Merge branch 'xen-netback-hash'

Jan Beulich says:

====================
xen-netback: hash mapping handling adjustments

First and foremost the fix for XSA-270. On top of that further changes
which looked desirable to me while investigating that XSA.

1: fix input validation in xenvif_set_hash_mapping()
2: validate queue numbers in xenvif_set_hash_mapping()
3: handle page straddling in xenvif_set_hash_mapping()
====================

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 40 insertions, 17 deletions

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index a46a1e94505d..936c0b3e0ba2 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -241,8 +241,9 @@ struct xenvif_hash_cache {
 struct xenvif_hash {
 	unsigned int alg;
 	u32 flags;
+	bool mapping_sel;
 	u8 key[XEN_NETBK_MAX_HASH_KEY_SIZE];
-	u32 mapping[XEN_NETBK_MAX_HASH_MAPPING_SIZE];
+	u32 mapping[2][XEN_NETBK_MAX_HASH_MAPPING_SIZE];
 	unsigned int size;
 	struct xenvif_hash_cache cache;
 };
diff --git a/drivers/net/xen-netback/hash.c b/drivers/net/xen-netback/hash.c
index 3c4c58b9fe76..0ccb021f1e78 100644
--- a/drivers/net/xen-netback/hash.c
+++ b/drivers/net/xen-netback/hash.c
@@ -324,7 +324,8 @@ u32 xenvif_set_hash_mapping_size(struct xenvif *vif, u32 size)
 		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
 
 	vif->hash.size = size;
-	memset(vif->hash.mapping, 0, sizeof(u32) * size);
+	memset(vif->hash.mapping[vif->hash.mapping_sel], 0,
+	       sizeof(u32) * size);
 
 	return XEN_NETIF_CTRL_STATUS_SUCCESS;
 }
@@ -332,31 +333,49 @@ u32 xenvif_set_hash_mapping_size(struct xenvif *vif, u32 size)
 u32 xenvif_set_hash_mapping(struct xenvif *vif, u32 gref, u32 len,
 			    u32 off)
 {
-	u32 *mapping = &vif->hash.mapping[off];
-	struct gnttab_copy copy_op = {
+	u32 *mapping = vif->hash.mapping[!vif->hash.mapping_sel];
+	unsigned int nr = 1;
+	struct gnttab_copy copy_op[2] = {{
 		.source.u.ref = gref,
 		.source.domid = vif->domid,
-		.dest.u.gmfn = virt_to_gfn(mapping),
 		.dest.domid = DOMID_SELF,
-		.dest.offset = xen_offset_in_page(mapping),
-		.len = len * sizeof(u32),
+		.len = len * sizeof(*mapping),
 		.flags = GNTCOPY_source_gref
-	};
+	}};
 
-	if ((off + len > vif->hash.size) || copy_op.len > XEN_PAGE_SIZE)
+	if ((off + len < off) || (off + len > vif->hash.size) ||
+	    len > XEN_PAGE_SIZE / sizeof(*mapping))
 		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
 
-	while (len-- != 0)
-		if (mapping[off++] >= vif->num_queues)
-			return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+	copy_op[0].dest.u.gmfn = virt_to_gfn(mapping + off);
+	copy_op[0].dest.offset = xen_offset_in_page(mapping + off);
+	if (copy_op[0].dest.offset + copy_op[0].len > XEN_PAGE_SIZE) {
+		copy_op[1] = copy_op[0];
+		copy_op[1].source.offset = XEN_PAGE_SIZE - copy_op[0].dest.offset;
+		copy_op[1].dest.u.gmfn = virt_to_gfn(mapping + off + len);
+		copy_op[1].dest.offset = 0;
+		copy_op[1].len = copy_op[0].len - copy_op[1].source.offset;
+		copy_op[0].len = copy_op[1].source.offset;
+		nr = 2;
+	}
 
-	if (copy_op.len != 0) {
-		gnttab_batch_copy(&copy_op, 1);
+	memcpy(mapping, vif->hash.mapping[vif->hash.mapping_sel],
+	       vif->hash.size * sizeof(*mapping));
 
-		if (copy_op.status != GNTST_okay)
+	if (copy_op[0].len != 0) {
+		gnttab_batch_copy(copy_op, nr);
+
+		if (copy_op[0].status != GNTST_okay ||
+		    copy_op[nr - 1].status != GNTST_okay)
 			return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
 	}
 
+	while (len-- != 0)
+		if (mapping[off++] >= vif->num_queues)
+			return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+
+	vif->hash.mapping_sel = !vif->hash.mapping_sel;
+
 	return XEN_NETIF_CTRL_STATUS_SUCCESS;
 }
 
@@ -408,6 +427,8 @@ void xenvif_dump_hash_info(struct xenvif *vif, struct seq_file *m)
 	}
 
 	if (vif->hash.size != 0) {
+		const u32 *mapping = vif->hash.mapping[vif->hash.mapping_sel];
+
 		seq_puts(m, "\nHash Mapping:\n");
 
 		for (i = 0; i < vif->hash.size; ) {
@@ -420,7 +441,7 @@ void xenvif_dump_hash_info(struct xenvif *vif, struct seq_file *m)
 			seq_printf(m, "[%4u - %4u]: ", i, i + n - 1);
 
 			for (j = 0; j < n; j++, i++)
-				seq_printf(m, "%4u ", vif->hash.mapping[i]);
+				seq_printf(m, "%4u ", mapping[i]);
 
 			seq_puts(m, "\n");
 		}
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 92274c237200..f6ae23fc3f6b 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -162,7 +162,8 @@ static u16 xenvif_select_queue(struct net_device *dev, struct sk_buff *skb,
 	if (size == 0)
 		return skb_get_hash_raw(skb) % dev->real_num_tx_queues;
 
-	return vif->hash.mapping[skb_get_hash_raw(skb) % size];
+	return vif->hash.mapping[vif->hash.mapping_sel]
+				[skb_get_hash_raw(skb) % size];
 }
 
 static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)