| Message ID | 1475765230-11936-1-git-send-email-paul.durrant@citrix.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Paul Durrant <paul.durrant@citrix.com> Date: Thu, 6 Oct 2016 15:47:10 +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 isunable to handle extra_info segments being given > such a segment, causing it to crash. > > This patch fixes the problem by gating whether the extra_info is sent > not only on the presence of a s/w hash, but also on whether the hash > algorithm has been configured. > > Signed-off-by: Paul Durrant <paul.durrant@citrix.com> > Cc: Wei Liu <wei.liu2@citrix.com> This doesn't apply cleanly to the current 'net' tree, please respin. Thanks.
> -----Original Message----- > From: David Miller [mailto:davem@davemloft.net] > Sent: 07 October 2016 06:38 > To: Paul Durrant <Paul.Durrant@citrix.com> > Cc: netdev@vger.kernel.org; xen-devel@lists.xenproject.org; Wei Liu > <wei.liu2@citrix.com> > Subject: Re: [PATCH net] xen-netback: make sure that hashes are not send > to unaware frontends > > From: Paul Durrant <paul.durrant@citrix.com> > Date: Thu, 6 Oct 2016 15:47:10 +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 isunable to handle extra_info segments being > > given such a segment, causing it to crash. > > > > This patch fixes the problem by gating whether the extra_info is sent > > not only on the presence of a s/w hash, but also on whether the hash > > algorithm has been configured. > > > > Signed-off-by: Paul Durrant <paul.durrant@citrix.com> > > Cc: Wei Liu <wei.liu2@citrix.com> > > This doesn't apply cleanly to the current 'net' tree, please respin. > Sure. V2 coming. Paul > Thanks.
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index fb50c6d..1034139 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); diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 3d0c989..2cd4a8e 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -168,6 +168,10 @@ static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue) needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE); if (skb_is_gso(skb)) needed++; + /* Assume the frontend is capable of handling the hash + * extra_info at this point. This will only ever lead to an + * accurate value or over-estimation. + */ if (skb->sw_hash) needed++; @@ -378,9 +382,8 @@ static void xenvif_gop_frag_copy(struct xenvif_queue *queue, struct sk_buff *skb .npo = npo, .head = *head, .gso_type = XEN_NETIF_GSO_TYPE_NONE, - /* xenvif_set_skb_hash() will have either set a s/w - * hash or cleared the hash depending on - * whether the the frontend wants a hash for this skb. + /* xenvif_rx_action() will have cleared any hash if + * the frontend is not capable of handling it. */ .hash_present = skb->sw_hash, }; @@ -593,6 +596,14 @@ static void xenvif_rx_action(struct xenvif_queue *queue) && (skb = xenvif_rx_dequeue(queue)) != NULL) { queue->last_rx_time = jiffies; + /* If there is no hash algorithm configured 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_CB(skb)->meta_slots_used = xenvif_gop_skb(skb, &npo, queue); __skb_queue_tail(&rxq, skb); @@ -667,12 +678,6 @@ static void xenvif_rx_action(struct xenvif_queue *queue) } if (skb->sw_hash) { - /* Since the skb got here via xenvif_select_queue() - * we know that the hash has been re-calculated - * according to a configuration set by the frontend - * and therefore we know that it is legitimate to - * pass it to the frontend. - */ if (resp->flags & XEN_NETRXF_extra_info) extra->flags |= XEN_NETIF_EXTRA_FLAG_MORE; else
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 isunable to handle extra_info segments being given such a segment, causing it to crash. This patch fixes the problem by gating whether the extra_info is sent not only on the presence of a s/w hash, but also on whether the hash algorithm has been configured. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Cc: Wei Liu <wei.liu2@citrix.com> --- drivers/net/xen-netback/interface.c | 13 ++----------- drivers/net/xen-netback/netback.c | 23 ++++++++++++++--------- 2 files changed, 16 insertions(+), 20 deletions(-)