* [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends
@ 2016-10-07 8:32 Paul Durrant
2016-10-07 8:54 ` FW: " Paul Durrant
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Paul Durrant @ 2016-10-07 8:32 UTC (permalink / raw
To: netdev, xen-devl; +Cc: Paul Durrant, Wei Liu
In the case when a frontend only negotiates a single queue with xen-
netback it is possible for a skbuff with a s/w hash to result in a
hash extra_info segment being sent to the frontend even when no hash
algorithm has been configured. (The ndo_select_queue() entry point makes
sure the hash is not set if no algorithm is configured, but this entry
point is not called when there is only a single queue). This can result
in a frontend that is unable to handle extra_info segments being given
such a segment, causing it to crash.
This patch fixes the problem by clearing the hash in ndo_start_xmit()
instead, which is clearly guaranteed to be called irrespective of the
number of queues.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
---
v2:
- Simplified and re-based onto re-factored net branch
---
drivers/net/xen-netback/interface.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 4af532a..74dc2bf 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -149,17 +149,8 @@ static u16 xenvif_select_queue(struct net_device *dev, struct sk_buff *skb,
struct xenvif *vif = netdev_priv(dev);
unsigned int size = vif->hash.size;
- if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) {
- u16 index = fallback(dev, skb) % dev->real_num_tx_queues;
-
- /* Make sure there is no hash information in the socket
- * buffer otherwise it would be incorrectly forwarded
- * to the frontend.
- */
- skb_clear_hash(skb);
-
- return index;
- }
+ if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
+ return fallback(dev, skb) % dev->real_num_tx_queues;
xenvif_set_skb_hash(vif, skb);
@@ -208,6 +199,13 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
cb = XENVIF_RX_CB(skb);
cb->expires = jiffies + vif->drain_timeout;
+ /* If there is no hash algorithm configured then make sure there
+ * is no hash information in the socket buffer otherwise it
+ * would be incorrectly forwarded to the frontend.
+ */
+ if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
+ skb_clear_hash(skb);
+
xenvif_rx_queue_tail(queue, skb);
xenvif_kick_thread(queue);
--
2.1.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* FW: [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends
2016-10-07 8:32 [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends Paul Durrant
@ 2016-10-07 8:54 ` Paul Durrant
2016-10-07 9:07 ` Wei Liu
2016-10-08 3:53 ` David Miller
2 siblings, 0 replies; 4+ messages in thread
From: Paul Durrant @ 2016-10-07 8:54 UTC (permalink / raw
To: xen-devel (xen-devel@lists.xenproject.org)
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Sorry, I fat-fingered the address in the get send-email...
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From: Paul Durrant <Paul.Durrant@citrix.com>
To: "netdev@vger.kernel.org" <netdev@vger.kernel.org>, "xen-devl@lists.xenproject.org" <xen-devl@lists.xenproject.org>
Cc: Paul Durrant <Paul.Durrant@citrix.com>, Wei Liu <wei.liu2@citrix.com>
Subject: [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends
Date: Fri, 7 Oct 2016 08:32:31 +0000
Message-ID: <1475829151-3707-1-git-send-email-paul.durrant@citrix.com>
In the case when a frontend only negotiates a single queue with xen-
netback it is possible for a skbuff with a s/w hash to result in a
hash extra_info segment being sent to the frontend even when no hash
algorithm has been configured. (The ndo_select_queue() entry point makes
sure the hash is not set if no algorithm is configured, but this entry
point is not called when there is only a single queue). This can result
in a frontend that is unable to handle extra_info segments being given
such a segment, causing it to crash.
This patch fixes the problem by clearing the hash in ndo_start_xmit()
instead, which is clearly guaranteed to be called irrespective of the
number of queues.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
---
v2:
- Simplified and re-based onto re-factored net branch
---
drivers/net/xen-netback/interface.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 4af532a..74dc2bf 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -149,17 +149,8 @@ static u16 xenvif_select_queue(struct net_device *dev, struct sk_buff *skb,
struct xenvif *vif = netdev_priv(dev);
unsigned int size = vif->hash.size;
- if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) {
- u16 index = fallback(dev, skb) % dev->real_num_tx_queues;
-
- /* Make sure there is no hash information in the socket
- * buffer otherwise it would be incorrectly forwarded
- * to the frontend.
- */
- skb_clear_hash(skb);
-
- return index;
- }
+ if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
+ return fallback(dev, skb) % dev->real_num_tx_queues;
xenvif_set_skb_hash(vif, skb);
@@ -208,6 +199,13 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
cb = XENVIF_RX_CB(skb);
cb->expires = jiffies + vif->drain_timeout;
+ /* If there is no hash algorithm configured then make sure there
+ * is no hash information in the socket buffer otherwise it
+ * would be incorrectly forwarded to the frontend.
+ */
+ if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
+ skb_clear_hash(skb);
+
xenvif_rx_queue_tail(queue, skb);
xenvif_kick_thread(queue);
--
2.1.4
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends
2016-10-07 8:32 [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends Paul Durrant
2016-10-07 8:54 ` FW: " Paul Durrant
@ 2016-10-07 9:07 ` Wei Liu
2016-10-08 3:53 ` David Miller
2 siblings, 0 replies; 4+ messages in thread
From: Wei Liu @ 2016-10-07 9:07 UTC (permalink / raw
To: Paul Durrant; +Cc: netdev, xen-devl, Wei Liu
On Fri, Oct 07, 2016 at 09:32:31AM +0100, Paul Durrant wrote:
> In the case when a frontend only negotiates a single queue with xen-
> netback it is possible for a skbuff with a s/w hash to result in a
> hash extra_info segment being sent to the frontend even when no hash
> algorithm has been configured. (The ndo_select_queue() entry point makes
> sure the hash is not set if no algorithm is configured, but this entry
> point is not called when there is only a single queue). This can result
> in a frontend that is unable to handle extra_info segments being given
> such a segment, causing it to crash.
>
> This patch fixes the problem by clearing the hash in ndo_start_xmit()
> instead, which is clearly guaranteed to be called irrespective of the
> number of queues.
>
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
> ---
>
> v2:
> - Simplified and re-based onto re-factored net branch
> ---
> drivers/net/xen-netback/interface.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
> index 4af532a..74dc2bf 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -149,17 +149,8 @@ static u16 xenvif_select_queue(struct net_device *dev, struct sk_buff *skb,
> struct xenvif *vif = netdev_priv(dev);
> unsigned int size = vif->hash.size;
>
> - if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE) {
> - u16 index = fallback(dev, skb) % dev->real_num_tx_queues;
> -
> - /* Make sure there is no hash information in the socket
> - * buffer otherwise it would be incorrectly forwarded
> - * to the frontend.
> - */
> - skb_clear_hash(skb);
> -
> - return index;
> - }
> + if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
> + return fallback(dev, skb) % dev->real_num_tx_queues;
>
> xenvif_set_skb_hash(vif, skb);
>
> @@ -208,6 +199,13 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
> cb = XENVIF_RX_CB(skb);
> cb->expires = jiffies + vif->drain_timeout;
>
> + /* If there is no hash algorithm configured then make sure there
> + * is no hash information in the socket buffer otherwise it
> + * would be incorrectly forwarded to the frontend.
> + */
> + if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
> + skb_clear_hash(skb);
> +
> xenvif_rx_queue_tail(queue, skb);
> xenvif_kick_thread(queue);
>
> --
> 2.1.4
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends
2016-10-07 8:32 [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends Paul Durrant
2016-10-07 8:54 ` FW: " Paul Durrant
2016-10-07 9:07 ` Wei Liu
@ 2016-10-08 3:53 ` David Miller
2 siblings, 0 replies; 4+ messages in thread
From: David Miller @ 2016-10-08 3:53 UTC (permalink / raw
To: paul.durrant; +Cc: netdev, xen-devl, wei.liu2
From: Paul Durrant <paul.durrant@citrix.com>
Date: Fri, 7 Oct 2016 09:32:31 +0100
> In the case when a frontend only negotiates a single queue with xen-
> netback it is possible for a skbuff with a s/w hash to result in a
> hash extra_info segment being sent to the frontend even when no hash
> algorithm has been configured. (The ndo_select_queue() entry point makes
> sure the hash is not set if no algorithm is configured, but this entry
> point is not called when there is only a single queue). This can result
> in a frontend that is unable to handle extra_info segments being given
> such a segment, causing it to crash.
>
> This patch fixes the problem by clearing the hash in ndo_start_xmit()
> instead, which is clearly guaranteed to be called irrespective of the
> number of queues.
>
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Applied, thanks.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-10-07 8:32 [PATCH v2 net] xen-netback: make sure that hashes are not send to unaware frontends Paul Durrant
2016-10-07 8:54 ` FW: " Paul Durrant
2016-10-07 9:07 ` Wei Liu
2016-10-08 3:53 ` David Miller
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