packet: validate variable length ll headers
Replace link layer header validation check ll_header_truncate with
more generic dev_validate_header.
Validation based on hard_header_len incorrectly drops valid packets
in variable length protocols, such as AX25. dev_validate_header
calls header_ops.validate for such protocols to ensure correctness
below hard_header_len.
See also http://comments.gmane.org/gmane.linux.network/401064
Fixes 9c7077622dd9 ("packet: make packet_snd fail on len smaller than l2 header")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d41b107..1ecfa71 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1915,6 +1915,10 @@
goto retry;
}
+ if (!dev_validate_header(dev, skb->data, len)) {
+ err = -EINVAL;
+ goto out_unlock;
+ }
if (len > (dev->mtu + dev->hard_header_len + extra_len) &&
!packet_extra_vlan_len_allowed(dev, skb)) {
err = -EMSGSIZE;
@@ -2393,18 +2397,6 @@
sock_wfree(skb);
}
-static bool ll_header_truncated(const struct net_device *dev, int len)
-{
- /* net device doesn't like empty head */
- if (unlikely(len < dev->hard_header_len)) {
- net_warn_ratelimited("%s: packet size is too short (%d < %d)\n",
- current->comm, len, dev->hard_header_len);
- return true;
- }
-
- return false;
-}
-
static void tpacket_set_protocol(const struct net_device *dev,
struct sk_buff *skb)
{
@@ -2522,16 +2514,20 @@
if (unlikely(err < 0))
return -EINVAL;
} else if (copylen) {
+ int hdrlen = min_t(int, copylen, tp_len);
+
skb_push(skb, dev->hard_header_len);
skb_put(skb, copylen - dev->hard_header_len);
- err = skb_store_bits(skb, 0, data, copylen);
+ err = skb_store_bits(skb, 0, data, hdrlen);
if (unlikely(err))
return err;
+ if (!dev_validate_header(dev, skb->data, hdrlen))
+ return -EINVAL;
if (!skb->protocol)
tpacket_set_protocol(dev, skb);
- data += copylen;
- to_write -= copylen;
+ data += hdrlen;
+ to_write -= hdrlen;
}
offset = offset_in_page(data);
@@ -2703,13 +2699,7 @@
copylen = __virtio16_to_cpu(vio_le(),
vnet_hdr->hdr_len);
}
- if (dev->hard_header_len) {
- if (ll_header_truncated(dev, tp_len)) {
- tp_len = -EINVAL;
- goto tpacket_error;
- }
- copylen = max_t(int, copylen, dev->hard_header_len);
- }
+ copylen = max_t(int, copylen, dev->hard_header_len);
skb = sock_alloc_send_skb(&po->sk,
hlen + tlen + sizeof(struct sockaddr_ll) +
(copylen - dev->hard_header_len),
@@ -2905,9 +2895,6 @@
offset = dev_hard_header(skb, dev, ntohs(proto), addr, NULL, len);
if (unlikely(offset < 0))
goto out_free;
- } else {
- if (ll_header_truncated(dev, len))
- goto out_free;
}
/* Returns -EFAULT on error */
@@ -2915,6 +2902,12 @@
if (err)
goto out_free;
+ if (sock->type == SOCK_RAW &&
+ !dev_validate_header(dev, skb->data, len)) {
+ err = -EINVAL;
+ goto out_free;
+ }
+
sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
if (!vnet_hdr.gso_type && (len > dev->mtu + reserve + extra_len) &&
