[PATCH nf-next 1/2] netfilter: fix possible removal of wrong hook

[PATCH nf-next 1/2] netfilter: fix possible removal of wrong hook

[Pablo Neira Ayuso]

nf_unregister_net_hook() uses the nf_hook_ops fields as tuple to look up for
the corresponding hook in the list. However, we may have two hooks with exactly
the same configuration.

This shouldn't be a problem for nftables since every new chain has an unique
priv field set, but this may still cause us problems in the future, so better
address this problem now by keeping a reference to the original nf_hook_ops
structure to make sure we delete the right hook from nf_unregister_net_hook().

Fixes: 085db2c04557 ("netfilter: Per network namespace netfilter hooks.")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/core.c |   39 ++++++++++++++++++---------------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 87d237d..a834181 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -78,26 +78,27 @@ static struct list_head *find_nf_hook_list(struct net *net,
 	return nf_hook_list;
 }
 
+struct nf_hook_entry {
+	const struct nf_hook_ops	*orig_ops;
+	struct nf_hook_ops		ops;
+};
+
 int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
 {
 	struct list_head *nf_hook_list;
-	struct nf_hook_ops *elem, *new;
+	struct nf_hook_entry *entry;
+	struct nf_hook_ops *elem;
 
-	new = kzalloc(sizeof(*new), GFP_KERNEL);
-	if (!new)
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
 		return -ENOMEM;
 
-	new->hook     = reg->hook;
-	new->dev      = reg->dev;
-	new->owner    = reg->owner;
-	new->priv     = reg->priv;
-	new->pf       = reg->pf;
-	new->hooknum  = reg->hooknum;
-	new->priority = reg->priority;
+	entry->orig_ops	= reg;
+	entry->ops	= *reg;
 
 	nf_hook_list = find_nf_hook_list(net, reg);
 	if (!nf_hook_list) {
-		kfree(new);
+		kfree(entry);
 		return -ENOENT;
 	}
 
@@ -106,7 +107,7 @@ int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
 		if (reg->priority < elem->priority)
 			break;
 	}
-	list_add_rcu(&new->list, elem->list.prev);
+	list_add_rcu(&entry->ops.list, elem->list.prev);
 	mutex_unlock(&nf_hook_mutex);
 #ifdef CONFIG_NETFILTER_INGRESS
 	if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
@@ -122,6 +123,7 @@ EXPORT_SYMBOL(nf_register_net_hook);
 void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
 {
 	struct list_head *nf_hook_list;
+	struct nf_hook_entry *entry;
 	struct nf_hook_ops *elem;
 
 	nf_hook_list = find_nf_hook_list(net, reg);
@@ -130,14 +132,9 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
 
 	mutex_lock(&nf_hook_mutex);
 	list_for_each_entry(elem, nf_hook_list, list) {
-		if ((reg->hook     == elem->hook) &&
-		    (reg->dev      == elem->dev) &&
-		    (reg->owner    == elem->owner) &&
-		    (reg->priv     == elem->priv) &&
-		    (reg->pf       == elem->pf) &&
-		    (reg->hooknum  == elem->hooknum) &&
-		    (reg->priority == elem->priority)) {
-			list_del_rcu(&elem->list);
+		entry = container_of(elem, struct nf_hook_entry, ops);
+		if (entry->orig_ops == reg) {
+			list_del_rcu(&entry->ops.list);
 			break;
 		}
 	}
@@ -154,7 +151,7 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
 	static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
 #endif
 	synchronize_net();
-	nf_queue_nf_hook_drop(elem);
+	nf_queue_nf_hook_drop(&entry->ops);
 	kfree(elem);
 }
 EXPORT_SYMBOL(nf_unregister_net_hook);
-- 
1.7.10.4

[PATCH nf-next 2/2] netfilter: rename local nf_hook_list to hook_list

[Pablo Neira Ayuso]

085db2c04557 ("netfilter: Per network namespace netfilter hooks.") introduced a
new nf_hook_list that is global, so let's avoid this overlap.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/linux/netfilter.h |   14 +++++++-------
 net/netfilter/core.c      |   28 ++++++++++++++--------------
 2 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index e01da73..d788ce6 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -140,20 +140,20 @@ void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 #ifdef HAVE_JUMP_LABEL
 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 
-static inline bool nf_hook_list_active(struct list_head *nf_hook_list,
+static inline bool nf_hook_list_active(struct list_head *hook_list,
 				       u_int8_t pf, unsigned int hook)
 {
 	if (__builtin_constant_p(pf) &&
 	    __builtin_constant_p(hook))
 		return static_key_false(&nf_hooks_needed[pf][hook]);
 
-	return !list_empty(nf_hook_list);
+	return !list_empty(hook_list);
 }
 #else
-static inline bool nf_hook_list_active(struct list_head *nf_hook_list,
+static inline bool nf_hook_list_active(struct list_head *hook_list,
 				       u_int8_t pf, unsigned int hook)
 {
-	return !list_empty(nf_hook_list);
+	return !list_empty(hook_list);
 }
 #endif
 
@@ -175,12 +175,12 @@ static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 				 int thresh)
 {
 	struct net *net = dev_net(indev ? indev : outdev);
-	struct list_head *nf_hook_list = &net->nf.hooks[pf][hook];
+	struct list_head *hook_list = &net->nf.hooks[pf][hook];
 
-	if (nf_hook_list_active(nf_hook_list, pf, hook)) {
+	if (nf_hook_list_active(hook_list, pf, hook)) {
 		struct nf_hook_state state;
 
-		nf_hook_state_init(&state, nf_hook_list, hook, thresh,
+		nf_hook_state_init(&state, hook_list, hook, thresh,
 				   pf, indev, outdev, sk, okfn);
 		return nf_hook_slow(skb, &state);
 	}
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index a834181..041f3a8 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -62,20 +62,20 @@ EXPORT_SYMBOL(nf_hooks_needed);
 
 static DEFINE_MUTEX(nf_hook_mutex);
 
-static struct list_head *find_nf_hook_list(struct net *net,
+static struct list_head *nf_find_hook_list(struct net *net,
 					   const struct nf_hook_ops *reg)
 {
-	struct list_head *nf_hook_list = NULL;
+	struct list_head *hook_list = NULL;
 
 	if (reg->pf != NFPROTO_NETDEV)
-		nf_hook_list = &net->nf.hooks[reg->pf][reg->hooknum];
+		hook_list = &net->nf.hooks[reg->pf][reg->hooknum];
 	else if (reg->hooknum == NF_NETDEV_INGRESS) {
 #ifdef CONFIG_NETFILTER_INGRESS
 		if (reg->dev && dev_net(reg->dev) == net)
-			nf_hook_list = &reg->dev->nf_hooks_ingress;
+			hook_list = &reg->dev->nf_hooks_ingress;
 #endif
 	}
-	return nf_hook_list;
+	return hook_list;
 }
 
 struct nf_hook_entry {
@@ -85,7 +85,7 @@ struct nf_hook_entry {
 
 int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
 {
-	struct list_head *nf_hook_list;
+	struct list_head *hook_list;
 	struct nf_hook_entry *entry;
 	struct nf_hook_ops *elem;
 
@@ -96,14 +96,14 @@ int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
 	entry->orig_ops	= reg;
 	entry->ops	= *reg;
 
-	nf_hook_list = find_nf_hook_list(net, reg);
-	if (!nf_hook_list) {
+	hook_list = nf_find_hook_list(net, reg);
+	if (!hook_list) {
 		kfree(entry);
 		return -ENOENT;
 	}
 
 	mutex_lock(&nf_hook_mutex);
-	list_for_each_entry(elem, nf_hook_list, list) {
+	list_for_each_entry(elem, hook_list, list) {
 		if (reg->priority < elem->priority)
 			break;
 	}
@@ -122,16 +122,16 @@ EXPORT_SYMBOL(nf_register_net_hook);
 
 void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
 {
-	struct list_head *nf_hook_list;
+	struct list_head *hook_list;
 	struct nf_hook_entry *entry;
 	struct nf_hook_ops *elem;
 
-	nf_hook_list = find_nf_hook_list(net, reg);
-	if (!nf_hook_list)
+	hook_list = nf_find_hook_list(net, reg);
+	if (!hook_list)
 		return;
 
 	mutex_lock(&nf_hook_mutex);
-	list_for_each_entry(elem, nf_hook_list, list) {
+	list_for_each_entry(elem, hook_list, list) {
 		entry = container_of(elem, struct nf_hook_entry, ops);
 		if (entry->orig_ops == reg) {
 			list_del_rcu(&entry->ops.list);
@@ -139,7 +139,7 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
 		}
 	}
 	mutex_unlock(&nf_hook_mutex);
-	if (&elem->list == nf_hook_list) {
+	if (&elem->list == hook_list) {
 		WARN(1, "nf_unregister_net_hook: hook not found!\n");
 		return;
 	}
-- 
1.7.10.4

Re: [PATCH nf-next 2/2] netfilter: rename local nf_hook_list to hook_list

[Eric W. Biederman]

Pablo Neira Ayuso <pablo@netfilter.org> writes:

> 085db2c04557 ("netfilter: Per network namespace netfilter hooks.") introduced a
> new nf_hook_list that is global, so let's avoid this overlap.

Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>

>
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
>  include/linux/netfilter.h |   14 +++++++-------
>  net/netfilter/core.c      |   28 ++++++++++++++--------------
>  2 files changed, 21 insertions(+), 21 deletions(-)
>
> diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
> index e01da73..d788ce6 100644
> --- a/include/linux/netfilter.h
> +++ b/include/linux/netfilter.h
> @@ -140,20 +140,20 @@ void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
>  #ifdef HAVE_JUMP_LABEL
>  extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
>  
> -static inline bool nf_hook_list_active(struct list_head *nf_hook_list,
> +static inline bool nf_hook_list_active(struct list_head *hook_list,
>  				       u_int8_t pf, unsigned int hook)
>  {
>  	if (__builtin_constant_p(pf) &&
>  	    __builtin_constant_p(hook))
>  		return static_key_false(&nf_hooks_needed[pf][hook]);
>  
> -	return !list_empty(nf_hook_list);
> +	return !list_empty(hook_list);
>  }
>  #else
> -static inline bool nf_hook_list_active(struct list_head *nf_hook_list,
> +static inline bool nf_hook_list_active(struct list_head *hook_list,
>  				       u_int8_t pf, unsigned int hook)
>  {
> -	return !list_empty(nf_hook_list);
> +	return !list_empty(hook_list);
>  }
>  #endif
>  
> @@ -175,12 +175,12 @@ static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
>  				 int thresh)
>  {
>  	struct net *net = dev_net(indev ? indev : outdev);
> -	struct list_head *nf_hook_list = &net->nf.hooks[pf][hook];
> +	struct list_head *hook_list = &net->nf.hooks[pf][hook];
>  
> -	if (nf_hook_list_active(nf_hook_list, pf, hook)) {
> +	if (nf_hook_list_active(hook_list, pf, hook)) {
>  		struct nf_hook_state state;
>  
> -		nf_hook_state_init(&state, nf_hook_list, hook, thresh,
> +		nf_hook_state_init(&state, hook_list, hook, thresh,
>  				   pf, indev, outdev, sk, okfn);
>  		return nf_hook_slow(skb, &state);
>  	}
> diff --git a/net/netfilter/core.c b/net/netfilter/core.c
> index a834181..041f3a8 100644
> --- a/net/netfilter/core.c
> +++ b/net/netfilter/core.c
> @@ -62,20 +62,20 @@ EXPORT_SYMBOL(nf_hooks_needed);
>  
>  static DEFINE_MUTEX(nf_hook_mutex);
>  
> -static struct list_head *find_nf_hook_list(struct net *net,
> +static struct list_head *nf_find_hook_list(struct net *net,
>  					   const struct nf_hook_ops *reg)
>  {
> -	struct list_head *nf_hook_list = NULL;
> +	struct list_head *hook_list = NULL;
>  
>  	if (reg->pf != NFPROTO_NETDEV)
> -		nf_hook_list = &net->nf.hooks[reg->pf][reg->hooknum];
> +		hook_list = &net->nf.hooks[reg->pf][reg->hooknum];
>  	else if (reg->hooknum == NF_NETDEV_INGRESS) {
>  #ifdef CONFIG_NETFILTER_INGRESS
>  		if (reg->dev && dev_net(reg->dev) == net)
> -			nf_hook_list = &reg->dev->nf_hooks_ingress;
> +			hook_list = &reg->dev->nf_hooks_ingress;
>  #endif
>  	}
> -	return nf_hook_list;
> +	return hook_list;
>  }
>  
>  struct nf_hook_entry {
> @@ -85,7 +85,7 @@ struct nf_hook_entry {
>  
>  int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
>  {
> -	struct list_head *nf_hook_list;
> +	struct list_head *hook_list;
>  	struct nf_hook_entry *entry;
>  	struct nf_hook_ops *elem;
>  
> @@ -96,14 +96,14 @@ int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
>  	entry->orig_ops	= reg;
>  	entry->ops	= *reg;
>  
> -	nf_hook_list = find_nf_hook_list(net, reg);
> -	if (!nf_hook_list) {
> +	hook_list = nf_find_hook_list(net, reg);
> +	if (!hook_list) {
>  		kfree(entry);
>  		return -ENOENT;
>  	}
>  
>  	mutex_lock(&nf_hook_mutex);
> -	list_for_each_entry(elem, nf_hook_list, list) {
> +	list_for_each_entry(elem, hook_list, list) {
>  		if (reg->priority < elem->priority)
>  			break;
>  	}
> @@ -122,16 +122,16 @@ EXPORT_SYMBOL(nf_register_net_hook);
>  
>  void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
>  {
> -	struct list_head *nf_hook_list;
> +	struct list_head *hook_list;
>  	struct nf_hook_entry *entry;
>  	struct nf_hook_ops *elem;
>  
> -	nf_hook_list = find_nf_hook_list(net, reg);
> -	if (!nf_hook_list)
> +	hook_list = nf_find_hook_list(net, reg);
> +	if (!hook_list)
>  		return;
>  
>  	mutex_lock(&nf_hook_mutex);
> -	list_for_each_entry(elem, nf_hook_list, list) {
> +	list_for_each_entry(elem, hook_list, list) {
>  		entry = container_of(elem, struct nf_hook_entry, ops);
>  		if (entry->orig_ops == reg) {
>  			list_del_rcu(&entry->ops.list);
> @@ -139,7 +139,7 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
>  		}
>  	}
>  	mutex_unlock(&nf_hook_mutex);
> -	if (&elem->list == nf_hook_list) {
> +	if (&elem->list == hook_list) {
>  		WARN(1, "nf_unregister_net_hook: hook not found!\n");
>  		return;
>  	}

Re: [PATCH nf-next 1/2] netfilter: fix possible removal of wrong hook

[Eric W. Biederman]

Pablo Neira Ayuso <pablo@netfilter.org> writes:

> nf_unregister_net_hook() uses the nf_hook_ops fields as tuple to look up for
> the corresponding hook in the list. However, we may have two hooks with exactly
> the same configuration.
>
> This shouldn't be a problem for nftables since every new chain has an unique
> priv field set, but this may still cause us problems in the future, so better
> address this problem now by keeping a reference to the original nf_hook_ops
> structure to make sure we delete the right hook from
> nf_unregister_net_hook().

Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>

> Fixes: 085db2c04557 ("netfilter: Per network namespace netfilter hooks.")
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
>  net/netfilter/core.c |   39 ++++++++++++++++++---------------------
>  1 file changed, 18 insertions(+), 21 deletions(-)
>
> diff --git a/net/netfilter/core.c b/net/netfilter/core.c
> index 87d237d..a834181 100644
> --- a/net/netfilter/core.c
> +++ b/net/netfilter/core.c
> @@ -78,26 +78,27 @@ static struct list_head *find_nf_hook_list(struct net *net,
>  	return nf_hook_list;
>  }
>  
> +struct nf_hook_entry {
> +	const struct nf_hook_ops	*orig_ops;
> +	struct nf_hook_ops		ops;
> +};
> +
>  int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
>  {
>  	struct list_head *nf_hook_list;
> -	struct nf_hook_ops *elem, *new;
> +	struct nf_hook_entry *entry;
> +	struct nf_hook_ops *elem;
>  
> -	new = kzalloc(sizeof(*new), GFP_KERNEL);
> -	if (!new)
> +	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
> +	if (!entry)
>  		return -ENOMEM;
>  
> -	new->hook     = reg->hook;
> -	new->dev      = reg->dev;
> -	new->owner    = reg->owner;
> -	new->priv     = reg->priv;
> -	new->pf       = reg->pf;
> -	new->hooknum  = reg->hooknum;
> -	new->priority = reg->priority;
> +	entry->orig_ops	= reg;
> +	entry->ops	= *reg;
>  
>  	nf_hook_list = find_nf_hook_list(net, reg);
>  	if (!nf_hook_list) {
> -		kfree(new);
> +		kfree(entry);
>  		return -ENOENT;
>  	}
>  
> @@ -106,7 +107,7 @@ int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
>  		if (reg->priority < elem->priority)
>  			break;
>  	}
> -	list_add_rcu(&new->list, elem->list.prev);
> +	list_add_rcu(&entry->ops.list, elem->list.prev);
>  	mutex_unlock(&nf_hook_mutex);
>  #ifdef CONFIG_NETFILTER_INGRESS
>  	if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
> @@ -122,6 +123,7 @@ EXPORT_SYMBOL(nf_register_net_hook);
>  void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
>  {
>  	struct list_head *nf_hook_list;
> +	struct nf_hook_entry *entry;
>  	struct nf_hook_ops *elem;
>  
>  	nf_hook_list = find_nf_hook_list(net, reg);
> @@ -130,14 +132,9 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
>  
>  	mutex_lock(&nf_hook_mutex);
>  	list_for_each_entry(elem, nf_hook_list, list) {
> -		if ((reg->hook     == elem->hook) &&
> -		    (reg->dev      == elem->dev) &&
> -		    (reg->owner    == elem->owner) &&
> -		    (reg->priv     == elem->priv) &&
> -		    (reg->pf       == elem->pf) &&
> -		    (reg->hooknum  == elem->hooknum) &&
> -		    (reg->priority == elem->priority)) {
> -			list_del_rcu(&elem->list);
> +		entry = container_of(elem, struct nf_hook_entry, ops);
> +		if (entry->orig_ops == reg) {
> +			list_del_rcu(&entry->ops.list);
>  			break;
>  		}
>  	}
> @@ -154,7 +151,7 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
>  	static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
>  #endif
>  	synchronize_net();
> -	nf_queue_nf_hook_drop(elem);
> +	nf_queue_nf_hook_drop(&entry->ops);
>  	kfree(elem);
>  }
>  EXPORT_SYMBOL(nf_unregister_net_hook);