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authorToshiaki Makita <makita.toshiaki@lab.ntt.co.jp>2018-03-13 08:51:27 +0300
committerDavid S. Miller <davem@davemloft.net>2018-03-16 17:03:47 +0300
commit4bbb3e0e8239f9079bf1fe20b3c0cb598714ae61 (patch)
treefeebbc0ee91f6c1ff26d63ab7b593397858a8eb1 /net
parent51d4740f88affd85d49c04e3c9cd129c0e33bcb9 (diff)
downloadlinux-4bbb3e0e8239f9079bf1fe20b3c0cb598714ae61.tar.xz
net: Fix vlan untag for bridge and vlan_dev with reorder_hdr off
When we have a bridge with vlan_filtering on and a vlan device on top of it, packets would be corrupted in skb_vlan_untag() called from br_dev_xmit(). The problem sits in skb_reorder_vlan_header() used in skb_vlan_untag(), which makes use of skb->mac_len. In this function mac_len is meant for handling rx path with vlan devices with reorder_header disabled, but in tx path mac_len is typically 0 and cannot be used, which is the problem in this case. The current code even does not properly handle rx path (skb_vlan_untag() called from __netif_receive_skb_core()) with reorder_header off actually. In rx path single tag case, it works as follows: - Before skb_reorder_vlan_header() mac_header data v v +-------------------+-------------+------+---- | ETH | VLAN | ETH | | ADDRS | TPID | TCI | TYPE | +-------------------+-------------+------+---- <-------- mac_len ---------> <-------------> to be removed - After skb_reorder_vlan_header() mac_header data v v +-------------------+------+---- | ETH | ETH | | ADDRS | TYPE | +-------------------+------+---- <-------- mac_len ---------> This is ok, but in rx double tag case, it corrupts packets: - Before skb_reorder_vlan_header() mac_header data v v +-------------------+-------------+-------------+------+---- | ETH | VLAN | VLAN | ETH | | ADDRS | TPID | TCI | TPID | TCI | TYPE | +-------------------+-------------+-------------+------+---- <--------------- mac_len ----------------> <-------------> should be removed <---------------------------> actually will be removed - After skb_reorder_vlan_header() mac_header data v v +-------------------+------+---- | ETH | ETH | | ADDRS | TYPE | +-------------------+------+---- <--------------- mac_len ----------------> So, two of vlan tags are both removed while only inner one should be removed and mac_header (and mac_len) is broken. skb_vlan_untag() is meant for removing the vlan header at (skb->data - 2), so use skb->data and skb->mac_header to calculate the right offset. Reported-by: Brandon Carpenter <brandon.carpenter@cypherpath.com> Fixes: a6e18ff11170 ("vlan: Fix untag operations of stacked vlans with REORDER_HEADER off") Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/skbuff.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index baf990528943..b103f46ec512 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5020,13 +5020,16 @@ EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len);
static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
{
+ int mac_len;
+
if (skb_cow(skb, skb_headroom(skb)) < 0) {
kfree_skb(skb);
return NULL;
}
- memmove(skb->data - ETH_HLEN, skb->data - skb->mac_len - VLAN_HLEN,
- 2 * ETH_ALEN);
+ mac_len = skb->data - skb_mac_header(skb);
+ memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb),
+ mac_len - VLAN_HLEN - ETH_TLEN);
skb->mac_header += VLAN_HLEN;
return skb;
}