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Message-Id: <20210513100302.22027-7-jgross@suse.com>
Date: Thu, 13 May 2021 12:03:00 +0200
From: Juergen Gross <jgross@...e.com>
To: xen-devel@...ts.xenproject.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Juergen Gross <jgross@...e.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Stefano Stabellini <sstabellini@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH 6/8] xen/netfront: don't read data from request on the ring page
In order to avoid a malicious backend being able to influence the local
processing of a request build the request locally first and then copy
it to the ring page. Any reading from the request needs to be done on
the local instance.
Signed-off-by: Juergen Gross <jgross@...e.com>
---
drivers/net/xen-netfront.c | 75 ++++++++++++++++++--------------------
1 file changed, 36 insertions(+), 39 deletions(-)
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index f91e41ece554..261c35be0147 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -435,7 +435,8 @@ struct xennet_gnttab_make_txreq {
struct netfront_queue *queue;
struct sk_buff *skb;
struct page *page;
- struct xen_netif_tx_request *tx; /* Last request */
+ struct xen_netif_tx_request *tx; /* Last request on ring page */
+ struct xen_netif_tx_request tx_local; /* Last request local copy*/
unsigned int size;
};
@@ -463,30 +464,27 @@ static void xennet_tx_setup_grant(unsigned long gfn, unsigned int offset,
queue->grant_tx_page[id] = page;
queue->grant_tx_ref[id] = ref;
- tx->id = id;
- tx->gref = ref;
- tx->offset = offset;
- tx->size = len;
- tx->flags = 0;
+ info->tx_local.id = id;
+ info->tx_local.gref = ref;
+ info->tx_local.offset = offset;
+ info->tx_local.size = len;
+ info->tx_local.flags = 0;
+
+ *tx = info->tx_local;
info->tx = tx;
- info->size += tx->size;
+ info->size += info->tx_local.size;
}
static struct xen_netif_tx_request *xennet_make_first_txreq(
- struct netfront_queue *queue, struct sk_buff *skb,
- struct page *page, unsigned int offset, unsigned int len)
+ struct xennet_gnttab_make_txreq *info,
+ unsigned int offset, unsigned int len)
{
- struct xennet_gnttab_make_txreq info = {
- .queue = queue,
- .skb = skb,
- .page = page,
- .size = 0,
- };
+ info->size = 0;
- gnttab_for_one_grant(page, offset, len, xennet_tx_setup_grant, &info);
+ gnttab_for_one_grant(info->page, offset, len, xennet_tx_setup_grant, info);
- return info.tx;
+ return info->tx;
}
static void xennet_make_one_txreq(unsigned long gfn, unsigned int offset,
@@ -499,35 +497,27 @@ static void xennet_make_one_txreq(unsigned long gfn, unsigned int offset,
xennet_tx_setup_grant(gfn, offset, len, data);
}
-static struct xen_netif_tx_request *xennet_make_txreqs(
- struct netfront_queue *queue, struct xen_netif_tx_request *tx,
- struct sk_buff *skb, struct page *page,
+static void xennet_make_txreqs(
+ struct xennet_gnttab_make_txreq *info,
+ struct page *page,
unsigned int offset, unsigned int len)
{
- struct xennet_gnttab_make_txreq info = {
- .queue = queue,
- .skb = skb,
- .tx = tx,
- };
-
/* Skip unused frames from start of page */
page += offset >> PAGE_SHIFT;
offset &= ~PAGE_MASK;
while (len) {
- info.page = page;
- info.size = 0;
+ info->page = page;
+ info->size = 0;
gnttab_foreach_grant_in_range(page, offset, len,
xennet_make_one_txreq,
- &info);
+ info);
page++;
offset = 0;
- len -= info.size;
+ len -= info->size;
}
-
- return info.tx;
}
/*
@@ -580,10 +570,14 @@ static int xennet_xdp_xmit_one(struct net_device *dev,
{
struct netfront_info *np = netdev_priv(dev);
struct netfront_stats *tx_stats = this_cpu_ptr(np->tx_stats);
+ struct xennet_gnttab_make_txreq info = {
+ .queue = queue,
+ .skb = NULL,
+ .page = virt_to_page(xdpf->data),
+ };
int notify;
- xennet_make_first_txreq(queue, NULL,
- virt_to_page(xdpf->data),
+ xennet_make_first_txreq(&info,
offset_in_page(xdpf->data),
xdpf->len);
@@ -647,6 +641,7 @@ static netdev_tx_t xennet_start_xmit(struct sk_buff *skb, struct net_device *dev
unsigned int len;
unsigned long flags;
struct netfront_queue *queue = NULL;
+ struct xennet_gnttab_make_txreq info = { };
unsigned int num_queues = dev->real_num_tx_queues;
u16 queue_index;
struct sk_buff *nskb;
@@ -704,14 +699,16 @@ static netdev_tx_t xennet_start_xmit(struct sk_buff *skb, struct net_device *dev
}
/* First request for the linear area. */
- first_tx = tx = xennet_make_first_txreq(queue, skb,
- page, offset, len);
+ info.queue = queue;
+ info.skb = skb;
+ info.page = page;
+ first_tx = tx = xennet_make_first_txreq(&info, offset, len);
offset += tx->size;
if (offset == PAGE_SIZE) {
page++;
offset = 0;
}
- len -= tx->size;
+ len -= info.tx_local.size;
if (skb->ip_summed == CHECKSUM_PARTIAL)
/* local packet? */
@@ -741,12 +738,12 @@ static netdev_tx_t xennet_start_xmit(struct sk_buff *skb, struct net_device *dev
}
/* Requests for the rest of the linear area. */
- tx = xennet_make_txreqs(queue, tx, skb, page, offset, len);
+ xennet_make_txreqs(&info, page, offset, len);
/* Requests for all the frags. */
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
- tx = xennet_make_txreqs(queue, tx, skb, skb_frag_page(frag),
+ xennet_make_txreqs(&info, skb_frag_page(frag),
skb_frag_off(frag),
skb_frag_size(frag));
}
--
2.26.2
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