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| author | Vladimir Oltean <vladimir.oltean@nxp.com> | 2023-04-21 01:56:01 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2023-04-23 16:16:45 +0300 |
| commit | 0bcf2e4aca6c29a07555b713f2fb461dc38d5977 (patch) | |
| tree | 5cbeb17571c9738e1bcd2f33c02989b8e4e9eb42 /net/core | |
| parent | f0a9d563064c3040a2d7b32317b37a6bcb1099b2 (diff) | |
| download | linux-0bcf2e4aca6c29a07555b713f2fb461dc38d5977.tar.xz | |
net: dsa: tag_ocelot: call only the relevant portion of __skb_vlan_pop() on TX
ocelot_xmit_get_vlan_info() calls __skb_vlan_pop() as the most
appropriate helper I could find which strips away a VLAN header.
That's all I need it to do, but __skb_vlan_pop() has more logic, which
will become incompatible with the future revert of commit 6d1ccff62780
("net: reset mac header in dev_start_xmit()").
Namely, it performs a sanity check on skb_mac_header(), which will stop
being set after the above revert, so it will return an error instead of
removing the VLAN tag.
ocelot_xmit_get_vlan_info() gets called in 2 circumstances:
(1) the port is under a VLAN-aware bridge and the bridge sends
VLAN-tagged packets
(2) the port is under a VLAN-aware bridge and somebody else (an 8021q
upper) sends VLAN-tagged packets (using a VID that isn't in the
bridge vlan tables)
In case (1), there is actually no bug to defend against, because
br_dev_xmit() calls skb_reset_mac_header() and things continue to work.
However, in case (2), illustrated using the commands below, it can be
seen that our intervention is needed, since __skb_vlan_pop() complains:
$ ip link add br0 type bridge vlan_filtering 1 && ip link set br0 up
$ ip link set $eth master br0 && ip link set $eth up
$ ip link add link $eth name $eth.100 type vlan id 100 && ip link set $eth.100 up
$ ip addr add 192.168.100.1/24 dev $eth.100
I could fend off the checks in __skb_vlan_pop() with some
skb_mac_header_was_set() calls, but seeing how few callers of
__skb_vlan_pop() there are from TX paths, that seems rather
unproductive.
As an alternative solution, extract the bare minimum logic to strip a
VLAN header, and move it to a new helper named vlan_remove_tag(), close
to the definition of vlan_insert_tag(). Document it appropriately and
make ocelot_xmit_get_vlan_info() call this smaller helper instead.
Seeing that it doesn't appear illegal to test skb->protocol in the TX
path, I guess it would be a good for vlan_remove_tag() to also absorb
the vlan_set_encap_proto() function call.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/skbuff.c | 8 |
1 files changed, 1 insertions, 7 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 304a966164d8..c7c141f6fc14 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5996,7 +5996,6 @@ EXPORT_SYMBOL(skb_ensure_writable); */ int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci) { - struct vlan_hdr *vhdr; int offset = skb->data - skb_mac_header(skb); int err; @@ -6012,13 +6011,8 @@ int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci) skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN); - vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN); - *vlan_tci = ntohs(vhdr->h_vlan_TCI); - - memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN); - __skb_pull(skb, VLAN_HLEN); + vlan_remove_tag(skb, vlan_tci); - vlan_set_encap_proto(skb, vhdr); skb->mac_header += VLAN_HLEN; if (skb_network_offset(skb) < ETH_HLEN) |