172
	173	+ /* rcu_read_lock()ed by nf_hook_slow */
173	174	innerproto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
	175	+
174	176	dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp);
175	177	/* Are they talking about one of our connections? */
176	178	if (!nf_ct_get_tuple(skb, dataoff, dataoff + inside->ip.ihl*4, PF_INET,
...	...	@@ -429,6 +429,7 @@
429	429	struct icmphdr icmp;
430	430	struct iphdr ip;
431	431	} *inside;
	432	+ struct nf_conntrack_l4proto *l4proto;
432	433	struct nf_conntrack_tuple inner, target;
433	434	int hdrlen = (pskb)->nh.iph->ihl 4;
434	435	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
435	436
...	...	@@ -464,16 +465,16 @@
464	465	DEBUGP("icmp_reply_translation: translating error %p manp %u dir %s\n",
465	466	*pskb, manip, dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY");
466	467
	468	+ /* rcu_read_lock()ed by nf_hook_slow */
	469	+ l4proto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
	470	+
467	471	if (!nf_ct_get_tuple(*pskb,
468	472	(pskb)->nh.iph->ihl4 + sizeof(struct icmphdr),
469	473	(pskb)->nh.iph->ihl4 +
470	474	sizeof(struct icmphdr) + inside->ip.ihl*4,
471	475	(u_int16_t)AF_INET,
472	476	inside->ip.protocol,
473		- &inner,
474		- l3proto,
475		- __nf_ct_l4proto_find((u_int16_t)PF_INET,
476		- inside->ip.protocol)))
	477	+ &inner, l3proto, l4proto))
477	478	return 0;
478	479
479	480	/* Change inner back to look like incoming packet. We do the
...	...	@@ -182,6 +182,7 @@
182	182	return -NF_ACCEPT;
183	183	}
184	184
	185	+ /* rcu_read_lock()ed by nf_hook_slow */
185	186	inproto = __nf_ct_l4proto_find(PF_INET6, inprotonum);
186	187
187	188	/* Are they talking about one of our connections? */
...	...	@@ -332,13 +332,16 @@
332	332	/* To make sure we don't get any weird locking issues here:
333	333	* destroy_conntrack() MUST NOT be called with a write lock
334	334	* to nf_conntrack_lock!!! -HW */
	335	+ rcu_read_lock();
335	336	l3proto = __nf_ct_l3proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num);
336	337	if (l3proto && l3proto->destroy)
337	338	l3proto->destroy(ct);
338	339
339		- l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num, ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
	340	+ l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num,
	341	+ ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
340	342	if (l4proto && l4proto->destroy)
341	343	l4proto->destroy(ct);
	344	+ rcu_read_unlock();
342	345
343	346	if (nf_conntrack_destroyed)
344	347	nf_conntrack_destroyed(ct);
345	348
346	349
...	...	@@ -647,9 +650,14 @@
647	650	const struct nf_conntrack_tuple *repl)
648	651	{
649	652	struct nf_conntrack_l3proto *l3proto;
	653	+ struct nf_conn *ct;
650	654
	655	+ rcu_read_lock();
651	656	l3proto = __nf_ct_l3proto_find(orig->src.l3num);
652		- return __nf_conntrack_alloc(orig, repl, l3proto, 0);
	657	+ ct = __nf_conntrack_alloc(orig, repl, l3proto, 0);
	658	+ rcu_read_unlock();
	659	+
	660	+ return ct;
653	661	}
654	662	EXPORT_SYMBOL_GPL(nf_conntrack_alloc);
655	663
656	664
...	...	@@ -817,7 +825,9 @@
817	825	return NF_ACCEPT;
818	826	}
819	827
	828	+ /* rcu_read_lock()ed by nf_hook_slow */
820	829	l3proto = __nf_ct_l3proto_find((u_int16_t)pf);
	830	+
821	831	if ((ret = l3proto->prepare(pskb, hooknum, &dataoff, &protonum)) <= 0) {
822	832	DEBUGP("not prepared to track yet or error occured\n");
823	833	return -ret;
...	...	@@ -872,10 +882,15 @@
872	882	int nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse,
873	883	const struct nf_conntrack_tuple *orig)
874	884	{
875		- return nf_ct_invert_tuple(inverse, orig,
876		- __nf_ct_l3proto_find(orig->src.l3num),
877		- __nf_ct_l4proto_find(orig->src.l3num,
878		- orig->dst.protonum));
	885	+ int ret;
	886	+
	887	+ rcu_read_lock();
	888	+ ret = nf_ct_invert_tuple(inverse, orig,
	889	+ __nf_ct_l3proto_find(orig->src.l3num),
	890	+ __nf_ct_l4proto_find(orig->src.l3num,
	891	+ orig->dst.protonum));
	892	+ rcu_read_unlock();
	893	+ return ret;
879	894	}
880	895	EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr);
881	896
...	...	@@ -66,7 +66,7 @@
66	66	if (unlikely(l3proto >= AF_MAX \|\| nf_ct_protos[l3proto] == NULL))
67	67	return &nf_conntrack_l4proto_generic;
68	68
69		- return nf_ct_protos[l3proto][l4proto];
	69	+ return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
70	70	}
71	71	EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
72	72
73	73
...	...	@@ -77,11 +77,11 @@
77	77	{
78	78	struct nf_conntrack_l4proto *p;
79	79
80		- preempt_disable();
	80	+ rcu_read_lock();
81	81	p = __nf_ct_l4proto_find(l3proto, l4proto);
82	82	if (!try_module_get(p->me))
83	83	p = &nf_conntrack_l4proto_generic;
84		- preempt_enable();
	84	+ rcu_read_unlock();
85	85
86	86	return p;
87	87	}
88	88
...	...	@@ -98,11 +98,11 @@
98	98	{
99	99	struct nf_conntrack_l3proto *p;
100	100
101		- preempt_disable();
	101	+ rcu_read_lock();
102	102	p = __nf_ct_l3proto_find(l3proto);
103	103	if (!try_module_get(p->me))
104	104	p = &nf_conntrack_l3proto_generic;
105		- preempt_enable();
	105	+ rcu_read_unlock();
106	106
107	107	return p;
108	108	}
109	109
...	...	@@ -137,10 +137,8 @@
137	137	{
138	138	struct nf_conntrack_l3proto *p;
139	139
140		- preempt_disable();
	140	+ /* rcu_read_lock not necessary since the caller holds a reference */
141	141	p = __nf_ct_l3proto_find(l3proto);
142		- preempt_enable();
143		-
144	142	module_put(p->me);
145	143	}
146	144	EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
...	...	@@ -202,7 +200,7 @@
202	200	ret = -EBUSY;
203	201	goto out_unlock;
204	202	}
205		- nf_ct_l3protos[proto->l3proto] = proto;
	203	+ rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
206	204	write_unlock_bh(&nf_conntrack_lock);
207	205
208	206	ret = nf_ct_l3proto_register_sysctl(proto);
209	207
210	208
...	...	@@ -233,14 +231,13 @@
233	231	goto out;
234	232	}
235	233
236		- nf_ct_l3protos[proto->l3proto] = &nf_conntrack_l3proto_generic;
	234	+ rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
	235	+ &nf_conntrack_l3proto_generic);
237	236	write_unlock_bh(&nf_conntrack_lock);
	237	+ synchronize_rcu();
238	238
239	239	nf_ct_l3proto_unregister_sysctl(proto);
240	240
241		- /* Somebody could be still looking at the proto in bh. */
242		- synchronize_net();
243		-
244	241	/* Remove all contrack entries for this protocol */
245	242	nf_ct_iterate_cleanup(kill_l3proto, proto);
246	243
...	...	@@ -356,7 +353,7 @@
356	353	goto retry;
357	354	}
358	355
359		- nf_ct_protos[l4proto->l3proto][l4proto->l4proto] = l4proto;
	356	+ rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto], l4proto);
360	357	write_unlock_bh(&nf_conntrack_lock);
361	358
362	359	ret = nf_ct_l4proto_register_sysctl(l4proto);
363	360
364	361
...	...	@@ -392,14 +389,12 @@
392	389	ret = -EBUSY;
393	390	goto out;
394	391	}
395		- nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
396		- = &nf_conntrack_l4proto_generic;
	392	+ rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
	393	+ &nf_conntrack_l4proto_generic);
397	394	write_unlock_bh(&nf_conntrack_lock);
	395	+ synchronize_rcu();
398	396
399	397	nf_ct_l4proto_unregister_sysctl(l4proto);
400		-
401		- /* Somebody could be still looking at the proto in bh. */
402		- synchronize_net();
403	398
404	399	/* Remove all contrack entries for this protocol */
405	400	nf_ct_iterate_cleanup(kill_l4proto, l4proto);