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authorJason Wang <jasowang@redhat.com>2012-05-02 07:42:15 +0400
committerMichael S. Tsirkin <mst@redhat.com>2012-05-02 19:22:21 +0400
commitb92946e2919134ebe2a4083e4302236295ea2a73 (patch)
tree46887b70dd309f7bdd358f32b47b0aee766788d3 /drivers/net/macvtap.c
parent01d6657b388438def19c8baaea28e742b6ed32ec (diff)
downloadlinux-b92946e2919134ebe2a4083e4302236295ea2a73.tar.xz
macvtap: zerocopy: validate vectors before building skb
There're several reasons that the vectors need to be validated: - Return error when caller provides vectors whose num is greater than UIO_MAXIOV. - Linearize part of skb when userspace provides vectors grater than MAX_SKB_FRAGS. - Return error when userspace provides vectors whose total length may exceed - MAX_SKB_FRAGS * PAGE_SIZE. Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/net/macvtap.c')
-rw-r--r--drivers/net/macvtap.c25
1 files changed, 21 insertions, 4 deletions
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index a4ff694cea22..163559c16988 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -529,9 +529,10 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
}
base = (unsigned long)from->iov_base + offset;
size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
+ if (i + size > MAX_SKB_FRAGS)
+ return -EMSGSIZE;
num_pages = get_user_pages_fast(base, size, 0, &page[i]);
- if ((num_pages != size) ||
- (num_pages > MAX_SKB_FRAGS - skb_shinfo(skb)->nr_frags)) {
+ if (num_pages != size) {
for (i = 0; i < num_pages; i++)
put_page(page[i]);
return -EFAULT;
@@ -651,7 +652,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
int err;
struct virtio_net_hdr vnet_hdr = { 0 };
int vnet_hdr_len = 0;
- int copylen;
+ int copylen = 0;
bool zerocopy = false;
if (q->flags & IFF_VNET_HDR) {
@@ -680,15 +681,31 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
if (unlikely(len < ETH_HLEN))
goto err;
+ err = -EMSGSIZE;
+ if (unlikely(count > UIO_MAXIOV))
+ goto err;
+
if (m && m->msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY))
zerocopy = true;
if (zerocopy) {
+ /* Userspace may produce vectors with count greater than
+ * MAX_SKB_FRAGS, so we need to linearize parts of the skb
+ * to let the rest of data to be fit in the frags.
+ */
+ if (count > MAX_SKB_FRAGS) {
+ copylen = iov_length(iv, count - MAX_SKB_FRAGS);
+ if (copylen < vnet_hdr_len)
+ copylen = 0;
+ else
+ copylen -= vnet_hdr_len;
+ }
/* There are 256 bytes to be copied in skb, so there is enough
* room for skb expand head in case it is used.
* The rest buffer is mapped from userspace.
*/
- copylen = vnet_hdr.hdr_len;
+ if (copylen < vnet_hdr.hdr_len)
+ copylen = vnet_hdr.hdr_len;
if (!copylen)
copylen = GOODCOPY_LEN;
} else