netfilter 00/03: netfilter fixes

netfilter 00/03: netfilter fixes

[Patrick McHardy]

Hi Dave,

following are two netfilter fixes for 2.6.31 and a MAINTAINERS update:

- a fix for the nf_conntrack_alloc() race from Eric
- a fix for incorrect invocation of nf_log_packet() in the new osf match
- a patch to add my netfilter git tree to MAINTAINERS

Please apply or pull from:

git://git.kernel.org/pub/scm/linux/kernel/git/kaber/nf-2.6.git master

Thanks!


 Documentation/RCU/rculist_nulls.txt |    7 ++++++-
 MAINTAINERS                         |    1 +
 net/netfilter/nf_conntrack_core.c   |   21 ++++++++++++++++++---
 net/netfilter/xt_osf.c              |    5 +++--
 4 files changed, 28 insertions(+), 6 deletions(-)

Eric Dumazet (1):
      netfilter: nf_conntrack: nf_conntrack_alloc() fixes

Joe Perches (1):
      netfilter: add netfilter git to MAINTAINERS

Patrick McHardy (1):
      netfilter: xt_osf: fix nf_log_packet() arguments

netfilter 01/03: add netfilter git to MAINTAINERS

[Patrick McHardy]

commit 3f1f7cf08ddf10ef7fbf06d881582c95b9747f4e
Author: Joe Perches <joe@perches.com>
Date:   Wed Jul 1 11:32:10 2009 +0200

    netfilter: add netfilter git to MAINTAINERS
    
    Signed-off-by: Joe Perches <joe@perches.com>
    Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/MAINTAINERS b/MAINTAINERS
index fa2a16d..a5042de 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4044,6 +4044,7 @@ L:	netfilter@vger.kernel.org
 L:	coreteam@netfilter.org
 W:	http://www.netfilter.org/
 W:	http://www.iptables.org/
+T:	git://git.kernel.org/pub/scm/linux/kernel/git/kaber/nf-2.6.git
 S:	Supported
 F:	include/linux/netfilter*
 F:	include/linux/netfilter/

netfilter 02/03: xt_osf: fix nf_log_packet() arguments

[Patrick McHardy]

commit aa6a03eb0ae859c1371555ef381de4c96ca1e4e6
Author: Patrick McHardy <kaber@trash.net>
Date:   Thu Jul 16 14:01:54 2009 +0200

    netfilter: xt_osf: fix nf_log_packet() arguments
    
    The first argument is the address family, the second one the hook
    number.
    
    Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/net/netfilter/xt_osf.c b/net/netfilter/xt_osf.c
index 863e409..0f482e2 100644
--- a/net/netfilter/xt_osf.c
+++ b/net/netfilter/xt_osf.c
@@ -330,7 +330,8 @@ static bool xt_osf_match_packet(const struct sk_buff *skb,
 			fcount++;
 
 			if (info->flags & XT_OSF_LOG)
-				nf_log_packet(p->hooknum, 0, skb, p->in, p->out, NULL,
+				nf_log_packet(p->family, p->hooknum, skb,
+					p->in, p->out, NULL,
 					"%s [%s:%s] : %pi4:%d -> %pi4:%d hops=%d\n",
 					f->genre, f->version, f->subtype,
 					&ip->saddr, ntohs(tcp->source),
@@ -345,7 +346,7 @@ static bool xt_osf_match_packet(const struct sk_buff *skb,
 	rcu_read_unlock();
 
 	if (!fcount && (info->flags & XT_OSF_LOG))
-		nf_log_packet(p->hooknum, 0, skb, p->in, p->out, NULL,
+		nf_log_packet(p->family, p->hooknum, skb, p->in, p->out, NULL,
 			"Remote OS is not known: %pi4:%u -> %pi4:%u\n",
 				&ip->saddr, ntohs(tcp->source),
 				&ip->daddr, ntohs(tcp->dest));

netfilter 03/03: nf_conntrack: nf_conntrack_alloc() fixes

[Patrick McHardy]

commit 941297f443f871b8c3372feccf27a8733f6ce9e9
Author: Eric Dumazet <eric.dumazet@gmail.com>
Date:   Thu Jul 16 14:03:40 2009 +0200

    netfilter: nf_conntrack: nf_conntrack_alloc() fixes
    
    When a slab cache uses SLAB_DESTROY_BY_RCU, we must be careful when allocating
    objects, since slab allocator could give a freed object still used by lockless
    readers.
    
    In particular, nf_conntrack RCU lookups rely on ct->tuplehash[xxx].hnnode.next
    being always valid (ie containing a valid 'nulls' value, or a valid pointer to next
    object in hash chain.)
    
    kmem_cache_zalloc() setups object with NULL values, but a NULL value is not valid
    for ct->tuplehash[xxx].hnnode.next.
    
    Fix is to call kmem_cache_alloc() and do the zeroing ourself.
    
    As spotted by Patrick, we also need to make sure lookup keys are committed to
    memory before setting refcount to 1, or a lockless reader could get a reference
    on the old version of the object. Its key re-check could then pass the barrier.
    
    Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
    Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/Documentation/RCU/rculist_nulls.txt b/Documentation/RCU/rculist_nulls.txt
index 93cb28d..18f9651 100644
--- a/Documentation/RCU/rculist_nulls.txt
+++ b/Documentation/RCU/rculist_nulls.txt
@@ -83,11 +83,12 @@ not detect it missed following items in original chain.
 obj = kmem_cache_alloc(...);
 lock_chain(); // typically a spin_lock()
 obj->key = key;
-atomic_inc(&obj->refcnt);
 /*
  * we need to make sure obj->key is updated before obj->next
+ * or obj->refcnt
  */
 smp_wmb();
+atomic_set(&obj->refcnt, 1);
 hlist_add_head_rcu(&obj->obj_node, list);
 unlock_chain(); // typically a spin_unlock()
 
@@ -159,6 +160,10 @@ out:
 obj = kmem_cache_alloc(cachep);
 lock_chain(); // typically a spin_lock()
 obj->key = key;
+/*
+ * changes to obj->key must be visible before refcnt one
+ */
+smp_wmb();
 atomic_set(&obj->refcnt, 1);
 /*
  * insert obj in RCU way (readers might be traversing chain)
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 7508f11..b5869b9 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -561,23 +561,38 @@ struct nf_conn *nf_conntrack_alloc(struct net *net,
 		}
 	}
 
-	ct = kmem_cache_zalloc(nf_conntrack_cachep, gfp);
+	/*
+	 * Do not use kmem_cache_zalloc(), as this cache uses
+	 * SLAB_DESTROY_BY_RCU.
+	 */
+	ct = kmem_cache_alloc(nf_conntrack_cachep, gfp);
 	if (ct == NULL) {
 		pr_debug("nf_conntrack_alloc: Can't alloc conntrack.\n");
 		atomic_dec(&net->ct.count);
 		return ERR_PTR(-ENOMEM);
 	}
-
+	/*
+	 * Let ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode.next
+	 * and ct->tuplehash[IP_CT_DIR_REPLY].hnnode.next unchanged.
+	 */
+	memset(&ct->tuplehash[IP_CT_DIR_MAX], 0,
+	       sizeof(*ct) - offsetof(struct nf_conn, tuplehash[IP_CT_DIR_MAX]));
 	spin_lock_init(&ct->lock);
-	atomic_set(&ct->ct_general.use, 1);
 	ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig;
+	ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode.pprev = NULL;
 	ct->tuplehash[IP_CT_DIR_REPLY].tuple = *repl;
+	ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev = NULL;
 	/* Don't set timer yet: wait for confirmation */
 	setup_timer(&ct->timeout, death_by_timeout, (unsigned long)ct);
 #ifdef CONFIG_NET_NS
 	ct->ct_net = net;
 #endif
 
+	/*
+	 * changes to lookup keys must be done before setting refcnt to 1
+	 */
+	smp_wmb();
+	atomic_set(&ct->ct_general.use, 1);
 	return ct;
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_alloc);

Re: netfilter 00/03: netfilter fixes

[David Miller]

From: Patrick McHardy <kaber@trash.net>
Date: Thu, 16 Jul 2009 14:26:44 +0200 (MEST)

> following are two netfilter fixes for 2.6.31 and a MAINTAINERS update:
> 
> - a fix for the nf_conntrack_alloc() race from Eric
> - a fix for incorrect invocation of nf_log_packet() in the new osf match
> - a patch to add my netfilter git tree to MAINTAINERS
> 
> Please apply or pull from:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/kaber/nf-2.6.git master

Pulled, thanks a lot Patrick!