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author | Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> | 2018-03-13 14:51:27 +0900 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2018-03-16 10:03:47 -0400 |
commit | 4bbb3e0e8239f9079bf1fe20b3c0cb598714ae61 (patch) | |
tree | feebbc0ee91f6c1ff26d63ab7b593397858a8eb1 | |
parent | 51d4740f88affd85d49c04e3c9cd129c0e33bcb9 (diff) | |
download | linux-stable-4bbb3e0e8239f9079bf1fe20b3c0cb598714ae61.tar.gz linux-stable-4bbb3e0e8239f9079bf1fe20b3c0cb598714ae61.tar.bz2 linux-stable-4bbb3e0e8239f9079bf1fe20b3c0cb598714ae61.zip |
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>
-rw-r--r-- | include/uapi/linux/if_ether.h | 1 | ||||
-rw-r--r-- | net/core/skbuff.c | 7 |
2 files changed, 6 insertions, 2 deletions
diff --git a/include/uapi/linux/if_ether.h b/include/uapi/linux/if_ether.h index 8bbbcb5cd94b..820de5d222d2 100644 --- a/include/uapi/linux/if_ether.h +++ b/include/uapi/linux/if_ether.h @@ -30,6 +30,7 @@ */ #define ETH_ALEN 6 /* Octets in one ethernet addr */ +#define ETH_TLEN 2 /* Octets in ethernet type field */ #define ETH_HLEN 14 /* Total octets in header. */ #define ETH_ZLEN 60 /* Min. octets in frame sans FCS */ #define ETH_DATA_LEN 1500 /* Max. octets in payload */ 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; } |