pull request (net): ipsec 2016-05-04

pull request (net): ipsec 2016-05-04

[Steffen Klassert]

1) The flowcache can hit an OOM condition if too
   many entries are in the gc_list. Fix this by
   counting the entries in the gc_list and refuse
   new allocations if the value is too high.

2) The inner headers are invalid after a xfrm transformation,
   so reset the skb encapsulation field to ensure nobody tries
   access the inner headers. Otherwise tunnel devices stacked
   on top of xfrm may build the outer headers based on wrong
   informations.

3) Add pmtu handling to vti, we need it to report
   pmtu informations for local generated packets.

Please pull or let me know if there are problems.

Thanks!

The following changes since commit aac8d3c282e024c344c5b86dc1eab7af88bb9716:

  qmi_wwan: add "4G LTE usb-modem U901" (2016-02-16 20:39:32 -0500)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec.git master

for you to fetch changes up to d6af1a31cc72fbd558c7eddbc36f61bf09d1cf6a:

  vti: Add pmtu handling to vti_xmit. (2016-03-31 08:59:56 +0200)

----------------------------------------------------------------
Steffen Klassert (3):
      flowcache: Avoid OOM condition under preasure
      xfrm: Reset encapsulation field of the skb before transformation
      vti: Add pmtu handling to vti_xmit.

 include/net/netns/xfrm.h |  1 +
 net/core/flow.c          | 14 +++++++++++++-
 net/ipv4/ip_vti.c        | 18 ++++++++++++++++++
 net/xfrm/xfrm_output.c   |  3 +++
 4 files changed, 35 insertions(+), 1 deletion(-)

[PATCH 1/3] flowcache: Avoid OOM condition under preasure

[Steffen Klassert]

We can hit an OOM condition if we are under presure because
we can not free the entries in gc_list fast enough. So add
a counter for the not yet freed entries in the gc_list and
refuse new allocations if the value is too high.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 include/net/netns/xfrm.h |  1 +
 net/core/flow.c          | 14 +++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index 730d82a..24cd394 100644
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -80,6 +80,7 @@ struct netns_xfrm {
 	struct flow_cache	flow_cache_global;
 	atomic_t		flow_cache_genid;
 	struct list_head	flow_cache_gc_list;
+	atomic_t		flow_cache_gc_count;
 	spinlock_t		flow_cache_gc_lock;
 	struct work_struct	flow_cache_gc_work;
 	struct work_struct	flow_cache_flush_work;
diff --git a/net/core/flow.c b/net/core/flow.c
index 1033725..3937b1b 100644
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -92,8 +92,11 @@ static void flow_cache_gc_task(struct work_struct *work)
 	list_splice_tail_init(&xfrm->flow_cache_gc_list, &gc_list);
 	spin_unlock_bh(&xfrm->flow_cache_gc_lock);
 
-	list_for_each_entry_safe(fce, n, &gc_list, u.gc_list)
+	list_for_each_entry_safe(fce, n, &gc_list, u.gc_list) {
 		flow_entry_kill(fce, xfrm);
+		atomic_dec(&xfrm->flow_cache_gc_count);
+		WARN_ON(atomic_read(&xfrm->flow_cache_gc_count) < 0);
+	}
 }
 
 static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp,
@@ -101,6 +104,7 @@ static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp,
 				     struct netns_xfrm *xfrm)
 {
 	if (deleted) {
+		atomic_add(deleted, &xfrm->flow_cache_gc_count);
 		fcp->hash_count -= deleted;
 		spin_lock_bh(&xfrm->flow_cache_gc_lock);
 		list_splice_tail(gc_list, &xfrm->flow_cache_gc_list);
@@ -232,6 +236,13 @@ flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
 		if (fcp->hash_count > fc->high_watermark)
 			flow_cache_shrink(fc, fcp);
 
+		if (fcp->hash_count > 2 * fc->high_watermark ||
+		    atomic_read(&net->xfrm.flow_cache_gc_count) > fc->high_watermark) {
+			atomic_inc(&net->xfrm.flow_cache_genid);
+			flo = ERR_PTR(-ENOBUFS);
+			goto ret_object;
+		}
+
 		fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
 		if (fle) {
 			fle->net = net;
@@ -446,6 +457,7 @@ int flow_cache_init(struct net *net)
 	INIT_WORK(&net->xfrm.flow_cache_gc_work, flow_cache_gc_task);
 	INIT_WORK(&net->xfrm.flow_cache_flush_work, flow_cache_flush_task);
 	mutex_init(&net->xfrm.flow_flush_sem);
+	atomic_set(&net->xfrm.flow_cache_gc_count, 0);
 
 	fc->hash_shift = 10;
 	fc->low_watermark = 2 * flow_cache_hash_size(fc);
-- 
1.9.1

[PATCH 2/3] xfrm: Reset encapsulation field of the skb before transformation

[Steffen Klassert]

The inner headers are invalid after a xfrm transformation.
So reset the skb encapsulation field to ensure nobody tries
to access the inner headers.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/xfrm/xfrm_output.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index ff4a91f..637387b 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -99,6 +99,9 @@ static int xfrm_output_one(struct sk_buff *skb, int err)
 
 		skb_dst_force(skb);
 
+		/* Inner headers are invalid now. */
+		skb->encapsulation = 0;
+
 		err = x->type->output(x, skb);
 		if (err == -EINPROGRESS)
 			goto out;
-- 
1.9.1

[PATCH 3/3] vti: Add pmtu handling to vti_xmit.

[Steffen Klassert]

We currently rely on the PMTU discovery of xfrm.
However if a packet is locally sent, the PMTU mechanism
of xfrm tries to do local socket notification what
might not work for applications like ping that don't
check for this. So add pmtu handling to vti_xmit to
report MTU changes immediately.

Reported-by: Mark McKinstry <Mark.McKinstry@alliedtelesis.co.nz>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/ipv4/ip_vti.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index 5cf10b7..a917903 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -156,6 +156,7 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
 	struct dst_entry *dst = skb_dst(skb);
 	struct net_device *tdev;	/* Device to other host */
 	int err;
+	int mtu;
 
 	if (!dst) {
 		dev->stats.tx_carrier_errors++;
@@ -192,6 +193,23 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
 			tunnel->err_count = 0;
 	}
 
+	mtu = dst_mtu(dst);
+	if (skb->len > mtu) {
+		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
+		if (skb->protocol == htons(ETH_P_IP)) {
+			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
+				  htonl(mtu));
+		} else {
+			if (mtu < IPV6_MIN_MTU)
+				mtu = IPV6_MIN_MTU;
+
+			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
+		}
+
+		dst_release(dst);
+		goto tx_error;
+	}
+
 	skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(dev)));
 	skb_dst_set(skb, dst);
 	skb->dev = skb_dst(skb)->dev;
-- 
1.9.1

Re: pull request (net): ipsec 2016-05-04

[David Miller]

From: Steffen Klassert <steffen.klassert@secunet.com>
Date: Wed, 4 May 2016 07:40:51 +0200

> 1) The flowcache can hit an OOM condition if too
>    many entries are in the gc_list. Fix this by
>    counting the entries in the gc_list and refuse
>    new allocations if the value is too high.
> 
> 2) The inner headers are invalid after a xfrm transformation,
>    so reset the skb encapsulation field to ensure nobody tries
>    access the inner headers. Otherwise tunnel devices stacked
>    on top of xfrm may build the outer headers based on wrong
>    informations.
> 
> 3) Add pmtu handling to vti, we need it to report
>    pmtu informations for local generated packets.
> 
> Please pull or let me know if there are problems.

Pulled, thanks Steffen.

While build testing this I was worried that it might be possible
to create a situation where IP_VTI=y yet IPV6=m and therefore have
a unresolvable reference to icmpv6_send().

However I was not able to create such a configuration, as hard as
I tried. :-)