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authorEyal Birger <eyal.birger@gmail.com>2020-11-21 08:28:17 +0200
committerJakub Kicinski <kuba@kernel.org>2020-11-23 17:29:36 -0800
commitd549699048b4b5c22dd710455bcdb76966e55aa3 (patch)
tree54881cbdf344f66ae28ee9e5106e419381bc199b /net/packet
parent2980cbd4dce7b1e9bf57df3ced43a7b184986f50 (diff)
net/packet: fix packet receive on L3 devices without visible hard header
In the patchset merged by commit b9fcf0a0d826 ("Merge branch 'support-AF_PACKET-for-layer-3-devices'") L3 devices which did not have header_ops were given one for the purpose of protocol parsing on af_packet transmit path. That change made af_packet receive path regard these devices as having a visible L3 header and therefore aligned incoming skb->data to point to the skb's mac_header. Some devices, such as ipip, xfrmi, and others, do not reset their mac_header prior to ingress and therefore their incoming packets became malformed. Ideally these devices would reset their mac headers, or af_packet would be able to rely on dev->hard_header_len being 0 for such cases, but it seems this is not the case. Fix by changing af_packet RX ll visibility criteria to include the existence of a '.create()' header operation, which is used when creating a device hard header - via dev_hard_header() - by upper layers, and does not exist in these L3 devices. As this predicate may be useful in other situations, add it as a common dev_has_header() helper in netdevice.h. Fixes: b9fcf0a0d826 ("Merge branch 'support-AF_PACKET-for-layer-3-devices'") Signed-off-by: Eyal Birger <eyal.birger@gmail.com> Acked-by: Jason A. Donenfeld <Jason@zx2c4.com> Acked-by: Willem de Bruijn <willemb@google.com> Link: https://lore.kernel.org/r/20201121062817.3178900-1-eyal.birger@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/packet')
-rw-r--r--net/packet/af_packet.c18
1 files changed, 9 insertions, 9 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index cefbd50c1090..7a18ffff8551 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -93,8 +93,8 @@
/*
Assumptions:
- - If the device has no dev->header_ops, there is no LL header visible
- above the device. In this case, its hard_header_len should be 0.
+ - If the device has no dev->header_ops->create, there is no LL header
+ visible above the device. In this case, its hard_header_len should be 0.
The device may prepend its own header internally. In this case, its
needed_headroom should be set to the space needed for it to add its
internal header.
@@ -108,26 +108,26 @@
On receive:
-----------
-Incoming, dev->header_ops != NULL
+Incoming, dev_has_header(dev) == true
mac_header -> ll header
data -> data
-Outgoing, dev->header_ops != NULL
+Outgoing, dev_has_header(dev) == true
mac_header -> ll header
data -> ll header
-Incoming, dev->header_ops == NULL
+Incoming, dev_has_header(dev) == false
mac_header -> data
However drivers often make it point to the ll header.
This is incorrect because the ll header should be invisible to us.
data -> data
-Outgoing, dev->header_ops == NULL
+Outgoing, dev_has_header(dev) == false
mac_header -> data. ll header is invisible to us.
data -> data
Resume
- If dev->header_ops == NULL we are unable to restore the ll header,
+ If dev_has_header(dev) == false we are unable to restore the ll header,
because it is invisible to us.
@@ -2069,7 +2069,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
skb->dev = dev;
- if (dev->header_ops) {
+ if (dev_has_header(dev)) {
/* The device has an explicit notion of ll header,
* exported to higher levels.
*
@@ -2198,7 +2198,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
if (!net_eq(dev_net(dev), sock_net(sk)))
goto drop;
- if (dev->header_ops) {
+ if (dev_has_header(dev)) {
if (sk->sk_type != SOCK_DGRAM)
skb_push(skb, skb->data - skb_mac_header(skb));
else if (skb->pkt_type == PACKET_OUTGOING) {